lightnvm: refactor end_io functions for sync

To implement sync I/O support within the LightNVM core, the end_io
functions are refactored to take an end_io function pointer instead of
testing for initialized media manager, followed by calling its end_io
function.

Sync I/O can then be implemented using a callback that signal I/O
completion. This is similar to the logic found in blk_to_execute_io().
By implementing it this way, the underlying device I/Os submission logic
is abstracted away from core, targets, and media managers.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/null_blk.c

@@ -436,9 +436,8 @@ static void null_del_dev(struct nullb *nullb)
 static void null_lnvm_end_io(struct request *rq, int error)
 {
 	struct nvm_rq *rqd = rq->end_io_data;
-	struct nvm_dev *dev = rqd->dev;
 
-	dev->mt->end_io(rqd, error);
+	nvm_end_io(rqd, error);
 
 	blk_put_request(rq);
 }

drivers/lightnvm/core.c

@@ -27,6 +27,7 @@
 #include <linux/module.h>
 #include <linux/miscdevice.h>
 #include <linux/lightnvm.h>
+#include <linux/sched/sysctl.h>
 #include <uapi/linux/lightnvm.h>
 
 static LIST_HEAD(nvm_targets);
@@ -288,6 +289,21 @@ int nvm_erase_ppa(struct nvm_dev *dev, struct ppa_addr ppa)
 }
 EXPORT_SYMBOL(nvm_erase_ppa);
 
+void nvm_end_io(struct nvm_rq *rqd, int error)
+{
+	rqd->end_io(rqd, error);
+}
+EXPORT_SYMBOL(nvm_end_io);
+
+static void nvm_end_io_sync(struct nvm_rq *rqd, int errors)
+{
+	struct completion *waiting = rqd->wait;
+
+	rqd->wait = NULL;
+
+	complete(waiting);
+}
+
 static int nvm_core_init(struct nvm_dev *dev)
 {
 	struct nvm_id *id = &dev->identity;

drivers/lightnvm/gennvm.c

@@ -317,18 +317,6 @@ static void gennvm_put_blk(struct nvm_dev *dev, struct nvm_block *blk)
 	spin_unlock(&vlun->lock);
 }
 
-static int gennvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
-{
-	if (!dev->ops->submit_io)
-		return -ENODEV;
-
-	/* Convert address space */
-	nvm_generic_to_addr_mode(dev, rqd);
-
-	rqd->dev = dev;
-	return dev->ops->submit_io(dev, rqd);
-}
-
 static void gennvm_blk_set_type(struct nvm_dev *dev, struct ppa_addr *ppa,
 								int type)
 {
@@ -375,25 +363,32 @@ static void gennvm_mark_blk_bad(struct nvm_dev *dev, struct nvm_rq *rqd)
 		gennvm_blk_set_type(dev, &rqd->ppa_addr, 2);
 }
 
-static int gennvm_end_io(struct nvm_rq *rqd, int error)
+static void gennvm_end_io(struct nvm_rq *rqd, int error)
 {
 	struct nvm_tgt_instance *ins = rqd->ins;
-	int ret = 0;
 
 	switch (error) {
 	case NVM_RSP_SUCCESS:
-		break;
 	case NVM_RSP_ERR_EMPTYPAGE:
 		break;
 	case NVM_RSP_ERR_FAILWRITE:
 		gennvm_mark_blk_bad(rqd->dev, rqd);
-	default:
-		ret++;
 	}
 
-	ret += ins->tt->end_io(rqd, error);
+	ins->tt->end_io(rqd, error);
+}
 
-	return ret;
+static int gennvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
+{
+	if (!dev->ops->submit_io)
+		return -ENODEV;
+
+	/* Convert address space */
+	nvm_generic_to_addr_mode(dev, rqd);
+
+	rqd->dev = dev;
+	rqd->end_io = gennvm_end_io;
+	return dev->ops->submit_io(dev, rqd);
 }
 
 static int gennvm_erase_blk(struct nvm_dev *dev, struct nvm_block *blk,
@@ -442,7 +437,6 @@ static struct nvmm_type gennvm = {
 	.put_blk	= gennvm_put_blk,
 
 	.submit_io	= gennvm_submit_io,
-	.end_io		= gennvm_end_io,
 	.erase_blk	= gennvm_erase_blk,
 
 	.get_lun	= gennvm_get_lun,

drivers/lightnvm/rrpc.c

@@ -642,7 +642,7 @@ static void rrpc_end_io_write(struct rrpc *rrpc, struct rrpc_rq *rrqd,
 	}
 }
 
-static int rrpc_end_io(struct nvm_rq *rqd, int error)
+static void rrpc_end_io(struct nvm_rq *rqd, int error)
 {
 	struct rrpc *rrpc = container_of(rqd->ins, struct rrpc, instance);
 	struct rrpc_rq *rrqd = nvm_rq_to_pdu(rqd);
@@ -655,7 +655,7 @@ static int rrpc_end_io(struct nvm_rq *rqd, int error)
 	bio_put(rqd->bio);
 
 	if (rrqd->flags & NVM_IOTYPE_GC)
-		return 0;
+		return;
 
 	rrpc_unlock_rq(rrpc, rqd);
 
@@ -665,8 +665,6 @@ static int rrpc_end_io(struct nvm_rq *rqd, int error)
 		nvm_dev_dma_free(rrpc->dev, rqd->metadata, rqd->dma_metadata);
 
 	mempool_free(rqd, rrpc->rq_pool);
-
-	return 0;
 }
 
 static int rrpc_read_ppalist_rq(struct rrpc *rrpc, struct bio *bio,

drivers/nvme/host/lightnvm.c

@@ -453,11 +453,8 @@ static inline void nvme_nvm_rqtocmd(struct request *rq, struct nvm_rq *rqd,
 static void nvme_nvm_end_io(struct request *rq, int error)
 {
 	struct nvm_rq *rqd = rq->end_io_data;
-	struct nvm_dev *dev = rqd->dev;
 
-	if (dev->mt && dev->mt->end_io(rqd, error))
-		pr_err("nvme: err status: %x result: %lx\n",
-				rq->errors, (unsigned long)rq->special);
+	nvm_end_io(rqd, error);
 
 	kfree(rq->cmd);
 	blk_mq_free_request(rq);

include/linux/lightnvm.h

@@ -148,6 +148,9 @@ struct ppa_addr {
 	};
 };
 
+struct nvm_rq;
+typedef void (nvm_end_io_fn)(struct nvm_rq *, int);
+
 struct nvm_rq {
 	struct nvm_tgt_instance *ins;
 	struct nvm_dev *dev;
@@ -164,6 +167,9 @@ struct nvm_rq {
 	void *metadata;
 	dma_addr_t dma_metadata;
 
+	struct completion *wait;
+	nvm_end_io_fn *end_io;
+
 	uint8_t opcode;
 	uint16_t nr_pages;
 	uint16_t flags;
@@ -347,7 +353,6 @@ static inline struct ppa_addr block_to_ppa(struct nvm_dev *dev,
 
 typedef blk_qc_t (nvm_tgt_make_rq_fn)(struct request_queue *, struct bio *);
 typedef sector_t (nvm_tgt_capacity_fn)(void *);
-typedef int (nvm_tgt_end_io_fn)(struct nvm_rq *, int);
 typedef void *(nvm_tgt_init_fn)(struct nvm_dev *, struct gendisk *, int, int);
 typedef void (nvm_tgt_exit_fn)(void *);
 
@@ -358,7 +363,7 @@ struct nvm_tgt_type {
 	/* target entry points */
 	nvm_tgt_make_rq_fn *make_rq;
 	nvm_tgt_capacity_fn *capacity;
-	nvm_tgt_end_io_fn *end_io;
+	nvm_end_io_fn *end_io;
 
 	/* module-specific init/teardown */
 	nvm_tgt_init_fn *init;
@@ -383,7 +388,6 @@ typedef int (nvmm_open_blk_fn)(struct nvm_dev *, struct nvm_block *);
 typedef int (nvmm_close_blk_fn)(struct nvm_dev *, struct nvm_block *);
 typedef void (nvmm_flush_blk_fn)(struct nvm_dev *, struct nvm_block *);
 typedef int (nvmm_submit_io_fn)(struct nvm_dev *, struct nvm_rq *);
-typedef int (nvmm_end_io_fn)(struct nvm_rq *, int);
 typedef int (nvmm_erase_blk_fn)(struct nvm_dev *, struct nvm_block *,
 								unsigned long);
 typedef struct nvm_lun *(nvmm_get_lun_fn)(struct nvm_dev *, int);
@@ -404,7 +408,6 @@ struct nvmm_type {
 	nvmm_flush_blk_fn *flush_blk;
 
 	nvmm_submit_io_fn *submit_io;
-	nvmm_end_io_fn *end_io;
 	nvmm_erase_blk_fn *erase_blk;
 
 	/* Configuration management */
@@ -434,6 +437,7 @@ extern int nvm_set_rqd_ppalist(struct nvm_dev *, struct nvm_rq *,
 extern void nvm_free_rqd_ppalist(struct nvm_dev *, struct nvm_rq *);
 extern int nvm_erase_ppa(struct nvm_dev *, struct ppa_addr);
 extern int nvm_erase_blk(struct nvm_dev *, struct nvm_block *);
+extern void nvm_end_io(struct nvm_rq *, int);
 #else /* CONFIG_NVM */
 struct nvm_dev_ops;