[PATCH] mm: add a new function (needed for swap suspend)
This adds the function get_swap_page_of_type() allowing us to specify an index
in swap_info[] and select a swap_info_struct structure to be used for
allocating a swap page.
This function (or another one of similar functionality) will be necessary for
implementing the image-writing part of swsusp in the user space. It can also
be used for simplifying the current in-kernel implementation of the
image-writing part of swsusp.
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/include/linux/swap.h b/include/linux/swap.h
index bd66417..556617b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -209,6 +209,7 @@
extern struct swap_info_struct swap_info[];
extern void si_swapinfo(struct sysinfo *);
extern swp_entry_t get_swap_page(void);
+extern swp_entry_t get_swap_page_of_type(int type);
extern int swap_duplicate(swp_entry_t);
extern int valid_swaphandles(swp_entry_t, unsigned long *);
extern void swap_free(swp_entry_t);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index edafeac..6da4b28 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -211,6 +211,26 @@
return (swp_entry_t) {0};
}
+swp_entry_t get_swap_page_of_type(int type)
+{
+ struct swap_info_struct *si;
+ pgoff_t offset;
+
+ spin_lock(&swap_lock);
+ si = swap_info + type;
+ if (si->flags & SWP_WRITEOK) {
+ nr_swap_pages--;
+ offset = scan_swap_map(si);
+ if (offset) {
+ spin_unlock(&swap_lock);
+ return swp_entry(type, offset);
+ }
+ nr_swap_pages++;
+ }
+ spin_unlock(&swap_lock);
+ return (swp_entry_t) {0};
+}
+
static struct swap_info_struct * swap_info_get(swp_entry_t entry)
{
struct swap_info_struct * p;
