Re: [PATCH] btrfs: Return right extent when fiemap gives unaligned offset and len.

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

-------- Original Message --------
Subject: Re: [PATCH] btrfs: Return right extent when fiemap gives 
unaligned offset and len.
From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: 2014年07月24日 20:17
> On Fri, Jul 18, 2014 at 09:55:43AM +0800, Qu Wenruo wrote:
>> When page aligned start and len passed to extent_fiemap(), the result is
>> good, but when start and len is not aligned, e.g. start = 1 and len =
>> 4095 is passed to extent_fiemap(), it returns no extent.
>>
>> The problem is that start and len is all rounded down which causes the
>> problem.
> ALIGN rounds up, not down. So the wrong rounding will use incorrect start
> (4096) and finds no extents if there's eg. only one [0,4095].
Sorry for the wrong description in patch.
Should I reword the patch and send a v2 patch?

Thanks,
Qu
>
>> This patch will round down start and round up (start + len) to
>> return right extent.
>>
>> Reported-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> Reviewed-by: David Sterba <dsterba@suse.cz>