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From:   Richard Weinberger <richard.weinberger@gmail.com>
Date:   Wed, 3 Jun 2020 09:03:42 +0200
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Subject: Re: [PATCH v2] jffs2: fix jffs2 mounting failure
To:     Zhe Li <lizhe67@huawei.com>
Cc:     David Woodhouse <dwmw2@infradead.org>,
        linux-mtd@lists.infradead.org, LKML <linux-kernel@vger.kernel.org>
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On Thu, Apr 23, 2020 at 4:58 AM Zhe Li <lizhe67@huawei.com> wrote:
>
> Mounting jffs2 on nand flash will get message "failed: I/O error"
> with the steps listed below.
> 1.erase nand flash
> 2.mount jffs2 on it (this mounting operation will be successful)
> 3.do chown or chmod to the mount point directory
> 4.umount jffs2
> 5.mount jffs2 on nand flash
> After step 5, we will get message "mount ... failed: I/O error".

The important step is missing. You need to unmount before jffs2 is done
with erasing.

>         if (c->nr_erasing_blocks) {
> -               if ( !c->used_size && ((c->nr_free_blocks+empty_blocks+bad_blocks)!= c->nr_blocks || bad_blocks == c->nr_blocks) ) {
> +               if (!c->used_size && ((c->nr_free_blocks+empty_blocks+bad_blocks) != c->nr_blocks || bad_blocks == c->nr_blocks) &&
> +                   !(has_root_inode(c) && !has_other_inode(c))) {

I see the problem but I don't think it is wise to implement such a workaround.
IIUC the real issue is that c->used_size being zero but
c->nr_free_blocks+empty_blocks+bad_blocks does not sum
up correctly in this situation.

-- 
Thanks,
//richard