commit 18eef3bc4eb80fee2cf4a9f18cb87784854d30c1
author Gerd Hoffmann <kraxel@redhat.com> Wed May 16 14:20:03 2012 +0200
committer Gerd Hoffmann <kraxel@redhat.com> Thu Jun 07 10:02:21 2012 +0200
tree 254dca7607a8072117859c1ec32db2d029691a49
parent 973002c11460efd3c17fe61a76711a103e30e1f9

scsi: prepare migration code for usb-storage support

usb-storage can't handle requests in one go as the data transfer can be
splitted into lots of usb packets.  Because of that there can be
normal in-flight requests at savevm time and we need to handle that.
With other scsi hba's this happens only in case i/o is stopped due to
errors and there are pending requests which need to be restarted
(req->retry = true).

So, first we need to save req->retry and then handle the req->retry =
false case.  Write requests are handled fine already.  For read requests
we have to save the buffer as we will not restart the request (and thus
not refill the buffer) on the target host.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/scsi-bus.c

diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c
index f10f3ec..4a79821 100644
--- a/hw/scsi-bus.c
+++ b/hw/scsi-bus.c
@@ -1507,10 +1507,9 @@
     QTAILQ_FOREACH(req, &s->requests, next) {
         assert(!req->io_canceled);
         assert(req->status == -1);
-        assert(req->retry);
         assert(req->enqueued);
 
-        qemu_put_sbyte(f, 1);
+        qemu_put_sbyte(f, req->retry ? 1 : 2);
         qemu_put_buffer(f, req->cmd.buf, sizeof(req->cmd.buf));
         qemu_put_be32s(f, &req->tag);
         qemu_put_be32s(f, &req->lun);
@@ -1528,8 +1527,9 @@
 {
     SCSIDevice *s = pv;
     SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, s->qdev.parent_bus);
+    int8_t sbyte;
 
-    while (qemu_get_sbyte(f)) {
+    while ((sbyte = qemu_get_sbyte(f)) > 0) {
         uint8_t buf[SCSI_CMD_BUF_SIZE];
         uint32_t tag;
         uint32_t lun;
@@ -1539,6 +1539,7 @@
         qemu_get_be32s(f, &tag);
         qemu_get_be32s(f, &lun);
         req = scsi_req_new(s, tag, lun, buf, NULL);
+        req->retry = (sbyte == 1);
         if (bus->info->load_request) {
             req->hba_private = bus->info->load_request(f, req);
         }
@@ -1547,7 +1548,6 @@
         }
 
         /* Just restart it later.  */
-        req->retry = true;
         scsi_req_enqueue_internal(req);
 
         /* At this point, the request will be kept alive by the reference

hw/scsi-disk.c

diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index 045c764..1691491 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -132,8 +132,14 @@
     qemu_put_be64s(f, &r->sector);
     qemu_put_be32s(f, &r->sector_count);
     qemu_put_be32s(f, &r->buflen);
-    if (r->buflen && r->req.cmd.mode == SCSI_XFER_TO_DEV) {
-        qemu_put_buffer(f, r->iov.iov_base, r->iov.iov_len);
+    if (r->buflen) {
+        if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
+            qemu_put_buffer(f, r->iov.iov_base, r->iov.iov_len);
+        } else if (!req->retry) {
+            uint32_t len = r->iov.iov_len;
+            qemu_put_be32s(f, &len);
+            qemu_put_buffer(f, r->iov.iov_base, r->iov.iov_len);
+        }
     }
 }
 
@@ -148,6 +154,12 @@
         scsi_init_iovec(r, r->buflen);
         if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
             qemu_get_buffer(f, r->iov.iov_base, r->iov.iov_len);
+        } else if (!r->req.retry) {
+            uint32_t len;
+            qemu_get_be32s(f, &len);
+            r->iov.iov_len = len;
+            assert(r->iov.iov_len <= r->buflen);
+            qemu_get_buffer(f, r->iov.iov_base, r->iov.iov_len);
         }
     }