scsi: core: Remove the cmd field from struct scsi_request

Now that each scsi_request is backed by a scsi_cmnd, there is no need to
indirect the CDB storage.  Change all submitters of SCSI passthrough
requests to store the CDB information directly in the scsi_cmnd, and while
doing so allocate the full 32 bytes that cover all Linux supported SCSI
hosts instead of requiring dynamic allocation for > 16 byte CDBs.  On
64-bit systems this does not change the size of the scsi_cmnd at all, while
on 32-bit systems it slightly increases it for now, but that increase will
be made up by the removal of the remaining scsi_request fields.

Link: https://lore.kernel.org/r/20220224175552.988286-4-hch@lst.de
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/ata/libata-scsi.c

@@ -1022,7 +1022,9 @@ void ata_scsi_sdev_config(struct scsi_device *sdev)
  */
 bool ata_scsi_dma_need_drain(struct request *rq)
 {
-	return atapi_cmd_type(scsi_req(rq)->cmd[0]) == ATAPI_MISC;
+	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
+
+	return atapi_cmd_type(scmd->cmnd[0]) == ATAPI_MISC;
 }
 EXPORT_SYMBOL_GPL(ata_scsi_dma_need_drain);
 

drivers/block/pktcdvd.c

@@ -693,13 +693,15 @@ static void pkt_rbtree_insert(struct pktcdvd_device *pd, struct pkt_rb_node *nod
 static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *cgc)
 {
 	struct request_queue *q = bdev_get_queue(pd->bdev);
+	struct scsi_cmnd *scmd;
 	struct request *rq;
 	int ret = 0;
 
 	rq = scsi_alloc_request(q, (cgc->data_direction == CGC_DATA_WRITE) ?
 			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
+	scmd = blk_mq_rq_to_pdu(rq);
 
 	if (cgc->buflen) {
 		ret = blk_rq_map_kern(q, rq, cgc->buffer, cgc->buflen,
@@ -708,8 +710,8 @@ static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *
 			goto out;
 	}
 
-	scsi_req(rq)->cmd_len = COMMAND_SIZE(cgc->cmd[0]);
-	memcpy(scsi_req(rq)->cmd, cgc->cmd, CDROM_PACKET_SIZE);
+	scmd->cmd_len = COMMAND_SIZE(cgc->cmd[0]);
+	memcpy(scmd->cmnd, cgc->cmd, CDROM_PACKET_SIZE);
 
 	rq->timeout = 60*HZ;
 	if (cgc->quiet)

drivers/scsi/scsi_bsg.c

@@ -13,6 +13,7 @@ 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 scsi_cmnd *scmd;
 	struct request *rq;
 	struct bio *bio;
 	int ret;
@@ -33,19 +34,19 @@ static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 
 	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)
-			goto out_put_request;
+	scmd = blk_mq_rq_to_pdu(rq);
+	scmd->cmd_len = hdr->request_len;
+	if (scmd->cmd_len > sizeof(scmd->cmnd)) {
+		ret = -EINVAL;
+		goto out_put_request;
 	}
 
 	ret = -EFAULT;
-	if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
-		goto out_free_cmd;
+	if (copy_from_user(scmd->cmnd, uptr64(hdr->request), scmd->cmd_len))
+		goto out_put_request;
 	ret = -EPERM;
-	if (!scsi_cmd_allowed(sreq->cmd, mode))
-		goto out_free_cmd;
+	if (!scsi_cmd_allowed(scmd->cmnd, mode))
+		goto out_put_request;
 
 	ret = 0;
 	if (hdr->dout_xfer_len) {
@@ -57,7 +58,7 @@ static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 	}
 
 	if (ret)
-		goto out_free_cmd;
+		goto out_put_request;
 
 	bio = rq->bio;
 	blk_execute_rq(rq, !(hdr->flags & BSG_FLAG_Q_AT_TAIL));
@@ -92,8 +93,6 @@ static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 
 	blk_rq_unmap_user(bio);
 
-out_free_cmd:
-	scsi_req_free_cmd(scsi_req(rq));
 out_put_request:
 	blk_mq_free_request(rq);
 	return ret;

drivers/scsi/scsi_debugfs.c

@@ -36,11 +36,9 @@ void scsi_show_rq(struct seq_file *m, struct request *rq)
 	struct scsi_cmnd *cmd = container_of(scsi_req(rq), typeof(*cmd), req);
 	int alloc_ms = jiffies_to_msecs(jiffies - cmd->jiffies_at_alloc);
 	int timeout_ms = jiffies_to_msecs(rq->timeout);
-	const u8 *const cdb = READ_ONCE(cmd->cmnd);
 	char buf[80] = "(?)";
 
-	if (cdb)
-		__scsi_format_command(buf, sizeof(buf), cdb, cmd->cmd_len);
+	__scsi_format_command(buf, sizeof(buf), cmd->cmnd, cmd->cmd_len);
 	seq_printf(m, ", .cmd=%s, .retries=%d, .result = %#x, .flags=", buf,
 		   cmd->retries, cmd->result);
 	scsi_flags_show(m, cmd->flags, scsi_cmd_flags,

drivers/scsi/scsi_error.c

@@ -980,7 +980,7 @@ static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
  * @scmd:       SCSI command structure to hijack
  * @ses:        structure to save restore information
  * @cmnd:       CDB to send. Can be NULL if no new cmnd is needed
- * @cmnd_size:  size in bytes of @cmnd (must be <= BLK_MAX_CDB)
+ * @cmnd_size:  size in bytes of @cmnd (must be <= MAX_COMMAND_SIZE)
  * @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
  *
  * This function is used to save a scsi command information before re-execution
@@ -1002,7 +1002,6 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
 	 * command.
 	 */
 	ses->cmd_len = scmd->cmd_len;
-	ses->cmnd = scmd->cmnd;
 	ses->data_direction = scmd->sc_data_direction;
 	ses->sdb = scmd->sdb;
 	ses->result = scmd->result;
@@ -1013,8 +1012,8 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
 
 	scmd->prot_op = SCSI_PROT_NORMAL;
 	scmd->eh_eflags = 0;
-	scmd->cmnd = ses->eh_cmnd;
-	memset(scmd->cmnd, 0, BLK_MAX_CDB);
+	memcpy(ses->cmnd, scmd->cmnd, sizeof(ses->cmnd));
+	memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
 	memset(&scmd->sdb, 0, sizeof(scmd->sdb));
 	scmd->result = 0;
 	scmd->req.resid_len = 0;
@@ -1033,7 +1032,7 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
 	} else {
 		scmd->sc_data_direction = DMA_NONE;
 		if (cmnd) {
-			BUG_ON(cmnd_size > BLK_MAX_CDB);
+			BUG_ON(cmnd_size > sizeof(scmd->cmnd));
 			memcpy(scmd->cmnd, cmnd, cmnd_size);
 			scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 		}
@@ -1066,7 +1065,7 @@ void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
 	 * Restore original data
 	 */
 	scmd->cmd_len = ses->cmd_len;
-	scmd->cmnd = ses->cmnd;
+	memcpy(scmd->cmnd, ses->cmnd, sizeof(ses->cmnd));
 	scmd->sc_data_direction = ses->data_direction;
 	scmd->sdb = ses->sdb;
 	scmd->result = ses->result;
@@ -2022,21 +2021,23 @@ static void eh_lock_door_done(struct request *req, blk_status_t status)
  */
 static void scsi_eh_lock_door(struct scsi_device *sdev)
 {
+	struct scsi_cmnd *scmd;
 	struct request *req;
 	struct scsi_request *rq;
 
 	req = scsi_alloc_request(sdev->request_queue, REQ_OP_DRV_IN, 0);
 	if (IS_ERR(req))
 		return;
 	rq = scsi_req(req);
+	scmd = blk_mq_rq_to_pdu(req);
 
-	rq->cmd[0] = ALLOW_MEDIUM_REMOVAL;
-	rq->cmd[1] = 0;
-	rq->cmd[2] = 0;
-	rq->cmd[3] = 0;
-	rq->cmd[4] = SCSI_REMOVAL_PREVENT;
-	rq->cmd[5] = 0;
-	rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
+	scmd->cmnd[0] = ALLOW_MEDIUM_REMOVAL;
+	scmd->cmnd[1] = 0;
+	scmd->cmnd[2] = 0;
+	scmd->cmnd[3] = 0;
+	scmd->cmnd[4] = SCSI_REMOVAL_PREVENT;
+	scmd->cmnd[5] = 0;
+	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 
 	req->rq_flags |= RQF_QUIET;
 	req->timeout = 10 * HZ;
@@ -2399,7 +2400,6 @@ scsi_ioctl_reset(struct scsi_device *dev, int __user *arg)
 
 	scmd = (struct scsi_cmnd *)(rq + 1);
 	scsi_init_command(dev, scmd);
-	scmd->cmnd = scsi_req(rq)->cmd;
 
 	scmd->submitter = SUBMITTED_BY_SCSI_RESET_IOCTL;
 	memset(&scmd->sdb, 0, sizeof(scmd->sdb));

drivers/scsi/scsi_ioctl.c

@@ -345,19 +345,15 @@ EXPORT_SYMBOL(scsi_cmd_allowed);
 static int scsi_fill_sghdr_rq(struct scsi_device *sdev, struct request *rq,
 		struct sg_io_hdr *hdr, fmode_t mode)
 {
-	struct scsi_request *req = scsi_req(rq);
+	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
 
 	if (hdr->cmd_len < 6)
 		return -EMSGSIZE;
-	if (copy_from_user(req->cmd, hdr->cmdp, hdr->cmd_len))
+	if (copy_from_user(scmd->cmnd, hdr->cmdp, hdr->cmd_len))
 		return -EFAULT;
-	if (!scsi_cmd_allowed(req->cmd, mode))
+	if (!scsi_cmd_allowed(scmd->cmnd, mode))
 		return -EPERM;
-
-	/*
-	 * fill in request structure
-	 */
-	req->cmd_len = hdr->cmd_len;
+	scmd->cmd_len = hdr->cmd_len;
 
 	rq->timeout = msecs_to_jiffies(hdr->timeout);
 	if (!rq->timeout)
@@ -416,6 +412,7 @@ static int sg_io(struct scsi_device *sdev, struct sg_io_hdr *hdr, fmode_t mode)
 	int at_head = 0;
 	struct request *rq;
 	struct scsi_request *req;
+	struct scsi_cmnd *scmd;
 	struct bio *bio;
 
 	if (hdr->interface_id != 'S')
@@ -444,16 +441,16 @@ static int sg_io(struct scsi_device *sdev, struct sg_io_hdr *hdr, fmode_t mode)
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
 	req = scsi_req(rq);
+	scmd = blk_mq_rq_to_pdu(rq);
 
-	if (hdr->cmd_len > BLK_MAX_CDB) {
-		req->cmd = kzalloc(hdr->cmd_len, GFP_KERNEL);
-		if (!req->cmd)
-			goto out_put_request;
+	if (hdr->cmd_len > sizeof(scmd->cmnd)) {
+		ret = -EINVAL;
+		goto out_put_request;
 	}
 
 	ret = scsi_fill_sghdr_rq(sdev, rq, hdr, mode);
 	if (ret < 0)
-		goto out_free_cdb;
+		goto out_put_request;
 
 	ret = 0;
 	if (hdr->iovec_count) {
@@ -463,7 +460,7 @@ static int sg_io(struct scsi_device *sdev, struct sg_io_hdr *hdr, fmode_t mode)
 		ret = import_iovec(rq_data_dir(rq), hdr->dxferp,
 				   hdr->iovec_count, 0, &iov, &i);
 		if (ret < 0)
-			goto out_free_cdb;
+			goto out_put_request;
 
 		/* SG_IO howto says that the shorter of the two wins */
 		iov_iter_truncate(&i, hdr->dxfer_len);
@@ -475,7 +472,7 @@ static int sg_io(struct scsi_device *sdev, struct sg_io_hdr *hdr, fmode_t mode)
 				      hdr->dxfer_len, GFP_KERNEL);
 
 	if (ret)
-		goto out_free_cdb;
+		goto out_put_request;
 
 	bio = rq->bio;
 	req->retries = 0;
@@ -488,8 +485,6 @@ static int sg_io(struct scsi_device *sdev, struct sg_io_hdr *hdr, fmode_t mode)
 
 	ret = scsi_complete_sghdr_rq(rq, hdr, bio);
 
-out_free_cdb:
-	scsi_req_free_cmd(req);
 out_put_request:
 	blk_mq_free_request(rq);
 	return ret;
@@ -530,6 +525,7 @@ static int sg_scsi_ioctl(struct request_queue *q, fmode_t mode,
 	struct scsi_request *req;
 	int err;
 	unsigned int in_len, out_len, bytes, opcode, cmdlen;
+	struct scsi_cmnd *scmd;
 	char *buffer = NULL;
 
 	if (!sic)
@@ -561,22 +557,23 @@ static int sg_scsi_ioctl(struct request_queue *q, fmode_t mode,
 		goto error_free_buffer;
 	}
 	req = scsi_req(rq);
+	scmd = blk_mq_rq_to_pdu(rq);
 
 	cmdlen = COMMAND_SIZE(opcode);
 
 	/*
 	 * get command and data to send to device, if any
 	 */
 	err = -EFAULT;
-	req->cmd_len = cmdlen;
-	if (copy_from_user(req->cmd, sic->data, cmdlen))
+	scmd->cmd_len = cmdlen;
+	if (copy_from_user(scmd->cmnd, sic->data, cmdlen))
 		goto error;
 
 	if (in_len && copy_from_user(buffer, sic->data + cmdlen, in_len))
 		goto error;
 
 	err = -EPERM;
-	if (!scsi_cmd_allowed(req->cmd, mode))
+	if (!scsi_cmd_allowed(scmd->cmnd, mode))
 		goto error;
 
 	/* default.  possible overridden later */

drivers/scsi/scsi_lib.c

@@ -214,6 +214,7 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 {
 	struct request *req;
 	struct scsi_request *rq;
+	struct scsi_cmnd *scmd;
 	int ret;
 
 	req = scsi_alloc_request(sdev->request_queue,
@@ -231,8 +232,9 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 		if (ret)
 			goto out;
 	}
-	rq->cmd_len = COMMAND_SIZE(cmd[0]);
-	memcpy(rq->cmd, cmd, rq->cmd_len);
+	scmd = blk_mq_rq_to_pdu(req);
+	scmd->cmd_len = COMMAND_SIZE(cmd[0]);
+	memcpy(scmd->cmnd, cmd, scmd->cmd_len);
 	rq->retries = retries;
 	req->timeout = timeout;
 	req->cmd_flags |= flags;
@@ -1126,9 +1128,9 @@ static void scsi_initialize_rq(struct request *rq)
 	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
 	struct scsi_request *req = &cmd->req;
 
-	memset(req->__cmd, 0, sizeof(req->__cmd));
-	req->cmd = req->__cmd;
-	req->cmd_len = BLK_MAX_CDB;
+	memset(cmd->cmnd, 0, sizeof(cmd->cmnd));
+	cmd->cmd_len = MAX_COMMAND_SIZE;
+
 	req->sense_len = 0;
 
 	init_rcu_head(&cmd->rcu);
@@ -1196,8 +1198,6 @@ static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev,
 		memset(&cmd->sdb, 0, sizeof(cmd->sdb));
 	}
 
-	cmd->cmd_len = scsi_req(req)->cmd_len;
-	cmd->cmnd = scsi_req(req)->cmd;
 	cmd->transfersize = blk_rq_bytes(req);
 	cmd->allowed = scsi_req(req)->retries;
 	return BLK_STS_OK;
@@ -1567,8 +1567,6 @@ static blk_status_t scsi_prepare_cmd(struct request *req)
 	cmd->prot_type = 0;
 	cmd->prot_flags = 0;
 	cmd->submitter = 0;
-	cmd->cmd_len = 0;
-	cmd->cmnd = NULL;
 	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
 	cmd->underflow = 0;
 	cmd->transfersize = 0;
@@ -1616,8 +1614,7 @@ static blk_status_t scsi_prepare_cmd(struct request *req)
 			return ret;
 	}
 
-	cmd->cmnd = scsi_req(req)->cmd = scsi_req(req)->__cmd;
-	memset(cmd->cmnd, 0, BLK_MAX_CDB);
+	memset(cmd->cmnd, 0, sizeof(cmd->cmnd));
 	return scsi_cmd_to_driver(cmd)->init_command(cmd);
 }
 

drivers/scsi/scsi_logging.c

@@ -87,7 +87,7 @@ void scmd_printk(const char *level, const struct scsi_cmnd *scmd,
 	char *logbuf;
 	size_t off = 0, logbuf_len;
 
-	if (!scmd || !scmd->cmnd)
+	if (!scmd)
 		return;
 
 	logbuf = scsi_log_reserve_buffer(&logbuf_len);
@@ -183,9 +183,6 @@ void scsi_print_command(struct scsi_cmnd *cmd)
 	char *logbuf;
 	size_t off, logbuf_len;
 
-	if (!cmd->cmnd)
-		return;
-
 	logbuf = scsi_log_reserve_buffer(&logbuf_len);
 	if (!logbuf)
 		return;