[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, 2 insertions, 2 deletions

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 0fd4746ee39d..cb2bcab41dfb 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -136,9 +136,9 @@ struct scsi_host_template {
 	 * the done callback is invoked.
 	 *
 	 * This is called to inform the LLD to transfer
-	 * cmd->request_bufflen bytes. The cmd->use_sg speciefies the
+	 * scsi_bufflen(cmd) bytes. scsi_sg_count(cmd) speciefies the
 	 * number of scatterlist entried in the command and
-	 * cmd->request_buffer contains the scatterlist.
+	 * scsi_sglist(cmd) returns the scatterlist.
 	 *
 	 * return values: see queuecommand
 	 *