3 files changed, 17 insertions, 10 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 65ab5145a09b..3f47e522a1ec 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -5,6 +5,7 @@
 #include <linux/list.h>
 #include <linux/types.h>
 #include <linux/timer.h>
+#include <linux/scatterlist.h>
 
 struct request;
 struct scatterlist;
@@ -68,7 +69,7 @@ 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 */
@@ -128,7 +129,7 @@ extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
 extern void scsi_kunmap_atomic_sg(void *virt);
 
 extern struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);
-extern void scsi_free_sgtable(struct scatterlist *, int);
+extern void scsi_free_sgtable(struct scsi_cmnd *);
 
 extern int scsi_dma_map(struct scsi_cmnd *cmd);
 extern void scsi_dma_unmap(struct scsi_cmnd *cmd);
@@ -148,6 +149,6 @@ static inline int scsi_get_resid(struct scsi_cmnd *cmd)
 }
 
 #define scsi_for_each_sg(cmd, sg, nseg, __i)                    \
-        for (__i = 0, sg = scsi_sglist(cmd); __i < (nseg); __i++, (sg)++)
+        for_each_sg(scsi_sglist(cmd), sg, nseg, __i)
 
 #endif /* _SCSI_SCSI_CMND_H */
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 7d210cd6c38d..0fd4746ee39d 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -39,6 +39,9 @@ struct blk_queue_tags;
 #define DISABLE_CLUSTERING 0
 #define ENABLE_CLUSTERING 1
 
+#define DISABLE_SG_CHAINING 0
+#define ENABLE_SG_CHAINING 1
+
 enum scsi_eh_timer_return {
         EH_NOT_HANDLED,
         EH_HANDLED,
@@ -443,6 +446,15 @@ struct scsi_host_template {
         unsigned ordered_tag:1;
 
         /*
+         * true if the low-level driver can support sg chaining. this
+         * will be removed eventually when all the drivers are
+         * converted to support sg chaining.
+         *
+         * Status: OBSOLETE
+         */
+        unsigned use_sg_chaining:1;
+
+        /*
          * Countdown for host blocking with no commands outstanding
          */
         unsigned int max_host_blocked;
@@ -586,6 +598,7 @@ struct Scsi_Host {
         unsigned unchecked_isa_dma:1;
         unsigned use_clustering:1;
         unsigned use_blk_tcq:1;
+        unsigned use_sg_chaining:1;
 
         /*
          * Host has requested that no further requests come through for the