Btrfs: don't take the chunk_mutex/dev_list mutex in statfs V2
authorJosef Bacik <jbacik@fb.com>
Mon, 3 Nov 2014 13:56:50 +0000 (08:56 -0500)
committerChris Mason <clm@fb.com>
Fri, 21 Nov 2014 01:20:05 +0000 (17:20 -0800)
commit7e33fd993a74b3fda39c756803ba8b24bef72df5
treeff2ddc1af7bc7e6f4949ca70519cccf7964c9ae8
parent633c0aad4c0243a506a3e8590551085ad78af82d
Btrfs: don't take the chunk_mutex/dev_list mutex in statfs V2

Our gluster boxes get several thousand statfs() calls per second, which begins
to suck hardcore with all of the lock contention on the chunk mutex and dev list
mutex.  We don't really need to hold these things, if we have transient
weirdness with statfs() because of the chunk allocator we don't care, so remove
this locking.

We still need the dev_list lock if you mount with -o alloc_start however, which
is a good argument for nuking that thing from orbit, but that's a patch for
another day.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
fs/btrfs/super.c