- Fix an incorrect free space calculation in xfs_reserve_blocks that
could lead to a request for free blocks that will never succeed.
- Fix a hang in xfs_reserve_blocks caused by an infinite loop and the
incorrect free space calculation.
- Fix yet a third problem in xfs_reserve_blocks where multiple racing
threads can overfill the reserve pool.
- Fix an accounting error that lead to us reporting reserved space as
"available".
- Fix a race condition during abnormal fs shutdown that could cause UAF
problems when memory reclaim and log shutdown try to clean up inodes.
- Fix a bug where log shutdown can race with unmount to tear down the
log, thereby causing UAF errors.
- Disentangle log and filesystem shutdown to reduce confusion.
- Fix some confusion in xfs_trans_commit such that a race between
transaction commit and filesystem shutdown can cause unlogged dirty
inode metadata to be committed, thereby corrupting the filesystem.
- Remove a performance optimization in the log as it was discovered that
certain storage hardware handle async log flushes so poorly as to
cause serious performance regressions. Recent restructuring of other
parts of the logging code mean that no performance benefit is seen on
hardware that handle it well.
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Merge tag 'xfs-5.18-merge-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs fixes from Darrick Wong:
"This fixes multiple problems in the reserve pool sizing functions: an
incorrect free space calculation, a pointless infinite loop, and even
more braindamage that could result in the pool being overfilled. The
pile of patches from Dave fix myriad races and UAF bugs in the log
recovery code that much to our mutual surprise nobody's tripped over.
Dave also fixed a performance optimization that had turned into a
regression.
Dave Chinner is taking over as XFS maintainer starting Sunday and
lasting until 5.19-rc1 is tagged so that I can focus on starting a
massive design review for the (feature complete after five years)
online repair feature. From then on, he and I will be moving XFS to a
co-maintainership model by trading duties every other release.
NOTE: I hope very strongly that the other pieces of the (X)FS
ecosystem (fstests and xfsprogs) will make similar changes to spread
their maintenance load.
Summary:
- Fix an incorrect free space calculation in xfs_reserve_blocks that
could lead to a request for free blocks that will never succeed.
- Fix a hang in xfs_reserve_blocks caused by an infinite loop and the
incorrect free space calculation.
- Fix yet a third problem in xfs_reserve_blocks where multiple racing
threads can overfill the reserve pool.
- Fix an accounting error that lead to us reporting reserved space as
"available".
- Fix a race condition during abnormal fs shutdown that could cause
UAF problems when memory reclaim and log shutdown try to clean up
inodes.
- Fix a bug where log shutdown can race with unmount to tear down the
log, thereby causing UAF errors.
- Disentangle log and filesystem shutdown to reduce confusion.
- Fix some confusion in xfs_trans_commit such that a race between
transaction commit and filesystem shutdown can cause unlogged dirty
inode metadata to be committed, thereby corrupting the filesystem.
- Remove a performance optimization in the log as it was discovered
that certain storage hardware handle async log flushes so poorly as
to cause serious performance regressions. Recent restructuring of
other parts of the logging code mean that no performance benefit is
seen on hardware that handle it well"
* tag 'xfs-5.18-merge-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: drop async cache flushes from CIL commits.
xfs: shutdown during log recovery needs to mark the log shutdown
xfs: xfs_trans_commit() path must check for log shutdown
xfs: xfs_do_force_shutdown needs to block racing shutdowns
xfs: log shutdown triggers should only shut down the log
xfs: run callbacks before waking waiters in xlog_state_shutdown_callbacks
xfs: shutdown in intent recovery has non-intent items in the AIL
xfs: aborting inodes on shutdown may need buffer lock
xfs: don't report reserved bnobt space as available
xfs: fix overfilling of reserve pool
xfs: always succeed at setting the reserve pool size
xfs: remove infinite loop when reserving free block pool
xfs: don't include bnobt blocks when reserving free block pool
xfs: document the XFS_ALLOC_AGFL_RESERVE constant
Jan Kara reported a performance regression in dbench that he
bisected down to commit bad77c375e ("xfs: CIL checkpoint
flushes caches unconditionally").
Whilst developing the journal flush/fua optimisations this cache was
part of, it appeared to made a significant difference to
performance. However, now that this patchset has settled and all the
correctness issues fixed, there does not appear to be any
significant performance benefit to asynchronous cache flushes.
In fact, the opposite is true on some storage types and workloads,
where additional cache flushes that can occur from fsync heavy
workloads have measurable and significant impact on overall
throughput.
Local dbench testing shows little difference on dbench runs with
sync vs async cache flushes on either fast or slow SSD storage, and
no difference in streaming concurrent async transaction workloads
like fs-mark.
Fast NVME storage.
From `dbench -t 30`, CIL scale:
clients async sync
BW Latency BW Latency
1 935.18 0.855 915.64 0.903
8 2404.51 6.873 2341.77 6.511
16 3003.42 6.460 2931.57 6.529
32 3697.23 7.939 3596.28 7.894
128 7237.43 15.495 7217.74 11.588
512 5079.24 90.587 5167.08 95.822
fsmark, 32 threads, create w/ 64 byte xattr w/32k logbsize
create chown unlink
async 1m41s 1m16s 2m03s
sync 1m40s 1m19s 1m54s
Slower SATA SSD storage:
From `dbench -t 30`, CIL scale:
clients async sync
BW Latency BW Latency
1 78.59 15.792 83.78 10.729
8 367.88 92.067 404.63 59.943
16 564.51 72.524 602.71 76.089
32 831.66 105.984 870.26 110.482
128 1659.76 102.969 1624.73 91.356
512 2135.91 223.054 2603.07 161.160
fsmark, 16 threads, create w/32k logbsize
create unlink
async 5m06s 4m15s
sync 5m00s 4m22s
And on Jan's test machine:
5.18-rc8-vanilla 5.18-rc8-patched
Amean 1 71.22 ( 0.00%) 64.94 * 8.81%*
Amean 2 93.03 ( 0.00%) 84.80 * 8.85%*
Amean 4 150.54 ( 0.00%) 137.51 * 8.66%*
Amean 8 252.53 ( 0.00%) 242.24 * 4.08%*
Amean 16 454.13 ( 0.00%) 439.08 * 3.31%*
Amean 32 835.24 ( 0.00%) 829.74 * 0.66%*
Amean 64 1740.59 ( 0.00%) 1686.73 * 3.09%*
Performance and cache flush behaviour is restored to pre-regression
levels.
As such, we can now consider the async cache flush mechanism an
unnecessary exercise in premature optimisation and hence we can
now remove it and the infrastructure it requires completely.
Fixes: bad77c375e ("xfs: CIL checkpoint flushes caches unconditionally")
Reported-and-tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Pass the block_device that we plan to use this bio for and the
operation to bio_init to optimize the assignment. A NULL block_device
can be passed, both for the passthrough case on a raw request_queue and
to temporarily avoid refactoring some nasty code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220124091107.642561-19-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the block_device and operation that we plan to use this bio for to
bio_alloc to optimize the assignment. NULL/0 can be passed, both for the
passthrough case on a raw request_queue and to temporarily avoid
refactoring some nasty code.
Also move the gfp_mask argument after the nr_vecs argument for a much
more logical calling convention matching what most of the kernel does.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220124091107.642561-18-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The new checkpoint cache flush mechanism requires us to issue an
unconditional cache flush before we start a new checkpoint. We don't
want to block for this if we can help it, and we have a fair chunk
of CPU work to do between starting the checkpoint and issuing the
first journal IO.
Hence it makes sense to amortise the latency cost of the cache flush
by issuing it asynchronously and then waiting for it only when we
need to issue the first IO in the transaction.
To do this, we need async cache flush primitives to submit the cache
flush bio and to wait on it. The block layer has no such primitives
for filesystems, so roll our own for the moment.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
It's often inconvenient to use BIO_MAX_PAGES due to min() requiring the
sign to be the same. Introduce bio_max_segs() and change BIO_MAX_PAGES to
be unsigned to make it easier for the users.
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We need to chain the earlier bios to the later ones, so that
submit_bio_wait waits on the bio that all the completions are
dispatched to.
Fixes: 6ad5b3255b ("xfs: use bios directly to read and write the log recovery buffers")
Reported-by: Dave Chinner <david@fromorbit.com>
Tested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
The xfs_buf structure is basically used as a glorified container for
a memory allocation in the log recovery code. Replace it with a
call to kmem_alloc_large and a simple abstraction to read into or
write from it synchronously using chained bios.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Linus Torvalds
Dave Chinner
Christoph Hellwig
Matthew Wilcox (Oracle)