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Subject[PATCH] lightnvm: pblk: extend line wp balance check
Date
From: Hans Holmberg <hans.holmberg@cnexlabs.com>

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@cnexlabs.com>
---

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
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