[PATCH] tag writeback pages as such in their radix tree

Arrange for under-writeback pages to be marked thus in their pagecache radix
tree.

fs/buffer.c

@@ -1829,7 +1829,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
 	} while ((bh = bh->b_this_page) != head);
 
 	BUG_ON(PageWriteback(page));
-	SetPageWriteback(page);		/* Keeps try_to_free_buffers() away */
+	set_page_writeback(page);	/* Keeps try_to_free_buffers() away */
 	unlock_page(page);
 
 	/*
@@ -1892,7 +1892,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
 	} while ((bh = bh->b_this_page) != head);
 	SetPageError(page);
 	BUG_ON(PageWriteback(page));
-	SetPageWriteback(page);
+	set_page_writeback(page);
 	unlock_page(page);
 	do {
 		struct buffer_head *next = bh->b_this_page;

fs/mpage.c

@@ -546,7 +546,7 @@ mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
 	}
 
 	BUG_ON(PageWriteback(page));
-	SetPageWriteback(page);
+	set_page_writeback(page);
 	unlock_page(page);
 	if (boundary || (first_unmapped != blocks_per_page)) {
 		bio = mpage_bio_submit(WRITE, bio);

fs/nfs/write.c

@@ -768,7 +768,7 @@ nfs_write_rpcsetup(struct list_head *head, struct nfs_write_data *data, int how)
 		req = nfs_list_entry(head->next);
 		nfs_list_remove_request(req);
 		nfs_list_add_request(req, &data->pages);
-		SetPageWriteback(req->wb_page);
+		set_page_writeback(req->wb_page);
 		*pages++ = req->wb_page;
 		count += req->wb_bytes;
 	}

fs/ntfs/aops.c

@@ -743,7 +743,7 @@ static int ntfs_write_block(struct page *page)
 	}
 
 	BUG_ON(PageWriteback(page));
-	SetPageWriteback(page);		/* Keeps try_to_free_buffers() away. */
+	set_page_writeback(page);	/* Keeps try_to_free_buffers() away. */
 	unlock_page(page);
 
 	/*
@@ -885,7 +885,7 @@ static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
 	// FIXME: Make sure it is ok to SetPageError() on unlocked page under
 	// writeback before doing the change!
 #if 0
-	SetPageWriteback(page);
+	set_page_writeback(page);
 	unlock_page(page);
 #endif
 

fs/reiserfs/inode.c

@@ -2134,7 +2134,7 @@ static int reiserfs_write_full_page(struct page *page, struct writeback_control
     } while(bh != head) ;
 
     BUG_ON(PageWriteback(page));
-    SetPageWriteback(page);
+    set_page_writeback(page);
     unlock_page(page);
 
     /*
@@ -2198,7 +2198,7 @@ static int reiserfs_write_full_page(struct page *page, struct writeback_control
     } while(bh != head);
     SetPageError(page);
     BUG_ON(PageWriteback(page));
-    SetPageWriteback(page);
+    set_page_writeback(page);
     unlock_page(page);
     do {
         struct buffer_head *next = bh->b_this_page;

fs/xfs/linux/xfs_aops.c

@@ -566,7 +566,7 @@ xfs_submit_page(
 	int			i;
 
 	BUG_ON(PageWriteback(page));
-	SetPageWriteback(page);
+	set_page_writeback(page);
 	clear_page_dirty(page);
 	unlock_page(page);
 

include/linux/page-flags.h

@@ -312,12 +312,18 @@ extern struct address_space swapper_space;
 struct page;	/* forward declaration */
 
 int test_clear_page_dirty(struct page *page);
+int __clear_page_dirty(struct page *page);
+int test_clear_page_writeback(struct page *page);
+int test_set_page_writeback(struct page *page);
 
 static inline void clear_page_dirty(struct page *page)
 {
 	test_clear_page_dirty(page);
 }
 
-int __clear_page_dirty(struct page *page);
+static inline void set_page_writeback(struct page *page)
+{
+	test_set_page_writeback(page);
+}
 
 #endif	/* PAGE_FLAGS_H */

mm/filemap.c

@@ -363,8 +363,7 @@ void end_page_writeback(struct page *page)
 	wait_queue_head_t *waitqueue = page_waitqueue(page);
 
 	if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
-		smp_mb__before_clear_bit();
-		if (!TestClearPageWriteback(page))
+		if (!test_clear_page_writeback(page))
 			BUG();
 		smp_mb__after_clear_bit();
 	}

mm/page-writeback.c

@@ -604,3 +604,45 @@ int __clear_page_dirty(struct page *page)
 	}
 	return TestClearPageDirty(page);
 }
+
+int test_clear_page_writeback(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	int ret;
+
+	if (mapping) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&mapping->tree_lock, flags);
+		ret = TestClearPageWriteback(page);
+		if (ret)
+			radix_tree_tag_clear(&mapping->page_tree, page->index,
+						PAGECACHE_TAG_WRITEBACK);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	} else {
+		ret = TestClearPageWriteback(page);
+	}
+	return ret;
+}
+
+int test_set_page_writeback(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	int ret;
+
+	if (mapping) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&mapping->tree_lock, flags);
+		ret = TestSetPageWriteback(page);
+		if (!ret)
+			radix_tree_tag_set(&mapping->page_tree, page->index,
+						PAGECACHE_TAG_WRITEBACK);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	} else {
+		ret = TestSetPageWriteback(page);
+	}
+	return ret;
+
+}
+EXPORT_SYMBOL(test_set_page_writeback);

mm/page_io.c

@@ -104,7 +104,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
 		goto out;
 	}
 	inc_page_state(pswpout);
-	SetPageWriteback(page);
+	set_page_writeback(page);
 	unlock_page(page);
 	submit_bio(WRITE, bio);
 out:

mm/swap.c

@@ -70,7 +70,7 @@ int rotate_reclaimable_page(struct page *page)
 		list_add_tail(&page->lru, &zone->inactive_list);
 		inc_page_state(pgrotated);
 	}
-	if (!TestClearPageWriteback(page))
+	if (!test_clear_page_writeback(page))
 		BUG();
 	spin_unlock_irqrestore(&zone->lru_lock, flags);
 	return 0;