On Fri, May 18, 2012 at 3:18 PM, Paolo Bonzini <pbonz...@redhat.com> wrote:
> Formats are entirely in charge of flushes for metadata writes. For
> guest-initiated writes, a writethrough cache is faked in the block layer.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> block.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block.c b/block.c
> index 3db7150..b3d0054 100644
> --- a/block.c
> +++ b/block.c
> @@ -661,7 +661,7 @@ static int bdrv_open_common(BlockDriverState *bs, const
> char *filename,
> if (drv->bdrv_file_open) {
> ret = drv->bdrv_file_open(bs, filename, open_flags);
> } else {
> - ret = bdrv_file_open(&bs->file, filename, open_flags);
> + ret = bdrv_file_open(&bs->file, filename, open_flags &
> ~BDRV_O_CACHE_WB);
Do you really want to open image files with O_DSYNC? For example,
when I try these patches with -drive
if=virtio,file=test.img,cache=none I find that the image file file
descriptor has O_DSYNC set! That would make cache=none equivalent to
cache=directsync.
Stefan
