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	for (i = 0; i < BLKG_RWSTAT_NR; i++) {
 13		ret = percpu_counter_init(&rwstat->cpu_cnt[i], 0, gfp);
 14		if (ret) {
 15			while (--i >= 0)
 16				percpu_counter_destroy(&rwstat->cpu_cnt[i]);
 17			return ret;
 18		}
 19		atomic64_set(&rwstat->aux_cnt[i], 0);
 20	}
 21	return 0;
 22}
 23EXPORT_SYMBOL_GPL(blkg_rwstat_init);
 24
 25void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
 26{
 27	int i;
 28
 29	for (i = 0; i < BLKG_RWSTAT_NR; i++)
 30		percpu_counter_destroy(&rwstat->cpu_cnt[i]);
 31}
 32EXPORT_SYMBOL_GPL(blkg_rwstat_exit);
 33
 34/**
 35 * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
 36 * @sf: seq_file to print to
 37 * @pd: policy private data of interest
 38 * @rwstat: rwstat to print
 39 *
 40 * Print @rwstat to @sf for the device assocaited with @pd.
 41 */
 42u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 43			 const struct blkg_rwstat_sample *rwstat)
 44{
 45	static const char *rwstr[] = {
 46		[BLKG_RWSTAT_READ]	= "Read",
 47		[BLKG_RWSTAT_WRITE]	= "Write",
 48		[BLKG_RWSTAT_SYNC]	= "Sync",
 49		[BLKG_RWSTAT_ASYNC]	= "Async",
 50		[BLKG_RWSTAT_DISCARD]	= "Discard",
 51	};
 52	const char *dname = blkg_dev_name(pd->blkg);
 53	u64 v;
 54	int i;
 55
 56	if (!dname)
 57		return 0;
 58
 59	for (i = 0; i < BLKG_RWSTAT_NR; i++)
 60		seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
 61			   rwstat->cnt[i]);
 62
 63	v = rwstat->cnt[BLKG_RWSTAT_READ] +
 64		rwstat->cnt[BLKG_RWSTAT_WRITE] +
 65		rwstat->cnt[BLKG_RWSTAT_DISCARD];
 66	seq_printf(sf, "%s Total %llu\n", dname, v);
 67	return v;
 68}
 69EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
 70
 71/**
 72 * blkg_prfill_rwstat - prfill callback for blkg_rwstat
 73 * @sf: seq_file to print to
 74 * @pd: policy private data of interest
 75 * @off: offset to the blkg_rwstat in @pd
 76 *
 77 * prfill callback for printing a blkg_rwstat.
 78 */
 79u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 80		       int off)
 81{
 82	struct blkg_rwstat_sample rwstat = { };
 83
 84	blkg_rwstat_read((void *)pd + off, &rwstat);
 85	return __blkg_prfill_rwstat(sf, pd, &rwstat);
 86}
 87EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
 88
 89/**
 90 * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
 91 * @blkg: blkg of interest
 92 * @pol: blkcg_policy which contains the blkg_rwstat
 93 * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
 94 * @sum: blkg_rwstat_sample structure containing the results
 95 *
 96 * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
 97 * online descendants and their aux counts.  The caller must be holding the
 98 * queue lock for online tests.
 99 *
100 * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it
101 * is at @off bytes into @blkg's blkg_policy_data of the policy.
102 */
103void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
104		int off, struct blkg_rwstat_sample *sum)
105{
106	struct blkcg_gq *pos_blkg;
107	struct cgroup_subsys_state *pos_css;
108	unsigned int i;
109
110	lockdep_assert_held(&blkg->q->queue_lock);
111
112	memset(sum, 0, sizeof(*sum));
113	rcu_read_lock();
114	blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
115		struct blkg_rwstat *rwstat;
116
117		if (!pos_blkg->online)
118			continue;
119
120		if (pol)
121			rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
122		else
123			rwstat = (void *)pos_blkg + off;
124
125		for (i = 0; i < BLKG_RWSTAT_NR; i++)
126			sum->cnt[i] += blkg_rwstat_read_counter(rwstat, i);
127	}
128	rcu_read_unlock();
129}
130EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);