From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 16 Dec 2016 21:34:52 +0000 (-0500)
Subject: Merge branch 'work.autofs' into for-linus
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=9763f7a4a5f7b1a7c480fa06d01b2bad25163c0a;p=linux-beck.git

Merge branch 'work.autofs' into for-linus

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

9763f7a4a5f7b1a7c480fa06d01b2bad25163c0a
diff --cc fs/namespace.c
index 9ad88a45b3e3,7a73383e8365..f7e28f8ea04d
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@@ -1159,7 -1159,36 +1159,36 @@@ struct vfsmount *mntget(struct vfsmoun
  }
  EXPORT_SYMBOL(mntget);
  
+ /* path_is_mountpoint() - Check if path is a mount in the current
+  *                          namespace.
+  *
+  *  d_mountpoint() can only be used reliably to establish if a dentry is
+  *  not mounted in any namespace and that common case is handled inline.
+  *  d_mountpoint() isn't aware of the possibility there may be multiple
+  *  mounts using a given dentry in a different namespace. This function
+  *  checks if the passed in path is a mountpoint rather than the dentry
+  *  alone.
+  */
+ bool path_is_mountpoint(const struct path *path)
+ {
+ 	unsigned seq;
+ 	bool res;
+ 
+ 	if (!d_mountpoint(path->dentry))
+ 		return false;
+ 
+ 	rcu_read_lock();
+ 	do {
+ 		seq = read_seqbegin(&mount_lock);
+ 		res = __path_is_mountpoint(path);
+ 	} while (read_seqretry(&mount_lock, seq));
+ 	rcu_read_unlock();
+ 
+ 	return res;
+ }
+ EXPORT_SYMBOL(path_is_mountpoint);
+ 
 -struct vfsmount *mnt_clone_internal(struct path *path)
 +struct vfsmount *mnt_clone_internal(const struct path *path)
  {
  	struct mount *p;
  	p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE);