diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 10dfb41f4c22..72dc02e82945 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -330,29 +330,19 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
 		return -EINVAL;
 
 	mutex_lock(&fs_info->volume_mutex);
-	ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
-					    &tgt_device);
-	if (ret) {
-		btrfs_err(fs_info, "target device %s is invalid!",
-		       args->start.tgtdev_name);
-		mutex_unlock(&fs_info->volume_mutex);
-		return -EINVAL;
-	}
-
 	ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
 					    args->start.srcdev_name,
 					    &src_device);
-	mutex_unlock(&fs_info->volume_mutex);
 	if (ret) {
-		ret = -EINVAL;
-		goto leave_no_lock;
+		mutex_unlock(&fs_info->volume_mutex);
+		return ret;
 	}
 
-	if (tgt_device->total_bytes < src_device->total_bytes) {
-		btrfs_err(fs_info, "target device is smaller than source device!");
-		ret = -EINVAL;
-		goto leave_no_lock;
-	}
+	ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
+					    src_device, &tgt_device);
+	mutex_unlock(&fs_info->volume_mutex);
+	if (ret)
+		return ret;
 
 	btrfs_dev_replace_lock(dev_replace);
 	switch (dev_replace->replace_state) {
@@ -380,10 +370,6 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
 		      src_device->devid,
 		      rcu_str_deref(tgt_device->name));
 
-	tgt_device->total_bytes = src_device->total_bytes;
-	tgt_device->disk_total_bytes = src_device->disk_total_bytes;
-	tgt_device->bytes_used = src_device->bytes_used;
-
 	/*
 	 * from now on, the writes to the srcdev are all duplicated to
 	 * go to the tgtdev as well (refer to btrfs_map_block()).
@@ -426,9 +412,7 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
 	dev_replace->srcdev = NULL;
 	dev_replace->tgtdev = NULL;
 	btrfs_dev_replace_unlock(dev_replace);
-leave_no_lock:
-	if (tgt_device)
-		btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
+	btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 	return ret;
 }
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 483fc6d45299..1646659f2800 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2295,6 +2295,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 }
 
 int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
+				  struct btrfs_device *srcdev,
 				  struct btrfs_device **device_out)
 {
 	struct request_queue *q;
@@ -2307,24 +2308,37 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
 	int ret = 0;
 
 	*device_out = NULL;
-	if (fs_info->fs_devices->seeding)
+	if (fs_info->fs_devices->seeding) {
+		btrfs_err(fs_info, "the filesystem is a seed filesystem!");
 		return -EINVAL;
+	}
 
 	bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
 				  fs_info->bdev_holder);
-	if (IS_ERR(bdev))
+	if (IS_ERR(bdev)) {
+		btrfs_err(fs_info, "target device %s is invalid!", device_path);
 		return PTR_ERR(bdev);
+	}
 
 	filemap_write_and_wait(bdev->bd_inode->i_mapping);
 
 	devices = &fs_info->fs_devices->devices;
 	list_for_each_entry(device, devices, dev_list) {
 		if (device->bdev == bdev) {
+			btrfs_err(fs_info, "target device is in the filesystem!");
 			ret = -EEXIST;
 			goto error;
 		}
 	}
 
+
+	if (i_size_read(bdev->bd_inode) < srcdev->total_bytes) {
+		btrfs_err(fs_info, "target device is smaller than source device!");
+		ret = -EINVAL;
+		goto error;
+	}
+
+
 	device = btrfs_alloc_device(NULL, &devid, NULL);
 	if (IS_ERR(device)) {
 		ret = PTR_ERR(device);
@@ -2348,8 +2362,9 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
 	device->io_width = root->sectorsize;
 	device->io_align = root->sectorsize;
 	device->sector_size = root->sectorsize;
-	device->total_bytes = i_size_read(bdev->bd_inode);
-	device->disk_total_bytes = device->total_bytes;
+	device->total_bytes = srcdev->total_bytes;
+	device->disk_total_bytes = srcdev->disk_total_bytes;
+	device->bytes_used = srcdev->bytes_used;
 	device->dev_root = fs_info->dev_root;
 	device->bdev = bdev;
 	device->in_fs_metadata = 1;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 37f8bff97df1..e15f2886d33e 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -322,6 +322,7 @@ struct btrfs_device *btrfs_find_device(struct btrfs_fs_info *fs_info, u64 devid,
 int btrfs_shrink_device(struct btrfs_device *device, u64 new_size);
 int btrfs_init_new_device(struct btrfs_root *root, char *path);
 int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
+				  struct btrfs_device *srcdev,
 				  struct btrfs_device **device_out);
 int btrfs_balance(struct btrfs_balance_control *bctl,
 		  struct btrfs_ioctl_balance_args *bargs);