On Thu, May 15, 2008 at 12:17:11AM +0530, Aneesh Kumar K.V wrote:
> @@ -3134,8 +3135,7 @@ static void ext4_mb_use_inode_pa(struct ext4_allocation_context *ac,
> static void ext4_mb_use_group_pa(struct ext4_allocation_context *ac,
> struct ext4_prealloc_space *pa)
> {
> - unsigned len = ac->ac_o_ex.fe_len;
> -
> + unsigned int len = ac->ac_o_ex.fe_len;
> ext4_get_group_no_and_offset(ac->ac_sb, pa->pa_pstart,
> &ac->ac_b_ex.fe_group,
> &ac->ac_b_ex.fe_start);
> --
This change had nothing to do with fixing the use of unitialized data,
but when I started looking more closely, it raised a potential signed
vs. unsigned issue: ac_o_ex is a struct ext4_free_extent, and fe_len
is an int.
So here we are assigning an int to an unsigned int. Later, len is
assigned to ac_b_ex.len, which means assigning an unsigned int to an
int. In other places, fe_len (an int) is compared against pa_free
(which is an unsigned short), and fe_len gets assined to pa_free, once
again mixing signed and unsigned.
Can someone who is really familiar with this code check this out? I
think the following pseudo-patch to mballoc.h might be in order:
struct ext4_free_extent {
ext4_lblk_t fe_logical;
ext4_grpblk_t fe_start;
ext4_group_t fe_group;
- int fe_len;
+ unsigned int fe_len;
};
- Ted
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