From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Zwisler Subject: Re: block allocator issue with ext4+DAX Date: Thu, 31 Mar 2016 09:13:58 -0600 Message-ID: <20160331151358.GA24866@linux.intel.com> References: <20160330220129.GA9101@linux.intel.com> <20160331085925.GC11041@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ross Zwisler , Theodore Ts'o , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20160331085925.GC11041@quack.suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, Mar 31, 2016 at 10:59:25AM +0200, Jan Kara wrote: > On Wed 30-03-16 16:01:29, Ross Zwisler wrote: > > I've hit an issue in my testing which I believe to be related to the ext4 > > block allocator when using the DAX mount option. I originally found this > > issue with the generic/102 xfstest, but have reduced it to the minimal > > reproducer at the bottom of this email. I've been able to reproduce this with > > both BRD and with PMEM as the underlying block device. > > > > For this test we're running in a very small filesystem, only 512 MiB. We > > fallocate() 400 MiB of that space, unlink the file, then try and rewrite that > > 400 MiB file one chunk at a time. > > > > What actually happens is that during the rewrite we run out of memory and the > > DAX call to get_block() in dax_io() fails with -ENOSPC. > > Yes, I have already sent a fix for this bug here: > > http://www.spinics.net/lists/linux-ext4/msg51649.html > > Ted, can you please pick it up? Thanks! > > Honza Yay! Ted, you can add my Tested-by: Ross Zwisler to that patch. Thanks for the fix, Jan!