target: Add target_submit_cmd_map_sgls for SGL fabric memory passthrough
This patch adds a new target_submit_cmd_map_sgls() to pass pre-allocated
SGL memory using transport_generic_map_mem_to_cmd() logic into the generic
target submit I/O codepath.
It also adds a target_submit_cmd() wrapper around target_submit_cmd_map_sgls()
for existing fabric code that already assumes internal target-core SGL memory
allocation.
(v2: Rename to target_submit_cmd_map_sgls + drop TARGET_SCF_MAP_MEM flag
in favor of non zero sgl_count check)
Reported-by: Christoph Hellwig <hch@lst.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 221f67f..d96d9aa 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1455,8 +1455,9 @@
}
EXPORT_SYMBOL(transport_handle_cdb_direct);
-/**
- * target_submit_cmd - lookup unpacked lun and submit uninitialized se_cmd
+/*
+ * target_submit_cmd_map_sgls - lookup unpacked lun and submit uninitialized
+ * se_cmd + use pre-allocated SGL memory.
*
* @se_cmd: command descriptor to submit
* @se_sess: associated se_sess for endpoint
@@ -1467,6 +1468,10 @@
* @task_addr: SAM task attribute
* @data_dir: DMA data direction
* @flags: flags for command submission from target_sc_flags_tables
+ * @sgl: struct scatterlist memory for unidirectional mapping
+ * @sgl_count: scatterlist count for unidirectional mapping
+ * @sgl_bidi: struct scatterlist memory for bidirectional READ mapping
+ * @sgl_bidi_count: scatterlist count for bidirectional READ mapping
*
* Returns non zero to signal active I/O shutdown failure. All other
* setup exceptions will be returned as a SCSI CHECK_CONDITION response,
@@ -1474,10 +1479,12 @@
*
* This may only be called from process context, and also currently
* assumes internal allocation of fabric payload buffer by target-core.
- **/
-int target_submit_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
+ */
+int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess,
unsigned char *cdb, unsigned char *sense, u32 unpacked_lun,
- u32 data_length, int task_attr, int data_dir, int flags)
+ u32 data_length, int task_attr, int data_dir, int flags,
+ struct scatterlist *sgl, u32 sgl_count,
+ struct scatterlist *sgl_bidi, u32 sgl_bidi_count)
{
struct se_portal_group *se_tpg;
int rc;
@@ -1524,7 +1531,21 @@
transport_generic_request_failure(se_cmd);
return 0;
}
+ /*
+ * When a non zero sgl_count has been passed perform SGL passthrough
+ * mapping for pre-allocated fabric memory instead of having target
+ * core perform an internal SGL allocation..
+ */
+ if (sgl_count != 0) {
+ BUG_ON(!sgl);
+ rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,
+ sgl_bidi, sgl_bidi_count);
+ if (rc != 0) {
+ transport_generic_request_failure(se_cmd);
+ return 0;
+ }
+ }
/*
* Check if we need to delay processing because of ALUA
* Active/NonOptimized primary access state..
@@ -1534,6 +1555,38 @@
transport_handle_cdb_direct(se_cmd);
return 0;
}
+EXPORT_SYMBOL(target_submit_cmd_map_sgls);
+
+/*
+ * target_submit_cmd - lookup unpacked lun and submit uninitialized se_cmd
+ *
+ * @se_cmd: command descriptor to submit
+ * @se_sess: associated se_sess for endpoint
+ * @cdb: pointer to SCSI CDB
+ * @sense: pointer to SCSI sense buffer
+ * @unpacked_lun: unpacked LUN to reference for struct se_lun
+ * @data_length: fabric expected data transfer length
+ * @task_addr: SAM task attribute
+ * @data_dir: DMA data direction
+ * @flags: flags for command submission from target_sc_flags_tables
+ *
+ * Returns non zero to signal active I/O shutdown failure. All other
+ * setup exceptions will be returned as a SCSI CHECK_CONDITION response,
+ * but still return zero here.
+ *
+ * This may only be called from process context, and also currently
+ * assumes internal allocation of fabric payload buffer by target-core.
+ *
+ * It also assumes interal target core SGL memory allocation.
+ */
+int target_submit_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
+ unsigned char *cdb, unsigned char *sense, u32 unpacked_lun,
+ u32 data_length, int task_attr, int data_dir, int flags)
+{
+ return target_submit_cmd_map_sgls(se_cmd, se_sess, cdb, sense,
+ unpacked_lun, data_length, task_attr, data_dir,
+ flags, NULL, 0, NULL, 0);
+}
EXPORT_SYMBOL(target_submit_cmd);
static void target_complete_tmr_failure(struct work_struct *work)