block: change flush to co_flush

Since coroutine operation is now mandatory, convert all bdrv_flush
implementations to coroutines.  For qcow2, this means taking the lock.
Other implementations are simpler and just forward bdrv_flush to the
underlying protocol, so they can avoid the lock.

The bdrv_flush callback is then unused and can be eliminated.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block.c

@@ -2892,8 +2892,6 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
             qemu_coroutine_yield();
             return co.ret;
         }
-    } else if (bs->drv->bdrv_flush) {
-        return bs->drv->bdrv_flush(bs);
     } else {
         /*
          * Some block drivers always operate in either writethrough or unsafe

block/cow.c

@@ -306,9 +306,9 @@ exit:
     return ret;
 }
 
-static int cow_flush(BlockDriverState *bs)
+static coroutine_fn int cow_co_flush(BlockDriverState *bs)
 {
-    return bdrv_flush(bs->file);
+    return bdrv_co_flush(bs->file);
 }
 
 static QEMUOptionParameter cow_create_options[] = {
@@ -334,7 +334,7 @@ static BlockDriver bdrv_cow = {
     .bdrv_write         = cow_co_write,
     .bdrv_close		= cow_close,
     .bdrv_create	= cow_create,
-    .bdrv_flush		= cow_flush,
+    .bdrv_co_flush      = cow_co_flush,
     .bdrv_is_allocated	= cow_is_allocated,
 
     .create_options = cow_create_options,

block/qcow.c

@@ -781,10 +781,9 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
     return 0;
 }
 
-static BlockDriverAIOCB *qcow_aio_flush(BlockDriverState *bs,
-        BlockDriverCompletionFunc *cb, void *opaque)
+static coroutine_fn int qcow_co_flush(BlockDriverState *bs)
 {
-    return bdrv_aio_flush(bs->file, cb, opaque);
+    return bdrv_co_flush(bs->file);
 }
 
 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
@@ -824,9 +823,9 @@ static BlockDriver bdrv_qcow = {
     .bdrv_is_allocated	= qcow_is_allocated,
     .bdrv_set_key	= qcow_set_key,
     .bdrv_make_empty	= qcow_make_empty,
-    .bdrv_co_readv  = qcow_co_readv,
-    .bdrv_co_writev = qcow_co_writev,
-    .bdrv_aio_flush	= qcow_aio_flush,
+    .bdrv_co_readv      = qcow_co_readv,
+    .bdrv_co_writev     = qcow_co_writev,
+    .bdrv_co_flush      = qcow_co_flush,
     .bdrv_write_compressed = qcow_write_compressed,
     .bdrv_get_info	= qcow_get_info,
 

block/qcow2.c

@@ -1099,24 +1099,24 @@ fail:
     return ret;
 }
 
-static BlockDriverAIOCB *qcow2_aio_flush(BlockDriverState *bs,
-                                         BlockDriverCompletionFunc *cb,
-                                         void *opaque)
+static int qcow2_co_flush(BlockDriverState *bs)
 {
     BDRVQcowState *s = bs->opaque;
     int ret;
 
+    qemu_co_mutex_lock(&s->lock);
     ret = qcow2_cache_flush(bs, s->l2_table_cache);
     if (ret < 0) {
-        return NULL;
+        return ret;
     }
 
     ret = qcow2_cache_flush(bs, s->refcount_block_cache);
     if (ret < 0) {
-        return NULL;
+        return ret;
     }
+    qemu_co_mutex_unlock(&s->lock);
 
-    return bdrv_aio_flush(bs->file, cb, opaque);
+    return bdrv_co_flush(bs->file);
 }
 
 static int64_t qcow2_vm_state_offset(BDRVQcowState *s)
@@ -1237,7 +1237,7 @@ static BlockDriver bdrv_qcow2 = {
 
     .bdrv_co_readv      = qcow2_co_readv,
     .bdrv_co_writev     = qcow2_co_writev,
-    .bdrv_aio_flush     = qcow2_aio_flush,
+    .bdrv_co_flush      = qcow2_co_flush,
 
     .bdrv_discard           = qcow2_discard,
     .bdrv_truncate          = qcow2_truncate,

block/raw-win32.c

@@ -281,7 +281,7 @@ static BlockDriver bdrv_file = {
     .bdrv_file_open	= raw_open,
     .bdrv_close		= raw_close,
     .bdrv_create	= raw_create,
-    .bdrv_flush		= raw_flush,
+    .bdrv_co_flush      = raw_flush,
     .bdrv_read		= raw_read,
     .bdrv_write		= raw_write,
     .bdrv_truncate	= raw_truncate,
@@ -409,7 +409,7 @@ static BlockDriver bdrv_host_device = {
     .bdrv_probe_device	= hdev_probe_device,
     .bdrv_file_open	= hdev_open,
     .bdrv_close		= raw_close,
-    .bdrv_flush		= raw_flush,
+    .bdrv_co_flush      = raw_flush,
     .bdrv_has_zero_init = hdev_has_zero_init,
 
     .bdrv_read		= raw_read,

block/rbd.c

@@ -705,7 +705,7 @@ static BlockDriverAIOCB *qemu_rbd_aio_writev(BlockDriverState *bs,
     return rbd_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
 }
 
-static int qemu_rbd_flush(BlockDriverState *bs)
+static int qemu_rbd_co_flush(BlockDriverState *bs)
 {
 #if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(0, 1, 1)
     /* rbd_flush added in 0.1.1 */
@@ -851,7 +851,7 @@ static BlockDriver bdrv_rbd = {
     .bdrv_file_open     = qemu_rbd_open,
     .bdrv_close         = qemu_rbd_close,
     .bdrv_create        = qemu_rbd_create,
-    .bdrv_flush         = qemu_rbd_flush,
+    .bdrv_co_flush      = qemu_rbd_co_flush,
     .bdrv_get_info      = qemu_rbd_getinfo,
     .create_options     = qemu_rbd_create_options,
     .bdrv_getlength     = qemu_rbd_getlength,

block/vdi.c

@@ -936,10 +936,10 @@ static void vdi_close(BlockDriverState *bs)
 {
 }
 
-static int vdi_flush(BlockDriverState *bs)
+static coroutine_fn int vdi_co_flush(BlockDriverState *bs)
 {
     logout("\n");
-    return bdrv_flush(bs->file);
+    return bdrv_co_flush(bs->file);
 }
 
 
@@ -975,7 +975,7 @@ static BlockDriver bdrv_vdi = {
     .bdrv_open = vdi_open,
     .bdrv_close = vdi_close,
     .bdrv_create = vdi_create,
-    .bdrv_flush = vdi_flush,
+    .bdrv_co_flush = vdi_co_flush,
     .bdrv_is_allocated = vdi_is_allocated,
     .bdrv_make_empty = vdi_make_empty,
 

block/vmdk.c

@@ -1494,14 +1494,14 @@ static void vmdk_close(BlockDriverState *bs)
     vmdk_free_extents(bs);
 }
 
-static int vmdk_flush(BlockDriverState *bs)
+static coroutine_fn int vmdk_co_flush(BlockDriverState *bs)
 {
     int i, ret, err;
     BDRVVmdkState *s = bs->opaque;
 
-    ret = bdrv_flush(bs->file);
+    ret = bdrv_co_flush(bs->file);
     for (i = 0; i < s->num_extents; i++) {
-        err = bdrv_flush(s->extents[i].file);
+        err = bdrv_co_flush(s->extents[i].file);
         if (err < 0) {
             ret = err;
         }
@@ -1568,7 +1568,7 @@ static BlockDriver bdrv_vmdk = {
     .bdrv_write     = vmdk_co_write,
     .bdrv_close     = vmdk_close,
     .bdrv_create    = vmdk_create,
-    .bdrv_flush     = vmdk_flush,
+    .bdrv_co_flush  = vmdk_co_flush,
     .bdrv_is_allocated  = vmdk_is_allocated,
     .bdrv_get_allocated_file_size  = vmdk_get_allocated_file_size,
 

block/vpc.c

@@ -467,9 +467,9 @@ static coroutine_fn int vpc_co_write(BlockDriverState *bs, int64_t sector_num,
     return ret;
 }
 
-static int vpc_flush(BlockDriverState *bs)
+static coroutine_fn int vpc_co_flush(BlockDriverState *bs)
 {
-    return bdrv_flush(bs->file);
+    return bdrv_co_flush(bs->file);
 }
 
 /*
@@ -665,7 +665,7 @@ static BlockDriver bdrv_vpc = {
     .bdrv_open      = vpc_open,
     .bdrv_read      = vpc_co_read,
     .bdrv_write     = vpc_co_write,
-    .bdrv_flush     = vpc_flush,
+    .bdrv_co_flush  = vpc_co_flush,
     .bdrv_close     = vpc_close,
     .bdrv_create    = vpc_create,
 

block_int.h

@@ -62,7 +62,6 @@ struct BlockDriver {
                       const uint8_t *buf, int nb_sectors);
     void (*bdrv_close)(BlockDriverState *bs);
     int (*bdrv_create)(const char *filename, QEMUOptionParameter *options);
-    int (*bdrv_flush)(BlockDriverState *bs);
     int (*bdrv_discard)(BlockDriverState *bs, int64_t sector_num,
                         int nb_sectors);
     int (*bdrv_is_allocated)(BlockDriverState *bs, int64_t sector_num,