ceph: don't take s_mutex in try_flush_caps

The s_mutex doesn't protect anything in this codepath.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Author: jtlayton

fs/ceph/caps.c

@@ -2146,26 +2146,17 @@ static int try_flush_caps(struct inode *inode, u64 *ptid)
 {
 	struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
 	struct ceph_inode_info *ci = ceph_inode(inode);
-	struct ceph_mds_session *session = NULL;
 	int flushing = 0;
 	u64 flush_tid = 0, oldest_flush_tid = 0;
 
-retry:
 	spin_lock(&ci->i_ceph_lock);
 retry_locked:
 	if (ci->i_dirty_caps && ci->i_auth_cap) {
 		struct ceph_cap *cap = ci->i_auth_cap;
 		struct cap_msg_args arg;
+		struct ceph_mds_session *session = cap->session;
 
-		if (session != cap->session) {
-			spin_unlock(&ci->i_ceph_lock);
-			if (session)
-				mutex_unlock(&session->s_mutex);
-			session = cap->session;
-			mutex_lock(&session->s_mutex);
-			goto retry;
-		}
-		if (cap->session->s_state < CEPH_MDS_SESSION_OPEN) {
+		if (session->s_state < CEPH_MDS_SESSION_OPEN) {
 			spin_unlock(&ci->i_ceph_lock);
 			goto out;
 		}
@@ -2202,9 +2193,6 @@ static int try_flush_caps(struct inode *inode, u64 *ptid)
 		spin_unlock(&ci->i_ceph_lock);
 	}
 out:
-	if (session)
-		mutex_unlock(&session->s_mutex);
-
 	*ptid = flush_tid;
 	return flushing;
 }