Re: [PATCH v5] ntfs: roll back the ACL xattr commit when the WSL mode update fails

[Hyunchul Lee <hyc.lee@gmail.com>]

On Tue, Oct 13, 2026 at 09:56:52AM +0800, Hongling Zeng wrote:
> ntfs_set_acl_ex() commits the ACL xattr before it rewrites the WSL
> mode EA, and removes it again when the rewrite fails.  That only
> undoes a set that created the xattr: when the update replaced or
> removed an existing one, the old ACL is discarded along with the
> failed update.  No error is recorded when the undo fails, so the
> new, typically more permissive, ACL is left on disk while i_mode,
> the mode EA and the cached ACL keep the old values.  After a
> remount, a chmod 0640 -> 0777 that reported failure leaves the file
> accessible to the relaxed ACL while stat() still reports 0640.
> 
> Save the previous xattr before committing the update, and restore it
> when the mode EA rewrite fails.  A removed xattr is created again,
> since XATTR_REPLACE fails with -ENODATA once the removal dropped the
> entry.  Remove the new xattr only when there was no previous one, and
> skip the undo when the commit changed nothing.  A failed rollback is
> recorded: NVolSetErrors(), which the next persistence point persists
> as VOLUME_IS_DIRTY, and a log message the errors= policy acts on.
> The flag cannot be written to disk here directly: the target inode's
> mrec_lock is held and the $Volume mrec_lock cannot be nested under
> it.
> 
> Fixes: fc053f05ca28 ("ntfs: add reparse and ea operations")
> Cc: stable@vger.kernel.org
> Suggested-by: Hyunchul Lee <hyc.lee@gmail.com>
> Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>

Looks good to me.

Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>

-- 
Thanks,
Hyunchul