| Message ID | 6107ccae94e0af75c60d1d1f6a5a0dd59aaafc58.1677003060.git.johannes.thumshirn@wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: fix percent calculation for reclaim message | expand |
LGTM
Reviewed-by: Anand Jain <anand.jain@oracle.com>
On 2023/2/22 02:11, Johannes Thumshirn wrote: > We have a report, that the info message for block-group reclaim is crossing the > 100% used mark. > > This is happening as we were truncaating the divisor for the division (the > block_group->length) to a 32bit value. > > Fix this by using div64_u64() to not truncate the divisor. Reviewed-by: Qu Wenruo <wqu@suse.com> In the worst case, it can lead to a div by zero error. And I believe it's not that hard to trigger, just 4 disks RAID0, and each device is large enough, then we're doomed: $ 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 Maybe this can be turned into a test case? Thanks, Qu > > 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") > Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> > --- > 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 fe4a60d7a49e..c6b9d5a04f3e 100644 > --- a/fs/btrfs/block-group.c > +++ b/fs/btrfs/block-group.c > @@ -1826,7 +1826,8 @@ 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);
On Tue, Feb 21, 2023 at 10:11:24AM -0800, Johannes Thumshirn wrote: > We have a report, that the info message for block-group reclaim is crossing the > 100% used mark. > > This is happening as we were truncaating the divisor for the division (the > block_group->length) to a 32bit value. > > Fix this by using div64_u64() to not truncate the divisor. > > 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") > Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Added to misc-next with Qu's note how to possibly reproduce it, thanks.
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index fe4a60d7a49e..c6b9d5a04f3e 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1826,7 +1826,8 @@ 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);
We have a report, that the info message for block-group reclaim is crossing the 100% used mark. This is happening as we were truncaating the divisor for the division (the block_group->length) to a 32bit value. Fix this by using div64_u64() to not truncate the divisor. 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") Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> --- fs/btrfs/block-group.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)