1 files changed, 63 insertions, 29 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 1767493dffda..92a5b8283528 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -141,8 +141,32 @@ static void wb_wakeup(struct bdi_writeback *wb)
 	spin_unlock_irq(&wb->work_lock);
 }
 
-static void finish_writeback_work(struct bdi_writeback *wb,
-				  struct wb_writeback_work *work)
+/*
+ * This function is used when the first inode for this wb is marked dirty. It
+ * wakes-up the corresponding bdi thread which should then take care of the
+ * periodic background write-out of dirty inodes. Since the write-out would
+ * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
+ * set up a timer which wakes the bdi thread up later.
+ *
+ * Note, we wouldn't bother setting up the timer, but this function is on the
+ * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
+ * by delaying the wake-up.
+ *
+ * We have to be careful not to postpone flush work if it is scheduled for
+ * earlier. Thus we use queue_delayed_work().
+ */
+static void wb_wakeup_delayed(struct bdi_writeback *wb)
+{
+	unsigned long timeout;
+
+	timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
+	spin_lock_irq(&wb->work_lock);
+	if (test_bit(WB_registered, &wb->state))
+		queue_delayed_work(bdi_wq, &wb->dwork, timeout);
+	spin_unlock_irq(&wb->work_lock);
+}
+
+static void finish_writeback_work(struct wb_writeback_work *work)
 {
 	struct wb_completion *done = work->done;
 
@@ -171,7 +195,7 @@ static void wb_queue_work(struct bdi_writeback *wb,
 		list_add_tail(&work->list, &wb->work_list);
 		mod_delayed_work(bdi_wq, &wb->dwork, 0);
 	} else
-		finish_writeback_work(wb, work);
+		finish_writeback_work(work);
 
 	spin_unlock_irq(&wb->work_lock);
 }
@@ -1536,7 +1560,8 @@ static void inode_sleep_on_writeback(struct inode *inode)
  * thread's back can have unexpected consequences.
  */
 static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
-			  struct writeback_control *wbc)
+			  struct writeback_control *wbc,
+			  unsigned long dirtied_before)
 {
 	if (inode->i_state & I_FREEING)
 		return;
@@ -1569,7 +1594,8 @@ static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
 		 * We didn't write back all the pages.  nfs_writepages()
 		 * sometimes bales out without doing anything.
 		 */
-		if (wbc->nr_to_write <= 0) {
+		if (wbc->nr_to_write <= 0 &&
+		    !inode_dirtied_after(inode, dirtied_before)) {
 			/* Slice used up. Queue for next turn. */
 			requeue_io(inode, wb);
 		} else {
@@ -1675,11 +1701,11 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 
 	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
 		inode->i_state |= I_DIRTY_PAGES;
-	else if (unlikely(inode->i_state & I_PINNING_FSCACHE_WB)) {
+	else if (unlikely(inode->i_state & I_PINNING_NETFS_WB)) {
 		if (!(inode->i_state & I_DIRTY_PAGES)) {
-			inode->i_state &= ~I_PINNING_FSCACHE_WB;
-			wbc->unpinned_fscache_wb = true;
-			dirty |= I_PINNING_FSCACHE_WB; /* Cause write_inode */
+			inode->i_state &= ~I_PINNING_NETFS_WB;
+			wbc->unpinned_netfs_wb = true;
+			dirty |= I_PINNING_NETFS_WB; /* Cause write_inode */
 		}
 	}
 
@@ -1691,7 +1717,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 		if (ret == 0)
 			ret = err;
 	}
-	wbc->unpinned_fscache_wb = false;
+	wbc->unpinned_netfs_wb = false;
 	trace_writeback_single_inode(inode, wbc, nr_to_write);
 	return ret;
 }
@@ -1837,6 +1863,11 @@ static long writeback_sb_inodes(struct super_block *sb,
 	unsigned long start_time = jiffies;
 	long write_chunk;
 	long total_wrote = 0;  /* count both pages and inodes */
+	unsigned long dirtied_before = jiffies;
+
+	if (work->for_kupdate)
+		dirtied_before = jiffies -
+			msecs_to_jiffies(dirty_expire_interval * 10);
 
 	while (!list_empty(&wb->b_io)) {
 		struct inode *inode = wb_inode(wb->b_io.prev);
@@ -1942,7 +1973,7 @@ static long writeback_sb_inodes(struct super_block *sb,
 		spin_lock(&inode->i_lock);
 		if (!(inode->i_state & I_DIRTY_ALL))
 			total_wrote++;
-		requeue_inode(inode, tmp_wb, &wbc);
+		requeue_inode(inode, tmp_wb, &wbc, dirtied_before);
 		inode_sync_complete(inode);
 		spin_unlock(&inode->i_lock);
 
@@ -2044,6 +2075,7 @@ static long wb_writeback(struct bdi_writeback *wb,
 	struct inode *inode;
 	long progress;
 	struct blk_plug plug;
+	bool queued = false;
 
 	blk_start_plug(&plug);
 	for (;;) {
@@ -2073,21 +2105,24 @@ static long wb_writeback(struct bdi_writeback *wb,
 
 		spin_lock(&wb->list_lock);
 
-		/*
-		 * Kupdate and background works are special and we want to
-		 * include all inodes that need writing. Livelock avoidance is
-		 * handled by these works yielding to any other work so we are
-		 * safe.
-		 */
-		if (work->for_kupdate) {
-			dirtied_before = jiffies -
-				msecs_to_jiffies(dirty_expire_interval * 10);
-		} else if (work->for_background)
-			dirtied_before = jiffies;
-
 		trace_writeback_start(wb, work);
-		if (list_empty(&wb->b_io))
+		if (list_empty(&wb->b_io)) {
+			/*
+			 * Kupdate and background works are special and we want
+			 * to include all inodes that need writing. Livelock
+			 * avoidance is handled by these works yielding to any
+			 * other work so we are safe.
+			 */
+			if (work->for_kupdate) {
+				dirtied_before = jiffies -
+					msecs_to_jiffies(dirty_expire_interval *
+							 10);
+			} else if (work->for_background)
+				dirtied_before = jiffies;
+
 			queue_io(wb, work, dirtied_before);
+			queued = true;
+		}
 		if (work->sb)
 			progress = writeback_sb_inodes(work->sb, wb, work);
 		else
@@ -2102,7 +2137,7 @@ static long wb_writeback(struct bdi_writeback *wb,
 		 * mean the overall work is done. So we keep looping as long
 		 * as made some progress on cleaning pages or inodes.
 		 */
-		if (progress) {
+		if (progress || !queued) {
 			spin_unlock(&wb->list_lock);
 			continue;
 		}
@@ -2237,7 +2272,7 @@ static long wb_do_writeback(struct bdi_writeback *wb)
 	while ((work = get_next_work_item(wb)) != NULL) {
 		trace_writeback_exec(wb, work);
 		wrote += wb_writeback(wb, work);
-		finish_writeback_work(wb, work);
+		finish_writeback_work(work);
 	}
 
 	/*
@@ -2297,8 +2332,7 @@ void wb_workfn(struct work_struct *work)
 }
 
 /*
- * Start writeback of `nr_pages' pages on this bdi. If `nr_pages' is zero,
- * write back the whole world.
+ * Start writeback of all dirty pages on this bdi.
  */
 static void __wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
 					 enum wb_reason reason)
@@ -2701,7 +2735,7 @@ EXPORT_SYMBOL(writeback_inodes_sb_nr);
  */
 void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
 {
-	return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason);
+	writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason);
 }
 EXPORT_SYMBOL(writeback_inodes_sb);