[PATCH -mm 4/6] swsusp: Add resume_offset command line parameter

["Rafael J. Wysocki" <rjw@sisk.pl>]

Add the kernel command line parameter "resume_offset=" allowing us to specify
the offset, in <PAGE_SIZE> units, from the beginning of the partition pointed
to by the "resume=" parameter at which the swap header is located.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
kernel/power/disk.c  |   15 +++++++++++++++
 kernel/power/power.h |    1 +
 kernel/power/swap.c  |   15 ++++++++++-----
 3 files changed, 26 insertions(+), 5 deletions(-)

Index: linux-2.6.18-rc7-mm1/kernel/power/disk.c
===================================================================
--- linux-2.6.18-rc7-mm1.orig/kernel/power/disk.c
+++ linux-2.6.18-rc7-mm1/kernel/power/disk.c
@@ -27,6 +27,7 @@
 static int noresume = 0;
 char resume_file[256] = CONFIG_PM_STD_PARTITION;
 dev_t swsusp_resume_device;
+sector_t swsusp_resume_block;
 
 /**
  *	power_down - Shut machine down for hibernate.
@@ -404,6 +405,19 @@ static int __init resume_setup(char *str
 	return 1;
 }
 
+static int __init resume_offset_setup(char *str)
+{
+	loff_t offset;
+
+	if (noresume)
+		return 1;
+
+	if (sscanf(str, "%llu", &offset) == 1)
+		swsusp_resume_block = offset;
+
+	return 1;
+}
+
 static int __init noresume_setup(char *str)
 {
 	noresume = 1;
@@ -411,4 +425,5 @@ static int __init noresume_setup(char *s
 }
 
 __setup("noresume", noresume_setup);
+__setup("resume_offset=", resume_offset_setup);
 __setup("resume=", resume_setup);
Index: linux-2.6.18-rc7-mm1/kernel/power/power.h
===================================================================
--- linux-2.6.18-rc7-mm1.orig/kernel/power/power.h
+++ linux-2.6.18-rc7-mm1/kernel/power/power.h
@@ -42,6 +42,7 @@ extern const void __nosave_begin, __nosa
 extern unsigned long image_size;
 extern int in_suspend;
 extern dev_t swsusp_resume_device;
+extern sector_t swsusp_resume_block;
 
 extern asmlinkage int swsusp_arch_suspend(void);
 extern asmlinkage int swsusp_arch_resume(void);
Index: linux-2.6.18-rc7-mm1/kernel/power/swap.c
===================================================================
--- linux-2.6.18-rc7-mm1.orig/kernel/power/swap.c
+++ linux-2.6.18-rc7-mm1/kernel/power/swap.c
@@ -160,13 +160,14 @@ static int mark_swapfiles(loff_t start)
 {
 	int error;
 
-	bio_read_page(0, &swsusp_header, NULL);
+	bio_read_page(swsusp_resume_block, &swsusp_header, NULL);
 	if (!memcmp("SWAP-SPACE",swsusp_header.sig, 10) ||
 	    !memcmp("SWAPSPACE2",swsusp_header.sig, 10)) {
 		memcpy(swsusp_header.orig_sig,swsusp_header.sig, 10);
 		memcpy(swsusp_header.sig,SWSUSP_SIG, 10);
 		swsusp_header.image = start;
-		error = bio_write_page(0, &swsusp_header, NULL);
+		error = bio_write_page(swsusp_resume_block,
+					&swsusp_header, NULL);
 	} else {
 		printk(KERN_ERR "swsusp: Swap header not found!\n");
 		error = -ENODEV;
@@ -183,7 +184,7 @@ static int swsusp_swap_check(void) /* Th
 {
 	int res;
 
-	res = swap_type_of(swsusp_resume_device, 0);
+	res = swap_type_of(swsusp_resume_device, swsusp_resume_block);
 	if (res < 0)
 		return res;
 
@@ -606,12 +607,16 @@ int swsusp_check(void)
 	if (!IS_ERR(resume_bdev)) {
 		set_blocksize(resume_bdev, PAGE_SIZE);
 		memset(&swsusp_header, 0, sizeof(swsusp_header));
-		if ((error = bio_read_page(0, &swsusp_header, NULL)))
+		error = bio_read_page(swsusp_resume_block,
+					&swsusp_header, NULL);
+		if (error)
 			return error;
+
 		if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
 			memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
 			/* Reset swap signature now */
-			error = bio_write_page(0, &swsusp_header, NULL);
+			error = bio_write_page(swsusp_resume_block,
+						&swsusp_header, NULL);
 		} else {
 			return -EINVAL;
 		}