From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C77123CF1EF; Thu, 24 Sep 2026 13:04:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790255050; cv=none; b=Z6gJ37g1z6Jt/CTZU6Rvt16h7ESzmO9qTfMurAtFb39bqi99Wn0U2Z4BcqUH7bvJWNmJP+WhPH1lJqsiQsNqUIJBkgaNP0RMeaOrzpeQLyA6ItR2UipekHJ06ebQpBUFK9rAkbsL7nHhQp7KQmU0fs4dfE0RdrS6BXzlNbI5XUk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790255050; c=relaxed/simple; bh=Vyyb/DvXlDQZU5coJEgzU8GWzT51K2/FeRjcOEuFlKk=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=m4ivXIe6qDv+0wnvc0OT8MaZTeWljPI7Ohq6MHqTgQY3PyBO2jNoRp6xwIXJy80gkXQzvFM3+O2MuuL6wVg5uxNNAnFjNCSo5705ju/E4HanVTkYa0ZBig2VGwvzgHSiD2r1OYAh9rZl/cVkc1mUIdQAImvyVzgdmchs7XQtA8w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=B6bBDM6R; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="B6bBDM6R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63D531F000FF; Thu, 24 Sep 2026 13:03:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790255038; bh=yjh2bTrhPurtSNQ+PKSrwOkkIhBdDNVWMQpqO75xcrw=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=B6bBDM6RLUwPMidyEA3J6yTrC1z2LxfebOzGupioZKL7/z+8dN5qX8EvtQcjsWGND 7seDE3XNfHUxmMqkumqQyNRazmMB2QkleCC3EGcr/NcPDW/VaIuSKE0+Qio6R/qo0m xo9XqNbJsK7hXA7zHwb6h5e/GH2sTL9IYrbZvNU1U0f4ksKxTs867r4KP3wmXnQVu8 MUHso+pXbXZwpaiJTOYrF5hsGdbiY27gyqIJtZxesX+s1moC7kWbhVtARNqvftdVIR m93cK3/EVxBrO14y1opug/eGdItQA6WVSo5r83I+LiEwCvWIBK5zseEGUilTHE66KE F177+fK1DVWlw== Message-ID: <2a78884377a5e537dab390788d66b10fbf2b2726.camel@kernel.org> Subject: Re: [PATCH v2 11/14] nfsd: check for mountpoints after non-creating open. From: Jeff Layton To: NeilBrown , Alexander Viro , Christian Brauner , Chuck Lever , Jori Koolstra , Mateusz Guzik , Dorjoy Chowdhury Cc: Trond Myklebust , Anna Schumaker , Andreas Gruenbacher , gfs2@lists.linux.dev, Ilya Dryomov , Alex Markuze , Viacheslav Dubeyko , ceph-devel@vger.kernel.org, Paulo Alcantara , Namjae Jeon , linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org Date: Thu, 24 Sep 2026 09:03:55 -0400 In-Reply-To: <20260919022441.3305170-12-neilb@ownmail.net> References: <20260919022441.3305170-1-neilb@ownmail.net> <20260919022441.3305170-12-neilb@ownmail.net> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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2tAMJUvFTdDbfe3zKlPDTuVsyNsALBGclPLagJ5ZTP+Vp2irAN9uwBuacBOTtmOdz4ZN2tdvNgozz uxp4CHBDVzAslUi2idy+xpsp47DWPxYFIRP3M8QG/aNW052LaPc0cedYxp8+9eiVUNpxF4SiU4i9J DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-2.fc44) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 LLM review: > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c > index 6e443503d0b7..3d37754f787b 100644 > --- a/fs/nfsd/nfs4proc.c > +++ b/fs/nfsd/nfs4proc.c [ ... ] > @@ -466,6 +454,14 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc= _fh *fhp, > status =3D nfserr_exist; > goto out; > } > + /* We opened an existing file, it might be a junction. */ > + if (unlikely(nfsd_mountpoint(child, fhp->fh_export) =3D=3D 1)) { > + dget(child); > + nfsd_filp_close(open->op_filp); > + open->op_filp =3D NULL; > + goto do_cross_mnt; > + } > + [ ... ] > @@ -511,6 +507,21 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc= _fh *fhp, > out: > nfsd_attrs_free(&attrs); > return status; > + > +do_cross_mnt: > + exp =3D exp_get(fhp->fh_export); > + > + status =3D nfsd_cross_mnt(rqstp, &child, &exp); > + if (status =3D=3D nfs_ok) > + status =3D fh_compose(resfhp, exp, > + child, fhp); When the new junction check triggers, resfhp was already composed earlier in nfsd4_create_file(), so the fh_compose() in do_cross_mnt runs a second time on the same handle: fs/nfsd/nfsfh.c:fh_compose() { ... if (fhp->fh_dentry) { printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n", dentry); } ... fhp->fh_dentry =3D dget(dentry); /* our internal copy */ fhp->fh_export =3D exp_get(exp); ... } The first composed dentry and export references are overwritten without being released. Should resfhp be released before crossing, or the mountpoint check done before the first compose? --=20 Jeff Layton