[PATCH 3.16 061/294] md/raid5: add thread_group worker async_tx_issue_pending_all

[Ben Hutchings]

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ofer Heifetz <oferh@xxxxxxxxxxx>

commit 7e96d559634b73a8158ee99a7abece2eacec2668 upstream.

Since thread_group worker and raid5d kthread are not in sync, if
worker writes stripe before raid5d then requests will be waiting
for issue_pendig.

Issue observed when building raid5 with ext4, in some build runs
jbd2 would get hung and requests were waiting in the HW engine
waiting to be issued.

Fix this by adding a call to async_tx_issue_pending_all in the
raid5_do_work.

Signed-off-by: Ofer Heifetz <oferh@xxxxxxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/md/raid5.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5240,6 +5240,8 @@ static void raid5_do_work(struct work_st
 	pr_debug("%d stripes handled\n", handled);
 
 	spin_unlock_irq(&conf->device_lock);
+
+	async_tx_issue_pending_all();
 	blk_finish_plug(&plug);
 
 	pr_debug("--- raid5worker inactive\n");