UBI: add image sequence number to EC header

An image sequence number is added to the UBI erase-counter header
to be able determine if the root file system contains a mixture
of old and new images (because the flashing failed to complete).

A change to nolo is also needed for this to take effect.

Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

6 files changed, 33 insertions, 3 deletions

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 286ed594e5a0..db0b9cb64c6c 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -996,6 +996,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
         ubi_msg("number of PEBs reserved for bad PEB handling: %d",
                 ubi->beb_rsvd_pebs);
         ubi_msg("max/mean erase counter: %d/%d", ubi->max_ec, ubi->mean_ec);
+        ubi_msg("image sequence number: %d", ubi->image_seq);
 
         /*
          * The below lock makes sure we do not race with 'ubi_thread()' which
diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index c0ed60e8ade9..54b0186915fb 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -44,6 +44,8 @@ void ubi_dbg_dump_ec_hdr(const struct ubi_ec_hdr *ec_hdr)
                be32_to_cpu(ec_hdr->vid_hdr_offset));
         printk(KERN_DEBUG "\tdata_offset    %d\n",
                be32_to_cpu(ec_hdr->data_offset));
+        printk(KERN_DEBUG "\timage_seq      %d\n",
+               be32_to_cpu(ec_hdr->image_seq));
         printk(KERN_DEBUG "\thdr_crc        %#08x\n",
                be32_to_cpu(ec_hdr->hdr_crc));
         printk(KERN_DEBUG "erase counter header hexdump:\n");
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index c8edbfd09b64..b58714011091 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -563,15 +563,16 @@ 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(const struct ubi_device *ubi,
+static int validate_ec_hdr(struct ubi_device *ubi,
                            const struct ubi_ec_hdr *ec_hdr)
 {
         long long ec;
-        int vid_hdr_offset, leb_start;
+        int vid_hdr_offset, leb_start, image_seq;
 
         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: "
@@ -597,6 +598,15 @@ static int validate_ec_hdr(const 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:
@@ -742,6 +752,7 @@ int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
         ec_hdr->version = UBI_VERSION;
         ec_hdr->vid_hdr_offset = cpu_to_be32(ubi->vid_hdr_offset);
         ec_hdr->data_offset = cpu_to_be32(ubi->leb_start);
+        ec_hdr->image_seq = cpu_to_be32(ubi->image_seq);
         crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
         ec_hdr->hdr_crc = cpu_to_be32(crc);
 
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index c3d653ba5ca0..72570ed7d33f 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -910,6 +910,8 @@ 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.
diff --git a/drivers/mtd/ubi/ubi-media.h b/drivers/mtd/ubi/ubi-media.h
index 8419fdccc79c..503ea9b27309 100644
--- a/drivers/mtd/ubi/ubi-media.h
+++ b/drivers/mtd/ubi/ubi-media.h
@@ -129,6 +129,7 @@ enum {
  * @ec: the erase counter
  * @vid_hdr_offset: where the VID header starts
  * @data_offset: where the user data start
+ * @image_seq: image sequence number
  * @padding2: reserved for future, zeroes
  * @hdr_crc: erase counter header CRC checksum
  *
@@ -144,6 +145,14 @@ enum {
  * volume identifier header and user data, relative to the beginning of the
  * physical eraseblock. These values have to be the same for all physical
  * eraseblocks.
+ *
+ * The @image_seq field is used to validate a UBI image that has been prepared
+ * for a UBI device. The @image_seq value can be any value, but it must be the
+ * same on all eraseblocks. UBI will ensure that all new erase counter headers
+ * also contain this value, and will check the value when scanning at start-up.
+ * One way to make use of @image_seq is to increase its value by one every time
+ * an image is flashed over an existing image, then, if the flashing does not
+ * complete, UBI will detect the error when scanning.
  */
 struct ubi_ec_hdr {
         __be32  magic;
@@ -152,7 +161,8 @@ struct ubi_ec_hdr {
         __be64  ec; /* Warning: the current limit is 31-bit anyway! */
         __be32  vid_hdr_offset;
         __be32  data_offset;
-        __u8    padding2[36];
+        __be32  image_seq;
+        __u8    padding2[32];
         __be32  hdr_crc;
 } __attribute__ ((packed));
 
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 28acd133c997..bb372c4222b7 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -301,6 +301,8 @@ struct ubi_wl_entry;
  *                @vol->readers, @vol->writers, @vol->exclusive,
  *                @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
@@ -390,6 +392,8 @@ struct ubi_device {
         struct ubi_volume *volumes[UBI_MAX_VOLUMES+UBI_INT_VOL_COUNT];
         spinlock_t volumes_lock;
         int ref_count;
+        int image_seq;
+        int image_seq_set;
 
         int rsvd_pebs;
         int avail_pebs;