Re: [Yaffs] Checkpointing in YAFFS2

Hi Phil

Thanx for that.

I feel a bit guilty that I did not respond to your earlier posting on this.

At present the reserved space is a hardwired value, but I think it would be
better to use a calculated value.
That is, by looking at the number of files, blocks etc, yaffs should be able
to calculate its needs.

I do however think that an option to turn on/off checkpointing on a
per-partition basis would be a GoodThing.

Also, the ability to mount ignoring current checkpt data (?? safe mount??)

Also the ability to turn off checkpointing in Kconfig.

Thus, I propose:

CONFIG_YAFFS_ENABLE_CHECKPOINT default 'y'

Adding mount flags:
"no-checkpoint-restore" do not read checkpoint on mount
"no-checkpoint-save" do not write checkpoints on flush/umount.

In the interum I am applying your patch because I think it useful.

-- Charles


On Tuesday 19 December 2006 05:33, Phil Sutter wrote:
> Hi!
>
> FreeWRT is working on support for Mikrotik's RouterBoard532, which
> has a large page NAND flash chip. To improve bootup time, Mikrotik
> developers decided to partition the flash into two parts, the first one
> just holding the kernel, and therefore only being 4MB of size.
> Unfortunately, this makes problems with checkpointing, as the default of
> 10 Blocks already covers half of the free space in the filesystem.
>
> To solve this in a clean way, I exported the reserved blocks count into
> the kernel configuration. But see yourself, patch is appended.
>
> I would be very happy if this patch makes it into upstream. I could also
> imagine having another option to totally disable checkpoints. If there
> is anything I can do to satisfy your expectations on the configuration
> possibilities for checkpointing, just tell me and I will send you an
> adjusted version of the patch.
>
> Thanks in advance, Phil