[PATCH 4.9 089/104] md/raid10: submit bio directly to replacement disk

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Shaohua Li <s...@fb.com>


[ Upstream commit 6d399783e9d4e9bd44931501948059d24ad96ff8 ]

Commit 57c67df(md/raid10: submit IO from originating thread instead of
md thread) submits bio directly for normal disks but not for replacement
disks. There is no point we shouldn't do this for replacement disks.

Cc: NeilBrown <ne...@suse.com>
Signed-off-by: Shaohua Li <s...@fb.com>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/md/raid10.c |   19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1407,11 +1407,24 @@ retry_write:
                        mbio->bi_private = r10_bio;
 
                        atomic_inc(&r10_bio->remaining);
+
+                       cb = blk_check_plugged(raid10_unplug, mddev,
+                                              sizeof(*plug));
+                       if (cb)
+                               plug = container_of(cb, struct raid10_plug_cb,
+                                                   cb);
+                       else
+                               plug = NULL;
                        spin_lock_irqsave(&conf->device_lock, flags);
-                       bio_list_add(&conf->pending_bio_list, mbio);
-                       conf->pending_count++;
+                       if (plug) {
+                               bio_list_add(&plug->pending, mbio);
+                               plug->pending_cnt++;
+                       } else {
+                               bio_list_add(&conf->pending_bio_list, mbio);
+                               conf->pending_count++;
+                       }
                        spin_unlock_irqrestore(&conf->device_lock, flags);
-                       if (!mddev_check_plugged(mddev))
+                       if (!plug)
                                md_wakeup_thread(mddev->thread);
                }
        }