blkcg: simplify blkg_conf_prep()

blkg_conf_prep() implements "MAJ:MIN VAL" parsing manually, which is
unnecessary.  Just use sscanf("%u:%u %llu").  This might not reject
some malformed input (extra input at the end) but we don't care.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 10 insertions, 54 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 1e1ee2af7b5f..b07a501839e7 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -987,57 +987,16 @@ static int blkg_conf_prep(struct blkio_cgroup *blkcg, const char *input,
 {
         struct gendisk *disk;
         struct blkio_group *blkg;
-        char *buf, *s[4], *p, *major_s, *minor_s;
-        unsigned long major, minor;
-        int i = 0, ret = -EINVAL;
-        int part;
-        dev_t dev;
-        u64 temp;
+        unsigned int major, minor;
+        unsigned long long v;
+        int part, ret;
 
-        buf = kstrdup(input, GFP_KERNEL);
-        if (!buf)
-                return -ENOMEM;
-
-        memset(s, 0, sizeof(s));
-
-        while ((p = strsep(&buf, " ")) != NULL) {
-                if (!*p)
-                        continue;
-
-                s[i++] = p;
-
-                /* Prevent from inputing too many things */
-                if (i == 3)
-                        break;
-        }
-
-        if (i != 2)
-                goto out;
-
-        p = strsep(&s[0], ":");
-        if (p != NULL)
-                major_s = p;
-        else
-                goto out;
-
-        minor_s = s[0];
-        if (!minor_s)
-                goto out;
-
-        if (strict_strtoul(major_s, 10, &major))
-                goto out;
-
-        if (strict_strtoul(minor_s, 10, &minor))
-                goto out;
-
-        dev = MKDEV(major, minor);
-
-        if (strict_strtoull(s[1], 10, &temp))
-                goto out;
+        if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3)
+                return -EINVAL;
 
-        disk = get_gendisk(dev, &part);
+        disk = get_gendisk(MKDEV(major, minor), &part);
         if (!disk || part)
-                goto out;
+                return -EINVAL;
 
         rcu_read_lock();
 
@@ -1059,16 +1018,13 @@ static int blkg_conf_prep(struct blkio_cgroup *blkcg, const char *input,
                         msleep(10);
                         ret = restart_syscall();
                 }
-                goto out;
+                return ret;
         }
 
         ctx->disk = disk;
         ctx->blkg = blkg;
-        ctx->v = temp;
-        ret = 0;
-out:
-        kfree(buf);
-        return ret;
+        ctx->v = v;
+        return 0;
 }
 
 /**