Merge branch 'work.namespace' into for-linus

[linux-2.6-block.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index 141d5776c70e30814829ce13cc2ca1fa3f7cefd6..b5b1259e064f8d9661110ba1f1f73d1a0ff19d51 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -674,7 +674,7 @@ out:
  *
  * lookup_mnt takes a reference to the found vfsmount.
  */
-struct vfsmount *lookup_mnt(struct path *path)
+struct vfsmount *lookup_mnt(const struct path *path)
 {
        struct mount *child_mnt;
        struct vfsmount *m;
@@ -1157,7 +1157,36 @@ struct vfsmount *mntget(struct vfsmount *mnt)
 }
 EXPORT_SYMBOL(mntget);
 
-struct vfsmount *mnt_clone_internal(struct path *path)
+/* 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(const struct path *path)
 {
        struct mount *p;
        p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE);
@@ -1756,7 +1785,7 @@ out:
 
 /* Caller should check returned pointer for errors */
 
-struct vfsmount *collect_mounts(struct path *path)
+struct vfsmount *collect_mounts(const struct path *path)
 {
        struct mount *tree;
        namespace_lock();
@@ -1789,7 +1818,7 @@ void drop_collected_mounts(struct vfsmount *mnt)
  *
  * Release with mntput().
  */
-struct vfsmount *clone_private_mount(struct path *path)
+struct vfsmount *clone_private_mount(const struct path *path)
 {
        struct mount *old_mnt = real_mount(path->mnt);
        struct mount *new_mnt;
@@ -2993,7 +3022,7 @@ bool is_path_reachable(struct mount *mnt, struct dentry *dentry,
        return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry);
 }
 
-bool path_is_under(struct path *path1, struct path *path2)
+bool path_is_under(const struct path *path1, const struct path *path2)
 {
        bool res;
        read_seqlock_excl(&mount_lock);