target: Updates from AGrover and HCH (round 3)

This patch contains a squashed version of third round series cleanups,
improvements ,and simplfications from Andy and Christoph ahead of the
heavy lifting between round 3 -> 4 for the target core SGL conversion.

This include cleanups to the main target I/O path and other miscellaneous
updates.

target: Replace custom sg<->buf functions with lib funcs
target: Simplify sector limiting code
target: get_cdb should never return NULL
target: Simplify transport_memcpy_se_mem_read_contig
target: Use assignment rather than increment for t_task_cdbs
target: Don't pass dma_size to generic_get_mem
target: Pass sg with type scatterlist in transport_map_sg_to_mem
target: Move task_sg_num next to task_sg in struct se_task
target: inline struct se_transport_task into struct se_cmd
target: Change name & semantics of transport_get_sectors()
target: Remove unused members of se_cmd
target: Rename se_cmd.t_task_cdbs to t_task_list_num
target: Fix some spelling
target: Remove unused var from transport_generic_do_tmr
target: map_sg_to_mem: return sg_count in return value
target/pscsi: Use min_t for sector limits
target/pscsi: Unused param for pscsi_get_bio()
target: Rename get_cdb_count to allocate_tasks
target: Make transport_generic_new_cmd() available for iscsi-target
target: Remove fabric callback to allocate iovecs
target: Fix transport_generic_new_cmd WRITE comment

(hch: Use __GFP_ZERO usage for alloc_pages() usage)

Signed-off-by: Andy Grover <agrover@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

17 files changed, 583 insertions, 753 deletions

diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c
index eeb7ee7ab9f7..7ba2542aabe7 100644
--- a/drivers/target/loopback/tcm_loop.c
+++ b/drivers/target/loopback/tcm_loop.c
@@ -118,7 +118,7 @@ static struct se_cmd *tcm_loop_allocate_core_cmd(
          * Signal BIDI usage with T_TASK(cmd)->t_tasks_bidi
          */
         if (scsi_bidi_cmnd(sc))
-                se_cmd->t_task.t_tasks_bidi = 1;
+                se_cmd->t_tasks_bidi = 1;
         /*
          * Locate the struct se_lun pointer and attach it to struct se_cmd
          */
@@ -169,7 +169,7 @@ static int tcm_loop_new_cmd_map(struct se_cmd *se_cmd)
          * For BIDI commands, pass in the extra READ buffer
          * to transport_generic_map_mem_to_cmd() below..
          */
-        if (se_cmd->t_task.t_tasks_bidi) {
+        if (se_cmd->t_tasks_bidi) {
                 struct scsi_data_buffer *sdb = scsi_in(sc);
 
                 sgl_bidi = sdb->table.sgl;
@@ -1424,13 +1424,6 @@ static int tcm_loop_register_configfs(void)
                                         &tcm_loop_tpg_release_fabric_acl;
         fabric->tf_ops.tpg_get_inst_index = &tcm_loop_get_inst_index;
         /*
-         * Since tcm_loop is mapping physical memory from Linux/SCSI
-         * struct scatterlist arrays for each struct scsi_cmnd I/O,
-         * we do not need TCM to allocate a iovec array for
-         * virtual memory address mappings
-         */
-        fabric->tf_ops.alloc_cmd_iovecs = NULL;
-        /*
          * Used for setting up remaining TCM resources in process context
          */
         fabric->tf_ops.new_cmd_map = &tcm_loop_new_cmd_map;
diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c
index 76abd86b6a73..76d506fe99e0 100644
--- a/drivers/target/target_core_alua.c
+++ b/drivers/target/target_core_alua.c
@@ -65,7 +65,7 @@ int core_emulate_report_target_port_groups(struct se_cmd *cmd)
         struct se_port *port;
         struct t10_alua_tg_pt_gp *tg_pt_gp;
         struct t10_alua_tg_pt_gp_member *tg_pt_gp_mem;
-        unsigned char *buf = (unsigned char *)cmd->t_task.t_task_buf;
+        unsigned char *buf = (unsigned char *)cmd->t_task_buf;
         u32 rd_len = 0, off = 4; /* Skip over RESERVED area to first
                                     Target port group descriptor */
 
@@ -157,7 +157,7 @@ int core_emulate_set_target_port_groups(struct se_cmd *cmd)
         struct se_node_acl *nacl = cmd->se_sess->se_node_acl;
         struct t10_alua_tg_pt_gp *tg_pt_gp = NULL, *l_tg_pt_gp;
         struct t10_alua_tg_pt_gp_member *tg_pt_gp_mem, *l_tg_pt_gp_mem;
-        unsigned char *buf = (unsigned char *)cmd->t_task.t_task_buf;
+        unsigned char *buf = (unsigned char *)cmd->t_task_buf;
         unsigned char *ptr = &buf[4]; /* Skip over RESERVED area in header */
         u32 len = 4; /* Skip over RESERVED area in header */
         int alua_access_state, primary = 0, rc;
diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c
index 8d5a0fc3a220..09ef3f811567 100644
--- a/drivers/target/target_core_cdb.c
+++ b/drivers/target/target_core_cdb.c
@@ -66,7 +66,7 @@ target_emulate_inquiry_std(struct se_cmd *cmd)
 {
         struct se_lun *lun = cmd->se_lun;
         struct se_device *dev = cmd->se_dev;
-        unsigned char *buf = cmd->t_task.t_task_buf;
+        unsigned char *buf = cmd->t_task_buf;
 
         /*
          * Make sure we at least have 6 bytes of INQUIRY response
@@ -621,8 +621,8 @@ static int
 target_emulate_inquiry(struct se_cmd *cmd)
 {
         struct se_device *dev = cmd->se_dev;
-        unsigned char *buf = cmd->t_task.t_task_buf;
-        unsigned char *cdb = cmd->t_task.t_task_cdb;
+        unsigned char *buf = cmd->t_task_buf;
+        unsigned char *cdb = cmd->t_task_cdb;
 
         if (!(cdb[1] & 0x1))
                 return target_emulate_inquiry_std(cmd);
@@ -666,7 +666,7 @@ static int
 target_emulate_readcapacity(struct se_cmd *cmd)
 {
         struct se_device *dev = cmd->se_dev;
-        unsigned char *buf = cmd->t_task.t_task_buf;
+        unsigned char *buf = cmd->t_task_buf;
         unsigned long long blocks_long = dev->transport->get_blocks(dev);
         u32 blocks;
 
@@ -696,7 +696,7 @@ static int
 target_emulate_readcapacity_16(struct se_cmd *cmd)
 {
         struct se_device *dev = cmd->se_dev;
-        unsigned char *buf = cmd->t_task.t_task_buf;
+        unsigned char *buf = cmd->t_task_buf;
         unsigned long long blocks = dev->transport->get_blocks(dev);
 
         buf[0] = (blocks >> 56) & 0xff;
@@ -831,8 +831,8 @@ static int
 target_emulate_modesense(struct se_cmd *cmd, int ten)
 {
         struct se_device *dev = cmd->se_dev;
-        char *cdb = cmd->t_task.t_task_cdb;
-        unsigned char *rbuf = cmd->t_task.t_task_buf;
+        char *cdb = cmd->t_task_cdb;
+        unsigned char *rbuf = cmd->t_task_buf;
         int type = dev->transport->get_device_type(dev);
         int offset = (ten) ? 8 : 4;
         int length = 0;
@@ -903,8 +903,8 @@ target_emulate_modesense(struct se_cmd *cmd, int ten)
 static int
 target_emulate_request_sense(struct se_cmd *cmd)
 {
-        unsigned char *cdb = cmd->t_task.t_task_cdb;
-        unsigned char *buf = cmd->t_task.t_task_buf;
+        unsigned char *cdb = cmd->t_task_cdb;
+        unsigned char *buf = cmd->t_task_buf;
         u8 ua_asc = 0, ua_ascq = 0;
 
         if (cdb[1] & 0x01) {
@@ -965,8 +965,8 @@ target_emulate_unmap(struct se_task *task)
 {
         struct se_cmd *cmd = task->task_se_cmd;
         struct se_device *dev = cmd->se_dev;
-        unsigned char *buf = cmd->t_task.t_task_buf, *ptr = NULL;
-        unsigned char *cdb = &cmd->t_task.t_task_cdb[0];
+        unsigned char *buf = cmd->t_task_buf, *ptr = NULL;
+        unsigned char *cdb = &cmd->t_task_cdb[0];
         sector_t lba;
         unsigned int size = cmd->data_length, range;