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Creating subvolumes and snapshots is one of the core features of btrfs
and is even available to unprivileged users. Make it possible to use
subvolume and snapshot creation on idmapped mounts. This is a fairly
straightforward operation since all the permission checking helpers are
already capable of handling idmapped mounts. So we just need to pass
down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_permission() to handle idmapped mounts. This is just a
matter of passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_setattr() to handle idmapped mounts. This is just a matter
of passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_tmpfile() to handle idmapped mounts. This is just a matter
of passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_symlink() to handle idmapped mounts. This is just a matter
of passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_mkdir() to handle idmapped mounts. This is just a matter of
passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_create() to handle idmapped mounts. This is just a matter
of passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_mknod() to handle idmapped mounts. This is just a matter of
passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_getattr() to handle idmapped mounts. This is just a matter
of passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable btrfs_rename() to handle idmapped mounts. This is just a matter
of passing down the mount's userns.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Extend btrfs_new_inode() to take the idmapped mount into account when
initializing a new inode. This is just a matter of passing down the
mount's userns. The rest is taken care of in inode_init_owner(). This is
a preliminary patch to make the individual btrfs inode operations
idmapped mount aware.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We call split_zoned_em() on an extent_map on submitting a bio for it. Thus,
we can assume the extent_map is PINNED, not LOGGING, and in the modified
list. Add ASSERT()s to ensure the extent_maps after the split also has the
proper flags set and are in the modified list.
Suggested-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At the very end of btrfs_rename_exchange(), in case an error happened, we
are checking if 'new_inode' is NULL, but that is not needed since during a
rename exchange, unlike regular renames, 'new_inode' can never be NULL,
and if it were, we would have a crashed much earlier when we dereference it
multiple times.
So remove the check because it is not necessary and because it is causing
static checkers to emit a warning. I probably introduced the check by
copy-pasting similar code from btrfs_rename(), where 'new_inode' can be
NULL, in commit 86e8aa0e772cab ("Btrfs: unpin logs if rename exchange
operation fails").
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Writing out the verity data is too large of an operation to do in a
single transaction. If we are interrupted before we finish creating
fsverity metadata for a file, or fail to clean up already created
metadata after a failure, we could leak the verity items that we already
committed.
To address this issue, we use the orphan mechanism. When we start
enabling verity on a file, we also add an orphan item for that inode.
When we are finished, we delete the orphan. However, if we are
interrupted midway, the orphan will be present at mount and we can
cleanup the half-formed verity state.
There is a possible race with a normal unlink operation: if unlink and
verity run on the same file in parallel, it is possible for verity to
succeed and delete the still legitimate orphan added by unlink. Then, if
we are interrupted and mount in that state, we will never clean up the
inode properly. This is also possible for a file created with O_TMPFILE.
Check nlink==0 before deleting to avoid this race.
A final thing to note is that this is a resurrection of using orphans to
signal an operation besides "delete this inode". The old case was to
signal the need to do a truncate. That case still technically applies
for mounting very old file systems, so we need to take some care to not
clobber it. To that end, we just have to be careful that verity orphan
cleanup is a no-op for non-verity files.
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add support for fsverity in btrfs. To support the generic interface in
fs/verity, we add two new item types in the fs tree for inodes with
verity enabled. One stores the per-file verity descriptor and btrfs
verity item and the other stores the Merkle tree data itself.
Verity checking is done in end_page_read just before a page is marked
uptodate. This naturally handles a variety of edge cases like holes,
preallocated extents, and inline extents. Some care needs to be taken to
not try to verity pages past the end of the file, which are accessed by
the generic buffered file reading code under some circumstances like
reading to the end of the last page and trying to read again. Direct IO
on a verity file falls back to buffered reads.
Verity relies on PageChecked for the Merkle tree data itself to avoid
re-walking up shared paths in the tree. For this reason, we need to
cache the Merkle tree data. Since the file is immutable after verity is
turned on, we can cache it at an index past EOF.
Use the new inode ro_flags to store verity on the inode item, so that we
can enable verity on a file, then rollback to an older kernel and still
mount the file system and read the file. Since we can't safely write the
file anymore without ruining the invariants of the Merkle tree, we mark
a ro_compat flag on the file system when a file has verity enabled.
Acked-by: Eric Biggers <ebiggers@google.com>
Co-developed-by: Chris Mason <clm@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently, inode flags are fully backwards incompatible in btrfs. If we
introduce a new inode flag, then tree-checker will detect it and fail.
This can even cause us to fail to mount entirely. To make it possible to
introduce new flags which can be read-only compatible, like VERITY, we
add new ro flags to btrfs without treating them quite so harshly in
tree-checker. A read-only file system can survive an unexpected flag,
and can be mounted.
As for the implementation, it unfortunately gets a little complicated.
The on-disk representation of the inode, btrfs_inode_item, has an __le64
for flags but the in-memory representation, btrfs_inode, uses a u32.
David Sterba had the nice idea that we could reclaim those wasted 32 bits
on disk and use them for the new ro_compat flags.
It turns out that the tree-checker code which checks for unknown flags
is broken, and ignores the upper 32 bits we are hoping to use. The issue
is that the flags use the literal 1 rather than 1ULL, so the flags are
signed ints, and one of them is specifically (1 << 31). As a result, the
mask which ORs the flags is a negative integer on machines where int is
32 bit twos complement. When tree-checker evaluates the expression:
btrfs_inode_flags(leaf, iitem) & ~BTRFS_INODE_FLAG_MASK)
The mask is something like 0x80000abc, which gets promoted to u64 with
sign extension to 0xffffffff80000abc. Negating that 64 bit mask leaves
all the upper bits zeroed, and we can't detect unexpected flags.
This suggests that we can't use those bits after all. Luckily, we have
good reason to believe that they are zero anyway. Inode flags are
metadata, which is always checksummed, so any bit flips that would
introduce 1s would cause a checksum failure anyway (excluding the
improbable case of the checksum getting corrupted exactly badly).
Further, unless the 1 << 31 flag is used, the cast to u64 of the 32 bit
inode flag should preserve its value and not add leading zeroes
(at least for twos complement). The only place that flag
(BTRFS_INODE_ROOT_ITEM_INIT) is used is in a special inode embedded in
the root item, and indeed for that inode we see 0xffffffff80000000 as
the flags on disk. However, that inode is never seen by tree checker,
nor is it used in a context where verity might be meaningful.
Theoretically, a future ro flag might cause trouble on that inode, so we
should proactively clean up that mess before it does.
With the introduction of the new ro flags, keep two separate unsigned
masks and check them against the appropriate u32. Since we no longer run
afoul of sign extension, this also stops writing out 0xffffffff80000000
in root_item inodes going forward.
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When btrfs_run_delalloc_range() failed, we will error out.
But there is a strange comment mentioning that
btrfs_run_delalloc_range() could have returned value >0 to indicate the
IO has already started.
Commit 40f765805f08 ("Btrfs: split up __extent_writepage to lower stack
usage") introduced the comment, but unfortunately at that time, we were
already using @page_started to indicate that case, and still return 0.
Furthermore, even if that comment was right (which is not), we would
return -EIO if the IO had already started.
By all means the comment is incorrect, just remove the comment along
with the dead check.
Just to be extra safe, add an ASSERT() in btrfs_run_delalloc_range() to
make sure we either return 0 or error, no positive return value.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During renames we pin the logs of the roots a bit too early, before the
calls to btrfs_insert_inode_ref(). We can pin the logs after those calls,
since those will not change anything in a log tree.
In a scenario where we have multiple and diverse filesystem operations
running in parallel, those calls can take a significant amount of time,
due to lock contention on extent buffers, and delay log commits from other
tasks for longer than necessary.
So just pin logs after calls to btrfs_insert_inode_ref() and right before
the first operation that can update a log tree.
The following script that uses dbench was used for testing:
$ cat dbench-test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-m single -d single"
echo "performance" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
umount $DEV &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
dbench -D $MNT -t 120 16
umount $MNT
The tests were run on a machine with 12 cores, 64G of RAN, a NVMe device
and using a non-debug kernel config (Debian's default config).
The results compare a branch without this patch and without the previous
patch in the series, that has the subject:
"btrfs: eliminate some false positives when checking if inode was logged"
Versus the same branch with these two patches applied.
dbench with 8 clients, results before:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 4391359 0.009 249.745
Close 3225882 0.001 3.243
Rename 185953 0.065 240.643
Unlink 886669 0.049 249.906
Deltree 112 2.455 217.433
Mkdir 56 0.002 0.004
Qpathinfo 3980281 0.004 3.109
Qfileinfo 697579 0.001 0.187
Qfsinfo 729780 0.002 2.424
Sfileinfo 357764 0.004 1.415
Find 1538861 0.016 4.863
WriteX 2189666 0.010 3.327
ReadX 6883443 0.002 0.729
LockX 14298 0.002 0.073
UnlockX 14298 0.001 0.042
Flush 307777 2.447 303.663
Throughput 1149.6 MB/sec 8 clients 8 procs max_latency=303.666 ms
dbench with 8 clients, results after:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 4269920 0.009 213.532
Close 3136653 0.001 0.690
Rename 180805 0.082 213.858
Unlink 862189 0.050 172.893
Deltree 112 2.998 218.328
Mkdir 56 0.002 0.003
Qpathinfo 3870158 0.004 5.072
Qfileinfo 678375 0.001 0.194
Qfsinfo 709604 0.002 0.485
Sfileinfo 347850 0.004 1.304
Find 1496310 0.017 5.504
WriteX 2129613 0.010 2.882
ReadX 6693066 0.002 1.517
LockX 13902 0.002 0.075
UnlockX 13902 0.001 0.055
Flush 299276 2.511 220.189
Throughput 1187.33 MB/sec 8 clients 8 procs max_latency=220.194 ms
+3.2% throughput, -31.8% max latency
dbench with 16 clients, results before:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 5978334 0.028 156.507
Close 4391598 0.001 1.345
Rename 253136 0.241 155.057
Unlink 1207220 0.182 257.344
Deltree 160 6.123 36.277
Mkdir 80 0.003 0.005
Qpathinfo 5418817 0.012 6.867
Qfileinfo 949929 0.001 0.941
Qfsinfo 993560 0.002 1.386
Sfileinfo 486904 0.004 2.829
Find 2095088 0.059 8.164
WriteX 2982319 0.017 9.029
ReadX 9371484 0.002 4.052
LockX 19470 0.002 0.461
UnlockX 19470 0.001 0.990
Flush 418936 2.740 347.902
Throughput 1495.31 MB/sec 16 clients 16 procs max_latency=347.909 ms
dbench with 16 clients, results after:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 5711833 0.029 131.240
Close 4195897 0.001 1.732
Rename 241849 0.204 147.831
Unlink 1153341 0.184 231.322
Deltree 160 6.086 30.198
Mkdir 80 0.003 0.021
Qpathinfo 5177011 0.012 7.150
Qfileinfo 907768 0.001 0.793
Qfsinfo 949205 0.002 1.431
Sfileinfo 465317 0.004 2.454
Find 2001541 0.058 7.819
WriteX 2850661 0.017 9.110
ReadX 8952289 0.002 3.991
LockX 18596 0.002 0.655
UnlockX 18596 0.001 0.179
Flush 400342 2.879 293.607
Throughput 1565.73 MB/sec 16 clients 16 procs max_latency=293.611 ms
+4.6% throughput, -16.9% max latency
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When on SINGLE block group, btrfs_get_io_geometry() will return "the
size of the block group - the offset of the logical address within the
block group" as geom.len. Since we allow up to 8 GiB zone size on zoned
filesystem, we can have up to 8 GiB block group, so can have up to 8 GiB
geom.len as well. With this setup, we easily hit the "ASSERT(geom.len <=
INT_MAX);".
The ASSERT looks like to guard btrfs_bio_clone_partial() and bio_trim()
which both take "int" (now u64 due to the previous patch). So to be
precise the ASSERT should check if clone_len <= UINT_MAX. But actually,
clone_len is already capped by bio.bi_iter.bi_size which is unsigned
int. So the ASSERT is not necessary.
Drop the ASSERT and properly compare submit_len and geom.len in u64.
Then, let the implicit casting to convert it to u64.
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
sync_inode() has some holes that can cause problems if we're under heavy
ENOSPC pressure. If there's writeback running on a separate thread
sync_inode() will skip writing the inode altogether. What we really
want is to make sure writeback has been started on all the pages to make
sure we can see the ordered extents and wait on them if appropriate.
Switch to this new helper which will allow us to accomplish this and
avoid ENOSPC'ing early.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
I've been debugging an early ENOSPC problem in production and finally
root caused it to this problem. When we switched to the per-inode in
38d715f494f2 ("btrfs: use btrfs_start_delalloc_roots in
shrink_delalloc") I pulled out the async extent handling, because we
were doing the correct thing by calling filemap_flush() if we had async
extents set. This would properly wait on any async extents by locking
the page in the second flush, thus making sure our ordered extents were
properly set up.
However when I switched us back to page based flushing, I used
sync_inode(), which allows us to pass in our own wbc. The problem here
is that sync_inode() is smarter than the filemap_* helpers, it tries to
avoid calling writepages at all. This means that our second call could
skip calling do_writepages altogether, and thus not wait on the pagelock
for the async helpers. This means we could come back before any ordered
extents were created and then simply continue on in our flushing
mechanisms and ENOSPC out when we have plenty of space to use.
Fix this by putting back the async pages logic in shrink_delalloc. This
allows us to bulk write out everything that we need to, and then we can
wait in one place for the async helpers to catch up, and then wait on
any ordered extents that are created.
Fixes: e076ab2a2ca7 ("btrfs: shrink delalloc pages instead of full inodes")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We use the async_delalloc_pages mechanism to make sure that we've
completed our async work before trying to continue our delalloc
flushing. The reason for this is we need to see any ordered extents
that were created by our delalloc flushing. However we're waking up
before we do the submit work, which is before we create the ordered
extents. This is a pretty wide race window where we could potentially
think there are no ordered extents and thus exit shrink_delalloc
prematurely. Fix this by waking us up after we've done the work to
create ordered extents.
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since now we support data and metadata read-write for subpage, remove
the RO requirement for subpage mount.
There are some extra limitations though:
- For now, subpage RW mount is still considered experimental
Thus that mount warning will still be there.
- No compression support
There are still quite some PAGE_SIZE hard coded and quite some call
sites use extent_clear_unlock_delalloc() to unlock locked_page.
This will screw up subpage helpers.
Now for subpage RW mount, no matter what mount option or inode attr is
set, all writes will not be compressed. Although reading compressed
data has no problem.
- No defrag for subpage case
The defrag support for subpage case will come in later patches, which
will also rework the defrag workflow.
- No inline extent will be created
This is mostly due to the fact that filemap_fdatawrite_range() will
trigger more write than the range specified.
In fallocate calls, this behavior can make us to writeback which can
be inlined, before we enlarge the i_size.
This is a very special corner case, and even current btrfs check won't
report error on such inline extent + regular extent.
But considering how much effort has been put to prevent such inline +
regular, I'd prefer to cut off inline extent completely until we have
a good solution.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When relocating partial preallocated data extents (part of the
preallocated extent is written) for subpage, it can cause the following
false alert and make the relocation to fail:
BTRFS info (device dm-3): balance: start -d
BTRFS info (device dm-3): relocating block group 13631488 flags data
BTRFS warning (device dm-3): csum failed root -9 ino 257 off 4096 csum 0x98757625 expected csum 0x00000000 mirror 1
BTRFS error (device dm-3): bdev /dev/mapper/arm_nvme-test errs: wr 0, rd 0, flush 0, corrupt 1, gen 0
BTRFS warning (device dm-3): csum failed root -9 ino 257 off 4096 csum 0x98757625 expected csum 0x00000000 mirror 1
BTRFS error (device dm-3): bdev /dev/mapper/arm_nvme-test errs: wr 0, rd 0, flush 0, corrupt 2, gen 0
BTRFS info (device dm-3): balance: ended with status: -5
The minimal script to reproduce looks like this:
mkfs.btrfs -f -s 4k $dev
mount $dev -o nospace_cache $mnt
xfs_io -f -c "falloc 0 8k" $mnt/file
xfs_io -f -c "pwrite 0 4k" $mnt/file
btrfs balance start -d $mnt
[CAUSE]
Function btrfs_verify_data_csum() checks if the full range has
EXTENT_NODATASUM bit for data reloc inode, if *all* bytes of the range
have EXTENT_NODATASUM bit, then it skip the range.
This works pretty well for regular sectorsize, as in that case
btrfs_verify_data_csum() is called for each sector, thus no problem at
all.
But for subpage case, btrfs_verify_data_csum() is called on each bvec,
which can contain several sectors, and since it checks *all* bytes for
EXTENT_NODATASUM bit, if we have some range with csum, then we will
continue checking all the sectors.
For the preallocated sectors, it doesn't have any csum, thus obviously
the csum won't match and cause the false alert.
[FIX]
Move the EXTENT_NODATASUM check into the main loop, so that we can check
each sector for EXTENT_NODATASUM bit for subpage case.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
There is a possible use-after-free bug when running generic/095.
BUG: Unable to handle kernel data access on write at 0x6b6b6b6b6b6b725b
Faulting instruction address: 0xc000000000283654
c000000000283078 do_raw_spin_unlock+0x88/0x230
c0000000012b1e14 _raw_spin_unlock_irqrestore+0x44/0x90
c000000000a918dc btrfs_subpage_clear_writeback+0xac/0xe0
c0000000009e0458 end_bio_extent_writepage+0x158/0x270
c000000000b6fd14 bio_endio+0x254/0x270
c0000000009fc0f0 btrfs_end_bio+0x1a0/0x200
c000000000b6fd14 bio_endio+0x254/0x270
c000000000b781fc blk_update_request+0x46c/0x670
c000000000b8b394 blk_mq_end_request+0x34/0x1d0
c000000000d82d1c lo_complete_rq+0x11c/0x140
c000000000b880a4 blk_complete_reqs+0x84/0xb0
c0000000012b2ca4 __do_softirq+0x334/0x680
c0000000001dd878 irq_exit+0x148/0x1d0
c000000000016f4c do_IRQ+0x20c/0x240
c000000000009240 hardware_interrupt_common_virt+0x1b0/0x1c0
[CAUSE]
There is very small race window like the following in generic/095.
Thread 1 | Thread 2
--------------------------------+------------------------------------
end_bio_extent_writepage() | btrfs_releasepage()
|- spin_lock_irqsave() | |
|- end_page_writeback() | |
| | |- if (PageWriteback() ||...)
| | |- clear_page_extent_mapped()
| | |- kfree(subpage);
|- spin_unlock_irqrestore().
The race can also happen between writeback and btrfs_invalidatepage(),
although that would be much harder as btrfs_invalidatepage() has much
more work to do before the clear_page_extent_mapped() call.
[FIX]
Here we "wait" for the subapge spinlock to be released before we detach
subpage structure.
So this patch will introduce a new function, wait_subpage_spinlock(), to
do the "wait" by acquiring the spinlock and release it.
Since the caller has ensured the page is not dirty nor writeback, and
page is already locked, the only way to hold the subpage spinlock is
from endio function.
Thus we only need to acquire the spinlock to wait for any existing
holder.
Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When running the following fsx command (extracted from generic/127) on
subpage filesystem, it can create inline extent with regular extents:
fsx -q -l 262144 -o 65536 -S 191110531 -N 9057 -R -W $mnt/file > /tmp/fsx
The offending extent would look like:
item 9 key (257 INODE_REF 256) itemoff 15703 itemsize 14
index 2 namelen 4 name: file
item 10 key (257 EXTENT_DATA 0) itemoff 14975 itemsize 728
generation 7 type 0 (inline)
inline extent data size 707 ram_bytes 707 compression 0 (none)
item 11 key (257 EXTENT_DATA 4096) itemoff 14922 itemsize 53
generation 7 type 2 (prealloc)
prealloc data disk byte 102346752 nr 4096
prealloc data offset 0 nr 4096
[CAUSE]
For subpage filesystem, the writeback is triggered in page units, which
means, even if we just want to writeback range [16K, 20K) for 64K page
system, we will still try to writeback any dirty sector of range [0, 64K).
This is never a problem if sectorsize == PAGE_SIZE, but for subpage,
this can cause unexpected problems.
For above test case, the last several operations from fsx are:
9055 trunc from 0x40000 to 0x2c3
9057 falloc from 0x164c to 0x19d2 (0x386 bytes)
In operation 9055, we dirtied sector [0, 4096), then in falloc, we call
btrfs_wait_ordered_range(inode, start=4096, len=4096), only expecting to
writeback any dirty data in [4096, 8192), but nothing else.
Unfortunately, in subpage case, above btrfs_wait_ordered_range() will
trigger writeback of the range [0, 64K), which includes the data at
[0, 4096).
And since at the call site, we haven't yet increased i_size, which is
still 707, this means cow_file_range() can insert an inline extent.
Resulting above inline + regular extent.
[WORKAROUND]
I don't really have any good short-term solution yet, as this means all
operations that would trigger writeback need to be reviewed for any
i_size change.
So here I choose to disable inline extent creation for subpage case as a
workaround. We have done tons of work just to avoid such extent, so I
don't to create an exception just for subpage.
This only affects inline extent creation, subpage has no problem reading
existing inline extents at all.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When testing experimental subpage compressed write support, it hits a
NULL pointer dereference inside read path:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018
pc : __pi_memcmp+0x28/0x1ec
lr : check_data_csum+0xd0/0x274 [btrfs]
Call trace:
__pi_memcmp+0x28/0x1ec
btrfs_verify_data_csum+0xf4/0x244 [btrfs]
end_bio_extent_readpage+0x1d0/0x6b0 [btrfs]
bio_endio+0x15c/0x1dc
end_workqueue_fn+0x44/0x64 [btrfs]
btrfs_work_helper+0x74/0x250 [btrfs]
process_one_work+0x1d4/0x47c
worker_thread+0x180/0x400
kthread+0x11c/0x120
ret_from_fork+0x10/0x30
Code: 54000261 d100044c d343fd8c f8408403 (f8408424)
---[ end trace 9e2c59f33ea40866 ]---
[CAUSE]
When reading two compressed extents inside the same page, like the
following layout, we trigger above crash:
0 32K 64K
|-------|\\\\\\\|
| \- Compressed extent (A)
\--------- Compressed extent (B)
For compressed read, we don't need to populate its io_bio->csum, as we
rely on compressed_bio->csum to verify the compressed data, and then
copy the decompressed to inode pages.
Normally btrfs_verify_data_csum() skip such page by checking and
clearing its PageChecked flag
But since that flag is still for the full page, when endio for inode
page range [0, 32K) gets executed, it clears PageChecked flag for the
full page.
Then when endio for inode page range [32K, 64K) gets executed, since the
page no longer has PageChecked flag, it just continues checking, even
though io_bio->csum is NULL.
[FIX]
Thankfully there are only two users of PageChecked bit:
- Cow fixup
Since subpage has its own way to trace page dirty (dirty_bitmap) and
ordered bit (ordered_bitmap), it should never trigger cow fixup.
- Compressed read
We can distinguish such read by just checking io_bio->csum.
So just check io_bio->csum before doing the verification to avoid such
NULL pointer dereference.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In commit e65f152e4348 ("btrfs: refactor how we finish ordered extent io
for endio functions") there was last caller not using 1 for the uptodate
parameter. Now there's only one, passing 1, so we can remove it and
simplify the code.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since commit d75855b4518b ("btrfs: Remove
extent_io_ops::writepage_start_hook") removes the writepage_start_hook()
and adds btrfs_writepage_cow_fixup() function, there is no need to
follow the old hook parameters.
Remove the @start and @end hook, since currently the fixup check is full
page check, it doesn't need @start and @end hook.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When using the NO_HOLES feature and expanding the size of an inode, we
update the inode's last_trans, last_sub_trans and last_log_commit fields
at maybe_insert_hole() so that a fsync does know that the inode needs to
be logged (by making sure that btrfs_inode_in_log() returns false). This
happens for expanding truncate operations, buffered writes, direct IO
writes and when cloning extents to an offset greater than the inode's
i_size.
However the way we do it is racy, because in between setting the inode's
last_sub_trans and last_log_commit fields, the log transaction ID that was
assigned to last_sub_trans might be committed before we read the root's
last_log_commit and assign that value to last_log_commit. If that happens
it would make a future call to btrfs_inode_in_log() return true. This is
a race that should be extremely unlikely to be hit in practice, and it is
the same that was described by commit bc0939fcfab0d7 ("btrfs: fix race
between marking inode needs to be logged and log syncing").
The fix would simply be to set last_log_commit to the value we assigned
to last_sub_trans minus 1, like it was done in that commit. However
updating these two fields plus the last_trans field is pointless here
because all the callers of btrfs_cont_expand() (which is the only
caller of maybe_insert_hole()) always call btrfs_set_inode_last_trans()
or btrfs_update_inode() after calling btrfs_cont_expand(). Calling either
btrfs_set_inode_last_trans() or btrfs_update_inode() guarantees that the
next fsync will log the inode, as it makes btrfs_inode_in_log() return
false.
So just remove the code that explicitly sets the inode's last_trans,
last_sub_trans and last_log_commit fields.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The pages in compressed_pages are not from highmem anymore so we can
drop the mapping for checksum calculation and inline extent.
Signed-off-by: David Sterba <dsterba@suse.com>
Cross-rename lacks a check when that would prevent exchanging a
directory and subvolume from different parent subvolume. This causes
data inconsistencies and is caught before commit by tree-checker,
turning the filesystem to read-only.
Calling the renameat2 with RENAME_EXCHANGE flags like
renameat2(AT_FDCWD, namesrc, AT_FDCWD, namedest, (1 << 1))
on two paths:
namesrc = dir1/subvol1/dir2
namedest = subvol2/subvol3
will cause key order problem with following write time tree-checker
report:
[1194842.307890] BTRFS critical (device loop1): corrupt leaf: root=5 block=27574272 slot=10 ino=258, invalid previous key objectid, have 257 expect 258
[1194842.322221] BTRFS info (device loop1): leaf 27574272 gen 8 total ptrs 11 free space 15444 owner 5
[1194842.331562] BTRFS info (device loop1): refs 2 lock_owner 0 current 26561
[1194842.338772] item 0 key (256 1 0) itemoff 16123 itemsize 160
[1194842.338793] inode generation 3 size 16 mode 40755
[1194842.338801] item 1 key (256 12 256) itemoff 16111 itemsize 12
[1194842.338809] item 2 key (256 84 2248503653) itemoff 16077 itemsize 34
[1194842.338817] dir oid 258 type 2
[1194842.338823] item 3 key (256 84 2363071922) itemoff 16043 itemsize 34
[1194842.338830] dir oid 257 type 2
[1194842.338836] item 4 key (256 96 2) itemoff 16009 itemsize 34
[1194842.338843] item 5 key (256 96 3) itemoff 15975 itemsize 34
[1194842.338852] item 6 key (257 1 0) itemoff 15815 itemsize 160
[1194842.338863] inode generation 6 size 8 mode 40755
[1194842.338869] item 7 key (257 12 256) itemoff 15801 itemsize 14
[1194842.338876] item 8 key (257 84 2505409169) itemoff 15767 itemsize 34
[1194842.338883] dir oid 256 type 2
[1194842.338888] item 9 key (257 96 2) itemoff 15733 itemsize 34
[1194842.338895] item 10 key (258 12 256) itemoff 15719 itemsize 14
[1194842.339163] BTRFS error (device loop1): block=27574272 write time tree block corruption detected
[1194842.339245] ------------[ cut here ]------------
[1194842.443422] WARNING: CPU: 6 PID: 26561 at fs/btrfs/disk-io.c:449 csum_one_extent_buffer+0xed/0x100 [btrfs]
[1194842.511863] CPU: 6 PID: 26561 Comm: kworker/u17:2 Not tainted 5.14.0-rc3-git+ #793
[1194842.511870] Hardware name: empty empty/S3993, BIOS PAQEX0-3 02/24/2008
[1194842.511876] Workqueue: btrfs-worker-high btrfs_work_helper [btrfs]
[1194842.511976] RIP: 0010:csum_one_extent_buffer+0xed/0x100 [btrfs]
[1194842.512068] RSP: 0018:ffffa2c284d77da0 EFLAGS: 00010282
[1194842.512074] RAX: 0000000000000000 RBX: 0000000000001000 RCX: ffff928867bd9978
[1194842.512078] RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff928867bd9970
[1194842.512081] RBP: ffff92876b958000 R08: 0000000000000001 R09: 00000000000c0003
[1194842.512085] R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
[1194842.512088] R13: ffff92875f989f98 R14: 0000000000000000 R15: 0000000000000000
[1194842.512092] FS: 0000000000000000(0000) GS:ffff928867a00000(0000) knlGS:0000000000000000
[1194842.512095] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1194842.512099] CR2: 000055f5384da1f0 CR3: 0000000102fe4000 CR4: 00000000000006e0
[1194842.512103] Call Trace:
[1194842.512128] ? run_one_async_free+0x10/0x10 [btrfs]
[1194842.631729] btree_csum_one_bio+0x1ac/0x1d0 [btrfs]
[1194842.631837] run_one_async_start+0x18/0x30 [btrfs]
[1194842.631938] btrfs_work_helper+0xd5/0x1d0 [btrfs]
[1194842.647482] process_one_work+0x262/0x5e0
[1194842.647520] worker_thread+0x4c/0x320
[1194842.655935] ? process_one_work+0x5e0/0x5e0
[1194842.655946] kthread+0x135/0x160
[1194842.655953] ? set_kthread_struct+0x40/0x40
[1194842.655965] ret_from_fork+0x1f/0x30
[1194842.672465] irq event stamp: 1729
[1194842.672469] hardirqs last enabled at (1735): [<ffffffffbd1104f5>] console_trylock_spinning+0x185/0x1a0
[1194842.672477] hardirqs last disabled at (1740): [<ffffffffbd1104cc>] console_trylock_spinning+0x15c/0x1a0
[1194842.672482] softirqs last enabled at (1666): [<ffffffffbdc002e1>] __do_softirq+0x2e1/0x50a
[1194842.672491] softirqs last disabled at (1651): [<ffffffffbd08aab7>] __irq_exit_rcu+0xa7/0xd0
The corrupted data will not be written, and filesystem can be unmounted
and mounted again (all changes since the last commit will be lost).
Add the missing check for new_ino so that all non-subvolumes must reside
under the same parent subvolume. There's an exception allowing to
exchange two subvolumes from any parents as the directory representing a
subvolume is only a logical link and does not have any other structures
related to the parent subvolume, unlike files, directories etc, that
are always in the inode namespace of the parent subvolume.
Fixes: cdd1fedf8261 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC: stable@vger.kernel.org # 4.7+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Store the block device instead of the gendisk in the btrfs_ordered_extent
structure instead of acquiring a reference to it later.
Note: this is from series removing bdgrab/bdput, btrfs is one of the
last users.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Damien reported a test failure with btrfs/209. The test itself ran fine,
but the fsck ran afterwards reported a corrupted filesystem.
The filesystem corruption happens because we're splitting an extent and
then writing the extent twice. We have to split the extent though, because
we're creating too large extents for a REQ_OP_ZONE_APPEND operation.
When dumping the extent tree, we can see two EXTENT_ITEMs at the same
start address but different lengths.
$ btrfs inspect dump-tree /dev/nullb1 -t extent
...
item 19 key (269484032 EXTENT_ITEM 126976) itemoff 15470 itemsize 53
refs 1 gen 7 flags DATA
extent data backref root FS_TREE objectid 257 offset 786432 count 1
item 20 key (269484032 EXTENT_ITEM 262144) itemoff 15417 itemsize 53
refs 1 gen 7 flags DATA
extent data backref root FS_TREE objectid 257 offset 786432 count 1
The duplicated EXTENT_ITEMs originally come from wrongly split extent_map in
extract_ordered_extent(). Since extract_ordered_extent() uses
create_io_em() to split an existing extent_map, we will have
split->orig_start != split->start. Then, it will be logged with non-zero
"extent data offset". Finally, the logged entries are replayed into
a duplicated EXTENT_ITEM.
Introduce and use proper splitting function for extent_map. The function is
intended to be simple and specific usage for extract_ordered_extent() e.g.
not supporting compression case (we do not allow splitting compressed
extent_map anyway).
There was a question raised by Qu, in summary why we want to split the
extent map (and not the bio):
The problem is not the limit on the zone end, which as you mention is
the same as the block group end. The problem is that data write use zone
append (ZA) operations. ZA BIOs cannot be split so a large extent may
need to be processed with multiple ZA BIOs, While that is also true for
regular writes, the major difference is that ZA are "nameless" write
operation giving back the written sectors on completion. And ZA
operations may be reordered by the block layer (not intentionally
though). Combine both of these characteristics and you can see that the
data for a large extent may end up being shuffled when written resulting
in data corruption and the impossibility to map the extent to some start
sector.
To avoid this problem, zoned btrfs uses the principle "one data extent
== one ZA BIO". So large extents need to be split. This is unfortunate,
but we can revisit this later and optimize, e.g. merge back together the
fragments of an extent once written if they actually were written
sequentially in the zone.
Reported-by: Damien Le Moal <damien.lemoal@wdc.com>
Fixes: d22002fd37bd ("btrfs: zoned: split ordered extent when bio is sent")
CC: stable@vger.kernel.org # 5.12+
CC: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The early check if we should attempt compression does not take into
account the number of input pages. It can happen that there's only one
page, eg. a tail page after some ranges of the BTRFS_MAX_UNCOMPRESSED
have been processed, or an isolated page that won't be converted to an
inline extent.
The single page would be compressed but a later check would drop it
again because the result size must be at least one block shorter than
the input. That can never work with just one page.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
With current btrfs subpage rw support, the following script can lead to
fs hang:
$ mkfs.btrfs -f -s 4k $dev
$ mount $dev -o nospace_cache $mnt
$ fsstress -w -n 100 -p 1 -s 1608140256 -v -d $mnt
The fs will hang at btrfs_start_ordered_extent().
[CAUSE]
In above test case, btrfs_invalidate() will be called with the following
parameters:
offset = 0 length = 53248 page dirty = 1 subpage dirty bitmap = 0x2000
Since @offset is 0, btrfs_invalidate() will try to invalidate the full
page, and finally call clear_page_extent_mapped() which will detach
subpage structure from the page.
And since the page no longer has subpage structure, the subpage dirty
bitmap will be cleared, preventing the dirty range from being written
back, thus no way to wake up the ordered extent.
[FIX]
Just follow other filesystems, only to invalidate the page if the range
covers the full page.
There are cases like truncate_setsize() which can call
btrfs_invalidatepage() with offset == 0 and length != 0 for the last
page of an inode.
Although the old code will still try to invalidate the full page, we are
still safe to just wait for ordered extent to finish.
So it shouldn't cause extra problems.
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Only set_page_dirty() and SetPageUptodate() is not subpage compatible.
Convert them to subpage helpers, so that __extent_writepage_io() can
submit page content correctly.
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_truncate_block() itself is already mostly subpage compatible, the
only missing part is the page dirtying code.
Currently if we have a sector that needs to be truncated, we set the
sector aligned range delalloc, then set the full page dirty.
The problem is, current subpage code requires subpage dirty bit to be
set, or __extent_writepage_io() won't submit bio, thus leads to ordered
extent never to finish.
So this patch will make btrfs_truncate_block() to call
btrfs_page_set_dirty() helper to replace set_page_dirty() to fix the
problem.
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Function btrfs_set_range_writeback() currently just sets the page
writeback unconditionally.
Change it to call the subpage helper so that we can handle both cases
well.
Since the subpage helpers needs btrfs_fs_info, also change the parameter
to accept btrfs_inode.
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In cow_file_range(), after we have succeeded creating an inline extent,
we unlock the page with extent_clear_unlock_delalloc() by passing
locked_page == NULL.
For sectorsize == PAGE_SIZE case, this is just making the page lock and
unlock harder to grab.
But for incoming subpage case, it can be a big problem.
For incoming subpage case, page locking have two entry points:
- __process_pages_contig()
In that case, we know exactly the range we want to lock (which only
requires sector alignment).
To handle the subpage requirement, we introduce btrfs_subpage::writers
to page::private, and will update it in __process_pages_contig().
- Other directly lock/unlock_page() call sites
Those won't touch btrfs_subpage::writers at all.
This means, page locked by __process_pages_contig() can only be unlocked
by __process_pages_contig().
Thankfully we already have the existing infrastructure in the form of
@locked_page in various call sites.
Unfortunately, extent_clear_unlock_delalloc() in cow_file_range() after
creating an inline extent is the exception.
It intentionally call extent_clear_unlock_delalloc() with locked_page ==
NULL, to also unlock current page (and clear its dirty/writeback bits).
To co-operate with incoming subpage modifications, and make the page
lock/unlock pair easier to understand, this patch will still call
extent_clear_unlock_delalloc() with locked_page, and only unlock the
page in __extent_writepage().
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This involves the following modification:
- Ordered extent creation
This is done in process_one_page(), now PAGE_SET_ORDERED will call
subpage helper to do the work.
- endio functions
This is done in btrfs_mark_ordered_io_finished().
- btrfs_invalidatepage()
- btrfs_cleanup_ordered_extents()
Use the subpage page helper, and add an extra branch to exit if the
locked page have covered the full range.
Now the usage of page Ordered flag for ordered extent accounting is fully
subpage compatible.
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When running subpage preparation patches on x86, btrfs/125 will hang
forever with one ordered extent never finished.
[CAUSE]
The test case btrfs/125 itself will always fail as the fix is never merged.
When the test fails at balance, btrfs needs to cleanup the ordered
extent in btrfs_cleanup_ordered_extents() for data reloc inode.
The problem is in the sequence how we cleanup the page Order bit.
Currently it works like:
btrfs_cleanup_ordered_extents()
|- find_get_page();
|- btrfs_page_clear_ordered(page);
| Now the page doesn't have Ordered bit anymore.
| !!! This also includes the first (locked) page !!!
|
|- offset += PAGE_SIZE
| This is to skip the first page
|- __endio_write_update_ordered()
|- btrfs_mark_ordered_io_finished(NULL)
Except the first page, all ordered extents are finished.
Then the locked page is cleaned up in __extent_writepage():
__extent_writepage()
|- If (PageError(page))
|- end_extent_writepage()
|- btrfs_mark_ordered_io_finished(page)
|- if (btrfs_test_page_ordered(page))
|- !!! The page gets skipped !!!
The ordered extent is not decreased as the page doesn't
have ordered bit anymore.
This leaves the ordered extent with bytes_left == sectorsize, thus never
finish.
[FIX]
The fix is to ensure we never clear page Ordered bit without running the
ordered extent accounting.
Here we choose to skip the locked page in
btrfs_cleanup_ordered_extents() so that later end_extent_writepage() can
properly finish the ordered extent.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Inside btrfs we use Private2 page status to indicate we have an ordered
extent with pending IO for the sector.
But the page status name, Private2, tells us nothing about the bit
itself, so this patch will rename it to Ordered.
And with extra comment about the bit added, so reader who is still
uncertain about the page Ordered status, will find the comment pretty
easily.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This patch will refactor btrfs_invalidatepage() for the incoming subpage
support.
The involved modifications are:
- Use while() loop instead of "goto again;"
- Use single variable to determine whether to delete extent states
Each branch will also have comments why we can or cannot delete the
extent states
- Do qgroup free and extent states deletion per-loop
Current code can only work for PAGE_SIZE == sectorsize case.
This refactor also makes it clear what we do for different sectors:
- Sectors without ordered extent
We're completely safe to remove all extent states for the sector(s)
- Sectors with ordered extent, but no Private2 bit
This means the endio has already been executed, we can't remove all
extent states for the sector(s).
- Sectors with ordere extent, still has Private2 bit
This means we need to decrease the ordered extent accounting.
And then it comes to two different variants:
* We have finished and removed the ordered extent
Then it's the same as "sectors without ordered extent"
* We didn't finished the ordered extent
We can remove some extent states, but not all.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The existing comments in btrfs_invalidatepage() don't really get to the
point, especially for what Private2 is really representing and how the
race avoidance is done.
The truth is, there are only three entrances to do ordered extent
accounting:
- btrfs_writepage_endio_finish_ordered()
- __endio_write_update_ordered()
Those two entrance are just endio functions for dio and buffered
write.
- btrfs_invalidatepage()
But there is a pitfall, in endio functions there is no check on whether
the ordered extent is already accounted.
They just blindly clear the Private2 bit and do the accounting.
So it's all btrfs_invalidatepage()'s responsibility to make sure we
won't do double account for the same sector.
That's why in btrfs_invalidatepage() we have to wait for page writeback,
this will ensure all submitted bios have finished, thus their endio
functions have finished the accounting on the ordered extent.
Then we also check page Private2 to ensure that, we only run ordered
extent accounting on pages who has no bio submitted.
This patch will rework related comments to make it more clear on the
race and how we use wait_on_page_writeback() and Private2 to prevent
double accounting on ordered extent.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs has two endio functions to mark certain io range finished for
ordered extents:
- __endio_write_update_ordered()
This is for direct IO
- btrfs_writepage_endio_finish_ordered()
This for buffered IO.
However they go different routines to handle ordered extent io:
- Whether to iterate through all ordered extents
__endio_write_update_ordered() will but
btrfs_writepage_endio_finish_ordered() will not.
In fact, iterating through all ordered extents will benefit later
subpage support, while for current PAGE_SIZE == sectorsize requirement
this behavior makes no difference.
- Whether to update page Private2 flag
__endio_write_update_ordered() will not update page Private2 flag as
for iomap direct IO, the page can not be even mapped.
While btrfs_writepage_endio_finish_ordered() will clear Private2 to
prevent double accounting against btrfs_invalidatepage().
Those differences are pretty subtle, and the ordered extent iterations
code in callers makes code much harder to read.
So this patch will introduce a new function,
btrfs_mark_ordered_io_finished(), to do the heavy lifting:
- Iterate through all ordered extents in the range
- Do the ordered extent accounting
- Queue the work for finished ordered extent
This function has two new feature:
- Proper underflow detection and recovery
The old underflow detection will only detect the problem, then
continue.
No proper info like root/inode/ordered extent info, nor noisy enough
to be caught by fstests.
Furthermore when underflow happens, the ordered extent will never
finish.
New error detection will reset the bytes_left to 0, do proper
kernel warning, and output extra info including root, ino, ordered
extent range, the underflow value.
- Prevent double accounting based on Private2 flag
Now if we find a range without Private2 flag, we will skip to next
range.
As that means someone else has already finished the accounting of
ordered extent.
This makes no difference for current code, but will be a critical part
for incoming subpage support, as we can call
btrfs_mark_ordered_io_finished() for multiple sectors if they are
beyond inode size.
Thus such double accounting prevention is a key feature for subpage.
Now both endio functions only need to call that new function.
And since the only caller of btrfs_dec_test_first_ordered_pending() is
removed, also remove btrfs_dec_test_first_ordered_pending() completely.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently we use page Private2 bit to indicate that we have ordered
extent for the page range.
But the lifespan of it is not consistent, during regular writeback path,
there are two locations to clear the same PagePrivate2:
T ----- Page marked Dirty
|
+ ----- Page marked Private2, through btrfs_run_dealloc_range()
|
+ ----- Page cleared Private2, through btrfs_writepage_cow_fixup()
| in __extent_writepage_io()
| ^^^ Private2 cleared for the first time
|
+ ----- Page marked Writeback, through btrfs_set_range_writeback()
| in __extent_writepage_io().
|
+ ----- Page cleared Private2, through
| btrfs_writepage_endio_finish_ordered()
| ^^^ Private2 cleared for the second time.
|
+ ----- Page cleared Writeback, through
btrfs_writepage_endio_finish_ordered()
Currently PagePrivate2 is mostly to prevent ordered extent accounting
being executed for both endio and invalidatepage.
Thus only the one who cleared page Private2 is responsible for ordered
extent accounting.
But the fact is, in btrfs_writepage_endio_finish_ordered(), page
Private2 is cleared and ordered extent accounting is executed
unconditionally.
The race prevention only happens through btrfs_invalidatepage(), where
we wait for the page writeback first, before checking the Private2 bit.
This means, Private2 is also protected by Writeback bit, and there is no
need for btrfs_writepage_cow_fixup() to clear Priavte2.
This patch will change btrfs_writepage_cow_fixup() to just check
PagePrivate2, not to clear it.
The clearing will happen in either btrfs_invalidatepage() or
btrfs_writepage_endio_finish_ordered().
This makes the Private2 bit easier to understand, just meaning the page
has unfinished ordered extent attached to it.
And this patch is a hard requirement for the incoming refactoring for
how we finished ordered IO for endio context, as the coming patch will
check Private2 to determine if we need to do the ordered extent
accounting. Thus this patch is definitely needed or we will hang due to
unfinished ordered extent.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There is a pretty bad abuse of btrfs_writepage_endio_finish_ordered() in
end_compressed_bio_write().
It passes compressed pages to btrfs_writepage_endio_finish_ordered(),
which is only supposed to accept inode pages.
Thankfully the important info here is the inode, so let's pass
btrfs_inode directly into btrfs_writepage_endio_finish_ordered(), and
make @page parameter optional.
By this, end_compressed_bio_write() can happily pass page=NULL while
still getting everything done properly.
Also, to cooperate with such modification, replace @page parameter for
trace_btrfs_writepage_end_io_hook() with btrfs_inode.
Although this removes page_index info, the existing start/len should be
enough for most usage.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
