Commit df2c0cb7 authored by Jeff Layton's avatar Jeff Layton Committed by Ilya Dryomov
Browse files

ceph: clean up locking annotation for ceph_get_snap_realm and __lookup_snap_realm 



They both say that the snap_rwsem must be held for write, but I don't
see any real reason for it, and it's not currently always called that
way.

The lookup is just walking the rbtree, so holding it for read should be
fine there. The "get" is bumping the refcount and (possibly) removing
it from the empty list. I see no need to hold the snap_rwsem for write
for that.

Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Reviewed-by: default avatarIlya Dryomov <idryomov@gmail.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent a6862e67

fs/ceph/snap.c

+4 −4
Original line number Diff line number Diff line
@@ -60,12 +60,12 @@ 
/*

 * increase ref count for the realm

 *

 * caller must hold snap_rwsem for write.

 * caller must hold snap_rwsem.

 */

void ceph_get_snap_realm(struct ceph_mds_client *mdsc,

			 struct ceph_snap_realm *realm)

{

	lockdep_assert_held_write(&mdsc->snap_rwsem);

	lockdep_assert_held(&mdsc->snap_rwsem);



	dout("get_realm %p %d -> %d\n", realm,

	     atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
@@ -139,7 +139,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm( 
/*

 * lookup the realm rooted at @ino.

 *

 * caller must hold snap_rwsem for write.

 * caller must hold snap_rwsem.

 */

static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,

						   u64 ino)
@@ -147,7 +147,7 @@ static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc, 
	struct rb_node *n = mdsc->snap_realms.rb_node;

	struct ceph_snap_realm *r;



	lockdep_assert_held_write(&mdsc->snap_rwsem);

	lockdep_assert_held(&mdsc->snap_rwsem);



	while (n) {

		r = rb_entry(n, struct ceph_snap_realm, node);