Merge "UBI: avoid program operation on NOR flash after erasure interrupted"

 */

static int nor_erase_prepare(struct ubi_device *ubi, int pnum)

{

	int err, err1;

	int err;

	size_t written;

	loff_t addr;

	uint32_t data = 0;

	struct ubi_ec_hdr ec_hdr;

	/*

	 * Note, we cannot generally define VID header buffers on stack,

	 * because of the way we deal with these buffers (see the header

	struct ubi_vid_hdr vid_hdr;

	/*

	 * If VID or EC is valid, we have to corrupt them before erasing.

	 * It is important to first invalidate the EC header, and then the VID

	 * header. Otherwise a power cut may lead to valid EC header and

	 * invalid VID header, in which case UBI will treat this PEB as

	 * corrupted and will try to preserve it, and print scary warnings.

	 */

	addr = (loff_t)pnum * ubi->peb_size;

	err = ubi_io_read_ec_hdr(ubi, pnum, &ec_hdr, 0);

	if (err != UBI_IO_BAD_HDR_EBADMSG && err != UBI_IO_BAD_HDR &&

	    err != UBI_IO_FF){

		err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);

	if (!err) {

		if(err)

			goto error;

	}

	err = ubi_io_read_vid_hdr(ubi, pnum, &vid_hdr, 0);

	if (err != UBI_IO_BAD_HDR_EBADMSG && err != UBI_IO_BAD_HDR &&

	    err != UBI_IO_FF){

		addr += ubi->vid_hdr_aloffset;

		err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);

		if (!err)

			return 0;

		if (err)

			goto error;

	}

	/*

	 * We failed to write to the media. This was observed with Spansion

	 * S29GL512N NOR flash. Most probably the previously eraseblock erasure

	 * was interrupted at a very inappropriate moment, so it became

	 * unwritable. In this case we probably anyway have garbage in this

	 * PEB.

	 */

	err1 = ubi_io_read_vid_hdr(ubi, pnum, &vid_hdr, 0);

	if (err1 == UBI_IO_BAD_HDR_EBADMSG || err1 == UBI_IO_BAD_HDR ||

	    err1 == UBI_IO_FF) {

		struct ubi_ec_hdr ec_hdr;

		err1 = ubi_io_read_ec_hdr(ubi, pnum, &ec_hdr, 0);

		if (err1 == UBI_IO_BAD_HDR_EBADMSG || err1 == UBI_IO_BAD_HDR ||

		    err1 == UBI_IO_FF)

			/*

			 * Both VID and EC headers are corrupted, so we can

			 * safely erase this PEB and not afraid that it will be

			 * treated as a valid PEB in case of an unclean reboot.

			 */

	return 0;

	}

error:

	/*

	 * The PEB contains a valid VID header, but we cannot invalidate it.

	 * Supposedly the flash media or the driver is screwed up, so return an

	 * error.

	 * The PEB contains a valid VID or EC header, but we cannot invalidate

	 * it. Supposedly the flash media or the driver is screwed up, so

	 * return an error.

	 */

	ubi_err("cannot invalidate PEB %d, write returned %d read returned %d",

		pnum, err, err1);

	ubi_err("cannot invalidate PEB %d, write returned %d", pnum, err);

	ubi_dump_flash(ubi, pnum, 0, ubi->peb_size);

	return -EIO;

}