[BUG]
When running fsstress with only falloc workload, and a very low qgroup
limit set, we can get qgroup data rsv leak at unmount time.
BTRFS warning (device dm-0): qgroup 0/5 has unreleased space, type 0 rsv 20480
BTRFS error (device dm-0): qgroup reserved space leaked
The minimal reproducer looks like:
#!/bin/bash
dev=/dev/test/test
mnt="/mnt/btrfs"
fsstress=~/xfstests-dev/ltp/fsstress
runtime=8
workload()
{
umount $dev &> /dev/null
umount $mnt &> /dev/null
mkfs.btrfs -f $dev > /dev/null
mount $dev $mnt
btrfs quota en $mnt
btrfs quota rescan -w $mnt
btrfs qgroup limit 16m 0/5 $mnt
$fsstress -w -z -f creat=10 -f fallocate=10 -p 2 -n 100 \
-d $mnt -v > /tmp/fsstress
umount $mnt
if dmesg | grep leak ; then
echo "!!! FAILED !!!"
exit 1
fi
}
for (( i=0; i < $runtime; i++)); do
echo "=== $i/$runtime==="
workload
done
Normally it would fail before round 4.
[CAUSE]
In function insert_prealloc_file_extent(), we first call
btrfs_qgroup_release_data() to know how many bytes are reserved for
qgroup data rsv.
Then use that @qgroup_released number to continue our work.
But after we call btrfs_qgroup_release_data(), we should either queue
@qgroup_released to delayed ref or free them manually in error path.
Unfortunately, we lack the error handling to free the released bytes,
leaking qgroup data rsv.
All the error handling function outside won't help at all, as we have
released the range, meaning in inode io tree, the EXTENT_QGROUP_RESERVED
bit is already cleared, thus all btrfs_qgroup_free_data() call won't
free any data rsv.
[FIX]
Add free_qgroup tag to manually free the released qgroup data rsv.
Reported-by: Nikolay Borisov <nborisov@suse.com>
Reported-by: David Sterba <dsterba@suse.cz>
Fixes: 9729f10a60 ("btrfs: inode: move qgroup reserved space release to the callers of insert_reserved_file_extent()")
CC: stable@vger.kernel.org # 5.10+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
a3ee79bd8f