linux-kernel - Re: [PATCH 2/4] configfs: Fix writing at a non-zero offset

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Message-ID: <d12f24b6-7066-f9bb-1b88-6cc23c9c45c1@acm.org>
Date:   Mon, 26 Jul 2021 09:26:49 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Bodo Stroesser <bostroesser@...il.com>,
        Christoph Hellwig <hch@....de>
Cc:     Joel Becker <jlbec@...lplan.org>, linux-kernel@...r.kernel.org,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Yanko Kaneti <yaneti@...lera.com>,
        Brendan Higgins <brendanhiggins@...gle.com>
Subject: Re: [PATCH 2/4] configfs: Fix writing at a non-zero offset

On 7/26/21 7:58 AM, Bodo Stroesser wrote:
> On 23.07.21 23:23, Bart Van Assche wrote:
> Let's say user writes 5 times to configfs file while keeping it open.
> On every write() call it writes 1 character only, e.g. first "A", then 
> "B", ...
> 
> The original code before the changes 5 times called flush_write_buffer 
> for the
> strings "A\0", "B\0", ... (with the '\0' not included in the count 
> parameter,
> so count is 1 always, which is the length of the last write).

Isn't that behavior a severe violation of how POSIX specifies that the 
write() system call should be implemented?

Thanks,

Bart.