From patchwork Mon Oct 25 18:22:35 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Harper X-Patchwork-Id: 69126 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 52801B6EEE for ; Tue, 26 Oct 2010 05:26:27 +1100 (EST) Received: from localhost ([127.0.0.1]:44518 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PARjd-0001H7-1B for incoming@patchwork.ozlabs.org; Mon, 25 Oct 2010 14:25:29 -0400 Received: from [140.186.70.92] (port=39945 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PARhB-0000KA-Jn for qemu-devel@nongnu.org; Mon, 25 Oct 2010 14:23:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PARh5-0006rx-AO for qemu-devel@nongnu.org; Mon, 25 Oct 2010 14:22:53 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:47647) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PARh5-0006rd-4o for qemu-devel@nongnu.org; Mon, 25 Oct 2010 14:22:51 -0400 Received: from d03relay05.boulder.ibm.com (d03relay05.boulder.ibm.com [9.17.195.107]) by e38.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id o9PIEnE2026206 for ; Mon, 25 Oct 2010 12:14:49 -0600 Received: from d03av05.boulder.ibm.com (d03av05.boulder.ibm.com [9.17.195.85]) by d03relay05.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o9PIMnxh158668 for ; Mon, 25 Oct 2010 12:22:49 -0600 Received: from d03av05.boulder.ibm.com (loopback [127.0.0.1]) by d03av05.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o9PIMnBx003603 for ; Mon, 25 Oct 2010 12:22:49 -0600 Received: from localhost.localdomain (sig-9-48-47-5.mts.ibm.com [9.48.47.5]) by d03av05.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id o9PIMhmm003375; Mon, 25 Oct 2010 12:22:47 -0600 From: Ryan Harper To: Date: Mon, 25 Oct 2010 13:22:35 -0500 Message-Id: <1288030956-28383-3-git-send-email-ryanh@us.ibm.com> X-Mailer: git-send-email 1.6.3.3 In-Reply-To: <1288030956-28383-1-git-send-email-ryanh@us.ibm.com> References: <1288030956-28383-1-git-send-email-ryanh@us.ibm.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6, seldom 2.4 (older, 4) Cc: Stefan Hajnoczi , Anthony Liguori , Ryan Harper , Kevin Wolf Subject: [Qemu-devel] [PATCH 2/3] v2 Fix Block Hotplug race with drive_unplug() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Block hot unplug is racy since the guest is required to acknowlege the ACPI unplug event; this may not happen synchronously with the device removal command This series aims to close a gap where by mgmt applications that assume the block resource has been removed without confirming that the guest has acknowledged the removal may re-assign the underlying device to a second guest leading to data leakage. This series introduces a new montor command to decouple asynchornous device removal from restricting guest access to a block device. We do this by creating a new monitor command drive_unplug which maps to a bdrv_unplug() command which does a qemu_aio_flush; bdrv_flush() and bdrv_close(). Once complete, subsequent IO is rejected from the device and the guest will get IO errors but continue to function. A subsequent device removal command can be issued to remove the device, to which the guest may or maynot respond, but as long as the unplugged bit is set, no IO will be sumbitted. Changes since v1: - Added qemu_aio_flush() before bdrv_flush() to wait on pending io Signed-off-by: Ryan Harper --- block.c | 7 +++++++ block.h | 1 + blockdev.c | 26 ++++++++++++++++++++++++++ blockdev.h | 1 + hmp-commands.hx | 15 +++++++++++++++ 5 files changed, 50 insertions(+), 0 deletions(-) diff --git a/block.c b/block.c index a19374d..be47655 100644 --- a/block.c +++ b/block.c @@ -1328,6 +1328,13 @@ void bdrv_set_removable(BlockDriverState *bs, int removable) } } +void bdrv_unplug(BlockDriverState *bs) +{ + qemu_aio_flush(); + bdrv_flush(bs); + bdrv_close(bs); +} + int bdrv_is_removable(BlockDriverState *bs) { return bs->removable; diff --git a/block.h b/block.h index 5f64380..732f63e 100644 --- a/block.h +++ b/block.h @@ -171,6 +171,7 @@ void bdrv_set_on_error(BlockDriverState *bs, BlockErrorAction on_read_error, BlockErrorAction on_write_error); BlockErrorAction bdrv_get_on_error(BlockDriverState *bs, int is_read); void bdrv_set_removable(BlockDriverState *bs, int removable); +void bdrv_unplug(BlockDriverState *bs); int bdrv_is_removable(BlockDriverState *bs); int bdrv_is_read_only(BlockDriverState *bs); int bdrv_is_sg(BlockDriverState *bs); diff --git a/blockdev.c b/blockdev.c index 5fc3b9b..68eb329 100644 --- a/blockdev.c +++ b/blockdev.c @@ -610,3 +610,29 @@ int do_change_block(Monitor *mon, const char *device, } return monitor_read_bdrv_key_start(mon, bs, NULL, NULL); } + +int do_drive_unplug(Monitor *mon, const QDict *qdict, QObject **ret_data) +{ + DriveInfo *dinfo; + BlockDriverState *bs; + const char *id; + + if (!qdict_haskey(qdict, "id")) { + qerror_report(QERR_MISSING_PARAMETER, "id"); + return -1; + } + + id = qdict_get_str(qdict, "id"); + dinfo = drive_get_by_id(id); + if (!dinfo) { + qerror_report(QERR_DEVICE_NOT_FOUND, id); + return -1; + } + + /* mark block device unplugged */ + bs = dinfo->bdrv; + bdrv_unplug(bs); + + return 0; +} + diff --git a/blockdev.h b/blockdev.h index 19c6915..ecb9ac8 100644 --- a/blockdev.h +++ b/blockdev.h @@ -52,5 +52,6 @@ int do_eject(Monitor *mon, const QDict *qdict, QObject **ret_data); int do_block_set_passwd(Monitor *mon, const QDict *qdict, QObject **ret_data); int do_change_block(Monitor *mon, const char *device, const char *filename, const char *fmt); +int do_drive_unplug(Monitor *mon, const QDict *qdict, QObject **ret_data); #endif diff --git a/hmp-commands.hx b/hmp-commands.hx index 81999aa..7a32a2e 100644 --- a/hmp-commands.hx +++ b/hmp-commands.hx @@ -68,6 +68,21 @@ Eject a removable medium (use -f to force it). ETEXI { + .name = "drive_unplug", + .args_type = "id:s", + .params = "device", + .help = "unplug block device", + .user_print = monitor_user_noop, + .mhandler.cmd_new = do_drive_unplug, + }, + +STEXI +@item unplug @var{device} +@findex unplug +Unplug block device. +ETEXI + + { .name = "change", .args_type = "device:B,target:F,arg:s?", .params = "device filename [format]",