Date:   Tue, 18 Sep 2018 08:09:40 +0000
From:   Javier Gonzalez <javier@...xlabs.com>
To:     "Konopko, Igor J" <igor.j.konopko@...el.com>
CC:     Matias Bjørling <mb@...htnvm.io>,
        "marcin.dziegielewski@...el.com" <marcin.dziegielewski@...el.com>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] lightnvm: pblk: support variable OOB size

> On 11 Sep 2018, at 12.22, Igor Konopko <igor.j.konopko@...el.com> wrote:
> 
> 
> 
> On 11.09.2018 11:14, Javier Gonzalez wrote:
>>> On 10 Sep 2018, at 12.21, Matias Bjørling <mb@...htnvm.io> wrote:
>>> 
>>> On 08/29/2018 12:09 PM, Javier González wrote:
>>>> pblk uses 8 bytes in the metadata region area exposed by the device
>>>> through the out of band area to store the lba mapped to the given
>>>> physical sector. This is used for recovery purposes. Given that the
>>>> first generation OCSSD devices exposed 16 bytes, pblk used a hard-coded
>>>> structure for this purpose.
>>>> This patch relaxes the 16 bytes assumption and uses the metadata size
>>>> reported by the device to layout metadata appropriately for the vector
>>>> commands. This adds support for arbitrary metadata sizes, as long as
>>>> these are larger than 8 bytes. Note that this patch does not address the
>>>> case in which the device does not expose an out of band area and that
>>>> pblk creation will fail in this case.
>>>> Signed-off-by: Javier González <javier@...xlabs.com>
>>>> ---
>>>>  drivers/lightnvm/pblk-core.c     | 56 ++++++++++++++++++++++++++++++----------
>>>>  drivers/lightnvm/pblk-init.c     | 14 ++++++++++
>>>>  drivers/lightnvm/pblk-map.c      | 19 +++++++++-----
>>>>  drivers/lightnvm/pblk-read.c     | 55 +++++++++++++++++++++++++--------------
>>>>  drivers/lightnvm/pblk-recovery.c | 34 +++++++++++++++++-------
>>>>  drivers/lightnvm/pblk.h          | 18 ++++++++++---
>>>>  6 files changed, 143 insertions(+), 53 deletions(-)
>>>> diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
>>>> index a311cc29afd8..d52e0047ae9d 100644
>>>> --- a/drivers/lightnvm/pblk-core.c
>>>> +++ b/drivers/lightnvm/pblk-core.c
>>>> @@ -250,8 +250,20 @@ int pblk_setup_rqd(struct pblk *pblk, struct nvm_rq *rqd, gfp_t mem_flags,
>>>>  	if (!is_vector)
>>>>  		return 0;
>>>>  -	rqd->ppa_list = rqd->meta_list + pblk_dma_meta_size;
>>>> -	rqd->dma_ppa_list = rqd->dma_meta_list + pblk_dma_meta_size;
>>>> +	if (pblk->dma_shared) {
>>>> +		rqd->ppa_list = rqd->meta_list + pblk->dma_meta_size;
>>>> +		rqd->dma_ppa_list = rqd->dma_meta_list + pblk->dma_meta_size;
>>>> +
>>>> +		return 0;
>>>> +	}
>>>> +
>>>> +	rqd->ppa_list = nvm_dev_dma_alloc(dev->parent, mem_flags,
>>>> +							&rqd->dma_ppa_list);
>>>> +	if (!rqd->ppa_list) {
>>>> +		nvm_dev_dma_free(dev->parent, rqd->meta_list,
>>>> +							rqd->dma_meta_list);
>>>> +		return -ENOMEM;
>>>> +	}
>>>>    	return 0;
>>>>  }
>>>> @@ -262,7 +274,11 @@ void pblk_clear_rqd(struct pblk *pblk, struct nvm_rq *rqd)
>>>>    	if (rqd->meta_list)
>>>>  		nvm_dev_dma_free(dev->parent, rqd->meta_list,
>>>> -				rqd->dma_meta_list);
>>>> +							rqd->dma_meta_list);
>>>> +
>>>> +	if (!pblk->dma_shared && rqd->ppa_list)
>>>> +		nvm_dev_dma_free(dev->parent, rqd->ppa_list,
>>>> +							rqd->dma_ppa_list);
>>>>  }
>>>>    /* Caller must guarantee that the request is a valid type */
>>>> @@ -796,10 +812,12 @@ static int pblk_line_smeta_write(struct pblk *pblk, struct pblk_line *line,
>>>>  	rqd.is_seq = 1;
>>>>    	for (i = 0; i < lm->smeta_sec; i++, paddr++) {
>>>> -		struct pblk_sec_meta *meta_list = rqd.meta_list;
>>>> +		struct pblk_sec_meta *meta;
>>>>    		rqd.ppa_list[i] = addr_to_gen_ppa(pblk, paddr, line->id);
>>>> -		meta_list[i].lba = lba_list[paddr] = addr_empty;
>>>> +
>>>> +		meta = sec_meta_index(pblk, rqd.meta_list, i);
>>>> +		meta->lba = lba_list[paddr] = addr_empty;
>>>>  	}
>>>>    	ret = pblk_submit_io_sync_sem(pblk, &rqd);
>>>> @@ -845,8 +863,17 @@ int pblk_line_emeta_read(struct pblk *pblk, struct pblk_line *line,
>>>>  	if (!meta_list)
>>>>  		return -ENOMEM;
>>>>  -	ppa_list = meta_list + pblk_dma_meta_size;
>>>> -	dma_ppa_list = dma_meta_list + pblk_dma_meta_size;
>>>> +	if (pblk->dma_shared) {
>>>> +		ppa_list = meta_list + pblk->dma_meta_size;
>>>> +		dma_ppa_list = dma_meta_list + pblk->dma_meta_size;
>>>> +	} else {
>>>> +		ppa_list = nvm_dev_dma_alloc(dev->parent, GFP_KERNEL,
>>>> +							&dma_ppa_list);
>>>> +		if (!ppa_list) {
>>>> +			ret = -ENOMEM;
>>>> +			goto free_meta_list;
>>>> +		}
>>>> +	}
>>>>    next_rq:
>>>>  	memset(&rqd, 0, sizeof(struct nvm_rq));
>>>> @@ -858,7 +885,7 @@ int pblk_line_emeta_read(struct pblk *pblk, struct pblk_line *line,
>>>>  					l_mg->emeta_alloc_type, GFP_KERNEL);
>>>>  	if (IS_ERR(bio)) {
>>>>  		ret = PTR_ERR(bio);
>>>> -		goto free_rqd_dma;
>>>> +		goto free_ppa_list;
>>>>  	}
>>>>    	bio->bi_iter.bi_sector = 0; /* internal bio */
>>>> @@ -884,7 +911,7 @@ int pblk_line_emeta_read(struct pblk *pblk, struct pblk_line *line,
>>>>  			if (pblk_boundary_paddr_checks(pblk, paddr)) {
>>>>  				bio_put(bio);
>>>>  				ret = -EINTR;
>>>> -				goto free_rqd_dma;
>>>> +				goto free_ppa_list;
>>>>  			}
>>>>    			ppa = addr_to_gen_ppa(pblk, paddr, line_id);
>>>> @@ -894,7 +921,7 @@ int pblk_line_emeta_read(struct pblk *pblk, struct pblk_line *line,
>>>>  		if (pblk_boundary_paddr_checks(pblk, paddr + min)) {
>>>>  			bio_put(bio);
>>>>  			ret = -EINTR;
>>>> -			goto free_rqd_dma;
>>>> +			goto free_ppa_list;
>>>>  		}
>>>>    		for (j = 0; j < min; j++, i++, paddr++)
>>>> @@ -905,7 +932,7 @@ int pblk_line_emeta_read(struct pblk *pblk, struct pblk_line *line,
>>>>  	if (ret) {
>>>>  		pblk_err(pblk, "emeta I/O submission failed: %d\n", ret);
>>>>  		bio_put(bio);
>>>> -		goto free_rqd_dma;
>>>> +		goto free_ppa_list;
>>>>  	}
>>>>    	atomic_dec(&pblk->inflight_io);
>>>> @@ -918,8 +945,11 @@ int pblk_line_emeta_read(struct pblk *pblk, struct pblk_line *line,
>>>>  	if (left_ppas)
>>>>  		goto next_rq;
>>>>  -free_rqd_dma:
>>>> -	nvm_dev_dma_free(dev->parent, rqd.meta_list, rqd.dma_meta_list);
>>>> +free_ppa_list:
>>>> +	if (!pblk->dma_shared)
>>>> +		nvm_dev_dma_free(dev->parent, ppa_list, dma_ppa_list);
>>>> +free_meta_list:
>>>> +	nvm_dev_dma_free(dev->parent, meta_list, dma_meta_list);
>>>>  	return ret;
>>>>  }
>>>>  diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
>>>> index a99854439224..57972156c318 100644
>>>> --- a/drivers/lightnvm/pblk-init.c
>>>> +++ b/drivers/lightnvm/pblk-init.c
>>>> @@ -354,6 +354,20 @@ static int pblk_core_init(struct pblk *pblk)
>>>>  	struct nvm_geo *geo = &dev->geo;
>>>>  	int ret, max_write_ppas;
>>>>  +	if (sizeof(struct pblk_sec_meta) > geo->sos) {
>>>> +		pblk_err(pblk, "OOB area too small. Min %lu bytes (%d)\n",
>>>> +			(unsigned long)sizeof(struct pblk_sec_meta), geo->sos);
>>>> +		return -EINTR;
>>>> +	}
>>>> +
>>>> +	pblk->dma_ppa_size = (sizeof(u64) * NVM_MAX_VLBA);
>>>> +	pblk->dma_meta_size = geo->sos * NVM_MAX_VLBA;
>>>> +
>>>> +	if (pblk->dma_ppa_size + pblk->dma_meta_size > PAGE_SIZE)
>>>> +		pblk->dma_shared = false;
>>>> +	else
>>>> +		pblk->dma_shared = true;
>>>> +
>>>>  	atomic64_set(&pblk->user_wa, 0);
>>>>  	atomic64_set(&pblk->pad_wa, 0);
>>>>  	atomic64_set(&pblk->gc_wa, 0);
>>>> diff --git a/drivers/lightnvm/pblk-map.c b/drivers/lightnvm/pblk-map.c
>>>> index dc0efb852475..55fca16d18e4 100644
>>>> --- a/drivers/lightnvm/pblk-map.c
>>>> +++ b/drivers/lightnvm/pblk-map.c
>>>> @@ -25,6 +25,7 @@ static int pblk_map_page_data(struct pblk *pblk, unsigned int sentry,
>>>>  			      unsigned int valid_secs)
>>>>  {
>>>>  	struct pblk_line *line = pblk_line_get_data(pblk);
>>>> +	struct pblk_sec_meta *meta;
>>>>  	struct pblk_emeta *emeta;
>>>>  	struct pblk_w_ctx *w_ctx;
>>>>  	__le64 *lba_list;
>>>> @@ -56,6 +57,8 @@ static int pblk_map_page_data(struct pblk *pblk, unsigned int sentry,
>>>>  		/* ppa to be sent to the device */
>>>>  		ppa_list[i] = addr_to_gen_ppa(pblk, paddr, line->id);
>>>>  +		meta = sec_meta_index(pblk, meta_list, i);
>>>> +
>>>>  		/* Write context for target bio completion on write buffer. Note
>>>>  		 * that the write buffer is protected by the sync backpointer,
>>>>  		 * and a single writer thread have access to each specific entry
>>>> @@ -67,14 +70,14 @@ static int pblk_map_page_data(struct pblk *pblk, unsigned int sentry,
>>>>  			kref_get(&line->ref);
>>>>  			w_ctx = pblk_rb_w_ctx(&pblk->rwb, sentry + i);
>>>>  			w_ctx->ppa = ppa_list[i];
>>>> -			meta_list[i].lba = cpu_to_le64(w_ctx->lba);
>>>> +			meta->lba = cpu_to_le64(w_ctx->lba);
>>>>  			lba_list[paddr] = cpu_to_le64(w_ctx->lba);
>>>>  			if (lba_list[paddr] != addr_empty)
>>>>  				line->nr_valid_lbas++;
>>>>  			else
>>>>  				atomic64_inc(&pblk->pad_wa);
>>>>  		} else {
>>>> -			lba_list[paddr] = meta_list[i].lba = addr_empty;
>>>> +			lba_list[paddr] = meta->lba = addr_empty;
>>>>  			__pblk_map_invalidate(pblk, line, paddr);
>>>>  		}
>>>>  	}
>>>> @@ -87,7 +90,7 @@ void pblk_map_rq(struct pblk *pblk, struct nvm_rq *rqd, unsigned int sentry,
>>>>  		 unsigned long *lun_bitmap, unsigned int valid_secs,
>>>>  		 unsigned int off)
>>>>  {
>>>> -	struct pblk_sec_meta *meta_list = rqd->meta_list;
>>>> +	struct pblk_sec_meta *meta_list;
>>>>  	struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);
>>>>  	unsigned int map_secs;
>>>>  	int min = pblk->min_write_pgs;
>>>> @@ -95,8 +98,10 @@ void pblk_map_rq(struct pblk *pblk, struct nvm_rq *rqd, unsigned int sentry,
>>>>    	for (i = off; i < rqd->nr_ppas; i += min) {
>>>>  		map_secs = (i + min > valid_secs) ? (valid_secs % min) : min;
>>>> +		meta_list = sec_meta_index(pblk, rqd->meta_list, i);
>>>> +
>>>>  		if (pblk_map_page_data(pblk, sentry + i, &ppa_list[i],
>>>> -					lun_bitmap, &meta_list[i], map_secs)) {
>>>> +					lun_bitmap, meta_list, map_secs)) {
>>>>  			bio_put(rqd->bio);
>>>>  			pblk_free_rqd(pblk, rqd, PBLK_WRITE);
>>>>  			pblk_pipeline_stop(pblk);
>>>> @@ -112,8 +117,8 @@ void pblk_map_erase_rq(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  	struct nvm_tgt_dev *dev = pblk->dev;
>>>>  	struct nvm_geo *geo = &dev->geo;
>>>>  	struct pblk_line_meta *lm = &pblk->lm;
>>>> -	struct pblk_sec_meta *meta_list = rqd->meta_list;
>>>>  	struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);
>>>> +	struct pblk_sec_meta *meta_list;
>>>>  	struct pblk_line *e_line, *d_line;
>>>>  	unsigned int map_secs;
>>>>  	int min = pblk->min_write_pgs;
>>>> @@ -121,8 +126,10 @@ void pblk_map_erase_rq(struct pblk *pblk, struct nvm_rq *rqd,
>>>>    	for (i = 0; i < rqd->nr_ppas; i += min) {
>>>>  		map_secs = (i + min > valid_secs) ? (valid_secs % min) : min;
>>>> +		meta_list = sec_meta_index(pblk, rqd->meta_list, i);
>>>> +
>>>>  		if (pblk_map_page_data(pblk, sentry + i, &ppa_list[i],
>>>> -					lun_bitmap, &meta_list[i], map_secs)) {
>>>> +					lun_bitmap, meta_list, map_secs)) {
>>>>  			bio_put(rqd->bio);
>>>>  			pblk_free_rqd(pblk, rqd, PBLK_WRITE);
>>>>  			pblk_pipeline_stop(pblk);
>>>> diff --git a/drivers/lightnvm/pblk-read.c b/drivers/lightnvm/pblk-read.c
>>>> index 57d3155ef9a5..12b690e2abd9 100644
>>>> --- a/drivers/lightnvm/pblk-read.c
>>>> +++ b/drivers/lightnvm/pblk-read.c
>>>> @@ -42,7 +42,6 @@ static void pblk_read_ppalist_rq(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  				 struct bio *bio, sector_t blba,
>>>>  				 unsigned long *read_bitmap)
>>>>  {
>>>> -	struct pblk_sec_meta *meta_list = rqd->meta_list;
>>>>  	struct ppa_addr ppas[NVM_MAX_VLBA];
>>>>  	int nr_secs = rqd->nr_ppas;
>>>>  	bool advanced_bio = false;
>>>> @@ -51,13 +50,16 @@ static void pblk_read_ppalist_rq(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  	pblk_lookup_l2p_seq(pblk, ppas, blba, nr_secs);
>>>>    	for (i = 0; i < nr_secs; i++) {
>>>> +		struct pblk_sec_meta *meta;
>>>>  		struct ppa_addr p = ppas[i];
>>>>  		sector_t lba = blba + i;
>>>>  +		meta = sec_meta_index(pblk, rqd->meta_list, i);
>>>>  retry:
>>>>  		if (pblk_ppa_empty(p)) {
>>>>  			WARN_ON(test_and_set_bit(i, read_bitmap));
>>>> -			meta_list[i].lba = cpu_to_le64(ADDR_EMPTY);
>>>> +
>>>> +			meta->lba = cpu_to_le64(ADDR_EMPTY);
>>>>    			if (unlikely(!advanced_bio)) {
>>>>  				bio_advance(bio, (i) * PBLK_EXPOSED_PAGE_SIZE);
>>>> @@ -77,7 +79,7 @@ static void pblk_read_ppalist_rq(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  				goto retry;
>>>>  			}
>>>>  			WARN_ON(test_and_set_bit(i, read_bitmap));
>>>> -			meta_list[i].lba = cpu_to_le64(lba);
>>>> +			meta->lba = cpu_to_le64(lba);
>>>>  			advanced_bio = true;
>>>>  #ifdef CONFIG_NVM_PBLK_DEBUG
>>>>  			atomic_long_inc(&pblk->cache_reads);
>>>> @@ -104,12 +106,15 @@ static void pblk_read_ppalist_rq(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  static void pblk_read_check_seq(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  				sector_t blba)
>>>>  {
>>>> -	struct pblk_sec_meta *meta_lba_list = rqd->meta_list;
>>>>  	int nr_lbas = rqd->nr_ppas;
>>>>  	int i;
>>>>    	for (i = 0; i < nr_lbas; i++) {
>>>> -		u64 lba = le64_to_cpu(meta_lba_list[i].lba);
>>>> +		struct pblk_sec_meta *meta;
>>>> +		u64 lba;
>>>> +
>>>> +		meta = sec_meta_index(pblk, rqd->meta_list, i);
>>>> +		lba = le64_to_cpu(meta->lba);
>>>>    		if (lba == ADDR_EMPTY)
>>>>  			continue;
>>>> @@ -133,17 +138,18 @@ static void pblk_read_check_seq(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  static void pblk_read_check_rand(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  				 u64 *lba_list, int nr_lbas)
>>>>  {
>>>> -	struct pblk_sec_meta *meta_lba_list = rqd->meta_list;
>>>>  	int i, j;
>>>>    	for (i = 0, j = 0; i < nr_lbas; i++) {
>>>> +		struct pblk_sec_meta *meta;
>>>>  		u64 lba = lba_list[i];
>>>>  		u64 meta_lba;
>>>>    		if (lba == ADDR_EMPTY)
>>>>  			continue;
>>>>  -		meta_lba = le64_to_cpu(meta_lba_list[j].lba);
>>>> +		meta = sec_meta_index(pblk, rqd->meta_list, j);
>>>> +		meta_lba = le64_to_cpu(meta->lba);
>>>>    		if (lba != meta_lba) {
>>>>  #ifdef CONFIG_NVM_PBLK_DEBUG
>>>> @@ -218,7 +224,7 @@ static void pblk_end_partial_read(struct nvm_rq *rqd)
>>>>  	struct bio *new_bio = rqd->bio;
>>>>  	struct bio *bio = pr_ctx->orig_bio;
>>>>  	struct bio_vec src_bv, dst_bv;
>>>> -	struct pblk_sec_meta *meta_list = rqd->meta_list;
>>>> +	struct pblk_sec_meta *meta;
>>>>  	int bio_init_idx = pr_ctx->bio_init_idx;
>>>>  	unsigned long *read_bitmap = pr_ctx->bitmap;
>>>>  	int nr_secs = pr_ctx->orig_nr_secs;
>>>> @@ -237,12 +243,13 @@ static void pblk_end_partial_read(struct nvm_rq *rqd)
>>>>  	}
>>>>    	/* Re-use allocated memory for intermediate lbas */
>>>> -	lba_list_mem = (((void *)rqd->ppa_list) + pblk_dma_ppa_size);
>>>> -	lba_list_media = (((void *)rqd->ppa_list) + 2 * pblk_dma_ppa_size);
>>>> +	lba_list_mem = (((void *)rqd->ppa_list) + pblk->dma_ppa_size);
>>>> +	lba_list_media = (((void *)rqd->ppa_list) + 2 * pblk->dma_ppa_size);
>>>>    	for (i = 0; i < nr_secs; i++) {
>>>> -		lba_list_media[i] = meta_list[i].lba;
>>>> -		meta_list[i].lba = lba_list_mem[i];
>>>> +		meta = sec_meta_index(pblk, rqd->meta_list, i);
>>>> +		lba_list_media[i] = meta->lba;
>>>> +		meta->lba = lba_list_mem[i];
>>>>  	}
>>>>    	/* Fill the holes in the original bio */
>>>> @@ -254,7 +261,8 @@ static void pblk_end_partial_read(struct nvm_rq *rqd)
>>>>  		line = pblk_ppa_to_line(pblk, rqd->ppa_list[i]);
>>>>  		kref_put(&line->ref, pblk_line_put);
>>>>  -		meta_list[hole].lba = lba_list_media[i];
>>>> +		meta = sec_meta_index(pblk, rqd->meta_list, hole);
>>>> +		meta->lba = lba_list_media[i];
>>>>    		src_bv = new_bio->bi_io_vec[i++];
>>>>  		dst_bv = bio->bi_io_vec[bio_init_idx + hole];
>>>> @@ -290,8 +298,8 @@ static int pblk_setup_partial_read(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  			    unsigned long *read_bitmap,
>>>>  			    int nr_holes)
>>>>  {
>>>> -	struct pblk_sec_meta *meta_list = rqd->meta_list;
>>>>  	struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
>>>> +	struct pblk_sec_meta *meta;
>>>>  	struct pblk_pr_ctx *pr_ctx;
>>>>  	struct bio *new_bio, *bio = r_ctx->private;
>>>>  	__le64 *lba_list_mem;
>>>> @@ -299,7 +307,7 @@ static int pblk_setup_partial_read(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  	int i;
>>>>    	/* Re-use allocated memory for intermediate lbas */
>>>> -	lba_list_mem = (((void *)rqd->ppa_list) + pblk_dma_ppa_size);
>>>> +	lba_list_mem = (((void *)rqd->ppa_list) + pblk->dma_ppa_size);
>>>>    	new_bio = bio_alloc(GFP_KERNEL, nr_holes);
>>>>  @@ -315,8 +323,10 @@ static int pblk_setup_partial_read(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  	if (!pr_ctx)
>>>>  		goto fail_free_pages;
>>>>  -	for (i = 0; i < nr_secs; i++)
>>>> -		lba_list_mem[i] = meta_list[i].lba;
>>>> +	for (i = 0; i < nr_secs; i++) {
>>>> +		meta = sec_meta_index(pblk, rqd->meta_list, i);
>>>> +		lba_list_mem[i] = meta->lba;
>>>> +	}
>>>>    	new_bio->bi_iter.bi_sector = 0; /* internal bio */
>>>>  	bio_set_op_attrs(new_bio, REQ_OP_READ, 0);
>>>> @@ -382,7 +392,7 @@ static int pblk_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
>>>>  static void pblk_read_rq(struct pblk *pblk, struct nvm_rq *rqd, struct bio *bio,
>>>>  			 sector_t lba, unsigned long *read_bitmap)
>>>>  {
>>>> -	struct pblk_sec_meta *meta_list = rqd->meta_list;
>>>> +	struct pblk_sec_meta *meta;
>>>>  	struct ppa_addr ppa;
>>>>    	pblk_lookup_l2p_seq(pblk, &ppa, lba, 1);
>>>> @@ -394,7 +404,10 @@ static void pblk_read_rq(struct pblk *pblk, struct nvm_rq *rqd, struct bio *bio,
>>>>  retry:
>>>>  	if (pblk_ppa_empty(ppa)) {
>>>>  		WARN_ON(test_and_set_bit(0, read_bitmap));
>>>> -		meta_list[0].lba = cpu_to_le64(ADDR_EMPTY);
>>>> +
>>>> +		meta = sec_meta_index(pblk, rqd->meta_list, 0);
>>>> +		meta->lba = cpu_to_le64(ADDR_EMPTY);
>>>> +
>>>>  		return;
>>>>  	}
>>>>  @@ -408,7 +421,9 @@ static void pblk_read_rq(struct pblk *pblk, struct nvm_rq *rqd, struct bio *bio,
>>>>  		}
>>>>    		WARN_ON(test_and_set_bit(0, read_bitmap));
>>>> -		meta_list[0].lba = cpu_to_le64(lba);
>>>> +
>>>> +		meta = sec_meta_index(pblk, rqd->meta_list, 0);
>>>> +		meta->lba = cpu_to_le64(lba);
>>>>    #ifdef CONFIG_NVM_PBLK_DEBUG
>>>>  		atomic_long_inc(&pblk->cache_reads);
>>>> diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
>>>> index 8114013c37b8..1ce92562603d 100644
>>>> --- a/drivers/lightnvm/pblk-recovery.c
>>>> +++ b/drivers/lightnvm/pblk-recovery.c
>>>> @@ -157,7 +157,7 @@ static int pblk_recov_pad_line(struct pblk *pblk, struct pblk_line *line,
>>>>  {
>>>>  	struct nvm_tgt_dev *dev = pblk->dev;
>>>>  	struct nvm_geo *geo = &dev->geo;
>>>> -	struct pblk_sec_meta *meta_list;
>>>> +	struct pblk_sec_meta *meta;
>>>>  	struct pblk_pad_rq *pad_rq;
>>>>  	struct nvm_rq *rqd;
>>>>  	struct bio *bio;
>>>> @@ -218,8 +218,6 @@ static int pblk_recov_pad_line(struct pblk *pblk, struct pblk_line *line,
>>>>  	rqd->end_io = pblk_end_io_recov;
>>>>  	rqd->private = pad_rq;
>>>>  -	meta_list = rqd->meta_list;
>>>> -
>>>>  	for (i = 0; i < rqd->nr_ppas; ) {
>>>>  		struct ppa_addr ppa;
>>>>  		int pos;
>>>> @@ -241,8 +239,10 @@ static int pblk_recov_pad_line(struct pblk *pblk, struct pblk_line *line,
>>>>  			dev_ppa = addr_to_gen_ppa(pblk, w_ptr, line->id);
>>>>    			pblk_map_invalidate(pblk, dev_ppa);
>>>> -			lba_list[w_ptr] = meta_list[i].lba = addr_empty;
>>>>  			rqd->ppa_list[i] = dev_ppa;
>>>> +
>>>> +			meta = sec_meta_index(pblk, rqd->meta_list, i);
>>>> +			lba_list[w_ptr] = meta->lba = addr_empty;
>>>>  		}
>>>>  	}
>>>>  @@ -327,7 +327,7 @@ static int pblk_recov_scan_oob(struct pblk *pblk, struct pblk_line *line,
>>>>  	struct nvm_tgt_dev *dev = pblk->dev;
>>>>  	struct nvm_geo *geo = &dev->geo;
>>>>  	struct ppa_addr *ppa_list;
>>>> -	struct pblk_sec_meta *meta_list;
>>>> +	struct pblk_sec_meta *meta_list, *meta;
>>>>  	struct nvm_rq *rqd;
>>>>  	struct bio *bio;
>>>>  	void *data;
>>>> @@ -425,7 +425,10 @@ static int pblk_recov_scan_oob(struct pblk *pblk, struct pblk_line *line,
>>>>  	}
>>>>    	for (i = 0; i < rqd->nr_ppas; i++) {
>>>> -		u64 lba = le64_to_cpu(meta_list[i].lba);
>>>> +		u64 lba;
>>>> +
>>>> +		meta = sec_meta_index(pblk, meta_list, i);
>>>> +		lba = le64_to_cpu(meta->lba);
>>>>    		lba_list[paddr++] = cpu_to_le64(lba);
>>>>  @@ -464,13 +467,22 @@ static int pblk_recov_l2p_from_oob(struct pblk *pblk, struct pblk_line *line)
>>>>  	if (!meta_list)
>>>>  		return -ENOMEM;
>>>>  -	ppa_list = (void *)(meta_list) + pblk_dma_meta_size;
>>>> -	dma_ppa_list = dma_meta_list + pblk_dma_meta_size;
>>>> +	if (pblk->dma_shared) {
>>>> +		ppa_list = (void *)(meta_list) + pblk->dma_meta_size;
>>>> +		dma_ppa_list = dma_meta_list + pblk->dma_meta_size;
>>>> +	} else {
>>>> +		ppa_list = nvm_dev_dma_alloc(dev->parent, GFP_KERNEL,
>>>> +							&dma_ppa_list);
>>>> +		if (!ppa_list) {
>>>> +			ret = -ENOMEM;
>>>> +			goto free_meta_list;
>>>> +		}
>>>> +	}
>>>>    	data = kcalloc(pblk->max_write_pgs, geo->csecs, GFP_KERNEL);
>>>>  	if (!data) {
>>>>  		ret = -ENOMEM;
>>>> -		goto free_meta_list;
>>>> +		goto free_ppa_list;
>>>>  	}
>>>>    	rqd = mempool_alloc(&pblk->r_rq_pool, GFP_KERNEL);
>>>> @@ -495,9 +507,11 @@ static int pblk_recov_l2p_from_oob(struct pblk *pblk, struct pblk_line *line)
>>>>  out:
>>>>  	mempool_free(rqd, &pblk->r_rq_pool);
>>>>  	kfree(data);
>>>> +free_ppa_list:
>>>> +	if (!pblk->dma_shared)
>>>> +		nvm_dev_dma_free(dev->parent, ppa_list, dma_ppa_list);
>>>>  free_meta_list:
>>>>  	nvm_dev_dma_free(dev->parent, meta_list, dma_meta_list);
>>>> -
>>>>  	return ret;
>>>>  }
>>>>  diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
>>>> index 22cc9bfbbb10..4526fee206d9 100644
>>>> --- a/drivers/lightnvm/pblk.h
>>>> +++ b/drivers/lightnvm/pblk.h
>>>> @@ -86,7 +86,6 @@ enum {
>>>>  };
>>>>    struct pblk_sec_meta {
>>>> -	u64 reserved;
>>>>  	__le64 lba;
>>>>  };
>>>>  @@ -103,9 +102,6 @@ enum {
>>>>  	PBLK_RL_LOW = 4
>>>>  };
>>>>  -#define pblk_dma_meta_size (sizeof(struct pblk_sec_meta) * NVM_MAX_VLBA)
>>>> -#define pblk_dma_ppa_size (sizeof(u64) * NVM_MAX_VLBA)
>>>> -
>>>>  /* write buffer completion context */
>>>>  struct pblk_c_ctx {
>>>>  	struct list_head list;		/* Head for out-of-order completion */
>>>> @@ -637,6 +633,10 @@ struct pblk {
>>>>    	int sec_per_write;
>>>>  +	int dma_meta_size;
>>>> +	int dma_ppa_size;
>>>> +	bool dma_shared;
>>>> +
>>>>  	unsigned char instance_uuid[16];
>>>>    	/* Persistent write amplification counters, 4kb sector I/Os */
>>>> @@ -985,6 +985,16 @@ static inline void *emeta_to_vsc(struct pblk *pblk, struct line_emeta *emeta)
>>>>  	return (emeta_to_lbas(pblk, emeta) + pblk->lm.emeta_len[2]);
>>>>  }
>>>>  +static inline struct pblk_sec_meta *sec_meta_index(struct pblk *pblk,
>>>> +						   struct pblk_sec_meta *meta,
>>>> +						   int index)
>>>> +{
>>>> +	struct nvm_tgt_dev *dev = pblk->dev;
>>>> +	struct nvm_geo *geo = &dev->geo;
>>>> +
>>>> +	return ((void *)meta + index * geo->sos);
>>>> +}
>>>> +
>>>>  static inline int pblk_line_vsc(struct pblk_line *line)
>>>>  {
>>>>  	return le32_to_cpu(*line->vsc);
>>> 
>>> It will be helpful to split this patch into two:
>>> 
>>> - One that does the 8b conversion
>>> - One that makes the change to merge metadata and ppa list data buffers
>> pblk has always shared the dma buffer for the ppa list and the metadata
>> buffer. This patch adds the possibility to not merge if the metadata
>> size does not fit. I can separate it in 2 patches, but it seems to me
>> like a natural extension when relaxing the 16byte metadata size.
>>>  - How about making it a simplification to only allow up to 32b
>>>    metadata buffers, then one doesn't have to think about it crossing
>>>    multiple pages.
>> You mean max. 56 bytes of metadata per 4KB right? That is what is left
>> on a 4KB pages after taking out the 512B needed by the ppa list. It's ok
>> by me, but I'd like to hear Igor's opinion, as this was Intel's use case
>> to start with.
> 
> So I think that if we want to do this properly, we should support
> 'all' the metadata sizes, including >64K - which is not the case after
> Javier changes. In the past there were NVMe drives available with 128
> bytes of metadata per 4K sector, so it could be similar in future too
> for OC drives. I have somewhere patch which should work for any size
> of metadata with slightly different approach. I can send it (just need
> a moment for rebase) and you will decide which approach you would like
> to take.
> 
>>>  - You can also make a structure for it, use the first 3.5KB for meta,
>>>    and the next 512B for PPAs.
>> Looks like a huge structure for just managing a couple of pointers,
>> don't you think?
>> Javier


Matias,

Can you pick up this patch as is for this window and then Igor can extend
it to an arbitrary size in the future? We have a use case for 64B OOB /
4KB, so 56B / 4KB is not enough in this case. Since pblk currently fixes
the metadata buffer, the code brakes under this configuration.

If you have any comments that can respect this requirement, I can apply
them and resubmit.

Thanks,
Javier

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