[Qemu-devel] [PATCH 2/7] dma-helpers: change BlockBackend to opaque value in DMAIOFunc

[Paolo Bonzini <pbonzini@redhat.com>]

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>
---
 dma-helpers.c        | 48 +++++++++++++++++++++++++++++++++++-------------
 hw/ide/core.c        | 14 ++++++++------
 hw/ide/internal.h    |  6 +++---
 hw/ide/macio.c       |  2 +-
 include/sysemu/dma.h | 12 ++++++------
 5 files changed, 53 insertions(+), 29 deletions(-)

diff --git a/dma-helpers.c b/dma-helpers.c
index af07aab..92c5d55 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 opaque,
+    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);
 }
 
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 7326189..029f6b9 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -441,13 +441,14 @@ static void ide_issue_trim_cb(void *opaque, int ret)
     }
 }
 
-BlockAIOCB *ide_issue_trim(BlockBackend *blk,
-        int64_t offset, QEMUIOVector *qiov, BdrvRequestFlags flags,
-        BlockCompletionFunc *cb, void *opaque)
+BlockAIOCB *ide_issue_trim(
+        int64_t offset, QEMUIOVector *qiov,
+        BlockCompletionFunc *cb, void *cb_opaque, void *opaque)
 {
+    BlockBackend *blk = opaque;
     TrimAIOCB *iocb;
 
-    iocb = blk_aio_get(&trim_aiocb_info, blk, cb, opaque);
+    iocb = blk_aio_get(&trim_aiocb_info, blk, cb, cb_opaque);
     iocb->blk = blk;
     iocb->bh = qemu_bh_new(ide_trim_bh_cb, iocb);
     iocb->ret = 0;
@@ -871,8 +872,9 @@ static void ide_dma_cb(void *opaque, int ret)
                                            ide_dma_cb, s);
         break;
     case IDE_DMA_TRIM:
-        s->bus->dma->aiocb = dma_blk_io(s->blk, &s->sg, offset,
-                                        ide_issue_trim, ide_dma_cb, s,
+        s->bus->dma->aiocb = dma_blk_io(blk_get_aio_context(s->blk),
+                                        &s->sg, offset,
+                                        ide_issue_trim, s->blk, ide_dma_cb, s,
                                         DMA_DIRECTION_TO_DEVICE);
         break;
     default:
diff --git a/hw/ide/internal.h b/hw/ide/internal.h
index ceb9e59..773928a 100644
--- a/hw/ide/internal.h
+++ b/hw/ide/internal.h
@@ -613,9 +613,9 @@ void ide_transfer_start(IDEState *s, uint8_t *buf, int size,
                         EndTransferFunc *end_transfer_func);
 void ide_transfer_stop(IDEState *s);
 void ide_set_inactive(IDEState *s, bool more);
-BlockAIOCB *ide_issue_trim(BlockBackend *blk,
-        int64_t offset, QEMUIOVector *qiov, BdrvRequestFlags flags,
-        BlockCompletionFunc *cb, void *opaque);
+BlockAIOCB *ide_issue_trim(
+        int64_t offset, QEMUIOVector *qiov,
+        BlockCompletionFunc *cb, void *cb_opaque, void *opaque);
 BlockAIOCB *ide_buffered_readv(IDEState *s, int64_t sector_num,
                                QEMUIOVector *iov, int nb_sectors,
                                BlockCompletionFunc *cb, void *opaque);
diff --git a/hw/ide/macio.c b/hw/ide/macio.c
index d7d9c0f..42ad68a 100644
--- a/hw/ide/macio.c
+++ b/hw/ide/macio.c
@@ -230,7 +230,7 @@ static void pmac_dma_trim(BlockBackend *blk,
     s->io_buffer_index += io->len;
     io->len = 0;
 
-    s->bus->dma->aiocb = ide_issue_trim(blk, offset, &io->iov, 0, cb, io);
+    s->bus->dma->aiocb = ide_issue_trim(offset, &io->iov, cb, io, blk);
 }
 
 static void pmac_ide_atapi_transfer_cb(void *opaque, int ret)
diff --git a/include/sysemu/dma.h b/include/sysemu/dma.h
index f0e0c30..34c8eaf 100644
--- a/include/sysemu/dma.h
+++ b/include/sysemu/dma.h
@@ -194,14 +194,14 @@ void qemu_sglist_add(QEMUSGList *qsg, dma_addr_t base, dma_addr_t len);
 void qemu_sglist_destroy(QEMUSGList *qsg);
 #endif
 
-typedef BlockAIOCB *DMAIOFunc(BlockBackend *blk, int64_t offset,
-                              QEMUIOVector *iov, BdrvRequestFlags flags,
-                              BlockCompletionFunc *cb, void *opaque);
+typedef BlockAIOCB *DMAIOFunc(int64_t offset, QEMUIOVector *iov,
+                              BlockCompletionFunc *cb, void *cb_opaque,
+                              void *opaque);
 
-BlockAIOCB *dma_blk_io(BlockBackend *blk,
+BlockAIOCB *dma_blk_io(AioContext *ctx,
                        QEMUSGList *sg, uint64_t offset,
-                       DMAIOFunc *io_func, BlockCompletionFunc *cb,
-                       void *opaque, DMADirection dir);
+                       DMAIOFunc *io_func, void *io_func_opaque,
+                       BlockCompletionFunc *cb, void *opaque, DMADirection dir);
 BlockAIOCB *dma_blk_read(BlockBackend *blk,
                          QEMUSGList *sg, uint64_t offset,
                          BlockCompletionFunc *cb, void *opaque);
-- 
2.5.5