md/raid1: handle flush request correctly

I got a warning triggered in align_to_barrier_unit_end. It's a flush
request so sectors == 0. The flush request happens to work well without
the new barrier patch, but we'd better handle it explictly.

Cc: NeilBrown <neilb@suse.com>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Shaohua Li <shli@fb.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 2e5e4805cbe1..8901f0c8c775 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1282,8 +1282,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio)
         unsigned long flags;
         const int op = bio_op(bio);
         const unsigned long do_sync = (bio->bi_opf & REQ_SYNC);
-        const unsigned long do_flush_fua = (bio->bi_opf &
-                                                (REQ_PREFLUSH | REQ_FUA));
+        const unsigned long do_fua = (bio->bi_opf & REQ_FUA);
         struct md_rdev *blocked_rdev;
         struct blk_plug_cb *cb;
         struct raid1_plug_cb *plug = NULL;
@@ -1509,7 +1508,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio)
                                    conf->mirrors[i].rdev->data_offset);
                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
                 mbio->bi_end_io = raid1_end_write_request;
-                bio_set_op_attrs(mbio, op, do_flush_fua | do_sync);
+                bio_set_op_attrs(mbio, op, do_fua | do_sync);
                 if (test_bit(FailFast, &conf->mirrors[i].rdev->flags) &&
                     !test_bit(WriteMostly, &conf->mirrors[i].rdev->flags) &&
                     conf->raid_disks - mddev->degraded > 1)
@@ -1565,6 +1564,11 @@ static void raid1_make_request(struct mddev *mddev, struct bio *bio)
         struct bio *split;
         sector_t sectors;
 
+        if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
+                md_flush_request(mddev, bio);
+                return;
+        }
+
         /* if bio exceeds barrier unit boundary, split it */
         do {
                 sectors = align_to_barrier_unit_end(