ceph: call handle_cap_grant() for cap import message

(cherry picked from commit 0e5e1774)

If client sends cap message that requests new max size during
exporting caps, the exporting MDS will drop the message quietly.
So the client may wait for the reply that updates the max size
forever. call handle_cap_grant() for cap import message can
avoid this issue.
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Sage Weil <sage@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/ceph/caps.c

@@ -2749,6 +2749,7 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 
 	/* make sure we re-request max_size, if necessary */
 	spin_lock(&ci->i_ceph_lock);
+	ci->i_wanted_max_size = 0;  /* reset */
 	ci->i_requested_max_size = 0;
 	spin_unlock(&ci->i_ceph_lock);
 }
@@ -2844,8 +2845,6 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 	case CEPH_CAP_OP_IMPORT:
 		handle_cap_import(mdsc, inode, h, session,
 				  snaptrace, snaptrace_len);
-		ceph_check_caps(ceph_inode(inode), 0, session);
-		goto done_unlocked;
 	}
 
 	/* the rest require a cap */
@@ -2862,6 +2861,7 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 	switch (op) {
 	case CEPH_CAP_OP_REVOKE:
 	case CEPH_CAP_OP_GRANT:
+	case CEPH_CAP_OP_IMPORT:
 		handle_cap_grant(inode, h, session, cap, msg->middle);
 		goto done_unlocked;