[PATCH] dcache: avoid race when updating nr_unused count of unused dentries

[PATCH] dcache: avoid race when updating nr_unused count of unused dentries

 ChangeSet
   2004/05/29 10:58:56-07:00 akpm@osdl.org
   [PATCH] fs/dcache.c: avoid race when updating nr_unused count of unused dentries.

   From: NeilBrown <neilb@cse.unsw.edu.au>

   d_count == 1 is no guarantee that dentry is on the dentry_unused list, even
   if it has just been incremented inside dcache_lock, as dput can decrement
   at any time.

   This test from Greg Banks is much safer, and is more transparently correct.

   Cc: Maneesh Soni <maneesh@in.ibm.com>, Dipankar Sarma <dipankar@in.ibm.com>
   From: Greg Banks <gnb@melbourne.sgi.com>
   Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
   Signed-off-by: Andrew Morton <akpm@osdl.org>
   Signed-off-by: Linus Torvalds <torvalds@osdl.org>