From: Josef Bacik <josef@toxicpanda.com>
Date: Tue, 22 Jun 2021 15:51:59 +0300
Subject: btrfs: remove FLUSH_DELAYED_REFS from data ENOSPC flushing
Git-commit: 048085539243bfd43839fe3dc6cbc02b0c620fdc
Patch-mainline: v5.14-rc1
References: bsc#1202528

Since we unconditionally commit the transaction now we no longer need to
run the delayed refs to make sure our total_bytes_pinned value is
uptodate, we can simply commit the transaction.  Remove this stage from
the data flushing list.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/space-info.c |   16 ----------------
 1 file changed, 16 deletions(-)

--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -962,21 +962,6 @@ static void btrfs_preempt_reclaim_metada
  *   immediately re-usable, it comes in the form of a delayed ref, which must be
  *   run and then the transaction must be committed.
  *
- * FLUSH_DELAYED_REFS
- *   The above two cases generate delayed refs that will affect
- *   ->total_bytes_pinned.  However this counter can be inconsistent with
- *   reality if there are outstanding delayed refs.  This is because we adjust
- *   the counter based solely on the current set of delayed refs and disregard
- *   any on-disk state which might include more refs.  So for example, if we
- *   have an extent with 2 references, but we only drop 1, we'll see that there
- *   is a negative delayed ref count for the extent and assume that the space
- *   will be freed, and thus increase ->total_bytes_pinned.
- *
- *   Running the delayed refs gives us the actual real view of what will be
- *   freed at the transaction commit time.  This stage will not actually free
- *   space for us, it just makes sure that may_commit_transaction() has all of
- *   the information it needs to make the right decision.
- *
  * COMMIT_TRANS
  *     This will commit the transaction.  Historically we had a lot of logic
  *     surrounding whether or not we'd commit the transaction, but this waits born
@@ -994,7 +979,6 @@ static void btrfs_preempt_reclaim_metada
 static const enum btrfs_flush_state data_flush_states[] = {
 	FLUSH_DELALLOC_WAIT,
 	RUN_DELAYED_IPUTS,
-	FLUSH_DELAYED_REFS,
 	COMMIT_TRANS,
 	ALLOC_CHUNK_FORCE,
 };