Date:	Mon, 21 Mar 2016 11:25:47 +0100
From:	Matias Bjørling <mb@...htnvm.io>
To:	Wenwei Tao <ww.tao0320@...il.com>, jg@...htnvm.io
Cc:	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH v2] lightnvm: divide global reverse translation map into
 per lun

On 03/20/2016 06:51 AM, Wenwei Tao wrote:
> Divide the target's global reverse translation map into per lun,
> to prepare support for the non-continuous lun target creation.
>
> Signed-off-by: Wenwei Tao <ww.tao0320@...il.com>
> ---
>
> Changes since v1
> -fix merge/rebase mistake in rrpc_block_map_update().
> -remove variables poffset and lun_offset in rrpc structure
> since no one use them now.
>
>   drivers/lightnvm/rrpc.c  | 181 +++++++++++++++++++++++++++--------------------
>   drivers/lightnvm/rrpc.h  |   9 ++-
>   include/linux/lightnvm.h |   1 +
>   3 files changed, 111 insertions(+), 80 deletions(-)
>
> diff --git a/drivers/lightnvm/rrpc.c b/drivers/lightnvm/rrpc.c
> index 3ab6495..88e2ce5 100644
> --- a/drivers/lightnvm/rrpc.c
> +++ b/drivers/lightnvm/rrpc.c
> @@ -23,28 +23,35 @@ static int rrpc_submit_io(struct rrpc *rrpc, struct bio *bio,
>   				struct nvm_rq *rqd, unsigned long flags);
>
>   #define rrpc_for_each_lun(rrpc, rlun, i) \
> -		for ((i) = 0, rlun = &(rrpc)->luns[0]; \
> -			(i) < (rrpc)->nr_luns; (i)++, rlun = &(rrpc)->luns[(i)])
> +	for ((i) = 0, rlun = &(rrpc)->luns[0]; \
> +		(i) < (rrpc)->nr_luns; (i)++, rlun = &(rrpc)->luns[(i)])
> +
> +static inline u64 lun_poffset(struct nvm_lun *lun, struct nvm_dev *dev)
> +{
> +	return lun->id * dev->sec_per_lun;
> +}
>
>   static void rrpc_page_invalidate(struct rrpc *rrpc, struct rrpc_addr *a)
>   {
>   	struct rrpc_block *rblk = a->rblk;
> -	unsigned int pg_offset;
> +	struct rrpc_lun *rlun = rblk->rlun;
> +	u64 pg_offset;
>
> -	lockdep_assert_held(&rrpc->rev_lock);
> +	lockdep_assert_held(&rlun->rev_lock);
>
>   	if (a->addr == ADDR_EMPTY || !rblk)
>   		return;
>
>   	spin_lock(&rblk->lock);
>
> -	div_u64_rem(a->addr, rrpc->dev->sec_per_blk, &pg_offset);
> +	div_u64_rem(a->addr, rrpc->dev->sec_per_blk, (u32 *)&pg_offset);
>   	WARN_ON(test_and_set_bit(pg_offset, rblk->invalid_pages));
>   	rblk->nr_invalid_pages++;
>
>   	spin_unlock(&rblk->lock);
>
> -	rrpc->rev_trans_map[a->addr - rrpc->poffset].addr = ADDR_EMPTY;
> +	pg_offset = lun_poffset(rlun->parent, rrpc->dev);
> +	rlun->rev_trans_map[a->addr - pg_offset].addr = ADDR_EMPTY;
>   }
>
>   static void rrpc_invalidate_range(struct rrpc *rrpc, sector_t slba,
> @@ -52,14 +59,15 @@ static void rrpc_invalidate_range(struct rrpc *rrpc, sector_t slba,
>   {
>   	sector_t i;
>
> -	spin_lock(&rrpc->rev_lock);
>   	for (i = slba; i < slba + len; i++) {
>   		struct rrpc_addr *gp = &rrpc->trans_map[i];
> +		struct rrpc_lun *rlun = gp->rblk->rlun;
>
> +		spin_lock(&rlun->rev_lock);
>   		rrpc_page_invalidate(rrpc, gp);
> +		spin_unlock(&rlun->rev_lock);
>   		gp->rblk = NULL;
>   	}
> -	spin_unlock(&rrpc->rev_lock);
>   }
>
>   static struct nvm_rq *rrpc_inflight_laddr_acquire(struct rrpc *rrpc,
> @@ -116,15 +124,6 @@ static int block_is_full(struct rrpc *rrpc, struct rrpc_block *rblk)
>   	return (rblk->next_page == rrpc->dev->sec_per_blk);
>   }
>
> -/* Calculate relative addr for the given block, considering instantiated LUNs */
> -static u64 block_to_rel_addr(struct rrpc *rrpc, struct rrpc_block *rblk)
> -{
> -	struct nvm_block *blk = rblk->parent;
> -	int lun_blk = blk->id % (rrpc->dev->blks_per_lun * rrpc->nr_luns);
> -
> -	return lun_blk * rrpc->dev->sec_per_blk;
> -}
> -
>   /* Calculate global addr for the given block */
>   static u64 block_to_addr(struct rrpc *rrpc, struct rrpc_block *rblk)
>   {
> @@ -291,13 +290,14 @@ static void rrpc_end_sync_bio(struct bio *bio)
>   static int rrpc_move_valid_pages(struct rrpc *rrpc, struct rrpc_block *rblk)
>   {
>   	struct request_queue *q = rrpc->dev->q;
> +	struct rrpc_lun *rlun = rblk->rlun;
>   	struct rrpc_rev_addr *rev;
>   	struct nvm_rq *rqd;
>   	struct bio *bio;
>   	struct page *page;
>   	int slot;
>   	int nr_sec_per_blk = rrpc->dev->sec_per_blk;
> -	u64 phys_addr;
> +	u64 phys_addr, poffset;
>   	DECLARE_COMPLETION_ONSTACK(wait);
>
>   	if (bitmap_full(rblk->invalid_pages, nr_sec_per_blk))
> @@ -315,6 +315,7 @@ static int rrpc_move_valid_pages(struct rrpc *rrpc, struct rrpc_block *rblk)
>   		return -ENOMEM;
>   	}
>
> +	poffset = lun_poffset(rlun->parent, rrpc->dev);
>   	while ((slot = find_first_zero_bit(rblk->invalid_pages,
>   					    nr_sec_per_blk)) < nr_sec_per_blk) {
>
> @@ -322,23 +323,23 @@ static int rrpc_move_valid_pages(struct rrpc *rrpc, struct rrpc_block *rblk)
>   		phys_addr = rblk->parent->id * nr_sec_per_blk + slot;
>
>   try:
> -		spin_lock(&rrpc->rev_lock);
> +		spin_lock(&rlun->rev_lock);
>   		/* Get logical address from physical to logical table */
> -		rev = &rrpc->rev_trans_map[phys_addr - rrpc->poffset];
> +		rev = &rlun->rev_trans_map[phys_addr - poffset];
>   		/* already updated by previous regular write */
>   		if (rev->addr == ADDR_EMPTY) {
> -			spin_unlock(&rrpc->rev_lock);
> +			spin_unlock(&rlun->rev_lock);
>   			continue;
>   		}
>
>   		rqd = rrpc_inflight_laddr_acquire(rrpc, rev->addr, 1);
>   		if (IS_ERR_OR_NULL(rqd)) {
> -			spin_unlock(&rrpc->rev_lock);
> +			spin_unlock(&rlun->rev_lock);
>   			schedule();
>   			goto try;
>   		}
>
> -		spin_unlock(&rrpc->rev_lock);
> +		spin_unlock(&rlun->rev_lock);
>
>   		/* Perform read to do GC */
>   		bio->bi_iter.bi_sector = rrpc_get_sector(rev->addr);
> @@ -407,7 +408,7 @@ static void rrpc_block_gc(struct work_struct *work)
>   	struct rrpc_block *rblk = gcb->rblk;
>   	struct nvm_dev *dev = rrpc->dev;
>   	struct nvm_lun *lun = rblk->parent->lun;
> -	struct rrpc_lun *rlun = &rrpc->luns[lun->id - rrpc->lun_offset];
> +	struct rrpc_lun *rlun = lun->private;
>
>   	mempool_free(gcb, rrpc->gcb_pool);
>   	pr_debug("nvm: block '%lu' being reclaimed\n", rblk->parent->id);
> @@ -510,7 +511,7 @@ static void rrpc_gc_queue(struct work_struct *work)
>   	struct rrpc_block *rblk = gcb->rblk;
>   	struct nvm_lun *lun = rblk->parent->lun;
>   	struct nvm_block *blk = rblk->parent;
> -	struct rrpc_lun *rlun = &rrpc->luns[lun->id - rrpc->lun_offset];
> +	struct rrpc_lun *rlun = lun->private;
>
>   	spin_lock(&rlun->lock);
>   	list_add_tail(&rblk->prio, &rlun->prio_list);
> @@ -561,22 +562,25 @@ static struct rrpc_lun *rrpc_get_lun_rr(struct rrpc *rrpc, int is_gc)
>   static struct rrpc_addr *rrpc_update_map(struct rrpc *rrpc, sector_t laddr,
>   					struct rrpc_block *rblk, u64 paddr)
>   {
> +	struct rrpc_lun *rlun = rblk->rlun;
>   	struct rrpc_addr *gp;
>   	struct rrpc_rev_addr *rev;
> +	u64 poffset = lun_poffset(rlun->parent, rrpc->dev);
>
>   	BUG_ON(laddr >= rrpc->nr_sects);
>
>   	gp = &rrpc->trans_map[laddr];
> -	spin_lock(&rrpc->rev_lock);
> +	spin_lock(&rlun->rev_lock);
> +
>   	if (gp->rblk)
>   		rrpc_page_invalidate(rrpc, gp);
>
>   	gp->addr = paddr;
>   	gp->rblk = rblk;
>
> -	rev = &rrpc->rev_trans_map[gp->addr - rrpc->poffset];
> +	rev = &rlun->rev_trans_map[gp->addr - poffset];
>   	rev->addr = laddr;
> -	spin_unlock(&rrpc->rev_lock);
> +	spin_unlock(&rlun->rev_lock);
>
>   	return gp;
>   }
> @@ -990,7 +994,6 @@ static int rrpc_gc_init(struct rrpc *rrpc)
>
>   static void rrpc_map_free(struct rrpc *rrpc)
>   {
> -	vfree(rrpc->rev_trans_map);
>   	vfree(rrpc->trans_map);
>   }
>
> @@ -998,8 +1001,8 @@ static int rrpc_l2p_update(u64 slba, u32 nlb, __le64 *entries, void *private)
>   {
>   	struct rrpc *rrpc = (struct rrpc *)private;
>   	struct nvm_dev *dev = rrpc->dev;
> -	struct rrpc_addr *addr = rrpc->trans_map + slba;
> -	struct rrpc_rev_addr *raddr = rrpc->rev_trans_map;
> +	struct rrpc_addr *addr;
> +	struct rrpc_rev_addr *raddr;
>   	u64 elba = slba + nlb;
>   	u64 i;
>
> @@ -1008,9 +1011,15 @@ static int rrpc_l2p_update(u64 slba, u32 nlb, __le64 *entries, void *private)
>   		return -EINVAL;
>   	}
>
> +	slba -= rrpc->soffset >> (ilog2(dev->sec_size) - 9);
> +	addr = rrpc->trans_map + slba;
>   	for (i = 0; i < nlb; i++) {
> +		struct rrpc_lun *rlun;
> +		struct nvm_lun *lun;
>   		u64 pba = le64_to_cpu(entries[i]);
> -		unsigned int mod;
> +		u64 poffset;
> +		int lunid;
> +
>   		/* LNVM treats address-spaces as silos, LBA and PBA are
>   		 * equally large and zero-indexed.
>   		 */
> @@ -1026,10 +1035,18 @@ static int rrpc_l2p_update(u64 slba, u32 nlb, __le64 *entries, void *private)
>   		if (!pba)
>   			continue;
>
> -		div_u64_rem(pba, rrpc->nr_sects, &mod);
> +		lunid = div_u64(pba, dev->sec_per_lun);
> +		lun = dev->mt->get_lun(dev, lunid);
> +
> +		if (unlikely(!lun))
> +			return -EINVAL;
> +
> +		rlun = lun->private;
> +		raddr = rlun->rev_trans_map;
> +		poffset = lun_poffset(lun, dev);
>
>   		addr[i].addr = pba;
> -		raddr[mod].addr = slba + i;
> +		raddr[pba - poffset].addr = slba + i;
>   	}
>
>   	return 0;
> @@ -1048,17 +1065,10 @@ static int rrpc_map_init(struct rrpc *rrpc)
>   	if (!rrpc->trans_map)
>   		return -ENOMEM;
>
> -	rrpc->rev_trans_map = vmalloc(sizeof(struct rrpc_rev_addr)
> -							* rrpc->nr_sects);
> -	if (!rrpc->rev_trans_map)
> -		return -ENOMEM;
> -
>   	for (i = 0; i < rrpc->nr_sects; i++) {
>   		struct rrpc_addr *p = &rrpc->trans_map[i];
> -		struct rrpc_rev_addr *r = &rrpc->rev_trans_map[i];
>
>   		p->addr = ADDR_EMPTY;
> -		r->addr = ADDR_EMPTY;
>   	}
>
>   	if (!dev->ops->get_l2p_tbl)
> @@ -1143,25 +1153,69 @@ static void rrpc_luns_free(struct rrpc *rrpc)
>   		if (!lun)
>   			break;
>   		dev->mt->release_lun(dev, lun->id);
> +		vfree(rlun->rev_trans_map);
>   		vfree(rlun->blocks);
>   	}
>
>   	kfree(rrpc->luns);
> +	rrpc->luns = NULL;
> +}
> +
> +static int rrpc_lun_init(struct rrpc *rrpc, struct rrpc_lun *rlun,
> +			struct nvm_lun *lun)
> +{
> +	struct nvm_dev *dev = rrpc->dev;
> +	int i;
> +
> +	rlun->rev_trans_map = vmalloc(sizeof(struct rrpc_rev_addr) *
> +					dev->sec_per_lun);
> +	if (!rlun->rev_trans_map)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < dev->sec_per_lun; i++) {
> +		struct rrpc_rev_addr *r = &rlun->rev_trans_map[i];
> +
> +		r->addr = ADDR_EMPTY;
> +	}
> +	rlun->blocks = vzalloc(sizeof(struct rrpc_block) * dev->blks_per_lun);
> +	if (!rlun->blocks) {
> +		vfree(rlun->rev_trans_map);
> +		return -ENOMEM;
> +	}
> +
> +	for (i = 0; i < dev->blks_per_lun; i++) {
> +		struct rrpc_block *rblk = &rlun->blocks[i];
> +		struct nvm_block *blk = &lun->blocks[i];
> +
> +		rblk->parent = blk;
> +		rblk->rlun = rlun;
> +		INIT_LIST_HEAD(&rblk->prio);
> +		spin_lock_init(&rblk->lock);
> +	}
> +
> +	rlun->rrpc = rrpc;
> +	lun->private = rlun;
> +	INIT_LIST_HEAD(&rlun->prio_list);
> +	INIT_LIST_HEAD(&rlun->open_list);
> +	INIT_LIST_HEAD(&rlun->closed_list);
> +	INIT_WORK(&rlun->ws_gc, rrpc_lun_gc);
> +	spin_lock_init(&rlun->lock);
> +	spin_lock_init(&rlun->rev_lock);
> +
> +	return 0;
>   }
>
>   static int rrpc_luns_init(struct rrpc *rrpc, int lun_begin, int lun_end)
>   {
>   	struct nvm_dev *dev = rrpc->dev;
>   	struct rrpc_lun *rlun;
> -	int i, j, ret = -EINVAL;
> +	int i, ret = -EINVAL;
>
>   	if (dev->sec_per_blk > MAX_INVALID_PAGES_STORAGE * BITS_PER_LONG) {
>   		pr_err("rrpc: number of pages per block too high.");
>   		return -EINVAL;
>   	}
>
> -	spin_lock_init(&rrpc->rev_lock);
> -
>   	rrpc->luns = kcalloc(rrpc->nr_luns, sizeof(struct rrpc_lun),
>   								GFP_KERNEL);
>   	if (!rrpc->luns)
> @@ -1183,31 +1237,9 @@ static int rrpc_luns_init(struct rrpc *rrpc, int lun_begin, int lun_end)
>
>   		rlun = &rrpc->luns[i];
>   		rlun->parent = lun;
> -		rlun->blocks = vzalloc(sizeof(struct rrpc_block) *
> -						rrpc->dev->blks_per_lun);
> -		if (!rlun->blocks) {
> -			ret = -ENOMEM;
> +		ret = rrpc_lun_init(rrpc, rlun, lun);
> +		if (ret)
>   			goto err;
> -		}
> -
> -		for (j = 0; j < rrpc->dev->blks_per_lun; j++) {
> -			struct rrpc_block *rblk = &rlun->blocks[j];
> -			struct nvm_block *blk = &lun->blocks[j];
> -
> -			rblk->parent = blk;
> -			rblk->rlun = rlun;
> -			INIT_LIST_HEAD(&rblk->prio);
> -			spin_lock_init(&rblk->lock);
> -		}
> -
> -		rlun->rrpc = rrpc;
> -		INIT_LIST_HEAD(&rlun->prio_list);
> -		INIT_LIST_HEAD(&rlun->open_list);
> -		INIT_LIST_HEAD(&rlun->closed_list);
> -
> -		INIT_WORK(&rlun->ws_gc, rrpc_lun_gc);
> -		spin_lock_init(&rlun->lock);
> -
>   		rrpc->total_blocks += dev->blks_per_lun;
>   		rrpc->nr_sects += dev->sec_per_lun;
>
> @@ -1215,6 +1247,7 @@ static int rrpc_luns_init(struct rrpc *rrpc, int lun_begin, int lun_end)
>
>   	return 0;
>   err:
> +	rrpc_luns_free(rrpc);
>   	return ret;
>   }
>
> @@ -1288,15 +1321,16 @@ static sector_t rrpc_capacity(void *private)
>   static void rrpc_block_map_update(struct rrpc *rrpc, struct rrpc_block *rblk)
>   {
>   	struct nvm_dev *dev = rrpc->dev;
> +	struct rrpc_lun *rlun = rblk->rlun;
>   	int offset;
>   	struct rrpc_addr *laddr;
> -	u64 bpaddr, paddr, pladdr;
> +	u64 paddr, pladdr, poffset;
>
> -	bpaddr = block_to_rel_addr(rrpc, rblk);
> +	poffset = lun_poffset(rlun->parent, dev);
>   	for (offset = 0; offset < dev->sec_per_blk; offset++) {
> -		paddr = bpaddr + offset;
> +		paddr = block_to_addr(rrpc, rblk) + offset;
>
> -		pladdr = rrpc->rev_trans_map[paddr].addr;
> +		pladdr = rlun->rev_trans_map[paddr - poffset].addr;
>   		if (pladdr == ADDR_EMPTY)
>   			continue;
>
> @@ -1405,9 +1439,6 @@ static void *rrpc_init(struct nvm_dev *dev, struct gendisk *tdisk,
>   		goto err;
>   	}
>
> -	rrpc->poffset = dev->sec_per_lun * lun_begin;
> -	rrpc->lun_offset = lun_begin;
> -
>   	ret = rrpc_core_init(rrpc);
>   	if (ret) {
>   		pr_err("nvm: rrpc: could not initialize core\n");
> diff --git a/drivers/lightnvm/rrpc.h b/drivers/lightnvm/rrpc.h
> index 2653484..590f1b7 100644
> --- a/drivers/lightnvm/rrpc.h
> +++ b/drivers/lightnvm/rrpc.h
> @@ -87,6 +87,10 @@ struct rrpc_lun {
>
>   	struct work_struct ws_gc;
>
> +	/* store a reverse map for garbage collection */
> +	struct rrpc_rev_addr *rev_trans_map;
> +	spinlock_t rev_lock;
> +
>   	spinlock_t lock;
>   };
>
> @@ -98,8 +102,6 @@ struct rrpc {
>   	struct gendisk *disk;
>
>   	sector_t soffset; /* logical sector offset */
> -	u64 poffset; /* physical page offset */
> -	int lun_offset;
>
>   	int nr_luns;
>   	struct rrpc_lun *luns;
> @@ -124,9 +126,6 @@ struct rrpc {
>   	 * addresses are used when writing to the disk block device.
>   	 */
>   	struct rrpc_addr *trans_map;
> -	/* also store a reverse map for garbage collection */
> -	struct rrpc_rev_addr *rev_trans_map;
> -	spinlock_t rev_lock;
>
>   	struct rrpc_inflight inflights;
>
> diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h
> index cdcb2cc..419a3db 100644
> --- a/include/linux/lightnvm.h
> +++ b/include/linux/lightnvm.h
> @@ -276,6 +276,7 @@ struct nvm_lun {
>   	spinlock_t lock;
>
>   	struct nvm_block *blocks;
> +	void *private;
>   };
>
>   enum {
>

It seems like there is a race-condition when GC hits. It panics on 
page_invalidation. You can test with the following fio script:

[global]
bs=4k
ioengine=libaio
iodepth=1
size=1G
direct=1
rw=randwrite
time_based
runtime=300

[p1]
numjobs=1
filename=/dev/test2

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