Date:   Mon, 20 Aug 2018 12:13:11 +0000
From:   Javier Gonzalez <javier@...xlabs.com>
To:     Matias Bjørling <mb@...htnvm.io>
CC:     "Konopko, Igor J" <igor.j.konopko@...el.com>,
        "marcin.dziegielewski@...el.com" <marcin.dziegielewski@...el.com>,
        Hans Holmberg <hans.holmberg@...xlabs.com>,
        Heiner Litz <hlitz@...c.edu>,
        Young Tack Tack Jin <youngtack.jin@...cuitblvd.com>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] lightnvm: move bad block and chunk state logic to core

> On 17 Aug 2018, at 13.14, Matias Bjørling <mb@...htnvm.io> wrote:
> 
> pblk implements two data paths for recovery line state. One for 1.2
> and another for 2.0, instead of having pblk implement these, combine
> them in the core to reduce complexity and make available to other
> targets.
> 
> The new interface will adhere to the 2.0 chunk definition,
> including managing open chunks with an active write pointer. To provide
> this interface, a 1.2 device recovers the state of the chunks by
> manually detecting if a chunk is either free/open/close/offline, and if
> open, scanning the flash pages sequentially to find the next writeable
> page. This process takes on average ~10 seconds on a device with 64 dies,
> 1024 blocks and 60us read access time. The process can be parallelized
> but is left out for maintenance simplicity, as the 1.2 specification is
> deprecated. For 2.0 devices, the logic is maintained internally in the
> drive and retrieved through the 2.0 interface.

A couple of things from closer review.

> 
> Signed-off-by: Matias Bjørling <mb@...htnvm.io>
> ---
> drivers/lightnvm/core.c      | 310 +++++++++++++++++++++++++++++++++++--------
> drivers/lightnvm/pblk-core.c |   6 +-
> drivers/lightnvm/pblk-init.c | 116 +---------------
> drivers/lightnvm/pblk.h      |   2 +-
> drivers/nvme/host/lightnvm.c |   4 +-
> include/linux/lightnvm.h     |  15 +--
> 6 files changed, 266 insertions(+), 187 deletions(-)
> 
> diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
> index 964352720a03..003fc073f496 100644
> --- a/drivers/lightnvm/core.c
> +++ b/drivers/lightnvm/core.c
> @@ -717,46 +717,6 @@ static void nvm_free_rqd_ppalist(struct nvm_tgt_dev *tgt_dev,
> 	nvm_dev_dma_free(tgt_dev->parent, rqd->ppa_list, rqd->dma_ppa_list);
> }
> 
> -int nvm_get_chunk_meta(struct nvm_tgt_dev *tgt_dev, struct nvm_chk_meta *meta,
> -		struct ppa_addr ppa, int nchks)
> -{
> -	struct nvm_dev *dev = tgt_dev->parent;
> -
> -	nvm_ppa_tgt_to_dev(tgt_dev, &ppa, 1);
> -
> -	return dev->ops->get_chk_meta(tgt_dev->parent, meta,
> -						(sector_t)ppa.ppa, nchks);
> -}
> -EXPORT_SYMBOL(nvm_get_chunk_meta);
> -
> -int nvm_set_tgt_bb_tbl(struct nvm_tgt_dev *tgt_dev, struct ppa_addr *ppas,
> -		       int nr_ppas, int type)
> -{
> -	struct nvm_dev *dev = tgt_dev->parent;
> -	struct nvm_rq rqd;
> -	int ret;
> -
> -	if (nr_ppas > NVM_MAX_VLBA) {
> -		pr_err("nvm: unable to update all blocks atomically\n");
> -		return -EINVAL;
> -	}
> -
> -	memset(&rqd, 0, sizeof(struct nvm_rq));
> -
> -	nvm_set_rqd_ppalist(tgt_dev, &rqd, ppas, nr_ppas);
> -	nvm_rq_tgt_to_dev(tgt_dev, &rqd);
> -
> -	ret = dev->ops->set_bb_tbl(dev, &rqd.ppa_addr, rqd.nr_ppas, type);
> -	nvm_free_rqd_ppalist(tgt_dev, &rqd);
> -	if (ret) {
> -		pr_err("nvm: failed bb mark\n");
> -		return -EINVAL;
> -	}
> -
> -	return 0;
> -}
> -EXPORT_SYMBOL(nvm_set_tgt_bb_tbl);
> -
> static int nvm_set_flags(struct nvm_geo *geo, struct nvm_rq *rqd)
> {
> 	int flags = 0;
> @@ -830,27 +790,159 @@ void nvm_end_io(struct nvm_rq *rqd)
> }
> EXPORT_SYMBOL(nvm_end_io);
> 
> +static int nvm_submit_io_sync_raw(struct nvm_dev *dev, struct nvm_rq *rqd)
> +{
> +	if (!dev->ops->submit_io_sync)
> +		return -ENODEV;
> +
> +	rqd->flags = nvm_set_flags(&dev->geo, rqd);
> +
> +	return dev->ops->submit_io_sync(dev, rqd);
> +}
> +
> +static int nvm_bb_chunk_sense(struct nvm_dev *dev, struct ppa_addr ppa)
> +{
> +	struct nvm_rq rqd = { NULL };
> +	struct bio bio;
> +	struct bio_vec bio_vec;
> +	struct page *page;
> +	int ret;
> +
> +	page = alloc_page(GFP_KERNEL);
> +	if (!page)
> +		return -ENOMEM;
> +
> +	bio_init(&bio, &bio_vec, 1);
> +	bio_add_page(&bio, page, PAGE_SIZE, 0);
> +	bio_set_op_attrs(&bio, REQ_OP_READ, 0);
> +
> +	rqd.bio = &bio;
> +	rqd.opcode = NVM_OP_PREAD;
> +	rqd.is_seq = 1;
> +	rqd.nr_ppas = 1;
> +	rqd.ppa_addr = generic_to_dev_addr(dev, ppa);
> +
> +	ret = nvm_submit_io_sync_raw(dev, &rqd);
> +	if (ret)
> +		return ret;
> +
> +	__free_page(page);
> +
> +	return rqd.error;
> +}
> +
> /*
> - * folds a bad block list from its plane representation to its virtual
> - * block representation. The fold is done in place and reduced size is
> - * returned.
> + * Scans a 1.2 chunk first and last page to determine if its state.
> + * If the chunk is found to be open, also scan it to update the write
> + * pointer.
> + */
> +static int nvm_bb_scan_chunk(struct nvm_dev *dev, struct ppa_addr ppa,
> +			     struct nvm_chk_meta *meta)

Keeping some name consistency would help nvm_bb_chunk_*

> [...]

> +
> +static int nvm_get_bb_meta(struct nvm_dev *dev, sector_t slba,
> +			   int nchks, struct nvm_chk_meta *meta)
> +{
> +	struct nvm_geo *geo = &dev->geo;
> +	struct ppa_addr ppa;
> +	u8 *blks;
> +	int ch, lun, nr_blks;
> +	int ret;
> +
> +	ppa.ppa = slba;
> +	ppa = dev_to_generic_addr(dev, ppa);
> +
> +	if (ppa.g.blk != 0)
> +		return -EINVAL;
> +
> +	if ((nchks % geo->num_chk) != 0)
> +		return -EINVAL;
> +
> +	nr_blks = geo->num_chk * geo->pln_mode;
> +
> +	blks = kmalloc(nr_blks, GFP_KERNEL);
> +	if (!blks)
> +		return -ENOMEM;
> +
> +	for (ch = ppa.g.ch; ch < geo->num_ch; ch++) {
> +		for (lun = ppa.g.lun; lun < geo->num_lun; lun++) {
> +			struct ppa_addr ppa_gen, ppa_dev;
> +
> +			if (!nchks)
> +				goto out;

You should free blks here too.

> +
> +			ppa_gen.ppa = 0;
> +			ppa_gen.a.ch = ch;
> +			ppa_gen.a.lun = lun;
> +			ppa_dev = generic_to_dev_addr(dev, ppa_gen);
> +
> +			ret = dev->ops->get_bb_tbl(dev, ppa_dev, blks);
> +			if (ret)
> +				goto err;
> +
> +			ret = nvm_bb_to_chunk(dev, ppa_gen, blks, nr_blks,
> +									meta);
> +			if (ret)
> +				goto err;
> +
> +			meta += geo->num_chk;
> +			nchks -= geo->num_chk;
> +		}
> +	}
> +out:
> +	return 0;
> +err:
> +	kfree(blks);
> +	return ret;
> }
> -EXPORT_SYMBOL(nvm_bb_tbl_fold);
> 
> -int nvm_get_tgt_bb_tbl(struct nvm_tgt_dev *tgt_dev, struct ppa_addr ppa,
> -		       u8 *blks)
> [...]



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