When a buffer is freed either by LRU eviction or because it is unset,
the lockref is marked as dead instantly, which prevents the buffer from
being used after finding it in the buffer hash in xfs_buf_lookup and
xfs_buf_find_insert. But the latter will then not add the new buffer to
the hash because it already found an existing buffer.
Fix this using in two places: Remove the buffer from the hash before
marking the lockref dead so that that no buffer with a dead lockref can
be found in the hash, but if we find one in xfs_buf_find_insert due to
store reordering, handle this case correctly instead of returning an
unhashed buffer.
Fixes: 67fe430397 ("xfs: don't keep a reference for buffers on the LRU")
Reported-by: Andrey Albershteyn <aalbersh@redhat.com>
Reported-by: Carlos Maiolino <cem@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andrey Albershteyn <aalbersh@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
In the error path, call fs_put_dax() to drop the DAX
device reference.
Fixes: 6f643c57d5 ("xfs: implement ->notify_failure() for XFS")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <lihaoxiang@isrc.iscas.ac.cn>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
XFS buffers are added to the LRU when they are unused, but are only
removed from the LRU lazily when the LRU list scan finds a used buffer.
So far this only happen when the LRU counter hits 0, which is suboptimal
as buffers that were added to the LRU, but are in use again still consume
LRU scanning resources and are aged while actually in use.
Fix this by checking for in-use buffers and removing the from the LRU
before decrementing the LRU counter.
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 per-AG buffer hashes were added when all buffer lookups took a
per-hash look. Since then we've made lookups entirely lockless and
removed the need for a hash-wide lock for inserts and removals as
well. With this there is no need to sharding the hash, so reduce the
used resources by using a per-buftarg hash for all buftargs.
Long after writing this initially, syzbot found a problem in the buffer
cache teardown order, which this happens to fix as well by doing the
entire buffer cache teardown in one places instead of splitting it
between destroying the buftarg and the perag structures.
Link: https://lore.kernel.org/linux-xfs/aLeUdemAZ5wmtZel@dread.disaster.area/
Reported-by: syzbot+0391d34e801643e2809b@syzkaller.appspotmail.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: syzbot+0391d34e801643e2809b@syzkaller.appspotmail.com
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
The lockref structure allows incrementing/decrementing counters like
an atomic_t for the fast path, while still allowing complex slow path
operations as if the counter was protected by a lock. The only slow
path operations that actually need to take the lock are the final
put, LRU evictions and marking a buffer stale.
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 the buffer cache adds a reference to b_hold for buffers that
are on the LRU. This seems to go all the way back and allows releasing
buffers from the LRU using xfs_buf_rele. But it makes xfs_buf_rele
really complicated in differs from how other LRUs are implemented in
Linux.
Switch to not having a reference for buffers in the LRU, and use a
separate negative hold value to mark buffers as dead. This simplifies
xfs_buf_rele, which now just deal with the last "real" reference,
and prepares for using the lockref primitive.
This also removes the b_lock protection for removing buffers from the
buffer hash. This is the desired outcome because the rhashtable is
fully internally synchronized, and previously the lock was mostly
held out of ordering constrains in xfs_buf_rele_cached.
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>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
The xfs.h header conflicts with the public xfs.h in xfsprogs, leading
to a spurious difference in all shared libxfs files that have to
include libxfs_priv.h in userspace. Directly include xfs_platform.h so
that we can add a header of the same name to xfsprogs and remove this
major annoyance for the shared code.
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_daddr_t is a signed type, which means that xfs_buf_map_verify is
using a signed comparison. This causes problems if bt_nr_sectors is
never overridden (e.g. in the case of an xfbtree for rmap btree repairs)
because even daddr 0 can't pass the verifier test in that case.
Define an explicit max constant and set the initial bt_nr_sectors to a
positive value.
Found by xfs/422.
Cc: stable@vger.kernel.org # v6.18-rc1
Fixes: 42852fe57c ("xfs: track the number of blocks in each buftarg")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Add a bt_nr_sectors to track the number of sector in each buftarg, and
replace the check that hard codes sb_dblock in xfs_buf_map_verify with
this new value so that it is correct for non-ddev buftargs. The
RT buftarg only has a superblock in the first block, so it is unlikely
to trigger this, or are we likely to ever have enough blocks in the
in-memory buftargs, but we might as well get the check right.
Fixes: 10616b806d ("xfs: fix _xfs_buf_find oops on blocks beyond the filesystem end")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Don't pass expr to XFS_TEST_ERROR. Most calls pass a constant false,
and the places that do pass an expression become cleaner by moving it
out.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
And use bt_file for both bdev and shmem backed buftargs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
The extra bdev_ is weird, so drop it. Also improve the comment to make
it clear these are the hardware limits.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
This extra call is not needed as xfs_alloc_buftarg already calls
sync_blockdev.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
On shutdown when quotas are enabled, the shutdown can deadlock
trying to unpin the dquot buffer buf_log_item like so:
[ 3319.483590] task:kworker/20:0H state:D stack:14360 pid:1962230 tgid:1962230 ppid:2 task_flags:0x4208060 flags:0x00004000
[ 3319.493966] Workqueue: xfs-log/dm-6 xlog_ioend_work
[ 3319.498458] Call Trace:
[ 3319.500800] <TASK>
[ 3319.502809] __schedule+0x699/0xb70
[ 3319.512672] schedule+0x64/0xd0
[ 3319.515573] schedule_timeout+0x30/0xf0
[ 3319.528125] __down_common+0xc3/0x200
[ 3319.531488] __down+0x1d/0x30
[ 3319.534186] down+0x48/0x50
[ 3319.540501] xfs_buf_lock+0x3d/0xe0
[ 3319.543609] xfs_buf_item_unpin+0x85/0x1b0
[ 3319.547248] xlog_cil_committed+0x289/0x570
[ 3319.571411] xlog_cil_process_committed+0x6d/0x90
[ 3319.575590] xlog_state_shutdown_callbacks+0x52/0x110
[ 3319.580017] xlog_force_shutdown+0x169/0x1a0
[ 3319.583780] xlog_ioend_work+0x7c/0xb0
[ 3319.587049] process_scheduled_works+0x1d6/0x400
[ 3319.591127] worker_thread+0x202/0x2e0
[ 3319.594452] kthread+0x20c/0x240
The CIL push has seen the deadlock, so it has aborted the push and
is running CIL checkpoint completion to abort all the items in the
checkpoint. This calls ->iop_unpin(remove = true) to clean up the
log items in the checkpoint.
When a buffer log item is unpined like this, it needs to lock the
buffer to run io completion to correctly fail the buffer and run all
the required completions to fail attached log items as well. In this
case, the attempt to lock the buffer on unpin is hanging because the
buffer is already locked.
I suspected a leaked XFS_BLI_HOLD state because of XFS_BLI_STALE
handling changes I was testing, so I went looking for
pin events on HOLD buffers and unpin events on locked buffer. That
isolated this one buffer with these two events:
xfs_buf_item_pin: dev 251:6 daddr 0xa910 bbcount 0x2 hold 2 pincount 0 lock 0 flags DONE|KMEM recur 0 refcount 1 bliflags HOLD|DIRTY|LOGGED liflags DIRTY
....
xfs_buf_item_unpin: dev 251:6 daddr 0xa910 bbcount 0x2 hold 4 pincount 1 lock 0 flags DONE|KMEM recur 0 refcount 1 bliflags DIRTY liflags ABORTED
Firstly, bbcount = 0x2, which means it is not a single sector
structure. That rules out every xfs_trans_bhold() case except one:
dquot buffers.
Then hung task dumping gave this trace:
[ 3197.312078] task:fsync-tester state:D stack:12080 pid:2051125 tgid:2051125 ppid:1643233 task_flags:0x400000 flags:0x00004002
[ 3197.323007] Call Trace:
[ 3197.325581] <TASK>
[ 3197.327727] __schedule+0x699/0xb70
[ 3197.334582] schedule+0x64/0xd0
[ 3197.337672] schedule_timeout+0x30/0xf0
[ 3197.350139] wait_for_completion+0xbd/0x180
[ 3197.354235] __flush_workqueue+0xef/0x4e0
[ 3197.362229] xlog_cil_force_seq+0xa0/0x300
[ 3197.374447] xfs_log_force+0x77/0x230
[ 3197.378015] xfs_qm_dqunpin_wait+0x49/0xf0
[ 3197.382010] xfs_qm_dqflush+0x55/0x460
[ 3197.385663] xfs_qm_dquot_isolate+0x29e/0x4d0
[ 3197.389977] __list_lru_walk_one+0x141/0x220
[ 3197.398867] list_lru_walk_one+0x10/0x20
[ 3197.402713] xfs_qm_shrink_scan+0x6a/0x100
[ 3197.406699] do_shrink_slab+0x18a/0x350
[ 3197.410512] shrink_slab+0xf7/0x430
[ 3197.413967] drop_slab+0x97/0xf0
[ 3197.417121] drop_caches_sysctl_handler+0x59/0xc0
[ 3197.421654] proc_sys_call_handler+0x18b/0x280
[ 3197.426050] proc_sys_write+0x13/0x20
[ 3197.429750] vfs_write+0x2b8/0x3e0
[ 3197.438532] ksys_write+0x7e/0xf0
[ 3197.441742] __x64_sys_write+0x1b/0x30
[ 3197.445363] x64_sys_call+0x2c72/0x2f60
[ 3197.449044] do_syscall_64+0x6c/0x140
[ 3197.456341] entry_SYSCALL_64_after_hwframe+0x76/0x7e
Yup, another test run by check-parallel is running drop_caches
concurrently and the dquot shrinker for the hung filesystem is
running. That's trying to flush a dirty dquot from reclaim context,
and it waiting on a log force to complete. xfs_qm_dqflush is called
with the dquot buffer held locked, and so we've called
xfs_log_force() with that buffer locked.
Now the log force is waiting for a workqueue flush to complete, and
that workqueue flush is waiting of CIL checkpoint processing to
finish.
The CIL checkpoint processing is aborting all the log items it has,
and that requires locking aborted buffers to cancel them.
Now, normally this isn't a problem if we are issuing a log force
to unpin an object, because the ->iop_unpin() method wakes pin
waiters first. That results in the pin waiter finishing off whatever
it was doing, dropping the lock and then xfs_buf_item_unpin() can
lock the buffer and fail it.
However, xfs_qm_dqflush() is waiting on the -dquot- unpin event, not
the dquot buffer unpin event, and so it never gets woken and so does
not drop the buffer lock.
Inodes do not have this problem, as they can only be written from
one spot (->iop_push) whilst dquots can be written from multiple
places (memory reclaim, ->iop_push, xfs_dq_dqpurge, and quotacheck).
The reason that the dquot buffer has an attached buffer log item is
that it has been recently allocated. Initialisation of the dquot
buffer logs the buffer directly, thereby pinning it in memory. We
then modify the dquot in a separate operation, and have memory
reclaim racing with a shutdown and we trigger this deadlock.
check-parallel reproduces this reliably on 1kB FSB filesystems with
quota enabled because it does all of these things concurrently
without having to explicitly write tests to exercise these corner
case conditions.
xfs_qm_dquot_logitem_push() doesn't have this deadlock because it
checks if the dquot is pinned before locking the dquot buffer and
skipping it if it is pinned. This means the xfs_qm_dqunpin_wait()
log force in xfs_qm_dqflush() never triggers and we unlock the
buffer safely allowing a concurrent shutdown to fail the buffer
appropriately.
xfs_qm_dqpurge() could have this problem as it is called from
quotacheck and we might have allocated dquot buffers when recording
the quota updates. This can be fixed by calling
xfs_qm_dqunpin_wait() before we lock the dquot buffer. Because we
hold the dquot locked, nothing will be able to add to the pin count
between the unpin_wait and the dqflush callout, so this now makes
xfs_qm_dqpurge() safe against this race.
xfs_qm_dquot_isolate() can also be fixed this same way but, quite
frankly, we shouldn't be doing IO in memory reclaim context. If the
dquot is pinned or dirty, simply rotate it and let memory reclaim
come back to it later, same as we do for inodes.
This then gets rid of the nasty issue in xfs_qm_flush_one() where
quotacheck writeback races with memory reclaim flushing the dquots.
We can lift xfs_qm_dqunpin_wait() up into this code, then get rid of
the "can't get the dqflush lock" buffer write to cycle the dqlfush
lock and enable it to be flushed again. checking if the dquot is
pinned and returning -EAGAIN so that the dquot walk will revisit the
dquot again later.
Finally, with xfs_qm_dqunpin_wait() lifted into all the callers,
we can remove it from the xfs_qm_dqflush() code.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Merge tag 'xfs-merge-6.16' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs updates from Carlos Maiolino:
- Atomic writes for XFS
- Remove experimental warnings for pNFS, scrub and parent pointers
* tag 'xfs-merge-6.16' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (26 commits)
xfs: add inode to zone caching for data placement
xfs: free the item in xfs_mru_cache_insert on failure
xfs: remove the EXPERIMENTAL warning for pNFS
xfs: remove some EXPERIMENTAL warnings
xfs: Remove deprecated xfs_bufd sysctl parameters
xfs: stop using set_blocksize
xfs: allow sysadmins to specify a maximum atomic write limit at mount time
xfs: update atomic write limits
xfs: add xfs_calc_atomic_write_unit_max()
xfs: add xfs_file_dio_write_atomic()
xfs: commit CoW-based atomic writes atomically
xfs: add large atomic writes checks in xfs_direct_write_iomap_begin()
xfs: add xfs_atomic_write_cow_iomap_begin()
xfs: refine atomic write size check in xfs_file_write_iter()
xfs: refactor xfs_reflink_end_cow_extent()
xfs: allow block allocator to take an alignment hint
xfs: ignore HW which cannot atomic write a single block
xfs: add helpers to compute transaction reservation for finishing intent items
xfs: add helpers to compute log item overhead
xfs: separate out setting buftarg atomic writes limits
...
XFS has its own buffer cache for metadata that uses submit_bio, which
means that it no longer uses the block device pagecache for anything.
Create a more lightweight helper that runs the blocksize checks and
flushes dirty data and use that instead. No more truncating the
pagecache because XFS does not use it or care about it.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Currently only HW which can write at least 1x block is supported.
For supporting atomic writes > 1x block, a CoW-based method will also be
used and this will not be resticted to using HW which can write >= 1x
block.
However for deciding if HW-based atomic writes can be used, we need to
start adding checks for write length < HW min, which complicates the
code. Indeed, a statx field similar to unit_max_opt should also be
added for this minimum, which is undesirable.
HW which can only write > 1x blocks would be uncommon and quite weird,
so let's just not support it.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Separate out setting buftarg atomic writes limits into a dedicated
function, xfs_configure_buftarg_atomic_writes(), to keep the specific
functionality self-contained.
For naming consistency, rename xfs_setsize_buftarg() ->
xfs_configure_buftarg().
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
[jpg: separate out from patch "xfs: ignore HW which ..."]
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
It's silly to call xfs_setsize_buftarg from xfs_alloc_buftarg with the
block device LBA size because we don't need to ask the block layer to
validate a geometry number that it provided us. Instead, set the
preliminary bt_meta_sector* fields to the LBA size in preparation for
reading the primary super.
However, we still want to flush and invalidate the pagecache for all
three block devices before we start reading metadata from those devices,
so call sync_blockdev() per bdev in xfs_alloc_buftarg().
This will enable a subsequent patch to validate hw atomic write geometry
against the filesystem geometry.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
[jpg: call sync_blockdev() from xfs_alloc_buftarg()]
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Convert the __bio_add_page(..., virt_to_page(), ...) pattern to the
bio_add_virt_nofail helper implementing it and use bio_add_vmalloc
to insulate xfs from the details of adding vmalloc memory to a bio.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20250507120451.4000627-16-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
XFS has its own buffer cache for metadata that uses submit_bio, which
means that it no longer uses the block device pagecache for anything.
Create a more lightweight helper that runs the blocksize checks and
flushes dirty data and use that instead. No more truncating the
pagecache because XFS does not use it or care about it.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_buf_free can call vunmap, which can sleep. The vunmap path is an
unlikely one, so add might_sleep to ensure calling xfs_buf_free from
atomic context gets caught more easily.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
No callers passes flags to xfs_buf_get_uncached, which makes sense
given that the flags apply to behavior not used for uncached buffers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
No callers passes flags to xfs_buf_read_uncached, which makes sense
given that the flags apply to behavior not used for uncached buffers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_buf_free_maps only has a single caller, so open code it there. Stop
zeroing the b_maps pointer as the buffer is freed in the next line.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_buf_get_maps has a single caller, and can just be open coded there.
When doing that, stop handling the allocation failure as we always pass
__GFP_NOFAIL to the slab allocator, and use the proper kcalloc helper for
array allocations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
We never allocate a buffer without backing memory. Simplify the call
chain by calling xfs_buf_alloc_backing_mem from _xfs_buf_alloc. To
avoid a forward declaration, move _xfs_buf_alloc down a bit in the
file.
Also drop the pointless _-prefix from _xfs_buf_alloc.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Add three trace points for the different backing memory allocators for
buffers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Directly assign b_addr based on the tmpfs folios without a detour
through pages, reuse the folio_put path used for non-tmpfs buffers
and replace all references to pages in comments with folios.
Partially based on a patch from Dave Chinner <dchinner@redhat.com>.
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 fallback buffer allocation path currently open codes a suboptimal
version of vmalloc to allocate pages that are then mapped into
vmalloc space. Switch to using vmalloc instead, which uses all the
optimizations in the common vmalloc code, and removes the need to
track the backing pages in the xfs_buf 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>
Unmapped buffer access is a pain, so kill it. The switch to large
folios means we rarely pay a vmap penalty for large buffers,
so this functionality is largely unnecessary now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Now that we have the buffer cache using the folio API, we can extend
the use of folios to allocate high order folios for multi-page
buffers rather than an array of single pages that are then vmapped
into a contiguous range.
This creates a new type of single folio buffers that can have arbitrary
order in addition to the existing multi-folio buffers made up of many
single page folios that get vmapped. The single folio is for now
stashed into the existing b_pages array, but that will go away entirely
later in the series and remove the temporary page vs folio typing issues
that only work because the two structures currently can be used largely
interchangeable.
The code that allocates buffers will optimistically attempt a high
order folio allocation as a fast path if the buffer size is a power
of two and thus fits into a folio. If this high order allocation
fails, then we fall back to the existing multi-folio allocation
code. This now forms the slow allocation path, and hopefully will be
largely unused in normal conditions except for buffers with size
that are not a power of two like larger remote xattrs.
This should improve performance of large buffer operations (e.g.
large directory block sizes) as we should now mostly avoid the
expense of vmapping large buffers (and the vmap lock contention that
can occur) as well as avoid the runtime pressure that frequently
accessing kernel vmapped pages put on the TLBs.
Based on a patch from Dave Chinner <dchinner@redhat.com>, but mutilated
beyond recognition.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Since commit 59bb47985c ("mm, sl[aou]b: guarantee natural alignment
for kmalloc(power-of-two)", kmalloc and friends guarantee that power of
two sized allocations are naturally aligned. Limit our use of kmalloc
for buffers to these power of two sizes and remove the fallback to
the page allocator for this case, but keep a check in addition to
trusting the slab allocator to get the alignment right.
Also refactor the kmalloc path to reuse various calculations for the
size and gfp flags.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Lift handling of shmem and slab backed buffers into xfs_buf_alloc_pages
and rename the result to xfs_buf_alloc_backing_mem. This shares more
code and ensures uncached buffers can also use slab, which slightly
reduces the memory usage of growfs on 512 byte sector size file systems,
but more importantly means the allocation invariants are the same for
cached and uncached buffers. Document these new invariants with a big
fat comment mostly stolen from a patch by Dave Chinner.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
No need to look at the page count if we can simply call is_vmalloc_addr
on bp->b_addr. This prepares for eventualy removing the b_page_count
field.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
b_offset is only set for slab backed buffers and always set to
offset_in_page(bp->b_addr), which can be done just as easily in the only
user of b_offset.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
No need to walk the page list if bp->b_addr is valid. That also means
b_offset doesn't need to be taken into account in the unmapped loop as
b_offset is only set for kmem backed buffers which are always mapped.
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_buf_stale already set b_lru_ref to 0, and thus prevents the buffer
from moving to the LRU. Remove the duplicate check.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
The buffer cache keeps a bt_io_count per-CPU counter to track all
in-flight I/O, which is used to ensure no I/O is in flight when
unmounting the file system.
For most I/O we already keep track of inflight I/O at higher levels:
- for synchronous I/O (xfs_buf_read/xfs_bwrite/xfs_buf_delwri_submit),
the caller has a reference and waits for I/O completions using
xfs_buf_iowait
- for xfs_buf_delwri_submit_nowait the only caller (AIL writeback)
tracks the log items that the buffer attached to
This only leaves only xfs_buf_readahead_map as a submitter of
asynchronous I/O that is not tracked by anything else. Replace the
bt_io_count per-cpu counter with a more specific bt_readahead_count
counter only tracking readahead I/O. This allows to simply increment
it when submitting readahead I/O and decrementing it when it completed,
and thus simplify xfs_buf_rele and remove the needed for the
XBF_NO_IOACCT flags and the XFS_BSTATE_IN_FLIGHT buffer state.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
xfs_buf_readahead_map is the only caller of xfs_buf_read_map and thus
_xfs_buf_read that is not synchronous. Split it from xfs_buf_read_map
so that the asynchronous path is self-contained and the now purely
synchronous xfs_buf_read_map / _xfs_buf_read implementation can be
simplified.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Currently all metadata I/O completions happen in the m_buf_workqueue
workqueue. But for synchronous I/O (i.e. all buffer reads) there is no
need for that, as there always is a called in process context that is
waiting for the I/O. Factor out the guts of xfs_buf_ioend into a
separate helper and call it from xfs_buf_iowait to avoid a double
an extra context switch to the workqueue.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Merge tag 'xfs-fixes-6.14-rc2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs bug fixes from Carlos Maiolino:
"A few fixes for XFS, but the most notable one is:
- xfs: remove xfs_buf_cache.bc_lock
which has been hit by different persons including syzbot"
* tag 'xfs-fixes-6.14-rc2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: remove xfs_buf_cache.bc_lock
xfs: Add error handling for xfs_reflink_cancel_cow_range
xfs: Propagate errors from xfs_reflink_cancel_cow_range in xfs_dax_write_iomap_end
xfs: don't call remap_verify_area with sb write protection held
xfs: remove an out of data comment in _xfs_buf_alloc
xfs: fix the entry condition of exact EOF block allocation optimization
xfs_buf_cache.bc_lock serializes adding buffers to and removing them from
the hashtable. But as the rhashtable code already uses fine grained
internal locking for inserts and removals the extra protection isn't
actually required.
It also happens to fix a lock order inversion vs b_lock added by the
recent lookup race fix.
Fixes: ee10f6fcdb ("xfs: fix buffer lookup vs release race")
Reported-by: Lai, Yi <yi1.lai@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
indivudual patches which are described in their changelogs.
- "Allocate and free frozen pages" from Matthew Wilcox reorganizes the
page allocator so we end up with the ability to allocate and free
zero-refcount pages. So that callers (ie, slab) can avoid a refcount
inc & dec.
- "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to use
large folios other than PMD-sized ones.
- "Fix mm/rodata_test" from Petr Tesarik performs some maintenance and
fixes for this small built-in kernel selftest.
- "mas_anode_descend() related cleanup" from Wei Yang tidies up part of
the mapletree code.
- "mm: fix format issues and param types" from Keren Sun implements a
few minor code cleanups.
- "simplify split calculation" from Wei Yang provides a few fixes and a
test for the mapletree code.
- "mm/vma: make more mmap logic userland testable" from Lorenzo Stoakes
continues the work of moving vma-related code into the (relatively) new
mm/vma.c.
- "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
Hildenbrand cleans up and rationalizes handling of gfp flags in the page
allocator.
- "readahead: Reintroduce fix for improper RA window sizing" from Jan
Kara is a second attempt at fixing a readahead window sizing issue. It
should reduce the amount of unnecessary reading.
- "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
addresses an issue where "huge" amounts of pte pagetables are
accumulated
(https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/).
Qi's series addresses this windup by synchronously freeing PTE memory
within the context of madvise(MADV_DONTNEED).
- "selftest/mm: Remove warnings found by adding compiler flags" from
Muhammad Usama Anjum fixes some build warnings in the selftests code
when optional compiler warnings are enabled.
- "mm: don't use __GFP_HARDWALL when migrating remote pages" from David
Hildenbrand tightens the allocator's observance of __GFP_HARDWALL.
- "pkeys kselftests improvements" from Kevin Brodsky implements various
fixes and cleanups in the MM selftests code, mainly pertaining to the
pkeys tests.
- "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
estimate application working set size.
- "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
provides some cleanups to memcg's hugetlb charging logic.
- "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
removes the global swap cgroup lock. A speedup of 10% for a tmpfs-based
kernel build was demonstrated.
- "zram: split page type read/write handling" from Sergey Senozhatsky
has several fixes and cleaups for zram in the area of zram_write_page().
A watchdog softlockup warning was eliminated.
- "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin Brodsky
cleans up the pagetable destructor implementations. A rare
use-after-free race is fixed.
- "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
simplifies and cleans up the debugging code in the VMA merging logic.
- "Account page tables at all levels" from Kevin Brodsky cleans up and
regularizes the pagetable ctor/dtor handling. This results in
improvements in accounting accuracy.
- "mm/damon: replace most damon_callback usages in sysfs with new core
functions" from SeongJae Park cleans up and generalizes DAMON's sysfs
file interface logic.
- "mm/damon: enable page level properties based monitoring" from
SeongJae Park increases the amount of information which is presented in
response to DAMOS actions.
- "mm/damon: remove DAMON debugfs interface" from SeongJae Park removes
DAMON's long-deprecated debugfs interfaces. Thus the migration to sysfs
is completed.
- "mm/hugetlb: Refactor hugetlb allocation resv accounting" from Peter
Xu cleans up and generalizes the hugetlb reservation accounting.
- "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
removes a never-used feature of the alloc_pages_bulk() interface.
- "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
extends DAMOS filters to support not only exclusion (rejecting), but
also inclusion (allowing) behavior.
- "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
"introduces a new memory descriptor for zswap.zpool that currently
overlaps with struct page for now. This is part of the effort to reduce
the size of struct page and to enable dynamic allocation of memory
descriptors."
- "mm, swap: rework of swap allocator locks" from Kairui Song redoes and
simplifies the swap allocator locking. A speedup of 400% was
demonstrated for one workload. As was a 35% reduction for kernel build
time with swap-on-zram.
- "mm: update mips to use do_mmap(), make mmap_region() internal" from
Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
mmap_region() can be made MM-internal.
- "mm/mglru: performance optimizations" from Yu Zhao fixes a few MGLRU
regressions and otherwise improves MGLRU performance.
- "Docs/mm/damon: add tuning guide and misc updates" from SeongJae Park
updates DAMON documentation.
- "Cleanup for memfd_create()" from Isaac Manjarres does that thing.
- "mm: hugetlb+THP folio and migration cleanups" from David Hildenbrand
provides various cleanups in the areas of hugetlb folios, THP folios and
migration.
- "Uncached buffered IO" from Jens Axboe implements the new
RWF_DONTCACHE flag which provides synchronous dropbehind for pagecache
reading and writing. To permite userspace to address issues with
massive buildup of useless pagecache when reading/writing fast devices.
- "selftests/mm: virtual_address_range: Reduce memory" from Thomas
Weißschuh fixes and optimizes some of the MM selftests.
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Merge tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"The various patchsets are summarized below. Plus of course many
indivudual patches which are described in their changelogs.
- "Allocate and free frozen pages" from Matthew Wilcox reorganizes
the page allocator so we end up with the ability to allocate and
free zero-refcount pages. So that callers (ie, slab) can avoid a
refcount inc & dec
- "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
use large folios other than PMD-sized ones
- "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
and fixes for this small built-in kernel selftest
- "mas_anode_descend() related cleanup" from Wei Yang tidies up part
of the mapletree code
- "mm: fix format issues and param types" from Keren Sun implements a
few minor code cleanups
- "simplify split calculation" from Wei Yang provides a few fixes and
a test for the mapletree code
- "mm/vma: make more mmap logic userland testable" from Lorenzo
Stoakes continues the work of moving vma-related code into the
(relatively) new mm/vma.c
- "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
Hildenbrand cleans up and rationalizes handling of gfp flags in the
page allocator
- "readahead: Reintroduce fix for improper RA window sizing" from Jan
Kara is a second attempt at fixing a readahead window sizing issue.
It should reduce the amount of unnecessary reading
- "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
addresses an issue where "huge" amounts of pte pagetables are
accumulated:
https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/
Qi's series addresses this windup by synchronously freeing PTE
memory within the context of madvise(MADV_DONTNEED)
- "selftest/mm: Remove warnings found by adding compiler flags" from
Muhammad Usama Anjum fixes some build warnings in the selftests
code when optional compiler warnings are enabled
- "mm: don't use __GFP_HARDWALL when migrating remote pages" from
David Hildenbrand tightens the allocator's observance of
__GFP_HARDWALL
- "pkeys kselftests improvements" from Kevin Brodsky implements
various fixes and cleanups in the MM selftests code, mainly
pertaining to the pkeys tests
- "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
estimate application working set size
- "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
provides some cleanups to memcg's hugetlb charging logic
- "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
removes the global swap cgroup lock. A speedup of 10% for a
tmpfs-based kernel build was demonstrated
- "zram: split page type read/write handling" from Sergey Senozhatsky
has several fixes and cleaups for zram in the area of
zram_write_page(). A watchdog softlockup warning was eliminated
- "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
Brodsky cleans up the pagetable destructor implementations. A rare
use-after-free race is fixed
- "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
simplifies and cleans up the debugging code in the VMA merging
logic
- "Account page tables at all levels" from Kevin Brodsky cleans up
and regularizes the pagetable ctor/dtor handling. This results in
improvements in accounting accuracy
- "mm/damon: replace most damon_callback usages in sysfs with new
core functions" from SeongJae Park cleans up and generalizes
DAMON's sysfs file interface logic
- "mm/damon: enable page level properties based monitoring" from
SeongJae Park increases the amount of information which is
presented in response to DAMOS actions
- "mm/damon: remove DAMON debugfs interface" from SeongJae Park
removes DAMON's long-deprecated debugfs interfaces. Thus the
migration to sysfs is completed
- "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
Peter Xu cleans up and generalizes the hugetlb reservation
accounting
- "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
removes a never-used feature of the alloc_pages_bulk() interface
- "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
extends DAMOS filters to support not only exclusion (rejecting),
but also inclusion (allowing) behavior
- "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
introduces a new memory descriptor for zswap.zpool that currently
overlaps with struct page for now. This is part of the effort to
reduce the size of struct page and to enable dynamic allocation of
memory descriptors
- "mm, swap: rework of swap allocator locks" from Kairui Song redoes
and simplifies the swap allocator locking. A speedup of 400% was
demonstrated for one workload. As was a 35% reduction for kernel
build time with swap-on-zram
- "mm: update mips to use do_mmap(), make mmap_region() internal"
from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
mmap_region() can be made MM-internal
- "mm/mglru: performance optimizations" from Yu Zhao fixes a few
MGLRU regressions and otherwise improves MGLRU performance
- "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
Park updates DAMON documentation
- "Cleanup for memfd_create()" from Isaac Manjarres does that thing
- "mm: hugetlb+THP folio and migration cleanups" from David
Hildenbrand provides various cleanups in the areas of hugetlb
folios, THP folios and migration
- "Uncached buffered IO" from Jens Axboe implements the new
RWF_DONTCACHE flag which provides synchronous dropbehind for
pagecache reading and writing. To permite userspace to address
issues with massive buildup of useless pagecache when
reading/writing fast devices
- "selftests/mm: virtual_address_range: Reduce memory" from Thomas
Weißschuh fixes and optimizes some of the MM selftests"
* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
mm/compaction: fix UBSAN shift-out-of-bounds warning
s390/mm: add missing ctor/dtor on page table upgrade
kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
tools: add VM_WARN_ON_VMG definition
mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
seqlock: add missing parameter documentation for raw_seqcount_try_begin()
mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
mm/page_alloc: remove the incorrect and misleading comment
zram: remove zcomp_stream_put() from write_incompressible_page()
mm: separate move/undo parts from migrate_pages_batch()
mm/kfence: use str_write_read() helper in get_access_type()
selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
selftests/mm: vm_util: split up /proc/self/smaps parsing
selftests/mm: virtual_address_range: unmap chunks after validation
selftests/mm: virtual_address_range: mmap() without PROT_WRITE
selftests/memfd/memfd_test: fix possible NULL pointer dereference
mm: add FGP_DONTCACHE folio creation flag
mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
...
The previous commit removed the page_list argument from
alloc_pages_bulk_noprof() along with the alloc_pages_bulk_list() function.
Now that only the *_array() flavour of the API remains, we can do the
following renaming (along with the _noprof() ones):
alloc_pages_bulk_array -> alloc_pages_bulk
alloc_pages_bulk_array_mempolicy -> alloc_pages_bulk_mempolicy
alloc_pages_bulk_array_node -> alloc_pages_bulk_node
Link: https://lkml.kernel.org/r/275a3bbc0be20fbe9002297d60045e67ab3d4ada.1734991165.git.luizcap@redhat.com
Signed-off-by: Luiz Capitulino <luizcap@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There hasn't been anything like an io_length for a long time.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Since commit 298f342245 ("xfs: lockless buffer lookup") the buffer
lookup fastpath is done without a hash-wide lock (then pag_buf_lock, now
bc_lock) and only under RCU protection. But this means that nothing
serializes lookups against the temporary 0 reference count for buffers
that are added to the LRU after dropping the last regular reference,
and a concurrent lookup would fail to find them.
Fix this by doing all b_hold modifications under b_lock. We're already
doing this for release so this "only" ~ doubles the b_lock round trips.
We'll later look into the lockref infrastructure to optimize the number
of lock round trips again.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Commit 32dd4f9c50 ("xfs: remove a superflous hash lookup when inserting
new buffers") converted xfs_buf_find_insert to use
rhashtable_lookup_get_insert_fast and thus an operation that returns the
existing buffer when an insert would duplicate the hash key. But this
code path misses the check for a buffer with a reference count of zero,
which could lead to reusing an about to be freed buffer. Fix this by
using the same atomic_inc_not_zero pattern as xfs_buf_insert.
Fixes: 32dd4f9c50 ("xfs: remove a superflous hash lookup when inserting new buffers")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: stable@vger.kernel.org # v6.0
Signed-off-by: Carlos Maiolino <cem@kernel.org>
