[PATCH v5 0/3] bsg: add io_uring command support for SCSI passthrough

[PATCH v5 0/3] bsg: add io_uring command support for SCSI passthrough

[Yang Xiuwei]

This series adds io_uring command support to the BSG SCSI passthrough
path.

The goal is to allow userspace to submit SCSI passthrough commands via
IORING_OP_URING_CMD, in addition to the existing sg_io interface.
The io_uring path mirrors the existing BSG behaviour: it currently only
supports BSG_PROTOCOL_SCSI + BSG_SUB_PROTOCOL_SCSI_CMD and does not
support BIDI transfers.

Patch 1 defines struct bsg_uring_cmd in the UAPI so that userspace can
describe SCSI passthrough requests for io_uring.

Patch 2 extends the generic BSG layer with an .uring_cmd file operation
and a bsg_uring_cmd_fn callback, allowing transport-specific handlers to
be registered.

Patch 3 implements the SCSI BSG io_uring handler. It builds a SCSI
request from struct bsg_uring_cmd, maps user buffers (including fixed
buffers), and completes asynchronously via a request end_io callback and
task_work. Completion returns SCSI device/host/driver status, residual
length and sense data length packed into the CQE result.

Compared to the earlier RFC v4 series [1], this version only includes
minor code cleanups (mainly comments and wording), without changing the
behaviour or logic of the implementation.

[1] https://lore.kernel.org/linux-block/20260122015653.703188-1-yangxiuwei@kylinos.cn/

Testing
-------
Testing was done inside a VM on a disk with:
  /sys/block/sdd/mq/0/nr_tags     = 1024
  /sys/block/sdd/queue/nr_requests = 256

The following SCSI INQUIRY micro-benchmark was run with N=100000:

  sg+SG_IO (v3), /dev/sg4:
    avg = 139.0 us, p50 = 128.9 us, p90 = 149.7 us, p99 = 301.0 us

  bsg+SG_IO (v4), /dev/bsg/2:0:0:0:
    avg = 97.2 us,  p50 = 92.7 us,  p90 = 111.5 us, p99 = 150.9 us

  bsg+io_uring, /dev/bsg/2:0:0:0:
    avg = 105.9 us, p50 = 95.4 us,  p90 = 116.2 us, p99 = 175.0 us

  bsg+io_uring (batch=64), /dev/bsg/2:0:0:0:
    avg = 61.9 us,  p50 = 60.9 us,  p90 = 63.9 us,  p99 = 94.6 us

These results show that the new io_uring path is comparable to the
existing BSG SG_IO interface for single-command workloads, and that
batched io_uring submission can significantly improve latency for
high-concurrency workloads when the device supports sufficient queue
depth.

Yang Xiuwei (3):
  bsg: add bsg_uring_cmd uapi structure
  bsg: add io_uring command support to generic layer
  scsi: bsg: add io_uring passthrough handler

 block/bsg-lib.c          |   2 +-
 block/bsg.c              |  32 +++++-
 drivers/scsi/scsi_bsg.c  | 206 ++++++++++++++++++++++++++++++++++++++-
 include/linux/bsg.h      |   6 +-
 include/uapi/linux/bsg.h |  21 ++++
 5 files changed, 263 insertions(+), 4 deletions(-)

-- 
2.25.1

[PATCH v5 1/3] bsg: add bsg_uring_cmd uapi structure

[Yang Xiuwei]

Add the bsg_uring_cmd structure to the BSG UAPI header to support
io_uring-based SCSI passthrough operations via IORING_OP_URING_CMD.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
---
 include/uapi/linux/bsg.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/uapi/linux/bsg.h b/include/uapi/linux/bsg.h
index cd6302def5ed..983c6e2b6871 100644
--- a/include/uapi/linux/bsg.h
+++ b/include/uapi/linux/bsg.h
@@ -63,5 +63,26 @@ struct sg_io_v4 {
 	__u32 padding;
 };
 
+struct bsg_uring_cmd {
+	__u64 request;		/* [i], [*i] command descriptor address */
+	__u32 request_len;	/* [i] command descriptor length in bytes */
+	__u32 protocol;		/* [i] protocol type (BSG_PROTOCOL_*) */
+	__u32 subprotocol;	/* [i] subprotocol type (BSG_SUB_PROTOCOL_*) */
+	__u32 max_response_len;	/* [i] response buffer size in bytes */
+
+	__u64 response;		/* [i], [*o] response data address */
+	__u64 dout_xferp;	/* [i], [*i] */
+	__u32 dout_xfer_len;	/* [i] bytes to be transferred to device */
+	__u32 dout_iovec_count;	/* [i] 0 -> "flat" dout transfer else
+				 * dout_xferp points to array of iovec
+				 */
+	__u64 din_xferp;	/* [i], [*o] */
+	__u32 din_xfer_len;	/* [i] bytes to be transferred from device */
+	__u32 din_iovec_count;	/* [i] 0 -> "flat" din transfer */
+
+	__u32 timeout_ms;	/* [i] timeout in milliseconds */
+	__u32 flags;		/* [i] bit mask */
+	__u8  reserved[8];	/* reserved for future extension */
+};
 
 #endif /* _UAPIBSG_H */
-- 
2.25.1

[PATCH v5 2/3] bsg: add io_uring command support to generic layer

[Yang Xiuwei]

Add an io_uring command handler to the generic BSG layer. The new
.uring_cmd file operation validates io_uring features and delegates
handling to a per-queue bsg_uring_cmd_fn callback.

Extend bsg_register_queue() so transport drivers can register both
sg_io and io_uring command handlers.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
---
 block/bsg-lib.c         |  2 +-
 block/bsg.c             | 32 +++++++++++++++++++++++++++++++-
 drivers/scsi/scsi_bsg.c | 10 +++++++++-
 include/linux/bsg.h     |  6 +++++-
 4 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/block/bsg-lib.c b/block/bsg-lib.c
index 20cd0ef3c394..fdb4b290ca68 100644
--- a/block/bsg-lib.c
+++ b/block/bsg-lib.c
@@ -393,7 +393,7 @@ struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 
 	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 
-	bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn);
+	bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn, NULL);
 	if (IS_ERR(bset->bd)) {
 		ret = PTR_ERR(bset->bd);
 		goto out_cleanup_queue;
diff --git a/block/bsg.c b/block/bsg.c
index e0af6206ed28..8f23296a7033 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -12,6 +12,7 @@
 #include <linux/idr.h>
 #include <linux/bsg.h>
 #include <linux/slab.h>
+#include <linux/io_uring/cmd.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_ioctl.h>
@@ -28,6 +29,7 @@ struct bsg_device {
 	unsigned int timeout;
 	unsigned int reserved_size;
 	bsg_sg_io_fn *sg_io_fn;
+	bsg_uring_cmd_fn *uring_cmd_fn;
 };
 
 static inline struct bsg_device *to_bsg_device(struct inode *inode)
@@ -158,11 +160,37 @@ static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	}
 }
 
+static int bsg_check_uring_features(unsigned int issue_flags)
+{
+	/* BSG passthrough requires big SQE/CQE support */
+	if ((issue_flags & (IO_URING_F_SQE128|IO_URING_F_CQE32)) !=
+	    (IO_URING_F_SQE128|IO_URING_F_CQE32))
+		return -EOPNOTSUPP;
+	return 0;
+}
+
+static int bsg_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
+{
+	struct bsg_device *bd = to_bsg_device(file_inode(ioucmd->file));
+	struct request_queue *q = bd->queue;
+	bool open_for_write = ioucmd->file->f_mode & FMODE_WRITE;
+	int ret;
+
+	ret = bsg_check_uring_features(issue_flags);
+	if (ret)
+		return ret;
+
+	if (bd->uring_cmd_fn)
+		return bd->uring_cmd_fn(q, ioucmd, issue_flags, open_for_write);
+	return -EOPNOTSUPP;
+}
+
 static const struct file_operations bsg_fops = {
 	.open		=	bsg_open,
 	.release	=	bsg_release,
 	.unlocked_ioctl	=	bsg_ioctl,
 	.compat_ioctl	=	compat_ptr_ioctl,
+	.uring_cmd	=	bsg_uring_cmd,
 	.owner		=	THIS_MODULE,
 	.llseek		=	default_llseek,
 };
@@ -187,7 +215,8 @@ 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, bsg_sg_io_fn *sg_io_fn)
+		struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn,
+		bsg_uring_cmd_fn *uring_cmd_fn)
 {
 	struct bsg_device *bd;
 	int ret;
@@ -199,6 +228,7 @@ struct bsg_device *bsg_register_queue(struct request_queue *q,
 	bd->reserved_size = INT_MAX;
 	bd->queue = q;
 	bd->sg_io_fn = sg_io_fn;
+	bd->uring_cmd_fn = uring_cmd_fn;
 
 	ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL);
 	if (ret < 0) {
diff --git a/drivers/scsi/scsi_bsg.c b/drivers/scsi/scsi_bsg.c
index a9a9ec086a7e..4d57e524e141 100644
--- a/drivers/scsi/scsi_bsg.c
+++ b/drivers/scsi/scsi_bsg.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/bsg.h>
+#include <linux/io_uring/cmd.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_ioctl.h>
 #include <scsi/scsi_cmnd.h>
@@ -9,6 +10,12 @@
 
 #define uptr64(val) ((void __user *)(uintptr_t)(val))
 
+static int scsi_bsg_uring_cmd(struct request_queue *q, struct io_uring_cmd *ioucmd,
+			       unsigned int issue_flags, bool open_for_write)
+{
+	return -EOPNOTSUPP;
+}
+
 static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 		bool open_for_write, unsigned int timeout)
 {
@@ -99,5 +106,6 @@ static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 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_sg_io_fn);
+			dev_name(&sdev->sdev_gendev), scsi_bsg_sg_io_fn,
+			scsi_bsg_uring_cmd);
 }
diff --git a/include/linux/bsg.h b/include/linux/bsg.h
index ee2df73edf83..162730bfc2d8 100644
--- a/include/linux/bsg.h
+++ b/include/linux/bsg.h
@@ -7,13 +7,17 @@
 struct bsg_device;
 struct device;
 struct request_queue;
+struct io_uring_cmd;
 
 typedef int (bsg_sg_io_fn)(struct request_queue *, struct sg_io_v4 *hdr,
 		bool open_for_write, unsigned int timeout);
 
+typedef int (bsg_uring_cmd_fn)(struct request_queue *q, struct io_uring_cmd *ioucmd,
+			       unsigned int issue_flags, bool open_for_write);
+
 struct bsg_device *bsg_register_queue(struct request_queue *q,
 		struct device *parent, const char *name,
-		bsg_sg_io_fn *sg_io_fn);
+		bsg_sg_io_fn *sg_io_fn, bsg_uring_cmd_fn *uring_cmd_fn);
 void bsg_unregister_queue(struct bsg_device *bcd);
 
 #endif /* _LINUX_BSG_H */
-- 
2.25.1

[PATCH v5 3/3] scsi: bsg: add io_uring passthrough handler

[Yang Xiuwei]

Implement the SCSI-specific io_uring command handler for BSG using
struct bsg_uring_cmd.

The handler builds a SCSI request from the io_uring command, maps user
buffers (including fixed buffers), and completes asynchronously via a
request end_io callback and task_work. Completion returns a 32-bit
status and packed residual/sense information via CQE res and res2, and
supports IO_URING_F_NONBLOCK.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
---
 drivers/scsi/scsi_bsg.c | 198 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 197 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_bsg.c b/drivers/scsi/scsi_bsg.c
index 4d57e524e141..95b2427cc0bf 100644
--- a/drivers/scsi/scsi_bsg.c
+++ b/drivers/scsi/scsi_bsg.c
@@ -10,10 +10,206 @@
 
 #define uptr64(val) ((void __user *)(uintptr_t)(val))
 
+/*
+ * Per-command BSG SCSI PDU stored in io_uring_cmd.pdu[32].
+ * Holds temporary state between submission, completion and task_work.
+ */
+struct scsi_bsg_uring_cmd_pdu {
+	struct bio *bio;		/* mapped user buffer, unmap in task work */
+	struct request *req;		/* block request, freed in task work */
+	u64 response_addr;		/* user space response buffer address */
+	u32 resid_len;			/* residual transfer length */
+	/* Protocol-specific status fields using union for extensibility */
+	union {
+		struct {
+			u8 device_status;	/* SCSI device status (low 8 bits of result) */
+			u8 driver_status;	/* SCSI driver status (DRIVER_SENSE if check) */
+			u8 host_status;		/* SCSI host status (host_byte of result) */
+			u8 sense_len_wr;	/* actual sense data length written */
+		} scsi;
+		/* Future protocols can add their own status layouts here */
+	};
+};
+
+static inline struct scsi_bsg_uring_cmd_pdu *scsi_bsg_uring_cmd_pdu(
+	struct io_uring_cmd *ioucmd)
+{
+	return io_uring_cmd_to_pdu(ioucmd, struct scsi_bsg_uring_cmd_pdu);
+}
+
+/*
+ * Task work callback executed in process context.
+ * Builds res2 with status information and copies sense data to user space.
+ * res2 layout (64-bit):
+ *   0-7:   device_status
+ *   8-15:  driver_status
+ *   16-23: host_status
+ *   24-31: sense_len_wr
+ *   32-63: resid_len
+ */
+static void scsi_bsg_uring_task_cb(struct io_tw_req tw_req, io_tw_token_t tw)
+{
+	struct io_uring_cmd *ioucmd = io_uring_cmd_from_tw(tw_req);
+	struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd);
+	struct scsi_cmnd *scmd;
+	struct request *rq = pdu->req;
+	int ret = 0;
+	u64 res2;
+
+	scmd = blk_mq_rq_to_pdu(rq);
+
+	if (pdu->bio)
+		blk_rq_unmap_user(pdu->bio);
+
+	/* Build res2 with status information */
+	res2 = ((u64)pdu->resid_len << 32) |
+	       ((u64)(pdu->scsi.sense_len_wr & 0xff) << 24) |
+	       ((u64)(pdu->scsi.host_status & 0xff) << 16) |
+	       ((u64)(pdu->scsi.driver_status & 0xff) << 8) |
+	       (pdu->scsi.device_status & 0xff);
+
+	if (pdu->scsi.sense_len_wr && pdu->response_addr) {
+		if (copy_to_user(uptr64(pdu->response_addr), scmd->sense_buffer,
+				 pdu->scsi.sense_len_wr))
+			ret = -EFAULT;
+	}
+
+	blk_mq_free_request(rq);
+	io_uring_cmd_done32(ioucmd, ret, res2,
+			    IO_URING_CMD_TASK_WORK_ISSUE_FLAGS);
+}
+
+static enum rq_end_io_ret scsi_bsg_uring_cmd_done(struct request *req,
+						  blk_status_t status)
+{
+	struct io_uring_cmd *ioucmd = req->end_io_data;
+	struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd);
+	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
+
+	/* Pack SCSI status fields into union */
+	pdu->scsi.device_status = scmd->result & 0xff;
+	pdu->scsi.host_status = host_byte(scmd->result);
+	pdu->scsi.driver_status = 0;
+	pdu->scsi.sense_len_wr = 0;
+
+	if (scsi_status_is_check_condition(scmd->result)) {
+		pdu->scsi.driver_status = DRIVER_SENSE;
+		if (pdu->response_addr)
+			pdu->scsi.sense_len_wr = min_t(u8, scmd->sense_len, SCSI_SENSE_BUFFERSIZE);
+	}
+
+	pdu->resid_len = scmd->resid_len;
+
+	io_uring_cmd_do_in_task_lazy(ioucmd, scsi_bsg_uring_task_cb);
+	return RQ_END_IO_NONE;
+}
+
+static int scsi_bsg_map_user_buffer(struct request *req,
+				    struct io_uring_cmd *ioucmd,
+				    unsigned int issue_flags, gfp_t gfp_mask)
+{
+	const struct bsg_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
+	struct iov_iter iter;
+	bool is_write = cmd->dout_xfer_len > 0;
+	u64 buf_addr = is_write ? cmd->dout_xferp : cmd->din_xferp;
+	unsigned long buf_len = is_write ? cmd->dout_xfer_len : cmd->din_xfer_len;
+	int ret;
+
+	if (ioucmd->flags & IORING_URING_CMD_FIXED) {
+		ret = io_uring_cmd_import_fixed(buf_addr, buf_len,
+						is_write ? WRITE : READ,
+						&iter, ioucmd, issue_flags);
+		if (ret < 0)
+			return ret;
+		ret = blk_rq_map_user_iov(req->q, req, NULL, &iter, gfp_mask);
+	} else {
+		ret = blk_rq_map_user(req->q, req, NULL, uptr64(buf_addr),
+				      buf_len, gfp_mask);
+	}
+
+	return ret;
+}
+
 static int scsi_bsg_uring_cmd(struct request_queue *q, struct io_uring_cmd *ioucmd,
 			       unsigned int issue_flags, bool open_for_write)
 {
-	return -EOPNOTSUPP;
+	struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd);
+	const struct bsg_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
+	struct scsi_cmnd *scmd;
+	struct request *req;
+	blk_mq_req_flags_t blk_flags = 0;
+	gfp_t gfp_mask = GFP_KERNEL;
+	int ret = 0;
+
+	if (cmd->protocol != BSG_PROTOCOL_SCSI ||
+	    cmd->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
+		return -EINVAL;
+
+	if (!cmd->request || cmd->request_len == 0)
+		return -EINVAL;
+
+	if (cmd->dout_xfer_len && cmd->din_xfer_len) {
+		pr_warn_once("BIDI support in bsg has been removed.\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (cmd->dout_iovec_count > 0 || cmd->din_iovec_count > 0)
+		return -EOPNOTSUPP;
+
+	if (issue_flags & IO_URING_F_NONBLOCK) {
+		blk_flags = BLK_MQ_REQ_NOWAIT;
+		gfp_mask = GFP_NOWAIT;
+	}
+
+	req = scsi_alloc_request(q, cmd->dout_xfer_len ?
+				 REQ_OP_DRV_OUT : REQ_OP_DRV_IN, blk_flags);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	scmd = blk_mq_rq_to_pdu(req);
+	scmd->cmd_len = cmd->request_len;
+	if (scmd->cmd_len > sizeof(scmd->cmnd)) {
+		ret = -EINVAL;
+		goto out_free_req;
+	}
+	scmd->allowed = SG_DEFAULT_RETRIES;
+
+	if (copy_from_user(scmd->cmnd, uptr64(cmd->request), cmd->request_len)) {
+		ret = -EFAULT;
+		goto out_free_req;
+	}
+
+	if (!scsi_cmd_allowed(scmd->cmnd, open_for_write)) {
+		ret = -EPERM;
+		goto out_free_req;
+	}
+
+	pdu->response_addr = cmd->response;
+	scmd->sense_len = cmd->max_response_len ?
+		min(cmd->max_response_len, SCSI_SENSE_BUFFERSIZE) : SCSI_SENSE_BUFFERSIZE;
+
+	if (cmd->dout_xfer_len || cmd->din_xfer_len) {
+		ret = scsi_bsg_map_user_buffer(req, ioucmd, issue_flags, gfp_mask);
+		if (ret)
+			goto out_free_req;
+		pdu->bio = req->bio;
+	} else {
+		pdu->bio = NULL;
+	}
+
+	req->timeout = cmd->timeout_ms ?
+		msecs_to_jiffies(cmd->timeout_ms) : BLK_DEFAULT_SG_TIMEOUT;
+
+	req->end_io = scsi_bsg_uring_cmd_done;
+	req->end_io_data = ioucmd;
+	pdu->req = req;
+
+	blk_execute_rq_nowait(req, false);
+	return -EIOCBQUEUED;
+
+out_free_req:
+	blk_mq_free_request(req);
+	return ret;
 }
 
 static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
-- 
2.25.1

Re: [PATCH v5 3/3] scsi: bsg: add io_uring passthrough handler

[kernel test robot]

Hi Yang,

kernel test robot noticed the following build errors:

[auto build test ERROR on axboe/for-next]
[also build test ERROR on jejb-scsi/for-next mkp-scsi/for-next linus/master v7.0-rc2 next-20260303]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Yang-Xiuwei/bsg-add-bsg_uring_cmd-uapi-structure/20260304-160717
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux.git for-next
patch link:    https://lore.kernel.org/r/20260304080313.675768-4-yangxiuwei%40kylinos.cn
patch subject: [PATCH v5 3/3] scsi: bsg: add io_uring passthrough handler
config: x86_64-rhel-9.4 (https://download.01.org/0day-ci/archive/20260304/202603041450.tuj48h9Q-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260304/202603041450.tuj48h9Q-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603041450.tuj48h9Q-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/scsi/scsi_bsg.c: In function 'scsi_bsg_map_user_buffer':
>> drivers/scsi/scsi_bsg.c:111:71: error: macro "io_uring_sqe_cmd" requires 2 arguments, but only 1 given
     111 |         const struct bsg_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
         |                                                                       ^
   In file included from drivers/scsi/scsi_bsg.c:3:
   include/linux/io_uring/cmd.h:29:9: note: macro "io_uring_sqe_cmd" defined here
      29 | #define io_uring_sqe_cmd(sqe, type)     ({                                      \
         |         ^~~~~~~~~~~~~~~~
>> drivers/scsi/scsi_bsg.c:111:43: error: 'io_uring_sqe_cmd' undeclared (first use in this function); did you mean 'io_uring_sqe'?
     111 |         const struct bsg_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
         |                                           ^~~~~~~~~~~~~~~~
         |                                           io_uring_sqe
   drivers/scsi/scsi_bsg.c:111:43: note: each undeclared identifier is reported only once for each function it appears in
   drivers/scsi/scsi_bsg.c: In function 'scsi_bsg_uring_cmd':
   drivers/scsi/scsi_bsg.c:137:71: error: macro "io_uring_sqe_cmd" requires 2 arguments, but only 1 given
     137 |         const struct bsg_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
         |                                                                       ^
   include/linux/io_uring/cmd.h:29:9: note: macro "io_uring_sqe_cmd" defined here
      29 | #define io_uring_sqe_cmd(sqe, type)     ({                                      \
         |         ^~~~~~~~~~~~~~~~
   drivers/scsi/scsi_bsg.c:137:43: error: 'io_uring_sqe_cmd' undeclared (first use in this function); did you mean 'io_uring_sqe'?
     137 |         const struct bsg_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
         |                                           ^~~~~~~~~~~~~~~~
         |                                           io_uring_sqe
   drivers/scsi/scsi_bsg.c:203:21: error: assignment to 'enum rq_end_io_ret (*)(struct request *, blk_status_t,  const struct io_comp_batch *)' {aka 'enum rq_end_io_ret (*)(struct request *, unsigned char,  const struct io_comp_batch *)'} from incompatible pointer type 'enum rq_end_io_ret (*)(struct request *, blk_status_t)' {aka 'enum rq_end_io_ret (*)(struct request *, unsigned char)'} [-Wincompatible-pointer-types]
     203 |         req->end_io = scsi_bsg_uring_cmd_done;
         |                     ^


vim +/io_uring_sqe_cmd +111 drivers/scsi/scsi_bsg.c

   106	
   107	static int scsi_bsg_map_user_buffer(struct request *req,
   108					    struct io_uring_cmd *ioucmd,
   109					    unsigned int issue_flags, gfp_t gfp_mask)
   110	{
 > 111		const struct bsg_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
   112		struct iov_iter iter;
   113		bool is_write = cmd->dout_xfer_len > 0;
   114		u64 buf_addr = is_write ? cmd->dout_xferp : cmd->din_xferp;
   115		unsigned long buf_len = is_write ? cmd->dout_xfer_len : cmd->din_xfer_len;
   116		int ret;
   117	
   118		if (ioucmd->flags & IORING_URING_CMD_FIXED) {
   119			ret = io_uring_cmd_import_fixed(buf_addr, buf_len,
   120							is_write ? WRITE : READ,
   121							&iter, ioucmd, issue_flags);
   122			if (ret < 0)
   123				return ret;
   124			ret = blk_rq_map_user_iov(req->q, req, NULL, &iter, gfp_mask);
   125		} else {
   126			ret = blk_rq_map_user(req->q, req, NULL, uptr64(buf_addr),
   127					      buf_len, gfp_mask);
   128		}
   129	
   130		return ret;
   131	}
   132	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH v6 0/3] bsg: add io_uring command support for SCSI passthrough

[Yang Xiuwei]

This series adds io_uring command support to the BSG SCSI passthrough
path.

The goal is to allow userspace to submit SCSI passthrough commands via
IORING_OP_URING_CMD, in addition to the existing sg_io interface.
The io_uring path mirrors the existing BSG behaviour: it currently only
supports BSG_PROTOCOL_SCSI + BSG_SUB_PROTOCOL_SCSI_CMD and does not
support BIDI transfers.

Patch 1 defines struct bsg_uring_cmd in the UAPI so that userspace can
describe SCSI passthrough requests for io_uring.

Patch 2 extends the generic BSG layer with an .uring_cmd file operation
and a bsg_uring_cmd_fn callback, allowing transport-specific handlers to
be registered.

Patch 3 implements the SCSI BSG io_uring handler. It builds a SCSI
request from struct bsg_uring_cmd, maps user buffers (including fixed
buffers), and completes asynchronously via a request end_io callback and
task_work. Completion returns SCSI device/host/driver status, residual
length and sense data length packed into the CQE result.

Changes since v5:
- Fixed compilation errors:
  * Use io_uring_sqe128_cmd() instead of io_uring_sqe_cmd()
  * Update scsi_bsg_uring_cmd_done() signature to match rq_end_io_fn typedef

Compared to the earlier RFC v4 series [1], this version only includes
minor code cleanups (mainly comments and wording), without changing the
behaviour or logic of the implementation.

[1] https://lore.kernel.org/linux-block/20260122015653.703188-1-yangxiuwei@kylinos.cn/

Testing
-------
Testing was done inside a VM on a disk with:
  /sys/block/sdd/mq/0/nr_tags     = 1024
  /sys/block/sdd/queue/nr_requests = 256

The following SCSI INQUIRY micro-benchmark was run with N=100000:

  sg+SG_IO (v3), /dev/sg4:
    avg = 139.0 us, p50 = 128.9 us, p90 = 149.7 us, p99 = 301.0 us

  bsg+SG_IO (v4), /dev/bsg/2:0:0:0:
    avg = 97.2 us,  p50 = 92.7 us,  p90 = 111.5 us, p99 = 150.9 us

  bsg+io_uring, /dev/bsg/2:0:0:0:
    avg = 105.9 us, p50 = 95.4 us,  p90 = 116.2 us, p99 = 175.0 us

  bsg+io_uring (batch=64), /dev/bsg/2:0:0:0:
    avg = 61.9 us,  p50 = 60.9 us,  p90 = 63.9 us,  p99 = 94.6 us

These results show that the new io_uring path is comparable to the
existing BSG SG_IO interface for single-command workloads, and that
batched io_uring submission can significantly improve latency for
high-concurrency workloads when the device supports sufficient queue
depth.

Yang Xiuwei (3):
  bsg: add bsg_uring_cmd uapi structure
  bsg: add io_uring command support to generic layer
  scsi: bsg: add io_uring passthrough handler

 block/bsg-lib.c          |   2 +-
 block/bsg.c              |  32 +++++-
 drivers/scsi/scsi_bsg.c  | 207 ++++++++++++++++++++++++++++++++++++++-
 include/linux/bsg.h      |   6 +-
 include/uapi/linux/bsg.h |  21 ++++
 5 files changed, 264 insertions(+), 4 deletions(-)

base-commit: af4e9ef3d78420feb8fe58cd9a1ab80c501b3c08
-- 
2.25.1

[PATCH v6 1/3] bsg: add bsg_uring_cmd uapi structure

[Yang Xiuwei]

Add the bsg_uring_cmd structure to the BSG UAPI header to support
io_uring-based SCSI passthrough operations via IORING_OP_URING_CMD.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
---
 include/uapi/linux/bsg.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/uapi/linux/bsg.h b/include/uapi/linux/bsg.h
index cd6302def5ed..983c6e2b6871 100644
--- a/include/uapi/linux/bsg.h
+++ b/include/uapi/linux/bsg.h
@@ -63,5 +63,26 @@ struct sg_io_v4 {
 	__u32 padding;
 };
 
+struct bsg_uring_cmd {
+	__u64 request;		/* [i], [*i] command descriptor address */
+	__u32 request_len;	/* [i] command descriptor length in bytes */
+	__u32 protocol;		/* [i] protocol type (BSG_PROTOCOL_*) */
+	__u32 subprotocol;	/* [i] subprotocol type (BSG_SUB_PROTOCOL_*) */
+	__u32 max_response_len;	/* [i] response buffer size in bytes */
+
+	__u64 response;		/* [i], [*o] response data address */
+	__u64 dout_xferp;	/* [i], [*i] */
+	__u32 dout_xfer_len;	/* [i] bytes to be transferred to device */
+	__u32 dout_iovec_count;	/* [i] 0 -> "flat" dout transfer else
+				 * dout_xferp points to array of iovec
+				 */
+	__u64 din_xferp;	/* [i], [*o] */
+	__u32 din_xfer_len;	/* [i] bytes to be transferred from device */
+	__u32 din_iovec_count;	/* [i] 0 -> "flat" din transfer */
+
+	__u32 timeout_ms;	/* [i] timeout in milliseconds */
+	__u32 flags;		/* [i] bit mask */
+	__u8  reserved[8];	/* reserved for future extension */
+};
 
 #endif /* _UAPIBSG_H */
-- 
2.25.1

[PATCH v6 2/3] bsg: add io_uring command support to generic layer

[Yang Xiuwei]

Add an io_uring command handler to the generic BSG layer. The new
.uring_cmd file operation validates io_uring features and delegates
handling to a per-queue bsg_uring_cmd_fn callback.

Extend bsg_register_queue() so transport drivers can register both
sg_io and io_uring command handlers.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
---
 block/bsg-lib.c         |  2 +-
 block/bsg.c             | 32 +++++++++++++++++++++++++++++++-
 drivers/scsi/scsi_bsg.c | 10 +++++++++-
 include/linux/bsg.h     |  6 +++++-
 4 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/block/bsg-lib.c b/block/bsg-lib.c
index 20cd0ef3c394..fdb4b290ca68 100644
--- a/block/bsg-lib.c
+++ b/block/bsg-lib.c
@@ -393,7 +393,7 @@ struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 
 	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 
-	bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn);
+	bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn, NULL);
 	if (IS_ERR(bset->bd)) {
 		ret = PTR_ERR(bset->bd);
 		goto out_cleanup_queue;
diff --git a/block/bsg.c b/block/bsg.c
index e0af6206ed28..8f23296a7033 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -12,6 +12,7 @@
 #include <linux/idr.h>
 #include <linux/bsg.h>
 #include <linux/slab.h>
+#include <linux/io_uring/cmd.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_ioctl.h>
@@ -28,6 +29,7 @@ struct bsg_device {
 	unsigned int timeout;
 	unsigned int reserved_size;
 	bsg_sg_io_fn *sg_io_fn;
+	bsg_uring_cmd_fn *uring_cmd_fn;
 };
 
 static inline struct bsg_device *to_bsg_device(struct inode *inode)
@@ -158,11 +160,37 @@ static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	}
 }
 
+static int bsg_check_uring_features(unsigned int issue_flags)
+{
+	/* BSG passthrough requires big SQE/CQE support */
+	if ((issue_flags & (IO_URING_F_SQE128|IO_URING_F_CQE32)) !=
+	    (IO_URING_F_SQE128|IO_URING_F_CQE32))
+		return -EOPNOTSUPP;
+	return 0;
+}
+
+static int bsg_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
+{
+	struct bsg_device *bd = to_bsg_device(file_inode(ioucmd->file));
+	struct request_queue *q = bd->queue;
+	bool open_for_write = ioucmd->file->f_mode & FMODE_WRITE;
+	int ret;
+
+	ret = bsg_check_uring_features(issue_flags);
+	if (ret)
+		return ret;
+
+	if (bd->uring_cmd_fn)
+		return bd->uring_cmd_fn(q, ioucmd, issue_flags, open_for_write);
+	return -EOPNOTSUPP;
+}
+
 static const struct file_operations bsg_fops = {
 	.open		=	bsg_open,
 	.release	=	bsg_release,
 	.unlocked_ioctl	=	bsg_ioctl,
 	.compat_ioctl	=	compat_ptr_ioctl,
+	.uring_cmd	=	bsg_uring_cmd,
 	.owner		=	THIS_MODULE,
 	.llseek		=	default_llseek,
 };
@@ -187,7 +215,8 @@ 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, bsg_sg_io_fn *sg_io_fn)
+		struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn,
+		bsg_uring_cmd_fn *uring_cmd_fn)
 {
 	struct bsg_device *bd;
 	int ret;
@@ -199,6 +228,7 @@ struct bsg_device *bsg_register_queue(struct request_queue *q,
 	bd->reserved_size = INT_MAX;
 	bd->queue = q;
 	bd->sg_io_fn = sg_io_fn;
+	bd->uring_cmd_fn = uring_cmd_fn;
 
 	ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL);
 	if (ret < 0) {
diff --git a/drivers/scsi/scsi_bsg.c b/drivers/scsi/scsi_bsg.c
index a9a9ec086a7e..4d57e524e141 100644
--- a/drivers/scsi/scsi_bsg.c
+++ b/drivers/scsi/scsi_bsg.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/bsg.h>
+#include <linux/io_uring/cmd.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_ioctl.h>
 #include <scsi/scsi_cmnd.h>
@@ -9,6 +10,12 @@
 
 #define uptr64(val) ((void __user *)(uintptr_t)(val))
 
+static int scsi_bsg_uring_cmd(struct request_queue *q, struct io_uring_cmd *ioucmd,
+			       unsigned int issue_flags, bool open_for_write)
+{
+	return -EOPNOTSUPP;
+}
+
 static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 		bool open_for_write, unsigned int timeout)
 {
@@ -99,5 +106,6 @@ static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 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_sg_io_fn);
+			dev_name(&sdev->sdev_gendev), scsi_bsg_sg_io_fn,
+			scsi_bsg_uring_cmd);
 }
diff --git a/include/linux/bsg.h b/include/linux/bsg.h
index ee2df73edf83..162730bfc2d8 100644
--- a/include/linux/bsg.h
+++ b/include/linux/bsg.h
@@ -7,13 +7,17 @@
 struct bsg_device;
 struct device;
 struct request_queue;
+struct io_uring_cmd;
 
 typedef int (bsg_sg_io_fn)(struct request_queue *, struct sg_io_v4 *hdr,
 		bool open_for_write, unsigned int timeout);
 
+typedef int (bsg_uring_cmd_fn)(struct request_queue *q, struct io_uring_cmd *ioucmd,
+			       unsigned int issue_flags, bool open_for_write);
+
 struct bsg_device *bsg_register_queue(struct request_queue *q,
 		struct device *parent, const char *name,
-		bsg_sg_io_fn *sg_io_fn);
+		bsg_sg_io_fn *sg_io_fn, bsg_uring_cmd_fn *uring_cmd_fn);
 void bsg_unregister_queue(struct bsg_device *bcd);
 
 #endif /* _LINUX_BSG_H */
-- 
2.25.1

[PATCH v6 3/3] scsi: bsg: add io_uring passthrough handler

[Yang Xiuwei]

Implement the SCSI-specific io_uring command handler for BSG using
struct bsg_uring_cmd.

The handler builds a SCSI request from the io_uring command, maps user
buffers (including fixed buffers), and completes asynchronously via a
request end_io callback and task_work. Completion returns a 32-bit
status and packed residual/sense information via CQE res and res2, and
supports IO_URING_F_NONBLOCK.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
---
 drivers/scsi/scsi_bsg.c | 199 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 198 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_bsg.c b/drivers/scsi/scsi_bsg.c
index 4d57e524e141..5b6ed15b8b19 100644
--- a/drivers/scsi/scsi_bsg.c
+++ b/drivers/scsi/scsi_bsg.c
@@ -10,10 +10,207 @@
 
 #define uptr64(val) ((void __user *)(uintptr_t)(val))
 
+/*
+ * Per-command BSG SCSI PDU stored in io_uring_cmd.pdu[32].
+ * Holds temporary state between submission, completion and task_work.
+ */
+struct scsi_bsg_uring_cmd_pdu {
+	struct bio *bio;		/* mapped user buffer, unmap in task work */
+	struct request *req;		/* block request, freed in task work */
+	u64 response_addr;		/* user space response buffer address */
+	u32 resid_len;			/* residual transfer length */
+	/* Protocol-specific status fields using union for extensibility */
+	union {
+		struct {
+			u8 device_status;	/* SCSI device status (low 8 bits of result) */
+			u8 driver_status;	/* SCSI driver status (DRIVER_SENSE if check) */
+			u8 host_status;		/* SCSI host status (host_byte of result) */
+			u8 sense_len_wr;	/* actual sense data length written */
+		} scsi;
+		/* Future protocols can add their own status layouts here */
+	};
+};
+
+static inline struct scsi_bsg_uring_cmd_pdu *scsi_bsg_uring_cmd_pdu(
+	struct io_uring_cmd *ioucmd)
+{
+	return io_uring_cmd_to_pdu(ioucmd, struct scsi_bsg_uring_cmd_pdu);
+}
+
+/*
+ * Task work callback executed in process context.
+ * Builds res2 with status information and copies sense data to user space.
+ * res2 layout (64-bit):
+ *   0-7:   device_status
+ *   8-15:  driver_status
+ *   16-23: host_status
+ *   24-31: sense_len_wr
+ *   32-63: resid_len
+ */
+static void scsi_bsg_uring_task_cb(struct io_tw_req tw_req, io_tw_token_t tw)
+{
+	struct io_uring_cmd *ioucmd = io_uring_cmd_from_tw(tw_req);
+	struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd);
+	struct scsi_cmnd *scmd;
+	struct request *rq = pdu->req;
+	int ret = 0;
+	u64 res2;
+
+	scmd = blk_mq_rq_to_pdu(rq);
+
+	if (pdu->bio)
+		blk_rq_unmap_user(pdu->bio);
+
+	/* Build res2 with status information */
+	res2 = ((u64)pdu->resid_len << 32) |
+	       ((u64)(pdu->scsi.sense_len_wr & 0xff) << 24) |
+	       ((u64)(pdu->scsi.host_status & 0xff) << 16) |
+	       ((u64)(pdu->scsi.driver_status & 0xff) << 8) |
+	       (pdu->scsi.device_status & 0xff);
+
+	if (pdu->scsi.sense_len_wr && pdu->response_addr) {
+		if (copy_to_user(uptr64(pdu->response_addr), scmd->sense_buffer,
+				 pdu->scsi.sense_len_wr))
+			ret = -EFAULT;
+	}
+
+	blk_mq_free_request(rq);
+	io_uring_cmd_done32(ioucmd, ret, res2,
+			    IO_URING_CMD_TASK_WORK_ISSUE_FLAGS);
+}
+
+static enum rq_end_io_ret scsi_bsg_uring_cmd_done(struct request *req,
+						  blk_status_t status,
+						  const struct io_comp_batch *iocb)
+{
+	struct io_uring_cmd *ioucmd = req->end_io_data;
+	struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd);
+	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
+
+	/* Pack SCSI status fields into union */
+	pdu->scsi.device_status = scmd->result & 0xff;
+	pdu->scsi.host_status = host_byte(scmd->result);
+	pdu->scsi.driver_status = 0;
+	pdu->scsi.sense_len_wr = 0;
+
+	if (scsi_status_is_check_condition(scmd->result)) {
+		pdu->scsi.driver_status = DRIVER_SENSE;
+		if (pdu->response_addr)
+			pdu->scsi.sense_len_wr = min_t(u8, scmd->sense_len, SCSI_SENSE_BUFFERSIZE);
+	}
+
+	pdu->resid_len = scmd->resid_len;
+
+	io_uring_cmd_do_in_task_lazy(ioucmd, scsi_bsg_uring_task_cb);
+	return RQ_END_IO_NONE;
+}
+
+static int scsi_bsg_map_user_buffer(struct request *req,
+				    struct io_uring_cmd *ioucmd,
+				    unsigned int issue_flags, gfp_t gfp_mask)
+{
+	const struct bsg_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe, struct bsg_uring_cmd);
+	struct iov_iter iter;
+	bool is_write = cmd->dout_xfer_len > 0;
+	u64 buf_addr = is_write ? cmd->dout_xferp : cmd->din_xferp;
+	unsigned long buf_len = is_write ? cmd->dout_xfer_len : cmd->din_xfer_len;
+	int ret;
+
+	if (ioucmd->flags & IORING_URING_CMD_FIXED) {
+		ret = io_uring_cmd_import_fixed(buf_addr, buf_len,
+						is_write ? WRITE : READ,
+						&iter, ioucmd, issue_flags);
+		if (ret < 0)
+			return ret;
+		ret = blk_rq_map_user_iov(req->q, req, NULL, &iter, gfp_mask);
+	} else {
+		ret = blk_rq_map_user(req->q, req, NULL, uptr64(buf_addr),
+				      buf_len, gfp_mask);
+	}
+
+	return ret;
+}
+
 static int scsi_bsg_uring_cmd(struct request_queue *q, struct io_uring_cmd *ioucmd,
 			       unsigned int issue_flags, bool open_for_write)
 {
-	return -EOPNOTSUPP;
+	struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd);
+	const struct bsg_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe, struct bsg_uring_cmd);
+	struct scsi_cmnd *scmd;
+	struct request *req;
+	blk_mq_req_flags_t blk_flags = 0;
+	gfp_t gfp_mask = GFP_KERNEL;
+	int ret = 0;
+
+	if (cmd->protocol != BSG_PROTOCOL_SCSI ||
+	    cmd->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
+		return -EINVAL;
+
+	if (!cmd->request || cmd->request_len == 0)
+		return -EINVAL;
+
+	if (cmd->dout_xfer_len && cmd->din_xfer_len) {
+		pr_warn_once("BIDI support in bsg has been removed.\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (cmd->dout_iovec_count > 0 || cmd->din_iovec_count > 0)
+		return -EOPNOTSUPP;
+
+	if (issue_flags & IO_URING_F_NONBLOCK) {
+		blk_flags = BLK_MQ_REQ_NOWAIT;
+		gfp_mask = GFP_NOWAIT;
+	}
+
+	req = scsi_alloc_request(q, cmd->dout_xfer_len ?
+				 REQ_OP_DRV_OUT : REQ_OP_DRV_IN, blk_flags);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	scmd = blk_mq_rq_to_pdu(req);
+	scmd->cmd_len = cmd->request_len;
+	if (scmd->cmd_len > sizeof(scmd->cmnd)) {
+		ret = -EINVAL;
+		goto out_free_req;
+	}
+	scmd->allowed = SG_DEFAULT_RETRIES;
+
+	if (copy_from_user(scmd->cmnd, uptr64(cmd->request), cmd->request_len)) {
+		ret = -EFAULT;
+		goto out_free_req;
+	}
+
+	if (!scsi_cmd_allowed(scmd->cmnd, open_for_write)) {
+		ret = -EPERM;
+		goto out_free_req;
+	}
+
+	pdu->response_addr = cmd->response;
+	scmd->sense_len = cmd->max_response_len ?
+		min(cmd->max_response_len, SCSI_SENSE_BUFFERSIZE) : SCSI_SENSE_BUFFERSIZE;
+
+	if (cmd->dout_xfer_len || cmd->din_xfer_len) {
+		ret = scsi_bsg_map_user_buffer(req, ioucmd, issue_flags, gfp_mask);
+		if (ret)
+			goto out_free_req;
+		pdu->bio = req->bio;
+	} else {
+		pdu->bio = NULL;
+	}
+
+	req->timeout = cmd->timeout_ms ?
+		msecs_to_jiffies(cmd->timeout_ms) : BLK_DEFAULT_SG_TIMEOUT;
+
+	req->end_io = scsi_bsg_uring_cmd_done;
+	req->end_io_data = ioucmd;
+	pdu->req = req;
+
+	blk_execute_rq_nowait(req, false);
+	return -EIOCBQUEUED;
+
+out_free_req:
+	blk_mq_free_request(req);
+	return ret;
 }
 
 static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
-- 
2.25.1

Re: [PATCH v6 0/3] bsg: add io_uring command support for SCSI passthrough

[Bart Van Assche]

On 3/4/26 7:28 PM, Yang Xiuwei wrote:
> This series adds io_uring command support to the BSG SCSI passthrough
> path.

Please send a new version of a patch series as a new email thread.
Otherwise the new version may get overlooked.

Thanks,

Bart.

Re: [PATCH v6 1/3] bsg: add bsg_uring_cmd uapi structure

[Bart Van Assche]

On 3/4/26 7:28 PM, Yang Xiuwei wrote:
> +	__u32 flags;		/* [i] bit mask */

Please document what flags are supported and what their meaning is.

Thanks,

Bart.

Re: [PATCH v6 2/3] bsg: add io_uring command support to generic layer

[Bart Van Assche]

On 3/4/26 7:28 PM, Yang Xiuwei wrote:
> +static int bsg_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
> +{
> +	struct bsg_device *bd = to_bsg_device(file_inode(ioucmd->file));
> +	struct request_queue *q = bd->queue;
> +	bool open_for_write = ioucmd->file->f_mode & FMODE_WRITE;
> +	int ret;

Please order declarations from longest to shortest.

> +	if (bd->uring_cmd_fn)
> +		return bd->uring_cmd_fn(q, ioucmd, issue_flags, open_for_write);
> +	return -EOPNOTSUPP;

The traditional Linux kernel coding style is to return early in case of
an error. For the above code that means writing it as follows:

	if (!bd->uring_cmd_fn)
		return -EOPNOTSUPP;

	return bd->uring_cmd_fn(q, ioucmd, issue_flags, open_for_write);

Thanks,

Bart.

Re: [PATCH v6 3/3] scsi: bsg: add io_uring passthrough handler

[Bart Van Assche]

On 3/4/26 7:28 PM, Yang Xiuwei wrote:
> +			u8 device_status;	/* SCSI device status (low 8 bits of result) */
> +			u8 driver_status;	/* SCSI driver status (DRIVER_SENSE if check) */
> +			u8 host_status;		/* SCSI host status (host_byte of result) */

Why separate members for device_status, driver_status and host_status 
instead of storing the SCSI result (scsi_cmnd.result)?

> +	/* Build res2 with status information */
> +	res2 = ((u64)pdu->resid_len << 32) |
> +	       ((u64)(pdu->scsi.sense_len_wr & 0xff) << 24) |
> +	       ((u64)(pdu->scsi.host_status & 0xff) << 16) |
> +	       ((u64)(pdu->scsi.driver_status & 0xff) << 8) |
> +	       (pdu->scsi.device_status & 0xff);

Please remove the superfluous " & 0xff" from u8 expressions.

> +	pdu->scsi.device_status = scmd->result & 0xff;

Please use the status_byte() macro instead of open-coding it.

Thanks,

Bart.

Re: [PATCH v6 0/3] bsg: add io_uring command support for SCSI passthrough

[Yang Xiuwei]

On 2026-03-05 15:12, Bart Van Assche wrote:
> Please send a new version of a patch series as a new email thread.
> Otherwise the new version may get overlooked.

Thanks for the reminder. I'll send v7 as a new thread.

Best regards,
Yang Xiuwei

Re: [PATCH v6 1/3] bsg: add bsg_uring_cmd uapi structure

[Yang Xiuwei]

On 2026-03-05 15:14, Bart Van Assche wrote:
> Please document what flags are supported and what their meaning is.

After analysis, I've decided to remove the flags field entirely since
io_uring already provides sufficient control mechanisms (sqe->flags,
sqe->uring_cmd_flags, issue_flags). The flags field is not used in the
current implementation and is not needed for future functionality, as
io_uring's existing flags cover all necessary control aspects.

Will remove the flags field in v7.

Best regards,
Yang Xiuwei

Re: [PATCH v6 2/3] bsg: add io_uring command support to generic layer

[Yang Xiuwei]

On 2026-03-05 15:17, Bart Van Assche wrote:
> Please order declarations from longest to shortest.

Done. Will reorder variable declarations from longest to shortest.

> The traditional Linux kernel coding style is to return early in case of
> an error. For the above code that means writing it as follows:
> 
> 	if (!bd->uring_cmd_fn)
> 		return -EOPNOTSUPP;
> 
> 	return bd->uring_cmd_fn(q, ioucmd, issue_flags, open_for_write);

Done. Will use early return style for error handling.

Will include these changes in v7.

Best regards,
Yang Xiuwei

Re: [PATCH v6 3/3] scsi: bsg: add io_uring passthrough handler

[Yang Xiuwei]

On 2026-03-05 15:39, Bart Van Assche wrote:
> Why separate members for device_status, driver_status and host_status 
> instead of storing the SCSI result (scsi_cmnd.result)?

You're right. Since scmd remains valid until blk_mq_free_request() is
called in the task work callback, we can extract all status information
directly from scmd->result in scsi_bsg_uring_task_cb() instead of storing
it in the PDU. This approach is cleaner and follows your suggestion to
read from scmd->result directly.

> Please remove the superfluous " & 0xff" from u8 expressions.

Done. Removed all unnecessary " & 0xff" from u8 expressions.

> Please use the status_byte() macro instead of open-coding it.

Done. Using status_byte() macro instead of open-coding
(scmd->result & 0xff).

Will include these changes in v7.

Best regards,
Yang Xiuwei