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
   8 int 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 }
  20 EXPORT_SYMBOL_GPL(blkg_rwstat_init);
  21
  22 void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
  23 {
  24         percpu_counter_destroy_many(rwstat->cpu_cnt, BLKG_RWSTAT_NR);
  25 }
  26 EXPORT_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  */
  36 u64 __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 }
  63 EXPORT_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  */
  73 u64 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 }
  81 EXPORT_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  */
  97 void 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 }
 124 EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);