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56cc24f59c
With previous modification to delay freeing policy data after an RCU grace period, prfill() can run under RCU instead of taking queue_lock. However, policy teardown can still clear blkg->pd[plid] after blkcg_print_blkgs() observes the policy enabled bit. Load policy data once with READ_ONCE() and skip the blkg if teardown already cleared it. Do the same in recursive stat walks for descendant blkgs. Remove the stale BFQ debug queue_lock assertion because blkcg_print_blkgs() no longer calls prfill() with queue_lock held. This also lets ioc_qos_prfill() and ioc_cost_model_prfill() use IRQ-safe ioc->lock locking without re-enabling IRQs while queue_lock is still held. Signed-off-by: Yu Kuai <yukuai@fygo.io> Link: https://patch.msgid.link/db7633d5e263dd1c2bf9b901762545a84b7d714e.1780621988.git.yukuai@fygo.io Signed-off-by: Jens Axboe <axboe@kernel.dk>
128 lines
3.3 KiB
C
128 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0
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*
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* Legacy blkg rwstat helpers enabled by CONFIG_BLK_CGROUP_RWSTAT.
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* Do not use in new code.
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*/
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#include "blk-cgroup-rwstat.h"
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int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
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{
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int i, ret;
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ret = percpu_counter_init_many(rwstat->cpu_cnt, 0, gfp, BLKG_RWSTAT_NR);
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if (ret)
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return ret;
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for (i = 0; i < BLKG_RWSTAT_NR; i++)
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atomic64_set(&rwstat->aux_cnt[i], 0);
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return 0;
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}
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EXPORT_SYMBOL_GPL(blkg_rwstat_init);
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void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
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{
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percpu_counter_destroy_many(rwstat->cpu_cnt, BLKG_RWSTAT_NR);
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}
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EXPORT_SYMBOL_GPL(blkg_rwstat_exit);
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/**
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* __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
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* @sf: seq_file to print to
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* @pd: policy private data of interest
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* @rwstat: rwstat to print
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*
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* Print @rwstat to @sf for the device assocaited with @pd.
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*/
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u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
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const struct blkg_rwstat_sample *rwstat)
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{
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static const char *rwstr[] = {
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[BLKG_RWSTAT_READ] = "Read",
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[BLKG_RWSTAT_WRITE] = "Write",
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[BLKG_RWSTAT_SYNC] = "Sync",
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[BLKG_RWSTAT_ASYNC] = "Async",
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[BLKG_RWSTAT_DISCARD] = "Discard",
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};
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const char *dname = blkg_dev_name(pd->blkg);
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u64 v;
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int i;
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if (!dname)
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return 0;
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for (i = 0; i < BLKG_RWSTAT_NR; i++)
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seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
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rwstat->cnt[i]);
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v = rwstat->cnt[BLKG_RWSTAT_READ] +
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rwstat->cnt[BLKG_RWSTAT_WRITE] +
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rwstat->cnt[BLKG_RWSTAT_DISCARD];
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seq_printf(sf, "%s Total %llu\n", dname, v);
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return v;
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}
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EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
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/**
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* blkg_prfill_rwstat - prfill callback for blkg_rwstat
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* @sf: seq_file to print to
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* @pd: policy private data of interest
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* @off: offset to the blkg_rwstat in @pd
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*
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* prfill callback for printing a blkg_rwstat.
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*/
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u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
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int off)
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{
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struct blkg_rwstat_sample rwstat = { };
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blkg_rwstat_read((void *)pd + off, &rwstat);
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return __blkg_prfill_rwstat(sf, pd, &rwstat);
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}
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EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
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/**
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* blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
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* @blkg: blkg of interest
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* @pol: blkcg_policy which contains the blkg_rwstat
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* @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
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* @sum: blkg_rwstat_sample structure containing the results
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*
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* Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
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* online descendants and their aux counts. The caller must be holding the
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* queue lock for online tests.
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*
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* If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it
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* is at @off bytes into @blkg's blkg_policy_data of the policy.
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*/
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void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
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int off, struct blkg_rwstat_sample *sum)
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{
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struct blkcg_gq *pos_blkg;
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struct cgroup_subsys_state *pos_css;
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unsigned int i;
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WARN_ON_ONCE(!rcu_read_lock_held());
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memset(sum, 0, sizeof(*sum));
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blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
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struct blkg_rwstat *rwstat;
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if (!pos_blkg->online)
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continue;
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if (pol) {
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struct blkg_policy_data *pd = blkg_to_pd(pos_blkg, pol);
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if (!pd)
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continue;
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rwstat = (void *)pd + off;
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} else {
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rwstat = (void *)pos_blkg + off;
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}
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for (i = 0; i < BLKG_RWSTAT_NR; i++)
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sum->cnt[i] += blkg_rwstat_read_counter(rwstat, i);
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}
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}
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EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
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