UBI: print a warning if too many PEBs are corrupted

There was a bug report recently where UBI prints:

UBI error: ubi_attach_mtd_dev: failed to attach by scanning, error -22

error messages and refuses to attach a PEB. It turned out to be a
buggy flash driver which returned garbage to almost every UBI read.
This patch makes UBI print a better message in such cases. Namely,
if UBI finds 8 or more corrupted PEBs, it prints a warning and
lists the corrupted PEBs.

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

2 files changed, 18 insertions, 2 deletions

diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index 93361eadab8..e7161adc419 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -75,9 +75,10 @@ static int add_to_list(struct ubi_scan_info *si, int pnum, int ec,
                 dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
         else if (list == &si->erase)
                 dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
-        else if (list == &si->corr)
+        else if (list == &si->corr) {
                 dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
-        else if (list == &si->alien)
+                si->corr_count += 1;
+        } else if (list == &si->alien)
                 dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
         else
                 BUG();
@@ -938,6 +939,19 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
                 ubi_msg("empty MTD device detected");
 
         /*
+         * Few corrupted PEBs are not a problem and may be just a result of
+         * unclean reboots. However, many of them may indicate some problems
+         * with the flash HW or driver. Print a warning in this case.
+         */
+        if (si->corr_count >= 8 || si->corr_count >= ubi->peb_count / 4) {
+                ubi_warn("%d PEBs are corrupted", si->corr_count);
+                printk(KERN_WARNING "corrupted PEBs are:");
+                list_for_each_entry(seb, &si->corr, u.list)
+                        printk(KERN_CONT " %d", seb->pnum);
+                printk(KERN_CONT "\n");
+        }
+
+        /*
          * In case of unknown erase counter we use the mean erase counter
          * value.
          */
diff --git a/drivers/mtd/ubi/scan.h b/drivers/mtd/ubi/scan.h
index 1017cf12def..bab31695dac 100644
--- a/drivers/mtd/ubi/scan.h
+++ b/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
+ * @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
@@ -125,6 +126,7 @@ struct ubi_scan_info {
         int mean_ec;
         uint64_t ec_sum;
         int ec_count;
+        int corr_count;
         int image_seq_set;
 };