LXR linux/block/blk-cgroup-rwstat.c

   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        rcu_read_lock();
 113        blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
 114                struct blkg_rwstat *rwstat;
 115
 116                if (!pos_blkg->online)
 117                        continue;
 118
 119                if (pol)
 120                        rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
 121                else
 122                        rwstat = (void *)pos_blkg + off;
 123
 124                for (i = 0; i < BLKG_RWSTAT_NR; i++)
 125                        sum->cnt[i] = blkg_rwstat_read_counter(rwstat, i);
 126        }
 127        rcu_read_unlock();
 128}
 129EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
 130