[PATCH] USB: ub 4: Zaitcev's quasi-S/G

Back out Axboe-style quasi-S/G and replace it with one command and
repeated URBs. This is similar to what usb-storage does, only instead
of a few URBs allocated together, one URB is reused.

Jens's idea was very nice, but it collapsed when I had to support
packet commads for CD burning. I cannot issue two or more packet
commands where application expected only one.

However, burning does not work completely yet. The cdrecord starts,
recognizes the device, then aborts without writing a TOC.

Signed-off-by: Pete Zaitcev <zaitcev@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 123 insertions, 164 deletions

diff --git a/drivers/block/ub.c b/drivers/block/ub.c
index 692553270401..57d3279a8815 100644
--- a/drivers/block/ub.c
+++ b/drivers/block/ub.c
@@ -235,27 +235,16 @@ struct ub_scsi_cmd {
 
         int stat_count;                 /* Retries getting status. */
 
-        /*
-         * We do not support transfers from highmem pages
-         * because the underlying USB framework does not do what we need.
-         */
-        char *data;                     /* Requested buffer */
         unsigned int len;               /* Requested length */
+        unsigned int current_sg;
+        unsigned int nsg;               /* sgv[nsg] */
+        struct scatterlist sgv[UB_MAX_REQ_SG];
 
         struct ub_lun *lun;
         void (*done)(struct ub_dev *, struct ub_scsi_cmd *);
         void *back;
 };
 
-struct ub_request {
-        struct request *rq;
-        unsigned char dir;
-        unsigned int current_block;
-        unsigned int current_sg;
-        unsigned int nsg;               /* sgv[nsg] */
-        struct scatterlist sgv[UB_MAX_REQ_SG];
-};
-
 /*
  */
 struct ub_capacity {
@@ -351,8 +340,6 @@ struct ub_lun {
         int readonly;
         int first_open;                 /* Kludge. See ub_bd_open. */
 
-        struct ub_request urq;
-
         /* Use Ingo's mempool if or when we have more than one command. */
         /*
          * Currently we never need more than one command for the whole device.
@@ -410,19 +397,16 @@ static void ub_cleanup(struct ub_dev *sc);
 static int ub_request_fn_1(struct ub_lun *lun, struct request *rq);
 static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
     struct ub_scsi_cmd *cmd, struct request *rq);
-static void ub_scsi_build_block(struct ub_lun *lun,
-    struct ub_scsi_cmd *cmd, struct ub_request *urq);
 static int ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
     struct ub_scsi_cmd *cmd, struct request *rq);
 static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 static void ub_end_rq(struct request *rq, int uptodate);
-static int ub_request_advance(struct ub_dev *sc, struct ub_lun *lun,
-    struct ub_request *urq, struct ub_scsi_cmd *cmd);
 static int ub_submit_scsi(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 static void ub_urb_complete(struct urb *urb, struct pt_regs *pt);
 static void ub_scsi_action(unsigned long _dev);
 static void ub_scsi_dispatch(struct ub_dev *sc);
 static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
+static void ub_data_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc);
 static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
@@ -793,8 +777,6 @@ static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
                 return 0;
         }
 
-        if (lun->urq.rq != NULL)
-                return -1;
         if ((cmd = ub_get_cmd(lun)) == NULL)
                 return -1;
         memset(cmd, 0, sizeof(struct ub_scsi_cmd));
@@ -813,7 +795,7 @@ static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
         cmd->state = UB_CMDST_INIT;
         cmd->lun = lun;
         cmd->done = ub_rw_cmd_done;
-        cmd->back = &lun->urq;
+        cmd->back = rq;
 
         cmd->tag = sc->tagcnt++;
         if (ub_submit_scsi(sc, cmd) != 0) {
@@ -828,22 +810,20 @@ static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
 static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
     struct ub_scsi_cmd *cmd, struct request *rq)
 {
-        struct ub_request *urq;
         int ub_dir;
         int n_elem;
-
-        urq = &lun->urq;
-        memset(urq, 0, sizeof(struct ub_request));
+        unsigned int block, nblks;
 
         if (rq_data_dir(rq) == WRITE)
                 ub_dir = UB_DIR_WRITE;
         else
                 ub_dir = UB_DIR_READ;
+        cmd->dir = ub_dir;
 
         /*
          * get scatterlist from block layer
          */
-        n_elem = blk_rq_map_sg(lun->disk->queue, rq, &urq->sgv[0]);
+        n_elem = blk_rq_map_sg(lun->disk->queue, rq, &cmd->sgv[0]);
         if (n_elem <= 0) {
                 printk(KERN_INFO "%s: failed request map (%d)\n",
                     sc->name, n_elem); /* P3 */
@@ -854,7 +834,7 @@ static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
                     sc->name, n_elem);
                 return -1;
         }
-        urq->nsg = n_elem;
+        cmd->nsg = n_elem;
         sc->sg_stat[n_elem]++;
 
         /*
@@ -863,29 +843,10 @@ static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
          * The call to blk_queue_hardsect_size() guarantees that request
          * is aligned, but it is given in terms of 512 byte units, always.
          */
-        urq->current_block = rq->sector >> lun->capacity.bshift;
-        // nblks = rq->nr_sectors >> lun->capacity.bshift;
-
-        urq->rq = rq;
-        urq->current_sg = 0;
-        urq->dir = ub_dir;
+        block = rq->sector >> lun->capacity.bshift;
+        nblks = rq->nr_sectors >> lun->capacity.bshift;
 
-        ub_scsi_build_block(lun, cmd, urq);
-        return 0;
-}
-
-static void ub_scsi_build_block(struct ub_lun *lun,
-    struct ub_scsi_cmd *cmd, struct ub_request *urq)
-{
-        struct scatterlist *sg;
-        unsigned int block, nblks;
-
-        sg = &urq->sgv[urq->current_sg];
-
-        block = urq->current_block;
-        nblks = sg->length >> (lun->capacity.bshift + 9);
-
-        cmd->cdb[0] = (urq->dir == UB_DIR_READ)? READ_10: WRITE_10;
+        cmd->cdb[0] = (ub_dir == UB_DIR_READ)? READ_10: WRITE_10;
         /* 10-byte uses 4 bytes of LBA: 2147483648KB, 2097152MB, 2048GB */
         cmd->cdb[2] = block >> 24;
         cmd->cdb[3] = block >> 16;
@@ -895,34 +856,15 @@ static void ub_scsi_build_block(struct ub_lun *lun,
         cmd->cdb[8] = nblks;
         cmd->cdb_len = 10;
 
-        cmd->dir = urq->dir;
-        cmd->data = page_address(sg->page) + sg->offset;
-        cmd->len = sg->length;
+        cmd->len = rq->nr_sectors * 512;
+
+        return 0;
 }
 
 static int ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
     struct ub_scsi_cmd *cmd, struct request *rq)
 {
-        struct ub_request *urq;
-
-        urq = &lun->urq;
-        memset(urq, 0, sizeof(struct ub_request));
-        urq->rq = rq;
-        sc->sg_stat[0]++;
-
-        if (rq->data_len != 0 && rq->data == NULL) {
-                static int do_print = 1;
-                if (do_print) {
-                        printk(KERN_WARNING "%s: unmapped packet request"
-                            " flags 0x%lx length %d\n",
-                            sc->name, rq->flags, rq->data_len);
-                        do_print = 0;
-                }
-                return -1;
-        }
-
-        memcpy(&cmd->cdb, rq->cmd, rq->cmd_len);
-        cmd->cdb_len = rq->cmd_len;
+        int n_elem;
 
         if (rq->data_len == 0) {
                 cmd->dir = UB_DIR_NONE;
@@ -931,8 +873,29 @@ static int ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
                         cmd->dir = UB_DIR_WRITE;
                 else
                         cmd->dir = UB_DIR_READ;
+
         }
-        cmd->data = rq->data;
+
+        /*
+         * get scatterlist from block layer
+         */
+        n_elem = blk_rq_map_sg(lun->disk->queue, rq, &cmd->sgv[0]);
+        if (n_elem < 0) {
+                printk(KERN_INFO "%s: failed request map (%d)\n",
+                    sc->name, n_elem); /* P3 */
+                return -1;
+        }
+        if (n_elem > UB_MAX_REQ_SG) {   /* Paranoia */
+                printk(KERN_WARNING "%s: request with %d segments\n",
+                    sc->name, n_elem);
+                return -1;
+        }
+        cmd->nsg = n_elem;
+        sc->sg_stat[n_elem]++;
+
+        memcpy(&cmd->cdb, rq->cmd, rq->cmd_len);
+        cmd->cdb_len = rq->cmd_len;
+
         cmd->len = rq->data_len;
 
         return 0;
@@ -940,33 +903,32 @@ static int ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
 
 static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 {
+        struct request *rq = cmd->back;
         struct ub_lun *lun = cmd->lun;
-        struct ub_request *urq = cmd->back;
-        struct request *rq;
         int uptodate;
 
-        rq = urq->rq;
-
-        if (blk_pc_request(rq)) {
-                /* UB_SENSE_SIZE is smaller than SCSI_SENSE_BUFFERSIZE */
-                memcpy(rq->sense, sc->top_sense, UB_SENSE_SIZE);
-                rq->sense_len = UB_SENSE_SIZE;
-        }
-
-        if (cmd->error == 0)
+        if (cmd->error == 0) {
                 uptodate = 1;
-        else
-                uptodate = 0;
 
-        if (cmd->error == 0 && urq->current_sg+1 < urq->nsg) {
-                if (ub_request_advance(sc, lun, urq, cmd) == 0) {
-                        /* Stay on target... */
-                        return;
+                if (blk_pc_request(rq)) {
+                        if (cmd->act_len >= rq->data_len)
+                                rq->data_len = 0;
+                        else
+                                rq->data_len -= cmd->act_len;
                 }
+        } else {
                 uptodate = 0;
-        }
 
-        urq->rq = NULL;
+                if (blk_pc_request(rq)) {
+                        /* UB_SENSE_SIZE is smaller than SCSI_SENSE_BUFFERSIZE */
+                        memcpy(rq->sense, sc->top_sense, UB_SENSE_SIZE);
+                        rq->sense_len = UB_SENSE_SIZE;
+                        if (sc->top_sense[0] != 0)
+                                rq->errors = SAM_STAT_CHECK_CONDITION;
+                        else
+                                rq->errors = DID_ERROR << 16;
+                }
+        }
 
         ub_put_cmd(lun, cmd);
         ub_end_rq(rq, uptodate);
@@ -982,40 +944,6 @@ static void ub_end_rq(struct request *rq, int uptodate)
         end_that_request_last(rq);
 }
 
-static int ub_request_advance(struct ub_dev *sc, struct ub_lun *lun,
-    struct ub_request *urq, struct ub_scsi_cmd *cmd)
-{
-        struct scatterlist *sg;
-        unsigned int nblks;
-
-        /* XXX This is temporary, until we sort out S/G in packet requests. */
-        if (blk_pc_request(urq->rq)) {
-                printk(KERN_WARNING
-                    "2-segment packet request completed\n"); /* P3 */
-                return -1;
-        }
-
-        sg = &urq->sgv[urq->current_sg];
-        nblks = sg->length >> (lun->capacity.bshift + 9);
-        urq->current_block += nblks;
-        urq->current_sg++;
-        sg++;
-
-        memset(cmd, 0, sizeof(struct ub_scsi_cmd));
-        ub_scsi_build_block(lun, cmd, urq);
-        cmd->state = UB_CMDST_INIT;
-        cmd->lun = lun;
-        cmd->done = ub_rw_cmd_done;
-        cmd->back = &lun->urq;
-
-        cmd->tag = sc->tagcnt++;
-        if (ub_submit_scsi(sc, cmd) != 0) {
-                return -1;
-        }
-
-        return 0;
-}
-
 /*
  * Submit a regular SCSI operation (not an auto-sense).
  *
@@ -1171,7 +1099,6 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 {
         struct urb *urb = &sc->work_urb;
         struct bulk_cs_wrap *bcs;
-        int pipe;
         int rc;
 
         if (atomic_read(&sc->poison)) {
@@ -1272,38 +1199,13 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                         goto Bad_End;
                 }
 
-                if (cmd->dir == UB_DIR_NONE) {
+                if (cmd->dir == UB_DIR_NONE || cmd->nsg < 1) {
                         ub_state_stat(sc, cmd);
                         return;
                 }
 
-                UB_INIT_COMPLETION(sc->work_done);
-
-                if (cmd->dir == UB_DIR_READ)
-                        pipe = sc->recv_bulk_pipe;
-                else
-                        pipe = sc->send_bulk_pipe;
-                sc->last_pipe = pipe;
-                usb_fill_bulk_urb(&sc->work_urb, sc->dev, pipe,
-                    cmd->data, cmd->len, ub_urb_complete, sc);
-                sc->work_urb.transfer_flags = URB_ASYNC_UNLINK;
-                sc->work_urb.actual_length = 0;
-                sc->work_urb.error_count = 0;
-                sc->work_urb.status = 0;
-
-                if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
-                        /* XXX Clear stalls */
-                        printk("ub: data #%d submit failed (%d)\n", cmd->tag, rc); /* P3 */
-                        ub_complete(&sc->work_done);
-                        ub_state_done(sc, cmd, rc);
-                        return;
-                }
-
-                sc->work_timer.expires = jiffies + UB_DATA_TIMEOUT;
-                add_timer(&sc->work_timer);
-
-                cmd->state = UB_CMDST_DATA;
-                ub_cmdtr_state(sc, cmd);
+                // udelay(125);         // usb-storage has this
+                ub_data_start(sc, cmd);
 
         } else if (cmd->state == UB_CMDST_DATA) {
                 if (urb->status == -EPIPE) {
@@ -1325,16 +1227,22 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                 if (urb->status == -EOVERFLOW) {
                         /*
                          * A babble? Failure, but we must transfer CSW now.
+                         * XXX This is going to end in perpetual babble. Reset.
                          */
                         cmd->error = -EOVERFLOW;        /* A cheap trick... */
-                } else {
-                        if (urb->status != 0)
-                                goto Bad_End;
+                        ub_state_stat(sc, cmd);
+                        return;
                 }
+                if (urb->status != 0)
+                        goto Bad_End;
 
-                cmd->act_len = urb->actual_length;
+                cmd->act_len += urb->actual_length;
                 ub_cmdtr_act_len(sc, cmd);
 
+                if (++cmd->current_sg < cmd->nsg) {
+                        ub_data_start(sc, cmd);
+                        return;
+                }
                 ub_state_stat(sc, cmd);
 
         } else if (cmd->state == UB_CMDST_STAT) {
@@ -1469,6 +1377,46 @@ Bad_End: /* Little Excel is dead */
 
 /*
  * Factorization helper for the command state machine:
+ * Initiate a data segment transfer.
+ */
+static void ub_data_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
+{
+        struct scatterlist *sg = &cmd->sgv[cmd->current_sg];
+        int pipe;
+        int rc;
+
+        UB_INIT_COMPLETION(sc->work_done);
+
+        if (cmd->dir == UB_DIR_READ)
+                pipe = sc->recv_bulk_pipe;
+        else
+                pipe = sc->send_bulk_pipe;
+        sc->last_pipe = pipe;
+        usb_fill_bulk_urb(&sc->work_urb, sc->dev, pipe,
+            page_address(sg->page) + sg->offset, sg->length,
+            ub_urb_complete, sc);
+        sc->work_urb.transfer_flags = URB_ASYNC_UNLINK;
+        sc->work_urb.actual_length = 0;
+        sc->work_urb.error_count = 0;
+        sc->work_urb.status = 0;
+
+        if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
+                /* XXX Clear stalls */
+                printk("ub: data #%d submit failed (%d)\n", cmd->tag, rc); /* P3 */
+                ub_complete(&sc->work_done);
+                ub_state_done(sc, cmd, rc);
+                return;
+        }
+
+        sc->work_timer.expires = jiffies + UB_DATA_TIMEOUT;
+        add_timer(&sc->work_timer);
+
+        cmd->state = UB_CMDST_DATA;
+        ub_cmdtr_state(sc, cmd);
+}
+
+/*
+ * Factorization helper for the command state machine:
  * Finish the command.
  */
 static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc)
@@ -1552,6 +1500,7 @@ static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 {
         struct ub_scsi_cmd *scmd;
+        struct scatterlist *sg;
         int rc;
 
         if (cmd->cdb[0] == REQUEST_SENSE) {
@@ -1560,12 +1509,17 @@ static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
         }
 
         scmd = &sc->top_rqs_cmd;
+        memset(scmd, 0, sizeof(struct ub_scsi_cmd));
         scmd->cdb[0] = REQUEST_SENSE;
         scmd->cdb[4] = UB_SENSE_SIZE;
         scmd->cdb_len = 6;
         scmd->dir = UB_DIR_READ;
         scmd->state = UB_CMDST_INIT;
-        scmd->data = sc->top_sense;
+        scmd->nsg = 1;
+        sg = &scmd->sgv[0];
+        sg->page = virt_to_page(sc->top_sense);
+        sg->offset = (unsigned int)sc->top_sense & (PAGE_SIZE-1);
+        sg->length = UB_SENSE_SIZE;
         scmd->len = UB_SENSE_SIZE;
         scmd->lun = cmd->lun;
         scmd->done = ub_top_sense_done;
@@ -1628,7 +1582,7 @@ static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
  */
 static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd)
 {
-        unsigned char *sense = scmd->data;
+        unsigned char *sense = sc->top_sense;
         struct ub_scsi_cmd *cmd;
 
         /*
@@ -1920,6 +1874,7 @@ static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
     struct ub_capacity *ret)
 {
         struct ub_scsi_cmd *cmd;
+        struct scatterlist *sg;
         char *p;
         enum { ALLOC_SIZE = sizeof(struct ub_scsi_cmd) + 8 };
         unsigned long flags;
@@ -1940,7 +1895,11 @@ static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
         cmd->cdb_len = 10;
         cmd->dir = UB_DIR_READ;
         cmd->state = UB_CMDST_INIT;
-        cmd->data = p;
+        cmd->nsg = 1;
+        sg = &cmd->sgv[0];
+        sg->page = virt_to_page(p);
+        sg->offset = (unsigned int)p & (PAGE_SIZE-1);
+        sg->length = 8;
         cmd->len = 8;
         cmd->lun = lun;
         cmd->done = ub_probe_done;