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bh=uGG0fmrhfcOATjuUJX1bVZwjwTj+jLWrAd4mWW7jh2o=; b=HElPVsXTSceg0gcIwmD1Mxp5+teRKs3ZdLxJcKd5fdqaoBQkigKjNw1ciOBAfc/K95vTmY H/rLM4HDO2ncL+PlPPTei17js7xPF0bk34zS4SXjXH38sckoUpp/zsDYDVkm/pUBKufg6M lH3+svDMOb/xK6GM75cusmHID2Dblas= X-MC-Unique: Ga2-SRgDPa6mPhjvvRhrOw-1 From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PULL 16/39] block: add bdrv_replace_child_safe() transaction action Date: Fri, 30 Apr 2021 12:51:24 +0200 Message-Id: <20210430105147.125840-17-kwolf@redhat.com> In-Reply-To: <20210430105147.125840-1-kwolf@redhat.com> References: <20210430105147.125840-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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-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=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.22, 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_H4=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: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) Content-Type: text/plain; charset="utf-8" From: Vladimir Sementsov-Ogievskiy To be used in the following commit. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Kevin Wolf Message-Id: <20210428151804.439460-17-vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf --- block.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/block.c b/block.c index 98b7bc179c..a5305662dc 100644 --- a/block.c +++ b/block.c @@ -83,6 +83,9 @@ static BlockDriverState *bdrv_open_inherit(const char *fi= lename, BdrvChildRole child_role, Error **errp); =20 +static void bdrv_replace_child_noperm(BdrvChild *child, + BlockDriverState *new_bs); + static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQ= ueue *queue, Error **errp); static void bdrv_reopen_commit(BDRVReopenState *reopen_state); @@ -2237,6 +2240,57 @@ static int bdrv_drv_set_perm(BlockDriverState *bs, u= int64_t perm, return 0; } =20 +typedef struct BdrvReplaceChildState { + BdrvChild *child; + BlockDriverState *old_bs; +} BdrvReplaceChildState; + +static void bdrv_replace_child_commit(void *opaque) +{ + BdrvReplaceChildState *s =3D opaque; + + bdrv_unref(s->old_bs); +} + +static void bdrv_replace_child_abort(void *opaque) +{ + BdrvReplaceChildState *s =3D opaque; + BlockDriverState *new_bs =3D s->child->bs; + + /* old_bs reference is transparently moved from @s to @s->child */ + bdrv_replace_child_noperm(s->child, s->old_bs); + bdrv_unref(new_bs); +} + +static TransactionActionDrv bdrv_replace_child_drv =3D { + .commit =3D bdrv_replace_child_commit, + .abort =3D bdrv_replace_child_abort, + .clean =3D g_free, +}; + +/* + * bdrv_replace_child_safe + * + * Note: real unref of old_bs is done only on commit. + */ +__attribute__((unused)) +static void bdrv_replace_child_safe(BdrvChild *child, BlockDriverState *ne= w_bs, + Transaction *tran) +{ + BdrvReplaceChildState *s =3D g_new(BdrvReplaceChildState, 1); + *s =3D (BdrvReplaceChildState) { + .child =3D child, + .old_bs =3D child->bs, + }; + tran_add(tran, &bdrv_replace_child_drv, s); + + if (new_bs) { + bdrv_ref(new_bs); + } + bdrv_replace_child_noperm(child, new_bs); + /* old_bs reference is transparently moved from @child to @s */ +} + /* * Check whether permissions on this node can be changed in a way that * @cumulative_perms and @cumulative_shared_perms are the new cumulative --=20 2.30.2