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authorArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2010-04-30 13:02:33 +0300
committerArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2010-06-04 11:30:44 +0300
commit0798cea8c2e1afee59686c51d27d0e96b05e42d1 (patch)
tree7bc5702e9bdeb37699f3cce0d4641d15676e74f2 /drivers/mtd/ubi
parent33789fb9d4470e27d18596c0966339e2ca8865a9 (diff)
UBI: improve corrupted flash handling
This patch improves the way UBI handles corrupted flash, or flash containing garbage or non-UBI data, which is the same from UBI POW. Namely, we do the following: * if 5% or more PEBs are corrupted, refuse the flash * if less than 5% PEBs are corrupted, do not refuse the flash and format these PEBs * if less than 8 PEBs are corrupted, format them silently, otherwise print a warning message. Reported-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Reviewed-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Tested-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Diffstat (limited to 'drivers/mtd/ubi')
-rw-r--r--drivers/mtd/ubi/scan.c101
1 files changed, 82 insertions, 19 deletions
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index a20f278d0c6..6b7c0c4baf0 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -760,8 +760,6 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
bitflips = 1;
}
- si->is_empty = 0;
-
if (!ec_corr) {
int image_seq;
@@ -892,6 +890,85 @@ 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(const 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");
+ } 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
*
@@ -915,7 +992,6 @@ 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);
@@ -941,22 +1017,9 @@ 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_peb_count >= 8 ||
- si->corr_peb_count >= ubi->peb_count / 4) {
- 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");
- }
+ err = check_what_we_have(ubi, si);
+ if (err)
+ goto out_vidh;
/*
* In case of unknown erase counter we use the mean erase counter