From: David Sterba Subject: Re: [RFC PATCH 1/5] new helper: iov_iter_rw() Date: Tue, 17 Mar 2015 10:31:51 +0100 Message-ID: <20150317093151.GS20767@twin.jikos.cz> References: <34dc78b262546e9343e0ed872232a97f5eaa5f15.1426502566.git.osandov@osandov.com> <20150316173605.GX29656@ZenIV.linux.org.uk> Reply-To: dsterba@suse.cz Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Omar Sandoval , linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org, osd-dev@open-osd.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, fuse-devel@lists.sourceforge.net, cluster-devel@redhat.com, jfs-discussion@lists.sourceforge.net, HPDD-discuss@ml01.01.org, linux-nfs@vger.kernel.org, linux-nilfs@vger.kernel.org, ocfs2-devel@oss.oracle.com, reiserfs-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, xfs@oss.sgi.com, linux-kernel@vger.kernel.org, Chris Mason , Josef Bacik , David Sterba , Yan Zheng , Sage Weil , Steve French , Boaz Harrosh , Benny Halevy , Jan Kara , Theodore Ts'o , A To: Al Viro Return-path: Content-Disposition: inline In-Reply-To: <20150316173605.GX29656@ZenIV.linux.org.uk> Sender: linux-btrfs-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, Mar 16, 2015 at 05:36:05PM +0000, Al Viro wrote: > On Mon, Mar 16, 2015 at 04:33:49AM -0700, Omar Sandoval wrote: > > Get either READ or WRITE out of iter->type. > > Umm... > > > + * Get one of READ or WRITE out of iter->type without any other flags OR'd in > > + * with it. > > + */ > > +static inline int iov_iter_rw(const struct iov_iter *i) > > +{ > > + return i->type & RW_MASK; > > +} > > TBH, I would turn that into a macro. Reason: indirect includes. Agreed, but the proposed define is rather cryptic and I was not able to understand the meaning on the first glance. > #define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & RW_MASK) This worked for me, does not compile with anything else than 'struct iov_iter*' as i: #define iov_iter_rw(i) ({ \ struct iov_iter __iter = *(i); \ (i)->type & RW_MASK; \ }) The assignment is optimized out.