[SCSI] bidirectional command support

[deliverable/linux.git] / drivers / scsi / scsi_lib.c

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index d5e77e9b3a9cfb8e0ca6af380ef71a41aa38aa0e..681ed1b830f5777ac88e81ee336b667fb8dfd2e6 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -64,6 +64,8 @@ static struct scsi_host_sg_pool scsi_sg_pools[] = {
 };
 #undef SP
 
+static struct kmem_cache *scsi_bidi_sdb_cache;
+
 static void scsi_run_queue(struct request_queue *q);
 
 /*
@@ -790,9 +792,37 @@ void scsi_release_buffers(struct scsi_cmnd *cmd)
                scsi_free_sgtable(&cmd->sdb);
 
        memset(&cmd->sdb, 0, sizeof(cmd->sdb));
+
+       if (scsi_bidi_cmnd(cmd)) {
+               struct scsi_data_buffer *bidi_sdb =
+                       cmd->request->next_rq->special;
+               scsi_free_sgtable(bidi_sdb);
+               kmem_cache_free(scsi_bidi_sdb_cache, bidi_sdb);
+               cmd->request->next_rq->special = NULL;
+       }
 }
 EXPORT_SYMBOL(scsi_release_buffers);
 
+/*
+ * Bidi commands Must be complete as a whole, both sides at once.
+ * If part of the bytes were written and lld returned
+ * scsi_in()->resid and/or scsi_out()->resid this information will be left
+ * in req->data_len and req->next_rq->data_len. The upper-layer driver can
+ * decide what to do with this information.
+ */
+void scsi_end_bidi_request(struct scsi_cmnd *cmd)
+{
+       blk_end_bidi_request(cmd->request, 0, scsi_out(cmd)->resid,
+                                                       scsi_in(cmd)->resid);
+       scsi_release_buffers(cmd);
+
+       /*
+        * This will goose the queue request function at the end, so we don't
+        * need to worry about launching another command.
+        */
+       scsi_next_command(cmd);
+}
+
 /*
  * Function:    scsi_io_completion()
  *
@@ -854,9 +884,15 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
                                req->sense_len = len;
                        }
                }
+               if (scsi_bidi_cmnd(cmd)) {
+                       /* will also release_buffers */
+                       scsi_end_bidi_request(cmd);
+                       return;
+               }
                req->data_len = scsi_get_resid(cmd);
        }
 
+       BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */
        scsi_release_buffers(cmd);
 
        /*
@@ -982,28 +1018,16 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
        scsi_end_request(cmd, -EIO, this_count, !result);
 }
 
-/*
- * Function:    scsi_init_io()
- *
- * Purpose:     SCSI I/O initialize function.
- *
- * Arguments:   cmd   - Command descriptor we wish to initialize
- *
- * Returns:     0 on success
- *             BLKPREP_DEFER if the failure is retryable
- */
-int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
+static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
+                            gfp_t gfp_mask)
 {
-       struct request     *req = cmd->request;
-       int                count;
-       struct scsi_data_buffer *sdb = &cmd->sdb;
+       int count;
 
        /*
         * If sg table allocation fails, requeue request later.
         */
        if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
                                        gfp_mask))) {
-               scsi_unprep_request(req);
                return BLKPREP_DEFER;
        }
 
@@ -1022,6 +1046,50 @@ int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
        sdb->table.nents = count;
        return BLKPREP_OK;
 }
+
+/*
+ * Function:    scsi_init_io()
+ *
+ * Purpose:     SCSI I/O initialize function.
+ *
+ * Arguments:   cmd   - Command descriptor we wish to initialize
+ *
+ * Returns:     0 on success
+ *             BLKPREP_DEFER if the failure is retryable
+ *             BLKPREP_KILL if the failure is fatal
+ */
+int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
+{
+       int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask);
+       if (error)
+               goto err_exit;
+
+       if (blk_bidi_rq(cmd->request)) {
+               struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
+                       scsi_bidi_sdb_cache, GFP_ATOMIC);
+               if (!bidi_sdb) {
+                       error = BLKPREP_DEFER;
+                       goto err_exit;
+               }
+
+               cmd->request->next_rq->special = bidi_sdb;
+               error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb,
+                                                                   GFP_ATOMIC);
+               if (error)
+                       goto err_exit;
+       }
+
+       return BLKPREP_OK ;
+
+err_exit:
+       scsi_release_buffers(cmd);
+       if (error == BLKPREP_KILL)
+               scsi_put_command(cmd);
+       else /* BLKPREP_DEFER */
+               scsi_unprep_request(cmd->request);
+
+       return error;
+}
 EXPORT_SYMBOL(scsi_init_io);
 
 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
@@ -1639,6 +1707,14 @@ int __init scsi_init_queue(void)
                return -ENOMEM;
        }
 
+       scsi_bidi_sdb_cache = kmem_cache_create("scsi_bidi_sdb",
+                                       sizeof(struct scsi_data_buffer),
+                                       0, 0, NULL);
+       if (!scsi_bidi_sdb_cache) {
+               printk(KERN_ERR "SCSI: can't init scsi bidi sdb cache\n");
+               return -ENOMEM;
+       }
+
        for (i = 0; i < SG_MEMPOOL_NR; i++) {
                struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
                int size = sgp->size * sizeof(struct scatterlist);