[Qemu-devel] [PATCH 10/10] scsi-disk: enable scatter/gather functionality

[Paolo Bonzini <pbonzini@redhat.com>]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/scsi-disk.c |   52 +++++++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index 509407f..81117d2 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -37,6 +37,7 @@ do { fprintf(stderr, "scsi-disk: " fmt , ## __VA_ARGS__); } while (0)
 #include "scsi-defs.h"
 #include "sysemu.h"
 #include "blockdev.h"
+#include "dma.h"
 
 #define SCSI_DMA_BUF_SIZE    131072
 #define SCSI_MAX_INQUIRY_LEN 256
@@ -123,6 +124,25 @@ static uint32_t scsi_init_iovec(SCSIDiskReq *r)
     return r->qiov.size / 512;
 }
 
+static void scsi_dma_complete(void *opaque, int ret)
+{
+    SCSIDiskReq *r = (SCSIDiskReq *)opaque;
+
+    r->req.resid = qemu_sglist_get_resid(r->req.sg);
+    r->req.aiocb = NULL;
+    if (ret) {
+        int is_read = (r->req.cmd.mode == SCSI_XFER_FROM_DEV);
+        int retry = is_read ? SCSI_REQ_STATUS_RETRY_READ : SCSI_REQ_STATUS_RETRY_WRITE;
+        if (scsi_handle_rw_error(r, -ret, retry)) {
+            return;
+        }
+    }
+
+    r->sector += r->sector_count;
+    r->sector_count = 0;
+    scsi_req_complete(&r->req, GOOD);
+}
+
 static void scsi_read_complete(void * opaque, int ret)
 {
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
@@ -174,9 +194,14 @@ static void scsi_read_data(SCSIRequest *req)
         return;
     }
 
-    n = scsi_init_iovec(r);
-    r->req.aiocb = bdrv_aio_readv(s->bs, r->sector, &r->qiov, n,
-                              scsi_read_complete, r);
+    if (r->req.sg) {
+        r->req.aiocb = dma_bdrv_read(s->bs, r->req.sg, r->sector,
+                                     scsi_dma_complete, r);
+    } else {
+        n = scsi_init_iovec(r);
+        r->req.aiocb = bdrv_aio_readv(s->bs, r->sector, &r->qiov, n,
+                                      scsi_read_complete, r);
+    }
     if (r->req.aiocb == NULL) {
         scsi_read_complete(r, -EIO);
     }
@@ -258,16 +283,21 @@ static void scsi_write_data(SCSIRequest *req)
         return;
     }
 
-    n = r->qiov.size / 512;
-    if (n) {
+    if (r->req.sg) {
+        r->req.aiocb = dma_bdrv_write(s->bs, r->req.sg, r->sector,
+                                      scsi_dma_complete, r);
+    } else {
+        n = r->qiov.size / 512;
+        if (!n) {
+            /* Called for the first time.  Ask the driver to send us more data.  */
+            scsi_write_complete(r, 0);
+            return;
+        }
         r->req.aiocb = bdrv_aio_writev(s->bs, r->sector, &r->qiov, n,
                                        scsi_write_complete, r);
-        if (r->req.aiocb == NULL) {
-            scsi_write_complete(r, -ENOMEM);
-        }
-    } else {
-        /* Called for the first time.  Ask the driver to send us more data.  */
-        scsi_write_complete(r, 0);
+    }
+    if (r->req.aiocb == NULL) {
+        scsi_write_complete(r, -ENOMEM);
     }
 }
 
-- 
1.7.6