ceph: monitor client

#include "ceph_debug.h"

#include <linux/types.h>

#include <linux/random.h>

#include <linux/sched.h>

#include "mon_client.h"

#include "super.h"

#include "decode.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.

 */

const static struct ceph_connection_operations mon_con_ops;

/*

 * 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;

	u16 version;

	dout("monmap_decode %p %p len %d\n", p, end, (int)(end-p));

	ceph_decode_16_safe(&p, end, version, bad);

	ceph_decode_need(&p, end, sizeof(fsid) + 2*sizeof(u32), bad);

	ceph_decode_copy(&p, &fsid, sizeof(fsid));

	ceph_decode_32(&p, epoch);

	ceph_decode_32(&p, num_mon);

	ceph_decode_need(&p, end, num_mon*sizeof(m->mon_inst[0]), bad);

	if (num_mon >= CEPH_MAX_MON)

		goto bad;

	m = kmalloc(sizeof(*m) + sizeof(m->mon_inst[0])*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]));

	if (p != end)

		goto bad;

	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,

		     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 (ceph_entity_addr_equal(addr, &m->mon_inst[i].addr))

			return 1;

	return 0;

}

/*

 * Close monitor session, if any.

 */

static void __close_session(struct ceph_mon_client *monc)

{

	if (monc->con) {

		dout("__close_session closing mon%d\n", monc->cur_mon);

		ceph_con_close(monc->con);

		monc->cur_mon = -1;

	}

}

/*

 * Open a session with a (new) monitor.

 */

static int __open_session(struct ceph_mon_client *monc)

{

	char r;

	if (monc->cur_mon < 0) {

		get_random_bytes(&r, 1);

		monc->cur_mon = r % monc->monmap->num_mon;

		dout("open_session num=%d r=%d -> mon%d\n",

		     monc->monmap->num_mon, r, monc->cur_mon);

		monc->sub_sent = 0;

		monc->sub_renew_after = jiffies;  /* i.e., expired */

		monc->want_next_osdmap = !!monc->want_next_osdmap;

		dout("open_session mon%d opening\n", monc->cur_mon);

		monc->con->peer_name.type = CEPH_ENTITY_TYPE_MON;

		monc->con->peer_name.num = cpu_to_le64(monc->cur_mon);

		ceph_con_open(monc->con,

			      &monc->monmap->mon_inst[monc->cur_mon].addr);

	} else {

		dout("open_session mon%d already open\n", monc->cur_mon);

	}

	return 0;

}

static bool __sub_expired(struct ceph_mon_client *monc)

{

	return time_after_eq(jiffies, monc->sub_renew_after);

}

/*

 * Reschedule delayed work timer.

 */

static void __schedule_delayed(struct ceph_mon_client *monc)

{

	unsigned delay;

	if (monc->cur_mon < 0 || monc->want_mount || __sub_expired(monc))

		delay = 10 * HZ;

	else

		delay = 20 * HZ;

	dout("__schedule_delayed after %u\n", delay);

	schedule_delayed_work(&monc->delayed_work, delay);

}

/*

 * Send subscribe request for mdsmap and/or osdmap.

 */

static void __send_subscribe(struct ceph_mon_client *monc)

{

	dout("__send_subscribe sub_sent=%u exp=%u want_osd=%d\n",

	     (unsigned)monc->sub_sent, __sub_expired(monc),

	     monc->want_next_osdmap);

	if ((__sub_expired(monc) && !monc->sub_sent) ||

	    monc->want_next_osdmap == 1) {

		struct ceph_msg *msg;

		struct ceph_mon_subscribe_item *i;

		void *p, *end;

		msg = ceph_msg_new(CEPH_MSG_MON_SUBSCRIBE, 64, 0, 0, NULL);

		if (!msg)

			return;

		p = msg->front.iov_base;

		end = p + msg->front.iov_len;

		dout("__send_subscribe to 'mdsmap' %u+\n",

		     (unsigned)monc->have_mdsmap);

		if (monc->want_next_osdmap) {

			dout("__send_subscribe to 'osdmap' %u\n",

			     (unsigned)monc->have_osdmap);

			ceph_encode_32(&p, 2);

			ceph_encode_string(&p, end, "osdmap", 6);

			i = p;

			i->have = cpu_to_le64(monc->have_osdmap);

			i->onetime = 1;

			p += sizeof(*i);

			monc->want_next_osdmap = 2;  /* requested */

		} else {

			ceph_encode_32(&p, 1);

		}

		ceph_encode_string(&p, end, "mdsmap", 6);

		i = p;

		i->have = cpu_to_le64(monc->have_mdsmap);

		i->onetime = 0;

		p += sizeof(*i);

		msg->front.iov_len = p - msg->front.iov_base;

		msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);

		ceph_con_send(monc->con, msg);

		monc->sub_sent = jiffies | 1;  /* never 0 */

	}

}

static void handle_subscribe_ack(struct ceph_mon_client *monc,

				 struct ceph_msg *msg)

{

	unsigned seconds;

	void *p = msg->front.iov_base;

	void *end = p + msg->front.iov_len;

	ceph_decode_32_safe(&p, end, seconds, bad);

	mutex_lock(&monc->mutex);

	if (monc->hunting) {

		pr_info("mon%d %s session established\n",

			monc->cur_mon, pr_addr(&monc->con->peer_addr.in_addr));

		monc->hunting = false;

	}

	dout("handle_subscribe_ack after %d seconds\n", seconds);

	monc->sub_renew_after = monc->sub_sent + seconds*HZ - 1;

	monc->sub_sent = 0;

	mutex_unlock(&monc->mutex);

	return;

bad:

	pr_err("got corrupt subscribe-ack msg\n");

}

/*

 * Keep track of which maps we have

 */

int ceph_monc_got_mdsmap(struct ceph_mon_client *monc, u32 got)

{

	mutex_lock(&monc->mutex);

	monc->have_mdsmap = got;

	mutex_unlock(&monc->mutex);

	return 0;

}

int ceph_monc_got_osdmap(struct ceph_mon_client *monc, u32 got)

{

	mutex_lock(&monc->mutex);

	monc->have_osdmap = got;

	monc->want_next_osdmap = 0;

	mutex_unlock(&monc->mutex);

	return 0;

}

/*

 * Register interest in the next osdmap

 */

void ceph_monc_request_next_osdmap(struct ceph_mon_client *monc)

{

	dout("request_next_osdmap have %u\n", monc->have_osdmap);

	mutex_lock(&monc->mutex);

	if (!monc->want_next_osdmap)

		monc->want_next_osdmap = 1;

	if (monc->want_next_osdmap < 2)

		__send_subscribe(monc);

	mutex_unlock(&monc->mutex);

}

/*

 * mount

 */

static void __request_mount(struct ceph_mon_client *monc)

{

	struct ceph_msg *msg;

	struct ceph_client_mount *h;

	int err;

	dout("__request_mount\n");

	err = __open_session(monc);

	if (err)

		return;

	msg = ceph_msg_new(CEPH_MSG_CLIENT_MOUNT, sizeof(*h), 0, 0, NULL);

	if (IS_ERR(msg))

		return;

	h = msg->front.iov_base;

	h->have_version = 0;

	ceph_con_send(monc->con, msg);

}

int ceph_monc_request_mount(struct ceph_mon_client *monc)

{

	if (!monc->con) {

		monc->con = kmalloc(sizeof(*monc->con), GFP_KERNEL);

		if (!monc->con)

			return -ENOMEM;

		ceph_con_init(monc->client->msgr, monc->con);

		monc->con->private = monc;

		monc->con->ops = &mon_con_ops;

	}

	mutex_lock(&monc->mutex);

	__request_mount(monc);

	__schedule_delayed(monc);

	mutex_unlock(&monc->mutex);

	return 0;

}

/*

 * The monitor responds with mount ack indicate mount success.  The

 * included client ticket allows the client to talk to MDSs and OSDs.

 */

static void handle_mount_ack(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;

	s32 result;

	u32 len;

	s64 cnum;

	int err = -EINVAL;

	if (client->whoami >= 0) {

		dout("handle_mount_ack - already mounted\n");

		return;

	}

	mutex_lock(&monc->mutex);

	dout("handle_mount_ack\n");

	p = msg->front.iov_base;

	end = p + msg->front.iov_len;

	ceph_decode_64_safe(&p, end, cnum, bad);

	ceph_decode_32_safe(&p, end, result, bad);

	ceph_decode_32_safe(&p, end, len, bad);

	if (result) {

		pr_err("mount denied: %.*s (%d)\n", len, (char *)p,

		       result);

		err = result;

		goto out;

	}

	p += len;

	ceph_decode_32_safe(&p, end, len, bad);

	ceph_decode_need(&p, end, len, bad);

	monmap = ceph_monmap_decode(p, p + len);

	if (IS_ERR(monmap)) {

		pr_err("problem decoding monmap, %d\n",

		       (int)PTR_ERR(monmap));

		err = -EINVAL;

		goto out;

	}

	p += len;

	client->monc.monmap = monmap;

	kfree(old);

	client->signed_ticket = NULL;

	client->signed_ticket_len = 0;

	monc->want_mount = false;

	client->whoami = cnum;

	client->msgr->inst.name.type = CEPH_ENTITY_TYPE_CLIENT;

	client->msgr->inst.name.num = cpu_to_le64(cnum);

	pr_info("client%lld fsid " FSID_FORMAT "\n",

		client->whoami, PR_FSID(&client->monc.monmap->fsid));

	ceph_debugfs_client_init(client);

	__send_subscribe(monc);

	err = 0;

	goto out;

bad:

	pr_err("error decoding mount_ack message\n");

out:

	client->mount_err = err;

	mutex_unlock(&monc->mutex);

	wake_up(&client->mount_wq);

}

/*

 * statfs

 */

static void handle_statfs_reply(struct ceph_mon_client *monc,

				struct ceph_msg *msg)

{

	struct ceph_mon_statfs_request *req;

	struct ceph_mon_statfs_reply *reply = msg->front.iov_base;

	u64 tid;

	if (msg->front.iov_len != sizeof(*reply))

		goto bad;

	tid = le64_to_cpu(reply->tid);

	dout("handle_statfs_reply %p tid %llu\n", msg, tid);

	mutex_lock(&monc->mutex);

	req = radix_tree_lookup(&monc->statfs_request_tree, tid);

	if (req) {

		*req->buf = reply->st;

		req->result = 0;

	}

	mutex_unlock(&monc->mutex);

	if (req)

		complete(&req->completion);

	return;

bad:

	pr_err("corrupt statfs reply, no tid\n");

}

/*

 * (re)send a statfs request

 */

static int send_statfs(struct ceph_mon_client *monc,

		       struct ceph_mon_statfs_request *req)

{

	struct ceph_msg *msg;

	struct ceph_mon_statfs *h;

	int err;

	dout("send_statfs tid %llu\n", req->tid);

	err = __open_session(monc);

	if (err)

		return err;

	msg = ceph_msg_new(CEPH_MSG_STATFS, sizeof(*h), 0, 0, NULL);

	if (IS_ERR(msg))

		return PTR_ERR(msg);

	req->request = msg;

	h = msg->front.iov_base;

	h->have_version = 0;

	h->fsid = monc->monmap->fsid;

	h->tid = cpu_to_le64(req->tid);

	ceph_con_send(monc->con, msg);

	return 0;

}

/*

 * Do a synchronous statfs().

 */

int ceph_monc_do_statfs(struct ceph_mon_client *monc, struct ceph_statfs *buf)

{

	struct ceph_mon_statfs_request req;

	int err;

	req.buf = buf;

	init_completion(&req.completion);

	/* allocate memory for reply */

	err = ceph_msgpool_resv(&monc->msgpool_statfs_reply, 1);

	if (err)

		return err;

	/* register request */

	mutex_lock(&monc->mutex);

	req.tid = ++monc->last_tid;

	req.last_attempt = jiffies;

	req.delay = BASE_DELAY_INTERVAL;

	if (radix_tree_insert(&monc->statfs_request_tree, req.tid, &req) < 0) {

		mutex_unlock(&monc->mutex);

		pr_err("ENOMEM in do_statfs\n");

		return -ENOMEM;

	}

	monc->num_statfs_requests++;

	mutex_unlock(&monc->mutex);

	/* send request and wait */

	err = send_statfs(monc, &req);

	if (!err)

		err = wait_for_completion_interruptible(&req.completion);

	mutex_lock(&monc->mutex);

	radix_tree_delete(&monc->statfs_request_tree, req.tid);

	monc->num_statfs_requests--;

	ceph_msgpool_resv(&monc->msgpool_statfs_reply, -1);

	mutex_unlock(&monc->mutex);

	if (!err)

		err = req.result;

	return err;

}

/*

 * Resend pending statfs requests.

 */

static void __resend_statfs(struct ceph_mon_client *monc)

{

	u64 next_tid = 0;

	int got;

	int did = 0;

	struct ceph_mon_statfs_request *req;

	while (1) {

		got = radix_tree_gang_lookup(&monc->statfs_request_tree,

					     (void **)&req,

					     next_tid, 1);

		if (got == 0)

			break;

		did++;

		next_tid = req->tid + 1;

		send_statfs(monc, req);

	}

}

/*

 * 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->want_mount) {

		__request_mount(monc);

	} else {

		if (__sub_expired(monc)) {

			__close_session(monc);

			__open_session(monc);  /* continue hunting */

		} else {

			ceph_con_keepalive(monc->con);

		}

	}

	__send_subscribe(monc);

	__schedule_delayed(monc);

	mutex_unlock(&monc->mutex);

}

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);

	monc->con = NULL;

	/* msg pools */

	err = ceph_msgpool_init(&monc->msgpool_mount_ack, 4096, 1, false);

	if (err < 0)

		goto out;

	err = ceph_msgpool_init(&monc->msgpool_subscribe_ack, 8, 1, false);

	if (err < 0)

		goto out;

	err = ceph_msgpool_init(&monc->msgpool_statfs_reply,

				sizeof(struct ceph_mon_statfs_reply), 0, false);

	if (err < 0)

		goto out;

	monc->cur_mon = -1;

	monc->hunting = false;  /* not really */

	monc->sub_renew_after = jiffies;

	monc->sub_sent = 0;

	INIT_DELAYED_WORK(&monc->delayed_work, delayed_work);

	INIT_RADIX_TREE(&monc->statfs_request_tree, GFP_NOFS);

	monc->num_statfs_requests = 0;

	monc->last_tid = 0;

	monc->have_mdsmap = 0;

	monc->have_osdmap = 0;

	monc->want_next_osdmap = 1;

	monc->want_mount = true;

out:

	return err;

}

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);

	if (monc->con) {

		monc->con->private = NULL;

		monc->con->ops->put(monc->con);

		monc->con = NULL;

	}

	mutex_unlock(&monc->mutex);

	ceph_msgpool_destroy(&monc->msgpool_mount_ack);

	ceph_msgpool_destroy(&monc->msgpool_subscribe_ack);

	ceph_msgpool_destroy(&monc->msgpool_statfs_reply);

	kfree(monc->monmap);

}

/*

 * 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_CLIENT_MOUNT_ACK:

		handle_mount_ack(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_MDS_MAP:

		ceph_mdsc_handle_map(&monc->client->mdsc, msg);

		break;

	case CEPH_MSG_OSD_MAP:

		ceph_osdc_handle_map(&monc->client->osdc, msg);

		break;

	default:

		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)

{

	struct ceph_mon_client *monc = con->private;

	int type = le16_to_cpu(hdr->type);

	switch (type) {

	case CEPH_MSG_CLIENT_MOUNT_ACK:

		return ceph_msgpool_get(&monc->msgpool_mount_ack);

	case CEPH_MSG_MON_SUBSCRIBE_ACK:

		return ceph_msgpool_get(&monc->msgpool_subscribe_ack);

	case CEPH_MSG_STATFS_REPLY:

		return ceph_msgpool_get(&monc->msgpool_statfs_reply);

	}

	return ceph_alloc_msg(con, hdr);

}

/*

 * 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;

	if (!monc)

		return;

	dout("mon_fault\n");

	mutex_lock(&monc->mutex);

	if (!con->private)

		goto out;

	if (monc->con && !monc->hunting)

		pr_info("mon%d %s session lost, "

			"hunting for new mon\n", monc->cur_mon,

			pr_addr(&monc->con->peer_addr.in_addr));

	__close_session(monc);

	if (!monc->hunting) {

		/* start hunting */

		monc->hunting = true;

		if (__open_session(monc) == 0) {

			__send_subscribe(monc);