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>

3 files changed, 49 insertions, 64 deletions

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 94c838dcfc3c..71c96ce9287e 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -403,64 +403,10 @@ struct se_queue_obj {
         wait_queue_head_t       thread_wq;
 } ____cacheline_aligned;
 
-/*
- * Used one per struct se_cmd to hold all extra struct se_task
- * metadata.  This structure is setup and allocated in
- * drivers/target/target_core_transport.c:__transport_alloc_se_cmd()
- */
-struct se_transport_task {
-        unsigned char           *t_task_cdb;
-        unsigned char           __t_task_cdb[TCM_MAX_COMMAND_SIZE];
-        unsigned long long      t_task_lba;
-        int                     t_tasks_failed;
-        int                     t_tasks_fua;
-        bool                    t_tasks_bidi;
-        u32                     t_task_cdbs;
-        u32                     t_tasks_check;
-        u32                     t_tasks_no;
-        u32                     t_tasks_sectors;
-        u32                     t_tasks_se_num;
-        u32                     t_tasks_se_bidi_num;
-        u32                     t_tasks_sg_chained_no;
-        atomic_t                t_fe_count;
-        atomic_t                t_se_count;
-        atomic_t                t_task_cdbs_left;
-        atomic_t                t_task_cdbs_ex_left;
-        atomic_t                t_task_cdbs_timeout_left;
-        atomic_t                t_task_cdbs_sent;
-        atomic_t                t_transport_aborted;
-        atomic_t                t_transport_active;
-        atomic_t                t_transport_complete;
-        atomic_t                t_transport_queue_active;
-        atomic_t                t_transport_sent;
-        atomic_t                t_transport_stop;
-        atomic_t                t_transport_timeout;
-        atomic_t                transport_dev_active;
-        atomic_t                transport_lun_active;
-        atomic_t                transport_lun_fe_stop;
-        atomic_t                transport_lun_stop;
-        spinlock_t              t_state_lock;
-        struct completion       t_transport_stop_comp;
-        struct completion       transport_lun_fe_stop_comp;
-        struct completion       transport_lun_stop_comp;
-        struct scatterlist      *t_tasks_sg_chained;
-        struct scatterlist      t_tasks_sg_bounce;
-        void                    *t_task_buf;
-        /*
-         * Used for pre-registered fabric SGL passthrough WRITE and READ
-         * with the special SCF_PASSTHROUGH_CONTIG_TO_SG case for TCM_Loop
-         * and other HW target mode fabric modules.
-         */
-        struct scatterlist      *t_task_pt_sgl;
-        struct list_head        t_mem_list;
-        /* Used for BIDI READ */
-        struct list_head        t_mem_bidi_list;
-        struct list_head        t_task_list;
-} ____cacheline_aligned;
-
 struct se_task {
         unsigned char   task_sense;
         struct scatterlist *task_sg;
+        u32             task_sg_num;
         struct scatterlist *task_sg_bidi;
         u8              task_scsi_status;
         u8              task_flags;
@@ -471,8 +417,6 @@ struct se_task {
         u32             task_no;
         u32             task_sectors;
         u32             task_size;
-        u32             task_sg_num;
-        u32             task_sg_offset;
         enum dma_data_direction task_data_direction;
         struct se_cmd *task_se_cmd;
         struct se_device        *se_dev;
@@ -534,13 +478,58 @@ struct se_cmd {
         /* Only used for internal passthrough and legacy TCM fabric modules */
         struct se_session       *se_sess;
         struct se_tmr_req       *se_tmr_req;
-        struct se_transport_task t_task;
         struct list_head        se_queue_node;
         struct target_core_fabric_ops *se_tfo;
         int (*transport_emulate_cdb)(struct se_cmd *);
         void (*transport_split_cdb)(unsigned long long, u32 *, unsigned char *);
         void (*transport_wait_for_tasks)(struct se_cmd *, int, int);
         void (*transport_complete_callback)(struct se_cmd *);
+        unsigned char           *t_task_cdb;
+        unsigned char           __t_task_cdb[TCM_MAX_COMMAND_SIZE];
+        unsigned long long      t_task_lba;
+        int                     t_tasks_failed;
+        int                     t_tasks_fua;
+        bool                    t_tasks_bidi;
+        u32                     t_tasks_se_num;
+        u32                     t_tasks_se_bidi_num;
+        u32                     t_tasks_sg_chained_no;
+        atomic_t                t_fe_count;
+        atomic_t                t_se_count;
+        atomic_t                t_task_cdbs_left;
+        atomic_t                t_task_cdbs_ex_left;
+        atomic_t                t_task_cdbs_timeout_left;
+        atomic_t                t_task_cdbs_sent;
+        atomic_t                t_transport_aborted;
+        atomic_t                t_transport_active;
+        atomic_t                t_transport_complete;
+        atomic_t                t_transport_queue_active;
+        atomic_t                t_transport_sent;
+        atomic_t                t_transport_stop;
+        atomic_t                t_transport_timeout;
+        atomic_t                transport_dev_active;
+        atomic_t                transport_lun_active;
+        atomic_t                transport_lun_fe_stop;
+        atomic_t                transport_lun_stop;
+        spinlock_t              t_state_lock;
+        struct completion       t_transport_stop_comp;
+        struct completion       transport_lun_fe_stop_comp;
+        struct completion       transport_lun_stop_comp;
+        struct scatterlist      *t_tasks_sg_chained;
+        struct scatterlist      t_tasks_sg_bounce;
+        void                    *t_task_buf;
+        /*
+         * Used for pre-registered fabric SGL passthrough WRITE and READ
+         * with the special SCF_PASSTHROUGH_CONTIG_TO_SG case for TCM_Loop
+         * and other HW target mode fabric modules.
+         */
+        struct scatterlist      *t_task_pt_sgl;
+        u32                     t_task_pt_sgl_num;
+        struct list_head        t_mem_list;
+        /* Used for BIDI READ */
+        struct list_head        t_mem_bidi_list;
+        struct list_head        t_task_list;
+        u32                     t_task_list_num;
+
 } ____cacheline_aligned;
 
 struct se_tmr_req {
diff --git a/include/target/target_core_fabric_ops.h b/include/target/target_core_fabric_ops.h
index 747e1404dca0..1752ed3f77fa 100644
--- a/include/target/target_core_fabric_ops.h
+++ b/include/target/target_core_fabric_ops.h
@@ -39,11 +39,6 @@ struct target_core_fabric_ops {
          */
         int (*new_cmd_map)(struct se_cmd *);
         /*
-         * Optional function pointer for TCM fabric modules that use
-         * Linux/NET sockets to allocate struct iovec array to struct se_cmd
-         */
-        int (*alloc_cmd_iovecs)(struct se_cmd *);
-        /*
          * Optional to release struct se_cmd and fabric dependent allocated
          * I/O descriptor in transport_cmd_check_stop()
          */
diff --git a/include/target/target_core_transport.h b/include/target/target_core_transport.h
index acd591491767..c9846d521945 100644
--- a/include/target/target_core_transport.h
+++ b/include/target/target_core_transport.h
@@ -184,10 +184,11 @@ extern void transport_generic_free_cmd(struct se_cmd *, int, int, int);
 extern void transport_generic_wait_for_cmds(struct se_cmd *, int);
 extern int transport_init_task_sg(struct se_task *, struct se_mem *, u32);
 extern int transport_map_mem_to_sg(struct se_task *, struct list_head *,
-                                        void *, struct se_mem *,
+                                        struct scatterlist *, struct se_mem *,
                                         struct se_mem **, u32 *, u32 *);
 extern void transport_do_task_sg_chain(struct se_cmd *);
 extern void transport_generic_process_write(struct se_cmd *);
+extern int transport_generic_new_cmd(struct se_cmd *);
 extern int transport_generic_do_tmr(struct se_cmd *);
 /* From target_core_alua.c */
 extern int core_alua_check_nonop_delay(struct se_cmd *);