NLM: Fix a circular lock dependency in lockd
authorTrond Myklebust <Trond.Myklebust@netapp.com>
Tue, 25 Sep 2007 19:55:03 +0000 (15:55 -0400)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Wed, 26 Sep 2007 16:22:04 +0000 (09:22 -0700)
commit255129d1e9ca0ed3d69d5517fae3e03d7ab4b806
treee3dedbffebd4f0e15da97684500296c9bc4d3d6a
parentf6a592e8abd2f2394623ce5427cbb4c265495974
NLM: Fix a circular lock dependency in lockd

The problem is that the garbage collector for the 'host' structures
nlm_gc_hosts(), holds nlm_host_mutex while calling down to
nlmsvc_mark_resources, which, eventually takes the file->f_mutex.

We cannot therefore call nlmsvc_lookup_host() from within
nlmsvc_create_block, since the caller will already hold file->f_mutex, so
the attempt to grab nlm_host_mutex may deadlock.

Fix the problem by calling nlmsvc_lookup_host() outside the file->f_mutex.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/lockd/svclock.c