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Currently reading an inline data extent will zero out the remaining
range in the page.
This is not yet causing problems even for block size < page size
(subpage) cases because:
1) An inline data extent always starts at file offset 0
Meaning at page read, we always read the inline extent first, before
any other blocks in the page. Then later blocks are properly read out
and re-fill the zeroed out ranges.
2) Currently btrfs will read out the whole page if a buffered write is
not page aligned
So a page is either fully uptodate at buffered write time (covers the
whole page), or we will read out the whole page first.
Meaning there is nothing to lose for such an inline extent read.
But it's still not ideal:
- We're zeroing out the page twice
Once done by read_inline_extent()/uncompress_inline(), once done by
btrfs_do_readpage() for ranges beyond i_size.
- We're touching blocks that don't belong to the inline extent
In the incoming patches, we can have a partial uptodate folio, of
which some dirty blocks can exist while the page is not fully uptodate:
The page size is 16K and block size is 4K:
0 4K 8K 12K 16K
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And range [8K, 12K) is dirtied by a buffered write, the remaining
blocks are not uptodate.
If range [0, 4K) contains an inline data extent, and we try to read
the whole page, the current behavior will overwrite range [8K, 12K)
with zero and cause data loss.
So to make the behavior more consistent and in preparation for future
changes, limit the inline data extents read to only zero out the range
inside the first block, not the whole page.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to btrfs_inherit_props() as it's an internal
interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to btrfs_load_inode_props() as it's an
internal interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to btrfs_fill_inode() as it's an internal
interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to btrfs_inode() as it's an internal
interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to new_simple_dir() as it's an internal
interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to btrfs_inode() as it's an internal
interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to btrfs_read_locked_inode() as it's an
internal interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to extent_range_clear_dirty_for_io() as it's
an internal interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass a struct btrfs_inode to can_nocow_extent() as it's an internal
interface, allowing to remove some use of BTRFS_I.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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The btrfs_key is defined as objectid/type/offset and the keys are also
printed like that. For better readability, update all key
initializations to match this order.
Signed-off-by: David Sterba <dsterba@suse.com>
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Allow using the fast modes (negative compression levels) of zstd as a
mount option.
As per the results, the compression ratio is (expectedly) lower:
for level in {-15..-1} 1 2 3; \
do printf "level %3d\n" $level; \
mount -o compress=zstd:$level /dev/sdb /mnt/test/; \
grep sdb /proc/mounts; \
cp -r /usr/bin /mnt/test/; sync; compsize /mnt/test/bin; \
cp -r /usr/share/doc /mnt/test/; sync; compsize /mnt/test/doc; \
cp enwik9 /mnt/test/; sync; compsize /mnt/test/enwik9; \
cp linux-6.13.tar /mnt/test/; sync; compsize /mnt/test/linux-6.13.tar; \
rm -r /mnt/test/{bin,doc,enwik9,linux-6.13.tar}; \
umount /mnt/test/; \
done |& tee results | \
awk '/^level/{print}/^TOTAL/{print$3"\t"$2" |"}' | paste - - - - -
266M bin | 45M doc | 953M wiki | 1.4G source
=============================+===============+===============+===============+
level -15 180M 67% | 30M 68% | 694M 72% | 598M 40% |
level -14 180M 67% | 30M 67% | 683M 71% | 581M 39% |
level -13 177M 66% | 29M 66% | 671M 70% | 566M 38% |
level -12 174M 65% | 29M 65% | 658M 69% | 548M 37% |
level -11 174M 65% | 28M 64% | 645M 67% | 530M 35% |
level -10 171M 64% | 28M 62% | 631M 66% | 512M 34% |
level -9 165M 62% | 27M 61% | 615M 64% | 493M 33% |
level -8 161M 60% | 27M 59% | 598M 62% | 475M 32% |
level -7 155M 58% | 26M 58% | 582M 61% | 457M 30% |
level -6 151M 56% | 25M 56% | 565M 59% | 437M 29% |
level -5 145M 54% | 24M 55% | 545M 57% | 417M 28% |
level -4 139M 52% | 23M 52% | 520M 54% | 391M 26% |
level -3 135M 50% | 22M 50% | 495M 51% | 369M 24% |
level -2 127M 47% | 22M 48% | 470M 49% | 349M 23% |
level -1 120M 45% | 21M 47% | 452M 47% | 332M 22% |
level 1 110M 41% | 17M 39% | 362M 38% | 290M 19% |
level 2 106M 40% | 17M 38% | 349M 36% | 288M 19% |
level 3 104M 39% | 16M 37% | 340M 35% | 276M 18% |
The samples represent some data sets that can be commonly found and show
approximate compressibility. The fast levels trade off speed for ratio
and are best suitable for highly compressible data.
As can be seen above, comparing the results to the current default zstd
level 3, the negative levels are roughly 2x worse at -15 and the
ratio increases almost linearly with each level.
Signed-off-by: Daniel Vacek <neelx@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
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The ordered extent cleanup is hard to grasp because it doesn't follow
the common cleanup-asap pattern.
E.g. run_delalloc_nocow() and cow_file_range() allocate one or more
ordered extent, but if any error is hit, the cleanup is done later inside
btrfs_run_delalloc_range().
To change the existing delayed cleanup:
- Update the comment on error handling of run_delalloc_nocow()
There are in fact 3 different cases other than 2 if we are doing
ordered extents cleanup inside run_delalloc_nocow():
1) @cow_start and @cow_end not set
No fallback to COW at all.
Before @cur_offset we need to cleanup the OE and page dirty.
After @cur_offset just clear all involved page and extent flags.
2) @cow_start set but @cow_end not set.
This means we failed before even calling fallback_to_cow().
It's just a variant of case 1), where it's @cow_start splitting
the two parts (and we should just ignore @cur_offset since it's
advanced without any new ordered extent).
3) @cow_start and @cow_end both set
This means fallback_to_cow() failed, meaning [start, cow_start)
needs the regular OE and dirty folio cleanup, and skip range
[cow_start, cow_end) as cow_file_range() has done the cleanup,
and eventually cleanup [cow_end, end) range.
- Only reset @cow_start after fallback_to_cow() succeeded
As above case 2) and 3) are both relying on @cow_start to determine
the cleanup range.
- Move btrfs_cleanup_ordered_extents() into run_delalloc_nocow(),
cow_file_range() and nocow_one_range()
For cow_file_range() it's pretty straightforward and easy.
For run_delalloc_nocow() refer to the above 3 different error cases.
For nocow_one_range() if we hit an error, we need to cleanup the
ordered extents by ourselves.
And then it will fallback to case 1), since @cur_offset is not yet
advanced, the existing cleanup will co-operate with nocow_one_range()
well.
- Remove the btrfs_cleanup_ordered_extents() inside submit_uncompressed_range()
As failed cow_file_range() will do all the proper cleanup now.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Currently we're doing all the ordered extent and extent map generation
inside a while() loop of run_delalloc_nocow(). This makes it pretty
hard to read, nor doing proper error handling.
So move that part of code into a helper, nocow_one_range().
This should not change anything, but there is a tiny timing change where
btrfs_dec_nocow_writers() is only called after nocow_one_range() helper
exits.
This timing change is small, and makes error handling easier, thus
should be fine.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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The address space flag AS_STABLE_WRITES determine if FGP_STABLE for will
wait for the folio to finish its writeback.
For btrfs, due to the default data checksum behavior, if we modify the
folio while it's still under writeback, it will cause data checksum
mismatch. Thus for quite some call sites we manually call
folio_wait_writeback() to prevent such problem from happening.
Currently there is only one call site inside btrfs really utilizing
FGP_STABLE, and in that case we also manually call folio_wait_writeback()
to do the waiting.
But it's better to properly expose the stable writes flag to a per-inode
basis, to allow call sites to fully benefit from FGP_STABLE flag.
E.g. for inodes with NODATASUM allowing beginning dirtying the page
without waiting for writeback.
This involves:
- Update the mapping's stable write flag when setting/clearing NODATASUM
inode flag using ioctl
This only works for empty files, so it should be fine.
- Update the mapping's stable write flag when reading an inode from disk
- Remove the explicit folio_wait_writeback() for FGP_BEGINWRITE call
site
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Remove references to the page lock and page->mapping. Also btrfs folios
can never be swizzled into swap (mentioned in extent_write_cache_pages()).
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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btrfs_encoded_read_regular_fill_pages()
Only allocate the btrfs_encoded_read_private structure for asynchronous
(io_uring) mode.
There's no need to allocate an object from slab in the synchronous mode. In
such a case stack can be happily used as it used to be before 68d3b27e05c7
("btrfs: move priv off stack in btrfs_encoded_read_regular_fill_pages()")
which was a preparation for the async mode.
While at it, fix the comment to reflect the atomic => refcount change in
d29662695ed7 ("btrfs: fix use-after-free waiting for encoded read endios").
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Daniel Vacek <neelx@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- fix leaked extent map after error when reading chunks
- replace use of deprecated strncpy
- in zoned mode, fixed range when ulocking extent range, causing a hang
* tag 'for-6.14-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fix a leaked chunk map issue in read_one_chunk()
btrfs: replace deprecated strncpy() with strscpy()
btrfs: zoned: fix extent range end unlock in cow_file_range()
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Some filesystems, such as NFS, cifs, ceph, and fuse, do not have
complete control of sequencing on the actual filesystem (e.g. on a
different server) and may find that the inode created for a mkdir
request already exists in the icache and dcache by the time the mkdir
request returns. For example, if the filesystem is mounted twice the
directory could be visible on the other mount before it is on the
original mount, and a pair of name_to_handle_at(), open_by_handle_at()
calls could instantiate the directory inode with an IS_ROOT() dentry
before the first mkdir returns.
This means that the dentry passed to ->mkdir() may not be the one that
is associated with the inode after the ->mkdir() completes. Some
callers need to interact with the inode after the ->mkdir completes and
they currently need to perform a lookup in the (rare) case that the
dentry is no longer hashed.
This lookup-after-mkdir requires that the directory remains locked to
avoid races. Planned future patches to lock the dentry rather than the
directory will mean that this lookup cannot be performed atomically with
the mkdir.
To remove this barrier, this patch changes ->mkdir to return the
resulting dentry if it is different from the one passed in.
Possible returns are:
NULL - the directory was created and no other dentry was used
ERR_PTR() - an error occurred
non-NULL - this other dentry was spliced in
This patch only changes file-systems to return "ERR_PTR(err)" instead of
"err" or equivalent transformations. Subsequent patches will make
further changes to some file-systems to return a correct dentry.
Not all filesystems reliably result in a positive hashed dentry:
- NFS, cifs, hostfs will sometimes need to perform a lookup of
the name to get inode information. Races could result in this
returning something different. Note that this lookup is
non-atomic which is what we are trying to avoid. Placing the
lookup in filesystem code means it only happens when the filesystem
has no other option.
- kernfs and tracefs leave the dentry negative and the ->revalidate
operation ensures that lookup will be called to correctly populate
the dentry. This could be fixed but I don't think it is important
to any of the users of vfs_mkdir() which look at the dentry.
The recommendation to use
d_drop();d_splice_alias()
is ugly but fits with current practice. A planned future patch will
change this.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250227013949.536172-2-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Running generic/751 on the for-next branch often results in a hang like
below. They are both stack by locking an extent. This suggests someone
forget to unlock an extent.
INFO: task kworker/u128:1:12 blocked for more than 323 seconds.
Not tainted 6.13.0-BTRFS-ZNS+ #503
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u128:1 state:D stack:0 pid:12 tgid:12 ppid:2 flags:0x00004000
Workqueue: btrfs-fixup btrfs_work_helper [btrfs]
Call Trace:
<TASK>
__schedule+0x534/0xdd0
schedule+0x39/0x140
__lock_extent+0x31b/0x380 [btrfs]
? __pfx_autoremove_wake_function+0x10/0x10
btrfs_writepage_fixup_worker+0xf1/0x3a0 [btrfs]
btrfs_work_helper+0xff/0x480 [btrfs]
? lock_release+0x178/0x2c0
process_one_work+0x1ee/0x570
? srso_return_thunk+0x5/0x5f
worker_thread+0x1d1/0x3b0
? __pfx_worker_thread+0x10/0x10
kthread+0x10b/0x230
? __pfx_kthread+0x10/0x10
ret_from_fork+0x30/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
INFO: task kworker/u134:0:184 blocked for more than 323 seconds.
Not tainted 6.13.0-BTRFS-ZNS+ #503
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u134:0 state:D stack:0 pid:184 tgid:184 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-btrfs-4)
Call Trace:
<TASK>
__schedule+0x534/0xdd0
schedule+0x39/0x140
__lock_extent+0x31b/0x380 [btrfs]
? __pfx_autoremove_wake_function+0x10/0x10
find_lock_delalloc_range+0xdb/0x260 [btrfs]
writepage_delalloc+0x12f/0x500 [btrfs]
? srso_return_thunk+0x5/0x5f
extent_write_cache_pages+0x232/0x840 [btrfs]
btrfs_writepages+0x72/0x130 [btrfs]
do_writepages+0xe7/0x260
? srso_return_thunk+0x5/0x5f
? lock_acquire+0xd2/0x300
? srso_return_thunk+0x5/0x5f
? find_held_lock+0x2b/0x80
? wbc_attach_and_unlock_inode.part.0+0x102/0x250
? wbc_attach_and_unlock_inode.part.0+0x102/0x250
__writeback_single_inode+0x5c/0x4b0
writeback_sb_inodes+0x22d/0x550
__writeback_inodes_wb+0x4c/0xe0
wb_writeback+0x2f6/0x3f0
wb_workfn+0x32a/0x510
process_one_work+0x1ee/0x570
? srso_return_thunk+0x5/0x5f
worker_thread+0x1d1/0x3b0
? __pfx_worker_thread+0x10/0x10
kthread+0x10b/0x230
? __pfx_kthread+0x10/0x10
ret_from_fork+0x30/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
This happens because we have another success path for the zoned mode. When
there is no active zone available, btrfs_reserve_extent() returns
-EAGAIN. In this case, we have two reactions.
(1) If the given range is never allocated, we can only wait for someone
to finish a zone, so wait on BTRFS_FS_NEED_ZONE_FINISH bit and retry
afterward.
(2) Or, if some allocations are already done, we must bail out and let
the caller to send IOs for the allocation. This is because these IOs
may be necessary to finish a zone.
The commit 06f364284794 ("btrfs: do proper folio cleanup when
cow_file_range() failed") moved the unlock code from the inside of the
loop to the outside. So, previously, the allocated extents are unlocked
just after the allocation and so before returning from the function.
However, they are no longer unlocked on the case (2) above. That caused
the hang issue.
Fix the issue by modifying the 'end' to the end of the allocated
range. Then, we can exit the loop and the same unlock code can properly
handle the case.
Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Fixes: 06f364284794 ("btrfs: do proper folio cleanup when cow_file_range() failed")
CC: stable@vger.kernel.org
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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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
...
|
|
Remove highest_bit and lowest_bit. After the HDD allocation path has been
removed, the only purpose of these two fields is to determine whether the
device is full or not, which can instead be determined by checking the
inuse_pages.
Link: https://lkml.kernel.org/r/20250113175732.48099-6-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chis Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
btrfs_cleanup_ordered_extents()
The function btrfs_cleanup_ordered_extents() is only called in error
handling path, and the last caller with a @locked_folio parameter was
removed to fix a bug in the btrfs_run_delalloc_range() error handling.
There is no need to pass @locked_folio parameter anymore.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
All the error handling bugs I hit so far are all -ENOSPC from either:
- cow_file_range()
- run_delalloc_nocow()
- submit_uncompressed_range()
Previously when those functions failed, there was no error message at
all, making the debugging much harder.
So here we introduce extra error messages for:
- cow_file_range()
- run_delalloc_nocow()
- submit_uncompressed_range()
- writepage_delalloc() when btrfs_run_delalloc_range() failed
- extent_writepage() when extent_writepage_io() failed
One example of the new debug error messages is the following one:
run fstests generic/750 at 2024-12-08 12:41:41
BTRFS: device fsid 461b25f5-e240-4543-8deb-e7c2bd01a6d3 devid 1 transid 8 /dev/mapper/test-scratch1 (253:4) scanned by mount (2436600)
BTRFS info (device dm-4): first mount of filesystem 461b25f5-e240-4543-8deb-e7c2bd01a6d3
BTRFS info (device dm-4): using crc32c (crc32c-arm64) checksum algorithm
BTRFS info (device dm-4): forcing free space tree for sector size 4096 with page size 65536
BTRFS info (device dm-4): using free-space-tree
BTRFS warning (device dm-4): read-write for sector size 4096 with page size 65536 is experimental
BTRFS info (device dm-4): checking UUID tree
BTRFS error (device dm-4): cow_file_range failed, root=363 inode=412 start=503808 len=98304: -28
BTRFS error (device dm-4): run_delalloc_nocow failed, root=363 inode=412 start=503808 len=98304: -28
BTRFS error (device dm-4): failed to run delalloc range, root=363 ino=412 folio=458752 submit_bitmap=11-15 start=503808 len=98304: -28
Which shows an error from cow_file_range() which is called inside a
nocow write attempt, along with the extra bitmap from
writepage_delalloc().
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
[BUG]
With CONFIG_DEBUG_VM set, test case generic/476 has some chance to crash
with the following VM_BUG_ON_FOLIO():
BTRFS error (device dm-3): cow_file_range failed, start 1146880 end 1253375 len 106496 ret -28
BTRFS error (device dm-3): run_delalloc_nocow failed, start 1146880 end 1253375 len 106496 ret -28
page: refcount:4 mapcount:0 mapping:00000000592787cc index:0x12 pfn:0x10664
aops:btrfs_aops [btrfs] ino:101 dentry name(?):"f1774"
flags: 0x2fffff80004028(uptodate|lru|private|node=0|zone=2|lastcpupid=0xfffff)
page dumped because: VM_BUG_ON_FOLIO(!folio_test_locked(folio))
------------[ cut here ]------------
kernel BUG at mm/page-writeback.c:2992!
Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
CPU: 2 UID: 0 PID: 3943513 Comm: kworker/u24:15 Tainted: G OE 6.12.0-rc7-custom+ #87
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs]
pc : folio_clear_dirty_for_io+0x128/0x258
lr : folio_clear_dirty_for_io+0x128/0x258
Call trace:
folio_clear_dirty_for_io+0x128/0x258
btrfs_folio_clamp_clear_dirty+0x80/0xd0 [btrfs]
__process_folios_contig+0x154/0x268 [btrfs]
extent_clear_unlock_delalloc+0x5c/0x80 [btrfs]
run_delalloc_nocow+0x5f8/0x760 [btrfs]
btrfs_run_delalloc_range+0xa8/0x220 [btrfs]
writepage_delalloc+0x230/0x4c8 [btrfs]
extent_writepage+0xb8/0x358 [btrfs]
extent_write_cache_pages+0x21c/0x4e8 [btrfs]
btrfs_writepages+0x94/0x150 [btrfs]
do_writepages+0x74/0x190
filemap_fdatawrite_wbc+0x88/0xc8
start_delalloc_inodes+0x178/0x3a8 [btrfs]
btrfs_start_delalloc_roots+0x174/0x280 [btrfs]
shrink_delalloc+0x114/0x280 [btrfs]
flush_space+0x250/0x2f8 [btrfs]
btrfs_async_reclaim_data_space+0x180/0x228 [btrfs]
process_one_work+0x164/0x408
worker_thread+0x25c/0x388
kthread+0x100/0x118
ret_from_fork+0x10/0x20
Code: 910a8021 a90363f7 a9046bf9 94012379 (d4210000)
---[ end trace 0000000000000000 ]---
[CAUSE]
The first two lines of extra debug messages show the problem is caused
by the error handling of run_delalloc_nocow().
E.g. we have the following dirtied range (4K blocksize 4K page size):
0 16K 32K
|//////////////////////////////////////|
| Pre-allocated |
And the range [0, 16K) has a preallocated extent.
- Enter run_delalloc_nocow() for range [0, 16K)
Which found range [0, 16K) is preallocated, can do the proper NOCOW
write.
- Enter fallback_to_fow() for range [16K, 32K)
Since the range [16K, 32K) is not backed by preallocated extent, we
have to go COW.
- cow_file_range() failed for range [16K, 32K)
So cow_file_range() will do the clean up by clearing folio dirty,
unlock the folios.
Now the folios in range [16K, 32K) is unlocked.
- Enter extent_clear_unlock_delalloc() from run_delalloc_nocow()
Which is called with PAGE_START_WRITEBACK to start page writeback.
But folios can only be marked writeback when it's properly locked,
thus this triggered the VM_BUG_ON_FOLIO().
Furthermore there is another hidden but common bug that
run_delalloc_nocow() is not clearing the folio dirty flags in its error
handling path.
This is the common bug shared between run_delalloc_nocow() and
cow_file_range().
[FIX]
- Clear folio dirty for range [@start, @cur_offset)
Introduce a helper, cleanup_dirty_folios(), which
will find and lock the folio in the range, clear the dirty flag and
start/end the writeback, with the extra handling for the
@locked_folio.
- Introduce a helper to clear folio dirty, start and end writeback
- Introduce a helper to record the last failed COW range end
This is to trace which range we should skip, to avoid double
unlocking.
- Skip the failed COW range for the error handling
CC: stable@vger.kernel.org
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
[BUG]
When testing with COW fixup marked as BUG_ON() (this is involved with the
new pin_user_pages*() change, which should not result new out-of-band
dirty pages), I hit a crash triggered by the BUG_ON() from hitting COW
fixup path.
This BUG_ON() happens just after a failed btrfs_run_delalloc_range():
BTRFS error (device dm-2): failed to run delalloc range, root 348 ino 405 folio 65536 submit_bitmap 6-15 start 90112 len 106496: -28
------------[ cut here ]------------
kernel BUG at fs/btrfs/extent_io.c:1444!
Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
CPU: 0 UID: 0 PID: 434621 Comm: kworker/u24:8 Tainted: G OE 6.12.0-rc7-custom+ #86
Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs]
pc : extent_writepage_io+0x2d4/0x308 [btrfs]
lr : extent_writepage_io+0x2d4/0x308 [btrfs]
Call trace:
extent_writepage_io+0x2d4/0x308 [btrfs]
extent_writepage+0x218/0x330 [btrfs]
extent_write_cache_pages+0x1d4/0x4b0 [btrfs]
btrfs_writepages+0x94/0x150 [btrfs]
do_writepages+0x74/0x190
filemap_fdatawrite_wbc+0x88/0xc8
start_delalloc_inodes+0x180/0x3b0 [btrfs]
btrfs_start_delalloc_roots+0x174/0x280 [btrfs]
shrink_delalloc+0x114/0x280 [btrfs]
flush_space+0x250/0x2f8 [btrfs]
btrfs_async_reclaim_data_space+0x180/0x228 [btrfs]
process_one_work+0x164/0x408
worker_thread+0x25c/0x388
kthread+0x100/0x118
ret_from_fork+0x10/0x20
Code: aa1403e1 9402f3ef aa1403e0 9402f36f (d4210000)
---[ end trace 0000000000000000 ]---
[CAUSE]
That failure is mostly from cow_file_range(), where we can hit -ENOSPC.
Although the -ENOSPC is already a bug related to our space reservation
code, let's just focus on the error handling.
For example, we have the following dirty range [0, 64K) of an inode,
with 4K sector size and 4K page size:
0 16K 32K 48K 64K
|///////////////////////////////////////|
|#######################################|
Where |///| means page are still dirty, and |###| means the extent io
tree has EXTENT_DELALLOC flag.
- Enter extent_writepage() for page 0
- Enter btrfs_run_delalloc_range() for range [0, 64K)
- Enter cow_file_range() for range [0, 64K)
- Function btrfs_reserve_extent() only reserved one 16K extent
So we created extent map and ordered extent for range [0, 16K)
0 16K 32K 48K 64K
|////////|//////////////////////////////|
|<- OE ->|##############################|
And range [0, 16K) has its delalloc flag cleared.
But since we haven't yet submit any bio, involved 4 pages are still
dirty.
- Function btrfs_reserve_extent() returns with -ENOSPC
Now we have to run error cleanup, which will clear all
EXTENT_DELALLOC* flags and clear the dirty flags for the remaining
ranges:
0 16K 32K 48K 64K
|////////| |
| | |
Note that range [0, 16K) still has its pages dirty.
- Some time later, writeback is triggered again for the range [0, 16K)
since the page range still has dirty flags.
- btrfs_run_delalloc_range() will do nothing because there is no
EXTENT_DELALLOC flag.
- extent_writepage_io() finds page 0 has no ordered flag
Which falls into the COW fixup path, triggering the BUG_ON().
Unfortunately this error handling bug dates back to the introduction of
btrfs. Thankfully with the abuse of COW fixup, at least it won't crash
the kernel.
[FIX]
Instead of immediately unlocking the extent and folios, we keep the extent
and folios locked until either erroring out or the whole delalloc range
finished.
When the whole delalloc range finished without error, we just unlock the
whole range with PAGE_SET_ORDERED (and PAGE_UNLOCK for !keep_locked
cases), with EXTENT_DELALLOC and EXTENT_LOCKED cleared.
And the involved folios will be properly submitted, with their dirty
flags cleared during submission.
For the error path, it will be a little more complex:
- The range with ordered extent allocated (range (1))
We only clear the EXTENT_DELALLOC and EXTENT_LOCKED, as the remaining
flags are cleaned up by
btrfs_mark_ordered_io_finished()->btrfs_finish_one_ordered().
For folios we finish the IO (clear dirty, start writeback and
immediately finish the writeback) and unlock the folios.
- The range with reserved extent but no ordered extent (range(2))
- The range we never touched (range(3))
For both range (2) and range(3) the behavior is not changed.
Now even if cow_file_range() failed halfway with some successfully
reserved extents/ordered extents, we will keep all folios clean, so
there will be no future writeback triggered on them.
CC: stable@vger.kernel.org
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
[BUG]
If we failed to compress the range, or cannot reserve a large enough
data extent (e.g. too fragmented free space), we will fall back to
submit_uncompressed_range().
But inside submit_uncompressed_range(), run_delalloc_cow() can also fail
due to -ENOSPC or any other error.
In that case there are 3 bugs in the error handling:
1) Double freeing for the same ordered extent
This can lead to crash due to ordered extent double accounting
2) Start/end writeback without updating the subpage writeback bitmap
3) Unlock the folio without clear the subpage lock bitmap
Both bugs 2) and 3) will crash the kernel if the btrfs block size is
smaller than folio size, as the next time the folio gets writeback/lock
updates, subpage will find the bitmap already have the range set,
triggering an ASSERT().
[CAUSE]
Bug 1) happens in the following call chain:
submit_uncompressed_range()
|- run_delalloc_cow()
| |- cow_file_range()
| |- btrfs_reserve_extent()
| Failed with -ENOSPC or whatever error
|
|- btrfs_clean_up_ordered_extents()
| |- btrfs_mark_ordered_io_finished()
| Which cleans all the ordered extents in the async_extent range.
|
|- btrfs_mark_ordered_io_finished()
Which cleans the folio range.
The finished ordered extents may not be immediately removed from the
ordered io tree, as they are removed inside a work queue.
So the second btrfs_mark_ordered_io_finished() may find the finished but
not-yet-removed ordered extents, and double free them.
Furthermore, the second btrfs_mark_ordered_io_finished() is not subpage
compatible, as it uses fixed folio_pos() with PAGE_SIZE, which can cover
other ordered extents.
Bugs 2) and 3) are more straightforward, btrfs just calls folio_unlock(),
folio_start_writeback() and folio_end_writeback(), other than the helpers
which handle subpage cases.
[FIX]
For bug 1) since the first btrfs_cleanup_ordered_extents() call is
handling the whole range, we should not do the second
btrfs_mark_ordered_io_finished() call.
And for the first btrfs_cleanup_ordered_extents(), we no longer need to
pass the @locked_page parameter, as we are already in the async extent
context, thus will never rely on the error handling inside
btrfs_run_delalloc_range().
So just let the btrfs_clean_up_ordered_extents() handle every folio
equally.
For bug 2) we should not even call
folio_start_writeback()/folio_end_writeback() anymore.
As the error handling protocol, cow_file_range() should clear
dirty flag and start/finish the writeback for the whole range passed in.
For bug 3) just change the folio_unlock() to btrfs_folio_end_lock()
helper.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
[BUG]
When running btrfs with block size (4K) smaller than page size (64K,
aarch64), there is a very high chance to crash the kernel at
generic/750, with the following messages:
(before the call traces, there are 3 extra debug messages added)
BTRFS warning (device dm-3): read-write for sector size 4096 with page size 65536 is experimental
BTRFS info (device dm-3): checking UUID tree
hrtimer: interrupt took 5451385 ns
BTRFS error (device dm-3): cow_file_range failed, root=4957 inode=257 start=1605632 len=69632: -28
BTRFS error (device dm-3): run_delalloc_nocow failed, root=4957 inode=257 start=1605632 len=69632: -28
BTRFS error (device dm-3): failed to run delalloc range, root=4957 ino=257 folio=1572864 submit_bitmap=8-15 start=1605632 len=69632: -28
------------[ cut here ]------------
WARNING: CPU: 2 PID: 3020984 at ordered-data.c:360 can_finish_ordered_extent+0x370/0x3b8 [btrfs]
CPU: 2 UID: 0 PID: 3020984 Comm: kworker/u24:1 Tainted: G OE 6.13.0-rc1-custom+ #89
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs]
pc : can_finish_ordered_extent+0x370/0x3b8 [btrfs]
lr : can_finish_ordered_extent+0x1ec/0x3b8 [btrfs]
Call trace:
can_finish_ordered_extent+0x370/0x3b8 [btrfs] (P)
can_finish_ordered_extent+0x1ec/0x3b8 [btrfs] (L)
btrfs_mark_ordered_io_finished+0x130/0x2b8 [btrfs]
extent_writepage+0x10c/0x3b8 [btrfs]
extent_write_cache_pages+0x21c/0x4e8 [btrfs]
btrfs_writepages+0x94/0x160 [btrfs]
do_writepages+0x74/0x190
filemap_fdatawrite_wbc+0x74/0xa0
start_delalloc_inodes+0x17c/0x3b0 [btrfs]
btrfs_start_delalloc_roots+0x17c/0x288 [btrfs]
shrink_delalloc+0x11c/0x280 [btrfs]
flush_space+0x288/0x328 [btrfs]
btrfs_async_reclaim_data_space+0x180/0x228 [btrfs]
process_one_work+0x228/0x680
worker_thread+0x1bc/0x360
kthread+0x100/0x118
ret_from_fork+0x10/0x20
---[ end trace 0000000000000000 ]---
BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1605632 OE len=16384 to_dec=16384 left=0
BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1622016 OE len=12288 to_dec=12288 left=0
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1634304 OE len=8192 to_dec=4096 left=0
CPU: 1 UID: 0 PID: 3286940 Comm: kworker/u24:3 Tainted: G W OE 6.13.0-rc1-custom+ #89
Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
Workqueue: btrfs_work_helper [btrfs] (btrfs-endio-write)
pstate: 404000c5 (nZcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : process_one_work+0x110/0x680
lr : worker_thread+0x1bc/0x360
Call trace:
process_one_work+0x110/0x680 (P)
worker_thread+0x1bc/0x360 (L)
worker_thread+0x1bc/0x360
kthread+0x100/0x118
ret_from_fork+0x10/0x20
Code: f84086a1 f9000fe1 53041c21 b9003361 (f9400661)
---[ end trace 0000000000000000 ]---
Kernel panic - not syncing: Oops: Fatal exception
SMP: stopping secondary CPUs
SMP: failed to stop secondary CPUs 2-3
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: 0x275bb9540000 from 0xffff800080000000
PHYS_OFFSET: 0xffff8fbba0000000
CPU features: 0x100,00000070,00801250,8201720b
[CAUSE]
The above warning is triggered immediately after the delalloc range
failure, this happens in the following sequence:
- Range [1568K, 1636K) is dirty
1536K 1568K 1600K 1636K 1664K
| |/////////|////////| |
Where 1536K, 1600K and 1664K are page boundaries (64K page size)
- Enter extent_writepage() for page 1536K
- Enter run_delalloc_nocow() with locked page 1536K and range
[1568K, 1636K)
This is due to the inode having preallocated extents.
- Enter cow_file_range() with locked page 1536K and range
[1568K, 1636K)
- btrfs_reserve_extent() only reserved two extents
The main loop of cow_file_range() only reserved two data extents,
Now we have:
1536K 1568K 1600K 1636K 1664K
| |<-->|<--->|/|///////| |
1584K 1596K
Range [1568K, 1596K) has an ordered extent reserved.
- btrfs_reserve_extent() failed inside cow_file_range() for file offset
1596K
This is already a bug in our space reservation code, but for now let's
focus on the error handling path.
Now cow_file_range() returned -ENOSPC.
- btrfs_run_delalloc_range() do error cleanup <<< ROOT CAUSE
Call btrfs_cleanup_ordered_extents() with locked folio 1536K and range
[1568K, 1636K)
Function btrfs_cleanup_ordered_extents() normally needs to skip the
ranges inside the folio, as it will normally be cleaned up by
extent_writepage().
Such split error handling is already problematic in the first place.
What's worse is the folio range skipping itself, which is not taking
subpage cases into consideration at all, it will only skip the range
if the page start >= the range start.
In our case, the page start < the range start, since for subpage cases
we can have delalloc ranges inside the folio but not covering the
folio.
So it doesn't skip the page range at all.
This means all the ordered extents, both [1568K, 1584K) and
[1584K, 1596K) will be marked as IOERR.
And these two ordered extents have no more pending ios, they are marked
finished, and *QUEUED* to be deleted from the io tree.
- extent_writepage() do error cleanup
Call btrfs_mark_ordered_io_finished() for the range [1536K, 1600K).
Although ranges [1568K, 1584K) and [1584K, 1596K) are finished, the
deletion from io tree is async, it may or may not happen at this
time.
If the ranges have not yet been removed, we will do double cleaning on
those ranges, triggering the above ordered extent warnings.
In theory there are other bugs, like the cleanup in extent_writepage()
can cause double accounting on ranges that are submitted asynchronously
(compression for example).
But that's much harder to trigger because normally we do not mix regular
and compression delalloc ranges.
[FIX]
The folio range split is already buggy and not subpage compatible, it
was introduced a long time ago where subpage support was not even considered.
So instead of splitting the ordered extents cleanup into the folio range
and out of folio range, do all the cleanup inside writepage_delalloc().
- Pass @NULL as locked_folio for btrfs_cleanup_ordered_extents() in
btrfs_run_delalloc_range()
- Skip the btrfs_cleanup_ordered_extents() if writepage_delalloc()
failed
So all ordered extents are only cleaned up by
btrfs_run_delalloc_range().
- Handle the ranges that already have ordered extents allocated
If part of the folio already has ordered extent allocated, and
btrfs_run_delalloc_range() failed, we also need to cleanup that range.
Now we have a concentrated error handling for ordered extents during
btrfs_run_delalloc_range().
Fixes: d1051d6ebf8e ("btrfs: Fix error handling in btrfs_cleanup_ordered_extents")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
We have several places explicitly calling btrfs_mark_buffer_dirty() but
that is not necessarily since the target leaf came from a path that was
obtained for a btree search function that modifies the btree, something
like btrfs_insert_empty_item() or anything else that ends up calling
btrfs_search_slot() with a value of 1 for its 'cow' argument.
These just make the code more verbose, confusing and add a little extra
overhead and well as increase the module's text size, so remove them.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
During renames we are grouping transaction aborts that can be due to a
failure of one of several function calls. While this makes the code less
verbose, it makes it harder to debug as we end up not knowing from which
function call we got an error.
So change this to trigger a transaction abort after each function call
failure, so that when we get a transaction abort message we know exactly
which function call failed, helping us to debug issues.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Instead of passing a root and an objectid which matches an inode number,
pass the inode instead, since the root is always the root associated to
the inode and the objectid is the number of that inode.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
All callers of can_nocow_extent() now pass a value of false for its
'strict' argument, making it redundant. So remove the argument from
can_nocow_extent() as well as can_nocow_file_extent(),
btrfs_cross_ref_exist() and check_committed_ref(), because this
argument was used just to influence the behavior of check_committed_ref().
Also remove the 'strict' field from struct can_nocow_file_extent_args,
which is now always false as well, as its value is taken from the
argument to can_nocow_extent().
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Since commit e1e577aafe41 ("btrfs: store fs_info in space_info"), we have
the fs_info in a space_info. So, we can drop fs_info argument from
btrfs_update_space_info_*. There is no behavior change.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes that accumulated over the last two weeks, fixing some
user reported problems:
- swapfile fixes:
- conditional reschedule in the activation loop
- fix race with memory mapped file when activating
- make activation loop interruptible
- rework and fix extent sharing checks
- folio fixes:
- in send, recheck folio mapping after unlock
- in relocation, recheck folio mapping after unlock
- fix waiting for encoded read io_uring requests
- fix transaction atomicity when enabling simple quotas
- move COW block trace point before the block gets freed
- print various sizes in sysfs with correct endianity"
* tag 'for-6.13-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: sysfs: fix direct super block member reads
btrfs: fix transaction atomicity bug when enabling simple quotas
btrfs: avoid monopolizing a core when activating a swap file
btrfs: allow swap activation to be interruptible
btrfs: fix swap file activation failure due to extents that used to be shared
btrfs: fix race with memory mapped writes when activating swap file
btrfs: check folio mapping after unlock in put_file_data()
btrfs: check folio mapping after unlock in relocate_one_folio()
btrfs: fix use-after-free when COWing tree bock and tracing is enabled
btrfs: fix use-after-free waiting for encoded read endios
|
|
During swap activation we iterate over the extents of a file and we can
have many thousands of them, so we can end up in a busy loop monopolizing
a core. Avoid this by doing a voluntary reschedule after processing each
extent.
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
During swap activation we iterate over the extents of a file, then do
several checks for each extent, some of which may take some significant
time such as checking if an extent is shared. Since a file can have
many thousands of extents, this can be a very slow operation and it's
currently not interruptible. I had a bug during development of a previous
patch that resulted in an infinite loop when iterating the extents, so
a core was busy looping and I couldn't cancel the operation, which is very
annoying and requires a reboot. So make the loop interruptible by checking
for fatal signals at the end of each iteration and stopping immediately if
there is one.
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
When activating a swap file, to determine if an extent is shared we use
can_nocow_extent(), which ends up at btrfs_cross_ref_exist(). That helper
is meant to be quick because it's used in the NOCOW write path, when
flushing delalloc and when doing a direct IO write, however it does return
some false positives, meaning it may indicate that an extent is shared
even if it's no longer the case. For the write path this is fine, we just
do a unnecessary COW operation instead of doing a more rigorous check
which would be too heavy (calling btrfs_is_data_extent_shared()).
However when activating a swap file, the false positives simply result
in a failure, which is confusing for users/applications. One particular
case where this happens is when a data extent only has 1 reference but
that reference is not inlined in the extent item located in the extent
tree - this happens when we create more than 33 references for an extent
and then delete those 33 references plus every other non-inline reference
except one. The function check_committed_ref() assumes that if the size
of an extent item doesn't match the size of struct btrfs_extent_item
plus the size of an inline reference (plus an owner reference in case
simple quotas are enabled), then the extent is shared - that is not the
case however, we can have a single reference but it's not inlined - the
reason we do this is to be fast and avoid inspecting non-inline references
which may be located in another leaf of the extent tree, slowing down
write paths.
The following test script reproduces the bug:
$ cat test.sh
#!/bin/bash
DEV=/dev/sdi
MNT=/mnt/sdi
NUM_CLONES=50
umount $DEV &> /dev/null
run_test()
{
local sync_after_add_reflinks=$1
local sync_after_remove_reflinks=$2
mkfs.btrfs -f $DEV > /dev/null
#mkfs.xfs -f $DEV > /dev/null
mount $DEV $MNT
touch $MNT/foo
chmod 0600 $MNT/foo
# On btrfs the file must be NOCOW.
chattr +C $MNT/foo &> /dev/null
xfs_io -s -c "pwrite -b 1M 0 1M" $MNT/foo
mkswap $MNT/foo
for ((i = 1; i <= $NUM_CLONES; i++)); do
touch $MNT/foo_clone_$i
chmod 0600 $MNT/foo_clone_$i
# On btrfs the file must be NOCOW.
chattr +C $MNT/foo_clone_$i &> /dev/null
cp --reflink=always $MNT/foo $MNT/foo_clone_$i
done
if [ $sync_after_add_reflinks -ne 0 ]; then
# Flush delayed refs and commit current transaction.
sync -f $MNT
fi
# Remove the original file and all clones except the last.
rm -f $MNT/foo
for ((i = 1; i < $NUM_CLONES; i++)); do
rm -f $MNT/foo_clone_$i
done
if [ $sync_after_remove_reflinks -ne 0 ]; then
# Flush delayed refs and commit current transaction.
sync -f $MNT
fi
# Now use the last clone as a swap file. It should work since
# its extent are not shared anymore.
swapon $MNT/foo_clone_${NUM_CLONES}
swapoff $MNT/foo_clone_${NUM_CLONES}
umount $MNT
}
echo -e "\nTest without sync after creating and removing clones"
run_test 0 0
echo -e "\nTest with sync after creating clones"
run_test 1 0
echo -e "\nTest with sync after removing clones"
run_test 0 1
echo -e "\nTest with sync after creating and removing clones"
run_test 1 1
Running the test:
$ ./test.sh
Test without sync after creating and removing clones
wrote 1048576/1048576 bytes at offset 0
1 MiB, 1 ops; 0.0017 sec (556.793 MiB/sec and 556.7929 ops/sec)
Setting up swapspace version 1, size = 1020 KiB (1044480 bytes)
no label, UUID=a6b9c29e-5ef4-4689-a8ac-bc199c750f02
swapon: /mnt/sdi/foo_clone_50: swapon failed: Invalid argument
swapoff: /mnt/sdi/foo_clone_50: swapoff failed: Invalid argument
Test with sync after creating clones
wrote 1048576/1048576 bytes at offset 0
1 MiB, 1 ops; 0.0036 sec (271.739 MiB/sec and 271.7391 ops/sec)
Setting up swapspace version 1, size = 1020 KiB (1044480 bytes)
no label, UUID=5e9008d6-1f7a-4948-a1b4-3f30aba20a33
swapon: /mnt/sdi/foo_clone_50: swapon failed: Invalid argument
swapoff: /mnt/sdi/foo_clone_50: swapoff failed: Invalid argument
Test with sync after removing clones
wrote 1048576/1048576 bytes at offset 0
1 MiB, 1 ops; 0.0103 sec (96.665 MiB/sec and 96.6651 ops/sec)
Setting up swapspace version 1, size = 1020 KiB (1044480 bytes)
no label, UUID=916c2740-fa9f-4385-9f06-29c3f89e4764
Test with sync after creating and removing clones
wrote 1048576/1048576 bytes at offset 0
1 MiB, 1 ops; 0.0031 sec (314.268 MiB/sec and 314.2678 ops/sec)
Setting up swapspace version 1, size = 1020 KiB (1044480 bytes)
no label, UUID=06aab1dd-4d90-49c0-bd9f-3a8db4e2f912
swapon: /mnt/sdi/foo_clone_50: swapon failed: Invalid argument
swapoff: /mnt/sdi/foo_clone_50: swapoff failed: Invalid argument
Fix this by reworking btrfs_swap_activate() to instead of using extent
maps and checking for shared extents with can_nocow_extent(), iterate
over the inode's file extent items and use the accurate
btrfs_is_data_extent_shared().
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
When activating the swap file we flush all delalloc and wait for ordered
extent completion, so that we don't miss any delalloc and extents before
we check that the file's extent layout is usable for a swap file and
activate the swap file. We are called with the inode's VFS lock acquired,
so we won't race with buffered and direct IO writes, however we can still
race with memory mapped writes since they don't acquire the inode's VFS
lock. The race window is between flushing all delalloc and locking the
whole file's extent range, since memory mapped writes lock an extent range
with the length of a page.
Fix this by acquiring the inode's mmap lock before we flush delalloc.
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Fix a use-after-free in the I/O completion path for encoded reads by
using a completion instead of a wait_queue for synchronizing the
destruction of 'struct btrfs_encoded_read_private'.
Fixes: 1881fba89bd5 ("btrfs: add BTRFS_IOC_ENCODED_READ ioctl")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes. Apart from the one liners and updated bio splitting
error handling there's a fix for subvolume mount with different flags.
This was known and fixed for some time but I've delayed it to give it
more testing.
- fix unbalanced locking when swapfile activation fails when the
subvolume gets deleted in the meantime
- add btrfs error handling after bio_split() calls that got error
handling recently
- during unmount, flush delalloc workers at the right time before the
cleaner thread is shut down
- fix regression in buffered write folio conversion, explicitly wait
for writeback as FGP_STABLE flag is currently a no-op on btrfs
- handle race in subvolume mount with different flags, the conversion
to the new mount API did not handle the case where multiple
subvolumes get mounted in parallel, which is a distro use case"
* tag 'for-6.13-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: flush delalloc workers queue before stopping cleaner kthread during unmount
btrfs: handle bio_split() errors
btrfs: properly wait for writeback before buffered write
btrfs: fix missing snapshot drew unlock when root is dead during swap activation
btrfs: fix mount failure due to remount races
|
|
When activating a swap file we acquire the root's snapshot drew lock and
then check if the root is dead, failing and returning with -EPERM if it's
dead but without unlocking the root's snapshot lock. Fix this by adding
the missing unlock.
Fixes: 60021bd754c6 ("btrfs: prevent subvol with swapfile from being deleted")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- add lockdep annotations for io_uring/encoded read integration, inode
lock is held when returning to userspace
- properly reflect experimental config option to sysfs
- handle NULL root in case the rescue mode accepts invalid/damaged tree
roots (rescue=ibadroot)
- regression fix of a deadlock between transaction and extent locks
- fix pending bio accounting bug in encoded read ioctl
- fix NOWAIT mode when checking references for NOCOW files
- fix use-after-free in a rb-tree cleanup in ref-verify debugging tool
* tag 'for-6.13-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fix lockdep warnings on io_uring encoded reads
btrfs: ref-verify: fix use-after-free after invalid ref action
btrfs: add a sanity check for btrfs root in btrfs_search_slot()
btrfs: don't loop for nowait writes when checking for cross references
btrfs: sysfs: advertise experimental features only if CONFIG_BTRFS_EXPERIMENTAL=y
btrfs: fix deadlock between transaction commits and extent locks
btrfs: fix use-after-free in btrfs_encoded_read_endio()
|
|
When running a workload with fsstress and duperemove (generic/561) we can
hit a deadlock related to transaction commits and locking extent ranges,
as described below.
Task A hanging during a transaction commit, waiting for all other writers
to complete:
[178317.334817] INFO: task fsstress:555623 blocked for more than 120 seconds.
[178317.335693] Not tainted 6.12.0-rc6-btrfs-next-179+ #1
[178317.336528] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[178317.337673] task:fsstress state:D stack:0 pid:555623 tgid:555623 ppid:555620 flags:0x00004002
[178317.337679] Call Trace:
[178317.337681] <TASK>
[178317.337685] __schedule+0x364/0xbe0
[178317.337691] schedule+0x26/0xa0
[178317.337695] btrfs_commit_transaction+0x5c5/0x1050 [btrfs]
[178317.337769] ? start_transaction+0xc4/0x800 [btrfs]
[178317.337815] ? __pfx_autoremove_wake_function+0x10/0x10
[178317.337819] btrfs_mksubvol+0x381/0x640 [btrfs]
[178317.337878] btrfs_mksnapshot+0x7a/0xb0 [btrfs]
[178317.337935] __btrfs_ioctl_snap_create+0x1bb/0x1d0 [btrfs]
[178317.337995] btrfs_ioctl_snap_create_v2+0x103/0x130 [btrfs]
[178317.338053] btrfs_ioctl+0x29b/0x2a90 [btrfs]
[178317.338118] ? kmem_cache_alloc_noprof+0x5f/0x2c0
[178317.338126] ? getname_flags+0x45/0x1f0
[178317.338133] ? _raw_spin_unlock+0x15/0x30
[178317.338145] ? __x64_sys_ioctl+0x88/0xc0
[178317.338149] __x64_sys_ioctl+0x88/0xc0
[178317.338152] do_syscall_64+0x4a/0x110
[178317.338160] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[178317.338190] RIP: 0033:0x7f13c28e271b
Which corresponds to line 2361 of transaction.c:
$ cat -n fs/btrfs/transaction.c
(...)
2162 int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
2163 {
(...)
2349 spin_lock(&fs_info->trans_lock);
2350 add_pending_snapshot(trans);
2351 cur_trans->state = TRANS_STATE_COMMIT_DOING;
2352 spin_unlock(&fs_info->trans_lock);
2353
2354 /*
2355 * The thread has started/joined the transaction thus it holds the
2356 * lockdep map as a reader. It has to release it before acquiring the
2357 * lockdep map as a writer.
2358 */
2359 btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
2360 btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);
2361 wait_event(cur_trans->writer_wait,
2362 atomic_read(&cur_trans->num_writers) == 1);
(...)
The transaction is in the TRANS_STATE_COMMIT_DOING state and so it's
waiting for all other existing writers to complete and release their
transaction handle.
Task B is running ordered extent completion and blocked waiting to lock an
extent range in an inode's io tree:
[178317.327411] INFO: task kworker/u48:8:554545 blocked for more than 120 seconds.
[178317.328630] Not tainted 6.12.0-rc6-btrfs-next-179+ #1
[178317.329635] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[178317.330872] task:kworker/u48:8 state:D stack:0 pid:554545 tgid:554545 ppid:2 flags:0x00004000
[178317.330878] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
[178317.330944] Call Trace:
[178317.330945] <TASK>
[178317.330947] __schedule+0x364/0xbe0
[178317.330952] schedule+0x26/0xa0
[178317.330955] __lock_extent+0x337/0x3a0 [btrfs]
[178317.331014] ? __pfx_autoremove_wake_function+0x10/0x10
[178317.331017] btrfs_finish_one_ordered+0x47a/0xaa0 [btrfs]
[178317.331074] ? psi_group_change+0x132/0x2d0
[178317.331078] btrfs_work_helper+0xbd/0x370 [btrfs]
[178317.331140] process_scheduled_works+0xd3/0x460
[178317.331144] ? __pfx_worker_thread+0x10/0x10
[178317.331146] worker_thread+0x121/0x250
[178317.331149] ? __pfx_worker_thread+0x10/0x10
[178317.331151] kthread+0xe9/0x120
[178317.331154] ? __pfx_kthread+0x10/0x10
[178317.331157] ret_from_fork+0x2d/0x50
[178317.331159] ? __pfx_kthread+0x10/0x10
[178317.331162] ret_from_fork_asm+0x1a/0x30
This extent range locking happens after joining the current transaction,
so task A is waiting for task B to release its transaction handle
(decrementing the transaction's num_writers counter).
Task C while doing a fiemap it tries to join the current transaction:
[242682.812815] task:pool state:D stack:0 pid:560767 tgid:560724 ppid:555622 flags:0x00004006
[242682.812827] Call Trace:
[242682.812856] <TASK>
[242682.812864] __schedule+0x364/0xbe0
[242682.812879] ? _raw_spin_unlock_irqrestore+0x23/0x40
[242682.812897] schedule+0x26/0xa0
[242682.812909] wait_current_trans+0xd6/0x130 [btrfs]
[242682.813148] ? __pfx_autoremove_wake_function+0x10/0x10
[242682.813162] start_transaction+0x3d4/0x800 [btrfs]
[242682.813399] btrfs_is_data_extent_shared+0xd2/0x440 [btrfs]
[242682.813723] fiemap_process_hole+0x2a2/0x300 [btrfs]
[242682.813995] extent_fiemap+0x9b8/0xb80 [btrfs]
[242682.814249] btrfs_fiemap+0x78/0xc0 [btrfs]
[242682.814501] do_vfs_ioctl+0x2db/0xa50
[242682.814519] __x64_sys_ioctl+0x6a/0xc0
[242682.814531] do_syscall_64+0x4a/0x110
[242682.814544] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[242682.814556] RIP: 0033:0x7efff595e71b
It tries to join the current transaction, but it can't because the
transaction is in the TRANS_STATE_COMMIT_DOING state, so
join_transaction() returns -EBUSY to start_transaction() and makes it
wait for the current transaction to complete. And while it's waiting
for the transaction to complete, it's holding an extent range locked
in the same inode that task B is operating, which causes a deadlock
between these 3 tasks. The extent range for the inode was locked at
the start of the fiemap operation, early at extent_fiemap().
In short these tasks deadlock because:
1) Task A is waiting for task B to release its transaction handle;
2) Task B is waiting to lock an extent range for an inode while holding a
transaction handle open;
3) Task C is waiting for the current transaction to complete (for task A
to finish the transaction commit) while holding the extent range for
the inode locked, so task B can't progress and release its transaction
handle.
This results in an ABBA deadlock involving transaction commits and extent
locks. Extent locks are higher level locks, like inode VFS locks, and
should always be acquired before joining or starting a transaction, but
recently commit 2206265f41e9 ("btrfs: remove code duplication in ordered
extent finishing") accidentally changed btrfs_finish_one_ordered() to do
the transaction join before locking the extent range.
Fix this by making sure that btrfs_finish_one_ordered() always locks the
extent before joining a transaction and add an explicit comment about the
need for this order.
Fixes: 2206265f41e9 ("btrfs: remove code duplication in ordered extent finishing")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Shinichiro reported the following use-after free that sometimes is
happening in our CI system when running fstests' btrfs/284 on a TCMU
runner device:
BUG: KASAN: slab-use-after-free in lock_release+0x708/0x780
Read of size 8 at addr ffff888106a83f18 by task kworker/u80:6/219
CPU: 8 UID: 0 PID: 219 Comm: kworker/u80:6 Not tainted 6.12.0-rc6-kts+ #15
Hardware name: Supermicro Super Server/X11SPi-TF, BIOS 3.3 02/21/2020
Workqueue: btrfs-endio btrfs_end_bio_work [btrfs]
Call Trace:
<TASK>
dump_stack_lvl+0x6e/0xa0
? lock_release+0x708/0x780
print_report+0x174/0x505
? lock_release+0x708/0x780
? __virt_addr_valid+0x224/0x410
? lock_release+0x708/0x780
kasan_report+0xda/0x1b0
? lock_release+0x708/0x780
? __wake_up+0x44/0x60
lock_release+0x708/0x780
? __pfx_lock_release+0x10/0x10
? __pfx_do_raw_spin_lock+0x10/0x10
? lock_is_held_type+0x9a/0x110
_raw_spin_unlock_irqrestore+0x1f/0x60
__wake_up+0x44/0x60
btrfs_encoded_read_endio+0x14b/0x190 [btrfs]
btrfs_check_read_bio+0x8d9/0x1360 [btrfs]
? lock_release+0x1b0/0x780
? trace_lock_acquire+0x12f/0x1a0
? __pfx_btrfs_check_read_bio+0x10/0x10 [btrfs]
? process_one_work+0x7e3/0x1460
? lock_acquire+0x31/0xc0
? process_one_work+0x7e3/0x1460
process_one_work+0x85c/0x1460
? __pfx_process_one_work+0x10/0x10
? assign_work+0x16c/0x240
worker_thread+0x5e6/0xfc0
? __pfx_worker_thread+0x10/0x10
kthread+0x2c3/0x3a0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x31/0x70
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Allocated by task 3661:
kasan_save_stack+0x30/0x50
kasan_save_track+0x14/0x30
__kasan_kmalloc+0xaa/0xb0
btrfs_encoded_read_regular_fill_pages+0x16c/0x6d0 [btrfs]
send_extent_data+0xf0f/0x24a0 [btrfs]
process_extent+0x48a/0x1830 [btrfs]
changed_cb+0x178b/0x2ea0 [btrfs]
btrfs_ioctl_send+0x3bf9/0x5c20 [btrfs]
_btrfs_ioctl_send+0x117/0x330 [btrfs]
btrfs_ioctl+0x184a/0x60a0 [btrfs]
__x64_sys_ioctl+0x12e/0x1a0
do_syscall_64+0x95/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Freed by task 3661:
kasan_save_stack+0x30/0x50
kasan_save_track+0x14/0x30
kasan_save_free_info+0x3b/0x70
__kasan_slab_free+0x4f/0x70
kfree+0x143/0x490
btrfs_encoded_read_regular_fill_pages+0x531/0x6d0 [btrfs]
send_extent_data+0xf0f/0x24a0 [btrfs]
process_extent+0x48a/0x1830 [btrfs]
changed_cb+0x178b/0x2ea0 [btrfs]
btrfs_ioctl_send+0x3bf9/0x5c20 [btrfs]
_btrfs_ioctl_send+0x117/0x330 [btrfs]
btrfs_ioctl+0x184a/0x60a0 [btrfs]
__x64_sys_ioctl+0x12e/0x1a0
do_syscall_64+0x95/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
The buggy address belongs to the object at ffff888106a83f00
which belongs to the cache kmalloc-rnd-07-96 of size 96
The buggy address is located 24 bytes inside of
freed 96-byte region [ffff888106a83f00, ffff888106a83f60)
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888106a83800 pfn:0x106a83
flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff)
page_type: f5(slab)
raw: 0017ffffc0000000 ffff888100053680 ffffea0004917200 0000000000000004
raw: ffff888106a83800 0000000080200019 00000001f5000000 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888106a83e00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff888106a83e80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff888106a83f00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff888106a83f80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff888106a84000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Further analyzing the trace and the crash dump's vmcore file shows that
the wake_up() call in btrfs_encoded_read_endio() is calling wake_up() on
the wait_queue that is in the private data passed to the end_io handler.
Commit 4ff47df40447 ("btrfs: move priv off stack in
btrfs_encoded_read_regular_fill_pages()") moved 'struct
btrfs_encoded_read_private' off the stack.
Before that commit one can see a corruption of the private data when
analyzing the vmcore after a crash:
*(struct btrfs_encoded_read_private *)0xffff88815626eec8 = {
.wait = (wait_queue_head_t){
.lock = (spinlock_t){
.rlock = (struct raw_spinlock){
.raw_lock = (arch_spinlock_t){
.val = (atomic_t){
.counter = (int)-2005885696,
},
.locked = (u8)0,
.pending = (u8)157,
.locked_pending = (u16)40192,
.tail = (u16)34928,
},
.magic = (unsigned int)536325682,
.owner_cpu = (unsigned int)29,
.owner = (void *)__SCT__tp_func_btrfs_transaction_commit+0x0 = 0x0,
.dep_map = (struct lockdep_map){
.key = (struct lock_class_key *)0xffff8881575a3b6c,
.class_cache = (struct lock_class *[2]){ 0xffff8882a71985c0, 0xffffea00066f5d40 },
.name = (const char *)0xffff88815626f100 = "",
.wait_type_outer = (u8)37,
.wait_type_inner = (u8)178,
.lock_type = (u8)154,
},
},
.__padding = (u8 [24]){ 0, 157, 112, 136, 50, 174, 247, 31, 29 },
.dep_map = (struct lockdep_map){
.key = (struct lock_class_key *)0xffff8881575a3b6c,
.class_cache = (struct lock_class *[2]){ 0xffff8882a71985c0, 0xffffea00066f5d40 },
.name = (const char *)0xffff88815626f100 = "",
.wait_type_outer = (u8)37,
.wait_type_inner = (u8)178,
.lock_type = (u8)154,
},
},
.head = (struct list_head){
.next = (struct list_head *)0x112cca,
.prev = (struct list_head *)0x47,
},
},
.pending = (atomic_t){
.counter = (int)-1491499288,
},
.status = (blk_status_t)130,
}
Here we can see several indicators of in-memory data corruption, e.g. the
large negative atomic values of ->pending or
->wait->lock->rlock->raw_lock->val, as well as the bogus spinlock magic
0x1ff7ae32 (decimal 536325682 above) instead of 0xdead4ead or the bogus
pointer values for ->wait->head.
To fix this, change atomic_dec_return() to atomic_dec_and_test() to fix the
corruption, as atomic_dec_return() is defined as two instructions on
x86_64, whereas atomic_dec_and_test() is defined as a single atomic
operation. This can lead to a situation where counter value is already
decremented but the if statement in btrfs_encoded_read_endio() is not
completely processed, i.e. the 0 test has not completed. If another thread
continues executing btrfs_encoded_read_regular_fill_pages() the
atomic_dec_return() there can see an already updated ->pending counter and
continues by freeing the private data. Continuing in the endio handler the
test for 0 succeeds and the wait_queue is woken up, resulting in a
use-after-free.
Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Suggested-by: Damien Le Moal <Damien.LeMoal@wdc.com>
Fixes: 1881fba89bd5 ("btrfs: add BTRFS_IOC_ENCODED_READ ioctl")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"Changes outside of btrfs: add io_uring command flag to track a dying
task (the rest will go via the block git tree).
User visible changes:
- wire encoded read (ioctl) to io_uring commands, this can be used on
itself, in the future this will allow 'send' to be asynchronous. As
a consequence, the encoded read ioctl can also work in non-blocking
mode
- new ioctl to wait for cleaned subvolumes, no need to use the
generic and root-only SEARCH_TREE ioctl, will be used by "btrfs
subvol sync"
- recognize different paths/symlinks for the same devices and don't
report them during rescanning, this can be observed with LVM or DM
- seeding device use case change, the sprout device (the one
capturing new writes) will not clear the read-only status of the
super block; this prevents accumulating space from deleted
snapshots
Performance improvements:
- reduce lock contention when traversing extent buffers
- reduce extent tree lock contention when searching for inline
backref
- switch from rb-trees to xarray for delayed ref tracking,
improvements due to better cache locality, branching factors and
more compact data structures
- enable extent map shrinker again (prevent memory exhaustion under
some types of IO load), reworked to run in a single worker thread
(there used to be problems causing long stalls under memory
pressure)
Core changes:
- raid-stripe-tree feature updates:
- make device replace and scrub work
- implement partial deletion of stripe extents
- new selftests
- split the config option BTRFS_DEBUG and add EXPERIMENTAL for
features that are experimental or with known problems so we don't
misuse debugging config for that
- subpage mode updates (sector < page):
- update compression implementations
- update writepage, writeback
- continued folio API conversions:
- buffered writes
- make buffered write copy one page at a time, preparatory work for
future integration with large folios, may cause performance drop
- proper locking of root item regarding starting send
- error handling improvements
- code cleanups and refactoring:
- dead code removal
- unused parameter reduction
- lockdep assertions"
* tag 'for-6.13-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (119 commits)
btrfs: send: check for read-only send root under critical section
btrfs: send: check for dead send root under critical section
btrfs: remove check for NULL fs_info at btrfs_folio_end_lock_bitmap()
btrfs: fix warning on PTR_ERR() against NULL device at btrfs_control_ioctl()
btrfs: fix a typo in btrfs_use_zone_append
btrfs: avoid superfluous calls to free_extent_map() in btrfs_encoded_read()
btrfs: simplify logic to decrement snapshot counter at btrfs_mksnapshot()
btrfs: remove hole from struct btrfs_delayed_node
btrfs: update stale comment for struct btrfs_delayed_ref_node::add_list
btrfs: add new ioctl to wait for cleaned subvolumes
btrfs: simplify range tracking in cow_file_range()
btrfs: remove conditional path allocation in btrfs_read_locked_inode()
btrfs: push cleanup into btrfs_read_locked_inode()
io_uring/cmd: let cmds to know about dying task
btrfs: add struct io_btrfs_cmd as type for io_uring_cmd_to_pdu()
btrfs: add io_uring command for encoded reads (ENCODED_READ ioctl)
btrfs: move priv off stack in btrfs_encoded_read_regular_fill_pages()
btrfs: don't sleep in btrfs_encoded_read() if IOCB_NOWAIT is set
btrfs: change btrfs_encoded_read() so that reading of extent is done by caller
btrfs: remove pointless iocb::ki_pos addition in btrfs_encoded_read()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs pagecache updates from Christian Brauner:
"Cleanup filesystem page flag usage: This continues the work to make
the mappedtodisk/owner_2 flag available to filesystems which don't use
buffer heads. Further patches remove uses of Private2. This brings us
very close to being rid of it entirely"
* tag 'vfs-6.13.pagecache' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
migrate: Remove references to Private2
ceph: Remove call to PagePrivate2()
btrfs: Switch from using the private_2 flag to owner_2
mm: Remove PageMappedToDisk
nilfs2: Convert nilfs_copy_buffer() to use folios
fs: Move clearing of mappedtodisk to buffer.c
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Features:
- Fixup and improve NLM and kNFSD file lock callbacks
Last year both GFS2 and OCFS2 had some work done to make their
locking more robust when exported over NFS. Unfortunately, part of
that work caused both NLM (for NFS v3 exports) and kNFSD (for
NFSv4.1+ exports) to no longer send lock notifications to clients
This in itself is not a huge problem because most NFS clients will
still poll the server in order to acquire a conflicted lock
It's important for NLM and kNFSD that they do not block their
kernel threads inside filesystem's file_lock implementations
because that can produce deadlocks. We used to make sure of this by
only trusting that posix_lock_file() can correctly handle blocking
lock calls asynchronously, so the lock managers would only setup
their file_lock requests for async callbacks if the filesystem did
not define its own lock() file operation
However, when GFS2 and OCFS2 grew the capability to correctly
handle blocking lock requests asynchronously, they started
signalling this behavior with EXPORT_OP_ASYNC_LOCK, and the check
for also trusting posix_lock_file() was inadvertently dropped, so
now most filesystems no longer produce lock notifications when
exported over NFS
Fix this by using an fop_flag which greatly simplifies the problem
and grooms the way for future uses by both filesystems and lock
managers alike
- Add a sysctl to delete the dentry when a file is removed instead of
making it a negative dentry
Commit 681ce8623567 ("vfs: Delete the associated dentry when
deleting a file") introduced an unconditional deletion of the
associated dentry when a file is removed. However, this led to
performance regressions in specific benchmarks, such as
ilebench.sum_operations/s, prompting a revert in commit
4a4be1ad3a6e ("Revert "vfs: Delete the associated dentry when
deleting a file""). This reintroduces the concept conditionally
through a sysctl
- Expand the statmount() system call:
* Report the filesystem subtype in a new fs_subtype field to
e.g., report fuse filesystem subtypes
* Report the superblock source in a new sb_source field
* Add a new way to return filesystem specific mount options in an
option array that returns filesystem specific mount options
separated by zero bytes and unescaped. This allows caller's to
retrieve filesystem specific mount options and immediately pass
them to e.g., fsconfig() without having to unescape or split
them
* Report security (LSM) specific mount options in a separate
security option array. We don't lump them together with
filesystem specific mount options as security mount options are
generic and most users aren't interested in them
The format is the same as for the filesystem specific mount
option array
- Support relative paths in fsconfig()'s FSCONFIG_SET_STRING command
- Optimize acl_permission_check() to avoid costly {g,u}id ownership
checks if possible
- Use smp_mb__after_spinlock() to avoid full smp_mb() in evict()
- Add synchronous wakeup support for ep_poll_callback.
Currently, epoll only uses wake_up() to wake up task. But sometimes
there are epoll users which want to use the synchronous wakeup flag
to give a hint to the scheduler, e.g., the Android binder driver.
So add a wake_up_sync() define, and use wake_up_sync() when sync is
true in ep_poll_callback()
Fixes:
- Fix kernel documentation for inode_insert5() and iget5_locked()
- Annotate racy epoll check on file->f_ep
- Make F_DUPFD_QUERY associative
- Avoid filename buffer overrun in initramfs
- Don't let statmount() return empty strings
- Add a cond_resched() to dump_user_range() to avoid hogging the CPU
- Don't query the device logical blocksize multiple times for hfsplus
- Make filemap_read() check that the offset is positive or zero
Cleanups:
- Various typo fixes
- Cleanup wbc_attach_fdatawrite_inode()
- Add __releases annotation to wbc_attach_and_unlock_inode()
- Add hugetlbfs tracepoints
- Fix various vfs kernel doc parameters
- Remove obsolete TODO comment from io_cancel()
- Convert wbc_account_cgroup_owner() to take a folio
- Fix comments for BANDWITH_INTERVAL and wb_domain_writeout_add()
- Reorder struct posix_acl to save 8 bytes
- Annotate struct posix_acl with __counted_by()
- Replace one-element array with flexible array member in freevxfs
- Use idiomatic atomic64_inc_return() in alloc_mnt_ns()"
* tag 'vfs-6.13.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
statmount: retrieve security mount options
vfs: make evict() use smp_mb__after_spinlock instead of smp_mb
statmount: add flag to retrieve unescaped options
fs: add the ability for statmount() to report the sb_source
writeback: wbc_attach_fdatawrite_inode out of line
writeback: add a __releases annoation to wbc_attach_and_unlock_inode
fs: add the ability for statmount() to report the fs_subtype
fs: don't let statmount return empty strings
fs:aio: Remove TODO comment suggesting hash or array usage in io_cancel()
hfsplus: don't query the device logical block size multiple times
freevxfs: Replace one-element array with flexible array member
fs: optimize acl_permission_check()
initramfs: avoid filename buffer overrun
fs/writeback: convert wbc_account_cgroup_owner to take a folio
acl: Annotate struct posix_acl with __counted_by()
acl: Realign struct posix_acl to save 8 bytes
epoll: Add synchronous wakeup support for ep_poll_callback
coredump: add cond_resched() to dump_user_range
mm/page-writeback.c: Fix comment of wb_domain_writeout_add()
mm/page-writeback.c: Update comment for BANDWIDTH_INTERVAL
...
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Change the control flow of btrfs_encoded_read() so that it doesn't call
free_extent_map() when we know that this has already been done.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Mark Harmstone <maharmstone@fb.com>
Suggested-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Simplify tracking of the range processed by using cur_alloc_size only to
store the reserved part that may fail to the allocated extent. Remove
the ram_size as well since it is always equal to cur_alloc_size in the
context. Advance the start in normal path until extent allocation
succeeds and keep the start unchanged in the error handling path.
Passed the fstest generic/475 test for a hundred times with quota
enabled. And a modified generic/475 test by removing the sleep time
for a hundred times. About one tenth of the tests do enter the error
handling path due to fail to reserve extent.
Suggested-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Haisu Wang <haisuwang@tencent.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Remove conditional path allocation from btrfs_read_locked_inode(). Add
an ASSERT(path) to indicate it should never be called with a NULL path.
Call btrfs_read_locked_inode() directly from btrfs_iget(). This causes
code duplication between btrfs_iget() and btrfs_iget_path(), but I
think this is justifiable as it removes the need for conditionally
allocating the path inside of btrfs_read_locked_inode(). This makes the
code easier to reason about and makes it clear who has the
responsibility of allocating and freeing the path.
Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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