From patchwork Thu Feb 9 15:45:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 13134815 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5360C61DA4 for ; Thu, 9 Feb 2023 15:46:30 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pQ97Q-0002DP-Ma; Thu, 09 Feb 2023 10:45:52 -0500 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 1pQ97A-0001wZ-TZ for qemu-devel@nongnu.org; Thu, 09 Feb 2023 10:45:42 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pQ978-0004LV-Ko for qemu-devel@nongnu.org; Thu, 09 Feb 2023 10:45:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675957528; 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; bh=c24n6h4cZyn1238lp8INnIalpufCghBolGU2T98Z3MA=; b=av4ny38gIJqvwDT1txTQokg8sJVjyAtUzFaO344PcPOy14pIjlTdBtxBq/cCZgDXn1vLlt 2KOvLiQ08mu24100bJWdyvmMWZP/UpLNU9+Ey6wg9vW7W5Rkjdwci296iA/Y7br2TCbsTL 4+7HF15ooXD4E30D+JltuPcAcUA/pbk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-116-ocn7J748O26i7xOx8RDGrw-1; Thu, 09 Feb 2023 10:45:24 -0500 X-MC-Unique: ocn7J748O26i7xOx8RDGrw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8680B8027FD; Thu, 9 Feb 2023 15:45:24 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5562E40398A2; Thu, 9 Feb 2023 15:45:24 +0000 (UTC) From: Emanuele Giuseppe Esposito To: qemu-block@nongnu.org Cc: Kevin Wolf , Hanna Reitz , Ninad Palsule , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , qemu-devel@nongnu.org, Emanuele Giuseppe Esposito Subject: [PATCH] block/file-posix: don't use functions calling AIO_WAIT_WHILE in worker threads Date: Thu, 9 Feb 2023 10:45:22 -0500 Message-Id: <20230209154522.1164401-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eesposit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org When calling bdrv_getlength() in handle_aiocb_write_zeroes(), the function creates a new coroutine and then waits that it finishes using AIO_WAIT_WHILE. The problem is that this function could also run in a worker thread, that has a different AioContext from main loop and iothreads, therefore in AIO_WAIT_WHILE we will have in_aio_context_home_thread(ctx) == false and therefore assert(qemu_get_current_aio_context() == qemu_get_aio_context()); in the else branch will fail, crashing QEMU. Aside from that, bdrv_getlength() is wrong also conceptually, because it reads the BDS graph from another thread and is not protected by any lock. Replace it with raw_co_getlength, that doesn't create a coroutine and doesn't read the BDS graph. Signed-off-by: Emanuele Giuseppe Esposito Reported-by: Ninad Palsule --- block/file-posix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/file-posix.c b/block/file-posix.c index d3073a7caa..9a99111f45 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1738,7 +1738,7 @@ static int handle_aiocb_write_zeroes(void *opaque) #ifdef CONFIG_FALLOCATE /* Last resort: we are trying to extend the file with zeroed data. This * can be done via fallocate(fd, 0) */ - len = bdrv_getlength(aiocb->bs); + len = raw_co_getlength(aiocb->bs); if (s->has_fallocate && len >= 0 && aiocb->aio_offset >= len) { int ret = do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes); if (ret == 0 || ret != -ENOTSUP) {