scsi: bsg: Move the whole request execution into the SCSI/transport handlers

Remove the amount of indirect calls by making the handler responsible for
the entire execution of the request.

Link: https://lore.kernel.org/r/20210729064845.1044147-5-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

block/bsg-lib.c

@@ -25,32 +25,39 @@ struct bsg_set {
 	bsg_timeout_fn		*timeout_fn;
 };
 
-static int bsg_transport_check_proto(struct sg_io_v4 *hdr)
+static int bsg_transport_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
+		fmode_t mode, unsigned int timeout)
 {
+	struct bsg_job *job;
+	struct request *rq;
+	struct bio *bio;
+	int ret;
+
 	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
 	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
 		return -EINVAL;
 	if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;
-	return 0;
-}
 
-static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
+	rq = blk_get_request(q, hdr->dout_xfer_len ?
-		fmode_t mode)
+			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
-{
+	if (IS_ERR(rq))
-	struct bsg_job *job = blk_mq_rq_to_pdu(rq);
+		return PTR_ERR(rq);
-	int ret;
+	rq->timeout = timeout;
 
+	job = blk_mq_rq_to_pdu(rq);
 	job->request_len = hdr->request_len;
 	job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
-	if (IS_ERR(job->request))
+	if (IS_ERR(job->request)) {
-		return PTR_ERR(job->request);
+		ret = PTR_ERR(job->request);
+		goto out_put_request;
+	}
 
 	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
 		job->bidi_rq = blk_get_request(rq->q, REQ_OP_DRV_IN, 0);
 		if (IS_ERR(job->bidi_rq)) {
 			ret = PTR_ERR(job->bidi_rq);
-			goto out;
+			goto out_free_job_request;
 		}
 
 		ret = blk_rq_map_user(rq->q, job->bidi_rq, NULL,
@@ -65,20 +72,19 @@ static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
 		job->bidi_bio = NULL;
 	}
 
-	return 0;
+	if (hdr->dout_xfer_len) {
-
+		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->dout_xferp),
-out_free_bidi_rq:
+				hdr->dout_xfer_len, GFP_KERNEL);
-	if (job->bidi_rq)
+	} else if (hdr->din_xfer_len) {
-		blk_put_request(job->bidi_rq);
+		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->din_xferp),
-out:
+				hdr->din_xfer_len, GFP_KERNEL);
-	kfree(job->request);
-	return ret;
 	}
 
-static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
+	if (ret)
-{
+		goto out_unmap_bidi_rq;
-	struct bsg_job *job = blk_mq_rq_to_pdu(rq);
+
-	int ret = 0;
+	bio = rq->bio;
+	blk_execute_rq(NULL, rq, !(hdr->flags & BSG_FLAG_Q_AT_TAIL));
 
 	/*
 	 * The assignments below don't make much sense, but are kept for
@@ -121,28 +127,20 @@ static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
 		hdr->din_resid = 0;
 	}
 
+	blk_rq_unmap_user(bio);
+out_unmap_bidi_rq:
+	if (job->bidi_rq)
+		blk_rq_unmap_user(job->bidi_bio);
+out_free_bidi_rq:
+	if (job->bidi_rq)
+		blk_put_request(job->bidi_rq);
+out_free_job_request:
+	kfree(job->request);
+out_put_request:
+	blk_put_request(rq);
 	return ret;
 }
 
-static void bsg_transport_free_rq(struct request *rq)
-{
-	struct bsg_job *job = blk_mq_rq_to_pdu(rq);
-
-	if (job->bidi_rq) {
-		blk_rq_unmap_user(job->bidi_bio);
-		blk_put_request(job->bidi_rq);
-	}
-
-	kfree(job->request);
-}
-
-static const struct bsg_ops bsg_transport_ops = {
-	.check_proto		= bsg_transport_check_proto,
-	.fill_hdr		= bsg_transport_fill_hdr,
-	.complete_rq		= bsg_transport_complete_rq,
-	.free_rq		= bsg_transport_free_rq,
-};
-
 /**
  * bsg_teardown_job - routine to teardown a bsg job
  * @kref: kref inside bsg_job that is to be torn down
@@ -398,7 +396,7 @@ struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 	q->queuedata = dev;
 	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 
-	bset->bd = bsg_register_queue(q, dev, name, &bsg_transport_ops);
+	bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn);
 	if (IS_ERR(bset->bd)) {
 		ret = PTR_ERR(bset->bd);
 		goto out_cleanup_queue;

block/bsg.c

@@ -22,12 +22,12 @@
 
 struct bsg_device {
 	struct request_queue *queue;
-	const struct bsg_ops *ops;
 	struct device device;
 	struct cdev cdev;
 	int max_queue;
 	unsigned int timeout;
 	unsigned int reserved_size;
+	bsg_sg_io_fn *sg_io_fn;
 };
 
 static inline struct bsg_device *to_bsg_device(struct inode *inode)
@@ -42,63 +42,28 @@ static DEFINE_IDA(bsg_minor_ida);
 static struct class *bsg_class;
 static int bsg_major;
 
-#define uptr64(val) ((void __user *)(uintptr_t)(val))
+static unsigned int bsg_timeout(struct bsg_device *bd, struct sg_io_v4 *hdr)
+{
+	unsigned int timeout = BLK_DEFAULT_SG_TIMEOUT;
+
+	if (hdr->timeout)
+		timeout = msecs_to_jiffies(hdr->timeout);
+	else if (bd->timeout)
+		timeout = bd->timeout;
+
+	return max_t(unsigned int, timeout, BLK_MIN_SG_TIMEOUT);
+}
 
 static int bsg_sg_io(struct bsg_device *bd, fmode_t mode, void __user *uarg)
 {
-	struct request *rq;
-	struct bio *bio;
 	struct sg_io_v4 hdr;
 	int ret;
 
 	if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 		return -EFAULT;
-
 	if (hdr.guard != 'Q')
 		return -EINVAL;
-	ret = bd->ops->check_proto(&hdr);
+	ret = bd->sg_io_fn(bd->queue, &hdr, mode, bsg_timeout(bd, &hdr));
-	if (ret)
-		return ret;
-
-	rq = blk_get_request(bd->queue, hdr.dout_xfer_len ?
-			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
-	if (IS_ERR(rq))
-		return PTR_ERR(rq);
-
-	ret = bd->ops->fill_hdr(rq, &hdr, mode);
-	if (ret) {
-		blk_put_request(rq);
-		return ret;
-	}
-
-	rq->timeout = msecs_to_jiffies(hdr.timeout);
-	if (!rq->timeout)
-		rq->timeout = bd->timeout;
-	if (!rq->timeout)
-		rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
-	if (rq->timeout < BLK_MIN_SG_TIMEOUT)
-		rq->timeout = BLK_MIN_SG_TIMEOUT;
-
-	if (hdr.dout_xfer_len) {
-		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr.dout_xferp),
-				hdr.dout_xfer_len, GFP_KERNEL);
-	} else if (hdr.din_xfer_len) {
-		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr.din_xferp),
-				hdr.din_xfer_len, GFP_KERNEL);
-	}
-
-	if (ret)
-		goto out_free_rq;
-
-	bio = rq->bio;
-
-	blk_execute_rq(NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
-	ret = bd->ops->complete_rq(rq, &hdr);
-	blk_rq_unmap_user(bio);
-
-out_free_rq:
-	bd->ops->free_rq(rq);
-	blk_put_request(rq);
 	if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
 		return -EFAULT;
 	return ret;
@@ -211,8 +176,7 @@ void bsg_unregister_queue(struct bsg_device *bd)
 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 
 struct bsg_device *bsg_register_queue(struct request_queue *q,
-		struct device *parent, const char *name,
+		struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn)
-		const struct bsg_ops *ops)
 {
 	struct bsg_device *bd;
 	int ret;
@@ -223,7 +187,7 @@ struct bsg_device *bsg_register_queue(struct request_queue *q,
 	bd->max_queue = BSG_DEFAULT_CMDS;
 	bd->reserved_size = INT_MAX;
 	bd->queue = q;
-	bd->ops = ops;
+	bd->sg_io_fn = sg_io_fn;
 
 	ret = ida_simple_get(&bsg_minor_ida, 0, BSG_MAX_DEVS, GFP_KERNEL);
 	if (ret < 0) {

drivers/scsi/scsi_bsg.c

@@ -9,42 +9,57 @@
 
 #define uptr64(val) ((void __user *)(uintptr_t)(val))
 
-static int scsi_bsg_check_proto(struct sg_io_v4 *hdr)
+static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
+		fmode_t mode, unsigned int timeout)
 {
+	struct scsi_request *sreq;
+	struct request *rq;
+	struct bio *bio;
+	int ret;
+
 	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
 	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
 		return -EINVAL;
-	return 0;
-}
-
-static int scsi_bsg_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
-		fmode_t mode)
-{
-	struct scsi_request *sreq = scsi_req(rq);
-
 	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
 		pr_warn_once("BIDI support in bsg has been removed.\n");
 		return -EOPNOTSUPP;
 	}
 
+	rq = blk_get_request(q, hdr->dout_xfer_len ?
+			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
+	if (IS_ERR(rq))
+		return PTR_ERR(rq);
+	rq->timeout = timeout;
+
+	ret = -ENOMEM;
+	sreq = scsi_req(rq);
 	sreq->cmd_len = hdr->request_len;
 	if (sreq->cmd_len > BLK_MAX_CDB) {
 		sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
 		if (!sreq->cmd)
-			return -ENOMEM;
+			goto out_put_request;
 	}
 
+	ret = -EFAULT;
 	if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
-		return -EFAULT;
+		goto out_free_cmd;
+	ret = -EPERM;
 	if (!scsi_cmd_allowed(sreq->cmd, mode))
-		return -EPERM;
+		goto out_free_cmd;
-	return 0;
+
+	if (hdr->dout_xfer_len) {
+		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->dout_xferp),
+				hdr->dout_xfer_len, GFP_KERNEL);
+	} else if (hdr->din_xfer_len) {
+		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->din_xferp),
+				hdr->din_xfer_len, GFP_KERNEL);
 	}
 
-static int scsi_bsg_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
+	if (ret)
-{
+		goto out_free_cmd;
-	struct scsi_request *sreq = scsi_req(rq);
+
-	int ret = 0;
+	bio = rq->bio;
+	blk_execute_rq(NULL, rq, !(hdr->flags & BSG_FLAG_Q_AT_TAIL));
 
 	/*
 	 * fill in all the output members
@@ -74,23 +89,17 @@ static int scsi_bsg_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
 	else
 		hdr->dout_resid = sreq->resid_len;
 
+	blk_rq_unmap_user(bio);
+
+out_free_cmd:
+	scsi_req_free_cmd(scsi_req(rq));
+out_put_request:
+	blk_put_request(rq);
 	return ret;
 }
 
-static void scsi_bsg_free_rq(struct request *rq)
-{
-	scsi_req_free_cmd(scsi_req(rq));
-}
-
-static const struct bsg_ops scsi_bsg_ops = {
-	.check_proto		= scsi_bsg_check_proto,
-	.fill_hdr		= scsi_bsg_fill_hdr,
-	.complete_rq		= scsi_bsg_complete_rq,
-	.free_rq		= scsi_bsg_free_rq,
-};
-
 struct bsg_device *scsi_bsg_register_queue(struct scsi_device *sdev)
 {
 	return bsg_register_queue(sdev->request_queue, &sdev->sdev_gendev,
-				  dev_name(&sdev->sdev_gendev), &scsi_bsg_ops);
+			dev_name(&sdev->sdev_gendev), scsi_bsg_sg_io_fn);
 }

include/linux/bsg.h

@@ -6,20 +6,14 @@
 
 struct bsg_device;
 struct device;
-struct request;
 struct request_queue;
 
-struct bsg_ops {
+typedef int (bsg_sg_io_fn)(struct request_queue *, struct sg_io_v4 *hdr,
-	int	(*check_proto)(struct sg_io_v4 *hdr);
+		fmode_t mode, unsigned int timeout);
-	int	(*fill_hdr)(struct request *rq, struct sg_io_v4 *hdr,
-				fmode_t mode);
-	int	(*complete_rq)(struct request *rq, struct sg_io_v4 *hdr);
-	void	(*free_rq)(struct request *rq);
-};
 
 struct bsg_device *bsg_register_queue(struct request_queue *q,
 		struct device *parent, const char *name,
-		const struct bsg_ops *ops);
+		bsg_sg_io_fn *sg_io_fn);
 void bsg_unregister_queue(struct bsg_device *bcd);
 
 #endif /* _LINUX_BSG_H */