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, 19 insertions, 14 deletions

diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c
index 045384ddc1f9..d293af12aa7a 100644
--- a/drivers/lightnvm/pblk-rb.c
+++ b/drivers/lightnvm/pblk-rb.c
@@ -521,20 +521,19 @@ out:
  * This function is used by the write thread to form the write bio that will
  * persist data on the write buffer to the media.
  */
-unsigned int pblk_rb_read_to_bio(struct pblk_rb *rb, struct bio *bio,
-				 struct pblk_c_ctx *c_ctx,
-				 unsigned int pos,
-				 unsigned int nr_entries,
-				 unsigned int count)
+unsigned int pblk_rb_read_to_bio(struct pblk_rb *rb, struct nvm_rq *rqd,
+				 struct bio *bio, unsigned int pos,
+				 unsigned int nr_entries, unsigned int count)
 {
 	struct pblk *pblk = container_of(rb, struct pblk, rwb);
+	struct request_queue *q = pblk->dev->q;
+	struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
 	struct pblk_rb_entry *entry;
 	struct page *page;
-	unsigned int pad = 0, read = 0, to_read = nr_entries;
+	unsigned int pad = 0, to_read = nr_entries;
 	unsigned int user_io = 0, gc_io = 0;
 	unsigned int i;
 	int flags;
-	int ret;
 
 	if (count < nr_entries) {
 		pad = nr_entries - count;
@@ -570,17 +569,17 @@ try:
 			flags |= PBLK_SUBMITTED_ENTRY;
 			/* Release flags on context. Protect from writes */
 			smp_store_release(&entry->w_ctx.flags, flags);
-			goto out;
+			return NVM_IO_ERR;
 		}
 
-		ret = bio_add_page(bio, page, rb->seg_size, 0);
-		if (ret != rb->seg_size) {
+		if (bio_add_pc_page(q, bio, page, rb->seg_size, 0) !=
+								rb->seg_size) {
 			pr_err("pblk: could not add page to write bio\n");
 			flags &= ~PBLK_WRITTEN_DATA;
 			flags |= PBLK_SUBMITTED_ENTRY;
 			/* Release flags on context. Protect from writes */
 			smp_store_release(&entry->w_ctx.flags, flags);
-			goto out;
+			return NVM_IO_ERR;
 		}
 
 		if (flags & PBLK_FLUSH_ENTRY) {
@@ -607,14 +606,20 @@ try:
 		pos = (pos + 1) & (rb->nr_entries - 1);
 	}
 
-	read = to_read;
+	if (pad) {
+		if (pblk_bio_add_pages(pblk, bio, GFP_KERNEL, pad)) {
+			pr_err("pblk: could not pad page in write bio\n");
+			return NVM_IO_ERR;
+		}
+	}
+
 	pblk_rl_out(&pblk->rl, user_io, gc_io);
 #ifdef CONFIG_NVM_DEBUG
 	atomic_long_add(pad, &((struct pblk *)
 			(container_of(rb, struct pblk, rwb)))->padded_writes);
 #endif
-out:
-	return read;
+
+	return NVM_IO_OK;
 }
 
 /*