linux-kernel - Re: [PATCH 5/9] lightnvm: pblk: consider bad sectors in emeta during recovery

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Message-Id: <D02F472F-B94F-4577-A92C-9B3470753B15@lightnvm.io>
Date:   Tue, 3 Oct 2017 12:38:23 +0200
From:   Javier González <jg@...htnvm.io>
To:     Hans Holmberg <hans.ml.holmberg@...tronix.com>
Cc:     Matias Bjørling <mb@...htnvm.io>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hans Holmberg <hans.holmberg@...xlabs.com>
Subject: Re: [PATCH 5/9] lightnvm: pblk: consider bad sectors in emeta during
 recovery

> On 3 Oct 2017, at 12.05, Hans Holmberg <hans.ml.holmberg@...tronix.com> wrote:
> 
> From: Hans Holmberg <hans.holmberg@...xlabs.com>
> 
> When recovering lines we need to consider that bad blocks in a line
> affects the emeta area size.
> 
> Previously it was assumed that the emeta area would grow by the
> number of sectors per page * number of bad blocks in the line.
> 
> This assumtion not correct - the number of "extra" pages that are
> consumed could be both smaller (depending on emeta size) and bigger
> (depending on the placement of the bad blocks).

This assumption is not correct >> missing _is_

> 
> Fix this by calculating the emeta start by iterating backwards
> through the line, skipping ppas that map to bad blocks.
> 
> Also fix the data types used for ppa indices/counts in
> pblk_recov_l2p_from_emeta - we should use u64.
> 
> Signed-off-by: Hans Holmberg <hans.holmberg@...xlabs.com>
> ---
> drivers/lightnvm/pblk-recovery.c | 44 +++++++++++++++++++++++++++-------------
> 1 file changed, 30 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
> index 74b3b86..b5a2275 100644
> --- a/drivers/lightnvm/pblk-recovery.c
> +++ b/drivers/lightnvm/pblk-recovery.c
> @@ -133,16 +133,16 @@ static int pblk_recov_l2p_from_emeta(struct pblk *pblk, struct pblk_line *line)
> 	struct pblk_emeta *emeta = line->emeta;
> 	struct line_emeta *emeta_buf = emeta->buf;
> 	__le64 *lba_list;
> -	int data_start, data_end;
> -	int nr_valid_lbas, nr_lbas = 0;
> -	int i;
> +	u64 data_start, data_end;
> +	u64 nr_valid_lbas, nr_lbas = 0;
> +	u64 i;
> 
> 	lba_list = pblk_recov_get_lba_list(pblk, emeta_buf);
> 	if (!lba_list)
> 		return 1;
> 
> 	data_start = pblk_line_smeta_start(pblk, line) + lm->smeta_sec;
> -	data_end = lm->sec_per_line - lm->emeta_sec[0];
> +	data_end = line->emeta_ssec;
> 	nr_valid_lbas = le64_to_cpu(emeta_buf->nr_valid_lbas);
> 
> 	for (i = data_start; i < data_end; i++) {
> @@ -172,8 +172,8 @@ static int pblk_recov_l2p_from_emeta(struct pblk *pblk, struct pblk_line *line)
> 	}
> 
> 	if (nr_valid_lbas != nr_lbas)
> -		pr_err("pblk: line %d - inconsistent lba list(%llu/%d)\n",
> -				line->id, emeta_buf->nr_valid_lbas, nr_lbas);
> +		pr_err("pblk: line %d - inconsistent lba list(%llu/%llu)\n",
> +				line->id, nr_valid_lbas, nr_lbas);
> 
> 	line->left_msecs = 0;
> 
> @@ -827,11 +827,33 @@ static void pblk_recov_line_add_ordered(struct list_head *head,
> 	__list_add(&line->list, t->list.prev, &t->list);
> }
> 
> -struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
> +static u64 pblk_line_emeta_start(struct pblk *pblk, struct pblk_line *line)
> {
> 	struct nvm_tgt_dev *dev = pblk->dev;
> 	struct nvm_geo *geo = &dev->geo;
> 	struct pblk_line_meta *lm = &pblk->lm;
> +	unsigned int emeta_secs;
> +	u64 emeta_start;
> +	struct ppa_addr ppa;
> +	int pos;
> +
> +	emeta_secs = lm->emeta_sec[0];
> +	emeta_start = lm->sec_per_line;
> +
> +	while (emeta_secs) {
> +		emeta_start--;
> +		ppa = addr_to_pblk_ppa(pblk, emeta_start, line->id);
> +		pos = pblk_ppa_to_pos(geo, ppa);
> +		if (!test_bit(pos, line->blk_bitmap))
> +			emeta_secs--;
> +	}
> +
> +	return emeta_start;
> +}
> +
> +struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
> +{
> +	struct pblk_line_meta *lm = &pblk->lm;
> 	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
> 	struct pblk_line *line, *tline, *data_line = NULL;
> 	struct pblk_smeta *smeta;
> @@ -930,15 +952,9 @@ struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
> 
> 	/* Verify closed blocks and recover this portion of L2P table*/
> 	list_for_each_entry_safe(line, tline, &recov_list, list) {
> -		int off, nr_bb;
> -
> 		recovered_lines++;
> -		/* Calculate where emeta starts based on the line bb */
> -		off = lm->sec_per_line - lm->emeta_sec[0];
> -		nr_bb = bitmap_weight(line->blk_bitmap, lm->blk_per_line);
> -		off -= nr_bb * geo->sec_per_pl;
> 
> -		line->emeta_ssec = off;
> +		line->emeta_ssec = pblk_line_emeta_start(pblk, line);
> 		line->emeta = emeta;
> 		memset(line->emeta->buf, 0, lm->emeta_len[0]);
> 
> --
> 2.7.4

Apart from the commit message, it looks good.

Reviewed-by: Javier González <javier@...xlabs.com>

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