Re: [Qemu-devel] [PATCH v5 4/6] block: Convert open calls to qemu_open

[Corey Bryant]

On 07/25/2012 03:22 PM, Eric Blake wrote:
> On 07/23/2012 07:08 AM, Corey Bryant wrote:
> > This patch converts all block layer open calls to qemu_open.
> >
> > Note that this adds the O_CLOEXEC flag to the changed open paths
> > when the O_CLOEXEC macro is defined.
>
> Is it actually adding O_CLOEXEC, or just the ability to use O_CLOEXEC?

It is adding O_CLOEXEC in qemu_open() on the open() call (as long as it 
is defined).

> Or is the actual change that the end result is that the fd now has
> FD_CLOEXEC set unconditionally, whether by O_CLOEXEC (which the caller
> need not pass) or by fcntl()?

The statement in the commit message isn't referring to anything dealing 
with qemu_dup(). The statement is specifically talking about the open() 
call in qemu_open(), and the point is to alert folks that old open() 
calls are now being routed through qemu_open() and likely are using the 
O_CLOEXEC flag, which is new behavior.

> > +++ b/block/raw-posix.c
> > @@ -572,8 +572,8 @@ static int raw_create(const char *filename, 
> > QEMUOptionParameter *options)
> >           options++;
> >       }
> >
> > -    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
> > -              0644);
> > +    fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
> > +                   0644);
>
> After all, I don't see O_CLOEXEC used here.

That's right.  qemu_open() adds O_CLOEXEC on the open() call.

> >       if (fd < 0) {
> >           result = -errno;
> >       } else {
> > @@ -846,7 +846,7 @@ static int hdev_open(BlockDriverState *bs, const char 
> > *filename, int flags)
> >           if ( bsdPath[ 0 ] != '\0' ) {
> >               strcat(bsdPath,"s0");
> >               /* some CDs don't have a partition 0 */
> > -            fd = open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
> > +            fd = qemu_open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
>
> Also, I still stand by my earlier claim that we don't need O_LARGEFILE
> here (we should already be configuring for 64-bit off_t by default),
> although cleaning that up is probably worth an independent commit.

I have a note to get rid of O_LARGEFILE as a separate follow-on patch.

> > +++ b/block/vdi.c
> > @@ -653,8 +653,9 @@ static int vdi_create(const char *filename, 
> > QEMUOptionParameter *options)
> >           options++;
> >       }
> >
> > -    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
> > -              0644);
> > +    fd = qemu_open(filename,
> > +                   O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
> > +                   0644);
>
> Another pointless O_LARGEFILE, and so forth.

Yep.

--
Regards,
Corey