From: Johannes Thumshirn johannes.thumshirn@wdc.com
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 --- fs/btrfs/block-group.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1687,7 +1687,8 @@ void btrfs_reclaim_bgs_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);