Btrfs: Update on disk i_size only after pending ordered extents are done

This changes the ordered data code to update i_size after the extent
is on disk.  An on disk i_size is maintained in the in-memory btrfs inode
structures, and this is updated as extents finish.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
index 33292c5..40e9126 100644
--- a/fs/btrfs/ordered-data.h
+++ b/fs/btrfs/ordered-data.h
@@ -89,4 +89,6 @@
 int btrfs_add_ordered_pending(struct inode *inode,
 			      struct btrfs_ordered_extent *ordered,
 			      u64 start, u64 len);
+int btrfs_ordered_update_i_size(struct inode *inode,
+				struct btrfs_ordered_extent *ordered);
 #endif