From: Al Viro Subject: Re: [PATCH 2/3] fs/ext2/inode: Fix a type cast error for fsdax Date: Sun, 1 Jul 2018 20:26:00 +0100 Message-ID: <20180701192600.GT30522@ZenIV.linux.org.uk> References: <20180701061848.7036-1-yehs2007@zoho.com> <20180701061848.7036-2-yehs2007@zoho.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, chengnt-6jq1YtArVR3QT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, jack-IBi9RG/b67k@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Huaisheng Ye Return-path: Content-Disposition: inline In-Reply-To: <20180701061848.7036-2-yehs2007-ytc+IHgoah0@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org On Sun, Jul 01, 2018 at 02:18:47PM +0800, Huaisheng Ye wrote: > From: Huaisheng Ye > > The type of offset within struct iomap is loff_t, which represents > file offset of mapping. > > In ext2_iomap_begin, iomap->offset shall be given a type cast as > loff_t instead of u64. Why is it an error? loff_t is uniformly typedefed to long long. In which case the second variant is different from the first one *and* does not step into nasal demon territory? > - iomap->offset = (u64)first_block << blkbits; > + iomap->offset = (loff_t)first_block << blkbits;