On Fri, Jan 24, 2014 at 02:08:21PM +0100, Kevin Wolf wrote:
> bdrv_commit() could return 0 or 1 on success, depending on whether or
> now the last sector was allocated in the overlay and whether the overlay
> format had a .bdrv_make_empty callback.
>
> Most callers ignored it, but qemu-img commit would print an error
> message while the operation actually succeeded.
>
> Also clean up the handling of I/O errors to return the real error code
> instead of -EIO.
>
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> ---
> block.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/block.c b/block.c
> index 3e0994b..7d22ca9 100644
> --- a/block.c
> +++ b/block.c
> @@ -2061,13 +2061,13 @@ int bdrv_commit(BlockDriverState *bs)
> goto ro_cleanup;
> }
> if (ret) {
> - if (bdrv_read(bs, sector, buf, n) != 0) {
> - ret = -EIO;
> + ret = bdrv_read(bs, sector, buf, n);
> + if (ret < 0) {
> goto ro_cleanup;
> }
>
> - if (bdrv_write(bs->backing_hd, sector, buf, n) != 0) {
> - ret = -EIO;
> + ret = bdrv_write(bs->backing_hd, sector, buf, n);
> + if (ret < 0) {
> goto ro_cleanup;
> }
> }
> @@ -2075,6 +2075,9 @@ int bdrv_commit(BlockDriverState *bs)
>
> if (drv->bdrv_make_empty) {
> ret = drv->bdrv_make_empty(bs);
> + if (ret < 0) {
> + goto ro_cleanup;
> + }
QED has a .bdrv_make_empty implementation, but it is a stub that
always returns -ENOTSUP.
Prior to this patch, a commit of a QED snapshot would complete OK, but
return an error saying "Image is already committed" (Which almost
seems like a non-error error).
Now, we'll skip ahead to cleanup.
I think we should either: 1) filter out -ENOTSUP here, or 2) remove
the stub from QED
> bdrv_flush(bs);
> }
>
> @@ -2082,9 +2085,11 @@ int bdrv_commit(BlockDriverState *bs)
> * Make sure all data we wrote to the backing device is actually
> * stable on disk.
> */
> - if (bs->backing_hd)
> + if (bs->backing_hd) {
> bdrv_flush(bs->backing_hd);
> + }
>
> + ret = 0;
> ro_cleanup:
> g_free(buf);
>
> --
> 1.8.1.4
>
