---

yaml
---
r: 115584
b: refs/heads/master
c: 17bc6c3
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 74baaaaec8b4f22e1ae279f5ecca4ff705b28912
+refs/heads/master: 17bc6c30cf6bfffd816bdc53682dd46fc34a2cf4

trunk/include/linux/writeback.h

@@ -63,6 +63,15 @@ struct writeback_control {
 	unsigned for_writepages:1;	/* This is a writepages() call */
 	unsigned range_cyclic:1;	/* range_start is cyclic */
 	unsigned more_io:1;		/* more io to be dispatched */
+	/*
+	 * write_cache_pages() won't update wbc->nr_to_write and
+	 * mapping->writeback_index if no_nrwrite_index_update
+	 * is set.  write_cache_pages() may write more than we
+	 * requested and we want to make sure nr_to_write and
+	 * writeback_index are updated in a consistent manner
+	 * so we use a single control to update them
+	 */
+	unsigned no_nrwrite_index_update:1;
 };
 
 /*

trunk/mm/page-writeback.c

@@ -876,6 +876,7 @@ int write_cache_pages(struct address_space *mapping,
 	pgoff_t end;		/* Inclusive */
 	int scanned = 0;
 	int range_whole = 0;
+	long nr_to_write = wbc->nr_to_write;
 
 	if (wbc->nonblocking && bdi_write_congested(bdi)) {
 		wbc->encountered_congestion = 1;
@@ -939,7 +940,7 @@ int write_cache_pages(struct address_space *mapping,
 				unlock_page(page);
 				ret = 0;
 			}
-			if (ret || (--(wbc->nr_to_write) <= 0))
+			if (ret || (--nr_to_write <= 0))
 				done = 1;
 			if (wbc->nonblocking && bdi_write_congested(bdi)) {
 				wbc->encountered_congestion = 1;
@@ -958,8 +959,11 @@ int write_cache_pages(struct address_space *mapping,
 		index = 0;
 		goto retry;
 	}
-	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
-		mapping->writeback_index = index;
+	if (!wbc->no_nrwrite_index_update) {
+		if (wbc->range_cyclic || (range_whole && nr_to_write > 0))
+			mapping->writeback_index = index;
+		wbc->nr_to_write = nr_to_write;
+	}
 
 	return ret;
 }