Btrfs: just free dummy extent buffers

If we fail during our sanity tests we could get NULL deref's because we unload
the module before the dummy extent buffers are free'd via RCU.  So check for
this case and just free the things directly.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
(cherry picked from commit 2fdbf36f587e956eee26e193264b0e8d86d2fd08)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ce266cbf2b72b11b9dbca48840c5e4adae41261c..b0bf0e14bc045d152f194f60ad9743ab1bc47159 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4954,6 +4954,12 @@ static int release_extent_buffer(struct extent_buffer *eb)
 
                /* Should be safe to release our pages at this point */
                btrfs_release_extent_buffer_page(eb);
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+               if (unlikely(test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))) {
+                       __free_extent_buffer(eb);
+                       return 1;
+               }
+#endif
                call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
                return 1;
        }