From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:36606)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1TCC2R-0002JA-KA
	for qemu-devel@nongnu.org; Thu, 13 Sep 2012 12:13:17 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1TCC2K-0006dt-Ph
	for qemu-devel@nongnu.org; Thu, 13 Sep 2012 12:13:11 -0400
Received: from mx1.redhat.com ([209.132.183.28]:7416)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1TCC2K-0006dh-G1
	for qemu-devel@nongnu.org; Thu, 13 Sep 2012 12:13:04 -0400
Message-ID: <5052060A.5010304@redhat.com>
Date: Thu, 13 Sep 2012 18:12:58 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <cover.1347548248.git.jcody@redhat.com>
	<01df3140216ac0398bfb3a295c553c42cdf31e5b.1347548248.git.jcody@redhat.com>
In-Reply-To: <01df3140216ac0398bfb3a295c553c42cdf31e5b.1347548248.git.jcody@redhat.com>
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v2 06/16] block: do not parse
 BDRV_O_CACHE_WB in raw block drivers
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Jeff Cody <jcody@redhat.com>
Cc: kwolf@redhat.com, supriyak@linux.vnet.ibm.com, eblake@redhat.com, qemu-devel@nongnu.org, stefanha@gmail.com

Il 13/09/2012 17:49, Jeff Cody ha scritto:
> Block drivers should always open the files in writeback mode (see commit
> e1e9b0ac), so raw-posix/raw-win32 should not parse the BDRV_O_CACHE_WB
> flag.
> 
> Signed-off-by: Jeff Cody <jcody@redhat.com>
> ---
>  block/raw-posix.c | 3 ---
>  block/raw-win32.c | 3 ---
>  2 files changed, 6 deletions(-)
> 
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index 7d3ac9d..4a1047c 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -202,9 +202,6 @@ static void raw_parse_flags(int bdrv_flags, int *open_flags)
>      if ((bdrv_flags & BDRV_O_NOCACHE)) {
>          *open_flags |= O_DIRECT;
>      }
> -    if (!(bdrv_flags & BDRV_O_CACHE_WB)) {
> -        *open_flags |= O_DSYNC;
> -    }
>  }
>  
>  static int raw_set_aio(void **aio_ctx, int *use_aio, int bdrv_flags)
> diff --git a/block/raw-win32.c b/block/raw-win32.c
> index 335c06a..78c8306 100644
> --- a/block/raw-win32.c
> +++ b/block/raw-win32.c
> @@ -92,9 +92,6 @@ static void raw_parse_flags(int flags, int *access_flags, DWORD *overlapped)
>      if (flags & BDRV_O_NOCACHE) {
>          *overlapped |= FILE_FLAG_NO_BUFFERING;
>      }
> -    if (!(flags & BDRV_O_CACHE_WB)) {
> -        *overlapped |= FILE_FLAG_WRITE_THROUGH;
> -    }
>  }
>  
>  static int raw_open(BlockDriverState *bs, const char *filename, int flags)
> 

Why does this matter?  If raw-posix was opened directly (i.e. without
the bs->file indirection) this would cause a writethrough file to be
incorrectly opened as writeback.

Paolo