Hibernation: Introduce SNAPSHOT_GET_IMAGE_SIZE ioctl

Add a new ioctl, SNAPSHOT_GET_IMAGE_SIZE, returning the size of the (just
created) hibernation image, to the hibernation userland interface.

This ioctl is necessary so that the userland utilities using the interface need
not access the hibernation image header, owned by the kernel, in order to obtain
the size of the image.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 14 insertions, 4 deletions

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 5bd321bcbb75..88aac26e598a 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -133,7 +133,7 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
 {
         int error = 0;
         struct snapshot_data *data;
-        loff_t avail;
+        loff_t size;
         sector_t offset;
 
         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
@@ -210,10 +210,20 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
                 image_size = arg;
                 break;
 
+        case SNAPSHOT_GET_IMAGE_SIZE:
+                if (!data->ready) {
+                        error = -ENODATA;
+                        break;
+                }
+                size = snapshot_get_image_size();
+                size <<= PAGE_SHIFT;
+                error = put_user(size, (loff_t __user *)arg);
+                break;
+
         case SNAPSHOT_AVAIL_SWAP:
-                avail = count_swap_pages(data->swap, 1);
-                avail <<= PAGE_SHIFT;
-                error = put_user(avail, (loff_t __user *)arg);
+                size = count_swap_pages(data->swap, 1);
+                size <<= PAGE_SHIFT;
+                error = put_user(size, (loff_t __user *)arg);
                 break;
 
         case SNAPSHOT_GET_SWAP_PAGE: