ramdisk driver in 2.6.6 has a severe bug
From: Robert M. Stockmann
Date: Mon May 17 2004 - 18:04:40 EST
Hi,
I have severe problems creating a new root-disk using the ramdisk driver
of kernel 2.6.6 :
[tapebox:root]:(~)# uname -a
Linux tapebox.stokkie.net 2.6.6 #1 Thu May 13 05:48:57 CEST 2004 i686 unknown unknown GNU/Linux
I'm trying to create a new root filesystem from my older version :
[tapebox:root]:(~)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2814216 2579804 53% /
[tapebox:root]:(~)# dd if=/dev/zero of=/dev/ram0 bs=1k count=16384
16384+0 records in
16384+0 records out
[tapebox:root]:(~)# mke2fs -vm0 /dev/ram0 16384
mke2fs 1.35 (28-Feb-2004)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4096 inodes, 16384 blocks
0 blocks (0.00%) reserved for the super user
First data block=1
2 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks:
8193
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 21 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[tapebox:root]:(~)# mount -t ext2 /dev/ram0 /mnt/root
[tapebox:root]:(~)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2814216 2579804 53% /
/dev/ram0 15863 13 15850 1% /mnt/root
[tapebox:root]:(~)# ll /tmp/
total 16416
drwxr-xr-x 8 root root 4096 May 13 03:24 e2fsprog/
drwx------ 2 root root 4096 May 10 20:58 gconfd-root/
drwx------ 2 stock stock 4096 May 11 04:00 gconfd-stock/
-rw-r--r-- 1 root root 16777216 May 13 01:27 rootmdk92
[tapebox:root]:(~)# losetup /dev/loop0 /tmp/rootmdk92
[tapebox:root]:(~)# mount -t ext2 /dev/loop0 /mnt/floppy
[tapebox:root]:(~)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2772536 2621484 52% /
/dev/ram0 15863 13 15850 1% /mnt/root
/dev/loop0 15863 7351 8512 47% /mnt/floppy
[tapebox:root]:(~)# cd /mnt/floppy/
[tapebox:root]:(/mnt/floppy)# ls
bin/ cdrom/ etc/ lib/ mnt/ root/ tag/ usr/
boot/ dev/ floppy/ lost+found/ proc/ sbin/ tmp/ var/
[tapebox:root]:(/mnt/floppy)# cp -ap bin boot cdrom dev etc floppy lib mnt proc root sbin tag tmp usr var /mnt/root
[tapebox:root]:(/mnt/floppy)# sync
[tapebox:root]:(/mnt/floppy)# sync
[tapebox:root]:(/mnt/floppy)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2772536 2621484 52% /
/dev/ram0 15863 7351 8512 47% /mnt/root
/dev/loop0 15863 7351 8512 47% /mnt/floppy
[tapebox:root]:(/mnt/floppy)# ls /mnt/root/
bin/ cdrom/ etc/ lib/ mnt/ root/ tag/ usr/
boot/ dev/ floppy/ lost+found/ proc/ sbin/ tmp/ var/
[tapebox:root]:(/mnt/floppy)# cd
[tapebox:root]:(~)# sync
[tapebox:root]:(~)# umount /mnt/root
[tapebox:root]:(~)# dd if=/dev/ram0 bs=1k count=16384 | gzip -v9 > /tmp/rootmdk100.gz
16384+0 records in
16384+0 records out
99.8%
[tapebox:root]:(~)# ll /tmp/
total 16444
drwxr-xr-x 8 root root 4096 May 13 03:24 e2fsprog/
drwx------ 2 root root 4096 May 10 20:58 gconfd-root/
drwx------ 2 stock stock 4096 May 11 04:00 gconfd-stock/
-rw-r--r-- 1 root root 27705 May 18 00:44 rootmdk100.gz
-rw-r--r-- 1 root root 16777216 May 13 01:27 rootmdk92
Notice that here already rootmdk100.gz is far too small. We proceed :
[tapebox:root]:(~)# gunzip /tmp/rootmdk100.gz
[tapebox:root]:(~)# losetup /dev/loop1 /tmp/rootmdk100
[tapebox:root]:(~)# mount -t ext2 /dev/loop1 /mnt/cdrom/
[tapebox:root]:(~)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2788940 2605080 52% /
/dev/loop0 15863 7351 8512 47% /mnt/floppy
/dev/loop1 15863 7351 8512 47% /mnt/cdrom
[tapebox:root]:(~)# umount /mnt/cdrom
[tapebox:root]:(~)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2788940 2605080 52% /
/dev/loop0 15863 7351 8512 47% /mnt/floppy
[tapebox:root]:(~)# ls /mnt/floppy/
bin/ cdrom/ etc/ lib/ mnt/ root/ tag/ usr/
boot/ dev/ floppy/ lost+found/ proc/ sbin/ tmp/ var/
[tapebox:root]:(~)# cd /mnt/floppy
[tapebox:root]:(/mnt/floppy)# ll
total 35
drwxr-xr-x 2 root root 1024 Jan 29 02:50 bin/
drwxr-xr-x 2 root root 1024 Nov 22 1996 boot/
drwxr-xr-x 2 root root 1024 Nov 23 1996 cdrom/
drwxr-xr-x 3 root root 8192 Mar 29 2002 dev/
drwxr-xr-x 4 root root 1024 Jan 29 01:41 etc/
drwxr-xr-x 2 root root 1024 May 18 1996 floppy/
drwxr-xr-x 6 root root 2048 Jan 28 18:46 lib/
drwx------ 2 root root 12288 Jan 29 02:44 lost+found/
drwxr-xr-x 2 root root 1024 Jun 24 1995 mnt/
drwxr-xr-x 2 root root 1024 Nov 22 1996 proc/
drwxr-xr-x 2 root root 1024 Nov 24 1995 root/
drwxr-xr-x 2 root root 1024 Jan 28 18:48 sbin/
drwxr-xr-x 2 root root 1024 Jan 30 1994 tag/
drwxrwxrwt 2 root root 1024 Nov 22 1996 tmp/
drwxr-xr-x 6 root root 1024 Mar 25 2000 usr/
drwxr-xr-x 9 root root 1024 Nov 22 1996 var/
[tapebox:root]:(/mnt/floppy)# du -s .
7351 .
[tapebox:root]:(/mnt/floppy)# cd /
[tapebox:root]:(/)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2788940 2605080 52% /
/dev/loop0 15863 7351 8512 47% /mnt/floppy
[tapebox:root]:(/)# losetup /dev/loop0
/dev/loop0: [0302]:376868 (/tmp/rootmdk92)
[tapebox:root]:(/)# losetup /dev/loop1
/dev/loop1: [0302]:369478 (/tmp/rootmdk100)
[tapebox:root]:(/)# umount /mnt/floppy
[tapebox:root]:(/)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2788940 2605080 52% /
[tapebox:root]:(/)# mount -t ext2 /dev/loop1 /mnt/root
[tapebox:root]:(/)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2788940 2605080 52% /
/dev/loop1 15863 7351 8512 47% /mnt/root
[tapebox:root]:(/)# cd /mnt/root/
[tapebox:root]:(/mnt/root)# ll
total 12
drwx------ 2 root root 12288 May 18 00:39 lost+found/
[tapebox:root]:(/mnt/root)# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda2 5682692 2788940 2605080 52% /
/dev/loop1 15863 7351 8512 47% /mnt/root
[tapebox:root]:(/mnt/root)#
So basicly i copied all my files from rootmdk92 to the new rootmdk100 ramdisk.
But after copying them and umounting the old ramdisk (rootmdk92) en deleting
/dev/loop0 , /dev/loop1 (which is /tmp/rootmdk100) loses all its contents.
This is a serious error... anyone know whats wrong?
Robert
--
Robert M. Stockmann - RHCE
Network Engineer - UNIX/Linux Specialist
crashrecovery.org stock@xxxxxxxxxxx
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