1 files changed, 23 insertions, 67 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 52e0c7652448..1725adb242e0 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -37,17 +37,6 @@ LIST_HEAD(bdi_list);
 /* bdi_wq serves all asynchronous writeback tasks */
 struct workqueue_struct *bdi_wq;
 
-static void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)
-{
-        if (wb1 < wb2) {
-                spin_lock(&wb1->list_lock);
-                spin_lock_nested(&wb2->list_lock, 1);
-        } else {
-                spin_lock(&wb2->list_lock);
-                spin_lock_nested(&wb1->list_lock, 1);
-        }
-}
-
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
@@ -352,19 +341,19 @@ EXPORT_SYMBOL(bdi_register_dev);
  */
 static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 {
-        if (!bdi_cap_writeback_dirty(bdi))
+        /* Make sure nobody queues further work */
+        spin_lock_bh(&bdi->wb_lock);
+        if (!test_and_clear_bit(BDI_registered, &bdi->state)) {
+                spin_unlock_bh(&bdi->wb_lock);
                 return;
+        }
+        spin_unlock_bh(&bdi->wb_lock);
 
         /*
          * Make sure nobody finds us on the bdi_list anymore
          */
         bdi_remove_from_list(bdi);
 
-        /* Make sure nobody queues further work */
-        spin_lock_bh(&bdi->wb_lock);
-        clear_bit(BDI_registered, &bdi->state);
-        spin_unlock_bh(&bdi->wb_lock);
-
         /*
          * Drain work list and shutdown the delayed_work.  At this point,
          * @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi
@@ -372,37 +361,22 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
          */
         mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
         flush_delayed_work(&bdi->wb.dwork);
-        WARN_ON(!list_empty(&bdi->work_list));
-        WARN_ON(delayed_work_pending(&bdi->wb.dwork));
 }
 
 /*
- * This bdi is going away now, make sure that no super_blocks point to it
+ * Called when the device behind @bdi has been removed or ejected.
+ *
+ * We can't really do much here except for reducing the dirty ratio at
+ * the moment.  In the future we should be able to set a flag so that
+ * the filesystem can handle errors at mark_inode_dirty time instead
+ * of only at writeback time.
  */
-static void bdi_prune_sb(struct backing_dev_info *bdi)
-{
-        struct super_block *sb;
-
-        spin_lock(&sb_lock);
-        list_for_each_entry(sb, &super_blocks, s_list) {
-                if (sb->s_bdi == bdi)
-                        sb->s_bdi = &default_backing_dev_info;
-        }
-        spin_unlock(&sb_lock);
-}
-
 void bdi_unregister(struct backing_dev_info *bdi)
 {
-        if (bdi->dev) {
-                bdi_set_min_ratio(bdi, 0);
-                trace_writeback_bdi_unregister(bdi);
-                bdi_prune_sb(bdi);
+        if (WARN_ON_ONCE(!bdi->dev))
+                return;
 
-                bdi_wb_shutdown(bdi);
-                bdi_debug_unregister(bdi);
-                device_unregister(bdi->dev);
-                bdi->dev = NULL;
-        }
+        bdi_set_min_ratio(bdi, 0);
 }
 EXPORT_SYMBOL(bdi_unregister);
 
@@ -471,37 +445,19 @@ void bdi_destroy(struct backing_dev_info *bdi)
 {
         int i;
 
-        /*
-         * Splice our entries to the default_backing_dev_info.  This
-         * condition shouldn't happen.  @wb must be empty at this point and
-         * dirty inodes on it might cause other issues.  This workaround is
-         * added by ce5f8e779519 ("writeback: splice dirty inode entries to
-         * default bdi on bdi_destroy()") without root-causing the issue.
-         *
-         * http://lkml.kernel.org/g/1253038617-30204-11-git-send-email-jens.axboe@oracle.com
-         * http://thread.gmane.org/gmane.linux.file-systems/35341/focus=35350
-         *
-         * We should probably add WARN_ON() to find out whether it still
-         * happens and track it down if so.
-         */
-        if (bdi_has_dirty_io(bdi)) {
-                struct bdi_writeback *dst = &default_backing_dev_info.wb;
-
-                bdi_lock_two(&bdi->wb, dst);
-                list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
-                list_splice(&bdi->wb.b_io, &dst->b_io);
-                list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
-                spin_unlock(&bdi->wb.list_lock);
-                spin_unlock(&dst->list_lock);
-        }
-
-        bdi_unregister(bdi);
+        bdi_wb_shutdown(bdi);
 
+        WARN_ON(!list_empty(&bdi->work_list));
         WARN_ON(delayed_work_pending(&bdi->wb.dwork));
 
+        if (bdi->dev) {
+                bdi_debug_unregister(bdi);
+                device_unregister(bdi->dev);
+                bdi->dev = NULL;
+        }
+
         for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
                 percpu_counter_destroy(&bdi->bdi_stat[i]);
-
         fprop_local_destroy_percpu(&bdi->completions);
 }
 EXPORT_SYMBOL(bdi_destroy);