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ceph: clean up locking annotation for ceph_get_snap_realm and __lookup_snap_realm

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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: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Jeff Layton 2021-06-01 09:24:38 -04:00 committed by Ilya Dryomov
parent a6862e6708
commit df2c0cb7f8
1 changed files with 4 additions and 4 deletions
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8
fs/ceph/snap.c
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@ -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);