1 files changed, 10 insertions, 0 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 61205e3bbefa..1da5753d886d 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -196,6 +196,16 @@ struct btrfs_inode {
         struct list_head delayed_iput;
         long delayed_iput_count;
 
+        /*
+         * To avoid races between lockless (i_mutex not held) direct IO writes
+         * and concurrent fsync requests. Direct IO writes must acquire read
+         * access on this semaphore for creating an extent map and its
+         * corresponding ordered extent. The fast fsync path must acquire write
+         * access on this semaphore before it collects ordered extents and
+         * extent maps.
+         */
+        struct rw_semaphore dio_sem;
+
         struct inode vfs_inode;
 };