On Fri, 26 Mar 2010 21:44:33 +0800, jing zhang <zj.barak@xxxxxxxxx> wrote:
> 2010/3/26, Aneesh Kumar K. V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>:
> > On Thu, 25 Mar 2010 22:54:21 +0800, jing zhang <zj.barak@xxxxxxxxx> wrote:
> >> From: Jing Zhang <zj.barak@xxxxxxxxx>
> >>
> >> Date: Wed Mar 25 22:55:04 2010
> >>
> >> Checking bug seems not at right place, and the function itself should
> >> be inlined.
> >>
> >> Cc: Theodore Ts'o <tytso@xxxxxxx>
> >> Cc: Andreas Dilger <adilger@xxxxxxx>
> >> Cc: Dave Kleikamp <shaggy@xxxxxxxxxxxxxxxxxx>
> >> Cc: "Aneesh Kumar K. V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> >> Signed-off-by: Jing Zhang <zj.barak@xxxxxxxxx>
> >>
> >> ---
> >>
> >> --- linux-2.6.32/fs/ext4/mballoc.c 2009-12-03 11:51:22.000000000 +0800
> >> +++ ext4_mm_leak/mballoc-10.c 2010-03-25 22:44:00.000000000 +0800
> >> @@ -2786,9 +2786,7 @@ out_err:
> >> static void ext4_mb_normalize_group_request(struct
> >> ext4_allocation_context *ac)
> >> {
> >> struct super_block *sb = ac->ac_sb;
> >> - struct ext4_locality_group *lg = ac->ac_lg;
> >>
> >> - BUG_ON(lg == NULL);
> >> if (EXT4_SB(sb)->s_stripe)
> >> ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_stripe;
> >> else
> >
> > That BUG_ON is to ensure that the allocation context is actually having
> > a locality group which is needed for group allocation request.
> >
> > -aneesh
> >
>
> Please check
> 1, the 3 lines at the end of ext4_mb_group_or_file()
> 2, the function name of this patch
>
What i wanted to mention was the BUG_ON is there to ensure that we don't
call ext4_mb_normalize_group_request on non group enabled allocation
context by programming mistake. Doing that would cause ac_g_ex.fe_len
to change. So that BUG_ON is there to capture a programming error.
-aneesh
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