dma-helpers: change BlockBackend to opaque value in DMAIOFunc

Callers of dma_blk_io have no way to pass extra data to the DMAIOFunc,
because the original callback and opaque are gone by the time DMAIOFunc
is called.  On the other hand, the BlockBackend is usually derived
from those extra data that you could pass to the DMAIOFunc (in the
next patch, that would be the SCSIRequest).

So change DMAIOFunc's prototype, decoupling it from blk_aio_readv
and blk_aio_writev's.  The new prototype loses the BlockBackend
and gains an extra opaque value which, in the case of dma_blk_readv
and dma_blk_writev, is of course used for the BlockBackend.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 35 insertions, 13 deletions

diff --git a/dma-helpers.c b/dma-helpers.c
index af07aab..b521d84 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -70,7 +70,7 @@ void qemu_sglist_destroy(QEMUSGList *qsg)
 
 typedef struct {
     BlockAIOCB common;
-    BlockBackend *blk;
+    AioContext *ctx;
     BlockAIOCB *acb;
     QEMUSGList *sg;
     uint64_t offset;
@@ -80,6 +80,7 @@ typedef struct {
     QEMUIOVector iov;
     QEMUBH *bh;
     DMAIOFunc *io_func;
+    void *io_func_opaque;
 } DMAAIOCB;
 
 static void dma_blk_cb(void *opaque, int ret);
@@ -154,8 +155,7 @@ static void dma_blk_cb(void *opaque, int ret)
 
     if (dbs->iov.size == 0) {
         trace_dma_map_wait(dbs);
-        dbs->bh = aio_bh_new(blk_get_aio_context(dbs->blk),
-                             reschedule_dma, dbs);
+        dbs->bh = aio_bh_new(dbs->ctx, reschedule_dma, dbs);
         cpu_register_map_client(dbs->bh);
         return;
     }
@@ -164,8 +164,8 @@ static void dma_blk_cb(void *opaque, int ret)
         qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & ~BDRV_SECTOR_MASK);
     }
 
-    dbs->acb = dbs->io_func(dbs->blk, dbs->offset, &dbs->iov, 0,
-                            dma_blk_cb, dbs);
+    dbs->acb = dbs->io_func(dbs->offset, &dbs->iov,
+                            dma_blk_cb, dbs, dbs->io_func_opaque);
     assert(dbs->acb);
 }
 
@@ -191,23 +191,25 @@ static const AIOCBInfo dma_aiocb_info = {
     .cancel_async       = dma_aio_cancel,
 };
 
-BlockAIOCB *dma_blk_io(
-    BlockBackend *blk, QEMUSGList *sg, uint64_t offset,
-    DMAIOFunc *io_func, BlockCompletionFunc *cb,
+BlockAIOCB *dma_blk_io(AioContext *ctx,
+    QEMUSGList *sg, uint64_t offset,
+    DMAIOFunc *io_func, void *io_func_opaque,
+    BlockCompletionFunc *cb,
     void *opaque, DMADirection dir)
 {
-    DMAAIOCB *dbs = blk_aio_get(&dma_aiocb_info, blk, cb, opaque);
+    DMAAIOCB *dbs = qemu_aio_get(&dma_aiocb_info, NULL, cb, opaque);
 
-    trace_dma_blk_io(dbs, blk, offset, (dir == DMA_DIRECTION_TO_DEVICE));
+    trace_dma_blk_io(dbs, io_func_opaque, offset, (dir == DMA_DIRECTION_TO_DEVICE));
 
     dbs->acb = NULL;
-    dbs->blk = blk;
     dbs->sg = sg;
+    dbs->ctx = ctx;
     dbs->offset = offset;
     dbs->sg_cur_index = 0;
     dbs->sg_cur_byte = 0;
     dbs->dir = dir;
     dbs->io_func = io_func;
+    dbs->io_func_opaque = io_func_opaque;
     dbs->bh = NULL;
     qemu_iovec_init(&dbs->iov, sg->nsg);
     dma_blk_cb(dbs, 0);
@@ -215,19 +217,39 @@ BlockAIOCB *dma_blk_io(
 }
 
 
+static
+BlockAIOCB *dma_blk_read_io_func(int64_t offset, QEMUIOVector *iov,
+                                 BlockCompletionFunc *cb, void *cb_opaque,
+                                 void *opaque)
+{
+    BlockBackend *blk = opaque;
+    return blk_aio_preadv(blk, offset, iov, 0, cb, cb_opaque);
+}
+
 BlockAIOCB *dma_blk_read(BlockBackend *blk,
                          QEMUSGList *sg, uint64_t offset,
                          void (*cb)(void *opaque, int ret), void *opaque)
 {
-    return dma_blk_io(blk, sg, offset, blk_aio_preadv, cb, opaque,
+    return dma_blk_io(blk_get_aio_context(blk),
+                      sg, offset, dma_blk_read_io_func, blk, cb, opaque,
                       DMA_DIRECTION_FROM_DEVICE);
 }
 
+static
+BlockAIOCB *dma_blk_write_io_func(int64_t offset, QEMUIOVector *iov,
+                                  BlockCompletionFunc *cb, void *cb_opaque,
+                                  void *opaque)
+{
+    BlockBackend *blk = opaque;
+    return blk_aio_pwritev(blk, offset, iov, 0, cb, cb_opaque);
+}
+
 BlockAIOCB *dma_blk_write(BlockBackend *blk,
                           QEMUSGList *sg, uint64_t offset,
                           void (*cb)(void *opaque, int ret), void *opaque)
 {
-    return dma_blk_io(blk, sg, offset, blk_aio_pwritev, cb, opaque,
+    return dma_blk_io(blk_get_aio_context(blk),
+                      sg, offset, dma_blk_write_io_func, blk, cb, opaque,
                       DMA_DIRECTION_TO_DEVICE);
 }