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-rw-r--r--block.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/block.c b/block.c
index 85ef6af883..753811288a 100644
--- a/block.c
+++ b/block.c
@@ -1758,8 +1758,8 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset,
return ret;
}
- /* No flush needed for cache modes that use O_DSYNC */
- if ((bs->open_flags & BDRV_O_CACHE_WB) != 0) {
+ /* No flush needed for cache modes that already do it */
+ if (bs->enable_write_cache) {
bdrv_flush(bs);
}
@@ -1808,6 +1808,9 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BlockDriverState *bs,
ret = bdrv_co_do_write_zeroes(bs, cluster_sector_num,
cluster_nb_sectors);
} else {
+ /* This does not change the data on the disk, it is not necessary
+ * to flush even in cache=writethrough mode.
+ */
ret = drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors,
&bounce_qiov);
}
@@ -1977,6 +1980,10 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
}
+ if (ret == 0 && !bs->enable_write_cache) {
+ ret = bdrv_co_flush(bs);
+ }
+
if (bs->dirty_bitmap) {
set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
}