target: Eliminate usage of struct se_mem

Both backstores and fabrics use arrays of struct scatterlist to describe
data buffers. However TCM used struct se_mems, basically a linked list
of scatterlist entries. We are able to simplify the code by eliminating
this intermediate data structure and just using struct scatterlist[]
throughout.

Also, moved attachment of task to cmd out of transport_generic_get_task
and into allocate_control_task and allocate_data_tasks. The reasoning
is that it's nonintuitive that get_task should automatically add it to
the cmd's task list -- it should just return an allocated, initialized
task. That's all it should do, based on the function's name, so either the
function shouldn't do it, or the name should change to encapsulate the
entire essence of what it does.

(nab: Fix compile warnings in tcm_fc, and make transport_kmap_first_data_page
 honor sg->offset for SGLs from contigious memory with TCM_Loop, and
 fix control se_cmd descriptor memory leak)

Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 13 insertions, 12 deletions

diff --git a/drivers/target/tcm_fc/tfc_cmd.c b/drivers/target/tcm_fc/tfc_cmd.c
index 1017f56bbbc..9365e53947a 100644
--- a/drivers/target/tcm_fc/tfc_cmd.c
+++ b/drivers/target/tcm_fc/tfc_cmd.c
@@ -59,7 +59,8 @@ void ft_dump_cmd(struct ft_cmd *cmd, const char *caller)
 	struct fc_exch *ep;
 	struct fc_seq *sp;
 	struct se_cmd *se_cmd;
-	struct se_mem *mem;
+	struct scatterlist *sg;
+	int count;
 
 	if (!(ft_debug_logging & FT_DEBUG_IO))
 		return;
@@ -71,15 +72,16 @@ void ft_dump_cmd(struct ft_cmd *cmd, const char *caller)
 		caller, cmd, cmd->cdb);
 	printk(KERN_INFO "%s: cmd %p lun %d\n", caller, cmd, cmd->lun);
 
-	printk(KERN_INFO "%s: cmd %p se_num %u len %u se_cmd_flags <0x%x>\n",
-	       caller, cmd, se_cmd->t_tasks_se_num,
+	printk(KERN_INFO "%s: cmd %p data_nents %u len %u se_cmd_flags <0x%x>\n",
+		caller, cmd, se_cmd->t_data_nents,
 	       se_cmd->data_length, se_cmd->se_cmd_flags);
 
-	list_for_each_entry(mem, &se_cmd->t_mem_list, se_list)
-		printk(KERN_INFO "%s: cmd %p mem %p page %p "
-		       "len 0x%x off 0x%x\n",
-		       caller, cmd, mem,
-		       mem->se_page, mem->se_len, mem->se_off);
+	for_each_sg(se_cmd->t_data_sg, sg, se_cmd->t_data_nents, count)
+		printk(KERN_INFO "%s: cmd %p sg %p page %p "
+			"len 0x%x off 0x%x\n",
+			caller, cmd, sg,
+			sg_page(sg), sg->length, sg->offset);
+
 	sp = cmd->seq;
 	if (sp) {
 		ep = fc_seq_exch(sp);
@@ -256,10 +258,9 @@ int ft_write_pending(struct se_cmd *se_cmd)
 		    (fh->fh_r_ctl == FC_RCTL_DD_DATA_DESC)) {
 			if (se_cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB) {
 				/*
-				 * Map se_mem list to scatterlist, so that
-				 * DDP can be setup. DDP setup function require
-				 * scatterlist. se_mem_list is internal to
-				 * TCM/LIO target
+				 * cmd may have been broken up into multiple
+				 * tasks. Link their sgs together so we can
+				 * operate on them all at once.
 				 */
 				transport_do_task_sg_chain(se_cmd);
 				cmd->sg = se_cmd->t_tasks_sg_chained;