lightnvm: pblk: simplify data validity check on GC

When a line is selected for recycling by the garbage collector (GC), the
line state changes and the invalid bitmap is frozen, preventing
invalidations from happening. Throughout the GC, the L2P map is checked
to verify that not data being recycled has been updated. The last check
is done before the new map is being stored on the L2P table. Though
this algorithm works, it requires a number of corner cases to be checked
each time the L2P table is being updated. This complicates readability
and is error prone in case that the recycling algorithm is modified.

Instead, this patch makes the invalid bitmap accessible even when the
line is being recycled. When recycled data is being remapped, it is
enough to check the invalid bitmap for the line before updating the L2P
table.

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 43 insertions, 36 deletions

diff --git a/drivers/lightnvm/pblk-read.c b/drivers/lightnvm/pblk-read.c
index eaaf9d55ba97..c28d6509312e 100644
--- a/drivers/lightnvm/pblk-read.c
+++ b/drivers/lightnvm/pblk-read.c
@@ -388,34 +388,40 @@ fail_rqd_free:
 
 static int read_ppalist_rq_gc(struct pblk *pblk, struct nvm_rq *rqd,
 			      struct pblk_line *line, u64 *lba_list,
-			      unsigned int nr_secs)
+			      u64 *paddr_list_gc, unsigned int nr_secs)
 {
-	struct ppa_addr ppas[PBLK_MAX_REQ_ADDRS];
+	struct ppa_addr ppa_list_l2p[PBLK_MAX_REQ_ADDRS];
+	struct ppa_addr ppa_gc;
 	int valid_secs = 0;
 	int i;
 
-	pblk_lookup_l2p_rand(pblk, ppas, lba_list, nr_secs);
+	pblk_lookup_l2p_rand(pblk, ppa_list_l2p, lba_list, nr_secs);
 
 	for (i = 0; i < nr_secs; i++) {
-		if (pblk_addr_in_cache(ppas[i]) || ppas[i].g.blk != line->id ||
-						pblk_ppa_empty(ppas[i])) {
-			lba_list[i] = ADDR_EMPTY;
+		if (lba_list[i] == ADDR_EMPTY)
+			continue;
+
+		ppa_gc = addr_to_gen_ppa(pblk, paddr_list_gc[i], line->id);
+		if (!pblk_ppa_comp(ppa_list_l2p[i], ppa_gc)) {
+			paddr_list_gc[i] = lba_list[i] = ADDR_EMPTY;
 			continue;
 		}
 
-		rqd->ppa_list[valid_secs++] = ppas[i];
+		rqd->ppa_list[valid_secs++] = ppa_list_l2p[i];
 	}
 
 #ifdef CONFIG_NVM_DEBUG
 	atomic_long_add(valid_secs, &pblk->inflight_reads);
 #endif
+
 	return valid_secs;
 }
 
 static int read_rq_gc(struct pblk *pblk, struct nvm_rq *rqd,
-		      struct pblk_line *line, sector_t lba)
+		      struct pblk_line *line, sector_t lba,
+		      u64 paddr_gc)
 {
-	struct ppa_addr ppa;
+	struct ppa_addr ppa_l2p, ppa_gc;
 	int valid_secs = 0;
 
 	if (lba == ADDR_EMPTY)
@@ -428,15 +434,14 @@ static int read_rq_gc(struct pblk *pblk, struct nvm_rq *rqd,
 	}
 
 	spin_lock(&pblk->trans_lock);
-	ppa = pblk_trans_map_get(pblk, lba);
+	ppa_l2p = pblk_trans_map_get(pblk, lba);
 	spin_unlock(&pblk->trans_lock);
 
-	/* Ignore updated values until the moment */
-	if (pblk_addr_in_cache(ppa) || ppa.g.blk != line->id ||
-							pblk_ppa_empty(ppa))
+	ppa_gc = addr_to_gen_ppa(pblk, paddr_gc, line->id);
+	if (!pblk_ppa_comp(ppa_l2p, ppa_gc))
 		goto out;
 
-	rqd->ppa_addr = ppa;
+	rqd->ppa_addr = ppa_l2p;
 	valid_secs = 1;
 
 #ifdef CONFIG_NVM_DEBUG
@@ -447,15 +452,14 @@ out:
 	return valid_secs;
 }
 
-int pblk_submit_read_gc(struct pblk *pblk, u64 *lba_list, void *data,
-			unsigned int nr_secs, unsigned int *secs_to_gc,
-			struct pblk_line *line)
+int pblk_submit_read_gc(struct pblk *pblk, struct pblk_gc_rq *gc_rq)
 {
 	struct nvm_tgt_dev *dev = pblk->dev;
 	struct nvm_geo *geo = &dev->geo;
 	struct bio *bio;
 	struct nvm_rq rqd;
-	int ret, data_len;
+	int data_len;
+	int ret = NVM_IO_OK;
 	DECLARE_COMPLETION_ONSTACK(wait);
 
 	memset(&rqd, 0, sizeof(struct nvm_rq));
@@ -463,25 +467,29 @@ int pblk_submit_read_gc(struct pblk *pblk, u64 *lba_list, void *data,
 	rqd.meta_list = nvm_dev_dma_alloc(dev->parent, GFP_KERNEL,
 							&rqd.dma_meta_list);
 	if (!rqd.meta_list)
-		return NVM_IO_ERR;
+		return -ENOMEM;
 
-	if (nr_secs > 1) {
+	if (gc_rq->nr_secs > 1) {
 		rqd.ppa_list = rqd.meta_list + pblk_dma_meta_size;
 		rqd.dma_ppa_list = rqd.dma_meta_list + pblk_dma_meta_size;
 
-		*secs_to_gc = read_ppalist_rq_gc(pblk, &rqd, line, lba_list,
-								nr_secs);
-		if (*secs_to_gc == 1)
+		gc_rq->secs_to_gc = read_ppalist_rq_gc(pblk, &rqd, gc_rq->line,
+							gc_rq->lba_list,
+							gc_rq->paddr_list,
+							gc_rq->nr_secs);
+		if (gc_rq->secs_to_gc == 1)
 			rqd.ppa_addr = rqd.ppa_list[0];
 	} else {
-		*secs_to_gc = read_rq_gc(pblk, &rqd, line, lba_list[0]);
+		gc_rq->secs_to_gc = read_rq_gc(pblk, &rqd, gc_rq->line,
+							gc_rq->lba_list[0],
+							gc_rq->paddr_list[0]);
 	}
 
-	if (!(*secs_to_gc))
+	if (!(gc_rq->secs_to_gc))
 		goto out;
 
-	data_len = (*secs_to_gc) * geo->sec_size;
-	bio = pblk_bio_map_addr(pblk, data, *secs_to_gc, data_len,
+	data_len = (gc_rq->secs_to_gc) * geo->sec_size;
+	bio = pblk_bio_map_addr(pblk, gc_rq->data, gc_rq->secs_to_gc, data_len,
 						PBLK_VMALLOC_META, GFP_KERNEL);
 	if (IS_ERR(bio)) {
 		pr_err("pblk: could not allocate GC bio (%lu)\n", PTR_ERR(bio));
@@ -494,13 +502,12 @@ int pblk_submit_read_gc(struct pblk *pblk, u64 *lba_list, void *data,
 	rqd.opcode = NVM_OP_PREAD;
 	rqd.end_io = pblk_end_io_sync;
 	rqd.private = &wait;
-	rqd.nr_ppas = *secs_to_gc;
+	rqd.nr_ppas = gc_rq->secs_to_gc;
 	rqd.flags = pblk_set_read_mode(pblk, PBLK_READ_RANDOM);
 	rqd.bio = bio;
 
-	ret = pblk_submit_read_io(pblk, &rqd);
-	if (ret) {
-		bio_endio(bio);
+	if (pblk_submit_read_io(pblk, &rqd)) {
+		ret = -EIO;
 		pr_err("pblk: GC read request failed\n");
 		goto err_free_bio;
 	}
@@ -519,19 +526,19 @@ int pblk_submit_read_gc(struct pblk *pblk, u64 *lba_list, void *data,
 	}
 
 #ifdef CONFIG_NVM_DEBUG
-	atomic_long_add(*secs_to_gc, &pblk->sync_reads);
-	atomic_long_add(*secs_to_gc, &pblk->recov_gc_reads);
-	atomic_long_sub(*secs_to_gc, &pblk->inflight_reads);
+	atomic_long_add(gc_rq->secs_to_gc, &pblk->sync_reads);
+	atomic_long_add(gc_rq->secs_to_gc, &pblk->recov_gc_reads);
+	atomic_long_sub(gc_rq->secs_to_gc, &pblk->inflight_reads);
 #endif
 
 	bio_put(bio);
 out:
 	nvm_dev_dma_free(dev->parent, rqd.meta_list, rqd.dma_meta_list);
-	return NVM_IO_OK;
+	return ret;
 
 err_free_bio:
 	bio_put(bio);
 err_free_dma:
 	nvm_dev_dma_free(dev->parent, rqd.meta_list, rqd.dma_meta_list);
-	return NVM_IO_ERR;
+	return ret;
 }