Commit 36aa9e5f authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe

blkcg: move body parsing from blkg_conf_prep() to its callers

Currently, blkg_conf_prep() expects input to be of the following form

 MAJ:MIN NUM

and reads the NUM part into blkg_conf_ctx->v.  This is quite
restrictive and gets in the way in implementing blkcg interface for
the unified hierarchy.  This patch updates blkg_conf_prep() so that it
expects

 MAJ:MIN BODY_STR

where BODY_STR is an arbitrary string.  blkg_conf_ctx->v is replaced
with ->body which is a char pointer pointing to the start of BODY_STR.
Parsing of the body is moved to blkg_conf_prep()'s callers.

To allow using, for example, strsep() on blkg_conf_ctx->val, it is a
non-const pointer and to accommodate that const is dropped from @input
too.

This doesn't cause any behavior changes.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 880f50e2
......@@ -24,6 +24,7 @@
#include <linux/genhd.h>
#include <linux/delay.h>
#include <linux/atomic.h>
#include <linux/ctype.h>
#include <linux/blk-cgroup.h>
#include "blk.h"
......@@ -773,23 +774,28 @@ EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
* @ctx: blkg_conf_ctx to be filled
*
* Parse per-blkg config update from @input and initialize @ctx with the
* result. @ctx->blkg points to the blkg to be updated and @ctx->v the new
* value. This function returns with RCU read lock and queue lock held and
* must be paired with blkg_conf_finish().
* result. @ctx->blkg points to the blkg to be updated and @ctx->body the
* part of @input following MAJ:MIN. This function returns with RCU read
* lock and queue lock held and must be paired with blkg_conf_finish().
*/
int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
const char *input, struct blkg_conf_ctx *ctx)
char *input, struct blkg_conf_ctx *ctx)
__acquires(rcu) __acquires(disk->queue->queue_lock)
{
struct gendisk *disk;
struct blkcg_gq *blkg;
unsigned int major, minor;
unsigned long long v;
int part, ret;
int key_len, part, ret;
char *body;
if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3)
if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2)
return -EINVAL;
body = input + key_len;
if (!isspace(*body))
return -EINVAL;
body = skip_spaces(body);
disk = get_gendisk(MKDEV(major, minor), &part);
if (!disk)
return -ENODEV;
......@@ -826,7 +832,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
ctx->disk = disk;
ctx->blkg = blkg;
ctx->v = v;
ctx->body = body;
return 0;
}
EXPORT_SYMBOL_GPL(blkg_conf_prep);
......
......@@ -1154,21 +1154,25 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
struct blkcg_gq *blkg;
struct cgroup_subsys_state *pos_css;
int ret;
u64 v;
ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
if (ret)
return ret;
ret = -EINVAL;
if (sscanf(ctx.body, "%llu", &v) != 1)
goto out_finish;
if (!v)
v = -1;
tg = blkg_to_tg(ctx.blkg);
sq = &tg->service_queue;
if (!ctx.v)
ctx.v = -1;
if (is_u64)
*(u64 *)((void *)tg + of_cft(of)->private) = ctx.v;
*(u64 *)((void *)tg + of_cft(of)->private) = v;
else
*(unsigned int *)((void *)tg + of_cft(of)->private) = ctx.v;
*(unsigned int *)((void *)tg + of_cft(of)->private) = v;
throtl_log(&tg->service_queue,
"limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
......@@ -1201,8 +1205,10 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
throtl_schedule_next_dispatch(sq->parent_sq, true);
}
ret = 0;
out_finish:
blkg_conf_finish(&ctx);
return nbytes;
return ret ?: nbytes;
}
static ssize_t tg_set_conf_u64(struct kernfs_open_file *of,
......
......@@ -1747,26 +1747,31 @@ static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
struct cfq_group *cfqg;
struct cfq_group_data *cfqgd;
int ret;
u64 v;
ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
if (ret)
return ret;
ret = -EINVAL;
if (sscanf(ctx.body, "%llu", &v) != 1)
goto out_finish;
cfqg = blkg_to_cfqg(ctx.blkg);
cfqgd = blkcg_to_cfqgd(blkcg);
ret = -ERANGE;
if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
if (!v || (v >= CFQ_WEIGHT_MIN && v <= CFQ_WEIGHT_MAX)) {
if (!is_leaf_weight) {
cfqg->dev_weight = ctx.v;
cfqg->new_weight = ctx.v ?: cfqgd->weight;
cfqg->dev_weight = v;
cfqg->new_weight = v ?: cfqgd->weight;
} else {
cfqg->dev_leaf_weight = ctx.v;
cfqg->new_leaf_weight = ctx.v ?: cfqgd->leaf_weight;
cfqg->dev_leaf_weight = v;
cfqg->new_leaf_weight = v ?: cfqgd->leaf_weight;
}
ret = 0;
}
out_finish:
blkg_conf_finish(&ctx);
return ret ?: nbytes;
}
......
......@@ -206,11 +206,11 @@ struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
struct blkg_conf_ctx {
struct gendisk *disk;
struct blkcg_gq *blkg;
u64 v;
char *body;
};
int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
const char *input, struct blkg_conf_ctx *ctx);
char *input, struct blkg_conf_ctx *ctx);
void blkg_conf_finish(struct blkg_conf_ctx *ctx);
......
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