Re: [PATCH v2 2/2] fs/ext4/xattr: Check for 'xattr_sem' inside 'ext4_xattr_delete_inode'

[Bhupesh Sharma <bhsharma@igalia.com>]

Hi Ted,

On 3/17/25 8:47 PM, Theodore Ts'o wrote:
> On Tue, Jan 28, 2025 at 01:57:51PM +0530, Bhupesh wrote:
>> Once we are inside the 'ext4_xattr_delete_inode' function and trying
>> to delete the inode, the 'xattr_sem' should be unlocked.
>>
>> We need trylock here to avoid false-positive warning from lockdep
>> about reclaim circular dependency.
>>
>> This makes the 'ext4_xattr_delete_inode' implementation mimic the
>> existing 'ext2_xattr_delete_inode' implementation and thus avoid
>> similar lockdep issues while deleting inodes.
>>
>> Signed-off-by: Bhupesh <bhupesh@igalia.com>
> This patch is causing a failure of test ext4/026, and also exposed a
> bug in e2fsprogs[1].  With the e2fsprogs bug fixed, the file system
> corruption which is induced by ext4/026 is (when running e2fsck -fn on
> SCRATCH_DEV):
>
> Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> Pass 4: Checking reference counts
> Regular filesystem inode 14 has EA_INODE flag set. Clear? no
>
> Unattached inode 14
> Connect to /lost+found? no
>
> Pass 5: Checking group summary information
>
> /tmp/kvm-xfstests-tytso/vdc.img: ********** WARNING: Filesystem still has errors **********
>
> [1] https://lore.kernel.org/20250317144526.990271-1-tytso@mit.edu
>
> So what appears to be happening is this patch is resulting in ext4/026
> failing to clean up a no-longer-used EA inode, which is unfortunate.
>
> Without the e2fsorigs bug fix, ext4/026 will fail but the error
> message will be much less edifying:
>
> e2fsck 1.47.2 (1-Jan-2025)
> Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> Pass 4: Checking reference counts
> ext2fs_write_inode: Attempt to write to filesystem opened read-only while writing inode 14 in pass4
> e2fsck: aborted
>
> So I'm going to drop this patch (2/2) from the ext4 tree, but I'm
> going to keep patch 1/2 from this series, since it is fixing a real
> bug.  I presume that without this patch, the syzbot reproducer will
> trigger a false lockdep warning, but we can fix that later.

Sure, many thanks for your help.

Regards,
Bhupesh