Re: [PATCH] Fix oops in mballoc caused by a variable overflow

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

On Thu, Jan 17, 2008 at 10:43:40AM +0100, Valerie Clement wrote:
> Aneesh Kumar K.V wrote:
>> What about this  ? I guess we will overflow start = start << bsbits;
>>
>
> Hi Aneesh,
> your patch below doesn't fix the issue, because as start_off is also  
> loff_t, start_off = ac->ac_o_ex.fe_logical << bsbits  also overflows.
>

loff_t is 64 bits.

typedef __kernel_loff_t         loff_t;
typedef long long       __kernel_loff_t;
typedef __u32 ext4_lblk_t;
typedef unsigned long long ext4_fsblk_t

start_off = ac->ac_o_ex.fe_logical << bsbits;

In the above line what we are storing in start_off is the offset in bytes.So it makes
sense to use the type loff_t. It is neither logical block nor physical block.


-aneesh