[SCSI] implement scsi_data_buffer

In preparation for bidi we abstract all IO members of scsi_cmnd,
that will need to duplicate, into a substructure.

- Group all IO members of scsi_cmnd into a scsi_data_buffer
  structure.
- Adjust accessors to new members.
- scsi_{alloc,free}_sgtable receive a scsi_data_buffer instead of
  scsi_cmnd. And work on it.
- Adjust scsi_init_io() and  scsi_release_buffers() for above
  change.
- Fix other parts of scsi_lib/scsi.c to members migration. Use
  accessors where appropriate.

- fix Documentation about scsi_cmnd in scsi_host.h

- scsi_error.c
  * Changed needed members of struct scsi_eh_save.
  * Careful considerations in scsi_eh_prep/restore_cmnd.

- sd.c and sr.c
  * sd and sr would adjust IO size to align on device's block
    size so code needs to change once we move to scsi_data_buff
    implementation.
  * Convert code to use scsi_for_each_sg
  * Use data accessors where appropriate.

- tgt: convert libsrp to use scsi_data_buffer

- isd200: This driver still bangs on scsi_cmnd IO members,
  so need changing

[jejb: rebased on top of sg_table patches fixed up conflicts
and used the synergy to eliminate use_sg and sg_count]

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 11 insertions, 19 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 547e85aa414f..4f4edc388c07 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -617,29 +617,25 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
         ses->cmd_len = scmd->cmd_len;
         memcpy(ses->cmnd, scmd->cmnd, sizeof(scmd->cmnd));
         ses->data_direction = scmd->sc_data_direction;
-        ses->bufflen = scmd->request_bufflen;
-        ses->buffer = scmd->request_buffer;
-        ses->use_sg = scmd->use_sg;
-        ses->resid = scmd->resid;
+        ses->sdb = scmd->sdb;
         ses->result = scmd->result;
 
+        memset(&scmd->sdb, 0, sizeof(scmd->sdb));
+
         if (sense_bytes) {
-                scmd->request_bufflen = min_t(unsigned,
-                                       SCSI_SENSE_BUFFERSIZE, sense_bytes);
+                scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE,
+                                         sense_bytes);
                 sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
-                                                       scmd->request_bufflen);
-                scmd->request_buffer = &ses->sense_sgl;
+                            scmd->sdb.length);
+                scmd->sdb.table.sgl = &ses->sense_sgl;
                 scmd->sc_data_direction = DMA_FROM_DEVICE;
-                scmd->use_sg = 1;
+                scmd->sdb.table.nents = 1;
                 memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
                 scmd->cmnd[0] = REQUEST_SENSE;
-                scmd->cmnd[4] = scmd->request_bufflen;
+                scmd->cmnd[4] = scmd->sdb.length;
                 scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
         } else {
-                scmd->request_buffer = NULL;
-                scmd->request_bufflen = 0;
                 scmd->sc_data_direction = DMA_NONE;
-                scmd->use_sg = 0;
                 if (cmnd) {
                         memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
                         memcpy(scmd->cmnd, cmnd, cmnd_size);
@@ -676,10 +672,7 @@ void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
         scmd->cmd_len = ses->cmd_len;
         memcpy(scmd->cmnd, ses->cmnd, sizeof(scmd->cmnd));
         scmd->sc_data_direction = ses->data_direction;
-        scmd->request_bufflen = ses->bufflen;
-        scmd->request_buffer = ses->buffer;
-        scmd->use_sg = ses->use_sg;
-        scmd->resid = ses->resid;
+        scmd->sdb = ses->sdb;
         scmd->result = ses->result;
 }
 EXPORT_SYMBOL(scsi_eh_restore_cmnd);
@@ -1700,8 +1693,7 @@ scsi_reset_provider(struct scsi_device *dev, int flag)
         memset(&scmd->cmnd, '\0', sizeof(scmd->cmnd));
     
         scmd->scsi_done         = scsi_reset_provider_done_command;
-        scmd->request_buffer            = NULL;
-        scmd->request_bufflen           = 0;
+        memset(&scmd->sdb, 0, sizeof(scmd->sdb));
 
         scmd->cmd_len                   = 0;