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path: root/drivers/mtd/ubi/scan.c
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Diffstat (limited to 'drivers/mtd/ubi/scan.c')
-rw-r--r--drivers/mtd/ubi/scan.c387
1 files changed, 269 insertions, 118 deletions
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index 69b52e9c9489..3c631863bf40 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -29,7 +29,7 @@
* objects which are kept in volume RB-tree with root at the @volumes field.
* The RB-tree is indexed by the volume ID.
*
- * Found logical eraseblocks are represented by &struct ubi_scan_leb objects.
+ * Scanned logical eraseblocks are represented by &struct ubi_scan_leb objects.
* These objects are kept in per-volume RB-trees with the root at the
* corresponding &struct ubi_scan_volume object. To put it differently, we keep
* an RB-tree of per-volume objects and each of these objects is the root of
@@ -38,6 +38,33 @@
* Corrupted physical eraseblocks are put to the @corr list, free physical
* eraseblocks are put to the @free list and the physical eraseblock to be
* erased are put to the @erase list.
+ *
+ * UBI tries to distinguish between 2 types of corruptions.
+ * 1. Corruptions caused by power cuts. These are harmless and expected
+ * corruptions and UBI tries to handle them gracefully, without printing too
+ * many warnings and error messages. The idea is that we do not lose
+ * important data in these case - we may lose only the data which was being
+ * written to the media just before the power cut happened, and the upper
+ * layers (e.g., UBIFS) are supposed to handle these situations. UBI puts
+ * these PEBs to the head of the @erase list and they are scheduled for
+ * erasure.
+ *
+ * 2. Unexpected corruptions which are not caused by power cuts. During
+ * scanning, such PEBs are put to the @corr list and UBI preserves them.
+ * Obviously, this lessens the amount of available PEBs, and if at some
+ * point UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly
+ * informs about such PEBs every time the MTD device is attached.
+ *
+ * However, it is difficult to reliably distinguish between these types of
+ * corruptions and UBI's strategy is as follows. UBI assumes (2.) if the VID
+ * header is corrupted and the data area does not contain all 0xFFs, and there
+ * were not bit-flips or integrity errors while reading the data area. Otherwise
+ * UBI assumes (1.). The assumptions are:
+ * o if the data area contains only 0xFFs, there is no data, and it is safe
+ * to just erase this PEB.
+ * o if the data area has bit-flips and data integrity errors (ECC errors on
+ * NAND), it is probably a PEB which was being erased when power cut
+ * happened.
*/
#include <linux/err.h>
@@ -62,26 +89,26 @@ static struct ubi_vid_hdr *vidh;
* @si: scanning information
* @pnum: physical eraseblock number to add
* @ec: erase counter of the physical eraseblock
+ * @to_head: if not zero, add to the head of the list
* @list: the list to add to
*
- * This function adds physical eraseblock @pnum to free, erase, corrupted or
- * alien lists. Returns zero in case of success and a negative error code in
- * case of failure.
+ * This function adds physical eraseblock @pnum to free, erase, or alien lists.
+ * If @to_head is not zero, PEB will be added to the head of the list, which
+ * basically means it will be processed first later. E.g., we add corrupted
+ * PEBs (corrupted due to power cuts) to the head of the erase list to make
+ * sure we erase them first and get rid of corruptions ASAP. This function
+ * returns zero in case of success and a negative error code in case of
+ * failure.
*/
-static int add_to_list(struct ubi_scan_info *si, int pnum, int ec,
+static int add_to_list(struct ubi_scan_info *si, int pnum, int ec, int to_head,
struct list_head *list)
{
struct ubi_scan_leb *seb;
if (list == &si->free) {
dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
- si->free_peb_count += 1;
} else if (list == &si->erase) {
dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
- si->erase_peb_count += 1;
- } else if (list == &si->corr) {
- dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
- si->corr_peb_count += 1;
} else if (list == &si->alien) {
dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
si->alien_peb_count += 1;
@@ -94,7 +121,37 @@ static int add_to_list(struct ubi_scan_info *si, int pnum, int ec,
seb->pnum = pnum;
seb->ec = ec;
- list_add_tail(&seb->u.list, list);
+ if (to_head)
+ list_add(&seb->u.list, list);
+ else
+ list_add_tail(&seb->u.list, list);
+ return 0;
+}
+
+/**
+ * add_corrupted - add a corrupted physical eraseblock.
+ * @si: scanning information
+ * @pnum: physical eraseblock number to add
+ * @ec: erase counter of the physical eraseblock
+ *
+ * This function adds corrupted physical eraseblock @pnum to the 'corr' list.
+ * The corruption was presumably not caused by a power cut. Returns zero in
+ * case of success and a negative error code in case of failure.
+ */
+static int add_corrupted(struct ubi_scan_info *si, int pnum, int ec)
+{
+ struct ubi_scan_leb *seb;
+
+ dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
+
+ seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
+ if (!seb)
+ return -ENOMEM;
+
+ si->corr_peb_count += 1;
+ seb->pnum = pnum;
+ seb->ec = ec;
+ list_add(&seb->u.list, &si->corr);
return 0;
}
@@ -258,8 +315,8 @@ static int compare_lebs(struct ubi_device *ubi, const struct ubi_scan_leb *seb,
* created before sequence numbers support has been added. At
* that times we used 32-bit LEB versions stored in logical
* eraseblocks. That was before UBI got into mainline. We do not
- * support these images anymore. Well, those images will work
- * still work, but only if no unclean reboots happened.
+ * support these images anymore. Well, those images still work,
+ * but only if no unclean reboots happened.
*/
ubi_err("unsupported on-flash UBI format\n");
return -EINVAL;
@@ -285,19 +342,25 @@ static int compare_lebs(struct ubi_device *ubi, const struct ubi_scan_leb *seb,
return 1;
}
} else {
- pnum = seb->pnum;
+ if (!seb->copy_flag) {
+ /* It is not a copy, so it is newer */
+ dbg_bld("first PEB %d is newer, copy_flag is unset",
+ pnum);
+ return bitflips << 1;
+ }
vh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
if (!vh)
return -ENOMEM;
+ pnum = seb->pnum;
err = ubi_io_read_vid_hdr(ubi, pnum, vh, 0);
if (err) {
if (err == UBI_IO_BITFLIPS)
bitflips = 1;
else {
dbg_err("VID of PEB %d header is bad, but it "
- "was OK earlier", pnum);
+ "was OK earlier, err %d", pnum, err);
if (err > 0)
err = -EIO;
@@ -305,14 +368,6 @@ static int compare_lebs(struct ubi_device *ubi, const struct ubi_scan_leb *seb,
}
}
- if (!vh->copy_flag) {
- /* It is not a copy, so it is newer */
- dbg_bld("first PEB %d is newer, copy_flag is unset",
- pnum);
- err = bitflips << 1;
- goto out_free_vidh;
- }
-
vid_hdr = vh;
}
@@ -463,18 +518,15 @@ int ubi_scan_add_used(struct ubi_device *ubi, struct ubi_scan_info *si,
if (err)
return err;
- if (cmp_res & 4)
- err = add_to_list(si, seb->pnum, seb->ec,
- &si->corr);
- else
- err = add_to_list(si, seb->pnum, seb->ec,
- &si->erase);
+ err = add_to_list(si, seb->pnum, seb->ec, cmp_res & 4,
+ &si->erase);
if (err)
return err;
seb->ec = ec;
seb->pnum = pnum;
seb->scrub = ((cmp_res & 2) || bitflips);
+ seb->copy_flag = vid_hdr->copy_flag;
seb->sqnum = sqnum;
if (sv->highest_lnum == lnum)
@@ -487,10 +539,8 @@ int ubi_scan_add_used(struct ubi_device *ubi, struct ubi_scan_info *si,
* This logical eraseblock is older than the one found
* previously.
*/
- if (cmp_res & 4)
- return add_to_list(si, pnum, ec, &si->corr);
- else
- return add_to_list(si, pnum, ec, &si->erase);
+ return add_to_list(si, pnum, ec, cmp_res & 4,
+ &si->erase);
}
}
@@ -510,8 +560,9 @@ int ubi_scan_add_used(struct ubi_device *ubi, struct ubi_scan_info *si,
seb->ec = ec;
seb->pnum = pnum;
seb->lnum = lnum;
- seb->sqnum = sqnum;
seb->scrub = bitflips;
+ seb->copy_flag = vid_hdr->copy_flag;
+ seb->sqnum = sqnum;
if (sv->highest_lnum <= lnum) {
sv->highest_lnum = lnum;
@@ -521,7 +572,6 @@ 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;
}
@@ -668,8 +718,8 @@ out_free:
struct ubi_scan_leb *ubi_scan_get_free_peb(struct ubi_device *ubi,
struct ubi_scan_info *si)
{
- int err = 0, i;
- struct ubi_scan_leb *seb;
+ int err = 0;
+ struct ubi_scan_leb *seb, *tmp_seb;
if (!list_empty(&si->free)) {
seb = list_entry(si->free.next, struct ubi_scan_leb, u.list);
@@ -678,38 +728,86 @@ struct ubi_scan_leb *ubi_scan_get_free_peb(struct ubi_device *ubi,
return seb;
}
- for (i = 0; i < 2; i++) {
- struct list_head *head;
- struct ubi_scan_leb *tmp_seb;
+ /*
+ * We try to erase the first physical eraseblock from the erase list
+ * and pick it if we succeed, or try to erase the next one if not. And
+ * so forth. We don't want to take care about bad eraseblocks here -
+ * they'll be handled later.
+ */
+ list_for_each_entry_safe(seb, tmp_seb, &si->erase, u.list) {
+ if (seb->ec == UBI_SCAN_UNKNOWN_EC)
+ seb->ec = si->mean_ec;
- if (i == 0)
- head = &si->erase;
- else
- head = &si->corr;
+ err = ubi_scan_erase_peb(ubi, si, seb->pnum, seb->ec+1);
+ if (err)
+ continue;
+ seb->ec += 1;
+ list_del(&seb->u.list);
+ dbg_bld("return PEB %d, EC %d", seb->pnum, seb->ec);
+ return seb;
+ }
+
+ ubi_err("no free eraseblocks");
+ return ERR_PTR(-ENOSPC);
+}
+
+/**
+ * check_corruption - check the data area of PEB.
+ * @ubi: UBI device description object
+ * @vid_hrd: the (corrupted) VID header of this PEB
+ * @pnum: the physical eraseblock number to check
+ *
+ * This is a helper function which is used to distinguish between VID header
+ * corruptions caused by power cuts and other reasons. If the PEB contains only
+ * 0xFF bytes in the data area, the VID header is most probably corrupted
+ * because of a power cut (%0 is returned in this case). Otherwise, it was
+ * probably corrupted for some other reasons (%1 is returned in this case). A
+ * negative error code is returned if a read error occurred.
+ *
+ * If the corruption reason was a power cut, UBI can safely erase this PEB.
+ * Otherwise, it should preserve it to avoid possibly destroying important
+ * information.
+ */
+static int check_corruption(struct ubi_device *ubi, struct ubi_vid_hdr *vid_hdr,
+ int pnum)
+{
+ int err;
+
+ mutex_lock(&ubi->buf_mutex);
+ memset(ubi->peb_buf1, 0x00, ubi->leb_size);
+
+ err = ubi_io_read(ubi, ubi->peb_buf1, pnum, ubi->leb_start,
+ ubi->leb_size);
+ if (err == UBI_IO_BITFLIPS || err == -EBADMSG) {
/*
- * We try to erase the first physical eraseblock from the @head
- * list and pick it if we succeed, or try to erase the
- * next one if not. And so forth. We don't want to take care
- * about bad eraseblocks here - they'll be handled later.
+ * Bit-flips or integrity errors while reading the data area.
+ * It is difficult to say for sure what type of corruption is
+ * this, but presumably a power cut happened while this PEB was
+ * erased, so it became unstable and corrupted, and should be
+ * erased.
*/
- list_for_each_entry_safe(seb, tmp_seb, head, u.list) {
- if (seb->ec == UBI_SCAN_UNKNOWN_EC)
- seb->ec = si->mean_ec;
+ return 0;
+ }
- err = ubi_scan_erase_peb(ubi, si, seb->pnum, seb->ec+1);
- if (err)
- continue;
+ if (err)
+ return err;
- seb->ec += 1;
- list_del(&seb->u.list);
- dbg_bld("return PEB %d, EC %d", seb->pnum, seb->ec);
- return seb;
- }
+ if (ubi_check_pattern(ubi->peb_buf1, 0xFF, ubi->leb_size)) {
+ mutex_unlock(&ubi->buf_mutex);
+ return 0;
}
- ubi_err("no eraseblocks found");
- return ERR_PTR(-ENOSPC);
+ ubi_err("PEB %d contains corrupted VID header, and the data does not "
+ "contain all 0xFF, this may be a non-UBI PEB or a severe VID "
+ "header corruption which requires manual inspection", pnum);
+ ubi_dbg_dump_vid_hdr(vid_hdr);
+ dbg_msg("hexdump of PEB %d offset %d, length %d",
+ pnum, ubi->leb_start, ubi->leb_size);
+ ubi_dbg_print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+ ubi->peb_buf1, ubi->leb_size, 1);
+ mutex_unlock(&ubi->buf_mutex);
+ return 1;
}
/**
@@ -725,7 +823,7 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
int pnum)
{
long long uninitialized_var(ec);
- int err, bitflips = 0, vol_id, ec_corr = 0;
+ int err, bitflips = 0, vol_id, ec_err = 0;
dbg_bld("scan PEB %d", pnum);
@@ -746,22 +844,37 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
if (err < 0)
return err;
- else if (err == UBI_IO_BITFLIPS)
+ switch (err) {
+ case 0:
+ break;
+ case UBI_IO_BITFLIPS:
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_HDR_READ || err == UBI_IO_BAD_HDR) {
+ break;
+ case UBI_IO_FF:
+ si->empty_peb_count += 1;
+ return add_to_list(si, pnum, UBI_SCAN_UNKNOWN_EC, 0,
+ &si->erase);
+ case UBI_IO_FF_BITFLIPS:
+ si->empty_peb_count += 1;
+ return add_to_list(si, pnum, UBI_SCAN_UNKNOWN_EC, 1,
+ &si->erase);
+ case UBI_IO_BAD_HDR_EBADMSG:
+ case 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 = err;
+ ec_err = err;
ec = UBI_SCAN_UNKNOWN_EC;
bitflips = 1;
+ break;
+ default:
+ ubi_err("'ubi_io_read_ec_hdr()' returned unknown code %d", err);
+ return -EINVAL;
}
- if (!ec_corr) {
+ if (!ec_err) {
int image_seq;
/* Make sure UBI version is OK */
@@ -814,24 +927,67 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
err = ubi_io_read_vid_hdr(ubi, pnum, vidh, 0);
if (err < 0)
return err;
- else if (err == UBI_IO_BITFLIPS)
+ switch (err) {
+ case 0:
+ break;
+ case UBI_IO_BITFLIPS:
bitflips = 1;
- 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);
+ break;
+ case UBI_IO_BAD_HDR_EBADMSG:
+ if (ec_err == UBI_IO_BAD_HDR_EBADMSG)
+ /*
+ * Both EC and VID headers are corrupted and were read
+ * with data integrity error, probably this is a bad
+ * PEB, bit it is not marked as bad yet. This may also
+ * be a result of power cut during erasure.
+ */
+ si->maybe_bad_peb_count += 1;
+ case UBI_IO_BAD_HDR:
+ if (ec_err)
+ /*
+ * Both headers are corrupted. There is a possibility
+ * that this a valid UBI PEB which has corresponding
+ * LEB, but the headers are corrupted. However, it is
+ * impossible to distinguish it from a PEB which just
+ * contains garbage because of a power cut during erase
+ * operation. So we just schedule this PEB for erasure.
+ */
+ err = 0;
+ else
+ /*
+ * The EC was OK, but the VID header is corrupted. We
+ * have to check what is in the data area.
+ */
+ err = check_corruption(ubi, vidh, pnum);
+
+ if (err < 0)
+ return err;
+ else if (!err)
+ /* This corruption is caused by a power cut */
+ err = add_to_list(si, pnum, ec, 1, &si->erase);
+ else
+ /* This is an unexpected corruption */
+ err = add_corrupted(si, pnum, ec);
if (err)
return err;
goto adjust_mean_ec;
- } else if (err == UBI_IO_PEB_FREE) {
- /* No VID header - the physical eraseblock is free */
- err = add_to_list(si, pnum, ec, &si->free);
+ case UBI_IO_FF_BITFLIPS:
+ err = add_to_list(si, pnum, ec, 1, &si->erase);
if (err)
return err;
goto adjust_mean_ec;
+ case UBI_IO_FF:
+ if (ec_err)
+ err = add_to_list(si, pnum, ec, 1, &si->erase);
+ else
+ err = add_to_list(si, pnum, ec, 0, &si->free);
+ if (err)
+ return err;
+ goto adjust_mean_ec;
+ default:
+ ubi_err("'ubi_io_read_vid_hdr()' returned unknown code %d",
+ err);
+ return -EINVAL;
}
vol_id = be32_to_cpu(vidh->vol_id);
@@ -843,7 +999,7 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
case UBI_COMPAT_DELETE:
ubi_msg("\"delete\" compatible internal volume %d:%d"
" found, will remove it", vol_id, lnum);
- err = add_to_list(si, pnum, ec, &si->erase);
+ err = add_to_list(si, pnum, ec, 1, &si->erase);
if (err)
return err;
return 0;
@@ -858,7 +1014,7 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
case UBI_COMPAT_PRESERVE:
ubi_msg("\"preserve\" compatible internal volume %d:%d"
" found", vol_id, lnum);
- err = add_to_list(si, pnum, ec, &si->alien);
+ err = add_to_list(si, pnum, ec, 0, &si->alien);
if (err)
return err;
return 0;
@@ -870,7 +1026,7 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
}
}
- if (ec_corr)
+ if (ec_err)
ubi_warn("valid VID header but corrupted EC header at PEB %d",
pnum);
err = ubi_scan_add_used(ubi, si, pnum, ec, vidh, bitflips);
@@ -878,7 +1034,7 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
return err;
adjust_mean_ec:
- if (!ec_corr) {
+ if (!ec_err) {
si->ec_sum += ec;
si->ec_count += 1;
if (ec > si->max_ec)
@@ -904,19 +1060,20 @@ adjust_mean_ec:
static int check_what_we_have(struct ubi_device *ubi, struct ubi_scan_info *si)
{
struct ubi_scan_leb *seb;
- int max_corr;
+ int max_corr, peb_count;
- max_corr = ubi->peb_count - si->bad_peb_count - si->alien_peb_count;
- max_corr = max_corr / 20 ?: 8;
+ peb_count = ubi->peb_count - si->bad_peb_count - si->alien_peb_count;
+ max_corr = peb_count / 20 ?: 8;
/*
- * Few corrupted PEBs are not a problem and may be just a result of
+ * Few corrupted PEBs is 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:");
+ if (si->corr_peb_count) {
+ ubi_err("%d PEBs are corrupted and preserved",
+ si->corr_peb_count);
+ printk(KERN_ERR "Corrupted PEBs are:");
list_for_each_entry(seb, &si->corr, u.list)
printk(KERN_CONT " %d", seb->pnum);
printk(KERN_CONT "\n");
@@ -931,41 +1088,35 @@ static int check_what_we_have(struct ubi_device *ubi, struct ubi_scan_info *si)
}
}
- 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).
- */
+ if (si->empty_peb_count + si->maybe_bad_peb_count == peb_count) {
+ /*
+ * All PEBs are empty, or almost all - a couple PEBs look like
+ * they may be bad PEBs which were not marked as bad yet.
+ *
+ * This piece of code basically tries to distinguish between
+ * the following 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 formatting,
+ * the faulty PEBs will probably be marked as bad.
+ *
+ * 2. Flash contains non-UBI data and we do not want to format
+ * it and destroy possibly important information.
+ */
+ if (si->maybe_bad_peb_count <= 2) {
si->is_empty = 1;
ubi_msg("empty MTD device detected");
- get_random_bytes(&ubi->image_seq, sizeof(ubi->image_seq));
+ get_random_bytes(&ubi->image_seq,
+ sizeof(ubi->image_seq));
} else {
- ubi_err("MTD device possibly contains non-UBI data, "
- "refusing it");
+ ubi_err("MTD device is not UBI-formatted and possibly "
+ "contains non-UBI data - refusing it");
return -EINVAL;
}
+
}
- if (si->corr_peb_count > 0)
- ubi_msg("corrupted PEBs will be formatted");
return 0;
}