Looks good.
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>
On 04/19/2019 11:24 AM, Coly Li wrote:
> Add comments to explain why in register_bcache() blkdev_put() won't
> be called in two location. Add comments to explain why blkdev_put()
> must be called in register_cache() when cache_alloc() failed.
>
> Signed-off-by: Coly Li <colyli@xxxxxxx>
> ---
> drivers/md/bcache/super.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index a435c506edba..83a7cb0e0e45 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -2191,6 +2191,12 @@ static int register_cache(struct cache_sb *sb, struct page *sb_page,
>
> ret = cache_alloc(ca);
> if (ret != 0) {
> + /*
> + * If we failed here, it means ca->kobj is not initialzed yet,
> + * kobject_put() won't be called and there is no chance to
> + * call blkdev_put() to bdev in bch_cache_release(). So we
> + * explictly call blkdev_put() here.
> + */
> blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
> if (ret == -ENOMEM)
> err = "cache_alloc(): -ENOMEM";
> @@ -2331,6 +2337,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
> mutex_lock(&bch_register_lock);
> ret = register_bdev(sb, sb_page, bdev, dc);
> mutex_unlock(&bch_register_lock);
> + /* blkdev_put() will be called in cached_dev_free() */
> if (ret < 0)
> goto err;
> } else {
> @@ -2339,6 +2346,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
> if (!ca)
> goto err_close;
>
> + /* blkdev_put() will be called in bch_cache_release() */
> if (register_cache(sb, sb_page, bdev, ca) != 0)
> goto err;
> }
>
