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>
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@ -760,8 +760,6 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
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bitflips = 1;
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}
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si->is_empty = 0;
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if (!ec_corr) {
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int image_seq;
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@ -891,6 +889,85 @@ adjust_mean_ec:
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return 0;
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}
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/**
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* check_what_we_have - check what PEB were found by scanning.
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* @ubi: UBI device description object
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* @si: scanning information
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*
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* This is a helper function which takes a look what PEBs were found by
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* scanning, and decides whether the flash is empty and should be formatted and
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* whether there are too many corrupted PEBs and we should not attach this
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* MTD device. Returns zero if we should proceed with attaching the MTD device,
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* and %-EINVAL if we should not.
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*/
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static int check_what_we_have(const struct ubi_device *ubi,
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struct ubi_scan_info *si)
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{
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struct ubi_scan_leb *seb;
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int max_corr;
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max_corr = ubi->peb_count - si->bad_peb_count - si->alien_peb_count;
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max_corr = max_corr / 20 ?: 8;
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/*
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* Few corrupted PEBs are not a problem and may be just a result of
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* unclean reboots. However, many of them may indicate some problems
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* with the flash HW or driver.
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*/
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if (si->corr_peb_count >= 8) {
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ubi_warn("%d PEBs are corrupted", si->corr_peb_count);
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printk(KERN_WARNING "corrupted PEBs are:");
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list_for_each_entry(seb, &si->corr, u.list)
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printk(KERN_CONT " %d", seb->pnum);
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printk(KERN_CONT "\n");
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/*
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* If too many PEBs are corrupted, we refuse attaching,
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* otherwise, only print a warning.
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*/
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if (si->corr_peb_count >= max_corr) {
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ubi_err("too many corrupted PEBs, refusing this device");
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return -EINVAL;
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}
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}
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if (si->free_peb_count + si->used_peb_count +
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si->alien_peb_count == 0) {
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/* No UBI-formatted eraseblocks were found */
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if (si->corr_peb_count == si->read_err_count &&
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si->corr_peb_count < 8) {
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/* No or just few corrupted PEBs, and all of them had a
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* read error. We assume that those are bad PEBs, which
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* were just not marked as bad so far.
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*
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* This piece of code basically tries to distinguish
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* between the following 2 situations:
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*
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* 1. Flash is empty, but there are few bad PEBs, which
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* are not marked as bad so far, and which were read
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* with error. We want to go ahead and format this
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* flash. While formating, the faulty PEBs will
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* probably be marked as bad.
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*
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* 2. Flash probably contains non-UBI data and we do
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* not want to format it and destroy possibly needed
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* data (e.g., consider the case when the bootloader
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* MTD partition was accidentally fed to UBI).
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*/
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si->is_empty = 1;
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ubi_msg("empty MTD device detected");
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} else {
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ubi_err("MTD device possibly contains non-UBI data, "
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"refusing it");
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return -EINVAL;
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}
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}
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if (si->corr_peb_count >= 0)
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ubi_msg("corrupted PEBs will be formatted");
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return 0;
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}
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/**
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* ubi_scan - scan an MTD device.
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* @ubi: UBI device description object
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@ -915,7 +992,6 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
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INIT_LIST_HEAD(&si->erase);
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INIT_LIST_HEAD(&si->alien);
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si->volumes = RB_ROOT;
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si->is_empty = 1;
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err = -ENOMEM;
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ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
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@ -941,22 +1017,9 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
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if (si->ec_count)
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si->mean_ec = div_u64(si->ec_sum, si->ec_count);
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if (si->is_empty)
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ubi_msg("empty MTD device detected");
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/*
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* Few corrupted PEBs are not a problem and may be just a result of
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* unclean reboots. However, many of them may indicate some problems
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* with the flash HW or driver. Print a warning in this case.
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*/
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if (si->corr_peb_count >= 8 ||
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si->corr_peb_count >= ubi->peb_count / 4) {
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ubi_warn("%d PEBs are corrupted", si->corr_peb_count);
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printk(KERN_WARNING "corrupted PEBs are:");
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list_for_each_entry(seb, &si->corr, u.list)
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printk(KERN_CONT " %d", seb->pnum);
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printk(KERN_CONT "\n");
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}
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err = check_what_we_have(ubi, si);
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if (err)
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goto out_vidh;
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/*
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* In case of unknown erase counter we use the mean erase counter
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