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Date: Tue, 20 Jul 2010 18:12:49 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] Disable O_DIRECT for physical CDROM/DVD
	drives
References: <1279639056-20465-1-git-send-email-Jes.Sorensen@redhat.com>
	<4C45C350.9000707@redhat.com> <4C45C8F1.9070705@redhat.com>
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To: Jes Sorensen <Jes.Sorensen@redhat.com>
Cc: qemu-devel@nongnu.org

Am 20.07.2010 18:04, schrieb Jes Sorensen:
> On 07/20/10 17:40, Kevin Wolf wrote:
>>> diff --git a/block/raw-posix.c b/block/raw-posix.c
>>> index 291699f..0ea79b6 100644
>>> --- a/block/raw-posix.c
>>> +++ b/block/raw-posix.c
>>> @@ -1139,6 +1139,11 @@ static int cdrom_open(BlockDriverState *bs, const char *filename, int flags)
>>>      BDRVRawState *s = bs->opaque;
>>>  
>>>      s->type = FTYPE_CD;
>>> +    if (flags & BDRV_O_NOCACHE) {
>>> +        fprintf(stderr, "Disabling unsupported O_DIRECT (cache=none) for "
>>> +                "CDROM/DVD device (%s)\n", filename);
>>> +        flags &= ~BDRV_O_NOCACHE;
>>> +    }
>>
>> Good point. Just one detail: We should probably change bs->open_flags,
>> too, to keep things consistent.
> 
> Thats effectively what my patch does. cdrom_open() calls
> raw_open_common() which has this part:
> 
>     /* Use O_DSYNC for write-through caching, no flags for write-back
> caching,
>      * and O_DIRECT for no caching. */
>     if ((bdrv_flags & BDRV_O_NOCACHE))
>         s->open_flags |= O_DIRECT;

s and bs both have a field open_flags (and I think they share some more
field names, which has caused confusion more than once). I meant the bs
one here.

Kevin