From: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170629132749.997-6-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vvfat.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index 4fd28e1..4dae790 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -3078,8 +3078,14 @@ static int coroutine_fn
 write_target_commit(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
                     QEMUIOVector *qiov, int flags)
 {
+    int ret;
+
     BDRVVVFATState* s = *((BDRVVVFATState**) bs->opaque);
-    return try_commit(s);
+    qemu_co_mutex_lock(&s->lock);
+    ret = try_commit(s);
+    qemu_co_mutex_unlock(&s->lock);
+
+    return ret;
 }
 
 static void write_target_close(BlockDriverState *bs) {
-- 
2.9.4