UBI: handle bit-flips when no header found
Currently UBI has one small flaw - when we read EC or VID header, but find only
0xFF bytes, we return UBI_IO_FF and do not report whether we had bit-flips or
not. In case of the VID header, the scanning code adds this PEB to the free list,
even though there were bit-flips.
Imagine the following situation: we start writing VID header to a PEB and have a
power cut, so the PEB becomes unstable. When we scan and read the PEB, we get
a bit-flip. Currently, UBI would just ignore this and treat the PEB as free. This
patch changes UBI behavior and now UBI will schedule this PEB for erasure.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 774bdca..1099077 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -86,17 +86,25 @@
* Error codes returned by the I/O sub-system.
*
* UBI_IO_FF: the read region of flash contains only 0xFFs
+ * UBI_IO_FF_BITFLIPS: the same as %UBI_IO_FF, but also also there was a data
+ * integrity error reported by the MTD driver
+ * (uncorrectable ECC error in case of NAND)
* UBI_IO_BAD_HDR: the EC or VID header is corrupted (bad magic or CRC)
* UBI_IO_BAD_HDR_EBADMSG: the same as %UBI_IO_BAD_HDR, but also there was a
* data integrity error reported by the MTD driver
* (uncorrectable ECC error in case of NAND)
* UBI_IO_BITFLIPS: bit-flips were detected and corrected
+ *
+ * Note, it is probably better to have bit-flip and ebadmsg as flags which can
+ * be or'ed with other error code. But this is a big change because there are
+ * may callers, so it does not worth the risk of introducing a bug
*/
enum {
UBI_IO_FF = 1,
+ UBI_IO_FF_BITFLIPS,
UBI_IO_BAD_HDR,
UBI_IO_BAD_HDR_EBADMSG,
- UBI_IO_BITFLIPS
+ UBI_IO_BITFLIPS,
};
/*