[PATCH] swsusp: add ioctl for swap files support

To be able to use swap files as suspend storage from the userland suspend
tools we need an additional ioctl() that will allow us to provide the kernel
with both the swap header's offset and the identification of the resume
partition.

The new ioctl() should be regarded as a replacement for the
SNAPSHOT_SET_SWAP_FILE ioctl() that from now on will be considered as
obsolete, but has to stay for backwards compatibility of the interface.

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/power.h b/kernel/power/power.h
index adaf7d4..7dbfd9f 100644 (file)
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -106,6 +106,16 @@ extern int snapshot_write_next(struct snapshot_handle *handle, size_t count);
 extern int snapshot_image_loaded(struct snapshot_handle *handle);
 extern void snapshot_free_unused_memory(struct snapshot_handle *handle);
 
+/*
+ * This structure is used to pass the values needed for the identification
+ * of the resume swap area from a user space to the kernel via the
+ * SNAPSHOT_SET_SWAP_AREA ioctl
+ */
+struct resume_swap_area {
+       loff_t offset;
+       u_int32_t dev;
+} __attribute__((packed));
+
 #define SNAPSHOT_IOC_MAGIC     '3'
 #define SNAPSHOT_FREEZE                        _IO(SNAPSHOT_IOC_MAGIC, 1)
 #define SNAPSHOT_UNFREEZE              _IO(SNAPSHOT_IOC_MAGIC, 2)
@@ -119,7 +129,9 @@ extern void snapshot_free_unused_memory(struct snapshot_handle *handle);
 #define SNAPSHOT_SET_SWAP_FILE         _IOW(SNAPSHOT_IOC_MAGIC, 10, unsigned int)
 #define SNAPSHOT_S2RAM                 _IO(SNAPSHOT_IOC_MAGIC, 11)
 #define SNAPSHOT_PMOPS                 _IOW(SNAPSHOT_IOC_MAGIC, 12, unsigned int)
-#define SNAPSHOT_IOC_MAXNR     12
+#define SNAPSHOT_SET_SWAP_AREA         _IOW(SNAPSHOT_IOC_MAGIC, 13, \
+                                                       struct resume_swap_area)
+#define SNAPSHOT_IOC_MAXNR     13
 
 #define PMOPS_PREPARE  1
 #define PMOPS_ENTER    2

diff --git a/kernel/power/user.c b/kernel/power/user.c
index f0b7ef8..05c58a2 100644 (file)
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -343,6 +343,37 @@ OutS3:
                }
                break;
 
+       case SNAPSHOT_SET_SWAP_AREA:
+               if (data->bitmap) {
+                       error = -EPERM;
+               } else {
+                       struct resume_swap_area swap_area;
+                       dev_t swdev;
+
+                       error = copy_from_user(&swap_area, (void __user *)arg,
+                                       sizeof(struct resume_swap_area));
+                       if (error) {
+                               error = -EFAULT;
+                               break;
+                       }
+
+                       /*
+                        * User space encodes device types as two-byte values,
+                        * so we need to recode them
+                        */
+                       swdev = old_decode_dev(swap_area.dev);
+                       if (swdev) {
+                               offset = swap_area.offset;
+                               data->swap = swap_type_of(swdev, offset);
+                               if (data->swap < 0)
+                                       error = -ENODEV;
+                       } else {
+                               data->swap = -1;
+                               error = -EINVAL;
+                       }
+               }
+               break;
+
        default:
                error = -ENOTTY;