lightnvm: pblk: generalize erase path

Erase I/Os are scheduled with the following goals in mind: (i) minimize
LUNs collisions with write I/Os, and (ii) even out the price of erasing
on every write, instead of putting all the burden on when garbage
collection runs. This works well on the current design, but is specific
to the default mapping algorithm.

This patch generalizes the erase path so that other mapping algorithms
can select an arbitrary line to be erased instead. It also gets rid of
the erase semaphore since it creates jittering for user writes.

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

1 files changed, 59 insertions, 50 deletions

diff --git a/drivers/lightnvm/pblk-write.c b/drivers/lightnvm/pblk-write.c
index 79b90d8dbcb3..c745a22057f8 100644
--- a/drivers/lightnvm/pblk-write.c
+++ b/drivers/lightnvm/pblk-write.c
@@ -219,11 +219,10 @@ static int pblk_alloc_w_rq(struct pblk *pblk, struct nvm_rq *rqd,
 }
 
 static int pblk_setup_w_rq(struct pblk *pblk, struct nvm_rq *rqd,
-			   struct pblk_c_ctx *c_ctx)
+			   struct pblk_c_ctx *c_ctx, struct ppa_addr *erase_ppa)
 {
 	struct pblk_line_meta *lm = &pblk->lm;
-	struct pblk_line *e_line = pblk_line_get_data_next(pblk);
-	struct ppa_addr erase_ppa;
+	struct pblk_line *e_line = pblk_line_get_erase(pblk);
 	unsigned int valid = c_ctx->nr_valid;
 	unsigned int padded = c_ctx->nr_padded;
 	unsigned int nr_secs = valid + padded;
@@ -231,40 +230,23 @@ static int pblk_setup_w_rq(struct pblk *pblk, struct nvm_rq *rqd,
 	int ret = 0;
 
 	lun_bitmap = kzalloc(lm->lun_bitmap_len, GFP_KERNEL);
-	if (!lun_bitmap) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!lun_bitmap)
+		return -ENOMEM;
 	c_ctx->lun_bitmap = lun_bitmap;
 
 	ret = pblk_alloc_w_rq(pblk, rqd, nr_secs);
 	if (ret) {
 		kfree(lun_bitmap);
-		goto out;
+		return ret;
 	}
 
-	ppa_set_empty(&erase_ppa);
-	if (likely(!e_line || !atomic_read(&e_line->left_eblks)))
+	if (likely(!atomic_read(&e_line->left_eblks) || !e_line))
 		pblk_map_rq(pblk, rqd, c_ctx->sentry, lun_bitmap, valid, 0);
 	else
 		pblk_map_erase_rq(pblk, rqd, c_ctx->sentry, lun_bitmap,
-							valid, &erase_ppa);
+							valid, erase_ppa);
 
-out:
-	if (unlikely(e_line && !ppa_empty(erase_ppa))) {
-		if (pblk_blk_erase_async(pblk, erase_ppa)) {
-			struct nvm_tgt_dev *dev = pblk->dev;
-			struct nvm_geo *geo = &dev->geo;
-			int bit;
-
-			atomic_inc(&e_line->left_eblks);
-			bit = erase_ppa.g.lun * geo->nr_chnls + erase_ppa.g.ch;
-			WARN_ON(!test_and_clear_bit(bit, e_line->erase_bitmap));
-			up(&pblk->erase_sem);
-		}
-	}
-
-	return ret;
+	return 0;
 }
 
 int pblk_setup_w_rec_rq(struct pblk *pblk, struct nvm_rq *rqd,
@@ -311,16 +293,60 @@ static int pblk_calc_secs_to_sync(struct pblk *pblk, unsigned int secs_avail,
 	return secs_to_sync;
 }
 
+static int pblk_submit_io_set(struct pblk *pblk, struct nvm_rq *rqd)
+{
+	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
+	struct ppa_addr erase_ppa;
+	int err;
+
+	ppa_set_empty(&erase_ppa);
+
+	/* Assign lbas to ppas and populate request structure */
+	err = pblk_setup_w_rq(pblk, rqd, c_ctx, &erase_ppa);
+	if (err) {
+		pr_err("pblk: could not setup write request: %d\n", err);
+		return NVM_IO_ERR;
+	}
+
+	/* Submit write for current data line */
+	err = pblk_submit_io(pblk, rqd);
+	if (err) {
+		pr_err("pblk: I/O submission failed: %d\n", err);
+		return NVM_IO_ERR;
+	}
+
+	/* Submit available erase for next data line */
+	if (unlikely(!ppa_empty(erase_ppa)) &&
+				pblk_blk_erase_async(pblk, erase_ppa)) {
+		struct pblk_line *e_line = pblk_line_get_erase(pblk);
+		struct nvm_tgt_dev *dev = pblk->dev;
+		struct nvm_geo *geo = &dev->geo;
+		int bit;
+
+		atomic_inc(&e_line->left_eblks);
+		bit = erase_ppa.g.lun * geo->nr_chnls + erase_ppa.g.ch;
+		WARN_ON(!test_and_clear_bit(bit, e_line->erase_bitmap));
+	}
+
+	return NVM_IO_OK;
+}
+
+static void pblk_free_write_rqd(struct pblk *pblk, struct nvm_rq *rqd)
+{
+	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
+	struct bio *bio = rqd->bio;
+
+	if (c_ctx->nr_padded)
+		pblk_bio_free_pages(pblk, bio, rqd->nr_ppas, c_ctx->nr_padded);
+}
+
 static int pblk_submit_write(struct pblk *pblk)
 {
 	struct bio *bio;
 	struct nvm_rq *rqd;
-	struct pblk_c_ctx *c_ctx;
-	unsigned int pgs_read;
 	unsigned int secs_avail, secs_to_sync, secs_to_com;
 	unsigned int secs_to_flush;
 	unsigned long pos;
-	int err;
 
 	/* If there are no sectors in the cache, flushes (bios without data)
 	 * will be cleared on the cache threads
@@ -338,7 +364,6 @@ static int pblk_submit_write(struct pblk *pblk)
 		pr_err("pblk: cannot allocate write req.\n");
 		return 1;
 	}
-	c_ctx = nvm_rq_to_pdu(rqd);
 
 	bio = bio_alloc(GFP_KERNEL, pblk->max_write_pgs);
 	if (!bio) {
@@ -358,29 +383,14 @@ static int pblk_submit_write(struct pblk *pblk)
 	secs_to_com = (secs_to_sync > secs_avail) ? secs_avail : secs_to_sync;
 	pos = pblk_rb_read_commit(&pblk->rwb, secs_to_com);
 
-	pgs_read = pblk_rb_read_to_bio(&pblk->rwb, bio, c_ctx, pos,
-						secs_to_sync, secs_avail);
-	if (!pgs_read) {
+	if (pblk_rb_read_to_bio(&pblk->rwb, rqd, bio, pos, secs_to_sync,
+								secs_avail)) {
 		pr_err("pblk: corrupted write bio\n");
 		goto fail_put_bio;
 	}
 
-	if (c_ctx->nr_padded)
-		if (pblk_bio_add_pages(pblk, bio, GFP_KERNEL, c_ctx->nr_padded))
-			goto fail_put_bio;
-
-	/* Assign lbas to ppas and populate request structure */
-	err = pblk_setup_w_rq(pblk, rqd, c_ctx);
-	if (err) {
-		pr_err("pblk: could not setup write request\n");
+	if (pblk_submit_io_set(pblk, rqd))
 		goto fail_free_bio;
-	}
-
-	err = pblk_submit_io(pblk, rqd);
-	if (err) {
-		pr_err("pblk: I/O submission failed: %d\n", err);
-		goto fail_free_bio;
-	}
 
 #ifdef CONFIG_NVM_DEBUG
 	atomic_long_add(secs_to_sync, &pblk->sub_writes);
@@ -389,8 +399,7 @@ static int pblk_submit_write(struct pblk *pblk)
 	return 0;
 
 fail_free_bio:
-	if (c_ctx->nr_padded)
-		pblk_bio_free_pages(pblk, bio, secs_to_sync, c_ctx->nr_padded);
+	pblk_free_write_rqd(pblk, rqd);
 fail_put_bio:
 	bio_put(bio);
 fail_free_rqd: