UBI errors when "ls -l"

[Yan Kong]

Hi, Richard,

Your question,
Is this a vanilla kernel or does it carry tons of vendor patches?
--- I use the Kernel based on Yocto 1.6, but includes lots Qualcomm patches.

> ubiattach /dev/ubi_ctrl -m 3 -O 4096

Why do you need -O?
--- I also tried without -O. But the result is the same.

Please use ubi tools to flash the image.
(dd should work, but just in case...)
--- I ever tried " ubiformat /dev/mtd7 -f ubi.img -s 4096", the same error :(.

What is line 213 in your drivers/mts/ubi/io.c?
--- I marked line 213 as follow, thank you.

int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
		int len)
{
	int err, retries = 0;
	size_t read;
	loff_t addr;

	dbg_io("read %d bytes from PEB %d:%d", len, pnum, offset);

	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
	ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
	ubi_assert(len > 0);

	err = paranoid_check_not_bad(ubi, pnum);
	if (err)
		return err;

	/*
	 * Deliberately corrupt the buffer to improve robustness. Indeed, if we
	 * do not do this, the following may happen:
	 * 1. The buffer contains data from previous operation, e.g., read from
	 *    another PEB previously. The data looks like expected, e.g., if we
	 *    just do not read anything and return - the caller would not
	 *    notice this. E.g., if we are reading a VID header, the buffer may
	 *    contain a valid VID header from another PEB.
	 * 2. The driver is buggy and returns us success or -EBADMSG or
	 *    -EUCLEAN, but it does not actually put any data to the buffer.
	 *
	 * This may confuse UBI or upper layers - they may think the buffer
	 * contains valid data while in fact it is just old data. This is
	 * especially possible because UBI (and UBIFS) relies on CRC, and
	 * treats data as correct even in case of ECC errors if the CRC is
	 * correct.
	 *
	 * Try to prevent this situation by changing the first byte of the
	 * buffer.
	 */
	*((uint8_t *)buf) ^= 0xFF;

	addr = (loff_t)pnum * ubi->peb_size + offset;
retry:
	err = mtd_read(ubi->mtd, addr, len, &read, buf);
	if (err) {
		const char *errstr = mtd_is_eccerr(err) ? " (ECC error)" : "";

		if (mtd_is_bitflip(err)) {
			/*
			 * -EUCLEAN is reported if there was a bit-flip which
			 * was corrected, so this is harmless.
			 *
			 * We do not report about it here unless debugging is
			 * enabled. A corresponding message will be printed
			 * later, when it is has been scrubbed.
			 */
			dbg_msg("fixable bit-flip detected at PEB %d", pnum);
			ubi_assert(len == read);
			return UBI_IO_BITFLIPS;
		}

		if (retries++ < UBI_IO_RETRIES) {
			dbg_io("error %d%s while reading %d bytes from PEB "
			       "%d:%d, read only %zd bytes, retry",
			       err, errstr, len, pnum, offset, read);
			yield();
			goto retry;
		}

		ubi_err("error %d%s while reading %d bytes from PEB %d:%d, "
			"read %zd bytes", err, errstr, len, pnum, offset, read);
		ubi_dbg_dump_stack();

		/*
		 * The driver should never return -EBADMSG if it failed to read
		 * all the requested data. But some buggy drivers might do
		 * this, so we change it to -EIO.
		 */
		if (read != len && mtd_is_eccerr(err)) {
			ubi_assert(0);
			err = -EIO;
		}
	} else {
		ubi_assert(len == read);      <--------------------------------- line 213

		if (ubi_dbg_is_bitflip(ubi)) {
			dbg_gen("bit-flip (emulated)");
			err = UBI_IO_BITFLIPS;
		}
	}

	return err;
}
-----Original Message-----
From: Richard Weinberger [mailto:richard.weinberger at gmail.com] 
Sent: 2014年12月10日 18:40
To: Yan Kong
Cc: linux-mtd at lists.infradead.org
Subject: Re: UBI errors when "ls -l"

On Wed, Dec 10, 2014 at 10:34 AM, Yan <ykong at sierrawireless.com> wrote:
> My Kernel version is:
> Linux swi-mdm9x15 3.4.91-yocto-standard #7 PREEMPT Wed Dec 10 17:39:02 
> HKT 2014 armv7l GNU/Linux

Is this a vanilla kernel or does it carry tons of vendor patches?

> I am trying to mount ubifs. It seems mount ubifs image successfully, 
> but when access ubifs, it will print out lots of error msgs.
> This is steps I do:
> (1)make ubifs.image. I make ubifs image from *.conf (I tried use "mkfs.ubifs"
> and "ubinize" to make image directly, the same error msgs ).
> IMAGE_FSTYPES += "ubi"
> MKUBIFS_ARGS = "-m 4096 -e 253952 -c 2047"
> UBINIZE_ARGS = "-m 4096 -p 256KiB -s 4096"
>
> (2)mount ubifs In Linux shell.
> mkdir -p /mnt/ubifs
> flash_erase /dev/mtd3 0 0 -N
> dd if=/mnt/flash/ubi.img of=/dev/mtd3 bs=4096

Please use ubi tools to flash the image.
(dd should work, but just in case...)

> ubiattach /dev/ubi_ctrl -m 3 -O 4096

Why do you need -O?
Looks fishy.

> ubiblkvol -a /dev/ubi0_0
> mount -t ubifs ubi0:swi-mdm9x15-rootfs /mnt/ubifs
>
> (3)After step (2), ubifs can be mounted successfully. But when I 
> access ubifs, such as when I input "ls", it will show lots of error 
> msgs. But after printing out error msgs, finally it will show directory.
> By the way, I tried to use nandsim to debug the ubi image in Ubuntu, it is OK.
> I think there is something wrong in Kernel configuration.
> Could you please help me? Thank you very much!
> Error msgs and Kernel configuration attached.
>
> error msgs:
> [ 1126.270349] UBI assert failed in ubi_io_read at 213 (pid 427)

What is line 213 in your drivers/mts/ubi/io.c?

--
Thanks,
//richard