Btrfs: fix wrong block group in trace during the free space allocation

We allocate the free space from the former block group, not the current
one, so should use the former one to output the trace information.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index b55a4fd13ecc..73b55d94b953 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6323,7 +6323,8 @@ have_block_group:
                                 /* we have a block, we're done */
                                 spin_unlock(&last_ptr->refill_lock);
                                 trace_btrfs_reserve_extent_cluster(root,
-                                        block_group, search_start, num_bytes);
+                                                used_block_group,
+                                                search_start, num_bytes);
                                 if (used_block_group != block_group) {
                                         btrfs_put_block_group(block_group);
                                         block_group = used_block_group;