1 files changed, 16 insertions, 0 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 3b9fb478b0d1..907ed0025dd4 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4184,6 +4184,7 @@ static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
 
 static void check_buffer_tree_ref(struct extent_buffer *eb)
 {
+        int refs;
         /* the ref bit is tricky.  We have to make sure it is set
          * if we have the buffer dirty.   Otherwise the
          * code to free a buffer can end up dropping a dirty
@@ -4204,6 +4205,10 @@ static void check_buffer_tree_ref(struct extent_buffer *eb)
          * So bump the ref count first, then set the bit.  If someone
          * beat us to it, drop the ref we added.
          */
+        refs = atomic_read(&eb->refs);
+        if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
+                return;
+
         spin_lock(&eb->refs_lock);
         if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
                 atomic_inc(&eb->refs);
@@ -4405,9 +4410,20 @@ static int release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
 
 void free_extent_buffer(struct extent_buffer *eb)
 {
+        int refs;
+        int old;
         if (!eb)
                 return;
 
+        while (1) {
+                refs = atomic_read(&eb->refs);
+                if (refs <= 3)
+                        break;
+                old = atomic_cmpxchg(&eb->refs, refs, refs - 1);
+                if (old == refs)
+                        return;
+        }
+
         spin_lock(&eb->refs_lock);
         if (atomic_read(&eb->refs) == 2 &&
             test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))