Re: [PATCH v6] md: allow configuring logical block size

[Li Nan]

在 2025/9/28 9:46, Xiao Ni 写道:

> > +static struct md_sysfs_entry md_logical_block_size =
> > +__ATTR(logical_block_size, S_IRUGO|S_IWUSR, lbs_show, lbs_store);
> >
> >   static struct attribute *md_default_attrs[] = {
> >          &md_level.attr,
> > @@ -5933,6 +5995,7 @@ static struct attribute *md_redundancy_attrs[] = {
> >          &md_scan_mode.attr,
> >          &md_last_scan_mode.attr,
> >          &md_mismatches.attr,
> > +       &md_logical_block_size.attr,
>
> Hi
>
> I just saw your v5 replied email and noticed this place. The logcial
> block size doesn't have relationship with sync action, right?
> md_redundancy_attrs is used for sync attributes. So is it better to
> put this into md_default_attrs?

Hi, Thansks for your review.

Agree, I will move it to md_default_attrs in the next version.


> >          &md_sync_min.attr,
> >          &md_sync_max.attr,
> >          &md_sync_io_depth.attr,
> > @@ -6052,6 +6115,17 @@ int mddev_stack_rdev_limits(struct mddev *mddev, struct queue_limits *lim,
> >                          return -EINVAL;
> >          }
> >
> > +       /*
> > +        * Before RAID adding folio support, the logical_block_size
> > +        * should be smaller than the page size.
> > +        */
> > +       if (lim->logical_block_size > PAGE_SIZE) {
> > +               pr_err("%s: logical_block_size must not larger than PAGE_SIZE\n",
> > +                       mdname(mddev));
> > +               return -EINVAL;
> > +       }
> > +       mddev->logical_block_size = lim->logical_block_size;
> > +
> >          return 0;
> >   }
> >   EXPORT_SYMBOL_GPL(mddev_stack_rdev_limits);
> > @@ -6690,6 +6764,7 @@ static void md_clean(struct mddev *mddev)
> >          mddev->chunk_sectors = 0;
> >          mddev->ctime = mddev->utime = 0;
> >          mddev->layout = 0;
> > +       mddev->logical_block_size = 0;
> >          mddev->max_disks = 0;
> >          mddev->events = 0;
> >          mddev->can_decrease_events = 0;
> > diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> > index f1d8811a542a..705889a09fc1 100644
> > --- a/drivers/md/raid0.c
> > +++ b/drivers/md/raid0.c
> > @@ -382,6 +382,7 @@ static int raid0_set_limits(struct mddev *mddev)
> >          md_init_stacking_limits(&lim);
> >          lim.max_hw_sectors = mddev->chunk_sectors;
> >          lim.max_write_zeroes_sectors = mddev->chunk_sectors;
> > +       lim.logical_block_size = mddev->logical_block_size;
>
> raid0 creates zone stripes first based on the member disk's LBS. So
> it's not right to change the logical block size here?
>
> Best Regards
> Xiao

On further check, it is feasible to move raid0_set_limits before
create_strip_zones. I will fix it in the next version. Thank you for your
detailed review.

> >          lim.io_min = mddev->chunk_sectors << 9;
> >          lim.io_opt = lim.io_min * mddev->raid_disks;
> >          lim.chunk_sectors = mddev->chunk_sectors;
> > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> > index d0f6afd2f988..de0c843067dc 100644
> > --- a/drivers/md/raid1.c
> > +++ b/drivers/md/raid1.c
> > @@ -3223,6 +3223,7 @@ static int raid1_set_limits(struct mddev *mddev)
> >
> >          md_init_stacking_limits(&lim);
> >          lim.max_write_zeroes_sectors = 0;
> > +       lim.logical_block_size = mddev->logical_block_size;
> >          lim.features |= BLK_FEAT_ATOMIC_WRITES;
> >          err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
> >          if (err)
> > diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> > index c3cfbb0347e7..68c8148386b0 100644
> > --- a/drivers/md/raid10.c
> > +++ b/drivers/md/raid10.c
> > @@ -4005,6 +4005,7 @@ static int raid10_set_queue_limits(struct mddev *mddev)
> >
> >          md_init_stacking_limits(&lim);
> >          lim.max_write_zeroes_sectors = 0;
> > +       lim.logical_block_size = mddev->logical_block_size;
> >          lim.io_min = mddev->chunk_sectors << 9;
> >          lim.chunk_sectors = mddev->chunk_sectors;
> >          lim.io_opt = lim.io_min * raid10_nr_stripes(conf);
> > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> > index c32ffd9cffce..ff0daa22df65 100644
> > --- a/drivers/md/raid5.c
> > +++ b/drivers/md/raid5.c
> > @@ -7747,6 +7747,7 @@ static int raid5_set_limits(struct mddev *mddev)
> >          stripe = roundup_pow_of_two(data_disks * (mddev->chunk_sectors << 9));
> >
> >          md_init_stacking_limits(&lim);
> > +       lim.logical_block_size = mddev->logical_block_size;
> >          lim.io_min = mddev->chunk_sectors << 9;
> >          lim.io_opt = lim.io_min * (conf->raid_disks - conf->max_degraded);
> >          lim.features |= BLK_FEAT_RAID_PARTIAL_STRIPES_EXPENSIVE;
> > --
> > 2.39.2
>
>
> .

--
Thanks,
Nan