UBI: fix backward compatibility

Commit 32bc4820287a1a03982979515949e8ea56eac641 did not fully fix
the backward compatibility issues. We still fail to properly handle
situations when the first PEB contains non-zero image sequence
number, but one of the following PEBs contains zero image sequence
number. For example, this may happen if we mount a new image with
an old kernel, and then try to mount it in the new kernel.

This patch should fix the issue.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index e7161ad..90af61a 100644 (file)
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -794,16 +794,15 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                 * number.
                 */
                image_seq = be32_to_cpu(ech->image_seq);
-               if (!si->image_seq_set) {
+               if (!ubi->image_seq && image_seq)
                        ubi->image_seq = image_seq;
-                       si->image_seq_set = 1;
-               } else if (ubi->image_seq && ubi->image_seq != image_seq) {
+               if (ubi->image_seq && image_seq &&
+                   ubi->image_seq != image_seq) {
                        ubi_err("bad image sequence number %d in PEB %d, "
                                "expected %d", image_seq, pnum, ubi->image_seq);
                        ubi_dbg_dump_ec_hdr(ech);
                        return -EINVAL;
                }
-
        }
 
        /* OK, we've done with the EC header, let's look at the VID header */

diff --git a/drivers/mtd/ubi/scan.h b/drivers/mtd/ubi/scan.h
index bab3169..ff179ad 100644 (file)
--- a/drivers/mtd/ubi/scan.h
+++ b/drivers/mtd/ubi/scan.h
@@ -103,7 +103,6 @@ struct ubi_scan_volume {
  * @ec_sum: a temporary variable used when calculating @mean_ec
  * @ec_count: a temporary variable used when calculating @mean_ec
  * @corr_count: count of corrupted PEBs
- * @image_seq_set: indicates @ubi->image_seq is known
  *
  * This data structure contains the result of scanning and may be used by other
  * UBI sub-systems to build final UBI data structures, further error-recovery
@@ -127,7 +126,6 @@ struct ubi_scan_info {
        uint64_t ec_sum;
        int ec_count;
        int corr_count;
-       int image_seq_set;
 };
 
 struct ubi_device;