doc: Update rcu_assign_pointer() definition in whatisRCU.txt

[linux/fpc-iii.git] / drivers / md / bcache / sysfs.c

/*
 * bcache sysfs interfaces
 *
 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
 * Copyright 2012 Google, Inc.
 */

#include "bcache.h"
#include "sysfs.h"
#include "btree.h"
#include "request.h"
#include "writeback.h"

#include <linux/blkdev.h>
#include <linux/sort.h>
#include <linux/sched/clock.h>

static const char * const cache_replacement_policies[] = {
        "lru",
        "fifo",
        "random",
        NULL
};

static const char * const error_actions[] = {
        "unregister",
        "panic",
        NULL
};

write_attribute(attach);
write_attribute(detach);
write_attribute(unregister);
write_attribute(stop);
write_attribute(clear_stats);
write_attribute(trigger_gc);
write_attribute(prune_cache);
write_attribute(flash_vol_create);

read_attribute(bucket_size);
read_attribute(block_size);
read_attribute(nbuckets);
read_attribute(tree_depth);
read_attribute(root_usage_percent);
read_attribute(priority_stats);
read_attribute(btree_cache_size);
read_attribute(btree_cache_max_chain);
read_attribute(cache_available_percent);
read_attribute(written);
read_attribute(btree_written);
read_attribute(metadata_written);
read_attribute(active_journal_entries);

sysfs_time_stats_attribute(btree_gc,    sec, ms);
sysfs_time_stats_attribute(btree_split, sec, us);
sysfs_time_stats_attribute(btree_sort,  ms,  us);
sysfs_time_stats_attribute(btree_read,  ms,  us);

read_attribute(btree_nodes);
read_attribute(btree_used_percent);
read_attribute(average_key_size);
read_attribute(dirty_data);
read_attribute(bset_tree_stats);

read_attribute(state);
read_attribute(cache_read_races);
read_attribute(writeback_keys_done);
read_attribute(writeback_keys_failed);
read_attribute(io_errors);
read_attribute(congested);
rw_attribute(congested_read_threshold_us);
rw_attribute(congested_write_threshold_us);

rw_attribute(sequential_cutoff);
rw_attribute(data_csum);
rw_attribute(cache_mode);
rw_attribute(writeback_metadata);
rw_attribute(writeback_running);
rw_attribute(writeback_percent);
rw_attribute(writeback_delay);
rw_attribute(writeback_rate);

rw_attribute(writeback_rate_update_seconds);
rw_attribute(writeback_rate_d_term);
rw_attribute(writeback_rate_p_term_inverse);
read_attribute(writeback_rate_debug);

read_attribute(stripe_size);
read_attribute(partial_stripes_expensive);

rw_attribute(synchronous);
rw_attribute(journal_delay_ms);
rw_attribute(discard);
rw_attribute(running);
rw_attribute(label);
rw_attribute(readahead);
rw_attribute(errors);
rw_attribute(io_error_limit);
rw_attribute(io_error_halflife);
rw_attribute(verify);
rw_attribute(bypass_torture_test);
rw_attribute(key_merging_disabled);
rw_attribute(gc_always_rewrite);
rw_attribute(expensive_debug_checks);
rw_attribute(cache_replacement_policy);
rw_attribute(btree_shrinker_disabled);
rw_attribute(copy_gc_enabled);
rw_attribute(size);

SHOW(__bch_cached_dev)
{
        struct cached_dev *dc = container_of(kobj, struct cached_dev,
                                             disk.kobj);
        const char *states[] = { "no cache", "clean", "dirty", "inconsistent" };

#define var(stat)               (dc->stat)

        if (attr == &sysfs_cache_mode)
                return bch_snprint_string_list(buf, PAGE_SIZE,
                                               bch_cache_modes + 1,
                                               BDEV_CACHE_MODE(&dc->sb));

        sysfs_printf(data_csum,         "%i", dc->disk.data_csum);
        var_printf(verify,              "%i");
        var_printf(bypass_torture_test, "%i");
        var_printf(writeback_metadata,  "%i");
        var_printf(writeback_running,   "%i");
        var_print(writeback_delay);
        var_print(writeback_percent);
        sysfs_hprint(writeback_rate,    dc->writeback_rate.rate << 9);

        var_print(writeback_rate_update_seconds);
        var_print(writeback_rate_d_term);
        var_print(writeback_rate_p_term_inverse);

        if (attr == &sysfs_writeback_rate_debug) {
                char rate[20];
                char dirty[20];
                char target[20];
                char proportional[20];
                char derivative[20];
                char change[20];
                s64 next_io;

                bch_hprint(rate,        dc->writeback_rate.rate << 9);
                bch_hprint(dirty,       bcache_dev_sectors_dirty(&dc->disk) << 9);
                bch_hprint(target,      dc->writeback_rate_target << 9);
                bch_hprint(proportional,dc->writeback_rate_proportional << 9);
                bch_hprint(derivative,  dc->writeback_rate_derivative << 9);
                bch_hprint(change,      dc->writeback_rate_change << 9);

                next_io = div64_s64(dc->writeback_rate.next - local_clock(),
                                    NSEC_PER_MSEC);

                return sprintf(buf,
                               "rate:\t\t%s/sec\n"
                               "dirty:\t\t%s\n"
                               "target:\t\t%s\n"
                               "proportional:\t%s\n"
                               "derivative:\t%s\n"
                               "change:\t\t%s/sec\n"
                               "next io:\t%llims\n",
                               rate, dirty, target, proportional,
                               derivative, change, next_io);
        }

        sysfs_hprint(dirty_data,
                     bcache_dev_sectors_dirty(&dc->disk) << 9);

        sysfs_hprint(stripe_size,       dc->disk.stripe_size << 9);
        var_printf(partial_stripes_expensive,   "%u");

        var_hprint(sequential_cutoff);
        var_hprint(readahead);

        sysfs_print(running,            atomic_read(&dc->running));
        sysfs_print(state,              states[BDEV_STATE(&dc->sb)]);

        if (attr == &sysfs_label) {
                memcpy(buf, dc->sb.label, SB_LABEL_SIZE);
                buf[SB_LABEL_SIZE + 1] = '\0';
                strcat(buf, "\n");
                return strlen(buf);
        }

#undef var
        return 0;
}
SHOW_LOCKED(bch_cached_dev)

STORE(__cached_dev)
{
        struct cached_dev *dc = container_of(kobj, struct cached_dev,
                                             disk.kobj);
        unsigned v = size;
        struct cache_set *c;
        struct kobj_uevent_env *env;

#define d_strtoul(var)          sysfs_strtoul(var, dc->var)
#define d_strtoul_nonzero(var)  sysfs_strtoul_clamp(var, dc->var, 1, INT_MAX)
#define d_strtoi_h(var)         sysfs_hatoi(var, dc->var)

        sysfs_strtoul(data_csum,        dc->disk.data_csum);
        d_strtoul(verify);
        d_strtoul(bypass_torture_test);
        d_strtoul(writeback_metadata);
        d_strtoul(writeback_running);
        d_strtoul(writeback_delay);

        sysfs_strtoul_clamp(writeback_percent, dc->writeback_percent, 0, 40);

        sysfs_strtoul_clamp(writeback_rate,
                            dc->writeback_rate.rate, 1, INT_MAX);

        d_strtoul_nonzero(writeback_rate_update_seconds);
        d_strtoul(writeback_rate_d_term);
        d_strtoul_nonzero(writeback_rate_p_term_inverse);

        d_strtoi_h(sequential_cutoff);
        d_strtoi_h(readahead);

        if (attr == &sysfs_clear_stats)
                bch_cache_accounting_clear(&dc->accounting);

        if (attr == &sysfs_running &&
            strtoul_or_return(buf))
                bch_cached_dev_run(dc);

        if (attr == &sysfs_cache_mode) {
                ssize_t v = bch_read_string_list(buf, bch_cache_modes + 1);

                if (v < 0)
                        return v;

                if ((unsigned) v != BDEV_CACHE_MODE(&dc->sb)) {
                        SET_BDEV_CACHE_MODE(&dc->sb, v);
                        bch_write_bdev_super(dc, NULL);
                }
        }

        if (attr == &sysfs_label) {
                if (size > SB_LABEL_SIZE)
                        return -EINVAL;
                memcpy(dc->sb.label, buf, size);
                if (size < SB_LABEL_SIZE)
                        dc->sb.label[size] = '\0';
                if (size && dc->sb.label[size - 1] == '\n')
                        dc->sb.label[size - 1] = '\0';
                bch_write_bdev_super(dc, NULL);
                if (dc->disk.c) {
                        memcpy(dc->disk.c->uuids[dc->disk.id].label,
                               buf, SB_LABEL_SIZE);
                        bch_uuid_write(dc->disk.c);
                }
                env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
                if (!env)
                        return -ENOMEM;
                add_uevent_var(env, "DRIVER=bcache");
                add_uevent_var(env, "CACHED_UUID=%pU", dc->sb.uuid),
                add_uevent_var(env, "CACHED_LABEL=%s", buf);
                kobject_uevent_env(
                        &disk_to_dev(dc->disk.disk)->kobj, KOBJ_CHANGE, env->envp);
                kfree(env);
        }

        if (attr == &sysfs_attach) {
                if (bch_parse_uuid(buf, dc->sb.set_uuid) < 16)
                        return -EINVAL;

                list_for_each_entry(c, &bch_cache_sets, list) {
                        v = bch_cached_dev_attach(dc, c);
                        if (!v)
                                return size;
                }

                pr_err("Can't attach %s: cache set not found", buf);
                size = v;
        }

        if (attr == &sysfs_detach && dc->disk.c)
                bch_cached_dev_detach(dc);

        if (attr == &sysfs_stop)
                bcache_device_stop(&dc->disk);

        return size;
}

STORE(bch_cached_dev)
{
        struct cached_dev *dc = container_of(kobj, struct cached_dev,
                                             disk.kobj);

        mutex_lock(&bch_register_lock);
        size = __cached_dev_store(kobj, attr, buf, size);

        if (attr == &sysfs_writeback_running)
                bch_writeback_queue(dc);

        if (attr == &sysfs_writeback_percent)
                schedule_delayed_work(&dc->writeback_rate_update,
                                      dc->writeback_rate_update_seconds * HZ);

        mutex_unlock(&bch_register_lock);
        return size;
}

static struct attribute *bch_cached_dev_files[] = {
        &sysfs_attach,
        &sysfs_detach,
        &sysfs_stop,
#if 0
        &sysfs_data_csum,
#endif
        &sysfs_cache_mode,
        &sysfs_writeback_metadata,
        &sysfs_writeback_running,
        &sysfs_writeback_delay,
        &sysfs_writeback_percent,
        &sysfs_writeback_rate,
        &sysfs_writeback_rate_update_seconds,
        &sysfs_writeback_rate_d_term,
        &sysfs_writeback_rate_p_term_inverse,
        &sysfs_writeback_rate_debug,
        &sysfs_dirty_data,
        &sysfs_stripe_size,
        &sysfs_partial_stripes_expensive,
        &sysfs_sequential_cutoff,
        &sysfs_clear_stats,
        &sysfs_running,
        &sysfs_state,
        &sysfs_label,
        &sysfs_readahead,
#ifdef CONFIG_BCACHE_DEBUG
        &sysfs_verify,
        &sysfs_bypass_torture_test,
#endif
        NULL
};
KTYPE(bch_cached_dev);

SHOW(bch_flash_dev)
{
        struct bcache_device *d = container_of(kobj, struct bcache_device,
                                               kobj);
        struct uuid_entry *u = &d->c->uuids[d->id];

        sysfs_printf(data_csum, "%i", d->data_csum);
        sysfs_hprint(size,      u->sectors << 9);

        if (attr == &sysfs_label) {
                memcpy(buf, u->label, SB_LABEL_SIZE);
                buf[SB_LABEL_SIZE + 1] = '\0';
                strcat(buf, "\n");
                return strlen(buf);
        }

        return 0;
}

STORE(__bch_flash_dev)
{
        struct bcache_device *d = container_of(kobj, struct bcache_device,
                                               kobj);
        struct uuid_entry *u = &d->c->uuids[d->id];

        sysfs_strtoul(data_csum,        d->data_csum);

        if (attr == &sysfs_size) {
                uint64_t v;
                strtoi_h_or_return(buf, v);

                u->sectors = v >> 9;
                bch_uuid_write(d->c);
                set_capacity(d->disk, u->sectors);
        }

        if (attr == &sysfs_label) {
                memcpy(u->label, buf, SB_LABEL_SIZE);
                bch_uuid_write(d->c);
        }

        if (attr == &sysfs_unregister) {
                set_bit(BCACHE_DEV_DETACHING, &d->flags);
                bcache_device_stop(d);
        }

        return size;
}
STORE_LOCKED(bch_flash_dev)

static struct attribute *bch_flash_dev_files[] = {
        &sysfs_unregister,
#if 0
        &sysfs_data_csum,
#endif
        &sysfs_label,
        &sysfs_size,
        NULL
};
KTYPE(bch_flash_dev);

struct bset_stats_op {
        struct btree_op op;
        size_t nodes;
        struct bset_stats stats;
};

static int bch_btree_bset_stats(struct btree_op *b_op, struct btree *b)
{
        struct bset_stats_op *op = container_of(b_op, struct bset_stats_op, op);

        op->nodes++;
        bch_btree_keys_stats(&b->keys, &op->stats);

        return MAP_CONTINUE;
}

static int bch_bset_print_stats(struct cache_set *c, char *buf)
{
        struct bset_stats_op op;
        int ret;

        memset(&op, 0, sizeof(op));
        bch_btree_op_init(&op.op, -1);

        ret = bch_btree_map_nodes(&op.op, c, &ZERO_KEY, bch_btree_bset_stats);
        if (ret < 0)
                return ret;

        return snprintf(buf, PAGE_SIZE,
                        "btree nodes:           %zu\n"
                        "written sets:          %zu\n"
                        "unwritten sets:                %zu\n"
                        "written key bytes:     %zu\n"
                        "unwritten key bytes:   %zu\n"
                        "floats:                        %zu\n"
                        "failed:                        %zu\n",
                        op.nodes,
                        op.stats.sets_written, op.stats.sets_unwritten,
                        op.stats.bytes_written, op.stats.bytes_unwritten,
                        op.stats.floats, op.stats.failed);
}

static unsigned bch_root_usage(struct cache_set *c)
{
        unsigned bytes = 0;
        struct bkey *k;
        struct btree *b;
        struct btree_iter iter;

        goto lock_root;

        do {
                rw_unlock(false, b);
lock_root:
                b = c->root;
                rw_lock(false, b, b->level);
        } while (b != c->root);

        for_each_key_filter(&b->keys, k, &iter, bch_ptr_bad)
                bytes += bkey_bytes(k);

        rw_unlock(false, b);

        return (bytes * 100) / btree_bytes(c);
}

static size_t bch_cache_size(struct cache_set *c)
{
        size_t ret = 0;
        struct btree *b;

        mutex_lock(&c->bucket_lock);
        list_for_each_entry(b, &c->btree_cache, list)
                ret += 1 << (b->keys.page_order + PAGE_SHIFT);

        mutex_unlock(&c->bucket_lock);
        return ret;
}

static unsigned bch_cache_max_chain(struct cache_set *c)
{
        unsigned ret = 0;
        struct hlist_head *h;

        mutex_lock(&c->bucket_lock);

        for (h = c->bucket_hash;
             h < c->bucket_hash + (1 << BUCKET_HASH_BITS);
             h++) {
                unsigned i = 0;
                struct hlist_node *p;

                hlist_for_each(p, h)
                        i++;

                ret = max(ret, i);
        }

        mutex_unlock(&c->bucket_lock);
        return ret;
}

static unsigned bch_btree_used(struct cache_set *c)
{
        return div64_u64(c->gc_stats.key_bytes * 100,
                         (c->gc_stats.nodes ?: 1) * btree_bytes(c));
}

static unsigned bch_average_key_size(struct cache_set *c)
{
        return c->gc_stats.nkeys
                ? div64_u64(c->gc_stats.data, c->gc_stats.nkeys)
                : 0;
}

SHOW(__bch_cache_set)
{
        struct cache_set *c = container_of(kobj, struct cache_set, kobj);

        sysfs_print(synchronous,                CACHE_SYNC(&c->sb));
        sysfs_print(journal_delay_ms,           c->journal_delay_ms);
        sysfs_hprint(bucket_size,               bucket_bytes(c));
        sysfs_hprint(block_size,                block_bytes(c));
        sysfs_print(tree_depth,                 c->root->level);
        sysfs_print(root_usage_percent,         bch_root_usage(c));

        sysfs_hprint(btree_cache_size,          bch_cache_size(c));
        sysfs_print(btree_cache_max_chain,      bch_cache_max_chain(c));
        sysfs_print(cache_available_percent,    100 - c->gc_stats.in_use);

        sysfs_print_time_stats(&c->btree_gc_time,       btree_gc, sec, ms);
        sysfs_print_time_stats(&c->btree_split_time,    btree_split, sec, us);
        sysfs_print_time_stats(&c->sort.time,           btree_sort, ms, us);
        sysfs_print_time_stats(&c->btree_read_time,     btree_read, ms, us);

        sysfs_print(btree_used_percent, bch_btree_used(c));
        sysfs_print(btree_nodes,        c->gc_stats.nodes);
        sysfs_hprint(average_key_size,  bch_average_key_size(c));

        sysfs_print(cache_read_races,
                    atomic_long_read(&c->cache_read_races));

        sysfs_print(writeback_keys_done,
                    atomic_long_read(&c->writeback_keys_done));
        sysfs_print(writeback_keys_failed,
                    atomic_long_read(&c->writeback_keys_failed));

        if (attr == &sysfs_errors)
                return bch_snprint_string_list(buf, PAGE_SIZE, error_actions,
                                               c->on_error);

        /* See count_io_errors for why 88 */
        sysfs_print(io_error_halflife,  c->error_decay * 88);
        sysfs_print(io_error_limit,     c->error_limit >> IO_ERROR_SHIFT);

        sysfs_hprint(congested,
                     ((uint64_t) bch_get_congested(c)) << 9);
        sysfs_print(congested_read_threshold_us,
                    c->congested_read_threshold_us);
        sysfs_print(congested_write_threshold_us,
                    c->congested_write_threshold_us);

        sysfs_print(active_journal_entries,     fifo_used(&c->journal.pin));
        sysfs_printf(verify,                    "%i", c->verify);
        sysfs_printf(key_merging_disabled,      "%i", c->key_merging_disabled);
        sysfs_printf(expensive_debug_checks,
                     "%i", c->expensive_debug_checks);
        sysfs_printf(gc_always_rewrite,         "%i", c->gc_always_rewrite);
        sysfs_printf(btree_shrinker_disabled,   "%i", c->shrinker_disabled);
        sysfs_printf(copy_gc_enabled,           "%i", c->copy_gc_enabled);

        if (attr == &sysfs_bset_tree_stats)
                return bch_bset_print_stats(c, buf);

        return 0;
}
SHOW_LOCKED(bch_cache_set)

STORE(__bch_cache_set)
{
        struct cache_set *c = container_of(kobj, struct cache_set, kobj);

        if (attr == &sysfs_unregister)
                bch_cache_set_unregister(c);

        if (attr == &sysfs_stop)
                bch_cache_set_stop(c);

        if (attr == &sysfs_synchronous) {
                bool sync = strtoul_or_return(buf);

                if (sync != CACHE_SYNC(&c->sb)) {
                        SET_CACHE_SYNC(&c->sb, sync);
                        bcache_write_super(c);
                }
        }

        if (attr == &sysfs_flash_vol_create) {
                int r;
                uint64_t v;
                strtoi_h_or_return(buf, v);

                r = bch_flash_dev_create(c, v);
                if (r)
                        return r;
        }

        if (attr == &sysfs_clear_stats) {
                atomic_long_set(&c->writeback_keys_done,        0);
                atomic_long_set(&c->writeback_keys_failed,      0);

                memset(&c->gc_stats, 0, sizeof(struct gc_stat));
                bch_cache_accounting_clear(&c->accounting);
        }

        if (attr == &sysfs_trigger_gc)
                wake_up_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->shrink.scan_objects(&c->shrink, &sc);
        }

        sysfs_strtoul(congested_read_threshold_us,
                      c->congested_read_threshold_us);
        sysfs_strtoul(congested_write_threshold_us,
                      c->congested_write_threshold_us);

        if (attr == &sysfs_errors) {
                ssize_t v = bch_read_string_list(buf, error_actions);

                if (v < 0)
                        return v;

                c->on_error = v;
        }

        if (attr == &sysfs_io_error_limit)
                c->error_limit = strtoul_or_return(buf) << IO_ERROR_SHIFT;

        /* See count_io_errors() for why 88 */
        if (attr == &sysfs_io_error_halflife)
                c->error_decay = strtoul_or_return(buf) / 88;

        sysfs_strtoul(journal_delay_ms,         c->journal_delay_ms);
        sysfs_strtoul(verify,                   c->verify);
        sysfs_strtoul(key_merging_disabled,     c->key_merging_disabled);
        sysfs_strtoul(expensive_debug_checks,   c->expensive_debug_checks);
        sysfs_strtoul(gc_always_rewrite,        c->gc_always_rewrite);
        sysfs_strtoul(btree_shrinker_disabled,  c->shrinker_disabled);
        sysfs_strtoul(copy_gc_enabled,          c->copy_gc_enabled);

        return size;
}
STORE_LOCKED(bch_cache_set)

SHOW(bch_cache_set_internal)
{
        struct cache_set *c = container_of(kobj, struct cache_set, internal);
        return bch_cache_set_show(&c->kobj, attr, buf);
}

STORE(bch_cache_set_internal)
{
        struct cache_set *c = container_of(kobj, struct cache_set, internal);
        return bch_cache_set_store(&c->kobj, attr, buf, size);
}

static void bch_cache_set_internal_release(struct kobject *k)
{
}

static struct attribute *bch_cache_set_files[] = {
        &sysfs_unregister,
        &sysfs_stop,
        &sysfs_synchronous,
        &sysfs_journal_delay_ms,
        &sysfs_flash_vol_create,

        &sysfs_bucket_size,
        &sysfs_block_size,
        &sysfs_tree_depth,
        &sysfs_root_usage_percent,
        &sysfs_btree_cache_size,
        &sysfs_cache_available_percent,

        &sysfs_average_key_size,

        &sysfs_errors,
        &sysfs_io_error_limit,
        &sysfs_io_error_halflife,
        &sysfs_congested,
        &sysfs_congested_read_threshold_us,
        &sysfs_congested_write_threshold_us,
        &sysfs_clear_stats,
        NULL
};
KTYPE(bch_cache_set);

static struct attribute *bch_cache_set_internal_files[] = {
        &sysfs_active_journal_entries,

        sysfs_time_stats_attribute_list(btree_gc, sec, ms)
        sysfs_time_stats_attribute_list(btree_split, sec, us)
        sysfs_time_stats_attribute_list(btree_sort, ms, us)
        sysfs_time_stats_attribute_list(btree_read, ms, us)

        &sysfs_btree_nodes,
        &sysfs_btree_used_percent,
        &sysfs_btree_cache_max_chain,

        &sysfs_bset_tree_stats,
        &sysfs_cache_read_races,
        &sysfs_writeback_keys_done,
        &sysfs_writeback_keys_failed,

        &sysfs_trigger_gc,
        &sysfs_prune_cache,
#ifdef CONFIG_BCACHE_DEBUG
        &sysfs_verify,
        &sysfs_key_merging_disabled,
        &sysfs_expensive_debug_checks,
#endif
        &sysfs_gc_always_rewrite,
        &sysfs_btree_shrinker_disabled,
        &sysfs_copy_gc_enabled,
        NULL
};
KTYPE(bch_cache_set_internal);

SHOW(__bch_cache)
{
        struct cache *ca = container_of(kobj, struct cache, kobj);

        sysfs_hprint(bucket_size,       bucket_bytes(ca));
        sysfs_hprint(block_size,        block_bytes(ca));
        sysfs_print(nbuckets,           ca->sb.nbuckets);
        sysfs_print(discard,            ca->discard);
        sysfs_hprint(written, atomic_long_read(&ca->sectors_written) << 9);
        sysfs_hprint(btree_written,
                     atomic_long_read(&ca->btree_sectors_written) << 9);
        sysfs_hprint(metadata_written,
                     (atomic_long_read(&ca->meta_sectors_written) +
                      atomic_long_read(&ca->btree_sectors_written)) << 9);

        sysfs_print(io_errors,
                    atomic_read(&ca->io_errors) >> IO_ERROR_SHIFT);

        if (attr == &sysfs_cache_replacement_policy)
                return bch_snprint_string_list(buf, PAGE_SIZE,
                                               cache_replacement_policies,
                                               CACHE_REPLACEMENT(&ca->sb));

        if (attr == &sysfs_priority_stats) {
                int cmp(const void *l, const void *r)
                {       return *((uint16_t *) r) - *((uint16_t *) l); }

                struct bucket *b;
                size_t n = ca->sb.nbuckets, i;
                size_t unused = 0, available = 0, dirty = 0, meta = 0;
                uint64_t sum = 0;
                /* Compute 31 quantiles */
                uint16_t q[31], *p, *cached;
                ssize_t ret;

                cached = p = vmalloc(ca->sb.nbuckets * sizeof(uint16_t));
                if (!p)
                        return -ENOMEM;

                mutex_lock(&ca->set->bucket_lock);
                for_each_bucket(b, ca) {
                        if (!GC_SECTORS_USED(b))
                                unused++;
                        if (GC_MARK(b) == GC_MARK_RECLAIMABLE)
                                available++;
                        if (GC_MARK(b) == GC_MARK_DIRTY)
                                dirty++;
                        if (GC_MARK(b) == GC_MARK_METADATA)
                                meta++;
                }

                for (i = ca->sb.first_bucket; i < n; i++)
                        p[i] = ca->buckets[i].prio;
                mutex_unlock(&ca->set->bucket_lock);

                sort(p, n, sizeof(uint16_t), cmp, NULL);

                while (n &&
                       !cached[n - 1])
                        --n;

                unused = ca->sb.nbuckets - n;

                while (cached < p + n &&
                       *cached == BTREE_PRIO)
                        cached++, n--;

                for (i = 0; i < n; i++)
                        sum += INITIAL_PRIO - cached[i];

                if (n)
                        do_div(sum, n);

                for (i = 0; i < ARRAY_SIZE(q); i++)
                        q[i] = INITIAL_PRIO - cached[n * (i + 1) /
                                (ARRAY_SIZE(q) + 1)];

                vfree(p);

                ret = scnprintf(buf, PAGE_SIZE,
                                "Unused:                %zu%%\n"
                                "Clean:         %zu%%\n"
                                "Dirty:         %zu%%\n"
                                "Metadata:      %zu%%\n"
                                "Average:       %llu\n"
                                "Sectors per Q: %zu\n"
                                "Quantiles:     [",
                                unused * 100 / (size_t) ca->sb.nbuckets,
                                available * 100 / (size_t) ca->sb.nbuckets,
                                dirty * 100 / (size_t) ca->sb.nbuckets,
                                meta * 100 / (size_t) ca->sb.nbuckets, sum,
                                n * ca->sb.bucket_size / (ARRAY_SIZE(q) + 1));

                for (i = 0; i < ARRAY_SIZE(q); i++)
                        ret += scnprintf(buf + ret, PAGE_SIZE - ret,
                                         "%u ", q[i]);
                ret--;

                ret += scnprintf(buf + ret, PAGE_SIZE - ret, "]\n");

                return ret;
        }

        return 0;
}
SHOW_LOCKED(bch_cache)

STORE(__bch_cache)
{
        struct cache *ca = container_of(kobj, struct cache, kobj);

        if (attr == &sysfs_discard) {
                bool v = strtoul_or_return(buf);

                if (blk_queue_discard(bdev_get_queue(ca->bdev)))
                        ca->discard = v;

                if (v != CACHE_DISCARD(&ca->sb)) {
                        SET_CACHE_DISCARD(&ca->sb, v);
                        bcache_write_super(ca->set);
                }
        }

        if (attr == &sysfs_cache_replacement_policy) {
                ssize_t v = bch_read_string_list(buf, cache_replacement_policies);

                if (v < 0)
                        return v;

                if ((unsigned) v != CACHE_REPLACEMENT(&ca->sb)) {
                        mutex_lock(&ca->set->bucket_lock);
                        SET_CACHE_REPLACEMENT(&ca->sb, v);
                        mutex_unlock(&ca->set->bucket_lock);

                        bcache_write_super(ca->set);
                }
        }

        if (attr == &sysfs_clear_stats) {
                atomic_long_set(&ca->sectors_written, 0);
                atomic_long_set(&ca->btree_sectors_written, 0);
                atomic_long_set(&ca->meta_sectors_written, 0);
                atomic_set(&ca->io_count, 0);
                atomic_set(&ca->io_errors, 0);
        }

        return size;
}
STORE_LOCKED(bch_cache)

static struct attribute *bch_cache_files[] = {
        &sysfs_bucket_size,
        &sysfs_block_size,
        &sysfs_nbuckets,
        &sysfs_priority_stats,
        &sysfs_discard,
        &sysfs_written,
        &sysfs_btree_written,
        &sysfs_metadata_written,
        &sysfs_io_errors,
        &sysfs_clear_stats,
        &sysfs_cache_replacement_policy,
        NULL
};
KTYPE(bch_cache);