block: Use blk_co_flush() for all BB level flushes

All read/write functions already have a single coroutine-based function
on the BlockBackend level through which all requests go (no matter what
API style the external caller used) and which passes the requests down
to the block node level.

This patch extends this mode of operation to flushes.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

1 files changed, 17 insertions, 10 deletions

diff --git a/block/block-backend.c b/block/block-backend.c
index 1a724a8d89..96bb6340a0 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1099,14 +1099,19 @@ BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
                         blk_aio_write_entry, flags, cb, opaque);
 }
 
+static void blk_aio_flush_entry(void *opaque)
+{
+    BlkAioEmAIOCB *acb = opaque;
+    BlkRwCo *rwco = &acb->rwco;
+
+    rwco->ret = blk_co_flush(rwco->blk);
+    blk_aio_complete(acb);
+}
+
 BlockAIOCB *blk_aio_flush(BlockBackend *blk,
                           BlockCompletionFunc *cb, void *opaque)
 {
-    if (!blk_is_available(blk)) {
-        return blk_abort_aio_request(blk, cb, opaque, -ENOMEDIUM);
-    }
-
-    return bdrv_aio_flush(blk_bs(blk), cb, opaque);
+    return blk_aio_prwv(blk, 0, 0, NULL, blk_aio_flush_entry, 0, cb, opaque);
 }
 
 BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk,
@@ -1169,13 +1174,15 @@ int blk_co_flush(BlockBackend *blk)
     return bdrv_co_flush(blk_bs(blk));
 }
 
-int blk_flush(BlockBackend *blk)
+static void blk_flush_entry(void *opaque)
 {
-    if (!blk_is_available(blk)) {
-        return -ENOMEDIUM;
-    }
+    BlkRwCo *rwco = opaque;
+    rwco->ret = blk_co_flush(rwco->blk);
+}
 
-    return bdrv_flush(blk_bs(blk));
+int blk_flush(BlockBackend *blk)
+{
+    return blk_prw(blk, 0, NULL, 0, blk_flush_entry, 0);
 }
 
 void blk_drain(BlockBackend *blk)