Re: [Yaffs] Disadvantage of using yaffs checkpointing?

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Author: peterlingoal
Date:  
To: Charles Manning
CC: yaffs
Subject: Re: [Yaffs] Disadvantage of using yaffs checkpointing?
Thanks Charles, the patch works.

On Tue, May 22, 2012 at 7:25 AM, Charles Manning <>wrote:

> On Tuesday 22 May 2012 10:12:35 Charles Manning wrote:
> > On Tuesday 22 May 2012 00:31:25 peterlingoal wrote:
> > > Hi Charles:
> > >
> > > following is a proposed patch that check for block state after
> > > discovering a check point block, and continues search if the block
> state
> > > is DEAD: From b08b8c5fc21c2820f66454968be3a5115477fc96 Mon Sep 17
> > > 00:00:00 2001 From: Peter Lin <>
> > > Date: Mon, 21 May 2012 20:25:55 +0800
> > > Subject: [PATCH] yaffs: ignore checkpt if it is in bad block
> > >
> > > ---
> > > yaffs_checkptrw.c | 11 +++++++++++
> > > 1 files changed, 11 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/yaffs_checkptrw.c b/yaffs_checkptrw.c
> > > index 997a618..0d63e74 100644
> > > --- a/yaffs_checkptrw.c
> > > +++ b/yaffs_checkptrw.c
> > > @@ -13,6 +13,8 @@
> > >
> > > #include "yaffs_checkptrw.h"
> > > #include "yaffs_getblockinfo.h"
> > > +#include "yaffs_nand.h"
> > > +#include "yaffs_guts.h"
> > >
> > > static int yaffs2_checkpt_space_ok(struct yaffs_dev *dev)
> > > {
> > > @@ -117,6 +119,15 @@ static void yaffs2_checkpt_find_block(struct
> > > yaffs_dev *dev)
> > > tags.ecc_result);
> > >
> > > if (tags.seq_number == YAFFS_SEQUENCE_CHECKPOINT_DATA) {
> > > + enum yaffs_block_state state = 0;
> > > + u32 seq_number = 0;
> > > + yaffs_query_init_block_state(dev, i, &state, &seq_number);
> > > + if( YAFFS_BLOCK_STATE_DEAD == state )
> > > + {
> > > + yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> > > + "ignore bad checkpt block %d", i);
> > > + continue;
> > > + }
> >
> > This approach won't always work
> > yaffs_querey_init_block_state() applies a block offset which is not set
> up
> > properly yet. Instead you need to use the raw functions during checkpoint
> > reading:
> >
> > +                       dev->param.query_block_fn(dev, i, &state, &seq);
> > +                       if (state == YAFFS_BLOCK_STATE_DEAD)
> > +                               continue;

> >
> > > /* Right kind of block */
> > > dev->checkpt_next_block = tags.obj_id;
> > > dev->checkpt_cur_block = i;
> >
> > I have a fix for this that should be pushed to yaffs2 git today.
>
> Pushed.
>
>
> http://yaffs.net/gitweb?p=yaffs2.git;a=commitdiff;h=d9cae0a277c62c660e4802d3b8745500583273da
>
> >
> > I am also adding a further check to the checkpointing.
> >
> > Currently the checkpoint data has various checks in it, but none that
> > checks for dropped or stale data during the reading. Each checkpoint
> record
> > is framed and there is a checksum at the end which do provide a level of
> > checking.
> >
> > I have written some code, now under test, which does further checks on a
> > chunk-by-chunk basis. This should be checked in today.
> >
>
> This has also been pushed.
>
>
> -- CHarles
>
>
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