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Re: [PATCH v2] block/backup-top: fix flags handling
From: |
Max Reitz |
Subject: |
Re: [PATCH v2] block/backup-top: fix flags handling |
Date: |
Thu, 6 Feb 2020 17:31:17 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 |
On 03.02.20 14:42, Vladimir Sementsov-Ogievskiy wrote:
> backup-top "supports" write-unchanged, by skipping CBW operation in
> backup_top_co_pwritev. But it forgets to do the same in
> backup_top_co_pwrite_zeroes, as well as declare support for
> BDRV_REQ_WRITE_UNCHANGED.
>
> Fix this, and, while being here, declare also support for flags
> supported by source child.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
>
> v2: restrict flags propagation like it is done in other filters [Eric]
> move state variable initialization to the top
>
> block/backup-top.c | 32 ++++++++++++++++++++------------
> 1 file changed, 20 insertions(+), 12 deletions(-)
>
> diff --git a/block/backup-top.c b/block/backup-top.c
> index 9aed2eb4c0..a4cec60859 100644
> --- a/block/backup-top.c
> +++ b/block/backup-top.c
[...]
> @@ -186,17 +190,21 @@ BlockDriverState
> *bdrv_backup_top_append(BlockDriverState *source,
> Error **errp)
> {
> Error *local_err = NULL;
> - BDRVBackupTopState *state;
> BlockDriverState *top = bdrv_new_open_driver(&bdrv_backup_top_filter,
> filter_node_name,
> BDRV_O_RDWR, errp);
> + BDRVBackupTopState *state = top->opaque;
>
> if (!top) {
> return NULL;
> }
If top can be NULL, then we shouldn’t dereference it before (with
state = top->opaque).
(Pulling up the initialization of @state is also unrelated to this
patch, I don’t exactly know why you’re doing it here.)
Max
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