3 files changed, 22 insertions, 9 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index f032e6e1e09a..5f6553ef1ba7 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -45,6 +45,17 @@ static struct timer_list sync_supers_timer;
 static int bdi_sync_supers(void *);
 static void sync_supers_timer_fn(unsigned long);
 
+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>
@@ -67,14 +78,14 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
         struct inode *inode;
 
         nr_dirty = nr_io = nr_more_io = 0;
-        spin_lock(&inode_wb_list_lock);
+        spin_lock(&wb->list_lock);
         list_for_each_entry(inode, &wb->b_dirty, i_wb_list)
                 nr_dirty++;
         list_for_each_entry(inode, &wb->b_io, i_wb_list)
                 nr_io++;
         list_for_each_entry(inode, &wb->b_more_io, i_wb_list)
                 nr_more_io++;
-        spin_unlock(&inode_wb_list_lock);
+        spin_unlock(&wb->list_lock);
 
         global_dirty_limits(&background_thresh, &dirty_thresh);
         bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
@@ -628,6 +639,7 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
         INIT_LIST_HEAD(&wb->b_dirty);
         INIT_LIST_HEAD(&wb->b_io);
         INIT_LIST_HEAD(&wb->b_more_io);
+        spin_lock_init(&wb->list_lock);
         setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi);
 }
 
@@ -676,11 +688,12 @@ void bdi_destroy(struct backing_dev_info *bdi)
         if (bdi_has_dirty_io(bdi)) {
                 struct bdi_writeback *dst = &default_backing_dev_info.wb;
 
-                spin_lock(&inode_wb_list_lock);
+                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(&inode_wb_list_lock);
+                spin_unlock(&bdi->wb.list_lock);
+                spin_unlock(&dst->list_lock);
         }
 
         bdi_unregister(bdi);
diff --git a/mm/filemap.c b/mm/filemap.c
index d7b10578a64b..1e492c3dd6f8 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -81,7 +81,7 @@
  *  ->i_mutex
  *    ->i_alloc_sem             (various)
  *
- *  inode_wb_list_lock
+ *  bdi->wb.list_lock
  *    sb_lock                   (fs/fs-writeback.c)
  *    ->mapping->tree_lock      (__sync_single_inode)
  *
@@ -99,9 +99,9 @@
  *    ->zone.lru_lock           (check_pte_range->isolate_lru_page)
  *    ->private_lock            (page_remove_rmap->set_page_dirty)
  *    ->tree_lock               (page_remove_rmap->set_page_dirty)
- *    inode_wb_list_lock        (page_remove_rmap->set_page_dirty)
+ *    bdi.wb->list_lock         (page_remove_rmap->set_page_dirty)
  *    ->inode->i_lock           (page_remove_rmap->set_page_dirty)
- *    inode_wb_list_lock        (zap_pte_range->set_page_dirty)
+ *    bdi.wb->list_lock         (zap_pte_range->set_page_dirty)
  *    ->inode->i_lock           (zap_pte_range->set_page_dirty)
  *    ->private_lock            (zap_pte_range->__set_page_dirty_buffers)
  *
diff --git a/mm/rmap.c b/mm/rmap.c
index 0eb463ea88dd..d04e36a7cc9f 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -32,11 +32,11 @@
  *               mmlist_lock (in mmput, drain_mmlist and others)
  *               mapping->private_lock (in __set_page_dirty_buffers)
  *               inode->i_lock (in set_page_dirty's __mark_inode_dirty)
- *               inode_wb_list_lock (in set_page_dirty's __mark_inode_dirty)
+ *               bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
  *                 sb_lock (within inode_lock in fs/fs-writeback.c)
  *                 mapping->tree_lock (widely used, in set_page_dirty,
  *                           in arch-dependent flush_dcache_mmap_lock,
- *                           within inode_wb_list_lock in __sync_single_inode)
+ *                           within bdi.wb->list_lock in __sync_single_inode)
  *
  * (code doesn't rely on that order so it could be switched around)
  * ->tasklist_lock