linux-kernel - Re: [PATCH v1 2/2] jffs2: make cleanmarker support option

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Message-ID: <b6b5b413-0fbe-4ce2-9d44-451b16555eb3@salutedevices.com>
Date:   Tue, 24 Oct 2023 16:29:57 +0300
From:   Martin Kurbanov <mmkurbanov@...utedevices.com>
To:     Richard Weinberger <richard@....at>
CC:     David Woodhouse <dwmw2@...radead.org>,
        Christian Brauner <brauner@...nel.org>,
        Dave Chinner <dchinner@...hat.com>,
        Yu Zhe <yuzhe@...china.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-mtd <linux-mtd@...ts.infradead.org>,
        kernel <kernel@...rdevices.ru>
Subject: Re: [PATCH v1 2/2] jffs2: make cleanmarker support option



On 23.10.2023 20:44, Richard Weinberger wrote:
> ----- Ursprüngliche Mail -----
>> Von: "Martin Kurbanov" <mmkurbanov@...utedevices.com>
>> If you disable the cleanmarker, the found clean block (filled with 0xff)
>> will be erased again (see fs/jffs2/scan.c#L162).
>> In my opinion, it is better to perform the block erasure again than to
>> not work with such a nand flash at all.
> 
> Doesn't this case many re-erases at each mount time?

You are right. David proposed the good solution.

> BTW: I tried your patch in nandsim, jffs2 was unhappy.
> [   56.147361] jffs2: notice: (440) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref (0 dead, 0 orphan) found.
> [   56.200438] nand: nand_do_write_ops: attempt to write non page aligned data
> [   56.201090] jffs2: Write clean marker to block at 0x001f8000 failed: -22
> 
> Do you have an idea?

According to this code from the function jffs2_mark_erased_block():

```
if (jffs2_cleanmarker_oob(c) || c->cleanmarker_size == 0) {

    if (jffs2_cleanmarker_oob(c)) {
        if (jffs2_write_nand_cleanmarker(c, jeb))
            goto filebad;
    }
} else {

    struct kvec vecs[1];
    struct jffs2_unknown_node marker = {
        .magic = cpu_to_je16(JFFS2_MAGIC_BITMASK),
        .nodetype = cpu_to_je16(JFFS2_NODETYPE_CLEANMARKER),
        .totlen = cpu_to_je32(c->cleanmarker_size)
    };
```

the "if" branch should be executed because "cleanmarker_size" is set to
0 for NAND flash:

```
int jffs2_nand_flash_setup(struct jffs2_sb_info *c)
{
    if (!c->mtd->oobsize)
        return 0;

    /* Cleanmarker is out-of-band, so inline size zero */
    c->cleanmarker_size = 0;
```

In your case, the "else" branch was executed. I assume that "oobsize" is
equal to 0. In this scenario, JFFS2 will not mount without
applying my patch.

-- 
Best Regards,
Martin Kurbanov