4 files changed, 68 insertions, 37 deletions

diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 702fcfeb37f1..82251575a9b4 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -11,6 +11,25 @@
 #include <linux/types.h>
 
 /*
+ * The maximum number of SG segments that we will put inside a
+ * scatterlist (unless chaining is used). Should ideally fit inside a
+ * single page, to avoid a higher order allocation.  We could define this
+ * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order.  The
+ * minimum value is 32
+ */
+#define SCSI_MAX_SG_SEGMENTS    128
+
+/*
+ * Like SCSI_MAX_SG_SEGMENTS, but for archs that have sg chaining. This limit
+ * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
+ */
+#ifdef ARCH_HAS_SG_CHAIN
+#define SCSI_MAX_SG_CHAIN_SEGMENTS      2048
+#else
+#define SCSI_MAX_SG_CHAIN_SEGMENTS      SCSI_MAX_SG_SEGMENTS
+#endif
+
+/*
  *      SCSI command lengths
  */
 
@@ -83,6 +102,7 @@ extern const unsigned char scsi_command_size[8];
 #define READ_TOC              0x43
 #define LOG_SELECT            0x4c
 #define LOG_SENSE             0x4d
+#define XDWRITEREAD_10        0x53
 #define MODE_SELECT_10        0x55
 #define RESERVE_10            0x56
 #define RELEASE_10            0x57
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index a457fca66f61..de28aab820b0 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -2,15 +2,20 @@
 #define _SCSI_SCSI_CMND_H
 
 #include <linux/dma-mapping.h>
+#include <linux/blkdev.h>
 #include <linux/list.h>
 #include <linux/types.h>
 #include <linux/timer.h>
 #include <linux/scatterlist.h>
 
-struct request;
 struct Scsi_Host;
 struct scsi_device;
 
+struct scsi_data_buffer {
+        struct sg_table table;
+        unsigned length;
+        int resid;
+};
 
 /* embedded in scsi_cmnd */
 struct scsi_pointer {
@@ -61,15 +66,11 @@ struct scsi_cmnd {
         /* These elements define the operation we are about to perform */
 #define MAX_COMMAND_SIZE        16
         unsigned char cmnd[MAX_COMMAND_SIZE];
-        unsigned request_bufflen;       /* Actual request size */
 
         struct timer_list eh_timeout;   /* Used to time out the command. */
-        void *request_buffer;           /* Actual requested buffer */
 
         /* These elements define the operation we ultimately want to perform */
-        struct sg_table sg_table;
-        unsigned short use_sg;  /* Number of pieces of scatter-gather */
-
+        struct scsi_data_buffer sdb;
         unsigned underflow;     /* Return error if less than
                                    this amount is transferred */
 
@@ -79,10 +80,6 @@ struct scsi_cmnd {
                                    reconnects.   Probably == sector
                                    size */
 
-        int resid;              /* Number of bytes requested to be
-                                   transferred less actual number
-                                   transferred (0 if not supported) */
-
         struct request *request;        /* The command we are
                                            working on */
 
@@ -127,27 +124,55 @@ extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
                                  size_t *offset, size_t *len);
 extern void scsi_kunmap_atomic_sg(void *virt);
 
-extern int scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);
-extern void scsi_free_sgtable(struct scsi_cmnd *);
+extern int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask);
+extern void scsi_release_buffers(struct scsi_cmnd *cmd);
 
 extern int scsi_dma_map(struct scsi_cmnd *cmd);
 extern void scsi_dma_unmap(struct scsi_cmnd *cmd);
 
-#define scsi_sg_count(cmd) ((cmd)->use_sg)
-#define scsi_sglist(cmd) ((cmd)->sg_table.sgl)
-#define scsi_bufflen(cmd) ((cmd)->request_bufflen)
+static inline unsigned scsi_sg_count(struct scsi_cmnd *cmd)
+{
+        return cmd->sdb.table.nents;
+}
+
+static inline struct scatterlist *scsi_sglist(struct scsi_cmnd *cmd)
+{
+        return cmd->sdb.table.sgl;
+}
+
+static inline unsigned scsi_bufflen(struct scsi_cmnd *cmd)
+{
+        return cmd->sdb.length;
+}
 
 static inline void scsi_set_resid(struct scsi_cmnd *cmd, int resid)
 {
-        cmd->resid = resid;
+        cmd->sdb.resid = resid;
 }
 
 static inline int scsi_get_resid(struct scsi_cmnd *cmd)
 {
-        return cmd->resid;
+        return cmd->sdb.resid;
 }
 
 #define scsi_for_each_sg(cmd, sg, nseg, __i)                    \
         for_each_sg(scsi_sglist(cmd), sg, nseg, __i)
 
+static inline int scsi_bidi_cmnd(struct scsi_cmnd *cmd)
+{
+        return blk_bidi_rq(cmd->request) &&
+                (cmd->request->next_rq->special != NULL);
+}
+
+static inline struct scsi_data_buffer *scsi_in(struct scsi_cmnd *cmd)
+{
+        return scsi_bidi_cmnd(cmd) ?
+                cmd->request->next_rq->special : &cmd->sdb;
+}
+
+static inline struct scsi_data_buffer *scsi_out(struct scsi_cmnd *cmd)
+{
+        return &cmd->sdb;
+}
+
 #endif /* _SCSI_SCSI_CMND_H */
diff --git a/include/scsi/scsi_eh.h b/include/scsi/scsi_eh.h
index d21b8913ceb3..25071d5d9bf8 100644
--- a/include/scsi/scsi_eh.h
+++ b/include/scsi/scsi_eh.h
@@ -68,16 +68,15 @@ extern int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
 extern int scsi_reset_provider(struct scsi_device *, int);
 
 struct scsi_eh_save {
+        /* saved state */
         int result;
         enum dma_data_direction data_direction;
         unsigned char cmd_len;
         unsigned char cmnd[MAX_COMMAND_SIZE];
+        struct scsi_data_buffer sdb;
+        struct request *next_rq;
 
-        void *buffer;
-        unsigned bufflen;
-        unsigned short use_sg;
-        int resid;
-
+        /* new command support */
         struct scatterlist sense_sgl;
 };
 
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 0fd4746ee39d..5c58d594126a 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -39,9 +39,6 @@ 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,
@@ -136,9 +133,9 @@ 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
          *
@@ -446,15 +443,6 @@ 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;
@@ -598,7 +586,6 @@ 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