__d_unalias() should refuse to move mountpoints
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/dcache.c b/fs/dcache.c
index 015586f..8086636 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2387,14 +2387,13 @@
struct dentry *dentry, struct dentry *alias)
{
struct mutex *m1 = NULL, *m2 = NULL;
- struct dentry *ret;
+ struct dentry *ret = ERR_PTR(-EBUSY);
/* If alias and dentry share a parent, then no extra locks required */
if (alias->d_parent == dentry->d_parent)
goto out_unalias;
/* See lock_rename() */
- ret = ERR_PTR(-EBUSY);
if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
goto out_err;
m1 = &dentry->d_sb->s_vfs_rename_mutex;
@@ -2402,8 +2401,10 @@
goto out_err;
m2 = &alias->d_parent->d_inode->i_mutex;
out_unalias:
- __d_move(alias, dentry);
- ret = alias;
+ if (likely(!d_mountpoint(alias))) {
+ __d_move(alias, dentry);
+ ret = alias;
+ }
out_err:
spin_unlock(&inode->i_lock);
if (m2)