Set has_discard only when BDRV_O_UNMAP is not set. With this users that want to keep their images fully allocated can disable hole punching when writing zeros or discarding using:
-drive file=thick.img,discard=off This change is not entirely correct since it changes the default discard behavior. Previously we always allowed punching holes, but now you have must use discard=unmap|on to enable it. We probably need to add the BDDR_O_UNMAP flag by default. make check still works, so maybe we don't have tests for sparsifying images, or maybe you need to run special tests that do not run by default. We needs tests for keeping images non-sparse. Signed-off-by: Nir Soffer <nsof...@redhat.com> --- block/file-posix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/file-posix.c b/block/file-posix.c index be25e35ff6..acac2abadc 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -738,11 +738,11 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, ret = -EINVAL; goto fail; } #endif /* !defined(CONFIG_LINUX_IO_URING) */ - s->has_discard = true; + s->has_discard = !!(bdrv_flags & BDRV_O_UNMAP); s->has_write_zeroes = true; if (fstat(s->fd, &st) < 0) { ret = -errno; error_setg_errno(errp, errno, "Could not stat file"); -- 2.45.1