From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: [PATCH] COW and checksumming ioctls Date: Fri, 20 Jun 2008 12:37:57 -0400 Message-ID: <1213979877.10187.515.camel@think.oraclecorp.com> References: <1213921608.27507.152.camel@BVR-FS.beaverton.ibm.com> <485B3EC5.8090006@oracle.com> <485BB852.4060202@gentoo.org> <20080620135812.GB3224@unused.rdu.redhat.com> <485BC7AF.6020708@gentoo.org> Mime-Version: 1.0 Content-Type: text/plain Cc: Josef Bacik , Zach Brown , Mingming , linux-btrfs@vger.kernel.org To: Joe Peterson Return-path: In-Reply-To: <485BC7AF.6020708@gentoo.org> List-ID: On Fri, 2008-06-20 at 09:07 -0600, Joe Peterson wrote: > Josef Bacik wrote: > > Database apps that do their own complicated stuff to make sure everything makes > > it to the disk properly who dont want the extra overhead of checksumming. > > I do see the benefit of that, if indeed the DB does end-to-end checking. > Then again, I could almost see that perhaps making the setting based on > something at the subvolume level (not per-file level) might be even > better for that case. > But, it'll be common to mix database files with files that you do want checksummed in the same volume. This is an admin level decision, and we can easily provide knobs to turn it on/off. So, I think the ioctl is really important and we'll just document it as best we can. Long term, these might end up getting folded into chattr, so I think Zach has a good point about folding them into a single change-file-attributes ioctl. -chris