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Re: AIO read returns negative number for bytes read

from [Avi Kivity] [Permanent Link][Original]
To: Alireza Haghdoost <haghdoost@xxxxxxxxx>
Subject: Re: AIO read returns negative number for bytes read
From: Avi Kivity <avi@xxxxxxxxxxxx>
Date: Mon, 16 Nov 2015 17:32:53 +0200
Cc: xfs@xxxxxxxxxxx, linux-aio@xxxxxxxxx
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On 11/16/2015 05:19 PM, Alireza Haghdoost wrote:

On Sun, Nov 15, 2015 at 7:08 AM, Avi Kivity <avi@xxxxxxxxxxxx> wrote:

Due to a bug in my program, I initiated a read beyond eof. Specifically, the
file size is 13002 bytes and the read offset is 13312 (0x3400).

I would expect such a read to return 0 bytes read, but io_getevents returns
-310, which is suspiciously equal to (13002 - 13312).

I attach a reproducer.

4.2.5-201.fc22.x86_64

Are my expectations incorrect, or is this a bug in aio or xfs?

I think it is not a bug. This post might be helpful:
http://marc.info/?l=linux-aio&m=142315449930935&w=2
The post indicates that it is a bug. A negative value indicates an error, but there is no error 310.
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