init/do_mounts_rd.c: fix ramdisk identification for padded cramfs

When a cramfs ramdisk padded with 512 bytes is given to the kernel, the
current identify_ramdisk_image function fails to identify it.

Tested with a padded cramfs image on an ARM based board.

Signed-off-by: Neil Armstrong <narmstrong@neotion.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Davidlohr Bueso <dave@gnu.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Neil Armstrong 2011-11-02 13:37:47 -07:00 committed by Linus Torvalds
parent 0620d9193c
commit f919b9235f

View File

@ -119,6 +119,20 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
goto done;
}
/*
* Read 512 bytes further to check if cramfs is padded
*/
sys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0);
sys_read(fd, buf, size);
if (cramfsb->magic == CRAMFS_MAGIC) {
printk(KERN_NOTICE
"RAMDISK: cramfs filesystem found at block %d\n",
start_block);
nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
goto done;
}
/*
* Read block 1 to test for minix and ext2 superblock
*/