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, 13 insertions, 16 deletions

diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
index b6d7c6660149..6dd4866e579c 100644
--- a/drivers/lightnvm/pblk-core.c
+++ b/drivers/lightnvm/pblk-core.c
@@ -78,11 +78,7 @@ void __pblk_map_invalidate(struct pblk *pblk, struct pblk_line *line,
 	 * that newer updates are not overwritten.
 	 */
 	spin_lock(&line->lock);
-	if (line->state == PBLK_LINESTATE_GC ||
-					line->state == PBLK_LINESTATE_FREE) {
-		spin_unlock(&line->lock);
-		return;
-	}
+	WARN_ON(line->state == PBLK_LINESTATE_FREE);
 
 	if (test_and_set_bit(paddr, line->invalid_bitmap)) {
 		WARN_ONCE(1, "pblk: double invalidate\n");
@@ -99,8 +95,7 @@ void __pblk_map_invalidate(struct pblk *pblk, struct pblk_line *line,
 		spin_lock(&l_mg->gc_lock);
 		spin_lock(&line->lock);
 		/* Prevent moving a line that has just been chosen for GC */
-		if (line->state == PBLK_LINESTATE_GC ||
-					line->state == PBLK_LINESTATE_FREE) {
+		if (line->state == PBLK_LINESTATE_GC) {
 			spin_unlock(&line->lock);
 			spin_unlock(&l_mg->gc_lock);
 			return;
@@ -1766,6 +1761,7 @@ void pblk_update_map(struct pblk *pblk, sector_t lba, struct ppa_addr ppa)
 
 void pblk_update_map_cache(struct pblk *pblk, sector_t lba, struct ppa_addr ppa)
 {
+
 #ifdef CONFIG_NVM_DEBUG
 	/* Callers must ensure that the ppa points to a cache address */
 	BUG_ON(!pblk_addr_in_cache(ppa));
@@ -1776,9 +1772,9 @@ void pblk_update_map_cache(struct pblk *pblk, sector_t lba, struct ppa_addr ppa)
 }
 
 int pblk_update_map_gc(struct pblk *pblk, sector_t lba, struct ppa_addr ppa_new,
-		       struct pblk_line *gc_line)
+		       struct pblk_line *gc_line, u64 paddr_gc)
 {
-	struct ppa_addr ppa_l2p;
+	struct ppa_addr ppa_l2p, ppa_gc;
 	int ret = 1;
 
 #ifdef CONFIG_NVM_DEBUG
@@ -1795,10 +1791,13 @@ int pblk_update_map_gc(struct pblk *pblk, sector_t lba, struct ppa_addr ppa_new,
 
 	spin_lock(&pblk->trans_lock);
 	ppa_l2p = pblk_trans_map_get(pblk, lba);
+	ppa_gc = addr_to_gen_ppa(pblk, paddr_gc, gc_line->id);
 
-	/* Prevent updated entries to be overwritten by GC */
-	if (pblk_addr_in_cache(ppa_l2p) || pblk_ppa_empty(ppa_l2p) ||
-				pblk_tgt_ppa_to_line(ppa_l2p) != gc_line->id) {
+	if (!pblk_ppa_comp(ppa_l2p, ppa_gc)) {
+		spin_lock(&gc_line->lock);
+		WARN(!test_bit(paddr_gc, gc_line->invalid_bitmap),
+						"pblk: corrupted GC update");
+		spin_unlock(&gc_line->lock);
 
 		ret = 0;
 		goto out;
@@ -1870,15 +1869,13 @@ void pblk_lookup_l2p_seq(struct pblk *pblk, struct ppa_addr *ppas,
 void pblk_lookup_l2p_rand(struct pblk *pblk, struct ppa_addr *ppas,
 			  u64 *lba_list, int nr_secs)
 {
-	sector_t lba;
+	u64 lba;
 	int i;
 
 	spin_lock(&pblk->trans_lock);
 	for (i = 0; i < nr_secs; i++) {
 		lba = lba_list[i];
-		if (lba == ADDR_EMPTY) {
-			ppas[i].ppa = ADDR_EMPTY;
-		} else {
+		if (lba != ADDR_EMPTY) {
 			/* logic error: lba out-of-bounds. Ignore update */
 			if (!(lba < pblk->rl.nr_secs)) {
 				WARN(1, "pblk: corrupted L2P map request\n");