From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759406AbZBLROc (ORCPT ); Thu, 12 Feb 2009 12:14:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757332AbZBLROY (ORCPT ); Thu, 12 Feb 2009 12:14:24 -0500 Received: from mx2.redhat.com ([66.187.237.31]:56558 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756806AbZBLROX (ORCPT ); Thu, 12 Feb 2009 12:14:23 -0500 Message-ID: <499458C1.90105@redhat.com> Date: Thu, 12 Feb 2009 11:13:37 -0600 From: Eric Sandeen User-Agent: Thunderbird 2.0.0.19 (Macintosh/20081209) MIME-Version: 1.0 To: =?ISO-8859-1?Q?Fernando_Luis_V=E1zquez_Cao?= CC: Jan Kara , Theodore Tso , Alan Cox , Pavel Machek , kernel list , Jens Axboe , fernando@kic.ac.jp, Ric Wheeler Subject: Re: vfs: Add MS_FLUSHONFSYNC mount flag References: <20090114165952.GH6222@mit.edu> <1232021211.14626.19.camel@sebastian.kern.oss.ntt.co.jp> <20090115234544.GA7579@duck.suse.cz> <1232109069.13775.35.camel@sebastian.kern.oss.ntt.co.jp> <1232114101.13775.63.camel@sebastian.kern.oss.ntt.co.jp> <20090116163039.GE10617@duck.suse.cz> <1232185639.4831.18.camel@sebastian.kern.oss.ntt.co.jp> <1232186449.4831.29.camel@sebastian.kern.oss.ntt.co.jp> <20090119120349.GA10193@duck.suse.cz> <1233135913.5399.57.camel@sebastian.kern.oss.ntt.co.jp> <20090128095518.GA16554@duck.suse.cz> <1234434811.15270.7.camel@sebastian.kern.oss.ntt.co.jp> <1234434970.15433.4.camel@sebastian.kern.oss.ntt.co.jp> In-Reply-To: <1234434970.15433.4.camel@sebastian.kern.oss.ntt.co.jp> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fernando Luis Vázquez Cao wrote: > This mount flag will be used to determine whether the block device's write > cache should be flush or not on fsync()/fdatasync(). > > Signed-off-by: Fernando Luis Vazquez Cao > --- Again, apologies for chiming in late. But wouldn't it be better to make this a block device property rather than a new filesystem mount option? That way the filesystem can always do "the right thing" and call the blkdev flush on fsync. The block device *could* choose to ignore this in hardware if it knows it's built with a nonvolatile write cache or if it has no write cache. Somewhere in the middle, if an administrator knows they have a UPS they trust and hardware that stays connected to it, they could tune the bdev to ignore these flush requests. Also that way if you have 8 partitions on a battery-backed blockdev, you can tune it once, instead of needing to mount all 8 filesystems with the new option. Thoughts? Thanks, -Eric > diff -urNp linux-2.6.29-rc3-orig/fs/namespace.c linux-2.6.29-rc3/fs/namespace.c > --- linux-2.6.29-rc3-orig/fs/namespace.c 2009-01-29 09:47:51.000000000 +0900 > +++ linux-2.6.29-rc3/fs/namespace.c 2009-01-29 18:40:04.000000000 +0900 > @@ -1933,8 +1933,8 @@ long do_mount(char *dev_name, char *dir_ > if (flags & MS_RDONLY) > mnt_flags |= MNT_READONLY; > > - flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | > - MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT); > + flags &= ~(MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_NOATIME | > + MS_NODIRATIME | MS_RELATIME | MS_ACTIVE | MS_KERNMOUNT); > > /* ... and get the mountpoint */ > retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); > diff -urNp linux-2.6.29-rc3-orig/include/linux/fs.h linux-2.6.29-rc3/include/linux/fs.h > --- linux-2.6.29-rc3-orig/include/linux/fs.h 2009-01-29 10:04:18.000000000 +0900 > +++ linux-2.6.29-rc3/include/linux/fs.h 2009-01-29 10:24:14.000000000 +0900 > @@ -135,6 +135,8 @@ struct inodes_stat_t { > #define MS_RELATIME (1<<21) /* Update atime relative to mtime/ctime. */ > #define MS_KERNMOUNT (1<<22) /* this is a kern_mount call */ > #define MS_I_VERSION (1<<23) /* Update inode I_version field */ > +#define MS_FLUSHONFSYNC (1<<24) /* Force block device flush on > + fsync()/fdatasync() */ > #define MS_ACTIVE (1<<30) > #define MS_NOUSER (1<<31) > > >