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Date: Thu, 2 Oct 2014 12:55:34 +0200
From: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20141002105534.GB4888@noname.redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v5 04/23] block: Connect BlockBackend and
	DriveInfo
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To: Markus Armbruster <armbru@redhat.com>
Cc: mreitz@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, benoit.canet@nodalink.com

Am 02.10.2014 um 11:04 hat Markus Armbruster geschrieben:
> Make the BlockBackend own the DriveInfo.  Change blockdev_init() to
> return the BlockBackend instead of the DriveInfo.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Max Reitz <mreitz@redhat.com>

> @@ -200,11 +202,11 @@ DriveInfo *drive_get_next(BlockInterfaceType type)
>  
>  DriveInfo *drive_get_by_blockdev(BlockDriverState *bs)
>  {
> -    DriveInfo *dinfo;
> +    BlockBackend *blk;
>  
> -    QTAILQ_FOREACH(dinfo, &drives, next) {
> -        if (dinfo->bdrv == bs) {
> -            return dinfo;
> +    for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
> +        if (blk == bs->blk) {
> +            return blk_legacy_dinfo(blk);
>          }
>      }
>      return NULL;

In v3, I asked why you don't use bs->blk here. Apparently you understood
this as a suggestion to change the if condition from:

    if (blk_bs(blk) == bs)

to:

    if (blk == bs->blk)

Which isn't a wrong change, it just doesn't change a lot. What I really
meant is something like this, removing the loop:

    DriveInfo *drive_get_by_blockdev(BlockDriverState *bs)
    {
        return bs->blk ? blk_legacy_dinfo(bs->blk) : NULL;
    }

This would only behave differently if there were BlockBackends that can
be assigned to bs->blk, but aren't iterated by blk_next(). But such
BlockBackends don't exist, blk_next() includes all of them.

Kevin