Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1369 insertions, 0 deletions

diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
new file mode 100644
index 000000000..a53e4fbb6
--- /dev/null
+++ b/net/ceph/mon_client.c
@@ -0,0 +1,1369 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/sched.h>
+
+#include <linux/ceph/ceph_features.h>
+#include <linux/ceph/mon_client.h>
+#include <linux/ceph/libceph.h>
+#include <linux/ceph/debugfs.h>
+#include <linux/ceph/decode.h>
+#include <linux/ceph/auth.h>
+
+/*
+ * Interact with Ceph monitor cluster.  Handle requests for new map
+ * versions, and periodically resend as needed.  Also implement
+ * statfs() and umount().
+ *
+ * A small cluster of Ceph "monitors" are responsible for managing critical
+ * cluster configuration and state information.  An odd number (e.g., 3, 5)
+ * of cmon daemons use a modified version of the Paxos part-time parliament
+ * algorithm to manage the MDS map (mds cluster membership), OSD map, and
+ * list of clients who have mounted the file system.
+ *
+ * We maintain an open, active session with a monitor at all times in order to
+ * receive timely MDSMap updates.  We periodically send a keepalive byte on the
+ * TCP socket to ensure we detect a failure.  If the connection does break, we
+ * randomly hunt for a new monitor.  Once the connection is reestablished, we
+ * resend any outstanding requests.
+ */
+
+static const struct ceph_connection_operations mon_con_ops;
+
+static int __validate_auth(struct ceph_mon_client *monc);
+
+/*
+ * Decode a monmap blob (e.g., during mount).
+ */
+struct ceph_monmap *ceph_monmap_decode(void *p, void *end)
+{
+	struct ceph_monmap *m = NULL;
+	int i, err = -EINVAL;
+	struct ceph_fsid fsid;
+	u32 epoch, num_mon;
+	u32 len;
+
+	ceph_decode_32_safe(&p, end, len, bad);
+	ceph_decode_need(&p, end, len, bad);
+
+	dout("monmap_decode %p %p len %d\n", p, end, (int)(end-p));
+	p += sizeof(u16);  /* skip version */
+
+	ceph_decode_need(&p, end, sizeof(fsid) + 2*sizeof(u32), bad);
+	ceph_decode_copy(&p, &fsid, sizeof(fsid));
+	epoch = ceph_decode_32(&p);
+
+	num_mon = ceph_decode_32(&p);
+	ceph_decode_need(&p, end, num_mon*sizeof(m->mon_inst[0]), bad);
+
+	if (num_mon > CEPH_MAX_MON)
+		goto bad;
+	m = kmalloc(struct_size(m, mon_inst, num_mon), GFP_NOFS);
+	if (m == NULL)
+		return ERR_PTR(-ENOMEM);
+	m->fsid = fsid;
+	m->epoch = epoch;
+	m->num_mon = num_mon;
+	ceph_decode_copy(&p, m->mon_inst, num_mon*sizeof(m->mon_inst[0]));
+	for (i = 0; i < num_mon; i++)
+		ceph_decode_addr(&m->mon_inst[i].addr);
+
+	dout("monmap_decode epoch %d, num_mon %d\n", m->epoch,
+	     m->num_mon);
+	for (i = 0; i < m->num_mon; i++)
+		dout("monmap_decode  mon%d is %s\n", i,
+		     ceph_pr_addr(&m->mon_inst[i].addr.in_addr));
+	return m;
+
+bad:
+	dout("monmap_decode failed with %d\n", err);
+	kfree(m);
+	return ERR_PTR(err);
+}
+
+/*
+ * return true if *addr is included in the monmap.
+ */
+int ceph_monmap_contains(struct ceph_monmap *m, struct ceph_entity_addr *addr)
+{
+	int i;
+
+	for (i = 0; i < m->num_mon; i++)
+		if (memcmp(addr, &m->mon_inst[i].addr, sizeof(*addr)) == 0)
+			return 1;
+	return 0;
+}
+
+/*
+ * Send an auth request.
+ */
+static void __send_prepared_auth_request(struct ceph_mon_client *monc, int len)
+{
+	monc->pending_auth = 1;
+	monc->m_auth->front.iov_len = len;
+	monc->m_auth->hdr.front_len = cpu_to_le32(len);
+	ceph_msg_revoke(monc->m_auth);
+	ceph_msg_get(monc->m_auth);  /* keep our ref */
+	ceph_con_send(&monc->con, monc->m_auth);
+}
+
+/*
+ * Close monitor session, if any.
+ */
+static void __close_session(struct ceph_mon_client *monc)
+{
+	dout("__close_session closing mon%d\n", monc->cur_mon);
+	ceph_msg_revoke(monc->m_auth);
+	ceph_msg_revoke_incoming(monc->m_auth_reply);
+	ceph_msg_revoke(monc->m_subscribe);
+	ceph_msg_revoke_incoming(monc->m_subscribe_ack);
+	ceph_con_close(&monc->con);
+
+	monc->pending_auth = 0;
+	ceph_auth_reset(monc->auth);
+}
+
+/*
+ * Pick a new monitor at random and set cur_mon.  If we are repicking
+ * (i.e. cur_mon is already set), be sure to pick a different one.
+ */
+static void pick_new_mon(struct ceph_mon_client *monc)
+{
+	int old_mon = monc->cur_mon;
+
+	BUG_ON(monc->monmap->num_mon < 1);
+
+	if (monc->monmap->num_mon == 1) {
+		monc->cur_mon = 0;
+	} else {
+		int max = monc->monmap->num_mon;
+		int o = -1;
+		int n;
+
+		if (monc->cur_mon >= 0) {
+			if (monc->cur_mon < monc->monmap->num_mon)
+				o = monc->cur_mon;
+			if (o >= 0)
+				max--;
+		}
+
+		n = prandom_u32() % max;
+		if (o >= 0 && n >= o)
+			n++;
+
+		monc->cur_mon = n;
+	}
+
+	dout("%s mon%d -> mon%d out of %d mons\n", __func__, old_mon,
+	     monc->cur_mon, monc->monmap->num_mon);
+}
+
+/*
+ * Open a session with a new monitor.
+ */
+static void __open_session(struct ceph_mon_client *monc)
+{
+	int ret;
+
+	pick_new_mon(monc);
+
+	monc->hunting = true;
+	if (monc->had_a_connection) {
+		monc->hunt_mult *= CEPH_MONC_HUNT_BACKOFF;
+		if (monc->hunt_mult > CEPH_MONC_HUNT_MAX_MULT)
+			monc->hunt_mult = CEPH_MONC_HUNT_MAX_MULT;
+	}
+
+	monc->sub_renew_after = jiffies; /* i.e., expired */
+	monc->sub_renew_sent = 0;
+
+	dout("%s opening mon%d\n", __func__, monc->cur_mon);
+	ceph_con_open(&monc->con, CEPH_ENTITY_TYPE_MON, monc->cur_mon,
+		      &monc->monmap->mon_inst[monc->cur_mon].addr);
+
+	/*
+	 * send an initial keepalive to ensure our timestamp is valid
+	 * by the time we are in an OPENED state
+	 */
+	ceph_con_keepalive(&monc->con);
+
+	/* initiate authentication handshake */
+	ret = ceph_auth_build_hello(monc->auth,
+				    monc->m_auth->front.iov_base,
+				    monc->m_auth->front_alloc_len);
+	BUG_ON(ret <= 0);
+	__send_prepared_auth_request(monc, ret);
+}
+
+static void reopen_session(struct ceph_mon_client *monc)
+{
+	if (!monc->hunting)
+		pr_info("mon%d %s session lost, hunting for new mon\n",
+		    monc->cur_mon, ceph_pr_addr(&monc->con.peer_addr.in_addr));
+
+	__close_session(monc);
+	__open_session(monc);
+}
+
+static void un_backoff(struct ceph_mon_client *monc)
+{
+	monc->hunt_mult /= 2; /* reduce by 50% */
+	if (monc->hunt_mult < 1)
+		monc->hunt_mult = 1;
+	dout("%s hunt_mult now %d\n", __func__, monc->hunt_mult);
+}
+
+/*
+ * Reschedule delayed work timer.
+ */
+static void __schedule_delayed(struct ceph_mon_client *monc)
+{
+	unsigned long delay;
+
+	if (monc->hunting)
+		delay = CEPH_MONC_HUNT_INTERVAL * monc->hunt_mult;
+	else
+		delay = CEPH_MONC_PING_INTERVAL;
+
+	dout("__schedule_delayed after %lu\n", delay);
+	mod_delayed_work(system_wq, &monc->delayed_work,
+			 round_jiffies_relative(delay));
+}
+
+const char *ceph_sub_str[] = {
+	[CEPH_SUB_MONMAP] = "monmap",
+	[CEPH_SUB_OSDMAP] = "osdmap",
+	[CEPH_SUB_FSMAP]  = "fsmap.user",
+	[CEPH_SUB_MDSMAP] = "mdsmap",
+};
+
+/*
+ * Send subscribe request for one or more maps, according to
+ * monc->subs.
+ */
+static void __send_subscribe(struct ceph_mon_client *monc)
+{
+	struct ceph_msg *msg = monc->m_subscribe;
+	void *p = msg->front.iov_base;
+	void *const end = p + msg->front_alloc_len;
+	int num = 0;
+	int i;
+
+	dout("%s sent %lu\n", __func__, monc->sub_renew_sent);
+
+	BUG_ON(monc->cur_mon < 0);
+
+	if (!monc->sub_renew_sent)
+		monc->sub_renew_sent = jiffies | 1; /* never 0 */
+
+	msg->hdr.version = cpu_to_le16(2);
+
+	for (i = 0; i < ARRAY_SIZE(monc->subs); i++) {
+		if (monc->subs[i].want)
+			num++;
+	}
+	BUG_ON(num < 1); /* monmap sub is always there */
+	ceph_encode_32(&p, num);
+	for (i = 0; i < ARRAY_SIZE(monc->subs); i++) {
+		char buf[32];
+		int len;
+
+		if (!monc->subs[i].want)
+			continue;
+
+		len = sprintf(buf, "%s", ceph_sub_str[i]);
+		if (i == CEPH_SUB_MDSMAP &&
+		    monc->fs_cluster_id != CEPH_FS_CLUSTER_ID_NONE)
+			len += sprintf(buf + len, ".%d", monc->fs_cluster_id);
+
+		dout("%s %s start %llu flags 0x%x\n", __func__, buf,
+		     le64_to_cpu(monc->subs[i].item.start),
+		     monc->subs[i].item.flags);
+		ceph_encode_string(&p, end, buf, len);
+		memcpy(p, &monc->subs[i].item, sizeof(monc->subs[i].item));
+		p += sizeof(monc->subs[i].item);
+	}
+
+	BUG_ON(p > end);
+	msg->front.iov_len = p - msg->front.iov_base;
+	msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
+	ceph_msg_revoke(msg);
+	ceph_con_send(&monc->con, ceph_msg_get(msg));
+}
+
+static void handle_subscribe_ack(struct ceph_mon_client *monc,
+				 struct ceph_msg *msg)
+{
+	unsigned int seconds;
+	struct ceph_mon_subscribe_ack *h = msg->front.iov_base;
+
+	if (msg->front.iov_len < sizeof(*h))
+		goto bad;
+	seconds = le32_to_cpu(h->duration);
+
+	mutex_lock(&monc->mutex);
+	if (monc->sub_renew_sent) {
+		/*
+		 * This is only needed for legacy (infernalis or older)
+		 * MONs -- see delayed_work().
+		 */
+		monc->sub_renew_after = monc->sub_renew_sent +
+					    (seconds >> 1) * HZ - 1;
+		dout("%s sent %lu duration %d renew after %lu\n", __func__,
+		     monc->sub_renew_sent, seconds, monc->sub_renew_after);
+		monc->sub_renew_sent = 0;
+	} else {
+		dout("%s sent %lu renew after %lu, ignoring\n", __func__,
+		     monc->sub_renew_sent, monc->sub_renew_after);
+	}
+	mutex_unlock(&monc->mutex);
+	return;
+bad:
+	pr_err("got corrupt subscribe-ack msg\n");
+	ceph_msg_dump(msg);
+}
+
+/*
+ * Register interest in a map
+ *
+ * @sub: one of CEPH_SUB_*
+ * @epoch: X for "every map since X", or 0 for "just the latest"
+ */
+static bool __ceph_monc_want_map(struct ceph_mon_client *monc, int sub,
+				 u32 epoch, bool continuous)
+{
+	__le64 start = cpu_to_le64(epoch);
+	u8 flags = !continuous ? CEPH_SUBSCRIBE_ONETIME : 0;
+
+	dout("%s %s epoch %u continuous %d\n", __func__, ceph_sub_str[sub],
+	     epoch, continuous);
+
+	if (monc->subs[sub].want &&
+	    monc->subs[sub].item.start == start &&
+	    monc->subs[sub].item.flags == flags)
+		return false;
+
+	monc->subs[sub].item.start = start;
+	monc->subs[sub].item.flags = flags;
+	monc->subs[sub].want = true;
+
+	return true;
+}
+
+bool ceph_monc_want_map(struct ceph_mon_client *monc, int sub, u32 epoch,
+			bool continuous)
+{
+	bool need_request;
+
+	mutex_lock(&monc->mutex);
+	need_request = __ceph_monc_want_map(monc, sub, epoch, continuous);
+	mutex_unlock(&monc->mutex);
+
+	return need_request;
+}
+EXPORT_SYMBOL(ceph_monc_want_map);
+
+/*
+ * Keep track of which maps we have
+ *
+ * @sub: one of CEPH_SUB_*
+ */
+static void __ceph_monc_got_map(struct ceph_mon_client *monc, int sub,
+				u32 epoch)
+{
+	dout("%s %s epoch %u\n", __func__, ceph_sub_str[sub], epoch);
+
+	if (monc->subs[sub].want) {
+		if (monc->subs[sub].item.flags & CEPH_SUBSCRIBE_ONETIME)
+			monc->subs[sub].want = false;
+		else
+			monc->subs[sub].item.start = cpu_to_le64(epoch + 1);
+	}
+
+	monc->subs[sub].have = epoch;
+}
+
+void ceph_monc_got_map(struct ceph_mon_client *monc, int sub, u32 epoch)
+{
+	mutex_lock(&monc->mutex);
+	__ceph_monc_got_map(monc, sub, epoch);
+	mutex_unlock(&monc->mutex);
+}
+EXPORT_SYMBOL(ceph_monc_got_map);
+
+void ceph_monc_renew_subs(struct ceph_mon_client *monc)
+{
+	mutex_lock(&monc->mutex);
+	__send_subscribe(monc);
+	mutex_unlock(&monc->mutex);
+}
+EXPORT_SYMBOL(ceph_monc_renew_subs);
+
+/*
+ * Wait for an osdmap with a given epoch.
+ *
+ * @epoch: epoch to wait for
+ * @timeout: in jiffies, 0 means "wait forever"
+ */
+int ceph_monc_wait_osdmap(struct ceph_mon_client *monc, u32 epoch,
+			  unsigned long timeout)
+{
+	unsigned long started = jiffies;
+	long ret;
+
+	mutex_lock(&monc->mutex);
+	while (monc->subs[CEPH_SUB_OSDMAP].have < epoch) {
+		mutex_unlock(&monc->mutex);
+
+		if (timeout && time_after_eq(jiffies, started + timeout))
+			return -ETIMEDOUT;
+
+		ret = wait_event_interruptible_timeout(monc->client->auth_wq,
+				     monc->subs[CEPH_SUB_OSDMAP].have >= epoch,
+				     ceph_timeout_jiffies(timeout));
+		if (ret < 0)
+			return ret;
+
+		mutex_lock(&monc->mutex);
+	}
+
+	mutex_unlock(&monc->mutex);
+	return 0;
+}
+EXPORT_SYMBOL(ceph_monc_wait_osdmap);
+
+/*
+ * Open a session with a random monitor.  Request monmap and osdmap,
+ * which are waited upon in __ceph_open_session().
+ */
+int ceph_monc_open_session(struct ceph_mon_client *monc)
+{
+	mutex_lock(&monc->mutex);
+	__ceph_monc_want_map(monc, CEPH_SUB_MONMAP, 0, true);
+	__ceph_monc_want_map(monc, CEPH_SUB_OSDMAP, 0, false);
+	__open_session(monc);
+	__schedule_delayed(monc);
+	mutex_unlock(&monc->mutex);
+	return 0;
+}
+EXPORT_SYMBOL(ceph_monc_open_session);
+
+static void ceph_monc_handle_map(struct ceph_mon_client *monc,
+				 struct ceph_msg *msg)
+{
+	struct ceph_client *client = monc->client;
+	struct ceph_monmap *monmap = NULL, *old = monc->monmap;
+	void *p, *end;
+
+	mutex_lock(&monc->mutex);
+
+	dout("handle_monmap\n");
+	p = msg->front.iov_base;
+	end = p + msg->front.iov_len;
+
+	monmap = ceph_monmap_decode(p, end);
+	if (IS_ERR(monmap)) {
+		pr_err("problem decoding monmap, %d\n",
+		       (int)PTR_ERR(monmap));
+		goto out;
+	}
+
+	if (ceph_check_fsid(monc->client, &monmap->fsid) < 0) {
+		kfree(monmap);
+		goto out;
+	}
+
+	client->monc.monmap = monmap;
+	kfree(old);
+
+	__ceph_monc_got_map(monc, CEPH_SUB_MONMAP, monc->monmap->epoch);
+	client->have_fsid = true;
+
+out:
+	mutex_unlock(&monc->mutex);
+	wake_up_all(&client->auth_wq);
+}
+
+/*
+ * generic requests (currently statfs, mon_get_version)
+ */
+DEFINE_RB_FUNCS(generic_request, struct ceph_mon_generic_request, tid, node)
+
+static void release_generic_request(struct kref *kref)
+{
+	struct ceph_mon_generic_request *req =
+		container_of(kref, struct ceph_mon_generic_request, kref);
+
+	dout("%s greq %p request %p reply %p\n", __func__, req, req->request,
+	     req->reply);
+	WARN_ON(!RB_EMPTY_NODE(&req->node));
+
+	if (req->reply)
+		ceph_msg_put(req->reply);
+	if (req->request)
+		ceph_msg_put(req->request);
+
+	kfree(req);
+}
+
+static void put_generic_request(struct ceph_mon_generic_request *req)
+{
+	if (req)
+		kref_put(&req->kref, release_generic_request);
+}
+
+static void get_generic_request(struct ceph_mon_generic_request *req)
+{
+	kref_get(&req->kref);
+}
+
+static struct ceph_mon_generic_request *
+alloc_generic_request(struct ceph_mon_client *monc, gfp_t gfp)
+{
+	struct ceph_mon_generic_request *req;
+
+	req = kzalloc(sizeof(*req), gfp);
+	if (!req)
+		return NULL;
+
+	req->monc = monc;
+	kref_init(&req->kref);
+	RB_CLEAR_NODE(&req->node);
+	init_completion(&req->completion);
+
+	dout("%s greq %p\n", __func__, req);
+	return req;
+}
+
+static void register_generic_request(struct ceph_mon_generic_request *req)
+{
+	struct ceph_mon_client *monc = req->monc;
+
+	WARN_ON(req->tid);
+
+	get_generic_request(req);
+	req->tid = ++monc->last_tid;
+	insert_generic_request(&monc->generic_request_tree, req);
+}
+
+static void send_generic_request(struct ceph_mon_client *monc,
+				 struct ceph_mon_generic_request *req)
+{
+	WARN_ON(!req->tid);
+
+	dout("%s greq %p tid %llu\n", __func__, req, req->tid);
+	req->request->hdr.tid = cpu_to_le64(req->tid);
+	ceph_con_send(&monc->con, ceph_msg_get(req->request));
+}
+
+static void __finish_generic_request(struct ceph_mon_generic_request *req)
+{
+	struct ceph_mon_client *monc = req->monc;
+
+	dout("%s greq %p tid %llu\n", __func__, req, req->tid);
+	erase_generic_request(&monc->generic_request_tree, req);
+
+	ceph_msg_revoke(req->request);
+	ceph_msg_revoke_incoming(req->reply);
+}
+
+static void finish_generic_request(struct ceph_mon_generic_request *req)
+{
+	__finish_generic_request(req);
+	put_generic_request(req);
+}
+
+static void complete_generic_request(struct ceph_mon_generic_request *req)
+{
+	if (req->complete_cb)
+		req->complete_cb(req);
+	else
+		complete_all(&req->completion);
+	put_generic_request(req);
+}
+
+static void cancel_generic_request(struct ceph_mon_generic_request *req)
+{
+	struct ceph_mon_client *monc = req->monc;
+	struct ceph_mon_generic_request *lookup_req;
+
+	dout("%s greq %p tid %llu\n", __func__, req, req->tid);
+
+	mutex_lock(&monc->mutex);
+	lookup_req = lookup_generic_request(&monc->generic_request_tree,
+					    req->tid);
+	if (lookup_req) {
+		WARN_ON(lookup_req != req);
+		finish_generic_request(req);
+	}
+
+	mutex_unlock(&monc->mutex);
+}
+
+static int wait_generic_request(struct ceph_mon_generic_request *req)
+{
+	int ret;
+
+	dout("%s greq %p tid %llu\n", __func__, req, req->tid);
+	ret = wait_for_completion_interruptible(&req->completion);
+	if (ret)
+		cancel_generic_request(req);
+	else
+		ret = req->result; /* completed */
+
+	return ret;
+}
+
+static struct ceph_msg *get_generic_reply(struct ceph_connection *con,
+					 struct ceph_msg_header *hdr,
+					 int *skip)
+{
+	struct ceph_mon_client *monc = con->private;
+	struct ceph_mon_generic_request *req;
+	u64 tid = le64_to_cpu(hdr->tid);
+	struct ceph_msg *m;
+
+	mutex_lock(&monc->mutex);
+	req = lookup_generic_request(&monc->generic_request_tree, tid);
+	if (!req) {
+		dout("get_generic_reply %lld dne\n", tid);
+		*skip = 1;
+		m = NULL;
+	} else {
+		dout("get_generic_reply %lld got %p\n", tid, req->reply);
+		*skip = 0;
+		m = ceph_msg_get(req->reply);
+		/*
+		 * we don't need to track the connection reading into
+		 * this reply because we only have one open connection
+		 * at a time, ever.
+		 */
+	}
+	mutex_unlock(&monc->mutex);
+	return m;
+}
+
+/*
+ * statfs
+ */
+static void handle_statfs_reply(struct ceph_mon_client *monc,
+				struct ceph_msg *msg)
+{
+	struct ceph_mon_generic_request *req;
+	struct ceph_mon_statfs_reply *reply = msg->front.iov_base;
+	u64 tid = le64_to_cpu(msg->hdr.tid);
+
+	dout("%s msg %p tid %llu\n", __func__, msg, tid);
+
+	if (msg->front.iov_len != sizeof(*reply))
+		goto bad;
+
+	mutex_lock(&monc->mutex);
+	req = lookup_generic_request(&monc->generic_request_tree, tid);
+	if (!req) {
+		mutex_unlock(&monc->mutex);
+		return;
+	}
+
+	req->result = 0;
+	*req->u.st = reply->st; /* struct */
+	__finish_generic_request(req);
+	mutex_unlock(&monc->mutex);
+
+	complete_generic_request(req);
+	return;
+
+bad:
+	pr_err("corrupt statfs reply, tid %llu\n", tid);
+	ceph_msg_dump(msg);
+}
+
+/*
+ * Do a synchronous statfs().
+ */
+int ceph_monc_do_statfs(struct ceph_mon_client *monc, u64 data_pool,
+			struct ceph_statfs *buf)
+{
+	struct ceph_mon_generic_request *req;
+	struct ceph_mon_statfs *h;
+	int ret = -ENOMEM;
+
+	req = alloc_generic_request(monc, GFP_NOFS);
+	if (!req)
+		goto out;
+
+	req->request = ceph_msg_new(CEPH_MSG_STATFS, sizeof(*h), GFP_NOFS,
+				    true);
+	if (!req->request)
+		goto out;
+
+	req->reply = ceph_msg_new(CEPH_MSG_STATFS_REPLY, 64, GFP_NOFS, true);
+	if (!req->reply)
+		goto out;
+
+	req->u.st = buf;
+	req->request->hdr.version = cpu_to_le16(2);
+
+	mutex_lock(&monc->mutex);
+	register_generic_request(req);
+	/* fill out request */
+	h = req->request->front.iov_base;
+	h->monhdr.have_version = 0;
+	h->monhdr.session_mon = cpu_to_le16(-1);
+	h->monhdr.session_mon_tid = 0;
+	h->fsid = monc->monmap->fsid;
+	h->contains_data_pool = (data_pool != CEPH_NOPOOL);
+	h->data_pool = cpu_to_le64(data_pool);
+	send_generic_request(monc, req);
+	mutex_unlock(&monc->mutex);
+
+	ret = wait_generic_request(req);
+out:
+	put_generic_request(req);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_monc_do_statfs);
+
+static void handle_get_version_reply(struct ceph_mon_client *monc,
+				     struct ceph_msg *msg)
+{
+	struct ceph_mon_generic_request *req;
+	u64 tid = le64_to_cpu(msg->hdr.tid);
+	void *p = msg->front.iov_base;
+	void *end = p + msg->front_alloc_len;
+	u64 handle;
+
+	dout("%s msg %p tid %llu\n", __func__, msg, tid);
+
+	ceph_decode_need(&p, end, 2*sizeof(u64), bad);
+	handle = ceph_decode_64(&p);
+	if (tid != 0 && tid != handle)
+		goto bad;
+
+	mutex_lock(&monc->mutex);
+	req = lookup_generic_request(&monc->generic_request_tree, handle);
+	if (!req) {
+		mutex_unlock(&monc->mutex);
+		return;
+	}
+
+	req->result = 0;
+	req->u.newest = ceph_decode_64(&p);
+	__finish_generic_request(req);
+	mutex_unlock(&monc->mutex);
+
+	complete_generic_request(req);
+	return;
+
+bad:
+	pr_err("corrupt mon_get_version reply, tid %llu\n", tid);
+	ceph_msg_dump(msg);
+}
+
+static struct ceph_mon_generic_request *
+__ceph_monc_get_version(struct ceph_mon_client *monc, const char *what,
+			ceph_monc_callback_t cb, u64 private_data)
+{
+	struct ceph_mon_generic_request *req;
+
+	req = alloc_generic_request(monc, GFP_NOIO);
+	if (!req)
+		goto err_put_req;
+
+	req->request = ceph_msg_new(CEPH_MSG_MON_GET_VERSION,
+				    sizeof(u64) + sizeof(u32) + strlen(what),
+				    GFP_NOIO, true);
+	if (!req->request)
+		goto err_put_req;
+
+	req->reply = ceph_msg_new(CEPH_MSG_MON_GET_VERSION_REPLY, 32, GFP_NOIO,
+				  true);
+	if (!req->reply)
+		goto err_put_req;
+
+	req->complete_cb = cb;
+	req->private_data = private_data;
+
+	mutex_lock(&monc->mutex);
+	register_generic_request(req);
+	{
+		void *p = req->request->front.iov_base;
+		void *const end = p + req->request->front_alloc_len;
+
+		ceph_encode_64(&p, req->tid); /* handle */
+		ceph_encode_string(&p, end, what, strlen(what));
+		WARN_ON(p != end);
+	}
+	send_generic_request(monc, req);
+	mutex_unlock(&monc->mutex);
+
+	return req;
+
+err_put_req:
+	put_generic_request(req);
+	return ERR_PTR(-ENOMEM);
+}
+
+/*
+ * Send MMonGetVersion and wait for the reply.
+ *
+ * @what: one of "mdsmap", "osdmap" or "monmap"
+ */
+int ceph_monc_get_version(struct ceph_mon_client *monc, const char *what,
+			  u64 *newest)
+{
+	struct ceph_mon_generic_request *req;
+	int ret;
+
+	req = __ceph_monc_get_version(monc, what, NULL, 0);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	ret = wait_generic_request(req);
+	if (!ret)
+		*newest = req->u.newest;
+
+	put_generic_request(req);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_monc_get_version);
+
+/*
+ * Send MMonGetVersion,
+ *
+ * @what: one of "mdsmap", "osdmap" or "monmap"
+ */
+int ceph_monc_get_version_async(struct ceph_mon_client *monc, const char *what,
+				ceph_monc_callback_t cb, u64 private_data)
+{
+	struct ceph_mon_generic_request *req;
+
+	req = __ceph_monc_get_version(monc, what, cb, private_data);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	put_generic_request(req);
+	return 0;
+}
+EXPORT_SYMBOL(ceph_monc_get_version_async);
+
+static void handle_command_ack(struct ceph_mon_client *monc,
+			       struct ceph_msg *msg)
+{
+	struct ceph_mon_generic_request *req;
+	void *p = msg->front.iov_base;
+	void *const end = p + msg->front_alloc_len;
+	u64 tid = le64_to_cpu(msg->hdr.tid);
+
+	dout("%s msg %p tid %llu\n", __func__, msg, tid);
+
+	ceph_decode_need(&p, end, sizeof(struct ceph_mon_request_header) +
+							    sizeof(u32), bad);
+	p += sizeof(struct ceph_mon_request_header);
+
+	mutex_lock(&monc->mutex);
+	req = lookup_generic_request(&monc->generic_request_tree, tid);
+	if (!req) {
+		mutex_unlock(&monc->mutex);
+		return;
+	}
+
+	req->result = ceph_decode_32(&p);
+	__finish_generic_request(req);
+	mutex_unlock(&monc->mutex);
+
+	complete_generic_request(req);
+	return;
+
+bad:
+	pr_err("corrupt mon_command ack, tid %llu\n", tid);
+	ceph_msg_dump(msg);
+}
+
+int ceph_monc_blacklist_add(struct ceph_mon_client *monc,
+			    struct ceph_entity_addr *client_addr)
+{
+	struct ceph_mon_generic_request *req;
+	struct ceph_mon_command *h;
+	int ret = -ENOMEM;
+	int len;
+
+	req = alloc_generic_request(monc, GFP_NOIO);
+	if (!req)
+		goto out;
+
+	req->request = ceph_msg_new(CEPH_MSG_MON_COMMAND, 256, GFP_NOIO, true);
+	if (!req->request)
+		goto out;
+
+	req->reply = ceph_msg_new(CEPH_MSG_MON_COMMAND_ACK, 512, GFP_NOIO,
+				  true);
+	if (!req->reply)
+		goto out;
+
+	mutex_lock(&monc->mutex);
+	register_generic_request(req);
+	h = req->request->front.iov_base;
+	h->monhdr.have_version = 0;
+	h->monhdr.session_mon = cpu_to_le16(-1);
+	h->monhdr.session_mon_tid = 0;
+	h->fsid = monc->monmap->fsid;
+	h->num_strs = cpu_to_le32(1);
+	len = sprintf(h->str, "{ \"prefix\": \"osd blacklist\", \
+		                 \"blacklistop\": \"add\", \
+				 \"addr\": \"%pISpc/%u\" }",
+		      &client_addr->in_addr, le32_to_cpu(client_addr->nonce));
+	h->str_len = cpu_to_le32(len);
+	send_generic_request(monc, req);
+	mutex_unlock(&monc->mutex);
+
+	ret = wait_generic_request(req);
+	if (!ret)
+		/*
+		 * Make sure we have the osdmap that includes the blacklist
+		 * entry.  This is needed to ensure that the OSDs pick up the
+		 * new blacklist before processing any future requests from
+		 * this client.
+		 */
+		ret = ceph_wait_for_latest_osdmap(monc->client, 0);
+
+out:
+	put_generic_request(req);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_monc_blacklist_add);
+
+/*
+ * Resend pending generic requests.
+ */
+static void __resend_generic_request(struct ceph_mon_client *monc)
+{
+	struct ceph_mon_generic_request *req;
+	struct rb_node *p;
+
+	for (p = rb_first(&monc->generic_request_tree); p; p = rb_next(p)) {
+		req = rb_entry(p, struct ceph_mon_generic_request, node);
+		ceph_msg_revoke(req->request);
+		ceph_msg_revoke_incoming(req->reply);
+		ceph_con_send(&monc->con, ceph_msg_get(req->request));
+	}
+}
+
+/*
+ * Delayed work.  If we haven't mounted yet, retry.  Otherwise,
+ * renew/retry subscription as needed (in case it is timing out, or we
+ * got an ENOMEM).  And keep the monitor connection alive.
+ */
+static void delayed_work(struct work_struct *work)
+{
+	struct ceph_mon_client *monc =
+		container_of(work, struct ceph_mon_client, delayed_work.work);
+
+	dout("monc delayed_work\n");
+	mutex_lock(&monc->mutex);
+	if (monc->hunting) {
+		dout("%s continuing hunt\n", __func__);
+		reopen_session(monc);
+	} else {
+		int is_auth = ceph_auth_is_authenticated(monc->auth);
+		if (ceph_con_keepalive_expired(&monc->con,
+					       CEPH_MONC_PING_TIMEOUT)) {
+			dout("monc keepalive timeout\n");
+			is_auth = 0;
+			reopen_session(monc);
+		}
+
+		if (!monc->hunting) {
+			ceph_con_keepalive(&monc->con);
+			__validate_auth(monc);
+			un_backoff(monc);
+		}
+
+		if (is_auth &&
+		    !(monc->con.peer_features & CEPH_FEATURE_MON_STATEFUL_SUB)) {
+			unsigned long now = jiffies;
+
+			dout("%s renew subs? now %lu renew after %lu\n",
+			     __func__, now, monc->sub_renew_after);
+			if (time_after_eq(now, monc->sub_renew_after))
+				__send_subscribe(monc);
+		}
+	}
+	__schedule_delayed(monc);
+	mutex_unlock(&monc->mutex);
+}
+
+/*
+ * On startup, we build a temporary monmap populated with the IPs
+ * provided by mount(2).
+ */
+static int build_initial_monmap(struct ceph_mon_client *monc)
+{
+	struct ceph_options *opt = monc->client->options;
+	struct ceph_entity_addr *mon_addr = opt->mon_addr;
+	int num_mon = opt->num_mon;
+	int i;
+
+	/* build initial monmap */
+	monc->monmap = kzalloc(struct_size(monc->monmap, mon_inst, num_mon),
+			       GFP_KERNEL);
+	if (!monc->monmap)
+		return -ENOMEM;
+	for (i = 0; i < num_mon; i++) {
+		monc->monmap->mon_inst[i].addr = mon_addr[i];
+		monc->monmap->mon_inst[i].addr.nonce = 0;
+		monc->monmap->mon_inst[i].name.type =
+			CEPH_ENTITY_TYPE_MON;
+		monc->monmap->mon_inst[i].name.num = cpu_to_le64(i);
+	}
+	monc->monmap->num_mon = num_mon;
+	return 0;
+}
+
+int ceph_monc_init(struct ceph_mon_client *monc, struct ceph_client *cl)
+{
+	int err = 0;
+
+	dout("init\n");
+	memset(monc, 0, sizeof(*monc));
+	monc->client = cl;
+	monc->monmap = NULL;
+	mutex_init(&monc->mutex);
+
+	err = build_initial_monmap(monc);
+	if (err)
+		goto out;
+
+	/* connection */
+	/* authentication */
+	monc->auth = ceph_auth_init(cl->options->name,
+				    cl->options->key);
+	if (IS_ERR(monc->auth)) {
+		err = PTR_ERR(monc->auth);
+		goto out_monmap;
+	}
+	monc->auth->want_keys =
+		CEPH_ENTITY_TYPE_AUTH | CEPH_ENTITY_TYPE_MON |
+		CEPH_ENTITY_TYPE_OSD | CEPH_ENTITY_TYPE_MDS;
+
+	/* msgs */
+	err = -ENOMEM;
+	monc->m_subscribe_ack = ceph_msg_new(CEPH_MSG_MON_SUBSCRIBE_ACK,
+				     sizeof(struct ceph_mon_subscribe_ack),
+				     GFP_KERNEL, true);
+	if (!monc->m_subscribe_ack)
+		goto out_auth;
+
+	monc->m_subscribe = ceph_msg_new(CEPH_MSG_MON_SUBSCRIBE, 128,
+					 GFP_KERNEL, true);
+	if (!monc->m_subscribe)
+		goto out_subscribe_ack;
+
+	monc->m_auth_reply = ceph_msg_new(CEPH_MSG_AUTH_REPLY, 4096,
+					  GFP_KERNEL, true);
+	if (!monc->m_auth_reply)
+		goto out_subscribe;
+
+	monc->m_auth = ceph_msg_new(CEPH_MSG_AUTH, 4096, GFP_KERNEL, true);
+	monc->pending_auth = 0;
+	if (!monc->m_auth)
+		goto out_auth_reply;
+
+	ceph_con_init(&monc->con, monc, &mon_con_ops,
+		      &monc->client->msgr);
+
+	monc->cur_mon = -1;
+	monc->had_a_connection = false;
+	monc->hunt_mult = 1;
+
+	INIT_DELAYED_WORK(&monc->delayed_work, delayed_work);
+	monc->generic_request_tree = RB_ROOT;
+	monc->last_tid = 0;
+
+	monc->fs_cluster_id = CEPH_FS_CLUSTER_ID_NONE;
+
+	return 0;
+
+out_auth_reply:
+	ceph_msg_put(monc->m_auth_reply);
+out_subscribe:
+	ceph_msg_put(monc->m_subscribe);
+out_subscribe_ack:
+	ceph_msg_put(monc->m_subscribe_ack);
+out_auth:
+	ceph_auth_destroy(monc->auth);
+out_monmap:
+	kfree(monc->monmap);
+out:
+	return err;
+}
+EXPORT_SYMBOL(ceph_monc_init);
+
+void ceph_monc_stop(struct ceph_mon_client *monc)
+{
+	dout("stop\n");
+	cancel_delayed_work_sync(&monc->delayed_work);
+
+	mutex_lock(&monc->mutex);
+	__close_session(monc);
+	monc->cur_mon = -1;
+	mutex_unlock(&monc->mutex);
+
+	/*
+	 * flush msgr queue before we destroy ourselves to ensure that:
+	 *  - any work that references our embedded con is finished.
+	 *  - any osd_client or other work that may reference an authorizer
+	 *    finishes before we shut down the auth subsystem.
+	 */
+	ceph_msgr_flush();
+
+	ceph_auth_destroy(monc->auth);
+
+	WARN_ON(!RB_EMPTY_ROOT(&monc->generic_request_tree));
+
+	ceph_msg_put(monc->m_auth);
+	ceph_msg_put(monc->m_auth_reply);
+	ceph_msg_put(monc->m_subscribe);
+	ceph_msg_put(monc->m_subscribe_ack);
+
+	kfree(monc->monmap);
+}
+EXPORT_SYMBOL(ceph_monc_stop);
+
+static void finish_hunting(struct ceph_mon_client *monc)
+{
+	if (monc->hunting) {
+		dout("%s found mon%d\n", __func__, monc->cur_mon);
+		monc->hunting = false;
+		monc->had_a_connection = true;
+		un_backoff(monc);
+		__schedule_delayed(monc);
+	}
+}
+
+static void handle_auth_reply(struct ceph_mon_client *monc,
+			      struct ceph_msg *msg)
+{
+	int ret;
+	int was_auth = 0;
+
+	mutex_lock(&monc->mutex);
+	was_auth = ceph_auth_is_authenticated(monc->auth);
+	monc->pending_auth = 0;
+	ret = ceph_handle_auth_reply(monc->auth, msg->front.iov_base,
+				     msg->front.iov_len,
+				     monc->m_auth->front.iov_base,
+				     monc->m_auth->front_alloc_len);
+	if (ret > 0) {
+		__send_prepared_auth_request(monc, ret);
+		goto out;
+	}
+
+	finish_hunting(monc);
+
+	if (ret < 0) {
+		monc->client->auth_err = ret;
+	} else if (!was_auth && ceph_auth_is_authenticated(monc->auth)) {
+		dout("authenticated, starting session\n");
+
+		monc->client->msgr.inst.name.type = CEPH_ENTITY_TYPE_CLIENT;
+		monc->client->msgr.inst.name.num =
+					cpu_to_le64(monc->auth->global_id);
+
+		__send_subscribe(monc);
+		__resend_generic_request(monc);
+
+		pr_info("mon%d %s session established\n", monc->cur_mon,
+			ceph_pr_addr(&monc->con.peer_addr.in_addr));
+	}
+
+out:
+	mutex_unlock(&monc->mutex);
+	if (monc->client->auth_err < 0)
+		wake_up_all(&monc->client->auth_wq);
+}
+
+static int __validate_auth(struct ceph_mon_client *monc)
+{
+	int ret;
+
+	if (monc->pending_auth)
+		return 0;
+
+	ret = ceph_build_auth(monc->auth, monc->m_auth->front.iov_base,
+			      monc->m_auth->front_alloc_len);
+	if (ret <= 0)
+		return ret; /* either an error, or no need to authenticate */
+	__send_prepared_auth_request(monc, ret);
+	return 0;
+}
+
+int ceph_monc_validate_auth(struct ceph_mon_client *monc)
+{
+	int ret;
+
+	mutex_lock(&monc->mutex);
+	ret = __validate_auth(monc);
+	mutex_unlock(&monc->mutex);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_monc_validate_auth);
+
+/*
+ * handle incoming message
+ */
+static void dispatch(struct ceph_connection *con, struct ceph_msg *msg)
+{
+	struct ceph_mon_client *monc = con->private;
+	int type = le16_to_cpu(msg->hdr.type);
+
+	if (!monc)
+		return;
+
+	switch (type) {
+	case CEPH_MSG_AUTH_REPLY:
+		handle_auth_reply(monc, msg);
+		break;
+
+	case CEPH_MSG_MON_SUBSCRIBE_ACK:
+		handle_subscribe_ack(monc, msg);
+		break;
+
+	case CEPH_MSG_STATFS_REPLY:
+		handle_statfs_reply(monc, msg);
+		break;
+
+	case CEPH_MSG_MON_GET_VERSION_REPLY:
+		handle_get_version_reply(monc, msg);
+		break;
+
+	case CEPH_MSG_MON_COMMAND_ACK:
+		handle_command_ack(monc, msg);
+		break;
+
+	case CEPH_MSG_MON_MAP:
+		ceph_monc_handle_map(monc, msg);
+		break;
+
+	case CEPH_MSG_OSD_MAP:
+		ceph_osdc_handle_map(&monc->client->osdc, msg);
+		break;
+
+	default:
+		/* can the chained handler handle it? */
+		if (monc->client->extra_mon_dispatch &&
+		    monc->client->extra_mon_dispatch(monc->client, msg) == 0)
+			break;
+
+		pr_err("received unknown message type %d %s\n", type,
+		       ceph_msg_type_name(type));
+	}
+	ceph_msg_put(msg);
+}
+
+/*
+ * Allocate memory for incoming message
+ */
+static struct ceph_msg *mon_alloc_msg(struct ceph_connection *con,
+				      struct ceph_msg_header *hdr,
+				      int *skip)
+{
+	struct ceph_mon_client *monc = con->private;
+	int type = le16_to_cpu(hdr->type);
+	int front_len = le32_to_cpu(hdr->front_len);
+	struct ceph_msg *m = NULL;
+
+	*skip = 0;
+
+	switch (type) {
+	case CEPH_MSG_MON_SUBSCRIBE_ACK:
+		m = ceph_msg_get(monc->m_subscribe_ack);
+		break;
+	case CEPH_MSG_STATFS_REPLY:
+	case CEPH_MSG_MON_COMMAND_ACK:
+		return get_generic_reply(con, hdr, skip);
+	case CEPH_MSG_AUTH_REPLY:
+		m = ceph_msg_get(monc->m_auth_reply);
+		break;
+	case CEPH_MSG_MON_GET_VERSION_REPLY:
+		if (le64_to_cpu(hdr->tid) != 0)
+			return get_generic_reply(con, hdr, skip);
+
+		/*
+		 * Older OSDs don't set reply tid even if the orignal
+		 * request had a non-zero tid.  Work around this weirdness
+		 * by allocating a new message.
+		 */
+		/* fall through */
+	case CEPH_MSG_MON_MAP:
+	case CEPH_MSG_MDS_MAP:
+	case CEPH_MSG_OSD_MAP:
+	case CEPH_MSG_FS_MAP_USER:
+		m = ceph_msg_new(type, front_len, GFP_NOFS, false);
+		if (!m)
+			return NULL;	/* ENOMEM--return skip == 0 */
+		break;
+	}
+
+	if (!m) {
+		pr_info("alloc_msg unknown type %d\n", type);
+		*skip = 1;
+	} else if (front_len > m->front_alloc_len) {
+		pr_warn("mon_alloc_msg front %d > prealloc %d (%u#%llu)\n",
+			front_len, m->front_alloc_len,
+			(unsigned int)con->peer_name.type,
+			le64_to_cpu(con->peer_name.num));
+		ceph_msg_put(m);
+		m = ceph_msg_new(type, front_len, GFP_NOFS, false);
+	}
+
+	return m;
+}
+
+/*
+ * If the monitor connection resets, pick a new monitor and resubmit
+ * any pending requests.
+ */
+static void mon_fault(struct ceph_connection *con)
+{
+	struct ceph_mon_client *monc = con->private;
+
+	mutex_lock(&monc->mutex);
+	dout("%s mon%d\n", __func__, monc->cur_mon);
+	if (monc->cur_mon >= 0) {
+		if (!monc->hunting) {
+			dout("%s hunting for new mon\n", __func__);
+			reopen_session(monc);
+			__schedule_delayed(monc);
+		} else {
+			dout("%s already hunting\n", __func__);
+		}
+	}
+	mutex_unlock(&monc->mutex);
+}
+
+/*
+ * We can ignore refcounting on the connection struct, as all references
+ * will come from the messenger workqueue, which is drained prior to
+ * mon_client destruction.
+ */
+static struct ceph_connection *con_get(struct ceph_connection *con)
+{
+	return con;
+}
+
+static void con_put(struct ceph_connection *con)
+{
+}
+
+static const struct ceph_connection_operations mon_con_ops = {
+	.get = con_get,
+	.put = con_put,
+	.dispatch = dispatch,
+	.fault = mon_fault,
+	.alloc_msg = mon_alloc_msg,
+};