Re: [EXT] [PATCH] lightnvm: pblk: extend line wp balance check

[Hans Holmberg]

On Tue, Jan 29, 2019 at 11:10 PM Zhoujie Wu <zjwu@xxxxxxxxxxx> wrote:
>
> Sorry that my Linux email client has configuration issue and can't reply email. Used my outlook to reply as plain text and hope that I won't corrupt the format.
> Tested on my board and it works well. Since this is a good fix, I think you don't need to do it based on my previous v3 patch and can directly apply yours:)
>
> Tested-by: Zhoujie Wu <zjwu@xxxxxxxxxxx>

Thanks Zhoujie!

I'll squash the two patches into a V2, carrying over the tested-by and
credit you as Reported-by if you don't mind.


>
>
> -----Original Message-----
> From: hans@xxxxxxxxxxxxx <hans@xxxxxxxxxxxxx>
> Sent: Tuesday, January 29, 2019 12:48 AM
> To: Matias Bjorling <mb@xxxxxxxxxxx>
> Cc: javier@xxxxxxxxxxx; Zhoujie Wu <zjwu@xxxxxxxxxxx>; linux-block@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Hans Holmberg <hans.holmberg@xxxxxxxxxxxx>
> Subject: [EXT] [PATCH] lightnvm: pblk: extend line wp balance check
>
> External Email
>
> ----------------------------------------------------------------------
> From: Hans Holmberg <hans.holmberg@xxxxxxxxxxxx>
>
> pblk stripes writes of minimal write size across all non-offline chunks in a line, which means that the maximum write pointer delta should not exceed the minimal write size. Extend the line write pointer balance check to cover this case.
>
> Signed-off-by: Hans Holmberg <hans.holmberg@xxxxxxxxxxxx>
> ---
>
> This patch applies on top of Zhoujie's V3 of
> "lightnvm: pblk: ignore bad block wp for pblk_line_wp_is_unbalanced
>
>  drivers/lightnvm/pblk-recovery.c | 60 ++++++++++++++++++++------------
>  1 file changed, 37 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
> index 02d466e6925e..d86f580036d3 100644
> --- a/drivers/lightnvm/pblk-recovery.c
> +++ b/drivers/lightnvm/pblk-recovery.c
> @@ -302,41 +302,55 @@ static int pblk_pad_distance(struct pblk *pblk, struct pblk_line *line)
>         return (distance > line->left_msecs) ? line->left_msecs : distance;  }
>
> -static int pblk_line_wp_is_unbalanced(struct pblk *pblk,
> -                                     struct pblk_line *line)
> +/* Return a chunk belonging to a line by stripe(write order) index */
> +static struct nvm_chk_meta *pblk_get_stripe_chunk(struct pblk *pblk,
> +                                                 struct pblk_line *line,
> +                                                 int index)
>  {
>         struct nvm_tgt_dev *dev = pblk->dev;
>         struct nvm_geo *geo = &dev->geo;
> -       struct pblk_line_meta *lm = &pblk->lm;
>         struct pblk_lun *rlun;
> -       struct nvm_chk_meta *chunk;
>         struct ppa_addr ppa;
> -       u64 line_wp;
> -       int pos, i, bit;
> +       int pos;
>
> -       bit = find_first_zero_bit(line->blk_bitmap, lm->blk_per_line);
> -       if (bit >= lm->blk_per_line)
> -               return 0;
> -       rlun = &pblk->luns[bit];
> +       rlun = &pblk->luns[index];
>         ppa = rlun->bppa;
>         pos = pblk_ppa_to_pos(geo, ppa);
> -       chunk = &line->chks[pos];
>
> -       line_wp = chunk->wp;
> +       return &line->chks[pos];
> +}
>
> -       for (i = bit + 1; i < lm->blk_per_line; i++) {
> -               rlun = &pblk->luns[i];
> -               ppa = rlun->bppa;
> -               pos = pblk_ppa_to_pos(geo, ppa);
> -               chunk = &line->chks[pos];
> +static int pblk_line_wps_are_unbalanced(struct pblk *pblk,
> +                                     struct pblk_line *line)
> +{
> +       struct pblk_line_meta *lm = &pblk->lm;
> +       int blk_in_line = lm->blk_per_line;
> +       struct nvm_chk_meta *chunk;
> +       u64 max_wp, min_wp;
> +       int i;
>
> -               if (chunk->state & NVM_CHK_ST_OFFLINE)
> -                       continue;
> +       i = find_first_zero_bit(line->blk_bitmap, blk_in_line);
> +
> +       /* If there is one or zero good chunks in the line,
> +        * the write pointers can't be unbalanced.
> +        */
> +       if (i >= (blk_in_line - 1))
> +               return 0;
>
> -               if (chunk->wp > line_wp)
> +       chunk = pblk_get_stripe_chunk(pblk, line, i);
> +       max_wp = chunk->wp;
> +       if (max_wp > pblk->max_write_pgs)
> +               min_wp = max_wp - pblk->max_write_pgs;
> +       else
> +               min_wp = 0;
> +
> +       i = find_next_zero_bit(line->blk_bitmap, blk_in_line, i + 1);
> +       while (i < blk_in_line) {
> +               chunk = pblk_get_stripe_chunk(pblk, line, i);
> +               if (chunk->wp > max_wp || chunk->wp < min_wp)
>                         return 1;
> -               else if (chunk->wp < line_wp)
> -                       line_wp = chunk->wp;
> +
> +               i = find_next_zero_bit(line->blk_bitmap, blk_in_line, i + 1);
>         }
>
>         return 0;
> @@ -362,7 +376,7 @@ static int pblk_recov_scan_oob(struct pblk *pblk, struct pblk_line *line,
>         int ret;
>         u64 left_ppas = pblk_sec_in_open_line(pblk, line) - lm->smeta_sec;
>
> -       if (pblk_line_wp_is_unbalanced(pblk, line))
> +       if (pblk_line_wps_are_unbalanced(pblk, line))
>                 pblk_warn(pblk, "recovering unbalanced line (%d)\n", line->id);
>
>         ppa_list = p.ppa_list;
> --
> 2.17.1
>