[Suspend2][ 05/28] [Suspend2] Enable/disable swapfile.

[Nigel Cunningham <nigel@suspend2.net>]

Routines to enable and disable a swap file specifically for suspending. The
swapon is called after userspace is frozen and the swapoff is done prior to
restarting userspace. We can't completely remove the possibility of it
being used by the vm. We're just doing the best we can.

Signed-off-by: Nigel Cunningham <nigel@suspend2.net>

 kernel/power/suspend_swap.c |   45 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/kernel/power/suspend_swap.c b/kernel/power/suspend_swap.c
index 212555f..13ad8d7 100644
--- a/kernel/power/suspend_swap.c
+++ b/kernel/power/suspend_swap.c
@@ -151,3 +151,48 @@ static struct block_device *open_bdev(in
 	return bdev;
 }
 
+/* Must be silent - might be called from cat /proc/suspend/debug_info
+ * Returns 0 if was off, -EBUSY if was on, error value otherwise.
+ */
+static int enable_swapfile(void)
+{
+	int activateswapresult = -EINVAL;
+
+	if (suspend_swapon_status)
+		return 0;
+
+	if (swapfilename[0]) {
+		/* Attempt to swap on with maximum priority */
+		activateswapresult = sys_swapon(swapfilename, 0xFFFF);
+		if ((activateswapresult) && (activateswapresult != -EBUSY))
+			printk(name_suspend
+				"The swapfile/partition specified by "
+				"/proc/suspend/swapfile (%s) could not"
+				" be turned on (error %d). Attempting "
+				"to continue.\n",
+				swapfilename, activateswapresult);
+		if (!activateswapresult)
+			suspend_swapon_status = 1;
+	}
+	return activateswapresult;
+}
+
+/* Returns 0 if was on, -EINVAL if was off, error value otherwise */
+static int disable_swapfile(void)
+{
+	int result = -EINVAL;
+	
+	if (!suspend_swapon_status)
+		return 0;
+
+	if (swapfilename[0]) {
+		result = sys_swapoff(swapfilename);
+		if (result == -EINVAL)
+	 		return 0;	/* Wasn't on */
+		if (!result)
+			suspend_swapon_status = 0;
+	}
+
+	return result;
+}
+

--
Nigel Cunningham		nigel at suspend2 dot net