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Date: Thu, 11 Jun 2009 18:00:30 +0200
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [Qemu-devel] [PATCH 2/4] raw-posix: add a raw_open_common helper
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To: Glauber Costa <glommer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, qemu-devel@nongnu.org

On Tue, Jun 09, 2009 at 04:54:49PM -0300, Glauber Costa wrote:
> > -
> > +    s->fd = -1;
> >      fd = open(filename, s->open_flags, 0644);
> >      if (fd < 0) {
> >          ret = -errno;
> it is not equivalent to the current code, while you claim it is.
> this one will return EROFS to the external world, while old code
> would return EACCES. If there is any user relying on that return value,
> we're screwed. And as a matter of fact, it appears to be (bdrv_open2)

The code to turn -EROFS into -EACCES is also present in raw_open (and
thus the new raw_open_common), it just didn't make it into the visible
patch hunk.

> > -    s->open_flags |= O_BINARY;
> > -    if ((flags & BDRV_O_ACCESS) == O_RDWR) {
> > -        s->open_flags |= O_RDWR;
> > -    } else {
> > -        s->open_flags |= O_RDONLY;
> > -        bs->read_only = 1;
> > -    }
> > -    /* Use O_DSYNC for write-through caching, no flags for write-back caching,
> > -     * and O_DIRECT for no caching. */
> > -    if ((flags & BDRV_O_NOCACHE))
> > -        s->open_flags |= O_DIRECT;
> > -    else if (!(flags & BDRV_O_CACHE_WB))
> > -        s->open_flags |= O_DSYNC;
> >  
> What happened to those flags? Are you just throwing them away?

raw_open_common deals with those, we just consolidated those to one
single site.