On 26.08.19 18:13, Vladimir Sementsov-Ogievskiy wrote: > Backup-top filter caches write operations and does copy-before-write > operations. > > The driver will be used in backup instead of write-notifiers. > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > --- > block/backup-top.h | 37 +++++++ > block/backup-top.c | 245 ++++++++++++++++++++++++++++++++++++++++++++ > block/Makefile.objs | 2 + > 3 files changed, 284 insertions(+) > create mode 100644 block/backup-top.h > create mode 100644 block/backup-top.c
[...]
> +static void backup_top_refresh_filename(BlockDriverState *bs)
> +{
> + if (bs->backing == NULL) {
> + /*
> + * we can be here after failed bdrv_attach_child in
> + * bdrv_set_backing_hd
> + */
> + return;
> + }
> + bdrv_refresh_filename(bs->backing->bs);
bdrv_refresh_filename() should have done this already.
> + pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
> + bs->backing->bs->filename);
> +}
[...]
> +BlockDriverState *bdrv_backup_top_append(BlockDriverState *source,
> + const char *filter_node_name,
> + Error **errp)
> +{
[...]
> + assert(!(top->backing->shared_perm & BLK_PERM_WRITE));
Not wrong, but why?
> +
> + return top;
> +}
> +
> +void bdrv_backup_top_set_bcs(BlockDriverState *bs, BlockCopyState
> *copy_state)
> +{
> + BDRVBackupTopState *s = bs->opaque;
> +
> + assert(blk_bs(copy_state->source) == bs->backing->bs);
> + s->bcs = copy_state;
> +}
> +
> +void bdrv_backup_top_drop(BlockDriverState *bs)
> +{
> + AioContext *aio_context = bdrv_get_aio_context(bs);
> +
> + aio_context_acquire(aio_context);
> +
> + bdrv_drained_begin(bs);
> +
> + bdrv_child_try_set_perm(bs->backing, 0, BLK_PERM_ALL, &error_abort);
I would prefer a state->active = false and bdrv_child_refresh_perms().
Max
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