RE: [f2fs-dev] [PATCH] f2fs: fix wrong number of max_nid when init

From: Chao Yu
Date: Thu Apr 17 2014 - 04:02:41 EST


Hi,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk.kim@xxxxxxxxxxx]
> Sent: Thursday, April 17, 2014 3:17 PM
> To: Chao Yu
> Cc: linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [f2fs-dev] [PATCH] f2fs: fix wrong number of max_nid when init
>
> Hi,
>
> 2014-04-17 (ë), 14:27 +0800, Chao Yu:
> > Since max_nid value was minus three in previous commit:
> > 'b63da15e8b475245026bdf2096853683f189706b', Our last three nids could not be
> > used ever, but 0/node nid/meta nid is still occupied.
> > And also our ra_meta_pages() could not readahead the last block of NAT.
>
> What is the root problem in there?

The last one is the root problem, I will submit another patch to fix it.

> IIRC, the max_nid should not be turned back since that can cause an
> infinite loop during build_free_nids() under a test using whole the
> nids.

Got it, thanks for your explanation.

Regards.

>
> > Let's fix the wrong calculation of this value, and left the reserved nids there.
> >
> > Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> > ---
> > fs/f2fs/node.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index 84f9b7b..3f0bb50 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -1860,7 +1860,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
> > nat_blocks = nat_segs << le32_to_cpu(sb_raw->log_blocks_per_seg);
> >
> > /* not used nids: 0, node, meta, (and root counted as valid node) */
> > - nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks - 3;
> > + nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks;
> > nm_i->fcnt = 0;
> > nm_i->nat_cnt = 0;
> > nm_i->ram_thresh = DEF_RAM_THRESHOLD;
>
> --
> Jaegeuk Kim
> Samsung

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