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

Jan Kara
2024-02-13T16:38:10Z

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
--
Jan Kara <jack@suse.com>
SUSE Labs, CR