Re: [Qemu-devel] [RFC] Using BlockdevRef in the block layer

[Max Reitz]

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

I noticed only just now that the current design does not seem to allow 
nesting of files (i.e., driver=blkdebug-qmp, file.driver=qcow2, 
file.file.driver=file). Perhaps I do have to call bdrv_find_ref() in 
bdrv_open() and only resort to bdrv_file_open() if a filename that must 
be parsed was given...?

Max