From: Ross Zwisler Subject: Re: [PATCH 2/7] dax: Add sync argument to dax_iomap_fault() Date: Thu, 27 Jul 2017 16:06:37 -0600 Message-ID: <20170727220637.GC22000@linux.intel.com> References: <20170727131245.28279-1-jack@suse.cz> <20170727131245.28279-3-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Christoph Hellwig , linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, Dave Chinner , linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andy Lutomirski , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20170727131245.28279-3-jack-AlSwsSmVLrQ@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 Thu, Jul 27, 2017 at 03:12:40PM +0200, Jan Kara wrote: > Add 'sync' argument to dax_iomap_fault(). It will be used to communicate > the fact that synchronous fault is requested. I don't actually think you need to pass this 'sync' parameter around. I think you can completely rely on IOMAP_F_NEEDSYNC being set in iomap.flags. The DAX fault handlers can call ops->iomap_begin() and use that flag for all the tests and make it our once source of truth. That flag also tells us that we are doing a write fault (from ext4_iomap_begin()): if ((flags & IOMAP_FAULT) && (flags & IOMAP_WRITE) && IS_SYNC(inode) && !jbd2_transaction_committed(EXT4_SB(inode->i_sb)->s_journal, EXT4_I(inode)->i_datasync_tid)) iomap->flags |= IOMAP_F_NEEDDSYNC; So conditionals like this from dax_iomap_pte_fault(): force_ro = (vmf->flags & FAULT_FLAG_WRITE) && sync && (iomap.flags & IOMAP_F_NEEDDSYNC); can be simplified to: force_ro = (iomap.flags & IOMAP_F_NEEDDSYNC);