mounting loop-device on a 2048 byte/sector medium fails

Hi,

first I thought this was some loop-AES specific issue, but now I know it isn't: When I try to mount a filesystem on a loop device which is in turn using a 2048 byte/sector medium (a magneto-optical drive in my case), the mount fails though mkfs & fsck are happy.

The following script (tests done with kernel 2.4.18):

----------------------------------------------------------------------
#!/bin/sh

echo -n "blockdev /dev/sdb result: "
blockdev --getbsz /dev/sdb

losetup /dev/loop0 /dev/sdb

echo
echo -n "blockdev /dev/loop0 result: "
blockdev --getbsz /dev/loop0

echo
echo "mkfs output:"
mkfs -t ext2 /dev/loop0

echo
echo "fsck output:"
fsck.ext2 -f /dev/loop0

echo
echo "mount output:"

mount -t ext2 /dev/loop0 /mnt/floppy
------------------------------------------------------------------------

works just fine when the medium inserted into the MO-drive is a 512 byte/sector medium, but when I put a 2048 byte/sector medium in the drive, this is the resulting output:

------------------------------------------------------------------------
blockdev /dev/sdb result: 2048

blockdev /dev/loop0 result: 2048

mkfs output:
mke2fs 1.23, 15-Aug-2001 for EXT2 FS 0.5b, 95/08/09 Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
77600 inodes, 155176 blocks
7758 blocks (5.00%) reserved for the super user First data block=0
5 block groups
32768 blocks per group, 32768 fragments per group 15520 inodes per group
Superblock backups stored on blocks:

        32768, 98304

Writing inode tables: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 31 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.

fsck output:
e2fsck 1.23, 15-Aug-2001 for EXT2 FS 0.5b, 95/08/09
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/loop0: 11/77600 files (0.0% non-contiguous), 2446/155176 blocks

mount output:
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
or too many mounted file systems
------------------------------------------------------------------------

Any idea?

Regards,

Peter Niemayer

I reported this some time ago as a problem with using offset mounting CDs with a binary prefix before the ISO image. And since it seems that the problem is not the offset but the sector size, the problems may be related.

I'll look at this over the weekend if not before. It works with 2.0 and 2.2, I use it regularly, and it's the main thing keeping a few of my machines on 2.2.

bill davidsen <[email protected]>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

Then I've got good news for you: Jari Ruusu just sent me a patch to the loop device that fixes the problem!

As loop-AES has a super-set of features of the original loop device, you may download loop-AES 1.6b here:

http://sourceforge.net/project/showfiles.php?group_id=28891&release_id=84590

... and replace the loop.c-2.4.diff file in it with the attached new version.

Or wait until there's an official new loop-AES release or until the maintainer of the original loop.c applied a similar patch.

Regards,

Peter Niemayer

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