virtio_blk: set the zone write granularitygrafted

virtblk_read_zoned_limits() reads the write granularity that the device
reports in virtio_blk_zoned_characteristics and assigns it to the
physical block size and to io_min, but never to the limit that is named
after it. queue_limits.zone_write_granularity is left at zero, so
blk_validate_zoned_limits() raises it to the logical block size:

	if (lim->zone_write_granularity < lim->logical_block_size)
		lim->zone_write_granularity = lim->logical_block_size;

A device that reports a granularity coarser than its logical block size,
which is what the field exists to express, therefore has it silently
reduced. A 512e host managed disk passed through to a guest reports a
logical block size of 512 and a write granularity of 4096, and the guest
ends up with a zone write granularity of 512.

bio_split_alignment() returns lim->zone_write_granularity if it is non-zero
and bio_split_io_at() may split a bio with as per bio_split_alignment().
This can real to the write getting rejected by the host drive, as the write
is not aligned to the physical block size.

zonefs also takes its block size from bdev_zone_write_granularity(), so it
would incorrectly use 512 on a disk that requires 4096.

sd_zbc_read_zones() sets the limit from the physical block size for the
same reason. NVMe ZNS and null_blk leave it unset, but the fallback
gives the right answer for them, as their write granularity is the
logical block size. virtio carries a separate value that may exceed it.

Set the zone write granularity from the value that the device reports.

Fixes: 95bfec41bd3d ("virtio-blk: add support for zoned block devices")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://patch.msgid.link/20260918140641.2031075-2-cassel@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 745 insertions, 0 deletions

diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
new file mode 100644
index 000000000..18eb5da03
--- /dev/null
+++ b/fs/ceph/debugfs.c
@@ -0,0 +1,745 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/math64.h>
+#include <linux/ktime.h>
+#include <linux/uaccess.h>
+#include <linux/atomic.h>
+
+#include <linux/ceph/libceph.h>
+#include <linux/ceph/mon_client.h>
+#include <linux/ceph/auth.h>
+#include <linux/ceph/debugfs.h>
+#include <linux/ceph/decode.h>
+
+#include "super.h"
+
+#ifdef CONFIG_DEBUG_FS
+
+#include "mds_client.h"
+#include "metric.h"
+#include "subvolume_metrics.h"
+
+/**
+ * struct ceph_session_feature_desc - Maps feature bits to names for debugfs
+ * @bit: Feature bit number from enum ceph_feature_type (see mds_client.h)
+ * @name: Human-readable feature name for debugfs output
+ *
+ * Used by metric_features_show() to display negotiated session features.
+ */
+struct ceph_session_feature_desc {
+	unsigned int bit;
+	const char *name;
+};
+
+static const struct ceph_session_feature_desc ceph_session_feature_table[] = {
+	{ CEPHFS_FEATURE_METRIC_COLLECT, "METRIC_COLLECT" },
+	{ CEPHFS_FEATURE_REPLY_ENCODING, "REPLY_ENCODING" },
+	{ CEPHFS_FEATURE_RECLAIM_CLIENT, "RECLAIM_CLIENT" },
+	{ CEPHFS_FEATURE_LAZY_CAP_WANTED, "LAZY_CAP_WANTED" },
+	{ CEPHFS_FEATURE_MULTI_RECONNECT, "MULTI_RECONNECT" },
+	{ CEPHFS_FEATURE_DELEG_INO, "DELEG_INO" },
+	{ CEPHFS_FEATURE_ALTERNATE_NAME, "ALTERNATE_NAME" },
+	{ CEPHFS_FEATURE_NOTIFY_SESSION_STATE, "NOTIFY_SESSION_STATE" },
+	{ CEPHFS_FEATURE_OP_GETVXATTR, "OP_GETVXATTR" },
+	{ CEPHFS_FEATURE_32BITS_RETRY_FWD, "32BITS_RETRY_FWD" },
+	{ CEPHFS_FEATURE_NEW_SNAPREALM_INFO, "NEW_SNAPREALM_INFO" },
+	{ CEPHFS_FEATURE_HAS_OWNER_UIDGID, "HAS_OWNER_UIDGID" },
+	{ CEPHFS_FEATURE_MDS_AUTH_CAPS_CHECK, "MDS_AUTH_CAPS_CHECK" },
+	{ CEPHFS_FEATURE_SUBVOLUME_METRICS, "SUBVOLUME_METRICS" },
+};
+
+static int mdsmap_show(struct seq_file *s, void *p)
+{
+	int i;
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mdsmap *mdsmap;
+
+	if (!fsc->mdsc || !fsc->mdsc->mdsmap)
+		return 0;
+	mdsmap = fsc->mdsc->mdsmap;
+	seq_printf(s, "epoch %d\n", mdsmap->m_epoch);
+	seq_printf(s, "root %d\n", mdsmap->m_root);
+	seq_printf(s, "max_mds %d\n", mdsmap->m_max_mds);
+	seq_printf(s, "session_timeout %d\n", mdsmap->m_session_timeout);
+	seq_printf(s, "session_autoclose %d\n", mdsmap->m_session_autoclose);
+	for (i = 0; i < mdsmap->possible_max_rank; i++) {
+		struct ceph_entity_addr *addr = &mdsmap->m_info[i].addr;
+		int state = mdsmap->m_info[i].state;
+		seq_printf(s, "\tmds%d\t%s\t(%s)\n", i,
+			       ceph_pr_addr(addr),
+			       ceph_mds_state_name(state));
+	}
+	return 0;
+}
+
+/*
+ * mdsc debugfs
+ */
+static int mdsc_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_mds_request *req;
+	struct rb_node *rp;
+	char *path;
+
+	mutex_lock(&mdsc->mutex);
+	for (rp = rb_first(&mdsc->request_tree); rp; rp = rb_next(rp)) {
+		req = rb_entry(rp, struct ceph_mds_request, r_node);
+
+		if (req->r_request && req->r_session)
+			seq_printf(s, "%lld\tmds%d\t", req->r_tid,
+				   req->r_session->s_mds);
+		else if (!req->r_request)
+			seq_printf(s, "%lld\t(no request)\t", req->r_tid);
+		else
+			seq_printf(s, "%lld\t(no session)\t", req->r_tid);
+
+		seq_printf(s, "%s", ceph_mds_op_name(req->r_op));
+
+		if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags))
+			seq_puts(s, "\t(unsafe)");
+		else
+			seq_puts(s, "\t");
+
+		if (req->r_inode) {
+			seq_printf(s, " #%llx", ceph_ino(req->r_inode));
+		} else if (req->r_dentry) {
+			struct ceph_path_info path_info = {0};
+			path = ceph_mdsc_build_path(mdsc, req->r_dentry, &path_info, 0);
+			if (IS_ERR(path))
+				path = NULL;
+			spin_lock(&req->r_dentry->d_lock);
+			seq_printf(s, " #%llx/%pd (%s)",
+				   ceph_ino(d_inode(req->r_dentry->d_parent)),
+				   req->r_dentry,
+				   path ? path : "");
+			spin_unlock(&req->r_dentry->d_lock);
+			ceph_mdsc_free_path_info(&path_info);
+		} else if (req->r_path1) {
+			seq_printf(s, " #%llx/%s", req->r_ino1.ino,
+				   req->r_path1);
+		} else {
+			seq_printf(s, " #%llx", req->r_ino1.ino);
+		}
+
+		if (req->r_old_dentry) {
+			struct ceph_path_info path_info = {0};
+			path = ceph_mdsc_build_path(mdsc, req->r_old_dentry, &path_info, 0);
+			if (IS_ERR(path))
+				path = NULL;
+			spin_lock(&req->r_old_dentry->d_lock);
+			seq_printf(s, " #%llx/%pd (%s)",
+				   req->r_old_dentry_dir ?
+				   ceph_ino(req->r_old_dentry_dir) : 0,
+				   req->r_old_dentry,
+				   path ? path : "");
+			spin_unlock(&req->r_old_dentry->d_lock);
+			ceph_mdsc_free_path_info(&path_info);
+		} else if (req->r_path2 && req->r_op != CEPH_MDS_OP_SYMLINK) {
+			if (req->r_ino2.ino)
+				seq_printf(s, " #%llx/%s", req->r_ino2.ino,
+					   req->r_path2);
+			else
+				seq_printf(s, " %s", req->r_path2);
+		}
+
+		seq_puts(s, "\n");
+	}
+	mutex_unlock(&mdsc->mutex);
+
+	return 0;
+}
+
+#define CEPH_LAT_METRIC_SHOW(name, total, avg, min, max, sq) {		\
+	s64 _total, _avg, _min, _max, _sq, _st;				\
+	_avg = ktime_to_us(avg);					\
+	_min = ktime_to_us(min == KTIME_MAX ? 0 : min);			\
+	_max = ktime_to_us(max);					\
+	_total = total - 1;						\
+	_sq = _total > 0 ? DIV64_U64_ROUND_CLOSEST(sq, _total) : 0;	\
+	_st = int_sqrt64(_sq);						\
+	_st = ktime_to_us(_st);						\
+	seq_printf(s, "%-14s%-12lld%-16lld%-16lld%-16lld%lld\n",	\
+		   name, total, _avg, _min, _max, _st);			\
+}
+
+#define CEPH_SZ_METRIC_SHOW(name, total, avg, min, max, sum) {		\
+	u64 _min = min == U64_MAX ? 0 : min;				\
+	seq_printf(s, "%-14s%-12lld%-16llu%-16llu%-16llu%llu\n",	\
+		   name, total, avg, _min, max, sum);			\
+}
+
+static int metrics_file_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_client_metric *m = &fsc->mdsc->metric;
+
+	seq_printf(s, "item                               total\n");
+	seq_printf(s, "------------------------------------------\n");
+	seq_printf(s, "%-35s%lld\n", "total inodes",
+		   percpu_counter_sum(&m->total_inodes));
+	seq_printf(s, "%-35s%lld\n", "opened files",
+		   atomic64_read(&m->opened_files));
+	seq_printf(s, "%-35s%lld\n", "pinned i_caps",
+		   atomic64_read(&m->total_caps));
+	seq_printf(s, "%-35s%lld\n", "opened inodes",
+		   percpu_counter_sum(&m->opened_inodes));
+	return 0;
+}
+
+static const char * const metric_str[] = {
+	"read",
+	"write",
+	"metadata",
+	"copyfrom"
+};
+static int metrics_latency_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_client_metric *cm = &fsc->mdsc->metric;
+	struct ceph_metric *m;
+	s64 total, avg, min, max, sq;
+	int i;
+
+	seq_printf(s, "item          total       avg_lat(us)     min_lat(us)     max_lat(us)     stdev(us)\n");
+	seq_printf(s, "-----------------------------------------------------------------------------------\n");
+
+	for (i = 0; i < METRIC_MAX; i++) {
+		m = &cm->metric[i];
+		spin_lock(&m->lock);
+		total = m->total;
+		avg = m->latency_avg;
+		min = m->latency_min;
+		max = m->latency_max;
+		sq = m->latency_sq_sum;
+		spin_unlock(&m->lock);
+		CEPH_LAT_METRIC_SHOW(metric_str[i], total, avg, min, max, sq);
+	}
+
+	return 0;
+}
+
+static int metrics_size_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_client_metric *cm = &fsc->mdsc->metric;
+	struct ceph_metric *m;
+	s64 total;
+	u64 sum, avg, min, max;
+	int i;
+
+	seq_printf(s, "item          total       avg_sz(bytes)   min_sz(bytes)   max_sz(bytes)  total_sz(bytes)\n");
+	seq_printf(s, "----------------------------------------------------------------------------------------\n");
+
+	for (i = 0; i < METRIC_MAX; i++) {
+		/* skip 'metadata' as it doesn't use the size metric */
+		if (i == METRIC_METADATA)
+			continue;
+		m = &cm->metric[i];
+		spin_lock(&m->lock);
+		total = m->total;
+		sum = m->size_sum;
+		avg = total > 0 ? DIV64_U64_ROUND_CLOSEST(sum, total) : 0;
+		min = m->size_min;
+		max = m->size_max;
+		spin_unlock(&m->lock);
+		CEPH_SZ_METRIC_SHOW(metric_str[i], total, avg, min, max, sum);
+	}
+
+	return 0;
+}
+
+static int metrics_caps_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_client_metric *m = &fsc->mdsc->metric;
+	int nr_caps = 0;
+
+	seq_printf(s, "item          total           miss            hit\n");
+	seq_printf(s, "-------------------------------------------------\n");
+
+	seq_printf(s, "%-14s%-16lld%-16lld%lld\n", "d_lease",
+		   atomic64_read(&m->total_dentries),
+		   percpu_counter_sum(&m->d_lease_mis),
+		   percpu_counter_sum(&m->d_lease_hit));
+
+	nr_caps = atomic64_read(&m->total_caps);
+	seq_printf(s, "%-14s%-16d%-16lld%lld\n", "caps", nr_caps,
+		   percpu_counter_sum(&m->i_caps_mis),
+		   percpu_counter_sum(&m->i_caps_hit));
+
+	return 0;
+}
+
+static int caps_show_cb(struct inode *inode, int mds, void *p)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct seq_file *s = p;
+	struct ceph_cap *cap;
+
+	spin_lock(&ci->i_ceph_lock);
+	cap = __get_cap_for_mds(ci, mds);
+	if (cap)
+		seq_printf(s, "0x%-17llx%-3d%-17s%-17s\n", ceph_ino(inode),
+			   cap->session->s_mds,
+			   ceph_cap_string(cap->issued),
+			   ceph_cap_string(cap->implemented));
+	spin_unlock(&ci->i_ceph_lock);
+	return 0;
+}
+
+static int caps_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	int total, avail, used, reserved, min, i;
+	struct cap_wait	*cw;
+
+	ceph_reservation_status(fsc, &total, &avail, &used, &reserved, &min);
+	seq_printf(s, "total\t\t%d\n"
+		   "avail\t\t%d\n"
+		   "used\t\t%d\n"
+		   "reserved\t%d\n"
+		   "min\t\t%d\n\n",
+		   total, avail, used, reserved, min);
+	seq_printf(s, "ino              mds  issued           implemented\n");
+	seq_printf(s, "--------------------------------------------------\n");
+
+	mutex_lock(&mdsc->mutex);
+	for (i = 0; i < mdsc->max_sessions; i++) {
+		struct ceph_mds_session *session;
+
+		session = __ceph_lookup_mds_session(mdsc, i);
+		if (!session)
+			continue;
+		mutex_unlock(&mdsc->mutex);
+		mutex_lock(&session->s_mutex);
+		ceph_iterate_session_caps(session, caps_show_cb, s);
+		mutex_unlock(&session->s_mutex);
+		ceph_put_mds_session(session);
+		mutex_lock(&mdsc->mutex);
+	}
+	mutex_unlock(&mdsc->mutex);
+
+	seq_printf(s, "\n\nWaiters:\n--------\n");
+	seq_printf(s, "tgid         ino                need             want\n");
+	seq_printf(s, "-----------------------------------------------------\n");
+
+	spin_lock(&mdsc->caps_list_lock);
+	list_for_each_entry(cw, &mdsc->cap_wait_list, list) {
+		seq_printf(s, "%-13d0x%-17llx%-17s%-17s\n", cw->tgid, cw->ino,
+				ceph_cap_string(cw->need),
+				ceph_cap_string(cw->want));
+	}
+	spin_unlock(&mdsc->caps_list_lock);
+
+	return 0;
+}
+
+static int mds_sessions_show(struct seq_file *s, void *ptr)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_auth_client *ac = fsc->client->monc.auth;
+	struct ceph_options *opt = fsc->client->options;
+	int mds;
+
+	mutex_lock(&mdsc->mutex);
+
+	/* The 'num' portion of an 'entity name' */
+	seq_printf(s, "global_id %llu\n", ac->global_id);
+
+	/* The -o name mount argument */
+	seq_printf(s, "name \"%s\"\n", opt->name ? opt->name : "");
+
+	/* The list of MDS session rank+state */
+	for (mds = 0; mds < mdsc->max_sessions; mds++) {
+		struct ceph_mds_session *session =
+			__ceph_lookup_mds_session(mdsc, mds);
+		if (!session) {
+			continue;
+		}
+		mutex_unlock(&mdsc->mutex);
+		seq_printf(s, "mds.%d %s\n",
+				session->s_mds,
+				ceph_session_state_name(session->s_state));
+
+		ceph_put_mds_session(session);
+		mutex_lock(&mdsc->mutex);
+	}
+	mutex_unlock(&mdsc->mutex);
+
+	return 0;
+}
+
+static int status_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_entity_inst *inst = &fsc->client->msgr.inst;
+	struct ceph_entity_addr *client_addr = ceph_client_addr(fsc->client);
+
+	seq_printf(s, "instance: %s.%lld %s/%u\n", ENTITY_NAME(inst->name),
+		   ceph_pr_addr(client_addr), le32_to_cpu(client_addr->nonce));
+	seq_printf(s, "blocklisted: %s\n", str_true_false(fsc->blocklisted));
+
+	return 0;
+}
+
+static int reset_status_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_client_reset_state *st;
+	u64 trigger = 0, success = 0, failure = 0;
+	unsigned long last_start = 0, last_finish = 0;
+	int last_errno = 0;
+	enum ceph_client_reset_phase phase = CEPH_CLIENT_RESET_IDLE;
+	bool drain_timed_out = false;
+	int sessions_reset = 0;
+	int blocked_requests = 0;
+	char reason[CEPH_CLIENT_RESET_REASON_LEN];
+
+	if (!mdsc)
+		return 0;
+
+	st = &mdsc->reset_state;
+
+	spin_lock(&st->lock);
+	trigger = st->trigger_count;
+	success = st->success_count;
+	failure = st->failure_count;
+	last_start = st->last_start;
+	last_finish = st->last_finish;
+	last_errno = st->last_errno;
+	phase = st->phase;
+	drain_timed_out = st->drain_timed_out;
+	sessions_reset = st->sessions_reset;
+	strscpy(reason, st->last_reason, sizeof(reason));
+	spin_unlock(&st->lock);
+
+	blocked_requests = atomic_read(&st->blocked_requests);
+
+	seq_printf(s, "phase: %s\n", ceph_reset_phase_name(phase));
+	seq_printf(s, "trigger_count: %llu\n", trigger);
+	seq_printf(s, "success_count: %llu\n", success);
+	seq_printf(s, "failure_count: %llu\n", failure);
+	if (last_start)
+		seq_printf(s, "last_start_ms_ago: %u\n",
+			   jiffies_to_msecs(jiffies - last_start));
+	else
+		seq_puts(s, "last_start_ms_ago: (never)\n");
+	if (last_finish)
+		seq_printf(s, "last_finish_ms_ago: %u\n",
+			   jiffies_to_msecs(jiffies - last_finish));
+	else
+		seq_puts(s, "last_finish_ms_ago: (never)\n");
+	seq_printf(s, "last_errno: %d\n", last_errno);
+	seq_printf(s, "last_reason: %s\n",
+		   reason[0] ? reason : "(none)");
+	seq_printf(s, "drain_timed_out: %s\n",
+		   drain_timed_out ? "yes" : "no");
+	seq_printf(s, "sessions_reset: %d\n", sessions_reset);
+	seq_printf(s, "blocked_requests: %d\n", blocked_requests);
+
+	return 0;
+}
+
+static ssize_t reset_trigger_write(struct file *file, const char __user *buf,
+				   size_t len, loff_t *ppos)
+{
+	struct ceph_fs_client *fsc = file->private_data;
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	char reason[CEPH_CLIENT_RESET_REASON_LEN];
+	size_t copy;
+	int ret;
+
+	if (!mdsc)
+		return -ENODEV;
+
+	copy = min_t(size_t, len, sizeof(reason) - 1);
+	if (copy && copy_from_user(reason, buf, copy))
+		return -EFAULT;
+	reason[copy] = '\0';
+	strim(reason);
+
+	ret = ceph_mdsc_schedule_reset(mdsc, reason);
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+static int subvolume_metrics_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_subvol_metric_snapshot *snapshot = NULL;
+	u32 nr = 0;
+	u64 total_sent = 0;
+	u64 nonzero_sends = 0;
+	u32 i;
+
+	if (!mdsc) {
+		seq_puts(s, "mds client unavailable\n");
+		return 0;
+	}
+
+	mutex_lock(&mdsc->subvol_metrics_last_mutex);
+	if (mdsc->subvol_metrics_last && mdsc->subvol_metrics_last_nr) {
+		nr = mdsc->subvol_metrics_last_nr;
+		snapshot = kmemdup_array(mdsc->subvol_metrics_last, nr,
+					 sizeof(*snapshot), GFP_KERNEL);
+		if (!snapshot)
+			nr = 0;
+	}
+	total_sent = mdsc->subvol_metrics_sent;
+	nonzero_sends = mdsc->subvol_metrics_nonzero_sends;
+	mutex_unlock(&mdsc->subvol_metrics_last_mutex);
+
+	seq_puts(s, "Last sent subvolume metrics:\n");
+	if (!nr) {
+		seq_puts(s, "  (none)\n");
+	} else {
+		seq_puts(s, "  subvol_id          rd_ops    wr_ops    rd_bytes       wr_bytes       rd_lat_us      wr_lat_us\n");
+		for (i = 0; i < nr; i++) {
+			const struct ceph_subvol_metric_snapshot *e = &snapshot[i];
+
+			seq_printf(s, "  %-18llu %-9llu %-9llu %-14llu %-14llu %-14llu %-14llu\n",
+				   e->subvolume_id,
+				   e->read_ops, e->write_ops,
+				   e->read_bytes, e->write_bytes,
+				   e->read_latency_us, e->write_latency_us);
+		}
+	}
+	kfree(snapshot);
+
+	seq_puts(s, "\nStatistics:\n");
+	seq_printf(s, "  entries_sent:      %llu\n", total_sent);
+	seq_printf(s, "  non_zero_sends:    %llu\n", nonzero_sends);
+
+	seq_puts(s, "\nPending (unsent) subvolume metrics:\n");
+	ceph_subvolume_metrics_dump(&mdsc->subvol_metrics, s);
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(mdsmap);
+DEFINE_SHOW_ATTRIBUTE(mdsc);
+DEFINE_SHOW_ATTRIBUTE(caps);
+DEFINE_SHOW_ATTRIBUTE(mds_sessions);
+DEFINE_SHOW_ATTRIBUTE(status);
+DEFINE_SHOW_ATTRIBUTE(reset_status);
+DEFINE_SHOW_ATTRIBUTE(metrics_file);
+DEFINE_SHOW_ATTRIBUTE(metrics_latency);
+DEFINE_SHOW_ATTRIBUTE(metrics_size);
+DEFINE_SHOW_ATTRIBUTE(metrics_caps);
+DEFINE_SHOW_ATTRIBUTE(subvolume_metrics);
+
+static int metric_features_show(struct seq_file *s, void *p)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	unsigned long session_features = 0;
+	bool have_session = false;
+	bool metric_collect = false;
+	bool subvol_support = false;
+	bool metrics_enabled = false;
+	bool subvol_enabled = false;
+	int i;
+
+	if (!mdsc) {
+		seq_puts(s, "mds client unavailable\n");
+		return 0;
+	}
+
+	mutex_lock(&mdsc->mutex);
+	if (mdsc->metric.session) {
+		have_session = true;
+		session_features = mdsc->metric.session->s_features;
+	}
+	mutex_unlock(&mdsc->mutex);
+
+	if (have_session) {
+		metric_collect =
+			test_bit(CEPHFS_FEATURE_METRIC_COLLECT,
+				 &session_features);
+		subvol_support =
+			test_bit(CEPHFS_FEATURE_SUBVOLUME_METRICS,
+				 &session_features);
+	}
+
+	metrics_enabled = !disable_send_metrics && have_session && metric_collect;
+	subvol_enabled = metrics_enabled && subvol_support;
+
+	seq_printf(s,
+		   "metrics_enabled: %s (disable_send_metrics=%d, session=%s, metric_collect=%s)\n",
+		   metrics_enabled ? "yes" : "no",
+		   disable_send_metrics ? 1 : 0,
+		   have_session ? "yes" : "no",
+		   metric_collect ? "yes" : "no");
+	seq_printf(s, "subvolume_metrics_enabled: %s\n",
+		   subvol_enabled ? "yes" : "no");
+	seq_printf(s, "session_feature_bits: 0x%lx\n", session_features);
+
+	if (!have_session) {
+		seq_puts(s, "(no active MDS session for metrics)\n");
+		return 0;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(ceph_session_feature_table); i++) {
+		const struct ceph_session_feature_desc *desc =
+			&ceph_session_feature_table[i];
+		bool set = test_bit(desc->bit, &session_features);
+
+		seq_printf(s, "  %-24s : %s\n", desc->name,
+			   set ? "yes" : "no");
+	}
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(metric_features);
+
+static const struct file_operations ceph_reset_trigger_fops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.write = reset_trigger_write,
+	.llseek = noop_llseek,
+};
+
+/*
+ * debugfs
+ */
+static int congestion_kb_set(void *data, u64 val)
+{
+	struct ceph_fs_client *fsc = (struct ceph_fs_client *)data;
+
+	fsc->mount_options->congestion_kb = (int)val;
+	return 0;
+}
+
+static int congestion_kb_get(void *data, u64 *val)
+{
+	struct ceph_fs_client *fsc = (struct ceph_fs_client *)data;
+
+	*val = (u64)fsc->mount_options->congestion_kb;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(congestion_kb_fops, congestion_kb_get,
+			congestion_kb_set, "%llu\n");
+
+
+void ceph_fs_debugfs_cleanup(struct ceph_fs_client *fsc)
+{
+	doutc(fsc->client, "begin\n");
+	debugfs_remove(fsc->debugfs_bdi);
+	debugfs_remove(fsc->debugfs_congestion_kb);
+	debugfs_remove(fsc->debugfs_mdsmap);
+	debugfs_remove(fsc->debugfs_mds_sessions);
+	debugfs_remove(fsc->debugfs_caps);
+	debugfs_remove(fsc->debugfs_status);
+	debugfs_remove(fsc->debugfs_mdsc);
+	debugfs_remove_recursive(fsc->debugfs_reset_dir);
+	debugfs_remove(fsc->debugfs_subvolume_metrics);
+	debugfs_remove_recursive(fsc->debugfs_metrics_dir);
+	doutc(fsc->client, "done\n");
+}
+
+void ceph_fs_debugfs_init(struct ceph_fs_client *fsc)
+{
+	char name[NAME_MAX];
+
+	doutc(fsc->client, "begin\n");
+	fsc->debugfs_congestion_kb =
+		debugfs_create_file("writeback_congestion_kb",
+				    0600,
+				    fsc->client->debugfs_dir,
+				    fsc,
+				    &congestion_kb_fops);
+
+	snprintf(name, sizeof(name), "../../bdi/%s",
+		 bdi_dev_name(fsc->sb->s_bdi));
+	fsc->debugfs_bdi =
+		debugfs_create_symlink("bdi",
+				       fsc->client->debugfs_dir,
+				       name);
+
+	fsc->debugfs_mdsmap = debugfs_create_file("mdsmap",
+					0400,
+					fsc->client->debugfs_dir,
+					fsc,
+					&mdsmap_fops);
+
+	fsc->debugfs_mds_sessions = debugfs_create_file("mds_sessions",
+					0400,
+					fsc->client->debugfs_dir,
+					fsc,
+					&mds_sessions_fops);
+
+	fsc->debugfs_mdsc = debugfs_create_file("mdsc",
+						0400,
+						fsc->client->debugfs_dir,
+						fsc,
+						&mdsc_fops);
+
+	fsc->debugfs_caps = debugfs_create_file("caps",
+						0400,
+						fsc->client->debugfs_dir,
+						fsc,
+						&caps_fops);
+
+	fsc->debugfs_reset_dir = debugfs_create_dir("reset",
+						    fsc->client->debugfs_dir);
+	debugfs_create_file("trigger", 0200,
+			    fsc->debugfs_reset_dir, fsc,
+			    &ceph_reset_trigger_fops);
+	debugfs_create_file("status", 0400,
+			    fsc->debugfs_reset_dir, fsc,
+			    &reset_status_fops);
+
+	fsc->debugfs_status = debugfs_create_file("status",
+						  0400,
+						  fsc->client->debugfs_dir,
+						  fsc,
+						  &status_fops);
+
+	fsc->debugfs_metrics_dir = debugfs_create_dir("metrics",
+						      fsc->client->debugfs_dir);
+
+	debugfs_create_file("file", 0400, fsc->debugfs_metrics_dir, fsc,
+			    &metrics_file_fops);
+	debugfs_create_file("latency", 0400, fsc->debugfs_metrics_dir, fsc,
+			    &metrics_latency_fops);
+	debugfs_create_file("size", 0400, fsc->debugfs_metrics_dir, fsc,
+			    &metrics_size_fops);
+	debugfs_create_file("caps", 0400, fsc->debugfs_metrics_dir, fsc,
+			    &metrics_caps_fops);
+	debugfs_create_file("metric_features", 0400, fsc->debugfs_metrics_dir,
+			    fsc, &metric_features_fops);
+	fsc->debugfs_subvolume_metrics =
+		debugfs_create_file("subvolumes", 0400,
+				    fsc->debugfs_metrics_dir, fsc,
+				    &subvolume_metrics_fops);
+	doutc(fsc->client, "done\n");
+}
+
+
+#else  /* CONFIG_DEBUG_FS */
+
+void ceph_fs_debugfs_init(struct ceph_fs_client *fsc)
+{
+}
+
+void ceph_fs_debugfs_cleanup(struct ceph_fs_client *fsc)
+{
+}
+
+#endif  /* CONFIG_DEBUG_FS */