btrfs: don't clobber ret in btrfs_validate_super()

Commit 2a9bb78 ("btrfs: validate system chunk array at
btrfs_validate_super()") introduces a call to validate_sys_chunk_array()
in btrfs_validate_super(), which clobbers the value of ret set earlier.
This has the effect of negating the validity checks done earlier, making
it so btrfs could potentially try to mount invalid filesystems.

Fixes: 2a9bb78 ("btrfs: validate system chunk array at btrfs_validate_super()")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Mark Harmstone <maharmstone@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: maharmstone

fs/btrfs/disk-io.c

@@ -2562,6 +2562,9 @@ int btrfs_validate_super(const struct btrfs_fs_info *fs_info,
 		ret = -EINVAL;
 	}
 
+	if (ret)
+		return ret;
+
 	ret = validate_sys_chunk_array(fs_info, sb);
 
 	/*