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Date: Fri, 14 Feb 2014 16:38:03 +0100
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20140214153802.GA23572@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2] block: gluster - code movements,
 state storage changes
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To: Jeff Cody <jcody@redhat.com>
Cc: kwolf@redhat.com, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org, bharata@linux.vnet.ibm.com

On Fri, Feb 14, 2014 at 09:41:46AM -0500, Jeff Cody wrote:
> On Fri, Feb 14, 2014 at 03:21:28PM +0100, Stefan Hajnoczi wrote:
> > On Tue, Feb 04, 2014 at 02:26:58PM -0500, Jeff Cody wrote:
> > > @@ -291,23 +311,17 @@ static int qemu_gluster_open(BlockDriverState *bs,  QDict *options,
> > >  
> > >      filename = qemu_opt_get(opts, "filename");
> > >  
> > > +    s->filename = g_strdup(filename);
> > 
> > It's not obvious to me that copying the filename is necessary.
> > block/raw-posix.c does this:
> > 
> >   raw_s->fd = qemu_open(state->bs->filename, raw_s->open_flags);
> > 
> > Why didn't you use bs->filename?
> >
> 
> Back when the raw-posix reopen was implemented, the .bdrv_file_open
> used the char * filename instead of options parameters.  Now that the
> filename is explicitly parsed via the options, I thought it made
> logical sense to cache the filename into the protocol state variable,
> for later use by reopen.
> 
> That way if the bs->filename was changed in some manner, the protocol
> would have the variable as originally intended to be passed to the
> .bdrv_file_open() method.
> 
> In reality, I should be able to just use bs->filename instead, as it
> does not get modified; this just seemed to make a bit more sense.

I thought about driver-specific options that are not part of 'filename',
too.  IMO it's simpler to use bs->filename until we actually use
driver-specific options, and then switch over to using bs->options
instead of copying.