[PATCH] swsusp: Do not fail if resume device is not set

In the kernels later than 2.6.19 there is a regression that makes swsusp
fail if the resume device is not explicitly specified.

It can be fixed by adding an additional parameter to
mm/swapfile.c:swap_type_of() allowing us to pass the (struct block_device
*) corresponding to the first available swap back to the caller.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index f133d4a..3581f8f 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -165,14 +165,15 @@
 {
 	int res;
 
-	res = swap_type_of(swsusp_resume_device, swsusp_resume_block);
+	res = swap_type_of(swsusp_resume_device, swsusp_resume_block,
+			&resume_bdev);
 	if (res < 0)
 		return res;
 
 	root_swap = res;
-	resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_WRITE);
-	if (IS_ERR(resume_bdev))
-		return PTR_ERR(resume_bdev);
+	res = blkdev_get(resume_bdev, FMODE_WRITE, O_RDWR);
+	if (res)
+		return res;
 
 	res = set_blocksize(resume_bdev, PAGE_SIZE);
 	if (res < 0)
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 89443b8..f7b7a78 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -57,7 +57,7 @@
 	memset(&data->handle, 0, sizeof(struct snapshot_handle));
 	if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
 		data->swap = swsusp_resume_device ?
-				swap_type_of(swsusp_resume_device, 0) : -1;
+			swap_type_of(swsusp_resume_device, 0, NULL) : -1;
 		data->mode = O_RDONLY;
 	} else {
 		data->swap = -1;
@@ -268,7 +268,8 @@
 			 * so we need to recode them
 			 */
 			if (old_decode_dev(arg)) {
-				data->swap = swap_type_of(old_decode_dev(arg), 0);
+				data->swap = swap_type_of(old_decode_dev(arg),
+							0, NULL);
 				if (data->swap < 0)
 					error = -ENODEV;
 			} else {
@@ -365,7 +366,7 @@
 			swdev = old_decode_dev(swap_area.dev);
 			if (swdev) {
 				offset = swap_area.offset;
-				data->swap = swap_type_of(swdev, offset);
+				data->swap = swap_type_of(swdev, offset, NULL);
 				if (data->swap < 0)
 					error = -ENODEV;
 			} else {