linux-kernel - Re: ext4 iomap SEEK broken [was: [GIT PULL] ext4 updates for 4.15]

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Message-ID: <8f689031-af4a-e927-3fe1-1498b87f28b1@suse.cz>
Date:   Mon, 12 Feb 2018 21:23:10 +0100
From:   Jiri Slaby <jslaby@...e.cz>
To:     Theodore Ts'o <tytso@....edu>, linux-kernel@...r.kernel.org,
        linux-ext4@...r.kernel.org, Christoph Hellwig <hch@...radead.org>
Subject: Re: ext4 iomap SEEK broken [was: [GIT PULL] ext4 updates for 4.15]

On 02/12/2018, 05:10 PM, Theodore Ts'o wrote:
> On Mon, Feb 12, 2018 at 01:14:07PM +0100, Jiri Slaby wrote:
>> On 02/12/2018, 11:02 AM, Jiri Slaby wrote:
>>> Given this happens only on 32bit kernel, I assume some 32bit overflow.
>>> But I am unable to see it (yet).
>>
>> Just to add, a diff of strace in good and bad kernels:
>> @@ -655,14 +655,4 @@
>>  _llseek(3, 4275568640, [4286054400], SEEK_DATA) = 0
>>  _llseek(3, 4286054400, [4288675840], SEEK_HOLE) = 0
>>  _llseek(3, 4288675840, [4299161600], SEEK_DATA) = 0
>> -_llseek(3, 4299161600, [4301783040], SEEK_HOLE) = 0
>> +_llseek(3, 4299161600, [4299161600], SEEK_HOLE) = 2621440
>>
>> llseek returns a very invalid value when it comes to 0x100400000.
> 
> Thanks for the bugreport!  Can you send me the output of "filefrag -v"
> on the file so I can make sure we can exactly replicate what you're
> seeing?

Sure, attaching.

thanks,
-- 
js
suse labs

View attachment "filefrag.txt" of type "text/plain" (149447 bytes)