[PATCH] mm: clean up pagecache allocation

- Consolidate page_cache_alloc

- Fix splice: only the pagecache pages and filesystem data need to use
  mapping_gfp_mask.

- Fix grab_cache_page_nowait: same as splice, also honour NUMA placement.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

fs/splice.c

@@ -74,7 +74,7 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
 		wait_on_page_writeback(page);
 
 		if (PagePrivate(page))
-			try_to_release_page(page, mapping_gfp_mask(mapping));
+			try_to_release_page(page, GFP_KERNEL);
 
 		/*
 		 * If we succeeded in removing the mapping, set LRU flag
@@ -333,7 +333,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
 				break;
 
 			error = add_to_page_cache_lru(page, mapping, index,
-					      mapping_gfp_mask(mapping));
+					      GFP_KERNEL);
 			if (unlikely(error)) {
 				page_cache_release(page);
 				if (error == -EEXIST)
@@ -557,7 +557,6 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 {
 	struct file *file = sd->file;
 	struct address_space *mapping = file->f_mapping;
-	gfp_t gfp_mask = mapping_gfp_mask(mapping);
 	unsigned int offset, this_len;
 	struct page *page;
 	pgoff_t index;
@@ -591,7 +590,7 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 			goto find_page;
 
 		page = buf->page;
-		if (add_to_page_cache(page, mapping, index, gfp_mask)) {
+		if (add_to_page_cache(page, mapping, index, GFP_KERNEL)) {
 			unlock_page(page);
 			goto find_page;
 		}
@@ -613,7 +612,7 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 			 * This will also lock the page
 			 */
 			ret = add_to_page_cache_lru(page, mapping, index,
-						    gfp_mask);
+						    GFP_KERNEL);
 			if (unlikely(ret))
 				goto out;
 		}

include/linux/pagemap.h

@@ -52,19 +52,23 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
 void release_pages(struct page **pages, int nr, int cold);
 
 #ifdef CONFIG_NUMA
-extern struct page *page_cache_alloc(struct address_space *x);
-extern struct page *page_cache_alloc_cold(struct address_space *x);
+extern struct page *__page_cache_alloc(gfp_t gfp);
 #else
+static inline struct page *__page_cache_alloc(gfp_t gfp)
+{
+	return alloc_pages(gfp, 0);
+}
+#endif
+
 static inline struct page *page_cache_alloc(struct address_space *x)
 {
-	return alloc_pages(mapping_gfp_mask(x), 0);
+	return __page_cache_alloc(mapping_gfp_mask(x));
 }
 
 static inline struct page *page_cache_alloc_cold(struct address_space *x)
 {
-	return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
+	return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
 }
-#endif
 
 typedef int filler_t(void *, struct page *);
 

mm/filemap.c

@@ -467,25 +467,15 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 }
 
 #ifdef CONFIG_NUMA
-struct page *page_cache_alloc(struct address_space *x)
+struct page *__page_cache_alloc(gfp_t gfp)
 {
 	if (cpuset_do_page_mem_spread()) {
 		int n = cpuset_mem_spread_node();
-		return alloc_pages_node(n, mapping_gfp_mask(x), 0);
+		return alloc_pages_node(n, gfp, 0);
 	}
-	return alloc_pages(mapping_gfp_mask(x), 0);
+	return alloc_pages(gfp, 0);
 }
-EXPORT_SYMBOL(page_cache_alloc);
-
-struct page *page_cache_alloc_cold(struct address_space *x)
-{
-	if (cpuset_do_page_mem_spread()) {
-		int n = cpuset_mem_spread_node();
-		return alloc_pages_node(n, mapping_gfp_mask(x)|__GFP_COLD, 0);
-	}
-	return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
-}
-EXPORT_SYMBOL(page_cache_alloc_cold);
+EXPORT_SYMBOL(__page_cache_alloc);
 #endif
 
 static int __sleep_on_page_lock(void *word)
@@ -826,7 +816,6 @@ struct page *
 grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
 {
 	struct page *page = find_get_page(mapping, index);
-	gfp_t gfp_mask;
 
 	if (page) {
 		if (!TestSetPageLocked(page))
@@ -834,9 +823,8 @@ grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
 		page_cache_release(page);
 		return NULL;
 	}
-	gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
-	page = alloc_pages(gfp_mask, 0);
-	if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
+	page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
+	if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
 		page_cache_release(page);
 		page = NULL;
 	}