3 files changed, 31 insertions, 7 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index e616f8872e69..12394a90d60f 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -37,6 +37,7 @@
 #define BTRFS_INODE_IN_DEFRAG                   3
 #define BTRFS_INODE_DELALLOC_META_RESERVED      4
 #define BTRFS_INODE_HAS_ORPHAN_ITEM             5
+#define BTRFS_INODE_HAS_ASYNC_EXTENT            6
 
 /* in memory btrfs inode */
 struct btrfs_inode {
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 06075043da5d..7a090fb4eb98 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1398,20 +1398,23 @@ static int run_delalloc_range(struct inode *inode, struct page *locked_page,
         int ret;
         struct btrfs_root *root = BTRFS_I(inode)->root;
 
-        if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW)
+        if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) {
                 ret = run_delalloc_nocow(inode, locked_page, start, end,
                                          page_started, 1, nr_written);
-        else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC)
+        } else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC) {
                 ret = run_delalloc_nocow(inode, locked_page, start, end,
                                          page_started, 0, nr_written);
-        else if (!btrfs_test_opt(root, COMPRESS) &&
-                 !(BTRFS_I(inode)->force_compress) &&
-                 !(BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS))
+        } else if (!btrfs_test_opt(root, COMPRESS) &&
+                   !(BTRFS_I(inode)->force_compress) &&
+                   !(BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS)) {
                 ret = cow_file_range(inode, locked_page, start, end,
                                       page_started, nr_written, 1);
-        else
+        } else {
+                set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+                        &BTRFS_I(inode)->runtime_flags);
                 ret = cow_file_range_async(inode, locked_page, start, end,
                                            page_started, nr_written);
+        }
         return ret;
 }
 
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;