Merge branch 'master' into next

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index a423131b6171..b847745394b4 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -781,11 +781,22 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                         return -EINVAL;
                 }
 
+                /*
+                 * Make sure that all PEBs have the same image sequence number.
+                 * This allows us to detect situations when users flash UBI
+                 * images incorrectly, so that the flash has the new UBI image
+                 * and leftovers from the old one. This feature was added
+                 * relatively recently, and the sequence number was always
+                 * zero, because old UBI implementations always set it to zero.
+                 * For this reasons, we do not panic if some PEBs have zero
+                 * sequence number, while other PEBs have non-zero sequence
+                 * number.
+                 */
                 image_seq = be32_to_cpu(ech->image_seq);
                 if (!si->image_seq_set) {
                         ubi->image_seq = image_seq;
                         si->image_seq_set = 1;
-                } else if (ubi->image_seq != image_seq) {
+                } else if (ubi->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);