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b=aRe9D5Sa7gMB/Ryp1GcMwBIJ0XwKuZ6UClP6Ug45QHAha8tYj9mJ1V510E+A9msBF uIhFQ4ERVA2/a/89lazW/TqRbLmJXCbnATean6EIJEuIz/669usXdDh3OAv3cCVNyN 153NxFJ5bXU00TkkzzXLWoUrW/pQLk9vKivAvy3EIK99PwQxTlxQfnsqWQCzOs4xkV djsQKErslPGQtEcNguvZIqh3BSoWwOetopyqoeBHApuQa2uwYZV8JERw+NxlC0nR0n fOEHc48tTPF5j3kPLorwmV32bUWcgE0EFzjrgIlJjLHAtcT1r/8PEQ677OthtO1AHK xGnYGFr1AXgiA== From: Jeff Layton Date: Mon, 19 Jan 2026 11:26:47 -0500 Subject: [PATCH v2 30/31] nfsd: only allow filesystems that set EXPORT_OP_STABLE_HANDLES MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260119-exportfs-nfsd-v2-30-d93368f903bd@kernel.org> References: <20260119-exportfs-nfsd-v2-0-d93368f903bd@kernel.org> In-Reply-To: <20260119-exportfs-nfsd-v2-0-d93368f903bd@kernel.org> To: Christian Brauner , Alexander Viro , Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Amir Goldstein , Hugh Dickins , Baolin Wang , Andrew Morton , Theodore Ts'o , Andreas Dilger , Jan Kara , Gao Xiang , Chao Yu , Yue Hu , Jeffle Xu , Sandeep Dhavale , Hongbo Li , Chunhai Guo , Carlos Maiolino , Ilya Dryomov , Alex Markuze , Viacheslav Dubeyko , Chris Mason , David Sterba , Luis de Bethencourt , Salah Triki , Phillip Lougher , Steve French , Paulo Alcantara , Ronnie Sahlberg , Shyam Prasad N , Bharath SM , Miklos Szeredi , Mike Marshall , Martin Brandenburg , Mark Fasheh , Joel Becker , Joseph Qi , Konstantin Komarov , Ryusuke Konishi , Trond Myklebust , Anna Schumaker , Dave Kleikamp , David Woodhouse , Richard Weinberger , Jan Kara , Andreas Gruenbacher , OGAWA Hirofumi , Jaegeuk Kim , Jonathan Corbet Cc: David Laight , Dave Chinner , Christoph Hellwig , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-xfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, linux-unionfs@vger.kernel.org, devel@lists.orangefs.org, ocfs2-devel@lists.linux.dev, ntfs3@lists.linux.dev, linux-nilfs@vger.kernel.org, jfs-discussion@lists.sourceforge.net, linux-mtd@lists.infradead.org, gfs2@lists.linux.dev, linux-f2fs-devel@lists.sourceforge.net, linux-doc@vger.kernel.org, Jeff Layton X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; 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a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 X-Rspamd-Queue-Id: 75163140010 X-Stat-Signature: njy9c95uizw533dzefdgbf5smta8kabe X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1768840256-912481 X-HE-Meta: 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 jlwKq+QS /BetGt0pbqGG0um/W87tAj9FPfpHVw+sDFJBKEo72MYpY9a5HONUct+V981pIFbSsYghA0HEiZuq+GbOu2zXC230zqTdD22YFsC74f7N9JNDbQUbXMuCXvMJ54rWRAnubILKoyZujbxtEcuruW9UaEzvc3UZCyp9e5WUT42jIxMxYH+cgNisLBJ9m1pCUb7hkETXsZqpPoLzdQAoQ6j4nQD3ue8j5ACMy9j4uZcYtOk3wPONsq0NI0iWPcFKAGC/npQaKnpzYiDeuKgb7jH8rAKD32ponafbYua2/GQSHXKHXL/xbqUa0utRjyHfm1yijkL9QQ4v8zbKACvBjGJjXzvNxTl4qkvnd4sWeEjLdDIB/rso= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Some filesystems have grown export operations in order to provide filehandles for local usage. Some of these filesystems are unsuitable for use with nfsd, since their filehandles are not stable across reboots. In check_export(), check whether EXPORT_OP_STABLE_HANDLES is set and return -EINVAL if it isn't. Signed-off-by: Jeff Layton --- fs/nfsd/export.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 2a1499f2ad196a6033787260881e451146283bdc..bc703cf58bfa210c7c57d49f22f15bc10d7cfc91 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -422,13 +422,15 @@ static int check_export(const struct path *path, int *flags, unsigned char *uuid if (*flags & NFSEXP_V4ROOT) *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. + /* There are four 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) * or an FSID number (so NFSEXP_FSID or ->uuid is needed). - * 2: We must be able to find an inode from a filehandle. + * 2: We must be able to find an inode from a filehandle. * This means that s_export_op must be set. - * 3: We must not currently be on an idmapped mount. + * 3: It must provide stable filehandles. + * This means that EXPORT_OP_STABLE_HANDLES is set + * 4: We must not currently be on an idmapped mount. */ if (!(inode->i_sb->s_type->fs_flags & FS_REQUIRES_DEV) && !(*flags & NFSEXP_FSID) && @@ -442,6 +444,11 @@ static int check_export(const struct path *path, int *flags, unsigned char *uuid return -EINVAL; } + if (!(inode->i_sb->s_export_op->flags & EXPORT_OP_STABLE_HANDLES)) { + dprintk("%s: fs does not provide stable filehandles!\n", __func__); + return -EINVAL; + } + if (is_idmapped_mnt(path->mnt)) { dprintk("exp_export: export of idmapped mounts not yet supported.\n"); return -EINVAL; -- 2.52.0