[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>

4 files changed, 17 insertions, 9 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index add51cebc8d9..5423559a44a6 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -245,7 +245,7 @@ extern int swap_duplicate(swp_entry_t);
 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 extern void swap_free(swp_entry_t);
 extern void free_swap_and_cache(swp_entry_t);
-extern int swap_type_of(dev_t, sector_t);
+extern int swap_type_of(dev_t, sector_t, struct block_device **);
 extern unsigned int count_swap_pages(int, int);
 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 extern sector_t swapdev_block(int, pgoff_t);
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index f133d4a6d817..3581f8f86acd 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -165,14 +165,15 @@ static int swsusp_swap_check(void) /* This is called before saving image */
 {
         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 89443b85163b..f7b7a785a5c6 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -57,7 +57,7 @@ static int snapshot_open(struct inode *inode, struct file *filp)
         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 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
                          * 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 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
                         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 {
diff --git a/mm/swapfile.c b/mm/swapfile.c
index b9fc0e5de6d5..a2d9bb4e80df 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -434,7 +434,7 @@ void free_swap_and_cache(swp_entry_t entry)
  *
  * This is needed for the suspend to disk (aka swsusp).
  */
-int swap_type_of(dev_t device, sector_t offset)
+int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
 {
         struct block_device *bdev = NULL;
         int i;
@@ -450,6 +450,9 @@ int swap_type_of(dev_t device, sector_t offset)
                         continue;
 
                 if (!bdev) {
+                        if (bdev_p)
+                                *bdev_p = sis->bdev;
+
                         spin_unlock(&swap_lock);
                         return i;
                 }
@@ -459,6 +462,9 @@ int swap_type_of(dev_t device, sector_t offset)
                         se = list_entry(sis->extent_list.next,
                                         struct swap_extent, list);
                         if (se->start_block == offset) {
+                                if (bdev_p)
+                                        *bdev_p = sis->bdev;
+
                                 spin_unlock(&swap_lock);
                                 bdput(bdev);
                                 return i;