mainline inclusion from mainline-5.2-rc1 commit bb6d355c2aff42d4075a8e7428dd72cb009d6143 category: backport 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@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> --- 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 e61abdce9a23..32dd81a6e57d 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -2177,6 +2177,12 @@ 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 initialized yet, + * kobject_put() won't be called and there is no chance to + * call blkdev_put() to bdev in bch_cache_release(). So we + * explicitly call blkdev_put() here. + */ blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); if (ret == -ENOMEM) err = "cache_alloc(): -ENOMEM"; @@ -2317,6 +2323,7 @@ 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 { @@ -2325,6 +2332,7 @@ 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; } -- 2.16.4