From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Desnoyers Subject: Re: [PATCH v11 20/21] ext4: Add DAX functionality Date: Fri, 17 Oct 2014 15:42:02 +0000 (UTC) Message-ID: <2128367244.10915.1413560522748.JavaMail.zimbra@efficios.com> References: <1411677218-29146-1-git-send-email-matthew.r.wilcox@intel.com> <1411677218-29146-21-git-send-email-matthew.r.wilcox@intel.com> <20141016125625.GR19075@thinkos.etherlink> <20141016221624.GL11522@wil.cx> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ross Zwisler To: Matthew Wilcox Return-path: In-Reply-To: <20141016221624.GL11522@wil.cx> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org ----- Original Message ----- > From: "Matthew Wilcox" > To: "Mathieu Desnoyers" > Cc: "Matthew Wilcox" , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, > linux-kernel@vger.kernel.org, "Ross Zwisler" > Sent: Friday, October 17, 2014 12:16:24 AM > Subject: Re: [PATCH v11 20/21] ext4: Add DAX functionality > [...] > On Thu, Oct 16, 2014 at 02:56:25PM +0200, Mathieu Desnoyers wrote: > > > @@ -3572,6 +3579,11 @@ static int ext4_fill_super(struct super_block *sb, > > > void *data, int silent) > > > "both data=journal and dioread_nolock"); > > > goto failed_mount; > > > } > > > + if (test_opt(sb, DAX)) { > > > + ext4_msg(sb, KERN_ERR, "can't mount with " > > > + "both data=journal and dax"); > > > > This limitation regarding ext4 and dax should be documented in dax > > Documentation. > > Maybe the ext4 documentation too? It seems kind of obvious to me that if > ypu're enabling in-place-updates that you can't journal the data you're > updating (well ... you could implement undo-log journalling, I suppose, > which would be quite a change for ext4) Yes, we could document this limitation in general for all journalling FS within DAX documentation, and then document it specifically per-FS in the FS documentation. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org