autofs4: don't take spinlock when not needed in autofs4_lookup_expiring
authorNeilBrown <neilb@suse.de>
Fri, 8 Aug 2014 21:19:54 +0000 (14:19 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 8 Aug 2014 22:57:19 +0000 (15:57 -0700)
commit668128e90b9596668141539326178dacc42af188
treed68268b71a156f2ed76999384e46d3dc36236975
parentc312442fe3ce9561137910db35ad1409d67dbac6
autofs4: don't take spinlock when not needed in autofs4_lookup_expiring

If the expiring_list is empty, we can avoid a costly spinlock in the
rcu-walk path through autofs4_d_manage (once the rest of the path
becomes rcu-walk friendly).

Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/autofs4/root.c