From: Josef Bacik <josef@toxicpanda.com>
Date: Tue, 21 Jul 2020 10:22:22 -0400
Subject: btrfs: check tickets after waiting on ordered extents
Git-commit: 448b966b49be55af8f4aa79b24d7896809fd8e67
Patch-mainline: v5.10-rc1
References: bsc#1135481

Right now if the space is freed up after the ordered extents complete
(which is likely since the reservations are held until they complete),
we would do extra delalloc flushing before we'd notice that we didn't
have any more tickets.  Fix this by moving the tickets check after our
wait_ordered_extents check.

Tested-by: Nikolay Borisov <nborisov@suse.com>
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 | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 4b8753b1a628..6a9bc5cc487b 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -545,14 +545,6 @@ static void shrink_delalloc(struct btrfs_fs_info *fs_info,
 	while ((delalloc_bytes || dio_bytes) && loops < 3) {
 		btrfs_start_delalloc_roots(fs_info, items);
 
-		spin_lock(&space_info->lock);
-		if (list_empty(&space_info->tickets) &&
-		    list_empty(&space_info->priority_tickets)) {
-			spin_unlock(&space_info->lock);
-			break;
-		}
-		spin_unlock(&space_info->lock);
-
 		loops++;
 		if (wait_ordered && !trans) {
 			btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
@@ -561,6 +553,15 @@ static void shrink_delalloc(struct btrfs_fs_info *fs_info,
 			if (time_left)
 				break;
 		}
+
+		spin_lock(&space_info->lock);
+		if (list_empty(&space_info->tickets) &&
+		    list_empty(&space_info->priority_tickets)) {
+			spin_unlock(&space_info->lock);
+			break;
+		}
+		spin_unlock(&space_info->lock);
+
 		delalloc_bytes = percpu_counter_sum_positive(
 						&fs_info->delalloc_bytes);
 		dio_bytes = percpu_counter_sum_positive(&fs_info->dio_bytes);