btrfs: use fs_holder_ops for all opened devices

Since we have btrfs_fs_info::sb (struct super_block) as our block device
holder, we can safely use fs_holder_ops for all of our block devices.

This enables freezing/thawing the btrfs from the underlying block
devices.

This may enhance hibernation/suspension support since previously
freezing/thawing a block device managed by btrfs won't do anything btrfs
specific, but only syncing the block device.

Thus before this change, freezing the underlying block devices won't
prevent future writes into the btrfs, thus may cause problems for
hibernation/suspension when btrfs is involved.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

fs/btrfs/dev-replace.c

@@ -250,7 +250,7 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 	}
 
 	bdev_file = bdev_file_open_by_path(device_path, BLK_OPEN_WRITE,
-					   fs_info->sb, NULL);
+					   fs_info->sb, &fs_holder_ops);
 	if (IS_ERR(bdev_file)) {
 		btrfs_err(fs_info, "target device %s is invalid!", device_path);
 		return PTR_ERR(bdev_file);

fs/btrfs/volumes.c

@@ -475,7 +475,7 @@ btrfs_get_bdev_and_sb(const char *device_path, blk_mode_t flags, void *holder,
 	struct block_device *bdev;
 	int ret;
 
-	*bdev_file = bdev_file_open_by_path(device_path, flags, holder, NULL);
+	*bdev_file = bdev_file_open_by_path(device_path, flags, holder, &fs_holder_ops);
 
 	if (IS_ERR(*bdev_file)) {
 		ret = PTR_ERR(*bdev_file);
@@ -2707,7 +2707,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 		return -EROFS;
 
 	bdev_file = bdev_file_open_by_path(device_path, BLK_OPEN_WRITE,
-					   fs_info->sb, NULL);
+					   fs_info->sb, &fs_holder_ops);
 	if (IS_ERR(bdev_file))
 		return PTR_ERR(bdev_file);