[PATCH v2 02/16] btrfs: make success path out of btrfs_init_dev_replace_tgtdev more clear

[David Sterba <dsterba@suse.com>]

This is a preparatory cleanup that will make clear that the only
successful way out of btrfs_init_dev_replace_tgtdev will also set the
device_out to a valid pointer. With this guarantee, the callers can be
simplified.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/dev-replace.c | 1 -
 fs/btrfs/volumes.c     | 8 +++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index c0397cd2a3ba..e3b8a79c1665 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -370,7 +370,6 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	dev_replace->cont_reading_from_srcdev_mode = read_src;
 	WARN_ON(!src_device);
 	dev_replace->srcdev = src_device;
-	WARN_ON(!tgt_device);
 	dev_replace->tgtdev = tgt_device;
 
 	btrfs_info_in_rcu(fs_info,
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 93f8f17cacca..8086c5687b72 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2592,6 +2592,12 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 	return ret;
 }
 
+/*
+ * Initialize a new device for device replace target from a given source dev
+ * and path.
+ *
+ * Return 0 and new device in @device_out, otherwise return < 0
+ */
 int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 				  const char *device_path,
 				  struct btrfs_device *srcdev,
@@ -2678,7 +2684,7 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 
 	*device_out = device;
-	return ret;
+	return 0;
 
 error:
 	blkdev_put(bdev, FMODE_EXCL);
-- 
2.16.2