From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:50960) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UIEhd-0003ih-UT for qemu-devel@nongnu.org; Wed, 20 Mar 2013 04:48:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UIEhc-0001kb-Nm for qemu-devel@nongnu.org; Wed, 20 Mar 2013 04:48:57 -0400 Received: from mail.avalus.com ([2001:41c8:10:1dd::10]:37617) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UIESS-0004Uv-Vx for qemu-devel@nongnu.org; Wed, 20 Mar 2013 04:33:17 -0400 Date: Wed, 20 Mar 2013 08:33:02 +0000 From: Alex Bligh Message-ID: In-Reply-To: References: <1363609123-20748-1-git-send-email-alex@alex.org.uk> <51471767.8030604@redhat.com> <7AC8953FE45335FB794B6DFE@Ximines.local> <51471F14.7030209@redhat.com> <6D0F4ACDA3B7FCF1A50F8B52@Ximines.local> <5147298C.8080900@redhat.com> <51473E82.1020806@redhat.com> <861AFE1A9C44444FD8BAEE16@Ximines.local> <5147512E.5050501@eu.citrix.com> <5147562E.1090203@redhat.com> <5148414C.7060303@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Subject: Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes. Reply-To: Alex Bligh List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefano Stabellini , Paolo Bonzini Cc: Ian Campbell , Stefano Stabellini , George Dunlap , Ian Jackson , qemu-devel@nongnu.org, xen-devel , Anthony Liguori , Alex Bligh Stefano, --On 19 March 2013 15:13:29 +0000 Stefano Stabellini wrote: > Therefore I think that the current change is not safe, but it is pretty > easy to make it safe. > You just need to move the call to blk_open from blk_init to blk_connect. > Actually you can move most of blk_init to blk_connect, you just need to > keep the 4 xenstore_write_be_int at the end of the function. The final of these 4 writes in blk_init is: xenstore_write_be_int(&blkdev->xendev, "sectors", blkdev->file_size / blkdev->file_blk); and blkdev->filesize comes from bdrv_getlength(blkdev->bs), and that requires (I think) bdrv_open to have been called. Can these 4 writes move safely to blk_connect? Or can we write the sectors count as (say) 0 here and fix it later in blk_connect? The remainder look ok. -- Alex Bligh