linux-kernel - Re: [PATCH 1/1] udf: Fix incorrect final NOT

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Message-ID: <c0c58929-4140-6cdd-77e9-c9c9a43f174d@digidescorp.com>
Date:   Wed, 19 Jun 2019 06:47:10 -0500
From:   Steve Magnani <steve.magnani@...idescorp.com>
To:     Jan Kara <jack@...e.cz>
Cc:     Jan Kara <jack@...e.com>, linux-kernel@...r.kernel.org,
        "Steven J . Magnani" <steve@...idescorp.com>
Subject: Re: [PATCH 1/1] udf: Fix incorrect final NOT_ALLOCATED (hole) extent
 length

On 6/19/19 1:47 AM, Jan Kara wrote:
> Hi Steve!
>
> On Sun 16-06-19 11:28:46, Steve Magnani wrote:
>> On 6/4/19 7:31 AM, Steve Magnani wrote:
>>
>>> In some cases, using the 'truncate' command to extend a UDF file results
>>> in a mismatch between the length of the file's extents (specifically, due
>>> to incorrect length of the final NOT_ALLOCATED extent) and the information
>>> (file) length. The discrepancy can prevent other operating systems
>>> (i.e., Windows 10) from opening the file.
>>>
>>> Two particular errors have been observed when extending a file:
>>>
>>> 1. The final extent is larger than it should be, having been rounded up
>>>      to a multiple of the block size.
>>>
>>> B. The final extent is shorter than it should be, due to not having
>>>      been updated when the file's information length was increased.
>> Wondering if you've seen this, or if something got lost in a spam folder.
> Sorry for not getting to you earlier. I've seen the patches and they look
> reasonable to me. I just wanted to have a one more closer look but last
> weeks were rather busy so I didn't get to it. I'll look into it this week.
> Thanks a lot for debugging the problem and sending the fixes!
>
> 								Honza

No worries. If you're short on time I'd suggest looking first at the ways
udf_do_extend_file() can be called via inode_getblk(). Those were harder for
me to follow so if there is a bug it's most likely in one of those paths.

Regards,
------------------------------------------------------------------------
  Steven J. Magnani               "I claim this network for MARS!
  www.digidescorp.com              Earthling, return my space modulator!"

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