From bb6d355c2aff42d4075a8e7428dd72cb009d6143 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Thu, 25 Apr 2019 00:48:38 +0800
Subject: [PATCH] bcache: Add comments for blkdev_put() in registration code
path
Git-commit: bb6d355c2aff42d4075a8e7428dd72cb009d6143
Patch-mainline: v5.2-rc1
References: bsc#1140652
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 fde334939545..fa856b2ca7af 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -2189,6 +2189,12 @@ 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";
@@ -2329,6 +2335,7 @@ 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 {
@@ -2337,6 +2344,7 @@ 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