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Re: [Qemu-devel] PATCH: Control over drive open modes for backing file
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] PATCH: Control over drive open modes for backing file |
Date: |
Thu, 31 Jul 2008 14:55:12 +0100 |
User-agent: |
Mutt/1.4.1i |
On Thu, Jul 31, 2008 at 02:46:55PM +0100, Paul Brook wrote:
> > +#define BDRV_O_RDONLY 0x0001 /* Force read-only */
> > +#define BDRV_O_WRONLY 0x0002 /* Force writeable, no fallback */
> > +#define BDRV_O_RDWR 0x0003 /* Try writeable, fallback to read-only
> > */
>
> This is IMHO really misleading. Normal O_* are not bitflags. The code uses
> these as bitflags sometimes, which means your descriptions are contradictory.
One alternative approach I considered would be to not have an explicit
flag for writable, and instead have a flag to explicitly indicate that
fallback to read-only shouldn't be attempted.
#define BDRV_O_RDONLY 0x0001
#define BDRV_O_NO_RO_FALLBACK 0x0002
This would probably make the patch smaller because I won't need to update
all the callers which assume flags of '0' gives a writable file, falling
back to RO.
Other suggestions welcome too...
Daniel
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Re: [Qemu-devel] PATCH: Control over drive open modes for backing file, Anthony Liguori, 2008/07/31