btrfs: send: do not BUG_ON() on unexpected symlink data extent

There's really no need to BUG_ON() if we find a symlink with an extent
that is not inline or is compressed. We can just make send fail with
an error (-EUCLEAN) and log an informative error message, so just do
that instead of BUG_ON().

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

Author: fdmanana

fs/btrfs/send.c

@@ -1774,9 +1774,21 @@ static int read_symlink(struct btrfs_root *root,
 	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
 			struct btrfs_file_extent_item);
 	type = btrfs_file_extent_type(path->nodes[0], ei);
+	if (unlikely(type != BTRFS_FILE_EXTENT_INLINE)) {
+		ret = -EUCLEAN;
+		btrfs_crit(root->fs_info,
+"send: found symlink extent that is not inline, ino %llu root %llu extent type %d",
+			   ino, btrfs_root_id(root), type);
+		goto out;
+	}
 	compression = btrfs_file_extent_compression(path->nodes[0], ei);
-	BUG_ON(type != BTRFS_FILE_EXTENT_INLINE);
-	BUG_ON(compression);
+	if (unlikely(compression != BTRFS_COMPRESS_NONE)) {
+		ret = -EUCLEAN;
+		btrfs_crit(root->fs_info,
+"send: found symlink extent with compression, ino %llu root %llu compression type %d",
+			   ino, btrfs_root_id(root), compression);
+		goto out;
+	}
 
 	off = btrfs_file_extent_inline_start(ei);
 	len = btrfs_file_extent_ram_bytes(path->nodes[0], ei);