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| author | Al Viro <viro@zeniv.linux.org.uk> | 2012-03-23 16:36:45 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-03-31 16:03:16 -0400 |
| commit | 39429c5e4a2c56a39c9a1c9bdad54431c63104b0 (patch) | |
| tree | 06abc2a4ff8d323b0358b768a71c7b651c3229f3 /include/linux/ext2_fs.h | |
| parent | 2f99c36986ff27a86f06f27212c5f5fa8c7164a3 (diff) | |
new helper: ext2_image_size()
... implemented that way since the next commit will leave it
almost alone in ext2_fs.h - most of the file (including
struct ext2_super_block) is going to move to fs/ext2/ext2.h.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux/ext2_fs.h')
| -rw-r--r-- | include/linux/ext2_fs.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/ext2_fs.h b/include/linux/ext2_fs.h index f28dba518a4a..5f65ec75b48a 100644 --- a/include/linux/ext2_fs.h +++ b/include/linux/ext2_fs.h @@ -536,4 +536,26 @@ enum { ~EXT2_DIR_ROUND) #define EXT2_MAX_REC_LEN ((1<<16)-1) +#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 +} + #endif /* _LINUX_EXT2_FS_H */ |