From nobody Mon May 6 10:21:26 2024 Delivered-To: importer2@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer2=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1622614092; cv=none; d=zohomail.com; s=zohoarc; b=SrH1OH7JiqmKtV7h9OW966uUtVwQcsWqTXq8InP0EUm6B9s6RKmSSv7WBW74uQoa8pWpTEhz5qSTM9NQvT2OEzZi44xGaGLigqW1A0A+cn56Oydo//OuMqscZCHSBkdzo7pBbZkU/W4rj9wM25f0CFNekPhvf7I3FLAJtSvvYAo= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1622614092; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=eoOo5hBfq6NS8rUpAEP97RZdcyUb+otYHU97CawxAkE=; b=aNeGeL6bUPW/7FlfYmmbue+mrAhiLquDRyOCGF9VUmvu5F8Lnkr5amKL2+58+mcZ6BQpRGX13IhurrsxEkCAVBlY+LxSFcjlHWUk62s8xOo2OQNnEpO+Z51qk1wL2ejOsx8ySEMKnrBEvcvAaOT+FUZkMFWsqR/PXOSFjIlHucc= ARC-Authentication-Results: i=1; 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bh=eoOo5hBfq6NS8rUpAEP97RZdcyUb+otYHU97CawxAkE=; b=P0dvh9Q86hqVr3LGYrV8mOxQQ/JIf0V5qobqH/NOmGMjgkkkmeGc9VLmYNAU6a3MZQEN6Y /+yLw3Mz0Hao7Jq+tGcjqYPwi63kutimhPH25Zm6xTo5GKmO7lnFs+mqgTFQ1zMvUQkE2U 3lOS7ufkXc1vnWY8HOYO+6mj3bN2rXI= X-MC-Unique: i-8BW7YhMECWo0_mZDDSrQ-1 From: Sergio Lopez To: qemu-devel@nongnu.org Subject: [PATCH v2 1/2] block-backend: add drained_poll Date: Wed, 2 Jun 2021 08:05:51 +0200 Message-Id: <20210602060552.17433-2-slp@redhat.com> In-Reply-To: <20210602060552.17433-1-slp@redhat.com> References: <20210602060552.17433-1-slp@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=slp@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+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=slp@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.371, 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: Kevin Wolf , Vladimir Sementsov-Ogievskiy , Sergio Lopez , qemu-block@nongnu.org, Max Reitz , Nir Soffer Errors-To: qemu-devel-bounces+importer2=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Allow block backends to poll their devices/users to check if they have been quiesced when entering a drained section. This will be used in the next patch to wait for the NBD server to be completely quiesced. Suggested-by: Kevin Wolf Reviewed-by: Kevin Wolf Reviewed-by: Eric Blake Signed-off-by: Sergio Lopez Reviewed-by: Vladimir Sementsov-Ogievskiy --- block/block-backend.c | 7 ++++++- include/sysemu/block-backend.h | 4 ++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/block/block-backend.c b/block/block-backend.c index de5496af66..8fcc2b4b3d 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -2393,8 +2393,13 @@ static void blk_root_drained_begin(BdrvChild *child) static bool blk_root_drained_poll(BdrvChild *child) { BlockBackend *blk =3D child->opaque; + bool busy =3D false; assert(blk->quiesce_counter); - return !!blk->in_flight; + + if (blk->dev_ops && blk->dev_ops->drained_poll) { + busy =3D blk->dev_ops->drained_poll(blk->dev_opaque); + } + return busy || !!blk->in_flight; } =20 static void blk_root_drained_end(BdrvChild *child, int *drained_end_counte= r) diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h index 880e903293..5423e3d9c6 100644 --- a/include/sysemu/block-backend.h +++ b/include/sysemu/block-backend.h @@ -66,6 +66,10 @@ typedef struct BlockDevOps { * Runs when the backend's last drain request ends. */ void (*drained_end)(void *opaque); + /* + * Is the device still busy? + */ + bool (*drained_poll)(void *opaque); } BlockDevOps; =20 /* This struct is embedded in (the private) BlockBackend struct and contai= ns --=20 2.26.2 From nobody Mon May 6 10:21:26 2024 Delivered-To: importer2@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer2=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1622614077; cv=none; d=zohomail.com; s=zohoarc; b=UACtlR6WVb+ppFFIbv2TaJE/SecPqXcBpnPHxpj+nkiLDrU4gRdPOS8H/eI6XKGXye96ZMzHAG5qXgwMpqwm4Atclmrboe/p2wGchBCvtvIzwWG4xfkgMfBHIn+c9pbRMgc7vqp0ZG63dlAYv462DckUiCypjAttwZBJoUQGfpA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1622614077; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; 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s=mimecast20190719; t=1622614011; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fw+cxqfkEz8HnBzm2ZZ9OhnHjwJoctGaOwfdY1ILi/I=; b=hbGA2t1jH/FyQ2eAiwGvSU0/hbvLPulqa7eUgNgwx/mDZwbrM3sD8K5BVg6zg3f/M4UCOM h+pBn+U1hqWOwROX6YlcOqkcUKWdMM/iFo5+BLQnK/VG+1jx9Ve5ji8km7fp40Mrz1jSM6 rOn2cycVix6Nd8i8gbxZ6FxkdMrnOgM= X-MC-Unique: mJPx5hJzN3mHiPMOrlWgFQ-1 From: Sergio Lopez To: qemu-devel@nongnu.org Subject: [PATCH v2 2/2] nbd/server: Use drained block ops to quiesce the server Date: Wed, 2 Jun 2021 08:05:52 +0200 Message-Id: <20210602060552.17433-3-slp@redhat.com> In-Reply-To: <20210602060552.17433-1-slp@redhat.com> References: <20210602060552.17433-1-slp@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=slp@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+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=slp@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.371, 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=ham 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 , Vladimir Sementsov-Ogievskiy , Sergio Lopez , qemu-block@nongnu.org, Max Reitz , Nir Soffer Errors-To: qemu-devel-bounces+importer2=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Before switching between AioContexts we need to make sure that we're fully quiesced ("nb_requests =3D=3D 0" for every client) when entering the drained section. To do this, we set "quiescing =3D true" for every client on ".drained_begin" to prevent new coroutines from being created, and check if "nb_requests =3D=3D 0" on ".drained_poll". Finally, once we're exiting the drained section, on ".drained_end" we set "quiescing =3D false" and call "nbd_client_receive_next_request()" to resume the processing of new requests. With these changes, "blk_aio_attach()" and "blk_aio_detach()" can be reverted to be as simple as they were before f148ae7d36. RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=3D1960137 Suggested-by: Kevin Wolf Signed-off-by: Sergio Lopez Reviewed-by: Vladimir Sementsov-Ogievskiy --- nbd/server.c | 82 ++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 61 insertions(+), 21 deletions(-) diff --git a/nbd/server.c b/nbd/server.c index 86a44a9b41..b60ebc3ab6 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1513,6 +1513,11 @@ static void nbd_request_put(NBDRequestData *req) g_free(req); =20 client->nb_requests--; + + if (client->quiescing && client->nb_requests =3D=3D 0) { + aio_wait_kick(); + } + nbd_client_receive_next_request(client); =20 nbd_client_put(client); @@ -1530,49 +1535,68 @@ static void blk_aio_attached(AioContext *ctx, void = *opaque) QTAILQ_FOREACH(client, &exp->clients, next) { qio_channel_attach_aio_context(client->ioc, ctx); =20 + assert(client->nb_requests =3D=3D 0); assert(client->recv_coroutine =3D=3D NULL); assert(client->send_coroutine =3D=3D NULL); - - if (client->quiescing) { - client->quiescing =3D false; - nbd_client_receive_next_request(client); - } } } =20 -static void nbd_aio_detach_bh(void *opaque) +static void blk_aio_detach(void *opaque) { NBDExport *exp =3D opaque; NBDClient *client; =20 + trace_nbd_blk_aio_detach(exp->name, exp->common.ctx); + QTAILQ_FOREACH(client, &exp->clients, next) { qio_channel_detach_aio_context(client->ioc); + } + + exp->common.ctx =3D NULL; +} + +static void nbd_drained_begin(void *opaque) +{ + NBDExport *exp =3D opaque; + NBDClient *client; + + QTAILQ_FOREACH(client, &exp->clients, next) { client->quiescing =3D true; + } +} =20 - if (client->recv_coroutine) { - if (client->read_yielding) { - qemu_aio_coroutine_enter(exp->common.ctx, - client->recv_coroutine); - } else { - AIO_WAIT_WHILE(exp->common.ctx, client->recv_coroutine != =3D NULL); - } - } +static void nbd_drained_end(void *opaque) +{ + NBDExport *exp =3D opaque; + NBDClient *client; =20 - if (client->send_coroutine) { - AIO_WAIT_WHILE(exp->common.ctx, client->send_coroutine !=3D NU= LL); - } + QTAILQ_FOREACH(client, &exp->clients, next) { + client->quiescing =3D false; + nbd_client_receive_next_request(client); } } =20 -static void blk_aio_detach(void *opaque) +static bool nbd_drained_poll(void *opaque) { NBDExport *exp =3D opaque; + NBDClient *client; =20 - trace_nbd_blk_aio_detach(exp->name, exp->common.ctx); + QTAILQ_FOREACH(client, &exp->clients, next) { + if (client->nb_requests !=3D 0) { + /* + * If there's a coroutine waiting for a request on nbd_read_eo= f() + * enter it here so we don't depend on the client to wake it u= p. + */ + if (client->recv_coroutine !=3D NULL && client->read_yielding)= { + qemu_aio_coroutine_enter(exp->common.ctx, + client->recv_coroutine); + } =20 - aio_wait_bh_oneshot(exp->common.ctx, nbd_aio_detach_bh, exp); + return true; + } + } =20 - exp->common.ctx =3D NULL; + return false; } =20 static void nbd_eject_notifier(Notifier *n, void *data) @@ -1594,6 +1618,12 @@ void nbd_export_set_on_eject_blk(BlockExport *exp, B= lockBackend *blk) blk_add_remove_bs_notifier(blk, &nbd_exp->eject_notifier); } =20 +static const BlockDevOps nbd_block_ops =3D { + .drained_begin =3D nbd_drained_begin, + .drained_end =3D nbd_drained_end, + .drained_poll =3D nbd_drained_poll, +}; + static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp= _args, Error **errp) { @@ -1715,8 +1745,17 @@ static int nbd_export_create(BlockExport *blk_exp, B= lockExportOptions *exp_args, =20 exp->allocation_depth =3D arg->allocation_depth; =20 + /* + * We need to inhibit request queuing in the block layer to ensure we = can + * be properly quiesced when entering a drained section, as our corout= ines + * servicing pending requests might enter blk_pread(). + */ + blk_set_disable_request_queuing(blk, true); + blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, ex= p); =20 + blk_set_dev_ops(blk, &nbd_block_ops, exp); + QTAILQ_INSERT_TAIL(&exports, exp, next); =20 return 0; @@ -1788,6 +1827,7 @@ static void nbd_export_delete(BlockExport *blk_exp) } blk_remove_aio_context_notifier(exp->common.blk, blk_aio_attached, blk_aio_detach, exp); + blk_set_disable_request_queuing(exp->common.blk, false); } =20 for (i =3D 0; i < exp->nr_export_bitmaps; i++) { --=20 2.26.2