[POC][PATCH 59/83] add pointer-returning variants of __get_free_pages/__get_free_page

[Al Viro <viro@ZenIV.linux.org.uk>]

From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 drivers/block/xen-blkback/blkback.c | 4 ++--
 drivers/xen/xen-scsiback.c          | 6 +++---
 include/linux/gfp.h                 | 9 +++++++--
 mm/page_alloc.c                     | 8 ++++----
 4 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index f909994..aa1c52a 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -113,7 +113,7 @@ module_param(log_stats, int, 0644);
 /* Number of free pages to remove on each call to gnttab_free_pages */
 #define NUM_BATCH_FREE_PAGES 10
 
-static inline int get_free_page(struct xen_blkif *blkif, struct page **page)
+static inline int xen_get_free_page(struct xen_blkif *blkif, struct page **page)
 {
 	unsigned long flags;
 
@@ -819,7 +819,7 @@ again:
 			pages[i]->page = persistent_gnt->page;
 			pages[i]->persistent_gnt = persistent_gnt;
 		} else {
-			if (get_free_page(blkif, &pages[i]->page))
+			if (xen_get_free_page(blkif, &pages[i]->page))
 				goto out_of_memory;
 			addr = vaddr(pages[i]->page);
 			pages_to_gnt[segs_to_map] = pages[i]->page;
diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index 43bcae8..ebd2321 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -229,7 +229,7 @@ static void put_free_pages(struct page **page, int num)
 	spin_unlock_irqrestore(&free_pages_lock, flags);
 }
 
-static int get_free_page(struct page **page)
+static int xen_get_free_page(struct page **page)
 {
 	unsigned long flags;
 
@@ -439,7 +439,7 @@ static int scsiback_gnttab_data_map_list(struct vscsibk_pend *pending_req,
 	struct vscsibk_info *info = pending_req->info;
 
 	for (i = 0; i < cnt; i++) {
-		if (get_free_page(pg + mapcount)) {
+		if (xen_get_free_page(pg + mapcount)) {
 			put_free_pages(pg, mapcount);
 			pr_err("no grant page\n");
 			return -ENOMEM;
@@ -1902,7 +1902,7 @@ static void __exit scsiback_exit(void)
 	struct page *page;
 
 	while (free_pages_num) {
-		if (get_free_page(&page))
+		if (xen_get_free_page(&page))
 			BUG();
 		gnttab_free_pages(1, &page);
 	}
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index fc4529d..bb1626a 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -473,18 +473,23 @@ extern struct page *alloc_kmem_pages(gfp_t gfp_mask, unsigned int order);
 extern struct page *alloc_kmem_pages_node(int nid, gfp_t gfp_mask,
 					  unsigned int order);
 
-extern unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order);
+extern void *get_free_pages(gfp_t gfp_mask, unsigned int order);
+#define __get_free_pages(gfp_mask, order) \
+	((unsigned long)get_free_pages(gfp_mask, order))
 extern void *get_zeroed_page(gfp_t gfp_mask);
 
 void *alloc_pages_exact(size_t size, gfp_t gfp_mask);
 void free_pages_exact(void *virt, size_t size);
 void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask);
 
+#define get_free_page(gfp_mask) \
+		get_free_pages((gfp_mask), 0)
+
 #define __get_free_page(gfp_mask) \
 		__get_free_pages((gfp_mask), 0)
 
 #define get_dma_pages(gfp_mask, order) \
-		((void *)__get_free_pages((gfp_mask) | GFP_DMA, (order)))
+		get_free_pages((gfp_mask) | GFP_DMA, (order))
 
 extern void __free_pages(struct page *page, unsigned int order);
 extern void free_pages(const void *addr, unsigned int order);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a1aa8eb..9ab053f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3257,7 +3257,7 @@ EXPORT_SYMBOL(__alloc_pages_nodemask);
 /*
  * Common helper functions.
  */
-unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
+void *get_free_pages(gfp_t gfp_mask, unsigned int order)
 {
 	struct page *page;
 
@@ -3269,10 +3269,10 @@ unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
 
 	page = alloc_pages(gfp_mask, order);
 	if (!page)
-		return 0;
-	return (unsigned long) page_address(page);
+		return NULL;
+	return page_address(page);
 }
-EXPORT_SYMBOL(__get_free_pages);
+EXPORT_SYMBOL(get_free_pages);
 
 void *get_zeroed_page(gfp_t gfp_mask)
 {
-- 
2.1.4