On Fri, Oct 6, 2023 at 8:24 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote: > > From: Yu Kuai <yukuai3@xxxxxxxxxx> > > Currently, discad io is treated the same as normal write io, and for > write behind case, io size is limited to: > > BIO_MAX_VECS * (PAGE_SIZE >> 9) > > For 0.5KB sector size and 4KB PAGE_SIZE, this is just 1MB. For > consequence, if 'WriteMostly' is set to one of the underlying disks, > then diskcard io will be splited into 1MB and it will take a long time > for the diskcard to finish. > > Fix this problem by disable write behind for discard io. > > Reported-by: Roman Mamedov <rm@xxxxxxxxxxx> > Closes: https://lore.kernel.org/all/6a1165f7-c792-c054-b8f0-1ad4f7b8ae01@xxxxxxxxxxxxxx/ > Reported-and-tested-by: Kirill Kirilenko <kirill@xxxxxxxxxxxxxx> > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> Applied to md-next. Thanks! Song > --- > drivers/md/raid1.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c > index 3a78f79ee6d5..35d12948e0a9 100644 > --- a/drivers/md/raid1.c > +++ b/drivers/md/raid1.c > @@ -1345,6 +1345,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, > int first_clone; > int max_sectors; > bool write_behind = false; > + bool is_discard = (bio_op(bio) == REQ_OP_DISCARD); > > if (mddev_is_clustered(mddev) && > md_cluster_ops->area_resyncing(mddev, WRITE, > @@ -1405,7 +1406,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, > * write-mostly, which means we could allocate write behind > * bio later. > */ > - if (rdev && test_bit(WriteMostly, &rdev->flags)) > + if (!is_discard && rdev && test_bit(WriteMostly, &rdev->flags)) > write_behind = true; > > if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) { > -- > 2.39.2 >
