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>

2 files changed, 10 insertions, 8 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 6d1cd45dca89..b3b0a913589f 100644
--- a/fs/ceph/caps.c
+++ b/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);
 
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index a17fc49c9948..5edf206354b2 100644
--- a/fs/ceph/mds_client.c
+++ b/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;