Btrfs: fix unprotected assignment of the target device

We didn't protect the assignment of the target device, it might cause the
problem that the super block update was skipped because we might find wrong
size of the target device during the assignment. Fix it by moving the
assignment sentences into the initialization function of the target device.
And there is another merit that we can check if the target device is suitable
more early.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 19 insertions, 4 deletions

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 @@ error:
 }
 
 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;