block: fix genhd refcounting in blkio_policy_parse_and_set()

blkio_policy_parse_and_set() calls blkio_check_dev_num() to check
whether the given dev_t is valid.  blkio_check_dev_num() uses
get_gendisk() for verification but never puts the returned genhd
leaking the reference.

This patch collapses blkio_check_dev_num() into its caller and updates
it such that the genhd is put before returning.

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

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b596e54..d61ec56 100644 (file)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -768,25 +768,14 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg,
        return disk_total;
 }
 
-static int blkio_check_dev_num(dev_t dev)
-{
-       int part = 0;
-       struct gendisk *disk;
-
-       disk = get_gendisk(dev, &part);
-       if (!disk || part)
-               return -ENODEV;
-
-       return 0;
-}
-
 static int blkio_policy_parse_and_set(char *buf,
        struct blkio_policy_node *newpn, enum blkio_policy_id plid, int fileid)
 {
+       struct gendisk *disk = NULL;
        char *s[4], *p, *major_s = NULL, *minor_s = NULL;
-       int ret;
        unsigned long major, minor;
-       int i = 0;
+       int i = 0, ret = -EINVAL;
+       int part;
        dev_t dev;
        u64 temp;
 
@@ -804,37 +793,36 @@ static int blkio_policy_parse_and_set(char *buf,
        }
 
        if (i != 2)
-               return -EINVAL;
+               goto out;
 
        p = strsep(&s[0], ":");
        if (p != NULL)
                major_s = p;
        else
-               return -EINVAL;
+               goto out;
 
        minor_s = s[0];
        if (!minor_s)
-               return -EINVAL;
+               goto out;
 
-       ret = strict_strtoul(major_s, 10, &major);
-       if (ret)
-               return -EINVAL;
+       if (strict_strtoul(major_s, 10, &major))
+               goto out;
 
-       ret = strict_strtoul(minor_s, 10, &minor);
-       if (ret)
-               return -EINVAL;
+       if (strict_strtoul(minor_s, 10, &minor))
+               goto out;
 
        dev = MKDEV(major, minor);
 
-       ret = strict_strtoull(s[1], 10, &temp);
-       if (ret)
-               return -EINVAL;
+       if (strict_strtoull(s[1], 10, &temp))
+               goto out;
 
        /* For rule removal, do not check for device presence. */
        if (temp) {
-               ret = blkio_check_dev_num(dev);
-               if (ret)
-                       return ret;
+               disk = get_gendisk(dev, &part);
+               if (!disk || part) {
+                       ret = -ENODEV;
+                       goto out;
+               }
        }
 
        newpn->dev = dev;
@@ -843,7 +831,7 @@ static int blkio_policy_parse_and_set(char *buf,
        case BLKIO_POLICY_PROP:
                if ((temp < BLKIO_WEIGHT_MIN && temp > 0) ||
                     temp > BLKIO_WEIGHT_MAX)
-                       return -EINVAL;
+                       goto out;
 
                newpn->plid = plid;
                newpn->fileid = fileid;
@@ -860,7 +848,7 @@ static int blkio_policy_parse_and_set(char *buf,
                case BLKIO_THROTL_read_iops_device:
                case BLKIO_THROTL_write_iops_device:
                        if (temp > THROTL_IOPS_MAX)
-                               return -EINVAL;
+                               goto out;
 
                        newpn->plid = plid;
                        newpn->fileid = fileid;
@@ -871,8 +859,10 @@ static int blkio_policy_parse_and_set(char *buf,
        default:
                BUG();
        }
-
-       return 0;
+       ret = 0;
+out:
+       put_disk(disk);
+       return ret;
 }
 
 unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,