Re: [Qemu-devel] [PATCH 6/6] block: Fix permissions after bdrv_reopen()

[Eric Blake <eblake@redhat.com>]

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On 09/15/2017 05:10 AM, Kevin Wolf wrote:
> If we switch between read-only and read-write, the permissions that
> image format drivers need on bs->file change, too. Make sure to update
> the permissions during bdrv_reopen().
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  include/block/block.h |  1 +
>  block.c               | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 65 insertions(+)
> 

> +static BlockReopenQueueEntry *find_parent_in_reopen_queue(BlockReopenQueue *q,
> +                                                          BdrvChild *c)
> +{
> +    BlockReopenQueueEntry *entry;
> +
> +    QSIMPLEQ_FOREACH(entry, q, entry) {
> +        BlockDriverState *bs = entry->state.bs;
> +        BdrvChild *child;
> +
> +        QLIST_FOREACH(child, &bs->children, next) {
> +            if (child == c) {
> +                return entry;

An O(n^2) loop. Is it going to bite us at any point in the future, or
are we generally dealing with a small enough queue size and BDS graph to
not worry about it?

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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