From nobody Fri Nov 14 23:27:51 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1759862157; cv=none; d=zohomail.com; s=zohoarc; b=lpSgiXPQwx5TwgydCWo8Eq2VLJflDNsUpQ8V8hmbzhqzLSBBozeit74xfqyChj+wGMlFbTYcHSIh8qMYUwkezUOIuNQP+t0/T1eFxWyFw6olsP9SH8STnjtG2enN2SAgiPBtTyDvVBtwDmb6DvYpYLXijwqdJhUH85TB+J9pe7I= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1759862157; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=4+d+ZZynQwMoVubA0KaHn38NBhgbFi2k8bySMKvDrIg=; b=Bmj0UhvzA7Ii81TGECjWwzLEBs/5f710N3kus/YAjFNVMDFXslXNfQgJ2lEz3L5+h9RGQzKmq7s1Qm9sNXIgTnxkUqsWZxd2XufZf11Jp6CHqEdmfpBqx0uvM0EtjH7fn68na7heVkuLwQFWd6f5DJMg/gDLCGUeyESo7OT1vLA= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1759862157638669.8236692968211; Tue, 7 Oct 2025 11:35:57 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v6CXB-0005tJ-27; Tue, 07 Oct 2025 14:35:38 -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 1v6CWd-0005i8-CU for qemu-devel@nongnu.org; Tue, 07 Oct 2025 14:35:04 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v6CWZ-0002dp-0b for qemu-devel@nongnu.org; Tue, 07 Oct 2025 14:35:03 -0400 Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-599-YCDhIJxDNJ-U6gnWaJRqZA-1; Tue, 07 Oct 2025 14:34:56 -0400 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-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 773741955F29; Tue, 7 Oct 2025 18:34:55 +0000 (UTC) Received: from localhost (unknown [10.2.16.87]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id E1BB11956056; Tue, 7 Oct 2025 18:34:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759862098; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4+d+ZZynQwMoVubA0KaHn38NBhgbFi2k8bySMKvDrIg=; b=fAducl7Xd7vVSP256zBBix/YesJJMjD38IVJ6+HtM6hXXjUbg8qbvE3bAjYLgWI/gg+BbY QU+/7ysMrlbtqTMEY90Ze4cwCI2jMJA3WPgVe2P6mNHj+ovar6/TsPyFt9p4526VYmyTVd HN1fjQFyBXJ1ZvuwhCEb97aqgA3M/sE= X-MC-Unique: YCDhIJxDNJ-U6gnWaJRqZA-1 X-Mimecast-MFC-AGG-ID: YCDhIJxDNJ-U6gnWaJRqZA_1759862095 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Kevin Wolf , Eric Blake , qemu-block@nongnu.org, Hanna Reitz , Stefan Hajnoczi Subject: [PATCH v2 2/5] block: add blk_add_attach/detach_notifier() APIs Date: Tue, 7 Oct 2025 14:34:44 -0400 Message-ID: <20251007183447.93120-3-stefanha@redhat.com> In-Reply-To: <20251007183447.93120-1-stefanha@redhat.com> References: <20251007183447.93120-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 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=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.422, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1759862161197154100 Content-Type: text/plain; charset="utf-8" Add an API to receive a callback when a BlockDriverState is attached or detached from the block graph. This allows callers to track insert, remove, and replace operations. Note that this API might be able to replace the blk_add_remove_bs_notifier() API if the callback checks that the root BDS is being removed and ignores all other calls. I think this is a bit messy though, so I kept blk_add_remove_bs_notifier(). Signed-off-by: Stefan Hajnoczi Reviewed-by: Eric Blake --- include/system/block-backend-global-state.h | 9 ++ block/block-backend.c | 44 ++++++ tests/unit/test-block-backend.c | 164 ++++++++++++++++++++ 3 files changed, 217 insertions(+) diff --git a/include/system/block-backend-global-state.h b/include/system/b= lock-backend-global-state.h index c3849640df..e828f271ee 100644 --- a/include/system/block-backend-global-state.h +++ b/include/system/block-backend-global-state.h @@ -97,6 +97,15 @@ void blk_remove_aio_context_notifier(BlockBackend *blk, void (*detach_aio_context)(void *), void *opaque); void blk_add_remove_bs_notifier(BlockBackend *blk, Notifier *notify); + +typedef struct { + BlockBackend *blk; + BlockDriverState *bs; +} BlockBackendAttachDetachArgs; + +void blk_add_attach_notifier(BlockBackend *blk, Notifier *notify); +void blk_add_detach_notifier(BlockBackend *blk, Notifier *notify); + BlockBackendRootState *blk_get_root_state(BlockBackend *blk); void blk_update_root_state(BlockBackend *blk); bool blk_get_detect_zeroes_from_root_state(BlockBackend *blk); diff --git a/block/block-backend.c b/block/block-backend.c index f8d6ba65c1..45e31f0079 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -76,6 +76,7 @@ struct BlockBackend { =20 /* Protected by BQL */ NotifierList remove_bs_notifiers, insert_bs_notifiers; + NotifierList attach_notifiers, detach_notifiers; QLIST_HEAD(, BlockBackendAioNotifier) aio_notifiers; =20 int quiesce_counter; /* atomic: written under BQL, read by other threa= ds */ @@ -280,6 +281,30 @@ static int GRAPH_RDLOCK blk_root_inactivate(BdrvChild = *child) return 0; } =20 +static void GRAPH_WRLOCK +blk_root_propagate_attach(BdrvChild *self, BdrvChild *descendant) +{ + BlockBackend *blk =3D self->opaque; + BlockBackendAttachDetachArgs args =3D { + .blk =3D blk, + .bs =3D descendant->bs, + }; + + notifier_list_notify(&blk->attach_notifiers, &args); +} + +static void GRAPH_WRLOCK +blk_root_propagate_detach(BdrvChild *self, BdrvChild *descendant) +{ + BlockBackend *blk =3D self->opaque; + BlockBackendAttachDetachArgs args =3D { + .blk =3D blk, + .bs =3D descendant->bs, + }; + + notifier_list_notify(&blk->detach_notifiers, &args); +} + static void blk_root_attach(BdrvChild *child) { BlockBackend *blk =3D child->opaque; @@ -333,6 +358,9 @@ static const BdrvChildClass child_root =3D { .activate =3D blk_root_activate, .inactivate =3D blk_root_inactivate, =20 + .propagate_attach =3D blk_root_propagate_attach, + .propagate_detach =3D blk_root_propagate_detach, + .attach =3D blk_root_attach, .detach =3D blk_root_detach, =20 @@ -374,6 +402,8 @@ BlockBackend *blk_new(AioContext *ctx, uint64_t perm, u= int64_t shared_perm) qemu_co_queue_init(&blk->queued_requests); notifier_list_init(&blk->remove_bs_notifiers); notifier_list_init(&blk->insert_bs_notifiers); + notifier_list_init(&blk->attach_notifiers); + notifier_list_init(&blk->detach_notifiers); QLIST_INIT(&blk->aio_notifiers); =20 QTAILQ_INSERT_TAIL(&block_backends, blk, link); @@ -492,6 +522,8 @@ static void blk_delete(BlockBackend *blk) } assert(QLIST_EMPTY(&blk->remove_bs_notifiers.notifiers)); assert(QLIST_EMPTY(&blk->insert_bs_notifiers.notifiers)); + assert(QLIST_EMPTY(&blk->attach_notifiers.notifiers)); + assert(QLIST_EMPTY(&blk->detach_notifiers.notifiers)); assert(QLIST_EMPTY(&blk->aio_notifiers)); assert(qemu_co_queue_empty(&blk->queued_requests)); qemu_mutex_destroy(&blk->queued_requests_lock); @@ -2512,6 +2544,18 @@ void blk_add_remove_bs_notifier(BlockBackend *blk, N= otifier *notify) notifier_list_add(&blk->remove_bs_notifiers, notify); } =20 +void blk_add_attach_notifier(BlockBackend *blk, Notifier *notify) +{ + GLOBAL_STATE_CODE(); + notifier_list_add(&blk->attach_notifiers, notify); +} + +void blk_add_detach_notifier(BlockBackend *blk, Notifier *notify) +{ + GLOBAL_STATE_CODE(); + notifier_list_add(&blk->detach_notifiers, notify); +} + BlockAcctStats *blk_get_stats(BlockBackend *blk) { IO_CODE(); diff --git a/tests/unit/test-block-backend.c b/tests/unit/test-block-backen= d.c index 4257b3f815..693383f029 100644 --- a/tests/unit/test-block-backend.c +++ b/tests/unit/test-block-backend.c @@ -24,6 +24,7 @@ =20 #include "qemu/osdep.h" #include "block/block.h" +#include "block/block_int.h" #include "system/block-backend.h" #include "qapi/error.h" #include "qemu/main-loop.h" @@ -70,6 +71,167 @@ static void test_drain_all_aio_error(void) blk_unref(blk); } =20 +static int bdrv_test_co_change_backing_file(BlockDriverState *bs, + const char *backing_file, + const char *backing_fmt) +{ + return 0; /* just return success so bdrv_set_backing_hd() works */ +} + +static BlockDriver bdrv_test =3D { + .format_name =3D "test", + .supports_backing =3D true, + .bdrv_child_perm =3D bdrv_default_perms, + .bdrv_co_change_backing_file =3D bdrv_test_co_change_backing_file, +}; + +typedef struct { + Notifier attach_notifier; + Notifier detach_notifier; + GArray *notifications; +} AttachDetach; + +typedef enum { + NOTIFY_END =3D 0, + NOTIFY_ATTACH, + NOTIFY_DETACH, +} NotificationType; + +typedef struct { + NotificationType type; + BlockDriverState *bs; +} Notification; + +static void attach_detach_append(AttachDetach *ad, NotificationType type, + BlockBackendAttachDetachArgs *args) +{ + Notification n =3D { + .type =3D type, + .bs =3D args->bs, + }; + + g_array_append_vals(ad->notifications, &n, 1); +} + +static void attach_notify(Notifier *notifier, void *data) +{ + AttachDetach *ad =3D container_of(notifier, AttachDetach, attach_notif= ier); + attach_detach_append(ad, NOTIFY_ATTACH, data); +} + +static void detach_notify(Notifier *notifier, void *data) +{ + AttachDetach *ad =3D container_of(notifier, AttachDetach, attach_notif= ier); + attach_detach_append(ad, NOTIFY_DETACH, data); +} + +static void attach_detach_init(AttachDetach *ad, BlockBackend *blk) +{ + ad->attach_notifier.notify =3D attach_notify; + ad->detach_notifier.notify =3D detach_notify; + ad->notifications =3D g_array_new(true, true, sizeof(Notification)); + + blk_add_attach_notifier(blk, &ad->attach_notifier); + blk_add_detach_notifier(blk, &ad->detach_notifier); +} + +static void attach_detach_cleanup(AttachDetach *ad) +{ + g_array_free(ad->notifications, true); + notifier_remove(&ad->detach_notifier); + notifier_remove(&ad->attach_notifier); +} + +/* + * Check that the expected notifications occurred. @expected is terminated= by a + * NOTIFY_END element. + */ +static void attach_detach_expect(AttachDetach *ad, const Notification *exp= ected) +{ + GArray *array =3D ad->notifications; + + /* The array is zero terminated so there is at least one element */ + Notification *actual =3D (Notification *)array->data; + + while (expected->type !=3D NOTIFY_END) { + g_assert_cmpint(actual->type, =3D=3D, expected->type); + g_assert(actual->bs =3D=3D expected->bs); + expected++; + actual++; + } + + g_assert_cmpint(actual->type, =3D=3D, NOTIFY_END); + + g_array_remove_range(array, 0, array->len); +} + +static void test_attach_detach_notifier(void) +{ + AttachDetach ad; + BlockDriverState *format; + BlockDriverState *file; + BlockDriverState *file2; + BlockBackend *blk =3D blk_new(qemu_get_aio_context(), + BLK_PERM_ALL, BLK_PERM_ALL); + + attach_detach_init(&ad, blk); + + format =3D bdrv_new_open_driver(&bdrv_test, "format", BDRV_O_RDWR, + &error_abort); + file =3D bdrv_new_open_driver(&bdrv_test, "file", BDRV_O_RDWR, &error_= abort); + file2 =3D bdrv_new_open_driver(&bdrv_test, "file2", BDRV_O_RDWR, + &error_abort); + + bdrv_graph_wrlock_drained(); + bdrv_attach_child(format, file, "file", &child_of_bds, + BDRV_CHILD_PRIMARY | BDRV_CHILD_DATA, &error_abort); + bdrv_graph_wrunlock(); + + /* Insert format -> file */ + blk_insert_bs(blk, format, &error_abort); + attach_detach_expect(&ad, (Notification[]){ + (Notification){NOTIFY_ATTACH, format}, + {}, + }); + + /* Replace format -> file with file2 */ + blk_replace_bs(blk, file2, &error_abort); + attach_detach_expect(&ad, (Notification[]){ + (Notification){NOTIFY_DETACH, format}, + (Notification){NOTIFY_ATTACH, file2}, + {}, + }); + + /* Remove file2 */ + blk_remove_bs(blk); + attach_detach_expect(&ad, (Notification[]){ + (Notification){NOTIFY_DETACH, file2}, + {}, + }); + + /* These BDSes were unrefed so we need new instances */ + file =3D bdrv_new_open_driver(&bdrv_test, "file", BDRV_O_RDWR, &error_= abort); + file2 =3D bdrv_new_open_driver(&bdrv_test, "file2", BDRV_O_RDWR, + &error_abort); + + /* Replace a non-root node */ + bdrv_graph_wrlock_drained(); + bdrv_attach_child(format, file, "file", &child_of_bds, + BDRV_CHILD_PRIMARY | BDRV_CHILD_DATA, &error_abort); + bdrv_replace_node(file, file2, &error_abort); + bdrv_graph_wrunlock(); + attach_detach_expect(&ad, (Notification[]){ + (Notification){NOTIFY_ATTACH, file}, + (Notification){NOTIFY_DETACH, file}, + (Notification){NOTIFY_ATTACH, file2}, + {}, + }); + + attach_detach_cleanup(&ad); + blk_unref(blk); + bdrv_unref(format); +} + int main(int argc, char **argv) { bdrv_init(); @@ -80,6 +242,8 @@ int main(int argc, char **argv) g_test_add_func("/block-backend/drain_aio_error", test_drain_aio_error= ); g_test_add_func("/block-backend/drain_all_aio_error", test_drain_all_aio_error); + g_test_add_func("/block-backend/attach_detach_notifier", + test_attach_detach_notifier); =20 return g_test_run(); } --=20 2.51.0