From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1462376543.27137.71.camel@hpe.com> Subject: Re: [PATCH v2 1/3] ext4: Add alignment check for DAX mount From: Toshi Kani To: Ross Zwisler , Jan Kara , Christoph Hellwig Cc: "tytso@mit.edu" , "linux-nvdimm@ml01.01.org" , "david@fromorbit.com" , "linux-kernel@vger.kernel.org" , "Parrish, Micah (HP Servers Linux R&D)" , "adilger.kernel@dilger.ca" , "linux-fsdevel@vger.kernel.org" Date: Wed, 04 May 2016 09:42:23 -0600 In-Reply-To: <1462290096.27137.47.camel@hpe.com> References: <1462214578-27122-1-git-send-email-toshi.kani@hpe.com> <1462214578-27122-2-git-send-email-toshi.kani@hpe.com> <20160503084410.GB31363@infradead.org> <20160503090021.GC12748@quack2.suse.cz> <20160503144352.GA27470@linux.intel.com> <1462290096.27137.47.camel@hpe.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: On Tue, 2016-05-03 at 15:41 +0000, Kani, Toshimitsu wrote: > On Tue, 2016-05-03 at 08:43 -0600, Ross Zwisler wrote: > > On Tue, May 03, 2016 at 11:00:21AM +0200, Jan Kara wrote: > > > On Tue 03-05-16 01:44:10, Christoph Hellwig wrote: > > > > > > > > Please come up with a version that doesn't require tons of > > > > boilerplate code in every file system. > > > > > > Well, I was thinking about some helper as well but we could save ~4 > > > lines with that and that didn't seem significant to me. Most of the > > > lines is actually reporting appropriate mount error in dmesg and that > > > is fs-dependent so it needs to stay in the filesystem... So what do > > > you have in mind? > > > > I guess if you wanted to reduce the code needed in each filesystem, you > > could avoid having different error messages for each of the failure > > conditions, and just print the error value.  All the error cases caught > > by the current code are unique, so we aren't losing any > > information.  The resulting patch for ext4 would look like this: > > I'd prefer to keep the "error: device does not support dax" and "error: > unaligned partition for dax" messages since they clarify the problem as a > user error. The former case is especially common with BTT. The "error: > dax access failed (%d)" message is helpful when we need to look into the > case. > > If XFS is OK to use the messages similar to ext2/4, then we can do:  > >  * Add a new helper function, say bdev_check_dax_mount(), which logs > common error messages with pr_err(), such as: >        "VFS (pmem0): error: device does not support dax" >  * When bdev_check_dax_mount() returns with a negative value: >    - XFS logs an additional message below via xfs_alert() and proceeds > without dax option. >        "XFS (pmem0): Turning DAX off." >    - ext2/4 fails the mount. Since v2 got multiple reviews, and Jan has added 2/3 into his tree (thanks!), I will send "[PATCH v2-UPDATE 3/3]" which addresses Ross's comments on v2 patch 3/3.  This keeps the v2 series. Christoph, let me know if you'd still like to see v3 with the above changes to share the same error messages among ext2/4 and xfs. Thanks, -Toshi