On Fri, 21 Sep 2012 17:24:44 +0200, David Sterba wrote:
> On Fri, Sep 21, 2012 at 05:07:46PM +0800, Miao Xie wrote:
>> --- a/fs/btrfs/ioctl.c
>> +++ b/fs/btrfs/ioctl.c
>> @@ -3335,6 +3335,24 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
>>
>> goto do_balance;
>> }
>> +
>> + if ((bargs->data.flags & BTRFS_BALANCE_ARGS_USAGE) &&
>> + (bargs->data.usage < 0 || bargs->data.usage > 100)) {
>
> the 0 checks belong here
>
>> + ret = -EINVAL;
>> + goto out_bargs;
>> + }
>> +
>> + if ((bargs->meta.flags & BTRFS_BALANCE_ARGS_USAGE) &&
>> + (bargs->meta.usage < 0 || bargs->meta.usage > 100)) {
>> + ret = -EINVAL;
>> + goto out_bargs;
>> + }
>> +
>> + if ((bargs->sys.flags & BTRFS_BALANCE_ARGS_USAGE) &&
>> + (bargs->sys.usage < 0 || bargs->sys.usage > 100)) {
>> + ret = -EINVAL;
>> + goto out_bargs;
>> + }
>> } else {
>> bargs = NULL;
>> }
>> @@ -2347,7 +2335,8 @@ static int chunk_usage_filter(struct btrfs_fs_info *fs_info, u64 chunk_offset,
>> cache = btrfs_lookup_block_group(fs_info, chunk_offset);
>> chunk_used = btrfs_block_group_used(&cache->item);
>>
>> - user_thresh = div_factor_fine(cache->key.offset, bargs->usage);
>> + BUG_ON(bargs->usage < 0 || bargs->usage > 100);
>
> otherwise it reliably crashes here
Sorry, I don't know why it will crash here if we input 0. I tried to input 0,
and it worked well.
I think the only case we must take into account is the users might input the wrong value (>100 or <0)
on the old kernel, and it can be stored into the filesystem. If we mount this filesystem
on the new kernel, some problems may happen.
Thanks
Miao
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