linux.git/fs/ext4, branch v6.6.131

ext4: always drain queued discard work in ext4_mb_release()

2026-04-02T11:07:29+00:00

commit 9ee29d20aab228adfb02ca93f87fb53c56c2f3af upstream.

While reviewing recent ext4 patch[1], Sashiko raised the following
concern[2]:

> If the filesystem is initially mounted with the discard option,
> deleting files will populate sbi->s_discard_list and queue
> s_discard_work. If it is then remounted with nodiscard, the
> EXT4_MOUNT_DISCARD flag is cleared, but the pending s_discard_work is
> neither cancelled nor flushed.

[1] https://lore.kernel.org/r/20260319094545.19291-1-qiang.zhang@linux.dev/
[2] https://sashiko.dev/#/patchset/20260319094545.19291-1-qiang.zhang%40linux.dev

The concern was valid, but it had nothing to do with the patch[1].
One of the problems with Sashiko in its current (early) form is that
it will detect pre-existing issues and report it as a problem with the
patch that it is reviewing.

In practice, it would be hard to hit deliberately (unless you are a
malicious syzkaller fuzzer), since it would involve mounting the file
system with -o discard, and then deleting a large number of files,
remounting the file system with -o nodiscard, and then immediately
unmounting the file system before the queued discard work has a change
to drain on its own.

Fix it because it's a real bug, and to avoid Sashiko from raising this
concern when analyzing future patches to mballoc.c.

Signed-off-by: Theodore Ts'o 
Fixes: 55cdd0af2bc5 ("ext4: get discard out of jbd2 commit kthread contex")
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: fix iloc.bh leak in ext4_fc_replay_inode() error paths

2026-04-02T11:07:29+00:00

commit ec0a7500d8eace5b4f305fa0c594dd148f0e8d29 upstream.

During code review, Joseph found that ext4_fc_replay_inode() calls
ext4_get_fc_inode_loc() to get the inode location, which holds a
reference to iloc.bh that must be released via brelse().

However, several error paths jump to the 'out' label without
releasing iloc.bh:

 - ext4_handle_dirty_metadata() failure
 - sync_dirty_buffer() failure
 - ext4_mark_inode_used() failure
 - ext4_iget() failure

Fix this by introducing an 'out_brelse' label placed just before
the existing 'out' label to ensure iloc.bh is always released.

Additionally, make ext4_fc_replay_inode() propagate errors
properly instead of always returning 0.

Reported-by: Joseph Qi 
Fixes: 8016e29f4362 ("ext4: fast commit recovery path")
Signed-off-by: Baokun Li 
Reviewed-by: Zhang Yi 
Reviewed-by: Jan Kara 
Link: https://patch.msgid.link/20260323060836.3452660-1-libaokun@linux.alibaba.com
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: fix the might_sleep() warnings in kvfree()

2026-04-02T11:07:28+00:00

commit 496bb99b7e66f48b178126626f47e9ba79e2d0fa upstream.

Use the kvfree() in the RCU read critical section can trigger
the following warnings:

EXT4-fs (vdb): unmounting filesystem cd983e5b-3c83-4f5a-a136-17b00eb9d018.

WARNING: suspicious RCU usage

./include/linux/rcupdate.h:409 Illegal context switch in RCU read-side critical section!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1

Call Trace:
 
 dump_stack_lvl+0xbb/0xd0
 dump_stack+0x14/0x20
 lockdep_rcu_suspicious+0x15a/0x1b0
 __might_resched+0x375/0x4d0
 ? put_object.part.0+0x2c/0x50
 __might_sleep+0x108/0x160
 vfree+0x58/0x910
 ? ext4_group_desc_free+0x27/0x270
 kvfree+0x23/0x40
 ext4_group_desc_free+0x111/0x270
 ext4_put_super+0x3c8/0xd40
 generic_shutdown_super+0x14c/0x4a0
 ? __pfx_shrinker_free+0x10/0x10
 kill_block_super+0x40/0x90
 ext4_kill_sb+0x6d/0xb0
 deactivate_locked_super+0xb4/0x180
 deactivate_super+0x7e/0xa0
 cleanup_mnt+0x296/0x3e0
 __cleanup_mnt+0x16/0x20
 task_work_run+0x157/0x250
 ? __pfx_task_work_run+0x10/0x10
 ? exit_to_user_mode_loop+0x6a/0x550
 exit_to_user_mode_loop+0x102/0x550
 do_syscall_64+0x44a/0x500
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
 

BUG: sleeping function called from invalid context at mm/vmalloc.c:3441
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 556, name: umount
preempt_count: 1, expected: 0
CPU: 3 UID: 0 PID: 556 Comm: umount
Call Trace:
 
 dump_stack_lvl+0xbb/0xd0
 dump_stack+0x14/0x20
 __might_resched+0x275/0x4d0
 ? put_object.part.0+0x2c/0x50
 __might_sleep+0x108/0x160
 vfree+0x58/0x910
 ? ext4_group_desc_free+0x27/0x270
 kvfree+0x23/0x40
 ext4_group_desc_free+0x111/0x270
 ext4_put_super+0x3c8/0xd40
 generic_shutdown_super+0x14c/0x4a0
 ? __pfx_shrinker_free+0x10/0x10
 kill_block_super+0x40/0x90
 ext4_kill_sb+0x6d/0xb0
 deactivate_locked_super+0xb4/0x180
 deactivate_super+0x7e/0xa0
 cleanup_mnt+0x296/0x3e0
 __cleanup_mnt+0x16/0x20
 task_work_run+0x157/0x250
 ? __pfx_task_work_run+0x10/0x10
 ? exit_to_user_mode_loop+0x6a/0x550
 exit_to_user_mode_loop+0x102/0x550
 do_syscall_64+0x44a/0x500
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The above scenarios occur in initialization failures and teardown
paths, there are no parallel operations on the resources released
by kvfree(), this commit therefore remove rcu_read_lock/unlock() and
use rcu_access_pointer() instead of rcu_dereference() operations.

Fixes: 7c990728b99e ("ext4: fix potential race between s_flex_groups online resizing and access")
Fixes: df3da4ea5a0f ("ext4: fix potential race between s_group_info online resizing and access")
Signed-off-by: Zqiang 
Reviewed-by: Baokun Li 
Link: https://patch.msgid.link/20260319094545.19291-1-qiang.zhang@linux.dev
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: fix use-after-free in update_super_work when racing with umount

2026-04-02T11:07:28+00:00

commit d15e4b0a418537aafa56b2cb80d44add83e83697 upstream.

Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount
filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work
to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups
reads during unmount. However, this introduced a use-after-free because
update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which
accesses the kobject's kernfs_node after it has been freed by kobject_del()
in ext4_unregister_sysfs():

  update_super_work                ext4_put_super
  -----------------                --------------
                                   ext4_unregister_sysfs(sb)
                                     kobject_del(&sbi->s_kobj)
                                       __kobject_del()
                                         sysfs_remove_dir()
                                           kobj->sd = NULL
                                         sysfs_put(sd)
                                           kernfs_put()  // RCU free
  ext4_notify_error_sysfs(sbi)
    sysfs_notify(&sbi->s_kobj)
      kn = kobj->sd              // stale pointer
      kernfs_get(kn)             // UAF on freed kernfs_node
                                   ext4_journal_destroy()
                                     flush_work(&sbi->s_sb_upd_work)

Instead of reordering the teardown sequence, fix this by making
ext4_notify_error_sysfs() detect that sysfs has already been torn down
by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call
in that case. A dedicated mutex (s_error_notify_mutex) serializes
ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs()
to prevent TOCTOU races where the kobject could be deleted between the
state_in_sysfs check and the sysfs_notify() call.

Fixes: b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem")
Cc: Jiayuan Chen 
Suggested-by: Jan Kara 
Signed-off-by: Jiayuan Chen 
Reviewed-by: Ritesh Harjani (IBM) 
Reviewed-by: Jan Kara 
Link: https://patch.msgid.link/20260319120336.157873-1-jiayuan.chen@linux.dev
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: reject mount if bigalloc with s_first_data_block != 0

2026-04-02T11:07:28+00:00

commit 3822743dc20386d9897e999dbb990befa3a5b3f8 upstream.

bigalloc with s_first_data_block != 0 is not supported, reject mounting
it.

Signed-off-by: Helen Koike 
Suggested-by: Theodore Ts'o 
Reported-by: syzbot+b73703b873a33d8eb8f6@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b73703b873a33d8eb8f6
Link: https://patch.msgid.link/20260317142325.135074-1-koike@igalia.com
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: avoid allocate block from corrupted group in ext4_mb_find_by_goal()

2026-04-02T11:07:28+00:00

commit 46066e3a06647c5b186cc6334409722622d05c44 upstream.

There's issue as follows:
...
EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 206 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 206 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 206 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 206 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 2243 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): Delayed block allocation failed for inode 2239 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (mmcblk0p1): This should not happen!! Data will be lost

EXT4-fs (mmcblk0p1): error count since last fsck: 1
EXT4-fs (mmcblk0p1): initial error at time 1765597433: ext4_mb_generate_buddy:760
EXT4-fs (mmcblk0p1): last error at time 1765597433: ext4_mb_generate_buddy:760
...

According to the log analysis, blocks are always requested from the
corrupted block group. This may happen as follows:
ext4_mb_find_by_goal
  ext4_mb_load_buddy
   ext4_mb_load_buddy_gfp
     ext4_mb_init_cache
      ext4_read_block_bitmap_nowait
      ext4_wait_block_bitmap
       ext4_validate_block_bitmap
        if (!grp || EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
         return -EFSCORRUPTED; // There's no logs.
 if (err)
  return err;  // Will return error
ext4_lock_group(ac->ac_sb, group);
  if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info))) // Unreachable
   goto out;

After commit 9008a58e5dce ("ext4: make the bitmap read routines return
real error codes") merged, Commit 163a203ddb36 ("ext4: mark block group
as corrupt on block bitmap error") is no real solution for allocating
blocks from corrupted block groups. This is because if
'EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info)' is true, then
'ext4_mb_load_buddy()' may return an error. This means that the block
allocation will fail.
Therefore, check block group if corrupted when ext4_mb_load_buddy()
returns error.

Fixes: 163a203ddb36 ("ext4: mark block group as corrupt on block bitmap error")
Fixes: 9008a58e5dce ("ext4: make the bitmap read routines return real error codes")
Signed-off-by: Ye Bin 
Reviewed-by: Ritesh Harjani (IBM) 
Reviewed-by: Zhang Yi 
Reviewed-by: Andreas Dilger 
Reviewed-by: Jan Kara 
Link: https://patch.msgid.link/20260302134619.3145520-1-yebin@huaweicloud.com
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: avoid infinite loops caused by residual data

2026-04-02T11:07:28+00:00

commit 5422fe71d26d42af6c454ca9527faaad4e677d6c upstream.

On the mkdir/mknod path, when mapping logical blocks to physical blocks,
if inserting a new extent into the extent tree fails (in this example,
because the file system disabled the huge file feature when marking the
inode as dirty), ext4_ext_map_blocks() only calls ext4_free_blocks() to
reclaim the physical block without deleting the corresponding data in
the extent tree. This causes subsequent mkdir operations to reference
the previously reclaimed physical block number again, even though this
physical block is already being used by the xattr block. Therefore, a
situation arises where both the directory and xattr are using the same
buffer head block in memory simultaneously.

The above causes ext4_xattr_block_set() to enter an infinite loop about
"inserted" and cannot release the inode lock, ultimately leading to the
143s blocking problem mentioned in [1].

If the metadata is corrupted, then trying to remove some extent space
can do even more harm. Also in case EXT4_GET_BLOCKS_DELALLOC_RESERVE
was passed, remove space wrongly update quota information.
Jan Kara suggests distinguishing between two cases:

1) The error is ENOSPC or EDQUOT - in this case the filesystem is fully
consistent and we must maintain its consistency including all the
accounting. However these errors can happen only early before we've
inserted the extent into the extent tree. So current code works correctly
for this case.

2) Some other error - this means metadata is corrupted. We should strive to
do as few modifications as possible to limit damage. So I'd just skip
freeing of allocated blocks.

[1]
INFO: task syz.0.17:5995 blocked for more than 143 seconds.
Call Trace:
 inode_lock_nested include/linux/fs.h:1073 [inline]
 __start_dirop fs/namei.c:2923 [inline]
 start_dirop fs/namei.c:2934 [inline]

Reported-by: syzbot+512459401510e2a9a39f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1659aaaaa8d9d11265d7
Tested-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com
Reported-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=512459401510e2a9a39f
Tested-by: syzbot+1659aaaaa8d9d11265d7@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis 
Reviewed-by: Jan Kara 
Tested-by: syzbot+512459401510e2a9a39f@syzkaller.appspotmail.com
Link: https://patch.msgid.link/tencent_43696283A68450B761D76866C6F360E36705@qq.com
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: replace BUG_ON with proper error handling in ext4_read_inline_folio

2026-04-02T11:07:28+00:00

commit 356227096eb66e41b23caf7045e6304877322edf upstream.

Replace BUG_ON() with proper error handling when inline data size
exceeds PAGE_SIZE. This prevents kernel panic and allows the system to
continue running while properly reporting the filesystem corruption.

The error is logged via ext4_error_inode(), the buffer head is released
to prevent memory leak, and -EFSCORRUPTED is returned to indicate
filesystem corruption.

Signed-off-by: Yuto Ohnuki 
Link: https://patch.msgid.link/20260223123345.14838-2-ytohnuki@amazon.com
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: make recently_deleted() properly work with lazy itable initialization

2026-04-02T11:07:28+00:00

commit bd060afa7cc3e0ad30afa9ecc544a78638498555 upstream.

recently_deleted() checks whether inode has been used in the near past.
However this can give false positive result when inode table is not
initialized yet and we are in fact comparing to random garbage (or stale
itable block of a filesystem before mkfs). Ultimately this results in
uninitialized inodes being skipped during inode allocation and possibly
they are never initialized and thus e2fsck complains.  Verify if the
inode has been initialized before checking for dtime.

Signed-off-by: Jan Kara 
Reviewed-by: Zhang Yi 
Link: https://patch.msgid.link/20260216164848.3074-3-jack@suse.cz
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman

ext4: fix fsync(2) for nojournal mode

2026-04-02T11:07:28+00:00

commit 1308255bbf8452762f89f44f7447ce137ecdbcff upstream.

When inode metadata is changed, we sometimes just call
ext4_mark_inode_dirty() to track modified metadata. This copies inode
metadata into block buffer which is enough when we are journalling
metadata. However when we are running in nojournal mode we currently
fail to write the dirtied inode buffer during fsync(2) because the inode
is not marked as dirty. Use explicit ext4_write_inode() call to make
sure the inode table buffer is written to the disk. This is a band aid
solution but proper solution requires a much larger rewrite including
changes in metadata bh tracking infrastructure.

Reported-by: Free Ekanayaka 
Link: https://lore.kernel.org/all/87il8nhxdm.fsf@x1.mail-host-address-is-not-set/
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara 
Reviewed-by: Zhang Yi 
Link: https://patch.msgid.link/20260216164848.3074-4-jack@suse.cz
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman