linux-kernel - Re: [RFC][PATCH 7/7] MTD: UBI: wire up checkpointing

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Message-ID: <4F41026C.6060203@linutronix.de>
Date:	Sun, 19 Feb 2012 15:08:44 +0100
From:	Richard Weinberger <rw@...utronix.de>
To:	Shmulik Ladkani <shmulik.ladkani@...il.com>
CC:	linux-mtd@...ts.infradead.org, tglx@...utronix.de,
	dedekind1@...il.com, linux-kernel@...r.kernel.org,
	tim.bird@...sony.com
Subject: Re: [RFC][PATCH 7/7] MTD: UBI: wire up checkpointing

Am 19.02.2012 14:57, schrieb Shmulik Ladkani:
> On Tue, 14 Feb 2012 21:06:46 +0100 Richard Weinberger<rw@...utronix.de>  wrote:
>> +#ifdef CONFIG_MTD_UBI_CHECKPOINT
>> +static int attach_by_checkpointing(struct ubi_device *ubi)
>> +{
>> +	int cp_start, err;
>> +	struct ubi_scan_info *si;
>> +
>> +	cp_start = ubi_find_checkpoint(ubi);
>> +	if (cp_start<  0)
>> +		return -ENOENT;
>> +
>> +	si = ubi_read_checkpoint(ubi, cp_start);
>> +	if (IS_ERR(si))
>> +		return PTR_ERR(si);
>> +
>> +	ubi->bad_peb_count = 0;
>> +	ubi->good_peb_count = ubi->peb_count;
>
> Zero reported bad PEBs when checkpointing.
> Seems that checkpointing does not remember number/location of bad PEBs.

Currently checkpointing cares only about used and free PEBs.
Bad PEBs are no longer visible to UBI after recovering from a checkpoint.

> Are we fine with that?

This patch is a RFC. :-)

>> +#ifdef CONFIG_MTD_UBI_CHECKPOINT
>> +	err = attach_by_checkpointing(ubi);
>> +
>> +	if (err) {
>> +		if (err != -ENOENT)
>> +			ubi_msg("falling back to attach by scanning mode!\n");
>> +
>> +		err = attach_by_scanning(ubi);
>> +	}
>
> Code does not fit error message.
> Message states "falling back to scanning" only if "err != -ENOENT".
> However code calls 'attach_by_scanning' regardless 'err'.
> Was it your intention?

Yes.
If recovering from a checkpoint fails the corresponding code prints
a human readable error message in any case.

Thanks,
//richard
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