1 files changed, 101 insertions, 30 deletions

diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index aed19f33b8f3..372a15ac9995 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -44,6 +44,7 @@
 #include <linux/slab.h>
 #include <linux/crc32.h>
 #include <linux/math64.h>
+#include <linux/random.h>
 #include "ubi.h"
 
 #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
@@ -72,16 +73,19 @@ static int add_to_list(struct ubi_scan_info *si, int pnum, int ec,
 {
         struct ubi_scan_leb *seb;
 
-        if (list == &si->free)
+        if (list == &si->free) {
                 dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
-        else if (list == &si->erase)
+                si->free_peb_count += 1;
+        } else if (list == &si->erase) {
                 dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
-        else if (list == &si->corr) {
+                si->erase_peb_count += 1;
+        } else if (list == &si->corr) {
                 dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
-                si->corr_count += 1;
-        } else if (list == &si->alien)
+                si->corr_peb_count += 1;
+        } else if (list == &si->alien) {
                 dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
-        else
+                si->alien_peb_count += 1;
+        } else
                 BUG();
 
         seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
@@ -517,6 +521,7 @@ int ubi_scan_add_used(struct ubi_device *ubi, struct ubi_scan_info *si,
         sv->leb_count += 1;
         rb_link_node(&seb->u.rb, parent, p);
         rb_insert_color(&seb->u.rb, &sv->root);
+        si->used_peb_count += 1;
         return 0;
 }
 
@@ -745,19 +750,17 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                 bitflips = 1;
         else if (err == UBI_IO_PEB_EMPTY)
                 return add_to_list(si, pnum, UBI_SCAN_UNKNOWN_EC, &si->erase);
-        else if (err == UBI_IO_BAD_EC_HDR) {
+        else if (err == UBI_IO_BAD_HDR_READ || err == UBI_IO_BAD_HDR) {
                 /*
                  * We have to also look at the VID header, possibly it is not
                  * corrupted. Set %bitflips flag in order to make this PEB be
                  * moved and EC be re-created.
                  */
-                ec_corr = 1;
+                ec_corr = err;
                 ec = UBI_SCAN_UNKNOWN_EC;
                 bitflips = 1;
         }
 
-        si->is_empty = 0;
-
         if (!ec_corr) {
                 int image_seq;
 
@@ -813,9 +816,12 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                 return err;
         else if (err == UBI_IO_BITFLIPS)
                 bitflips = 1;
-        else if (err == UBI_IO_BAD_VID_HDR ||
+        else if (err == UBI_IO_BAD_HDR_READ || err == UBI_IO_BAD_HDR ||
                  (err == UBI_IO_PEB_FREE && ec_corr)) {
                 /* VID header is corrupted */
+                if (err == UBI_IO_BAD_HDR_READ ||
+                    ec_corr == UBI_IO_BAD_HDR_READ)
+                        si->read_err_count += 1;
                 err = add_to_list(si, pnum, ec, &si->corr);
                 if (err)
                         return err;
@@ -836,11 +842,11 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                 switch (vidh->compat) {
                 case UBI_COMPAT_DELETE:
                         ubi_msg("\"delete\" compatible internal volume %d:%d"
-                                " found, remove it", vol_id, lnum);
+                                " found, will remove it", vol_id, lnum);
                         err = add_to_list(si, pnum, ec, &si->corr);
                         if (err)
                                 return err;
-                        break;
+                        return 0;
 
                 case UBI_COMPAT_RO:
                         ubi_msg("read-only compatible internal volume %d:%d"
@@ -855,7 +861,6 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                         err = add_to_list(si, pnum, ec, &si->alien);
                         if (err)
                                 return err;
-                        si->alien_peb_count += 1;
                         return 0;
 
                 case UBI_COMPAT_REJECT:
@@ -886,6 +891,85 @@ adjust_mean_ec:
 }
 
 /**
+ * check_what_we_have - check what PEB were found by scanning.
+ * @ubi: UBI device description object
+ * @si: scanning information
+ *
+ * This is a helper function which takes a look what PEBs were found by
+ * scanning, and decides whether the flash is empty and should be formatted and
+ * whether there are too many corrupted PEBs and we should not attach this
+ * MTD device. Returns zero if we should proceed with attaching the MTD device,
+ * and %-EINVAL if we should not.
+ */
+static int check_what_we_have(struct ubi_device *ubi, struct ubi_scan_info *si)
+{
+        struct ubi_scan_leb *seb;
+        int max_corr;
+
+        max_corr = ubi->peb_count - si->bad_peb_count - si->alien_peb_count;
+        max_corr = max_corr / 20 ?: 8;
+
+        /*
+         * 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.
+         */
+        if (si->corr_peb_count >= 8) {
+                ubi_warn("%d PEBs are corrupted", si->corr_peb_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");
+
+                /*
+                 * If too many PEBs are corrupted, we refuse attaching,
+                 * otherwise, only print a warning.
+                 */
+                if (si->corr_peb_count >= max_corr) {
+                        ubi_err("too many corrupted PEBs, refusing this device");
+                        return -EINVAL;
+                }
+        }
+
+        if (si->free_peb_count + si->used_peb_count +
+            si->alien_peb_count == 0) {
+                /* No UBI-formatted eraseblocks were found */
+                if (si->corr_peb_count == si->read_err_count &&
+                    si->corr_peb_count < 8) {
+                        /* No or just few corrupted PEBs, and all of them had a
+                         * read error. We assume that those are bad PEBs, which
+                         * were just not marked as bad so far.
+                         *
+                         * This piece of code basically tries to distinguish
+                         * between the following 2 situations:
+                         *
+                         * 1. Flash is empty, but there are few bad PEBs, which
+                         *    are not marked as bad so far, and which were read
+                         *    with error. We want to go ahead and format this
+                         *    flash. While formating, the faulty PEBs will
+                         *    probably be marked as bad.
+                         *
+                         * 2. Flash probably contains non-UBI data and we do
+                         * not want to format it and destroy possibly needed
+                         * data (e.g., consider the case when the bootloader
+                         * MTD partition was accidentally fed to UBI).
+                         */
+                        si->is_empty = 1;
+                        ubi_msg("empty MTD device detected");
+                        get_random_bytes(&ubi->image_seq, sizeof(ubi->image_seq));
+                } else {
+                        ubi_err("MTD device possibly contains non-UBI data, "
+                                "refusing it");
+                        return -EINVAL;
+                }
+        }
+
+        if (si->corr_peb_count > 0)
+                ubi_msg("corrupted PEBs will be formatted");
+        return 0;
+}
+
+/**
  * ubi_scan - scan an MTD device.
  * @ubi: UBI device description object
  *
@@ -909,7 +993,6 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
         INIT_LIST_HEAD(&si->erase);
         INIT_LIST_HEAD(&si->alien);
         si->volumes = RB_ROOT;
-        si->is_empty = 1;
 
         err = -ENOMEM;
         ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
@@ -935,21 +1018,9 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
         if (si->ec_count)
                 si->mean_ec = div_u64(si->ec_sum, si->ec_count);
 
-        if (si->is_empty)
-                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");
-        }
+        err = check_what_we_have(ubi, si);
+        if (err)
+                goto out_vidh;
 
         /*
          * In case of unknown erase counter we use the mean erase counter