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 --- drivers/scsi/scsi_bsg.c | 173 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 172 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/scsi_bsg.c b/drivers/scsi/scsi_bsg.c index 4d57e524e141..da227fa890e0 100644 --- a/drivers/scsi/scsi_bsg.c +++ b/drivers/scsi/scsi_bsg.c @@ -10,10 +10,181 @@ #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 */ +}; + +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: build res2 (layout in uapi/linux/bsg.h) and copy sense to user. */ +static void scsi_bsg_uring_task_cb(struct io_tw_req tw_req, io_tw_token_t tw) +{ + struct scsi_bsg_uring_cmd_pdu *pdu; + struct io_uring_cmd *ioucmd = io_uring_cmd_from_tw(tw_req); + struct scsi_cmnd *scmd; + struct request *rq; + u64 res2; + int ret = 0; + u8 driver_status = 0; + u8 sense_len_wr = 0; + + pdu = scsi_bsg_uring_cmd_pdu(ioucmd); + rq = pdu->req; + scmd = blk_mq_rq_to_pdu(rq); + + if (pdu->bio) + blk_rq_unmap_user(pdu->bio); + + if (scsi_status_is_check_condition(scmd->result)) { + driver_status = DRIVER_SENSE; + if (pdu->response_addr) + sense_len_wr = min_t(u8, scmd->sense_len, + SCSI_SENSE_BUFFERSIZE); + } + + if (sense_len_wr) { + if (copy_to_user(uptr64(pdu->response_addr), scmd->sense_buffer, + sense_len_wr)) + ret = -EFAULT; + } + + res2 = BSG_SCSI_RES2_BUILD(status_byte(scmd->result), driver_status, + host_byte(scmd->result), sense_len_wr, + scmd->resid_len); + + 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; + + 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; + unsigned long buf_len; + bool is_write = cmd->dout_xfer_len > 0; + u64 buf_addr = is_write ? cmd->dout_xferp : cmd->din_xferp; + int ret; + + buf_len = is_write ? cmd->dout_xfer_len : cmd->din_xfer_len; + + 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; + blk_mq_req_flags_t blk_flags = 0; + struct request *req; + 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