From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1239724679C for ; Fri, 20 Jun 2025 12:59:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750424363; cv=none; b=cwW15lgSi5m+pKJb8WGI7GpLgNjWFpXxCu28QHh38LdP0pFm6jbdrKFppuk1aeIG7jtjz48Z/DkPc9TnpoGjvpbQPKoTFIE0vH7Syn5QWCfAzD7/GLAxpwb//MYsZ7WDrFThoBZucQfsArgeG3DlL+8TQcTcXP1Eg9/CyLPdNg4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750424363; c=relaxed/simple; bh=2qYWiBHlm1D58irbmWAArbiJN15Rn+Us52EhPaaECuM=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=bPQsXaYJE73QaIyBXahykO9h/hMoSPznvECKxUvJeXvcMjBTmjXPkjU++BCl5+77sMMdnBV2XP+k2IIYNkZtNoaDlL6FVnqAOp9lq0y/3uzXunVe3eVhTsrAt7BLezkxOlv8oA4DBFyywFm3/wVedvTuCu9McE03SfLo5A21/pg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CJ0yEMPQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CJ0yEMPQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 071E8C4CEE3; Fri, 20 Jun 2025 12:59:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750424362; bh=2qYWiBHlm1D58irbmWAArbiJN15Rn+Us52EhPaaECuM=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=CJ0yEMPQZvDH6bs8tKIIFO7CBRERfZWGr2IgVOr9JpGNonBjYOy6+o1K16WpHlpf5 5zh3myT/PMYC6YwnaIt65QctkQo2uIAZeRnm1GpyvKRWsTjEmuu7iTU8mjJKhsREt8 U/1XgakoNmd4PJd2uU3x0U3Oq7ETNiRu1cGrjuWLhc3LxGbwIbMpXGC096NDxsDtrV TYnjrgY2WeNUk0EMkXiBdCKV8aLrwPBAKT3DhYyMqasJxpXqVFfoCI6b7nk001QgEA ttni+kK8bf24IptNAniHbs66IlSjoVvennsocBVzAGfXHR/SkI8PDsj38xByvf3By8 k9sBX/i8M/ZgQ== Message-ID: <90e0be81e22228f846ccb8435689c7a699bb3d3a.camel@kernel.org> Subject: Re: [PATCH 1/3] nfsd: provide proper locking for all write_ function From: Jeff Layton To: NeilBrown , Chuck Lever Cc: linux-nfs@vger.kernel.org, Olga Kornievskaia , Dai Ngo , Tom Talpey , Li Lingfeng Date: Fri, 20 Jun 2025 08:59:20 -0400 In-Reply-To: <20250618213347.425503-2-neil@brown.name> References: <20250618213347.425503-1-neil@brown.name> <20250618213347.425503-2-neil@brown.name> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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to handle IO to files in /proc/fs/nfsd/. > The can be called at any time and so generally need locking to ensure > they don't happen at an awkward time. >=20 > Many already take nfsd_mutex and check if nfsd_serv has been set. This > ensures they only run when the server is fully configured. >=20 > write_filehandle() does *not* need locking. It interacts with the > export table which is set up when the netns is set up, so it is always > valid and it has its own locking. write_filehandle() is needed before > the nfs server is started so checking nfsd_serv would be wrong. >=20 > The remaining files which do not have any locking are > write_v4_end_grace(), write_unlock_ip(), and write_unlock_fs(). > None of these make sense when the nfs server is not running and there is > evidence that write_v4_end_grace() can race with ->client_tracking_op > setup/shutdown and cause problems. >=20 > This patch adds locking to these three and ensures the "unlock" > functions abort if ->nfsd_serv is not set. >=20 > Reported-by: Li Lingfeng > Signed-off-by: NeilBrown > --- > fs/nfsd/nfsctl.c | 115 +++++++++++++++++++++++++++++++---------------- > 1 file changed, 77 insertions(+), 38 deletions(-) >=20 > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c > index 3f3e9f6c4250..3710a1992d17 100644 > --- a/fs/nfsd/nfsctl.c > +++ b/fs/nfsd/nfsctl.c > @@ -200,27 +200,18 @@ static inline struct net *netns(struct file *file) > return file_inode(file)->i_sb->s_fs_info; > } > =20 > -/* > - * write_unlock_ip - Release all locks used by a client > - * > - * Experimental. > - * > - * Input: > - * buf: '\n'-terminated C string containing a > - * presentation format IP address > - * size: length of C string in @buf > - * Output: > - * On success: returns zero if all specified locks were released; > - * returns one if one or more locks were not released > - * On error: return code is negative errno value > - */ > -static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size= ) > +static ssize_t __write_unlock_ip(struct file *file, char *buf, size_t si= ze) > { > struct sockaddr_storage address; > struct sockaddr *sap =3D (struct sockaddr *)&address; > size_t salen =3D sizeof(address); > char *fo_path; > struct net *net =3D netns(file); > + struct nfsd_net *nn =3D net_generic(net, nfsd_net_id); > + > + if (!nn->nfsd_serv) > + /* There cannot be any files to unlock */ > + return -EINVAL; > =20 > /* sanity check */ > if (size =3D=3D 0) > @@ -241,24 +232,39 @@ static ssize_t write_unlock_ip(struct file *file, c= har *buf, size_t size) > } > =20 > /* > - * write_unlock_fs - Release all locks on a local file system > + * write_unlock_ip - Release all locks used by a client > * > * Experimental. > * > * Input: > - * buf: '\n'-terminated C string containing the > - * absolute pathname of a local file system > + * buf: '\n'-terminated C string containing a > + * presentation format IP address > * size: length of C string in @buf > * Output: > * On success: returns zero if all specified locks were released; > * returns one if one or more locks were not released > * On error: return code is negative errno value > */ > -static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size= ) > +static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size= ) > +{ > + ssize_t rv; > + > + mutex_lock(&nfsd_mutex); > + rv =3D __write_unlock_ip(file, buf, size); > + mutex_unlock(&nfsd_mutex); > + return rv; > +} > + > +static ssize_t __write_unlock_fs(struct file *file, char *buf, size_t si= ze) > { > struct path path; > char *fo_path; > int error; > + struct nfsd_net *nn =3D net_generic(netns(file), nfsd_net_id); > + > + if (!nn->nfsd_serv) > + /* There cannot be any files to unlock */ > + return -EINVAL; > =20 > /* sanity check */ > if (size =3D=3D 0) > @@ -291,6 +297,30 @@ static ssize_t write_unlock_fs(struct file *file, ch= ar *buf, size_t size) > return error; > } > =20 > +/* > + * write_unlock_fs - Release all locks on a local file system > + * > + * Experimental. > + * > + * Input: > + * buf: '\n'-terminated C string containing the > + * absolute pathname of a local file system > + * size: length of C string in @buf > + * Output: > + * On success: returns zero if all specified locks were released; > + * returns one if one or more locks were not released > + * On error: return code is negative errno value > + */ > +static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size= ) > +{ > + ssize_t rv; > + > + mutex_lock(&nfsd_mutex); > + rv =3D __write_unlock_fs(file, buf, size); > + mutex_unlock(&nfsd_mutex); > + return rv; > +} > + > /* > * write_filehandle - Get a variable-length NFS file handle by path > * > @@ -1053,6 +1083,29 @@ static ssize_t write_recoverydir(struct file *file= , char *buf, size_t size) > } > #endif > =20 > +static ssize_t __write_v4_end_grace(struct file *file, char *buf, size_t= size) > +{ > + struct nfsd_net *nn =3D net_generic(netns(file), nfsd_net_id); > + > + if (size > 0) { > + switch(buf[0]) { > + case 'Y': > + case 'y': > + case '1': > + if (!nn->nfsd_serv) > + return -EBUSY; > + trace_nfsd_end_grace(netns(file)); > + nfsd4_end_grace(nn); > + break; > + default: > + return -EINVAL; > + } > + } > + > + return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%c\n", > + nn->grace_ended ? 'Y' : 'N'); > +} > + > /* > * write_v4_end_grace - release grace period for nfsd's v4.x lock manage= r > * > @@ -1075,27 +1128,13 @@ static ssize_t write_recoverydir(struct file *fil= e, char *buf, size_t size) > */ > static ssize_t write_v4_end_grace(struct file *file, char *buf, size_t s= ize) > { > - struct nfsd_net *nn =3D net_generic(netns(file), nfsd_net_id); > - > - if (size > 0) { > - switch(buf[0]) { > - case 'Y': > - case 'y': > - case '1': > - if (!nn->nfsd_serv) > - return -EBUSY; > - trace_nfsd_end_grace(netns(file)); > - nfsd4_end_grace(nn); > - break; > - default: > - return -EINVAL; > - } > - } > + ssize_t rv; > =20 > - return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%c\n", > - nn->grace_ended ? 'Y' : 'N'); > + mutex_lock(&nfsd_mutex); > + rv =3D __write_v4_end_grace(file, buf, size); > + mutex_unlock(&nfsd_mutex); > + return rv; > } > - > #endif > =20 > /*----------------------------------------------------------------------= ------*/ Reviewed-by: Jeff Layton