Hi, Eric
On Tue, Jul 8, 2008 at 4:15 AM, Eric Sandeen <sandeen@xxxxxxxxxx> 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 <sandeen@xxxxxxxxxx>
> ---
>
> 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);
>
>
> --
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--
RGDS
Bergwolf
................
Here lieth one whose name was writ on water.
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