[PATCH 3/6] ublk: split request validation from io_desc init

[Caleb Sander Mateos <csander@purestorage.com>]

In preparation for moving the struct ublksrv_io_desc initialization from
the thread submitting ublk requests to the daemon thread receiving them,
split the fallible part of ublk_setup_iod{,_zoned}() into new helper
ublk_validate_req{,_zoned}(). Only ublk_setup_iod{,_zoned}() accesses
the io_desc and cannot error out.

Return a bool value from ublk_validate_req{,_zoned}() as the existing
error code ublk_setup_iod{,_zoned}() returns is only checked against
BLK_STS_OK.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 drivers/block/ublk_drv.c | 70 +++++++++++++++++++++++++++-------------
 1 file changed, 48 insertions(+), 22 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index fada30d8d350..efbb0d6af128 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -698,12 +698,28 @@ static int ublk_report_zones(struct gendisk *disk, sector_t sector,
 out:
 	kvfree(buffer);
 	return ret;
 }
 
-static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
-					 struct request *req)
+static bool ublk_validate_req_zoned(const struct request *req)
+{
+	switch (req_op(req)) {
+	case REQ_OP_ZONE_OPEN:
+	case REQ_OP_ZONE_CLOSE:
+	case REQ_OP_ZONE_FINISH:
+	case REQ_OP_ZONE_RESET:
+	case REQ_OP_ZONE_APPEND:
+	case REQ_OP_ZONE_RESET_ALL:
+		return true;
+	case REQ_OP_DRV_IN:
+		return !!ublk_zoned_get_report_desc(req);
+	default:
+		return false;
+	}
+}
+
+static void ublk_setup_iod_zoned(struct ublk_queue *ubq, struct request *req)
 {
 	struct ublk_zoned_report_desc *desc;
 	u32 ublk_op;
 
 	switch (req_op(req)) {
@@ -725,24 +741,19 @@ static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
 	case REQ_OP_ZONE_RESET_ALL:
 		ublk_op = UBLK_IO_OP_ZONE_RESET_ALL;
 		break;
 	case REQ_OP_DRV_IN:
 		desc = ublk_zoned_get_report_desc(req);
-		if (!desc)
-			return BLK_STS_IOERR;
 		ublk_init_iod(ubq, req, UBLK_IO_OP_REPORT_ZONES, desc->nr_zones,
 			      desc->sector);
-		return BLK_STS_OK;
-	case REQ_OP_DRV_OUT:
-		/* We do not support drv_out */
-		return BLK_STS_NOTSUPP;
+		return;
 	default:
-		return BLK_STS_IOERR;
+		WARN_ON_ONCE(1);
+		return;
 	}
 
 	ublk_init_iod(ubq, req, ublk_op, blk_rq_sectors(req), blk_rq_pos(req));
-	return BLK_STS_OK;
 }
 
 #else
 
 #define ublk_report_zones (NULL)
@@ -759,14 +770,18 @@ static void ublk_dev_param_zoned_apply(struct ublk_device *ub)
 static int ublk_revalidate_disk_zones(struct ublk_device *ub)
 {
 	return 0;
 }
 
-static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
-					 struct request *req)
+static bool ublk_validate_req_zoned(const struct request *req)
 {
-	return BLK_STS_NOTSUPP;
+	return false;
+}
+
+static void ublk_setup_iod_zoned(struct ublk_queue *ubq, struct request *req)
+{
+	WARN_ON_ONCE(1);
 }
 
 #endif
 
 static inline void __ublk_complete_rq(struct request *req, struct ublk_io *io,
@@ -1489,11 +1504,26 @@ static unsigned int ublk_unmap_io(bool need_map,
 		return ublk_copy_user_pages(req, 0, &iter, dir);
 	}
 	return rq_bytes;
 }
 
-static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
+static bool ublk_validate_req(const struct ublk_queue *ubq,
+			      const struct request *req)
+{
+	switch (req_op(req)) {
+	case REQ_OP_READ:
+	case REQ_OP_WRITE:
+	case REQ_OP_FLUSH:
+	case REQ_OP_DISCARD:
+	case REQ_OP_WRITE_ZEROES:
+		return true;
+	default:
+		return ublk_queue_is_zoned(ubq) && ublk_validate_req_zoned(req);
+	}
+}
+
+static void ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 {
 	u32 ublk_op;
 
 	switch (req_op(req)) {
 	case REQ_OP_READ:
@@ -1510,17 +1540,15 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 		break;
 	case REQ_OP_WRITE_ZEROES:
 		ublk_op = UBLK_IO_OP_WRITE_ZEROES;
 		break;
 	default:
-		if (ublk_queue_is_zoned(ubq))
-			return ublk_setup_iod_zoned(ubq, req);
-		return BLK_STS_IOERR;
+		ublk_setup_iod_zoned(ubq, req);
+		return;
 	}
 
 	ublk_init_iod(ubq, req, ublk_op, blk_rq_sectors(req), blk_rq_pos(req));
-	return BLK_STS_OK;
 }
 
 static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu(
 		struct io_uring_cmd *ioucmd)
 {
@@ -2124,12 +2152,10 @@ static enum blk_eh_timer_return ublk_timeout(struct request *rq)
 }
 
 static blk_status_t ublk_prep_req(struct ublk_queue *ubq, struct request *rq,
 				  bool check_cancel)
 {
-	blk_status_t res;
-
 	if (unlikely(READ_ONCE(ubq->fail_io)))
 		return BLK_STS_TARGET;
 
 	/* With recovery feature enabled, force_abort is set in
 	 * ublk_stop_dev() before calling del_gendisk(). We have to
@@ -2146,14 +2172,14 @@ static blk_status_t ublk_prep_req(struct ublk_queue *ubq, struct request *rq,
 
 	if (check_cancel && unlikely(ubq->canceling))
 		return BLK_STS_IOERR;
 
 	/* fill iod to slot in io cmd buffer */
-	res = ublk_setup_iod(ubq, rq);
-	if (unlikely(res != BLK_STS_OK))
+	if (unlikely(!ublk_validate_req(ubq, rq)))
 		return BLK_STS_IOERR;
 
+	ublk_setup_iod(ubq, rq);
 	blk_mq_start_request(rq);
 	return BLK_STS_OK;
 }
 
 /*
-- 
2.54.0