diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c
index af95670..0ad466e 100644
--- a/hw/scsi-bus.c
+++ b/hw/scsi-bus.c
@@ -133,12 +133,12 @@
     return res;
 }
 
-SCSIRequest *scsi_req_alloc(size_t size, SCSIDevice *d, uint32_t tag,
+SCSIRequest *scsi_req_alloc(SCSIReqOps *reqops, SCSIDevice *d, uint32_t tag,
                             uint32_t lun, void *hba_private)
 {
     SCSIRequest *req;
 
-    req = qemu_mallocz(size);
+    req = qemu_mallocz(reqops->size);
     req->refcount = 1;
     req->bus = scsi_bus_from_device(d);
     req->dev = d;
@@ -147,6 +147,7 @@
     req->hba_private = hba_private;
     req->status = -1;
     req->sense_len = 0;
+    req->ops = reqops;
     trace_scsi_req_alloc(req->dev->id, req->lun, req->tag);
     return req;
 }
diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index e266d6f..dddc1f3 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -76,19 +76,6 @@
 static int scsi_handle_rw_error(SCSIDiskReq *r, int error, int type);
 static int scsi_disk_emulate_command(SCSIDiskReq *r, uint8_t *outbuf);
 
-static SCSIRequest *scsi_new_request(SCSIDevice *d, uint32_t tag,
-                                     uint32_t lun, void *hba_private)
-{
-    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, d);
-    SCSIRequest *req;
-    SCSIDiskReq *r;
-
-    req = scsi_req_alloc(sizeof(SCSIDiskReq), &s->qdev, tag, lun, hba_private);
-    r = DO_UPCAST(SCSIDiskReq, req, req);
-    r->iov.iov_base = qemu_blockalign(s->bs, SCSI_DMA_BUF_SIZE);
-    return req;
-}
-
 static void scsi_free_request(SCSIRequest *req)
 {
     SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);
@@ -1225,6 +1212,23 @@
     return scsi_initfn(dev, scsi_type);
 }
 
+static SCSIReqOps scsi_disk_reqops = {
+    .size         = sizeof(SCSIDiskReq),
+};
+
+static SCSIRequest *scsi_new_request(SCSIDevice *d, uint32_t tag,
+                                     uint32_t lun, void *hba_private)
+{
+    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, d);
+    SCSIRequest *req;
+    SCSIDiskReq *r;
+
+    req = scsi_req_alloc(&scsi_disk_reqops, &s->qdev, tag, lun, hba_private);
+    r = DO_UPCAST(SCSIDiskReq, req, req);
+    r->iov.iov_base = qemu_blockalign(s->bs, SCSI_DMA_BUF_SIZE);
+    return req;
+}
+
 #define DEFINE_SCSI_DISK_PROPERTIES()                           \
     DEFINE_BLOCK_PROPERTIES(SCSIDiskState, qdev.conf),          \
     DEFINE_PROP_STRING("ver",  SCSIDiskState, version),         \
diff --git a/hw/scsi-generic.c b/hw/scsi-generic.c
index 37c5982..80d1601 100644
--- a/hw/scsi-generic.c
+++ b/hw/scsi-generic.c
@@ -63,15 +63,6 @@
     int lun;
 };
 
-static SCSIRequest *scsi_new_request(SCSIDevice *d, uint32_t tag, uint32_t lun,
-                                     void *hba_private)
-{
-    SCSIRequest *req;
-
-    req = scsi_req_alloc(sizeof(SCSIGenericReq), d, tag, lun, hba_private);
-    return req;
-}
-
 static void scsi_free_request(SCSIRequest *req)
 {
     SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
@@ -498,6 +489,19 @@
     return 0;
 }
 
+static SCSIReqOps scsi_generic_req_ops = {
+    .size         = sizeof(SCSIGenericReq),
+};
+
+static SCSIRequest *scsi_new_request(SCSIDevice *d, uint32_t tag, uint32_t lun,
+                                     void *hba_private)
+{
+    SCSIRequest *req;
+
+    req = scsi_req_alloc(&scsi_generic_req_ops, d, tag, lun, hba_private);
+    return req;
+}
+
 static SCSIDeviceInfo scsi_generic_info = {
     .qdev.name    = "scsi-generic",
     .qdev.desc    = "pass through generic scsi device (/dev/sg*)",
diff --git a/hw/scsi.h b/hw/scsi.h
index c1cb987..ee76c64 100644
--- a/hw/scsi.h
+++ b/hw/scsi.h
@@ -14,6 +14,7 @@
 typedef struct SCSIDevice SCSIDevice;
 typedef struct SCSIDeviceInfo SCSIDeviceInfo;
 typedef struct SCSIRequest SCSIRequest;
+typedef struct SCSIReqOps SCSIReqOps;
 
 enum SCSIXferMode {
     SCSI_XFER_NONE,      /*  TEST_UNIT_READY, ...            */
@@ -32,6 +33,7 @@
 struct SCSIRequest {
     SCSIBus           *bus;
     SCSIDevice        *dev;
+    SCSIReqOps        *ops;
     uint32_t          refcount;
     uint32_t          tag;
     uint32_t          lun;
@@ -69,6 +71,10 @@
 int cdrom_read_toc_raw(int nb_sectors, uint8_t *buf, int msf, int session_num);
 
 /* scsi-bus.c */
+struct SCSIReqOps {
+    size_t size;
+};
+
 typedef int (*scsi_qdev_initfn)(SCSIDevice *dev);
 struct SCSIDeviceInfo {
     DeviceInfo qdev;
@@ -144,7 +150,7 @@
 
 int scsi_sense_valid(SCSISense sense);
 
-SCSIRequest *scsi_req_alloc(size_t size, SCSIDevice *d, uint32_t tag,
+SCSIRequest *scsi_req_alloc(SCSIReqOps *reqops, SCSIDevice *d, uint32_t tag,
                             uint32_t lun, void *hba_private);
 SCSIRequest *scsi_req_new(SCSIDevice *d, uint32_t tag, uint32_t lun,
                           void *hba_private);