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From: Chao Yu <yuchao0@huawei.com>
To: Gabriel Krisman Bertazi <krisman@collabora.com>,
	<viro@zeniv.linux.org.uk>, <jaegeuk@kernel.org>,
	<chao@kernel.org>
Cc: <linux-fsdevel@vger.kernel.org>,
	<linux-f2fs-devel@lists.sourceforge.net>, <kernel@collabora.com>
Subject: Re: [PATCH 2/2] f2fs: Return EOF on unaligned end of file DIO read
Date: Fri, 21 Aug 2020 09:37:20 +0800	[thread overview]
Message-ID: <1c036ee5-a864-f50d-d439-e2d520e18b32@huawei.com> (raw)
In-Reply-To: <20200819200731.2972195-3-krisman@collabora.com>

On 2020/8/20 4:07, Gabriel Krisman Bertazi wrote:
> Reading past end of file returns EOF for aligned reads but -EINVAL for
> unaligned reads on f2fs.  While documentation is not strict about this
> corner case, most filesystem returns EOF on this case, like iomap
> filesystems.  This patch consolidates the behavior for f2fs, by making
> it return EOF(0).
> 
> it can be verified by a read loop on a file that does a partial read
> before EOF (A file that doesn't end at an aligned address).  The
> following code fails on an unaligned file on f2fs, but not on
> btrfs, ext4, and xfs.
> 
>    while (done < total) {
>      ssize_t delta = pread(fd, buf + done, total - done, off + done);
>      if (!delta)
>        break;
>      ...
>    }
> 
> It is arguable whether filesystems should actually return EOF or
> -EINVAL, but since iomap filesystems support it, and so does the
> original DIO code, it seems reasonable to consolidate on that.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,

      parent reply	other threads:[~2020-08-21  1:37 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-19 20:07 [PATCH 0/2] Consolidate DIO behavior on unaligned EOF read Gabriel Krisman Bertazi
2020-08-19 20:07 ` [PATCH 1/2] direct-io: defer alignment check until after EOF check Gabriel Krisman Bertazi
2020-08-26 14:28   ` Jan Kara
2020-08-19 20:07 ` [PATCH 2/2] f2fs: Return EOF on unaligned end of file DIO read Gabriel Krisman Bertazi
2020-08-20 16:13   ` Jaegeuk Kim
2020-08-21  1:37   ` Chao Yu [this message]

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