Current write_zeroes implementation is good enough to satisfy this flag too

Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block/file-posix.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index 8d3ec96627..dac218ec7f 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -607,6 +607,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
         } else {
             s->discard_zeroes = true;
             s->has_fallocate = true;
+            bs->supported_zero_flags = BDRV_REQ_ALLOCATE;
         }
     } else {
         if (!(S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode))) {
@@ -650,10 +651,11 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
 #ifdef CONFIG_XFS
     if (platform_test_xfs_fd(s->fd)) {
         s->is_xfs = true;
+        bs->supported_zero_flags = BDRV_REQ_ALLOCATE;
     }
 #endif
 
-    bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP;
+    bs->supported_zero_flags |= BDRV_REQ_MAY_UNMAP;
     ret = 0;
 fail:
     if (filename && (bdrv_flags & BDRV_O_TEMPORARY)) {
@@ -1552,6 +1554,10 @@ static int handle_aiocb_write_zeroes(void *opaque)
     s->has_fallocate = false;
 #endif
 
+    if (!s->has_fallocate) {
+        aiocb->bs->supported_zero_flags &= ~BDRV_REQ_ALLOCATE;
+    }
+
     return -ENOTSUP;
 }
 
-- 
2.17.1