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-rw-r--r--fs/fs-writeback.c32
1 files changed, 30 insertions, 2 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 3d84fcc471..d31853032a 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -141,6 +141,31 @@ static void wb_wakeup(struct bdi_writeback *wb)
spin_unlock_irq(&wb->work_lock);
}
+/*
+ * 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 bdi_writeback *wb,
struct wb_writeback_work *work)
{
@@ -2044,6 +2069,7 @@ 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 (;;) {
@@ -2086,8 +2112,10 @@ static long wb_writeback(struct bdi_writeback *wb,
dirtied_before = jiffies;
trace_writeback_start(wb, work);
- if (list_empty(&wb->b_io))
+ if (list_empty(&wb->b_io)) {
queue_io(wb, work, dirtied_before);
+ queued = true;
+ }
if (work->sb)
progress = writeback_sb_inodes(work->sb, wb, work);
else
@@ -2102,7 +2130,7 @@ 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;
}