nvmet_fc: add req_release to lldd api

With the advent of the opdone calls changing context, the lldd can no
longer assume that once the op->done call returns for RSP operations
that the request struct is no longer being accessed.

As such, revise the lldd api for a req_release callback that the
transport will call when the job is complete. This will also be used
with abort cases.

Fixed text in api header for change in io complete semantics.

Revised lpfc to support the new req_release api.

Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

1 files changed, 35 insertions, 22 deletions

diff --git a/include/linux/nvme-fc-driver.h b/include/linux/nvme-fc-driver.h
index d70a9c98bc23..d98ddb2feabc 100644
--- a/include/linux/nvme-fc-driver.h
+++ b/include/linux/nvme-fc-driver.h
@@ -741,12 +741,12 @@ struct nvmet_fc_target_port {
  *       be freed/released.
  *       Entrypoint is Mandatory.
  *
- * @fcp_op:  Called to perform a data transfer, transmit a response, or
- *       abort an FCP opertion. The nvmefc_tgt_fcp_req structure is the same
- *       LLDD-supplied exchange structure specified in the
- *       nvmet_fc_rcv_fcp_req() call made when the FCP CMD IU was received.
- *       The op field in the structure shall indicate the operation for
- *       the LLDD to perform relative to the io.
+ * @fcp_op:  Called to perform a data transfer or transmit a response.
+ *       The nvmefc_tgt_fcp_req structure is the same LLDD-supplied
+ *       exchange structure specified in the nvmet_fc_rcv_fcp_req() call
+ *       made when the FCP CMD IU was received. The op field in the
+ *       structure shall indicate the operation for the LLDD to perform
+ *       relative to the io.
  *         NVMET_FCOP_READDATA operation: the LLDD is to send the
  *           payload data (described by sglist) to the host in 1 or
  *           more FC sequences (preferrably 1).  Note: the fc-nvme layer
@@ -768,29 +768,35 @@ struct nvmet_fc_target_port {
  *           successfully, the LLDD is to update the nvmefc_tgt_fcp_req
  *           transferred_length field and may subsequently transmit the
  *           FCP_RSP iu payload (described by rspbuf, rspdma, rsplen).
- *           The LLDD is to await FCP_CONF reception to confirm the RSP
- *           reception by the host. The LLDD may retramsit the FCP_RSP iu
- *           if necessary per FC-NVME. Upon reception of FCP_CONF, or upon
- *           FCP_CONF failure, the LLDD is to set the nvmefc_tgt_fcp_req
- *           fcp_error field and consider the operation complete..
+ *           If FCP_CONF is supported, the LLDD is to await FCP_CONF
+ *           reception to confirm the RSP reception by the host. The LLDD
+ *           may retramsit the FCP_RSP iu if necessary per FC-NVME. Upon
+ *           transmission of the FCP_RSP iu if FCP_CONF is not supported,
+ *           or upon success/failure of FCP_CONF if it is supported, the
+ *           LLDD is to set the nvmefc_tgt_fcp_req fcp_error field and
+ *           consider the operation complete.
  *         NVMET_FCOP_RSP: the LLDD is to transmit the FCP_RSP iu payload
- *           (described by rspbuf, rspdma, rsplen).  The LLDD is to await
- *           FCP_CONF reception to confirm the RSP reception by the host.
- *           The LLDD may retramsit the FCP_RSP iu if necessary per FC-NVME.
- *           Upon reception of FCP_CONF, or upon FCP_CONF failure, the
+ *           (described by rspbuf, rspdma, rsplen). If FCP_CONF is
+ *           supported, the LLDD is to await FCP_CONF reception to confirm
+ *           the RSP reception by the host. The LLDD may retramsit the
+ *           FCP_RSP iu if FCP_CONF is not received per FC-NVME. Upon
+ *           transmission of the FCP_RSP iu if FCP_CONF is not supported,
+ *           or upon success/failure of FCP_CONF if it is supported, the
  *           LLDD is to set the nvmefc_tgt_fcp_req fcp_error field and
- *           consider the operation complete..
+ *           consider the operation complete.
  *         NVMET_FCOP_ABORT: the LLDD is to terminate the exchange
  *           corresponding to the fcp operation. The LLDD shall send
  *           ABTS and follow FC exchange abort-multi rules, including
  *           ABTS retries and possible logout.
  *       Upon completing the indicated operation, the LLDD is to set the
  *       status fields for the operation (tranferred_length and fcp_error
- *       status) in the request, then all the "done" routine
- *       indicated in the fcp request.  Upon return from the "done"
- *       routine for either a NVMET_FCOP_RSP or NVMET_FCOP_ABORT operation
- *       the fc-nvme layer will not longer reference the fcp request,
- *       allowing the LLDD to free/release the fcp request.
+ *       status) in the request, then call the "done" routine
+ *       indicated in the fcp request. After the operation completes,
+ *       regardless of whether the FCP_RSP iu was successfully transmit,
+ *       the LLDD-supplied exchange structure must remain valid until the
+ *       transport calls the fcp_req_release() callback to return ownership
+ *       of the exchange structure back to the LLDD so that it may be used
+ *       for another fcp command.
  *       Note: when calling the done routine for READDATA or WRITEDATA
  *       operations, the fc-nvme layer may immediate convert, in the same
  *       thread and before returning to the LLDD, the fcp operation to
@@ -802,6 +808,11 @@ struct nvmet_fc_target_port {
  *       Returns 0 on success, -<errno> on failure (Ex: -EIO)
  *       Entrypoint is Mandatory.
  *
+ * @fcp_req_release:  Called by the transport to return a nvmefc_tgt_fcp_req
+ *       to the LLDD after all operations on the fcp operation are complete.
+ *       This may be due to the command completing or upon completion of
+ *       abort cleanup.
+ *
  * @max_hw_queues:  indicates the maximum number of hw queues the LLDD
  *       supports for cpu affinitization.
  *       Value is Mandatory. Must be at least 1.
@@ -836,7 +847,9 @@ struct nvmet_fc_target_template {
 	int (*xmt_ls_rsp)(struct nvmet_fc_target_port *tgtport,
 				struct nvmefc_tgt_ls_req *tls_req);
 	int (*fcp_op)(struct nvmet_fc_target_port *tgtport,
-				struct nvmefc_tgt_fcp_req *);
+				struct nvmefc_tgt_fcp_req *fcpreq);
+	void (*fcp_req_release)(struct nvmet_fc_target_port *tgtport,
+				struct nvmefc_tgt_fcp_req *fcpreq);
 
 	u32	max_hw_queues;
 	u16	max_sgl_segments;