configfs: Don't try to d_delete() negative dentries.

When configfs is faking mkdir() on its subsystem or default group
objects, it starts by adding a negative dentry.  It then tries to
instantiate the group.  If that should fail, it must clean up after
itself.

I was using d_delete() here, but configfs_attach_group() promises to
return an empty dentry on error.  d_delete() explodes with the entry
dentry.  Let's try d_drop() instead.  The unhashing is what we want for
our dentry.

Signed-off-by: Joel Becker <jlbec@evilplan.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 3313dd19f543..b11d7342eef2 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -689,7 +689,8 @@ static int create_default_group(struct config_group *parent_group,
                         sd = child->d_fsdata;
                         sd->s_type |= CONFIGFS_USET_DEFAULT;
                 } else {
-                        d_delete(child);
+                        BUG_ON(child->d_inode);
+                        d_drop(child);
                         dput(child);
                 }
         }
@@ -1683,7 +1684,8 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
                 err = configfs_attach_group(sd->s_element, &group->cg_item,
                                             dentry);
                 if (err) {
-                        d_delete(dentry);
+                        BUG_ON(dentry->d_inode);
+                        d_drop(dentry);
                         dput(dentry);
                 } else {
                         spin_lock(&configfs_dirent_lock);