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>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 2e5e4805cbe110bdfeaf7e75b8fe26376803d764..8901f0c8c775ad655566b75d54d22f65179ef8a0 100644 (file)
--- 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(