linux-ext4 - Re: [RESEND][PATCH][BUG] ext4: fix infinite loop at ext4_da_writepages with the terminal extent block of too big file

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Message-ID: <4C93717B.2020401@redhat.com>
Date:	Fri, 17 Sep 2010 08:47:39 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Dmitry Monakhov <dmonakhov@...nvz.org>
CC:	Toshiyuki Okajima <toshi.okajima@...fujitsu.com>, tytso@....edu,
	adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org
Subject: Re: [RESEND][PATCH][BUG] ext4: fix infinite loop at ext4_da_writepages
 with the terminal extent block of too big file

Dmitry Monakhov wrote:
> Toshiyuki Okajima <toshi.okajima@...fujitsu.com> writes:
> 
>> From: Toshiyuki Okajima <toshi.okajima@...fujitsu.com>
>>
>> On linux-2.6.36-rc2, if we execute the following script, we can encounter 
>> the hangup of '/bin/sync' command:
>> ================================================================================
>> #!/bin/sh
>>
>> echo -n "HANG UP TEST: "
>> /bin/dd if=/dev/zero of=/tmp/img bs=1k count=1 seek=1M 2> /dev/null
>> /sbin/mkfs.ext4 -Fq /tmp/img
>> /bin/mount -o loop -t ext4 /tmp/img /mnt
>> /bin/dd if=/dev/zero of=/mnt/file bs=1 count=1 \
>> seek=$((16*1024*1024*1024*1024-4096)) 2> /dev/null
>> /bin/sync
>> /bin/umount /mnt
>> echo "DONE"
>> exit 0
> On older kernels this testcase result in BUG_ON triggering
> at fs/ext4/mballoc.c:3229 ext4_mb_normalize_request()

If anyone feels up to the task, extending xfstest 071
("# Exercise IO at large file offsets.") to work on generic kernels,
it would have caught this earlier.  It needs work, however, configure
expected max offsets for various filesystems...

-Eric
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