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

[Eric Sandeen <sandeen@redhat.com>]

Dmitry Monakhov wrote:
> Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> writes:
> 
>> From: Toshiyuki Okajima <toshi.okajima@jp.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