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    Subject[PATCH 16/44 take 2] [UBI] scanning unit implementation
    diff -auNrp tmp-from/drivers/mtd/ubi/scan.c tmp-to/drivers/mtd/ubi/scan.c
    --- tmp-from/drivers/mtd/ubi/scan.c 1970-01-01 02:00:00.000000000 +0200
    +++ tmp-to/drivers/mtd/ubi/scan.c 2007-02-17 18:07:26.000000000 +0200
    @@ -0,0 +1,1383 @@
    +/*
    + * Copyright (c) International Business Machines Corp., 2006
    + *
    + * This program is free software; you can redistribute it and/or modify
    + * it under the terms of the GNU General Public License as published by
    + * the Free Software Foundation; either version 2 of the License, or
    + * (at your option) any later version.
    + *
    + * This program is distributed in the hope that it will be useful,
    + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
    + * the GNU General Public License for more details.
    + *
    + * You should have received a copy of the GNU General Public License
    + * along with this program; if not, write to the Free Software
    + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
    + *
    + * Author: Artem B. Bityutskiy
    + */
    +
    +#include <linux/list.h>
    +#include <linux/rbtree.h>
    +#include <linux/err.h>
    +#include <linux/crc32.h>
    +#include <linux/sched.h>
    +#include <linux/types.h>
    +#include <mtd/ubi-header.h>
    +#include "ubi.h"
    +#include "alloc.h"
    +#include "scan.h"
    +#include "io.h"
    +#include "misc.h"
    +#include "vtbl.h"
    +#include "debug.h"
    +
    +#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID_SCAN
    +static int paranoid_check_si(const struct ubi_info *ubi,
    + struct ubi_scan_info *si);
    +#else
    +#define paranoid_check_si(ubi, si) 0
    +#endif
    +
    +static int process_eb(const struct ubi_info *ubi,
    + struct ubi_scan_info *si, int pnum);
    +static void commit_to_mean_value(struct ubi_scan_info *si);
    +
    +/* Temporary variables used during scanning */
    +static struct ubi_ec_hdr *ech;
    +static struct ubi_vid_hdr *vidh;
    +
    +struct ubi_scan_info *ubi_scan(struct ubi_info *ubi)
    +{
    + int err, pnum;
    + struct rb_node *rb1, *rb2;
    + struct ubi_scan_volume *sv;
    + struct ubi_scan_leb *seb;
    + struct ubi_scan_info *si;
    + struct ubi_io_info *io = ubi->io;
    +
    + si = ubi_kzalloc(sizeof(struct ubi_scan_info));
    + if (!si)
    + return ERR_PTR(-ENOMEM);
    +
    + INIT_LIST_HEAD(&si->corr);
    + INIT_LIST_HEAD(&si->free);
    + INIT_LIST_HEAD(&si->erase);
    + INIT_LIST_HEAD(&si->alien);
    + si->volumes = RB_ROOT;
    + si->is_empty = 1;
    +
    + err = -ENOMEM;
    + ech = ubi_zalloc_ec_hdr(ubi);
    + if (!ech)
    + goto out_si;
    +
    + vidh = ubi_zalloc_vid_hdr(ubi);
    + if (!vidh)
    + goto out_ech;
    +
    + for (pnum = 0; pnum < io->peb_count; pnum++) {
    + cond_resched();
    +
    + err = process_eb(ubi, si, pnum);
    + if (unlikely(err < 0))
    + goto out_vidh;
    + }
    +
    + dbg_scan("scanning is finished");
    +
    + /* Finish mean erase counter calculations */
    + if (si->ec_count)
    + commit_to_mean_value(si);
    +
    + /*
    + * FIXME: this is actually duty of the I/O unit to initialize this, but
    + * MTD does not provide enough information.
    + */
    + io->bad_peb_count = si->bad_peb_count;
    + io->good_peb_count = io->peb_count - io->bad_peb_count;
    +
    + if (si->is_empty)
    + ubi_msg("empty MTD device detected");
    +
    + /*
    + * In case of unknown erase counter we use the mean erase counter
    + * value.
    + */
    + rb_for_each_entry(rb1, sv, &si->volumes, rb) {
    + cond_resched();
    + rb_for_each_entry(rb2, seb, &sv->root, u.rb)
    + if (seb->ec == NAND_SCAN_UNKNOWN_EC)
    + seb->ec = si->mean_ec;
    + }
    +
    + cond_resched();
    + list_for_each_entry(seb, &si->free, u.list)
    + if (seb->ec == NAND_SCAN_UNKNOWN_EC)
    + seb->ec = si->mean_ec;
    +
    + cond_resched();
    + list_for_each_entry(seb, &si->corr, u.list)
    + if (seb->ec == NAND_SCAN_UNKNOWN_EC)
    + seb->ec = si->mean_ec;
    +
    + cond_resched();
    + list_for_each_entry(seb, &si->erase, u.list)
    + if (seb->ec == NAND_SCAN_UNKNOWN_EC)
    + seb->ec = si->mean_ec;
    +
    + err = paranoid_check_si(ubi, si);
    + if (err) {
    + if (err > 0)
    + err = -EINVAL;
    + goto out_vidh;
    + }
    +
    + ubi_free_vid_hdr(ubi, vidh);
    + ubi_free_ec_hdr(ubi, ech);
    + return si;
    +
    +out_vidh:
    + ubi_free_vid_hdr(ubi, vidh);
    +out_ech:
    + ubi_free_ec_hdr(ubi, ech);
    +out_si:
    + ubi_scan_destroy_si(si);
    + return ERR_PTR(err);
    +}
    +
    +static int vid_hdr_sanity_check(const struct ubi_info *ubi,
    + const struct ubi_vid_hdr *vid_hdr,
    + const struct ubi_scan_volume *sv, int pnum);
    +
    +static int add_to_erase(struct ubi_scan_info *si, int pnum, int ec);
    +
    +static struct ubi_scan_volume *add_volume(const struct ubi_info *ubi,
    + struct ubi_scan_info *si, int vol_id,
    + int pnum,
    + const struct ubi_vid_hdr *vid_hdr);
    +
    +static int compare_lebs(const struct ubi_info *ubi,
    + const struct ubi_scan_leb *seb, int pnum,
    + const struct ubi_vid_hdr *vid_hdr);
    +
    +int ubi_scan_add_peb(const struct ubi_info *ubi, struct ubi_scan_info *si,
    + int pnum, int ec, const struct ubi_vid_hdr *vid_hdr,
    + int bitflips)
    +{
    + int err, vol_id, lnum;
    + uint32_t leb_ver;
    + struct ubi_scan_volume *sv;
    + struct ubi_scan_leb *seb;
    + struct rb_node **p, *parent = NULL;
    +
    + vol_id = ubi32_to_cpu(vid_hdr->vol_id);
    + lnum = ubi32_to_cpu(vid_hdr->lnum);
    + leb_ver = ubi32_to_cpu(vid_hdr->leb_ver);
    +
    + dbg_scan("PEB %d, LEB %d:%d, EC %d, LEB ver %u, bitflips %d",
    + pnum, vol_id, lnum, ec, leb_ver, bitflips);
    +
    + sv = add_volume(ubi, si, vol_id, pnum, vid_hdr);
    + if (unlikely(IS_ERR(sv)) < 0)
    + return PTR_ERR(sv);
    +
    + /*
    + * Walk the RB-tree of logical eraseblocks of volume @vol_id to look
    + * if this is the first instance of this logical eraseblock or not.
    + */
    + p = &sv->root.rb_node;
    + while (*p) {
    + int cmp_res;
    +
    + parent = *p;
    + seb = rb_entry(parent, struct ubi_scan_leb, u.rb);
    +
    + if (lnum != seb->lnum) {
    + if (lnum < seb->lnum)
    + p = &(*p)->rb_left;
    + else
    + p = &(*p)->rb_right;
    + continue;
    + }
    +
    + /*
    + * There is already a physical eraseblock describing the same
    + * logical eraseblock present.
    + */
    +
    + dbg_scan("this LEB already exists: PEB %d, LEB ver %u, EC %d",
    + seb->pnum, seb->leb_ver, seb->ec);
    +
    + /*
    + * Make sure that the logical eraseblocks have different
    + * versions. Otherwise the image is bad.
    + */
    + if (unlikely(seb->leb_ver == leb_ver)) {
    + ubi_err("two LEBs with same version %u", leb_ver);
    + ubi_dbg_dump_seb(seb, 0);
    + ubi_dbg_dump_vid_hdr(vid_hdr);
    + return -EINVAL;
    + }
    +
    + /*
    + * Now we have to drop the older one and preserve the newer
    + * one.
    + */
    + cmp_res = compare_lebs(ubi, seb, pnum, vid_hdr);
    + if (unlikely(cmp_res < 0))
    + return cmp_res;
    +
    + if (cmp_res & 1) {
    + /*
    + * This logical eraseblock is newer then the one
    + * found earlier.
    + */
    + err = vid_hdr_sanity_check(ubi, vid_hdr, sv,
    + pnum);
    + if (unlikely(err))
    + return err;
    +
    + if (cmp_res & 4)
    + err = ubi_scan_add_corr_peb(si, seb->pnum, seb->ec);
    + else
    + err = add_to_erase(si, seb->pnum, seb->ec);
    + if (unlikely(err))
    + return err;
    +
    + seb->ec = ec;
    + seb->pnum = pnum;
    + seb->leb_ver = leb_ver;
    + seb->scrub = ((cmp_res & 2) || bitflips);
    +
    + if (sv->highest_lnum == lnum)
    + sv->last_data_size =
    + ubi32_to_cpu(vid_hdr->data_size);
    +
    + return 0;
    + } else {
    + /*
    + * This logical eraseblock is older then the one found
    + * previously.
    + */
    + if (cmp_res & 4)
    + return ubi_scan_add_corr_peb(si, pnum, ec);
    + else
    + return add_to_erase(si, pnum, ec);
    + }
    + }
    +
    + /*
    + * We've met this logical eraseblock for the first time, add it to the
    + * scanning information.
    + */
    +
    + err = vid_hdr_sanity_check(ubi, vid_hdr, sv, pnum);
    + if (unlikely(err))
    + return err;
    +
    + seb = ubi_alloc_scan_leb();
    + if (unlikely(!seb))
    + return -ENOMEM;
    +
    + seb->ec = ec;
    + seb->pnum = pnum;
    + seb->lnum = lnum;
    + seb->leb_ver = leb_ver;
    + seb->scrub = bitflips;
    +
    + if (sv->highest_lnum <= lnum) {
    + sv->highest_lnum = lnum;
    + sv->last_data_size = ubi32_to_cpu(vid_hdr->data_size);
    + }
    +
    + sv->leb_count += 1;
    + rb_link_node(&seb->u.rb, parent, p);
    + rb_insert_color(&seb->u.rb, &sv->root);
    + return 0;
    +}
    +
    +int ubi_scan_add_corr_peb(struct ubi_scan_info *si, int pnum, int ec)
    +{
    + struct ubi_scan_leb *seb;
    +
    + dbg_scan("PEB %d (EC %d) is corrupted", pnum, ec);
    +
    + seb = ubi_alloc_scan_leb();
    + if (unlikely(!seb))
    + return -ENOMEM;
    +
    + seb->pnum = pnum;
    + seb->ec = ec;
    + list_add_tail(&seb->u.list, &si->corr);
    + return 0;
    +}
    +
    +struct ubi_scan_volume *ubi_scan_find_sv(const struct ubi_scan_info *si,
    + int vol_id)
    +{
    + struct ubi_scan_volume *sv;
    + struct rb_node *p = si->volumes.rb_node;
    +
    + while (p) {
    + sv = rb_entry(p, struct ubi_scan_volume, rb);
    +
    + if (vol_id == sv->vol_id)
    + return sv;
    +
    + if (vol_id > sv->vol_id)
    + p = p->rb_left;
    + else
    + p = p->rb_right;
    + }
    +
    + return NULL;
    +}
    +
    +struct ubi_scan_leb *ubi_scan_find_seb(const struct ubi_scan_volume *sv,
    + int lnum)
    +{
    + struct ubi_scan_leb *seb;
    + struct rb_node *p = sv->root.rb_node;
    +
    + while (p) {
    + seb = rb_entry(p, struct ubi_scan_leb, u.rb);
    +
    + if (lnum == seb->lnum)
    + return seb;
    +
    + if (lnum > seb->lnum)
    + p = p->rb_left;
    + else
    + p = p->rb_right;
    + }
    +
    + return NULL;
    +}
    +
    +void ubi_scan_rm_volume(const struct ubi_info *ubi, struct ubi_scan_info *si,
    + struct ubi_scan_volume *sv)
    +{
    + struct rb_node *rb;
    + struct ubi_scan_leb *seb;
    +
    + dbg_scan("remove scanning information about volume %d", sv->vol_id);
    +
    + while ((rb = rb_first(&sv->root))) {
    + cond_resched();
    +
    + seb = rb_entry(rb, struct ubi_scan_leb, u.rb);
    +
    + /* The physical eraseblock will be erased later */
    + rb_erase(&seb->u.rb, &sv->root);
    + list_add_tail(&seb->u.list, &si->erase);
    + }
    +
    + rb_erase(&sv->rb, &si->volumes);
    + ubi_free_scan_volume(sv);
    + si->vols_found -= 1;
    +}
    +
    +int ubi_scan_erase_peb(const struct ubi_info *ubi,
    + const struct ubi_scan_info *si, int pnum, int ec)
    +{
    + int err;
    + struct ubi_ec_hdr *ec_hdr;
    + uint64_t ec1 = ec;
    +
    + ec_hdr = ubi_zalloc_ec_hdr(ubi);
    + if (!ec_hdr)
    + return -ENOMEM;
    +
    + if (unlikely(ec1 >= UBI_MAX_ERASECOUNTER)) {
    + /*
    + * Erase counter overflow. Upgrade UBI and use 64-bit
    + * erase counters internally.
    + */
    + ubi_err("erase counter overflow at PEB %d, EC %lld",
    + pnum, (long long)ec);
    + return -EINVAL;
    + }
    +
    + ec_hdr->ec = cpu_to_ubi64(ec1);
    +
    + err = ubi_io_sync_erase(ubi, pnum, 0);
    + if (unlikely(err < 0))
    + goto out_free;
    +
    + err = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
    +
    +out_free:
    + ubi_free_ec_hdr(ubi, ec_hdr);
    + return err;
    +}
    +
    +struct ubi_scan_leb *ubi_scan_get_free_peb(const struct ubi_info *ubi,
    + struct ubi_scan_info *si)
    +{
    + int err = 0, i;
    + struct ubi_scan_leb *seb;
    +
    + if (!list_empty(&si->free)) {
    + seb = list_entry(si->free.next, struct ubi_scan_leb,
    + u.list);
    + list_del(&seb->u.list);
    + return seb;
    + }
    +
    + if (unlikely(list_empty(&si->erase) && list_empty(&si->corr))) {
    + ubi_err("no vacant eraseblocks found");
    + return ERR_PTR(-ENOSPC);
    + }
    +
    + for (i = 0; i < 2; i++) {
    + struct list_head *head;
    + struct ubi_scan_leb *tmp_seb;
    +
    + if (i == 0)
    + head = &si->erase;
    + else
    + head = &si->corr;
    +
    + /*
    + * 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.
    + */
    + list_for_each_entry_safe(seb, tmp_seb, head, u.list) {
    + cond_resched();
    +
    + if (seb->ec == NAND_SCAN_UNKNOWN_EC)
    + seb->ec = si->mean_ec;
    +
    + err = ubi_scan_erase_peb(ubi, si, seb->pnum,
    + seb->ec + 1);
    + if (unlikely(err))
    + continue;
    +
    + seb->ec += 1;
    + list_del(&seb->u.list);
    + dbg_scan("return PEB %d, EC %d", seb->pnum, seb->ec);
    + return seb;
    + }
    + }
    +
    + return ERR_PTR(err ? err : -ENOSPC);
    +}
    +
    +static void destroy_sv(struct ubi_scan_volume *sv);
    +
    +void ubi_scan_destroy_si(struct ubi_scan_info *si)
    +{
    + struct ubi_scan_leb *seb, *seb_tmp;
    + struct ubi_scan_volume *sv;
    + struct rb_node *rb;
    +
    + list_for_each_entry_safe(seb, seb_tmp, &si->alien, u.list) {
    + list_del(&seb->u.list);
    + ubi_free_scan_leb(seb);
    + }
    + list_for_each_entry_safe(seb, seb_tmp, &si->erase, u.list) {
    + list_del(&seb->u.list);
    + ubi_free_scan_leb(seb);
    + }
    + list_for_each_entry_safe(seb, seb_tmp, &si->corr, u.list) {
    + list_del(&seb->u.list);
    + ubi_free_scan_leb(seb);
    + }
    + list_for_each_entry_safe(seb, seb_tmp, &si->free, u.list) {
    + list_del(&seb->u.list);
    + ubi_free_scan_leb(seb);
    + }
    +
    + /* Destroy the volume RB-tree */
    + rb = si->volumes.rb_node;
    + while (rb) {
    + if (rb->rb_left)
    + rb = rb->rb_left;
    + else if (rb->rb_right)
    + rb = rb->rb_right;
    + else {
    + sv = rb_entry(rb, struct ubi_scan_volume, rb);
    +
    + rb = rb_parent(rb);
    + if (rb) {
    + if (rb->rb_left == &sv->rb)
    + rb->rb_left = NULL;
    + else
    + rb->rb_right = NULL;
    + }
    +
    + destroy_sv(sv);
    + }
    + }
    +
    + ubi_kfree(si);
    +}
    +
    +static int add_to_free(struct ubi_scan_info *si, int pnum, int ec);
    +static int add_to_alien(struct ubi_scan_info *si, int pnum);
    +
    +/**
    + * process_eb - read UBI headers, check them and add corresponding data
    + * to the scanning information.
    + *
    + * @ubi: the UBI device description object
    + * @si: a pointer to the scanning information
    + * @pnum: the physical eraseblock number
    + *
    + * This function returns a zero if the physical eraseblock was succesfully
    + * handled and a negative error code in case of failure.
    + */
    +static int process_eb(const struct ubi_info *ubi,
    + struct ubi_scan_info *si, int pnum)
    +{
    + long long ec;
    + int err, bitflips = 0, vol_id, ec_corr = 0;
    +
    + dbg_scan("scan PEB %d", pnum);
    +
    + /* Skip bad physical eraseblocks */
    + err = ubi_io_is_bad(ubi, pnum);
    + if (unlikely(err < 0))
    + return err;
    + else if (err) {
    + si->bad_peb_count += 1;
    + return 0;
    + }
    +
    + err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
    + if (unlikely(err < 0))
    + return err;
    + else if (unlikely(err == UBI_IO_BITFLIPS))
    + bitflips = 1;
    + else if (err == UBI_IO_PEB_EMPTY)
    + return add_to_erase(si, pnum, NAND_SCAN_UNKNOWN_EC);
    + else if (err == UBI_IO_BAD_EC_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 = 1;
    + ec = NAND_SCAN_UNKNOWN_EC;
    + bitflips = 1;
    + }
    +
    + si->is_empty = 0;
    +
    + if (!ec_corr) {
    + /* Make sure UBI version is OK */
    + if (unlikely(ech->version != UBI_VERSION)) {
    + ubi_err("this UBI version is %d, image version is %d",
    + UBI_VERSION, (int)ech->version);
    + return -EINVAL;
    + }
    +
    + ec = ubi64_to_cpu(ech->ec);
    + if (unlikely(ec > UBI_MAX_ERASECOUNTER)) {
    + /*
    + * Erase counter overflow. The EC headers have 64 bits
    + * reserved, but we anyway make use of only 31 bit
    + * values, as this seems to be enough for any existing
    + * flash. Upgrade UBI and use 64-bit erase counters
    + * internally.
    + */
    + ubi_err("erase counter overflow, max is %d",
    + UBI_MAX_ERASECOUNTER);
    + ubi_dbg_dump_ec_hdr(ech);
    + return -EINVAL;
    + }
    + }
    +
    + /* OK, we've done with the EC header, let's look at the VID header */
    +
    + err = ubi_io_read_vid_hdr(ubi, pnum, vidh, 0);
    + if (unlikely(err < 0))
    + return err;
    + else if (unlikely(err == UBI_IO_BITFLIPS))
    + bitflips = 1;
    + else if (unlikely(err == UBI_IO_BAD_VID_HDR ||
    + (err == UBI_IO_PEB_FREE && ec_corr))) {
    + /* VID header is corrupted */
    + err = ubi_scan_add_corr_peb(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_free(si, pnum, ec);
    + if (unlikely(err))
    + return err;
    + goto adjust_mean_ec;
    + }
    +
    + vol_id = ubi32_to_cpu(vidh->vol_id);
    + if (unlikely(!ubi_ivol_is_known(vol_id))) {
    + int lnum = ubi32_to_cpu(vidh->lnum);
    +
    + /* Unsupported internal volume */
    + switch (vidh->compat) {
    + case UBI_COMPAT_DELETE:
    + ubi_msg("\"delete\" compatible internal volume %d:%d"
    + " found, remove it", vol_id, lnum);
    + err = ubi_scan_add_corr_peb(si, pnum, ec);
    + if (unlikely(err))
    + return err;
    + break;
    +
    + case UBI_COMPAT_RO:
    + ubi_msg("read-only compatible internal volume %d:%d"
    + " found, switch to read-only mode",
    + vol_id, lnum);
    + ubi->io->ro_mode = 1;
    + break;
    +
    + case UBI_COMPAT_PRESERVE:
    + ubi_msg("\"preserve\" compatible internal volume %d:%d"
    + " found", vol_id, lnum);
    + err = add_to_alien(si, pnum);
    + if (unlikely(err))
    + return err;
    + si->alien_peb_count += 1;
    + return 0;
    +
    + case UBI_COMPAT_REJECT:
    + ubi_err("incompatible internal volume %d:%d found",
    + vol_id, lnum);
    + return -EINVAL;
    + }
    + }
    +
    + /* Both UBI headers seem to be fine */
    + err = ubi_scan_add_peb(ubi, si, pnum, ec, vidh, bitflips);
    + if (unlikely(err))
    + return err;
    +
    +adjust_mean_ec:
    + if (!ec_corr) {
    + if (si->ec_sum + ec < ec) {
    + commit_to_mean_value(si);
    + si->ec_sum = 0;
    + si->ec_count = 0;
    + } else {
    + si->ec_sum += ec;
    + si->ec_count += 1;
    + }
    +
    + if (ec > si->max_ec)
    + si->max_ec = ec;
    + if (ec < si->min_ec)
    + si->min_ec = ec;
    + }
    +
    + return 0;
    +}
    +
    +/**
    + * add_volume - add a volume tho the scanning information.
    + *
    + * @ubi: the UBI device description object
    + * @si: a pointer to the scanning information
    + * @vol_id: ID of the volume to add
    + * @pnum: physical eraseblock number
    + * @vid_hdr: volume identifier header
    + * @vol_info: a pointer to the corresponding volume scanning information is
    + * returned here.
    + *
    + * If the volume corresponding to the @vid_hdr logical eraseblock is already
    + * present in the scanning information, this function does nothing. Otherwise
    + * it adds corresponding volume to the scanning information. Returns the a
    + * pointer to the scanning volume object in case of success and a negative
    + * error code in case of failure.
    + */
    +static struct ubi_scan_volume *add_volume(const struct ubi_info *ubi,
    + struct ubi_scan_info *si, int vol_id,
    + int pnum,
    + const struct ubi_vid_hdr *vid_hdr)
    +{
    + struct ubi_scan_volume *sv;
    + struct rb_node **p = &si->volumes.rb_node, *parent = NULL;
    +
    + ubi_assert(vol_id == ubi32_to_cpu(vid_hdr->vol_id));
    +
    + /*
    + * Walk the volume RB-tree to look if a volume @vol_id is already
    + * present there.
    + */
    + while (*p) {
    + parent = *p;
    + sv = rb_entry(parent, struct ubi_scan_volume, rb);
    +
    + if (vol_id == sv->vol_id)
    + return sv;
    +
    + if (vol_id > sv->vol_id)
    + p = &(*p)->rb_left;
    + else
    + p = &(*p)->rb_right;
    + }
    +
    + /* The volume is absent - add it */
    +
    + sv = ubi_alloc_scan_volume();
    + if (unlikely(!sv))
    + return ERR_PTR(-ENOMEM);
    +
    + sv->highest_lnum = sv->leb_count = 0;
    + sv->vol_id = vol_id;
    + sv->root = RB_ROOT;
    + sv->used_ebs = ubi32_to_cpu(vid_hdr->used_ebs);
    + sv->data_pad = ubi32_to_cpu(vid_hdr->data_pad);
    + sv->compat = vid_hdr->compat;
    + sv->vol_type = vid_hdr->vol_type == UBI_VID_DYNAMIC ? UBI_DYNAMIC_VOLUME
    + : UBI_STATIC_VOLUME;
    + if (vol_id > si->highest_vol_id)
    + si->highest_vol_id = vol_id;
    +
    + rb_link_node(&sv->rb, parent, p);
    + rb_insert_color(&sv->rb, &si->volumes);
    + si->vols_found += 1;
    + dbg_scan("added volume %d", vol_id);
    + return sv;
    +}
    +
    +/**
    + * compare_lebs - find out which logical eraseblock is newer.
    + *
    + * @ubi: the UBI device description object
    + * @seb: the first logical eraseblock to compare
    + * @pnum: the physical eraseblock number of the second logical eraseblock to
    + * compare
    + * @vid_hdr: the volume identifier header of the second logical eraseblock
    + *
    + * This function compares versions of 2 copies of a LEB and informs which one
    + * is newer. In case of success this function returns a positive value, in case
    + * of error, a negative error code is returned. The success return codes use
    + * the following bits:
    + * o bit 0 is cleared: the first PEB (described by @seb) is newer then the
    + * second PEB (described by @pnum and @vid_hdr);
    + * o bit 0 is set: the second PEB is newer;
    + * o bit 1 is cleared: no bit-flips were detected in the newer PEB;
    + * o bit 1 is set: bit-flips were detected in the newer PEB;
    + * o bit 2 is cleared: the older PEB is not corrupted;
    + * o bit 2 is set: the older PEB is not corrupted.
    + */
    +static int compare_lebs(const struct ubi_info *ubi,
    + const struct ubi_scan_leb *seb, int pnum,
    + const struct ubi_vid_hdr *vid_hdr)
    +{
    + void *buf;
    + int len, err, second_is_newer, bitflips = 0, corrupted = 0;
    + uint32_t data_crc, crc;
    + long long abs, v1 = seb->leb_ver, v2 = ubi32_to_cpu(vid_hdr->leb_ver);
    + struct ubi_vid_hdr *vidh = NULL;
    +
    + /*
    + * UBI constantly increases the logical eraseblock version number and
    + * it can overflow. Thus, we have to bear in mind that versions that
    + * are close to %0xFFFFFFFF are less then versions that are close to
    + * %0.
    + *
    + * The UBI WL unit guarantees that the number of pending tasks is not
    + * greater then %0x7FFFFFFF. So, if the difference between any two
    + * versions is greater or equivalent to %0x7FFFFFFF, there was an
    + * overflow and the logical eraseblock with lower version is actually
    + * newer then the one with higher version.
    + */
    +
    + abs = v1 - v2;
    + if (abs < 0)
    + abs = -abs;
    +
    + if (likely(abs < 0x7FFFFFFF))
    + /* Non-overflow situation */
    + second_is_newer = (v2 > v1);
    + else
    + second_is_newer = (v2 < v1);
    +
    + /*
    + * Now we know which copy is newer. If the copy flag of the PEB with
    + * newer version is not set, then we just return, otherwise we have to
    + * check data CRC. For the second PEB we already have the VID header,
    + * for the first one - we'll need to re-read it from flash.
    + *
    + * FIXME: this may be optimized so that we wouldn't read twice.
    + */
    +
    + if (second_is_newer) {
    + if (!vid_hdr->copy_flag) {
    + /* It is not a copy, so it is newer */
    + dbg_scan("second PEB %d is newer, copy_flag is unset",
    + pnum);
    + return 1;
    + }
    + } else {
    + pnum = seb->pnum;
    +
    + vidh = ubi_zalloc_vid_hdr(ubi);
    + if (!vidh)
    + return -ENOMEM;
    +
    + err = ubi_io_read_vid_hdr(ubi, pnum, vidh, 0);
    + if (unlikely(err)) {
    + if (err == UBI_IO_BITFLIPS)
    + bitflips = 1;
    + else {
    + dbg_err("VID of PEB %d header is bad, but it "
    + "was OK earlier", pnum);
    + if (err > 0)
    + err = -EIO;
    +
    + goto out_free_vidh;
    + }
    + }
    +
    + if (!vidh->copy_flag) {
    + /* It is not a copy, so it is newer */
    + dbg_scan("first PEB %d is newer, copy_flag is unset",
    + pnum);
    + err = bitflips << 1;
    + goto out_free_vidh;
    + }
    +
    + vid_hdr = vidh;
    + }
    +
    + /* Read the data of the copy and check the CRC */
    +
    + len = ubi32_to_cpu(vid_hdr->data_size);
    + buf = ubi_kmalloc(len);
    + if (unlikely(!buf)) {
    + err = -ENOMEM;
    + goto out_free_vidh;
    + }
    +
    + err = ubi_io_read_data(ubi, buf, pnum, 0, len);
    + if (unlikely(err && err != UBI_IO_BITFLIPS))
    + goto out_free_buf;
    +
    + data_crc = ubi32_to_cpu(vid_hdr->data_crc);
    + crc = crc32(UBI_CRC32_INIT, buf, len);
    + if (unlikely(crc != data_crc)) {
    + dbg_scan("PEB %d CRC error: calculated %#08x, must be %#08x",
    + pnum, crc, data_crc);
    + corrupted = 1;
    + bitflips = 0;
    + second_is_newer = !second_is_newer;
    + } else {
    + dbg_scan("PEB %d CRC is OK", pnum);
    + bitflips = !!err;
    + }
    +
    + ubi_kfree(buf);
    + ubi_free_vid_hdr(ubi, vidh);
    +
    + if (second_is_newer)
    + dbg_scan("second PEB %d is newer, copy_flag is set", pnum);
    + else
    + dbg_scan("first PEB %d is newer, copy_flag is set", pnum);
    +
    + return second_is_newer | (bitflips << 1) | (corrupted << 2);
    +
    +out_free_buf:
    + ubi_kfree(buf);
    +out_free_vidh:
    + ubi_free_vid_hdr(ubi, vidh);
    + return err;
    +}
    +
    +/**
    + * add_to_erase - add a physical eraseblock to the list of physical eraseblocks
    + * which have to be erased.
    + *
    + * @si: a pointer to the scanning information
    + * @pnum: the physical eraseblock number
    + * @ec: erase counter of this physical eraseblock
    + *
    + * This function returns zero in case of success and a negative error code in
    + * case of failure.
    + */
    +static int add_to_erase(struct ubi_scan_info *si, int pnum, int ec)
    +{
    + struct ubi_scan_leb *seb;
    +
    + dbg_scan("PEB %d, EC %d", pnum, ec);
    +
    + seb = ubi_alloc_scan_leb();
    + if (unlikely(!seb))
    + return -ENOMEM;
    +
    + seb->pnum = pnum;
    + seb->ec = ec;
    + list_add_tail(&seb->u.list, &si->erase);
    + return 0;
    +}
    +
    +/**
    + * add_to_alien - add a physical eraseblock to the @si->alien list.
    + *
    + * @si: a pointer to the scanning information
    + * @pnum: the physical eraseblock number
    + *
    + * This function returns zero in case of success and a negative error
    + * code in case of failure.
    + */
    +static int add_to_alien(struct ubi_scan_info *si, int pnum)
    +{
    + struct ubi_scan_leb *seb;
    +
    + dbg_scan("PEB %d is alien", pnum);
    +
    + seb = ubi_alloc_scan_leb();
    + if (unlikely(!seb))
    + return -ENOMEM;
    +
    + seb->pnum = pnum;
    + list_add_tail(&seb->u.list, &si->alien);
    + return 0;
    +}
    +
    +/**
    + * add_to_free - add a physical eraseblock to the list of free physical
    + * eraseblocks.
    + *
    + * @si: a pointer to the scanning information
    + * @pnum: the physical eraseblock number
    + * @ec: erase counter of this physical eraseblock
    + *
    + * This function returns zero in case of success and a negative error code in
    + * case of failure.
    + */
    +static int add_to_free(struct ubi_scan_info *si, int pnum, int ec)
    +{
    + struct ubi_scan_leb *seb;
    +
    + dbg_scan("PEB %d, EC %d", pnum, ec);
    + ubi_assert(ec >= 0);
    +
    + seb = ubi_alloc_scan_leb();
    + if (unlikely(!seb))
    + return -ENOMEM;
    +
    + seb->pnum = pnum;
    + seb->ec = ec;
    + list_add_tail(&seb->u.list, &si->free);
    + return 0;
    +}
    +
    +/**
    + * destroy_sv - free the scanning volume information
    + *
    + * @sv: scanning volume information
    + *
    + * This function destroys the volume RB-tree (@sv->root) and the scanning
    + * volume information.
    + */
    +static void destroy_sv(struct ubi_scan_volume *sv)
    +{
    + struct ubi_scan_leb *seb;
    + struct rb_node *this = sv->root.rb_node;
    +
    + while (this) {
    + if (this->rb_left)
    + this = this->rb_left;
    + else if (this->rb_right)
    + this = this->rb_right;
    + else {
    + seb = rb_entry(this, struct ubi_scan_leb, u.rb);
    + this = rb_parent(this);
    + if (this) {
    + if (this->rb_left == &seb->u.rb)
    + this->rb_left = NULL;
    + else
    + this->rb_right = NULL;
    + }
    +
    + ubi_free_scan_leb(seb);
    + }
    + }
    + ubi_free_scan_volume(sv);
    +}
    +
    +/**
    + * commit_to_mean_value - commit intermediate results to the final mean erase
    + * counter value.
    + *
    + * @si: the scanning information
    + *
    + * This function is a helper function which calculates partial mean value and
    + * adds it to the resulting mean value. As we can work only in integer
    + * arithmetic and we want to calculate the mean value of erase counter
    + * accurately, we first sum erase counter values in @si->ec_sum variable and
    + * count these components in @si->ec_count. If this temporary @si->ec_sum is
    + * going to overflow, we calculate the partial mean value
    + * (@si->ec_sum/@si->ec_count) and add it to @si->mean_ec.
    + */
    +static void commit_to_mean_value(struct ubi_scan_info *si)
    +{
    + int rem;
    +
    + rem = si->ec_sum % si->ec_count;
    + si->ec_sum /= si->ec_count;
    + if (rem >= si->ec_count / 2)
    + si->mean_ec += 1;
    + si->mean_ec += si->ec_sum;
    +}
    +
    +/**
    + * vid_hdr_sanity_check - check that a volume identifier header is sane.
    + *
    + * @ubi: the UBI device description object
    + * @vid_hdr: the volume identifier header to check
    + * @sv: information about the volume this logical eraseblock belongs to
    + * @pnum: the physical eraseblock number the VID header came from
    + *
    + * This function checks that data stored in the volume identifier header
    + * @vid_hdr is consistent. This function returns non-zero if an inconsistency
    + * was found and zero if not.
    + *
    + * Note, UBI does sanity check of everything it reads from the flash media.
    + * Most of the checks are done in the I/O unit. Here we check that the
    + * information in this VID header is consistent to information in other VID
    + * headers of the same volume.
    + */
    +static int vid_hdr_sanity_check(const struct ubi_info *ubi,
    + const struct ubi_vid_hdr *vid_hdr,
    + const struct ubi_scan_volume *sv, int pnum)
    +{
    + int vol_type = vid_hdr->vol_type;
    + int vol_id = ubi32_to_cpu(vid_hdr->vol_id);
    + int used_ebs = ubi32_to_cpu(vid_hdr->used_ebs);
    + int data_pad = ubi32_to_cpu(vid_hdr->data_pad);
    +
    + if (sv->leb_count != 0) {
    + /*
    + * This is not the first logical eraseblock belonging to this
    + * volume. Ensure that the data in its VID header is consistent
    + * to the data in previous logical eraseblocks' headers.
    + */
    + int sv_vol_type;
    +
    + if (unlikely(vol_id != sv->vol_id)) {
    + dbg_err("inconsistent vol_id");
    + goto bad;
    + }
    +
    + if (sv->vol_type == UBI_STATIC_VOLUME)
    + sv_vol_type = UBI_VID_STATIC;
    + else
    + sv_vol_type = UBI_VID_DYNAMIC;
    +
    + if (unlikely(vol_type != sv_vol_type)) {
    + dbg_err("inconsistent vol_type");
    + goto bad;
    + }
    +
    + if (unlikely(used_ebs != sv->used_ebs)) {
    + dbg_err("inconsistent used_ebs");
    + goto bad;
    + }
    +
    + if (unlikely(data_pad != sv->data_pad)) {
    + dbg_err("inconsistent data_pad");
    + goto bad;
    + }
    + }
    +
    + return 0;
    +
    +bad:
    + ubi_err("bad VID header at PEB %d", pnum);
    + ubi_dbg_dump_vid_hdr(vid_hdr);
    + ubi_dbg_dump_sv(sv);
    + return -EINVAL;
    +}
    +
    +#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID_SCAN
    +
    +/**
    + * paranoid_check_si - check if the scanning information is sane and correct.
    + *
    + * @ubi: the UBI device description object
    + * @si: a pointer to the scanning information
    + *
    + * This function returns zero if the scanning information is all right, %1 if
    + * not and a negative error code if an error occurred.
    + */
    +static int paranoid_check_si(const struct ubi_info *ubi,
    + struct ubi_scan_info *si)
    +{
    + int pnum, err, vols_found = 0;
    + struct rb_node *rb1, *rb2;
    + struct ubi_scan_volume *sv;
    + struct ubi_scan_leb *seb, *last_seb;
    + const struct ubi_io_info *io = ubi->io;
    + uint8_t *buf;
    +
    + /*
    + * At first, check that scanning information is sane.
    + */
    + rb_for_each_entry(rb1, sv, &si->volumes, rb) {
    + int leb_count = 0;
    +
    + cond_resched();
    +
    + vols_found += 1;
    +
    + if (unlikely(si->is_empty)) {
    + ubi_err("bad is_empty flag");
    + goto bad_sv;
    + }
    +
    + if (unlikely(sv->vol_id < 0 || sv->highest_lnum < 0 ||
    + sv->leb_count < 0 || sv->vol_type < 0 ||
    + sv->used_ebs < 0 || sv->data_pad < 0 ||
    + sv->last_data_size < 0)) {
    + ubi_err("negative values");
    + goto bad_sv;
    + }
    +
    + if (unlikely(sv->vol_id >= UBI_MAX_VOLUMES &&
    + sv->vol_id < UBI_INTERNAL_VOL_START)) {
    + ubi_err("bad vol_id");
    + goto bad_sv;
    + }
    +
    + if (unlikely(sv->vol_id > si->highest_vol_id)) {
    + ubi_err("highest_vol_id is %d, but vol_id %d is there",
    + si->highest_vol_id, sv->vol_id);
    + goto out;
    + }
    +
    + if (unlikely(sv->vol_type != UBI_DYNAMIC_VOLUME &&
    + sv->vol_type != UBI_STATIC_VOLUME)) {
    + ubi_err("bad vol_type");
    + goto bad_sv;
    + }
    +
    + if (unlikely(sv->data_pad > io->leb_size / 2)) {
    + ubi_err("bad data_pad");
    + goto bad_sv;
    + }
    +
    + last_seb = NULL;
    + rb_for_each_entry(rb2, seb, &sv->root, u.rb) {
    + cond_resched();
    +
    + last_seb = seb;
    + leb_count += 1;
    +
    + if (unlikely(seb->pnum < 0 || seb->ec < 0)) {
    + ubi_err("negative values");
    + goto bad_seb;
    + }
    +
    + if (unlikely(seb->ec < si->min_ec)) {
    + ubi_err("bad si->min_ec (%d), %d found",
    + si->min_ec, seb->ec);
    + goto bad_seb;
    + }
    +
    + if (unlikely(seb->ec > si->max_ec)) {
    + ubi_err("bad si->max_ec (%d), %d found",
    + si->max_ec, seb->ec);
    + goto bad_seb;
    + }
    +
    + if (unlikely(seb->pnum >= io->peb_count)) {
    + ubi_err("too high PEB number %d, total PEBs %d",
    + seb->pnum, io->peb_count);
    + goto bad_seb;
    + }
    +
    + if (sv->vol_type == UBI_STATIC_VOLUME) {
    + if (unlikely(seb->lnum >= sv->used_ebs)) {
    + ubi_err("bad lnum or used_ebs");
    + goto bad_seb;
    + }
    + } else {
    + if (unlikely(sv->used_ebs != 0)) {
    + ubi_err("non-zero used_ebs");
    + goto bad_seb;
    + }
    + }
    +
    + if (unlikely(seb->lnum > sv->highest_lnum)) {
    + ubi_err("incorrect highest_lnum or lnum");
    + goto bad_seb;
    + }
    + }
    +
    + if (unlikely(sv->leb_count != leb_count)) {
    + ubi_err("bad leb_count, %d objects in the tree",
    + leb_count);
    + goto bad_sv;
    + }
    +
    + if (!last_seb)
    + continue;
    +
    + seb = last_seb;
    +
    + if (unlikely(seb->lnum != sv->highest_lnum)) {
    + ubi_err("bad highest_lnum");
    + goto bad_seb;
    + }
    + }
    +
    + if (vols_found != si->vols_found) {
    + ubi_err("bad si->vols_found %d, should be %d",
    + si->vols_found, vols_found);
    + goto out;
    + }
    +
    + /* Check that scanning information is correct */
    + rb_for_each_entry(rb1, sv, &si->volumes, rb) {
    + last_seb = NULL;
    + rb_for_each_entry(rb2, seb, &sv->root, u.rb) {
    + int vol_type;
    +
    + cond_resched();
    +
    + last_seb = seb;
    +
    + err = ubi_io_read_vid_hdr(ubi, seb->pnum, vidh, 1);
    + if (unlikely(err) && err != UBI_IO_BITFLIPS) {
    + ubi_err("VID header is not OK (%d)", err);
    + if (err > 0)
    + err = -EIO;
    + return err;
    + }
    +
    + vol_type = vidh->vol_type == UBI_VID_DYNAMIC ?
    + UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
    + if (unlikely(sv->vol_type != vol_type)) {
    + ubi_err("bad vol_type");
    + goto bad_vid_hdr;
    + }
    +
    + if (unlikely(seb->leb_ver !=
    + ubi32_to_cpu(vidh->leb_ver))) {
    + ubi_err("bad leb_ver %u", seb->leb_ver);
    + goto bad_vid_hdr;
    + }
    +
    + if (unlikely(sv->vol_id !=
    + ubi32_to_cpu(vidh->vol_id))) {
    + ubi_err("bad vol_id %d", sv->vol_id);
    + goto bad_vid_hdr;
    + }
    +
    + if (unlikely(sv->compat != vidh->compat)) {
    + ubi_err("bad compat %d", vidh->compat);
    + goto bad_vid_hdr;
    + }
    +
    + if (unlikely(seb->lnum !=
    + ubi32_to_cpu(vidh->lnum))) {
    + ubi_err("bad lnum %d", seb->lnum);
    + goto bad_vid_hdr;
    + }
    +
    + if (unlikely(sv->used_ebs !=
    + ubi32_to_cpu(vidh->used_ebs))) {
    + ubi_err("bad used_ebs %d", sv->used_ebs);
    + goto bad_vid_hdr;
    + }
    +
    + if (unlikely(sv->data_pad !=
    + ubi32_to_cpu(vidh->data_pad))) {
    + ubi_err("bad data_pad %d", sv->data_pad);
    + goto bad_vid_hdr;
    + }
    + }
    +
    + if (!last_seb)
    + continue;
    +
    + if (unlikely(sv->highest_lnum != ubi32_to_cpu(vidh->lnum))) {
    + ubi_err("bad highest_lnum %d", sv->highest_lnum);
    + goto bad_vid_hdr;
    + }
    +
    + if (unlikely(sv->last_data_size !=
    + ubi32_to_cpu(vidh->data_size))) {
    + ubi_err("bad last_data_size %d", sv->last_data_size);
    + goto bad_vid_hdr;
    + }
    + }
    +
    + /*
    + * Make sure that all the physical eraseblocks are in one of the lists
    + * or trees.
    + */
    + buf = ubi_kmalloc(io->peb_count);
    + if (!buf)
    + return -ENOMEM;
    +
    + memset(buf, 1, io->peb_count);
    + for (pnum = 0; pnum < io->peb_count; pnum++) {
    + err = ubi_io_is_bad(ubi, pnum);
    + if (unlikely(err < 0))
    + return err;
    + else if (err)
    + buf[pnum] = 0;
    + }
    +
    + rb_for_each_entry(rb1, sv, &si->volumes, rb)
    + rb_for_each_entry(rb2, seb, &sv->root, u.rb)
    + buf[seb->pnum] = 0;
    +
    + cond_resched();
    + list_for_each_entry(seb, &si->free, u.list)
    + buf[seb->pnum] = 0;
    +
    + cond_resched();
    + list_for_each_entry(seb, &si->corr, u.list)
    + buf[seb->pnum] = 0;
    +
    + cond_resched();
    + list_for_each_entry(seb, &si->erase, u.list)
    + buf[seb->pnum] = 0;
    +
    + cond_resched();
    + list_for_each_entry(seb, &si->alien, u.list)
    + buf[seb->pnum] = 0;
    +
    + err = 0;
    + for (pnum = 0; pnum < io->peb_count; pnum++)
    + if (unlikely(buf[pnum])) {
    + ubi_err("PEB %d is not referred", pnum);
    + err = 1;
    + }
    +
    + ubi_kfree(buf);
    + if (err)
    + goto out;
    + return 0;
    +
    +bad_seb:
    + ubi_err("bad scanning information about LEB %d", seb->lnum);
    + ubi_dbg_dump_seb(seb, 0);
    + ubi_dbg_dump_sv(sv);
    + goto out;
    +
    +bad_sv:
    + ubi_err("bad scanning information about volume %d", sv->vol_id);
    + ubi_dbg_dump_sv(sv);
    + goto out;
    +
    +bad_vid_hdr:
    + ubi_err("bad scanning information about volume %d", sv->vol_id);
    + ubi_dbg_dump_sv(sv);
    + ubi_dbg_dump_vid_hdr(vidh);
    +
    +out:
    + ubi_dbg_dump_stack();
    + return 1;
    +}
    +
    +#endif /* CONFIG_MTD_UBI_DEBUG_PARANOID_SCAN */
    -
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