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Date: Wed, 25 Mar 2015 13:55:23 +0100
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Subject: Re: [Qemu-devel] [RFC PATCH COLO v2 10/13] Backup: clear all bitmap
 when doing block checkpoint
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To: Wen Congyang <wency@cn.fujitsu.com>, qemu devel <qemu-devel@nongnu.org>, Fam Zheng <famz@redhat.com>, Max Reitz <mreitz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Lai Jiangshan <laijs@cn.fujitsu.com>, qemu block <qemu-block@nongnu.org>, Jeff Cody <jcody@redhat.com>, Jiang Yunhong <yunhong.jiang@intel.com>, Dong Eddie <eddie.dong@intel.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Gonglei <arei.gonglei@huawei.com>, Stefan Hajnoczi <stefanha@redhat.com>, Yang Hongyang <yanghy@cn.fujitsu.com>, zhanghailiang <zhang.zhanghailiang@huawei.com>



On 25/03/2015 10:36, Wen Congyang wrote:
> 
> +void backup_do_checkpoint(BlockJob *job, Error **errp)
> +{
> +    BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
> +
> +    if (job->driver != &backup_job_driver) {
> +        error_setg(errp, "It is not backup job");
> +        return;
> +    }
> +
> +    hbitmap_reset_all(backup_job->bitmap);
> +}

Please add instead a block_job_do_checkpoint API, and a do_checkpoint
function pointer to BlockJobDriver.

> +{
> +#if 0
> +    hbitmap_reset(hb, 0, hb->size << hb->granularity);
> +#else
> +    uint64_t size = hb->size;
> +    unsigned int i;
> +
> +    /* Same as hbitmap_alloc() except memset() */
> +    for (i = HBITMAP_LEVELS; i-- > 0; ) {

This can be "--i >= 1"...

> +        size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
> +        memset(hb->levels[i], 0, size * sizeof(unsigned long));
> +    }
> +
> +    assert(size == 1);
> +    hb->levels[0][0] |= 1UL << (BITS_PER_LONG - 1);

... if you use "=" instead of "|=" here.

> +#endif
> +}

Please pick one implementation (no #if), and also add a testcase to
tests/test-hbitmap.c.

Paolo