[POWERPC] spufs: Fix error handling in spufs_fill_dir()

The error path in spufs_fill_dir() is broken. If d_alloc_name() or
spufs_new_file() fails, spufs_prune_dir() is getting called. At this time
dir->inode is not set and a NULL pointer is dereferenced by mutex_lock().
This bugfix replaces spufs_prune_dir() with a shorter version that does
not touch dir->inode but simply removes all children.

Signed-off-by: Sebastian Siewior <bigeasy@linux.vnet.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Acked-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/cell/spufs/inode.c

@@ -177,7 +177,7 @@ static int spufs_rmdir(struct inode *parent, struct dentry *dir)
 static int spufs_fill_dir(struct dentry *dir, struct tree_descr *files,
 			  int mode, struct spu_context *ctx)
 {
-	struct dentry *dentry;
+	struct dentry *dentry, *tmp;
 	int ret;
 
 	while (files->name && files->name[0]) {
@@ -193,7 +193,20 @@ static int spufs_fill_dir(struct dentry *dir, struct tree_descr *files,
 	}
 	return 0;
 out:
-	spufs_prune_dir(dir);
+	/*
+	 * remove all children from dir. dir->inode is not set so don't
+	 * just simply use spufs_prune_dir() and panic afterwards :)
+	 * dput() looks like it will do the right thing:
+	 * - dec parent's ref counter
+	 * - remove child from parent's child list
+	 * - free child's inode if possible
+	 * - free child
+	 */
+	list_for_each_entry_safe(dentry, tmp, &dir->d_subdirs, d_u.d_child) {
+		dput(dentry);
+	}
+
+	shrink_dcache_parent(dir);
 	return ret;
 }