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 
blkg_rwstat_init(struct blkg_rwstat * rwstat,gfp_t gfp)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 
blkg_rwstat_exit(struct blkg_rwstat * rwstat)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  */
__blkg_prfill_rwstat(struct seq_file * sf,struct blkg_policy_data * pd,const struct blkg_rwstat_sample * rwstat)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  */
blkg_prfill_rwstat(struct seq_file * sf,struct blkg_policy_data * pd,int off)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  */
blkg_rwstat_recursive_sum(struct blkcg_gq * blkg,struct blkcg_policy * pol,int off,struct blkg_rwstat_sample * sum)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);
131