RE: [f2fs-dev] [PATCH] f2fs: avoid to use a NULL point indestroy_segment_manager

From: Chao Yu
Date: Wed Nov 06 2013 - 00:12:18 EST


Hi Gu,

> -----Original Message-----
> From: Gu Zheng [mailto:guz.fnst@xxxxxxxxxxxxxx]
> Sent: Wednesday, November 06, 2013 11:41 AM
> To: Chao Yu
> Cc: ???; linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx; 谭姝
> Subject: Re: [f2fs-dev] [PATCH] f2fs: avoid to use a NULL point in destroy_segment_manager
>
> On 11/06/2013 09:12 AM, Chao Yu wrote:
>
> > A NULL point should avoid to be used in destroy_segment_manager after allocating memory fail for f2fs_sm_info.
>
> Though without this patch it still can work well, because if it failed
> to allocate f2fs_sm_info, the sit_info, free_info... all were NULL, and
> the destory path(e.g. destroy_dirty_segmap) can deal with them well.

I think it could not work well. Without this patch we may got a segment
fault in DIRTY_I(sbi) at the following code if it failed to allocate
f2fs_sm_info memory(sbi->sm_info). Right?

static void destroy_dirty_segmap(struct f2fs_sb_info *sbi)
{
struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);

> IMO, this patch is still a good catch.
>
> Regards,
> Gu
>
> >
> > Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> > ---
> > fs/f2fs/segment.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 3d4d5fc..ff363e6
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -1744,6 +1744,8 @@ static void destroy_sit_info(struct f2fs_sb_info *sbi)
> > void destroy_segment_manager(struct f2fs_sb_info *sbi)
> > {
> > struct f2fs_sm_info *sm_info = SM_I(sbi);
> > + if (!sm_info)
> > + return;
> > destroy_dirty_segmap(sbi);
> > destroy_curseg(sbi);
> > destroy_free_segmap(sbi);


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