1 files changed, 38 insertions, 1 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 67a33a5a1a93..707d0dc6da0f 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -11,6 +11,8 @@
 #include <linux/writeback.h>
 #include <linux/device.h>
 
+static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
+
 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
 {
 }
@@ -25,6 +27,11 @@ struct backing_dev_info default_backing_dev_info = {
 };
 EXPORT_SYMBOL_GPL(default_backing_dev_info);
 
+struct backing_dev_info noop_backing_dev_info = {
+        .name           = "noop",
+};
+EXPORT_SYMBOL_GPL(noop_backing_dev_info);
+
 static struct class *bdi_class;
 
 /*
@@ -227,6 +234,9 @@ static struct device_attribute bdi_dev_attrs[] = {
 static __init int bdi_class_init(void)
 {
         bdi_class = class_create(THIS_MODULE, "bdi");
+        if (IS_ERR(bdi_class))
+                return PTR_ERR(bdi_class);
+
         bdi_class->dev_attrs = bdi_dev_attrs;
         bdi_debug_init();
         return 0;
@@ -609,7 +619,7 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
          * it would never exet if it is currently stuck in the refrigerator.
          */
         list_for_each_entry(wb, &bdi->wb_list, list) {
-                wb->task->flags &= ~PF_FROZEN;
+                thaw_process(wb->task);
                 kthread_stop(wb->task);
         }
 }
@@ -712,6 +722,33 @@ void bdi_destroy(struct backing_dev_info *bdi)
 }
 EXPORT_SYMBOL(bdi_destroy);
 
+/*
+ * For use from filesystems to quickly init and register a bdi associated
+ * with dirty writeback
+ */
+int bdi_setup_and_register(struct backing_dev_info *bdi, char *name,
+                           unsigned int cap)
+{
+        char tmp[32];
+        int err;
+
+        bdi->name = name;
+        bdi->capabilities = cap;
+        err = bdi_init(bdi);
+        if (err)
+                return err;
+
+        sprintf(tmp, "%.28s%s", name, "-%d");
+        err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq));
+        if (err) {
+                bdi_destroy(bdi);
+                return err;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL(bdi_setup_and_register);
+
 static wait_queue_head_t congestion_wqh[2] = {
                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])