From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Date: Fri, 11 Jul 2008 12:52:19 +0100 Subject: [Cluster-devel] Re: [PATCH 17/18] [GFS2] Remove support for unused and pointless flag In-Reply-To: References: <121577107950-git-send-email-swhiteho@redhat.com> <12157710872782-git-send-email-swhiteho@redhat.com> <1215771089769-git-send-email-swhiteho@redhat.com> <1215771091790-git-send-email-swhiteho@redhat.com> <12157710931623-git-send-email-swhiteho@redhat.com> <12157710954145-git-send-email-swhiteho@redhat.com> <12157710973601-git-send-email-swhiteho@redhat.com> <12157710983282-git-send-email-swhiteho@redhat.com> <12157711013356-git-send-email-swhiteho@redhat.com> <12157711023743-git-send-email-swhiteho@redhat.com> <12157711041157-git-send-email-swhiteho@redhat.com> <1215771106247-git-send-email-swhiteho@redhat.com> <12157711073280-git-send-email-swhiteho@redhat.com> <12157711093284-git-send-email-swhiteho@redhat.com> <12157711133727-git-send-email-swhiteho@redhat.com> <12157711153366-git-send-email-swhiteho@redhat.com> <12157711171692-git-send-email-swhiteho@redhat.com> <1215771119431-git-send-email-swhiteho@redhat.com> Message-ID: <1215777139.4011.188.camel@quoit> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, On Fri, 2008-07-11 at 07:19 -0400, linux-os (Dick Johnson) wrote: > On Fri, 11 Jul 2008 swhiteho at redhat.com wrote: > > > From: Steven Whitehouse > > > > The ability to mark files for direct i/o access when opened > > normally is both unused and pointless, so this patch removes > > support for that feature. > [Snipped...] > > So linux is no longer going to support commercial databases? > Oracle and others need the O_DIRECT attribute. Linux can > probably igonore it, but such an open cannot fail or else > Linux gets thrown out of the commercial enterprise when > an upgrade disables an entire financial institution. > > Cheers, > Dick Johnson > Penguin : Linux version 2.6.22.1 on an i686 machine (5588.28 BogoMips). > My book : http://www.AbominableFirebug.com/ > _ > No, thats not what it means...., but perhaps I could have explained it better. You can still use O_DIRECT flags in open syscalls in exactly the same way as before. What this patch removes is the (never used, and IMHO pointless) feature of being able to set a flag on the inode (via chattr/setattr) to force open's to set O_DIRECT in every case, even when the application didn't ask for it. The reason that its pointless is that applications which don't otherwise support O_DIRECT are very unlikely to supply suitably aligned buffers and I/O requests, so that overriding the O_DIRECT flag for such applications will most likely result in an I/O error. GFS2 will still support O_DIRECT just the same as it has always done, and this doesn't affect any other filesystem's support for that feature either, Steve.