/* SPDX-License-Identifier: GPL-2.0
 *
 * Legacy blkg rwstat helpers enabled by CONFIG_BLK_CGROUP_RWSTAT.
 * Do not use in new code.
 */
#include "blk-cgroup-rwstat.h"

int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
{
        int i, ret;

        ret = percpu_counter_init_many(rwstat->cpu_cnt, 0, gfp, BLKG_RWSTAT_NR);
        if (ret)
                return ret;

        for (i = 0; i < BLKG_RWSTAT_NR; i++)
                atomic64_set(&rwstat->aux_cnt[i], 0);
        return 0;
}
EXPORT_SYMBOL_GPL(blkg_rwstat_init);

void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
{
        percpu_counter_destroy_many(rwstat->cpu_cnt, BLKG_RWSTAT_NR);
}
EXPORT_SYMBOL_GPL(blkg_rwstat_exit);

/**
 * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
 * @sf: seq_file to print to
 * @pd: policy private data of interest
 * @rwstat: rwstat to print
 *
 * Print @rwstat to @sf for the device assocaited with @pd.
 */
u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
                         const struct blkg_rwstat_sample *rwstat)
{
        static const char *rwstr[] = {
                [BLKG_RWSTAT_READ]      = "Read",
                [BLKG_RWSTAT_WRITE]     = "Write",
                [BLKG_RWSTAT_SYNC]      = "Sync",
                [BLKG_RWSTAT_ASYNC]     = "Async",
                [BLKG_RWSTAT_DISCARD]   = "Discard",
        };
        const char *dname = blkg_dev_name(pd->blkg);
        u64 v;
        int i;

        if (!dname)
                return 0;

        for (i = 0; i < BLKG_RWSTAT_NR; i++)
                seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
                           rwstat->cnt[i]);

        v = rwstat->cnt[BLKG_RWSTAT_READ] +
                rwstat->cnt[BLKG_RWSTAT_WRITE] +
                rwstat->cnt[BLKG_RWSTAT_DISCARD];
        seq_printf(sf, "%s Total %llu\n", dname, v);
        return v;
}
EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);

/**
 * blkg_prfill_rwstat - prfill callback for blkg_rwstat
 * @sf: seq_file to print to
 * @pd: policy private data of interest
 * @off: offset to the blkg_rwstat in @pd
 *
 * prfill callback for printing a blkg_rwstat.
 */
u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
                       int off)
{
        struct blkg_rwstat_sample rwstat = { };

        blkg_rwstat_read((void *)pd + off, &rwstat);
        return __blkg_prfill_rwstat(sf, pd, &rwstat);
}
EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);

/**
 * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
 * @blkg: blkg of interest
 * @pol: blkcg_policy which contains the blkg_rwstat
 * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
 * @sum: blkg_rwstat_sample structure containing the results
 *
 * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
 * online descendants and their aux counts.  The caller must be holding the
 * queue lock for online tests.
 *
 * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it
 * is at @off bytes into @blkg's blkg_policy_data of the policy.
 */
void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
                int off, struct blkg_rwstat_sample *sum)
{
        struct blkcg_gq *pos_blkg;
        struct cgroup_subsys_state *pos_css;
        unsigned int i;

        lockdep_assert_held(&blkg->q->queue_lock);

        memset(sum, 0, sizeof(*sum));
        rcu_read_lock();
        blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
                struct blkg_rwstat *rwstat;

                if (!pos_blkg->online)
                        continue;

                if (pol)
                        rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
                else
                        rwstat = (void *)pos_blkg + off;

                for (i = 0; i < BLKG_RWSTAT_NR; i++)
                        sum->cnt[i] += blkg_rwstat_read_counter(rwstat, i);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);