From: Boaz Harrosh <[EMAIL PROTECTED]>

  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

Signed-off-by: Boaz Harrosh <[EMAIL PROTECTED]>
Signed-off-by: FUJITA Tomonori <[EMAIL PROTECTED]>
Cc: James Bottomley <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---

 drivers/scsi/libsrp.c        |    4 -
 drivers/scsi/scsi.c          |    2 
 drivers/scsi/scsi_error.c    |   28 ++++--------
 drivers/scsi/scsi_lib.c      |   77 ++++++++++++---------------------
 drivers/scsi/sd.c            |    4 -
 drivers/scsi/sr.c            |   25 +++++-----
 drivers/usb/storage/isd200.c |    8 +--
 include/scsi/scsi_cmnd.h     |   39 ++++++++++------
 include/scsi/scsi_eh.h       |    8 +--
 include/scsi/scsi_host.h     |    4 -
 10 files changed, 91 insertions(+), 108 deletions(-)

diff -puN drivers/scsi/libsrp.c~scsi-scsi_data_buffer drivers/scsi/libsrp.c
--- a/drivers/scsi/libsrp.c~scsi-scsi_data_buffer
+++ a/drivers/scsi/libsrp.c
@@ -426,8 +426,8 @@ int srp_cmd_queue(struct Scsi_Host *shos
 
        sc->SCp.ptr = info;
        memcpy(sc->cmnd, cmd->cdb, MAX_COMMAND_SIZE);
-       sc->request_bufflen = len;
-       sc->request_buffer = (void *) (unsigned long) addr;
+       sc->sdb.length = len;
+       sc->sdb.sglist = (void *) (unsigned long) addr;
        sc->tag = tag;
        err = scsi_tgt_queue_command(sc, itn_id, (struct scsi_lun *)&cmd->lun,
                                     cmd->tag);
diff -puN drivers/scsi/scsi.c~scsi-scsi_data_buffer drivers/scsi/scsi.c
--- a/drivers/scsi/scsi.c~scsi-scsi_data_buffer
+++ a/drivers/scsi/scsi.c
@@ -712,7 +712,7 @@ void scsi_finish_command(struct scsi_cmn
                                "Notifying upper driver of completion "
                                "(result %x)\n", cmd->result));
 
-       good_bytes = cmd->request_bufflen;
+       good_bytes = scsi_bufflen(cmd);
         if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
                drv = scsi_cmd_to_driver(cmd);
                if (drv->done)
diff -puN drivers/scsi/scsi_error.c~scsi-scsi_data_buffer 
drivers/scsi/scsi_error.c
--- a/drivers/scsi/scsi_error.c~scsi-scsi_data_buffer
+++ a/drivers/scsi/scsi_error.c
@@ -617,29 +617,25 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd 
        ses->cmd_len = scmd->cmd_len;
        memcpy(ses->cmnd, scmd->cmnd, sizeof(scmd->cmnd));
        ses->data_direction = scmd->sc_data_direction;
-       ses->bufflen = scmd->request_bufflen;
-       ses->buffer = scmd->request_buffer;
-       ses->use_sg = scmd->use_sg;
-       ses->resid = scmd->resid;
+       ses->sdb = scmd->sdb;
        ses->result = scmd->result;
 
+       memset(&scmd->sdb, 0, sizeof(scmd->sdb));
+
        if (sense_bytes) {
-               scmd->request_bufflen = min_t(unsigned,
+               scmd->sdb.length = min_t(unsigned,
                                       sizeof(scmd->sense_buffer), sense_bytes);
                sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
-                                                      scmd->request_bufflen);
-               scmd->request_buffer = &ses->sense_sgl;
+                                                             scmd->sdb.length);
+               scmd->sdb.sglist = &ses->sense_sgl;
                scmd->sc_data_direction = DMA_FROM_DEVICE;
-               scmd->use_sg = 1;
+               scmd->sdb.sg_count = 1;
                memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
                scmd->cmnd[0] = REQUEST_SENSE;
-               scmd->cmnd[4] = scmd->request_bufflen;
+               scmd->cmnd[4] = scmd->sdb.length;
                scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
        } else {
-               scmd->request_buffer = NULL;
-               scmd->request_bufflen = 0;
                scmd->sc_data_direction = DMA_NONE;
-               scmd->use_sg = 0;
                if (cmnd) {
                        memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
                        memcpy(scmd->cmnd, cmnd, cmnd_size);
@@ -676,10 +672,7 @@ void scsi_eh_restore_cmnd(struct scsi_cm
        scmd->cmd_len = ses->cmd_len;
        memcpy(scmd->cmnd, ses->cmnd, sizeof(scmd->cmnd));
        scmd->sc_data_direction = ses->data_direction;
-       scmd->request_bufflen = ses->bufflen;
-       scmd->request_buffer = ses->buffer;
-       scmd->use_sg = ses->use_sg;
-       scmd->resid = ses->resid;
+       scmd->sdb = ses->sdb;
        scmd->result = ses->result;
 }
 EXPORT_SYMBOL(scsi_eh_restore_cmnd);
@@ -1700,8 +1693,7 @@ scsi_reset_provider(struct scsi_device *
        memset(&scmd->cmnd, '\0', sizeof(scmd->cmnd));
     
        scmd->scsi_done         = scsi_reset_provider_done_command;
-       scmd->request_buffer            = NULL;
-       scmd->request_bufflen           = 0;
+       memset(&scmd->sdb, 0, sizeof(scmd->sdb));
 
        scmd->cmd_len                   = 0;
 
diff -puN drivers/scsi/scsi_lib.c~scsi-scsi_data_buffer drivers/scsi/scsi_lib.c
--- a/drivers/scsi/scsi_lib.c~scsi-scsi_data_buffer
+++ a/drivers/scsi/scsi_lib.c
@@ -440,7 +440,7 @@ EXPORT_SYMBOL_GPL(scsi_execute_async);
 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
 {
        cmd->serial_number = 0;
-       cmd->resid = 0;
+       scsi_set_resid(cmd, 0);
        memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
        if (cmd->cmd_len == 0)
                cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
@@ -739,17 +739,15 @@ static inline unsigned int scsi_sgtable_
        return index;
 }
 
-static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd,
-                                                               gfp_t gfp_mask)
+static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb,
+                                       unsigned short sg_count, gfp_t gfp_mask)
 {
        struct scsi_host_sg_pool *sgp;
        struct scatterlist *sgl, *prev, *ret;
        unsigned int index;
        int this, left;
 
-       BUG_ON(!cmd->use_sg);
-
-       left = cmd->use_sg;
+       left = sg_count;
        ret = prev = NULL;
        do {
                this = left;
@@ -803,8 +801,9 @@ static struct scatterlist *scsi_alloc_sg
         * ->use_sg may get modified after dma mapping has potentially
         * shrunk the number of segments, so keep a copy of it for free.
         */
-       cmd->__use_sg = cmd->use_sg;
-       return ret;
+       sdb->alloc_sg_count = sdb->sg_count = sg_count;
+       sdb->sglist = ret;
+       return 0;
 enomem:
        if (ret) {
                /*
@@ -823,24 +822,24 @@ enomem:
 
                mempool_free(prev, sgp->pool);
        }
-       return NULL;
+       return -ENOMEM;
 }
 
-static void scsi_free_sgtable(struct scsi_cmnd *cmd)
+static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
 {
-       struct scatterlist *sgl = cmd->request_buffer;
+       struct scatterlist *sgl = sdb->sglist;
        struct scsi_host_sg_pool *sgp;
 
        /*
         * if this is the biggest size sglist, check if we have
         * chained parts we need to free
         */
-       if (cmd->__use_sg > SCSI_MAX_SG_SEGMENTS) {
+       if (sdb->alloc_sg_count > SCSI_MAX_SG_SEGMENTS) {
                unsigned short this, left;
                struct scatterlist *next;
                unsigned int index;
 
-               left = cmd->__use_sg - (SCSI_MAX_SG_SEGMENTS - 1);
+               left = sdb->alloc_sg_count - (SCSI_MAX_SG_SEGMENTS - 1);
                next = sg_chain_ptr(&sgl[SCSI_MAX_SG_SEGMENTS - 1]);
                while (left && next) {
                        sgl = next;
@@ -864,10 +863,10 @@ static void scsi_free_sgtable(struct scs
                /*
                 * Restore original, will be freed below
                 */
-               sgl = cmd->request_buffer;
+               sgl = sdb->sglist;
                sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
        } else
-               sgp = scsi_sg_pools + scsi_sgtable_index(cmd->__use_sg);
+               sgp = scsi_sg_pools + scsi_sgtable_index(sdb->alloc_sg_count);
 
        mempool_free(sgl, sgp->pool);
 }
@@ -891,15 +890,10 @@ static void scsi_free_sgtable(struct scs
  */
 void scsi_release_buffers(struct scsi_cmnd *cmd)
 {
-       if (cmd->use_sg)
-               scsi_free_sgtable(cmd);
+       if (cmd->sdb.sglist)
+               scsi_free_sgtable(&cmd->sdb);
 
-       /*
-        * Zero these out.  They now point to freed memory, and it is
-        * dangerous to hang onto the pointers.
-        */
-       cmd->request_buffer = NULL;
-       cmd->request_bufflen = 0;
+       memset(&cmd->sdb, 0, sizeof(cmd->sdb));
 }
 EXPORT_SYMBOL(scsi_release_buffers);
 
@@ -934,7 +928,7 @@ EXPORT_SYMBOL(scsi_release_buffers);
 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 {
        int result = cmd->result;
-       int this_count = cmd->request_bufflen;
+       int this_count = scsi_bufflen(cmd);
        struct request_queue *q = cmd->device->request_queue;
        struct request *req = cmd->request;
        int clear_errors = 1;
@@ -942,8 +936,6 @@ void scsi_io_completion(struct scsi_cmnd
        int sense_valid = 0;
        int sense_deferred = 0;
 
-       scsi_release_buffers(cmd);
-
        if (result) {
                sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
                if (sense_valid)
@@ -966,9 +958,11 @@ void scsi_io_completion(struct scsi_cmnd
                                req->sense_len = len;
                        }
                }
-               req->data_len = cmd->resid;
+               req->data_len = scsi_get_resid(cmd);
        }
 
+       scsi_release_buffers(cmd);
+
        /*
         * Next deal with any sectors which we were able to correctly
         * handle.
@@ -976,7 +970,6 @@ void scsi_io_completion(struct scsi_cmnd
        SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
                                      "%d bytes done.\n",
                                      req->nr_sectors, good_bytes));
-       SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
 
        if (clear_errors)
                req->errors = 0;
@@ -1107,36 +1100,26 @@ int scsi_init_io(struct scsi_cmnd *cmd, 
 {
        struct request     *req = cmd->request;
        int                count;
+       struct scsi_data_buffer *sdb = &cmd->sdb;
 
-       /*
-        * We used to not use scatter-gather for single segment request,
-        * but now we do (it makes highmem I/O easier to support without
-        * kmapping pages)
-        */
-       cmd->use_sg = req->nr_phys_segments;
-
-       /*
-        * If sg table allocation fails, requeue request later.
-        */
-       cmd->request_buffer = scsi_alloc_sgtable(cmd, gfp_mask);
-       if (unlikely(!cmd->request_buffer)) {
+       if (scsi_alloc_sgtable(sdb, req->nr_phys_segments, gfp_mask)) {
                scsi_unprep_request(req);
                return BLKPREP_DEFER;
        }
 
        req->buffer = NULL;
        if (blk_pc_request(req))
-               cmd->request_bufflen = req->data_len;
+               sdb->length = req->data_len;
        else
-               cmd->request_bufflen = req->nr_sectors << 9;
+               sdb->length = req->nr_sectors << 9;
 
        /* 
         * Next, walk the list, and fill in the addresses and sizes of
         * each segment.
         */
-       count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
-       BUG_ON(count > cmd->use_sg);
-       cmd->use_sg = count;
+       count = blk_rq_map_sg(req->q, req, sdb->sglist);
+       BUG_ON(count > sdb->sg_count);
+       sdb->sg_count = count;
        return BLKPREP_OK;
 }
 EXPORT_SYMBOL(scsi_init_io);
@@ -1192,9 +1175,7 @@ int scsi_setup_blk_pc_cmnd(struct scsi_d
                BUG_ON(req->data_len);
                BUG_ON(req->data);
 
-               cmd->request_bufflen = 0;
-               cmd->request_buffer = NULL;
-               cmd->use_sg = 0;
+               memset(&cmd->sdb, 0, sizeof(cmd->sdb));
                req->buffer = NULL;
        }
 
diff -puN drivers/scsi/sd.c~scsi-scsi_data_buffer drivers/scsi/sd.c
--- a/drivers/scsi/sd.c~scsi-scsi_data_buffer
+++ a/drivers/scsi/sd.c
@@ -510,7 +510,7 @@ static int sd_prep_fn(struct request_que
                SCpnt->cmnd[4] = (unsigned char) this_count;
                SCpnt->cmnd[5] = 0;
        }
-       SCpnt->request_bufflen = this_count * sdp->sector_size;
+       SCpnt->sdb.length = this_count * sdp->sector_size;
 
        /*
         * We shouldn't disconnect in the middle of a sector, so with a dumb
@@ -917,7 +917,7 @@ static struct block_device_operations sd
 static int sd_done(struct scsi_cmnd *SCpnt)
 {
        int result = SCpnt->result;
-       unsigned int xfer_size = SCpnt->request_bufflen;
+       unsigned int xfer_size = scsi_bufflen(SCpnt);
        unsigned int good_bytes = result ? 0 : xfer_size;
        u64 start_lba = SCpnt->request->sector;
        u64 bad_lba;
diff -puN drivers/scsi/sr.c~scsi-scsi_data_buffer drivers/scsi/sr.c
--- a/drivers/scsi/sr.c~scsi-scsi_data_buffer
+++ a/drivers/scsi/sr.c
@@ -233,7 +233,7 @@ 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;
@@ -381,17 +381,18 @@ static int sr_prep_fn(struct request_que
        }
 
        {
-               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;
                }
        }
 
@@ -399,12 +400,12 @@ static int sr_prep_fn(struct request_que
         * 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",
@@ -418,7 +419,7 @@ static int sr_prep_fn(struct request_que
 
        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;
diff -puN drivers/usb/storage/isd200.c~scsi-scsi_data_buffer 
drivers/usb/storage/isd200.c
--- a/drivers/usb/storage/isd200.c~scsi-scsi_data_buffer
+++ a/drivers/usb/storage/isd200.c
@@ -415,14 +415,14 @@ static void isd200_set_srb(struct isd200
                sg_init_one(&info->sg, buff, bufflen);
 
        srb->sc_data_direction = dir;
-       srb->request_buffer = buff ? &info->sg : NULL;
-       srb->request_bufflen = bufflen;
-       srb->use_sg = buff ? 1 : 0;
+       srb->sdb.sglist = buff ? &info->sg : NULL;
+       srb->sdb.length = bufflen;
+       srb->sdb.sg_count = buff ? 1 : 0;
 }
 
 static void isd200_srb_set_bufflen(struct scsi_cmnd *srb, unsigned bufflen)
 {
-       srb->request_bufflen = bufflen;
+       srb->sdb.length = bufflen;
 }
 
 
diff -puN include/scsi/scsi_cmnd.h~scsi-scsi_data_buffer 
include/scsi/scsi_cmnd.h
--- a/include/scsi/scsi_cmnd.h~scsi-scsi_data_buffer
+++ a/include/scsi/scsi_cmnd.h
@@ -12,6 +12,13 @@ struct scatterlist;
 struct Scsi_Host;
 struct scsi_device;
 
+struct scsi_data_buffer {
+       struct scatterlist *sglist;
+       unsigned length;
+       int resid;
+       unsigned short sg_count;
+       unsigned short alloc_sg_count; /* private to scsi_lib */
+};
 
 /* embedded in scsi_cmnd */
 struct scsi_pointer {
@@ -62,15 +69,10 @@ 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 */
-       unsigned short use_sg;  /* Number of pieces of scatter-gather */
-       unsigned short __use_sg;
-
        unsigned underflow;     /* Return error if less than
                                   this amount is transferred */
 
@@ -80,10 +82,6 @@ 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 */
 
@@ -114,6 +112,8 @@ struct scsi_cmnd {
        int result;             /* Status code from lower level driver */
 
        unsigned char tag;      /* SCSI-II queued command tag */
+
+       struct scsi_data_buffer sdb;
 };
 
 extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t);
@@ -134,18 +134,29 @@ extern void scsi_release_buffers(struct 
 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) ((struct scatterlist *)(cmd)->request_buffer)
-#define scsi_bufflen(cmd) ((cmd)->request_bufflen)
+static inline unsigned scsi_sg_count(struct scsi_cmnd *cmd)
+{
+       return cmd->sdb.sg_count;
+}
+
+static inline struct scatterlist *scsi_sglist(struct scsi_cmnd *cmd)
+{
+       return cmd->sdb.sglist;
+}
+
+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)                   \
diff -puN include/scsi/scsi_eh.h~scsi-scsi_data_buffer include/scsi/scsi_eh.h
--- a/include/scsi/scsi_eh.h~scsi-scsi_data_buffer
+++ a/include/scsi/scsi_eh.h
@@ -68,16 +68,14 @@ extern int scsi_get_sense_info_fld(const
 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;
 
-       void *buffer;
-       unsigned bufflen;
-       unsigned short use_sg;
-       int resid;
-
+       /* new command support */
        struct scatterlist sense_sgl;
 };
 
diff -puN include/scsi/scsi_host.h~scsi-scsi_data_buffer 
include/scsi/scsi_host.h
--- a/include/scsi/scsi_host.h~scsi-scsi_data_buffer
+++ a/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
         *
_
-
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