On Sat 21 Apr 2018 03:29:21 PM CEST, Max Reitz wrote:
> This adds a simple copy-on-read filter driver. It relies on the already
> existing COR functionality in the central block layer code, which may be
> moved here once we no longer need it there.
>
> Signed-off-by: Max Reitz <mre...@redhat.com>
> +#define PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
> + | BLK_PERM_WRITE \
> + | BLK_PERM_RESIZE)
> +#define PERM_UNCHANGED (BLK_PERM_ALL & ~PERM_PASSTHROUGH)
> +
> +static void cor_child_perm(BlockDriverState *bs, BdrvChild *c,
> + const BdrvChildRole *role,
> + BlockReopenQueue *reopen_queue,
> + uint64_t perm, uint64_t shared,
> + uint64_t *nperm, uint64_t *nshared)
> +{
> + if (c == NULL) {
> + *nperm = (perm & PERM_PASSTHROUGH) | BLK_PERM_WRITE_UNCHANGED;
> + *nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED;
> + return;
> + }
> +
> + *nperm = (perm & PERM_PASSTHROUGH) |
> + (c->perm & PERM_UNCHANGED);
I admit I'm not completely familiar with this, but don't you need to add
BLK_PERM_WRITE_UNCHANGED to *nperm ?
> + *nshared = (shared & PERM_PASSTHROUGH) |
> + (c->shared_perm & PERM_UNCHANGED);
> +}
Berto
