From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59964) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XIJM9-000739-Vt for qemu-devel@nongnu.org; Fri, 15 Aug 2014 11:24:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XIJM3-0008NC-R5 for qemu-devel@nongnu.org; Fri, 15 Aug 2014 11:23:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22764) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XIJM3-0008Mz-IM for qemu-devel@nongnu.org; Fri, 15 Aug 2014 11:23:47 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s7FFNl1V032463 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Fri, 15 Aug 2014 11:23:47 -0400 Message-ID: <53EE25FF.4010707@redhat.com> Date: Fri, 15 Aug 2014 17:23:43 +0200 From: Max Reitz MIME-Version: 1.0 References: <1405117387-25539-1-git-send-email-mreitz@redhat.com> In-Reply-To: <1405117387-25539-1-git-send-email-mreitz@redhat.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/4] block: Warn about usage of growing formats over non-growable protocols List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Stefan Hajnoczi On 12.07.2014 00:23, Max Reitz wrote: > Some image formats (e.g. qcow2) require the underlying file to grow on > write accesses, but this is in fact not supported by all protocols (e.g. > nbd does not). If such a format requiring file growth is used > non-read-only over a protocol which does not support this, a warning > should be issued. > > This warning is issued for example whenever one tries to export a qcow2 > image over nbd-server and use the export from qemu. > > We could make this an error, but I decided not to in order to retain > "compatibility" (although if this warning is emitted, the user should > have already complained about I/O errors on write accesses, so it's > questionable what behavior this should be compatible to). > > While at it, make BDS.growable actually indicate what it is (as far as I > understood) supposed to: Whether the BDS supports writes beyond the end > of the disk size (which then automatically increase that disk size). > > > Max Reitz (4): > block: Correct bs->growable > block: Introduce requires_growing_file > iotests: Make some qemu-io commands read-only > iotests: Skip read and write in 040 for length=0 > > block.c | 11 +++++++++++ > block/blkdebug.c | 2 ++ > block/blkverify.c | 2 ++ > block/cow.c | 1 + > block/iscsi.c | 2 ++ > block/nbd.c | 2 ++ > block/qcow.c | 1 + > block/qcow2.c | 2 ++ > block/qed.c | 1 + > block/raw_bsd.c | 1 + > block/vdi.c | 2 ++ > block/vhdx.c | 2 ++ > block/vmdk.c | 1 + > block/vpc.c | 2 ++ > include/block/block_int.h | 4 ++++ > tests/qemu-iotests/040 | 18 +++++++++++------- > tests/qemu-iotests/072 | 9 ++++++++- > tests/qemu-iotests/072.out | 1 + > tests/qemu-iotests/089 | 2 +- > 19 files changed, 57 insertions(+), 9 deletions(-) Ping