UBI: nicify image sequence number handling

Move the image seq. number handling from I/O level to the scanning
lever, where it really belongs to. Move the @image_seq_set variable
to the @struct ubi_scan_info structure, which exists only during
scanning.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/io.c

@@ -563,16 +563,15 @@ int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum)
  * This function returns zero if the erase counter header is OK, and %1 if
  * not.
  */
-static int validate_ec_hdr(struct ubi_device *ubi,
+static int validate_ec_hdr(const struct ubi_device *ubi,
 			   const struct ubi_ec_hdr *ec_hdr)
 {
 	long long ec;
-	int vid_hdr_offset, leb_start, image_seq;
+	int vid_hdr_offset, leb_start;
 
 	ec = be64_to_cpu(ec_hdr->ec);
 	vid_hdr_offset = be32_to_cpu(ec_hdr->vid_hdr_offset);
 	leb_start = be32_to_cpu(ec_hdr->data_offset);
-	image_seq = be32_to_cpu(ec_hdr->image_seq);
 
 	if (ec_hdr->version != UBI_VERSION) {
 		ubi_err("node with incompatible UBI version found: "
@@ -598,15 +597,6 @@ static int validate_ec_hdr(struct ubi_device *ubi,
 		goto bad;
 	}
 
-	if (!ubi->image_seq_set) {
-		ubi->image_seq = image_seq;
-		ubi->image_seq_set = 1;
-	} else if (ubi->image_seq != image_seq) {
-		ubi_err("bad image sequence number %d, expected %d",
-			image_seq, ubi->image_seq);
-		goto bad;
-	}
-
 	return 0;
 
 bad:

drivers/mtd/ubi/scan.c

@@ -757,6 +757,8 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
 	si->is_empty = 0;
 
 	if (!ec_corr) {
+		int image_seq;
+
 		/* Make sure UBI version is OK */
 		if (ech->version != UBI_VERSION) {
 			ubi_err("this UBI version is %d, image version is %d",
@@ -778,6 +780,18 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
 			ubi_dbg_dump_ec_hdr(ech);
 			return -EINVAL;
 		}
+
+		image_seq = be32_to_cpu(ech->ec);
+		if (!si->image_seq_set) {
+			ubi->image_seq = image_seq;
+			si->image_seq_set = 1;
+		} else if (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 */
@@ -910,8 +924,6 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
 	if (si->is_empty)
 		ubi_msg("empty MTD device detected");
 
-	ubi->image_seq_set = 1;
-
 	/*
 	 * In case of unknown erase counter we use the mean erase counter
 	 * value.

drivers/mtd/ubi/scan.h

@@ -102,6 +102,7 @@ struct ubi_scan_volume {
  * @mean_ec: mean erase counter value
  * @ec_sum: a temporary variable used when calculating @mean_ec
  * @ec_count: a temporary variable used when calculating @mean_ec
+ * @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
@@ -124,6 +125,7 @@ struct ubi_scan_info {
 	int mean_ec;
 	uint64_t ec_sum;
 	int ec_count;
+	int image_seq_set;
 };
 
 struct ubi_device;

drivers/mtd/ubi/ubi.h

@@ -302,7 +302,6 @@ struct ubi_wl_entry;
  *                @vol->ref_count, @vol->mapping and @vol->eba_tbl.
  * @ref_count: count of references on the UBI device
  * @image_seq: image sequence number recorded on EC headers
- * @image_seq_set: indicates @image_seq is known
  *
  * @rsvd_pebs: count of reserved physical eraseblocks
  * @avail_pebs: count of available physical eraseblocks
@@ -393,7 +392,6 @@ struct ubi_device {
 	spinlock_t volumes_lock;
 	int ref_count;
 	int image_seq;
-	int image_seq_set;
 
 	int rsvd_pebs;
 	int avail_pebs;