[Suspend2][ 22/28] [Suspend2] Does a swapwriter image exist?

[Nigel Cunningham <nigel@suspend2.net>]

Return whether there is an image at the location currently pointed to by
resume2=.

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

 kernel/power/suspend_swap.c |   54 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 54 insertions(+), 0 deletions(-)

diff --git a/kernel/power/suspend_swap.c b/kernel/power/suspend_swap.c
index ba6ed75..7342cb2 100644
--- a/kernel/power/suspend_swap.c
+++ b/kernel/power/suspend_swap.c
@@ -872,3 +872,57 @@ static unsigned long swapwriter_storage_
 	return result;
 }
 
+/*
+ * Image_exists
+ */
+
+static int swapwriter_image_exists(void)
+{
+	int signature_found;
+	union p_diskpage diskpage;
+	
+	if (!resume_dev_t) {
+		printk("Not even trying to read header "
+				"because resume_dev_t is not set.\n");
+		return 0;
+	}
+	
+	if (!resume_block_device &&
+	    IS_ERR(resume_block_device = open_bdev(MAX_SWAPFILES, resume_dev_t)))
+		return 0;
+
+	diskpage.address = get_zeroed_page(GFP_ATOMIC);
+
+	suspend_bio_ops.bdev_page_io(READ, resume_block_device,
+			resume_firstblock,
+			virt_to_page(diskpage.ptr));
+	suspend_bio_ops.finish_all_io();
+
+	signature_found = parse_signature(diskpage.pointer->swh.magic.magic, 0);
+	free_page(diskpage.address);
+
+	if (signature_found < 2) {
+		return 0;	/* Normal swap space */
+	} else if (signature_found == -1) {
+		printk(KERN_ERR name_suspend
+			"Unable to find a signature. Could you have moved "
+			"a swap file?\n");
+		return 0;
+	} else if (signature_found < 6) {
+		if ((!(test_suspend_state(SUSPEND_NORESUME_SPECIFIED)))
+				&& suspend_early_boot_message(1,
+				SUSPEND_CONTINUE_REQ,
+				"Detected the signature of an alternate "
+				"implementation.\n"))
+			set_suspend_state(SUSPEND_NORESUME_SPECIFIED);
+		return 0;
+	} else if ((signature_found >> 1) != SIGNATURE_VER) {
+		if ((!(test_suspend_state(SUSPEND_NORESUME_SPECIFIED))) &&
+			suspend_early_boot_message(1, SUSPEND_CONTINUE_REQ,
+			 "Found a different style suspend image signature."))
+			set_suspend_state(SUSPEND_NORESUME_SPECIFIED);
+	}
+
+	return 1;
+}
+

--
Nigel Cunningham		nigel at suspend2 dot net