Am 18.09.2015 um 17:22 hat Max Reitz geschrieben:
> There are several BlockBackend functions which, in theory, cannot fail.
> This patch makes them cope with the BlockDriverState pointer being NULL
> by making them fall back to some default action like ignoring the value
> in setters and returning the default in getters.
>
> Signed-off-by: Max Reitz <[email protected]>
> Reviewed-by: Eric Blake <[email protected]>
Hm, okay, maybe bdrv_drain() belongs here. I just reviewed the end
result for completeness and didn't check which patch did what.
> int blk_enable_write_cache(BlockBackend *blk)
> {
> + if (!blk->bs) {
> + return 0;
> + }
> +
> return bdrv_enable_write_cache(blk->bs);
> }
>
> void blk_set_enable_write_cache(BlockBackend *blk, bool wce)
> {
> - bdrv_set_enable_write_cache(blk->bs, wce);
> + if (blk->bs) {
> + bdrv_set_enable_write_cache(blk->bs, wce);
> + }
> }
WCE is part of the open_flags in BlockBackendRootState. The root state
doesn't seem to be used yet, and I wrote about my concerns about it in
reply to an earlier patch, but as long as we have it, should this
query/modify the root state if no BDS is attached?
Kevin
