On Mon 18-12-23 22:18:14, Baokun Li wrote:
When bb_free is not 0 but bb_fragments is 0, return directly to avoid system crash due to division by zero.
How could this possibly happen? bb_fragments is the number of free space extents and bb_free is the number of free blocks. No free space extents => no free blocks seems pretty obvious? You can see the logic in ext4_mb_generate_buddy()...
Honza
Fixes: 83e80a6e3543 ("ext4: use buckets for cr 1 block scan instead of rbtree") CC: stable@vger.kernel.org Signed-off-by: Baokun Li libaokun1@huawei.com
fs/ext4/mballoc.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 2fbee0f0f5c3..e2a167240335 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -845,6 +845,9 @@ mb_update_avg_fragment_size(struct super_block *sb, struct ext4_group_info *grp) if (!test_opt2(sb, MB_OPTIMIZE_SCAN) || grp->bb_free == 0) return;
- if (unlikely(grp->bb_fragments == 0))
return;- new_order = mb_avg_fragment_size_order(sb, grp->bb_free / grp->bb_fragments); if (new_order == grp->bb_avg_fragment_size_order)
-- 2.31.1