From e1f19857f94be09f9526f180e64f20138bd4e394 Mon Sep 17 00:00:00 2001
From: Richard Weinberger <richard@nod.at>
Date: Wed, 7 Dec 2022 09:43:08 +0100
Subject: [PATCH] fs: namei: Allow follow_down() to uncover auto mounts
This function is only used by NFSD to cross mount points.
If a mount point is of type auto mount, follow_down() will
not uncover it. Add LOOKUP_AUTOMOUNT to the lookup flags
to have ->d_automount() called when NFSD walks down the
mount tree.
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Ian Kent <raven@themaw.net>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
fs/namei.c | 6 +++---
fs/nfsd/vfs.c | 6 +++++-
include/linux/namei.h | 2 +-
3 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 309ae6fc8c993..c06f470660630 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1458,11 +1458,11 @@ EXPORT_SYMBOL(follow_down_one);
* point, the filesystem owning that dentry may be queried as to whether the
* caller is permitted to proceed or not.
*/
-int follow_down(struct path *path)
+int follow_down(struct path *path, unsigned int flags)
{
struct vfsmount *mnt = path->mnt;
bool jumped;
- int ret = traverse_mounts(path, &jumped, NULL, 0);
+ int ret = traverse_mounts(path, &jumped, NULL, flags);
if (path->mnt != mnt)
mntput(mnt);
@@ -2864,7 +2864,7 @@ int path_pts(struct path *path)
path->dentry = child;
dput(parent);
- follow_down(path);
+ follow_down(path, 0);
return 0;
}
#endif
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 780856561bbba..21d5209f6e041 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -126,9 +126,13 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
struct dentry *dentry = *dpp;
struct path path = {.mnt = mntget(exp->ex_path.mnt),
.dentry = dget(dentry)};
+ unsigned int follow_flags = 0;
int err = 0;
- err = follow_down(&path);
+ if (exp->ex_flags & NFSEXP_CROSSMOUNT)
+ follow_flags = LOOKUP_AUTOMOUNT;
+
+ err = follow_down(&path, follow_flags);
if (err < 0)
goto out;
if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 00fee52df8423..c82e2ac658464 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -77,7 +77,7 @@ struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns,
struct dentry *base, int len);
extern int follow_down_one(struct path *);
-extern int follow_down(struct path *);
+extern int follow_down(struct path *path, unsigned int flags);
extern int follow_up(struct path *);
extern struct dentry *lock_rename(struct dentry *, struct dentry *);
--
2.30.2