From: "Peng tao" Subject: Re: [PATCH] do not set extents feature from the kernel Date: Tue, 8 Jul 2008 10:23:28 +0800 Message-ID: <6149e97b0807071923t62379bf0qc682c6cbc15e1380@mail.gmail.com> References: <48727954.1080406@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: "ext4 development" To: "Eric Sandeen" Return-path: Received: from wa-out-1112.google.com ([209.85.146.180]:58986 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755408AbYGHCXf (ORCPT ); Mon, 7 Jul 2008 22:23:35 -0400 Received: by wa-out-1112.google.com with SMTP id j37so1505056waf.23 for ; Mon, 07 Jul 2008 19:23:28 -0700 (PDT) In-Reply-To: <48727954.1080406@redhat.com> Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi, Eric On Tue, Jul 8, 2008 at 4:15 AM, Eric Sandeen wrote: > We've talked for a while about getting rid of any feature- > setting from the kernel; this gets rid of the code which would > set the INCOMPAT_EXTENTS flag on the first file write when mounted > as ext4[dev]. > > With this patch, if the extents feature is not already set on disk, > then mounting as ext4 will fall back to noextents with a warning, > and if -o extents is explicitly requested, the mount will fail, > also with warning. Does this mean no more migration from ext3 to ext4? > > Does this seem like a decent approach? > > Signed-off-by: Eric Sandeen > --- > > Index: linux-2.6/fs/ext4/ialloc.c > =================================================================== > --- linux-2.6.orig/fs/ext4/ialloc.c 2008-07-07 10:22:00.000000000 -0500 > +++ linux-2.6/fs/ext4/ialloc.c 2008-07-07 12:07:02.133292077 -0500 > @@ -740,14 +740,10 @@ got: > goto fail_free_drop; > > if (test_opt(sb, EXTENTS)) { > - /* set extent flag only for diretory, file and normal symlink*/ > + /* set extent flag only for directory, file and normal symlink*/ > if (S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode)) { > EXT4_I(inode)->i_flags |= EXT4_EXTENTS_FL; > ext4_ext_tree_init(handle, inode); > - err = ext4_update_incompat_feature(handle, sb, > - EXT4_FEATURE_INCOMPAT_EXTENTS); > - if (err) > - goto fail_free_drop; > } > } > > Index: linux-2.6/fs/ext4/super.c > =================================================================== > --- linux-2.6.orig/fs/ext4/super.c 2008-07-07 10:22:19.000000000 -0500 > +++ linux-2.6/fs/ext4/super.c 2008-07-07 14:08:43.684291817 -0500 > @@ -1309,6 +1309,13 @@ set_qf_format: > clear_opt(sbi->s_mount_opt, NOBH); > break; > case Opt_extents: > + if (!EXT4_HAS_INCOMPAT_FEATURE(sb, > + EXT4_FEATURE_INCOMPAT_EXTENTS)) { > + ext4_warning(sb, __func__, > + "extents feature not enabled " > + "on this filesystem, use tune2fs\n"); > + return 0; > + } > set_opt (sbi->s_mount_opt, EXTENTS); > break; > case Opt_noextents: > @@ -1919,12 +1926,18 @@ static int ext4_fill_super (struct super > > /* > * turn on extents feature by default in ext4 filesystem > - * User -o noextents to turn it off > + * only if feature flag already set by mkfs or tune2fs. > + * Use -o noextents to turn it off > */ > - set_opt(sbi->s_mount_opt, EXTENTS); > + if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) > + set_opt(sbi->s_mount_opt, EXTENTS); > + else > + ext4_warning(sb, __func__, > + "extents feature not enabled on this filesystem, " > + "use tune2fs.\n"); > /* > - * turn on mballoc feature by default in ext4 filesystem > - * User -o nomballoc to turn it off > + * turn on mballoc code by default in ext4 filesystem > + * Use -o nomballoc to turn it off > */ > set_opt(sbi->s_mount_opt, MBALLOC); > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- RGDS Bergwolf ................ Here lieth one whose name was writ on water.