[PATCH 03/10] blkcg: separate blkcg_conf_get_disk() out of blkg_conf_prep()

From: Tejun Heo
Date: Wed Jul 10 2019 - 16:51:48 EST


Separate out blkcg_conf_get_disk() so that it can be used by blkcg
policy interface file input parsers before the policy is actually
enabled. This doesn't introduce any functional changes.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
block/blk-cgroup.c | 62 ++++++++++++++++++++++++++------------
include/linux/blk-cgroup.h | 1 +
2 files changed, 44 insertions(+), 19 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 818e50b4cc7a..aed46a2c553e 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -753,6 +753,44 @@ static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg,
return __blkg_lookup(blkcg, q, true /* update_hint */);
}

+/**
+ * blkg_conf_prep - parse and prepare for per-blkg config update
+ * @inputp: input string pointer
+ *
+ * Parse the device node prefix part, MAJ:MIN, of per-blkg config update
+ * from @input and get and return the matching gendisk. *@inputp is
+ * updated to point past the device node prefix. Returns an ERR_PTR()
+ * value on error.
+ *
+ * Use this function iff blkg_conf_prep() can't be used for some reason.
+ */
+struct gendisk *blkcg_conf_get_disk(char **inputp)
+{
+ char *input = *inputp;
+ unsigned int major, minor;
+ struct gendisk *disk;
+ int key_len, part;
+
+ if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2)
+ return ERR_PTR(-EINVAL);
+
+ input += key_len;
+ if (!isspace(*input))
+ return ERR_PTR(-EINVAL);
+ input = skip_spaces(input);
+
+ disk = get_gendisk(MKDEV(major, minor), &part);
+ if (!disk)
+ return ERR_PTR(-ENODEV);
+ if (part) {
+ put_disk_and_module(disk);
+ return ERR_PTR(-ENODEV);
+ }
+
+ *inputp = input;
+ return disk;
+}
+
/**
* blkg_conf_prep - parse and prepare for per-blkg config update
* @blkcg: target block cgroup
@@ -772,25 +810,11 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
struct gendisk *disk;
struct request_queue *q;
struct blkcg_gq *blkg;
- unsigned int major, minor;
- int key_len, part, ret;
- char *body;
-
- 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);
+ int ret;

- disk = get_gendisk(MKDEV(major, minor), &part);
- if (!disk)
- return -ENODEV;
- if (part) {
- ret = -ENODEV;
- goto fail;
- }
+ disk = blkcg_conf_get_disk(&input);
+ if (IS_ERR(disk))
+ return PTR_ERR(disk);

q = disk->queue;

@@ -856,7 +880,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
success:
ctx->disk = disk;
ctx->blkg = blkg;
- ctx->body = body;
+ ctx->body = input;
return 0;

fail_unlock:
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 930631cad5cf..b0eacec11037 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -233,6 +233,7 @@ struct blkg_conf_ctx {
char *body;
};

+struct gendisk *blkcg_conf_get_disk(char **inputp);
int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
char *input, struct blkg_conf_ctx *ctx);
void blkg_conf_finish(struct blkg_conf_ctx *ctx);
--
2.17.1