From: Huaisheng Ye Subject: Re: [PATCH 2/3] fs/ext2/inode: Fix a type cast error for fsdax Date: Mon, 02 Jul 2018 14:23:42 +0800 Message-ID: <16459a9432e.10c419704327.5268154349116077352@zoho.com> References: <20180701061848.7036-1-yehs2007@zoho.com> <20180701061848.7036-2-yehs2007@zoho.com> <20180701192600.GT30522@ZenIV.linux.org.uk> Reply-To: yehs2007-ytc+IHgoah0@public.gmane.org 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: "\"Al Viro\"" Return-path: In-Reply-To: <20180701192600.GT30522-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@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 Mon, 02 Jul 2018 03:26:00 +0800 Al Viro wrote ---- > 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? Sorry for my inaccuracy. The type of iomap->offset is loff_t, is it better to cast first_block to loff_t, then do the left shift operation? > > > - iomap->offset = (u64)first_block << blkbits; > > + iomap->offset = (loff_t)first_block << blkbits; > --- Cheers, Huaisheng