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Message-ID: <516F1C8A.9040702@redhat.com>
Date: Wed, 17 Apr 2013 15:04:58 -0700
From: Eric Sandeen <sandeen@...hat.com>
To: ext4 development <linux-ext4@...r.kernel.org>
Subject: [PATCH] mke2fs: add discard to default mke2fs.conf and disable by
default
Discard is a very big hammer. If it succeeds, there's no undo
or going back; on the other hand, on some devices the giant discard
issued at mkfs time makes them go offline. :(
Although I'm reluctant to waffle back and forth on default behavior,
I think this disabling it by default the prudent thing to do.
This patch also adds the discard option into the default mke2fs.conf
file; although it could be set, it was not in the template.
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---
If disabling by default isn't desired, we should at least include
the mke2fs.conf.in change (set to 1).
Thanks,
-Eric
diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
index 023ba49..a005eca 100644
--- a/misc/mke2fs.8.in
+++ b/misc/mke2fs.8.in
@@ -277,11 +277,11 @@ Attempt to discard blocks at mkfs time (discarding blocks initially is useful
on solid state devices and sparse / thin-provisioned storage). When the device
advertises that discard also zeroes data (any subsequent read after the discard
and before write returns zero), then mark all not-yet-zeroed inode tables as
-zeroed. This significantly speeds up filesystem initialization. This is set
-as default.
+zeroed. This significantly speeds up filesystem initialization. This is disabled
+by default.
.TP
.BI nodiscard
-Do not attempt to discard blocks at mkfs time.
+Do not attempt to discard blocks at mkfs time. This is the default.
.TP
.BI quotatype
Specify which quota type ('usr' or 'grp') is to be initialized. This
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index bbf477a..d723ee7 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -84,7 +84,7 @@ int cflag;
int verbose;
int quiet;
int super_only;
-int discard = 1; /* attempt to discard device before fs creation */
+int discard; /* attempt to discard device before fs creation? */
int direct_io;
int force;
int noaction;
diff --git a/misc/mke2fs.conf.in b/misc/mke2fs.conf.in
index 178733f..db6decb 100644
--- a/misc/mke2fs.conf.in
+++ b/misc/mke2fs.conf.in
@@ -2,6 +2,7 @@
base_features = sparse_super,filetype,resize_inode,dir_index,ext_attr
default_mntopts = acl,user_xattr
enable_periodic_fsck = 0
+ discard = 0
blocksize = 4096
inode_size = 256
inode_ratio = 16384
--
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