[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;