ceph: move ceph_find_inode() outside the s_mutex

ceph_find_inode() may wait on freeing inode, using it inside the s_mutex
may cause deadlock. (the freeing inode is waiting for OSD read reply, but
dispatch thread is blocked by the s_mutex)
Signed-off-by: Yan, Zheng <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

fs/ceph/caps.c

@@ -3045,6 +3045,12 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 		}
 	}
 
+	/* lookup ino */
+	inode = ceph_find_inode(sb, vino);
+	ci = ceph_inode(inode);
+	dout(" op %s ino %llx.%llx inode %p\n", ceph_cap_op_name(op), vino.ino,
+	     vino.snap, inode);
+
 	mutex_lock(&session->s_mutex);
 	session->s_seq++;
 	dout(" mds%d seq %lld cap seq %u\n", session->s_mds, session->s_seq,
@@ -3053,11 +3059,6 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 	if (op == CEPH_CAP_OP_IMPORT)
 		ceph_add_cap_releases(mdsc, session);
 
-	/* lookup ino */
-	inode = ceph_find_inode(sb, vino);
-	ci = ceph_inode(inode);
-	dout(" op %s ino %llx.%llx inode %p\n", ceph_cap_op_name(op), vino.ino,
-	     vino.snap, inode);
 	if (!inode) {
 		dout(" i don't have ino %llx\n", vino.ino);
 

fs/ceph/mds_client.c

@@ -2944,14 +2944,15 @@ static void handle_lease(struct ceph_mds_client *mdsc,
 	if (dname.len != get_unaligned_le32(h+1))
 		goto bad;
 
-	mutex_lock(&session->s_mutex);
-	session->s_seq++;
-
 	/* lookup inode */
 	inode = ceph_find_inode(sb, vino);
 	dout("handle_lease %s, ino %llx %p %.*s\n",
 	     ceph_lease_op_name(h->action), vino.ino, inode,
 	     dname.len, dname.name);
+
+	mutex_lock(&session->s_mutex);
+	session->s_seq++;
+
 	if (inode == NULL) {
 		dout("handle_lease no inode %llx\n", vino.ino);
 		goto release;