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Date: Thu, 05 Dec 2013 19:35:43 +0100
From: Max Reitz <mreitz@redhat.com>
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Subject: Re: [Qemu-devel] [RFC] Using BlockdevRef in the block layer
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To: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>

On 05.12.2013 18:41, Max Reitz wrote:
> [=85]
>
> Second, if specifying a reference to an existing device should really=20
> be supported, bdrv_open() should ideally not call bdrv_file_open()=20
> anymore, but a function bdrv_find_ref() instead which resolves a=20
> BlockdevRef structure (for simplicity, it appears to be easier to use=20
> a QDict equivalent to a BlockdevRef instead of the latter itself=20
> (since that results in many effectively redundant conversions to and=20
> from those representations)). However, bdrv_file_open() supports=20
> parsing protocol filenames, which bdrv_find_ref() would not. As a=20
> result, it is probably best to call bdrv_find_ref() from=20
> bdrv_file_open() instead and leave bdrv_open() generally the way it is=20
> right now =96 yes, this is a question. ;-) (=93Do you agree?=94)

I noticed only just now that the current design does not seem to allow=20
nesting of files (i.e., driver=3Dblkdebug-qmp, file.driver=3Dqcow2,=20
file.file.driver=3Dfile). Perhaps I do have to call bdrv_find_ref() in=20
bdrv_open() and only resort to bdrv_file_open() if a filename that must=20
be parsed was given...?

Max