introduce kern_path_mountpoint()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index 11184df3307ed270a3abd78ccc1043cb90959358..e412421210cc4bfae3a6659418dc932ecc7bdce6 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2360,6 +2360,20 @@ out:
        return err;
 }
 
+static int
+filename_mountpoint(int dfd, struct filename *s, struct path *path,
+                       unsigned int flags)
+{
+       int error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU);
+       if (unlikely(error == -ECHILD))
+               error = path_mountpoint(dfd, s->name, path, flags);
+       if (unlikely(error == -ESTALE))
+               error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL);
+       if (likely(!error))
+               audit_inode(s, path->dentry, 0);
+       return error;
+}
+
 /**
  * user_path_mountpoint_at - lookup a path from userland in order to umount it
  * @dfd:       directory file descriptor
@@ -2380,23 +2394,22 @@ user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags,
 {
        struct filename *s = getname(name);
        int error;
-
        if (IS_ERR(s))
                return PTR_ERR(s);
-
-       error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU);
-       if (unlikely(error == -ECHILD))
-               error = path_mountpoint(dfd, s->name, path, flags);
-       if (unlikely(error == -ESTALE))
-               error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL);
-
-       if (likely(!error))
-               audit_inode(s, path->dentry, 0);
-
+       error = filename_mountpoint(dfd, s, path, flags);
        putname(s);
        return error;
 }
 
+int
+kern_path_mountpoint(int dfd, const char *name, struct path *path,
+                       unsigned int flags)
+{
+       struct filename s = {.name = name};
+       return filename_mountpoint(dfd, &s, path, flags);
+}
+EXPORT_SYMBOL(kern_path_mountpoint);
+
 /*
  * It's inline, so penalty for filesystems that don't use sticky bit is
  * minimal.

diff --git a/include/linux/namei.h b/include/linux/namei.h
index 53c18f00d9fb463c10500ca7a99b8373c323d103..8e47bc7a1665b8b7e6ca06392584328aab702d82 100644 (file)
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -70,6 +70,7 @@ extern struct dentry *kern_path_create(int, const char *, struct path *, unsigne
 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
 extern void done_path_create(struct path *, struct dentry *);
 extern struct dentry *kern_path_locked(const char *, struct path *);
+extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
 
 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);