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UBI: handle bit-flips when no header found

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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>
This commit is contained in:
Artem Bityutskiy
2010-09-03 14:22:17 +03:00
parent 74d82d2660
commit 92e1a7d9e7
4 changed files with 51 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

54
drivers/mtd/ubi/io.c
View File

@@ -720,16 +720,16 @@ bad:
int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
struct ubi_ec_hdr *ec_hdr, int verbose)
{
int err, read_err = 0;
int err, read_err;
uint32_t crc, magic, hdr_crc;
dbg_io("read EC header from PEB %d", pnum);
ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
if (err) {
if (err != UBI_IO_BITFLIPS && err != -EBADMSG)
return err;
read_err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
if (read_err) {
if (read_err != UBI_IO_BITFLIPS && read_err != -EBADMSG)
return read_err;
/*
* We read all the data, but either a correctable bit-flip
@@ -740,14 +740,12 @@ int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
* this. If the EC header is still OK, we just report this as
* there was a bit-flip, to force scrubbing.
*/
if (err == -EBADMSG)
read_err = UBI_IO_BAD_HDR_EBADMSG;
}
magic = be32_to_cpu(ec_hdr->magic);
if (magic != UBI_EC_HDR_MAGIC) {
if (read_err)
return read_err;
if (read_err == -EBADMSG)
return UBI_IO_BAD_HDR_EBADMSG;
/*
* The magic field is wrong. Let's check if we have read all
@@ -762,7 +760,10 @@ int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
else if (UBI_IO_DEBUG)
dbg_msg("no EC header found at PEB %d, "
"only 0xFF bytes", pnum);
return UBI_IO_FF;
if (!read_err)
return UBI_IO_FF;
else
return UBI_IO_FF_BITFLIPS;
}
/*
@@ -790,7 +791,11 @@ int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
} else if (UBI_IO_DEBUG)
dbg_msg("bad EC header CRC at PEB %d, calculated "
"%#08x, read %#08x", pnum, crc, hdr_crc);
return read_err ?: UBI_IO_BAD_HDR;
if (!read_err)
return UBI_IO_BAD_HDR;
else
return UBI_IO_BAD_HDR_EBADMSG;
}
/* And of course validate what has just been read from the media */
@@ -986,7 +991,7 @@ bad:
int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
struct ubi_vid_hdr *vid_hdr, int verbose)
{
int err, read_err = 0;
int err, read_err;
uint32_t crc, magic, hdr_crc;
void *p;
@@ -994,20 +999,15 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
p = (char *)vid_hdr - ubi->vid_hdr_shift;
err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
read_err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
ubi->vid_hdr_alsize);
if (err) {
if (err != UBI_IO_BITFLIPS && err != -EBADMSG)
return err;
if (err == -EBADMSG)
read_err = UBI_IO_BAD_HDR_EBADMSG;
}
if (read_err && read_err != UBI_IO_BITFLIPS && read_err != -EBADMSG)
return read_err;
magic = be32_to_cpu(vid_hdr->magic);
if (magic != UBI_VID_HDR_MAGIC) {
if (read_err)
return read_err;
if (read_err == -EBADMSG)
return UBI_IO_BAD_HDR_EBADMSG;
if (check_pattern(vid_hdr, 0xFF, UBI_VID_HDR_SIZE)) {
if (verbose)
@@ -1016,7 +1016,10 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
else if (UBI_IO_DEBUG)
dbg_msg("no VID header found at PEB %d, "
"only 0xFF bytes", pnum);
return UBI_IO_FF;
if (!read_err)
return UBI_IO_FF;
else
return UBI_IO_FF_BITFLIPS;
}
if (verbose) {
@@ -1040,7 +1043,10 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
} else if (UBI_IO_DEBUG)
dbg_msg("bad CRC at PEB %d, calculated %#08x, "
"read %#08x", pnum, crc, hdr_crc);
return read_err ?: UBI_IO_BAD_HDR;
if (!read_err)
return UBI_IO_BAD_HDR;
else
return UBI_IO_BAD_HDR_EBADMSG;
}
err = validate_vid_hdr(ubi, vid_hdr);