From 0798cea8c2e1afee59686c51d27d0e96b05e42d1 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Fri, 30 Apr 2010 13:02:33 +0300 Subject: 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 Signed-off-by: Artem Bityutskiy Reviewed-by: Sebastian Andrzej Siewior Tested-by: Sebastian Andrzej Siewior --- drivers/mtd/ubi/scan.c | 101 +++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 82 insertions(+), 19 deletions(-) (limited to 'drivers/mtd') diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c index a20f278d0c6c..6b7c0c4baf07 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; @@ -891,6 +889,85 @@ adjust_mean_ec: return 0; } +/** + * 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 -- cgit v1.2.3