From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Date: Tue, 21 Feb 2023 10:11:24 -0800
Subject: [PATCH] btrfs: fix percent calculation for bg reclaim message
References: bsc#1012628
Patch-mainline: 6.2.7
Git-commit: 95cd356ca23c3807b5f3503687161e216b1c520d
commit 95cd356ca23c3807b5f3503687161e216b1c520d upstream.
We have a report, that the info message for block-group reclaim is
crossing the 100% used mark.
This is happening as we were truncating the divisor for the division
(the block_group->length) to a 32bit value.
Fix this by using div64_u64() to not truncate the divisor.
In the worst case, it can lead to a div by zero error and should be
possible to trigger on 4 disks RAID0, and each device is large enough:
$ mkfs.btrfs -f /dev/test/scratch[1234] -m raid1 -d raid0
btrfs-progs v6.1
[...]
Filesystem size: 40.00GiB
Block group profiles:
Data: RAID0 4.00GiB <<<
Metadata: RAID1 256.00MiB
System: RAID1 8.00MiB
Reported-by: Forza <forza@tnonline.net>
Link: https://lore.kernel.org/linux-btrfs/e99483.c11a58d.1863591ca52@tnonline.net/
Fixes: 5f93e776c673 ("btrfs: zoned: print unusable percentage when reclaiming block groups")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add Qu's note ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
fs/btrfs/block-group.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 708d843d..5d694433 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1687,7 +1687,8 @@ void btrfs_reclaim_bgs_work(struct work_struct *work)
btrfs_info(fs_info,
"reclaiming chunk %llu with %llu%% used %llu%% unusable",
- bg->start, div_u64(bg->used * 100, bg->length),
+ bg->start,
+ div64_u64(bg->used * 100, bg->length),
div64_u64(zone_unusable * 100, bg->length));
trace_btrfs_reclaim_block_group(bg);
ret = btrfs_relocate_chunk(fs_info, bg->start);
--
2.35.3