SCSI: support for allocating large scatterlists

This is what enables large commands. If we need to allocate an
sgtable that doesn't fit in a single page, allocate several
SCSI_MAX_SG_SEGMENTS sized tables and chain them together.

SCSI defaults to large chained sg tables, if the arch supports it.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 1 insertions, 7 deletions

diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 9f8f80ab0c8b..702fcfeb37f1 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -11,13 +11,6 @@
 #include <linux/types.h>
 
 /*
- *      The maximum sg list length SCSI can cope with
- *      (currently must be a power of 2 between 32 and 256)
- */
-#define SCSI_MAX_PHYS_SEGMENTS  MAX_PHYS_SEGMENTS
-
-
-/*
  *      SCSI command lengths
  */
 
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index a5439a4b8f97..4a5fa2d1c44c 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -70,6 +70,7 @@ struct scsi_cmnd {
         /* These elements define the operation we ultimately want to perform */
         unsigned short use_sg;  /* Number of pieces of scatter-gather */
         unsigned short sglist_len;      /* size of malloc'd scatter-gather list */
+        unsigned short __use_sg;
 
         unsigned underflow;     /* Return error if less than
                                    this amount is transferred */