From: "Post, Mark K" <mark.post@eds.com>
[1.] One line summary of the problem:
Trying to use an initrd for an installation fails unless the mke2fs
used a blocksize of 1024 bytes.
[2.] Full description of the problem/report:
I'm trying to create a Linux for S/390 version 2.2.20 installation
kernel/ramdisk set. When I create the ramdisk, if I issue the mke2fs
command with -b 2048 or -b 4096, it works fine. But, I try to boot the
system, I get an "EXT2-fs: Magic mismatch, very weird !" error when the
kernel tries to mount the ramdisk as the root file system. If I let the
blocksize default, or specify -b 1024, everything works fine.
The comparison that seems to be failing is at line 500 of
linux/fs/ext/super.c:
if (es->s_magic != le16_to_cpu(EXT2_SUPER_MAGIC)) {
printk ("EXT2-fs: Magic mismatch, very weird !\n");
goto failed_mount;
Well, we can read the source.
ext2_read_super() starts finding a blocksize:
blocksize = get_hardblocksize(dev);
and buffer.c:get_hardblocksize() returns hardsect_size[major][minor].
rd.c sets hardsect_size[] to rd_hardsec, and initializes rd_hardsec
to RDBLK_SIZE, which is 512.
OK, so blocksize = 512.
Next,
if (blocksize < BLOCK_SIZE)
blocksize = BLOCK_SIZE;
So, now it is 1024.
Then bread (dev, 1, blocksize) reads the wrong part,
if in reality blocksize was different.
I once submitted a patch for this, but apparently it is not in 2.2.20.
Might do so later this evening, if there is time.
Andries
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This archive was generated by hypermail 2b29 : Mon Apr 15 2002 - 22:00:21 EST