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Date: Wed, 30 Aug 2017 16:37:04 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Christoph Hellwig <hch@lst.de>
Cc: arve@android.com, riandrews@android.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 05/16] fs: fix kernel_read prototype
Message-ID: <20170830153704.GN5426@ZenIV.linux.org.uk>
References: <20170830150007.3953-1-hch@lst.de>
 <20170830150007.3953-6-hch@lst.de>
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On Wed, Aug 30, 2017 at 04:59:56PM +0200, Christoph Hellwig wrote:
> Use proper ssize_t and size_t types for the return value and count
> argument,  move the offset last and make it an in/out argument like
> all other read/write helpers.

Might be better to switch the third argument to void * at the same time
and lose those casts.

>  			if (p)
>  				memcpy(p + offset, buf, n);
> -
> -			offset += n;

Almost certainly broken - in effect, you've taken the update of offset
several lines prior, so that memcpy() is getting the wrong first argument.
The same needs to be watched out for in other similar places.