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FS corruption with 8 exabyte sized file.

To: linux-xfs@xxxxxxxxxxx
Subject: FS corruption with 8 exabyte sized file.
From: utz lehmann <xfs@xxxxxxxxxx>
Date: Tue, 16 Oct 2001 03:14:50 +0200
In-reply-to: <20011015161900.A3432@bistro.marx>
References: <Pine.LNX.4.21.0110150332421.1797-100000@ctgw.lbsd.net> <1003172400.4680.2.camel@stout.americas.sgi.com> <20011015161900.A3432@bistro.marx>
Sender: owner-linux-xfs@xxxxxxxxxxx
User-agent: Mutt/1.2.5i
Hi

pac@xxxxxxxxxxxxxx [pac@xxxxxxxxxxxxxx] wrote:
> * The maximum accessible file offset of a Linux XFS file is 16 Terabytes on 4K
>   page size and 64 Terabytes on 16K page size. 

Is this true?
I was able to create up to 8 exabyte sized files (with a big hole). But it
produces fs corruption.


[root@segv /root]# mkfs.xfs -f /dev/hda4
meta-data=/dev/hda4              isize=256    agcount=8, agsize=63256 blks
data     =                       bsize=4096   blocks=506047, imaxpct=25
         =                       sunit=0      swidth=0 blks, unwritten=0
naming   =version 2              bsize=4096  
log      =internal log           bsize=4096   blocks=1200
realtime =none                   extsz=65536  blocks=0, rtextents=0
[root@segv /root]# mount /dev/hda4 /mnt/
[root@segv /root]# cd /mnt/
[root@segv /mnt]# seq 1 100 | dd of=BIG1 bs=1024 seek=9007199254740991
0+1 records in
0+1 records out
[root@segv /mnt]# ls -l
total 4
-rw-r--r--    1 root     root     9223372036854775076 Oct 16 02:26 BIG1
[root@segv /mnt]# ls -lh
total 4.0k
-rw-r--r--    1 root     root         8.0E Oct 16 02:26 BIG1
[root@segv /mnt]# tail BIG1 
91
92
93
94
95
96
97
98
99
100
[root@segv /mnt]# 

looks good so far.


[root@segv /mnt]# cd
[root@segv /root]# umount /mnt/
[root@segv /root]# xfs_check /dev/hda4
bad agf magic # 0 in ag 0
bad agf version # 0 in ag 0
block 0/0 expected type unknown got sb
bad agi magic # 0 in ag 0
bad agi version # 0 in ag 0
bad magic # 0x58465342 in btbno block 0/0
bad magic # 0x58465342 in btcnt block 0/0
bad magic # 0x58465342 in inobt block 0/0
agi unlinked bucket 0 is 0 in ag 0 (inode=0)
agi unlinked bucket 1 is 0 in ag 0 (inode=0)
agi unlinked bucket 2 is 0 in ag 0 (inode=0)
[...]
agi unlinked bucket 61 is 0 in ag 0 (inode=0)
agi unlinked bucket 62 is 0 in ag 0 (inode=0)
agi unlinked bucket 63 is 0 in ag 0 (inode=0)


I first tried it on my system partition. It trap in kdb (X running and no
serial console). recovery crashed. xfs_repair from the 1.0.1 installer
repaired it. 465 files from 221237 were in lost+found, most from kernel
sources and a few from tuxracer. I verify the system with rpm -Va, looks
good so far. A good working repair tool is great!


Then i tried this with some kernel versions on a spare partition (hda4).

2.4.10 till todays CVS had this fs corruption.

2.4.2 till 2.4.10-pre13 had "Bad write on page 0xc13110cc0" (address varies)
errors on umount but no corruption.

All kernels were compiled with kgcc. System is a K6-500 256MB RAM.


utz


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