From mboxrd@z Thu Jan 1 00:00:00 1970 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 D313DC433EF for ; Fri, 11 Mar 2022 16:47:50 +0000 (UTC) Received: from localhost ([::1]:43246 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nSiQf-0001Rt-Fg for qemu-devel@archiver.kernel.org; Fri, 11 Mar 2022 11:47:49 -0500 Received: from eggs.gnu.org ([209.51.188.92]:47818) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nSiNu-0008Vr-Rx for qemu-devel@nongnu.org; Fri, 11 Mar 2022 11:45:03 -0500 Received: from kylie.crudebyte.com ([5.189.157.229]:45473) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nSiNs-0002AV-KK for qemu-devel@nongnu.org; Fri, 11 Mar 2022 11:44:58 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=kylie; h=Content-Type:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Content-ID:Content-Description; bh=eRYlw2O01WNhakOSsNcC6rNZx0vXjm03Cidhn9ZGbgk=; b=h7iMmPqJEGEh1dgA+TXS6elVfi BJlUx6BW+G9ZsP0aj8i32Wo+SvuL0r3wHUGx220viKVlztl8xP2AsC5brXCUpGhDYcddez+1emrRp GkvxvT31cYoBiD1yBv5Bn+7nqV1SRN4OELp4ub/RxrFJ5PZowzfUpbZ5wv3dWWYv7njhbVVLD7NFs Enu32eBzzCvIO0ae1pijbL+HqSoLQ3hbkgUWHfwcrbn3DMIod9MEhB+iJ45fN0YSu9nXflfaSHtx2 0lQTlDL74/o6MamAlis9tBBDLuHAtTpZrZSCUSgj9kSyEccqbp0puetMXmb95EIeyg2myOI8y0a7p cT/Q9pRUIq2dcAapb5scurq/I1B3jEbtQvd6SlbqwJIt6Izk8NX1eBfymMs+vAAeub3jB7WxZpuf8 QrSLwl0+lfsc6kKJXWqKCpuJd52KCVUuivLnMu4JWkciOR9EQP9PPGNov4ax+kYDrxDwbKkZgUokY EHP0DWUMunYPV+CUpIKRJQtEmFDaC+P0hFvKw0W6rzN5tolz989oTXaxj85F4jQPn2A4op7Cmta83 l5QLndChPHUA11uJJnEmcQ5jKKaH+HKmV78Xjy9ybJjKnWxX0C3ujDtr1MaMYQYgRLXAhDOqhUgzX EHiJWQMyinTmucEBWj+sRVmBjU3SYr1IfC0VlIP+o=; From: Christian Schoenebeck To: qemu-devel@nongnu.org Cc: Greg Kurz Subject: Re: [PATCH 5/6] 9pfs: fix 'Twalk' to only send error if no component walked Date: Fri, 11 Mar 2022 17:44:54 +0100 Message-ID: <3685932.ieBdHTVF6f@silver> In-Reply-To: <20220311173541.06d6e96e@bahia> References: <1785989.mTmxrQOLcC@silver> <20220311173541.06d6e96e@bahia> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" Received-SPF: pass client-ip=5.189.157.229; envelope-from=qemu_oss@crudebyte.com; helo=kylie.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_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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Freitag, 11. M=E4rz 2022 17:35:41 CET Greg Kurz wrote: > On Thu, 10 Mar 2022 10:13:33 +0100 >=20 > Christian Schoenebeck wrote: > > On Mittwoch, 9. M=E4rz 2022 18:57:39 CET Christian Schoenebeck wrote: > > > Current implementation of 'Twalk' request handling always sends an > > > 'Rerror' > > >=20 > > > response if any error occured. The 9p2000 protocol spec sais though: > > > " > > > If the first element cannot be walked for any reason, Rerror is > > > returned. > > > Otherwise, the walk will return an Rwalk message containing nwqid q= ids > > > corresponding, in order, to the files that are visited by the nwqid > > > successful elementwise walks; nwqid is therefore either nwname or t= he > > >=20 > > > index of the first elementwise walk that failed. > > >=20 > > > " > > > =20 > > > http://ericvh.github.io/9p-rfc/rfc9p2000.html#anchor33 > > >=20 > > > For that reason we are no longer leaving from an error path in functi= on > > > v9fs_walk(), unless really no path component could be walked > > > successfully or if the request has been interrupted. > > >=20 > > > Local variable 'nvalid' counts and reflects the number of path > > > components > > > successfully processed by background I/O thread, whereas local variab= le > > > 'name_idx' subsequently counts and reflects the number of path > > > components > > > eventually accepted successfully by 9p server controller portion. > > >=20 > > > New local variable 'any_err' is an aggregate variable reflecting whet= her > > > any error occurred at all, while already existing variable 'err' only > > > reflects the last error. > > >=20 > > > Despite QIDs being delivered to client in a more relaxed way now, it = is > > > important to note though that fid still must remain uneffacted if any > > > error > >=20 > > Typo: should be "unaffected". > >=20 > > > occurred. > > >=20 > > > Signed-off-by: Christian Schoenebeck > > > --- > > >=20 > > > hw/9pfs/9p.c | 29 +++++++++++++++++++++-------- > > > 1 file changed, 21 insertions(+), 8 deletions(-) > > >=20 > > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > > > index 6cdc566866..8ccd180608 100644 > > > --- a/hw/9pfs/9p.c > > > +++ b/hw/9pfs/9p.c > > > @@ -1766,7 +1766,7 @@ static void coroutine_fn v9fs_walk(void *opaque) > > >=20 > > > { > > > =20 > > > int name_idx, nvalid; > > > g_autofree V9fsQID *qids =3D NULL; > > >=20 > > > - int i, err =3D 0; > > > + int i, err =3D 0, any_err =3D 0; > > >=20 > > > V9fsPath dpath, path; > > > P9ARRAY_REF(V9fsPath) pathes =3D NULL; > > > uint16_t nwnames; > > >=20 > > > @@ -1832,6 +1832,7 @@ static void coroutine_fn v9fs_walk(void *opaque) > > >=20 > > > * driver code altogether inside the following block. > > > */ > > > =20 > > > v9fs_co_run_in_worker({ > > >=20 > > > + nvalid =3D 0; > > >=20 > > > if (v9fs_request_cancelled(pdu)) { > > > =20 > > > err =3D -EINTR; > > > break; > > >=20 > > > @@ -1842,7 +1843,7 @@ static void coroutine_fn v9fs_walk(void *opaque) > > >=20 > > > break; > > > =20 > > > } > > > stbuf =3D fidst; > > >=20 > > > - for (nvalid =3D 0; nvalid < nwnames; nvalid++) { > > > + for (; nvalid < nwnames; nvalid++) { > > >=20 > > > if (v9fs_request_cancelled(pdu)) { > > > =20 > > > err =3D -EINTR; > > > break; > > >=20 > > > @@ -1874,12 +1875,13 @@ static void coroutine_fn v9fs_walk(void *opaq= ue) > > >=20 > > > /* > > > =20 > > > * Handle all the rest of this Twalk request on main thread ... > > > */ > > >=20 > > > - if (err < 0) { > > > + if ((err < 0 && !nvalid) || err =3D=3D -EINTR) { > > >=20 > > > goto out; > > > =20 > > > } > > >=20 > > > + any_err |=3D err; > > >=20 > > > err =3D stat_to_qid(pdu, &fidst, &qid); > > >=20 > > > - if (err < 0) { > > > + if (err < 0 && !nvalid) { > > >=20 > > > goto out; > > > =20 > > > } > > > stbuf =3D fidst; > > >=20 > > > @@ -1888,20 +1890,30 @@ static void coroutine_fn v9fs_walk(void *opaq= ue) > > >=20 > > > v9fs_path_copy(&dpath, &fidp->path); > > > v9fs_path_copy(&path, &fidp->path); > > >=20 > > > - for (name_idx =3D 0; name_idx < nwnames; name_idx++) { > > > + for (name_idx =3D 0; name_idx < nvalid; name_idx++) { > > >=20 > > > if (!same_stat_id(&pdu->s->root_st, &stbuf) || > > > =20 > > > strcmp("..", wnames[name_idx].data)) > > > =20 > > > { > > > =20 > > > stbuf =3D stbufs[name_idx]; > > > err =3D stat_to_qid(pdu, &stbuf, &qid); > > > if (err < 0) { > > >=20 > > > - goto out; > > > + break; > > >=20 > > > } > > > v9fs_path_copy(&path, &pathes[name_idx]); > > > v9fs_path_copy(&dpath, &path); > > > =20 > > > } > > > memcpy(&qids[name_idx], &qid, sizeof(qid)); > > > =20 > > > } > > >=20 > > > + any_err |=3D err; > > > + if (any_err) { > >=20 > > Not sure if there is ever the case err > 0, but as we are already > > comparing > > for "if (err < 0)" everywhere, we should probably also do the same > > comparison for the aggregate error variable here, right? >=20 > It seems that you could drop any_err and just check name_idx !=3D nwnames= ? Mmm, what about the special case 'Twalk nwnames=3D0' (i.e. fid cloning), th= at=20 implementation would then skip errors, no? > > if (any_err < 0) { > > =20 > > ... > > >=20 > > > + if (!name_idx) { > > > + /* don't send any QIDs, send Rlerror instead */ > > > + goto out; > > > + } else { > > > + /* send QIDs (not Rlerror), but fid MUST remain unaffect= ed > > > */ > > > + goto send_qids; > > > + } > > > + } > > >=20 > > > if (fid =3D=3D newfid) { > > > =20 > > > if (fidp->fid_type !=3D P9_FID_NONE) { > > > =20 > > > err =3D -EINVAL; > > >=20 > > > @@ -1919,8 +1931,9 @@ static void coroutine_fn v9fs_walk(void *opaque) > > >=20 > > > newfidp->uid =3D fidp->uid; > > > v9fs_path_copy(&newfidp->path, &path); > > > =20 > > > } > > >=20 > > > - err =3D v9fs_walk_marshal(pdu, nwnames, qids); > > > - trace_v9fs_walk_return(pdu->tag, pdu->id, nwnames, qids); > > > +send_qids: > > > + err =3D v9fs_walk_marshal(pdu, name_idx, qids); > > > + trace_v9fs_walk_return(pdu->tag, pdu->id, name_idx, qids); > > >=20 > > > out: > > > put_fid(pdu, fidp); > > > if (newfidp) {