[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, 13 insertions, 12 deletions

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 1fcee16fa36d..50ba49250203 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -231,7 +231,7 @@ out:
 static int sr_done(struct scsi_cmnd *SCpnt)
 {
         int result = SCpnt->result;
-        int this_count = SCpnt->request_bufflen;
+        int this_count = scsi_bufflen(SCpnt);
         int good_bytes = (result == 0 ? this_count : 0);
         int block_sectors = 0;
         long error_sector;
@@ -379,17 +379,18 @@ static int sr_prep_fn(struct request_queue *q, struct request *rq)
         }
 
         {
-                struct scatterlist *sg = SCpnt->request_buffer;
-                int i, size = 0;
-                for (i = 0; i < SCpnt->use_sg; i++)
-                        size += sg[i].length;
+                struct scatterlist *sg;
+                int i, size = 0, sg_count = scsi_sg_count(SCpnt);
 
-                if (size != SCpnt->request_bufflen && SCpnt->use_sg) {
+                scsi_for_each_sg(SCpnt, sg, sg_count, i)
+                        size += sg->length;
+
+                if (size != scsi_bufflen(SCpnt)) {
                         scmd_printk(KERN_ERR, SCpnt,
                                 "mismatch count %d, bytes %d\n",
-                                size, SCpnt->request_bufflen);
-                        if (SCpnt->request_bufflen > size)
-                                SCpnt->request_bufflen = size;
+                                size, scsi_bufflen(SCpnt));
+                        if (scsi_bufflen(SCpnt) > size)
+                                SCpnt->sdb.length = size;
                 }
         }
 
@@ -397,12 +398,12 @@ static int sr_prep_fn(struct request_queue *q, struct request *rq)
          * request doesn't start on hw block boundary, add scatter pads
          */
         if (((unsigned int)rq->sector % (s_size >> 9)) ||
-            (SCpnt->request_bufflen % s_size)) {
+            (scsi_bufflen(SCpnt) % s_size)) {
                 scmd_printk(KERN_NOTICE, SCpnt, "unaligned transfer\n");
                 goto out;
         }
 
-        this_count = (SCpnt->request_bufflen >> 9) / (s_size >> 9);
+        this_count = (scsi_bufflen(SCpnt) >> 9) / (s_size >> 9);
 
 
         SCSI_LOG_HLQUEUE(2, printk("%s : %s %d/%ld 512 byte blocks.\n",
@@ -416,7 +417,7 @@ static int sr_prep_fn(struct request_queue *q, struct request *rq)
 
         if (this_count > 0xffff) {
                 this_count = 0xffff;
-                SCpnt->request_bufflen = this_count * s_size;
+                SCpnt->sdb.length = this_count * s_size;
         }
 
         SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;