[RFC][PATCH -mm 1/6] Freezer: Do not sync filesystems

Rafael J. Wysocki
2007-07-09T20:31:45Z

From: Rafael J. Wysocki <rjw@sisk.pl>

The syncing of filesystems from within the freezer is generally not needed.
Also, if FUSE implements sync, this will cause the freezer to deadlock with it.

Change freeze_processes() so that it doesn't execute sys_sync() and make the
suspend and hibernation code path sync filesystems independently of the freezer.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
kernel/power/disk.c | 4 ++++
kernel/power/main.c | 6 ++++++
kernel/power/process.c | 1 -
kernel/power/user.c | 4 ++++
4 files changed, 14 insertions(+), 1 deletion(-)

Index: linux-2.6.22-rc6-mm1/kernel/power/disk.c
===================================================================
--- linux-2.6.22-rc6-mm1.orig/kernel/power/disk.c
+++ linux-2.6.22-rc6-mm1/kernel/power/disk.c
@@ -297,6 +297,10 @@ int hibernate(void)
if (error)
goto Exit;

+ printk("Syncing filesystems ... ");
+ sys_sync();
+ printk("done.\n");
+
error = prepare_processes();
if (error)
goto Finish;
Index: linux-2.6.22-rc6-mm1/kernel/power/main.c
===================================================================
--- linux-2.6.22-rc6-mm1.orig/kernel/power/main.c
+++ linux-2.6.22-rc6-mm1/kernel/power/main.c
@@ -20,6 +20,7 @@
#include <linux/resume-trace.h>
#include <linux/freezer.h>
#include <linux/vmstat.h>
+#include <linux/syscalls.h>

#include "power.h"

@@ -234,9 +235,14 @@ static int enter_state(suspend_state_t s

if (!valid_state(state))
return -ENODEV;
+
if (!mutex_trylock(&pm_mutex))
return -EBUSY;

+ printk("Syncing filesystems ... ");
+ sys_sync();
+ printk("done.\n");
+
pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
if ((error = suspend_prepare()))
goto Unlock;
Index: linux-2.6.22-rc6-mm1/kernel/power/process.c
===================================================================
--- linux-2.6.22-rc6-mm1.orig/kernel/power/process.c
+++ linux-2.6.22-rc6-mm1/kernel/power/process.c
@@ -191,7 +191,6 @@ int freeze_processes(void)
if (error)
return error;

- sys_sync();
error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
if (error)
return error;
Index: linux-2.6.22-rc6-mm1/kernel/power/user.c
===================================================================
--- linux-2.6.22-rc6-mm1.orig/kernel/power/user.c
+++ linux-2.6.22-rc6-mm1/kernel/power/user.c
@@ -153,6 +153,10 @@ static int snapshot_ioctl(struct inode *
mutex_lock(&pm_mutex);
error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
if (!error) {
+ printk("Syncing filesystems ... ");
+ sys_sync();
+ printk("done.\n");
+
error = freeze_processes();
if (error)
thaw_processes();