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         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 }
  23 EXPORT_SYMBOL_GPL(blkg_rwstat_init);
  24
  25 void 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 }
  32 EXPORT_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  */
  42 u64 __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 }
  69 EXPORT_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  */
  79 u64 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 }
  87 EXPORT_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  */
 103 void 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 }
 130 EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);