From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3EA7FC54E65 for ; Wed, 21 May 2025 09:54:06 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uHg8w-0001Sg-HB; Wed, 21 May 2025 05:53:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uHg8u-0001RW-9B for qemu-devel@nongnu.org; Wed, 21 May 2025 05:53:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uHg8p-0002nL-8H for qemu-devel@nongnu.org; Wed, 21 May 2025 05:53:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1747821217; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=mM7XzfWvF5G5HVJY+98oHV6JxxeBdB2ztXBAKSfnCiU=; b=L5NSek9Y61gW5/4/Q5dOwLwAAfsrPxW1oxDVjNkYxYU/7OXbTnL2ZeR9ArBGTk9fUA/lzn MI7bmknKmQ+eQ4T+1qJ0wFfqN6WpOk0RtDpLqifqSpQFxbjDfIBn0vV0fxAuDMFqVrFlM2 kWvp65BjuKXUu5dB7s4fhnvOyeOOdUE= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-304-UI-dv02fNWy1ErRXfW71kg-1; Wed, 21 May 2025 05:53:35 -0400 X-MC-Unique: UI-dv02fNWy1ErRXfW71kg-1 X-Mimecast-MFC-AGG-ID: UI-dv02fNWy1ErRXfW71kg_1747821214 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0E045180087B; Wed, 21 May 2025 09:53:31 +0000 (UTC) Received: from redhat.com (unknown [10.45.226.112]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4748F195608F; Wed, 21 May 2025 09:53:25 +0000 (UTC) Date: Wed, 21 May 2025 11:53:23 +0200 From: Kevin Wolf To: Fiona Ebner Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, den@virtuozzo.com, andrey.drobyshev@virtuozzo.com, hreitz@redhat.com, stefanha@redhat.com, eblake@redhat.com, jsnow@redhat.com, vsementsov@yandex-team.ru, xiechanglong.d@gmail.com, wencongyang2@huawei.com, berto@igalia.com, fam@euphon.net, ari@tuxera.com Subject: Re: [PATCH v2 03/24] block/snapshot: move drain outside of read-locked bdrv_snapshot_delete() Message-ID: References: <20250520103012.424311-1-f.ebner@proxmox.com> <20250520103012.424311-4-f.ebner@proxmox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250520103012.424311-4-f.ebner@proxmox.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.487, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_PASS=-0.001, T_SPF_HELO_TEMPERROR=0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 20.05.2025 um 12:29 hat Fiona Ebner geschrieben: > This is in preparation to mark bdrv_drained_begin() as GRAPH_UNLOCKED. > > More granular draining is not trivially possible, because > bdrv_snapshot_delete() can recursively call itself. > > The return value of bdrv_all_delete_snapshot() changes from -1 to > -errno propagated from failed sub-calls. This is fine for the existing > callers of bdrv_all_delete_snapshot(). > > Signed-off-by: Fiona Ebner > --- > > Changes in v2: > * Use 'must be drained' instead of 'needs to be drained'. > * Use goto for cleanup/error handling in bdrv_all_delete_snapshot(). > * Don't use atomics to access bs->quiesce_counter. > > block/snapshot.c | 26 +++++++++++++++----------- > blockdev.c | 25 +++++++++++++++++-------- > qemu-img.c | 2 ++ > 3 files changed, 34 insertions(+), 19 deletions(-) > @@ -571,19 +569,22 @@ int bdrv_all_delete_snapshot(const char *name, > ERRP_GUARD(); > g_autoptr(GList) bdrvs = NULL; > GList *iterbdrvs; > + int ret = 0; The initialisation here is technically not needed... > GLOBAL_STATE_CODE(); > - GRAPH_RDLOCK_GUARD_MAINLOOP(); > > - if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) { > - return -1; > + bdrv_drain_all_begin(); > + bdrv_graph_rdlock_main_loop(); > + > + ret = bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp); > + if (ret < 0) { > + goto out; > } ...because ret is assigned here before anyone reads it. But it doesn't hurt either, so: Reviewed-by: Kevin Wolf