From patchwork Wed Apr 27 11:40:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12828707 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 9BC0CC433EF for ; Wed, 27 Apr 2022 11:54:02 +0000 (UTC) Received: from localhost ([::1]:45088 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1njgF7-0007QE-DV for qemu-devel@archiver.kernel.org; Wed, 27 Apr 2022 07:54:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45792) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1njg2i-0005G5-U3 for qemu-devel@nongnu.org; Wed, 27 Apr 2022 07:41:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:25555) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1njg2f-00033z-TT for qemu-devel@nongnu.org; Wed, 27 Apr 2022 07:41:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651059668; 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=1YYmKNlCMLuMRq9JZ6xzn39kJ2qC/zHscg40GPcZ6QY=; b=G0NG8jL7rbZVs02K1e2s5HaGA6OAaE6mXdteXyrZ42Kq5UfMbqr6KF4rd1mEI4MeTQEf52 LOGMQOyZ32ML05ACFAyN0HRe3WPWTQLx2cMgRaAaPSthIyznCc09BO225p9AmvzN8HQFRk fRyz3Ax9wfpvMn0ucDsq1Qm6fb5Cg8w= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-156-6pebBsguOh-xxjNA0dxw2A-1; Wed, 27 Apr 2022 07:41:07 -0400 X-MC-Unique: 6pebBsguOh-xxjNA0dxw2A-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D8C131C05AAC; Wed, 27 Apr 2022 11:41:06 +0000 (UTC) Received: from localhost (unknown [10.39.193.160]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C08EC9E74; Wed, 27 Apr 2022 11:41:02 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH 2/4] qcow2: Do not reopen data_file in invalidate_cache Date: Wed, 27 Apr 2022 13:40:55 +0200 Message-Id: <20220427114057.36651-3-hreitz@redhat.com> In-Reply-To: <20220427114057.36651-1-hreitz@redhat.com> References: <20220427114057.36651-1-hreitz@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Cc: Kevin Wolf , Emanuele Giuseppe Esposito , Hanna Reitz , qemu-devel@nongnu.org, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" qcow2_co_invalidate_cache() closes and opens the qcow2 file, by calling qcow2_close() and qcow2_do_open(). These two functions must thus be usable from both a global-state and an I/O context. As they are, they are not safe to call in an I/O context, because they use bdrv_unref_child() and bdrv_open_child() to close/open the data_file child, respectively, both of which are global-state functions. When used from qcow2_co_invalidate_cache(), we do not need to close/open the data_file child, though (we do not do this for bs->file or bs->backing either), and so we should skip it in the qcow2_co_invalidate_cache() path. To do so, add a parameter to qcow2_do_open() and qcow2_close() to make them skip handling s->data_file, and have qcow2_co_invalidate_cache() exempt it from the memset() on the BDRVQcow2State. (Note that the QED driver similarly closes/opens the QED image by invoking bdrv_qed_close()+bdrv_qed_do_open(), but both functions seem safe to use in an I/O context.) Fixes: https://gitlab.com/qemu-project/qemu/-/issues/945 Signed-off-by: Hanna Reitz Reviewed-by: Eric Blake --- block/qcow2.c | 104 ++++++++++++++++++++++++++++++-------------------- 1 file changed, 62 insertions(+), 42 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index b5c47931ef..4f5e6440fb 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1296,7 +1296,8 @@ static int validate_compression_type(BDRVQcow2State *s, Error **errp) /* Called with s->lock held. */ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options, - int flags, Error **errp) + int flags, bool open_data_file, + Error **errp) { ERRP_GUARD(); BDRVQcow2State *s = bs->opaque; @@ -1614,50 +1615,52 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options, goto fail; } - /* Open external data file */ - s->data_file = bdrv_open_child(NULL, options, "data-file", bs, - &child_of_bds, BDRV_CHILD_DATA, - true, errp); - if (*errp) { - ret = -EINVAL; - goto fail; - } + if (open_data_file) { + /* Open external data file */ + s->data_file = bdrv_open_child(NULL, options, "data-file", bs, + &child_of_bds, BDRV_CHILD_DATA, + true, errp); + if (*errp) { + ret = -EINVAL; + goto fail; + } - if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) { - if (!s->data_file && s->image_data_file) { - s->data_file = bdrv_open_child(s->image_data_file, options, - "data-file", bs, &child_of_bds, - BDRV_CHILD_DATA, false, errp); + if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) { + if (!s->data_file && s->image_data_file) { + s->data_file = bdrv_open_child(s->image_data_file, options, + "data-file", bs, &child_of_bds, + BDRV_CHILD_DATA, false, errp); + if (!s->data_file) { + ret = -EINVAL; + goto fail; + } + } if (!s->data_file) { + error_setg(errp, "'data-file' is required for this image"); ret = -EINVAL; goto fail; } - } - if (!s->data_file) { - error_setg(errp, "'data-file' is required for this image"); - ret = -EINVAL; - goto fail; - } - /* No data here */ - bs->file->role &= ~BDRV_CHILD_DATA; + /* No data here */ + bs->file->role &= ~BDRV_CHILD_DATA; - /* Must succeed because we have given up permissions if anything */ - bdrv_child_refresh_perms(bs, bs->file, &error_abort); - } else { - if (s->data_file) { - error_setg(errp, "'data-file' can only be set for images with an " - "external data file"); - ret = -EINVAL; - goto fail; - } + /* Must succeed because we have given up permissions if anything */ + bdrv_child_refresh_perms(bs, bs->file, &error_abort); + } else { + if (s->data_file) { + error_setg(errp, "'data-file' can only be set for images with " + "an external data file"); + ret = -EINVAL; + goto fail; + } - s->data_file = bs->file; + s->data_file = bs->file; - if (data_file_is_raw(bs)) { - error_setg(errp, "data-file-raw requires a data file"); - ret = -EINVAL; - goto fail; + if (data_file_is_raw(bs)) { + error_setg(errp, "data-file-raw requires a data file"); + ret = -EINVAL; + goto fail; + } } } @@ -1839,7 +1842,7 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options, fail: g_free(s->image_data_file); - if (has_data_file(bs)) { + if (open_data_file && has_data_file(bs)) { bdrv_unref_child(bs, s->data_file); s->data_file = NULL; } @@ -1876,7 +1879,8 @@ static void coroutine_fn qcow2_open_entry(void *opaque) BDRVQcow2State *s = qoc->bs->opaque; qemu_co_mutex_lock(&s->lock); - qoc->ret = qcow2_do_open(qoc->bs, qoc->options, qoc->flags, qoc->errp); + qoc->ret = qcow2_do_open(qoc->bs, qoc->options, qoc->flags, true, + qoc->errp); qemu_co_mutex_unlock(&s->lock); } @@ -2714,7 +2718,7 @@ static int qcow2_inactivate(BlockDriverState *bs) return result; } -static void qcow2_close(BlockDriverState *bs) +static void qcow2_do_close(BlockDriverState *bs, bool close_data_file) { BDRVQcow2State *s = bs->opaque; qemu_vfree(s->l1_table); @@ -2740,7 +2744,7 @@ static void qcow2_close(BlockDriverState *bs) g_free(s->image_backing_file); g_free(s->image_backing_format); - if (has_data_file(bs)) { + if (close_data_file && has_data_file(bs)) { bdrv_unref_child(bs, s->data_file); s->data_file = NULL; } @@ -2749,11 +2753,17 @@ static void qcow2_close(BlockDriverState *bs) qcow2_free_snapshots(bs); } +static void qcow2_close(BlockDriverState *bs) +{ + qcow2_do_close(bs, true); +} + static void coroutine_fn qcow2_co_invalidate_cache(BlockDriverState *bs, Error **errp) { ERRP_GUARD(); BDRVQcow2State *s = bs->opaque; + BdrvChild *data_file; int flags = s->flags; QCryptoBlock *crypto = NULL; QDict *options; @@ -2767,14 +2777,24 @@ static void coroutine_fn qcow2_co_invalidate_cache(BlockDriverState *bs, crypto = s->crypto; s->crypto = NULL; - qcow2_close(bs); + /* + * Do not reopen s->data_file (i.e., have qcow2_do_close() not close it, + * and then prevent qcow2_do_open() from opening it), because this function + * runs in the I/O path and as such we must not invoke global-state + * functions like bdrv_unref_child() and bdrv_open_child(). + */ + qcow2_do_close(bs, false); + + data_file = s->data_file; memset(s, 0, sizeof(BDRVQcow2State)); + s->data_file = data_file; + options = qdict_clone_shallow(bs->options); flags &= ~BDRV_O_INACTIVE; qemu_co_mutex_lock(&s->lock); - ret = qcow2_do_open(bs, options, flags, errp); + ret = qcow2_do_open(bs, options, flags, false, errp); qemu_co_mutex_unlock(&s->lock); qobject_unref(options); if (ret < 0) {