/* 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 <linux/ratelimit.h>

#include <linux/ceph/decode.h>

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

static bool metrics_disable_warned;

static inline u32 ceph_subvolume_entry_payload_len(void)
{
	return sizeof(struct ceph_subvolume_metric_entry_wire);
}

static inline u32 ceph_subvolume_entry_encoded_len(void)
{
	return CEPH_ENCODING_START_BLK_LEN +
		ceph_subvolume_entry_payload_len();
}

static inline u32 ceph_subvolume_outer_payload_len(u32 nr_subvols)
{
	/* count is encoded as le64 (size_t on wire) to match FUSE client */
	return sizeof(__le64) +
		nr_subvols * ceph_subvolume_entry_encoded_len();
}

static inline u32 ceph_subvolume_metric_data_len(u32 nr_subvols)
{
	return CEPH_ENCODING_START_BLK_LEN +
		ceph_subvolume_outer_payload_len(nr_subvols);
}

static inline u32 ceph_subvolume_clamp_u32(u64 val)
{
	return val > U32_MAX ? U32_MAX : (u32)val;
}

static void ceph_init_subvolume_wire_entry(
	struct ceph_subvolume_metric_entry_wire *dst,
	const struct ceph_subvol_metric_snapshot *src)
{
	dst->subvolume_id = cpu_to_le64(src->subvolume_id);
	dst->read_ops = cpu_to_le32(ceph_subvolume_clamp_u32(src->read_ops));
	dst->write_ops = cpu_to_le32(ceph_subvolume_clamp_u32(src->write_ops));
	dst->read_bytes = cpu_to_le64(src->read_bytes);
	dst->write_bytes = cpu_to_le64(src->write_bytes);
	dst->read_latency_us = cpu_to_le64(src->read_latency_us);
	dst->write_latency_us = cpu_to_le64(src->write_latency_us);
	dst->time_stamp = 0;
}

static int ceph_encode_subvolume_metrics(void **p, void *end,
					 struct ceph_subvol_metric_snapshot *subvols,
					 u32 nr_subvols)
{
	u32 i;

	ceph_start_encoding(p, 1, 1,
			    ceph_subvolume_outer_payload_len(nr_subvols));
	/* count is encoded as le64 (size_t on wire) to match FUSE client */
	ceph_encode_64_safe(p, end, (u64)nr_subvols, enc_err);

	for (i = 0; i < nr_subvols; i++) {
		struct ceph_subvolume_metric_entry_wire wire_entry;

		ceph_init_subvolume_wire_entry(&wire_entry, &subvols[i]);
		ceph_start_encoding(p, 1, 1,
				    ceph_subvolume_entry_payload_len());
		ceph_encode_copy_safe(p, end, &wire_entry,
				      sizeof(wire_entry), enc_err);
	}

	return 0;
enc_err:
	return -ERANGE;
}

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;
	struct ceph_subvol_metric_snapshot *subvols = NULL;
	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;
	u32 nr_subvols = 0;
	size_t subvol_len = 0;
	void *cursor;
	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);

	if (ceph_subvolume_metrics_enabled(&mdsc->subvol_metrics) &&
	    test_bit(CEPHFS_FEATURE_SUBVOLUME_METRICS, &s->s_features)) {
		int ret;

		ret = ceph_subvolume_metrics_snapshot(&mdsc->subvol_metrics,
						      &subvols, &nr_subvols,
						      true);
		if (ret) {
			pr_warn_client(cl, "failed to snapshot subvolume metrics: %d\n",
				       ret);
			/*
			 * On error, ceph_subvolume_metrics_snapshot() guarantees
			 * *out = NULL and *nr = 0 at function entry, so subvols
			 * is already NULL here - no cleanup needed.
			 */
			nr_subvols = 0;
			subvols = NULL;
		}
	}

	if (nr_subvols) {
		/* type (le32) + ENCODE_START payload - no metric header */
		subvol_len = sizeof(__le32) +
			     ceph_subvolume_metric_data_len(nr_subvols);
	}

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

	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);
		kfree(subvols);
		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++;

	cursor = wsize + 1;

	if (nr_subvols) {
		void *payload;
		void *payload_end;
		int ret;

		/* Emit only the type (le32), no ver/compat/data_len */
		ceph_encode_32(&cursor, CLIENT_METRIC_TYPE_SUBVOLUME_METRICS);
		items++;

		payload = cursor;
		payload_end = (char *)payload +
			      ceph_subvolume_metric_data_len(nr_subvols);

		ret = ceph_encode_subvolume_metrics(&payload, payload_end,
						    subvols, nr_subvols);
		if (ret) {
			pr_warn_client(cl,
				       "failed to encode subvolume metrics\n");
			kfree(subvols);
			ceph_msg_put(msg);
			return false;
		}

		WARN_ON(payload != payload_end);
		cursor = payload;
	}

	put_unaligned_le32(items, &head->num);
	msg->front.iov_len = (char *)cursor - (char *)head;
	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);

	if (nr_subvols) {
		mutex_lock(&mdsc->subvol_metrics_last_mutex);
		kfree(mdsc->subvol_metrics_last);
		mdsc->subvol_metrics_last = subvols;
		mdsc->subvol_metrics_last_nr = nr_subvols;
		mdsc->subvol_metrics_sent += nr_subvols;
		mdsc->subvol_metrics_nonzero_sends++;
		mutex_unlock(&mdsc->subvol_metrics_last_mutex);

		subvols = NULL;
	}
	kfree(subvols);

	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.
		 *
		 * Also skip sessions that don't support SUBVOLUME_METRICS
		 * when subvolume metrics collection is enabled. This ensures
		 * we only send subvolume metrics to MDSs that understand them.
		 * If no session supports the feature, metrics won't be sent.
		 */
		if (check_session_state(s) &&
		    test_bit(CEPHFS_FEATURE_METRIC_COLLECT, &s->s_features)) {
			if (ceph_subvolume_metrics_enabled(&mdsc->subvol_metrics) &&
			    !test_bit(CEPHFS_FEATURE_SUBVOLUME_METRICS,
				      &s->s_features)) {
				ceph_put_mds_session(s);
				continue;
			}
			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)
		return;

	if (disable_send_metrics) {
		if (!metrics_disable_warned) {
			pr_info("ceph: metrics sending disabled via module parameter\n");
			metrics_disable_warned = true;
		}
		return;
	}
	metrics_disable_warned = false;

	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);
	else
		pr_warn_ratelimited("ceph: metrics worker has no MDS session\n");

	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);
}