[SCSI] ibmvscsi: handle large scatter/gather lists

The maximum size of a scatter-gather list that the current IBM VSCSI
Client can handle is 10.  This patch adds large scatter-gather support
to the client so that it is capable of handling up to SG_ALL(255)
number of requests in the scatter-gather list.

Signed-off-by: Linda Xie <lxie@us.ibm.com>
Acked by: Dave C Boutcher <sleddog@us.ibm.com>

Rejections fixed up and
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

2 files changed, 116 insertions, 42 deletions

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index e3e6752c4104..1b911dadf64b 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -87,7 +87,7 @@ static int max_channel = 3;
 static int init_timeout = 5;
 static int max_requests = 50;
 
-#define IBMVSCSI_VERSION "1.5.6"
+#define IBMVSCSI_VERSION "1.5.7"
 
 MODULE_DESCRIPTION("IBM Virtual SCSI");
 MODULE_AUTHOR("Dave Boutcher");
@@ -145,6 +145,8 @@ static int initialize_event_pool(struct event_pool *pool,
                         sizeof(*evt->xfer_iu) * i;
                 evt->xfer_iu = pool->iu_storage + i;
                 evt->hostdata = hostdata;
+                evt->ext_list = NULL;
+                evt->ext_list_token = 0;
         }
 
         return 0;
@@ -161,9 +163,16 @@ static void release_event_pool(struct event_pool *pool,
                                struct ibmvscsi_host_data *hostdata)
 {
         int i, in_use = 0;
-        for (i = 0; i < pool->size; ++i)
+        for (i = 0; i < pool->size; ++i) {
                 if (atomic_read(&pool->events[i].free) != 1)
                         ++in_use;
+                if (pool->events[i].ext_list) {
+                        dma_free_coherent(hostdata->dev,
+                                  SG_ALL * sizeof(struct memory_descriptor),
+                                  pool->events[i].ext_list,
+                                  pool->events[i].ext_list_token);
+                }
+        }
         if (in_use)
                 printk(KERN_WARNING
                        "ibmvscsi: releasing event pool with %d "
@@ -286,24 +295,41 @@ static void set_srp_direction(struct scsi_cmnd *cmd,
         } else {
                 if (cmd->sc_data_direction == DMA_TO_DEVICE) {
                         srp_cmd->data_out_format = SRP_INDIRECT_BUFFER;
-                        srp_cmd->data_out_count = numbuf;
+                        srp_cmd->data_out_count =
+                                numbuf < MAX_INDIRECT_BUFS ?
+                                        numbuf: MAX_INDIRECT_BUFS;
                 } else {
                         srp_cmd->data_in_format = SRP_INDIRECT_BUFFER;
-                        srp_cmd->data_in_count = numbuf;
+                        srp_cmd->data_in_count =
+                                numbuf < MAX_INDIRECT_BUFS ?
+                                        numbuf: MAX_INDIRECT_BUFS;
                 }
         }
 }
 
+static void unmap_sg_list(int num_entries, 
+                struct device *dev,
+                struct memory_descriptor *md)
+{ 
+        int i;
+
+        for (i = 0; i < num_entries; ++i) {
+                dma_unmap_single(dev,
+                        md[i].virtual_address,
+                        md[i].length, DMA_BIDIRECTIONAL);
+        }
+}
+
 /**
  * unmap_cmd_data: - Unmap data pointed in srp_cmd based on the format
  * @cmd:        srp_cmd whose additional_data member will be unmapped
  * @dev:        device for which the memory is mapped
  *
 */
-static void unmap_cmd_data(struct srp_cmd *cmd, struct device *dev)
+static void unmap_cmd_data(struct srp_cmd *cmd,
+                           struct srp_event_struct *evt_struct,
+                           struct device *dev)
 {
-        int i;
-
         if ((cmd->data_out_format == SRP_NO_BUFFER) &&
             (cmd->data_in_format == SRP_NO_BUFFER))
                 return;
@@ -318,15 +344,34 @@ static void unmap_cmd_data(struct srp_cmd *cmd, struct device *dev)
                         (struct indirect_descriptor *)cmd->additional_data;
                 int num_mapped = indirect->head.length / 
                         sizeof(indirect->list[0]);
-                for (i = 0; i < num_mapped; ++i) {
-                        struct memory_descriptor *data = &indirect->list[i];
-                        dma_unmap_single(dev,
-                                         data->virtual_address,
-                                         data->length, DMA_BIDIRECTIONAL);
+
+                if (num_mapped <= MAX_INDIRECT_BUFS) {
+                        unmap_sg_list(num_mapped, dev, &indirect->list[0]);
+                        return;
                 }
+
+                unmap_sg_list(num_mapped, dev, evt_struct->ext_list);
         }
 }
 
+static int map_sg_list(int num_entries, 
+                       struct scatterlist *sg,
+                       struct memory_descriptor *md)
+{
+        int i;
+        u64 total_length = 0;
+
+        for (i = 0; i < num_entries; ++i) {
+                struct memory_descriptor *descr = md + i;
+                struct scatterlist *sg_entry = &sg[i];
+                descr->virtual_address = sg_dma_address(sg_entry);
+                descr->length = sg_dma_len(sg_entry);
+                descr->memory_handle = 0;
+                total_length += sg_dma_len(sg_entry);
+        }
+        return total_length;
+}
+
 /**
  * map_sg_data: - Maps dma for a scatterlist and initializes decriptor fields
  * @cmd:        Scsi_Cmnd with the scatterlist
@@ -337,10 +382,11 @@ static void unmap_cmd_data(struct srp_cmd *cmd, struct device *dev)
  * Returns 1 on success.
 */
 static int map_sg_data(struct scsi_cmnd *cmd,
+                       struct srp_event_struct *evt_struct,
                        struct srp_cmd *srp_cmd, struct device *dev)
 {
 
-        int i, sg_mapped;
+        int sg_mapped;
         u64 total_length = 0;
         struct scatterlist *sg = cmd->request_buffer;
         struct memory_descriptor *data =
@@ -363,27 +409,46 @@ static int map_sg_data(struct scsi_cmnd *cmd,
                 return 1;
         }
 
-        if (sg_mapped > MAX_INDIRECT_BUFS) {
+        if (sg_mapped > SG_ALL) {
                 printk(KERN_ERR
                        "ibmvscsi: More than %d mapped sg entries, got %d\n",
-                       MAX_INDIRECT_BUFS, sg_mapped);
+                       SG_ALL, sg_mapped);
                 return 0;
         }
 
         indirect->head.virtual_address = 0;
         indirect->head.length = sg_mapped * sizeof(indirect->list[0]);
         indirect->head.memory_handle = 0;
-        for (i = 0; i < sg_mapped; ++i) {
-                struct memory_descriptor *descr = &indirect->list[i];
-                struct scatterlist *sg_entry = &sg[i];
-                descr->virtual_address = sg_dma_address(sg_entry);
-                descr->length = sg_dma_len(sg_entry);
-                descr->memory_handle = 0;
-                total_length += sg_dma_len(sg_entry);
+
+        if (sg_mapped <= MAX_INDIRECT_BUFS) {
+                total_length = map_sg_list(sg_mapped, sg, &indirect->list[0]);
+                indirect->total_length = total_length;
+                return 1;
         }
-        indirect->total_length = total_length;
 
-        return 1;
+        /* get indirect table */
+        if (!evt_struct->ext_list) {
+                evt_struct->ext_list =(struct memory_descriptor*)
+                        dma_alloc_coherent(dev, 
+                                SG_ALL * sizeof(struct memory_descriptor),
+                                &evt_struct->ext_list_token, 0);
+                if (!evt_struct->ext_list) {
+                    printk(KERN_ERR
+                        "ibmvscsi: Can't allocate memory for indirect table\n");
+                        return 0;
+                        
+                }
+        }
+
+        total_length = map_sg_list(sg_mapped, sg, evt_struct->ext_list);        
+
+        indirect->total_length = total_length;
+        indirect->head.virtual_address = evt_struct->ext_list_token;
+        indirect->head.length = sg_mapped * sizeof(indirect->list[0]);
+        memcpy(indirect->list, evt_struct->ext_list,
+                MAX_INDIRECT_BUFS * sizeof(struct memory_descriptor));
+        
+        return 1;
 }
 
 /**
@@ -428,6 +493,7 @@ static int map_single_data(struct scsi_cmnd *cmd,
  * Returns 1 on success.
 */
 static int map_data_for_srp_cmd(struct scsi_cmnd *cmd,
+                                struct srp_event_struct *evt_struct,
                                 struct srp_cmd *srp_cmd, struct device *dev)
 {
         switch (cmd->sc_data_direction) {
@@ -450,7 +516,7 @@ static int map_data_for_srp_cmd(struct scsi_cmnd *cmd,
         if (!cmd->request_buffer)
                 return 1;
         if (cmd->use_sg)
-                return map_sg_data(cmd, srp_cmd, dev);
+                return map_sg_data(cmd, evt_struct, srp_cmd, dev);
         return map_single_data(cmd, srp_cmd, dev);
 }
 
@@ -486,6 +552,7 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct,
                 printk(KERN_WARNING 
                        "ibmvscsi: Warning, request_limit exceeded\n");
                 unmap_cmd_data(&evt_struct->iu.srp.cmd,
+                               evt_struct,
                                hostdata->dev);
                 free_event_struct(&hostdata->pool, evt_struct);
                 return SCSI_MLQUEUE_HOST_BUSY;
@@ -513,7 +580,7 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct,
         return 0;
 
  send_error:
-        unmap_cmd_data(&evt_struct->iu.srp.cmd, hostdata->dev);
+        unmap_cmd_data(&evt_struct->iu.srp.cmd, evt_struct, hostdata->dev);
 
         if ((cmnd = evt_struct->cmnd) != NULL) {
                 cmnd->result = DID_ERROR << 16;
@@ -551,6 +618,7 @@ static void handle_cmd_rsp(struct srp_event_struct *evt_struct)
                                rsp->sense_and_response_data,
                                rsp->sense_data_list_length);
                 unmap_cmd_data(&evt_struct->iu.srp.cmd, 
+                               evt_struct, 
                                evt_struct->hostdata->dev);
 
                 if (rsp->doover)
@@ -583,6 +651,7 @@ static int ibmvscsi_queuecommand(struct scsi_cmnd *cmnd,
 {
         struct srp_cmd *srp_cmd;
         struct srp_event_struct *evt_struct;
+        struct indirect_descriptor *indirect;
         struct ibmvscsi_host_data *hostdata =
                 (struct ibmvscsi_host_data *)&cmnd->device->host->hostdata;
         u16 lun = lun_from_dev(cmnd->device);
@@ -591,14 +660,6 @@ static int ibmvscsi_queuecommand(struct scsi_cmnd *cmnd,
         if (!evt_struct)
                 return SCSI_MLQUEUE_HOST_BUSY;
 
-        init_event_struct(evt_struct,
-                          handle_cmd_rsp,
-                          VIOSRP_SRP_FORMAT,
-                          cmnd->timeout_per_command/HZ);
-
-        evt_struct->cmnd = cmnd;
-        evt_struct->cmnd_done = done;
-
         /* Set up the actual SRP IU */
         srp_cmd = &evt_struct->iu.srp.cmd;
         memset(srp_cmd, 0x00, sizeof(*srp_cmd));
@@ -606,17 +667,25 @@ static int ibmvscsi_queuecommand(struct scsi_cmnd *cmnd,
         memcpy(srp_cmd->cdb, cmnd->cmnd, sizeof(cmnd->cmnd));
         srp_cmd->lun = ((u64) lun) << 48;
 
-        if (!map_data_for_srp_cmd(cmnd, srp_cmd, hostdata->dev)) {
+        if (!map_data_for_srp_cmd(cmnd, evt_struct, srp_cmd, hostdata->dev)) {
                 printk(KERN_ERR "ibmvscsi: couldn't convert cmd to srp_cmd\n");
                 free_event_struct(&hostdata->pool, evt_struct);
                 return SCSI_MLQUEUE_HOST_BUSY;
         }
 
+        init_event_struct(evt_struct,
+                          handle_cmd_rsp,
+                          VIOSRP_SRP_FORMAT,
+                          cmnd->timeout_per_command/HZ);
+
+        evt_struct->cmnd = cmnd;
+        evt_struct->cmnd_done = done;
+
         /* Fix up dma address of the buffer itself */
-        if ((srp_cmd->data_out_format == SRP_INDIRECT_BUFFER) ||
-            (srp_cmd->data_in_format == SRP_INDIRECT_BUFFER)) {
-                struct indirect_descriptor *indirect =
-                    (struct indirect_descriptor *)srp_cmd->additional_data;
+        indirect = (struct indirect_descriptor *)srp_cmd->additional_data;
+        if (((srp_cmd->data_out_format == SRP_INDIRECT_BUFFER) ||
+            (srp_cmd->data_in_format == SRP_INDIRECT_BUFFER)) &&
+            (indirect->head.virtual_address == 0)) {
                 indirect->head.virtual_address = evt_struct->crq.IU_data_ptr +
                     offsetof(struct srp_cmd, additional_data) +
                     offsetof(struct indirect_descriptor, list);
@@ -931,7 +1000,8 @@ static int ibmvscsi_eh_abort_handler(struct scsi_cmnd *cmd)
 
         cmd->result = (DID_ABORT << 16);
         list_del(&found_evt->list);
-        unmap_cmd_data(&found_evt->iu.srp.cmd, found_evt->hostdata->dev);
+        unmap_cmd_data(&found_evt->iu.srp.cmd, found_evt,
+                       found_evt->hostdata->dev);
         free_event_struct(&found_evt->hostdata->pool, found_evt);
         spin_unlock_irqrestore(hostdata->host->host_lock, flags);
         atomic_inc(&hostdata->request_limit);
@@ -1023,7 +1093,8 @@ static int ibmvscsi_eh_device_reset_handler(struct scsi_cmnd *cmd)
                         if (tmp_evt->cmnd)
                                 tmp_evt->cmnd->result = (DID_RESET << 16);
                         list_del(&tmp_evt->list);
-                        unmap_cmd_data(&tmp_evt->iu.srp.cmd, tmp_evt->hostdata->dev);
+                        unmap_cmd_data(&tmp_evt->iu.srp.cmd, tmp_evt,
+                                       tmp_evt->hostdata->dev);
                         free_event_struct(&tmp_evt->hostdata->pool,
                                                    tmp_evt);
                         atomic_inc(&hostdata->request_limit);
@@ -1052,6 +1123,7 @@ static void purge_requests(struct ibmvscsi_host_data *hostdata)
                 if (tmp_evt->cmnd) {
                         tmp_evt->cmnd->result = (DID_ERROR << 16);
                         unmap_cmd_data(&tmp_evt->iu.srp.cmd, 
+                                       tmp_evt, 
                                        tmp_evt->hostdata->dev);
                         if (tmp_evt->cmnd_done)
                                 tmp_evt->cmnd_done(tmp_evt->cmnd);
@@ -1356,7 +1428,7 @@ static struct scsi_host_template driver_template = {
         .cmd_per_lun = 16,
         .can_queue = 1,         /* Updated after SRP_LOGIN */
         .this_id = -1,
-        .sg_tablesize = MAX_INDIRECT_BUFS,
+        .sg_tablesize = SG_ALL,
         .use_clustering = ENABLE_CLUSTERING,
         .shost_attrs = ibmvscsi_attrs,
 };
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.h b/drivers/scsi/ibmvscsi/ibmvscsi.h
index 1030b703c30e..8bec0438dc8a 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.h
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.h
@@ -68,6 +68,8 @@ struct srp_event_struct {
         void (*cmnd_done) (struct scsi_cmnd *);
         struct completion comp;
         union viosrp_iu *sync_srp;
+        struct memory_descriptor *ext_list;
+        dma_addr_t ext_list_token;
 };
 
 /* a pool of event structs for use */