Merge branch 'for-jens' of git://git.drbd.org/linux-drbd into for-3.6/drivers

1 files changed, 21 insertions, 1 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 9e138cdc36c5..643335a4fe3c 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -627,7 +627,27 @@ void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
         /* start IO across the range first to instantiate any delalloc
          * extents
          */
-        filemap_write_and_wait_range(inode->i_mapping, start, orig_end);
+        filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
+
+        /*
+         * So with compression we will find and lock a dirty page and clear the
+         * first one as dirty, setup an async extent, and immediately return
+         * with the entire range locked but with nobody actually marked with
+         * writeback.  So we can't just filemap_write_and_wait_range() and
+         * expect it to work since it will just kick off a thread to do the
+         * actual work.  So we need to call filemap_fdatawrite_range _again_
+         * since it will wait on the page lock, which won't be unlocked until
+         * after the pages have been marked as writeback and so we're good to go
+         * from there.  We have to do this otherwise we'll miss the ordered
+         * extents and that results in badness.  Please Josef, do not think you
+         * know better and pull this out at some point in the future, it is
+         * right and you are wrong.
+         */
+        if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+                     &BTRFS_I(inode)->runtime_flags))
+                filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
+
+        filemap_fdatawait_range(inode->i_mapping, start, orig_end);
 
         end = orig_end;
         found = 0;