bcache: A block layer cache
Does writethrough and writeback caching, handles unclean shutdown, and
has a bunch of other nifty features motivated by real world usage.
See the wiki at http://bcache.evilpiepirate.org for more.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
new file mode 100644
index 0000000..5c7e770
--- /dev/null
+++ b/drivers/md/bcache/sysfs.c
@@ -0,0 +1,817 @@
+/*
+ * 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 <linux/sort.h>
+
+static const char * const cache_replacement_policies[] = {
+ "lru",
+ "fifo",
+ "random",
+ 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);
+sysfs_time_stats_attribute(try_harder, 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(sequential_merge);
+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);
+rw_attribute(writeback_rate_d_smooth);
+read_attribute(writeback_rate_debug);
+
+rw_attribute(synchronous);
+rw_attribute(journal_delay_ms);
+rw_attribute(discard);
+rw_attribute(running);
+rw_attribute(label);
+rw_attribute(readahead);
+rw_attribute(io_error_limit);
+rw_attribute(io_error_halflife);
+rw_attribute(verify);
+rw_attribute(key_merging_disabled);
+rw_attribute(gc_always_rewrite);
+rw_attribute(freelist_percent);
+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 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(writeback_metadata, "%i");
+ var_printf(writeback_running, "%i");
+ var_print(writeback_delay);
+ var_print(writeback_percent);
+ sysfs_print(writeback_rate, dc->writeback_rate.rate);
+
+ var_print(writeback_rate_update_seconds);
+ var_print(writeback_rate_d_term);
+ var_print(writeback_rate_p_term_inverse);
+ var_print(writeback_rate_d_smooth);
+
+ if (attr == &sysfs_writeback_rate_debug) {
+ char dirty[20];
+ char derivative[20];
+ char target[20];
+ hprint(dirty,
+ atomic_long_read(&dc->disk.sectors_dirty) << 9);
+ hprint(derivative, dc->writeback_rate_derivative << 9);
+ hprint(target, dc->writeback_rate_target << 9);
+
+ return sprintf(buf,
+ "rate:\t\t%u\n"
+ "change:\t\t%i\n"
+ "dirty:\t\t%s\n"
+ "derivative:\t%s\n"
+ "target:\t\t%s\n",
+ dc->writeback_rate.rate,
+ dc->writeback_rate_change,
+ dirty, derivative, target);
+ }
+
+ sysfs_hprint(dirty_data,
+ atomic_long_read(&dc->disk.sectors_dirty) << 9);
+
+ var_printf(sequential_merge, "%i");
+ 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;
+
+#define d_strtoul(var) sysfs_strtoul(var, dc->var)
+#define d_strtoi_h(var) sysfs_hatoi(var, dc->var)
+
+ sysfs_strtoul(data_csum, dc->disk.data_csum);
+ d_strtoul(verify);
+ d_strtoul(writeback_metadata);
+ d_strtoul(writeback_running);
+ d_strtoul(writeback_delay);
+ sysfs_strtoul_clamp(writeback_rate,
+ dc->writeback_rate.rate, 1, 1000000);
+ sysfs_strtoul_clamp(writeback_percent, dc->writeback_percent, 0, 40);
+
+ d_strtoul(writeback_rate_update_seconds);
+ d_strtoul(writeback_rate_d_term);
+ d_strtoul(writeback_rate_p_term_inverse);
+ sysfs_strtoul_clamp(writeback_rate_p_term_inverse,
+ dc->writeback_rate_p_term_inverse, 1, INT_MAX);
+ d_strtoul(writeback_rate_d_smooth);
+
+ d_strtoul(sequential_merge);
+ 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 = 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) {
+ memcpy(dc->sb.label, buf, SB_LABEL_SIZE);
+ 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);
+ }
+ }
+
+ if (attr == &sysfs_attach) {
+ if (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_d_smooth,
+ &sysfs_writeback_rate_debug,
+ &sysfs_dirty_data,
+ &sysfs_sequential_cutoff,
+ &sysfs_sequential_merge,
+ &sysfs_clear_stats,
+ &sysfs_running,
+ &sysfs_state,
+ &sysfs_label,
+ &sysfs_readahead,
+#ifdef CONFIG_BCACHE_DEBUG
+ &sysfs_verify,
+#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) {
+ atomic_set(&d->detaching, 1);
+ 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);
+
+SHOW(__bch_cache_set)
+{
+ unsigned 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, k, &iter, bch_ptr_bad)
+ bytes += bkey_bytes(k);
+
+ rw_unlock(false, b);
+
+ return (bytes * 100) / btree_bytes(c);
+ }
+
+ size_t 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->page_order + PAGE_SHIFT);
+
+ mutex_unlock(&c->bucket_lock);
+ return ret;
+ }
+
+ unsigned 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;
+ }
+
+ unsigned btree_used(struct cache_set *c)
+ {
+ return div64_u64(c->gc_stats.key_bytes * 100,
+ (c->gc_stats.nodes ?: 1) * btree_bytes(c));
+ }
+
+ unsigned average_key_size(struct cache_set *c)
+ {
+ return c->gc_stats.nkeys
+ ? div64_u64(c->gc_stats.data, c->gc_stats.nkeys)
+ : 0;
+ }
+
+ 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, root_usage(c));
+
+ sysfs_hprint(btree_cache_size, cache_size(c));
+ sysfs_print(btree_cache_max_chain, 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_time_stats(&c->try_harder_time, try_harder, ms, us);
+
+ sysfs_print(btree_used_percent, btree_used(c));
+ sysfs_print(btree_nodes, c->gc_stats.nodes);
+ sysfs_hprint(dirty_data, c->gc_stats.dirty);
+ sysfs_hprint(average_key_size, 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));
+
+ /* 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(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)
+ bch_queue_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.shrink(&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_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(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_dirty_data,
+
+ &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_time_stats_attribute_list(try_harder, 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,
+#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);
+
+ sysfs_print(freelist_percent, ca->free.size * 100 /
+ ((size_t) ca->sb.nbuckets));
+
+ if (attr == &sysfs_cache_replacement_policy)
+ return 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); }
+
+ /* Number of quantiles we compute */
+ const unsigned nq = 31;
+
+ size_t n = ca->sb.nbuckets, i, unused, btree;
+ uint64_t sum = 0;
+ uint16_t q[nq], *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 (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++;
+
+ btree = cached - p;
+ n -= btree;
+
+ for (i = 0; i < n; i++)
+ sum += INITIAL_PRIO - cached[i];
+
+ if (n)
+ do_div(sum, n);
+
+ for (i = 0; i < nq; i++)
+ q[i] = INITIAL_PRIO - cached[n * (i + 1) / (nq + 1)];
+
+ vfree(p);
+
+ ret = snprintf(buf, PAGE_SIZE,
+ "Unused: %zu%%\n"
+ "Metadata: %zu%%\n"
+ "Average: %llu\n"
+ "Sectors per Q: %zu\n"
+ "Quantiles: [",
+ unused * 100 / (size_t) ca->sb.nbuckets,
+ btree * 100 / (size_t) ca->sb.nbuckets, sum,
+ n * ca->sb.bucket_size / (nq + 1));
+
+ for (i = 0; i < nq && ret < (ssize_t) PAGE_SIZE; i++)
+ ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ i < nq - 1 ? "%u " : "%u]\n", q[i]);
+
+ buf[PAGE_SIZE - 1] = '\0';
+ 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 = 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_freelist_percent) {
+ DECLARE_FIFO(long, free);
+ long i;
+ size_t p = strtoul_or_return(buf);
+
+ p = clamp_t(size_t,
+ ((size_t) ca->sb.nbuckets * p) / 100,
+ roundup_pow_of_two(ca->sb.nbuckets) >> 9,
+ ca->sb.nbuckets / 2);
+
+ if (!init_fifo_exact(&free, p, GFP_KERNEL))
+ return -ENOMEM;
+
+ mutex_lock(&ca->set->bucket_lock);
+
+ fifo_move(&free, &ca->free);
+ fifo_swap(&free, &ca->free);
+
+ mutex_unlock(&ca->set->bucket_lock);
+
+ while (fifo_pop(&free, i))
+ atomic_dec(&ca->buckets[i].pin);
+
+ free_fifo(&free);
+ }
+
+ 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_freelist_percent,
+ &sysfs_cache_replacement_policy,
+ NULL
+};
+KTYPE(bch_cache);