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new helper: ext2_image_size()

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... 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>
This commit is contained in:
Al Viro 2012-03-23 16:36:45 -04:00
parent 2f99c36986
commit 39429c5e4a
3 changed files with 30 additions and 8 deletions
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7
arch/blackfin/kernel/setup.c
View File

@ -550,6 +550,7 @@ static __init void memory_setup(void)
{
#ifdef CONFIG_MTD_UCLINUX
unsigned long mtd_phys = 0;
unsigned long n;
#endif
unsigned long max_mem;
@ -593,9 +594,9 @@ static __init void memory_setup(void)
mtd_size = PAGE_ALIGN(*((unsigned long *)(mtd_phys + 8)));
# if defined(CONFIG_EXT2_FS) || defined(CONFIG_EXT3_FS)
if (*((unsigned short *)(mtd_phys + 0x438)) == EXT2_SUPER_MAGIC)
mtd_size =
PAGE_ALIGN(*((unsigned long *)(mtd_phys + 0x404)) << 10);
n = ext2_image_size((void *)(mtd_phys + 0x400));
if (n)
mtd_size = PAGE_ALIGN(n * 1024);
# endif
# if defined(CONFIG_CRAMFS)

22
include/linux/ext2_fs.h
View File

@ -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 */

9
init/do_mounts_rd.c
View File

@ -54,20 +54,19 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
{
const int size = 512;
struct minix_super_block *minixsb;
struct ext2_super_block *ext2sb;
struct romfs_super_block *romfsb;
struct cramfs_super *cramfsb;
struct squashfs_super_block *squashfsb;
int nblocks = -1;
unsigned char *buf;
const char *compress_name;
unsigned long n;
buf = kmalloc(size, GFP_KERNEL);
if (!buf)
return -ENOMEM;
minixsb = (struct minix_super_block *) buf;
ext2sb = (struct ext2_super_block *) buf;
romfsb = (struct romfs_super_block *) buf;
cramfsb = (struct cramfs_super *) buf;
squashfsb = (struct squashfs_super_block *) buf;
@ -150,12 +149,12 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
}
/* Try ext2 */
if (ext2sb->s_magic == cpu_to_le16(EXT2_SUPER_MAGIC)) {
n = ext2_image_size(buf);
if (n) {
printk(KERN_NOTICE
"RAMDISK: ext2 filesystem found at block %d\n",
start_block);
nblocks = le32_to_cpu(ext2sb->s_blocks_count) <<
le32_to_cpu(ext2sb->s_log_block_size);
nblocks = n;
goto done;
}