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 X-Spam-Level: X-Spam-Status: No, score=-13.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18594C433E0 for ; Fri, 5 Feb 2021 16:31:51 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id A4F5A64EA1 for ; Fri, 5 Feb 2021 16:31:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A4F5A64EA1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34472 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l841N-0005UZ-KE for qemu-devel@archiver.kernel.org; Fri, 05 Feb 2021 11:31:49 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:38856) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l840H-0004pw-KP for qemu-devel@nongnu.org; Fri, 05 Feb 2021 11:30:42 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:23373) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l840E-0007f5-MY for qemu-devel@nongnu.org; Fri, 05 Feb 2021 11:30:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612542638; 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=IXjvjLme6FM+0TCKRr9F+HiQeorls1D61+p1jS48xeI=; b=Omi4yqqZWbF3SfpCpbdI35WY54n1ZKjnvSf0gQk6pxJ/EnQ0UljNwgUg3MYmVgXw73akg4 4R03m4IP1iGpgW7rGUORXx8VBtmEfV39gSeJblKdOw1DyuHbuLxu0WZ6rftcElES4s9L4P /s9PH/1QV5EFPO5IagtWeCIaBzoW+2w= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-497-594OMumFMPyicBGLYyI9IA-1; Fri, 05 Feb 2021 11:30:34 -0500 X-MC-Unique: 594OMumFMPyicBGLYyI9IA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1C108107ACC7; Fri, 5 Feb 2021 16:30:33 +0000 (UTC) Received: from merkur.fritz.box (ovpn-114-240.ams2.redhat.com [10.36.114.240]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7F5BF60BF1; Fri, 5 Feb 2021 16:30:30 +0000 (UTC) Date: Fri, 5 Feb 2021 17:30:29 +0100 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v2 28/36] block: add bdrv_set_backing_noperm() transaction action Message-ID: <20210205163029.GG7072@merkur.fritz.box> References: <20201127144522.29991-1-vsementsov@virtuozzo.com> <20201127144522.29991-29-vsementsov@virtuozzo.com> <20210205140028.GC7072@merkur.fritz.box> <9fe6a325-4af7-5d97-fc0d-06911f7c677a@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <9fe6a325-4af7-5d97-fc0d-06911f7c677a@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.352, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-block@nongnu.org, armbru@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, den@openvz.org, jsnow@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 05.02.2021 um 17:06 hat Vladimir Sementsov-Ogievskiy geschrieben: > 05.02.2021 17:00, Kevin Wolf wrote: > > Am 27.11.2020 um 15:45 hat Vladimir Sementsov-Ogievskiy geschrieben: > > > Split out no-perm part of bdrv_set_backing_hd() as a separate > > > transaction action. Note the in case of existing BdrvChild we reuse it, > > > not recreate, just to do less actions. > > > > > > Signed-off-by: Vladimir Sementsov-Ogievskiy > > > --- > > > block.c | 111 +++++++++++++++++++++++++++++++++++++++++++++----------- > > > 1 file changed, 89 insertions(+), 22 deletions(-) > > > > > > diff --git a/block.c b/block.c > > > index 54fb6d24bd..617cba9547 100644 > > > --- a/block.c > > > +++ b/block.c > > > @@ -101,6 +101,7 @@ static int bdrv_attach_child_common(BlockDriverState *child_bs, > > > uint64_t perm, uint64_t shared_perm, > > > void *opaque, BdrvChild **child, > > > GSList **tran, Error **errp); > > > +static void bdrv_remove_backing(BlockDriverState *bs, GSList **tran); > > > static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue > > > *queue, Error **errp); > > > @@ -3194,45 +3195,111 @@ static BdrvChildRole bdrv_backing_role(BlockDriverState *bs) > > > } > > > } > > > +typedef struct BdrvSetBackingNoPermState { > > > + BlockDriverState *bs; > > > + BlockDriverState *backing_bs; > > > + BlockDriverState *old_inherits_from; > > > + GSList *attach_tran; > > > +} BdrvSetBackingNoPermState; > > > > Why do we need the nested attach_tran instead of just including these > > actions in the outer transaction? > > > > > +static void bdrv_set_backing_noperm_abort(void *opaque) > > > +{ > > > + BdrvSetBackingNoPermState *s = opaque; > > > + > > > + if (s->backing_bs) { > > > + s->backing_bs->inherits_from = s->old_inherits_from; > > > + } > > > + > > > + tran_abort(s->attach_tran); > > > + > > > + bdrv_refresh_limits(s->bs, NULL); > > > + if (s->old_inherits_from) { > > > + bdrv_refresh_limits(s->old_inherits_from, NULL); > > > + } > > > > How is bs->inherits_from related to limits? I don't see a > > bdrv_refresh_limits() call in bdrv_set_backing_noperm() that this would > > undo. > > > > > +} > > > + > > > +static void bdrv_set_backing_noperm_commit(void *opaque) > > > +{ > > > + BdrvSetBackingNoPermState *s = opaque; > > > + > > > + tran_commit(s->attach_tran); > > > +} > > > + > > > +static TransactionActionDrv bdrv_set_backing_noperm_drv = { > > > + .abort = bdrv_set_backing_noperm_abort, > > > + .commit = bdrv_set_backing_noperm_commit, > > > + .clean = g_free, > > > +}; > > > + > > > /* > > > * Sets the bs->backing link of a BDS. A new reference is created; callers > > > * which don't need their own reference any more must call bdrv_unref(). > > > */ > > > -void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, > > > - Error **errp) > > > +static int bdrv_set_backing_noperm(BlockDriverState *bs, > > > + BlockDriverState *backing_bs, > > > + GSList **tran, Error **errp) > > > { > > > - bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) && > > > - bdrv_inherits_from_recursive(backing_hd, bs); > > > + int ret = 0; > > > + bool update_inherits_from = bdrv_chain_contains(bs, backing_bs) && > > > + bdrv_inherits_from_recursive(backing_bs, bs); > > > + GSList *attach_tran = NULL; > > > + BdrvSetBackingNoPermState *s; > > > if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) { > > > - return; > > > + return -EPERM; > > > } > > > - if (backing_hd) { > > > - bdrv_ref(backing_hd); > > > + if (bs->backing && backing_bs) { > > > + bdrv_replace_child_safe(bs->backing, backing_bs, tran); > > > + } else if (bs->backing && !backing_bs) { > > > + bdrv_remove_backing(bs, tran); > > > + } else if (backing_bs) { > > > + assert(!bs->backing); > > > + ret = bdrv_attach_child_noperm(bs, backing_bs, "backing", > > > + &child_of_bds, bdrv_backing_role(bs), > > > + &bs->backing, &attach_tran, errp); > > > + if (ret < 0) { > > > + tran_abort(attach_tran); > > > > This looks wrong to me, we'll call tran_abort() a second time through > > bdrv_set_backing_noperm_abort() when the outer transaction aborts. > > > > I also notice that the other two if branches do just add things to the > > outer 'tran', it's just this branch that gets a nested one. > > > > > + return ret; > > > + } > > > } > > > - if (bs->backing) { > > > - /* Cannot be frozen, we checked that above */ > > > - bdrv_unref_child(bs, bs->backing); > > > - bs->backing = NULL; > > > - } > > > + s = g_new(BdrvSetBackingNoPermState, 1); > > > + *s = (BdrvSetBackingNoPermState) { > > > + .bs = bs, > > > + .backing_bs = backing_bs, > > > + .old_inherits_from = backing_bs ? backing_bs->inherits_from : NULL, > > > + }; > > > + tran_prepend(tran, &bdrv_set_backing_noperm_drv, s); > > > - if (!backing_hd) { > > > - goto out; > > > + /* > > > + * If backing_bs was already part of bs's backing chain, and > > > + * inherits_from pointed recursively to bs then let's update it to > > > + * point directly to bs (else it will become NULL). > > > > Setting it to NULL was previously done by bdrv_unref_child(). > > > > bdrv_replace_child_safe() and bdrv_remove_backing() don't seem to do > > this any more. > > Hmm, yes.. May be we should move bdrv_unset_inherts_from() from > bdrv_unref_child() to bdrv_replace_child_noperm() ? Sounds good to me. This should hopefully be called for all graph changes that could possibly happen. Kevin > > > > > + */ > > > + if (backing_bs && update_inherits_from) { > > > + backing_bs->inherits_from = bs; > > > } > > > - bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_of_bds, > > > - bdrv_backing_role(bs), errp); > > > - /* If backing_hd was already part of bs's backing chain, and > > > - * inherits_from pointed recursively to bs then let's update it to > > > - * point directly to bs (else it will become NULL). */ > > > - if (bs->backing && update_inherits_from) { > > > - backing_hd->inherits_from = bs; > > > + bdrv_refresh_limits(bs, NULL); > > > + > > > + return 0; > > > +} > > > > Kevin > > > > > -- > Best regards, > Vladimir >