ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 533 insertions, 0 deletions

diff --git a/fs/ceph/metric.c b/fs/ceph/metric.c
new file mode 100644
index 000000000..b6450fdac
--- /dev/null
+++ b/fs/ceph/metric.c
@@ -0,0 +1,533 @@
+/* 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);
+}