On Wed, May 16, 2018 at 05:18:39PM +0800, Jianchao Wang wrote:
> For sb version 0.90 and 1.0 which locates after data, when we increase
> the spindle volume size and grow the raid arry size, the older sb which is
> different between spindles will be left there. Due to this left sb, the
> spindle volume cannot be grown with zero filled part with --asume-clean.
> applications have to take some workarounds such as sync_min/max to avoid
> resync.
>
> It is easy and convevient for md to zero the older sb position after
> write sb to new position, so do it here.
>From the description, this looks easy to do in userspace, eg, you can zero the
super before increase the spindle volume. Convenience isn't a reason we should
put these code into kernel space.
Thanks,
Shaohua
> Cc: robert.butera@xxxxxxxxxx
> Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
> ---
> drivers/md/md.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index c208c01..a042add 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -1020,6 +1020,23 @@ int md_check_no_bitmap(struct mddev *mddev)
> }
> EXPORT_SYMBOL(md_check_no_bitmap);
>
> +static void md_zero_original_sb_position(struct md_rdev *rdev, sector_t old_pos)
> +{
> + struct page *zero_pg;
> +
> + zero_pg = alloc_pages(GFP_KERNEL | __GFP_ZERO, 0);
> + if (!zero_pg) {
> + pr_warn("%s: failed to get page for zero original sb position",
> + mdname(rdev->mddev));
> + return;
> + }
> + md_super_write(rdev->mddev, rdev, old_pos, rdev->sb_size,
> + zero_pg);
> + wait_event(rdev->mddev->sb_wait,
> + (atomic_read(&rdev->mddev->pending_writes) == 0));
> + __free_pages(zero_pg, 0);
> +}
> +
> /*
> * load_super for 0.90.0
> */
> @@ -1394,6 +1411,8 @@ static void super_90_sync(struct mddev *mddev, struct md_rdev *rdev)
> static unsigned long long
> super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
> {
> + sector_t old_pos = rdev->sb_start;
> +
> if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
> return 0; /* component must fit device */
> if (rdev->mddev->bitmap_info.offset)
> @@ -1411,6 +1430,8 @@ super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
> md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
> rdev->sb_page);
> } while (md_super_wait(rdev->mddev) < 0);
> +
> + md_zero_original_sb_position(rdev, old_pos);
> return num_sectors;
> }
>
> @@ -1953,6 +1974,8 @@ super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
> {
> struct mdp_superblock_1 *sb;
> sector_t max_sectors;
> + sector_t old_pos = 0;
> +
> if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
> return 0; /* component must fit device */
> if (rdev->data_offset != rdev->new_data_offset)
> @@ -1969,6 +1992,7 @@ super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
> } else {
> /* minor version 0; superblock after data */
> sector_t sb_start;
> + old_pos = rdev->sb_start;
> sb_start = (i_size_read(rdev->bdev->bd_inode) >> 9) - 8*2;
> sb_start &= ~(sector_t)(4*2 - 1);
> max_sectors = rdev->sectors + sb_start - rdev->sb_start;
> @@ -1984,6 +2008,9 @@ super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
> md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
> rdev->sb_page);
> } while (md_super_wait(rdev->mddev) < 0);
> +
> + if (old_pos)
> + md_zero_original_sb_position(rdev, old_pos);
> return num_sectors;
>
> }
> --
> 2.7.4
>
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