From f31ea0888caeee75bb8a8514c9f8f28b521b55df Mon Sep 17 00:00:00 2001
From: Qu Wenruo <wqu@suse.com>
Date: Mon, 17 Feb 2020 14:16:54 +0800
Patch-mainline: v5.7-rc1
Git-commit: f31ea0888caeee75bb8a8514c9f8f28b521b55df
References: bsc#1171417
Subject: [PATCH 3/3] btrfs: relocation: Check cancel request after each extent
 found

When relocating data block groups with tons of small extents, or large
metadata block groups, there can be over 200,000 extents.

We will iterate all extents of such block group in relocate_block_group(),
where iteration itself can be kinda time-consuming.

So when user want to cancel the balance, the extent iteration loop can
be another target.

This patch will add the cancelling check in the extent iteration loop of
relocate_block_group() to make balance cancelling faster.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/relocation.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index a4edb821990f..008ba7efc4be 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4232,6 +4232,10 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 				break;
 			}
 		}
+		if (btrfs_should_cancel_balance(fs_info)) {
+			err = -ECANCELED;
+			break;
+		}
 	}
 	if (trans && progress && err == -ENOSPC) {
 		ret = btrfs_force_chunk_alloc(trans, rc->block_group->flags);
-- 
2.26.2