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Re: [Qemu-devel] [FIX V2] block: Fix device snapshots broken by the bloc
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [FIX V2] block: Fix device snapshots broken by the block filter snapshots patchset. |
Date: |
Tue, 11 Feb 2014 16:12:17 +0800 |
User-agent: |
Mutt/1.5.22 (2013-10-16) |
On Mon, 02/10 22:49, Benoît Canet wrote:
> Take into account the fact that a block filter like quorum will be in bs->file
> while a regular block driver device is really on the top level.
>
> Signed-off-by: Benoit Canet <address@hidden>
> ---
> block.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/block.c b/block.c
> index 07ac50a..d04f535 100644
> --- a/block.c
> +++ b/block.c
> @@ -5400,14 +5400,16 @@ bool bdrv_is_first_non_filter(BlockDriverState
> *candidate)
>
> /* walk down the bs forest recursively */
> QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> - bool perm;
> -
> - if (!bs->file) {
> - continue;
> + bool perm = false;
> +
> + if (bs->file &&
> + bs->file->drv &&
> + bs->file->drv->authorizations[BS_IS_A_FILTER]) {
> + perm = bdrv_recurse_is_first_non_filter(bs->file, candidate);
> + } else if (bs == candidate) {
> + perm = true;
> }
>
> - perm = bdrv_recurse_is_first_non_filter(bs->file, candidate);
> -
> /* candidate is the first non filter */
> if (perm) {
> return true;
With this change, if the top level driver has ->file, its implementation of
.bdrv_recurse_is_first_non_filter() is skipped and bs->file is the start point.
So we have an implication that single child block drivers (that has ->file)
doesn't need to, and shouldn't implement this operation, as commentted above
bdrv_generic_is_first_non_filter.
Tested that this patch fixes the external snapshot problem, but didn't test
the "quorum as bs->file case".
Thanks,
Reviewed-by: Fam Zheng <address@hidden>