Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:

 - a few misc things

 - kexec updates

 - DMA-mapping updates to better support networking DMA operations

 - IPC updates

 - various MM changes to improve DAX fault handling

 - lots of radix-tree changes, mainly to the test suite. All leading up
   to reimplementing the IDA/IDR code to be a wrapper layer over the
   radix-tree. However the final trigger-pulling patch is held off for
   4.11.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (114 commits)
  radix tree test suite: delete unused rcupdate.c
  radix tree test suite: add new tag check
  radix-tree: ensure counts are initialised
  radix tree test suite: cache recently freed objects
  radix tree test suite: add some more functionality
  idr: reduce the number of bits per level from 8 to 6
  rxrpc: abstract away knowledge of IDR internals
  tpm: use idr_find(), not idr_find_slowpath()
  idr: add ida_is_empty
  radix tree test suite: check multiorder iteration
  radix-tree: fix replacement for multiorder entries
  radix-tree: add radix_tree_split_preload()
  radix-tree: add radix_tree_split
  radix-tree: add radix_tree_join
  radix-tree: delete radix_tree_range_tag_if_tagged()
  radix-tree: delete radix_tree_locate_item()
  radix-tree: improve multiorder iterators
  btrfs: fix race in btrfs_free_dummy_fs_info()
  radix-tree: improve dump output
  radix-tree: make radix_tree_find_next_bit more useful
  ...

1 files changed, 18 insertions, 10 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 52e2f8e3b472..290e8b7d3181 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2106,18 +2106,26 @@ void tag_pages_for_writeback(struct address_space *mapping,
                              pgoff_t start, pgoff_t end)
 {
 #define WRITEBACK_TAG_BATCH 4096
-        unsigned long tagged;
-
-        do {
-                spin_lock_irq(&mapping->tree_lock);
-                tagged = radix_tree_range_tag_if_tagged(&mapping->page_tree,
-                                &start, end, WRITEBACK_TAG_BATCH,
-                                PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE);
+        unsigned long tagged = 0;
+        struct radix_tree_iter iter;
+        void **slot;
+
+        spin_lock_irq(&mapping->tree_lock);
+        radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, start,
+                                                        PAGECACHE_TAG_DIRTY) {
+                if (iter.index > end)
+                        break;
+                radix_tree_iter_tag_set(&mapping->page_tree, &iter,
+                                                        PAGECACHE_TAG_TOWRITE);
+                tagged++;
+                if ((tagged % WRITEBACK_TAG_BATCH) != 0)
+                        continue;
+                slot = radix_tree_iter_resume(slot, &iter);
                 spin_unlock_irq(&mapping->tree_lock);
-                WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH);
                 cond_resched();
-                /* We check 'start' to handle wrapping when end == ~0UL */
-        } while (tagged >= WRITEBACK_TAG_BATCH && start);
+                spin_lock_irq(&mapping->tree_lock);
+        }
+        spin_unlock_irq(&mapping->tree_lock);
 }
 EXPORT_SYMBOL(tag_pages_for_writeback);