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bh=7KSv+t6mWbRgJUaI085CiY6NM0m0poggbOSsBtkUmpE=; b=RS7bqfVSv2hbkgEzcPBnJ2Dp4reDm476yqwd+Mf/t8Vv0ZrRiN29KVXVLMirXacLzm7s9s 01Z4esFgJPhCvXqyUjJuYyP+vXTRVbPfo79xfLpeOgUu08NxbPSFowHfdZHTBwbzw1vefG O1hJi4Qrf2ZJ1qyEyrRHWfwpJ1WxAms= X-MC-Unique: SvepPAtYN0eZVsaqsGqIjg-1 From: Max Reitz To: qemu-block@nongnu.org Subject: [PULL 04/53] copy-on-read: add filter drop function Date: Tue, 26 Jan 2021 15:19:27 +0100 Message-Id: <20210126142016.806073-5-mreitz@redhat.com> In-Reply-To: <20210126142016.806073-1-mreitz@redhat.com> References: <20210126142016.806073-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@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=-0.255, 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: Kevin Wolf , Peter Maydell , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" From: Andrey Shinkevich Provide API for the COR-filter removal. Also, drop the filter child permissions for an inactive state when the filter node is being removed. To insert the filter, the block generic layer function bdrv_insert_node() can be used. The new function bdrv_cor_filter_drop() may be considered as an intermediate solution before the QEMU permission update system has overhauled. Then we are able to implement the API function bdrv_remove_node() on the block generic layer. Signed-off-by: Andrey Shinkevich Reviewed-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Max Reitz Message-Id: <20201216061703.70908-4-vsementsov@virtuozzo.com> Signed-off-by: Max Reitz --- block/copy-on-read.h | 32 +++++++++++++++++++++++++ block/copy-on-read.c | 56 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 88 insertions(+) create mode 100644 block/copy-on-read.h diff --git a/block/copy-on-read.h b/block/copy-on-read.h new file mode 100644 index 0000000000..7bf405dccd --- /dev/null +++ b/block/copy-on-read.h @@ -0,0 +1,32 @@ +/* + * Copy-on-read filter block driver + * + * The filter driver performs Copy-On-Read (COR) operations + * + * Copyright (c) 2018-2020 Virtuozzo International GmbH. + * + * Author: + * Andrey Shinkevich + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ + +#ifndef BLOCK_COPY_ON_READ +#define BLOCK_COPY_ON_READ + +#include "block/block_int.h" + +void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs); + +#endif /* BLOCK_COPY_ON_READ */ diff --git a/block/copy-on-read.c b/block/copy-on-read.c index cb03e0f2d3..618c4c4f43 100644 --- a/block/copy-on-read.c +++ b/block/copy-on-read.c @@ -23,11 +23,20 @@ #include "qemu/osdep.h" #include "block/block_int.h" #include "qemu/module.h" +#include "qapi/error.h" +#include "block/copy-on-read.h" + + +typedef struct BDRVStateCOR { + bool active; +} BDRVStateCOR; =20 =20 static int cor_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { + BDRVStateCOR *state =3D bs->opaque; + bs->file =3D bdrv_open_child(NULL, options, "file", bs, &child_of_bds, BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, false, errp); @@ -42,6 +51,13 @@ static int cor_open(BlockDriverState *bs, QDict *options= , int flags, ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) & bs->file->bs->supported_zero_flags); =20 + state->active =3D true; + + /* + * We don't need to call bdrv_child_refresh_perms() now as the permiss= ions + * will be updated later when the filter node gets its parent. + */ + return 0; } =20 @@ -57,6 +73,17 @@ static void cor_child_perm(BlockDriverState *bs, BdrvChi= ld *c, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared) { + BDRVStateCOR *s =3D bs->opaque; + + if (!s->active) { + /* + * While the filter is being removed + */ + *nperm =3D 0; + *nshared =3D BLK_PERM_ALL; + return; + } + *nperm =3D perm & PERM_PASSTHROUGH; *nshared =3D (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED; =20 @@ -135,6 +162,7 @@ static void cor_lock_medium(BlockDriverState *bs, bool = locked) =20 static BlockDriver bdrv_copy_on_read =3D { .format_name =3D "copy-on-read", + .instance_size =3D sizeof(BDRVStateCOR), =20 .bdrv_open =3D cor_open, .bdrv_child_perm =3D cor_child_perm, @@ -154,6 +182,34 @@ static BlockDriver bdrv_copy_on_read =3D { .is_filter =3D true, }; =20 + +void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs) +{ + BdrvChild *child; + BlockDriverState *bs; + BDRVStateCOR *s =3D cor_filter_bs->opaque; + + child =3D bdrv_filter_child(cor_filter_bs); + if (!child) { + return; + } + bs =3D child->bs; + + /* Retain the BDS until we complete the graph change. */ + bdrv_ref(bs); + /* Hold a guest back from writing while permissions are being reset. */ + bdrv_drained_begin(bs); + /* Drop permissions before the graph change. */ + s->active =3D false; + bdrv_child_refresh_perms(cor_filter_bs, child, &error_abort); + bdrv_replace_node(cor_filter_bs, bs, &error_abort); + + bdrv_drained_end(bs); + bdrv_unref(bs); + bdrv_unref(cor_filter_bs); +} + + static void bdrv_copy_on_read_init(void) { bdrv_register(&bdrv_copy_on_read); --=20 2.29.2