Btrfs: Fixes for 2.6.18 enterprise kernels

2.6.18 seems to get caught in an infinite loop when
cancel_rearming_delayed_workqueue is called more than once, so this switches
to cancel_delayed_work, which is arguably more correct.

Also, balance_dirty_pages can run into problems with 2.6.18 based kernels
because it doesn't have the per-bdi dirty limits.  This avoids calling
balance_dirty_pages on the btree inode unless there is actually something
to balance, which is a good optimization in general.

Finally there's a compile fix for ordered-data.h

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 19 insertions, 5 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e35e70165b53..fabc31b334b6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1548,6 +1548,7 @@ int close_ctree(struct btrfs_root *root)
         btrfs_commit_transaction(trans, root);
         ret = btrfs_write_and_wait_transaction(NULL, root);
         BUG_ON(ret);
+
         write_ctree_super(NULL, root);
         mutex_unlock(&fs_info->fs_mutex);
 
@@ -1583,17 +1584,17 @@ int close_ctree(struct btrfs_root *root)
         extent_io_tree_empty_lru(&fs_info->extent_ins);
         extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);
 
-        flush_workqueue(end_io_workqueue);
         flush_workqueue(async_submit_workqueue);
+        flush_workqueue(end_io_workqueue);
 
         truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
 
-        flush_workqueue(end_io_workqueue);
-        destroy_workqueue(end_io_workqueue);
-
         flush_workqueue(async_submit_workqueue);
         destroy_workqueue(async_submit_workqueue);
 
+        flush_workqueue(end_io_workqueue);
+        destroy_workqueue(end_io_workqueue);
+
         iput(fs_info->btree_inode);
 #if 0
         while(!list_empty(&fs_info->hashers)) {
@@ -1663,8 +1664,21 @@ void btrfs_throttle(struct btrfs_root *root)
 
 void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
 {
-        balance_dirty_pages_ratelimited_nr(
+        struct extent_io_tree *tree;
+        u64 num_dirty;
+        u64 start = 0;
+        unsigned long thresh = 16 * 1024 * 1024;
+        tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
+
+        if (current_is_pdflush())
+                return;
+
+        num_dirty = count_range_bits(tree, &start, (u64)-1,
+                                     thresh, EXTENT_DIRTY);
+        if (num_dirty > thresh) {
+                balance_dirty_pages_ratelimited_nr(
                                    root->fs_info->btree_inode->i_mapping, 1);
+        }
 }
 
 void btrfs_set_buffer_defrag(struct extent_buffer *buf)