introduce kern_path_mountpoint()

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

1 files changed, 24 insertions, 11 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 11184df3307e..e412421210cc 100644
--- 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.