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UBI: improve corrupted flash handling

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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>
This commit is contained in:
Artem Bityutskiy 2010-04-30 13:02:33 +03:00
parent 33789fb9d4
commit 0798cea8c2
1 changed files with 82 additions and 19 deletions
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101
drivers/mtd/ubi/scan.c
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@ -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 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
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