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SubjectRe: + task_struct-make-journal_info-conditional.patch added to -mm tree
Alexey Dobriyan wrote:
> On Fri, Dec 04, 2009 at 12:58:06PM +0900, Hiroshi Shimamoto wrote:
>> Alexey Dobriyan wrote:
>>> On Thu, Dec 03, 2009 at 02:40:57PM -0800, akpm@linux-foundation.org wrote:
>>>> --- a/include/linux/sched.h~task_struct-make-journal_info-conditional
>>>> +++ a/include/linux/sched.h
>>>> @@ -1452,8 +1452,10 @@ struct task_struct {
>>>> gfp_t lockdep_reclaim_gfp;
>>>> #endif
>>>>
>>>> +#ifdef CONFIG_FS_JOURNAL_INFO
>>>> /* journalling filesystem info */
>>>> void *journal_info;
>>>> +#endif
>>> This will prevent using e.g. ext3 on CONFIG_EXT3_FS=n kernels.
>> I'm sorry, I'm not sure what you're mentioning.
>
> With this patch admin must decide in advance if he will ever use ext3.
> EXT3_FS=n kernels won't be able to get ext3 support without reboot
> even as module, because task_struct will be different.

I see, you want to keep this field for future use even if EXT3_FS=n.
I think, however, there might be a need to remove this because the user
never enable any journaling filesystem.

>
> Which is a regression compared to current state.

I understand it's a regression, so how about make this option Y by
default?

====
From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Subject: [PATCH v2] task_struct: make journal_info conditional

journal_info in task_struct is used in journaling file system only.
So introduce CONFIG_FS_JOURNAL_INFO and make it conditional.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
CC: Chris Mason <chris.mason@oracle.com>
CC: "Theodore Ts'o" <tytso@mit.edu>
CC: Steven Whitehouse <swhiteho@redhat.com>
CC: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
CC: Andrew Morton <akpm@linux-foundation.org>
---
v1->v2: Make FS_JOURNAL_INFO Y by default, and add help document.

fs/Kconfig | 12 ++++++++++++
fs/btrfs/Kconfig | 1 +
fs/ext4/Kconfig | 1 +
fs/gfs2/Kconfig | 1 +
fs/jbd/Kconfig | 1 +
fs/jbd2/Kconfig | 1 +
fs/nilfs2/Kconfig | 1 +
fs/reiserfs/Kconfig | 1 +
include/linux/init_task.h | 8 +++++++-
include/linux/sched.h | 2 ++
10 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/fs/Kconfig b/fs/Kconfig
index 2aa5663..a684c1b 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -6,6 +6,18 @@ menu "File systems"

if BLOCK

+config FS_JOURNAL_INFO
+ bool "Include FS Journal Info in task struct"
+ default y
+ help
+ Include Journal Information in task struct for journaling filesystem.
+ It used in Btrfs, EXT3, EXT4, GFS2, NILFS2 and Reiserfs.
+ If you say N, remove the field for journal info from task struct, it
+ reduces task struct size but disables to support the above journaling
+ filesystems.
+
+ Say Y if unsure.
+
source "fs/ext2/Kconfig"
source "fs/ext3/Kconfig"
source "fs/ext4/Kconfig"
diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 7bb3c02..402afe0 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -4,6 +4,7 @@ config BTRFS_FS
select LIBCRC32C
select ZLIB_INFLATE
select ZLIB_DEFLATE
+ select FS_JOURNAL_INFO
help
Btrfs is a new filesystem with extents, writable snapshotting,
support for multiple devices and many more features.
diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig
index 9f2d45d..464b486 100644
--- a/fs/ext4/Kconfig
+++ b/fs/ext4/Kconfig
@@ -2,6 +2,7 @@ config EXT4_FS
tristate "The Extended 4 (ext4) filesystem"
select JBD2
select CRC16
+ select FS_JOURNAL_INFO
help
This is the next generation of the ext3 filesystem.

diff --git a/fs/gfs2/Kconfig b/fs/gfs2/Kconfig
index 4dcddf8..b192c66 100644
--- a/fs/gfs2/Kconfig
+++ b/fs/gfs2/Kconfig
@@ -10,6 +10,7 @@ config GFS2_FS
select SLOW_WORK
select QUOTA
select QUOTACTL
+ select FS_JOURNAL_INFO
help
A cluster filesystem.

diff --git a/fs/jbd/Kconfig b/fs/jbd/Kconfig
index 4e28bee..a840898 100644
--- a/fs/jbd/Kconfig
+++ b/fs/jbd/Kconfig
@@ -1,5 +1,6 @@
config JBD
tristate
+ select FS_JOURNAL_INFO
help
This is a generic journalling layer for block devices. It is
currently used by the ext3 file system, but it could also be
diff --git a/fs/jbd2/Kconfig b/fs/jbd2/Kconfig
index f32f346..0f7d1ce 100644
--- a/fs/jbd2/Kconfig
+++ b/fs/jbd2/Kconfig
@@ -1,6 +1,7 @@
config JBD2
tristate
select CRC32
+ select FS_JOURNAL_INFO
help
This is a generic journaling layer for block devices that support
both 32-bit and 64-bit block numbers. It is currently used by
diff --git a/fs/nilfs2/Kconfig b/fs/nilfs2/Kconfig
index 251da07..1225af7 100644
--- a/fs/nilfs2/Kconfig
+++ b/fs/nilfs2/Kconfig
@@ -2,6 +2,7 @@ config NILFS2_FS
tristate "NILFS2 file system support (EXPERIMENTAL)"
depends on EXPERIMENTAL
select CRC32
+ select FS_JOURNAL_INFO
help
NILFS2 is a log-structured file system (LFS) supporting continuous
snapshotting. In addition to versioning capability of the entire
diff --git a/fs/reiserfs/Kconfig b/fs/reiserfs/Kconfig
index 513f431..ac7cd75 100644
--- a/fs/reiserfs/Kconfig
+++ b/fs/reiserfs/Kconfig
@@ -1,6 +1,7 @@
config REISERFS_FS
tristate "Reiserfs support"
select CRC32
+ select FS_JOURNAL_INFO
help
Stores not just filenames but the files themselves in a balanced
tree. Uses journalling.
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 8d10aa7..8ed0abf 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -111,6 +111,12 @@ extern struct cred init_cred;
# define INIT_PERF_EVENTS(tsk)
#endif

+#ifdef CONFIG_FS_JOURNAL_INFO
+#define INIT_JOURNAL_INFO .journal_info = NULL,
+#else
+#define INIT_JOURNAL_INFO
+#endif
+
/*
* INIT_TASK is used to set up the first task table, touch at
* your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -162,7 +168,6 @@ extern struct cred init_cred;
.signal = {{0}}}, \
.blocked = {{0}}, \
.alloc_lock = __SPIN_LOCK_UNLOCKED(tsk.alloc_lock), \
- .journal_info = NULL, \
.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
.fs_excl = ATOMIC_INIT(0), \
.pi_lock = __SPIN_LOCK_UNLOCKED(tsk.pi_lock), \
@@ -173,6 +178,7 @@ extern struct cred init_cred;
[PIDTYPE_SID] = INIT_PID_LINK(PIDTYPE_SID), \
}, \
.dirties = INIT_PROP_LOCAL_SINGLE(dirties), \
+ INIT_JOURNAL_INFO \
INIT_IDS \
INIT_PERF_EVENTS(tsk) \
INIT_TRACE_IRQFLAGS \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c13c43e..92b1325 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1452,8 +1452,10 @@ struct task_struct {
gfp_t lockdep_reclaim_gfp;
#endif

+#ifdef CONFIG_FS_JOURNAL_INFO
/* journalling filesystem info */
void *journal_info;
+#endif

/* stacked block device info */
struct bio *bio_list, **bio_tail;
--
1.6.5.5


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