On Mon, Nov 28, 2016 at 11:44:20AM +0100, Jan Kara wrote:

On Sat 26-11-16 22:17:57, Eric Biggers wrote:

quoted

mbcache entries have an 'e_referenced' bit which users can set with
mb_cache_entry_touch() to indicate that an entry should be given another
pass through the LRU list before the shrinker can delete it.  However,
mb_cache_shrink() actually would, when seeing an e_referenced entry at
the front of the list (the least-recently used end), place it right at
the front of the list again.  The next iteration would then remove the
entry from the list and delete it.  Consequently, e_referenced had
essentially no effect, so ext2/ext4 xattr blocks would sometimes not be
reused as often as expected.

Fix this by making the shrinker move e_referenced entries to the back of
the list rather than the front.

Signed-off-by: Eric Biggers <redacted>

Bah, good spotting. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

BTW, how did you find out?

Nothing special --- I just happened to notice while reading over the code.

Eric