From: Richard Weinberger Date: Wed, 7 Dec 2022 08:43:08 +0000 (+0100) Subject: fs: namei: Allow follow_down() to uncover auto mounts X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e1f19857f94be09f9526f180e64f20138bd4e394;p=linux.git 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 Reviewed-by: Ian Kent Reviewed-by: Jeff Layton Acked-by: Al Viro Signed-off-by: Chuck Lever --- 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 *);