From patchwork Mon Feb 18 16:18:16 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 10818445 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 55814922 for ; Mon, 18 Feb 2019 16:28:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4322F29F6B for ; Mon, 18 Feb 2019 16:28:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3657C2A891; Mon, 18 Feb 2019 16:28:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id AB73329F6B for ; Mon, 18 Feb 2019 16:28:01 +0000 (UTC) Received: from localhost ([127.0.0.1]:33179 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gvllw-0004ZW-Tr for patchwork-qemu-devel@patchwork.kernel.org; Mon, 18 Feb 2019 11:28:01 -0500 Received: from eggs.gnu.org ([209.51.188.92]:34755) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gvldO-0006GK-Sp for qemu-devel@nongnu.org; Mon, 18 Feb 2019 11:19:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gvldL-0002NX-DT for qemu-devel@nongnu.org; Mon, 18 Feb 2019 11:19:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37982) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gvldF-0002Fv-Af; Mon, 18 Feb 2019 11:19:03 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AD5292F3; Mon, 18 Feb 2019 16:18:56 +0000 (UTC) Received: from dhcp-200-176.str.redhat.com (dhcp-200-176.str.redhat.com [10.33.200.176]) by smtp.corp.redhat.com (Postfix) with ESMTP id 17C255D70E; Mon, 18 Feb 2019 16:18:54 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Date: Mon, 18 Feb 2019 17:18:16 +0100 Message-Id: <20190218161822.3573-7-kwolf@redhat.com> In-Reply-To: <20190218161822.3573-1-kwolf@redhat.com> References: <20190218161822.3573-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 18 Feb 2019 16:18:56 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 06/12] nbd: Use low-level QIOChannel API in nbd_read_eof() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Instead of using the convenience wrapper qio_channel_read_all_eof(), use the lower level QIOChannel API. This means duplicating some code, but we'll need this because this coroutine yield is special: We want it to be interruptible so that nbd_client_attach_aio_context() can correctly reenter the coroutine. This moves the bdrv_dec/inc_in_flight() pair into nbd_read_eof(), so that connection_co will always sit in this exact qio_channel_yield() call when bdrv_drain() returns. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- include/block/nbd.h | 4 ++-- block/nbd-client.c | 8 +------- nbd/client.c | 46 ++++++++++++++++++++++++++++++++++++--------- 3 files changed, 40 insertions(+), 18 deletions(-) diff --git a/include/block/nbd.h b/include/block/nbd.h index cad975e00c..c6ef1ef42e 100644 --- a/include/block/nbd.h +++ b/include/block/nbd.h @@ -300,8 +300,8 @@ int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds, int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info, Error **errp); int nbd_send_request(QIOChannel *ioc, NBDRequest *request); -int coroutine_fn nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, - Error **errp); +int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc, + NBDReply *reply, Error **errp); int nbd_client(int fd); int nbd_disconnect(int fd); int nbd_errno_to_system_errno(int err); diff --git a/block/nbd-client.c b/block/nbd-client.c index e776785325..688993652d 100644 --- a/block/nbd-client.c +++ b/block/nbd-client.c @@ -84,15 +84,9 @@ static coroutine_fn void nbd_connection_entry(void *opaque) * * Therefore we keep an additional in_flight reference all the time and * only drop it temporarily here. - * - * FIXME This is not safe because the QIOChannel could wake up the - * coroutine for a second time; it is not prepared for coroutine - * resumption from external code. */ - bdrv_dec_in_flight(s->bs); assert(s->reply.handle == 0); - ret = nbd_receive_reply(s->ioc, &s->reply, &local_err); - bdrv_inc_in_flight(s->bs); + ret = nbd_receive_reply(s->bs, s->ioc, &s->reply, &local_err); if (local_err) { trace_nbd_read_reply_entry_fail(ret, error_get_pretty(local_err)); diff --git a/nbd/client.c b/nbd/client.c index 28d174c0f3..de7da48246 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -1394,30 +1394,58 @@ static int nbd_receive_structured_reply_chunk(QIOChannel *ioc, * negative errno on failure (errp is set) */ static inline int coroutine_fn -nbd_read_eof(QIOChannel *ioc, void *buffer, size_t size, Error **errp) +nbd_read_eof(BlockDriverState *bs, QIOChannel *ioc, void *buffer, size_t size, + Error **errp) { - int ret; + bool partial = false; assert(size); - ret = qio_channel_read_all_eof(ioc, buffer, size, errp); - if (ret < 0) { - ret = -EIO; + while (size > 0) { + struct iovec iov = { .iov_base = buffer, .iov_len = size }; + ssize_t len; + + len = qio_channel_readv(ioc, &iov, 1, errp); + if (len == QIO_CHANNEL_ERR_BLOCK) { + bdrv_dec_in_flight(bs); + qio_channel_yield(ioc, G_IO_IN); + bdrv_inc_in_flight(bs); + continue; + } else if (len < 0) { + return -EIO; + } else if (len == 0) { + if (partial) { + error_setg(errp, + "Unexpected end-of-file before all bytes were read"); + return -EIO; + } else { + return 0; + } + } + + partial = true; + size -= len; + buffer = (uint8_t*) buffer + len; } - return ret; + return 1; } /* nbd_receive_reply + * + * Decreases bs->in_flight while waiting for a new reply. This yield is where + * we wait indefinitely and the coroutine must be able to be safely reentered + * for nbd_client_attach_aio_context(). + * * Returns 1 on success * 0 on eof, when no data was read (errp is not set) * negative errno on failure (errp is set) */ -int coroutine_fn nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, - Error **errp) +int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc, + NBDReply *reply, Error **errp) { int ret; const char *type; - ret = nbd_read_eof(ioc, &reply->magic, sizeof(reply->magic), errp); + ret = nbd_read_eof(bs, ioc, &reply->magic, sizeof(reply->magic), errp); if (ret <= 0) { return ret; }