[PATCH 5/6] fs-writeback: move nr_pages == 0 logic to one location

From: Jens Axboe
Date: Tue Sep 19 2017 - 15:53:58 EST


Now that we have no external callers of wb_start_writeback(),
we can move the nr_pages == 0 logic into that function.

Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
fs/fs-writeback.c | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7564347914f8..a9a86644cb9f 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -933,6 +933,17 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,

#endif /* CONFIG_CGROUP_WRITEBACK */

+/*
+ * Add in the number of potentially dirty inodes, because each inode
+ * write can dirty pagecache in the underlying blockdev.
+ */
+static unsigned long get_nr_dirty_pages(void)
+{
+ return global_node_page_state(NR_FILE_DIRTY) +
+ global_node_page_state(NR_UNSTABLE_NFS) +
+ get_nr_dirty_inodes();
+}
+
static void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
bool range_cyclic, enum wb_reason reason)
{
@@ -942,6 +953,12 @@ static void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
return;

/*
+ * If someone asked for zero pages, we write out the WORLD
+ */
+ if (!nr_pages)
+ nr_pages = get_nr_dirty_pages();
+
+ /*
* This is WB_SYNC_NONE writeback, so if allocation fails just
* wakeup the thread for old dirty data writeback
*/
@@ -1814,17 +1831,6 @@ static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb)
return work;
}

-/*
- * Add in the number of potentially dirty inodes, because each inode
- * write can dirty pagecache in the underlying blockdev.
- */
-static unsigned long get_nr_dirty_pages(void)
-{
- return global_node_page_state(NR_FILE_DIRTY) +
- global_node_page_state(NR_UNSTABLE_NFS) +
- get_nr_dirty_inodes();
-}
-
static long wb_check_background_flush(struct bdi_writeback *wb)
{
if (wb_over_bg_thresh(wb)) {
@@ -1966,9 +1972,6 @@ static void __wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, long nr_pages,
enum wb_reason reason)
{
- if (!nr_pages)
- nr_pages = get_nr_dirty_pages();
-
rcu_read_lock();
__wakeup_flusher_threads_bdi(bdi, nr_pages, reason);
rcu_read_unlock();
@@ -1988,9 +1991,6 @@ void wakeup_flusher_threads(long nr_pages, enum wb_reason reason)
if (blk_needs_flush_plug(current))
blk_schedule_flush_plug(current);

- if (!nr_pages)
- nr_pages = get_nr_dirty_pages();
-
rcu_read_lock();
list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
__wakeup_flusher_threads_bdi(bdi, nr_pages, reason);
--
2.7.4