vfs: add lookup_hash() helper

Overlayfs needs lookup without inode_permission() and already has the name
hash (in form of dentry->d_name on overlayfs dentry).  It also doesn't
support filesystems with d_op->d_hash() so basically it only needs
the actual hashed lookup from lookup_one_len_unlocked()

So add a new helper that does unlocked lookup of a hashed name.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/namei.h b/include/linux/namei.h
index 77d01700daf7..ec5ec2818a28 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -79,6 +79,8 @@ extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
 
 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
+struct qstr;
+extern struct dentry *lookup_hash(const struct qstr *, struct dentry *);
 
 extern int follow_down_one(struct path *);
 extern int follow_down(struct path *);