ceph: release cap on import if we don't have the inode

If we get an IMPORT that give us a cap, but we don't have the inode, queue
a release (and try to send it immediately) so that the MDS doesn't get
stuck waiting for us.

Signed-off-by: Sage Weil <[e-mail]>

fs/ceph/caps.c

···
 	return 0;
 }
 
+static void __queue_cap_release(struct ceph_mds_session *session,
+				u64 ino, u64 cap_id, u32 migrate_seq,
+				u32 issue_seq)
+{
+	struct ceph_msg *msg;
+	struct ceph_mds_cap_release *head;
+	struct ceph_mds_cap_item *item;
+
+	spin_lock(&session->s_cap_lock);
+	BUG_ON(!session->s_num_cap_releases);
+	msg = list_first_entry(&session->s_cap_releases,
+			       struct ceph_msg, list_head);
+
+	dout(" adding %llx release to mds%d msg %p (%d left)\n",
+	     ino, session->s_mds, msg, session->s_num_cap_releases);
+
+	BUG_ON(msg->front.iov_len + sizeof(*item) > PAGE_CACHE_SIZE);
+	head = msg->front.iov_base;
+	head->num = cpu_to_le32(le32_to_cpu(head->num) + 1);
+	item = msg->front.iov_base + msg->front.iov_len;
+	item->ino = cpu_to_le64(ino);
+	item->cap_id = cpu_to_le64(cap_id);
+	item->migrate_seq = cpu_to_le32(migrate_seq);
+	item->seq = cpu_to_le32(issue_seq);
+
+	session->s_num_cap_releases--;
+
+	msg->front.iov_len += sizeof(*item);
+	if (le32_to_cpu(head->num) == CEPH_CAPS_PER_RELEASE) {
+		dout(" release msg %p full\n", msg);
+		list_move_tail(&msg->list_head, &session->s_cap_releases_done);
+	} else {
+		dout(" release msg %p at %d/%d (%d)\n", msg,
+		     (int)le32_to_cpu(head->num),
+		     (int)CEPH_CAPS_PER_RELEASE,
+		     (int)msg->front.iov_len);
+	}
+	spin_unlock(&session->s_cap_lock);
+}
+
 /*
  * Queue cap releases when an inode is dropped from our cache.  Since
  * inode is about to be destroyed, there is no need for i_lock.
···
 	while (p) {
 		struct ceph_cap *cap = rb_entry(p, struct ceph_cap, ci_node);
 		struct ceph_mds_session *session = cap->session;
-		struct ceph_msg *msg;
-		struct ceph_mds_cap_release *head;
-		struct ceph_mds_cap_item *item;
 
-		spin_lock(&session->s_cap_lock);
-		BUG_ON(!session->s_num_cap_releases);
-		msg = list_first_entry(&session->s_cap_releases,
-				       struct ceph_msg, list_head);
-
-		dout(" adding %p release to mds%d msg %p (%d left)\n",
-		     inode, session->s_mds, msg, session->s_num_cap_releases);
-
-		BUG_ON(msg->front.iov_len + sizeof(*item) > PAGE_CACHE_SIZE);
-		head = msg->front.iov_base;
-		head->num = cpu_to_le32(le32_to_cpu(head->num) + 1);
-		item = msg->front.iov_base + msg->front.iov_len;
-		item->ino = cpu_to_le64(ceph_ino(inode));
-		item->cap_id = cpu_to_le64(cap->cap_id);
-		item->migrate_seq = cpu_to_le32(cap->mseq);
-		item->seq = cpu_to_le32(cap->issue_seq);
-
-		session->s_num_cap_releases--;
-
-		msg->front.iov_len += sizeof(*item);
-		if (le32_to_cpu(head->num) == CEPH_CAPS_PER_RELEASE) {
-			dout(" release msg %p full\n", msg);
-			list_move_tail(&msg->list_head,
-				       &session->s_cap_releases_done);
-		} else {
-			dout(" release msg %p at %d/%d (%d)\n", msg,
-			     (int)le32_to_cpu(head->num),
-			     (int)CEPH_CAPS_PER_RELEASE,
-			     (int)msg->front.iov_len);
-		}
-		spin_unlock(&session->s_cap_lock);
+		__queue_cap_release(session, ceph_ino(inode), cap->cap_id,
+				    cap->mseq, cap->issue_seq);
 		p = rb_next(p);
 		__ceph_remove_cap(cap);
 	}
···
 	struct ceph_mds_caps *h;
 	int mds = session->s_mds;
 	int op;
-	u32 seq;
+	u32 seq, mseq;
 	struct ceph_vino vino;
 	u64 cap_id;
 	u64 size, max_size;
···
 	vino.snap = CEPH_NOSNAP;
 	cap_id = le64_to_cpu(h->cap_id);
 	seq = le32_to_cpu(h->seq);
+	mseq = le32_to_cpu(h->migrate_seq);
 	size = le64_to_cpu(h->size);
 	max_size = le64_to_cpu(h->max_size);
 
···
 	     vino.snap, inode);
 	if (!inode) {
 		dout(" i don't have ino %llx\n", vino.ino);
+
+		if (op == CEPH_CAP_OP_IMPORT)
+			__queue_cap_release(session, vino.ino, cap_id,
+					    mseq, seq);
+
+		/*
+		 * send any full release message to try to move things
+		 * along for the mds (who clearly thinks we still have this
+		 * cap).
+		 */
+		ceph_send_cap_releases(mdsc, session);
 		goto done;
 	}
 

fs/ceph/mds_client.c

···
 /*
  * called under s_mutex
  */
-static void send_cap_releases(struct ceph_mds_client *mdsc,
-		       struct ceph_mds_session *session)
+void ceph_send_cap_releases(struct ceph_mds_client *mdsc,
+			    struct ceph_mds_session *session)
 {
 	struct ceph_msg *msg;
 
···
 		add_cap_releases(mdsc, s, -1);
 		if (s->s_state == CEPH_MDS_SESSION_OPEN ||
 		    s->s_state == CEPH_MDS_SESSION_HUNG)
-			send_cap_releases(mdsc, s);
+			ceph_send_cap_releases(mdsc, s);
 		mutex_unlock(&s->s_mutex);
 		ceph_put_mds_session(s);
 

fs/ceph/mds_client.h

···
 	kref_put(&req->r_kref, ceph_mdsc_release_request);
 }
 
+extern void ceph_send_cap_releases(struct ceph_mds_client *mdsc,
+				   struct ceph_mds_session *session);
+
 extern void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc);
 
 extern char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *base,