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Date: Thu, 27 Mar 2014 16:43:52 +0100
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20140327154352.GB2441@stefanha-thinkpad.redhat.com>
References: <1395911388-31027-1-git-send-email-famz@redhat.com>
	<1395911388-31027-3-git-send-email-famz@redhat.com>
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In-Reply-To: <1395911388-31027-3-git-send-email-famz@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v4 2/9] qmp: Add dirty-bitmap-add and
 dirty-bitmap-remove
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To: Fam Zheng <famz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Benoit Canet <benoit@irqsave.net>

On Thu, Mar 27, 2014 at 05:09:41PM +0800, Fam Zheng wrote:
> @@ -1713,6 +1713,66 @@ void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
>      }
>  }
>  
> +void qmp_dirty_bitmap_add(const char *device, const char *name,
> +                          bool has_granularity, int64_t granularity,
> +                          Error **errp)
> +{
> +    BlockDriverState *bs;
> +    BdrvDirtyBitmap *bitmap;
> +
> +    bs = bdrv_find(device);
> +    if (!bs) {
> +        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
> +        return;
> +    }
> +
> +    if (!name || name[0] == '\0') {
> +        error_setg(errp, "Bitmap name cannot be empty");
> +        return;
> +    }
> +    if (has_granularity) {
> +        if (granularity & (granularity - 1)) {
> +            error_setg(errp, "Granularity must be power of 2");
> +            return;
> +        }

granularity must be non-zero, otherwise bdrv_create_dirty_bitmap() hits
an assertion failure.

It should probably also be at least 512.

> +    } else {
> +        granularity = 65536;
> +    }
> +
> +    bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
> +    if (!bitmap) {
> +        return;
> +    }

Useless error return.

> +}
> +
> +void qmp_dirty_bitmap_remove(const char *device, const char *name,
> +                             Error **errp)
> +{
> +    BlockDriverState *bs;
> +    BdrvDirtyBitmap *bitmap;
> +
> +    bs = bdrv_find(device);
> +    if (!bs) {
> +        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
> +        return;
> +    }
> +
> +    if (!name || name[0] == '\0') {
> +        error_setg(errp, "Bitmap name cannot be empty");
> +        return;
> +    }
> +    bitmap = bdrv_find_dirty_bitmap(bs, name);
> +    if (!bitmap) {
> +        error_setg(errp, "Dirty bitmap not found: %s", name);
> +        return;
> +    }
> +
> +    /* Make it invisible to user in case the following
> +     * bdrv_release_dirty_bitmap doens't free it because of refcnt */

"doesn't"