+#define EXT2_SB_MAGIC_OFFSET 0x38
+#define EXT2_SB_BLOCKS_OFFSET 0x04
+#define EXT2_SB_BSIZE_OFFSET 0x18
+
+static inline u64 ext2_image_size(void *ext2_sb)
+{
+ __u8 *p = ext2_sb;
+ if (*(__le16 *)(p + EXT2_SB_MAGIC_OFFSET) != cpu_to_le16(EXT2_SUPER_MAGIC))
+ return 0;
+ return (u64)le32_to_cpup((__le32 *)(p + EXT2_SB_BLOCKS_OFFSET)) <<
+ le32_to_cpup((__le32 *)(p + EXT2_SB_BSIZE_OFFSET));
+}
+
+static inline void verify_offsets(void)
+{
+#define A(x,y) BUILD_BUG_ON(x != offsetof(struct ext2_super_block, y));
+ A(EXT2_SB_MAGIC_OFFSET, s_magic);
+ A(EXT2_SB_BLOCKS_OFFSET, s_blocks_count);
+ A(EXT2_SB_BSIZE_OFFSET, s_log_block_size);
+#undef A
+}
+