Return-Path: Received: from mail-pg0-f68.google.com ([74.125.83.68]:35894 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S969474AbdAEOqh (ORCPT ); Thu, 5 Jan 2017 09:46:37 -0500 Received: by mail-pg0-f68.google.com with SMTP id 75so2696725pgf.3 for ; Thu, 05 Jan 2017 06:46:36 -0800 (PST) Subject: [PATCH v2] NFSD: Only support readonly export for !fsync and readonly filesystem To: "J. Bruce Fields" , linux-nfs@vger.kernel.org References: <960d206f-3cb5-b60e-5245-d7282dabf664@gmail.com> Cc: Christoph Hellwig , Steve Dickson , kinglongmee@gmail.com From: Kinglong Mee Message-ID: Date: Thu, 5 Jan 2017 22:46:24 +0800 MIME-Version: 1.0 In-Reply-To: <960d206f-3cb5-b60e-5245-d7282dabf664@gmail.com> Content-Type: text/plain; charset=utf-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: Commit fae5096ad217 "nfsd: assume writeable exportabled filesystems have f_sync" have remove the checking of f_sync. Christoph Hellwig suggests, "Warn and refuse the writable export." I think just covert to a readonly export for !fsync filesystem and readonly filesystem is reasonable. For example, A test directory may be mounted many underlay filesystem (contain ISO9660, f2fs, etc) frequently. If refuse the writeable export, for ISO9660 the exports entry must be *(ro,...), but for f2fs may be *(rw,...). I don't think someone wants change it every time. Also, I let the message as a dprintk for, an export entry cache will be dropped without any use in some times, and created in the next use. If let the message as a warning, there will be many messages that users maybe think that's a noise or bug. v2, update the notice message advice from Bruce just pass svc_exoprt to check_export instead many parameters a path string for exporting entry is simply than d_path Signed-off-by: Kinglong Mee --- fs/nfsd/export.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 43e109c..5b9527b 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -339,8 +339,10 @@ static struct svc_export *svc_export_update(struct svc_export *new, struct svc_export *old); static struct svc_export *svc_export_lookup(struct svc_export *); -static int check_export(struct inode *inode, int *flags, unsigned char *uuid) +static int check_export(struct svc_export *exp, char *path_str) { + struct inode *inode = d_inode(exp->ex_path.dentry); + int *flags = &exp->ex_flags; /* * We currently export only dirs, regular files, and (for v4 @@ -358,6 +360,18 @@ static int check_export(struct inode *inode, int *flags, unsigned char *uuid) if (*flags & NFSEXP_V4ROOT) *flags |= NFSEXP_READONLY; + /* + * Convert to a readonly export for that, + * 1. not supported fsync filesystem, + * 2. readonly filesystem. + */ + if ((!inode->i_fop->fsync || IS_RDONLY(inode)) + && !(*flags & NFSEXP_READONLY)) { + dprintk("%s %s: exporting read-only.\n", path_str, + IS_RDONLY(inode) ? "is read-only" : "has no fsync method"); + *flags |= NFSEXP_READONLY; + } + /* There are two requirements on a filesystem to be exportable. * 1: We must be able to identify the filesystem from a number. * either a device number (so FS_REQUIRES_DEV needed) @@ -367,7 +381,7 @@ static int check_export(struct inode *inode, int *flags, unsigned char *uuid) */ if (!(inode->i_sb->s_type->fs_flags & FS_REQUIRES_DEV) && !(*flags & NFSEXP_FSID) && - uuid == NULL) { + exp->ex_uuid == NULL) { dprintk("exp_export: export of non-dev fs without fsid\n"); return -EINVAL; } @@ -509,7 +523,7 @@ uuid_parse(char **mesg, char *buf, unsigned char **puuid) static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) { /* client path expiry [flags anonuid anongid fsid] */ - char *buf; + char *buf, *path_str = NULL; int len; int err; struct auth_domain *dom = NULL; @@ -544,6 +558,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) if (err) goto out1; + path_str = kstrdup(buf, GFP_KERNEL); exp.ex_client = dom; exp.cd = cd; exp.ex_devid_map = NULL; @@ -599,8 +614,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) goto out4; } - err = check_export(d_inode(exp.ex_path.dentry), &exp.ex_flags, - exp.ex_uuid); + err = check_export(&exp, path_str); if (err) goto out4; /* @@ -645,6 +659,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) out1: auth_domain_put(dom); out: + kfree(path_str); kfree(buf); return err; } -- 2.9.3