lightnvm: pblk: add iostat support

Since pblk registers its own block device, the iostat accounting is
not automatically done for us. Therefore, add the necessary
accounting logic to satisfy the iostat interface.

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

drivers/lightnvm/pblk-cache.c

@@ -19,12 +19,16 @@
 
 int pblk_write_to_cache(struct pblk *pblk, struct bio *bio, unsigned long flags)
 {
+	struct request_queue *q = pblk->dev->q;
 	struct pblk_w_ctx w_ctx;
 	sector_t lba = pblk_get_lba(bio);
+	unsigned long start_time = jiffies;
 	unsigned int bpos, pos;
 	int nr_entries = pblk_get_secs(bio);
 	int i, ret;
 
+	generic_start_io_acct(q, WRITE, bio_sectors(bio), &pblk->disk->part0);
+
 	/* Update the write buffer head (mem) with the entries that we can
 	 * write. The write in itself cannot fail, so there is no need to
 	 * rollback from here on.
@@ -67,6 +71,7 @@ retry:
 	pblk_rl_inserted(&pblk->rl, nr_entries);
 
 out:
+	generic_end_io_acct(q, WRITE, &pblk->disk->part0, start_time);
 	pblk_write_should_kick(pblk);
 	return ret;
 }

drivers/lightnvm/pblk-read.c

@@ -158,8 +158,12 @@ static void pblk_end_user_read(struct bio *bio)
 static void __pblk_end_io_read(struct pblk *pblk, struct nvm_rq *rqd,
 			       bool put_line)
 {
+	struct nvm_tgt_dev *dev = pblk->dev;
 	struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
 	struct bio *bio = rqd->bio;
+	unsigned long start_time = r_ctx->start_time;
+
+	generic_end_io_acct(dev->q, READ, &pblk->disk->part0, start_time);
 
 	if (rqd->error)
 		pblk_log_read_err(pblk, rqd);
@@ -193,9 +197,9 @@ static void pblk_end_io_read(struct nvm_rq *rqd)
 	__pblk_end_io_read(pblk, rqd, true);
 }
 
-static int pblk_fill_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
-				      unsigned int bio_init_idx,
-				      unsigned long *read_bitmap)
+static int pblk_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
+				 unsigned int bio_init_idx,
+				 unsigned long *read_bitmap)
 {
 	struct bio *new_bio, *bio = rqd->bio;
 	struct pblk_sec_meta *meta_list = rqd->meta_list;
@@ -306,6 +310,8 @@ static int pblk_fill_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
 	return NVM_IO_OK;
 
 err:
+	pr_err("pblk: failed to perform partial read\n");
+
 	/* Free allocated pages in new bio */
 	pblk_bio_free_pages(pblk, bio, 0, new_bio->bi_vcnt);
 	__pblk_end_io_read(pblk, rqd, false);
@@ -357,6 +363,7 @@ retry:
 int pblk_submit_read(struct pblk *pblk, struct bio *bio)
 {
 	struct nvm_tgt_dev *dev = pblk->dev;
+	struct request_queue *q = dev->q;
 	sector_t blba = pblk_get_lba(bio);
 	unsigned int nr_secs = pblk_get_secs(bio);
 	struct pblk_g_ctx *r_ctx;
@@ -372,6 +379,8 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
 		return NVM_IO_ERR;
 	}
 
+	generic_start_io_acct(q, READ, bio_sectors(bio), &pblk->disk->part0);
+
 	bitmap_zero(&read_bitmap, nr_secs);
 
 	rqd = pblk_alloc_rqd(pblk, PBLK_READ);
@@ -383,6 +392,7 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
 	rqd->end_io = pblk_end_io_read;
 
 	r_ctx = nvm_rq_to_pdu(rqd);
+	r_ctx->start_time = jiffies;
 	r_ctx->lba = blba;
 
 	/* Save the index for this bio's start. This is needed in case
@@ -422,7 +432,7 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
 		int_bio = bio_clone_fast(bio, GFP_KERNEL, pblk_bio_set);
 		if (!int_bio) {
 			pr_err("pblk: could not clone read bio\n");
-			return NVM_IO_ERR;
+			goto fail_end_io;
 		}
 
 		rqd->bio = int_bio;
@@ -433,7 +443,7 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
 			pr_err("pblk: read IO submission failed\n");
 			if (int_bio)
 				bio_put(int_bio);
-			return ret;
+			goto fail_end_io;
 		}
 
 		return NVM_IO_OK;
@@ -442,17 +452,14 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
 	/* The read bio request could be partially filled by the write buffer,
 	 * but there are some holes that need to be read from the drive.
 	 */
-	ret = pblk_fill_partial_read_bio(pblk, rqd, bio_init_idx, &read_bitmap);
-	if (ret) {
-		pr_err("pblk: failed to perform partial read\n");
-		return ret;
-	}
-
-	return NVM_IO_OK;
+	return pblk_partial_read_bio(pblk, rqd, bio_init_idx, &read_bitmap);
 
 fail_rqd_free:
 	pblk_free_rqd(pblk, rqd, PBLK_READ);
 	return ret;
+fail_end_io:
+	__pblk_end_io_read(pblk, rqd, false);
+	return ret;
 }
 
 static int read_ppalist_rq_gc(struct pblk *pblk, struct nvm_rq *rqd,

drivers/lightnvm/pblk.h

@@ -113,6 +113,7 @@ struct pblk_c_ctx {
 /* read context */
 struct pblk_g_ctx {
 	void *private;
+	unsigned long start_time;
 	u64 lba;
 };