From: Josef Bacik <josef@toxicpanda.com>
Date: Wed, 28 Apr 2021 13:38:42 -0400
Subject: btrfs: check worker before need_preemptive_reclaim
Git-commit: ed738ba7f96170384f3e94a38be5536560eabc00
Patch-mainline: v5.14-rc1
References: bsc#1202528

need_preemptive_reclaim() does some calculations, which aren't heavy,
but if we're already running preemptive reclaim there's no reason to do
them at all, so re-order the checks so that we don't do the calculation
if we're already doing reclaim.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/space-info.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 2dc674b7c3b1..c9a5e003bcfa 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -1588,8 +1588,8 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info,
 		 * the async reclaim as we will panic.
 		 */
 		if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
-		    need_preemptive_reclaim(fs_info, space_info) &&
-		    !work_busy(&fs_info->preempt_reclaim_work)) {
+		    !work_busy(&fs_info->preempt_reclaim_work) &&
+		    need_preemptive_reclaim(fs_info, space_info)) {
 			trace_btrfs_trigger_flush(fs_info, space_info->flags,
 						  orig_bytes, flush, "preempt");
 			queue_work(system_unbound_wq,