ceph: add flock/fcntl lock support

Implement flock inode operation to support advisory file locking.  All
lock/unlock operations are synchronous with the MDS.  Lock state is
sent when reconnecting to a recovering MDS to restore the shared lock
state.

Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/file.c

@@ -938,6 +938,8 @@ const struct file_operations ceph_file_fops = {
 	.aio_write = ceph_aio_write,
 	.mmap = ceph_mmap,
 	.fsync = ceph_fsync,
+	.lock = ceph_lock,
+	.flock = ceph_flock,
 	.splice_read = generic_file_splice_read,
 	.splice_write = generic_file_splice_write,
 	.unlocked_ioctl = ceph_ioctl,