From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47270) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wn5dA-0000KW-Kk for qemu-devel@nongnu.org; Wed, 21 May 2014 08:28:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wn5d5-0003Kq-I5 for qemu-devel@nongnu.org; Wed, 21 May 2014 08:28:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:61332) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wn5d5-0003Kd-9x for qemu-devel@nongnu.org; Wed, 21 May 2014 08:28:19 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s4LCSIHB024238 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 21 May 2014 08:28:18 -0400 Date: Wed, 21 May 2014 14:28:16 +0200 From: Stefan Hajnoczi Message-ID: <20140521122816.GB6619@stefanha-thinkpad.redhat.com> References: <1400565880-13409-1-git-send-email-famz@redhat.com> <1400565880-13409-3-git-send-email-famz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1400565880-13409-3-git-send-email-famz@redhat.com> Subject: Re: [Qemu-devel] [PATCH v20 02/15] block: Introduce op_blockers to BlockDriverState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: kwolf@redhat.com, armbru@redhat.com, jcody@redhat.com, hbrock@redhat.com, qemu-devel@nongnu.org, rjones@redhat.com, imain@redhat.com, pbonzini@redhat.com On Tue, May 20, 2014 at 02:04:27PM +0800, Fam Zheng wrote: > BlockDriverState.op_blockers is an array of lists with BLOCK_OP_TYPE_MAX > elements. Each list is a list of blockers of an operation type > (BlockOpType), that marks this BDS as currently blocked for a certain > type of operation with reason errors stored in the list. The rule of > usage is: > > * BDS user who wants to take an operation should check if there's any > blocker of the type with bdrv_op_is_blocked(). > > * BDS user who wants to block certain types of operation, should call > bdrv_op_block (or bdrv_op_block_all to block all types of operations, > which is similar to the existing bdrv_set_in_use()). > > * A blocker is only referenced by op_blockers, so the lifecycle is > managed by caller, and shouldn't be lost until unblock, so typically > a caller does these: > > - Allocate a blocker with error_setg or similar, call bdrv_op_block() > to block some operations. > - Hold the blocker, do his job. > - Unblock operations that it blocked, with the same reason pointer > passed to bdrv_op_unblock(). > - Release the blocker with error_free(). > > Signed-off-by: Fam Zheng > Reviewed-by: Benoit Canet > Reviewed-by: Jeff Cody > --- > block.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++ > include/block/block.h | 7 +++++ > include/block/block_int.h | 5 ++++ > 3 files changed, 88 insertions(+) Reviewed-by: Stefan Hajnoczi