Making sure that struct fd instances are destroyed in the same
scope where they'd been created, getting rid of reassignments
and passing them by reference, converting to CLASS(fd{,_pos,_raw}).
We are getting very close to having the memory safety of that stuff
trivial to verify.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull 'struct fd' class updates from Al Viro:
"The bulk of struct fd memory safety stuff
Making sure that struct fd instances are destroyed in the same scope
where they'd been created, getting rid of reassignments and passing
them by reference, converting to CLASS(fd{,_pos,_raw}).
We are getting very close to having the memory safety of that stuff
trivial to verify"
* tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits)
deal with the last remaing boolean uses of fd_file()
css_set_fork(): switch to CLASS(fd_raw, ...)
memcg_write_event_control(): switch to CLASS(fd)
assorted variants of irqfd setup: convert to CLASS(fd)
do_pollfd(): convert to CLASS(fd)
convert do_select()
convert vfs_dedupe_file_range().
convert cifs_ioctl_copychunk()
convert media_request_get_by_fd()
convert spu_run(2)
switch spufs_calls_{get,put}() to CLASS() use
convert cachestat(2)
convert do_preadv()/do_pwritev()
fdget(), more trivial conversions
fdget(), trivial conversions
privcmd_ioeventfd_assign(): don't open-code eventfd_ctx_fdget()
o2hb_region_dev_store(): avoid goto around fdget()/fdput()
introduce "fd_pos" class, convert fdget_pos() users to it.
fdget_raw() users: switch to CLASS(fd_raw)
convert vmsplice() to CLASS(fd)
...
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Merge tag 'vfs-6.13.untorn.writes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs untorn write support from Christian Brauner:
"An atomic write is a write issed with torn-write protection. This
means for a power failure or any hardware failure all or none of the
data from the write will be stored, never a mix of old and new data.
This work is already supported for block devices. If a block device is
opened with O_DIRECT and the block device supports atomic write, then
FMODE_CAN_ATOMIC_WRITE is added to the file of the opened block
device.
This contains the work to expand atomic write support to filesystems,
specifically ext4 and XFS. Currently, only support for writing exactly
one filesystem block atomically is added.
Since it's now possible to have filesystem block size > page size for
XFS, it's possible to write 4K+ blocks atomically on x86"
* tag 'vfs-6.13.untorn.writes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
iomap: drop an obsolete comment in iomap_dio_bio_iter
ext4: Do not fallback to buffered-io for DIO atomic write
ext4: Support setting FMODE_CAN_ATOMIC_WRITE
ext4: Check for atomic writes support in write iter
ext4: Add statx support for atomic writes
xfs: Support setting FMODE_CAN_ATOMIC_WRITE
xfs: Validate atomic writes
xfs: Support atomic write for statx
fs: iomap: Atomic write support
fs: Export generic_atomic_write_valid()
block: Add bdev atomic write limits helpers
fs/block: Check for IOCB_DIRECT in generic_atomic_write_valid()
block/fs: Pass an iocb to generic_atomic_write_valid()
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Merge tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs multigrain timestamps from Christian Brauner:
"This is another try at implementing multigrain timestamps. This time
with significant help from the timekeeping maintainers to reduce the
performance impact.
Thomas provided a base branch that contains the required timekeeping
interfaces for the VFS. It serves as the base for the multi-grain
timestamp work:
- Multigrain timestamps allow the kernel to use fine-grained
timestamps when an inode's attributes is being actively observed
via ->getattr(). With this support, it's possible for a file to get
a fine-grained timestamp, and another modified after it to get a
coarse-grained stamp that is earlier than the fine-grained time. If
this happens then the files can appear to have been modified in
reverse order, which breaks VFS ordering guarantees.
To prevent this, a floor value is maintained for multigrain
timestamps. Whenever a fine-grained timestamp is handed out, record
it, and when later coarse-grained stamps are handed out, ensure
they are not earlier than that value. If the coarse-grained
timestamp is earlier than the fine-grained floor, return the floor
value instead.
The timekeeper changes add a static singleton atomic64_t into
timekeeper.c that is used to keep track of the latest fine-grained
time ever handed out. This is tracked as a monotonic ktime_t value
to ensure that it isn't affected by clock jumps. Because it is
updated at different times than the rest of the timekeeper object,
the floor value is managed independently of the timekeeper via a
cmpxchg() operation, and sits on its own cacheline.
Two new public timekeeper interfaces are added:
(1) ktime_get_coarse_real_ts64_mg() fills a timespec64 with the
later of the coarse-grained clock and the floor time
(2) ktime_get_real_ts64_mg() gets the fine-grained clock value,
and tries to swap it into the floor. A timespec64 is filled
with the result.
- The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around
1 per jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting
via NFSv3, which relies on timestamps to validate caches. A lot of
changes can happen in a jiffy, so timestamps aren't sufficient to
help the client decide when to invalidate the cache. Even with
NFSv4, a lot of exported filesystems don't properly support a
change attribute and are subject to the same problems with
timestamp granularity. Other applications have similar issues with
timestamps (e.g backup applications).
If we were to always use fine-grained timestamps, that would
improve the situation, but that becomes rather expensive, as the
underlying filesystem would have to log a lot more metadata
updates.
This adds a way to only use fine-grained timestamps when they are
being actively queried. Use the (unused) top bit in
inode->i_ctime_nsec as a flag that indicates whether the current
timestamps have been queried via stat() or the like. When it's set,
we allow the kernel to use a fine-grained timestamp iff it's
necessary to make the ctime show a different value.
This solves the problem of being able to distinguish the timestamp
between updates, but introduces a new problem: it's now possible
for a file being changed to get a fine-grained timestamp. A file
that is altered just a bit later can then get a coarse-grained one
that appears older than the earlier fine-grained time. This
violates timestamp ordering guarantees.
This is where the earlier mentioned timkeeping interfaces help. A
global monotonic atomic64_t value is kept that acts as a timestamp
floor. When we go to stamp a file, we first get the latter of the
current floor value and the current coarse-grained time. If the
inode ctime hasn't been queried then we just attempt to stamp it
with that value.
If it has been queried, then first see whether the current coarse
time is later than the existing ctime. If it is, then we accept
that value. If it isn't, then we get a fine-grained time and try to
swap that into the global floor. Whether that succeeds or fails, we
take the resulting floor time, convert it to realtime and try to
swap that into the ctime.
We take the result of the ctime swap whether it succeeds or fails,
since either is just as valid.
Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same
floor value as multigrain filesystems)"
* tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: reduce pointer chasing in is_mgtime() test
tmpfs: add support for multigrain timestamps
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
Documentation: add a new file documenting multigrain timestamps
fs: add percpu counters for significant multigrain timestamp events
fs: tracepoints around multigrain timestamp events
fs: handle delegated timestamps in setattr_copy_mgtime
timekeeping: Add percpu counter for tracking floor swap events
timekeeping: Add interfaces for handling timestamps with a floor value
fs: have setattr_copy handle multigrain timestamps appropriately
fs: add infrastructure for multigrain timestamps
Set FMODE_CAN_ATOMIC_WRITE flag if we can atomic write for that inode.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> #On ppc64
Validate that an atomic write adheres to length/offset rules. Currently
we can only write a single FS block.
For an IOCB with IOCB_ATOMIC set to get as far as xfs_file_write_iter(),
FMODE_CAN_ATOMIC_WRITE will need to be set for the file; for this,
ATOMICWRITES flags would also need to be set for the inode.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Support providing info on atomic write unit min and max for an inode.
For simplicity, currently we limit the min at the FS block size. As for
max, we limit also at FS block size, as there is no current method to
guarantee extent alignment or granularity for regular files.
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
all failure exits prior to fdget() leave the scope, all matching fdput()
are immediately followed by leaving the scope.
[xfs_ioc_commit_range() chunk moved here as well]
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
XFS_IOC_FD_TO_HANDLE can grab a reference to copied ->f_path and
let the file go; results in simpler control flow - cleanup is
the same for both "by descriptor" and "by pathname" cases.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fix a sysbot reported crash on filestreams
* Reduce cpu time spent searching for extents in
a very fragmented FS
* Check for delayed allocations before setting extsize
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Merge tag 'xfs-6.12-fixes-6' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs fixes from Carlos Maiolino:
- fix a sysbot reported crash on filestreams
- Reduce cpu time spent searching for extents in a very fragmented FS
- Check for delayed allocations before setting extsize
* tag 'xfs-6.12-fixes-6' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: streamline xfs_filestream_pick_ag
xfs: fix finding a last resort AG in xfs_filestream_pick_ag
xfs: Reduce unnecessary searches when searching for the best extents
xfs: Check for delayed allocations before setting extsize
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Merge tag 'vfs-6.12-rc6.iomap' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull iomap fixes from Christian Brauner:
"Fixes for iomap to prevent data corruption bugs in the fallocate
unshare range implementation of fsdax and a small cleanup to turn
iomap_want_unshare_iter() into an inline function"
* tag 'vfs-6.12-rc6.iomap' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
iomap: turn iomap_want_unshare_iter into an inline function
fsdax: dax_unshare_iter needs to copy entire blocks
fsdax: remove zeroing code from dax_unshare_iter
iomap: share iomap_unshare_iter predicate code with fsdax
xfs: don't allocate COW extents when unsharing a hole
Directly return the error from xfs_bmap_longest_free_extent instead
of breaking from the loop and handling it there, and use a done
label to directly jump to the exist when we found a suitable perag
structure to reduce the indentation level and pag/max_pag check
complexity in the tail of the function.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
When the main loop in xfs_filestream_pick_ag fails to find a suitable
AG it tries to just pick the online AG. But the loop for that uses
args->pag as loop iterator while the later code expects pag to be
set. Fix this by reusing the max_pag case for this last resort, and
also add a check for impossible case of no AG just to make sure that
the uninitialized pag doesn't even escape in theory.
Reported-by: syzbot+4125a3c514e3436a02e6@syzkaller.appspotmail.com
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: syzbot+4125a3c514e3436a02e6@syzkaller.appspotmail.com
Fixes: f8f1ed1ab3 ("xfs: return a referenced perag from filestreams allocator")
Cc: <stable@vger.kernel.org> # v6.3
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Recently, we found that the CPU spent a lot of time in
xfs_alloc_ag_vextent_size when the filesystem has millions of fragmented
spaces.
The reason is that we conducted much extra searching for extents that
could not yield a better result, and these searches would cost a lot of
time when there were millions of extents to search through. Even if we
get the same result length, we don't switch our choice to the new one,
so we can definitely terminate the search early.
Since the result length cannot exceed the found length, when the found
length equals the best result length we already have, we can conclude
the search.
We did a test in that filesystem:
[root@localhost ~]# xfs_db -c freesp /dev/vdb
from to extents blocks pct
1 1 215 215 0.01
2 3 994476 1988952 99.99
Before this patch:
0) | xfs_alloc_ag_vextent_size [xfs]() {
0) * 15597.94 us | }
After this patch:
0) | xfs_alloc_ag_vextent_size [xfs]() {
0) 19.176 us | }
Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Extsize should only be allowed to be set on files with no data in it.
For this, we check if the files have extents but miss to check if
delayed extents are present. This patch adds that check.
While we are at it, also refactor this check into a helper since
it's used in some other places as well like xfs_inactive() or
xfs_ioctl_setattr_xflags()
**Without the patch (SUCCEEDS)**
$ xfs_io -c 'open -f testfile' -c 'pwrite 0 1024' -c 'extsize 65536'
wrote 1024/1024 bytes at offset 0
1 KiB, 1 ops; 0.0002 sec (4.628 MiB/sec and 4739.3365 ops/sec)
**With the patch (FAILS as expected)**
$ xfs_io -c 'open -f testfile' -c 'pwrite 0 1024' -c 'extsize 65536'
wrote 1024/1024 bytes at offset 0
1 KiB, 1 ops; 0.0002 sec (4.628 MiB/sec and 4739.3365 ops/sec)
xfs_io: FS_IOC_FSSETXATTR testfile: Invalid argument
Fixes: e94af02a9c ("[XFS] fix old xfs_setattr mis-merge from irix; mostly harmless esp if not using xfs rt")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Currently log recovery never updates the in-core perag values for the
last allocation group when they were grown by growfs. This leads to
btree record validation failures for the alloc, ialloc or finotbt
trees if a transaction references this new space.
Found by Brian's new growfs recovery stress test.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
__GFP_RETRY_MAYFAIL increases the likelyhood of allocations to fail,
which isn't really helpful during log recovery. Remove the flag and
stick to the default GFP_KERNEL policies.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
XFS currently does not support reducing the agcount, so error out if
a logged sb buffer tries to shrink the agcount.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Primary superblock buffers that change the file system geometry after a
growfs operation can affect the operation of later CIL checkpoints that
make use of the newly added space and allocation groups.
Apply the changes to the in-memory structures as part of recovery pass 2,
to ensure recovery works fine for such cases.
In the future we should apply the logic to other updates such as features
bits as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
There is no good reason to have two different routines for freeing perag
structures for the unmount and error cases. Add two arguments to specify
the range of AGs to free to xfs_free_perag, and use that to replace
xfs_free_unused_perag_range.
The addition RCU grace period for the error case is harmless, and the
extra check for the AG to actually exist is not required now that the
callers pass the exact known allocated range.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Currently only the new agcount is passed to xfs_initialize_perag, which
requires lookups of existing AGs to skip them and complicates error
handling. Also pass the previous agcount so that the range that
xfs_initialize_perag operates on is exactly defined. That way the
extra lookups can be avoided, and error handling can clean up the
exact range from the old count to the last added perag structure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Fix a minor bug where we fail repairs on metadata files that do not have
attr forks because xrep_metadata_inode_subtype doesn't filter ENOENT.
Cc: stable@vger.kernel.org # v6.8
Fixes: 5a8e07e799 ("xfs: repair the inode core and forks of a metadata inode")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
When ->iomap_end is called on a short write to the COW fork it needs to
punch stale delalloc data from the COW fork and not the data fork.
Ensure that IOMAP_F_NEW is set for new COW fork allocations in
xfs_buffered_write_iomap_begin, and then use the IOMAP_F_SHARED flag
in xfs_buffered_write_delalloc_punch to decide which fork to punch.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Change to always set xfs_buffered_write_iomap_begin for COW fork
allocations even if they don't overlap existing data fork extents,
which will allow the iomap_end callback to detect if it has to punch
stale delalloc blocks from the COW fork instead of the data fork. It
also means we sample the sequence counter for both the data and the COW
fork when writing to the COW fork, which ensures we properly revalidate
when only COW fork changes happens.
This is essentially a revert of commit 72a048c105 ("xfs: only set
IOMAP_F_SHARED when providing a srcmap to a write"). This is fine because
the problem that the commit fixed has now been dealt with in iomap by
only looking at the actual srcmap and not the fallback to the write
iomap.
Note that the direct I/O path was never changed and has always set
IOMAP_F_SHARED for all COW fork allocations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Introduce a local iomap_flags variable so that the code allocating new
delalloc blocks in the data fork can fall through to the found_imap
label and reuse the code to unlock and fill the iomap.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_buffered_write_iomap_begin can also create delallocate reservations
that need cleaning up, prepare for that by adding support for the COW
fork in xfs_bmap_punch_delalloc_range.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
All XFS callers of iomap_zero_range and iomap_file_unshare already hold
invalidate_lock, so we can't take it again in
iomap_file_buffered_write_punch_delalloc.
Use the passed in flags argument to detect if we're called from a zero
or unshare operation and don't take the lock again in this case.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_file_write_zero_eof is the only caller of xfs_zero_range that does
not take XFS_MMAPLOCK_EXCL (aka the invalidate lock). Currently that
is actually the right thing, as an error in the iomap zeroing code will
also take the invalidate_lock to clean up, but to fix that deadlock we
need a consistent locking pattern first.
The only extra thing that XFS_MMAPLOCK_EXCL will lock out are read
pagefaults, which isn't really needed here, but also not actively
harmful.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Split a helper from xfs_file_write_checks that just deal with the
post-EOF zeroing to keep the code readable.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
XFS (which currently is the only user of iomap_write_delalloc_release)
already holds invalidate_lock for most zeroing operations. To be able
to avoid a deadlock it needs to stop taking the lock, but doing so
in iomap would leak XFS locking details into iomap.
To avoid this require the caller to hold invalidate_lock when calling
iomap_write_delalloc_release instead of taking it there.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Currently iomap_file_buffered_write_punch_delalloc can be called from
XFS either with the invalidate lock held or not. To fix this while
keeping the locking in the file system and not the iomap library
code we'll need to life the locking up into the file system.
To prepare for that, open code iomap_file_buffered_write_punch_delalloc
in the only caller, and instead export iomap_write_delalloc_release.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
The variable declaration in this function predates the merge of the
nrext64 (aka 64-bit extent counters) feature, which means that the
variable declaration type is insufficient to avoid an integer overflow.
Fix that by redeclaring the variable to be xfs_extnum_t.
Coverity-id: 1630958
Fixes: 8f71bede8e ("xfs: repair inode fork block mapping data structures")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Jeff Layton <jlayton@kernel.org> says:
The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around 1
per jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide when to invalidate the cache. Even with NFSv4, a lot of
exported filesystems don't properly support a change attribute and are
subject to the same problems with timestamp granularity. Other
applications have similar issues with timestamps (e.g backup
applications).
If we were to always use fine-grained timestamps, that would improve the
situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.
What we need is a way to only use fine-grained timestamps when they are
being actively queried. Use the (unused) top bit in inode->i_ctime_nsec
as a flag that indicates whether the current timestamps have been
queried via stat() or the like. When it's set, we allow the kernel to
use a fine-grained timestamp iff it's necessary to make the ctime show
a different value.
This solves the problem of being able to distinguish the timestamp
between updates, but introduces a new problem: it's now possible for a
file being changed to get a fine-grained timestamp. A file that is
altered just a bit later can then get a coarse-grained one that appears
older than the earlier fine-grained time. This violates timestamp
ordering guarantees.
To remedy this, keep a global monotonic atomic64_t value that acts as a
timestamp floor. When we go to stamp a file, we first get the latter of
the current floor value and the current coarse-grained time. If the
inode ctime hasn't been queried then we just attempt to stamp it with
that value.
If it has been queried, then first see whether the current coarse time
is later than the existing ctime. If it is, then we accept that value.
If it isn't, then we get a fine-grained time and try to swap that into
the global floor. Whether that succeeds or fails, we take the resulting
floor time, convert it to realtime and try to swap that into the ctime.
We take the result of the ctime swap whether it succeeds or fails, since
either is just as valid.
Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same floor
value as multigrain filesystems).
* patches from https://lore.kernel.org/r/20241002-mgtime-v10-0-d1c4717f5284@kernel.org:
tmpfs: add support for multigrain timestamps
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
Documentation: add a new file documenting multigrain timestamps
fs: add percpu counters for significant multigrain timestamp events
fs: tracepoints around multigrain timestamp events
fs: handle delegated timestamps in setattr_copy_mgtime
fs: have setattr_copy handle multigrain timestamps appropriately
fs: add infrastructure for multigrain timestamps
Link: https://lore.kernel.org/r/20241002-mgtime-v10-0-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Enable multigrain timestamps, which should ensure that there is an
apparent change to the timestamp whenever it has been written after
being actively observed via getattr.
Also, anytime the mtime changes, the ctime must also change, and those
are now the only two options for xfs_trans_ichgtime. Have that function
unconditionally bump the ctime, and ASSERT that XFS_ICHGTIME_CHG is
always set.
Finally, stop setting STATX_CHANGE_COOKIE in getattr, since the ctime
should give us better semantics now.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-9-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Fix a typo in comments.
Signed-off-by: Andrew Kreimer <algonell@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
fallocate unshare mode explicitly breaks extent sharing. When a
command completes, it checks the data fork for any remaining shared
extents to determine whether the reflink inode flag and COW fork
preallocation can be removed. This logic doesn't consider in-core
pagecache and I/O state, however, which means we can unsafely remove
COW fork blocks that are still needed under certain conditions.
For example, consider the following command sequence:
xfs_io -fc "pwrite 0 1k" -c "reflink <file> 0 256k 1k" \
-c "pwrite 0 32k" -c "funshare 0 1k" <file>
This allocates a data block at offset 0, shares it, and then
overwrites it with a larger buffered write. The overwrite triggers
COW fork preallocation, 32 blocks by default, which maps the entire
32k write to delalloc in the COW fork. All but the shared block at
offset 0 remains hole mapped in the data fork. The unshare command
redirties and flushes the folio at offset 0, removing the only
shared extent from the inode. Since the inode no longer maps shared
extents, unshare purges the COW fork before the remaining 28k may
have written back.
This leaves dirty pagecache backed by holes, which writeback quietly
skips, thus leaving clean, non-zeroed pagecache over holes in the
file. To verify, fiemap shows holes in the first 32k of the file and
reads return different data across a remount:
$ xfs_io -c "fiemap -v" <file>
<file>:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
...
1: [8..511]: hole 504
...
$ xfs_io -c "pread -v 4k 8" <file>
00001000: cd cd cd cd cd cd cd cd ........
$ umount <mnt>; mount <dev> <mnt>
$ xfs_io -c "pread -v 4k 8" <file>
00001000: 00 00 00 00 00 00 00 00 ........
To avoid this problem, make unshare follow the same rules used for
background cowblock scanning and never purge the COW fork for inodes
with dirty pagecache or in-flight I/O.
Fixes: 46afb0628b ("xfs: only flush the unshared range in xfs_reflink_unshare")
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
It doesn't make sense to allocate a COW extent when unsharing a hole
because holes cannot be shared.
Fixes: 1f1397b721 ("xfs: don't allocate into the data fork for an unshare request")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/172796813277.1131942.5486112889531210260.stgit@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
The background blockgc scanner runs on a 5m interval by default and
trims preallocation (post-eof and cow fork) from inodes that are
otherwise idle. Idle effectively means that iolock can be acquired
without blocking and that the inode has no dirty pagecache or I/O in
flight.
This simple mechanism and heuristic has worked fairly well for
post-eof speculative preallocations. Support for reflink and COW
fork preallocations came sometime later and plugged into the same
mechanism, with similar heuristics. Some recent testing has shown
that COW fork preallocation may be notably more sensitive to blockgc
processing than post-eof preallocation, however.
For example, consider an 8GB reflinked file with a COW extent size
hint of 1MB. A worst case fully randomized overwrite of this file
results in ~8k extents of an average size of ~1MB. If the same
workload is interrupted a couple times for blockgc processing
(assuming the file goes idle), the resulting extent count explodes
to over 100k extents with an average size <100kB. This is
significantly worse than ideal and essentially defeats the COW
extent size hint mechanism.
While this particular test is instrumented, it reflects a fairly
reasonable pattern in practice where random I/Os might spread out
over a large period of time with varying periods of (in)activity.
For example, consider a cloned disk image file for a VM or container
with long uptime and variable and bursty usage. A background blockgc
scan that races and processes the image file when it happens to be
clean and idle can have a significant effect on the future
fragmentation level of the file, even when still in use.
To help combat this, update the heuristic to skip cowblocks inodes
that are currently opened for write access during non-sync blockgc
scans. This allows COW fork preallocations to persist for as long as
possible unless otherwise needed for functional purposes (i.e. a
sync scan), the file is idle and closed, or the inode is being
evicted from cache. While here, update the comments to help
distinguish performance oriented heuristics from the logic that
exists to maintain functional correctness.
Suggested-by: Darrick Wong <djwong@kernel.org>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Currently the debug-only xfs_bmap_exact_minlen_extent_alloc allocation
variant fails to drop into the lowmode last resort allocator, and
thus can sometimes fail allocations for which the caller has a
transaction block reservation.
Fix this by using xfs_bmap_btalloc_low_space to do the actual allocation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_bmap_exact_minlen_extent_alloc duplicates the args setup in
xfs_bmap_btalloc. Switch to call it from xfs_bmap_btalloc after
doing the basic setup.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Exact minlen allocations only exist as an error injection tool for debug
builds. Currently this is implemented using ifdefs, which means the code
isn't even compiled for non-XFS_DEBUG builds. Enhance the compile test
coverage by always building the code and use the compilers' dead code
elimination to remove it from the generated binary instead.
The only downside is that the alloc_minlen_only field is unconditionally
added to struct xfs_alloc_args now, but by moving it around and packing
it tightly this doesn't actually increase the size of the structure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Userdata and metadata allocations end up in the same allocation helpers.
Remove the separate xfs_bmap_alloc_userdata function to make this more
clear.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Just like xfs_attr3_leaf_split, xfs_attr_node_try_addname can return
-ENOSPC both for an actual failure to allocate a disk block, but also
to signal the caller to convert the format of the attr fork. Use magic
1 to ask for the conversion here as well.
Note that unlike the similar issue in xfs_attr3_leaf_split, this one was
only found by code review.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_attr3_leaf_split propagates the need for an extra btree split as
-ENOSPC to it's only caller, but the same return value can also be
returned from xfs_da_grow_inode when it fails to find free space.
Distinguish the two cases by returning 1 for the extra split case instead
of overloading -ENOSPC.
This can be triggered relatively easily with the pending realtime group
support and a file system with a lot of small zones that use metadata
space on the main device. In this case every about 5-10th run of
xfs/538 runs into the following assert:
ASSERT(oldblk->magic == XFS_ATTR_LEAF_MAGIC);
in xfs_attr3_leaf_split caused by an allocation failure. Note that
the allocation failure is caused by another bug that will be fixed
subsequently, but this commit at least sorts out the error handling.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_attr3_leaf_add only has two potential return values, indicating if the
entry could be added or not. Replace the errno return with a bool so that
ENOSPC from it can't easily be confused with a real ENOSPC.
Remove the return value from the xfs_attr3_leaf_add_work helper entirely,
as it always return 0.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_attr_leaf_try_add is only called by xfs_attr_leaf_addname, and
merging the two will simplify a following error handling fix.
To facilitate this move the remote block state save/restore helpers up in
the file so that they don't need forward declarations now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Use !try_cmpxchg instead of cmpxchg (*ptr, old, new) != old in
xlog_cil_insert_pcp_aggregate(). x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after cmpxchg.
Also, try_cmpxchg implicitly assigns old *ptr value to "old" when
cmpxchg fails. There is no need to re-read the value in the loop.
Note that the value from *ptr should be read using READ_ONCE to
prevent the compiler from merging, refetching or reordering the read.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Chandan Babu R <chandan.babu@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Replace a comma between expression statements by a semicolon.
Signed-off-by: Yan Zhen <yanzhen@vivo.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
The definition of xfs_attr_use_log_assist() has been removed since
commit d9c61ccb3b ("xfs: move xfs_attr_use_log_assist out of xfs_log.c").
So, Remove the empty declartion in header files.
Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.
auto-generated by the following:
for i in `git grep -l -w asm/unaligned.h`; do
sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h
