btrfs-progs: image: Verify the superblock before restore

This patch will export disk-io.c::check_super() as btrfs_check_super()
and use it in btrfs-image for extra verification.

Signed-off-by: Qu Wenruo <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: adam900710

disk-io.c

@@ -1347,7 +1347,7 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
  * - number of devices   - something sane
  * - sys array size      - maximum
  */
-static int check_super(struct btrfs_super_block *sb, unsigned sbflags)
+int btrfs_check_super(struct btrfs_super_block *sb, unsigned sbflags)
 {
 	u8 result[BTRFS_CSUM_SIZE];
 	u32 crc;
@@ -1547,7 +1547,7 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
 		if (btrfs_super_bytenr(buf) != sb_bytenr)
 			return -EIO;
 
-		ret = check_super(buf, sbflags);
+		ret = btrfs_check_super(buf, sbflags);
 		if (ret < 0)
 			return ret;
 		memcpy(sb, buf, BTRFS_SUPER_INFO_SIZE);
@@ -1572,7 +1572,7 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
 		/* if magic is NULL, the device was removed */
 		if (btrfs_super_magic(buf) == 0 && i == 0)
 			break;
-		if (check_super(buf, sbflags))
+		if (btrfs_check_super(buf, sbflags))
 			continue;
 
 		if (!fsid_is_initialized) {

disk-io.h

@@ -171,6 +171,7 @@ static inline int close_ctree(struct btrfs_root *root)
 
 int write_all_supers(struct btrfs_fs_info *fs_info);
 int write_ctree_super(struct btrfs_trans_handle *trans);
+int btrfs_check_super(struct btrfs_super_block *sb, unsigned sbflags);
 int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
 		unsigned sbflags);
 int btrfs_map_bh_to_logical(struct btrfs_root *root, struct extent_buffer *bh,

image/main.c

@@ -1983,6 +1983,11 @@ static int build_chunk_tree(struct mdrestore_struct *mdres,
 
 	pthread_mutex_lock(&mdres->mutex);
 	super = (struct btrfs_super_block *)buffer;
+	ret = btrfs_check_super(super, 0);
+	if (ret < 0) {
+		error("invalid superblock");
+		return ret;
+	}
 	chunk_root_bytenr = btrfs_super_chunk_root(super);
 	mdres->nodesize = btrfs_super_nodesize(super);
 	if (btrfs_super_incompat_flags(super) &