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

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

block/blk-cgroup.c

+14 −8
Original line number Diff line number Diff line
@@ -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);

block/blk-throttle.c

+12 −6
Original line number Diff line number Diff line
@@ -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,

block/cfq-iosched.c

+11 −6
Original line number Diff line number Diff line
@@ -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;

}

include/linux/blk-cgroup.h

+2 −2
Original line number Diff line number Diff line
@@ -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);