Re: [PATCH AUTOSEL 4.4 27/37] ext4: work around deleting a file with i_nlink == 0 safely

[Greg KH]

On Wed, Dec 11, 2019 at 11:19:59AM -0500, Theodore Y. Ts'o wrote:
> On Wed, Dec 11, 2019 at 10:38:03AM -0500, Sasha Levin wrote:
> > From: Theodore Ts'o <tytso@xxxxxxx>
> > 
> > [ Upstream commit c7df4a1ecb8579838ec8c56b2bb6a6716e974f37 ]
> > 
> > If the file system is corrupted such that a file's i_links_count is
> > too small, then it's possible that when unlinking that file, i_nlink
> > will already be zero.  Previously we were working around this kind of
> > corruption by forcing i_nlink to one; but we were doing this before
> > trying to delete the directory entry --- and if the file system is
> > corrupted enough that ext4_delete_entry() fails, then we exit with
> > i_nlink elevated, and this causes the orphan inode list handling to be
> > FUBAR'ed, such that when we unmount the file system, the orphan inode
> > list can get corrupted.
> > 
> > A better way to fix this is to simply skip trying to call drop_nlink()
> > if i_nlink is already zero, thus moving the check to the place where
> > it makes the most sense.
> > 
> > https://bugzilla.kernel.org/show_bug.cgi?id=205433
> > 
> > Link: https://lore.kernel.org/r/20191112032903.8828-1-tytso@xxxxxxx
> > Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
> > Cc: stable@xxxxxxxxxx
> > Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> 
> I'm confused; this was explicitly cc'ed to stable@xxxxxxxxxx, so why
> is your AUTOSEL picking this up?  I would have thought this would get
> picked up via the normal stable kernel processes.

Perhaps because it is still in my queue, I haven't gotten there yet, but
will do so after this next round of -rcs are released.

thanks,

greg k-h