1 files changed, 21 insertions, 3 deletions

diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 5665d2149249..f8229ef1b46d 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -128,6 +128,26 @@ again:
 }
 
 /*
+ * take a spinning read lock.
+ * returns 1 if we get the read lock and 0 if we don't
+ * this won't wait for blocking writers
+ */
+int btrfs_tree_read_lock_atomic(struct extent_buffer *eb)
+{
+        if (atomic_read(&eb->blocking_writers))
+                return 0;
+
+        read_lock(&eb->lock);
+        if (atomic_read(&eb->blocking_writers)) {
+                read_unlock(&eb->lock);
+                return 0;
+        }
+        atomic_inc(&eb->read_locks);
+        atomic_inc(&eb->spinning_readers);
+        return 1;
+}
+
+/*
  * returns 1 if we get the read lock and 0 if we don't
  * this won't wait for blocking writers
  */
@@ -158,9 +178,7 @@ int btrfs_try_tree_write_lock(struct extent_buffer *eb)
             atomic_read(&eb->blocking_readers))
                 return 0;
 
-        if (!write_trylock(&eb->lock))
-                return 0;
-
+        write_lock(&eb->lock);
         if (atomic_read(&eb->blocking_writers) ||
             atomic_read(&eb->blocking_readers)) {
                 write_unlock(&eb->lock);