freezer: do not sync filesystems from freeze_processes

The syncing of filesystems from within the freezer is generally not needed.
Also, if there's an ext3 filesystem loopback-mounted from a FUSE one, the
syncing results in writes to it and deadlocks.  Similarly, it will deadlock if
FUSE implements sync.

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>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/power/user.c b/kernel/power/user.c
index bd0723a7df3f..5bd321bcbb75 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -153,6 +153,10 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
                 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();