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: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 429726bed560b8b2020dfd14f2ee76d91193ffa0..8ee1ca4d4f2f8ec7ceec4df8fd5039e887a8e5b1 100644 (file)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -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);

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 8b4f6b81bb721b473da601cce7d2e93cbc1787b8..0e17c8f92d254053e3ac5790498dfb9eeeb89b8a 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -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,

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index baa8459f7064670def949e737afc5146530e3419..ea88d8905bbd64bc3f4d3dfa2d02320dcddff3f2 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -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;
 }

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 6e016e6fee872c770aa44316ab1cf13eb7d44286..85a4d989ae437c6e26e97adfa9a03e4c8c0e0ced 100644 (file)
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -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);