Skip to content

Conversation

@kdave
Copy link
Member

@kdave kdave commented Feb 21, 2024

Keep this open, the build tests are hosted on github CI.

@kdave kdave changed the title Post rc5 build test Regular for-next build test Feb 22, 2024
@kdave kdave force-pushed the for-next branch 6 times, most recently from 2d4aefb to c9e380a Compare February 28, 2024 14:37
@kdave kdave force-pushed the for-next branch 6 times, most recently from c56343b to 1cab137 Compare March 5, 2024 17:23
@kdave kdave force-pushed the for-next branch 2 times, most recently from 6613f3c to b30a0ce Compare March 15, 2024 01:05
@kdave kdave force-pushed the for-next branch 6 times, most recently from d205ebd to c0bd9d9 Compare March 25, 2024 17:48
@kdave kdave force-pushed the for-next branch 4 times, most recently from 15022b1 to c22750c Compare March 28, 2024 02:04
@kdave kdave force-pushed the for-next branch 3 times, most recently from 28d9855 to e18d8ce Compare April 4, 2024 19:30
fdmanana and others added 12 commits January 12, 2026 15:11
There's no point in committing the transaction if we failed to insert the
balance item, since we haven't done anything else after we started/joined
the transaction. Also stop using two variables for tracking the return
value and use only 'ret'.

Reviewed-by: Daniel Vacek <neelx@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This function already dereferences 'inode' multiple times earlier,
making the additional NULL check at line 840 redundant since the
function would have crashed already if inode were NULL.

After commit 81cea6c ("btrfs: remove btrfs_bio::fs_info by
extracting it from btrfs_bio::inode"), the btrfs_bio::inode field is
mandatory for all btrfs_bio allocations and is guaranteed to be
non-NULL.

Simplify the condition for allocating dummy checksums for zoned
NODATASUM data by removing the unnecessary 'inode &&' check.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
Before btrfs-progs v6.16.1 release, mkfs.btrfs can leave free space tree
entries for deleted chunks:

  # mkfs.btrfs -f -O fst $dev
  # btrfs ins dump-tree -t chunk $dev
  btrfs-progs v6.16
  chunk tree
  leaf 22036480 items 4 free space 15781 generation 8 owner CHUNK_TREE
  leaf 22036480 flags 0x1(WRITTEN) backref revision 1
	 item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 16185 itemsize 98
	 item 1 key (FIRST_CHUNK_TREE CHUNK_ITEM 13631488) itemoff 16105 itemsize 80
	 ^^^ The first chunk is at 13631488
	 item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 22020096) itemoff 15993 itemsize 112
	 item 3 key (FIRST_CHUNK_TREE CHUNK_ITEM 30408704) itemoff 15881 itemsize 112

  # btrfs ins dump-tree -t free-space-tree $dev
  btrfs-progs v6.16
  free space tree key (FREE_SPACE_TREE ROOT_ITEM 0)
  leaf 30556160 items 13 free space 15918 generation 8 owner FREE_SPACE_TREE
  leaf 30556160 flags 0x1(WRITTEN) backref revision 1
	 item 0 key (1048576 FREE_SPACE_INFO 4194304) itemoff 16275 itemsize 8
		 free space info extent count 1 flags 0
	 item 1 key (1048576 FREE_SPACE_EXTENT 4194304) itemoff 16275 itemsize 0
		 free space extent
	 item 2 key (5242880 FREE_SPACE_INFO 8388608) itemoff 16267 itemsize 8
		 free space info extent count 1 flags 0
	 item 3 key (5242880 FREE_SPACE_EXTENT 8388608) itemoff 16267 itemsize 0
		 free space extent
	 ^^^ Above 4 items are all before the first chunk.
	 item 4 key (13631488 FREE_SPACE_INFO 8388608) itemoff 16259 itemsize 8
		 free space info extent count 1 flags 0
	 item 5 key (13631488 FREE_SPACE_EXTENT 8388608) itemoff 16259 itemsize 0
		 free space extent
	 ...

This can trigger btrfs check errors.

[CAUSE]
It's a bug in free space tree implementation of btrfs-progs, which
doesn't delete involved fst entries for the to-be-deleted chunk/block
group.

[ENHANCEMENT]
The mostly common fix is to clear the space cache and rebuild it, but
that requires a ro->rw remount which may not be possible for rootfs,
and also relies on users to use "clear_cache" mount option manually.

Here introduce a kernel fix for it, which will delete any entries that
is before the first block group automatically at the first RW mount.

For filesystems without such problem, the overhead is just a single tree
search and no modification to the free space tree, thus the overhead
should be minimal.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The function add_block_group_free_space() was renamed
btrfs_add_block_group_free_space() by commit 6fc5ef7 ("btrfs:
add btrfs prefix to free space tree exported functions").  Update
the comment accordingly.

Do some reorganization of the next few lines to keep the comment
within 80 characters.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In btrfs_read_locked_inode() if we fail to lookup the inode, we jump to
the 'out' label with a path that has a read locked leaf and then we call
iget_failed(). This can result in a ABBA deadlock, since iget_failed()
triggers inode eviction and that causes the release of the delayed inode,
which must lock the delayed inode's mutex, and a task updating a delayed
inode starts by taking the node's mutex and then modifying the inode's
subvolume btree.

Syzbot reported the following lockdep splat for this:

   ======================================================
   WARNING: possible circular locking dependency detected
   syzkaller #0 Not tainted
   ------------------------------------------------------
   btrfs-cleaner/8725 is trying to acquire lock:
   ffff0000d6826a48 (&delayed_node->mutex){+.+.}-{4:4}, at: __btrfs_release_delayed_node+0xa0/0x9b0 fs/btrfs/delayed-inode.c:290

   but task is already holding lock:
   ffff0000dbeba878 (btrfs-tree-00){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x44/0x2ec fs/btrfs/locking.c:145

   which lock already depends on the new lock.

   the existing dependency chain (in reverse order) is:

   -> #1 (btrfs-tree-00){++++}-{4:4}:
          __lock_release kernel/locking/lockdep.c:5574 [inline]
          lock_release+0x198/0x39c kernel/locking/lockdep.c:5889
          up_read+0x24/0x3c kernel/locking/rwsem.c:1632
          btrfs_tree_read_unlock+0xdc/0x298 fs/btrfs/locking.c:169
          btrfs_tree_unlock_rw fs/btrfs/locking.h:218 [inline]
          btrfs_search_slot+0xa6c/0x223c fs/btrfs/ctree.c:2133
          btrfs_lookup_inode+0xd8/0x38c fs/btrfs/inode-item.c:395
          __btrfs_update_delayed_inode+0x124/0xed0 fs/btrfs/delayed-inode.c:1032
          btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1118 [inline]
          __btrfs_commit_inode_delayed_items+0x15f8/0x1748 fs/btrfs/delayed-inode.c:1141
          __btrfs_run_delayed_items+0x1ac/0x514 fs/btrfs/delayed-inode.c:1176
          btrfs_run_delayed_items_nr+0x28/0x38 fs/btrfs/delayed-inode.c:1219
          flush_space+0x26c/0xb68 fs/btrfs/space-info.c:828
          do_async_reclaim_metadata_space+0x110/0x364 fs/btrfs/space-info.c:1158
          btrfs_async_reclaim_metadata_space+0x90/0xd8 fs/btrfs/space-info.c:1226
          process_one_work+0x7e8/0x155c kernel/workqueue.c:3263
          process_scheduled_works kernel/workqueue.c:3346 [inline]
          worker_thread+0x958/0xed8 kernel/workqueue.c:3427
          kthread+0x5fc/0x75c kernel/kthread.c:463
          ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844

   -> #0 (&delayed_node->mutex){+.+.}-{4:4}:
          check_prev_add kernel/locking/lockdep.c:3165 [inline]
          check_prevs_add kernel/locking/lockdep.c:3284 [inline]
          validate_chain kernel/locking/lockdep.c:3908 [inline]
          __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237
          lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868
          __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598
          __mutex_lock kernel/locking/mutex.c:760 [inline]
          mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812
          __btrfs_release_delayed_node+0xa0/0x9b0 fs/btrfs/delayed-inode.c:290
          btrfs_release_delayed_node fs/btrfs/delayed-inode.c:315 [inline]
          btrfs_remove_delayed_node+0x68/0x84 fs/btrfs/delayed-inode.c:1326
          btrfs_evict_inode+0x578/0xe28 fs/btrfs/inode.c:5587
          evict+0x414/0x928 fs/inode.c:810
          iput_final fs/inode.c:1914 [inline]
          iput+0x95c/0xad4 fs/inode.c:1966
          iget_failed+0xec/0x134 fs/bad_inode.c:248
          btrfs_read_locked_inode+0xe1c/0x1234 fs/btrfs/inode.c:4101
          btrfs_iget+0x1b0/0x264 fs/btrfs/inode.c:5837
          btrfs_run_defrag_inode fs/btrfs/defrag.c:237 [inline]
          btrfs_run_defrag_inodes+0x520/0xdc4 fs/btrfs/defrag.c:309
          cleaner_kthread+0x21c/0x418 fs/btrfs/disk-io.c:1516
          kthread+0x5fc/0x75c kernel/kthread.c:463
          ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844

   other info that might help us debug this:

    Possible unsafe locking scenario:

          CPU0                    CPU1
          ----                    ----
     rlock(btrfs-tree-00);
                                  lock(&delayed_node->mutex);
                                  lock(btrfs-tree-00);
     lock(&delayed_node->mutex);

    *** DEADLOCK ***

   1 lock held by btrfs-cleaner/8725:
    #0: ffff0000dbeba878 (btrfs-tree-00){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x44/0x2ec fs/btrfs/locking.c:145

   stack backtrace:
   CPU: 0 UID: 0 PID: 8725 Comm: btrfs-cleaner Not tainted syzkaller #0 PREEMPT
   Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
   Call trace:
    show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
    __dump_stack+0x30/0x40 lib/dump_stack.c:94
    dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
    dump_stack+0x1c/0x28 lib/dump_stack.c:129
    print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2043
    check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2175
    check_prev_add kernel/locking/lockdep.c:3165 [inline]
    check_prevs_add kernel/locking/lockdep.c:3284 [inline]
    validate_chain kernel/locking/lockdep.c:3908 [inline]
    __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237
    lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868
    __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598
    __mutex_lock kernel/locking/mutex.c:760 [inline]
    mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812
    __btrfs_release_delayed_node+0xa0/0x9b0 fs/btrfs/delayed-inode.c:290
    btrfs_release_delayed_node fs/btrfs/delayed-inode.c:315 [inline]
    btrfs_remove_delayed_node+0x68/0x84 fs/btrfs/delayed-inode.c:1326
    btrfs_evict_inode+0x578/0xe28 fs/btrfs/inode.c:5587
    evict+0x414/0x928 fs/inode.c:810
    iput_final fs/inode.c:1914 [inline]
    iput+0x95c/0xad4 fs/inode.c:1966
    iget_failed+0xec/0x134 fs/bad_inode.c:248
    btrfs_read_locked_inode+0xe1c/0x1234 fs/btrfs/inode.c:4101
    btrfs_iget+0x1b0/0x264 fs/btrfs/inode.c:5837
    btrfs_run_defrag_inode fs/btrfs/defrag.c:237 [inline]
    btrfs_run_defrag_inodes+0x520/0xdc4 fs/btrfs/defrag.c:309
    cleaner_kthread+0x21c/0x418 fs/btrfs/disk-io.c:1516
    kthread+0x5fc/0x75c kernel/kthread.c:463
    ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844

Fix this by releasing the path before calling iget_failed().

Reported-by: syzbot+c1c6edb02bea1da754d8@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/694530c2.a70a0220.207337.010d.GAE@google.com/
Fixes: 6967399 ("btrfs: push cleanup into btrfs_read_locked_inode()")
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If btrfs_insert_fs_root() fails, the tmp_root allocated by
btrfs_alloc_dummy_root() is leaked because its initial reference count
is not decremented.

Fix this by calling btrfs_put_root() unconditionally after
btrfs_insert_fs_root(). This ensures the local reference is always
dropped.

Also fix a copy-paste error in the error message where the subvolume
root insertion failure was incorrectly logged as "fs root".

Co-developed-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
Signed-off-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In test_rmap_blocks(), we have ret = 0 before checking the results. We need
to set it to -EINVAL, so that a mismatching result will return -EINVAL not
0.

Reviewed-by: Qu Wenruo <wqu@suse.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>
Currently for an inode that needs compression, even if there is a delalloc
range that is single fs block sized and can not be inlined, we will
still go through the compression path.

Then inside compress_file_range(), we have one extra check to reject
single block sized range, and fall back to regular uncompressed write.

This rejection is in fact a little too late, we have already allocated
memory to async_chunk, delayed the submission, just to fallback to the
same uncompressed write.

Change the behavior to reject such cases earlier at
inode_need_compress(), so for such single block sized range we won't
even bother trying to go through compress path.

And since the inline small block check is inside inode_need_compress()
and compress_file_range() also calls that function, we no longer need a
dedicate check inside compress_file_range().

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Before accessing the disk_bytenr field of a file extent item we need
to check if we are dealing with an inline extent.
This is because for inline extents their data starts at the offset of
the disk_bytenr field. So accessing the disk_bytenr
means we are accessing inline data or in case the inline data is less
than 8 bytes we can actually cause an invalid
memory access if this inline extent item is the first item in the leaf
or access metadata from other items.

Fixes: 82bfb2e ("Btrfs: incremental send, fix unnecessary hole writes for sparse files")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are two tests in btrfs_fs_closing() but checking the
BTRFS_FS_CLOSING_DONE bit is done only in one place
load_extent_tree_free(). As this is an inline we can reduce size of the
generated code. The types can be also changed to bool as this becomes a
simple condition.

   text    data     bss     dec     hex filename
1674006  146704   15560 1836270  1c04ee pre/btrfs.ko
1673772  146704   15560 1836036  1c0404 post/btrfs.ko

DELTA: -234

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The offload csum mode was introduced to allow developers to compare the
performance of generating checksum for data writes at different timings:

- During btrfs_submit_chunk()
  This is the most common one, if any of the following condition is met
  we go this path:

  * The csum is fast
    For now it's CRC32C and xxhash.

  * It's a synchronous write

  * Zoned

- Delay the checksum generation to a workqueue

However since commit dd57c78 ("btrfs: introduce
btrfs_bio::async_csum") we no longer need to bother any of them.

As if it's an experimental build, async checksum generation at the
background will be faster anyway.

And if not an experimental build, we won't even have the offload csum
mode support.

Considering the async csum will be the new default, let's remove the
offload csum mode code.

There will be no impact to end users, and offload csum mode is still
under experimental features.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When the user performs a btrfs mount, the block device is not set
correctly. The user sets the block size of the block device to 0x4000
by executing the BLKBSZSET command.
Since the block size change also changes the mapping->flags value, this
further affects the result of the mapping_min_folio_order() calculation.

Let's analyze the following two scenarios:

Scenario 1: Without executing the BLKBSZSET command, the block size is
0x1000, and mapping_min_folio_order() returns 0;

Scenario 2: After executing the BLKBSZSET command, the block size is
0x4000, and mapping_min_folio_order() returns 2.

do_read_cache_folio() allocates a folio before the BLKBSZSET command
is executed. This results in the allocated folio having an order value
of 0. Later, after BLKBSZSET is executed, the block size increases to
0x4000, and the mapping_min_folio_order() calculation result becomes 2.

This leads to two undesirable consequences:

1. filemap_add_folio() triggers a VM_BUG_ON_FOLIO(folio_order(folio) <
mapping_min_folio_order(mapping)) assertion.

2. The syzbot report [1] shows a null pointer dereference in
create_empty_buffers() due to a buffer head allocation failure.

Synchronization should be established based on the inode between the
BLKBSZSET command and read cache page to prevent inconsistencies in
block size or mapping flags before and after folio allocation.

[1]
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:create_empty_buffers+0x4d/0x480 fs/buffer.c:1694
Call Trace:
 folio_create_buffers+0x109/0x150 fs/buffer.c:1802
 block_read_full_folio+0x14c/0x850 fs/buffer.c:2403
 filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2496
 do_read_cache_folio+0x266/0x5c0 mm/filemap.c:4096
 do_read_cache_page mm/filemap.c:4162 [inline]
 read_cache_page_gfp+0x29/0x120 mm/filemap.c:4195
 btrfs_read_disk_super+0x192/0x500 fs/btrfs/volumes.c:1367

Reported-by: syzbot+b4a2af3000eaa84d95d5@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b4a2af3000eaa84d95d5
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
adam900710 and others added 4 commits January 12, 2026 18:40
The following new features are missing:

- Async checksum

- Shutdown ioctl and auto-degradation

- Larger block size support
  Which is dependent on larger folios.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu reported that generic/164 often fails because the read operations get
zeroes when it expects to either get all bytes with a value of 0x61 or
0x62. The issue stems from truncating the pages from the page cache
instead of invalidating, as truncating can zero page contents. This
zeroing is not just in case the range is not page sized (as it's commented
in truncate_inode_pages_range()) but also in case we are using large
folios, they need to be split and the splitting fails. Stealing Qu's
comment in the thread linked below:

  "We can have the following case:

	0          4K         8K         12K          16K
        |          |          |          |            |
        |<---- Extent A ----->|<----- Extent B ------>|

   The page size is still 4K, but the folio we got is 16K.

   Then if we remap the range for [8K, 16K), then
   truncate_inode_pages_range() will get the large folio 0 sized 16K,
   then call truncate_inode_partial_folio().

   Which later calls folio_zero_range() for the [8K, 16K) range first,
   then tries to split the folio into smaller ones to properly drop them
   from the cache.

   But if splitting failed (e.g. racing with other operations holding the
   filemap lock), the partially zeroed large folio will be kept, resulting
   the range [8K, 16K) being zeroed meanwhile the folio is still a 16K
   sized large one."

So instead of truncating, invalidate the page cache range with a call to
filemap_invalidate_inode(), which besides not doing any zeroing also
ensures that while it's invalidating folios, no new folios are added.

This helps ensure that buffered reads that happen while a reflink
operation is in progress always get either the whole old data (the one
before the reflink) or the whole new data, which is what generic/164
expects.

Link: https://lore.kernel.org/linux-btrfs/7fb9b44f-9680-4c22-a47f-6648cb109ddf@suse.com/
Reported-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
…iles()

Make the comment more detailed about why we need to flush delalloc and
wait for ordered extent completion before attempting to invalidate the
page cache.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In create_space_info(), the 'space_info' object is allocated at the
beginning of the function. However, there are two error paths where the
function returns an error code without freeing the allocated memory:

1. When create_space_info_sub_group() fails in zoned mode.
2. When btrfs_sysfs_add_space_info_type() fails.

In both cases, 'space_info' has not yet been added to the
fs_info->space_info list, resulting in a memory leak. Fix this by
adding an error handling label to kfree(space_info) before returning.

Fixes: 2be12ef ("btrfs: Separate space_info create/update")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are two main causes of holes inside btrfs_device:

- The single bytes member of last_flush_error
  Not only it's a single byte member, but we never really care about the
  exact error number.

- The @devt member
  Which is placed between two u64 members.

Shrink the size of btrfs_device by:

- Use a single bit flag for flush error
  Use BTRFS_DEV_STATE_FLUSH_FAILED so that we no longer need that
  dedicated member.

- Move @devt to the hole after dev_stat_values[]

This reduces the size of btrfs_device from 528 to exact 512 bytes for
x86_64.

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>
@kdave kdave force-pushed the for-next branch 2 times, most recently from f4cbd49 to 3eece6d Compare January 15, 2026 01:09
adam900710 and others added 6 commits January 15, 2026 03:43
[BUG]
There is a bug report where a heavily fuzzed fs is mounted with all
rescue mount options, which leads to the following warnings during
unmount:

  BTRFS: Transaction aborted (error -22)
  Modules linked in:
  CPU: 0 UID: 0 PID: 9758 Comm: repro.out Not tainted
  6.19.0-rc5-00002-gb71e635feefc #7 PREEMPT(full)
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
  RIP: 0010:find_free_extent_update_loop fs/btrfs/extent-tree.c:4208 [inline]
  RIP: 0010:find_free_extent+0x52f0/0x5d20 fs/btrfs/extent-tree.c:4611
  Call Trace:
   <TASK>
   btrfs_reserve_extent+0x2cd/0x790 fs/btrfs/extent-tree.c:4705
   btrfs_alloc_tree_block+0x1e1/0x10e0 fs/btrfs/extent-tree.c:5157
   btrfs_force_cow_block+0x578/0x2410 fs/btrfs/ctree.c:517
   btrfs_cow_block+0x3c4/0xa80 fs/btrfs/ctree.c:708
   btrfs_search_slot+0xcad/0x2b50 fs/btrfs/ctree.c:2130
   btrfs_truncate_inode_items+0x45d/0x2350 fs/btrfs/inode-item.c:499
   btrfs_evict_inode+0x923/0xe70 fs/btrfs/inode.c:5628
   evict+0x5f4/0xae0 fs/inode.c:837
   __dentry_kill+0x209/0x660 fs/dcache.c:670
   finish_dput+0xc9/0x480 fs/dcache.c:879
   shrink_dcache_for_umount+0xa0/0x170 fs/dcache.c:1661
   generic_shutdown_super+0x67/0x2c0 fs/super.c:621
   kill_anon_super+0x3b/0x70 fs/super.c:1289
   btrfs_kill_super+0x41/0x50 fs/btrfs/super.c:2127
   deactivate_locked_super+0xbc/0x130 fs/super.c:474
   cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318
   task_work_run+0x1d4/0x260 kernel/task_work.c:233
   exit_task_work include/linux/task_work.h:40 [inline]
   do_exit+0x694/0x22f0 kernel/exit.c:971
   do_group_exit+0x21c/0x2d0 kernel/exit.c:1112
   __do_sys_exit_group kernel/exit.c:1123 [inline]
   __se_sys_exit_group kernel/exit.c:1121 [inline]
   __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1121
   x64_sys_call+0x2210/0x2210 arch/x86/include/generated/asm/syscalls_64.h:232
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xe8/0xf80 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  RIP: 0033:0x44f639
  Code: Unable to access opcode bytes at 0x44f60f.
  RSP: 002b:00007ffc15c4e088 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
  RAX: ffffffffffffffda RBX: 00000000004c32f0 RCX: 000000000044f639
  RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000001
  RBP: 0000000000000001 R08: ffffffffffffffc0 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004c32f0
  R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
   </TASK>

Since rescue mount options will mark the full fs read-only, there should
be no new transaction triggered.

But during unmount we will evict all inodes, which can trigger a new
transaction, and triggers warnings on a heavily corrupted fs.

[CAUSE]
Btrfs allows new transaction even on a read-only fs, this is to allow
log replay happen even on read-only mounts, just like what ext4/xfs do.

However with rescue mount options, the fs is fully read-only and cannot
be remounted read-write, thus in that case we should also reject any new
transactions.

[FIX]
If we find the fs has rescue mount options, we should treat the fs as
error, so that no new transaction can be started.

Reported-by: Jiaming Zhang <r772577952@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CANypQFYw8Nt8stgbhoycFojOoUmt+BoZ-z8WJOZVxcogDdwm=Q@mail.gmail.com/
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_verify_dev_extents() iterates through the entire device tree
during mount to verify dev extents against chunks. Since this function
scans the whole tree, READA_FORWARD_ALWAYS is more appropriate than
READA_FORWARD.

While the device tree is typically small (a few hundred KB even for
multi-TB filesystems), using the correct readahead mode for full-tree
iteration is more consistent with the intended usage.

Signed-off-by: robbieko <robbieko@synology.com>
Signed-off-by: jinbaohong <jinbaohong@synology.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
…ref()

There is no need to BUG(), we can just return an error and log an error
message.

Reviewed-by: Boris Burkov <boris@bur.io>
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>
There is no need for an else branch to deal with an unexpected delayed ref
type. We can just change the previous branch to deal with this by checking
if the ref type is not BTRFS_EXTENT_OWNER_REF_KEY, since that branch is
useless as it only sets 'ret' to zero when it's already zero. So merge the
two branches.

Reviewed-by: Boris Burkov <boris@bur.io>
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>
We don't expect to get errors unless we have a corrupted fs, bad RAM or a
bug. So tag the error handling as unlikely.

This slightly reduces the module's text size on x86_64 using gcc 14.2.0-19
from Debian.

Before this change:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1939458	 172512	  15592	2127562	 2076ca	fs/btrfs/btrfs.ko

After this change:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1939398	 172512	  15592	2127502	 20768e	fs/btrfs/btrfs.ko

Reviewed-by: Boris Burkov <boris@bur.io>
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>
When the BLOCK_GROUP_TREE compat_ro flag is set, the extent root and
csum root fields are getting missed.

This is because EXTENT_TREE_V2 treated these differently, and when
they were split off this special-casing was mistakenly assigned to
BGT rather than the rump EXTENT_TREE_V2. There's no reason why the
existence of the block group tree should mean that we don't record the
details of the last commit's extent root and csum root.

Fix the code in backup_super_roots() so that the correct check gets
made.

Fixes: 1c56ab9 ("btrfs: separate BLOCK_GROUP_TREE compat RO flag from EXTENT_TREE_V2")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
adam900710 and others added 2 commits January 15, 2026 17:26
[BUG]
There is a bug report where after a dev-replace, the replace source
device with devid 4 is properly erased (dump tree shows it's the old
devid 4), but the target device is still using devid 0.

When the user tries to mount the fs degraded, the mount failed with the
following errors:

  BTRFS: device fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 devid 5 transid 1394395 /dev/sda (8:0) scanned by btrfs (261)
  BTRFS: device fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 devid 6 transid 1394395 /dev/sde (8:64) scanned by btrfs (261)
  BTRFS: device fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 devid 0 transid 1394395 /dev/sdd (8:48) scanned by btrfs (261)
  BTRFS: device fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 devid 3 transid 1394395 /dev/sdf (8:80) scanned by btrfs (261)
  BTRFS info (device sdd): first mount of filesystem 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9
  BTRFS info (device sdd): using crc32c (crc32c-intel) checksum algorithm
  BTRFS warning (device sdd): devid 4 uuid 01e2081c-9c2a-4071-b9f4-e1b27e571ff5 is missing
  BTRFS info (device sdd): bdev <missing disk> errs: wr 84994544, rd 15567, flush 65872, corrupt 0, gen 0
  BTRFS info (device sdd): bdev /dev/sdd errs: wr 71489901, rd 0, flush 30001, corrupt 0, gen 0
  BTRFS error (device sdd): replace without active item, run 'device scan --forget' on the target device
  BTRFS error (device sdd): failed to init dev_replace: -117
  BTRFS error (device sdd): open_ctree failed: -117

[CAUSE]
The devid 0 didn't get its devid updated is its own problem, here I'm
only focusing on the mount failure itself.

The mount is not caused by the missing device, as the fs has RAID1C3 for
metadata and RAID10 for data, thus is completely able to tolerate one
missing device.

The device tree shows the dev-replace has properly finished:

        item 7 key (0 DEV_REPLACE 0) itemoff 15931 itemsize 72
                src devid -1 cursor left 11091821199360 cursor right 11091821199360 mode ALWAYS
                state FINISHED write errors 0 uncorrectable read errors 0
		      ^^^^^^^^

And the chunk tree shows there is no devid 0:

  leaf 37980736602112 items 23 free space 12548 generation 1394388 owner CHUNK_TREE
  leaf 37980736602112 flags 0x1(WRITTEN) backref revision 1
  fs uuid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9
  chunk uuid d074c661-6311-4570-b59f-a5c83fd37f8e
         item 0 key (DEV_ITEMS DEV_ITEM 3) itemoff 16185 itemsize 98
                 devid 3 total_bytes 20000588955648 bytes_used 8282877984768
                 io_align 4096 io_width 4096 sector_size 4096 type 0
                 generation 0 start_offset 0 dev_group 0
                 seek_speed 0 bandwidth 0
                 uuid 0d596b69-fb0d-4031-b4af-a301d0868b8b
                 fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9
         ...

Which shows the first device is devid 3.

But there is indeed /dev/sdd with devid 0:

  superblock: bytenr=65536, device=/dev/sdd
  ---------------------------------------------------------
  csum_type               0 (crc32c)
  csum_size               4
  csum                    0xd4bed87e [match]
  bytenr                  65536
  flags                   0x1
                          ( WRITTEN )
  magic                   _BHRfS_M [match]
  fsid                    84a1ed4a-365c-45c3-a9ee-a7df525dc3c9
  ...
  uuid_tree_generation    1394388
  dev_item.uuid           ee6532ad-5442-45f7-87fb-7703e29ed934
  dev_item.fsid           84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 [match]
  dev_item.type           0
  dev_item.total_bytes    20000588955648
  dev_item.bytes_used     8292541661184
  dev_item.io_align       0
  dev_item.io_width       0
  dev_item.sector_size    0
  dev_item.devid          0 <<<

So this means device scan will register sdd as devid 0 into the fs, then
during btrfs_init_dev_replace(), we located the replace progress item,
found the previous replace is finished, but we still need to check if
the dev-replace target device (devid 0) exists.

If that device exists, we error out showing that error message.

But to be honest the end user may not really remember which device is
the replace target device, thus not sure what to do in the next step.

[ENHANCEMENT]
To make the error more obvious, and tell the end user which devices
should be unregistered:

- Introduce BTRFS_DEV_STATE_ITEM_FOUND flag
  During device item read from the chunk tree, set the flag for each
  found device item.

- Verify there is no device without the above flag during mount
  Even missing device should have that flag set.
  If we found a device without that flag set, it means it's an
  unexpected one and should be rejected.

- More detailed error message on what to do next
  This will show all unexpected devices and tell the end user to use
  'btrfs dev scan --forget' to forget them or remove them before mount.

There is an example dmesg where a device of a valid filesystem is modified to
have devid 0, then try degraded mount:

  BTRFS info (device dm-6): first mount of filesystem 7c873869-844c-4b39-bd75-a96148bf4656
  BTRFS info (device dm-6): using crc32c checksum algorithm
  BTRFS warning (device dm-6): devid 3 uuid b4a9f35b-db42-4ac4-b55a-cbf81d3b9683 is missing
  BTRFS error (device dm-6): devid 0 path /dev/mapper/test-scratch3 is registered but not found in chunk tree
  BTRFS error (device dm-6): please remove above devices or use 'btrfs device scan --forget <dev>' to unregister them before mount
  BTRFS error (device dm-6): open_ctree failed: -117

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
…group

We have currently three places that compute how much available space a
block group has. Add a helper function for this and use it in those
places.

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Development

Successfully merging this pull request may close these issues.