fs/ceph/metric.c - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 #include <linux/ceph/ceph_debug.h>

 #include <linux/types.h>
 #include <linux/percpu_counter.h>
 #include <linux/math64.h>

 #include "metric.h"
 #include "mds_client.h"

 static void ktime_to_ceph_timespec(struct ceph_timespec *ts, ktime_t val)
 {
 	struct timespec64 t = ktime_to_timespec64(val);
 	ceph_encode_timespec64(ts, &t);
 }

 static bool ceph_mdsc_send_metrics(struct ceph_mds_client *mdsc,
 				   struct ceph_mds_session *s)
 {
 	struct ceph_metric_head *head;
 	struct ceph_metric_cap *cap;
 	struct ceph_metric_read_latency *read;
 	struct ceph_metric_write_latency *write;
 	struct ceph_metric_metadata_latency *meta;
 	struct ceph_metric_dlease *dlease;
 	struct ceph_opened_files *files;
 	struct ceph_pinned_icaps *icaps;
 	struct ceph_opened_inodes *inodes;
 	struct ceph_read_io_size *rsize;
 	struct ceph_write_io_size *wsize;
 	struct ceph_client_metric *m = &mdsc->metric;
 	u64 nr_caps = atomic64_read(&m->total_caps);
 	u32 header_len = sizeof(struct ceph_metric_header);
 	struct ceph_client *cl = mdsc->fsc->client;
 	struct ceph_msg *msg;
 	s64 sum;
 	s32 items = 0;
 	s32 len;

 	/* Do not send the metrics until the MDS rank is ready */
 	mutex_lock(&mdsc->mutex);
 	if (ceph_mdsmap_get_state(mdsc->mdsmap, s->s_mds) != CEPH_MDS_STATE_ACTIVE) {
 		mutex_unlock(&mdsc->mutex);
 		return false;
 	}
 	mutex_unlock(&mdsc->mutex);

 	len = sizeof(*head) + sizeof(*cap) + sizeof(*read) + sizeof(*write)
 	      + sizeof(*meta) + sizeof(*dlease) + sizeof(*files)
 	      + sizeof(*icaps) + sizeof(*inodes) + sizeof(*rsize)
 	      + sizeof(*wsize);

 	msg = ceph_msg_new(CEPH_MSG_CLIENT_METRICS, len, GFP_NOFS, true);
 	if (!msg) {
 		pr_err_client(cl, "to mds%d, failed to allocate message\n",
 			      s->s_mds);
 		return false;
 	}

 	head = msg->front.iov_base;

 	/* encode the cap metric */
 	cap = (struct ceph_metric_cap *)(head + 1);
 	cap->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_CAP_INFO);
 	cap->header.ver = 1;
 	cap->header.compat = 1;
 	cap->header.data_len = cpu_to_le32(sizeof(*cap) - header_len);
 	cap->hit = cpu_to_le64(percpu_counter_sum(&m->i_caps_hit));
 	cap->mis = cpu_to_le64(percpu_counter_sum(&m->i_caps_mis));
 	cap->total = cpu_to_le64(nr_caps);
 	items++;

 	/* encode the read latency metric */
 	read = (struct ceph_metric_read_latency *)(cap + 1);
 	read->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_READ_LATENCY);
 	read->header.ver = 2;
 	read->header.compat = 1;
 	read->header.data_len = cpu_to_le32(sizeof(*read) - header_len);
 	sum = m->metric[METRIC_READ].latency_sum;
 	ktime_to_ceph_timespec(&read->lat, sum);
 	ktime_to_ceph_timespec(&read->avg, m->metric[METRIC_READ].latency_avg);
 	read->sq_sum = cpu_to_le64(m->metric[METRIC_READ].latency_sq_sum);
 	read->count = cpu_to_le64(m->metric[METRIC_READ].total);
 	items++;

 	/* encode the write latency metric */
 	write = (struct ceph_metric_write_latency *)(read + 1);
 	write->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_WRITE_LATENCY);
 	write->header.ver = 2;
 	write->header.compat = 1;
 	write->header.data_len = cpu_to_le32(sizeof(*write) - header_len);
 	sum = m->metric[METRIC_WRITE].latency_sum;
 	ktime_to_ceph_timespec(&write->lat, sum);
 	ktime_to_ceph_timespec(&write->avg, m->metric[METRIC_WRITE].latency_avg);
 	write->sq_sum = cpu_to_le64(m->metric[METRIC_WRITE].latency_sq_sum);
 	write->count = cpu_to_le64(m->metric[METRIC_WRITE].total);
 	items++;

 	/* encode the metadata latency metric */
 	meta = (struct ceph_metric_metadata_latency *)(write + 1);
 	meta->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_METADATA_LATENCY);
 	meta->header.ver = 2;
 	meta->header.compat = 1;
 	meta->header.data_len = cpu_to_le32(sizeof(*meta) - header_len);
 	sum = m->metric[METRIC_METADATA].latency_sum;
 	ktime_to_ceph_timespec(&meta->lat, sum);
 	ktime_to_ceph_timespec(&meta->avg, m->metric[METRIC_METADATA].latency_avg);
 	meta->sq_sum = cpu_to_le64(m->metric[METRIC_METADATA].latency_sq_sum);
 	meta->count = cpu_to_le64(m->metric[METRIC_METADATA].total);
 	items++;

 	/* encode the dentry lease metric */
 	dlease = (struct ceph_metric_dlease *)(meta + 1);
 	dlease->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_DENTRY_LEASE);
 	dlease->header.ver = 1;
 	dlease->header.compat = 1;
 	dlease->header.data_len = cpu_to_le32(sizeof(*dlease) - header_len);
 	dlease->hit = cpu_to_le64(percpu_counter_sum(&m->d_lease_hit));
 	dlease->mis = cpu_to_le64(percpu_counter_sum(&m->d_lease_mis));
 	dlease->total = cpu_to_le64(atomic64_read(&m->total_dentries));
 	items++;

 	sum = percpu_counter_sum(&m->total_inodes);

 	/* encode the opened files metric */
 	files = (struct ceph_opened_files *)(dlease + 1);
 	files->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_OPENED_FILES);
 	files->header.ver = 1;
 	files->header.compat = 1;
 	files->header.data_len = cpu_to_le32(sizeof(*files) - header_len);
 	files->opened_files = cpu_to_le64(atomic64_read(&m->opened_files));
 	files->total = cpu_to_le64(sum);
 	items++;

 	/* encode the pinned icaps metric */
 	icaps = (struct ceph_pinned_icaps *)(files + 1);
 	icaps->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_PINNED_ICAPS);
 	icaps->header.ver = 1;
 	icaps->header.compat = 1;
 	icaps->header.data_len = cpu_to_le32(sizeof(*icaps) - header_len);
 	icaps->pinned_icaps = cpu_to_le64(nr_caps);
 	icaps->total = cpu_to_le64(sum);
 	items++;

 	/* encode the opened inodes metric */
 	inodes = (struct ceph_opened_inodes *)(icaps + 1);
 	inodes->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_OPENED_INODES);
 	inodes->header.ver = 1;
 	inodes->header.compat = 1;
 	inodes->header.data_len = cpu_to_le32(sizeof(*inodes) - header_len);
 	inodes->opened_inodes = cpu_to_le64(percpu_counter_sum(&m->opened_inodes));
 	inodes->total = cpu_to_le64(sum);
 	items++;

 	/* encode the read io size metric */
 	rsize = (struct ceph_read_io_size *)(inodes + 1);
 	rsize->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_READ_IO_SIZES);
 	rsize->header.ver = 1;
 	rsize->header.compat = 1;
 	rsize->header.data_len = cpu_to_le32(sizeof(*rsize) - header_len);
 	rsize->total_ops = cpu_to_le64(m->metric[METRIC_READ].total);
 	rsize->total_size = cpu_to_le64(m->metric[METRIC_READ].size_sum);
 	items++;

 	/* encode the write io size metric */
 	wsize = (struct ceph_write_io_size *)(rsize + 1);
 	wsize->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_WRITE_IO_SIZES);
 	wsize->header.ver = 1;
 	wsize->header.compat = 1;
 	wsize->header.data_len = cpu_to_le32(sizeof(*wsize) - header_len);
 	wsize->total_ops = cpu_to_le64(m->metric[METRIC_WRITE].total);
 	wsize->total_size = cpu_to_le64(m->metric[METRIC_WRITE].size_sum);
 	items++;

 	put_unaligned_le32(items, &head->num);
 	msg->front.iov_len = len;
 	msg->hdr.version = cpu_to_le16(1);
 	msg->hdr.compat_version = cpu_to_le16(1);
 	msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
 	ceph_con_send(&s->s_con, msg);

 	return true;
 }


 static void metric_get_session(struct ceph_mds_client *mdsc)
 {
 	struct ceph_mds_session *s;
 	int i;

 	mutex_lock(&mdsc->mutex);
 	for (i = 0; i < mdsc->max_sessions; i++) {
 		s = __ceph_lookup_mds_session(mdsc, i);
 		if (!s)
 			continue;

 		/*
 		 * Skip it if MDS doesn't support the metric collection,
 		 * or the MDS will close the session's socket connection
 		 * directly when it get this message.
 		 */
 		if (check_session_state(s) &&
 		    test_bit(CEPHFS_FEATURE_METRIC_COLLECT, &s->s_features)) {
 			mdsc->metric.session = s;
 			break;
 		}

 		ceph_put_mds_session(s);
 	}
 	mutex_unlock(&mdsc->mutex);
 }

 static void metric_delayed_work(struct work_struct *work)
 {
 	struct ceph_client_metric *m =
 		container_of(work, struct ceph_client_metric, delayed_work.work);
 	struct ceph_mds_client *mdsc =
 		container_of(m, struct ceph_mds_client, metric);

 	if (mdsc->stopping || disable_send_metrics)
 		return;

 	if (!m->session || !check_session_state(m->session)) {
 		if (m->session) {
 			ceph_put_mds_session(m->session);
 			m->session = NULL;
 		}
 		metric_get_session(mdsc);
 	}
 	if (m->session) {
 		ceph_mdsc_send_metrics(mdsc, m->session);
 		metric_schedule_delayed(m);
 	}
 }

 int ceph_metric_init(struct ceph_client_metric *m)
 {
 	struct ceph_metric *metric;
 	int ret, i;

 	if (!m)
 		return -EINVAL;

 	atomic64_set(&m->total_dentries, 0);
 	ret = percpu_counter_init(&m->d_lease_hit, 0, GFP_KERNEL);
 	if (ret)
 		return ret;

 	ret = percpu_counter_init(&m->d_lease_mis, 0, GFP_KERNEL);
 	if (ret)
 		goto err_d_lease_mis;

 	atomic64_set(&m->total_caps, 0);
 	ret = percpu_counter_init(&m->i_caps_hit, 0, GFP_KERNEL);
 	if (ret)
 		goto err_i_caps_hit;

 	ret = percpu_counter_init(&m->i_caps_mis, 0, GFP_KERNEL);
 	if (ret)
 		goto err_i_caps_mis;

 	for (i = 0; i < METRIC_MAX; i++) {
 		metric = &m->metric[i];
 		spin_lock_init(&metric->lock);
 		metric->size_sum = 0;
 		metric->size_min = U64_MAX;
 		metric->size_max = 0;
 		metric->total = 0;
 		metric->latency_sum = 0;
 		metric->latency_avg = 0;
 		metric->latency_sq_sum = 0;
 		metric->latency_min = KTIME_MAX;
 		metric->latency_max = 0;
 	}

 	atomic64_set(&m->opened_files, 0);
 	ret = percpu_counter_init(&m->opened_inodes, 0, GFP_KERNEL);
 	if (ret)
 		goto err_opened_inodes;
 	ret = percpu_counter_init(&m->total_inodes, 0, GFP_KERNEL);
 	if (ret)
 		goto err_total_inodes;

 	m->session = NULL;
 	INIT_DELAYED_WORK(&m->delayed_work, metric_delayed_work);

 	return 0;

 err_total_inodes:
 	percpu_counter_destroy(&m->opened_inodes);
 err_opened_inodes:
 	percpu_counter_destroy(&m->i_caps_mis);
 err_i_caps_mis:
 	percpu_counter_destroy(&m->i_caps_hit);
 err_i_caps_hit:
 	percpu_counter_destroy(&m->d_lease_mis);
 err_d_lease_mis:
 	percpu_counter_destroy(&m->d_lease_hit);

 	return ret;
 }

 void ceph_metric_destroy(struct ceph_client_metric *m)
 {
 	if (!m)
 		return;

 	cancel_delayed_work_sync(&m->delayed_work);

 	percpu_counter_destroy(&m->total_inodes);
 	percpu_counter_destroy(&m->opened_inodes);
 	percpu_counter_destroy(&m->i_caps_mis);
 	percpu_counter_destroy(&m->i_caps_hit);
 	percpu_counter_destroy(&m->d_lease_mis);
 	percpu_counter_destroy(&m->d_lease_hit);

 	ceph_put_mds_session(m->session);
 }

 #define METRIC_UPDATE_MIN_MAX(min, max, new)	\
 {						\
 	if (unlikely(new < min))		\
 		min = new;			\
 	if (unlikely(new > max))		\
 		max = new;			\
 }

 static inline void __update_mean_and_stdev(ktime_t total, ktime_t *lavg,
 					   ktime_t *sq_sump, ktime_t lat)
 {
 	ktime_t avg;

 	if (unlikely(total == 1)) {
 		*lavg = lat;
 	} else {
 		/* the sq is (lat - old_avg) * (lat - new_avg) */
 		avg = *lavg + div64_s64(lat - *lavg, total);
 		*sq_sump += (lat - *lavg)*(lat - avg);
 		*lavg = avg;
 	}
 }

 void ceph_update_metrics(struct ceph_metric *m,
 			 ktime_t r_start, ktime_t r_end,
 			 unsigned int size, int rc)
 {
 	ktime_t lat = ktime_sub(r_end, r_start);
 	ktime_t total;

 	if (unlikely(rc < 0 && rc != -ENOENT && rc != -ETIMEDOUT))
 		return;

 	spin_lock(&m->lock);
 	total = ++m->total;
 	m->size_sum += size;
 	METRIC_UPDATE_MIN_MAX(m->size_min, m->size_max, size);
 	m->latency_sum += lat;
 	METRIC_UPDATE_MIN_MAX(m->latency_min, m->latency_max, lat);
 	__update_mean_and_stdev(total, &m->latency_avg,	&m->latency_sq_sum,
 				lat);
 	spin_unlock(&m->lock);
 }
	/* SPDX-License-Identifier: GPL-2.0 */
	#include <linux/ceph/ceph_debug.h>

	#include <linux/types.h>
	#include <linux/percpu_counter.h>
	#include <linux/math64.h>

	#include "metric.h"
	#include "mds_client.h"

	static void ktime_to_ceph_timespec(struct ceph_timespec *ts, ktime_t val)
	{
	struct timespec64 t = ktime_to_timespec64(val);
	ceph_encode_timespec64(ts, &t);
	}

	static bool ceph_mdsc_send_metrics(struct ceph_mds_client *mdsc,
	struct ceph_mds_session *s)
	{
	struct ceph_metric_head *head;
	struct ceph_metric_cap *cap;
	struct ceph_metric_read_latency *read;
	struct ceph_metric_write_latency *write;
	struct ceph_metric_metadata_latency *meta;
	struct ceph_metric_dlease *dlease;
	struct ceph_opened_files *files;
	struct ceph_pinned_icaps *icaps;
	struct ceph_opened_inodes *inodes;
	struct ceph_read_io_size *rsize;
	struct ceph_write_io_size *wsize;
	struct ceph_client_metric *m = &mdsc->metric;
	u64 nr_caps = atomic64_read(&m->total_caps);
	u32 header_len = sizeof(struct ceph_metric_header);
	struct ceph_client *cl = mdsc->fsc->client;
	struct ceph_msg *msg;
	s64 sum;
	s32 items = 0;
	s32 len;

	/* Do not send the metrics until the MDS rank is ready */
	mutex_lock(&mdsc->mutex);
	if (ceph_mdsmap_get_state(mdsc->mdsmap, s->s_mds) != CEPH_MDS_STATE_ACTIVE) {
	mutex_unlock(&mdsc->mutex);
	return false;
	}
	mutex_unlock(&mdsc->mutex);

	len = sizeof(head) + sizeof(cap) + sizeof(read) + sizeof(write)
	+ sizeof(meta) + sizeof(dlease) + sizeof(*files)
	+ sizeof(icaps) + sizeof(inodes) + sizeof(*rsize)
	+ sizeof(*wsize);

	msg = ceph_msg_new(CEPH_MSG_CLIENT_METRICS, len, GFP_NOFS, true);
	if (!msg) {
	pr_err_client(cl, "to mds%d, failed to allocate message\n",
	s->s_mds);
	return false;
	}

	head = msg->front.iov_base;

	/* encode the cap metric */
	cap = (struct ceph_metric_cap *)(head + 1);
	cap->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_CAP_INFO);
	cap->header.ver = 1;
	cap->header.compat = 1;
	cap->header.data_len = cpu_to_le32(sizeof(*cap) - header_len);
	cap->hit = cpu_to_le64(percpu_counter_sum(&m->i_caps_hit));
	cap->mis = cpu_to_le64(percpu_counter_sum(&m->i_caps_mis));
	cap->total = cpu_to_le64(nr_caps);
	items++;

	/* encode the read latency metric */
	read = (struct ceph_metric_read_latency *)(cap + 1);
	read->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_READ_LATENCY);
	read->header.ver = 2;
	read->header.compat = 1;
	read->header.data_len = cpu_to_le32(sizeof(*read) - header_len);
	sum = m->metric[METRIC_READ].latency_sum;
	ktime_to_ceph_timespec(&read->lat, sum);
	ktime_to_ceph_timespec(&read->avg, m->metric[METRIC_READ].latency_avg);
	read->sq_sum = cpu_to_le64(m->metric[METRIC_READ].latency_sq_sum);
	read->count = cpu_to_le64(m->metric[METRIC_READ].total);
	items++;

	/* encode the write latency metric */
	write = (struct ceph_metric_write_latency *)(read + 1);
	write->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_WRITE_LATENCY);
	write->header.ver = 2;
	write->header.compat = 1;
	write->header.data_len = cpu_to_le32(sizeof(*write) - header_len);
	sum = m->metric[METRIC_WRITE].latency_sum;
	ktime_to_ceph_timespec(&write->lat, sum);
	ktime_to_ceph_timespec(&write->avg, m->metric[METRIC_WRITE].latency_avg);
	write->sq_sum = cpu_to_le64(m->metric[METRIC_WRITE].latency_sq_sum);
	write->count = cpu_to_le64(m->metric[METRIC_WRITE].total);
	items++;

	/* encode the metadata latency metric */
	meta = (struct ceph_metric_metadata_latency *)(write + 1);
	meta->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_METADATA_LATENCY);
	meta->header.ver = 2;
	meta->header.compat = 1;
	meta->header.data_len = cpu_to_le32(sizeof(*meta) - header_len);
	sum = m->metric[METRIC_METADATA].latency_sum;
	ktime_to_ceph_timespec(&meta->lat, sum);
	ktime_to_ceph_timespec(&meta->avg, m->metric[METRIC_METADATA].latency_avg);
	meta->sq_sum = cpu_to_le64(m->metric[METRIC_METADATA].latency_sq_sum);
	meta->count = cpu_to_le64(m->metric[METRIC_METADATA].total);
	items++;

	/* encode the dentry lease metric */
	dlease = (struct ceph_metric_dlease *)(meta + 1);
	dlease->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_DENTRY_LEASE);
	dlease->header.ver = 1;
	dlease->header.compat = 1;
	dlease->header.data_len = cpu_to_le32(sizeof(*dlease) - header_len);
	dlease->hit = cpu_to_le64(percpu_counter_sum(&m->d_lease_hit));
	dlease->mis = cpu_to_le64(percpu_counter_sum(&m->d_lease_mis));
	dlease->total = cpu_to_le64(atomic64_read(&m->total_dentries));
	items++;

	sum = percpu_counter_sum(&m->total_inodes);

	/* encode the opened files metric */
	files = (struct ceph_opened_files *)(dlease + 1);
	files->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_OPENED_FILES);
	files->header.ver = 1;
	files->header.compat = 1;
	files->header.data_len = cpu_to_le32(sizeof(*files) - header_len);
	files->opened_files = cpu_to_le64(atomic64_read(&m->opened_files));
	files->total = cpu_to_le64(sum);
	items++;

	/* encode the pinned icaps metric */
	icaps = (struct ceph_pinned_icaps *)(files + 1);
	icaps->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_PINNED_ICAPS);
	icaps->header.ver = 1;
	icaps->header.compat = 1;
	icaps->header.data_len = cpu_to_le32(sizeof(*icaps) - header_len);
	icaps->pinned_icaps = cpu_to_le64(nr_caps);
	icaps->total = cpu_to_le64(sum);
	items++;

	/* encode the opened inodes metric */
	inodes = (struct ceph_opened_inodes *)(icaps + 1);
	inodes->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_OPENED_INODES);
	inodes->header.ver = 1;
	inodes->header.compat = 1;
	inodes->header.data_len = cpu_to_le32(sizeof(*inodes) - header_len);
	inodes->opened_inodes = cpu_to_le64(percpu_counter_sum(&m->opened_inodes));
	inodes->total = cpu_to_le64(sum);
	items++;

	/* encode the read io size metric */
	rsize = (struct ceph_read_io_size *)(inodes + 1);
	rsize->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_READ_IO_SIZES);
	rsize->header.ver = 1;
	rsize->header.compat = 1;
	rsize->header.data_len = cpu_to_le32(sizeof(*rsize) - header_len);
	rsize->total_ops = cpu_to_le64(m->metric[METRIC_READ].total);
	rsize->total_size = cpu_to_le64(m->metric[METRIC_READ].size_sum);
	items++;

	/* encode the write io size metric */
	wsize = (struct ceph_write_io_size *)(rsize + 1);
	wsize->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_WRITE_IO_SIZES);
	wsize->header.ver = 1;
	wsize->header.compat = 1;
	wsize->header.data_len = cpu_to_le32(sizeof(*wsize) - header_len);
	wsize->total_ops = cpu_to_le64(m->metric[METRIC_WRITE].total);
	wsize->total_size = cpu_to_le64(m->metric[METRIC_WRITE].size_sum);
	items++;

	put_unaligned_le32(items, &head->num);
	msg->front.iov_len = len;
	msg->hdr.version = cpu_to_le16(1);
	msg->hdr.compat_version = cpu_to_le16(1);
	msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
	ceph_con_send(&s->s_con, msg);

	return true;
	}


	static void metric_get_session(struct ceph_mds_client *mdsc)
	{
	struct ceph_mds_session *s;
	int i;

	mutex_lock(&mdsc->mutex);
	for (i = 0; i < mdsc->max_sessions; i++) {
	s = __ceph_lookup_mds_session(mdsc, i);
	if (!s)
	continue;

	/*
	* Skip it if MDS doesn't support the metric collection,
	* or the MDS will close the session's socket connection
	* directly when it get this message.
	*/
	if (check_session_state(s) &&
	test_bit(CEPHFS_FEATURE_METRIC_COLLECT, &s->s_features)) {
	mdsc->metric.session = s;
	break;
	}

	ceph_put_mds_session(s);
	}
	mutex_unlock(&mdsc->mutex);
	}

	static void metric_delayed_work(struct work_struct *work)
	{
	struct ceph_client_metric *m =
	container_of(work, struct ceph_client_metric, delayed_work.work);
	struct ceph_mds_client *mdsc =
	container_of(m, struct ceph_mds_client, metric);

	if (mdsc->stopping \|\| disable_send_metrics)
	return;

	if (!m->session \|\| !check_session_state(m->session)) {
	if (m->session) {
	ceph_put_mds_session(m->session);
	m->session = NULL;
	}
	metric_get_session(mdsc);
	}
	if (m->session) {
	ceph_mdsc_send_metrics(mdsc, m->session);
	metric_schedule_delayed(m);
	}
	}

	int ceph_metric_init(struct ceph_client_metric *m)
	{
	struct ceph_metric *metric;
	int ret, i;

	if (!m)
	return -EINVAL;

	atomic64_set(&m->total_dentries, 0);
	ret = percpu_counter_init(&m->d_lease_hit, 0, GFP_KERNEL);
	if (ret)
	return ret;

	ret = percpu_counter_init(&m->d_lease_mis, 0, GFP_KERNEL);
	if (ret)
	goto err_d_lease_mis;

	atomic64_set(&m->total_caps, 0);
	ret = percpu_counter_init(&m->i_caps_hit, 0, GFP_KERNEL);
	if (ret)
	goto err_i_caps_hit;

	ret = percpu_counter_init(&m->i_caps_mis, 0, GFP_KERNEL);
	if (ret)
	goto err_i_caps_mis;

	for (i = 0; i < METRIC_MAX; i++) {
	metric = &m->metric[i];
	spin_lock_init(&metric->lock);
	metric->size_sum = 0;
	metric->size_min = U64_MAX;
	metric->size_max = 0;
	metric->total = 0;
	metric->latency_sum = 0;
	metric->latency_avg = 0;
	metric->latency_sq_sum = 0;
	metric->latency_min = KTIME_MAX;
	metric->latency_max = 0;
	}

	atomic64_set(&m->opened_files, 0);
	ret = percpu_counter_init(&m->opened_inodes, 0, GFP_KERNEL);
	if (ret)
	goto err_opened_inodes;
	ret = percpu_counter_init(&m->total_inodes, 0, GFP_KERNEL);
	if (ret)
	goto err_total_inodes;

	m->session = NULL;
	INIT_DELAYED_WORK(&m->delayed_work, metric_delayed_work);

	return 0;

	err_total_inodes:
	percpu_counter_destroy(&m->opened_inodes);
	err_opened_inodes:
	percpu_counter_destroy(&m->i_caps_mis);
	err_i_caps_mis:
	percpu_counter_destroy(&m->i_caps_hit);
	err_i_caps_hit:
	percpu_counter_destroy(&m->d_lease_mis);
	err_d_lease_mis:
	percpu_counter_destroy(&m->d_lease_hit);

	return ret;
	}

	void ceph_metric_destroy(struct ceph_client_metric *m)
	{
	if (!m)
	return;

	cancel_delayed_work_sync(&m->delayed_work);

	percpu_counter_destroy(&m->total_inodes);
	percpu_counter_destroy(&m->opened_inodes);
	percpu_counter_destroy(&m->i_caps_mis);
	percpu_counter_destroy(&m->i_caps_hit);
	percpu_counter_destroy(&m->d_lease_mis);
	percpu_counter_destroy(&m->d_lease_hit);

	ceph_put_mds_session(m->session);
	}

	#define METRIC_UPDATE_MIN_MAX(min, max, new) \
	{ \
	if (unlikely(new < min)) \
	min = new; \
	if (unlikely(new > max)) \
	max = new; \
	}

	static inline void __update_mean_and_stdev(ktime_t total, ktime_t *lavg,
	ktime_t *sq_sump, ktime_t lat)
	{
	ktime_t avg;

	if (unlikely(total == 1)) {
	*lavg = lat;
	} else {
	/* the sq is (lat - old_avg) * (lat - new_avg) */
	avg = lavg + div64_s64(lat - lavg, total);
	sq_sump += (lat - lavg)*(lat - avg);
	*lavg = avg;
	}
	}

	void ceph_update_metrics(struct ceph_metric *m,
	ktime_t r_start, ktime_t r_end,
	unsigned int size, int rc)
	{
	ktime_t lat = ktime_sub(r_end, r_start);
	ktime_t total;

	if (unlikely(rc < 0 && rc != -ENOENT && rc != -ETIMEDOUT))
	return;

	spin_lock(&m->lock);
	total = ++m->total;
	m->size_sum += size;
	METRIC_UPDATE_MIN_MAX(m->size_min, m->size_max, size);
	m->latency_sum += lat;
	METRIC_UPDATE_MIN_MAX(m->latency_min, m->latency_max, lat);
	__update_mean_and_stdev(total, &m->latency_avg, &m->latency_sq_sum,
	lat);
	spin_unlock(&m->lock);
	}