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Date: Mon, 07 Jul 2008 15:15:16 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: ext4 development <linux-ext4@...r.kernel.org>
Subject: [PATCH] do not set extents feature from the kernel
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 seem like a decent approach?
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---
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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