[PATCH] md/raid1: handle flush request correctly

[PATCH] md/raid1: handle flush request correctly

[Shaohua Li]

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: Coly Li <colyli@suse.de>
Cc: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
---
 drivers/md/raid1.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 954d028..e1ee446 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 */
 	sectors = align_to_barrier_unit_end(
 			bio->bi_iter.bi_sector, bio_sectors(bio));
-- 
2.9.3

Re: [PATCH] md/raid1: handle flush request correctly

[Coly Li]

On 2017/2/22 上午3:03, Shaohua Li wrote:
> 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: Coly Li <colyli@suse.de>
> Cc: NeilBrown <neilb@suse.com>
> Signed-off-by: Shaohua Li <shli@fb.com>

Acked-by: Coly Li <colyli@suse.de>

Thanks.

Coly

> ---
>  drivers/md/raid1.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 954d028..e1ee446 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 */
>  	sectors = align_to_barrier_unit_end(
>  			bio->bi_iter.bi_sector, bio_sectors(bio));
>