[SCSI] libfc: add support of large receive offload by ddp in fc_fcp
When LLD supports direct data placement (ddp) for large receive of an scsi
i/o coming into fc_fcp, we call into libfc_function_template's ddp_setup()
to prepare for a ddp of large receive for this read I/O. When I/O is complete,
we call the corresponding ddp_done() to get the length of data ddped as well
as to let LLD do clean up.
fc_fcp_ddp_setup()/fc_fcp_ddp_done() are added to setup and complete a ddped
read I/O described by the given fc_fcp_pkt. They would call into corresponding
ddp_setup/ddp_done implemented by the fcoe layer. Eventually, fcoe layer calls
into LLD's ddp_setup/ddp_done provided through net_device
Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/include/scsi/libfc.h b/include/scsi/libfc.h
index 61c746c..a70eafa 100644
--- a/include/scsi/libfc.h
+++ b/include/scsi/libfc.h
@@ -245,6 +245,7 @@
*/
struct fcp_cmnd cdb_cmd;
size_t xfer_len;
+ u16 xfer_ddp; /* this xfer is ddped */
u32 xfer_contig_end; /* offset of end of contiguous xfer */
u16 max_payload; /* max payload size in bytes */
@@ -267,6 +268,15 @@
u8 recov_retry; /* count of recovery retries */
struct fc_seq *recov_seq; /* sequence for REC or SRR */
};
+/*
+ * FC_FCP HELPER FUNCTIONS
+ *****************************/
+static inline bool fc_fcp_is_read(const struct fc_fcp_pkt *fsp)
+{
+ if (fsp && fsp->cmd)
+ return fsp->cmd->sc_data_direction == DMA_FROM_DEVICE;
+ return false;
+}
/*
* Structure and function definitions for managing Fibre Channel Exchanges
@@ -400,6 +410,21 @@
void *arg, unsigned int timer_msec);
/*
+ * Sets up the DDP context for a given exchange id on the given
+ * scatterlist if LLD supports DDP for large receive.
+ *
+ * STATUS: OPTIONAL
+ */
+ int (*ddp_setup)(struct fc_lport *lp, u16 xid,
+ struct scatterlist *sgl, unsigned int sgc);
+ /*
+ * Completes the DDP transfer and returns the length of data DDPed
+ * for the given exchange id.
+ *
+ * STATUS: OPTIONAL
+ */
+ int (*ddp_done)(struct fc_lport *lp, u16 xid);
+ /*
* Send a frame using an existing sequence and exchange.
*
* STATUS: OPTIONAL
@@ -822,6 +847,11 @@
void fc_fcp_destroy(struct fc_lport *);
/*
+ * Set up direct-data placement for this I/O request
+ */
+void fc_fcp_ddp_setup(struct fc_fcp_pkt *fsp, u16 xid);
+
+/*
* ELS/CT interface
*****************************/
/*
