From patchwork Sun Mar 13 09:28:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Schoenebeck X-Patchwork-Id: 12779117 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 8D98FC433EF for ; Sun, 13 Mar 2022 09:48:51 +0000 (UTC) Received: from localhost ([::1]:50732 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nTKqI-0001nw-Kt for qemu-devel@archiver.kernel.org; Sun, 13 Mar 2022 05:48:50 -0400 Received: from eggs.gnu.org ([209.51.188.92]:48836) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <4d6395b9285920fe91131e63c3c79a2a3a07c7b7@lizzy.crudebyte.com>) id 1nTKn9-0007R1-GS for qemu-devel@nongnu.org; Sun, 13 Mar 2022 05:45:35 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:53083) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <4d6395b9285920fe91131e63c3c79a2a3a07c7b7@lizzy.crudebyte.com>) id 1nTKn7-0004h8-Ma for qemu-devel@nongnu.org; Sun, 13 Mar 2022 05:45:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Cc:To:Subject:Date:From:References:In-Reply-To: Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Content-ID: Content-Description; bh=a0crYNaDR8bFaHuaYpqJ8FipN3b+gvU/VTrR86DztiI=; b=bmfSa KuFAaBkOHHlPJtjqTZWoxsVrJd+Gv7eSF39xla2z6pYhRfVWzU0vwaEHdL/A56vTbiA+wceUS2oIU IAjDAo6q46RTXWuBeb4Oshubn26WIg5sI7GWn2jq1I+oKxrKvQ6Y5lnjIA3XVvc7g1CVWn0UX/9HO yv2wb4+FZktOzv4gwpHbK3aQ3hhbZYiMbxlaBphmhwYcnYV3gh1yxwtE9rmXb4eSD7C+5EbKA46wq msglmX/Kf+LoWmxfIU5cQly7bijHcTnFY+7hEhqlWYZvOBVRUebRTNHVH463fTFL8Qe1luAJ5cG2f GLZ+XfOjAIFKDEiRNtvsbEB43E4+Q==; Message-Id: <4d6395b9285920fe91131e63c3c79a2a3a07c7b7.1647163863.git.qemu_oss@crudebyte.com> In-Reply-To: References: From: Christian Schoenebeck Date: Sun, 13 Mar 2022 10:28:27 +0100 Subject: [PATCH v3 5/7] 9pfs: fix 'Twalk' to only send error if no component walked To: qemu-devel@nongnu.org Cc: Greg Kurz Received-SPF: none client-ip=91.194.90.13; envelope-from=4d6395b9285920fe91131e63c3c79a2a3a07c7b7@lizzy.crudebyte.com; helo=lizzy.crudebyte.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Current implementation of 'Twalk' request handling always sends an 'Rerror' response if any error occured. The 9p2000 protocol spec says though: " If the first element cannot be walked for any reason, Rerror is returned. Otherwise, the walk will return an Rwalk message containing nwqid qids corresponding, in order, to the files that are visited by the nwqid successful elementwise walks; nwqid is therefore either nwname or the index of the first elementwise walk that failed. " http://ericvh.github.io/9p-rfc/rfc9p2000.html#anchor33 For that reason we are no longer leaving from an error path in function v9fs_walk(), unless really no path component could be walked successfully or if the request has been interrupted. Local variable 'nwalked' counts and reflects the number of path components successfully processed by background I/O thread, whereas local variable 'name_idx' subsequently counts and reflects the number of path components eventually accepted successfully by 9p server controller portion. New local variable 'any_err' is an aggregate variable reflecting whether any error occurred at all, while already existing variable 'err' only reflects the last error. Despite QIDs being delivered to client in a more relaxed way now, it is important to note though that fid still must remain unaffected if any error occurred. Signed-off-by: Christian Schoenebeck --- hw/9pfs/9p.c | 43 +++++++++++++++++++++++++++---------------- 1 file changed, 27 insertions(+), 16 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 298f4e6548..e770972a71 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1766,7 +1766,7 @@ static void coroutine_fn v9fs_walk(void *opaque) { int name_idx, nwalked; g_autofree V9fsQID *qids = NULL; - int i, err = 0; + int i, err = 0, any_err = 0; V9fsPath dpath, path; P9ARRAY_REF(V9fsPath) pathes = NULL; uint16_t nwnames; @@ -1832,19 +1832,20 @@ static void coroutine_fn v9fs_walk(void *opaque) * driver code altogether inside the following block. */ v9fs_co_run_in_worker({ + nwalked = 0; if (v9fs_request_cancelled(pdu)) { - err = -EINTR; + any_err |= err = -EINTR; break; } err = s->ops->lstat(&s->ctx, &dpath, &fidst); if (err < 0) { - err = -errno; + any_err |= err = -errno; break; } stbuf = fidst; - for (nwalked = 0; nwalked < nwnames; nwalked++) { + for (; nwalked < nwnames; nwalked++) { if (v9fs_request_cancelled(pdu)) { - err = -EINTR; + any_err |= err = -EINTR; break; } if (!same_stat_id(&pdu->s->root_st, &stbuf) || @@ -1854,16 +1855,16 @@ static void coroutine_fn v9fs_walk(void *opaque) wnames[nwalked].data, &pathes[nwalked]); if (err < 0) { - err = -errno; + any_err |= err = -errno; break; } if (v9fs_request_cancelled(pdu)) { - err = -EINTR; + any_err |= err = -EINTR; break; } err = s->ops->lstat(&s->ctx, &pathes[nwalked], &stbuf); if (err < 0) { - err = -errno; + any_err |= err = -errno; break; } stbufs[nwalked] = stbuf; @@ -1874,12 +1875,12 @@ static void coroutine_fn v9fs_walk(void *opaque) /* * Handle all the rest of this Twalk request on main thread ... */ - if (err < 0) { + if ((err < 0 && !nwalked) || err == -EINTR) { goto out; } - err = stat_to_qid(pdu, &fidst, &qid); - if (err < 0) { + any_err |= err = stat_to_qid(pdu, &fidst, &qid); + if (err < 0 && !nwalked) { goto out; } stbuf = fidst; @@ -1888,20 +1889,29 @@ static void coroutine_fn v9fs_walk(void *opaque) v9fs_path_copy(&dpath, &fidp->path); v9fs_path_copy(&path, &fidp->path); - for (name_idx = 0; name_idx < nwnames; name_idx++) { + for (name_idx = 0; name_idx < nwalked; name_idx++) { if (!same_stat_id(&pdu->s->root_st, &stbuf) || strcmp("..", wnames[name_idx].data)) { stbuf = stbufs[name_idx]; - err = stat_to_qid(pdu, &stbuf, &qid); + any_err |= err = stat_to_qid(pdu, &stbuf, &qid); if (err < 0) { - goto out; + break; } v9fs_path_copy(&path, &pathes[name_idx]); v9fs_path_copy(&dpath, &path); } memcpy(&qids[name_idx], &qid, sizeof(qid)); } + if (any_err < 0) { + if (!name_idx) { + /* don't send any QIDs, send Rlerror instead */ + goto out; + } else { + /* send QIDs (not Rlerror), but fid MUST remain unaffected */ + goto send_qids; + } + } if (fid == newfid) { if (fidp->fid_type != P9_FID_NONE) { err = -EINVAL; @@ -1919,8 +1929,9 @@ static void coroutine_fn v9fs_walk(void *opaque) newfidp->uid = fidp->uid; v9fs_path_copy(&newfidp->path, &path); } - err = v9fs_walk_marshal(pdu, nwnames, qids); - trace_v9fs_walk_return(pdu->tag, pdu->id, nwnames, qids); +send_qids: + err = v9fs_walk_marshal(pdu, name_idx, qids); + trace_v9fs_walk_return(pdu->tag, pdu->id, name_idx, qids); out: put_fid(pdu, fidp); if (newfidp) {