1/* SPDX-License-Identifier: GPL-2.0
  2 *
  3 * Legacy blkg rwstat helpers enabled by CONFIG_BLK_CGROUP_RWSTAT.
  4 * Do not use in new code.
  5 */
  6#include "blk-cgroup-rwstat.h"
  7
  8int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
  9{
 10	int i, ret;
 11
 12	ret = percpu_counter_init_many(rwstat->cpu_cnt, 0, gfp, BLKG_RWSTAT_NR);
 13	if (ret)
 14		return ret;
 15
 16	for (i = 0; i < BLKG_RWSTAT_NR; i++)
 17		atomic64_set(&rwstat->aux_cnt[i], 0);
 18	return 0;
 19}
 20EXPORT_SYMBOL_GPL(blkg_rwstat_init);
 21
 22void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
 23{
 24	percpu_counter_destroy_many(rwstat->cpu_cnt, BLKG_RWSTAT_NR);
 25}
 26EXPORT_SYMBOL_GPL(blkg_rwstat_exit);
 27
 28/**
 29 * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
 30 * @sf: seq_file to print to
 31 * @pd: policy private data of interest
 32 * @rwstat: rwstat to print
 33 *
 34 * Print @rwstat to @sf for the device assocaited with @pd.
 35 */
 36u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 37			 const struct blkg_rwstat_sample *rwstat)
 38{
 39	static const char *rwstr[] = {
 40		[BLKG_RWSTAT_READ]	= "Read",
 41		[BLKG_RWSTAT_WRITE]	= "Write",
 42		[BLKG_RWSTAT_SYNC]	= "Sync",
 43		[BLKG_RWSTAT_ASYNC]	= "Async",
 44		[BLKG_RWSTAT_DISCARD]	= "Discard",
 45	};
 46	const char *dname = blkg_dev_name(pd->blkg);
 47	u64 v;
 48	int i;
 49
 50	if (!dname)
 51		return 0;
 52
 53	for (i = 0; i < BLKG_RWSTAT_NR; i++)
 54		seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
 55			   rwstat->cnt[i]);
 56
 57	v = rwstat->cnt[BLKG_RWSTAT_READ] +
 58		rwstat->cnt[BLKG_RWSTAT_WRITE] +
 59		rwstat->cnt[BLKG_RWSTAT_DISCARD];
 60	seq_printf(sf, "%s Total %llu\n", dname, v);
 61	return v;
 62}
 63EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
 64
 65/**
 66 * blkg_prfill_rwstat - prfill callback for blkg_rwstat
 67 * @sf: seq_file to print to
 68 * @pd: policy private data of interest
 69 * @off: offset to the blkg_rwstat in @pd
 70 *
 71 * prfill callback for printing a blkg_rwstat.
 72 */
 73u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 74		       int off)
 75{
 76	struct blkg_rwstat_sample rwstat = { };
 77
 78	blkg_rwstat_read((void *)pd + off, &rwstat);
 79	return __blkg_prfill_rwstat(sf, pd, &rwstat);
 80}
 81EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
 82
 83/**
 84 * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
 85 * @blkg: blkg of interest
 86 * @pol: blkcg_policy which contains the blkg_rwstat
 87 * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
 88 * @sum: blkg_rwstat_sample structure containing the results
 89 *
 90 * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
 91 * online descendants and their aux counts.  The caller must be holding the
 92 * queue lock for online tests.
 93 *
 94 * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it
 95 * is at @off bytes into @blkg's blkg_policy_data of the policy.
 96 */
 97void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
 98		int off, struct blkg_rwstat_sample *sum)
 99{
100	struct blkcg_gq *pos_blkg;
101	struct cgroup_subsys_state *pos_css;
102	unsigned int i;
103
104	lockdep_assert_held(&blkg->q->queue_lock);
105
106	memset(sum, 0, sizeof(*sum));
107	rcu_read_lock();
108	blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
109		struct blkg_rwstat *rwstat;
110
111		if (!pos_blkg->online)
112			continue;
113
114		if (pol)
115			rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
116		else
117			rwstat = (void *)pos_blkg + off;
118
119		for (i = 0; i < BLKG_RWSTAT_NR; i++)
120			sum->cnt[i] += blkg_rwstat_read_counter(rwstat, i);
121	}
122	rcu_read_unlock();
123}
124EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);