X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=fs%2Ffs-writeback.c;h=551684de13924dc256d89bb3b7ce175a02b73fdf;hb=7fbdea32328312c65870c397a0a436c3226c8631;hp=8e1e5e19d21e1fd60c9f99b3988fee0191c3e901;hpb=81ce31b773226332475f89501b1072bec0c0e241;p=linux-block.git

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 8e1e5e19d21e..551684de1392 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -41,8 +41,9 @@ struct wb_writeback_args {
 	long nr_pages;
 	struct super_block *sb;
 	enum writeback_sync_modes sync_mode;
-	int for_kupdate;
-	int range_cyclic;
+	int for_kupdate:1;
+	int range_cyclic:1;
+	int for_background:1;
 };
 
 /*
@@ -257,6 +258,15 @@ void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages)
 		.range_cyclic	= 1,
 	};
 
+	/*
+	 * We treat @nr_pages=0 as the special case to do background writeback,
+	 * ie. to sync pages until the background dirty threshold is reached.
+	 */
+	if (!nr_pages) {
+		args.nr_pages = LONG_MAX;
+		args.for_background = 1;
+	}
+
 	bdi_alloc_queue_work(bdi, &args);
 }
 
@@ -706,6 +716,7 @@ static long wb_writeback(struct bdi_writeback *wb,
 	};
 	unsigned long oldest_jif;
 	long wrote = 0;
+	struct inode *inode;
 
 	if (wbc.for_kupdate) {
 		wbc.older_than_this = &oldest_jif;
@@ -719,20 +730,16 @@ static long wb_writeback(struct bdi_writeback *wb,
 
 	for (;;) {
 		/*
-		 * Don't flush anything for non-integrity writeback where
-		 * no nr_pages was given
+		 * Stop writeback when nr_pages has been consumed
 		 */
-		if (!args->for_kupdate && args->nr_pages <= 0 &&
-		     args->sync_mode == WB_SYNC_NONE)
+		if (args->nr_pages <= 0)
 			break;
 
 		/*
-		 * If no specific pages were given and this is just a
-		 * periodic background writeout and we are below the
-		 * background dirty threshold, don't do anything
+		 * For background writeout, stop when we are below the
+		 * background dirty threshold
 		 */
-		if (args->for_kupdate && args->nr_pages <= 0 &&
-		    !over_bground_thresh())
+		if (args->for_background && !over_bground_thresh())
 			break;
 
 		wbc.more_io = 0;
@@ -746,9 +753,25 @@ static long wb_writeback(struct bdi_writeback *wb,
 		/*
 		 * If we ran out of stuff to write, bail unless more_io got set
 		 */
-		if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
-			if (wbc.more_io && !wbc.for_kupdate)
+		if (wbc.nr_to_write > 0) {
+			if (wbc.more_io) {
+				if (wbc.nr_to_write < MAX_WRITEBACK_PAGES)
+					continue;
+				/*
+				 * Nothing written. Wait for some inode to
+				 * become available for writeback. Otherwise
+				 * we'll just busyloop.
+				 */
+				spin_lock(&inode_lock);
+				if (!list_empty(&wb->b_more_io))  {
+					inode = list_entry(
+							wb->b_more_io.prev,
+							struct inode, i_list);
+					inode_wait_for_writeback(inode);
+				}
+				spin_unlock(&inode_lock);
 				continue;
+			}
 			break;
 		}
 	}