[Qemu-devel] [PATCH 10/12] block: add bdrv_co_flush support

[Paolo Bonzini <pbonzini@redhat.com>]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block.c     |   53 ++++++++++++++++++++++++++++++++++++++++++-----------
 block_int.h |    1 +
 2 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/block.c b/block.c
index 43742b7..3f32f75 100644
--- a/block.c
+++ b/block.c
@@ -64,6 +64,9 @@ static BlockDriverAIOCB *bdrv_co_aio_readv_em(BlockDriverState *bs,
 static BlockDriverAIOCB *bdrv_co_aio_writev_em(BlockDriverState *bs,
         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
         BlockDriverCompletionFunc *cb, void *opaque);
+static BlockDriverAIOCB *bdrv_co_aio_flush_em(BlockDriverState *bs,
+                                              BlockDriverCompletionFunc *cb,
+                                              void *opaque);
 static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs,
                                          int64_t sector_num, int nb_sectors,
                                          QEMUIOVector *iov);
@@ -204,8 +207,18 @@ void bdrv_register(BlockDriver *bdrv)
         }
     }
 
-    if (!bdrv->bdrv_aio_flush)
-        bdrv->bdrv_aio_flush = bdrv_aio_flush_em;
+    if (bdrv->bdrv_aio_flush && !bdrv->bdrv_co_flush) {
+        /* Emulate coroutines by AIO */
+        bdrv->bdrv_co_flush = bdrv_co_flush_em;
+    }
+    if (!bdrv->bdrv_aio_flush) {
+        /* Emulate AIO by either coroutines or sync */
+        if (bdrv->bdrv_co_flush) {
+            bdrv->bdrv_aio_flush = bdrv_co_aio_flush_em;
+        } else {
+            bdrv->bdrv_aio_flush = bdrv_aio_flush_em;
+        }
+    }
 
     QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
 }
@@ -980,11 +993,6 @@ static inline bool bdrv_has_async_rw(BlockDriver *drv)
         || drv->bdrv_aio_readv != bdrv_aio_readv_em;
 }
 
-static inline bool bdrv_has_async_flush(BlockDriver *drv)
-{
-    return drv->bdrv_aio_flush != bdrv_aio_flush_em;
-}
-
 /* return < 0 if error. See bdrv_write() for the return codes */
 int bdrv_read(BlockDriverState *bs, int64_t sector_num,
               uint8_t *buf, int nb_sectors)
@@ -1713,8 +1721,8 @@ int bdrv_flush(BlockDriverState *bs)
         return 0;
     }
 
-    if (bs->drv && bdrv_has_async_flush(bs->drv) && qemu_in_coroutine()) {
-        return bdrv_co_flush_em(bs);
+    if (bs->drv && bs->drv->bdrv_co_flush && qemu_in_coroutine()) {
+        return bs->drv->bdrv_co_flush(bs);
     }
 
     if (bs->drv && bs->drv->bdrv_flush) {
@@ -2729,7 +2737,7 @@ static AIOPool bdrv_em_co_aio_pool = {
     .cancel             = bdrv_aio_co_cancel_em,
 };
 
-static void bdrv_co_rw_bh(void *opaque)
+static void bdrv_co_em_bh(void *opaque)
 {
     BlockDriverAIOCBCoroutine *acb = opaque;
 
@@ -2751,7 +2759,7 @@ static void coroutine_fn bdrv_co_rw(void *opaque)
             acb->req.nb_sectors, acb->req.qiov);
     }
 
-    acb->bh = qemu_bh_new(bdrv_co_rw_bh, acb);
+    acb->bh = qemu_bh_new(bdrv_co_em_bh, acb);
     qemu_bh_schedule(acb->bh);
 }
 
@@ -2794,6 +2802,29 @@ static BlockDriverAIOCB *bdrv_co_aio_writev_em(BlockDriverState *bs,
                                  true);
 }
 
+static void coroutine_fn bdrv_co_flush(void *opaque)
+{
+    BlockDriverAIOCBCoroutine *acb = opaque;
+    BlockDriverState *bs = acb->common.bs;
+
+    acb->req.error = bs->drv->bdrv_co_flush(bs);
+    acb->bh = qemu_bh_new(bdrv_co_em_bh, acb);
+    qemu_bh_schedule(acb->bh);
+}
+
+static BlockDriverAIOCB *bdrv_co_aio_flush_em(BlockDriverState *bs,
+                                              BlockDriverCompletionFunc *cb,
+                                              void *opaque)
+{
+    Coroutine *co;
+    BlockDriverAIOCBCoroutine *acb;
+
+    acb = qemu_aio_get(&bdrv_em_co_aio_pool, bs, cb, opaque);
+    co = qemu_coroutine_create(bdrv_co_flush);
+    qemu_coroutine_enter(co, acb);
+
+    return &acb->common;
+}
 static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,
         BlockDriverCompletionFunc *cb, void *opaque)
 {
diff --git a/block_int.h b/block_int.h
index 8a72b80..b0cd5ea 100644
--- a/block_int.h
+++ b/block_int.h
@@ -83,6 +83,7 @@ struct BlockDriver {
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
     int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
+    int coroutine_fn (*bdrv_co_flush)(BlockDriverState *bs);
 
     int (*bdrv_aio_multiwrite)(BlockDriverState *bs, BlockRequest *reqs,
         int num_reqs);
-- 
1.7.6