1 files changed, 1027 insertions, 0 deletions

diff --git a/fs/bcachefs/sysfs.c b/fs/bcachefs/sysfs.c
new file mode 100644
index 000000000000..430dcbcb6e8a
--- /dev/null
+++ b/fs/bcachefs/sysfs.c
@@ -0,0 +1,1027 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * bcache sysfs interfaces
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#ifndef NO_BCACHEFS_SYSFS
+
+#include "bcachefs.h"
+#include "alloc.h"
+#include "compress.h"
+#include "sysfs.h"
+#include "btree_cache.h"
+#include "btree_io.h"
+#include "btree_iter.h"
+#include "btree_update.h"
+#include "btree_update_interior.h"
+#include "btree_gc.h"
+#include "buckets.h"
+#include "disk_groups.h"
+#include "inode.h"
+#include "journal.h"
+#include "keylist.h"
+#include "move.h"
+#include "opts.h"
+#include "rebalance.h"
+#include "replicas.h"
+#include "super-io.h"
+#include "tests.h"
+
+#include <linux/blkdev.h>
+#include <linux/sort.h>
+#include <linux/sched/clock.h>
+
+#include "util.h"
+
+#define SYSFS_OPS(type)							\
+struct sysfs_ops type ## _sysfs_ops = {					\
+	.show	= type ## _show,					\
+	.store	= type ## _store					\
+}
+
+#define SHOW(fn)							\
+static ssize_t fn ## _show(struct kobject *kobj, struct attribute *attr,\
+			   char *buf)					\
+
+#define STORE(fn)							\
+static ssize_t fn ## _store(struct kobject *kobj, struct attribute *attr,\
+			    const char *buf, size_t size)		\
+
+#define __sysfs_attribute(_name, _mode)					\
+	static struct attribute sysfs_##_name =				\
+		{ .name = #_name, .mode = _mode }
+
+#define write_attribute(n)	__sysfs_attribute(n, S_IWUSR)
+#define read_attribute(n)	__sysfs_attribute(n, S_IRUGO)
+#define rw_attribute(n)		__sysfs_attribute(n, S_IRUGO|S_IWUSR)
+
+#define sysfs_printf(file, fmt, ...)					\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return scnprintf(buf, PAGE_SIZE, fmt "\n", __VA_ARGS__);\
+} while (0)
+
+#define sysfs_print(file, var)						\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return snprint(buf, PAGE_SIZE, var);			\
+} while (0)
+
+#define sysfs_hprint(file, val)						\
+do {									\
+	if (attr == &sysfs_ ## file) {					\
+		ssize_t ret = bch2_hprint(buf, val);			\
+		strcat(buf, "\n");					\
+		return ret + 1;						\
+	}								\
+} while (0)
+
+#define var_printf(_var, fmt)	sysfs_printf(_var, fmt, var(_var))
+#define var_print(_var)		sysfs_print(_var, var(_var))
+#define var_hprint(_var)	sysfs_hprint(_var, var(_var))
+
+#define sysfs_strtoul(file, var)					\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return strtoul_safe(buf, var) ?: (ssize_t) size;	\
+} while (0)
+
+#define sysfs_strtoul_clamp(file, var, min, max)			\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return strtoul_safe_clamp(buf, var, min, max)		\
+			?: (ssize_t) size;				\
+} while (0)
+
+#define strtoul_or_return(cp)						\
+({									\
+	unsigned long _v;						\
+	int _r = kstrtoul(cp, 10, &_v);					\
+	if (_r)								\
+		return _r;						\
+	_v;								\
+})
+
+#define strtoul_restrict_or_return(cp, min, max)			\
+({									\
+	unsigned long __v = 0;						\
+	int _r = strtoul_safe_restrict(cp, __v, min, max);		\
+	if (_r)								\
+		return _r;						\
+	__v;								\
+})
+
+#define strtoi_h_or_return(cp)						\
+({									\
+	u64 _v;								\
+	int _r = strtoi_h(cp, &_v);					\
+	if (_r)								\
+		return _r;						\
+	_v;								\
+})
+
+#define sysfs_hatoi(file, var)						\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return strtoi_h(buf, &var) ?: (ssize_t) size;		\
+} while (0)
+
+write_attribute(trigger_journal_flush);
+write_attribute(trigger_btree_coalesce);
+write_attribute(trigger_gc);
+write_attribute(prune_cache);
+rw_attribute(btree_gc_periodic);
+
+read_attribute(uuid);
+read_attribute(minor);
+read_attribute(bucket_size);
+read_attribute(block_size);
+read_attribute(btree_node_size);
+read_attribute(first_bucket);
+read_attribute(nbuckets);
+read_attribute(durability);
+read_attribute(iodone);
+
+read_attribute(io_latency_read);
+read_attribute(io_latency_write);
+read_attribute(io_latency_stats_read);
+read_attribute(io_latency_stats_write);
+read_attribute(congested);
+
+read_attribute(bucket_quantiles_last_read);
+read_attribute(bucket_quantiles_last_write);
+read_attribute(bucket_quantiles_fragmentation);
+read_attribute(bucket_quantiles_oldest_gen);
+
+read_attribute(reserve_stats);
+read_attribute(btree_cache_size);
+read_attribute(compression_stats);
+read_attribute(journal_debug);
+read_attribute(journal_pins);
+read_attribute(btree_updates);
+read_attribute(dirty_btree_nodes);
+
+read_attribute(internal_uuid);
+
+read_attribute(has_data);
+read_attribute(alloc_debug);
+write_attribute(wake_allocator);
+
+read_attribute(read_realloc_races);
+read_attribute(extent_migrate_done);
+read_attribute(extent_migrate_raced);
+
+rw_attribute(journal_write_delay_ms);
+rw_attribute(journal_reclaim_delay_ms);
+
+rw_attribute(discard);
+rw_attribute(cache_replacement_policy);
+rw_attribute(label);
+
+rw_attribute(copy_gc_enabled);
+sysfs_pd_controller_attribute(copy_gc);
+
+rw_attribute(rebalance_enabled);
+sysfs_pd_controller_attribute(rebalance);
+read_attribute(rebalance_work);
+rw_attribute(promote_whole_extents);
+
+rw_attribute(pd_controllers_update_seconds);
+
+read_attribute(meta_replicas_have);
+read_attribute(data_replicas_have);
+
+#ifdef CONFIG_BCACHEFS_TESTS
+write_attribute(perf_test);
+#endif /* CONFIG_BCACHEFS_TESTS */
+
+#define BCH_DEBUG_PARAM(name, description)				\
+	rw_attribute(name);
+
+	BCH_DEBUG_PARAMS()
+#undef BCH_DEBUG_PARAM
+
+#define x(_name)						\
+	static struct attribute sysfs_time_stat_##_name =		\
+		{ .name = #_name, .mode = S_IRUGO };
+	BCH_TIME_STATS()
+#undef x
+
+static struct attribute sysfs_state_rw = {
+	.name = "state",
+	.mode = S_IRUGO
+};
+
+static size_t bch2_btree_cache_size(struct bch_fs *c)
+{
+	size_t ret = 0;
+	struct btree *b;
+
+	mutex_lock(&c->btree_cache.lock);
+	list_for_each_entry(b, &c->btree_cache.live, list)
+		ret += btree_bytes(c);
+
+	mutex_unlock(&c->btree_cache.lock);
+	return ret;
+}
+
+static ssize_t show_fs_alloc_debug(struct bch_fs *c, char *buf)
+{
+	struct bch_fs_usage stats = bch2_fs_usage_read(c);
+
+	return scnprintf(buf, PAGE_SIZE,
+			 "capacity:\t\t%llu\n"
+			 "1 replicas:\n"
+			 "\tmeta:\t\t%llu\n"
+			 "\tdirty:\t\t%llu\n"
+			 "\treserved:\t%llu\n"
+			 "2 replicas:\n"
+			 "\tmeta:\t\t%llu\n"
+			 "\tdirty:\t\t%llu\n"
+			 "\treserved:\t%llu\n"
+			 "3 replicas:\n"
+			 "\tmeta:\t\t%llu\n"
+			 "\tdirty:\t\t%llu\n"
+			 "\treserved:\t%llu\n"
+			 "4 replicas:\n"
+			 "\tmeta:\t\t%llu\n"
+			 "\tdirty:\t\t%llu\n"
+			 "\treserved:\t%llu\n"
+			 "online reserved:\t%llu\n",
+			 c->capacity,
+			 stats.s[0].data[S_META],
+			 stats.s[0].data[S_DIRTY],
+			 stats.s[0].persistent_reserved,
+			 stats.s[1].data[S_META],
+			 stats.s[1].data[S_DIRTY],
+			 stats.s[1].persistent_reserved,
+			 stats.s[2].data[S_META],
+			 stats.s[2].data[S_DIRTY],
+			 stats.s[2].persistent_reserved,
+			 stats.s[3].data[S_META],
+			 stats.s[3].data[S_DIRTY],
+			 stats.s[3].persistent_reserved,
+			 stats.online_reserved);
+}
+
+static ssize_t bch2_compression_stats(struct bch_fs *c, char *buf)
+{
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	u64 nr_uncompressed_extents = 0, uncompressed_sectors = 0,
+	    nr_compressed_extents = 0,
+	    compressed_sectors_compressed = 0,
+	    compressed_sectors_uncompressed = 0;
+
+	if (!bch2_fs_running(c))
+		return -EPERM;
+
+	for_each_btree_key(&iter, c, BTREE_ID_EXTENTS, POS_MIN, 0, k)
+		if (k.k->type == BCH_EXTENT) {
+			struct bkey_s_c_extent e = bkey_s_c_to_extent(k);
+			const struct bch_extent_ptr *ptr;
+			struct bch_extent_crc_unpacked crc;
+
+			extent_for_each_ptr_crc(e, ptr, crc) {
+				if (crc.compression_type == BCH_COMPRESSION_NONE) {
+					nr_uncompressed_extents++;
+					uncompressed_sectors += e.k->size;
+				} else {
+					nr_compressed_extents++;
+					compressed_sectors_compressed +=
+						crc.compressed_size;
+					compressed_sectors_uncompressed +=
+						crc.uncompressed_size;
+				}
+
+				/* only looking at the first ptr */
+				break;
+			}
+		}
+	bch2_btree_iter_unlock(&iter);
+
+	return scnprintf(buf, PAGE_SIZE,
+			"uncompressed data:\n"
+			"	nr extents:			%llu\n"
+			"	size (bytes):			%llu\n"
+			"compressed data:\n"
+			"	nr extents:			%llu\n"
+			"	compressed size (bytes):	%llu\n"
+			"	uncompressed size (bytes):	%llu\n",
+			nr_uncompressed_extents,
+			uncompressed_sectors << 9,
+			nr_compressed_extents,
+			compressed_sectors_compressed << 9,
+			compressed_sectors_uncompressed << 9);
+}
+
+SHOW(bch2_fs)
+{
+	struct bch_fs *c = container_of(kobj, struct bch_fs, kobj);
+
+	sysfs_print(minor,			c->minor);
+	sysfs_printf(internal_uuid, "%pU",	c->sb.uuid.b);
+
+	sysfs_print(journal_write_delay_ms,	c->journal.write_delay_ms);
+	sysfs_print(journal_reclaim_delay_ms,	c->journal.reclaim_delay_ms);
+
+	sysfs_print(block_size,			block_bytes(c));
+	sysfs_print(btree_node_size,		btree_bytes(c));
+	sysfs_hprint(btree_cache_size,		bch2_btree_cache_size(c));
+
+	sysfs_print(read_realloc_races,
+		    atomic_long_read(&c->read_realloc_races));
+	sysfs_print(extent_migrate_done,
+		    atomic_long_read(&c->extent_migrate_done));
+	sysfs_print(extent_migrate_raced,
+		    atomic_long_read(&c->extent_migrate_raced));
+
+	sysfs_printf(btree_gc_periodic, "%u",	(int) c->btree_gc_periodic);
+
+	sysfs_printf(copy_gc_enabled, "%i", c->copy_gc_enabled);
+
+	sysfs_print(pd_controllers_update_seconds,
+		    c->pd_controllers_update_seconds);
+
+	sysfs_printf(rebalance_enabled,		"%i", c->rebalance.enabled);
+	sysfs_pd_controller_show(rebalance,	&c->rebalance.pd); /* XXX */
+
+	if (attr == &sysfs_rebalance_work)
+		return bch2_rebalance_work_show(c, buf);
+
+	sysfs_print(promote_whole_extents,	c->promote_whole_extents);
+
+	sysfs_printf(meta_replicas_have, "%u",	bch2_replicas_online(c, true));
+	sysfs_printf(data_replicas_have, "%u",	bch2_replicas_online(c, false));
+
+	/* Debugging: */
+
+	if (attr == &sysfs_alloc_debug)
+		return show_fs_alloc_debug(c, buf);
+
+	if (attr == &sysfs_journal_debug)
+		return bch2_journal_print_debug(&c->journal, buf);
+
+	if (attr == &sysfs_journal_pins)
+		return bch2_journal_print_pins(&c->journal, buf);
+
+	if (attr == &sysfs_btree_updates)
+		return bch2_btree_updates_print(c, buf);
+
+	if (attr == &sysfs_dirty_btree_nodes)
+		return bch2_dirty_btree_nodes_print(c, buf);
+
+	if (attr == &sysfs_compression_stats)
+		return bch2_compression_stats(c, buf);
+
+#define BCH_DEBUG_PARAM(name, description) sysfs_print(name, c->name);
+	BCH_DEBUG_PARAMS()
+#undef BCH_DEBUG_PARAM
+
+	return 0;
+}
+
+STORE(__bch2_fs)
+{
+	struct bch_fs *c = container_of(kobj, struct bch_fs, kobj);
+
+	sysfs_strtoul(journal_write_delay_ms, c->journal.write_delay_ms);
+	sysfs_strtoul(journal_reclaim_delay_ms, c->journal.reclaim_delay_ms);
+
+	if (attr == &sysfs_btree_gc_periodic) {
+		ssize_t ret = strtoul_safe(buf, c->btree_gc_periodic)
+			?: (ssize_t) size;
+
+		wake_up_process(c->gc_thread);
+		return ret;
+	}
+
+	if (attr == &sysfs_copy_gc_enabled) {
+		struct bch_dev *ca;
+		unsigned i;
+		ssize_t ret = strtoul_safe(buf, c->copy_gc_enabled)
+			?: (ssize_t) size;
+
+		for_each_member_device(ca, c, i)
+			if (ca->copygc_thread)
+				wake_up_process(ca->copygc_thread);
+		return ret;
+	}
+
+	if (attr == &sysfs_rebalance_enabled) {
+		ssize_t ret = strtoul_safe(buf, c->rebalance.enabled)
+			?: (ssize_t) size;
+
+		rebalance_wakeup(c);
+		return ret;
+	}
+
+	sysfs_strtoul(pd_controllers_update_seconds,
+		      c->pd_controllers_update_seconds);
+	sysfs_pd_controller_store(rebalance,	&c->rebalance.pd);
+
+	sysfs_strtoul(promote_whole_extents,	c->promote_whole_extents);
+
+	/* Debugging: */
+
+#define BCH_DEBUG_PARAM(name, description) sysfs_strtoul(name, c->name);
+	BCH_DEBUG_PARAMS()
+#undef BCH_DEBUG_PARAM
+
+	if (!bch2_fs_running(c))
+		return -EPERM;
+
+	/* Debugging: */
+
+	if (attr == &sysfs_trigger_journal_flush)
+		bch2_journal_meta_async(&c->journal, NULL);
+
+	if (attr == &sysfs_trigger_btree_coalesce)
+		bch2_coalesce(c);
+
+	if (attr == &sysfs_trigger_gc)
+		bch2_gc(c);
+
+	if (attr == &sysfs_prune_cache) {
+		struct shrink_control sc;
+
+		sc.gfp_mask = GFP_KERNEL;
+		sc.nr_to_scan = strtoul_or_return(buf);
+		c->btree_cache.shrink.scan_objects(&c->btree_cache.shrink, &sc);
+	}
+#ifdef CONFIG_BCACHEFS_TESTS
+	if (attr == &sysfs_perf_test) {
+		char *tmp = kstrdup(buf, GFP_KERNEL), *p = tmp;
+		char *test		= strsep(&p, " \t\n");
+		char *nr_str		= strsep(&p, " \t\n");
+		char *threads_str	= strsep(&p, " \t\n");
+		unsigned threads;
+		u64 nr;
+		int ret = -EINVAL;
+
+		if (threads_str &&
+		    !(ret = kstrtouint(threads_str, 10, &threads)) &&
+		    !(ret = bch2_strtoull_h(nr_str, &nr)))
+			bch2_btree_perf_test(c, test, nr, threads);
+		else
+			size = ret;
+		kfree(tmp);
+	}
+#endif
+	return size;
+}
+
+STORE(bch2_fs)
+{
+	struct bch_fs *c = container_of(kobj, struct bch_fs, kobj);
+
+	mutex_lock(&c->state_lock);
+	size = __bch2_fs_store(kobj, attr, buf, size);
+	mutex_unlock(&c->state_lock);
+
+	return size;
+}
+SYSFS_OPS(bch2_fs);
+
+struct attribute *bch2_fs_files[] = {
+	&sysfs_minor,
+	&sysfs_block_size,
+	&sysfs_btree_node_size,
+	&sysfs_btree_cache_size,
+
+	&sysfs_meta_replicas_have,
+	&sysfs_data_replicas_have,
+
+	&sysfs_journal_write_delay_ms,
+	&sysfs_journal_reclaim_delay_ms,
+
+	&sysfs_promote_whole_extents,
+
+	&sysfs_compression_stats,
+
+#ifdef CONFIG_BCACHEFS_TESTS
+	&sysfs_perf_test,
+#endif
+	NULL
+};
+
+/* internal dir - just a wrapper */
+
+SHOW(bch2_fs_internal)
+{
+	struct bch_fs *c = container_of(kobj, struct bch_fs, internal);
+	return bch2_fs_show(&c->kobj, attr, buf);
+}
+
+STORE(bch2_fs_internal)
+{
+	struct bch_fs *c = container_of(kobj, struct bch_fs, internal);
+	return bch2_fs_store(&c->kobj, attr, buf, size);
+}
+SYSFS_OPS(bch2_fs_internal);
+
+struct attribute *bch2_fs_internal_files[] = {
+	&sysfs_alloc_debug,
+	&sysfs_journal_debug,
+	&sysfs_journal_pins,
+	&sysfs_btree_updates,
+	&sysfs_dirty_btree_nodes,
+
+	&sysfs_read_realloc_races,
+	&sysfs_extent_migrate_done,
+	&sysfs_extent_migrate_raced,
+
+	&sysfs_trigger_journal_flush,
+	&sysfs_trigger_btree_coalesce,
+	&sysfs_trigger_gc,
+	&sysfs_prune_cache,
+
+	&sysfs_copy_gc_enabled,
+
+	&sysfs_rebalance_enabled,
+	&sysfs_rebalance_work,
+	sysfs_pd_controller_files(rebalance),
+
+	&sysfs_internal_uuid,
+
+#define BCH_DEBUG_PARAM(name, description) &sysfs_##name,
+	BCH_DEBUG_PARAMS()
+#undef BCH_DEBUG_PARAM
+
+	NULL
+};
+
+/* options */
+
+SHOW(bch2_fs_opts_dir)
+{
+	char *out = buf, *end = buf + PAGE_SIZE;
+	struct bch_fs *c = container_of(kobj, struct bch_fs, opts_dir);
+	const struct bch_option *opt = container_of(attr, struct bch_option, attr);
+	int id = opt - bch2_opt_table;
+	u64 v = bch2_opt_get_by_id(&c->opts, id);
+
+	out += bch2_opt_to_text(c, out, end - out, opt, v, OPT_SHOW_FULL_LIST);
+	out += scnprintf(out, end - out, "\n");
+
+	return out - buf;
+}
+
+STORE(bch2_fs_opts_dir)
+{
+	struct bch_fs *c = container_of(kobj, struct bch_fs, opts_dir);
+	const struct bch_option *opt = container_of(attr, struct bch_option, attr);
+	int ret, id = opt - bch2_opt_table;
+	char *tmp;
+	u64 v;
+
+	tmp = kstrdup(buf, GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	ret = bch2_opt_parse(c, opt, strim(tmp), &v);
+	kfree(tmp);
+
+	if (ret < 0)
+		return ret;
+
+	if (id == Opt_compression ||
+	    id == Opt_background_compression) {
+		int ret = bch2_check_set_has_compressed_data(c, v);
+		if (ret) {
+			mutex_unlock(&c->sb_lock);
+			return ret;
+		}
+	}
+
+	if (opt->set_sb != SET_NO_SB_OPT) {
+		mutex_lock(&c->sb_lock);
+		opt->set_sb(c->disk_sb.sb, v);
+		bch2_write_super(c);
+		mutex_unlock(&c->sb_lock);
+	}
+
+	bch2_opt_set_by_id(&c->opts, id, v);
+
+	if ((id == Opt_background_target ||
+	     id == Opt_background_compression) && v) {
+		bch2_rebalance_add_work(c, S64_MAX);
+		rebalance_wakeup(c);
+	}
+
+	return size;
+}
+SYSFS_OPS(bch2_fs_opts_dir);
+
+struct attribute *bch2_fs_opts_dir_files[] = { NULL };
+
+int bch2_opts_create_sysfs_files(struct kobject *kobj)
+{
+	const struct bch_option *i;
+	int ret;
+
+	for (i = bch2_opt_table;
+	     i < bch2_opt_table + bch2_opts_nr;
+	     i++) {
+		if (i->mode == OPT_INTERNAL)
+			continue;
+
+		ret = sysfs_create_file(kobj, &i->attr);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/* time stats */
+
+SHOW(bch2_fs_time_stats)
+{
+	struct bch_fs *c = container_of(kobj, struct bch_fs, time_stats);
+
+#define x(name)						\
+	if (attr == &sysfs_time_stat_##name)				\
+		return bch2_time_stats_print(&c->times[BCH_TIME_##name],\
+					     buf, PAGE_SIZE);
+	BCH_TIME_STATS()
+#undef x
+
+	return 0;
+}
+
+STORE(bch2_fs_time_stats)
+{
+	return size;
+}
+SYSFS_OPS(bch2_fs_time_stats);
+
+struct attribute *bch2_fs_time_stats_files[] = {
+#define x(name)						\
+	&sysfs_time_stat_##name,
+	BCH_TIME_STATS()
+#undef x
+	NULL
+};
+
+typedef unsigned (bucket_map_fn)(struct bch_fs *, struct bch_dev *,
+				 size_t, void *);
+
+static unsigned bucket_last_io_fn(struct bch_fs *c, struct bch_dev *ca,
+				  size_t b, void *private)
+{
+	int rw = (private ? 1 : 0);
+
+	return bucket_last_io(c, bucket(ca, b), rw);
+}
+
+static unsigned bucket_sectors_used_fn(struct bch_fs *c, struct bch_dev *ca,
+				       size_t b, void *private)
+{
+	struct bucket *g = bucket(ca, b);
+	return bucket_sectors_used(g->mark);
+}
+
+static unsigned bucket_oldest_gen_fn(struct bch_fs *c, struct bch_dev *ca,
+				     size_t b, void *private)
+{
+	return bucket_gc_gen(ca, b);
+}
+
+static int unsigned_cmp(const void *_l, const void *_r)
+{
+	unsigned l = *((unsigned *) _l);
+	unsigned r = *((unsigned *) _r);
+
+	return (l > r) - (l < r);
+}
+
+static ssize_t show_quantiles(struct bch_fs *c, struct bch_dev *ca,
+			      char *buf, bucket_map_fn *fn, void *private)
+{
+	size_t i, n;
+	/* Compute 31 quantiles */
+	unsigned q[31], *p;
+	ssize_t ret = 0;
+
+	down_read(&ca->bucket_lock);
+	n = ca->mi.nbuckets;
+
+	p = vzalloc(n * sizeof(unsigned));
+	if (!p) {
+		up_read(&ca->bucket_lock);
+		return -ENOMEM;
+	}
+
+	for (i = ca->mi.first_bucket; i < n; i++)
+		p[i] = fn(c, ca, i, private);
+
+	sort(p, n, sizeof(unsigned), unsigned_cmp, NULL);
+	up_read(&ca->bucket_lock);
+
+	while (n &&
+	       !p[n - 1])
+		--n;
+
+	for (i = 0; i < ARRAY_SIZE(q); i++)
+		q[i] = p[n * (i + 1) / (ARRAY_SIZE(q) + 1)];
+
+	vfree(p);
+
+	for (i = 0; i < ARRAY_SIZE(q); i++)
+		ret += scnprintf(buf + ret, PAGE_SIZE - ret,
+				 "%u ", q[i]);
+	buf[ret - 1] = '\n';
+
+	return ret;
+}
+
+static ssize_t show_reserve_stats(struct bch_dev *ca, char *buf)
+{
+	enum alloc_reserve i;
+	ssize_t ret;
+
+	spin_lock(&ca->freelist_lock);
+
+	ret = scnprintf(buf, PAGE_SIZE,
+			"free_inc:\t%zu\t%zu\n",
+			fifo_used(&ca->free_inc),
+			ca->free_inc.size);
+
+	for (i = 0; i < RESERVE_NR; i++)
+		ret += scnprintf(buf + ret, PAGE_SIZE - ret,
+				 "free[%u]:\t%zu\t%zu\n", i,
+				 fifo_used(&ca->free[i]),
+				 ca->free[i].size);
+
+	spin_unlock(&ca->freelist_lock);
+
+	return ret;
+}
+
+static ssize_t show_dev_alloc_debug(struct bch_dev *ca, char *buf)
+{
+	struct bch_fs *c = ca->fs;
+	struct bch_dev_usage stats = bch2_dev_usage_read(c, ca);
+
+	return scnprintf(buf, PAGE_SIZE,
+		"free_inc:               %zu/%zu\n"
+		"free[RESERVE_BTREE]:    %zu/%zu\n"
+		"free[RESERVE_MOVINGGC]: %zu/%zu\n"
+		"free[RESERVE_NONE]:     %zu/%zu\n"
+		"buckets:\n"
+		"    capacity:           %llu\n"
+		"    alloc:              %llu\n"
+		"    sb:                 %llu\n"
+		"    journal:            %llu\n"
+		"    meta:               %llu\n"
+		"    user:               %llu\n"
+		"    cached:             %llu\n"
+		"    available:          %llu\n"
+		"sectors:\n"
+		"    sb:                 %llu\n"
+		"    journal:            %llu\n"
+		"    meta:               %llu\n"
+		"    user:               %llu\n"
+		"    cached:             %llu\n"
+		"freelist_wait:          %s\n"
+		"open buckets:           %u/%u (reserved %u)\n"
+		"open_buckets_wait:      %s\n",
+		fifo_used(&ca->free_inc),		ca->free_inc.size,
+		fifo_used(&ca->free[RESERVE_BTREE]),	ca->free[RESERVE_BTREE].size,
+		fifo_used(&ca->free[RESERVE_MOVINGGC]),	ca->free[RESERVE_MOVINGGC].size,
+		fifo_used(&ca->free[RESERVE_NONE]),	ca->free[RESERVE_NONE].size,
+		ca->mi.nbuckets - ca->mi.first_bucket,
+		stats.buckets_alloc,
+		stats.buckets[BCH_DATA_SB],
+		stats.buckets[BCH_DATA_JOURNAL],
+		stats.buckets[BCH_DATA_BTREE],
+		stats.buckets[BCH_DATA_USER],
+		stats.buckets[BCH_DATA_CACHED],
+		__dev_buckets_available(ca, stats),
+		stats.sectors[BCH_DATA_SB],
+		stats.sectors[BCH_DATA_JOURNAL],
+		stats.sectors[BCH_DATA_BTREE],
+		stats.sectors[BCH_DATA_USER],
+		stats.sectors[BCH_DATA_CACHED],
+		c->freelist_wait.list.first		? "waiting" : "empty",
+		c->open_buckets_nr_free, OPEN_BUCKETS_COUNT, BTREE_NODE_RESERVE,
+		c->open_buckets_wait.list.first		? "waiting" : "empty");
+}
+
+static const char * const bch2_rw[] = {
+	"read",
+	"write",
+	NULL
+};
+
+static ssize_t show_dev_iodone(struct bch_dev *ca, char *buf)
+{
+	char *out = buf, *end = buf + PAGE_SIZE;
+	int rw, i, cpu;
+
+	for (rw = 0; rw < 2; rw++) {
+		out += scnprintf(out, end - out, "%s:\n", bch2_rw[rw]);
+
+		for (i = 1; i < BCH_DATA_NR; i++) {
+			u64 n = 0;
+
+			for_each_possible_cpu(cpu)
+				n += per_cpu_ptr(ca->io_done, cpu)->sectors[rw][i];
+
+			out += scnprintf(out, end - out, "%-12s:%12llu\n",
+					 bch2_data_types[i], n << 9);
+		}
+	}
+
+	return out - buf;
+}
+
+SHOW(bch2_dev)
+{
+	struct bch_dev *ca = container_of(kobj, struct bch_dev, kobj);
+	struct bch_fs *c = ca->fs;
+	char *out = buf, *end = buf + PAGE_SIZE;
+
+	sysfs_printf(uuid,		"%pU\n", ca->uuid.b);
+
+	sysfs_print(bucket_size,	bucket_bytes(ca));
+	sysfs_print(block_size,		block_bytes(c));
+	sysfs_print(first_bucket,	ca->mi.first_bucket);
+	sysfs_print(nbuckets,		ca->mi.nbuckets);
+	sysfs_print(durability,		ca->mi.durability);
+	sysfs_print(discard,		ca->mi.discard);
+
+	if (attr == &sysfs_label) {
+		if (ca->mi.group) {
+			mutex_lock(&c->sb_lock);
+			out += bch2_disk_path_print(&c->disk_sb, out, end - out,
+						    ca->mi.group - 1);
+			mutex_unlock(&c->sb_lock);
+		} else {
+			out += scnprintf(out, end - out, "none");
+		}
+
+		out += scnprintf(out, end - out, "\n");
+		return out - buf;
+	}
+
+	if (attr == &sysfs_has_data) {
+		out += bch2_scnprint_flag_list(out, end - out,
+					       bch2_data_types,
+					       bch2_dev_has_data(c, ca));
+		out += scnprintf(out, end - out, "\n");
+		return out - buf;
+	}
+
+	sysfs_pd_controller_show(copy_gc, &ca->copygc_pd);
+
+	if (attr == &sysfs_cache_replacement_policy) {
+		out += bch2_scnprint_string_list(out, end - out,
+						 bch2_cache_replacement_policies,
+						 ca->mi.replacement);
+		out += scnprintf(out, end - out, "\n");
+		return out - buf;
+	}
+
+	if (attr == &sysfs_state_rw) {
+		out += bch2_scnprint_string_list(out, end - out,
+						 bch2_dev_state,
+						 ca->mi.state);
+		out += scnprintf(out, end - out, "\n");
+		return out - buf;
+	}
+
+	if (attr == &sysfs_iodone)
+		return show_dev_iodone(ca, buf);
+
+	sysfs_print(io_latency_read,		atomic64_read(&ca->cur_latency[READ]));
+	sysfs_print(io_latency_write,		atomic64_read(&ca->cur_latency[WRITE]));
+
+	if (attr == &sysfs_io_latency_stats_read)
+		return bch2_time_stats_print(&ca->io_latency[READ], buf, PAGE_SIZE);
+	if (attr == &sysfs_io_latency_stats_write)
+		return bch2_time_stats_print(&ca->io_latency[WRITE], buf, PAGE_SIZE);
+
+	sysfs_printf(congested,			"%u%%",
+		     clamp(atomic_read(&ca->congested), 0, CONGESTED_MAX)
+		     * 100 / CONGESTED_MAX);
+
+	if (attr == &sysfs_bucket_quantiles_last_read)
+		return show_quantiles(c, ca, buf, bucket_last_io_fn, (void *) 0);
+	if (attr == &sysfs_bucket_quantiles_last_write)
+		return show_quantiles(c, ca, buf, bucket_last_io_fn, (void *) 1);
+	if (attr == &sysfs_bucket_quantiles_fragmentation)
+		return show_quantiles(c, ca, buf, bucket_sectors_used_fn, NULL);
+	if (attr == &sysfs_bucket_quantiles_oldest_gen)
+		return show_quantiles(c, ca, buf, bucket_oldest_gen_fn, NULL);
+
+	if (attr == &sysfs_reserve_stats)
+		return show_reserve_stats(ca, buf);
+	if (attr == &sysfs_alloc_debug)
+		return show_dev_alloc_debug(ca, buf);
+
+	return 0;
+}
+
+STORE(bch2_dev)
+{
+	struct bch_dev *ca = container_of(kobj, struct bch_dev, kobj);
+	struct bch_fs *c = ca->fs;
+	struct bch_member *mi;
+
+	sysfs_pd_controller_store(copy_gc, &ca->copygc_pd);
+
+	if (attr == &sysfs_discard) {
+		bool v = strtoul_or_return(buf);
+
+		mutex_lock(&c->sb_lock);
+		mi = &bch2_sb_get_members(c->disk_sb.sb)->members[ca->dev_idx];
+
+		if (v != BCH_MEMBER_DISCARD(mi)) {
+			SET_BCH_MEMBER_DISCARD(mi, v);
+			bch2_write_super(c);
+		}
+		mutex_unlock(&c->sb_lock);
+	}
+
+	if (attr == &sysfs_cache_replacement_policy) {
+		ssize_t v = __sysfs_match_string(bch2_cache_replacement_policies, -1, buf);
+
+		if (v < 0)
+			return v;
+
+		mutex_lock(&c->sb_lock);
+		mi = &bch2_sb_get_members(c->disk_sb.sb)->members[ca->dev_idx];
+
+		if ((unsigned) v != BCH_MEMBER_REPLACEMENT(mi)) {
+			SET_BCH_MEMBER_REPLACEMENT(mi, v);
+			bch2_write_super(c);
+		}
+		mutex_unlock(&c->sb_lock);
+	}
+
+	if (attr == &sysfs_label) {
+		char *tmp;
+		int ret;
+
+		tmp = kstrdup(buf, GFP_KERNEL);
+		if (!tmp)
+			return -ENOMEM;
+
+		ret = bch2_dev_group_set(c, ca, strim(tmp));
+		kfree(tmp);
+		if (ret)
+			return ret;
+	}
+
+	if (attr == &sysfs_wake_allocator)
+		bch2_wake_allocator(ca);
+
+	return size;
+}
+SYSFS_OPS(bch2_dev);
+
+struct attribute *bch2_dev_files[] = {
+	&sysfs_uuid,
+	&sysfs_bucket_size,
+	&sysfs_block_size,
+	&sysfs_first_bucket,
+	&sysfs_nbuckets,
+	&sysfs_durability,
+
+	/* settings: */
+	&sysfs_discard,
+	&sysfs_cache_replacement_policy,
+	&sysfs_state_rw,
+	&sysfs_label,
+
+	&sysfs_has_data,
+	&sysfs_iodone,
+
+	&sysfs_io_latency_read,
+	&sysfs_io_latency_write,
+	&sysfs_io_latency_stats_read,
+	&sysfs_io_latency_stats_write,
+	&sysfs_congested,
+
+	/* alloc info - other stats: */
+	&sysfs_bucket_quantiles_last_read,
+	&sysfs_bucket_quantiles_last_write,
+	&sysfs_bucket_quantiles_fragmentation,
+	&sysfs_bucket_quantiles_oldest_gen,
+
+	&sysfs_reserve_stats,
+
+	/* debug: */
+	&sysfs_alloc_debug,
+	&sysfs_wake_allocator,
+
+	sysfs_pd_controller_files(copy_gc),
+	NULL
+};
+
+#endif  /* _BCACHEFS_SYSFS_H_ */