1 files changed, 210 insertions, 95 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index b7bda5d9611..92a2548278f 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3,6 +3,7 @@
 #include <linux/fs.h>
 #include <linux/wait.h>
 #include <linux/slab.h>
+#include <linux/gfp.h>
 #include <linux/sched.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
@@ -43,6 +44,7 @@
  */
 
 struct ceph_reconnect_state {
+	int nr_caps;
 	struct ceph_pagelist *pagelist;
 	bool flock;
 };
@@ -62,7 +64,7 @@ static const struct ceph_connection_operations mds_con_ops;
  */
 static int parse_reply_info_in(void **p, void *end,
 			       struct ceph_mds_reply_info_in *info,
-			       int features)
+			       u64 features)
 {
 	int err = -EIO;
 
@@ -97,7 +99,7 @@ bad:
  */
 static int parse_reply_info_trace(void **p, void *end,
 				  struct ceph_mds_reply_info_parsed *info,
-				  int features)
+				  u64 features)
 {
 	int err;
 
@@ -144,7 +146,7 @@ out_bad:
  */
 static int parse_reply_info_dir(void **p, void *end,
 				struct ceph_mds_reply_info_parsed *info,
-				int features)
+				u64 features)
 {
 	u32 num, i = 0;
 	int err;
@@ -164,21 +166,18 @@ static int parse_reply_info_dir(void **p, void *end,
 	if (num == 0)
 		goto done;
 
-	/* alloc large array */
-	info->dir_nr = num;
-	info->dir_in = kcalloc(num, sizeof(*info->dir_in) +
-			       sizeof(*info->dir_dname) +
-			       sizeof(*info->dir_dname_len) +
-			       sizeof(*info->dir_dlease),
-			       GFP_NOFS);
-	if (info->dir_in == NULL) {
-		err = -ENOMEM;
-		goto out_bad;
-	}
+	BUG_ON(!info->dir_in);
 	info->dir_dname = (void *)(info->dir_in + num);
 	info->dir_dname_len = (void *)(info->dir_dname + num);
 	info->dir_dlease = (void *)(info->dir_dname_len + num);
+	if ((unsigned long)(info->dir_dlease + num) >
+	    (unsigned long)info->dir_in + info->dir_buf_size) {
+		pr_err("dir contents are larger than expected\n");
+		WARN_ON(1);
+		goto bad;
+	}
 
+	info->dir_nr = num;
 	while (num) {
 		/* dentry */
 		ceph_decode_need(p, end, sizeof(u32)*2, bad);
@@ -216,7 +215,7 @@ out_bad:
  */
 static int parse_reply_info_filelock(void **p, void *end,
 				     struct ceph_mds_reply_info_parsed *info,
-				     int features)
+				     u64 features)
 {
 	if (*p + sizeof(*info->filelock_reply) > end)
 		goto bad;
@@ -237,7 +236,7 @@ bad:
  */
 static int parse_reply_info_create(void **p, void *end,
 				  struct ceph_mds_reply_info_parsed *info,
-				  int features)
+				  u64 features)
 {
 	if (features & CEPH_FEATURE_REPLY_CREATE_INODE) {
 		if (*p == end) {
@@ -261,7 +260,7 @@ bad:
  */
 static int parse_reply_info_extra(void **p, void *end,
 				  struct ceph_mds_reply_info_parsed *info,
-				  int features)
+				  u64 features)
 {
 	if (info->head->op == CEPH_MDS_OP_GETFILELOCK)
 		return parse_reply_info_filelock(p, end, info, features);
@@ -279,7 +278,7 @@ static int parse_reply_info_extra(void **p, void *end,
  */
 static int parse_reply_info(struct ceph_msg *msg,
 			    struct ceph_mds_reply_info_parsed *info,
-			    int features)
+			    u64 features)
 {
 	void *p, *end;
 	u32 len;
@@ -326,7 +325,9 @@ out_bad:
 
 static void destroy_reply_info(struct ceph_mds_reply_info_parsed *info)
 {
-	kfree(info->dir_in);
+	if (!info->dir_in)
+		return;
+	free_pages((unsigned long)info->dir_in, get_order(info->dir_buf_size));
 }
 
 
@@ -443,6 +444,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 	INIT_LIST_HEAD(&s->s_waiting);
 	INIT_LIST_HEAD(&s->s_unsafe);
 	s->s_num_cap_releases = 0;
+	s->s_cap_reconnect = 0;
 	s->s_cap_iterator = NULL;
 	INIT_LIST_HEAD(&s->s_cap_releases);
 	INIT_LIST_HEAD(&s->s_cap_releases_done);
@@ -510,12 +512,11 @@ void ceph_mdsc_release_request(struct kref *kref)
 	struct ceph_mds_request *req = container_of(kref,
 						    struct ceph_mds_request,
 						    r_kref);
+	destroy_reply_info(&req->r_reply_info);
 	if (req->r_request)
 		ceph_msg_put(req->r_request);
-	if (req->r_reply) {
+	if (req->r_reply)
 		ceph_msg_put(req->r_reply);
-		destroy_reply_info(&req->r_reply_info);
-	}
 	if (req->r_inode) {
 		ceph_put_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
 		iput(req->r_inode);
@@ -526,7 +527,9 @@ void ceph_mdsc_release_request(struct kref *kref)
 		iput(req->r_target_inode);
 	if (req->r_dentry)
 		dput(req->r_dentry);
-	if (req->r_old_dentry) {
+	if (req->r_old_dentry)
+		dput(req->r_old_dentry);
+	if (req->r_old_dentry_dir) {
 		/*
 		 * track (and drop pins for) r_old_dentry_dir
 		 * separately, since r_old_dentry's d_parent may have
@@ -535,7 +538,6 @@ void ceph_mdsc_release_request(struct kref *kref)
 		 */
 		ceph_put_cap_refs(ceph_inode(req->r_old_dentry_dir),
 				  CEPH_CAP_PIN);
-		dput(req->r_old_dentry);
 		iput(req->r_old_dentry_dir);
 	}
 	kfree(req->r_path1);
@@ -642,6 +644,8 @@ static void __unregister_request(struct ceph_mds_client *mdsc,
 		req->r_unsafe_dir = NULL;
 	}
 
+	complete_all(&req->r_safe_completion);
+
 	ceph_mdsc_put_request(req);
 }
 
@@ -709,14 +713,15 @@ static int __choose_mds(struct ceph_mds_client *mdsc,
 			struct dentry *dn = get_nonsnap_parent(parent);
 			inode = dn->d_inode;
 			dout("__choose_mds using nonsnap parent %p\n", inode);
-		} else if (req->r_dentry->d_inode) {
+		} else {
 			/* dentry target */
 			inode = req->r_dentry->d_inode;
-		} else {
-			/* dir + name */
-			inode = dir;
-			hash = ceph_dentry_hash(dir, req->r_dentry);
-			is_hash = true;
+			if (!inode || mode == USE_AUTH_MDS) {
+				/* dir + name */
+				inode = dir;
+				hash = ceph_dentry_hash(dir, req->r_dentry);
+				is_hash = true;
+			}
 		}
 	}
 
@@ -842,35 +847,56 @@ static int __open_session(struct ceph_mds_client *mdsc,
  *
  * called under mdsc->mutex
  */
+static struct ceph_mds_session *
+__open_export_target_session(struct ceph_mds_client *mdsc, int target)
+{
+	struct ceph_mds_session *session;
+
+	session = __ceph_lookup_mds_session(mdsc, target);
+	if (!session) {
+		session = register_session(mdsc, target);
+		if (IS_ERR(session))
+			return session;
+	}
+	if (session->s_state == CEPH_MDS_SESSION_NEW ||
+	    session->s_state == CEPH_MDS_SESSION_CLOSING)
+		__open_session(mdsc, session);
+
+	return session;
+}
+
+struct ceph_mds_session *
+ceph_mdsc_open_export_target_session(struct ceph_mds_client *mdsc, int target)
+{
+	struct ceph_mds_session *session;
+
+	dout("open_export_target_session to mds%d\n", target);
+
+	mutex_lock(&mdsc->mutex);
+	session = __open_export_target_session(mdsc, target);
+	mutex_unlock(&mdsc->mutex);
+
+	return session;
+}
+
 static void __open_export_target_sessions(struct ceph_mds_client *mdsc,
 					  struct ceph_mds_session *session)
 {
 	struct ceph_mds_info *mi;
 	struct ceph_mds_session *ts;
 	int i, mds = session->s_mds;
-	int target;
 
 	if (mds >= mdsc->mdsmap->m_max_mds)
 		return;
+
 	mi = &mdsc->mdsmap->m_info[mds];
 	dout("open_export_target_sessions for mds%d (%d targets)\n",
 	     session->s_mds, mi->num_export_targets);
 
 	for (i = 0; i < mi->num_export_targets; i++) {
-		target = mi->export_targets[i];
-		ts = __ceph_lookup_mds_session(mdsc, target);
-		if (!ts) {
-			ts = register_session(mdsc, target);
-			if (IS_ERR(ts))
-				return;
-		}
-		if (session->s_state == CEPH_MDS_SESSION_NEW ||
-		    session->s_state == CEPH_MDS_SESSION_CLOSING)
-			__open_session(mdsc, session);
-		else
-			dout(" mds%d target mds%d %p is %s\n", session->s_mds,
-			     i, ts, session_state_name(ts->s_state));
-		ceph_put_mds_session(ts);
+		ts = __open_export_target_session(mdsc, mi->export_targets[i]);
+		if (!IS_ERR(ts))
+			ceph_put_mds_session(ts);
 	}
 }
 
@@ -986,7 +1012,7 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
 	dout("removing cap %p, ci is %p, inode is %p\n",
 	     cap, ci, &ci->vfs_inode);
 	spin_lock(&ci->i_ceph_lock);
-	__ceph_remove_cap(cap);
+	__ceph_remove_cap(cap, false);
 	if (!__ceph_is_any_real_caps(ci)) {
 		struct ceph_mds_client *mdsc =
 			ceph_sb_to_client(inode->i_sb)->mdsc;
@@ -1132,6 +1158,21 @@ static int send_renew_caps(struct ceph_mds_client *mdsc,
 	return 0;
 }
 
+static int send_flushmsg_ack(struct ceph_mds_client *mdsc,
+			     struct ceph_mds_session *session, u64 seq)
+{
+	struct ceph_msg *msg;
+
+	dout("send_flushmsg_ack to mds%d (%s)s seq %lld\n",
+	     session->s_mds, session_state_name(session->s_state), seq);
+	msg = create_session_msg(CEPH_SESSION_FLUSHMSG_ACK, seq);
+	if (!msg)
+		return -ENOMEM;
+	ceph_con_send(&session->s_con, msg);
+	return 0;
+}
+
+
 /*
  * Note new cap ttl, and any transition from stale -> not stale (fresh?).
  *
@@ -1210,7 +1251,7 @@ static int trim_caps_cb(struct inode *inode, struct ceph_cap *cap, void *arg)
 {
 	struct ceph_mds_session *session = arg;
 	struct ceph_inode_info *ci = ceph_inode(inode);
-	int used, oissued, mine;
+	int used, wanted, oissued, mine;
 
 	if (session->s_trim_caps <= 0)
 		return -1;
@@ -1218,22 +1259,25 @@ static int trim_caps_cb(struct inode *inode, struct ceph_cap *cap, void *arg)
 	spin_lock(&ci->i_ceph_lock);
 	mine = cap->issued | cap->implemented;
 	used = __ceph_caps_used(ci);
+	wanted = __ceph_caps_file_wanted(ci);
 	oissued = __ceph_caps_issued_other(ci, cap);
 
-	dout("trim_caps_cb %p cap %p mine %s oissued %s used %s\n",
+	dout("trim_caps_cb %p cap %p mine %s oissued %s used %s wanted %s\n",
 	     inode, cap, ceph_cap_string(mine), ceph_cap_string(oissued),
-	     ceph_cap_string(used));
-	if (ci->i_dirty_caps)
-		goto out;   /* dirty caps */
-	if ((used & ~oissued) & mine)
+	     ceph_cap_string(used), ceph_cap_string(wanted));
+	if (cap == ci->i_auth_cap) {
+		if (ci->i_dirty_caps | ci->i_flushing_caps)
+			goto out;
+		if ((used | wanted) & CEPH_CAP_ANY_WR)
+			goto out;
+	}
+	if ((used | wanted) & ~oissued & mine)
 		goto out;   /* we need these caps */
 
 	session->s_trim_caps--;
 	if (oissued) {
 		/* we aren't the only cap.. just remove us */
-		__queue_cap_release(session, ceph_ino(inode), cap->cap_id,
-				    cap->mseq, cap->issue_seq);
-		__ceph_remove_cap(cap);
+		__ceph_remove_cap(cap, true);
 	} else {
 		/* try to drop referring dentries */
 		spin_unlock(&ci->i_ceph_lock);
@@ -1267,6 +1311,9 @@ static int trim_caps(struct ceph_mds_client *mdsc,
 			trim_caps - session->s_trim_caps);
 		session->s_trim_caps = 0;
 	}
+
+	ceph_add_cap_releases(mdsc, session);
+	ceph_send_cap_releases(mdsc, session);
 	return 0;
 }
 
@@ -1416,17 +1463,19 @@ static void discard_cap_releases(struct ceph_mds_client *mdsc,
 	unsigned num;
 
 	dout("discard_cap_releases mds%d\n", session->s_mds);
-	spin_lock(&session->s_cap_lock);
 
-	/* zero out the in-progress message */
-	msg = list_first_entry(&session->s_cap_releases,
-			       struct ceph_msg, list_head);
-	head = msg->front.iov_base;
-	num = le32_to_cpu(head->num);
-	dout("discard_cap_releases mds%d %p %u\n", session->s_mds, msg, num);
-	head->num = cpu_to_le32(0);
-	msg->front.iov_len = sizeof(*head);
-	session->s_num_cap_releases += num;
+	if (!list_empty(&session->s_cap_releases)) {
+		/* zero out the in-progress message */
+		msg = list_first_entry(&session->s_cap_releases,
+					struct ceph_msg, list_head);
+		head = msg->front.iov_base;
+		num = le32_to_cpu(head->num);
+		dout("discard_cap_releases mds%d %p %u\n",
+		     session->s_mds, msg, num);
+		head->num = cpu_to_le32(0);
+		msg->front.iov_len = sizeof(*head);
+		session->s_num_cap_releases += num;
+	}
 
 	/* requeue completed messages */
 	while (!list_empty(&session->s_cap_releases_done)) {
@@ -1443,14 +1492,49 @@ static void discard_cap_releases(struct ceph_mds_client *mdsc,
 		msg->front.iov_len = sizeof(*head);
 		list_add(&msg->list_head, &session->s_cap_releases);
 	}
-
-	spin_unlock(&session->s_cap_lock);
 }
 
 /*
  * requests
  */
 
+int ceph_alloc_readdir_reply_buffer(struct ceph_mds_request *req,
+				    struct inode *dir)
+{
+	struct ceph_inode_info *ci = ceph_inode(dir);
+	struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
+	struct ceph_mount_options *opt = req->r_mdsc->fsc->mount_options;
+	size_t size = sizeof(*rinfo->dir_in) + sizeof(*rinfo->dir_dname_len) +
+		      sizeof(*rinfo->dir_dname) + sizeof(*rinfo->dir_dlease);
+	int order, num_entries;
+
+	spin_lock(&ci->i_ceph_lock);
+	num_entries = ci->i_files + ci->i_subdirs;
+	spin_unlock(&ci->i_ceph_lock);
+	num_entries = max(num_entries, 1);
+	num_entries = min(num_entries, opt->max_readdir);
+
+	order = get_order(size * num_entries);
+	while (order >= 0) {
+		rinfo->dir_in = (void*)__get_free_pages(GFP_NOFS | __GFP_NOWARN,
+							order);
+		if (rinfo->dir_in)
+			break;
+		order--;
+	}
+	if (!rinfo->dir_in)
+		return -ENOMEM;
+
+	num_entries = (PAGE_SIZE << order) / size;
+	num_entries = min(num_entries, opt->max_readdir);
+
+	rinfo->dir_buf_size = PAGE_SIZE << order;
+	req->r_num_caps = num_entries + 1;
+	req->r_args.readdir.max_entries = cpu_to_le32(num_entries);
+	req->r_args.readdir.max_bytes = cpu_to_le32(opt->max_readdir_bytes);
+	return 0;
+}
+
 /*
  * Create an mds request.
  */
@@ -1474,6 +1558,8 @@ ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
 	init_completion(&req->r_safe_completion);
 	INIT_LIST_HEAD(&req->r_unsafe_item);
 
+	req->r_stamp = CURRENT_TIME;
+
 	req->r_op = op;
 	req->r_direct_mode = mode;
 	return req;
@@ -1699,7 +1785,8 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
 	}
 
 	len = sizeof(*head) +
-		pathlen1 + pathlen2 + 2*(1 + sizeof(u32) + sizeof(u64));
+		pathlen1 + pathlen2 + 2*(1 + sizeof(u32) + sizeof(u64)) +
+		sizeof(struct timespec);
 
 	/* calculate (max) length for cap releases */
 	len += sizeof(struct ceph_mds_request_release) *
@@ -1716,6 +1803,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
 		goto out_free2;
 	}
 
+	msg->hdr.version = 2;
 	msg->hdr.tid = cpu_to_le64(req->r_tid);
 
 	head = msg->front.iov_base;
@@ -1752,6 +1840,9 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
 		      mds, req->r_old_inode_drop, req->r_old_inode_unless, 0);
 	head->num_releases = cpu_to_le16(releases);
 
+	/* time stamp */
+	ceph_encode_copy(&p, &req->r_stamp, sizeof(req->r_stamp));
+
 	BUG_ON(p > end);
 	msg->front.iov_len = p - msg->front.iov_base;
 	msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
@@ -1875,8 +1966,11 @@ static int __do_request(struct ceph_mds_client *mdsc,
 	int mds = -1;
 	int err = -EAGAIN;
 
-	if (req->r_err || req->r_got_result)
+	if (req->r_err || req->r_got_result) {
+		if (req->r_aborted)
+			__unregister_request(mdsc, req);
 		goto out;
+	}
 
 	if (req->r_timeout &&
 	    time_after_eq(jiffies, req->r_started + req->r_timeout)) {
@@ -2009,7 +2103,7 @@ int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
 		ceph_get_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
 	if (req->r_locked_dir)
 		ceph_get_cap_refs(ceph_inode(req->r_locked_dir), CEPH_CAP_PIN);
-	if (req->r_old_dentry)
+	if (req->r_old_dentry_dir)
 		ceph_get_cap_refs(ceph_inode(req->r_old_dentry_dir),
 				  CEPH_CAP_PIN);
 
@@ -2131,13 +2225,13 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
 	/* dup? */
 	if ((req->r_got_unsafe && !head->safe) ||
 	    (req->r_got_safe && head->safe)) {
-		pr_warning("got a dup %s reply on %llu from mds%d\n",
+		pr_warn("got a dup %s reply on %llu from mds%d\n",
 			   head->safe ? "safe" : "unsafe", tid, mds);
 		mutex_unlock(&mdsc->mutex);
 		goto out;
 	}
 	if (req->r_got_safe && !head->safe) {
-		pr_warning("got unsafe after safe on %llu from mds%d\n",
+		pr_warn("got unsafe after safe on %llu from mds%d\n",
 			   tid, mds);
 		mutex_unlock(&mdsc->mutex);
 		goto out;
@@ -2154,26 +2248,16 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
 	 */
 	if (result == -ESTALE) {
 		dout("got ESTALE on request %llu", req->r_tid);
-		if (!req->r_inode) {
-			/* do nothing; not an authority problem */
-		} else if (req->r_direct_mode != USE_AUTH_MDS) {
+		if (req->r_direct_mode != USE_AUTH_MDS) {
 			dout("not using auth, setting for that now");
 			req->r_direct_mode = USE_AUTH_MDS;
 			__do_request(mdsc, req);
 			mutex_unlock(&mdsc->mutex);
 			goto out;
 		} else  {
-			struct ceph_inode_info *ci = ceph_inode(req->r_inode);
-			struct ceph_cap *cap = NULL;
-
-			if (req->r_session)
-				cap = ceph_get_cap_for_mds(ci,
-						   req->r_session->s_mds);
-
-			dout("already using auth");
-			if ((!cap || cap != ci->i_auth_cap) ||
-			    (cap->mseq != req->r_sent_on_mseq)) {
-				dout("but cap changed, so resending");
+			int mds = __choose_mds(mdsc, req);
+			if (mds >= 0 && mds != req->r_session->s_mds) {
+				dout("but auth changed, so resending");
 				__do_request(mdsc, req);
 				mutex_unlock(&mdsc->mutex);
 				goto out;
@@ -2186,7 +2270,6 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
 	if (head->safe) {
 		req->r_got_safe = true;
 		__unregister_request(mdsc, req);
-		complete_all(&req->r_safe_completion);
 
 		if (req->r_got_unsafe) {
 			/*
@@ -2238,8 +2321,7 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
 	err = ceph_fill_trace(mdsc->fsc->sb, req, req->r_session);
 	if (err == 0) {
 		if (result == 0 && (req->r_op == CEPH_MDS_OP_READDIR ||
-				    req->r_op == CEPH_MDS_OP_LSSNAP) &&
-		    rinfo->dir_nr)
+				    req->r_op == CEPH_MDS_OP_LSSNAP))
 			ceph_readdir_prepopulate(req, req->r_session);
 		ceph_unreserve_caps(mdsc, &req->r_caps_reservation);
 	}
@@ -2400,6 +2482,10 @@ static void handle_session(struct ceph_mds_session *session,
 		trim_caps(mdsc, session, le32_to_cpu(h->max_caps));
 		break;
 
+	case CEPH_SESSION_FLUSHMSG:
+		send_flushmsg_ack(mdsc, session, seq);
+		break;
+
 	default:
 		pr_err("mdsc_handle_session bad op %d mds%d\n", op, mds);
 		WARN_ON(1);
@@ -2490,6 +2576,7 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
 	cap->seq = 0;        /* reset cap seq */
 	cap->issue_seq = 0;  /* and issue_seq */
 	cap->mseq = 0;       /* and migrate_seq */
+	cap->cap_gen = cap->session->s_cap_gen;
 
 	if (recon_state->flock) {
 		rec.v2.cap_id = cpu_to_le64(cap->cap_id);
@@ -2552,6 +2639,8 @@ encode_again:
 	} else {
 		err = ceph_pagelist_append(pagelist, &rec, reclen);
 	}
+
+	recon_state->nr_caps++;
 out_free:
 	kfree(path);
 out_dput:
@@ -2579,6 +2668,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
 	struct rb_node *p;
 	int mds = session->s_mds;
 	int err = -ENOMEM;
+	int s_nr_caps;
 	struct ceph_pagelist *pagelist;
 	struct ceph_reconnect_state recon_state;
 
@@ -2610,20 +2700,38 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
 	dout("session %p state %s\n", session,
 	     session_state_name(session->s_state));
 
+	spin_lock(&session->s_gen_ttl_lock);
+	session->s_cap_gen++;
+	spin_unlock(&session->s_gen_ttl_lock);
+
+	spin_lock(&session->s_cap_lock);
+	/*
+	 * notify __ceph_remove_cap() that we are composing cap reconnect.
+	 * If a cap get released before being added to the cap reconnect,
+	 * __ceph_remove_cap() should skip queuing cap release.
+	 */
+	session->s_cap_reconnect = 1;
 	/* drop old cap expires; we're about to reestablish that state */
 	discard_cap_releases(mdsc, session);
+	spin_unlock(&session->s_cap_lock);
 
 	/* traverse this session's caps */
-	err = ceph_pagelist_encode_32(pagelist, session->s_nr_caps);
+	s_nr_caps = session->s_nr_caps;
+	err = ceph_pagelist_encode_32(pagelist, s_nr_caps);
 	if (err)
 		goto fail;
 
+	recon_state.nr_caps = 0;
 	recon_state.pagelist = pagelist;
 	recon_state.flock = session->s_con.peer_features & CEPH_FEATURE_FLOCK;
 	err = iterate_session_caps(session, encode_caps_cb, &recon_state);
 	if (err < 0)
 		goto fail;
 
+	spin_lock(&session->s_cap_lock);
+	session->s_cap_reconnect = 0;
+	spin_unlock(&session->s_cap_lock);
+
 	/*
 	 * snaprealms.  we provide mds with the ino, seq (version), and
 	 * parent for all of our realms.  If the mds has any newer info,
@@ -2646,11 +2754,18 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
 
 	if (recon_state.flock)
 		reply->hdr.version = cpu_to_le16(2);
-	if (pagelist->length) {
-		/* set up outbound data if we have any */
-		reply->hdr.data_len = cpu_to_le32(pagelist->length);
-		ceph_msg_data_add_pagelist(reply, pagelist);
+
+	/* raced with cap release? */
+	if (s_nr_caps != recon_state.nr_caps) {
+		struct page *page = list_first_entry(&pagelist->head,
+						     struct page, lru);
+		__le32 *addr = kmap_atomic(page);
+		*addr = cpu_to_le32(recon_state.nr_caps);
+		kunmap_atomic(addr);
 	}
+
+	reply->hdr.data_len = cpu_to_le32(pagelist->length);
+	ceph_msg_data_add_pagelist(reply, pagelist);
 	ceph_con_send(&session->s_con, reply);
 
 	mutex_unlock(&session->s_mutex);
@@ -3417,7 +3532,7 @@ static void peer_reset(struct ceph_connection *con)
 	struct ceph_mds_session *s = con->private;
 	struct ceph_mds_client *mdsc = s->s_mdsc;
 
-	pr_warning("mds%d closed our session\n", s->s_mds);
+	pr_warn("mds%d closed our session\n", s->s_mds);
 	send_mds_reconnect(mdsc, s);
 }