226 Commits

Author SHA1 Message Date
Kent Overstreet
8b16413cda bcachefs: bch_sb.recovery_passes_required
Add two new superblock fields. Since the main section of the superblock
is now fully, we have to add a new variable length section for them -
bch_sb_field_ext.

 - recovery_passes_requried: recovery passes that must be run on the
   next mount
 - errors_silent: errors that will be silently fixed

These are to improve upgrading and dwongrading: these fields won't be
cleared until after recovery successfully completes, so there won't be
any issues with crashing partway through an upgrade or a downgrade.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-01 11:47:07 -05:00
Kent Overstreet
bbc3a46065 bcachefs: Fix zstd compress workspace size
zstd apparently lies about the size of the compression workspace it
requires; if we double it compression succeeds.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-28 17:18:24 -05:00
Kent Overstreet
8a443d3ea1 bcachefs: Proper refcounting for journal_keys
The btree iterator code overlays keys from the journal until journal
replay is finished; since we're now starting copygc/rebalance etc.
before replay is finished, this is multithreaded access and thus needs
refcounting.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-24 02:43:12 -05:00
Gustavo A. R. Silva
274c2f8fd2 bcachefs: Fix multiple -Warray-bounds warnings
Transform zero-length array `entries` into a proper flexible-array
member in `struct journal_seq_blacklist_table`; and fix the following
-Warray-bounds warnings:

fs/bcachefs/journal_seq_blacklist.c:148:26: warning: array subscript idx is outside array bounds of 'struct journal_seq_blacklist_table_entry[0]' [-Warray-bounds=]
fs/bcachefs/journal_seq_blacklist.c:150:30: warning: array subscript idx is outside array bounds of 'struct journal_seq_blacklist_table_entry[0]' [-Warray-bounds=]
fs/bcachefs/journal_seq_blacklist.c:154:27: warning: array subscript idx is outside array bounds of 'struct journal_seq_blacklist_table_entry[0]' [-Warray-bounds=]
fs/bcachefs/journal_seq_blacklist.c:176:27: warning: array subscript i is outside array bounds of 'struct journal_seq_blacklist_table_entry[0]' [-Warray-bounds=]
fs/bcachefs/journal_seq_blacklist.c:177:27: warning: array subscript i is outside array bounds of 'struct journal_seq_blacklist_table_entry[0]' [-Warray-bounds=]
fs/bcachefs/journal_seq_blacklist.c:297:34: warning: array subscript i is outside array bounds of 'struct journal_seq_blacklist_table_entry[0]' [-Warray-bounds=]
fs/bcachefs/journal_seq_blacklist.c:298:34: warning: array subscript i is outside array bounds of 'struct journal_seq_blacklist_table_entry[0]' [-Warray-bounds=]
fs/bcachefs/journal_seq_blacklist.c:300:31: warning: array subscript i is outside array bounds of 'struct journal_seq_blacklist_table_entry[0]' [-Warray-bounds=]

This results in no differences in binary output.

This helps with the ongoing efforts to globally enable -Warray-bounds.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-13 21:42:22 -05:00
Kent Overstreet
f5d26fa31e bcachefs: bch_sb_field_errors
Add a new superblock section to keep counts of errors seen since
filesystem creation: we'll be addingcounters for every distinct fsck
error.

The new superblock section has entries of the for [ id, count,
time_of_last_error ]; this is intended to let us see what errors are
occuring - and getting fixed - via show-super output.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-01 21:11:08 -04:00
Kent Overstreet
94119eeb02 bcachefs: Add IO error counts to bch_member
We now track IO errors per device since filesystem creation.

IO error counts can be viewed in sysfs, or with the 'bcachefs
show-super' command.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-01 21:11:08 -04:00
Kent Overstreet
fb3f57bb11 bcachefs: rebalance_work
This adds a new btree, rebalance_work, to eliminate scanning required
for finding extents that need work done on them in the background - i.e.
for the background_target and background_compression options.

rebalance_work is a bitset btree, where a KEY_TYPE_set corresponds to an
extent in the extents or reflink btree at the same pos.

A new extent field is added, bch_extent_rebalance, which indicates that
this extent has work that needs to be done in the background - and which
options to use. This allows per-inode options to be propagated to
indirect extents - at least in some circumstances. In this patch,
changing IO options on a file will not propagate the new options to
indirect extents pointed to by that file.

Updating (setting/clearing) the rebalance_work btree is done by the
extent trigger, which looks at the bch_extent_rebalance field.

Scanning is still requrired after changing IO path options - either just
for a given inode, or for the whole filesystem. We indicate that
scanning is required by adding a KEY_TYPE_cookie key to the
rebalance_work btree: the cookie counter is so that we can detect that
scanning is still required when an option has been flipped mid-way
through an existing scan.

Future possible work:
 - Propagate options to indirect extents when being changed
 - Add other IO path options - nr_replicas, ec, to rebalance_work so
   they can be applied in the background when they change
 - Add a counter, for bcachefs fs usage output, showing the pending
   amount of rebalance work: we'll probably want to do this after the
   disk space accounting rewrite (moving it to a new btree)

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-01 21:11:05 -04:00
Kent Overstreet
96a363a7e6 bcachefs: move: move_stats refactoring
data_progress_list is gone - it was redundant with moving_context_list

The upcoming rebalance rewrite is going to have it using two different
move_stats objects with the same moving_context, depending on whether
it's scanning or using the rebalance_work btree - this patch plumbs
stats around a bit differently so that will work.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-31 12:18:38 -04:00
Kent Overstreet
37707bb183 bcachefs: Split out disk_groups_types.h
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-31 12:18:37 -04:00
Kent Overstreet
b0b5bbf99f bcachefs: Don't run bch2_delete_dead_snapshots() unnecessarily
Be a bit more careful about when bch2_delete_dead_snapshots needs to
run: it only needs to run synchronously if we're running fsck, and it
only needs to run at all if we have snapshot nodes to delete or if fsck
has noticed that it needs to run.

Also:
  Rename BCH_FS_HAVE_DELETED_SNAPSHOTS -> BCH_FS_NEED_DELETE_DEAD_SNAPSHOTS

  Kill bch2_delete_dead_snapshots_hook(), move functionality to
  bch2_mark_snapshot()

  Factor out bch2_check_snapshot_needs_deletion(), to explicitly check
  if we need to be running snapshot deletion.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-31 12:18:37 -04:00
Kent Overstreet
37fad9497f bcachefs: snapshot_create_lock
Add a new lock for snapshot creation - this addresses a few races with
logged operations and snapshot deletion.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:16 -04:00
Kent Overstreet
d2a990d1b1 bcachefs: bch_err_msg(), bch_err_fn() now filters out transaction restart errors
These errors aren't actual errors, and should never be printed - do this
in the common helpers.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:15 -04:00
Kent Overstreet
6bd68ec266 bcachefs: Heap allocate btree_trans
We're using more stack than we'd like in a number of functions, and
btree_trans is the biggest object that we stack allocate.

But we have to do a heap allocatation to initialize it anyways, so
there's no real downside to heap allocating the entire thing.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:13 -04:00
Kent Overstreet
96dea3d599 bcachefs: Fix W=12 build errors
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:13 -04:00
Kent Overstreet
aaad530ac6 bcachefs: BTREE_ID_logged_ops
Add a new btree for long running logged operations - i.e. for logging
operations that we can't do within a single btree transaction, so that
they can be resumed if we crash.

Keys in the logged operations btree will represent operations in
progress, with the state of the operation stored in the value.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:12 -04:00
Kent Overstreet
e691b391f0 bcachefs: Add logging to bch2_inode_peek() & related
Add error messages when we fail to lookup an inode, and also add a few
missing bch2_err_class() calls.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:09 -04:00
Kent Overstreet
0ed4ca146e bcachefs: Ensure topology repair runs
This fixes should_restart_for_topology_repair() - previously it was
returning false if the btree io path had already seleceted topology
repair to run, even if it hadn't run yet.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:09 -04:00
Kent Overstreet
ad52bac251 bcachefs: Log a message when running an explicit recovery pass
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:09 -04:00
Kent Overstreet
dde8cb1164 bcachefs: bcachefs_metadata_version_deleted_inodes
Add a new bitset btree for inodes pending deletion; this means we no
longer have to scan the full inodes btree after an unclean shutdown.

Specifically, this adds:
 - a trigger to update the deleted_inodes btree based on changes to the
   inodes btree
 - a new recovery pass
 - and check_inodes is now only a fsck pass.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:09 -04:00
Kent Overstreet
1074a21c88 bcachefs: recovery_types.h
Move some code out of bcachefs.h, which is too much of an everything
header.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:09 -04:00
Kent Overstreet
922bc5a037 bcachefs: Make topology repair a normal recovery pass
This adds bch2_run_explicit_recovery_pass(), for rewinding recovery and
explicitly running a specific recovery pass - this is a more general
replacement for how we were running topology repair before.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:08 -04:00
Kent Overstreet
ae2e13d780 bcachefs: bch2_run_explicit_recovery_pass()
This introduces bch2_run_explicit_recovery_pass() and uses it for when
fsck detects that we need to re-run dead snaphots cleanup, and makes
dead snapshot cleanup more like a normal recovery pass.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:08 -04:00
Kent Overstreet
813e0cecd1 bcachefs: Upgrade path fixes
Some minor fixes to not print errors that are actually due to a verson
upgrade.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:07 -04:00
Kent Overstreet
8479938d7a bcachefs: Convert snapshot table to RCU array
This switches the generic radix tree for the in-memory table of snapshot
nodes to a simple rcu array. This means we have to add new locking to
deal with reallocations, but is faster than traversing the radix tree.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:07 -04:00
Kent Overstreet
065bd3356c bcachefs: Version table now lists required recovery passes
Now that we've got forward compatibility sorted out, we should be doing
more frequent version upgrades in the future.

To avoid having to run a full fsck for every version upgrade, this
improves the BCH_METADATA_VERSIONS() table to explicitly specify a
bitmask of recovery passes to run when upgrading to or past a given
version.

This means we can also delete PASS_UPGRADE().

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:06 -04:00
Kent Overstreet
ba8eeae8ee bcachefs: bcachefs_metadata_version_major_minor
This introduces major/minor versioning to the superblock version number.
Major version number changes indicate incompatible releases; we can move
forward to a new major version number, but not backwards. Minor version
numbers indicate compatible changes - these add features, but can still
be mounted and used by old versions.

With the recent patches that make it possible to roll out new btrees and
key types without breaking compatibility, we should be able to roll out
most new features without incompatible changes.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:06 -04:00
Kent Overstreet
067d228bb0 bcachefs: Enumerate recovery passes
Recovery and fsck have many different passes/jobs to do, which always
run in the same order - but not all of them run all the time. Some are
for fsck, some for unclean shutdown, some for version upgrades.

This adds some new structure: a defined list of recovery passes that we
can run in a loop, as well as consolidating the log messages.

The main benefit is consolidating the "should run this recovery pass"
logic, as well as cleaning up the "this recovery pass has finished"
state; instead of having a bunch of ad-hoc state bits in c->flags, we've
now got c->curr_recovery_pass.

By consolidating the "should run this recovery pass" logic, in the
future on disk format upgrades will be able to say "upgrading to this
version requires x passes to run", instead of forcing all of fsck to
run.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:06 -04:00
Kent Overstreet
78328fec70 bcachefs: Stash journal replay params in bch_fs
For the upcoming enumeration of recovery passes, we need all recovery
passes to be called the same way - including journal replay.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:06 -04:00
Kent Overstreet
3045bb958a bcachefs: version_upgrade is now an enum
The version_upgrade parameter is now an enum, not a bool, and it's
persistent in the superblock:
 - compatible (default):	upgrade to the latest compatible version
 - incompatible:		upgrade to latest incompatible version
 - none

Currently all upgrades are incompatible upgrades, but the next release
will introduce major:minor versions.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:06 -04:00
Kent Overstreet
24964e1c5c bcachefs: BCH_SB_VERSION_UPGRADE_COMPLETE()
Version upgrades are not atomic operations: when we do a version upgrade
we need to update the superblock before we start using new features, and
then when the upgrade completes we need to update the superblock again.
This adds a new superblock field so we can detect and handle incomplete
version upgrades.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:06 -04:00
Kent Overstreet
faa6cb6c13 bcachefs: Allow for unknown btree IDs
We need to allow filesystems with metadata from newer versions to be
mountable and usable by older versions.

This patch enables us to roll out new btrees without a new major version
number; we can now handle btree roots for unknown btree types.

The unknown btree roots will be retained, and fsck (including
backpointers) will check them, the same as other btree types.

We add a dynamic array for the extra, unknown btree roots, in addition
to the fixed size btree root array, and add new helpers for looking up
btree roots.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:05 -04:00
Kent Overstreet
1bb3c2a974 bcachefs: New error message helpers
Add two new helpers for printing error messages with __func__ and
bch2_err_str():
 - bch_err_fn
 - bch_err_msg

Also kill the old error strings in the recovery path, which were causing
us to incorrectly report memory allocation failures - they're not needed
anymore.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:04 -04:00
Kent Overstreet
a5b696ee6e bcachefs: seqmutex; fix a lockdep splat
We can't be holding btree_trans_lock while copying to user space, which
might incur a page fault. To fix this, convert it to a seqmutex so we
can unlock/relock.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:04 -04:00
Kent Overstreet
fc0ee376bb bcachefs: Don't reuse reflink btree keyspace
We've been seeing difficult to debug "missing indirect extent" bugs,
that fsck doesn't seem to find.

One possibility is that there was a missing indirect extent, but then a
new indirect extent was created at the location of the previous indirect
extent.

This patch eliminates that possibility by always creating new indirect
extents right after the last one, at the end of the reflink btree.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:02 -04:00
Kent Overstreet
1c59b483a3 bcachefs: BTREE_ID_snapshot_tree
This adds a new btree which gets us a persistent per-snapshot-tree
identifier.

 - BTREE_ID_snapshot_trees
 - KEY_TYPE_snapshot_tree
 - bch_snapshot now has a field that points to a snapshot_tree

This is going to be used to designate one snapshot ID/subvolume out of a
given tree of snapshots as the "main" subvolume, so that we can do quota
accounting in that subvolume and not the rest.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:10:01 -04:00
Kent Overstreet
4f77dcde28 bcachefs: move snapshot_t to subvolume_types.h
this doesn't need to be in bcachefs.h

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:58 -04:00
Kent Overstreet
0fb11e0801 bcachefs: Improved copygc wait debugging
This just adds a line for how long copygc has been waiting to sysfs
copygc_wait, helpful for debugging why copygc isn't running.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:58 -04:00
Brian Foster
8bff9875a6 bcachefs: use dedicated workqueue for tasks holding write refs
A workqueue resource deadlock has been observed when running fsck
on a filesystem with a full/stuck journal. fsck is not currently
able to repair the fs due to fairly rapid emergency shutdown, but
rather than exit gracefully the fsck process hangs during the
shutdown sequence. Fortunately this is easily recoverable from
userspace, but the root cause involves code shared between the
kernel and userspace and so should be addressed.

The deadlock scenario involves the main task in the bch2_fs_stop()
-> bch2_fs_read_only() path waiting on write references to drain
with the fs state lock held. A bch2_read_only_work() workqueue task
is scheduled on the system_long_wq, blocked on the state lock.
Finally, various other write ref holding workqueue tasks are
scheduled to run on the same workqueue and must complete in order to
release references that the initial task is waiting on.

To avoid this problem, we can split the dependent workqueue tasks
across different workqueues. It's a bit of a waste to create a
dedicated wq for the read-only worker, but there are several tasks
throughout the fs that follow the pattern of acquiring a write
reference and then scheduling to the system wq. Use a local wq
for such tasks to break the subtle dependency between these and the
read-only worker.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:58 -04:00
Kent Overstreet
9edbcc72f6 bcachefs: Fix bch2_evict_subvolume_inodes()
This fixes a bug in bch2_evict_subvolume_inodes(): d_mark_dontcache()
doesn't handle the case where i_count is already 0, we need to grab and
put the inode in order for it to be dropped.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:57 -04:00
Kent Overstreet
b40901b0f7 bcachefs: New erasure coding shutdown path
This implements a new shutdown path for erasure coding, which is needed
for the upcoming BCH_WRITE_WAIT_FOR_EC write path.

The process is:
 - Cancel new stripes being built up
 - Close out/cancel open buckets on write points or the partial list
   that are for stripes
 - Shutdown rebalance/copygc
 - Then wait for in flight new stripes to finish

With BCH_WRITE_WAIT_FOR_EC, move ops will be waiting on stripes to fill
up before they complete; the new ec shutdown path is needed for shutting
down copygc/rebalance without deadlocking.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:57 -04:00
Kent Overstreet
b9fa375bab bcachefs: bch2_fs_moving_ctxts_to_text()
This also adds bch2_write_op_to_text(): now we can see outstand moves,
useful for debugging shutdown with the upcoming BCH_WRITE_WAIT_FOR_EC
and likely for other things in the future.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:57 -04:00
Kent Overstreet
45dd05b3ec bcachefs: BKEY_PADDED_ONSTACK()
Rust bindgen doesn't do anonymous structs very nicely: BKEY_PADDED()
only needs the anonymous struct when it's used on the stack, to
guarantee layout, not when it's embedded in another struct.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:55 -04:00
Kent Overstreet
39a1ea129a bcachefs: Single open_bucket_partial list
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:54 -04:00
Kent Overstreet
4b1e669995 bcachefs: Erasure coding: Track open stripes
This adds a new hash table for stripes being created or updated, instead
of hackily relying on the stripes heap.

This lets us reserve the slot for the new stripe up front, at the same
time as we would pick an existing stripe - if we were updating an
existing stripe - making the overall code more consistent.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:54 -04:00
Kent Overstreet
627a231239 bcachefs: Switch ec_stripes_heap_lock to a mutex
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:53 -04:00
Kent Overstreet
80c3308578 bcachefs: Fragmentation LRU
Now that we have much more efficient updates to the LRU btree, this
patch adds a new LRU that indexes buckets by fragmentation.

This means copygc no longer has to scan every bucket to find buckets
that need to be evacuated.

Changes:
 - A new field in bch_alloc_v4, fragmentation_lru - this corresponds to
   the bucket's position in the fragmentation LRU. We add a new field
   for this instead of calculating it as needed because we may make the
   fragmentation LRU optional; this field indicates whether a bucket is
   on the fragmentation LRU.

   Also, zoned devices will introduce variable bucket sizes; explicitly
   recording the LRU position will be safer for them.

 - A new copygc path for using the fragmentation LRU instead of
   scanning every bucket and building up an in-memory heap.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:53 -04:00
Kent Overstreet
a1f26d700a bcachefs: Handle btree node rewrites before going RW
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:52 -04:00
Kent Overstreet
350175bf9b bcachefs: Improved nocow locking
This improves the nocow lock table so that hash table entries have
multiple locks, and locks specify which bucket they're for - i.e. we can
now resolve hash collisions.

This is important because the allocator has to skip buckets that are
locked in the nocow lock table, and previously hash collisions would
cause it to spuriously skip unlocked buckets.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:52 -04:00
Kent Overstreet
5250b74d55 bcachefs: bucket_gens btree
To improve mount times, add a btree for just bucket gens, 256 of them
per key: this means we'll have to scan drastically less metadata at
startup.

This adds
 - trigger for keeping it in sync with the all btree
 - initialization code, for filesystems from previous versions
 - new path for reading bucket gens
 - new fsck code

And a new on disk format version.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:51 -04:00
Kent Overstreet
a8b3a677e7 bcachefs: Nocow support
This adds support for nocow mode, where we do writes in-place when
possible. Patch components:

 - New boolean filesystem and inode option, nocow: note that when nocow
   is enabled, data checksumming and compression are implicitly disabled

 - To prevent in-place writes from racing with data moves
   (data_update.c) or bucket reuse (i.e. a bucket being reused and
   re-allocated while a nocow write is in flight, we have a new locking
   mechanism.

   Buckets can be locked for either data update or data move, using a
   fixed size hash table of two_state_shared locks. We don't have any
   chaining, meaning updates and moves to different buckets that hash to
   the same lock will wait unnecessarily - we'll want to watch for this
   becoming an issue.

 - The allocator path also needs to check for in-place writes in flight
   to a given bucket before giving it out: thus we add another counter
   to bucket_alloc_state so we can track this.

 - Fsync now may need to issue cache flushes to block devices instead of
   flushing the journal. We add a device bitmask to bch_inode_info,
   ei_devs_need_flush, which tracks devices that need to have flushes
   issued - note that this will lead to unnecessary flushes when other
   codepaths have already issued flushes, we may want to replace this with
   a sequence number.

 - New nocow write path: look up extents, and if they're writable write
   to them - otherwise fall back to the normal COW write path.

XXX: switch to sequence numbers instead of bitmask for devs needing
journal flush

XXX: ei_quota_lock being a mutex means bch2_nocow_write_done() needs to
run in process context - see if we can improve this

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:09:51 -04:00