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authorAl Viro <viro@zeniv.linux.org.uk>2012-03-24 00:36:45 +0400
committerAl Viro <viro@zeniv.linux.org.uk>2012-04-01 00:03:16 +0400
commit39429c5e4a2c56a39c9a1c9bdad54431c63104b0 (patch)
tree06abc2a4ff8d323b0358b768a71c7b651c3229f3
parent2f99c36986ff27a86f06f27212c5f5fa8c7164a3 (diff)
downloadlinux-39429c5e4a2c56a39c9a1c9bdad54431c63104b0.tar.xz
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>
-rw-r--r--arch/blackfin/kernel/setup.c7
-rw-r--r--include/linux/ext2_fs.h22
-rw-r--r--init/do_mounts_rd.c9
3 files changed, 30 insertions, 8 deletions
diff --git a/arch/blackfin/kernel/setup.c b/arch/blackfin/kernel/setup.c
index 2aa019368504..2ad747e909fb 100644
--- a/arch/blackfin/kernel/setup.c
+++ b/arch/blackfin/kernel/setup.c
@@ -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)
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 */
diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c
index 01f1306aa26e..6212586df29a 100644
--- a/init/do_mounts_rd.c
+++ b/init/do_mounts_rd.c
@@ -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;
}