ceph: don't take i_ceph_lock in handle_cap_import

Just take it before calling it. This means we have to do a couple of
minor in-memory operations under the spinlock now, but those shouldn't
be an issue.
Signed-off-by: NJeff Layton <jlayton@kernel.org>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

fs/ceph/caps.c

@@ -3805,7 +3805,6 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 			      struct ceph_mds_cap_peer *ph,
 			      struct ceph_mds_session *session,
 			      struct ceph_cap **target_cap, int *old_issued)
-	__acquires(ci->i_ceph_lock)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_cap *cap, *ocap, *new_cap = NULL;
@@ -3830,14 +3829,13 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 
 	dout("handle_cap_import inode %p ci %p mds%d mseq %d peer %d\n",
 	     inode, ci, mds, mseq, peer);
-
 retry:
-	spin_lock(&ci->i_ceph_lock);
 	cap = __get_cap_for_mds(ci, mds);
 	if (!cap) {
 		if (!new_cap) {
 			spin_unlock(&ci->i_ceph_lock);
 			new_cap = ceph_get_cap(mdsc, NULL);
+			spin_lock(&ci->i_ceph_lock);
 			goto retry;
 		}
 		cap = new_cap;
@@ -4051,6 +4049,7 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 		} else {
 			down_read(&mdsc->snap_rwsem);
 		}
+		spin_lock(&ci->i_ceph_lock);
 		handle_cap_import(mdsc, inode, h, peer, session,
 				  &cap, &extra_info.issued);
 		handle_cap_grant(inode, session, cap,