Re: [PATCH 7/7] ext4: set the type of max_zeroout to unsigned int to avoid overflow

Baokun Li
2024-02-17T07:45:16Z

On 2024/2/14 0:38, Jan Kara wrote:
> On Fri 26-01-24 16:57:16, Baokun Li wrote:
>> The max_zeroout is of type int and the s_extent_max_zeroout_kb is of
>> type uint, and the s_extent_max_zeroout_kb can be freely modified via
>> the sysfs interface. When the block size is 1024, max_zeroout may
>> overflow, so declare it as unsigned int to avoid overflow.
>>
>> Signed-off-by: Baokun Li <libaokun1@huawei.com>
>> ---
>> fs/ext4/extents.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
>> index 01299b55a567..8653b13e8248 100644
>> --- a/fs/ext4/extents.c
>> +++ b/fs/ext4/extents.c
>> @@ -3425,10 +3425,8 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
>> struct ext4_extent zero_ex1, zero_ex2;
>> struct ext4_extent *ex, *abut_ex;
>> ext4_lblk_t ee_block, eof_block;
>> - unsigned int ee_len, depth, map_len = map->m_len;
>> - int allocated = 0, max_zeroout = 0;
>> - int err = 0;
>> - int split_flag = EXT4_EXT_DATA_VALID2;
>> + unsigned int ee_len, depth, map_len = map->m_len, max_zeroout = 0;
>> + int err = 0, allocated = 0, split_flag = EXT4_EXT_DATA_VALID2;
> Honestly, I prefer if we keep unrelated variables on different lines,
> especially when they have initializers. I find the code more readable that
> way. So in this case:
>
> int err = 0;
> int split_flag = EXT4_EXT_DATA_VALID2;
> int allocated = 0;
> unsigned int max_zeroout = 0;
>
> But otherwise the fix looks good!
>
> Honza
Totally agree! I will replace it in the next version.

Thanks!
--
With Best Regards,
Baokun Li
.