[PATCH 09/12] writeback: move nr_pages == 0 logic to one location

From: Jens Axboe
Date: Wed Sep 27 2017 - 16:15:28 EST


Now that we have no external callers of wb_start_writeback(), we
can shuffle the passing in of 'nr_pages'. Everybody passes in 0
at this point, so just kill the argument and move the dirty
count retrieval to that function.

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Tested-by: Chris Mason <clm@xxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
fs/fs-writeback.c | 42 ++++++++++++++++++------------------------
1 file changed, 18 insertions(+), 24 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 571a5702b568..d9be3dc34302 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -933,8 +933,19 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,

#endif /* CONFIG_CGROUP_WRITEBACK */

-static void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
- bool range_cyclic, enum wb_reason reason)
+/*
+ * 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, bool range_cyclic,
+ enum wb_reason reason)
{
struct wb_writeback_work *work;

@@ -954,7 +965,7 @@ static void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
}

work->sync_mode = WB_SYNC_NONE;
- work->nr_pages = nr_pages;
+ work->nr_pages = wb_split_bdi_pages(wb, get_nr_dirty_pages());
work->range_cyclic = range_cyclic;
work->reason = reason;
work->auto_free = 1;
@@ -1814,17 +1825,6 @@ 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)) {
@@ -1951,7 +1951,7 @@ void wb_workfn(struct work_struct *work)
* write back the whole world.
*/
static void __wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
- long nr_pages, enum wb_reason reason)
+ enum wb_reason reason)
{
struct bdi_writeback *wb;

@@ -1959,17 +1959,14 @@ static void __wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
return;

list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node)
- wb_start_writeback(wb, wb_split_bdi_pages(wb, nr_pages),
- true, reason);
+ wb_start_writeback(wb, true, reason);
}

void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
enum wb_reason reason)
{
- long nr_pages = get_nr_dirty_pages();
-
rcu_read_lock();
- __wakeup_flusher_threads_bdi(bdi, nr_pages, reason);
+ __wakeup_flusher_threads_bdi(bdi, reason);
rcu_read_unlock();
}

@@ -1979,7 +1976,6 @@ void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
void wakeup_flusher_threads(enum wb_reason reason)
{
struct backing_dev_info *bdi;
- long nr_pages;

/*
* If we are expecting writeback progress we must submit plugged IO.
@@ -1987,11 +1983,9 @@ void wakeup_flusher_threads(enum wb_reason reason)
if (blk_needs_flush_plug(current))
blk_schedule_flush_plug(current);

- 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);
+ __wakeup_flusher_threads_bdi(bdi, reason);
rcu_read_unlock();
}

--
2.7.4