bcache: A block layer cache

Does writethrough and writeback caching, handles unclean shutdown, and
has a bunch of other nifty features motivated by real world usage.

See the wiki at http://bcache.evilpiepirate.org for more.

Signed-off-by: Kent Overstreet <koverstreet@google.com>

Documentation/ABI/testing/sysfs-block-bcache

@@ -0,0 +1,156 @@
+What:		/sys/block/<disk>/bcache/unregister
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		A write to this file causes the backing device or cache to be
+		unregistered. If a backing device had dirty data in the cache,
+		writeback mode is automatically disabled and all dirty data is
+		flushed before the device is unregistered. Caches unregister
+		all associated backing devices before unregistering themselves.
+
+What:		/sys/block/<disk>/bcache/clear_stats
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		Writing to this file resets all the statistics for the device.
+
+What:		/sys/block/<disk>/bcache/cache
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For a backing device that has cache, a symlink to
+		the bcache/ dir of that cache.
+
+What:		/sys/block/<disk>/bcache/cache_hits
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For backing devices: integer number of full cache hits,
+		counted per bio. A partial cache hit counts as a miss.
+
+What:		/sys/block/<disk>/bcache/cache_misses
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For backing devices: integer number of cache misses.
+
+What:		/sys/block/<disk>/bcache/cache_hit_ratio
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For backing devices: cache hits as a percentage.
+
+What:		/sys/block/<disk>/bcache/sequential_cutoff
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For backing devices: Threshold past which sequential IO will
+		skip the cache. Read and written as bytes in human readable
+		units (i.e. echo 10M > sequntial_cutoff).
+
+What:		/sys/block/<disk>/bcache/bypassed
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		Sum of all reads and writes that have bypassed the cache (due
+		to the sequential cutoff).  Expressed as bytes in human
+		readable units.
+
+What:		/sys/block/<disk>/bcache/writeback
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For backing devices: When on, writeback caching is enabled and
+		writes will be buffered in the cache. When off, caching is in
+		writethrough mode; reads and writes will be added to the
+		cache but no write buffering will take place.
+
+What:		/sys/block/<disk>/bcache/writeback_running
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For backing devices: when off, dirty data will not be written
+		from the cache to the backing device. The cache will still be
+		used to buffer writes until it is mostly full, at which point
+		writes transparently revert to writethrough mode. Intended only
+		for benchmarking/testing.
+
+What:		/sys/block/<disk>/bcache/writeback_delay
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For backing devices: In writeback mode, when dirty data is
+		written to the cache and the cache held no dirty data for that
+		backing device, writeback from cache to backing device starts
+		after this delay, expressed as an integer number of seconds.
+
+What:		/sys/block/<disk>/bcache/writeback_percent
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For backing devices: If nonzero, writeback from cache to
+		backing device only takes place when more than this percentage
+		of the cache is used, allowing more write coalescing to take
+		place and reducing total number of writes sent to the backing
+		device. Integer between 0 and 40.
+
+What:		/sys/block/<disk>/bcache/synchronous
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For a cache, a boolean that allows synchronous mode to be
+		switched on and off. In synchronous mode all writes are ordered
+		such that the cache can reliably recover from unclean shutdown;
+		if disabled bcache will not generally wait for writes to
+		complete but if the cache is not shut down cleanly all data
+		will be discarded from the cache. Should not be turned off with
+		writeback caching enabled.
+
+What:		/sys/block/<disk>/bcache/discard
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For a cache, a boolean allowing discard/TRIM to be turned off
+		or back on if the device supports it.
+
+What:		/sys/block/<disk>/bcache/bucket_size
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For a cache, bucket size in human readable units, as set at
+		cache creation time; should match the erase block size of the
+		SSD for optimal performance.
+
+What:		/sys/block/<disk>/bcache/nbuckets
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For a cache, the number of usable buckets.
+
+What:		/sys/block/<disk>/bcache/tree_depth
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For a cache, height of the btree excluding leaf nodes (i.e. a
+		one node tree will have a depth of 0).
+
+What:		/sys/block/<disk>/bcache/btree_cache_size
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		Number of btree buckets/nodes that are currently cached in
+		memory; cache dynamically grows and shrinks in response to
+		memory pressure from the rest of the system.
+
+What:		/sys/block/<disk>/bcache/written
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For a cache, total amount of data in human readable units
+		written to the cache, excluding all metadata.
+
+What:		/sys/block/<disk>/bcache/btree_written
+Date:		November 2010
+Contact:	Kent Overstreet <kent.overstreet@gmail.com>
+Description:
+		For a cache, sum of all btree writes in human readable units.

Documentation/bcache.txt

@@ -0,0 +1,343 @@
+Say you've got a big slow raid 6, and an X-25E or three. Wouldn't it be
+nice if you could use them as cache... Hence bcache.
+
+Wiki and git repositories are at:
+  http://bcache.evilpiepirate.org
+  http://evilpiepirate.org/git/linux-bcache.git
+  http://evilpiepirate.org/git/bcache-tools.git
+
+It's designed around the performance characteristics of SSDs - it only allocates
+in erase block sized buckets, and it uses a hybrid btree/log to track cached
+extants (which can be anywhere from a single sector to the bucket size). It's
+designed to avoid random writes at all costs; it fills up an erase block
+sequentially, then issues a discard before reusing it.
+
+Both writethrough and writeback caching are supported. Writeback defaults to
+off, but can be switched on and off arbitrarily at runtime. Bcache goes to
+great lengths to protect your data - it reliably handles unclean shutdown. (It
+doesn't even have a notion of a clean shutdown; bcache simply doesn't return
+writes as completed until they're on stable storage).
+
+Writeback caching can use most of the cache for buffering writes - writing
+dirty data to the backing device is always done sequentially, scanning from the
+start to the end of the index.
+
+Since random IO is what SSDs excel at, there generally won't be much benefit
+to caching large sequential IO. Bcache detects sequential IO and skips it;
+it also keeps a rolling average of the IO sizes per task, and as long as the
+average is above the cutoff it will skip all IO from that task - instead of
+caching the first 512k after every seek. Backups and large file copies should
+thus entirely bypass the cache.
+
+In the event of a data IO error on the flash it will try to recover by reading
+from disk or invalidating cache entries.  For unrecoverable errors (meta data
+or dirty data), caching is automatically disabled; if dirty data was present
+in the cache it first disables writeback caching and waits for all dirty data
+to be flushed.
+
+Getting started:
+You'll need make-bcache from the bcache-tools repository. Both the cache device
+and backing device must be formatted before use.
+  make-bcache -B /dev/sdb
+  make-bcache -C /dev/sdc
+
+make-bcache has the ability to format multiple devices at the same time - if
+you format your backing devices and cache device at the same time, you won't
+have to manually attach:
+  make-bcache -B /dev/sda /dev/sdb -C /dev/sdc
+
+To make bcache devices known to the kernel, echo them to /sys/fs/bcache/register:
+
+  echo /dev/sdb > /sys/fs/bcache/register
+  echo /dev/sdc > /sys/fs/bcache/register
+
+To register your bcache devices automatically, you could add something like
+this to an init script:
+
+  echo /dev/sd* > /sys/fs/bcache/register_quiet
+
+It'll look for bcache superblocks and ignore everything that doesn't have one.
+
+Registering the backing device makes the bcache show up in /dev; you can now
+format it and use it as normal. But the first time using a new bcache device,
+it'll be running in passthrough mode until you attach it to a cache. See the
+section on attaching.
+
+The devices show up at /dev/bcacheN, and can be controlled via sysfs from
+/sys/block/bcacheN/bcache:
+
+  mkfs.ext4 /dev/bcache0
+  mount /dev/bcache0 /mnt
+
+Cache devices are managed as sets; multiple caches per set isn't supported yet
+but will allow for mirroring of metadata and dirty data in the future. Your new
+cache set shows up as /sys/fs/bcache/<UUID>
+
+ATTACHING:
+
+After your cache device and backing device are registered, the backing device
+must be attached to your cache set to enable caching. Attaching a backing
+device to a cache set is done thusly, with the UUID of the cache set in
+/sys/fs/bcache:
+
+  echo <UUID> > /sys/block/bcache0/bcache/attach
+
+This only has to be done once. The next time you reboot, just reregister all
+your bcache devices. If a backing device has data in a cache somewhere, the
+/dev/bcache# device won't be created until the cache shows up - particularly
+important if you have writeback caching turned on.
+
+If you're booting up and your cache device is gone and never coming back, you
+can force run the backing device:
+
+  echo 1 > /sys/block/sdb/bcache/running
+
+(You need to use /sys/block/sdb (or whatever your backing device is called), not
+/sys/block/bcache0, because bcache0 doesn't exist yet. If you're using a
+partition, the bcache directory would be at /sys/block/sdb/sdb2/bcache)
+
+The backing device will still use that cache set if it shows up in the future,
+but all the cached data will be invalidated. If there was dirty data in the
+cache, don't expect the filesystem to be recoverable - you will have massive
+filesystem corruption, though ext4's fsck does work miracles.
+
+SYSFS - BACKING DEVICE:
+
+attach
+  Echo the UUID of a cache set to this file to enable caching.
+
+cache_mode
+  Can be one of either writethrough, writeback, writearound or none.
+
+clear_stats
+  Writing to this file resets the running total stats (not the day/hour/5 minute
+  decaying versions).
+
+detach
+  Write to this file to detach from a cache set. If there is dirty data in the
+  cache, it will be flushed first.
+
+dirty_data
+  Amount of dirty data for this backing device in the cache. Continuously
+  updated unlike the cache set's version, but may be slightly off.
+
+label
+  Name of underlying device.
+
+readahead
+  Size of readahead that should be performed.  Defaults to 0.  If set to e.g.
+  1M, it will round cache miss reads up to that size, but without overlapping
+  existing cache entries.
+
+running
+  1 if bcache is running (i.e. whether the /dev/bcache device exists, whether
+  it's in passthrough mode or caching).
+
+sequential_cutoff
+  A sequential IO will bypass the cache once it passes this threshhold; the
+  most recent 128 IOs are tracked so sequential IO can be detected even when
+  it isn't all done at once.
+
+sequential_merge
+  If non zero, bcache keeps a list of the last 128 requests submitted to compare
+  against all new requests to determine which new requests are sequential
+  continuations of previous requests for the purpose of determining sequential
+  cutoff. This is necessary if the sequential cutoff value is greater than the
+  maximum acceptable sequential size for any single request. 
+
+state
+  The backing device can be in one of four different states:
+
+  no cache: Has never been attached to a cache set.
+
+  clean: Part of a cache set, and there is no cached dirty data.
+
+  dirty: Part of a cache set, and there is cached dirty data.
+
+  inconsistent: The backing device was forcibly run by the user when there was
+  dirty data cached but the cache set was unavailable; whatever data was on the
+  backing device has likely been corrupted.
+
+stop
+  Write to this file to shut down the bcache device and close the backing
+  device.
+
+writeback_delay
+  When dirty data is written to the cache and it previously did not contain
+  any, waits some number of seconds before initiating writeback. Defaults to
+  30.
+
+writeback_percent
+  If nonzero, bcache tries to keep around this percentage of the cache dirty by
+  throttling background writeback and using a PD controller to smoothly adjust
+  the rate.
+
+writeback_rate
+  Rate in sectors per second - if writeback_percent is nonzero, background
+  writeback is throttled to this rate. Continuously adjusted by bcache but may
+  also be set by the user.
+
+writeback_running
+  If off, writeback of dirty data will not take place at all. Dirty data will
+  still be added to the cache until it is mostly full; only meant for
+  benchmarking. Defaults to on.
+
+SYSFS - BACKING DEVICE STATS:
+
+There are directories with these numbers for a running total, as well as
+versions that decay over the past day, hour and 5 minutes; they're also
+aggregated in the cache set directory as well.
+
+bypassed
+  Amount of IO (both reads and writes) that has bypassed the cache
+
+cache_hits
+cache_misses
+cache_hit_ratio
+  Hits and misses are counted per individual IO as bcache sees them; a
+  partial hit is counted as a miss.
+
+cache_bypass_hits
+cache_bypass_misses
+  Hits and misses for IO that is intended to skip the cache are still counted,
+  but broken out here.
+
+cache_miss_collisions
+  Counts instances where data was going to be inserted into the cache from a
+  cache miss, but raced with a write and data was already present (usually 0
+  since the synchronization for cache misses was rewritten)
+
+cache_readaheads
+  Count of times readahead occured.
+
+SYSFS - CACHE SET:
+
+average_key_size
+  Average data per key in the btree.
+
+bdev<0..n>
+  Symlink to each of the attached backing devices.
+
+block_size
+  Block size of the cache devices.
+
+btree_cache_size
+  Amount of memory currently used by the btree cache
+
+bucket_size
+  Size of buckets
+
+cache<0..n>
+  Symlink to each of the cache devices comprising this cache set. 
+
+cache_available_percent
+  Percentage of cache device free.
+
+clear_stats
+  Clears the statistics associated with this cache
+
+dirty_data
+  Amount of dirty data is in the cache (updated when garbage collection runs).
+
+flash_vol_create
+  Echoing a size to this file (in human readable units, k/M/G) creates a thinly
+  provisioned volume backed by the cache set.
+
+io_error_halflife
+io_error_limit
+  These determines how many errors we accept before disabling the cache.
+  Each error is decayed by the half life (in # ios).  If the decaying count
+  reaches io_error_limit dirty data is written out and the cache is disabled.
+
+journal_delay_ms
+  Journal writes will delay for up to this many milliseconds, unless a cache
+  flush happens sooner. Defaults to 100.
+
+root_usage_percent
+  Percentage of the root btree node in use.  If this gets too high the node
+  will split, increasing the tree depth.
+
+stop
+  Write to this file to shut down the cache set - waits until all attached
+  backing devices have been shut down.
+
+tree_depth
+  Depth of the btree (A single node btree has depth 0).
+
+unregister
+  Detaches all backing devices and closes the cache devices; if dirty data is
+  present it will disable writeback caching and wait for it to be flushed.
+
+SYSFS - CACHE SET INTERNAL:
+
+This directory also exposes timings for a number of internal operations, with
+separate files for average duration, average frequency, last occurence and max
+duration: garbage collection, btree read, btree node sorts and btree splits.
+
+active_journal_entries
+  Number of journal entries that are newer than the index.
+
+btree_nodes
+  Total nodes in the btree.
+
+btree_used_percent
+  Average fraction of btree in use.
+
+bset_tree_stats
+  Statistics about the auxiliary search trees
+
+btree_cache_max_chain
+  Longest chain in the btree node cache's hash table
+
+cache_read_races
+  Counts instances where while data was being read from the cache, the bucket
+  was reused and invalidated - i.e. where the pointer was stale after the read
+  completed. When this occurs the data is reread from the backing device.
+
+trigger_gc
+  Writing to this file forces garbage collection to run.
+
+SYSFS - CACHE DEVICE:
+
+block_size
+  Minimum granularity of writes - should match hardware sector size.
+
+btree_written
+  Sum of all btree writes, in (kilo/mega/giga) bytes
+
+bucket_size
+  Size of buckets
+
+cache_replacement_policy
+  One of either lru, fifo or random.
+
+discard
+  Boolean; if on a discard/TRIM will be issued to each bucket before it is
+  reused. Defaults to off, since SATA TRIM is an unqueued command (and thus
+  slow).
+
+freelist_percent
+  Size of the freelist as a percentage of nbuckets. Can be written to to
+  increase the number of buckets kept on the freelist, which lets you
+  artificially reduce the size of the cache at runtime. Mostly for testing
+  purposes (i.e. testing how different size caches affect your hit rate), but
+  since buckets are discarded when they move on to the freelist will also make
+  the SSD's garbage collection easier by effectively giving it more reserved
+  space.
+
+io_errors
+  Number of errors that have occured, decayed by io_error_halflife.
+
+metadata_written
+  Sum of all non data writes (btree writes and all other metadata).
+
+nbuckets
+  Total buckets in this cache
+
+priority_stats
+  Statistics about how recently data in the cache has been accessed.  This can
+  reveal your working set size.
+
+written
+  Sum of all data that has been written to the cache; comparison with
+  btree_written gives the amount of write inflation in bcache.

MAINTAINERS

@@ -1616,6 +1616,13 @@ W:	http://www.baycom.org/~tom/ham/ham.html
 S:	Maintained
 F:	drivers/net/hamradio/baycom*
 
+BCACHE (BLOCK LAYER CACHE)
+M:	Kent Overstreet <koverstreet@google.com>
+L:	linux-bcache@vger.kernel.org
+W:	http://bcache.evilpiepirate.org
+S:	Maintained:
+F:	drivers/md/bcache/
+
 BEFS FILE SYSTEM
 S:	Orphan
 F:	Documentation/filesystems/befs.txt

drivers/md/Kconfig

@@ -174,6 +174,8 @@ config MD_FAULTY
 
 	  In unsure, say N.
 
+source "drivers/md/bcache/Kconfig"
+
 config BLK_DEV_DM
 	tristate "Device mapper support"
 	---help---

drivers/md/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_MD_RAID10)		+= raid10.o
 obj-$(CONFIG_MD_RAID456)	+= raid456.o
 obj-$(CONFIG_MD_MULTIPATH)	+= multipath.o
 obj-$(CONFIG_MD_FAULTY)		+= faulty.o
+obj-$(CONFIG_BCACHE)		+= bcache/
 obj-$(CONFIG_BLK_DEV_MD)	+= md-mod.o
 obj-$(CONFIG_BLK_DEV_DM)	+= dm-mod.o
 obj-$(CONFIG_DM_BUFIO)		+= dm-bufio.o

drivers/md/bcache/Kconfig

@@ -0,0 +1,42 @@
+
+config BCACHE
+	tristate "Block device as cache"
+	select CLOSURES
+	---help---
+	Allows a block device to be used as cache for other devices; uses
+	a btree for indexing and the layout is optimized for SSDs.
+
+	See Documentation/bcache.txt for details.
+
+config BCACHE_DEBUG
+	bool "Bcache debugging"
+	depends on BCACHE
+	---help---
+	Don't select this option unless you're a developer
+
+	Enables extra debugging tools (primarily a fuzz tester)
+
+config BCACHE_EDEBUG
+	bool "Extended runtime checks"
+	depends on BCACHE
+	---help---
+	Don't select this option unless you're a developer
+
+	Enables extra runtime checks which significantly affect performance
+
+config BCACHE_CLOSURES_DEBUG
+	bool "Debug closures"
+	depends on BCACHE
+	select DEBUG_FS
+	---help---
+	Keeps all active closures in a linked list and provides a debugfs
+	interface to list them, which makes it possible to see asynchronous
+	operations that get stuck.
+
+# cgroup code needs to be updated:
+#
+#config CGROUP_BCACHE
+#	bool "Cgroup controls for bcache"
+#	depends on BCACHE && BLK_CGROUP
+#	---help---
+#	TODO

drivers/md/bcache/Makefile

@@ -0,0 +1,7 @@
+
+obj-$(CONFIG_BCACHE)	+= bcache.o
+
+bcache-y		:= alloc.o btree.o bset.o io.o journal.o writeback.o\
+	movinggc.o request.o super.o sysfs.o debug.o util.o trace.o stats.o closure.o
+
+CFLAGS_request.o	+= -Iblock

drivers/md/bcache/alloc.c

@@ -0,0 +1,583 @@
+/*
+ * Primary bucket allocation code
+ *
+ * Copyright 2012 Google, Inc.
+ *
+ * Allocation in bcache is done in terms of buckets:
+ *
+ * Each bucket has associated an 8 bit gen; this gen corresponds to the gen in
+ * btree pointers - they must match for the pointer to be considered valid.
+ *
+ * Thus (assuming a bucket has no dirty data or metadata in it) we can reuse a
+ * bucket simply by incrementing its gen.
+ *
+ * The gens (along with the priorities; it's really the gens are important but
+ * the code is named as if it's the priorities) are written in an arbitrary list
+ * of buckets on disk, with a pointer to them in the journal header.
+ *
+ * When we invalidate a bucket, we have to write its new gen to disk and wait
+ * for that write to complete before we use it - otherwise after a crash we
+ * could have pointers that appeared to be good but pointed to data that had
+ * been overwritten.
+ *
+ * Since the gens and priorities are all stored contiguously on disk, we can
+ * batch this up: We fill up the free_inc list with freshly invalidated buckets,
+ * call prio_write(), and when prio_write() finishes we pull buckets off the
+ * free_inc list and optionally discard them.
+ *
+ * free_inc isn't the only freelist - if it was, we'd often to sleep while
+ * priorities and gens were being written before we could allocate. c->free is a
+ * smaller freelist, and buckets on that list are always ready to be used.
+ *
+ * If we've got discards enabled, that happens when a bucket moves from the
+ * free_inc list to the free list.
+ *
+ * There is another freelist, because sometimes we have buckets that we know
+ * have nothing pointing into them - these we can reuse without waiting for
+ * priorities to be rewritten. These come from freed btree nodes and buckets
+ * that garbage collection discovered no longer had valid keys pointing into
+ * them (because they were overwritten). That's the unused list - buckets on the
+ * unused list move to the free list, optionally being discarded in the process.
+ *
+ * It's also important to ensure that gens don't wrap around - with respect to
+ * either the oldest gen in the btree or the gen on disk. This is quite
+ * difficult to do in practice, but we explicitly guard against it anyways - if
+ * a bucket is in danger of wrapping around we simply skip invalidating it that
+ * time around, and we garbage collect or rewrite the priorities sooner than we
+ * would have otherwise.
+ *
+ * bch_bucket_alloc() allocates a single bucket from a specific cache.
+ *
+ * bch_bucket_alloc_set() allocates one or more buckets from different caches
+ * out of a cache set.
+ *
+ * free_some_buckets() drives all the processes described above. It's called
+ * from bch_bucket_alloc() and a few other places that need to make sure free
+ * buckets are ready.
+ *
+ * invalidate_buckets_(lru|fifo)() find buckets that are available to be
+ * invalidated, and then invalidate them and stick them on the free_inc list -
+ * in either lru or fifo order.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+
+#include <linux/random.h>
+
+#define MAX_IN_FLIGHT_DISCARDS		8U
+
+/* Bucket heap / gen */
+
+uint8_t bch_inc_gen(struct cache *ca, struct bucket *b)
+{
+	uint8_t ret = ++b->gen;
+
+	ca->set->need_gc = max(ca->set->need_gc, bucket_gc_gen(b));
+	WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX);
+
+	if (CACHE_SYNC(&ca->set->sb)) {
+		ca->need_save_prio = max(ca->need_save_prio,
+					 bucket_disk_gen(b));
+		WARN_ON_ONCE(ca->need_save_prio > BUCKET_DISK_GEN_MAX);
+	}
+
+	return ret;
+}
+
+void bch_rescale_priorities(struct cache_set *c, int sectors)
+{
+	struct cache *ca;
+	struct bucket *b;
+	unsigned next = c->nbuckets * c->sb.bucket_size / 1024;
+	unsigned i;
+	int r;
+
+	atomic_sub(sectors, &c->rescale);
+
+	do {
+		r = atomic_read(&c->rescale);
+
+		if (r >= 0)
+			return;
+	} while (atomic_cmpxchg(&c->rescale, r, r + next) != r);
+
+	mutex_lock(&c->bucket_lock);
+
+	c->min_prio = USHRT_MAX;
+
+	for_each_cache(ca, c, i)
+		for_each_bucket(b, ca)
+			if (b->prio &&
+			    b->prio != BTREE_PRIO &&
+			    !atomic_read(&b->pin)) {
+				b->prio--;
+				c->min_prio = min(c->min_prio, b->prio);
+			}
+
+	mutex_unlock(&c->bucket_lock);
+}
+
+/* Discard/TRIM */
+
+struct discard {
+	struct list_head	list;
+	struct work_struct	work;
+	struct cache		*ca;
+	long			bucket;
+
+	struct bio		bio;
+	struct bio_vec		bv;
+};
+
+static void discard_finish(struct work_struct *w)
+{
+	struct discard *d = container_of(w, struct discard, work);
+	struct cache *ca = d->ca;
+	char buf[BDEVNAME_SIZE];
+
+	if (!test_bit(BIO_UPTODATE, &d->bio.bi_flags)) {
+		pr_notice("discard error on %s, disabling",
+			 bdevname(ca->bdev, buf));
+		d->ca->discard = 0;
+	}
+
+	mutex_lock(&ca->set->bucket_lock);
+
+	fifo_push(&ca->free, d->bucket);
+	list_add(&d->list, &ca->discards);
+	atomic_dec(&ca->discards_in_flight);
+
+	mutex_unlock(&ca->set->bucket_lock);
+
+	closure_wake_up(&ca->set->bucket_wait);
+	wake_up(&ca->set->alloc_wait);
+
+	closure_put(&ca->set->cl);
+}
+
+static void discard_endio(struct bio *bio, int error)
+{
+	struct discard *d = container_of(bio, struct discard, bio);
+	schedule_work(&d->work);
+}
+
+static void do_discard(struct cache *ca, long bucket)
+{
+	struct discard *d = list_first_entry(&ca->discards,
+					     struct discard, list);
+
+	list_del(&d->list);
+	d->bucket = bucket;
+
+	atomic_inc(&ca->discards_in_flight);
+	closure_get(&ca->set->cl);
+
+	bio_init(&d->bio);
+
+	d->bio.bi_sector	= bucket_to_sector(ca->set, d->bucket);
+	d->bio.bi_bdev		= ca->bdev;
+	d->bio.bi_rw		= REQ_WRITE|REQ_DISCARD;
+	d->bio.bi_max_vecs	= 1;
+	d->bio.bi_io_vec	= d->bio.bi_inline_vecs;
+	d->bio.bi_size		= bucket_bytes(ca);
+	d->bio.bi_end_io	= discard_endio;
+	bio_set_prio(&d->bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
+
+	submit_bio(0, &d->bio);
+}
+
+/* Allocation */
+
+static inline bool can_inc_bucket_gen(struct bucket *b)
+{
+	return bucket_gc_gen(b) < BUCKET_GC_GEN_MAX &&
+		bucket_disk_gen(b) < BUCKET_DISK_GEN_MAX;
+}
+
+bool bch_bucket_add_unused(struct cache *ca, struct bucket *b)
+{
+	BUG_ON(GC_MARK(b) || GC_SECTORS_USED(b));
+
+	if (fifo_used(&ca->free) > ca->watermark[WATERMARK_MOVINGGC] &&
+	    CACHE_REPLACEMENT(&ca->sb) == CACHE_REPLACEMENT_FIFO)
+		return false;
+
+	b->prio = 0;
+
+	if (can_inc_bucket_gen(b) &&
+	    fifo_push(&ca->unused, b - ca->buckets)) {
+		atomic_inc(&b->pin);
+		return true;
+	}
+
+	return false;
+}
+
+static bool can_invalidate_bucket(struct cache *ca, struct bucket *b)
+{
+	return GC_MARK(b) == GC_MARK_RECLAIMABLE &&
+		!atomic_read(&b->pin) &&
+		can_inc_bucket_gen(b);
+}
+
+static void invalidate_one_bucket(struct cache *ca, struct bucket *b)
+{
+	bch_inc_gen(ca, b);
+	b->prio = INITIAL_PRIO;
+	atomic_inc(&b->pin);
+	fifo_push(&ca->free_inc, b - ca->buckets);
+}
+
+static void invalidate_buckets_lru(struct cache *ca)
+{
+	unsigned bucket_prio(struct bucket *b)
+	{
+		return ((unsigned) (b->prio - ca->set->min_prio)) *
+			GC_SECTORS_USED(b);
+	}
+
+	bool bucket_max_cmp(struct bucket *l, struct bucket *r)
+	{
+		return bucket_prio(l) < bucket_prio(r);
+	}
+
+	bool bucket_min_cmp(struct bucket *l, struct bucket *r)
+	{
+		return bucket_prio(l) > bucket_prio(r);
+	}
+
+	struct bucket *b;
+	ssize_t i;
+
+	ca->heap.used = 0;
+
+	for_each_bucket(b, ca) {
+		if (!can_invalidate_bucket(ca, b))
+			continue;
+
+		if (!GC_SECTORS_USED(b)) {
+			if (!bch_bucket_add_unused(ca, b))
+				return;
+		} else {
+			if (!heap_full(&ca->heap))
+				heap_add(&ca->heap, b, bucket_max_cmp);
+			else if (bucket_max_cmp(b, heap_peek(&ca->heap))) {
+				ca->heap.data[0] = b;
+				heap_sift(&ca->heap, 0, bucket_max_cmp);
+			}
+		}
+	}
+
+	if (ca->heap.used * 2 < ca->heap.size)
+		bch_queue_gc(ca->set);
+
+	for (i = ca->heap.used / 2 - 1; i >= 0; --i)
+		heap_sift(&ca->heap, i, bucket_min_cmp);
+
+	while (!fifo_full(&ca->free_inc)) {
+		if (!heap_pop(&ca->heap, b, bucket_min_cmp)) {
+			/* We don't want to be calling invalidate_buckets()
+			 * multiple times when it can't do anything
+			 */
+			ca->invalidate_needs_gc = 1;
+			bch_queue_gc(ca->set);
+			return;
+		}
+
+		invalidate_one_bucket(ca, b);
+	}
+}
+
+static void invalidate_buckets_fifo(struct cache *ca)
+{
+	struct bucket *b;
+	size_t checked = 0;
+
+	while (!fifo_full(&ca->free_inc)) {
+		if (ca->fifo_last_bucket <  ca->sb.first_bucket ||
+		    ca->fifo_last_bucket >= ca->sb.nbuckets)
+			ca->fifo_last_bucket = ca->sb.first_bucket;
+
+		b = ca->buckets + ca->fifo_last_bucket++;
+
+		if (can_invalidate_bucket(ca, b))
+			invalidate_one_bucket(ca, b);
+
+		if (++checked >= ca->sb.nbuckets) {
+			ca->invalidate_needs_gc = 1;
+			bch_queue_gc(ca->set);
+			return;
+		}
+	}
+}
+
+static void invalidate_buckets_random(struct cache *ca)
+{
+	struct bucket *b;
+	size_t checked = 0;
+
+	while (!fifo_full(&ca->free_inc)) {
+		size_t n;
+		get_random_bytes(&n, sizeof(n));
+
+		n %= (size_t) (ca->sb.nbuckets - ca->sb.first_bucket);
+		n += ca->sb.first_bucket;
+
+		b = ca->buckets + n;
+
+		if (can_invalidate_bucket(ca, b))
+			invalidate_one_bucket(ca, b);
+
+		if (++checked >= ca->sb.nbuckets / 2) {
+			ca->invalidate_needs_gc = 1;
+			bch_queue_gc(ca->set);
+			return;
+		}
+	}
+}
+
+static void invalidate_buckets(struct cache *ca)
+{
+	if (ca->invalidate_needs_gc)
+		return;
+
+	switch (CACHE_REPLACEMENT(&ca->sb)) {
+	case CACHE_REPLACEMENT_LRU:
+		invalidate_buckets_lru(ca);
+		break;
+	case CACHE_REPLACEMENT_FIFO:
+		invalidate_buckets_fifo(ca);
+		break;
+	case CACHE_REPLACEMENT_RANDOM:
+		invalidate_buckets_random(ca);
+		break;
+	}
+}
+
+#define allocator_wait(ca, cond)					\
+do {									\
+	DEFINE_WAIT(__wait);						\
+									\
+	while (!(cond)) {						\
+		prepare_to_wait(&ca->set->alloc_wait,			\
+				&__wait, TASK_INTERRUPTIBLE);		\
+									\
+		mutex_unlock(&(ca)->set->bucket_lock);			\
+		if (test_bit(CACHE_SET_STOPPING_2, &ca->set->flags)) {	\
+			finish_wait(&ca->set->alloc_wait, &__wait);	\
+			closure_return(cl);				\
+		}							\
+									\
+		schedule();						\
+		__set_current_state(TASK_RUNNING);			\
+		mutex_lock(&(ca)->set->bucket_lock);			\
+	}								\
+									\
+	finish_wait(&ca->set->alloc_wait, &__wait);			\
+} while (0)
+
+void bch_allocator_thread(struct closure *cl)
+{
+	struct cache *ca = container_of(cl, struct cache, alloc);
+
+	mutex_lock(&ca->set->bucket_lock);
+
+	while (1) {
+		while (1) {
+			long bucket;
+
+			if ((!atomic_read(&ca->set->prio_blocked) ||
+			     !CACHE_SYNC(&ca->set->sb)) &&
+			    !fifo_empty(&ca->unused))
+				fifo_pop(&ca->unused, bucket);
+			else if (!fifo_empty(&ca->free_inc))
+				fifo_pop(&ca->free_inc, bucket);
+			else
+				break;
+
+			allocator_wait(ca, (int) fifo_free(&ca->free) >
+				       atomic_read(&ca->discards_in_flight));
+
+			if (ca->discard) {
+				allocator_wait(ca, !list_empty(&ca->discards));
+				do_discard(ca, bucket);
+			} else {
+				fifo_push(&ca->free, bucket);
+				closure_wake_up(&ca->set->bucket_wait);
+			}
+		}
+
+		allocator_wait(ca, ca->set->gc_mark_valid);
+		invalidate_buckets(ca);
+
+		allocator_wait(ca, !atomic_read(&ca->set->prio_blocked) ||
+			       !CACHE_SYNC(&ca->set->sb));
+
+		if (CACHE_SYNC(&ca->set->sb) &&
+		    (!fifo_empty(&ca->free_inc) ||
+		     ca->need_save_prio > 64)) {
+			bch_prio_write(ca);
+		}
+	}
+}
+
+long bch_bucket_alloc(struct cache *ca, unsigned watermark, struct closure *cl)
+{
+	long r = -1;
+again:
+	wake_up(&ca->set->alloc_wait);
+
+	if (fifo_used(&ca->free) > ca->watermark[watermark] &&
+	    fifo_pop(&ca->free, r)) {
+		struct bucket *b = ca->buckets + r;
+#ifdef CONFIG_BCACHE_EDEBUG
+		size_t iter;
+		long i;
+
+		for (iter = 0; iter < prio_buckets(ca) * 2; iter++)
+			BUG_ON(ca->prio_buckets[iter] == (uint64_t) r);
+
+		fifo_for_each(i, &ca->free, iter)
+			BUG_ON(i == r);
+		fifo_for_each(i, &ca->free_inc, iter)
+			BUG_ON(i == r);
+		fifo_for_each(i, &ca->unused, iter)
+			BUG_ON(i == r);
+#endif
+		BUG_ON(atomic_read(&b->pin) != 1);
+
+		SET_GC_SECTORS_USED(b, ca->sb.bucket_size);
+
+		if (watermark <= WATERMARK_METADATA) {
+			SET_GC_MARK(b, GC_MARK_METADATA);
+			b->prio = BTREE_PRIO;
+		} else {
+			SET_GC_MARK(b, GC_MARK_RECLAIMABLE);
+			b->prio = INITIAL_PRIO;
+		}
+
+		return r;
+	}
+
+	pr_debug("alloc failure: blocked %i free %zu free_inc %zu unused %zu",
+		 atomic_read(&ca->set->prio_blocked), fifo_used(&ca->free),
+		 fifo_used(&ca->free_inc), fifo_used(&ca->unused));
+
+	if (cl) {
+		closure_wait(&ca->set->bucket_wait, cl);
+
+		if (closure_blocking(cl)) {
+			mutex_unlock(&ca->set->bucket_lock);
+			closure_sync(cl);
+			mutex_lock(&ca->set->bucket_lock);
+			goto again;
+		}
+	}
+
+	return -1;
+}
+
+void bch_bucket_free(struct cache_set *c, struct bkey *k)
+{
+	unsigned i;
+
+	for (i = 0; i < KEY_PTRS(k); i++) {
+		struct bucket *b = PTR_BUCKET(c, k, i);
+
+		SET_GC_MARK(b, 0);
+		SET_GC_SECTORS_USED(b, 0);
+		bch_bucket_add_unused(PTR_CACHE(c, k, i), b);
+	}
+}
+
+int __bch_bucket_alloc_set(struct cache_set *c, unsigned watermark,
+			   struct bkey *k, int n, struct closure *cl)
+{
+	int i;
+
+	lockdep_assert_held(&c->bucket_lock);
+	BUG_ON(!n || n > c->caches_loaded || n > 8);
+
+	bkey_init(k);
+
+	/* sort by free space/prio of oldest data in caches */
+
+	for (i = 0; i < n; i++) {
+		struct cache *ca = c->cache_by_alloc[i];
+		long b = bch_bucket_alloc(ca, watermark, cl);
+
+		if (b == -1)
+			goto err;
+
+		k->ptr[i] = PTR(ca->buckets[b].gen,
+				bucket_to_sector(c, b),
+				ca->sb.nr_this_dev);
+
+		SET_KEY_PTRS(k, i + 1);
+	}
+
+	return 0;
+err:
+	bch_bucket_free(c, k);
+	__bkey_put(c, k);
+	return -1;
+}
+
+int bch_bucket_alloc_set(struct cache_set *c, unsigned watermark,
+			 struct bkey *k, int n, struct closure *cl)
+{
+	int ret;
+	mutex_lock(&c->bucket_lock);
+	ret = __bch_bucket_alloc_set(c, watermark, k, n, cl);
+	mutex_unlock(&c->bucket_lock);
+	return ret;
+}
+
+/* Init */
+
+void bch_cache_allocator_exit(struct cache *ca)
+{
+	struct discard *d;
+
+	while (!list_empty(&ca->discards)) {
+		d = list_first_entry(&ca->discards, struct discard, list);
+		cancel_work_sync(&d->work);
+		list_del(&d->list);
+		kfree(d);
+	}
+}
+
+int bch_cache_allocator_init(struct cache *ca)
+{
+	unsigned i;
+
+	/*
+	 * Reserve:
+	 * Prio/gen writes first
+	 * Then 8 for btree allocations
+	 * Then half for the moving garbage collector
+	 */
+
+	ca->watermark[WATERMARK_PRIO] = 0;
+
+	ca->watermark[WATERMARK_METADATA] = prio_buckets(ca);
+
+	ca->watermark[WATERMARK_MOVINGGC] = 8 +
+		ca->watermark[WATERMARK_METADATA];
+
+	ca->watermark[WATERMARK_NONE] = ca->free.size / 2 +
+		ca->watermark[WATERMARK_MOVINGGC];
+
+	for (i = 0; i < MAX_IN_FLIGHT_DISCARDS; i++) {
+		struct discard *d = kzalloc(sizeof(*d), GFP_KERNEL);
+		if (!d)
+			return -ENOMEM;
+
+		d->ca = ca;
+		INIT_WORK(&d->work, discard_finish);
+		list_add(&d->list, &ca->discards);
+	}
+
+	return 0;
+}

drivers/md/bcache/bset.h

@@ -0,0 +1,379 @@
+#ifndef _BCACHE_BSET_H
+#define _BCACHE_BSET_H
+
+/*
+ * BKEYS:
+ *
+ * A bkey contains a key, a size field, a variable number of pointers, and some
+ * ancillary flag bits.
+ *
+ * We use two different functions for validating bkeys, bch_ptr_invalid and
+ * bch_ptr_bad().
+ *
+ * bch_ptr_invalid() primarily filters out keys and pointers that would be
+ * invalid due to some sort of bug, whereas bch_ptr_bad() filters out keys and
+ * pointer that occur in normal practice but don't point to real data.
+ *
+ * The one exception to the rule that ptr_invalid() filters out invalid keys is
+ * that it also filters out keys of size 0 - these are keys that have been
+ * completely overwritten. It'd be safe to delete these in memory while leaving
+ * them on disk, just unnecessary work - so we filter them out when resorting
+ * instead.
+ *
+ * We can't filter out stale keys when we're resorting, because garbage
+ * collection needs to find them to ensure bucket gens don't wrap around -
+ * unless we're rewriting the btree node those stale keys still exist on disk.
+ *
+ * We also implement functions here for removing some number of sectors from the
+ * front or the back of a bkey - this is mainly used for fixing overlapping
+ * extents, by removing the overlapping sectors from the older key.
+ *
+ * BSETS:
+ *
+ * A bset is an array of bkeys laid out contiguously in memory in sorted order,
+ * along with a header. A btree node is made up of a number of these, written at
+ * different times.
+ *
+ * There could be many of them on disk, but we never allow there to be more than
+ * 4 in memory - we lazily resort as needed.
+ *
+ * We implement code here for creating and maintaining auxiliary search trees
+ * (described below) for searching an individial bset, and on top of that we
+ * implement a btree iterator.
+ *
+ * BTREE ITERATOR:
+ *
+ * Most of the code in bcache doesn't care about an individual bset - it needs
+ * to search entire btree nodes and iterate over them in sorted order.
+ *
+ * The btree iterator code serves both functions; it iterates through the keys
+ * in a btree node in sorted order, starting from either keys after a specific
+ * point (if you pass it a search key) or the start of the btree node.
+ *
+ * AUXILIARY SEARCH TREES:
+ *
+ * Since keys are variable length, we can't use a binary search on a bset - we
+ * wouldn't be able to find the start of the next key. But binary searches are
+ * slow anyways, due to terrible cache behaviour; bcache originally used binary
+ * searches and that code topped out at under 50k lookups/second.
+ *
+ * So we need to construct some sort of lookup table. Since we only insert keys
+ * into the last (unwritten) set, most of the keys within a given btree node are
+ * usually in sets that are mostly constant. We use two different types of
+ * lookup tables to take advantage of this.
+ *
+ * Both lookup tables share in common that they don't index every key in the
+ * set; they index one key every BSET_CACHELINE bytes, and then a linear search
+ * is used for the rest.
+ *
+ * For sets that have been written to disk and are no longer being inserted
+ * into, we construct a binary search tree in an array - traversing a binary
+ * search tree in an array gives excellent locality of reference and is very
+ * fast, since both children of any node are adjacent to each other in memory
+ * (and their grandchildren, and great grandchildren...) - this means
+ * prefetching can be used to great effect.
+ *
+ * It's quite useful performance wise to keep these nodes small - not just
+ * because they're more likely to be in L2, but also because we can prefetch
+ * more nodes on a single cacheline and thus prefetch more iterations in advance
+ * when traversing this tree.
+ *
+ * Nodes in the auxiliary search tree must contain both a key to compare against
+ * (we don't want to fetch the key from the set, that would defeat the purpose),
+ * and a pointer to the key. We use a few tricks to compress both of these.
+ *
+ * To compress the pointer, we take advantage of the fact that one node in the
+ * search tree corresponds to precisely BSET_CACHELINE bytes in the set. We have
+ * a function (to_inorder()) that takes the index of a node in a binary tree and
+ * returns what its index would be in an inorder traversal, so we only have to
+ * store the low bits of the offset.
+ *
+ * The key is 84 bits (KEY_DEV + key->key, the offset on the device). To
+ * compress that,  we take advantage of the fact that when we're traversing the
+ * search tree at every iteration we know that both our search key and the key
+ * we're looking for lie within some range - bounded by our previous
+ * comparisons. (We special case the start of a search so that this is true even
+ * at the root of the tree).
+ *
+ * So we know the key we're looking for is between a and b, and a and b don't
+ * differ higher than bit 50, we don't need to check anything higher than bit
+ * 50.
+ *
+ * We don't usually need the rest of the bits, either; we only need enough bits
+ * to partition the key range we're currently checking.  Consider key n - the
+ * key our auxiliary search tree node corresponds to, and key p, the key
+ * immediately preceding n.  The lowest bit we need to store in the auxiliary
+ * search tree is the highest bit that differs between n and p.
+ *
+ * Note that this could be bit 0 - we might sometimes need all 80 bits to do the
+ * comparison. But we'd really like our nodes in the auxiliary search tree to be
+ * of fixed size.
+ *
+ * The solution is to make them fixed size, and when we're constructing a node
+ * check if p and n differed in the bits we needed them to. If they don't we
+ * flag that node, and when doing lookups we fallback to comparing against the
+ * real key. As long as this doesn't happen to often (and it seems to reliably
+ * happen a bit less than 1% of the time), we win - even on failures, that key
+ * is then more likely to be in cache than if we were doing binary searches all
+ * the way, since we're touching so much less memory.
+ *
+ * The keys in the auxiliary search tree are stored in (software) floating
+ * point, with an exponent and a mantissa. The exponent needs to be big enough
+ * to address all the bits in the original key, but the number of bits in the
+ * mantissa is somewhat arbitrary; more bits just gets us fewer failures.
+ *
+ * We need 7 bits for the exponent and 3 bits for the key's offset (since keys
+ * are 8 byte aligned); using 22 bits for the mantissa means a node is 4 bytes.
+ * We need one node per 128 bytes in the btree node, which means the auxiliary
+ * search trees take up 3% as much memory as the btree itself.
+ *
+ * Constructing these auxiliary search trees is moderately expensive, and we
+ * don't want to be constantly rebuilding the search tree for the last set
+ * whenever we insert another key into it. For the unwritten set, we use a much
+ * simpler lookup table - it's just a flat array, so index i in the lookup table
+ * corresponds to the i range of BSET_CACHELINE bytes in the set. Indexing
+ * within each byte range works the same as with the auxiliary search trees.
+ *
+ * These are much easier to keep up to date when we insert a key - we do it
+ * somewhat lazily; when we shift a key up we usually just increment the pointer
+ * to it, only when it would overflow do we go to the trouble of finding the
+ * first key in that range of bytes again.
+ */
+
+/* Btree key comparison/iteration */
+
+struct btree_iter {
+	size_t size, used;
+	struct btree_iter_set {
+		struct bkey *k, *end;
+	} data[MAX_BSETS];
+};
+
+struct bset_tree {
+	/*
+	 * We construct a binary tree in an array as if the array
+	 * started at 1, so that things line up on the same cachelines
+	 * better: see comments in bset.c at cacheline_to_bkey() for
+	 * details
+	 */
+
+	/* size of the binary tree and prev array */
+	unsigned	size;
+
+	/* function of size - precalculated for to_inorder() */
+	unsigned	extra;
+
+	/* copy of the last key in the set */
+	struct bkey	end;
+	struct bkey_float *tree;
+
+	/*
+	 * The nodes in the bset tree point to specific keys - this
+	 * array holds the sizes of the previous key.
+	 *
+	 * Conceptually it's a member of struct bkey_float, but we want
+	 * to keep bkey_float to 4 bytes and prev isn't used in the fast
+	 * path.
+	 */
+	uint8_t		*prev;
+
+	/* The actual btree node, with pointers to each sorted set */
+	struct bset	*data;
+};
+
+static __always_inline int64_t bkey_cmp(const struct bkey *l,
+					const struct bkey *r)
+{
+	return unlikely(KEY_INODE(l) != KEY_INODE(r))
+		? (int64_t) KEY_INODE(l) - (int64_t) KEY_INODE(r)
+		: (int64_t) KEY_OFFSET(l) - (int64_t) KEY_OFFSET(r);
+}
+
+static inline size_t bkey_u64s(const struct bkey *k)
+{
+	BUG_ON(KEY_CSUM(k) > 1);
+	return 2 + KEY_PTRS(k) + (KEY_CSUM(k) ? 1 : 0);
+}
+
+static inline size_t bkey_bytes(const struct bkey *k)
+{
+	return bkey_u64s(k) * sizeof(uint64_t);
+}
+
+static inline void bkey_copy(struct bkey *dest, const struct bkey *src)
+{
+	memcpy(dest, src, bkey_bytes(src));
+}
+
+static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
+{
+	if (!src)
+		src = &KEY(0, 0, 0);
+
+	SET_KEY_INODE(dest, KEY_INODE(src));
+	SET_KEY_OFFSET(dest, KEY_OFFSET(src));
+}
+
+static inline struct bkey *bkey_next(const struct bkey *k)
+{
+	uint64_t *d = (void *) k;
+	return (struct bkey *) (d + bkey_u64s(k));
+}
+
+/* Keylists */
+
+struct keylist {
+	struct bkey		*top;
+	union {
+		uint64_t		*list;
+		struct bkey		*bottom;
+	};
+
+	/* Enough room for btree_split's keys without realloc */
+#define KEYLIST_INLINE		16
+	uint64_t		d[KEYLIST_INLINE];
+};
+
+static inline void bch_keylist_init(struct keylist *l)
+{
+	l->top = (void *) (l->list = l->d);
+}
+
+static inline void bch_keylist_push(struct keylist *l)
+{
+	l->top = bkey_next(l->top);
+}
+
+static inline void bch_keylist_add(struct keylist *l, struct bkey *k)
+{
+	bkey_copy(l->top, k);
+	bch_keylist_push(l);
+}
+
+static inline bool bch_keylist_empty(struct keylist *l)
+{
+	return l->top == (void *) l->list;
+}
+
+static inline void bch_keylist_free(struct keylist *l)
+{
+	if (l->list != l->d)
+		kfree(l->list);
+}
+
+void bch_keylist_copy(struct keylist *, struct keylist *);
+struct bkey *bch_keylist_pop(struct keylist *);
+int bch_keylist_realloc(struct keylist *, int, struct cache_set *);
+
+void bch_bkey_copy_single_ptr(struct bkey *, const struct bkey *,
+			      unsigned);
+bool __bch_cut_front(const struct bkey *, struct bkey *);
+bool __bch_cut_back(const struct bkey *, struct bkey *);
+
+static inline bool bch_cut_front(const struct bkey *where, struct bkey *k)
+{
+	BUG_ON(bkey_cmp(where, k) > 0);
+	return __bch_cut_front(where, k);
+}
+
+static inline bool bch_cut_back(const struct bkey *where, struct bkey *k)
+{
+	BUG_ON(bkey_cmp(where, &START_KEY(k)) < 0);
+	return __bch_cut_back(where, k);
+}
+
+const char *bch_ptr_status(struct cache_set *, const struct bkey *);
+bool __bch_ptr_invalid(struct cache_set *, int level, const struct bkey *);
+bool bch_ptr_bad(struct btree *, const struct bkey *);
+
+static inline uint8_t gen_after(uint8_t a, uint8_t b)
+{
+	uint8_t r = a - b;
+	return r > 128U ? 0 : r;
+}
+
+static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k,
+				unsigned i)
+{
+	return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i));
+}
+
+static inline bool ptr_available(struct cache_set *c, const struct bkey *k,
+				 unsigned i)
+{
+	return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && PTR_CACHE(c, k, i);
+}
+
+
+typedef bool (*ptr_filter_fn)(struct btree *, const struct bkey *);
+
+struct bkey *bch_next_recurse_key(struct btree *, struct bkey *);
+struct bkey *bch_btree_iter_next(struct btree_iter *);
+struct bkey *bch_btree_iter_next_filter(struct btree_iter *,
+					struct btree *, ptr_filter_fn);
+
+void bch_btree_iter_push(struct btree_iter *, struct bkey *, struct bkey *);
+struct bkey *__bch_btree_iter_init(struct btree *, struct btree_iter *,
+				   struct bkey *, struct bset_tree *);
+
+/* 32 bits total: */
+#define BKEY_MID_BITS		3
+#define BKEY_EXPONENT_BITS	7
+#define BKEY_MANTISSA_BITS	22
+#define BKEY_MANTISSA_MASK	((1 << BKEY_MANTISSA_BITS) - 1)
+
+struct bkey_float {
+	unsigned	exponent:BKEY_EXPONENT_BITS;
+	unsigned	m:BKEY_MID_BITS;
+	unsigned	mantissa:BKEY_MANTISSA_BITS;
+} __packed;
+
+/*
+ * BSET_CACHELINE was originally intended to match the hardware cacheline size -
+ * it used to be 64, but I realized the lookup code would touch slightly less
+ * memory if it was 128.
+ *
+ * It definites the number of bytes (in struct bset) per struct bkey_float in
+ * the auxiliar search tree - when we're done searching the bset_float tree we
+ * have this many bytes left that we do a linear search over.
+ *
+ * Since (after level 5) every level of the bset_tree is on a new cacheline,
+ * we're touching one fewer cacheline in the bset tree in exchange for one more
+ * cacheline in the linear search - but the linear search might stop before it
+ * gets to the second cacheline.
+ */
+
+#define BSET_CACHELINE		128
+#define bset_tree_space(b)	(btree_data_space(b) / BSET_CACHELINE)
+
+#define bset_tree_bytes(b)	(bset_tree_space(b) * sizeof(struct bkey_float))
+#define bset_prev_bytes(b)	(bset_tree_space(b) * sizeof(uint8_t))
+
+void bch_bset_init_next(struct btree *);
+
+void bch_bset_fix_invalidated_key(struct btree *, struct bkey *);
+void bch_bset_fix_lookup_table(struct btree *, struct bkey *);
+
+struct bkey *__bch_bset_search(struct btree *, struct bset_tree *,
+			   const struct bkey *);
+
+static inline struct bkey *bch_bset_search(struct btree *b, struct bset_tree *t,
+					   const struct bkey *search)
+{
+	return search ? __bch_bset_search(b, t, search) : t->data->start;
+}
+
+bool bch_bkey_try_merge(struct btree *, struct bkey *, struct bkey *);
+void bch_btree_sort_lazy(struct btree *);
+void bch_btree_sort_into(struct btree *, struct btree *);
+void bch_btree_sort_and_fix_extents(struct btree *, struct btree_iter *);
+void bch_btree_sort_partial(struct btree *, unsigned);
+
+static inline void bch_btree_sort(struct btree *b)
+{
+	bch_btree_sort_partial(b, 0);
+}
+
+int bch_bset_print_stats(struct cache_set *, char *);
+
+#endif

drivers/md/bcache/btree.h

@@ -0,0 +1,405 @@
+#ifndef _BCACHE_BTREE_H
+#define _BCACHE_BTREE_H
+
+/*
+ * THE BTREE:
+ *
+ * At a high level, bcache's btree is relatively standard b+ tree. All keys and
+ * pointers are in the leaves; interior nodes only have pointers to the child
+ * nodes.
+ *
+ * In the interior nodes, a struct bkey always points to a child btree node, and
+ * the key is the highest key in the child node - except that the highest key in
+ * an interior node is always MAX_KEY. The size field refers to the size on disk
+ * of the child node - this would allow us to have variable sized btree nodes
+ * (handy for keeping the depth of the btree 1 by expanding just the root).
+ *
+ * Btree nodes are themselves log structured, but this is hidden fairly
+ * thoroughly. Btree nodes on disk will in practice have extents that overlap
+ * (because they were written at different times), but in memory we never have
+ * overlapping extents - when we read in a btree node from disk, the first thing
+ * we do is resort all the sets of keys with a mergesort, and in the same pass
+ * we check for overlapping extents and adjust them appropriately.
+ *
+ * struct btree_op is a central interface to the btree code. It's used for
+ * specifying read vs. write locking, and the embedded closure is used for
+ * waiting on IO or reserve memory.
+ *
+ * BTREE CACHE:
+ *
+ * Btree nodes are cached in memory; traversing the btree might require reading
+ * in btree nodes which is handled mostly transparently.
+ *
+ * bch_btree_node_get() looks up a btree node in the cache and reads it in from
+ * disk if necessary. This function is almost never called directly though - the
+ * btree() macro is used to get a btree node, call some function on it, and
+ * unlock the node after the function returns.
+ *
+ * The root is special cased - it's taken out of the cache's lru (thus pinning
+ * it in memory), so we can find the root of the btree by just dereferencing a
+ * pointer instead of looking it up in the cache. This makes locking a bit
+ * tricky, since the root pointer is protected by the lock in the btree node it
+ * points to - the btree_root() macro handles this.
+ *
+ * In various places we must be able to allocate memory for multiple btree nodes
+ * in order to make forward progress. To do this we use the btree cache itself
+ * as a reserve; if __get_free_pages() fails, we'll find a node in the btree
+ * cache we can reuse. We can't allow more than one thread to be doing this at a
+ * time, so there's a lock, implemented by a pointer to the btree_op closure -
+ * this allows the btree_root() macro to implicitly release this lock.
+ *
+ * BTREE IO:
+ *
+ * Btree nodes never have to be explicitly read in; bch_btree_node_get() handles
+ * this.
+ *
+ * For writing, we have two btree_write structs embeddded in struct btree - one
+ * write in flight, and one being set up, and we toggle between them.
+ *
+ * Writing is done with a single function -  bch_btree_write() really serves two
+ * different purposes and should be broken up into two different functions. When
+ * passing now = false, it merely indicates that the node is now dirty - calling
+ * it ensures that the dirty keys will be written at some point in the future.
+ *
+ * When passing now = true, bch_btree_write() causes a write to happen
+ * "immediately" (if there was already a write in flight, it'll cause the write
+ * to happen as soon as the previous write completes). It returns immediately
+ * though - but it takes a refcount on the closure in struct btree_op you passed
+ * to it, so a closure_sync() later can be used to wait for the write to
+ * complete.
+ *
+ * This is handy because btree_split() and garbage collection can issue writes
+ * in parallel, reducing the amount of time they have to hold write locks.
+ *
+ * LOCKING:
+ *
+ * When traversing the btree, we may need write locks starting at some level -
+ * inserting a key into the btree will typically only require a write lock on
+ * the leaf node.
+ *
+ * This is specified with the lock field in struct btree_op; lock = 0 means we
+ * take write locks at level <= 0, i.e. only leaf nodes. bch_btree_node_get()
+ * checks this field and returns the node with the appropriate lock held.
+ *
+ * If, after traversing the btree, the insertion code discovers it has to split
+ * then it must restart from the root and take new locks - to do this it changes
+ * the lock field and returns -EINTR, which causes the btree_root() macro to
+ * loop.
+ *
+ * Handling cache misses require a different mechanism for upgrading to a write
+ * lock. We do cache lookups with only a read lock held, but if we get a cache
+ * miss and we wish to insert this data into the cache, we have to insert a
+ * placeholder key to detect races - otherwise, we could race with a write and
+ * overwrite the data that was just written to the cache with stale data from
+ * the backing device.
+ *
+ * For this we use a sequence number that write locks and unlocks increment - to
+ * insert the check key it unlocks the btree node and then takes a write lock,
+ * and fails if the sequence number doesn't match.
+ */
+
+#include "bset.h"
+#include "debug.h"
+
+struct btree_write {
+	struct closure		*owner;
+	atomic_t		*journal;
+
+	/* If btree_split() frees a btree node, it writes a new pointer to that
+	 * btree node indicating it was freed; it takes a refcount on
+	 * c->prio_blocked because we can't write the gens until the new
+	 * pointer is on disk. This allows btree_write_endio() to release the
+	 * refcount that btree_split() took.
+	 */
+	int			prio_blocked;
+};
+
+struct btree {
+	/* Hottest entries first */
+	struct hlist_node	hash;
+
+	/* Key/pointer for this btree node */
+	BKEY_PADDED(key);
+
+	/* Single bit - set when accessed, cleared by shrinker */
+	unsigned long		accessed;
+	unsigned long		seq;
+	struct rw_semaphore	lock;
+	struct cache_set	*c;
+
+	unsigned long		flags;
+	uint16_t		written;	/* would be nice to kill */
+	uint8_t			level;
+	uint8_t			nsets;
+	uint8_t			page_order;
+
+	/*
+	 * Set of sorted keys - the real btree node - plus a binary search tree
+	 *
+	 * sets[0] is special; set[0]->tree, set[0]->prev and set[0]->data point
+	 * to the memory we have allocated for this btree node. Additionally,
+	 * set[0]->data points to the entire btree node as it exists on disk.
+	 */
+	struct bset_tree	sets[MAX_BSETS];
+
+	/* Used to refcount bio splits, also protects b->bio */
+	struct closure_with_waitlist	io;
+
+	/* Gets transferred to w->prio_blocked - see the comment there */
+	int			prio_blocked;
+
+	struct list_head	list;
+	struct delayed_work	work;
+
+	uint64_t		io_start_time;
+	struct btree_write	writes[2];
+	struct bio		*bio;
+};
+
+#define BTREE_FLAG(flag)						\
+static inline bool btree_node_ ## flag(struct btree *b)			\
+{	return test_bit(BTREE_NODE_ ## flag, &b->flags); }		\
+									\
+static inline void set_btree_node_ ## flag(struct btree *b)		\
+{	set_bit(BTREE_NODE_ ## flag, &b->flags); }			\
+
+enum btree_flags {
+	BTREE_NODE_read_done,
+	BTREE_NODE_io_error,
+	BTREE_NODE_dirty,
+	BTREE_NODE_write_idx,
+};
+
+BTREE_FLAG(read_done);
+BTREE_FLAG(io_error);
+BTREE_FLAG(dirty);
+BTREE_FLAG(write_idx);
+
+static inline struct btree_write *btree_current_write(struct btree *b)
+{
+	return b->writes + btree_node_write_idx(b);
+}
+
+static inline struct btree_write *btree_prev_write(struct btree *b)
+{
+	return b->writes + (btree_node_write_idx(b) ^ 1);
+}
+
+static inline unsigned bset_offset(struct btree *b, struct bset *i)
+{
+	return (((size_t) i) - ((size_t) b->sets->data)) >> 9;
+}
+
+static inline struct bset *write_block(struct btree *b)
+{
+	return ((void *) b->sets[0].data) + b->written * block_bytes(b->c);
+}
+
+static inline bool bset_written(struct btree *b, struct bset_tree *t)
+{
+	return t->data < write_block(b);
+}
+
+static inline bool bkey_written(struct btree *b, struct bkey *k)
+{
+	return k < write_block(b)->start;
+}
+
+static inline void set_gc_sectors(struct cache_set *c)
+{
+	atomic_set(&c->sectors_to_gc, c->sb.bucket_size * c->nbuckets / 8);
+}
+
+static inline bool bch_ptr_invalid(struct btree *b, const struct bkey *k)
+{
+	return __bch_ptr_invalid(b->c, b->level, k);
+}
+
+static inline struct bkey *bch_btree_iter_init(struct btree *b,
+					       struct btree_iter *iter,
+					       struct bkey *search)
+{
+	return __bch_btree_iter_init(b, iter, search, b->sets);
+}
+
+/* Looping macros */
+
+#define for_each_cached_btree(b, c, iter)				\
+	for (iter = 0;							\
+	     iter < ARRAY_SIZE((c)->bucket_hash);			\
+	     iter++)							\
+		hlist_for_each_entry_rcu((b), (c)->bucket_hash + iter, hash)
+
+#define for_each_key_filter(b, k, iter, filter)				\
+	for (bch_btree_iter_init((b), (iter), NULL);			\
+	     ((k) = bch_btree_iter_next_filter((iter), b, filter));)
+
+#define for_each_key(b, k, iter)					\
+	for (bch_btree_iter_init((b), (iter), NULL);			\
+	     ((k) = bch_btree_iter_next(iter));)
+
+/* Recursing down the btree */
+
+struct btree_op {
+	struct closure		cl;
+	struct cache_set	*c;
+
+	/* Journal entry we have a refcount on */
+	atomic_t		*journal;
+
+	/* Bio to be inserted into the cache */
+	struct bio		*cache_bio;
+
+	unsigned		inode;
+
+	uint16_t		write_prio;
+
+	/* Btree level at which we start taking write locks */
+	short			lock;
+
+	/* Btree insertion type */
+	enum {
+		BTREE_INSERT,
+		BTREE_REPLACE
+	} type:8;
+
+	unsigned		csum:1;
+	unsigned		skip:1;
+	unsigned		flush_journal:1;
+
+	unsigned		insert_data_done:1;
+	unsigned		lookup_done:1;
+	unsigned		insert_collision:1;
+
+	/* Anything after this point won't get zeroed in do_bio_hook() */
+
+	/* Keys to be inserted */
+	struct keylist		keys;
+	BKEY_PADDED(replace);
+};
+
+void bch_btree_op_init_stack(struct btree_op *);
+
+static inline void rw_lock(bool w, struct btree *b, int level)
+{
+	w ? down_write_nested(&b->lock, level + 1)
+	  : down_read_nested(&b->lock, level + 1);
+	if (w)
+		b->seq++;
+}
+
+static inline void rw_unlock(bool w, struct btree *b)
+{
+#ifdef CONFIG_BCACHE_EDEBUG
+	unsigned i;
+
+	if (w &&
+	    b->key.ptr[0] &&
+	    btree_node_read_done(b))
+		for (i = 0; i <= b->nsets; i++)
+			bch_check_key_order(b, b->sets[i].data);
+#endif
+
+	if (w)
+		b->seq++;
+	(w ? up_write : up_read)(&b->lock);
+}
+
+#define insert_lock(s, b)	((b)->level <= (s)->lock)
+
+/*
+ * These macros are for recursing down the btree - they handle the details of
+ * locking and looking up nodes in the cache for you. They're best treated as
+ * mere syntax when reading code that uses them.
+ *
+ * op->lock determines whether we take a read or a write lock at a given depth.
+ * If you've got a read lock and find that you need a write lock (i.e. you're
+ * going to have to split), set op->lock and return -EINTR; btree_root() will
+ * call you again and you'll have the correct lock.
+ */
+
+/**
+ * btree - recurse down the btree on a specified key
+ * @fn:		function to call, which will be passed the child node
+ * @key:	key to recurse on
+ * @b:		parent btree node
+ * @op:		pointer to struct btree_op
+ */
+#define btree(fn, key, b, op, ...)					\
+({									\
+	int _r, l = (b)->level - 1;					\
+	bool _w = l <= (op)->lock;					\
+	struct btree *_b = bch_btree_node_get((b)->c, key, l, op);	\
+	if (!IS_ERR(_b)) {						\
+		_r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__);		\
+		rw_unlock(_w, _b);					\
+	} else								\
+		_r = PTR_ERR(_b);					\
+	_r;								\
+})
+
+/**
+ * btree_root - call a function on the root of the btree
+ * @fn:		function to call, which will be passed the child node
+ * @c:		cache set
+ * @op:		pointer to struct btree_op
+ */
+#define btree_root(fn, c, op, ...)					\
+({									\
+	int _r = -EINTR;						\
+	do {								\
+		struct btree *_b = (c)->root;				\
+		bool _w = insert_lock(op, _b);				\
+		rw_lock(_w, _b, _b->level);				\
+		if (_b == (c)->root &&					\
+		    _w == insert_lock(op, _b))				\
+			_r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__);	\
+		rw_unlock(_w, _b);					\
+		bch_cannibalize_unlock(c, &(op)->cl);		\
+	} while (_r == -EINTR);						\
+									\
+	_r;								\
+})
+
+static inline bool should_split(struct btree *b)
+{
+	struct bset *i = write_block(b);
+	return b->written >= btree_blocks(b) ||
+		(i->seq == b->sets[0].data->seq &&
+		 b->written + __set_blocks(i, i->keys + 15, b->c)
+		 > btree_blocks(b));
+}
+
+void bch_btree_read_done(struct closure *);
+void bch_btree_read(struct btree *);
+void bch_btree_write(struct btree *b, bool now, struct btree_op *op);
+
+void bch_cannibalize_unlock(struct cache_set *, struct closure *);
+void bch_btree_set_root(struct btree *);
+struct btree *bch_btree_node_alloc(struct cache_set *, int, struct closure *);
+struct btree *bch_btree_node_get(struct cache_set *, struct bkey *,
+				int, struct btree_op *);
+
+bool bch_btree_insert_keys(struct btree *, struct btree_op *);
+bool bch_btree_insert_check_key(struct btree *, struct btree_op *,
+				   struct bio *);
+int bch_btree_insert(struct btree_op *, struct cache_set *);
+
+int bch_btree_search_recurse(struct btree *, struct btree_op *);
+
+void bch_queue_gc(struct cache_set *);
+size_t bch_btree_gc_finish(struct cache_set *);
+void bch_moving_gc(struct closure *);
+int bch_btree_check(struct cache_set *, struct btree_op *);
+uint8_t __bch_btree_mark_key(struct cache_set *, int, struct bkey *);
+
+void bch_keybuf_init(struct keybuf *, keybuf_pred_fn *);
+void bch_refill_keybuf(struct cache_set *, struct keybuf *, struct bkey *);
+bool bch_keybuf_check_overlapping(struct keybuf *, struct bkey *,
+				  struct bkey *);
+void bch_keybuf_del(struct keybuf *, struct keybuf_key *);
+struct keybuf_key *bch_keybuf_next(struct keybuf *);
+struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *,
+					  struct keybuf *, struct bkey *);
+
+#endif

drivers/md/bcache/closure.c

@@ -0,0 +1,348 @@
+/*
+ * Asynchronous refcounty things
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+
+#include "closure.h"
+
+void closure_queue(struct closure *cl)
+{
+	struct workqueue_struct *wq = cl->wq;
+	if (wq) {
+		INIT_WORK(&cl->work, cl->work.func);
+		BUG_ON(!queue_work(wq, &cl->work));
+	} else
+		cl->fn(cl);
+}
+EXPORT_SYMBOL_GPL(closure_queue);
+
+#define CL_FIELD(type, field)					\
+	case TYPE_ ## type:					\
+	return &container_of(cl, struct type, cl)->field
+
+static struct closure_waitlist *closure_waitlist(struct closure *cl)
+{
+	switch (cl->type) {
+		CL_FIELD(closure_with_waitlist, wait);
+		CL_FIELD(closure_with_waitlist_and_timer, wait);
+	default:
+		return NULL;
+	}
+}
+
+static struct timer_list *closure_timer(struct closure *cl)
+{
+	switch (cl->type) {
+		CL_FIELD(closure_with_timer, timer);
+		CL_FIELD(closure_with_waitlist_and_timer, timer);
+	default:
+		return NULL;
+	}
+}
+
+static inline void closure_put_after_sub(struct closure *cl, int flags)
+{
+	int r = flags & CLOSURE_REMAINING_MASK;
+
+	BUG_ON(flags & CLOSURE_GUARD_MASK);
+	BUG_ON(!r && (flags & ~(CLOSURE_DESTRUCTOR|CLOSURE_BLOCKING)));
+
+	/* Must deliver precisely one wakeup */
+	if (r == 1 && (flags & CLOSURE_SLEEPING))
+		wake_up_process(cl->task);
+
+	if (!r) {
+		if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) {
+			/* CLOSURE_BLOCKING might be set - clear it */
+			atomic_set(&cl->remaining,
+				   CLOSURE_REMAINING_INITIALIZER);
+			closure_queue(cl);
+		} else {
+			struct closure *parent = cl->parent;
+			struct closure_waitlist *wait = closure_waitlist(cl);
+
+			closure_debug_destroy(cl);
+
+			atomic_set(&cl->remaining, -1);
+
+			if (wait)
+				closure_wake_up(wait);
+
+			if (cl->fn)
+				cl->fn(cl);
+
+			if (parent)
+				closure_put(parent);
+		}
+	}
+}
+
+/* For clearing flags with the same atomic op as a put */
+void closure_sub(struct closure *cl, int v)
+{
+	closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining));
+}
+EXPORT_SYMBOL_GPL(closure_sub);
+
+void closure_put(struct closure *cl)
+{
+	closure_put_after_sub(cl, atomic_dec_return(&cl->remaining));
+}
+EXPORT_SYMBOL_GPL(closure_put);
+
+static void set_waiting(struct closure *cl, unsigned long f)
+{
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+	cl->waiting_on = f;
+#endif
+}
+
+void __closure_wake_up(struct closure_waitlist *wait_list)
+{
+	struct llist_node *list;
+	struct closure *cl;
+	struct llist_node *reverse = NULL;
+
+	list = llist_del_all(&wait_list->list);
+
+	/* We first reverse the list to preserve FIFO ordering and fairness */
+
+	while (list) {
+		struct llist_node *t = list;
+		list = llist_next(list);
+
+		t->next = reverse;
+		reverse = t;
+	}
+
+	/* Then do the wakeups */
+
+	while (reverse) {
+		cl = container_of(reverse, struct closure, list);
+		reverse = llist_next(reverse);
+
+		set_waiting(cl, 0);
+		closure_sub(cl, CLOSURE_WAITING + 1);
+	}
+}
+EXPORT_SYMBOL_GPL(__closure_wake_up);
+
+bool closure_wait(struct closure_waitlist *list, struct closure *cl)
+{
+	if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
+		return false;
+
+	set_waiting(cl, _RET_IP_);
+	atomic_add(CLOSURE_WAITING + 1, &cl->remaining);
+	llist_add(&cl->list, &list->list);
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(closure_wait);
+
+/**
+ * closure_sync() - sleep until a closure a closure has nothing left to wait on
+ *
+ * Sleeps until the refcount hits 1 - the thread that's running the closure owns
+ * the last refcount.
+ */
+void closure_sync(struct closure *cl)
+{
+	while (1) {
+		__closure_start_sleep(cl);
+		closure_set_ret_ip(cl);
+
+		if ((atomic_read(&cl->remaining) &
+		     CLOSURE_REMAINING_MASK) == 1)
+			break;
+
+		schedule();
+	}
+
+	__closure_end_sleep(cl);
+}
+EXPORT_SYMBOL_GPL(closure_sync);
+
+/**
+ * closure_trylock() - try to acquire the closure, without waiting
+ * @cl:		closure to lock
+ *
+ * Returns true if the closure was succesfully locked.
+ */
+bool closure_trylock(struct closure *cl, struct closure *parent)
+{
+	if (atomic_cmpxchg(&cl->remaining, -1,
+			   CLOSURE_REMAINING_INITIALIZER) != -1)
+		return false;
+
+	closure_set_ret_ip(cl);
+
+	smp_mb();
+	cl->parent = parent;
+	if (parent)
+		closure_get(parent);
+
+	closure_debug_create(cl);
+	return true;
+}
+EXPORT_SYMBOL_GPL(closure_trylock);
+
+void __closure_lock(struct closure *cl, struct closure *parent,
+		    struct closure_waitlist *wait_list)
+{
+	struct closure wait;
+	closure_init_stack(&wait);
+
+	while (1) {
+		if (closure_trylock(cl, parent))
+			return;
+
+		closure_wait_event_sync(wait_list, &wait,
+					atomic_read(&cl->remaining) == -1);
+	}
+}
+EXPORT_SYMBOL_GPL(__closure_lock);
+
+static void closure_delay_timer_fn(unsigned long data)
+{
+	struct closure *cl = (struct closure *) data;
+	closure_sub(cl, CLOSURE_TIMER + 1);
+}
+
+void do_closure_timer_init(struct closure *cl)
+{
+	struct timer_list *timer = closure_timer(cl);
+
+	init_timer(timer);
+	timer->data	= (unsigned long) cl;
+	timer->function = closure_delay_timer_fn;
+}
+EXPORT_SYMBOL_GPL(do_closure_timer_init);
+
+bool __closure_delay(struct closure *cl, unsigned long delay,
+		     struct timer_list *timer)
+{
+	if (atomic_read(&cl->remaining) & CLOSURE_TIMER)
+		return false;
+
+	BUG_ON(timer_pending(timer));
+
+	timer->expires	= jiffies + delay;
+
+	atomic_add(CLOSURE_TIMER + 1, &cl->remaining);
+	add_timer(timer);
+	return true;
+}
+EXPORT_SYMBOL_GPL(__closure_delay);
+
+void __closure_flush(struct closure *cl, struct timer_list *timer)
+{
+	if (del_timer(timer))
+		closure_sub(cl, CLOSURE_TIMER + 1);
+}
+EXPORT_SYMBOL_GPL(__closure_flush);
+
+void __closure_flush_sync(struct closure *cl, struct timer_list *timer)
+{
+	if (del_timer_sync(timer))
+		closure_sub(cl, CLOSURE_TIMER + 1);
+}
+EXPORT_SYMBOL_GPL(__closure_flush_sync);
+
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+
+static LIST_HEAD(closure_list);
+static DEFINE_SPINLOCK(closure_list_lock);
+
+void closure_debug_create(struct closure *cl)
+{
+	unsigned long flags;
+
+	BUG_ON(cl->magic == CLOSURE_MAGIC_ALIVE);
+	cl->magic = CLOSURE_MAGIC_ALIVE;
+
+	spin_lock_irqsave(&closure_list_lock, flags);
+	list_add(&cl->all, &closure_list);
+	spin_unlock_irqrestore(&closure_list_lock, flags);
+}
+EXPORT_SYMBOL_GPL(closure_debug_create);
+
+void closure_debug_destroy(struct closure *cl)
+{
+	unsigned long flags;
+
+	BUG_ON(cl->magic != CLOSURE_MAGIC_ALIVE);
+	cl->magic = CLOSURE_MAGIC_DEAD;
+
+	spin_lock_irqsave(&closure_list_lock, flags);
+	list_del(&cl->all);
+	spin_unlock_irqrestore(&closure_list_lock, flags);
+}
+EXPORT_SYMBOL_GPL(closure_debug_destroy);
+
+static struct dentry *debug;
+
+#define work_data_bits(work) ((unsigned long *)(&(work)->data))
+
+static int debug_seq_show(struct seq_file *f, void *data)
+{
+	struct closure *cl;
+	spin_lock_irq(&closure_list_lock);
+
+	list_for_each_entry(cl, &closure_list, all) {
+		int r = atomic_read(&cl->remaining);
+
+		seq_printf(f, "%p: %pF -> %pf p %p r %i ",
+			   cl, (void *) cl->ip, cl->fn, cl->parent,
+			   r & CLOSURE_REMAINING_MASK);
+
+		seq_printf(f, "%s%s%s%s%s%s\n",
+			   test_bit(WORK_STRUCT_PENDING,
+				    work_data_bits(&cl->work)) ? "Q" : "",
+			   r & CLOSURE_RUNNING	? "R" : "",
+			   r & CLOSURE_BLOCKING	? "B" : "",
+			   r & CLOSURE_STACK	? "S" : "",
+			   r & CLOSURE_SLEEPING	? "Sl" : "",
+			   r & CLOSURE_TIMER	? "T" : "");
+
+		if (r & CLOSURE_WAITING)
+			seq_printf(f, " W %pF\n",
+				   (void *) cl->waiting_on);
+
+		seq_printf(f, "\n");
+	}
+
+	spin_unlock_irq(&closure_list_lock);
+	return 0;
+}
+
+static int debug_seq_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, debug_seq_show, NULL);
+}
+
+static const struct file_operations debug_ops = {
+	.owner		= THIS_MODULE,
+	.open		= debug_seq_open,
+	.read		= seq_read,
+	.release	= single_release
+};
+
+int __init closure_debug_init(void)
+{
+	debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops);
+	return 0;
+}
+
+module_init(closure_debug_init);
+
+#endif
+
+MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
+MODULE_LICENSE("GPL");

drivers/md/bcache/closure.h

@@ -0,0 +1,670 @@
+#ifndef _LINUX_CLOSURE_H
+#define _LINUX_CLOSURE_H
+
+#include <linux/llist.h>
+#include <linux/sched.h>
+#include <linux/workqueue.h>
+
+/*
+ * Closure is perhaps the most overused and abused term in computer science, but
+ * since I've been unable to come up with anything better you're stuck with it
+ * again.
+ *
+ * What are closures?
+ *
+ * They embed a refcount. The basic idea is they count "things that are in
+ * progress" - in flight bios, some other thread that's doing something else -
+ * anything you might want to wait on.
+ *
+ * The refcount may be manipulated with closure_get() and closure_put().
+ * closure_put() is where many of the interesting things happen, when it causes
+ * the refcount to go to 0.
+ *
+ * Closures can be used to wait on things both synchronously and asynchronously,
+ * and synchronous and asynchronous use can be mixed without restriction. To
+ * wait synchronously, use closure_sync() - you will sleep until your closure's
+ * refcount hits 1.
+ *
+ * To wait asynchronously, use
+ *   continue_at(cl, next_function, workqueue);
+ *
+ * passing it, as you might expect, the function to run when nothing is pending
+ * and the workqueue to run that function out of.
+ *
+ * continue_at() also, critically, is a macro that returns the calling function.
+ * There's good reason for this.
+ *
+ * To use safely closures asynchronously, they must always have a refcount while
+ * they are running owned by the thread that is running them. Otherwise, suppose
+ * you submit some bios and wish to have a function run when they all complete:
+ *
+ * foo_endio(struct bio *bio, int error)
+ * {
+ *	closure_put(cl);
+ * }
+ *
+ * closure_init(cl);
+ *
+ * do_stuff();
+ * closure_get(cl);
+ * bio1->bi_endio = foo_endio;
+ * bio_submit(bio1);
+ *
+ * do_more_stuff();
+ * closure_get(cl);
+ * bio2->bi_endio = foo_endio;
+ * bio_submit(bio2);
+ *
+ * continue_at(cl, complete_some_read, system_wq);
+ *
+ * If closure's refcount started at 0, complete_some_read() could run before the
+ * second bio was submitted - which is almost always not what you want! More
+ * importantly, it wouldn't be possible to say whether the original thread or
+ * complete_some_read()'s thread owned the closure - and whatever state it was
+ * associated with!
+ *
+ * So, closure_init() initializes a closure's refcount to 1 - and when a
+ * closure_fn is run, the refcount will be reset to 1 first.
+ *
+ * Then, the rule is - if you got the refcount with closure_get(), release it
+ * with closure_put() (i.e, in a bio->bi_endio function). If you have a refcount
+ * on a closure because you called closure_init() or you were run out of a
+ * closure - _always_ use continue_at(). Doing so consistently will help
+ * eliminate an entire class of particularly pernicious races.
+ *
+ * For a closure to wait on an arbitrary event, we need to introduce waitlists:
+ *
+ * struct closure_waitlist list;
+ * closure_wait_event(list, cl, condition);
+ * closure_wake_up(wait_list);
+ *
+ * These work analagously to wait_event() and wake_up() - except that instead of
+ * operating on the current thread (for wait_event()) and lists of threads, they
+ * operate on an explicit closure and lists of closures.
+ *
+ * Because it's a closure we can now wait either synchronously or
+ * asynchronously. closure_wait_event() returns the current value of the
+ * condition, and if it returned false continue_at() or closure_sync() can be
+ * used to wait for it to become true.
+ *
+ * It's useful for waiting on things when you can't sleep in the context in
+ * which you must check the condition (perhaps a spinlock held, or you might be
+ * beneath generic_make_request() - in which case you can't sleep on IO).
+ *
+ * closure_wait_event() will wait either synchronously or asynchronously,
+ * depending on whether the closure is in blocking mode or not. You can pick a
+ * mode explicitly with closure_wait_event_sync() and
+ * closure_wait_event_async(), which do just what you might expect.
+ *
+ * Lastly, you might have a wait list dedicated to a specific event, and have no
+ * need for specifying the condition - you just want to wait until someone runs
+ * closure_wake_up() on the appropriate wait list. In that case, just use
+ * closure_wait(). It will return either true or false, depending on whether the
+ * closure was already on a wait list or not - a closure can only be on one wait
+ * list at a time.
+ *
+ * Parents:
+ *
+ * closure_init() takes two arguments - it takes the closure to initialize, and
+ * a (possibly null) parent.
+ *
+ * If parent is non null, the new closure will have a refcount for its lifetime;
+ * a closure is considered to be "finished" when its refcount hits 0 and the
+ * function to run is null. Hence
+ *
+ * continue_at(cl, NULL, NULL);
+ *
+ * returns up the (spaghetti) stack of closures, precisely like normal return
+ * returns up the C stack. continue_at() with non null fn is better thought of
+ * as doing a tail call.
+ *
+ * All this implies that a closure should typically be embedded in a particular
+ * struct (which its refcount will normally control the lifetime of), and that
+ * struct can very much be thought of as a stack frame.
+ *
+ * Locking:
+ *
+ * Closures are based on work items but they can be thought of as more like
+ * threads - in that like threads and unlike work items they have a well
+ * defined lifetime; they are created (with closure_init()) and eventually
+ * complete after a continue_at(cl, NULL, NULL).
+ *
+ * Suppose you've got some larger structure with a closure embedded in it that's
+ * used for periodically doing garbage collection. You only want one garbage
+ * collection happening at a time, so the natural thing to do is protect it with
+ * a lock. However, it's difficult to use a lock protecting a closure correctly
+ * because the unlock should come after the last continue_to() (additionally, if
+ * you're using the closure asynchronously a mutex won't work since a mutex has
+ * to be unlocked by the same process that locked it).
+ *
+ * So to make it less error prone and more efficient, we also have the ability
+ * to use closures as locks:
+ *
+ * closure_init_unlocked();
+ * closure_trylock();
+ *
+ * That's all we need for trylock() - the last closure_put() implicitly unlocks
+ * it for you.  But for closure_lock(), we also need a wait list:
+ *
+ * struct closure_with_waitlist frobnicator_cl;
+ *
+ * closure_init_unlocked(&frobnicator_cl);
+ * closure_lock(&frobnicator_cl);
+ *
+ * A closure_with_waitlist embeds a closure and a wait list - much like struct
+ * delayed_work embeds a work item and a timer_list. The important thing is, use
+ * it exactly like you would a regular closure and closure_put() will magically
+ * handle everything for you.
+ *
+ * We've got closures that embed timers, too. They're called, appropriately
+ * enough:
+ * struct closure_with_timer;
+ *
+ * This gives you access to closure_delay(). It takes a refcount for a specified
+ * number of jiffies - you could then call closure_sync() (for a slightly
+ * convoluted version of msleep()) or continue_at() - which gives you the same
+ * effect as using a delayed work item, except you can reuse the work_struct
+ * already embedded in struct closure.
+ *
+ * Lastly, there's struct closure_with_waitlist_and_timer. It does what you
+ * probably expect, if you happen to need the features of both. (You don't
+ * really want to know how all this is implemented, but if I've done my job
+ * right you shouldn't have to care).
+ */
+
+struct closure;
+typedef void (closure_fn) (struct closure *);
+
+struct closure_waitlist {
+	struct llist_head	list;
+};
+
+enum closure_type {
+	TYPE_closure				= 0,
+	TYPE_closure_with_waitlist		= 1,
+	TYPE_closure_with_timer			= 2,
+	TYPE_closure_with_waitlist_and_timer	= 3,
+	MAX_CLOSURE_TYPE			= 3,
+};
+
+enum closure_state {
+	/*
+	 * CLOSURE_BLOCKING: Causes closure_wait_event() to block, instead of
+	 * waiting asynchronously
+	 *
+	 * CLOSURE_WAITING: Set iff the closure is on a waitlist. Must be set by
+	 * the thread that owns the closure, and cleared by the thread that's
+	 * waking up the closure.
+	 *
+	 * CLOSURE_SLEEPING: Must be set before a thread uses a closure to sleep
+	 * - indicates that cl->task is valid and closure_put() may wake it up.
+	 * Only set or cleared by the thread that owns the closure.
+	 *
+	 * CLOSURE_TIMER: Analagous to CLOSURE_WAITING, indicates that a closure
+	 * has an outstanding timer. Must be set by the thread that owns the
+	 * closure, and cleared by the timer function when the timer goes off.
+	 *
+	 * The rest are for debugging and don't affect behaviour:
+	 *
+	 * CLOSURE_RUNNING: Set when a closure is running (i.e. by
+	 * closure_init() and when closure_put() runs then next function), and
+	 * must be cleared before remaining hits 0. Primarily to help guard
+	 * against incorrect usage and accidentally transferring references.
+	 * continue_at() and closure_return() clear it for you, if you're doing
+	 * something unusual you can use closure_set_dead() which also helps
+	 * annotate where references are being transferred.
+	 *
+	 * CLOSURE_STACK: Sanity check - remaining should never hit 0 on a
+	 * closure with this flag set
+	 */
+
+	CLOSURE_BITS_START	= (1 << 19),
+	CLOSURE_DESTRUCTOR	= (1 << 19),
+	CLOSURE_BLOCKING	= (1 << 21),
+	CLOSURE_WAITING		= (1 << 23),
+	CLOSURE_SLEEPING	= (1 << 25),
+	CLOSURE_TIMER		= (1 << 27),
+	CLOSURE_RUNNING		= (1 << 29),
+	CLOSURE_STACK		= (1 << 31),
+};
+
+#define CLOSURE_GUARD_MASK					\
+	((CLOSURE_DESTRUCTOR|CLOSURE_BLOCKING|CLOSURE_WAITING|	\
+	  CLOSURE_SLEEPING|CLOSURE_TIMER|CLOSURE_RUNNING|CLOSURE_STACK) << 1)
+
+#define CLOSURE_REMAINING_MASK		(CLOSURE_BITS_START - 1)
+#define CLOSURE_REMAINING_INITIALIZER	(1|CLOSURE_RUNNING)
+
+struct closure {
+	union {
+		struct {
+			struct workqueue_struct *wq;
+			struct task_struct	*task;
+			struct llist_node	list;
+			closure_fn		*fn;
+		};
+		struct work_struct	work;
+	};
+
+	struct closure		*parent;
+
+	atomic_t		remaining;
+
+	enum closure_type	type;
+
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+#define CLOSURE_MAGIC_DEAD	0xc054dead
+#define CLOSURE_MAGIC_ALIVE	0xc054a11e
+
+	unsigned		magic;
+	struct list_head	all;
+	unsigned long		ip;
+	unsigned long		waiting_on;
+#endif
+};
+
+struct closure_with_waitlist {
+	struct closure		cl;
+	struct closure_waitlist	wait;
+};
+
+struct closure_with_timer {
+	struct closure		cl;
+	struct timer_list	timer;
+};
+
+struct closure_with_waitlist_and_timer {
+	struct closure		cl;
+	struct closure_waitlist	wait;
+	struct timer_list	timer;
+};
+
+extern unsigned invalid_closure_type(void);
+
+#define __CLOSURE_TYPE(cl, _t)						\
+	  __builtin_types_compatible_p(typeof(cl), struct _t)		\
+		? TYPE_ ## _t :						\
+
+#define __closure_type(cl)						\
+(									\
+	__CLOSURE_TYPE(cl, closure)					\
+	__CLOSURE_TYPE(cl, closure_with_waitlist)			\
+	__CLOSURE_TYPE(cl, closure_with_timer)				\
+	__CLOSURE_TYPE(cl, closure_with_waitlist_and_timer)		\
+	invalid_closure_type()						\
+)
+
+void closure_sub(struct closure *cl, int v);
+void closure_put(struct closure *cl);
+void closure_queue(struct closure *cl);
+void __closure_wake_up(struct closure_waitlist *list);
+bool closure_wait(struct closure_waitlist *list, struct closure *cl);
+void closure_sync(struct closure *cl);
+
+bool closure_trylock(struct closure *cl, struct closure *parent);
+void __closure_lock(struct closure *cl, struct closure *parent,
+		    struct closure_waitlist *wait_list);
+
+void do_closure_timer_init(struct closure *cl);
+bool __closure_delay(struct closure *cl, unsigned long delay,
+		     struct timer_list *timer);
+void __closure_flush(struct closure *cl, struct timer_list *timer);
+void __closure_flush_sync(struct closure *cl, struct timer_list *timer);
+
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+
+void closure_debug_create(struct closure *cl);
+void closure_debug_destroy(struct closure *cl);
+
+#else
+
+static inline void closure_debug_create(struct closure *cl) {}
+static inline void closure_debug_destroy(struct closure *cl) {}
+
+#endif
+
+static inline void closure_set_ip(struct closure *cl)
+{
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+	cl->ip = _THIS_IP_;
+#endif
+}
+
+static inline void closure_set_ret_ip(struct closure *cl)
+{
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+	cl->ip = _RET_IP_;
+#endif
+}
+
+static inline void closure_get(struct closure *cl)
+{
+#ifdef CONFIG_BCACHE_CLOSURES_DEBUG
+	BUG_ON((atomic_inc_return(&cl->remaining) &
+		CLOSURE_REMAINING_MASK) <= 1);
+#else
+	atomic_inc(&cl->remaining);
+#endif
+}
+
+static inline void closure_set_stopped(struct closure *cl)
+{
+	atomic_sub(CLOSURE_RUNNING, &cl->remaining);
+}
+
+static inline bool closure_is_stopped(struct closure *cl)
+{
+	return !(atomic_read(&cl->remaining) & CLOSURE_RUNNING);
+}
+
+static inline bool closure_is_unlocked(struct closure *cl)
+{
+	return atomic_read(&cl->remaining) == -1;
+}
+
+static inline void do_closure_init(struct closure *cl, struct closure *parent,
+				   bool running)
+{
+	switch (cl->type) {
+	case TYPE_closure_with_timer:
+	case TYPE_closure_with_waitlist_and_timer:
+		do_closure_timer_init(cl);
+	default:
+		break;
+	}
+
+	cl->parent = parent;
+	if (parent)
+		closure_get(parent);
+
+	if (running) {
+		closure_debug_create(cl);
+		atomic_set(&cl->remaining, CLOSURE_REMAINING_INITIALIZER);
+	} else
+		atomic_set(&cl->remaining, -1);
+
+	closure_set_ip(cl);
+}
+
+/*
+ * Hack to get at the embedded closure if there is one, by doing an unsafe cast:
+ * the result of __closure_type() is thrown away, it's used merely for type
+ * checking.
+ */
+#define __to_internal_closure(cl)				\
+({								\
+	BUILD_BUG_ON(__closure_type(*cl) > MAX_CLOSURE_TYPE);	\
+	(struct closure *) cl;					\
+})
+
+#define closure_init_type(cl, parent, running)			\
+do {								\
+	struct closure *_cl = __to_internal_closure(cl);	\
+	_cl->type = __closure_type(*(cl));			\
+	do_closure_init(_cl, parent, running);			\
+} while (0)
+
+/**
+ * __closure_init() - Initialize a closure, skipping the memset()
+ *
+ * May be used instead of closure_init() when memory has already been zeroed.
+ */
+#define __closure_init(cl, parent)				\
+	closure_init_type(cl, parent, true)
+
+/**
+ * closure_init() - Initialize a closure, setting the refcount to 1
+ * @cl:		closure to initialize
+ * @parent:	parent of the new closure. cl will take a refcount on it for its
+ *		lifetime; may be NULL.
+ */
+#define closure_init(cl, parent)				\
+do {								\
+	memset((cl), 0, sizeof(*(cl)));				\
+	__closure_init(cl, parent);				\
+} while (0)
+
+static inline void closure_init_stack(struct closure *cl)
+{
+	memset(cl, 0, sizeof(struct closure));
+	atomic_set(&cl->remaining, CLOSURE_REMAINING_INITIALIZER|
+		   CLOSURE_BLOCKING|CLOSURE_STACK);
+}
+
+/**
+ * closure_init_unlocked() - Initialize a closure but leave it unlocked.
+ * @cl:		closure to initialize
+ *
+ * For when the closure will be used as a lock. The closure may not be used
+ * until after a closure_lock() or closure_trylock().
+ */
+#define closure_init_unlocked(cl)				\
+do {								\
+	memset((cl), 0, sizeof(*(cl)));				\
+	closure_init_type(cl, NULL, false);			\
+} while (0)
+
+/**
+ * closure_lock() - lock and initialize a closure.
+ * @cl:		the closure to lock
+ * @parent:	the new parent for this closure
+ *
+ * The closure must be of one of the types that has a waitlist (otherwise we
+ * wouldn't be able to sleep on contention).
+ *
+ * @parent has exactly the same meaning as in closure_init(); if non null, the
+ * closure will take a reference on @parent which will be released when it is
+ * unlocked.
+ */
+#define closure_lock(cl, parent)				\
+	__closure_lock(__to_internal_closure(cl), parent, &(cl)->wait)
+
+/**
+ * closure_delay() - delay some number of jiffies
+ * @cl:		the closure that will sleep
+ * @delay:	the delay in jiffies
+ *
+ * Takes a refcount on @cl which will be released after @delay jiffies; this may
+ * be used to have a function run after a delay with continue_at(), or
+ * closure_sync() may be used for a convoluted version of msleep().
+ */
+#define closure_delay(cl, delay)			\
+	__closure_delay(__to_internal_closure(cl), delay, &(cl)->timer)
+
+#define closure_flush(cl)				\
+	__closure_flush(__to_internal_closure(cl), &(cl)->timer)
+
+#define closure_flush_sync(cl)				\
+	__closure_flush_sync(__to_internal_closure(cl), &(cl)->timer)
+
+static inline void __closure_end_sleep(struct closure *cl)
+{
+	__set_current_state(TASK_RUNNING);
+
+	if (atomic_read(&cl->remaining) & CLOSURE_SLEEPING)
+		atomic_sub(CLOSURE_SLEEPING, &cl->remaining);
+}
+
+static inline void __closure_start_sleep(struct closure *cl)
+{
+	closure_set_ip(cl);
+	cl->task = current;
+	set_current_state(TASK_UNINTERRUPTIBLE);
+
+	if (!(atomic_read(&cl->remaining) & CLOSURE_SLEEPING))
+		atomic_add(CLOSURE_SLEEPING, &cl->remaining);
+}
+
+/**
+ * closure_blocking() - returns true if the closure is in blocking mode.
+ *
+ * If a closure is in blocking mode, closure_wait_event() will sleep until the
+ * condition is true instead of waiting asynchronously.
+ */
+static inline bool closure_blocking(struct closure *cl)
+{
+	return atomic_read(&cl->remaining) & CLOSURE_BLOCKING;
+}
+
+/**
+ * set_closure_blocking() - put a closure in blocking mode.
+ *
+ * If a closure is in blocking mode, closure_wait_event() will sleep until the
+ * condition is true instead of waiting asynchronously.
+ *
+ * Not thread safe - can only be called by the thread running the closure.
+ */
+static inline void set_closure_blocking(struct closure *cl)
+{
+	if (!closure_blocking(cl))
+		atomic_add(CLOSURE_BLOCKING, &cl->remaining);
+}
+
+/*
+ * Not thread safe - can only be called by the thread running the closure.
+ */
+static inline void clear_closure_blocking(struct closure *cl)
+{
+	if (closure_blocking(cl))
+		atomic_sub(CLOSURE_BLOCKING, &cl->remaining);
+}
+
+/**
+ * closure_wake_up() - wake up all closures on a wait list.
+ */
+static inline void closure_wake_up(struct closure_waitlist *list)
+{
+	smp_mb();
+	__closure_wake_up(list);
+}
+
+/*
+ * Wait on an event, synchronously or asynchronously - analogous to wait_event()
+ * but for closures.
+ *
+ * The loop is oddly structured so as to avoid a race; we must check the
+ * condition again after we've added ourself to the waitlist. We know if we were
+ * already on the waitlist because closure_wait() returns false; thus, we only
+ * schedule or break if closure_wait() returns false. If it returns true, we
+ * just loop again - rechecking the condition.
+ *
+ * The __closure_wake_up() is necessary because we may race with the event
+ * becoming true; i.e. we see event false -> wait -> recheck condition, but the
+ * thread that made the event true may have called closure_wake_up() before we
+ * added ourself to the wait list.
+ *
+ * We have to call closure_sync() at the end instead of just
+ * __closure_end_sleep() because a different thread might've called
+ * closure_wake_up() before us and gotten preempted before they dropped the
+ * refcount on our closure. If this was a stack allocated closure, that would be
+ * bad.
+ */
+#define __closure_wait_event(list, cl, condition, _block)		\
+({									\
+	bool block = _block;						\
+	typeof(condition) ret;						\
+									\
+	while (1) {							\
+		ret = (condition);					\
+		if (ret) {						\
+			__closure_wake_up(list);			\
+			if (block)					\
+				closure_sync(cl);			\
+									\
+			break;						\
+		}							\
+									\
+		if (block)						\
+			__closure_start_sleep(cl);			\
+									\
+		if (!closure_wait(list, cl)) {				\
+			if (!block)					\
+				break;					\
+									\
+			schedule();					\
+		}							\
+	}								\
+									\
+	ret;								\
+})
+
+/**
+ * closure_wait_event() - wait on a condition, synchronously or asynchronously.
+ * @list:	the wait list to wait on
+ * @cl:		the closure that is doing the waiting
+ * @condition:	a C expression for the event to wait for
+ *
+ * If the closure is in blocking mode, sleeps until the @condition evaluates to
+ * true - exactly like wait_event().
+ *
+ * If the closure is not in blocking mode, waits asynchronously; if the
+ * condition is currently false the @cl is put onto @list and returns. @list
+ * owns a refcount on @cl; closure_sync() or continue_at() may be used later to
+ * wait for another thread to wake up @list, which drops the refcount on @cl.
+ *
+ * Returns the value of @condition; @cl will be on @list iff @condition was
+ * false.
+ *
+ * closure_wake_up(@list) must be called after changing any variable that could
+ * cause @condition to become true.
+ */
+#define closure_wait_event(list, cl, condition)				\
+	__closure_wait_event(list, cl, condition, closure_blocking(cl))
+
+#define closure_wait_event_async(list, cl, condition)			\
+	__closure_wait_event(list, cl, condition, false)
+
+#define closure_wait_event_sync(list, cl, condition)			\
+	__closure_wait_event(list, cl, condition, true)
+
+static inline void set_closure_fn(struct closure *cl, closure_fn *fn,
+				  struct workqueue_struct *wq)
+{
+	BUG_ON(object_is_on_stack(cl));
+	closure_set_ip(cl);
+	cl->fn = fn;
+	cl->wq = wq;
+	/* between atomic_dec() in closure_put() */
+	smp_mb__before_atomic_dec();
+}
+
+#define continue_at(_cl, _fn, _wq)					\
+do {									\
+	set_closure_fn(_cl, _fn, _wq);					\
+	closure_sub(_cl, CLOSURE_RUNNING + 1);				\
+	return;								\
+} while (0)
+
+#define closure_return(_cl)	continue_at((_cl), NULL, NULL)
+
+#define continue_at_nobarrier(_cl, _fn, _wq)				\
+do {									\
+	set_closure_fn(_cl, _fn, _wq);					\
+	closure_queue(cl);						\
+	return;								\
+} while (0)
+
+#define closure_return_with_destructor(_cl, _destructor)		\
+do {									\
+	set_closure_fn(_cl, _destructor, NULL);				\
+	closure_sub(_cl, CLOSURE_RUNNING - CLOSURE_DESTRUCTOR + 1);	\
+	return;								\
+} while (0)
+
+static inline void closure_call(struct closure *cl, closure_fn fn,
+				struct workqueue_struct *wq,
+				struct closure *parent)
+{
+	closure_init(cl, parent);
+	continue_at_nobarrier(cl, fn, wq);
+}
+
+static inline void closure_trylock_call(struct closure *cl, closure_fn fn,
+					struct workqueue_struct *wq,
+					struct closure *parent)
+{
+	if (closure_trylock(cl, parent))
+		continue_at_nobarrier(cl, fn, wq);
+}
+
+#endif /* _LINUX_CLOSURE_H */

drivers/md/bcache/debug.c

@@ -0,0 +1,563 @@
+/*
+ * Assorted bcache debug code
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+
+#include <linux/console.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/seq_file.h>
+
+static struct dentry *debug;
+
+const char *bch_ptr_status(struct cache_set *c, const struct bkey *k)
+{
+	unsigned i;
+
+	for (i = 0; i < KEY_PTRS(k); i++)
+		if (ptr_available(c, k, i)) {
+			struct cache *ca = PTR_CACHE(c, k, i);
+			size_t bucket = PTR_BUCKET_NR(c, k, i);
+			size_t r = bucket_remainder(c, PTR_OFFSET(k, i));
+
+			if (KEY_SIZE(k) + r > c->sb.bucket_size)
+				return "bad, length too big";
+			if (bucket <  ca->sb.first_bucket)
+				return "bad, short offset";
+			if (bucket >= ca->sb.nbuckets)
+				return "bad, offset past end of device";
+			if (ptr_stale(c, k, i))
+				return "stale";
+		}
+
+	if (!bkey_cmp(k, &ZERO_KEY))
+		return "bad, null key";
+	if (!KEY_PTRS(k))
+		return "bad, no pointers";
+	if (!KEY_SIZE(k))
+		return "zeroed key";
+	return "";
+}
+
+struct keyprint_hack bch_pkey(const struct bkey *k)
+{
+	unsigned i = 0;
+	struct keyprint_hack r;
+	char *out = r.s, *end = r.s + KEYHACK_SIZE;
+
+#define p(...)	(out += scnprintf(out, end - out, __VA_ARGS__))
+
+	p("%llu:%llu len %llu -> [", KEY_INODE(k), KEY_OFFSET(k), KEY_SIZE(k));
+
+	if (KEY_PTRS(k))
+		while (1) {
+			p("%llu:%llu gen %llu",
+			  PTR_DEV(k, i), PTR_OFFSET(k, i), PTR_GEN(k, i));
+
+			if (++i == KEY_PTRS(k))
+				break;
+
+			p(", ");
+		}
+
+	p("]");
+
+	if (KEY_DIRTY(k))
+		p(" dirty");
+	if (KEY_CSUM(k))
+		p(" cs%llu %llx", KEY_CSUM(k), k->ptr[1]);
+#undef p
+	return r;
+}
+
+struct keyprint_hack bch_pbtree(const struct btree *b)
+{
+	struct keyprint_hack r;
+
+	snprintf(r.s, 40, "%li level %i/%i", PTR_BUCKET_NR(b->c, &b->key, 0),
+		 b->level, b->c->root ? b->c->root->level : -1);
+	return r;
+}
+
+#if defined(CONFIG_BCACHE_DEBUG) || defined(CONFIG_BCACHE_EDEBUG)
+
+static bool skipped_backwards(struct btree *b, struct bkey *k)
+{
+	return bkey_cmp(k, (!b->level)
+			? &START_KEY(bkey_next(k))
+			: bkey_next(k)) > 0;
+}
+
+static void dump_bset(struct btree *b, struct bset *i)
+{
+	struct bkey *k;
+	unsigned j;
+
+	for (k = i->start; k < end(i); k = bkey_next(k)) {
+		printk(KERN_ERR "block %zu key %zi/%u: %s", index(i, b),
+		       (uint64_t *) k - i->d, i->keys, pkey(k));
+
+		for (j = 0; j < KEY_PTRS(k); j++) {
+			size_t n = PTR_BUCKET_NR(b->c, k, j);
+			printk(" bucket %zu", n);
+
+			if (n >= b->c->sb.first_bucket && n < b->c->sb.nbuckets)
+				printk(" prio %i",
+				       PTR_BUCKET(b->c, k, j)->prio);
+		}
+
+		printk(" %s\n", bch_ptr_status(b->c, k));
+
+		if (bkey_next(k) < end(i) &&
+		    skipped_backwards(b, k))
+			printk(KERN_ERR "Key skipped backwards\n");
+	}
+}
+
+#endif
+
+#ifdef CONFIG_BCACHE_DEBUG
+
+void bch_btree_verify(struct btree *b, struct bset *new)
+{
+	struct btree *v = b->c->verify_data;
+	struct closure cl;
+	closure_init_stack(&cl);
+
+	if (!b->c->verify)
+		return;
+
+	closure_wait_event(&b->io.wait, &cl,
+			   atomic_read(&b->io.cl.remaining) == -1);
+
+	mutex_lock(&b->c->verify_lock);
+
+	bkey_copy(&v->key, &b->key);
+	v->written = 0;
+	v->level = b->level;
+
+	bch_btree_read(v);
+	closure_wait_event(&v->io.wait, &cl,
+			   atomic_read(&b->io.cl.remaining) == -1);
+
+	if (new->keys != v->sets[0].data->keys ||
+	    memcmp(new->start,
+		   v->sets[0].data->start,
+		   (void *) end(new) - (void *) new->start)) {
+		unsigned i, j;
+
+		console_lock();
+
+		printk(KERN_ERR "*** original memory node:\n");
+		for (i = 0; i <= b->nsets; i++)
+			dump_bset(b, b->sets[i].data);
+
+		printk(KERN_ERR "*** sorted memory node:\n");
+		dump_bset(b, new);
+
+		printk(KERN_ERR "*** on disk node:\n");
+		dump_bset(v, v->sets[0].data);
+
+		for (j = 0; j < new->keys; j++)
+			if (new->d[j] != v->sets[0].data->d[j])
+				break;
+
+		console_unlock();
+		panic("verify failed at %u\n", j);
+	}
+
+	mutex_unlock(&b->c->verify_lock);
+}
+
+static void data_verify_endio(struct bio *bio, int error)
+{
+	struct closure *cl = bio->bi_private;
+	closure_put(cl);
+}
+
+void bch_data_verify(struct search *s)
+{
+	char name[BDEVNAME_SIZE];
+	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+	struct closure *cl = &s->cl;
+	struct bio *check;
+	struct bio_vec *bv;
+	int i;
+
+	if (!s->unaligned_bvec)
+		bio_for_each_segment(bv, s->orig_bio, i)
+			bv->bv_offset = 0, bv->bv_len = PAGE_SIZE;
+
+	check = bio_clone(s->orig_bio, GFP_NOIO);
+	if (!check)
+		return;
+
+	if (bio_alloc_pages(check, GFP_NOIO))
+		goto out_put;
+
+	check->bi_rw		= READ_SYNC;
+	check->bi_private	= cl;
+	check->bi_end_io	= data_verify_endio;
+
+	closure_bio_submit(check, cl, &dc->disk);
+	closure_sync(cl);
+
+	bio_for_each_segment(bv, s->orig_bio, i) {
+		void *p1 = kmap(bv->bv_page);
+		void *p2 = kmap(check->bi_io_vec[i].bv_page);
+
+		if (memcmp(p1 + bv->bv_offset,
+			   p2 + bv->bv_offset,
+			   bv->bv_len))
+			printk(KERN_ERR "bcache (%s): verify failed"
+			       " at sector %llu\n",
+			       bdevname(dc->bdev, name),
+			       (uint64_t) s->orig_bio->bi_sector);
+
+		kunmap(bv->bv_page);
+		kunmap(check->bi_io_vec[i].bv_page);
+	}
+
+	__bio_for_each_segment(bv, check, i, 0)
+		__free_page(bv->bv_page);
+out_put:
+	bio_put(check);
+}
+
+#endif
+
+#ifdef CONFIG_BCACHE_EDEBUG
+
+unsigned bch_count_data(struct btree *b)
+{
+	unsigned ret = 0;
+	struct btree_iter iter;
+	struct bkey *k;
+
+	if (!b->level)
+		for_each_key(b, k, &iter)
+			ret += KEY_SIZE(k);
+	return ret;
+}
+
+static void vdump_bucket_and_panic(struct btree *b, const char *fmt,
+				   va_list args)
+{
+	unsigned i;
+
+	console_lock();
+
+	for (i = 0; i <= b->nsets; i++)
+		dump_bset(b, b->sets[i].data);
+
+	vprintk(fmt, args);
+
+	console_unlock();
+
+	panic("at %s\n", pbtree(b));
+}
+
+void bch_check_key_order_msg(struct btree *b, struct bset *i,
+			     const char *fmt, ...)
+{
+	struct bkey *k;
+
+	if (!i->keys)
+		return;
+
+	for (k = i->start; bkey_next(k) < end(i); k = bkey_next(k))
+		if (skipped_backwards(b, k)) {
+			va_list args;
+			va_start(args, fmt);
+
+			vdump_bucket_and_panic(b, fmt, args);
+			va_end(args);
+		}
+}
+
+void bch_check_keys(struct btree *b, const char *fmt, ...)
+{
+	va_list args;
+	struct bkey *k, *p = NULL;
+	struct btree_iter iter;
+
+	if (b->level)
+		return;
+
+	for_each_key(b, k, &iter) {
+		if (p && bkey_cmp(&START_KEY(p), &START_KEY(k)) > 0) {
+			printk(KERN_ERR "Keys out of order:\n");
+			goto bug;
+		}
+
+		if (bch_ptr_invalid(b, k))
+			continue;
+
+		if (p && bkey_cmp(p, &START_KEY(k)) > 0) {
+			printk(KERN_ERR "Overlapping keys:\n");
+			goto bug;
+		}
+		p = k;
+	}
+	return;
+bug:
+	va_start(args, fmt);
+	vdump_bucket_and_panic(b, fmt, args);
+	va_end(args);
+}
+
+#endif
+
+#ifdef CONFIG_DEBUG_FS
+
+/* XXX: cache set refcounting */
+
+struct dump_iterator {
+	char			buf[PAGE_SIZE];
+	size_t			bytes;
+	struct cache_set	*c;
+	struct keybuf		keys;
+};
+
+static bool dump_pred(struct keybuf *buf, struct bkey *k)
+{
+	return true;
+}
+
+static ssize_t bch_dump_read(struct file *file, char __user *buf,
+			     size_t size, loff_t *ppos)
+{
+	struct dump_iterator *i = file->private_data;
+	ssize_t ret = 0;
+
+	while (size) {
+		struct keybuf_key *w;
+		unsigned bytes = min(i->bytes, size);
+
+		int err = copy_to_user(buf, i->buf, bytes);
+		if (err)
+			return err;
+
+		ret	 += bytes;
+		buf	 += bytes;
+		size	 -= bytes;
+		i->bytes -= bytes;
+		memmove(i->buf, i->buf + bytes, i->bytes);
+
+		if (i->bytes)
+			break;
+
+		w = bch_keybuf_next_rescan(i->c, &i->keys, &MAX_KEY);
+		if (!w)
+			break;
+
+		i->bytes = snprintf(i->buf, PAGE_SIZE, "%s\n", pkey(&w->key));
+		bch_keybuf_del(&i->keys, w);
+	}
+
+	return ret;
+}
+
+static int bch_dump_open(struct inode *inode, struct file *file)
+{
+	struct cache_set *c = inode->i_private;
+	struct dump_iterator *i;
+
+	i = kzalloc(sizeof(struct dump_iterator), GFP_KERNEL);
+	if (!i)
+		return -ENOMEM;
+
+	file->private_data = i;
+	i->c = c;
+	bch_keybuf_init(&i->keys, dump_pred);
+	i->keys.last_scanned = KEY(0, 0, 0);
+
+	return 0;
+}
+
+static int bch_dump_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static const struct file_operations cache_set_debug_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch_dump_open,
+	.read		= bch_dump_read,
+	.release	= bch_dump_release
+};
+
+void bch_debug_init_cache_set(struct cache_set *c)
+{
+	if (!IS_ERR_OR_NULL(debug)) {
+		char name[50];
+		snprintf(name, 50, "bcache-%pU", c->sb.set_uuid);
+
+		c->debug = debugfs_create_file(name, 0400, debug, c,
+					       &cache_set_debug_ops);
+	}
+}
+
+#endif
+
+#ifdef CONFIG_BCACHE_DEBUG
+static ssize_t btree_fuzz(struct kobject *k, struct kobj_attribute *a,
+			  const char *buffer, size_t size)
+{
+	void dump(struct btree *b)
+	{
+		struct bset *i;
+
+		for (i = b->sets[0].data;
+		     index(i, b) < btree_blocks(b) &&
+		     i->seq == b->sets[0].data->seq;
+		     i = ((void *) i) + set_blocks(i, b->c) * block_bytes(b->c))
+			dump_bset(b, i);
+	}
+
+	struct cache_sb *sb;
+	struct cache_set *c;
+	struct btree *all[3], *b, *fill, *orig;
+	int j;
+
+	struct btree_op op;
+	bch_btree_op_init_stack(&op);
+
+	sb = kzalloc(sizeof(struct cache_sb), GFP_KERNEL);
+	if (!sb)
+		return -ENOMEM;
+
+	sb->bucket_size = 128;
+	sb->block_size = 4;
+
+	c = bch_cache_set_alloc(sb);
+	if (!c)
+		return -ENOMEM;
+
+	for (j = 0; j < 3; j++) {
+		BUG_ON(list_empty(&c->btree_cache));
+		all[j] = list_first_entry(&c->btree_cache, struct btree, list);
+		list_del_init(&all[j]->list);
+
+		all[j]->key = KEY(0, 0, c->sb.bucket_size);
+		bkey_copy_key(&all[j]->key, &MAX_KEY);
+	}
+
+	b = all[0];
+	fill = all[1];
+	orig = all[2];
+
+	while (1) {
+		for (j = 0; j < 3; j++)
+			all[j]->written = all[j]->nsets = 0;
+
+		bch_bset_init_next(b);
+
+		while (1) {
+			struct bset *i = write_block(b);
+			struct bkey *k = op.keys.top;
+			unsigned rand;
+
+			bkey_init(k);
+			rand = get_random_int();
+
+			op.type = rand & 1
+				? BTREE_INSERT
+				: BTREE_REPLACE;
+			rand >>= 1;
+
+			SET_KEY_SIZE(k, bucket_remainder(c, rand));
+			rand >>= c->bucket_bits;
+			rand &= 1024 * 512 - 1;
+			rand += c->sb.bucket_size;
+			SET_KEY_OFFSET(k, rand);
+#if 0
+			SET_KEY_PTRS(k, 1);
+#endif
+			bch_keylist_push(&op.keys);
+			bch_btree_insert_keys(b, &op);
+
+			if (should_split(b) ||
+			    set_blocks(i, b->c) !=
+			    __set_blocks(i, i->keys + 15, b->c)) {
+				i->csum = csum_set(i);
+
+				memcpy(write_block(fill),
+				       i, set_bytes(i));
+
+				b->written += set_blocks(i, b->c);
+				fill->written = b->written;
+				if (b->written == btree_blocks(b))
+					break;
+
+				bch_btree_sort_lazy(b);
+				bch_bset_init_next(b);
+			}
+		}
+
+		memcpy(orig->sets[0].data,
+		       fill->sets[0].data,
+		       btree_bytes(c));
+
+		bch_btree_sort(b);
+		fill->written = 0;
+		bch_btree_read_done(&fill->io.cl);
+
+		if (b->sets[0].data->keys != fill->sets[0].data->keys ||
+		    memcmp(b->sets[0].data->start,
+			   fill->sets[0].data->start,
+			   b->sets[0].data->keys * sizeof(uint64_t))) {
+			struct bset *i = b->sets[0].data;
+			struct bkey *k, *l;
+
+			for (k = i->start,
+			     l = fill->sets[0].data->start;
+			     k < end(i);
+			     k = bkey_next(k), l = bkey_next(l))
+				if (bkey_cmp(k, l) ||
+				    KEY_SIZE(k) != KEY_SIZE(l))
+					pr_err("key %zi differs: %s "
+					       "!= %s", (uint64_t *) k - i->d,
+					       pkey(k), pkey(l));
+
+			for (j = 0; j < 3; j++) {
+				pr_err("**** Set %i ****", j);
+				dump(all[j]);
+			}
+			panic("\n");
+		}
+
+		pr_info("fuzz complete: %i keys", b->sets[0].data->keys);
+	}
+}
+
+kobj_attribute_write(fuzz, btree_fuzz);
+#endif
+
+void bch_debug_exit(void)
+{
+	if (!IS_ERR_OR_NULL(debug))
+		debugfs_remove_recursive(debug);
+}
+
+int __init bch_debug_init(struct kobject *kobj)
+{
+	int ret = 0;
+#ifdef CONFIG_BCACHE_DEBUG
+	ret = sysfs_create_file(kobj, &ksysfs_fuzz.attr);
+	if (ret)
+		return ret;
+#endif
+
+	debug = debugfs_create_dir("bcache", NULL);
+	return ret;
+}

drivers/md/bcache/debug.h

@@ -0,0 +1,54 @@
+#ifndef _BCACHE_DEBUG_H
+#define _BCACHE_DEBUG_H
+
+/* Btree/bkey debug printing */
+
+#define KEYHACK_SIZE 80
+struct keyprint_hack {
+	char s[KEYHACK_SIZE];
+};
+
+struct keyprint_hack bch_pkey(const struct bkey *k);
+struct keyprint_hack bch_pbtree(const struct btree *b);
+#define pkey(k)		(&bch_pkey(k).s[0])
+#define pbtree(b)	(&bch_pbtree(b).s[0])
+
+#ifdef CONFIG_BCACHE_EDEBUG
+
+unsigned bch_count_data(struct btree *);
+void bch_check_key_order_msg(struct btree *, struct bset *, const char *, ...);
+void bch_check_keys(struct btree *, const char *, ...);
+
+#define bch_check_key_order(b, i)			\
+	bch_check_key_order_msg(b, i, "keys out of order")
+#define EBUG_ON(cond)		BUG_ON(cond)
+
+#else /* EDEBUG */
+
+#define bch_count_data(b)				0
+#define bch_check_key_order(b, i)			do {} while (0)
+#define bch_check_key_order_msg(b, i, ...)		do {} while (0)
+#define bch_check_keys(b, ...)				do {} while (0)
+#define EBUG_ON(cond)					do {} while (0)
+
+#endif
+
+#ifdef CONFIG_BCACHE_DEBUG
+
+void bch_btree_verify(struct btree *, struct bset *);
+void bch_data_verify(struct search *);
+
+#else /* DEBUG */
+
+static inline void bch_btree_verify(struct btree *b, struct bset *i) {}
+static inline void bch_data_verify(struct search *s) {};
+
+#endif
+
+#ifdef CONFIG_DEBUG_FS
+void bch_debug_init_cache_set(struct cache_set *);
+#else
+static inline void bch_debug_init_cache_set(struct cache_set *c) {}
+#endif
+
+#endif

drivers/md/bcache/io.c

@@ -0,0 +1,390 @@
+/*
+ * Some low level IO code, and hacks for various block layer limitations
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "bset.h"
+#include "debug.h"
+
+static void bch_bi_idx_hack_endio(struct bio *bio, int error)
+{
+	struct bio *p = bio->bi_private;
+
+	bio_endio(p, error);
+	bio_put(bio);
+}
+
+static void bch_generic_make_request_hack(struct bio *bio)
+{
+	if (bio->bi_idx) {
+		struct bio *clone = bio_alloc(GFP_NOIO, bio_segments(bio));
+
+		memcpy(clone->bi_io_vec,
+		       bio_iovec(bio),
+		       bio_segments(bio) * sizeof(struct bio_vec));
+
+		clone->bi_sector	= bio->bi_sector;
+		clone->bi_bdev		= bio->bi_bdev;
+		clone->bi_rw		= bio->bi_rw;
+		clone->bi_vcnt		= bio_segments(bio);
+		clone->bi_size		= bio->bi_size;
+
+		clone->bi_private	= bio;
+		clone->bi_end_io	= bch_bi_idx_hack_endio;
+
+		bio = clone;
+	}
+
+	generic_make_request(bio);
+}
+
+/**
+ * bch_bio_split - split a bio
+ * @bio:	bio to split
+ * @sectors:	number of sectors to split from the front of @bio
+ * @gfp:	gfp mask
+ * @bs:		bio set to allocate from
+ *
+ * Allocates and returns a new bio which represents @sectors from the start of
+ * @bio, and updates @bio to represent the remaining sectors.
+ *
+ * If bio_sectors(@bio) was less than or equal to @sectors, returns @bio
+ * unchanged.
+ *
+ * The newly allocated bio will point to @bio's bi_io_vec, if the split was on a
+ * bvec boundry; it is the caller's responsibility to ensure that @bio is not
+ * freed before the split.
+ *
+ * If bch_bio_split() is running under generic_make_request(), it's not safe to
+ * allocate more than one bio from the same bio set. Therefore, if it is running
+ * under generic_make_request() it masks out __GFP_WAIT when doing the
+ * allocation. The caller must check for failure if there's any possibility of
+ * it being called from under generic_make_request(); it is then the caller's
+ * responsibility to retry from a safe context (by e.g. punting to workqueue).
+ */
+struct bio *bch_bio_split(struct bio *bio, int sectors,
+			  gfp_t gfp, struct bio_set *bs)
+{
+	unsigned idx = bio->bi_idx, vcnt = 0, nbytes = sectors << 9;
+	struct bio_vec *bv;
+	struct bio *ret = NULL;
+
+	BUG_ON(sectors <= 0);
+
+	/*
+	 * If we're being called from underneath generic_make_request() and we
+	 * already allocated any bios from this bio set, we risk deadlock if we
+	 * use the mempool. So instead, we possibly fail and let the caller punt
+	 * to workqueue or somesuch and retry in a safe context.
+	 */
+	if (current->bio_list)
+		gfp &= ~__GFP_WAIT;
+
+	if (sectors >= bio_sectors(bio))
+		return bio;
+
+	if (bio->bi_rw & REQ_DISCARD) {
+		ret = bio_alloc_bioset(gfp, 1, bs);
+		idx = 0;
+		goto out;
+	}
+
+	bio_for_each_segment(bv, bio, idx) {
+		vcnt = idx - bio->bi_idx;
+
+		if (!nbytes) {
+			ret = bio_alloc_bioset(gfp, vcnt, bs);
+			if (!ret)
+				return NULL;
+
+			memcpy(ret->bi_io_vec, bio_iovec(bio),
+			       sizeof(struct bio_vec) * vcnt);
+
+			break;
+		} else if (nbytes < bv->bv_len) {
+			ret = bio_alloc_bioset(gfp, ++vcnt, bs);
+			if (!ret)
+				return NULL;
+
+			memcpy(ret->bi_io_vec, bio_iovec(bio),
+			       sizeof(struct bio_vec) * vcnt);
+
+			ret->bi_io_vec[vcnt - 1].bv_len = nbytes;
+			bv->bv_offset	+= nbytes;
+			bv->bv_len	-= nbytes;
+			break;
+		}
+
+		nbytes -= bv->bv_len;
+	}
+out:
+	ret->bi_bdev	= bio->bi_bdev;
+	ret->bi_sector	= bio->bi_sector;
+	ret->bi_size	= sectors << 9;
+	ret->bi_rw	= bio->bi_rw;
+	ret->bi_vcnt	= vcnt;
+	ret->bi_max_vecs = vcnt;
+
+	bio->bi_sector	+= sectors;
+	bio->bi_size	-= sectors << 9;
+	bio->bi_idx	 = idx;
+
+	if (bio_integrity(bio)) {
+		if (bio_integrity_clone(ret, bio, gfp)) {
+			bio_put(ret);
+			return NULL;
+		}
+
+		bio_integrity_trim(ret, 0, bio_sectors(ret));
+		bio_integrity_trim(bio, bio_sectors(ret), bio_sectors(bio));
+	}
+
+	return ret;
+}
+
+static unsigned bch_bio_max_sectors(struct bio *bio)
+{
+	unsigned ret = bio_sectors(bio);
+	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+	struct bio_vec *bv, *end = bio_iovec(bio) +
+		min_t(int, bio_segments(bio), queue_max_segments(q));
+
+	struct bvec_merge_data bvm = {
+		.bi_bdev	= bio->bi_bdev,
+		.bi_sector	= bio->bi_sector,
+		.bi_size	= 0,
+		.bi_rw		= bio->bi_rw,
+	};
+
+	if (bio->bi_rw & REQ_DISCARD)
+		return min(ret, q->limits.max_discard_sectors);
+
+	if (bio_segments(bio) > queue_max_segments(q) ||
+	    q->merge_bvec_fn) {
+		ret = 0;
+
+		for (bv = bio_iovec(bio); bv < end; bv++) {
+			if (q->merge_bvec_fn &&
+			    q->merge_bvec_fn(q, &bvm, bv) < (int) bv->bv_len)
+				break;
+
+			ret		+= bv->bv_len >> 9;
+			bvm.bi_size	+= bv->bv_len;
+		}
+
+		if (ret >= (BIO_MAX_PAGES * PAGE_SIZE) >> 9)
+			return (BIO_MAX_PAGES * PAGE_SIZE) >> 9;
+	}
+
+	ret = min(ret, queue_max_sectors(q));
+
+	WARN_ON(!ret);
+	ret = max_t(int, ret, bio_iovec(bio)->bv_len >> 9);
+
+	return ret;
+}
+
+static void bch_bio_submit_split_done(struct closure *cl)
+{
+	struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
+
+	s->bio->bi_end_io = s->bi_end_io;
+	s->bio->bi_private = s->bi_private;
+	bio_endio(s->bio, 0);
+
+	closure_debug_destroy(&s->cl);
+	mempool_free(s, s->p->bio_split_hook);
+}
+
+static void bch_bio_submit_split_endio(struct bio *bio, int error)
+{
+	struct closure *cl = bio->bi_private;
+	struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
+
+	if (error)
+		clear_bit(BIO_UPTODATE, &s->bio->bi_flags);
+
+	bio_put(bio);
+	closure_put(cl);
+}
+
+static void __bch_bio_submit_split(struct closure *cl)
+{
+	struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
+	struct bio *bio = s->bio, *n;
+
+	do {
+		n = bch_bio_split(bio, bch_bio_max_sectors(bio),
+				  GFP_NOIO, s->p->bio_split);
+		if (!n)
+			continue_at(cl, __bch_bio_submit_split, system_wq);
+
+		n->bi_end_io	= bch_bio_submit_split_endio;
+		n->bi_private	= cl;
+
+		closure_get(cl);
+		bch_generic_make_request_hack(n);
+	} while (n != bio);
+
+	continue_at(cl, bch_bio_submit_split_done, NULL);
+}
+
+void bch_generic_make_request(struct bio *bio, struct bio_split_pool *p)
+{
+	struct bio_split_hook *s;
+
+	if (!bio_has_data(bio) && !(bio->bi_rw & REQ_DISCARD))
+		goto submit;
+
+	if (bio_sectors(bio) <= bch_bio_max_sectors(bio))
+		goto submit;
+
+	s = mempool_alloc(p->bio_split_hook, GFP_NOIO);
+
+	s->bio		= bio;
+	s->p		= p;
+	s->bi_end_io	= bio->bi_end_io;
+	s->bi_private	= bio->bi_private;
+	bio_get(bio);
+
+	closure_call(&s->cl, __bch_bio_submit_split, NULL, NULL);
+	return;
+submit:
+	bch_generic_make_request_hack(bio);
+}
+
+/* Bios with headers */
+
+void bch_bbio_free(struct bio *bio, struct cache_set *c)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+	mempool_free(b, c->bio_meta);
+}
+
+struct bio *bch_bbio_alloc(struct cache_set *c)
+{
+	struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO);
+	struct bio *bio = &b->bio;
+
+	bio_init(bio);
+	bio->bi_flags		|= BIO_POOL_NONE << BIO_POOL_OFFSET;
+	bio->bi_max_vecs	 = bucket_pages(c);
+	bio->bi_io_vec		 = bio->bi_inline_vecs;
+
+	return bio;
+}
+
+void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+
+	bio->bi_sector	= PTR_OFFSET(&b->key, 0);
+	bio->bi_bdev	= PTR_CACHE(c, &b->key, 0)->bdev;
+
+	b->submit_time_us = local_clock_us();
+	closure_bio_submit(bio, bio->bi_private, PTR_CACHE(c, &b->key, 0));
+}
+
+void bch_submit_bbio(struct bio *bio, struct cache_set *c,
+		     struct bkey *k, unsigned ptr)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+	bch_bkey_copy_single_ptr(&b->key, k, ptr);
+	__bch_submit_bbio(bio, c);
+}
+
+/* IO errors */
+
+void bch_count_io_errors(struct cache *ca, int error, const char *m)
+{
+	/*
+	 * The halflife of an error is:
+	 * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
+	 */
+
+	if (ca->set->error_decay) {
+		unsigned count = atomic_inc_return(&ca->io_count);
+
+		while (count > ca->set->error_decay) {
+			unsigned errors;
+			unsigned old = count;
+			unsigned new = count - ca->set->error_decay;
+
+			/*
+			 * First we subtract refresh from count; each time we
+			 * succesfully do so, we rescale the errors once:
+			 */
+
+			count = atomic_cmpxchg(&ca->io_count, old, new);
+
+			if (count == old) {
+				count = new;
+
+				errors = atomic_read(&ca->io_errors);
+				do {
+					old = errors;
+					new = ((uint64_t) errors * 127) / 128;
+					errors = atomic_cmpxchg(&ca->io_errors,
+								old, new);
+				} while (old != errors);
+			}
+		}
+	}
+
+	if (error) {
+		char buf[BDEVNAME_SIZE];
+		unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
+						    &ca->io_errors);
+		errors >>= IO_ERROR_SHIFT;
+
+		if (errors < ca->set->error_limit)
+			pr_err("%s: IO error on %s, recovering",
+			       bdevname(ca->bdev, buf), m);
+		else
+			bch_cache_set_error(ca->set,
+					    "%s: too many IO errors %s",
+					    bdevname(ca->bdev, buf), m);
+	}
+}
+
+void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
+			      int error, const char *m)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+	struct cache *ca = PTR_CACHE(c, &b->key, 0);
+
+	unsigned threshold = bio->bi_rw & REQ_WRITE
+		? c->congested_write_threshold_us
+		: c->congested_read_threshold_us;
+
+	if (threshold) {
+		unsigned t = local_clock_us();
+
+		int us = t - b->submit_time_us;
+		int congested = atomic_read(&c->congested);
+
+		if (us > (int) threshold) {
+			int ms = us / 1024;
+			c->congested_last_us = t;
+
+			ms = min(ms, CONGESTED_MAX + congested);
+			atomic_sub(ms, &c->congested);
+		} else if (congested < 0)
+			atomic_inc(&c->congested);
+	}
+
+	bch_count_io_errors(ca, error, m);
+}
+
+void bch_bbio_endio(struct cache_set *c, struct bio *bio,
+		    int error, const char *m)
+{
+	struct closure *cl = bio->bi_private;
+
+	bch_bbio_count_io_errors(c, bio, error, m);
+	bio_put(bio);
+	closure_put(cl);
+}

drivers/md/bcache/journal.c

@@ -0,0 +1,785 @@
+/*
+ * bcache journalling code, for btree insertions
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+
+/*
+ * Journal replay/recovery:
+ *
+ * This code is all driven from run_cache_set(); we first read the journal
+ * entries, do some other stuff, then we mark all the keys in the journal
+ * entries (same as garbage collection would), then we replay them - reinserting
+ * them into the cache in precisely the same order as they appear in the
+ * journal.
+ *
+ * We only journal keys that go in leaf nodes, which simplifies things quite a
+ * bit.
+ */
+
+static void journal_read_endio(struct bio *bio, int error)
+{
+	struct closure *cl = bio->bi_private;
+	closure_put(cl);
+}
+
+static int journal_read_bucket(struct cache *ca, struct list_head *list,
+			       struct btree_op *op, unsigned bucket_index)
+{
+	struct journal_device *ja = &ca->journal;
+	struct bio *bio = &ja->bio;
+
+	struct journal_replay *i;
+	struct jset *j, *data = ca->set->journal.w[0].data;
+	unsigned len, left, offset = 0;
+	int ret = 0;
+	sector_t bucket = bucket_to_sector(ca->set, ca->sb.d[bucket_index]);
+
+	pr_debug("reading %llu", (uint64_t) bucket);
+
+	while (offset < ca->sb.bucket_size) {
+reread:		left = ca->sb.bucket_size - offset;
+		len = min_t(unsigned, left, PAGE_SECTORS * 8);
+
+		bio_reset(bio);
+		bio->bi_sector	= bucket + offset;
+		bio->bi_bdev	= ca->bdev;
+		bio->bi_rw	= READ;
+		bio->bi_size	= len << 9;
+
+		bio->bi_end_io	= journal_read_endio;
+		bio->bi_private = &op->cl;
+		bio_map(bio, data);
+
+		closure_bio_submit(bio, &op->cl, ca);
+		closure_sync(&op->cl);
+
+		/* This function could be simpler now since we no longer write
+		 * journal entries that overlap bucket boundaries; this means
+		 * the start of a bucket will always have a valid journal entry
+		 * if it has any journal entries at all.
+		 */
+
+		j = data;
+		while (len) {
+			struct list_head *where;
+			size_t blocks, bytes = set_bytes(j);
+
+			if (j->magic != jset_magic(ca->set))
+				return ret;
+
+			if (bytes > left << 9)
+				return ret;
+
+			if (bytes > len << 9)
+				goto reread;
+
+			if (j->csum != csum_set(j))
+				return ret;
+
+			blocks = set_blocks(j, ca->set);
+
+			while (!list_empty(list)) {
+				i = list_first_entry(list,
+					struct journal_replay, list);
+				if (i->j.seq >= j->last_seq)
+					break;
+				list_del(&i->list);
+				kfree(i);
+			}
+
+			list_for_each_entry_reverse(i, list, list) {
+				if (j->seq == i->j.seq)
+					goto next_set;
+
+				if (j->seq < i->j.last_seq)
+					goto next_set;
+
+				if (j->seq > i->j.seq) {
+					where = &i->list;
+					goto add;
+				}
+			}
+
+			where = list;
+add:
+			i = kmalloc(offsetof(struct journal_replay, j) +
+				    bytes, GFP_KERNEL);
+			if (!i)
+				return -ENOMEM;
+			memcpy(&i->j, j, bytes);
+			list_add(&i->list, where);
+			ret = 1;
+
+			ja->seq[bucket_index] = j->seq;
+next_set:
+			offset	+= blocks * ca->sb.block_size;
+			len	-= blocks * ca->sb.block_size;
+			j = ((void *) j) + blocks * block_bytes(ca);
+		}
+	}
+
+	return ret;
+}
+
+int bch_journal_read(struct cache_set *c, struct list_head *list,
+			struct btree_op *op)
+{
+#define read_bucket(b)							\
+	({								\
+		int ret = journal_read_bucket(ca, list, op, b);		\
+		__set_bit(b, bitmap);					\
+		if (ret < 0)						\
+			return ret;					\
+		ret;							\
+	})
+
+	struct cache *ca;
+	unsigned iter;
+
+	for_each_cache(ca, c, iter) {
+		struct journal_device *ja = &ca->journal;
+		unsigned long bitmap[SB_JOURNAL_BUCKETS / BITS_PER_LONG];
+		unsigned i, l, r, m;
+		uint64_t seq;
+
+		bitmap_zero(bitmap, SB_JOURNAL_BUCKETS);
+		pr_debug("%u journal buckets", ca->sb.njournal_buckets);
+
+		/* Read journal buckets ordered by golden ratio hash to quickly
+		 * find a sequence of buckets with valid journal entries
+		 */
+		for (i = 0; i < ca->sb.njournal_buckets; i++) {
+			l = (i * 2654435769U) % ca->sb.njournal_buckets;
+
+			if (test_bit(l, bitmap))
+				break;
+
+			if (read_bucket(l))
+				goto bsearch;
+		}
+
+		/* If that fails, check all the buckets we haven't checked
+		 * already
+		 */
+		pr_debug("falling back to linear search");
+
+		for (l = 0; l < ca->sb.njournal_buckets; l++) {
+			if (test_bit(l, bitmap))
+				continue;
+
+			if (read_bucket(l))
+				goto bsearch;
+		}
+bsearch:
+		/* Binary search */
+		m = r = find_next_bit(bitmap, ca->sb.njournal_buckets, l + 1);
+		pr_debug("starting binary search, l %u r %u", l, r);
+
+		while (l + 1 < r) {
+			m = (l + r) >> 1;
+
+			if (read_bucket(m))
+				l = m;
+			else
+				r = m;
+		}
+
+		/* Read buckets in reverse order until we stop finding more
+		 * journal entries
+		 */
+		pr_debug("finishing up");
+		l = m;
+
+		while (1) {
+			if (!l--)
+				l = ca->sb.njournal_buckets - 1;
+
+			if (l == m)
+				break;
+
+			if (test_bit(l, bitmap))
+				continue;
+
+			if (!read_bucket(l))
+				break;
+		}
+
+		seq = 0;
+
+		for (i = 0; i < ca->sb.njournal_buckets; i++)
+			if (ja->seq[i] > seq) {
+				seq = ja->seq[i];
+				ja->cur_idx = ja->discard_idx =
+					ja->last_idx = i;
+
+			}
+	}
+
+	c->journal.seq = list_entry(list->prev,
+				    struct journal_replay,
+				    list)->j.seq;
+
+	return 0;
+#undef read_bucket
+}
+
+void bch_journal_mark(struct cache_set *c, struct list_head *list)
+{
+	atomic_t p = { 0 };
+	struct bkey *k;
+	struct journal_replay *i;
+	struct journal *j = &c->journal;
+	uint64_t last = j->seq;
+
+	/*
+	 * journal.pin should never fill up - we never write a journal
+	 * entry when it would fill up. But if for some reason it does, we
+	 * iterate over the list in reverse order so that we can just skip that
+	 * refcount instead of bugging.
+	 */
+
+	list_for_each_entry_reverse(i, list, list) {
+		BUG_ON(last < i->j.seq);
+		i->pin = NULL;
+
+		while (last-- != i->j.seq)
+			if (fifo_free(&j->pin) > 1) {
+				fifo_push_front(&j->pin, p);
+				atomic_set(&fifo_front(&j->pin), 0);
+			}
+
+		if (fifo_free(&j->pin) > 1) {
+			fifo_push_front(&j->pin, p);
+			i->pin = &fifo_front(&j->pin);
+			atomic_set(i->pin, 1);
+		}
+
+		for (k = i->j.start;
+		     k < end(&i->j);
+		     k = bkey_next(k)) {
+			unsigned j;
+
+			for (j = 0; j < KEY_PTRS(k); j++) {
+				struct bucket *g = PTR_BUCKET(c, k, j);
+				atomic_inc(&g->pin);
+
+				if (g->prio == BTREE_PRIO &&
+				    !ptr_stale(c, k, j))
+					g->prio = INITIAL_PRIO;
+			}
+
+			__bch_btree_mark_key(c, 0, k);
+		}
+	}
+}
+
+int bch_journal_replay(struct cache_set *s, struct list_head *list,
+			  struct btree_op *op)
+{
+	int ret = 0, keys = 0, entries = 0;
+	struct bkey *k;
+	struct journal_replay *i =
+		list_entry(list->prev, struct journal_replay, list);
+
+	uint64_t start = i->j.last_seq, end = i->j.seq, n = start;
+
+	list_for_each_entry(i, list, list) {
+		BUG_ON(i->pin && atomic_read(i->pin) != 1);
+
+		if (n != i->j.seq)
+			pr_err("journal entries %llu-%llu "
+			       "missing! (replaying %llu-%llu)\n",
+			       n, i->j.seq - 1, start, end);
+
+		for (k = i->j.start;
+		     k < end(&i->j);
+		     k = bkey_next(k)) {
+			pr_debug("%s", pkey(k));
+			bkey_copy(op->keys.top, k);
+			bch_keylist_push(&op->keys);
+
+			op->journal = i->pin;
+			atomic_inc(op->journal);
+
+			ret = bch_btree_insert(op, s);
+			if (ret)
+				goto err;
+
+			BUG_ON(!bch_keylist_empty(&op->keys));
+			keys++;
+
+			cond_resched();
+		}
+
+		if (i->pin)
+			atomic_dec(i->pin);
+		n = i->j.seq + 1;
+		entries++;
+	}
+
+	pr_info("journal replay done, %i keys in %i entries, seq %llu",
+		keys, entries, end);
+
+	while (!list_empty(list)) {
+		i = list_first_entry(list, struct journal_replay, list);
+		list_del(&i->list);
+		kfree(i);
+	}
+err:
+	closure_sync(&op->cl);
+	return ret;
+}
+
+/* Journalling */
+
+static void btree_flush_write(struct cache_set *c)
+{
+	/*
+	 * Try to find the btree node with that references the oldest journal
+	 * entry, best is our current candidate and is locked if non NULL:
+	 */
+	struct btree *b, *best = NULL;
+	unsigned iter;
+
+	for_each_cached_btree(b, c, iter) {
+		if (!down_write_trylock(&b->lock))
+			continue;
+
+		if (!btree_node_dirty(b) ||
+		    !btree_current_write(b)->journal) {
+			rw_unlock(true, b);
+			continue;
+		}
+
+		if (!best)
+			best = b;
+		else if (journal_pin_cmp(c,
+					 btree_current_write(best),
+					 btree_current_write(b))) {
+			rw_unlock(true, best);
+			best = b;
+		} else
+			rw_unlock(true, b);
+	}
+
+	if (best)
+		goto out;
+
+	/* We can't find the best btree node, just pick the first */
+	list_for_each_entry(b, &c->btree_cache, list)
+		if (!b->level && btree_node_dirty(b)) {
+			best = b;
+			rw_lock(true, best, best->level);
+			goto found;
+		}
+
+out:
+	if (!best)
+		return;
+found:
+	if (btree_node_dirty(best))
+		bch_btree_write(best, true, NULL);
+	rw_unlock(true, best);
+}
+
+#define last_seq(j)	((j)->seq - fifo_used(&(j)->pin) + 1)
+
+static void journal_discard_endio(struct bio *bio, int error)
+{
+	struct journal_device *ja =
+		container_of(bio, struct journal_device, discard_bio);
+	struct cache *ca = container_of(ja, struct cache, journal);
+
+	atomic_set(&ja->discard_in_flight, DISCARD_DONE);
+
+	closure_wake_up(&ca->set->journal.wait);
+	closure_put(&ca->set->cl);
+}
+
+static void journal_discard_work(struct work_struct *work)
+{
+	struct journal_device *ja =
+		container_of(work, struct journal_device, discard_work);
+
+	submit_bio(0, &ja->discard_bio);
+}
+
+static void do_journal_discard(struct cache *ca)
+{
+	struct journal_device *ja = &ca->journal;
+	struct bio *bio = &ja->discard_bio;
+
+	if (!ca->discard) {
+		ja->discard_idx = ja->last_idx;
+		return;
+	}
+
+	switch (atomic_read(&ja->discard_in_flight) == DISCARD_IN_FLIGHT) {
+	case DISCARD_IN_FLIGHT:
+		return;
+
+	case DISCARD_DONE:
+		ja->discard_idx = (ja->discard_idx + 1) %
+			ca->sb.njournal_buckets;
+
+		atomic_set(&ja->discard_in_flight, DISCARD_READY);
+		/* fallthrough */
+
+	case DISCARD_READY:
+		if (ja->discard_idx == ja->last_idx)
+			return;
+
+		atomic_set(&ja->discard_in_flight, DISCARD_IN_FLIGHT);
+
+		bio_init(bio);
+		bio->bi_sector		= bucket_to_sector(ca->set,
+							   ca->sb.d[ja->discard_idx]);
+		bio->bi_bdev		= ca->bdev;
+		bio->bi_rw		= REQ_WRITE|REQ_DISCARD;
+		bio->bi_max_vecs	= 1;
+		bio->bi_io_vec		= bio->bi_inline_vecs;
+		bio->bi_size		= bucket_bytes(ca);
+		bio->bi_end_io		= journal_discard_endio;
+
+		closure_get(&ca->set->cl);
+		INIT_WORK(&ja->discard_work, journal_discard_work);
+		schedule_work(&ja->discard_work);
+	}
+}
+
+static void journal_reclaim(struct cache_set *c)
+{
+	struct bkey *k = &c->journal.key;
+	struct cache *ca;
+	uint64_t last_seq;
+	unsigned iter, n = 0;
+	atomic_t p;
+
+	while (!atomic_read(&fifo_front(&c->journal.pin)))
+		fifo_pop(&c->journal.pin, p);
+
+	last_seq = last_seq(&c->journal);
+
+	/* Update last_idx */
+
+	for_each_cache(ca, c, iter) {
+		struct journal_device *ja = &ca->journal;
+
+		while (ja->last_idx != ja->cur_idx &&
+		       ja->seq[ja->last_idx] < last_seq)
+			ja->last_idx = (ja->last_idx + 1) %
+				ca->sb.njournal_buckets;
+	}
+
+	for_each_cache(ca, c, iter)
+		do_journal_discard(ca);
+
+	if (c->journal.blocks_free)
+		return;
+
+	/*
+	 * Allocate:
+	 * XXX: Sort by free journal space
+	 */
+
+	for_each_cache(ca, c, iter) {
+		struct journal_device *ja = &ca->journal;
+		unsigned next = (ja->cur_idx + 1) % ca->sb.njournal_buckets;
+
+		/* No space available on this device */
+		if (next == ja->discard_idx)
+			continue;
+
+		ja->cur_idx = next;
+		k->ptr[n++] = PTR(0,
+				  bucket_to_sector(c, ca->sb.d[ja->cur_idx]),
+				  ca->sb.nr_this_dev);
+	}
+
+	bkey_init(k);
+	SET_KEY_PTRS(k, n);
+
+	if (n)
+		c->journal.blocks_free = c->sb.bucket_size >> c->block_bits;
+
+	if (!journal_full(&c->journal))
+		__closure_wake_up(&c->journal.wait);
+}
+
+void bch_journal_next(struct journal *j)
+{
+	atomic_t p = { 1 };
+
+	j->cur = (j->cur == j->w)
+		? &j->w[1]
+		: &j->w[0];
+
+	/*
+	 * The fifo_push() needs to happen at the same time as j->seq is
+	 * incremented for last_seq() to be calculated correctly
+	 */
+	BUG_ON(!fifo_push(&j->pin, p));
+	atomic_set(&fifo_back(&j->pin), 1);
+
+	j->cur->data->seq	= ++j->seq;
+	j->cur->need_write	= false;
+	j->cur->data->keys	= 0;
+
+	if (fifo_full(&j->pin))
+		pr_debug("journal_pin full (%zu)", fifo_used(&j->pin));
+}
+
+static void journal_write_endio(struct bio *bio, int error)
+{
+	struct journal_write *w = bio->bi_private;
+
+	cache_set_err_on(error, w->c, "journal io error");
+	closure_put(&w->c->journal.io.cl);
+}
+
+static void journal_write(struct closure *);
+
+static void journal_write_done(struct closure *cl)
+{
+	struct journal *j = container_of(cl, struct journal, io.cl);
+	struct cache_set *c = container_of(j, struct cache_set, journal);
+
+	struct journal_write *w = (j->cur == j->w)
+		? &j->w[1]
+		: &j->w[0];
+
+	__closure_wake_up(&w->wait);
+
+	if (c->journal_delay_ms)
+		closure_delay(&j->io, msecs_to_jiffies(c->journal_delay_ms));
+
+	continue_at(cl, journal_write, system_wq);
+}
+
+static void journal_write_unlocked(struct closure *cl)
+{
+	struct cache_set *c = container_of(cl, struct cache_set, journal.io.cl);
+	struct cache *ca;
+	struct journal_write *w = c->journal.cur;
+	struct bkey *k = &c->journal.key;
+	unsigned i, sectors = set_blocks(w->data, c) * c->sb.block_size;
+
+	struct bio *bio;
+	struct bio_list list;
+	bio_list_init(&list);
+
+	if (!w->need_write) {
+		/*
+		 * XXX: have to unlock closure before we unlock journal lock,
+		 * else we race with bch_journal(). But this way we race
+		 * against cache set unregister. Doh.
+		 */
+		set_closure_fn(cl, NULL, NULL);
+		closure_sub(cl, CLOSURE_RUNNING + 1);
+		spin_unlock(&c->journal.lock);
+		return;
+	} else if (journal_full(&c->journal)) {
+		journal_reclaim(c);
+		spin_unlock(&c->journal.lock);
+
+		btree_flush_write(c);
+		continue_at(cl, journal_write, system_wq);
+	}
+
+	c->journal.blocks_free -= set_blocks(w->data, c);
+
+	w->data->btree_level = c->root->level;
+
+	bkey_copy(&w->data->btree_root, &c->root->key);
+	bkey_copy(&w->data->uuid_bucket, &c->uuid_bucket);
+
+	for_each_cache(ca, c, i)
+		w->data->prio_bucket[ca->sb.nr_this_dev] = ca->prio_buckets[0];
+
+	w->data->magic		= jset_magic(c);
+	w->data->version	= BCACHE_JSET_VERSION;
+	w->data->last_seq	= last_seq(&c->journal);
+	w->data->csum		= csum_set(w->data);
+
+	for (i = 0; i < KEY_PTRS(k); i++) {
+		ca = PTR_CACHE(c, k, i);
+		bio = &ca->journal.bio;
+
+		atomic_long_add(sectors, &ca->meta_sectors_written);
+
+		bio_reset(bio);
+		bio->bi_sector	= PTR_OFFSET(k, i);
+		bio->bi_bdev	= ca->bdev;
+		bio->bi_rw	= REQ_WRITE|REQ_SYNC|REQ_META|REQ_FLUSH;
+		bio->bi_size	= sectors << 9;
+
+		bio->bi_end_io	= journal_write_endio;
+		bio->bi_private = w;
+		bio_map(bio, w->data);
+
+		trace_bcache_journal_write(bio);
+		bio_list_add(&list, bio);
+
+		SET_PTR_OFFSET(k, i, PTR_OFFSET(k, i) + sectors);
+
+		ca->journal.seq[ca->journal.cur_idx] = w->data->seq;
+	}
+
+	atomic_dec_bug(&fifo_back(&c->journal.pin));
+	bch_journal_next(&c->journal);
+	journal_reclaim(c);
+
+	spin_unlock(&c->journal.lock);
+
+	while ((bio = bio_list_pop(&list)))
+		closure_bio_submit(bio, cl, c->cache[0]);
+
+	continue_at(cl, journal_write_done, NULL);
+}
+
+static void journal_write(struct closure *cl)
+{
+	struct cache_set *c = container_of(cl, struct cache_set, journal.io.cl);
+
+	spin_lock(&c->journal.lock);
+	journal_write_unlocked(cl);
+}
+
+static void __journal_try_write(struct cache_set *c, bool noflush)
+{
+	struct closure *cl = &c->journal.io.cl;
+
+	if (!closure_trylock(cl, &c->cl))
+		spin_unlock(&c->journal.lock);
+	else if (noflush && journal_full(&c->journal)) {
+		spin_unlock(&c->journal.lock);
+		continue_at(cl, journal_write, system_wq);
+	} else
+		journal_write_unlocked(cl);
+}
+
+#define journal_try_write(c)	__journal_try_write(c, false)
+
+void bch_journal_meta(struct cache_set *c, struct closure *cl)
+{
+	struct journal_write *w;
+
+	if (CACHE_SYNC(&c->sb)) {
+		spin_lock(&c->journal.lock);
+
+		w = c->journal.cur;
+		w->need_write = true;
+
+		if (cl)
+			BUG_ON(!closure_wait(&w->wait, cl));
+
+		__journal_try_write(c, true);
+	}
+}
+
+/*
+ * Entry point to the journalling code - bio_insert() and btree_invalidate()
+ * pass bch_journal() a list of keys to be journalled, and then
+ * bch_journal() hands those same keys off to btree_insert_async()
+ */
+
+void bch_journal(struct closure *cl)
+{
+	struct btree_op *op = container_of(cl, struct btree_op, cl);
+	struct cache_set *c = op->c;
+	struct journal_write *w;
+	size_t b, n = ((uint64_t *) op->keys.top) - op->keys.list;
+
+	if (op->type != BTREE_INSERT ||
+	    !CACHE_SYNC(&c->sb))
+		goto out;
+
+	/*
+	 * If we're looping because we errored, might already be waiting on
+	 * another journal write:
+	 */
+	while (atomic_read(&cl->parent->remaining) & CLOSURE_WAITING)
+		closure_sync(cl->parent);
+
+	spin_lock(&c->journal.lock);
+
+	if (journal_full(&c->journal)) {
+		/* XXX: tracepoint */
+		closure_wait(&c->journal.wait, cl);
+
+		journal_reclaim(c);
+		spin_unlock(&c->journal.lock);
+
+		btree_flush_write(c);
+		continue_at(cl, bch_journal, bcache_wq);
+	}
+
+	w = c->journal.cur;
+	w->need_write = true;
+	b = __set_blocks(w->data, w->data->keys + n, c);
+
+	if (b * c->sb.block_size > PAGE_SECTORS << JSET_BITS ||
+	    b > c->journal.blocks_free) {
+		/* XXX: If we were inserting so many keys that they won't fit in
+		 * an _empty_ journal write, we'll deadlock. For now, handle
+		 * this in bch_keylist_realloc() - but something to think about.
+		 */
+		BUG_ON(!w->data->keys);
+
+		/* XXX: tracepoint */
+		BUG_ON(!closure_wait(&w->wait, cl));
+
+		closure_flush(&c->journal.io);
+
+		journal_try_write(c);
+		continue_at(cl, bch_journal, bcache_wq);
+	}
+
+	memcpy(end(w->data), op->keys.list, n * sizeof(uint64_t));
+	w->data->keys += n;
+
+	op->journal = &fifo_back(&c->journal.pin);
+	atomic_inc(op->journal);
+
+	if (op->flush_journal) {
+		closure_flush(&c->journal.io);
+		closure_wait(&w->wait, cl->parent);
+	}
+
+	journal_try_write(c);
+out:
+	bch_btree_insert_async(cl);
+}
+
+void bch_journal_free(struct cache_set *c)
+{
+	free_pages((unsigned long) c->journal.w[1].data, JSET_BITS);
+	free_pages((unsigned long) c->journal.w[0].data, JSET_BITS);
+	free_fifo(&c->journal.pin);
+}
+
+int bch_journal_alloc(struct cache_set *c)
+{
+	struct journal *j = &c->journal;
+
+	closure_init_unlocked(&j->io);
+	spin_lock_init(&j->lock);
+
+	c->journal_delay_ms = 100;
+
+	j->w[0].c = c;
+	j->w[1].c = c;
+
+	if (!(init_fifo(&j->pin, JOURNAL_PIN, GFP_KERNEL)) ||
+	    !(j->w[0].data = (void *) __get_free_pages(GFP_KERNEL, JSET_BITS)) ||
+	    !(j->w[1].data = (void *) __get_free_pages(GFP_KERNEL, JSET_BITS)))
+		return -ENOMEM;
+
+	return 0;
+}

drivers/md/bcache/journal.h

@@ -0,0 +1,215 @@
+#ifndef _BCACHE_JOURNAL_H
+#define _BCACHE_JOURNAL_H
+
+/*
+ * THE JOURNAL:
+ *
+ * The journal is treated as a circular buffer of buckets - a journal entry
+ * never spans two buckets. This means (not implemented yet) we can resize the
+ * journal at runtime, and will be needed for bcache on raw flash support.
+ *
+ * Journal entries contain a list of keys, ordered by the time they were
+ * inserted; thus journal replay just has to reinsert the keys.
+ *
+ * We also keep some things in the journal header that are logically part of the
+ * superblock - all the things that are frequently updated. This is for future
+ * bcache on raw flash support; the superblock (which will become another
+ * journal) can't be moved or wear leveled, so it contains just enough
+ * information to find the main journal, and the superblock only has to be
+ * rewritten when we want to move/wear level the main journal.
+ *
+ * Currently, we don't journal BTREE_REPLACE operations - this will hopefully be
+ * fixed eventually. This isn't a bug - BTREE_REPLACE is used for insertions
+ * from cache misses, which don't have to be journaled, and for writeback and
+ * moving gc we work around it by flushing the btree to disk before updating the
+ * gc information. But it is a potential issue with incremental garbage
+ * collection, and it's fragile.
+ *
+ * OPEN JOURNAL ENTRIES:
+ *
+ * Each journal entry contains, in the header, the sequence number of the last
+ * journal entry still open - i.e. that has keys that haven't been flushed to
+ * disk in the btree.
+ *
+ * We track this by maintaining a refcount for every open journal entry, in a
+ * fifo; each entry in the fifo corresponds to a particular journal
+ * entry/sequence number. When the refcount at the tail of the fifo goes to
+ * zero, we pop it off - thus, the size of the fifo tells us the number of open
+ * journal entries
+ *
+ * We take a refcount on a journal entry when we add some keys to a journal
+ * entry that we're going to insert (held by struct btree_op), and then when we
+ * insert those keys into the btree the btree write we're setting up takes a
+ * copy of that refcount (held by struct btree_write). That refcount is dropped
+ * when the btree write completes.
+ *
+ * A struct btree_write can only hold a refcount on a single journal entry, but
+ * might contain keys for many journal entries - we handle this by making sure
+ * it always has a refcount on the _oldest_ journal entry of all the journal
+ * entries it has keys for.
+ *
+ * JOURNAL RECLAIM:
+ *
+ * As mentioned previously, our fifo of refcounts tells us the number of open
+ * journal entries; from that and the current journal sequence number we compute
+ * last_seq - the oldest journal entry we still need. We write last_seq in each
+ * journal entry, and we also have to keep track of where it exists on disk so
+ * we don't overwrite it when we loop around the journal.
+ *
+ * To do that we track, for each journal bucket, the sequence number of the
+ * newest journal entry it contains - if we don't need that journal entry we
+ * don't need anything in that bucket anymore. From that we track the last
+ * journal bucket we still need; all this is tracked in struct journal_device
+ * and updated by journal_reclaim().
+ *
+ * JOURNAL FILLING UP:
+ *
+ * There are two ways the journal could fill up; either we could run out of
+ * space to write to, or we could have too many open journal entries and run out
+ * of room in the fifo of refcounts. Since those refcounts are decremented
+ * without any locking we can't safely resize that fifo, so we handle it the
+ * same way.
+ *
+ * If the journal fills up, we start flushing dirty btree nodes until we can
+ * allocate space for a journal write again - preferentially flushing btree
+ * nodes that are pinning the oldest journal entries first.
+ */
+
+#define BCACHE_JSET_VERSION_UUIDv1	1
+/* Always latest UUID format */
+#define BCACHE_JSET_VERSION_UUID	1
+#define BCACHE_JSET_VERSION		1
+
+/*
+ * On disk format for a journal entry:
+ * seq is monotonically increasing; every journal entry has its own unique
+ * sequence number.
+ *
+ * last_seq is the oldest journal entry that still has keys the btree hasn't
+ * flushed to disk yet.
+ *
+ * version is for on disk format changes.
+ */
+struct jset {
+	uint64_t		csum;
+	uint64_t		magic;
+	uint64_t		seq;
+	uint32_t		version;
+	uint32_t		keys;
+
+	uint64_t		last_seq;
+
+	BKEY_PADDED(uuid_bucket);
+	BKEY_PADDED(btree_root);
+	uint16_t		btree_level;
+	uint16_t		pad[3];
+
+	uint64_t		prio_bucket[MAX_CACHES_PER_SET];
+
+	union {
+		struct bkey	start[0];
+		uint64_t	d[0];
+	};
+};
+
+/*
+ * Only used for holding the journal entries we read in btree_journal_read()
+ * during cache_registration
+ */
+struct journal_replay {
+	struct list_head	list;
+	atomic_t		*pin;
+	struct jset		j;
+};
+
+/*
+ * We put two of these in struct journal; we used them for writes to the
+ * journal that are being staged or in flight.
+ */
+struct journal_write {
+	struct jset		*data;
+#define JSET_BITS		3
+
+	struct cache_set	*c;
+	struct closure_waitlist	wait;
+	bool			need_write;
+};
+
+/* Embedded in struct cache_set */
+struct journal {
+	spinlock_t		lock;
+	/* used when waiting because the journal was full */
+	struct closure_waitlist	wait;
+	struct closure_with_timer io;
+
+	/* Number of blocks free in the bucket(s) we're currently writing to */
+	unsigned		blocks_free;
+	uint64_t		seq;
+	DECLARE_FIFO(atomic_t, pin);
+
+	BKEY_PADDED(key);
+
+	struct journal_write	w[2], *cur;
+};
+
+/*
+ * Embedded in struct cache. First three fields refer to the array of journal
+ * buckets, in cache_sb.
+ */
+struct journal_device {
+	/*
+	 * For each journal bucket, contains the max sequence number of the
+	 * journal writes it contains - so we know when a bucket can be reused.
+	 */
+	uint64_t		seq[SB_JOURNAL_BUCKETS];
+
+	/* Journal bucket we're currently writing to */
+	unsigned		cur_idx;
+
+	/* Last journal bucket that still contains an open journal entry */
+	unsigned		last_idx;
+
+	/* Next journal bucket to be discarded */
+	unsigned		discard_idx;
+
+#define DISCARD_READY		0
+#define DISCARD_IN_FLIGHT	1
+#define DISCARD_DONE		2
+	/* 1 - discard in flight, -1 - discard completed */
+	atomic_t		discard_in_flight;
+
+	struct work_struct	discard_work;
+	struct bio		discard_bio;
+	struct bio_vec		discard_bv;
+
+	/* Bio for journal reads/writes to this device */
+	struct bio		bio;
+	struct bio_vec		bv[8];
+};
+
+#define journal_pin_cmp(c, l, r)				\
+	(fifo_idx(&(c)->journal.pin, (l)->journal) >		\
+	 fifo_idx(&(c)->journal.pin, (r)->journal))
+
+#define JOURNAL_PIN	20000
+
+#define journal_full(j)						\
+	(!(j)->blocks_free || fifo_free(&(j)->pin) <= 1)
+
+struct closure;
+struct cache_set;
+struct btree_op;
+
+void bch_journal(struct closure *);
+void bch_journal_next(struct journal *);
+void bch_journal_mark(struct cache_set *, struct list_head *);
+void bch_journal_meta(struct cache_set *, struct closure *);
+int bch_journal_read(struct cache_set *, struct list_head *,
+			struct btree_op *);
+int bch_journal_replay(struct cache_set *, struct list_head *,
+			  struct btree_op *);
+
+void bch_journal_free(struct cache_set *);
+int bch_journal_alloc(struct cache_set *);
+
+#endif /* _BCACHE_JOURNAL_H */

drivers/md/bcache/movinggc.c

@@ -0,0 +1,254 @@
+/*
+ * Moving/copying garbage collector
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+
+struct moving_io {
+	struct keybuf_key	*w;
+	struct search		s;
+	struct bbio		bio;
+};
+
+static bool moving_pred(struct keybuf *buf, struct bkey *k)
+{
+	struct cache_set *c = container_of(buf, struct cache_set,
+					   moving_gc_keys);
+	unsigned i;
+
+	for (i = 0; i < KEY_PTRS(k); i++) {
+		struct cache *ca = PTR_CACHE(c, k, i);
+		struct bucket *g = PTR_BUCKET(c, k, i);
+
+		if (GC_SECTORS_USED(g) < ca->gc_move_threshold)
+			return true;
+	}
+
+	return false;
+}
+
+/* Moving GC - IO loop */
+
+static void moving_io_destructor(struct closure *cl)
+{
+	struct moving_io *io = container_of(cl, struct moving_io, s.cl);
+	kfree(io);
+}
+
+static void write_moving_finish(struct closure *cl)
+{
+	struct moving_io *io = container_of(cl, struct moving_io, s.cl);
+	struct bio *bio = &io->bio.bio;
+	struct bio_vec *bv = bio_iovec_idx(bio, bio->bi_vcnt);
+
+	while (bv-- != bio->bi_io_vec)
+		__free_page(bv->bv_page);
+
+	pr_debug("%s %s", io->s.op.insert_collision
+		 ? "collision moving" : "moved",
+		 pkey(&io->w->key));
+
+	bch_keybuf_del(&io->s.op.c->moving_gc_keys, io->w);
+
+	atomic_dec_bug(&io->s.op.c->in_flight);
+	closure_wake_up(&io->s.op.c->moving_gc_wait);
+
+	closure_return_with_destructor(cl, moving_io_destructor);
+}
+
+static void read_moving_endio(struct bio *bio, int error)
+{
+	struct moving_io *io = container_of(bio->bi_private,
+					    struct moving_io, s.cl);
+
+	if (error)
+		io->s.error = error;
+
+	bch_bbio_endio(io->s.op.c, bio, error, "reading data to move");
+}
+
+static void moving_init(struct moving_io *io)
+{
+	struct bio *bio = &io->bio.bio;
+
+	bio_init(bio);
+	bio_get(bio);
+	bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
+
+	bio->bi_size		= KEY_SIZE(&io->w->key) << 9;
+	bio->bi_max_vecs	= DIV_ROUND_UP(KEY_SIZE(&io->w->key),
+					       PAGE_SECTORS);
+	bio->bi_private		= &io->s.cl;
+	bio->bi_io_vec		= bio->bi_inline_vecs;
+	bio_map(bio, NULL);
+}
+
+static void write_moving(struct closure *cl)
+{
+	struct search *s = container_of(cl, struct search, cl);
+	struct moving_io *io = container_of(s, struct moving_io, s);
+
+	if (!s->error) {
+		trace_bcache_write_moving(&io->bio.bio);
+
+		moving_init(io);
+
+		io->bio.bio.bi_sector	= KEY_START(&io->w->key);
+		s->op.lock		= -1;
+		s->op.write_prio	= 1;
+		s->op.cache_bio		= &io->bio.bio;
+
+		s->writeback		= KEY_DIRTY(&io->w->key);
+		s->op.csum		= KEY_CSUM(&io->w->key);
+
+		s->op.type = BTREE_REPLACE;
+		bkey_copy(&s->op.replace, &io->w->key);
+
+		closure_init(&s->op.cl, cl);
+		bch_insert_data(&s->op.cl);
+	}
+
+	continue_at(cl, write_moving_finish, NULL);
+}
+
+static void read_moving_submit(struct closure *cl)
+{
+	struct search *s = container_of(cl, struct search, cl);
+	struct moving_io *io = container_of(s, struct moving_io, s);
+	struct bio *bio = &io->bio.bio;
+
+	trace_bcache_read_moving(bio);
+	bch_submit_bbio(bio, s->op.c, &io->w->key, 0);
+
+	continue_at(cl, write_moving, bch_gc_wq);
+}
+
+static void read_moving(struct closure *cl)
+{
+	struct cache_set *c = container_of(cl, struct cache_set, moving_gc);
+	struct keybuf_key *w;
+	struct moving_io *io;
+	struct bio *bio;
+
+	/* XXX: if we error, background writeback could stall indefinitely */
+
+	while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
+		w = bch_keybuf_next_rescan(c, &c->moving_gc_keys, &MAX_KEY);
+		if (!w)
+			break;
+
+		io = kzalloc(sizeof(struct moving_io) + sizeof(struct bio_vec)
+			     * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
+			     GFP_KERNEL);
+		if (!io)
+			goto err;
+
+		w->private	= io;
+		io->w		= w;
+		io->s.op.inode	= KEY_INODE(&w->key);
+		io->s.op.c	= c;
+
+		moving_init(io);
+		bio = &io->bio.bio;
+
+		bio->bi_rw	= READ;
+		bio->bi_end_io	= read_moving_endio;
+
+		if (bio_alloc_pages(bio, GFP_KERNEL))
+			goto err;
+
+		pr_debug("%s", pkey(&w->key));
+
+		closure_call(&io->s.cl, read_moving_submit, NULL, &c->gc.cl);
+
+		if (atomic_inc_return(&c->in_flight) >= 64) {
+			closure_wait_event(&c->moving_gc_wait, cl,
+					   atomic_read(&c->in_flight) < 64);
+			continue_at(cl, read_moving, bch_gc_wq);
+		}
+	}
+
+	if (0) {
+err:		if (!IS_ERR_OR_NULL(w->private))
+			kfree(w->private);
+
+		bch_keybuf_del(&c->moving_gc_keys, w);
+	}
+
+	closure_return(cl);
+}
+
+void bch_moving_gc(struct closure *cl)
+{
+	struct cache_set *c = container_of(cl, struct cache_set, gc.cl);
+	struct cache *ca;
+	struct bucket *b;
+	unsigned i;
+
+	bool bucket_cmp(struct bucket *l, struct bucket *r)
+	{
+		return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
+	}
+
+	unsigned top(struct cache *ca)
+	{
+		return GC_SECTORS_USED(heap_peek(&ca->heap));
+	}
+
+	if (!c->copy_gc_enabled)
+		closure_return(cl);
+
+	mutex_lock(&c->bucket_lock);
+
+	for_each_cache(ca, c, i) {
+		unsigned sectors_to_move = 0;
+		unsigned reserve_sectors = ca->sb.bucket_size *
+			min(fifo_used(&ca->free), ca->free.size / 2);
+
+		ca->heap.used = 0;
+
+		for_each_bucket(b, ca) {
+			if (!GC_SECTORS_USED(b))
+				continue;
+
+			if (!heap_full(&ca->heap)) {
+				sectors_to_move += GC_SECTORS_USED(b);
+				heap_add(&ca->heap, b, bucket_cmp);
+			} else if (bucket_cmp(b, heap_peek(&ca->heap))) {
+				sectors_to_move -= top(ca);
+				sectors_to_move += GC_SECTORS_USED(b);
+
+				ca->heap.data[0] = b;
+				heap_sift(&ca->heap, 0, bucket_cmp);
+			}
+		}
+
+		while (sectors_to_move > reserve_sectors) {
+			heap_pop(&ca->heap, b, bucket_cmp);
+			sectors_to_move -= GC_SECTORS_USED(b);
+		}
+
+		ca->gc_move_threshold = top(ca);
+
+		pr_debug("threshold %u", ca->gc_move_threshold);
+	}
+
+	mutex_unlock(&c->bucket_lock);
+
+	c->moving_gc_keys.last_scanned = ZERO_KEY;
+
+	closure_init(&c->moving_gc, cl);
+	read_moving(&c->moving_gc);
+
+	closure_return(cl);
+}
+
+void bch_moving_init_cache_set(struct cache_set *c)
+{
+	bch_keybuf_init(&c->moving_gc_keys, moving_pred);
+}

drivers/md/bcache/request.h

@@ -0,0 +1,62 @@
+#ifndef _BCACHE_REQUEST_H_
+#define _BCACHE_REQUEST_H_
+
+#include <linux/cgroup.h>
+
+struct search {
+	/* Stack frame for bio_complete */
+	struct closure		cl;
+
+	struct bcache_device	*d;
+	struct task_struct	*task;
+
+	struct bbio		bio;
+	struct bio		*orig_bio;
+	struct bio		*cache_miss;
+	unsigned		cache_bio_sectors;
+
+	unsigned		recoverable:1;
+	unsigned		unaligned_bvec:1;
+
+	unsigned		write:1;
+	unsigned		writeback:1;
+
+	/* IO error returned to s->bio */
+	short			error;
+	unsigned long		start_time;
+
+	/* Anything past op->keys won't get zeroed in do_bio_hook */
+	struct btree_op		op;
+};
+
+void bch_cache_read_endio(struct bio *, int);
+int bch_get_congested(struct cache_set *);
+void bch_insert_data(struct closure *cl);
+void bch_btree_insert_async(struct closure *);
+void bch_cache_read_endio(struct bio *, int);
+
+void bch_open_buckets_free(struct cache_set *);
+int bch_open_buckets_alloc(struct cache_set *);
+
+void bch_cached_dev_request_init(struct cached_dev *dc);
+void bch_flash_dev_request_init(struct bcache_device *d);
+
+extern struct kmem_cache *bch_search_cache, *bch_passthrough_cache;
+
+struct bch_cgroup {
+#ifdef CONFIG_CGROUP_BCACHE
+	struct cgroup_subsys_state	css;
+#endif
+	/*
+	 * We subtract one from the index into bch_cache_modes[], so that
+	 * default == -1; this makes it so the rest match up with d->cache_mode,
+	 * and we use d->cache_mode if cgrp->cache_mode < 0
+	 */
+	short				cache_mode;
+	bool				verify;
+	struct cache_stat_collector	stats;
+};
+
+struct bch_cgroup *bch_bio_to_cgroup(struct bio *bio);
+
+#endif /* _BCACHE_REQUEST_H_ */

drivers/md/bcache/stats.c

@@ -0,0 +1,245 @@
+/*
+ * bcache stats code
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "stats.h"
+#include "btree.h"
+#include "request.h"
+#include "sysfs.h"
+
+/*
+ * We keep absolute totals of various statistics, and addionally a set of three
+ * rolling averages.
+ *
+ * Every so often, a timer goes off and rescales the rolling averages.
+ * accounting_rescale[] is how many times the timer has to go off before we
+ * rescale each set of numbers; that gets us half lives of 5 minutes, one hour,
+ * and one day.
+ *
+ * accounting_delay is how often the timer goes off - 22 times in 5 minutes,
+ * and accounting_weight is what we use to rescale:
+ *
+ * pow(31 / 32, 22) ~= 1/2
+ *
+ * So that we don't have to increment each set of numbers every time we (say)
+ * get a cache hit, we increment a single atomic_t in acc->collector, and when
+ * the rescale function runs it resets the atomic counter to 0 and adds its
+ * old value to each of the exported numbers.
+ *
+ * To reduce rounding error, the numbers in struct cache_stats are all
+ * stored left shifted by 16, and scaled back in the sysfs show() function.
+ */
+
+static const unsigned DAY_RESCALE		= 288;
+static const unsigned HOUR_RESCALE		= 12;
+static const unsigned FIVE_MINUTE_RESCALE	= 1;
+static const unsigned accounting_delay		= (HZ * 300) / 22;
+static const unsigned accounting_weight		= 32;
+
+/* sysfs reading/writing */
+
+read_attribute(cache_hits);
+read_attribute(cache_misses);
+read_attribute(cache_bypass_hits);
+read_attribute(cache_bypass_misses);
+read_attribute(cache_hit_ratio);
+read_attribute(cache_readaheads);
+read_attribute(cache_miss_collisions);
+read_attribute(bypassed);
+
+SHOW(bch_stats)
+{
+	struct cache_stats *s =
+		container_of(kobj, struct cache_stats, kobj);
+#define var(stat)		(s->stat >> 16)
+	var_print(cache_hits);
+	var_print(cache_misses);
+	var_print(cache_bypass_hits);
+	var_print(cache_bypass_misses);
+
+	sysfs_print(cache_hit_ratio,
+		    DIV_SAFE(var(cache_hits) * 100,
+			     var(cache_hits) + var(cache_misses)));
+
+	var_print(cache_readaheads);
+	var_print(cache_miss_collisions);
+	sysfs_hprint(bypassed,	var(sectors_bypassed) << 9);
+#undef var
+	return 0;
+}
+
+STORE(bch_stats)
+{
+	return size;
+}
+
+static void bch_stats_release(struct kobject *k)
+{
+}
+
+static struct attribute *bch_stats_files[] = {
+	&sysfs_cache_hits,
+	&sysfs_cache_misses,
+	&sysfs_cache_bypass_hits,
+	&sysfs_cache_bypass_misses,
+	&sysfs_cache_hit_ratio,
+	&sysfs_cache_readaheads,
+	&sysfs_cache_miss_collisions,
+	&sysfs_bypassed,
+	NULL
+};
+static KTYPE(bch_stats);
+
+static void scale_accounting(unsigned long data);
+
+void bch_cache_accounting_init(struct cache_accounting *acc, struct closure *parent)
+{
+	kobject_init(&acc->total.kobj,		&bch_stats_ktype);
+	kobject_init(&acc->five_minute.kobj,	&bch_stats_ktype);
+	kobject_init(&acc->hour.kobj,		&bch_stats_ktype);
+	kobject_init(&acc->day.kobj,		&bch_stats_ktype);
+
+	closure_init(&acc->cl, parent);
+	init_timer(&acc->timer);
+	acc->timer.expires	= jiffies + accounting_delay;
+	acc->timer.data		= (unsigned long) acc;
+	acc->timer.function	= scale_accounting;
+	add_timer(&acc->timer);
+}
+
+int bch_cache_accounting_add_kobjs(struct cache_accounting *acc,
+				   struct kobject *parent)
+{
+	int ret = kobject_add(&acc->total.kobj, parent,
+			      "stats_total");
+	ret = ret ?: kobject_add(&acc->five_minute.kobj, parent,
+				 "stats_five_minute");
+	ret = ret ?: kobject_add(&acc->hour.kobj, parent,
+				 "stats_hour");
+	ret = ret ?: kobject_add(&acc->day.kobj, parent,
+				 "stats_day");
+	return ret;
+}
+
+void bch_cache_accounting_clear(struct cache_accounting *acc)
+{
+	memset(&acc->total.cache_hits,
+	       0,
+	       sizeof(unsigned long) * 7);
+}
+
+void bch_cache_accounting_destroy(struct cache_accounting *acc)
+{
+	kobject_put(&acc->total.kobj);
+	kobject_put(&acc->five_minute.kobj);
+	kobject_put(&acc->hour.kobj);
+	kobject_put(&acc->day.kobj);
+
+	atomic_set(&acc->closing, 1);
+	if (del_timer_sync(&acc->timer))
+		closure_return(&acc->cl);
+}
+
+/* EWMA scaling */
+
+static void scale_stat(unsigned long *stat)
+{
+	*stat =  ewma_add(*stat, 0, accounting_weight, 0);
+}
+
+static void scale_stats(struct cache_stats *stats, unsigned long rescale_at)
+{
+	if (++stats->rescale == rescale_at) {
+		stats->rescale = 0;
+		scale_stat(&stats->cache_hits);
+		scale_stat(&stats->cache_misses);
+		scale_stat(&stats->cache_bypass_hits);
+		scale_stat(&stats->cache_bypass_misses);
+		scale_stat(&stats->cache_readaheads);
+		scale_stat(&stats->cache_miss_collisions);
+		scale_stat(&stats->sectors_bypassed);
+	}
+}
+
+static void scale_accounting(unsigned long data)
+{
+	struct cache_accounting *acc = (struct cache_accounting *) data;
+
+#define move_stat(name) do {						\
+	unsigned t = atomic_xchg(&acc->collector.name, 0);		\
+	t <<= 16;							\
+	acc->five_minute.name += t;					\
+	acc->hour.name += t;						\
+	acc->day.name += t;						\
+	acc->total.name += t;						\
+} while (0)
+
+	move_stat(cache_hits);
+	move_stat(cache_misses);
+	move_stat(cache_bypass_hits);
+	move_stat(cache_bypass_misses);
+	move_stat(cache_readaheads);
+	move_stat(cache_miss_collisions);
+	move_stat(sectors_bypassed);
+
+	scale_stats(&acc->total, 0);
+	scale_stats(&acc->day, DAY_RESCALE);
+	scale_stats(&acc->hour, HOUR_RESCALE);
+	scale_stats(&acc->five_minute, FIVE_MINUTE_RESCALE);
+
+	acc->timer.expires += accounting_delay;
+
+	if (!atomic_read(&acc->closing))
+		add_timer(&acc->timer);
+	else
+		closure_return(&acc->cl);
+}
+
+static void mark_cache_stats(struct cache_stat_collector *stats,
+			     bool hit, bool bypass)
+{
+	if (!bypass)
+		if (hit)
+			atomic_inc(&stats->cache_hits);
+		else
+			atomic_inc(&stats->cache_misses);
+	else
+		if (hit)
+			atomic_inc(&stats->cache_bypass_hits);
+		else
+			atomic_inc(&stats->cache_bypass_misses);
+}
+
+void bch_mark_cache_accounting(struct search *s, bool hit, bool bypass)
+{
+	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+	mark_cache_stats(&dc->accounting.collector, hit, bypass);
+	mark_cache_stats(&s->op.c->accounting.collector, hit, bypass);
+#ifdef CONFIG_CGROUP_BCACHE
+	mark_cache_stats(&(bch_bio_to_cgroup(s->orig_bio)->stats), hit, bypass);
+#endif
+}
+
+void bch_mark_cache_readahead(struct search *s)
+{
+	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+	atomic_inc(&dc->accounting.collector.cache_readaheads);
+	atomic_inc(&s->op.c->accounting.collector.cache_readaheads);
+}
+
+void bch_mark_cache_miss_collision(struct search *s)
+{
+	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+	atomic_inc(&dc->accounting.collector.cache_miss_collisions);
+	atomic_inc(&s->op.c->accounting.collector.cache_miss_collisions);
+}
+
+void bch_mark_sectors_bypassed(struct search *s, int sectors)
+{
+	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+	atomic_add(sectors, &dc->accounting.collector.sectors_bypassed);
+	atomic_add(sectors, &s->op.c->accounting.collector.sectors_bypassed);
+}

drivers/md/bcache/stats.h

@@ -0,0 +1,58 @@
+#ifndef _BCACHE_STATS_H_
+#define _BCACHE_STATS_H_
+
+struct cache_stat_collector {
+	atomic_t cache_hits;
+	atomic_t cache_misses;
+	atomic_t cache_bypass_hits;
+	atomic_t cache_bypass_misses;
+	atomic_t cache_readaheads;
+	atomic_t cache_miss_collisions;
+	atomic_t sectors_bypassed;
+};
+
+struct cache_stats {
+	struct kobject		kobj;
+
+	unsigned long cache_hits;
+	unsigned long cache_misses;
+	unsigned long cache_bypass_hits;
+	unsigned long cache_bypass_misses;
+	unsigned long cache_readaheads;
+	unsigned long cache_miss_collisions;
+	unsigned long sectors_bypassed;
+
+	unsigned		rescale;
+};
+
+struct cache_accounting {
+	struct closure		cl;
+	struct timer_list	timer;
+	atomic_t		closing;
+
+	struct cache_stat_collector collector;
+
+	struct cache_stats total;
+	struct cache_stats five_minute;
+	struct cache_stats hour;
+	struct cache_stats day;
+};
+
+struct search;
+
+void bch_cache_accounting_init(struct cache_accounting *acc,
+			       struct closure *parent);
+
+int bch_cache_accounting_add_kobjs(struct cache_accounting *acc,
+				   struct kobject *parent);
+
+void bch_cache_accounting_clear(struct cache_accounting *acc);
+
+void bch_cache_accounting_destroy(struct cache_accounting *acc);
+
+void bch_mark_cache_accounting(struct search *s, bool hit, bool bypass);
+void bch_mark_cache_readahead(struct search *s);
+void bch_mark_cache_miss_collision(struct search *s);
+void bch_mark_sectors_bypassed(struct search *s, int sectors);
+
+#endif /* _BCACHE_STATS_H_ */

drivers/md/bcache/sysfs.c

@@ -0,0 +1,817 @@
+/*
+ * bcache sysfs interfaces
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "sysfs.h"
+#include "btree.h"
+#include "request.h"
+
+#include <linux/sort.h>
+
+static const char * const cache_replacement_policies[] = {
+	"lru",
+	"fifo",
+	"random",
+	NULL
+};
+
+write_attribute(attach);
+write_attribute(detach);
+write_attribute(unregister);
+write_attribute(stop);
+write_attribute(clear_stats);
+write_attribute(trigger_gc);
+write_attribute(prune_cache);
+write_attribute(flash_vol_create);
+
+read_attribute(bucket_size);
+read_attribute(block_size);
+read_attribute(nbuckets);
+read_attribute(tree_depth);
+read_attribute(root_usage_percent);
+read_attribute(priority_stats);
+read_attribute(btree_cache_size);
+read_attribute(btree_cache_max_chain);
+read_attribute(cache_available_percent);
+read_attribute(written);
+read_attribute(btree_written);
+read_attribute(metadata_written);
+read_attribute(active_journal_entries);
+
+sysfs_time_stats_attribute(btree_gc,	sec, ms);
+sysfs_time_stats_attribute(btree_split, sec, us);
+sysfs_time_stats_attribute(btree_sort,	ms,  us);
+sysfs_time_stats_attribute(btree_read,	ms,  us);
+sysfs_time_stats_attribute(try_harder,	ms,  us);
+
+read_attribute(btree_nodes);
+read_attribute(btree_used_percent);
+read_attribute(average_key_size);
+read_attribute(dirty_data);
+read_attribute(bset_tree_stats);
+
+read_attribute(state);
+read_attribute(cache_read_races);
+read_attribute(writeback_keys_done);
+read_attribute(writeback_keys_failed);
+read_attribute(io_errors);
+read_attribute(congested);
+rw_attribute(congested_read_threshold_us);
+rw_attribute(congested_write_threshold_us);
+
+rw_attribute(sequential_cutoff);
+rw_attribute(sequential_merge);
+rw_attribute(data_csum);
+rw_attribute(cache_mode);
+rw_attribute(writeback_metadata);
+rw_attribute(writeback_running);
+rw_attribute(writeback_percent);
+rw_attribute(writeback_delay);
+rw_attribute(writeback_rate);
+
+rw_attribute(writeback_rate_update_seconds);
+rw_attribute(writeback_rate_d_term);
+rw_attribute(writeback_rate_p_term_inverse);
+rw_attribute(writeback_rate_d_smooth);
+read_attribute(writeback_rate_debug);
+
+rw_attribute(synchronous);
+rw_attribute(journal_delay_ms);
+rw_attribute(discard);
+rw_attribute(running);
+rw_attribute(label);
+rw_attribute(readahead);
+rw_attribute(io_error_limit);
+rw_attribute(io_error_halflife);
+rw_attribute(verify);
+rw_attribute(key_merging_disabled);
+rw_attribute(gc_always_rewrite);
+rw_attribute(freelist_percent);
+rw_attribute(cache_replacement_policy);
+rw_attribute(btree_shrinker_disabled);
+rw_attribute(copy_gc_enabled);
+rw_attribute(size);
+
+SHOW(__bch_cached_dev)
+{
+	struct cached_dev *dc = container_of(kobj, struct cached_dev,
+					     disk.kobj);
+	const char *states[] = { "no cache", "clean", "dirty", "inconsistent" };
+
+#define var(stat)		(dc->stat)
+
+	if (attr == &sysfs_cache_mode)
+		return snprint_string_list(buf, PAGE_SIZE,
+					   bch_cache_modes + 1,
+					   BDEV_CACHE_MODE(&dc->sb));
+
+	sysfs_printf(data_csum,		"%i", dc->disk.data_csum);
+	var_printf(verify,		"%i");
+	var_printf(writeback_metadata,	"%i");
+	var_printf(writeback_running,	"%i");
+	var_print(writeback_delay);
+	var_print(writeback_percent);
+	sysfs_print(writeback_rate,	dc->writeback_rate.rate);
+
+	var_print(writeback_rate_update_seconds);
+	var_print(writeback_rate_d_term);
+	var_print(writeback_rate_p_term_inverse);
+	var_print(writeback_rate_d_smooth);
+
+	if (attr == &sysfs_writeback_rate_debug) {
+		char dirty[20];
+		char derivative[20];
+		char target[20];
+		hprint(dirty,
+		       atomic_long_read(&dc->disk.sectors_dirty) << 9);
+		hprint(derivative,	dc->writeback_rate_derivative << 9);
+		hprint(target,		dc->writeback_rate_target << 9);
+
+		return sprintf(buf,
+			       "rate:\t\t%u\n"
+			       "change:\t\t%i\n"
+			       "dirty:\t\t%s\n"
+			       "derivative:\t%s\n"
+			       "target:\t\t%s\n",
+			       dc->writeback_rate.rate,
+			       dc->writeback_rate_change,
+			       dirty, derivative, target);
+	}
+
+	sysfs_hprint(dirty_data,
+		     atomic_long_read(&dc->disk.sectors_dirty) << 9);
+
+	var_printf(sequential_merge,	"%i");
+	var_hprint(sequential_cutoff);
+	var_hprint(readahead);
+
+	sysfs_print(running,		atomic_read(&dc->running));
+	sysfs_print(state,		states[BDEV_STATE(&dc->sb)]);
+
+	if (attr == &sysfs_label) {
+		memcpy(buf, dc->sb.label, SB_LABEL_SIZE);
+		buf[SB_LABEL_SIZE + 1] = '\0';
+		strcat(buf, "\n");
+		return strlen(buf);
+	}
+
+#undef var
+	return 0;
+}
+SHOW_LOCKED(bch_cached_dev)
+
+STORE(__cached_dev)
+{
+	struct cached_dev *dc = container_of(kobj, struct cached_dev,
+					     disk.kobj);
+	unsigned v = size;
+	struct cache_set *c;
+
+#define d_strtoul(var)		sysfs_strtoul(var, dc->var)
+#define d_strtoi_h(var)		sysfs_hatoi(var, dc->var)
+
+	sysfs_strtoul(data_csum,	dc->disk.data_csum);
+	d_strtoul(verify);
+	d_strtoul(writeback_metadata);
+	d_strtoul(writeback_running);
+	d_strtoul(writeback_delay);
+	sysfs_strtoul_clamp(writeback_rate,
+			    dc->writeback_rate.rate, 1, 1000000);
+	sysfs_strtoul_clamp(writeback_percent, dc->writeback_percent, 0, 40);
+
+	d_strtoul(writeback_rate_update_seconds);
+	d_strtoul(writeback_rate_d_term);
+	d_strtoul(writeback_rate_p_term_inverse);
+	sysfs_strtoul_clamp(writeback_rate_p_term_inverse,
+			    dc->writeback_rate_p_term_inverse, 1, INT_MAX);
+	d_strtoul(writeback_rate_d_smooth);
+
+	d_strtoul(sequential_merge);
+	d_strtoi_h(sequential_cutoff);
+	d_strtoi_h(readahead);
+
+	if (attr == &sysfs_clear_stats)
+		bch_cache_accounting_clear(&dc->accounting);
+
+	if (attr == &sysfs_running &&
+	    strtoul_or_return(buf))
+		bch_cached_dev_run(dc);
+
+	if (attr == &sysfs_cache_mode) {
+		ssize_t v = read_string_list(buf, bch_cache_modes + 1);
+
+		if (v < 0)
+			return v;
+
+		if ((unsigned) v != BDEV_CACHE_MODE(&dc->sb)) {
+			SET_BDEV_CACHE_MODE(&dc->sb, v);
+			bch_write_bdev_super(dc, NULL);
+		}
+	}
+
+	if (attr == &sysfs_label) {
+		memcpy(dc->sb.label, buf, SB_LABEL_SIZE);
+		bch_write_bdev_super(dc, NULL);
+		if (dc->disk.c) {
+			memcpy(dc->disk.c->uuids[dc->disk.id].label,
+			       buf, SB_LABEL_SIZE);
+			bch_uuid_write(dc->disk.c);
+		}
+	}
+
+	if (attr == &sysfs_attach) {
+		if (parse_uuid(buf, dc->sb.set_uuid) < 16)
+			return -EINVAL;
+
+		list_for_each_entry(c, &bch_cache_sets, list) {
+			v = bch_cached_dev_attach(dc, c);
+			if (!v)
+				return size;
+		}
+
+		pr_err("Can't attach %s: cache set not found", buf);
+		size = v;
+	}
+
+	if (attr == &sysfs_detach && dc->disk.c)
+		bch_cached_dev_detach(dc);
+
+	if (attr == &sysfs_stop)
+		bcache_device_stop(&dc->disk);
+
+	return size;
+}
+
+STORE(bch_cached_dev)
+{
+	struct cached_dev *dc = container_of(kobj, struct cached_dev,
+					     disk.kobj);
+
+	mutex_lock(&bch_register_lock);
+	size = __cached_dev_store(kobj, attr, buf, size);
+
+	if (attr == &sysfs_writeback_running)
+		bch_writeback_queue(dc);
+
+	if (attr == &sysfs_writeback_percent)
+		schedule_delayed_work(&dc->writeback_rate_update,
+				      dc->writeback_rate_update_seconds * HZ);
+
+	mutex_unlock(&bch_register_lock);
+	return size;
+}
+
+static struct attribute *bch_cached_dev_files[] = {
+	&sysfs_attach,
+	&sysfs_detach,
+	&sysfs_stop,
+#if 0
+	&sysfs_data_csum,
+#endif
+	&sysfs_cache_mode,
+	&sysfs_writeback_metadata,
+	&sysfs_writeback_running,
+	&sysfs_writeback_delay,
+	&sysfs_writeback_percent,
+	&sysfs_writeback_rate,
+	&sysfs_writeback_rate_update_seconds,
+	&sysfs_writeback_rate_d_term,
+	&sysfs_writeback_rate_p_term_inverse,
+	&sysfs_writeback_rate_d_smooth,
+	&sysfs_writeback_rate_debug,
+	&sysfs_dirty_data,
+	&sysfs_sequential_cutoff,
+	&sysfs_sequential_merge,
+	&sysfs_clear_stats,
+	&sysfs_running,
+	&sysfs_state,
+	&sysfs_label,
+	&sysfs_readahead,
+#ifdef CONFIG_BCACHE_DEBUG
+	&sysfs_verify,
+#endif
+	NULL
+};
+KTYPE(bch_cached_dev);
+
+SHOW(bch_flash_dev)
+{
+	struct bcache_device *d = container_of(kobj, struct bcache_device,
+					       kobj);
+	struct uuid_entry *u = &d->c->uuids[d->id];
+
+	sysfs_printf(data_csum,	"%i", d->data_csum);
+	sysfs_hprint(size,	u->sectors << 9);
+
+	if (attr == &sysfs_label) {
+		memcpy(buf, u->label, SB_LABEL_SIZE);
+		buf[SB_LABEL_SIZE + 1] = '\0';
+		strcat(buf, "\n");
+		return strlen(buf);
+	}
+
+	return 0;
+}
+
+STORE(__bch_flash_dev)
+{
+	struct bcache_device *d = container_of(kobj, struct bcache_device,
+					       kobj);
+	struct uuid_entry *u = &d->c->uuids[d->id];
+
+	sysfs_strtoul(data_csum,	d->data_csum);
+
+	if (attr == &sysfs_size) {
+		uint64_t v;
+		strtoi_h_or_return(buf, v);
+
+		u->sectors = v >> 9;
+		bch_uuid_write(d->c);
+		set_capacity(d->disk, u->sectors);
+	}
+
+	if (attr == &sysfs_label) {
+		memcpy(u->label, buf, SB_LABEL_SIZE);
+		bch_uuid_write(d->c);
+	}
+
+	if (attr == &sysfs_unregister) {
+		atomic_set(&d->detaching, 1);
+		bcache_device_stop(d);
+	}
+
+	return size;
+}
+STORE_LOCKED(bch_flash_dev)
+
+static struct attribute *bch_flash_dev_files[] = {
+	&sysfs_unregister,
+#if 0
+	&sysfs_data_csum,
+#endif
+	&sysfs_label,
+	&sysfs_size,
+	NULL
+};
+KTYPE(bch_flash_dev);
+
+SHOW(__bch_cache_set)
+{
+	unsigned root_usage(struct cache_set *c)
+	{
+		unsigned bytes = 0;
+		struct bkey *k;
+		struct btree *b;
+		struct btree_iter iter;
+
+		goto lock_root;
+
+		do {
+			rw_unlock(false, b);
+lock_root:
+			b = c->root;
+			rw_lock(false, b, b->level);
+		} while (b != c->root);
+
+		for_each_key_filter(b, k, &iter, bch_ptr_bad)
+			bytes += bkey_bytes(k);
+
+		rw_unlock(false, b);
+
+		return (bytes * 100) / btree_bytes(c);
+	}
+
+	size_t cache_size(struct cache_set *c)
+	{
+		size_t ret = 0;
+		struct btree *b;
+
+		mutex_lock(&c->bucket_lock);
+		list_for_each_entry(b, &c->btree_cache, list)
+			ret += 1 << (b->page_order + PAGE_SHIFT);
+
+		mutex_unlock(&c->bucket_lock);
+		return ret;
+	}
+
+	unsigned cache_max_chain(struct cache_set *c)
+	{
+		unsigned ret = 0;
+		struct hlist_head *h;
+
+		mutex_lock(&c->bucket_lock);
+
+		for (h = c->bucket_hash;
+		     h < c->bucket_hash + (1 << BUCKET_HASH_BITS);
+		     h++) {
+			unsigned i = 0;
+			struct hlist_node *p;
+
+			hlist_for_each(p, h)
+				i++;
+
+			ret = max(ret, i);
+		}
+
+		mutex_unlock(&c->bucket_lock);
+		return ret;
+	}
+
+	unsigned btree_used(struct cache_set *c)
+	{
+		return div64_u64(c->gc_stats.key_bytes * 100,
+				 (c->gc_stats.nodes ?: 1) * btree_bytes(c));
+	}
+
+	unsigned average_key_size(struct cache_set *c)
+	{
+		return c->gc_stats.nkeys
+			? div64_u64(c->gc_stats.data, c->gc_stats.nkeys)
+			: 0;
+	}
+
+	struct cache_set *c = container_of(kobj, struct cache_set, kobj);
+
+	sysfs_print(synchronous,		CACHE_SYNC(&c->sb));
+	sysfs_print(journal_delay_ms,		c->journal_delay_ms);
+	sysfs_hprint(bucket_size,		bucket_bytes(c));
+	sysfs_hprint(block_size,		block_bytes(c));
+	sysfs_print(tree_depth,			c->root->level);
+	sysfs_print(root_usage_percent,		root_usage(c));
+
+	sysfs_hprint(btree_cache_size,		cache_size(c));
+	sysfs_print(btree_cache_max_chain,	cache_max_chain(c));
+	sysfs_print(cache_available_percent,	100 - c->gc_stats.in_use);
+
+	sysfs_print_time_stats(&c->btree_gc_time,	btree_gc, sec, ms);
+	sysfs_print_time_stats(&c->btree_split_time,	btree_split, sec, us);
+	sysfs_print_time_stats(&c->sort_time,		btree_sort, ms, us);
+	sysfs_print_time_stats(&c->btree_read_time,	btree_read, ms, us);
+	sysfs_print_time_stats(&c->try_harder_time,	try_harder, ms, us);
+
+	sysfs_print(btree_used_percent,	btree_used(c));
+	sysfs_print(btree_nodes,	c->gc_stats.nodes);
+	sysfs_hprint(dirty_data,	c->gc_stats.dirty);
+	sysfs_hprint(average_key_size,	average_key_size(c));
+
+	sysfs_print(cache_read_races,
+		    atomic_long_read(&c->cache_read_races));
+
+	sysfs_print(writeback_keys_done,
+		    atomic_long_read(&c->writeback_keys_done));
+	sysfs_print(writeback_keys_failed,
+		    atomic_long_read(&c->writeback_keys_failed));
+
+	/* See count_io_errors for why 88 */
+	sysfs_print(io_error_halflife,	c->error_decay * 88);
+	sysfs_print(io_error_limit,	c->error_limit >> IO_ERROR_SHIFT);
+
+	sysfs_hprint(congested,
+		     ((uint64_t) bch_get_congested(c)) << 9);
+	sysfs_print(congested_read_threshold_us,
+		    c->congested_read_threshold_us);
+	sysfs_print(congested_write_threshold_us,
+		    c->congested_write_threshold_us);
+
+	sysfs_print(active_journal_entries,	fifo_used(&c->journal.pin));
+	sysfs_printf(verify,			"%i", c->verify);
+	sysfs_printf(key_merging_disabled,	"%i", c->key_merging_disabled);
+	sysfs_printf(gc_always_rewrite,		"%i", c->gc_always_rewrite);
+	sysfs_printf(btree_shrinker_disabled,	"%i", c->shrinker_disabled);
+	sysfs_printf(copy_gc_enabled,		"%i", c->copy_gc_enabled);
+
+	if (attr == &sysfs_bset_tree_stats)
+		return bch_bset_print_stats(c, buf);
+
+	return 0;
+}
+SHOW_LOCKED(bch_cache_set)
+
+STORE(__bch_cache_set)
+{
+	struct cache_set *c = container_of(kobj, struct cache_set, kobj);
+
+	if (attr == &sysfs_unregister)
+		bch_cache_set_unregister(c);
+
+	if (attr == &sysfs_stop)
+		bch_cache_set_stop(c);
+
+	if (attr == &sysfs_synchronous) {
+		bool sync = strtoul_or_return(buf);
+
+		if (sync != CACHE_SYNC(&c->sb)) {
+			SET_CACHE_SYNC(&c->sb, sync);
+			bcache_write_super(c);
+		}
+	}
+
+	if (attr == &sysfs_flash_vol_create) {
+		int r;
+		uint64_t v;
+		strtoi_h_or_return(buf, v);
+
+		r = bch_flash_dev_create(c, v);
+		if (r)
+			return r;
+	}
+
+	if (attr == &sysfs_clear_stats) {
+		atomic_long_set(&c->writeback_keys_done,	0);
+		atomic_long_set(&c->writeback_keys_failed,	0);
+
+		memset(&c->gc_stats, 0, sizeof(struct gc_stat));
+		bch_cache_accounting_clear(&c->accounting);
+	}
+
+	if (attr == &sysfs_trigger_gc)
+		bch_queue_gc(c);
+
+	if (attr == &sysfs_prune_cache) {
+		struct shrink_control sc;
+		sc.gfp_mask = GFP_KERNEL;
+		sc.nr_to_scan = strtoul_or_return(buf);
+		c->shrink.shrink(&c->shrink, &sc);
+	}
+
+	sysfs_strtoul(congested_read_threshold_us,
+		      c->congested_read_threshold_us);
+	sysfs_strtoul(congested_write_threshold_us,
+		      c->congested_write_threshold_us);
+
+	if (attr == &sysfs_io_error_limit)
+		c->error_limit = strtoul_or_return(buf) << IO_ERROR_SHIFT;
+
+	/* See count_io_errors() for why 88 */
+	if (attr == &sysfs_io_error_halflife)
+		c->error_decay = strtoul_or_return(buf) / 88;
+
+	sysfs_strtoul(journal_delay_ms,		c->journal_delay_ms);
+	sysfs_strtoul(verify,			c->verify);
+	sysfs_strtoul(key_merging_disabled,	c->key_merging_disabled);
+	sysfs_strtoul(gc_always_rewrite,	c->gc_always_rewrite);
+	sysfs_strtoul(btree_shrinker_disabled,	c->shrinker_disabled);
+	sysfs_strtoul(copy_gc_enabled,		c->copy_gc_enabled);
+
+	return size;
+}
+STORE_LOCKED(bch_cache_set)
+
+SHOW(bch_cache_set_internal)
+{
+	struct cache_set *c = container_of(kobj, struct cache_set, internal);
+	return bch_cache_set_show(&c->kobj, attr, buf);
+}
+
+STORE(bch_cache_set_internal)
+{
+	struct cache_set *c = container_of(kobj, struct cache_set, internal);
+	return bch_cache_set_store(&c->kobj, attr, buf, size);
+}
+
+static void bch_cache_set_internal_release(struct kobject *k)
+{
+}
+
+static struct attribute *bch_cache_set_files[] = {
+	&sysfs_unregister,
+	&sysfs_stop,
+	&sysfs_synchronous,
+	&sysfs_journal_delay_ms,
+	&sysfs_flash_vol_create,
+
+	&sysfs_bucket_size,
+	&sysfs_block_size,
+	&sysfs_tree_depth,
+	&sysfs_root_usage_percent,
+	&sysfs_btree_cache_size,
+	&sysfs_cache_available_percent,
+
+	&sysfs_average_key_size,
+	&sysfs_dirty_data,
+
+	&sysfs_io_error_limit,
+	&sysfs_io_error_halflife,
+	&sysfs_congested,
+	&sysfs_congested_read_threshold_us,
+	&sysfs_congested_write_threshold_us,
+	&sysfs_clear_stats,
+	NULL
+};
+KTYPE(bch_cache_set);
+
+static struct attribute *bch_cache_set_internal_files[] = {
+	&sysfs_active_journal_entries,
+
+	sysfs_time_stats_attribute_list(btree_gc, sec, ms)
+	sysfs_time_stats_attribute_list(btree_split, sec, us)
+	sysfs_time_stats_attribute_list(btree_sort, ms, us)
+	sysfs_time_stats_attribute_list(btree_read, ms, us)
+	sysfs_time_stats_attribute_list(try_harder, ms, us)
+
+	&sysfs_btree_nodes,
+	&sysfs_btree_used_percent,
+	&sysfs_btree_cache_max_chain,
+
+	&sysfs_bset_tree_stats,
+	&sysfs_cache_read_races,
+	&sysfs_writeback_keys_done,
+	&sysfs_writeback_keys_failed,
+
+	&sysfs_trigger_gc,
+	&sysfs_prune_cache,
+#ifdef CONFIG_BCACHE_DEBUG
+	&sysfs_verify,
+	&sysfs_key_merging_disabled,
+#endif
+	&sysfs_gc_always_rewrite,
+	&sysfs_btree_shrinker_disabled,
+	&sysfs_copy_gc_enabled,
+	NULL
+};
+KTYPE(bch_cache_set_internal);
+
+SHOW(__bch_cache)
+{
+	struct cache *ca = container_of(kobj, struct cache, kobj);
+
+	sysfs_hprint(bucket_size,	bucket_bytes(ca));
+	sysfs_hprint(block_size,	block_bytes(ca));
+	sysfs_print(nbuckets,		ca->sb.nbuckets);
+	sysfs_print(discard,		ca->discard);
+	sysfs_hprint(written, atomic_long_read(&ca->sectors_written) << 9);
+	sysfs_hprint(btree_written,
+		     atomic_long_read(&ca->btree_sectors_written) << 9);
+	sysfs_hprint(metadata_written,
+		     (atomic_long_read(&ca->meta_sectors_written) +
+		      atomic_long_read(&ca->btree_sectors_written)) << 9);
+
+	sysfs_print(io_errors,
+		    atomic_read(&ca->io_errors) >> IO_ERROR_SHIFT);
+
+	sysfs_print(freelist_percent, ca->free.size * 100 /
+		    ((size_t) ca->sb.nbuckets));
+
+	if (attr == &sysfs_cache_replacement_policy)
+		return snprint_string_list(buf, PAGE_SIZE,
+					   cache_replacement_policies,
+					   CACHE_REPLACEMENT(&ca->sb));
+
+	if (attr == &sysfs_priority_stats) {
+		int cmp(const void *l, const void *r)
+		{	return *((uint16_t *) r) - *((uint16_t *) l); }
+
+		/* Number of quantiles we compute */
+		const unsigned nq = 31;
+
+		size_t n = ca->sb.nbuckets, i, unused, btree;
+		uint64_t sum = 0;
+		uint16_t q[nq], *p, *cached;
+		ssize_t ret;
+
+		cached = p = vmalloc(ca->sb.nbuckets * sizeof(uint16_t));
+		if (!p)
+			return -ENOMEM;
+
+		mutex_lock(&ca->set->bucket_lock);
+		for (i = ca->sb.first_bucket; i < n; i++)
+			p[i] = ca->buckets[i].prio;
+		mutex_unlock(&ca->set->bucket_lock);
+
+		sort(p, n, sizeof(uint16_t), cmp, NULL);
+
+		while (n &&
+		       !cached[n - 1])
+			--n;
+
+		unused = ca->sb.nbuckets - n;
+
+		while (cached < p + n &&
+		       *cached == BTREE_PRIO)
+			cached++;
+
+		btree = cached - p;
+		n -= btree;
+
+		for (i = 0; i < n; i++)
+			sum += INITIAL_PRIO - cached[i];
+
+		if (n)
+			do_div(sum, n);
+
+		for (i = 0; i < nq; i++)
+			q[i] = INITIAL_PRIO - cached[n * (i + 1) / (nq + 1)];
+
+		vfree(p);
+
+		ret = snprintf(buf, PAGE_SIZE,
+			       "Unused:		%zu%%\n"
+			       "Metadata:	%zu%%\n"
+			       "Average:	%llu\n"
+			       "Sectors per Q:	%zu\n"
+			       "Quantiles:	[",
+			       unused * 100 / (size_t) ca->sb.nbuckets,
+			       btree * 100 / (size_t) ca->sb.nbuckets, sum,
+			       n * ca->sb.bucket_size / (nq + 1));
+
+		for (i = 0; i < nq && ret < (ssize_t) PAGE_SIZE; i++)
+			ret += snprintf(buf + ret, PAGE_SIZE - ret,
+					i < nq - 1 ? "%u " : "%u]\n", q[i]);
+
+		buf[PAGE_SIZE - 1] = '\0';
+		return ret;
+	}
+
+	return 0;
+}
+SHOW_LOCKED(bch_cache)
+
+STORE(__bch_cache)
+{
+	struct cache *ca = container_of(kobj, struct cache, kobj);
+
+	if (attr == &sysfs_discard) {
+		bool v = strtoul_or_return(buf);
+
+		if (blk_queue_discard(bdev_get_queue(ca->bdev)))
+			ca->discard = v;
+
+		if (v != CACHE_DISCARD(&ca->sb)) {
+			SET_CACHE_DISCARD(&ca->sb, v);
+			bcache_write_super(ca->set);
+		}
+	}
+
+	if (attr == &sysfs_cache_replacement_policy) {
+		ssize_t v = read_string_list(buf, cache_replacement_policies);
+
+		if (v < 0)
+			return v;
+
+		if ((unsigned) v != CACHE_REPLACEMENT(&ca->sb)) {
+			mutex_lock(&ca->set->bucket_lock);
+			SET_CACHE_REPLACEMENT(&ca->sb, v);
+			mutex_unlock(&ca->set->bucket_lock);
+
+			bcache_write_super(ca->set);
+		}
+	}
+
+	if (attr == &sysfs_freelist_percent) {
+		DECLARE_FIFO(long, free);
+		long i;
+		size_t p = strtoul_or_return(buf);
+
+		p = clamp_t(size_t,
+			    ((size_t) ca->sb.nbuckets * p) / 100,
+			    roundup_pow_of_two(ca->sb.nbuckets) >> 9,
+			    ca->sb.nbuckets / 2);
+
+		if (!init_fifo_exact(&free, p, GFP_KERNEL))
+			return -ENOMEM;
+
+		mutex_lock(&ca->set->bucket_lock);
+
+		fifo_move(&free, &ca->free);
+		fifo_swap(&free, &ca->free);
+
+		mutex_unlock(&ca->set->bucket_lock);
+
+		while (fifo_pop(&free, i))
+			atomic_dec(&ca->buckets[i].pin);
+
+		free_fifo(&free);
+	}
+
+	if (attr == &sysfs_clear_stats) {
+		atomic_long_set(&ca->sectors_written, 0);
+		atomic_long_set(&ca->btree_sectors_written, 0);
+		atomic_long_set(&ca->meta_sectors_written, 0);
+		atomic_set(&ca->io_count, 0);
+		atomic_set(&ca->io_errors, 0);
+	}
+
+	return size;
+}
+STORE_LOCKED(bch_cache)
+
+static struct attribute *bch_cache_files[] = {
+	&sysfs_bucket_size,
+	&sysfs_block_size,
+	&sysfs_nbuckets,
+	&sysfs_priority_stats,
+	&sysfs_discard,
+	&sysfs_written,
+	&sysfs_btree_written,
+	&sysfs_metadata_written,
+	&sysfs_io_errors,
+	&sysfs_clear_stats,
+	&sysfs_freelist_percent,
+	&sysfs_cache_replacement_policy,
+	NULL
+};
+KTYPE(bch_cache);

drivers/md/bcache/sysfs.h

@@ -0,0 +1,110 @@
+#ifndef _BCACHE_SYSFS_H_
+#define _BCACHE_SYSFS_H_
+
+#define KTYPE(type)							\
+struct kobj_type type ## _ktype = {					\
+	.release	= type ## _release,				\
+	.sysfs_ops	= &((const struct sysfs_ops) {			\
+		.show	= type ## _show,				\
+		.store	= type ## _store				\
+	}),								\
+	.default_attrs	= type ## _files				\
+}
+
+#define SHOW(fn)							\
+static ssize_t fn ## _show(struct kobject *kobj, struct attribute *attr,\
+			   char *buf)					\
+
+#define STORE(fn)							\
+static ssize_t fn ## _store(struct kobject *kobj, struct attribute *attr,\
+			    const char *buf, size_t size)		\
+
+#define SHOW_LOCKED(fn)							\
+SHOW(fn)								\
+{									\
+	ssize_t ret;							\
+	mutex_lock(&bch_register_lock);					\
+	ret = __ ## fn ## _show(kobj, attr, buf);			\
+	mutex_unlock(&bch_register_lock);				\
+	return ret;							\
+}
+
+#define STORE_LOCKED(fn)						\
+STORE(fn)								\
+{									\
+	ssize_t ret;							\
+	mutex_lock(&bch_register_lock);					\
+	ret = __ ## fn ## _store(kobj, attr, buf, size);		\
+	mutex_unlock(&bch_register_lock);				\
+	return ret;							\
+}
+
+#define __sysfs_attribute(_name, _mode)					\
+	static struct attribute sysfs_##_name =				\
+		{ .name = #_name, .mode = _mode }
+
+#define write_attribute(n)	__sysfs_attribute(n, S_IWUSR)
+#define read_attribute(n)	__sysfs_attribute(n, S_IRUGO)
+#define rw_attribute(n)		__sysfs_attribute(n, S_IRUGO|S_IWUSR)
+
+#define sysfs_printf(file, fmt, ...)					\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return snprintf(buf, PAGE_SIZE, fmt "\n", __VA_ARGS__);	\
+} while (0)
+
+#define sysfs_print(file, var)						\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return snprint(buf, PAGE_SIZE, var);			\
+} while (0)
+
+#define sysfs_hprint(file, val)						\
+do {									\
+	if (attr == &sysfs_ ## file) {					\
+		ssize_t ret = hprint(buf, val);				\
+		strcat(buf, "\n");					\
+		return ret + 1;						\
+	}								\
+} while (0)
+
+#define var_printf(_var, fmt)	sysfs_printf(_var, fmt, var(_var))
+#define var_print(_var)		sysfs_print(_var, var(_var))
+#define var_hprint(_var)	sysfs_hprint(_var, var(_var))
+
+#define sysfs_strtoul(file, var)					\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return strtoul_safe(buf, var) ?: (ssize_t) size;	\
+} while (0)
+
+#define sysfs_strtoul_clamp(file, var, min, max)			\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return strtoul_safe_clamp(buf, var, min, max)		\
+			?: (ssize_t) size;				\
+} while (0)
+
+#define strtoul_or_return(cp)						\
+({									\
+	unsigned long _v;						\
+	int _r = kstrtoul(cp, 10, &_v);					\
+	if (_r)								\
+		return _r;						\
+	_v;								\
+})
+
+#define strtoi_h_or_return(cp, v)					\
+do {									\
+	int _r = strtoi_h(cp, &v);					\
+	if (_r)								\
+		return _r;						\
+} while (0)
+
+#define sysfs_hatoi(file, var)						\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return strtoi_h(buf, &var) ?: (ssize_t) size;		\
+} while (0)
+
+#endif  /* _BCACHE_SYSFS_H_ */

drivers/md/bcache/trace.c

@@ -0,0 +1,26 @@
+#include "bcache.h"
+#include "btree.h"
+#include "request.h"
+
+#include <linux/module.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/bcache.h>
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_request_start);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_request_end);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_passthrough);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_cache_hit);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_cache_miss);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_read_retry);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_writethrough);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_writeback);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_write_skip);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_read);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_write);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_write_dirty);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_read_dirty);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_journal_write);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_cache_insert);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_gc_start);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_gc_end);

drivers/md/bcache/util.c

@@ -0,0 +1,389 @@
+/*
+ * random utiility code, for bcache but in theory not specific to bcache
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/types.h>
+
+#include "util.h"
+
+#define simple_strtoint(c, end, base)	simple_strtol(c, end, base)
+#define simple_strtouint(c, end, base)	simple_strtoul(c, end, base)
+
+#define STRTO_H(name, type)					\
+int name ## _h(const char *cp, type *res)		        \
+{								\
+	int u = 0;						\
+	char *e;						\
+	type i = simple_ ## name(cp, &e, 10);			\
+								\
+	switch (tolower(*e)) {					\
+	default:						\
+		return -EINVAL;					\
+	case 'y':						\
+	case 'z':						\
+		u++;						\
+	case 'e':						\
+		u++;						\
+	case 'p':						\
+		u++;						\
+	case 't':						\
+		u++;						\
+	case 'g':						\
+		u++;						\
+	case 'm':						\
+		u++;						\
+	case 'k':						\
+		u++;						\
+		if (e++ == cp)					\
+			return -EINVAL;				\
+	case '\n':						\
+	case '\0':						\
+		if (*e == '\n')					\
+			e++;					\
+	}							\
+								\
+	if (*e)							\
+		return -EINVAL;					\
+								\
+	while (u--) {						\
+		if ((type) ~0 > 0 &&				\
+		    (type) ~0 / 1024 <= i)			\
+			return -EINVAL;				\
+		if ((i > 0 && ANYSINT_MAX(type) / 1024 < i) ||	\
+		    (i < 0 && -ANYSINT_MAX(type) / 1024 > i))	\
+			return -EINVAL;				\
+		i *= 1024;					\
+	}							\
+								\
+	*res = i;						\
+	return 0;						\
+}								\
+EXPORT_SYMBOL_GPL(name ## _h);
+
+STRTO_H(strtoint, int)
+STRTO_H(strtouint, unsigned int)
+STRTO_H(strtoll, long long)
+STRTO_H(strtoull, unsigned long long)
+
+ssize_t hprint(char *buf, int64_t v)
+{
+	static const char units[] = "?kMGTPEZY";
+	char dec[3] = "";
+	int u, t = 0;
+
+	for (u = 0; v >= 1024 || v <= -1024; u++) {
+		t = v & ~(~0 << 10);
+		v >>= 10;
+	}
+
+	if (!u)
+		return sprintf(buf, "%llu", v);
+
+	if (v < 100 && v > -100)
+		sprintf(dec, ".%i", t / 100);
+
+	return sprintf(buf, "%lli%s%c", v, dec, units[u]);
+}
+EXPORT_SYMBOL_GPL(hprint);
+
+ssize_t snprint_string_list(char *buf, size_t size, const char * const list[],
+			    size_t selected)
+{
+	char *out = buf;
+	size_t i;
+
+	for (i = 0; list[i]; i++)
+		out += snprintf(out, buf + size - out,
+				i == selected ? "[%s] " : "%s ", list[i]);
+
+	out[-1] = '\n';
+	return out - buf;
+}
+EXPORT_SYMBOL_GPL(snprint_string_list);
+
+ssize_t read_string_list(const char *buf, const char * const list[])
+{
+	size_t i;
+	char *s, *d = kstrndup(buf, PAGE_SIZE - 1, GFP_KERNEL);
+	if (!d)
+		return -ENOMEM;
+
+	s = strim(d);
+
+	for (i = 0; list[i]; i++)
+		if (!strcmp(list[i], s))
+			break;
+
+	kfree(d);
+
+	if (!list[i])
+		return -EINVAL;
+
+	return i;
+}
+EXPORT_SYMBOL_GPL(read_string_list);
+
+bool is_zero(const char *p, size_t n)
+{
+	size_t i;
+
+	for (i = 0; i < n; i++)
+		if (p[i])
+			return false;
+	return true;
+}
+EXPORT_SYMBOL_GPL(is_zero);
+
+int parse_uuid(const char *s, char *uuid)
+{
+	size_t i, j, x;
+	memset(uuid, 0, 16);
+
+	for (i = 0, j = 0;
+	     i < strspn(s, "-0123456789:ABCDEFabcdef") && j < 32;
+	     i++) {
+		x = s[i] | 32;
+
+		switch (x) {
+		case '0'...'9':
+			x -= '0';
+			break;
+		case 'a'...'f':
+			x -= 'a' - 10;
+			break;
+		default:
+			continue;
+		}
+
+		if (!(j & 1))
+			x <<= 4;
+		uuid[j++ >> 1] |= x;
+	}
+	return i;
+}
+EXPORT_SYMBOL_GPL(parse_uuid);
+
+void time_stats_update(struct time_stats *stats, uint64_t start_time)
+{
+	uint64_t now		= local_clock();
+	uint64_t duration	= time_after64(now, start_time)
+		? now - start_time : 0;
+	uint64_t last		= time_after64(now, stats->last)
+		? now - stats->last : 0;
+
+	stats->max_duration = max(stats->max_duration, duration);
+
+	if (stats->last) {
+		ewma_add(stats->average_duration, duration, 8, 8);
+
+		if (stats->average_frequency)
+			ewma_add(stats->average_frequency, last, 8, 8);
+		else
+			stats->average_frequency  = last << 8;
+	} else {
+		stats->average_duration  = duration << 8;
+	}
+
+	stats->last = now ?: 1;
+}
+EXPORT_SYMBOL_GPL(time_stats_update);
+
+unsigned next_delay(struct ratelimit *d, uint64_t done)
+{
+	uint64_t now = local_clock();
+
+	d->next += div_u64(done, d->rate);
+
+	return time_after64(d->next, now)
+		? div_u64(d->next - now, NSEC_PER_SEC / HZ)
+		: 0;
+}
+EXPORT_SYMBOL_GPL(next_delay);
+
+void bio_map(struct bio *bio, void *base)
+{
+	size_t size = bio->bi_size;
+	struct bio_vec *bv = bio->bi_io_vec;
+
+	BUG_ON(!bio->bi_size);
+	BUG_ON(bio->bi_vcnt);
+
+	bv->bv_offset = base ? ((unsigned long) base) % PAGE_SIZE : 0;
+	goto start;
+
+	for (; size; bio->bi_vcnt++, bv++) {
+		bv->bv_offset	= 0;
+start:		bv->bv_len	= min_t(size_t, PAGE_SIZE - bv->bv_offset,
+					size);
+		if (base) {
+			bv->bv_page = is_vmalloc_addr(base)
+				? vmalloc_to_page(base)
+				: virt_to_page(base);
+
+			base += bv->bv_len;
+		}
+
+		size -= bv->bv_len;
+	}
+}
+EXPORT_SYMBOL_GPL(bio_map);
+
+int bio_alloc_pages(struct bio *bio, gfp_t gfp)
+{
+	int i;
+	struct bio_vec *bv;
+
+	bio_for_each_segment(bv, bio, i) {
+		bv->bv_page = alloc_page(gfp);
+		if (!bv->bv_page) {
+			while (bv-- != bio->bi_io_vec + bio->bi_idx)
+				__free_page(bv->bv_page);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(bio_alloc_pages);
+
+/*
+ * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group (Any
+ * use permitted, subject to terms of PostgreSQL license; see.)
+
+ * If we have a 64-bit integer type, then a 64-bit CRC looks just like the
+ * usual sort of implementation. (See Ross Williams' excellent introduction
+ * A PAINLESS GUIDE TO CRC ERROR DETECTION ALGORITHMS, available from
+ * ftp://ftp.rocksoft.com/papers/crc_v3.txt or several other net sites.)
+ * If we have no working 64-bit type, then fake it with two 32-bit registers.
+ *
+ * The present implementation is a normal (not "reflected", in Williams'
+ * terms) 64-bit CRC, using initial all-ones register contents and a final
+ * bit inversion. The chosen polynomial is borrowed from the DLT1 spec
+ * (ECMA-182, available from http://www.ecma.ch/ecma1/STAND/ECMA-182.HTM):
+ *
+ * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
+ * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
+ * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
+ * x^7 + x^4 + x + 1
+*/
+
+static const uint64_t crc_table[256] = {
+	0x0000000000000000, 0x42F0E1EBA9EA3693, 0x85E1C3D753D46D26,
+	0xC711223CFA3E5BB5, 0x493366450E42ECDF, 0x0BC387AEA7A8DA4C,
+	0xCCD2A5925D9681F9, 0x8E224479F47CB76A, 0x9266CC8A1C85D9BE,
+	0xD0962D61B56FEF2D, 0x17870F5D4F51B498, 0x5577EEB6E6BB820B,
+	0xDB55AACF12C73561, 0x99A54B24BB2D03F2, 0x5EB4691841135847,
+	0x1C4488F3E8F96ED4, 0x663D78FF90E185EF, 0x24CD9914390BB37C,
+	0xE3DCBB28C335E8C9, 0xA12C5AC36ADFDE5A, 0x2F0E1EBA9EA36930,
+	0x6DFEFF5137495FA3, 0xAAEFDD6DCD770416, 0xE81F3C86649D3285,
+	0xF45BB4758C645C51, 0xB6AB559E258E6AC2, 0x71BA77A2DFB03177,
+	0x334A9649765A07E4, 0xBD68D2308226B08E, 0xFF9833DB2BCC861D,
+	0x388911E7D1F2DDA8, 0x7A79F00C7818EB3B, 0xCC7AF1FF21C30BDE,
+	0x8E8A101488293D4D, 0x499B3228721766F8, 0x0B6BD3C3DBFD506B,
+	0x854997BA2F81E701, 0xC7B97651866BD192, 0x00A8546D7C558A27,
+	0x4258B586D5BFBCB4, 0x5E1C3D753D46D260, 0x1CECDC9E94ACE4F3,
+	0xDBFDFEA26E92BF46, 0x990D1F49C77889D5, 0x172F5B3033043EBF,
+	0x55DFBADB9AEE082C, 0x92CE98E760D05399, 0xD03E790CC93A650A,
+	0xAA478900B1228E31, 0xE8B768EB18C8B8A2, 0x2FA64AD7E2F6E317,
+	0x6D56AB3C4B1CD584, 0xE374EF45BF6062EE, 0xA1840EAE168A547D,
+	0x66952C92ECB40FC8, 0x2465CD79455E395B, 0x3821458AADA7578F,
+	0x7AD1A461044D611C, 0xBDC0865DFE733AA9, 0xFF3067B657990C3A,
+	0x711223CFA3E5BB50, 0x33E2C2240A0F8DC3, 0xF4F3E018F031D676,
+	0xB60301F359DBE0E5, 0xDA050215EA6C212F, 0x98F5E3FE438617BC,
+	0x5FE4C1C2B9B84C09, 0x1D14202910527A9A, 0x93366450E42ECDF0,
+	0xD1C685BB4DC4FB63, 0x16D7A787B7FAA0D6, 0x5427466C1E109645,
+	0x4863CE9FF6E9F891, 0x0A932F745F03CE02, 0xCD820D48A53D95B7,
+	0x8F72ECA30CD7A324, 0x0150A8DAF8AB144E, 0x43A04931514122DD,
+	0x84B16B0DAB7F7968, 0xC6418AE602954FFB, 0xBC387AEA7A8DA4C0,
+	0xFEC89B01D3679253, 0x39D9B93D2959C9E6, 0x7B2958D680B3FF75,
+	0xF50B1CAF74CF481F, 0xB7FBFD44DD257E8C, 0x70EADF78271B2539,
+	0x321A3E938EF113AA, 0x2E5EB66066087D7E, 0x6CAE578BCFE24BED,
+	0xABBF75B735DC1058, 0xE94F945C9C3626CB, 0x676DD025684A91A1,
+	0x259D31CEC1A0A732, 0xE28C13F23B9EFC87, 0xA07CF2199274CA14,
+	0x167FF3EACBAF2AF1, 0x548F120162451C62, 0x939E303D987B47D7,
+	0xD16ED1D631917144, 0x5F4C95AFC5EDC62E, 0x1DBC74446C07F0BD,
+	0xDAAD56789639AB08, 0x985DB7933FD39D9B, 0x84193F60D72AF34F,
+	0xC6E9DE8B7EC0C5DC, 0x01F8FCB784FE9E69, 0x43081D5C2D14A8FA,
+	0xCD2A5925D9681F90, 0x8FDAB8CE70822903, 0x48CB9AF28ABC72B6,
+	0x0A3B7B1923564425, 0x70428B155B4EAF1E, 0x32B26AFEF2A4998D,
+	0xF5A348C2089AC238, 0xB753A929A170F4AB, 0x3971ED50550C43C1,
+	0x7B810CBBFCE67552, 0xBC902E8706D82EE7, 0xFE60CF6CAF321874,
+	0xE224479F47CB76A0, 0xA0D4A674EE214033, 0x67C58448141F1B86,
+	0x253565A3BDF52D15, 0xAB1721DA49899A7F, 0xE9E7C031E063ACEC,
+	0x2EF6E20D1A5DF759, 0x6C0603E6B3B7C1CA, 0xF6FAE5C07D3274CD,
+	0xB40A042BD4D8425E, 0x731B26172EE619EB, 0x31EBC7FC870C2F78,
+	0xBFC9838573709812, 0xFD39626EDA9AAE81, 0x3A28405220A4F534,
+	0x78D8A1B9894EC3A7, 0x649C294A61B7AD73, 0x266CC8A1C85D9BE0,
+	0xE17DEA9D3263C055, 0xA38D0B769B89F6C6, 0x2DAF4F0F6FF541AC,
+	0x6F5FAEE4C61F773F, 0xA84E8CD83C212C8A, 0xEABE6D3395CB1A19,
+	0x90C79D3FEDD3F122, 0xD2377CD44439C7B1, 0x15265EE8BE079C04,
+	0x57D6BF0317EDAA97, 0xD9F4FB7AE3911DFD, 0x9B041A914A7B2B6E,
+	0x5C1538ADB04570DB, 0x1EE5D94619AF4648, 0x02A151B5F156289C,
+	0x4051B05E58BC1E0F, 0x87409262A28245BA, 0xC5B073890B687329,
+	0x4B9237F0FF14C443, 0x0962D61B56FEF2D0, 0xCE73F427ACC0A965,
+	0x8C8315CC052A9FF6, 0x3A80143F5CF17F13, 0x7870F5D4F51B4980,
+	0xBF61D7E80F251235, 0xFD913603A6CF24A6, 0x73B3727A52B393CC,
+	0x31439391FB59A55F, 0xF652B1AD0167FEEA, 0xB4A25046A88DC879,
+	0xA8E6D8B54074A6AD, 0xEA16395EE99E903E, 0x2D071B6213A0CB8B,
+	0x6FF7FA89BA4AFD18, 0xE1D5BEF04E364A72, 0xA3255F1BE7DC7CE1,
+	0x64347D271DE22754, 0x26C49CCCB40811C7, 0x5CBD6CC0CC10FAFC,
+	0x1E4D8D2B65FACC6F, 0xD95CAF179FC497DA, 0x9BAC4EFC362EA149,
+	0x158E0A85C2521623, 0x577EEB6E6BB820B0, 0x906FC95291867B05,
+	0xD29F28B9386C4D96, 0xCEDBA04AD0952342, 0x8C2B41A1797F15D1,
+	0x4B3A639D83414E64, 0x09CA82762AAB78F7, 0x87E8C60FDED7CF9D,
+	0xC51827E4773DF90E, 0x020905D88D03A2BB, 0x40F9E43324E99428,
+	0x2CFFE7D5975E55E2, 0x6E0F063E3EB46371, 0xA91E2402C48A38C4,
+	0xEBEEC5E96D600E57, 0x65CC8190991CB93D, 0x273C607B30F68FAE,
+	0xE02D4247CAC8D41B, 0xA2DDA3AC6322E288, 0xBE992B5F8BDB8C5C,
+	0xFC69CAB42231BACF, 0x3B78E888D80FE17A, 0x7988096371E5D7E9,
+	0xF7AA4D1A85996083, 0xB55AACF12C735610, 0x724B8ECDD64D0DA5,
+	0x30BB6F267FA73B36, 0x4AC29F2A07BFD00D, 0x08327EC1AE55E69E,
+	0xCF235CFD546BBD2B, 0x8DD3BD16FD818BB8, 0x03F1F96F09FD3CD2,
+	0x41011884A0170A41, 0x86103AB85A2951F4, 0xC4E0DB53F3C36767,
+	0xD8A453A01B3A09B3, 0x9A54B24BB2D03F20, 0x5D45907748EE6495,
+	0x1FB5719CE1045206, 0x919735E51578E56C, 0xD367D40EBC92D3FF,
+	0x1476F63246AC884A, 0x568617D9EF46BED9, 0xE085162AB69D5E3C,
+	0xA275F7C11F7768AF, 0x6564D5FDE549331A, 0x279434164CA30589,
+	0xA9B6706FB8DFB2E3, 0xEB46918411358470, 0x2C57B3B8EB0BDFC5,
+	0x6EA7525342E1E956, 0x72E3DAA0AA188782, 0x30133B4B03F2B111,
+	0xF7021977F9CCEAA4, 0xB5F2F89C5026DC37, 0x3BD0BCE5A45A6B5D,
+	0x79205D0E0DB05DCE, 0xBE317F32F78E067B, 0xFCC19ED95E6430E8,
+	0x86B86ED5267CDBD3, 0xC4488F3E8F96ED40, 0x0359AD0275A8B6F5,
+	0x41A94CE9DC428066, 0xCF8B0890283E370C, 0x8D7BE97B81D4019F,
+	0x4A6ACB477BEA5A2A, 0x089A2AACD2006CB9, 0x14DEA25F3AF9026D,
+	0x562E43B4931334FE, 0x913F6188692D6F4B, 0xD3CF8063C0C759D8,
+	0x5DEDC41A34BBEEB2, 0x1F1D25F19D51D821, 0xD80C07CD676F8394,
+	0x9AFCE626CE85B507
+};
+
+uint64_t crc64_update(uint64_t crc, const void *_data, size_t len)
+{
+	const unsigned char *data = _data;
+
+	while (len--) {
+		int i = ((int) (crc >> 56) ^ *data++) & 0xFF;
+		crc = crc_table[i] ^ (crc << 8);
+	}
+
+	return crc;
+}
+EXPORT_SYMBOL(crc64_update);
+
+uint64_t crc64(const void *data, size_t len)
+{
+	uint64_t crc = 0xffffffffffffffff;
+
+	crc = crc64_update(crc, data, len);
+
+	return crc ^ 0xffffffffffffffff;
+}
+EXPORT_SYMBOL(crc64);

drivers/md/bcache/util.h

@@ -0,0 +1,589 @@
+
+#ifndef _BCACHE_UTIL_H
+#define _BCACHE_UTIL_H
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/llist.h>
+#include <linux/ratelimit.h>
+#include <linux/vmalloc.h>
+#include <linux/workqueue.h>
+
+#include "closure.h"
+
+#define PAGE_SECTORS		(PAGE_SIZE / 512)
+
+struct closure;
+
+#include <trace/events/bcache.h>
+
+#ifdef CONFIG_BCACHE_EDEBUG
+
+#define atomic_dec_bug(v)	BUG_ON(atomic_dec_return(v) < 0)
+#define atomic_inc_bug(v, i)	BUG_ON(atomic_inc_return(v) <= i)
+
+#else /* EDEBUG */
+
+#define atomic_dec_bug(v)	atomic_dec(v)
+#define atomic_inc_bug(v, i)	atomic_inc(v)
+
+#endif
+
+#define BITMASK(name, type, field, offset, size)		\
+static inline uint64_t name(const type *k)			\
+{ return (k->field >> offset) & ~(((uint64_t) ~0) << size); }	\
+								\
+static inline void SET_##name(type *k, uint64_t v)		\
+{								\
+	k->field &= ~(~((uint64_t) ~0 << size) << offset);	\
+	k->field |= v << offset;				\
+}
+
+#define DECLARE_HEAP(type, name)					\
+	struct {							\
+		size_t size, used;					\
+		type *data;						\
+	} name
+
+#define init_heap(heap, _size, gfp)					\
+({									\
+	size_t _bytes;							\
+	(heap)->used = 0;						\
+	(heap)->size = (_size);						\
+	_bytes = (heap)->size * sizeof(*(heap)->data);			\
+	(heap)->data = NULL;						\
+	if (_bytes < KMALLOC_MAX_SIZE)					\
+		(heap)->data = kmalloc(_bytes, (gfp));			\
+	if ((!(heap)->data) && ((gfp) & GFP_KERNEL))			\
+		(heap)->data = vmalloc(_bytes);				\
+	(heap)->data;							\
+})
+
+#define free_heap(heap)							\
+do {									\
+	if (is_vmalloc_addr((heap)->data))				\
+		vfree((heap)->data);					\
+	else								\
+		kfree((heap)->data);					\
+	(heap)->data = NULL;						\
+} while (0)
+
+#define heap_swap(h, i, j)	swap((h)->data[i], (h)->data[j])
+
+#define heap_sift(h, i, cmp)						\
+do {									\
+	size_t _r, _j = i;						\
+									\
+	for (; _j * 2 + 1 < (h)->used; _j = _r) {			\
+		_r = _j * 2 + 1;					\
+		if (_r + 1 < (h)->used &&				\
+		    cmp((h)->data[_r], (h)->data[_r + 1]))		\
+			_r++;						\
+									\
+		if (cmp((h)->data[_r], (h)->data[_j]))			\
+			break;						\
+		heap_swap(h, _r, _j);					\
+	}								\
+} while (0)
+
+#define heap_sift_down(h, i, cmp)					\
+do {									\
+	while (i) {							\
+		size_t p = (i - 1) / 2;					\
+		if (cmp((h)->data[i], (h)->data[p]))			\
+			break;						\
+		heap_swap(h, i, p);					\
+		i = p;							\
+	}								\
+} while (0)
+
+#define heap_add(h, d, cmp)						\
+({									\
+	bool _r = !heap_full(h);					\
+	if (_r) {							\
+		size_t _i = (h)->used++;				\
+		(h)->data[_i] = d;					\
+									\
+		heap_sift_down(h, _i, cmp);				\
+		heap_sift(h, _i, cmp);					\
+	}								\
+	_r;								\
+})
+
+#define heap_pop(h, d, cmp)						\
+({									\
+	bool _r = (h)->used;						\
+	if (_r) {							\
+		(d) = (h)->data[0];					\
+		(h)->used--;						\
+		heap_swap(h, 0, (h)->used);				\
+		heap_sift(h, 0, cmp);					\
+	}								\
+	_r;								\
+})
+
+#define heap_peek(h)	((h)->size ? (h)->data[0] : NULL)
+
+#define heap_full(h)	((h)->used == (h)->size)
+
+#define DECLARE_FIFO(type, name)					\
+	struct {							\
+		size_t front, back, size, mask;				\
+		type *data;						\
+	} name
+
+#define fifo_for_each(c, fifo, iter)					\
+	for (iter = (fifo)->front;					\
+	     c = (fifo)->data[iter], iter != (fifo)->back;		\
+	     iter = (iter + 1) & (fifo)->mask)
+
+#define __init_fifo(fifo, gfp)						\
+({									\
+	size_t _allocated_size, _bytes;					\
+	BUG_ON(!(fifo)->size);						\
+									\
+	_allocated_size = roundup_pow_of_two((fifo)->size + 1);		\
+	_bytes = _allocated_size * sizeof(*(fifo)->data);		\
+									\
+	(fifo)->mask = _allocated_size - 1;				\
+	(fifo)->front = (fifo)->back = 0;				\
+	(fifo)->data = NULL;						\
+									\
+	if (_bytes < KMALLOC_MAX_SIZE)					\
+		(fifo)->data = kmalloc(_bytes, (gfp));			\
+	if ((!(fifo)->data) && ((gfp) & GFP_KERNEL))			\
+		(fifo)->data = vmalloc(_bytes);				\
+	(fifo)->data;							\
+})
+
+#define init_fifo_exact(fifo, _size, gfp)				\
+({									\
+	(fifo)->size = (_size);						\
+	__init_fifo(fifo, gfp);						\
+})
+
+#define init_fifo(fifo, _size, gfp)					\
+({									\
+	(fifo)->size = (_size);						\
+	if ((fifo)->size > 4)						\
+		(fifo)->size = roundup_pow_of_two((fifo)->size) - 1;	\
+	__init_fifo(fifo, gfp);						\
+})
+
+#define free_fifo(fifo)							\
+do {									\
+	if (is_vmalloc_addr((fifo)->data))				\
+		vfree((fifo)->data);					\
+	else								\
+		kfree((fifo)->data);					\
+	(fifo)->data = NULL;						\
+} while (0)
+
+#define fifo_used(fifo)		(((fifo)->back - (fifo)->front) & (fifo)->mask)
+#define fifo_free(fifo)		((fifo)->size - fifo_used(fifo))
+
+#define fifo_empty(fifo)	(!fifo_used(fifo))
+#define fifo_full(fifo)		(!fifo_free(fifo))
+
+#define fifo_front(fifo)	((fifo)->data[(fifo)->front])
+#define fifo_back(fifo)							\
+	((fifo)->data[((fifo)->back - 1) & (fifo)->mask])
+
+#define fifo_idx(fifo, p)	(((p) - &fifo_front(fifo)) & (fifo)->mask)
+
+#define fifo_push_back(fifo, i)						\
+({									\
+	bool _r = !fifo_full((fifo));					\
+	if (_r) {							\
+		(fifo)->data[(fifo)->back++] = (i);			\
+		(fifo)->back &= (fifo)->mask;				\
+	}								\
+	_r;								\
+})
+
+#define fifo_pop_front(fifo, i)						\
+({									\
+	bool _r = !fifo_empty((fifo));					\
+	if (_r) {							\
+		(i) = (fifo)->data[(fifo)->front++];			\
+		(fifo)->front &= (fifo)->mask;				\
+	}								\
+	_r;								\
+})
+
+#define fifo_push_front(fifo, i)					\
+({									\
+	bool _r = !fifo_full((fifo));					\
+	if (_r) {							\
+		--(fifo)->front;					\
+		(fifo)->front &= (fifo)->mask;				\
+		(fifo)->data[(fifo)->front] = (i);			\
+	}								\
+	_r;								\
+})
+
+#define fifo_pop_back(fifo, i)						\
+({									\
+	bool _r = !fifo_empty((fifo));					\
+	if (_r) {							\
+		--(fifo)->back;						\
+		(fifo)->back &= (fifo)->mask;				\
+		(i) = (fifo)->data[(fifo)->back]			\
+	}								\
+	_r;								\
+})
+
+#define fifo_push(fifo, i)	fifo_push_back(fifo, (i))
+#define fifo_pop(fifo, i)	fifo_pop_front(fifo, (i))
+
+#define fifo_swap(l, r)							\
+do {									\
+	swap((l)->front, (r)->front);					\
+	swap((l)->back, (r)->back);					\
+	swap((l)->size, (r)->size);					\
+	swap((l)->mask, (r)->mask);					\
+	swap((l)->data, (r)->data);					\
+} while (0)
+
+#define fifo_move(dest, src)						\
+do {									\
+	typeof(*((dest)->data)) _t;					\
+	while (!fifo_full(dest) &&					\
+	       fifo_pop(src, _t))					\
+		fifo_push(dest, _t);					\
+} while (0)
+
+/*
+ * Simple array based allocator - preallocates a number of elements and you can
+ * never allocate more than that, also has no locking.
+ *
+ * Handy because if you know you only need a fixed number of elements you don't
+ * have to worry about memory allocation failure, and sometimes a mempool isn't
+ * what you want.
+ *
+ * We treat the free elements as entries in a singly linked list, and the
+ * freelist as a stack - allocating and freeing push and pop off the freelist.
+ */
+
+#define DECLARE_ARRAY_ALLOCATOR(type, name, size)			\
+	struct {							\
+		type	*freelist;					\
+		type	data[size];					\
+	} name
+
+#define array_alloc(array)						\
+({									\
+	typeof((array)->freelist) _ret = (array)->freelist;		\
+									\
+	if (_ret)							\
+		(array)->freelist = *((typeof((array)->freelist) *) _ret);\
+									\
+	_ret;								\
+})
+
+#define array_free(array, ptr)						\
+do {									\
+	typeof((array)->freelist) _ptr = ptr;				\
+									\
+	*((typeof((array)->freelist) *) _ptr) = (array)->freelist;	\
+	(array)->freelist = _ptr;					\
+} while (0)
+
+#define array_allocator_init(array)					\
+do {									\
+	typeof((array)->freelist) _i;					\
+									\
+	BUILD_BUG_ON(sizeof((array)->data[0]) < sizeof(void *));	\
+	(array)->freelist = NULL;					\
+									\
+	for (_i = (array)->data;					\
+	     _i < (array)->data + ARRAY_SIZE((array)->data);		\
+	     _i++)							\
+		array_free(array, _i);					\
+} while (0)
+
+#define array_freelist_empty(array)	((array)->freelist == NULL)
+
+#define ANYSINT_MAX(t)							\
+	((((t) 1 << (sizeof(t) * 8 - 2)) - (t) 1) * (t) 2 + (t) 1)
+
+int strtoint_h(const char *, int *);
+int strtouint_h(const char *, unsigned int *);
+int strtoll_h(const char *, long long *);
+int strtoull_h(const char *, unsigned long long *);
+
+static inline int strtol_h(const char *cp, long *res)
+{
+#if BITS_PER_LONG == 32
+	return strtoint_h(cp, (int *) res);
+#else
+	return strtoll_h(cp, (long long *) res);
+#endif
+}
+
+static inline int strtoul_h(const char *cp, long *res)
+{
+#if BITS_PER_LONG == 32
+	return strtouint_h(cp, (unsigned int *) res);
+#else
+	return strtoull_h(cp, (unsigned long long *) res);
+#endif
+}
+
+#define strtoi_h(cp, res)						\
+	(__builtin_types_compatible_p(typeof(*res), int)		\
+	? strtoint_h(cp, (void *) res)					\
+	: __builtin_types_compatible_p(typeof(*res), long)		\
+	? strtol_h(cp, (void *) res)					\
+	: __builtin_types_compatible_p(typeof(*res), long long)		\
+	? strtoll_h(cp, (void *) res)					\
+	: __builtin_types_compatible_p(typeof(*res), unsigned int)	\
+	? strtouint_h(cp, (void *) res)					\
+	: __builtin_types_compatible_p(typeof(*res), unsigned long)	\
+	? strtoul_h(cp, (void *) res)					\
+	: __builtin_types_compatible_p(typeof(*res), unsigned long long)\
+	? strtoull_h(cp, (void *) res) : -EINVAL)
+
+#define strtoul_safe(cp, var)						\
+({									\
+	unsigned long _v;						\
+	int _r = kstrtoul(cp, 10, &_v);					\
+	if (!_r)							\
+		var = _v;						\
+	_r;								\
+})
+
+#define strtoul_safe_clamp(cp, var, min, max)				\
+({									\
+	unsigned long _v;						\
+	int _r = kstrtoul(cp, 10, &_v);					\
+	if (!_r)							\
+		var = clamp_t(typeof(var), _v, min, max);		\
+	_r;								\
+})
+
+#define snprint(buf, size, var)						\
+	snprintf(buf, size,						\
+		__builtin_types_compatible_p(typeof(var), int)		\
+		     ? "%i\n" :						\
+		__builtin_types_compatible_p(typeof(var), unsigned)	\
+		     ? "%u\n" :						\
+		__builtin_types_compatible_p(typeof(var), long)		\
+		     ? "%li\n" :					\
+		__builtin_types_compatible_p(typeof(var), unsigned long)\
+		     ? "%lu\n" :					\
+		__builtin_types_compatible_p(typeof(var), int64_t)	\
+		     ? "%lli\n" :					\
+		__builtin_types_compatible_p(typeof(var), uint64_t)	\
+		     ? "%llu\n" :					\
+		__builtin_types_compatible_p(typeof(var), const char *)	\
+		     ? "%s\n" : "%i\n", var)
+
+ssize_t hprint(char *buf, int64_t v);
+
+bool is_zero(const char *p, size_t n);
+int parse_uuid(const char *s, char *uuid);
+
+ssize_t snprint_string_list(char *buf, size_t size, const char * const list[],
+			    size_t selected);
+
+ssize_t read_string_list(const char *buf, const char * const list[]);
+
+struct time_stats {
+	/*
+	 * all fields are in nanoseconds, averages are ewmas stored left shifted
+	 * by 8
+	 */
+	uint64_t	max_duration;
+	uint64_t	average_duration;
+	uint64_t	average_frequency;
+	uint64_t	last;
+};
+
+void time_stats_update(struct time_stats *stats, uint64_t time);
+
+#define NSEC_PER_ns			1L
+#define NSEC_PER_us			NSEC_PER_USEC
+#define NSEC_PER_ms			NSEC_PER_MSEC
+#define NSEC_PER_sec			NSEC_PER_SEC
+
+#define __print_time_stat(stats, name, stat, units)			\
+	sysfs_print(name ## _ ## stat ## _ ## units,			\
+		    div_u64((stats)->stat >> 8, NSEC_PER_ ## units))
+
+#define sysfs_print_time_stats(stats, name,				\
+			       frequency_units,				\
+			       duration_units)				\
+do {									\
+	__print_time_stat(stats, name,					\
+			  average_frequency,	frequency_units);	\
+	__print_time_stat(stats, name,					\
+			  average_duration,	duration_units);	\
+	__print_time_stat(stats, name,					\
+			  max_duration,		duration_units);	\
+									\
+	sysfs_print(name ## _last_ ## frequency_units, (stats)->last	\
+		    ? div_s64(local_clock() - (stats)->last,		\
+			      NSEC_PER_ ## frequency_units)		\
+		    : -1LL);						\
+} while (0)
+
+#define sysfs_time_stats_attribute(name,				\
+				   frequency_units,			\
+				   duration_units)			\
+read_attribute(name ## _average_frequency_ ## frequency_units);		\
+read_attribute(name ## _average_duration_ ## duration_units);		\
+read_attribute(name ## _max_duration_ ## duration_units);		\
+read_attribute(name ## _last_ ## frequency_units)
+
+#define sysfs_time_stats_attribute_list(name,				\
+					frequency_units,		\
+					duration_units)			\
+&sysfs_ ## name ## _average_frequency_ ## frequency_units,		\
+&sysfs_ ## name ## _average_duration_ ## duration_units,		\
+&sysfs_ ## name ## _max_duration_ ## duration_units,			\
+&sysfs_ ## name ## _last_ ## frequency_units,
+
+#define ewma_add(ewma, val, weight, factor)				\
+({									\
+	(ewma) *= (weight) - 1;						\
+	(ewma) += (val) << factor;					\
+	(ewma) /= (weight);						\
+	(ewma) >> factor;						\
+})
+
+struct ratelimit {
+	uint64_t		next;
+	unsigned		rate;
+};
+
+static inline void ratelimit_reset(struct ratelimit *d)
+{
+	d->next = local_clock();
+}
+
+unsigned next_delay(struct ratelimit *d, uint64_t done);
+
+#define __DIV_SAFE(n, d, zero)						\
+({									\
+	typeof(n) _n = (n);						\
+	typeof(d) _d = (d);						\
+	_d ? _n / _d : zero;						\
+})
+
+#define DIV_SAFE(n, d)	__DIV_SAFE(n, d, 0)
+
+#define container_of_or_null(ptr, type, member)				\
+({									\
+	typeof(ptr) _ptr = ptr;						\
+	_ptr ? container_of(_ptr, type, member) : NULL;			\
+})
+
+#define RB_INSERT(root, new, member, cmp)				\
+({									\
+	__label__ dup;							\
+	struct rb_node **n = &(root)->rb_node, *parent = NULL;		\
+	typeof(new) this;						\
+	int res, ret = -1;						\
+									\
+	while (*n) {							\
+		parent = *n;						\
+		this = container_of(*n, typeof(*(new)), member);	\
+		res = cmp(new, this);					\
+		if (!res)						\
+			goto dup;					\
+		n = res < 0						\
+			? &(*n)->rb_left				\
+			: &(*n)->rb_right;				\
+	}								\
+									\
+	rb_link_node(&(new)->member, parent, n);			\
+	rb_insert_color(&(new)->member, root);				\
+	ret = 0;							\
+dup:									\
+	ret;								\
+})
+
+#define RB_SEARCH(root, search, member, cmp)				\
+({									\
+	struct rb_node *n = (root)->rb_node;				\
+	typeof(&(search)) this, ret = NULL;				\
+	int res;							\
+									\
+	while (n) {							\
+		this = container_of(n, typeof(search), member);		\
+		res = cmp(&(search), this);				\
+		if (!res) {						\
+			ret = this;					\
+			break;						\
+		}							\
+		n = res < 0						\
+			? n->rb_left					\
+			: n->rb_right;					\
+	}								\
+	ret;								\
+})
+
+#define RB_GREATER(root, search, member, cmp)				\
+({									\
+	struct rb_node *n = (root)->rb_node;				\
+	typeof(&(search)) this, ret = NULL;				\
+	int res;							\
+									\
+	while (n) {							\
+		this = container_of(n, typeof(search), member);		\
+		res = cmp(&(search), this);				\
+		if (res < 0) {						\
+			ret = this;					\
+			n = n->rb_left;					\
+		} else							\
+			n = n->rb_right;				\
+	}								\
+	ret;								\
+})
+
+#define RB_FIRST(root, type, member)					\
+	container_of_or_null(rb_first(root), type, member)
+
+#define RB_LAST(root, type, member)					\
+	container_of_or_null(rb_last(root), type, member)
+
+#define RB_NEXT(ptr, member)						\
+	container_of_or_null(rb_next(&(ptr)->member), typeof(*ptr), member)
+
+#define RB_PREV(ptr, member)						\
+	container_of_or_null(rb_prev(&(ptr)->member), typeof(*ptr), member)
+
+/* Does linear interpolation between powers of two */
+static inline unsigned fract_exp_two(unsigned x, unsigned fract_bits)
+{
+	unsigned fract = x & ~(~0 << fract_bits);
+
+	x >>= fract_bits;
+	x   = 1 << x;
+	x  += (x * fract) >> fract_bits;
+
+	return x;
+}
+
+#define bio_end(bio)	((bio)->bi_sector + bio_sectors(bio))
+
+void bio_map(struct bio *bio, void *base);
+
+int bio_alloc_pages(struct bio *bio, gfp_t gfp);
+
+static inline sector_t bdev_sectors(struct block_device *bdev)
+{
+	return bdev->bd_inode->i_size >> 9;
+}
+
+#define closure_bio_submit(bio, cl, dev)				\
+do {									\
+	closure_get(cl);						\
+	bch_generic_make_request(bio, &(dev)->bio_split_hook);		\
+} while (0)
+
+uint64_t crc64_update(uint64_t, const void *, size_t);
+uint64_t crc64(const void *, size_t);
+
+#endif /* _BCACHE_UTIL_H */

drivers/md/bcache/writeback.c

@@ -0,0 +1,414 @@
+/*
+ * background writeback - scan btree for dirty data and write it to the backing
+ * device
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+
+static struct workqueue_struct *dirty_wq;
+
+static void read_dirty(struct closure *);
+
+struct dirty_io {
+	struct closure		cl;
+	struct cached_dev	*dc;
+	struct bio		bio;
+};
+
+/* Rate limiting */
+
+static void __update_writeback_rate(struct cached_dev *dc)
+{
+	struct cache_set *c = dc->disk.c;
+	uint64_t cache_sectors = c->nbuckets * c->sb.bucket_size;
+	uint64_t cache_dirty_target =
+		div_u64(cache_sectors * dc->writeback_percent, 100);
+
+	int64_t target = div64_u64(cache_dirty_target * bdev_sectors(dc->bdev),
+				   c->cached_dev_sectors);
+
+	/* PD controller */
+
+	int change = 0;
+	int64_t error;
+	int64_t dirty = atomic_long_read(&dc->disk.sectors_dirty);
+	int64_t derivative = dirty - dc->disk.sectors_dirty_last;
+
+	dc->disk.sectors_dirty_last = dirty;
+
+	derivative *= dc->writeback_rate_d_term;
+	derivative = clamp(derivative, -dirty, dirty);
+
+	derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
+			      dc->writeback_rate_d_smooth, 0);
+
+	/* Avoid divide by zero */
+	if (!target)
+		goto out;
+
+	error = div64_s64((dirty + derivative - target) << 8, target);
+
+	change = div_s64((dc->writeback_rate.rate * error) >> 8,
+			 dc->writeback_rate_p_term_inverse);
+
+	/* Don't increase writeback rate if the device isn't keeping up */
+	if (change > 0 &&
+	    time_after64(local_clock(),
+			 dc->writeback_rate.next + 10 * NSEC_PER_MSEC))
+		change = 0;
+
+	dc->writeback_rate.rate =
+		clamp_t(int64_t, dc->writeback_rate.rate + change,
+			1, NSEC_PER_MSEC);
+out:
+	dc->writeback_rate_derivative = derivative;
+	dc->writeback_rate_change = change;
+	dc->writeback_rate_target = target;
+
+	schedule_delayed_work(&dc->writeback_rate_update,
+			      dc->writeback_rate_update_seconds * HZ);
+}
+
+static void update_writeback_rate(struct work_struct *work)
+{
+	struct cached_dev *dc = container_of(to_delayed_work(work),
+					     struct cached_dev,
+					     writeback_rate_update);
+
+	down_read(&dc->writeback_lock);
+
+	if (atomic_read(&dc->has_dirty) &&
+	    dc->writeback_percent)
+		__update_writeback_rate(dc);
+
+	up_read(&dc->writeback_lock);
+}
+
+static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors)
+{
+	if (atomic_read(&dc->disk.detaching) ||
+	    !dc->writeback_percent)
+		return 0;
+
+	return next_delay(&dc->writeback_rate, sectors * 10000000ULL);
+}
+
+/* Background writeback */
+
+static bool dirty_pred(struct keybuf *buf, struct bkey *k)
+{
+	return KEY_DIRTY(k);
+}
+
+static void dirty_init(struct keybuf_key *w)
+{
+	struct dirty_io *io = w->private;
+	struct bio *bio = &io->bio;
+
+	bio_init(bio);
+	if (!io->dc->writeback_percent)
+		bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
+
+	bio->bi_size		= KEY_SIZE(&w->key) << 9;
+	bio->bi_max_vecs	= DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS);
+	bio->bi_private		= w;
+	bio->bi_io_vec		= bio->bi_inline_vecs;
+	bio_map(bio, NULL);
+}
+
+static void refill_dirty(struct closure *cl)
+{
+	struct cached_dev *dc = container_of(cl, struct cached_dev,
+					     writeback.cl);
+	struct keybuf *buf = &dc->writeback_keys;
+	bool searched_from_start = false;
+	struct bkey end = MAX_KEY;
+	SET_KEY_INODE(&end, dc->disk.id);
+
+	if (!atomic_read(&dc->disk.detaching) &&
+	    !dc->writeback_running)
+		closure_return(cl);
+
+	down_write(&dc->writeback_lock);
+
+	if (!atomic_read(&dc->has_dirty)) {
+		SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
+		bch_write_bdev_super(dc, NULL);
+
+		up_write(&dc->writeback_lock);
+		closure_return(cl);
+	}
+
+	if (bkey_cmp(&buf->last_scanned, &end) >= 0) {
+		buf->last_scanned = KEY(dc->disk.id, 0, 0);
+		searched_from_start = true;
+	}
+
+	bch_refill_keybuf(dc->disk.c, buf, &end);
+
+	if (bkey_cmp(&buf->last_scanned, &end) >= 0 && searched_from_start) {
+		/* Searched the entire btree  - delay awhile */
+
+		if (RB_EMPTY_ROOT(&buf->keys)) {
+			atomic_set(&dc->has_dirty, 0);
+			cached_dev_put(dc);
+		}
+
+		if (!atomic_read(&dc->disk.detaching))
+			closure_delay(&dc->writeback, dc->writeback_delay * HZ);
+	}
+
+	up_write(&dc->writeback_lock);
+
+	ratelimit_reset(&dc->writeback_rate);
+
+	/* Punt to workqueue only so we don't recurse and blow the stack */
+	continue_at(cl, read_dirty, dirty_wq);
+}
+
+void bch_writeback_queue(struct cached_dev *dc)
+{
+	if (closure_trylock(&dc->writeback.cl, &dc->disk.cl)) {
+		if (!atomic_read(&dc->disk.detaching))
+			closure_delay(&dc->writeback, dc->writeback_delay * HZ);
+
+		continue_at(&dc->writeback.cl, refill_dirty, dirty_wq);
+	}
+}
+
+void bch_writeback_add(struct cached_dev *dc, unsigned sectors)
+{
+	atomic_long_add(sectors, &dc->disk.sectors_dirty);
+
+	if (!atomic_read(&dc->has_dirty) &&
+	    !atomic_xchg(&dc->has_dirty, 1)) {
+		atomic_inc(&dc->count);
+
+		if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
+			SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
+			/* XXX: should do this synchronously */
+			bch_write_bdev_super(dc, NULL);
+		}
+
+		bch_writeback_queue(dc);
+
+		if (dc->writeback_percent)
+			schedule_delayed_work(&dc->writeback_rate_update,
+				      dc->writeback_rate_update_seconds * HZ);
+	}
+}
+
+/* Background writeback - IO loop */
+
+static void dirty_io_destructor(struct closure *cl)
+{
+	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
+	kfree(io);
+}
+
+static void write_dirty_finish(struct closure *cl)
+{
+	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
+	struct keybuf_key *w = io->bio.bi_private;
+	struct cached_dev *dc = io->dc;
+	struct bio_vec *bv = bio_iovec_idx(&io->bio, io->bio.bi_vcnt);
+
+	while (bv-- != io->bio.bi_io_vec)
+		__free_page(bv->bv_page);
+
+	/* This is kind of a dumb way of signalling errors. */
+	if (KEY_DIRTY(&w->key)) {
+		unsigned i;
+		struct btree_op op;
+		bch_btree_op_init_stack(&op);
+
+		op.type = BTREE_REPLACE;
+		bkey_copy(&op.replace, &w->key);
+
+		SET_KEY_DIRTY(&w->key, false);
+		bch_keylist_add(&op.keys, &w->key);
+
+		for (i = 0; i < KEY_PTRS(&w->key); i++)
+			atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin);
+
+		pr_debug("clearing %s", pkey(&w->key));
+		bch_btree_insert(&op, dc->disk.c);
+		closure_sync(&op.cl);
+
+		atomic_long_inc(op.insert_collision
+				? &dc->disk.c->writeback_keys_failed
+				: &dc->disk.c->writeback_keys_done);
+	}
+
+	bch_keybuf_del(&dc->writeback_keys, w);
+	atomic_dec_bug(&dc->in_flight);
+
+	closure_wake_up(&dc->writeback_wait);
+
+	closure_return_with_destructor(cl, dirty_io_destructor);
+}
+
+static void dirty_endio(struct bio *bio, int error)
+{
+	struct keybuf_key *w = bio->bi_private;
+	struct dirty_io *io = w->private;
+
+	if (error)
+		SET_KEY_DIRTY(&w->key, false);
+
+	closure_put(&io->cl);
+}
+
+static void write_dirty(struct closure *cl)
+{
+	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
+	struct keybuf_key *w = io->bio.bi_private;
+
+	dirty_init(w);
+	io->bio.bi_rw		= WRITE;
+	io->bio.bi_sector	= KEY_START(&w->key);
+	io->bio.bi_bdev		= io->dc->bdev;
+	io->bio.bi_end_io	= dirty_endio;
+
+	trace_bcache_write_dirty(&io->bio);
+	closure_bio_submit(&io->bio, cl, &io->dc->disk);
+
+	continue_at(cl, write_dirty_finish, dirty_wq);
+}
+
+static void read_dirty_endio(struct bio *bio, int error)
+{
+	struct keybuf_key *w = bio->bi_private;
+	struct dirty_io *io = w->private;
+
+	bch_count_io_errors(PTR_CACHE(io->dc->disk.c, &w->key, 0),
+			    error, "reading dirty data from cache");
+
+	dirty_endio(bio, error);
+}
+
+static void read_dirty_submit(struct closure *cl)
+{
+	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
+
+	trace_bcache_read_dirty(&io->bio);
+	closure_bio_submit(&io->bio, cl, &io->dc->disk);
+
+	continue_at(cl, write_dirty, dirty_wq);
+}
+
+static void read_dirty(struct closure *cl)
+{
+	struct cached_dev *dc = container_of(cl, struct cached_dev,
+					     writeback.cl);
+	unsigned delay = writeback_delay(dc, 0);
+	struct keybuf_key *w;
+	struct dirty_io *io;
+
+	/*
+	 * XXX: if we error, background writeback just spins. Should use some
+	 * mempools.
+	 */
+
+	while (1) {
+		w = bch_keybuf_next(&dc->writeback_keys);
+		if (!w)
+			break;
+
+		BUG_ON(ptr_stale(dc->disk.c, &w->key, 0));
+
+		if (delay > 0 &&
+		    (KEY_START(&w->key) != dc->last_read ||
+		     jiffies_to_msecs(delay) > 50)) {
+			w->private = NULL;
+
+			closure_delay(&dc->writeback, delay);
+			continue_at(cl, read_dirty, dirty_wq);
+		}
+
+		dc->last_read	= KEY_OFFSET(&w->key);
+
+		io = kzalloc(sizeof(struct dirty_io) + sizeof(struct bio_vec)
+			     * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
+			     GFP_KERNEL);
+		if (!io)
+			goto err;
+
+		w->private	= io;
+		io->dc		= dc;
+
+		dirty_init(w);
+		io->bio.bi_sector	= PTR_OFFSET(&w->key, 0);
+		io->bio.bi_bdev		= PTR_CACHE(dc->disk.c,
+						    &w->key, 0)->bdev;
+		io->bio.bi_rw		= READ;
+		io->bio.bi_end_io	= read_dirty_endio;
+
+		if (bio_alloc_pages(&io->bio, GFP_KERNEL))
+			goto err_free;
+
+		pr_debug("%s", pkey(&w->key));
+
+		closure_call(&io->cl, read_dirty_submit, NULL, &dc->disk.cl);
+
+		delay = writeback_delay(dc, KEY_SIZE(&w->key));
+
+		atomic_inc(&dc->in_flight);
+
+		if (!closure_wait_event(&dc->writeback_wait, cl,
+					atomic_read(&dc->in_flight) < 64))
+			continue_at(cl, read_dirty, dirty_wq);
+	}
+
+	if (0) {
+err_free:
+		kfree(w->private);
+err:
+		bch_keybuf_del(&dc->writeback_keys, w);
+	}
+
+	refill_dirty(cl);
+}
+
+void bch_writeback_init_cached_dev(struct cached_dev *dc)
+{
+	closure_init_unlocked(&dc->writeback);
+	init_rwsem(&dc->writeback_lock);
+
+	bch_keybuf_init(&dc->writeback_keys, dirty_pred);
+
+	dc->writeback_metadata		= true;
+	dc->writeback_running		= true;
+	dc->writeback_percent		= 10;
+	dc->writeback_delay		= 30;
+	dc->writeback_rate.rate		= 1024;
+
+	dc->writeback_rate_update_seconds = 30;
+	dc->writeback_rate_d_term	= 16;
+	dc->writeback_rate_p_term_inverse = 64;
+	dc->writeback_rate_d_smooth	= 8;
+
+	INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
+	schedule_delayed_work(&dc->writeback_rate_update,
+			      dc->writeback_rate_update_seconds * HZ);
+}
+
+void bch_writeback_exit(void)
+{
+	if (dirty_wq)
+		destroy_workqueue(dirty_wq);
+}
+
+int __init bch_writeback_init(void)
+{
+	dirty_wq = create_singlethread_workqueue("bcache_writeback");
+	if (!dirty_wq)
+		return -ENOMEM;
+
+	return 0;
+}

include/linux/cgroup_subsys.h

@@ -78,3 +78,9 @@ SUBSYS(hugetlb)
 #endif
 
 /* */
+
+#ifdef CONFIG_CGROUP_BCACHE
+SUBSYS(bcache)
+#endif
+
+/* */

include/linux/sched.h

@@ -1576,6 +1576,10 @@ struct task_struct {
 #ifdef CONFIG_UPROBES
 	struct uprobe_task *utask;
 #endif
+#if defined(CONFIG_BCACHE) || defined(CONFIG_BCACHE_MODULE)
+	unsigned int	sequential_io;
+	unsigned int	sequential_io_avg;
+#endif
 };
 
 /* Future-safe accessor for struct task_struct's cpus_allowed. */

include/trace/events/bcache.h

@@ -0,0 +1,271 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM bcache
+
+#if !defined(_TRACE_BCACHE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_BCACHE_H
+
+#include <linux/tracepoint.h>
+
+struct search;
+
+DECLARE_EVENT_CLASS(bcache_request,
+
+	TP_PROTO(struct search *s, struct bio *bio),
+
+	TP_ARGS(s, bio),
+
+	TP_STRUCT__entry(
+		__field(dev_t,		dev			)
+		__field(unsigned int,	orig_major		)
+		__field(unsigned int,	orig_minor		)
+		__field(sector_t,	sector			)
+		__field(dev_t,		orig_sector		)
+		__field(unsigned int,	nr_sector		)
+		__array(char,		rwbs,	6		)
+		__array(char,		comm,	TASK_COMM_LEN	)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= bio->bi_bdev->bd_dev;
+		__entry->orig_major	= s->d->disk->major;
+		__entry->orig_minor	= s->d->disk->first_minor;
+		__entry->sector		= bio->bi_sector;
+		__entry->orig_sector	= bio->bi_sector - 16;
+		__entry->nr_sector	= bio->bi_size >> 9;
+		blk_fill_rwbs(__entry->rwbs, bio->bi_rw, bio->bi_size);
+		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+	),
+
+	TP_printk("%d,%d %s %llu + %u [%s] (from %d,%d @ %llu)",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->rwbs,
+		  (unsigned long long)__entry->sector,
+		  __entry->nr_sector, __entry->comm,
+		  __entry->orig_major, __entry->orig_minor,
+		  (unsigned long long)__entry->orig_sector)
+);
+
+DEFINE_EVENT(bcache_request, bcache_request_start,
+
+	TP_PROTO(struct search *s, struct bio *bio),
+
+	TP_ARGS(s, bio)
+);
+
+DEFINE_EVENT(bcache_request, bcache_request_end,
+
+	TP_PROTO(struct search *s, struct bio *bio),
+
+	TP_ARGS(s, bio)
+);
+
+DECLARE_EVENT_CLASS(bcache_bio,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio),
+
+	TP_STRUCT__entry(
+		__field(dev_t,		dev			)
+		__field(sector_t,	sector			)
+		__field(unsigned int,	nr_sector		)
+		__array(char,		rwbs,	6		)
+		__array(char,		comm,	TASK_COMM_LEN	)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= bio->bi_bdev->bd_dev;
+		__entry->sector		= bio->bi_sector;
+		__entry->nr_sector	= bio->bi_size >> 9;
+		blk_fill_rwbs(__entry->rwbs, bio->bi_rw, bio->bi_size);
+		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+	),
+
+	TP_printk("%d,%d  %s %llu + %u [%s]",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->rwbs,
+		  (unsigned long long)__entry->sector,
+		  __entry->nr_sector, __entry->comm)
+);
+
+
+DEFINE_EVENT(bcache_bio, bcache_passthrough,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_cache_hit,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_cache_miss,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_read_retry,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_writethrough,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_writeback,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_write_skip,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_btree_read,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_btree_write,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_write_dirty,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_read_dirty,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_write_moving,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_read_moving,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DEFINE_EVENT(bcache_bio, bcache_journal_write,
+
+	TP_PROTO(struct bio *bio),
+
+	TP_ARGS(bio)
+);
+
+DECLARE_EVENT_CLASS(bcache_cache_bio,
+
+	TP_PROTO(struct bio *bio,
+		 sector_t orig_sector,
+		 struct block_device* orig_bdev),
+
+	TP_ARGS(bio, orig_sector, orig_bdev),
+
+	TP_STRUCT__entry(
+		__field(dev_t,		dev			)
+		__field(dev_t,		orig_dev		)
+		__field(sector_t,	sector			)
+		__field(sector_t,	orig_sector		)
+		__field(unsigned int,	nr_sector		)
+		__array(char,		rwbs,	6		)
+		__array(char,		comm,	TASK_COMM_LEN	)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= bio->bi_bdev->bd_dev;
+		__entry->orig_dev	= orig_bdev->bd_dev;
+		__entry->sector		= bio->bi_sector;
+		__entry->orig_sector	= orig_sector;
+		__entry->nr_sector	= bio->bi_size >> 9;
+		blk_fill_rwbs(__entry->rwbs, bio->bi_rw, bio->bi_size);
+		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+	),
+
+	TP_printk("%d,%d  %s %llu + %u [%s] (from %d,%d %llu)",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->rwbs,
+		  (unsigned long long)__entry->sector,
+		  __entry->nr_sector, __entry->comm,
+		  MAJOR(__entry->orig_dev), MINOR(__entry->orig_dev),
+		  (unsigned long long)__entry->orig_sector)
+);
+
+DEFINE_EVENT(bcache_cache_bio, bcache_cache_insert,
+
+	TP_PROTO(struct bio *bio,
+		 sector_t orig_sector,
+		 struct block_device *orig_bdev),
+
+	TP_ARGS(bio, orig_sector, orig_bdev)
+);
+
+DECLARE_EVENT_CLASS(bcache_gc,
+
+	TP_PROTO(uint8_t *uuid),
+
+	TP_ARGS(uuid),
+
+	TP_STRUCT__entry(
+		__field(uint8_t *,	uuid)
+	),
+
+	TP_fast_assign(
+		__entry->uuid		= uuid;
+	),
+
+	TP_printk("%pU", __entry->uuid)
+);
+
+
+DEFINE_EVENT(bcache_gc, bcache_gc_start,
+
+	     TP_PROTO(uint8_t *uuid),
+
+	     TP_ARGS(uuid)
+);
+
+DEFINE_EVENT(bcache_gc, bcache_gc_end,
+
+	     TP_PROTO(uint8_t *uuid),
+
+	     TP_ARGS(uuid)
+);
+
+#endif /* _TRACE_BCACHE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>

kernel/fork.c

@@ -1303,6 +1303,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	p->memcg_batch.do_batch = 0;
 	p->memcg_batch.memcg = NULL;
 #endif
+#ifdef CONFIG_BCACHE
+	p->sequential_io	= 0;
+	p->sequential_io_avg	= 0;
+#endif
 
 	/* Perform scheduler related setup. Assign this task to a CPU. */
 	sched_fork(p);