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Re: [Qemu-devel] [PATCH] Disable O_DIRECT for physical CDROM/DVD drives
From: |
Jes Sorensen |
Subject: |
Re: [Qemu-devel] [PATCH] Disable O_DIRECT for physical CDROM/DVD drives |
Date: |
Tue, 20 Jul 2010 18:04:01 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100621 Fedora/3.0.5-1.fc13 Lightning/1.0b2pre Thunderbird/3.0.5 |
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;
Cheers,
Jes
Re: [Qemu-devel] Re: [PATCH] Disable O_DIRECT for physical CDROM/DVD drives, Kevin Wolf, 2010/07/20