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super.c

/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * 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., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/*
 * This file implements UBIFS initialization and VFS superblock operations. Some
 * initialization stuff which is rather large and complex is placed at
 * corresponding subsystems, but most of it is here.
 */

#include "ubifs.h"
#include <linux/math64.h>

#define INODE_LOCKED_MAX      64

struct super_block *ubifs_sb;
static struct inode *inodes_locked_down[INODE_LOCKED_MAX];

/* shrinker.c */

/* List of all UBIFS file-system instances */
struct list_head ubifs_infos;

/* linux/fs/super.c */

static int sb_set(struct super_block *sb, void *data)
{
      dev_t *dev = data;

      sb->s_dev = *dev;
      return 0;
}

/**
 *    sget  -     find or create a superblock
 *    @type:      filesystem type superblock should belong to
 *    @test:      comparison callback
 *    @set: setup callback
 *    @data:      argument to each of them
 */
struct super_block *sget(struct file_system_type *type,
                  int (*test)(struct super_block *,void *),
                  int (*set)(struct super_block *,void *),
                  void *data)
{
      struct super_block *s = NULL;
      int err;

      s = kzalloc(sizeof(struct super_block),  GFP_USER);
      if (!s) {
            err = -ENOMEM;
            return ERR_PTR(err);
      }

      INIT_LIST_HEAD(&s->s_instances);
      INIT_LIST_HEAD(&s->s_inodes);
      s->s_time_gran = 1000000000;

      err = set(s, data);
      if (err) {
            return ERR_PTR(err);
      }
      s->s_type = type;
      strncpy(s->s_id, type->name, sizeof(s->s_id));
      list_add(&s->s_instances, &type->fs_supers);
      return s;
}

/**
 * validate_inode - validate inode.
 * @c: UBIFS file-system description object
 * @inode: the inode to validate
 *
 * This is a helper function for 'ubifs_iget()' which validates various fields
 * of a newly built inode to make sure they contain sane values and prevent
 * possible vulnerabilities. Returns zero if the inode is all right and
 * a non-zero error code if not.
 */
static int validate_inode(struct ubifs_info *c, const struct inode *inode)
{
      int err;
      const struct ubifs_inode *ui = ubifs_inode(inode);

      if (inode->i_size > c->max_inode_sz) {
            ubifs_err("inode is too large (%lld)",
                    (long long)inode->i_size);
            return 1;
      }

      if (ui->compr_type < 0 || ui->compr_type >= UBIFS_COMPR_TYPES_CNT) {
            ubifs_err("unknown compression type %d", ui->compr_type);
            return 2;
      }

      if (ui->data_len < 0 || ui->data_len > UBIFS_MAX_INO_DATA)
            return 4;

      if (!ubifs_compr_present(ui->compr_type)) {
            ubifs_warn("inode %lu uses '%s' compression, but it was not "
                     "compiled in", inode->i_ino,
                     ubifs_compr_name(ui->compr_type));
      }

      err = dbg_check_dir_size(c, inode);
      return err;
}

struct inode *iget_locked(struct super_block *sb, unsigned long ino)
{
      struct inode *inode;

      inode = (struct inode *)malloc(sizeof(struct ubifs_inode));
      if (inode) {
            inode->i_ino = ino;
            inode->i_sb = sb;
            list_add(&inode->i_sb_list, &sb->s_inodes);
            inode->i_state = I_LOCK | I_NEW;
      }

      return inode;
}

int ubifs_iput(struct inode *inode)
{
      list_del_init(&inode->i_sb_list);

      free(inode);
      return 0;
}

/*
 * Lock (save) inode in inode array for readback after recovery
 */
void iput(struct inode *inode)
{
      int i;
      struct inode *ino;

      /*
       * Search end of list
       */
      for (i = 0; i < INODE_LOCKED_MAX; i++) {
            if (inodes_locked_down[i] == NULL)
                  break;
      }

      if (i >= INODE_LOCKED_MAX) {
            ubifs_err("Error, can't lock (save) more inodes while recovery!!!");
            return;
      }

      /*
       * Allocate and use new inode
       */
      ino = (struct inode *)malloc(sizeof(struct ubifs_inode));
      memcpy(ino, inode, sizeof(struct ubifs_inode));

      /*
       * Finally save inode in array
       */
      inodes_locked_down[i] = ino;
}

struct inode *ubifs_iget(struct super_block *sb, unsigned long inum)
{
      int err;
      union ubifs_key key;
      struct ubifs_ino_node *ino;
      struct ubifs_info *c = sb->s_fs_info;
      struct inode *inode;
      struct ubifs_inode *ui;
      int i;

      dbg_gen("inode %lu", inum);

      /*
       * U-Boot special handling of locked down inodes via recovery
       * e.g. ubifs_recover_size()
       */
      for (i = 0; i < INODE_LOCKED_MAX; i++) {
            /*
             * Exit on last entry (NULL), inode not found in list
             */
            if (inodes_locked_down[i] == NULL)
                  break;

            if (inodes_locked_down[i]->i_ino == inum) {
                  /*
                   * We found the locked down inode in our array,
                   * so just return this pointer instead of creating
                   * a new one.
                   */
                  return inodes_locked_down[i];
            }
      }

      inode = iget_locked(sb, inum);
      if (!inode)
            return ERR_PTR(-ENOMEM);
      if (!(inode->i_state & I_NEW))
            return inode;
      ui = ubifs_inode(inode);

      ino = kmalloc(UBIFS_MAX_INO_NODE_SZ, GFP_NOFS);
      if (!ino) {
            err = -ENOMEM;
            goto out;
      }

      ino_key_init(c, &key, inode->i_ino);

      err = ubifs_tnc_lookup(c, &key, ino);
      if (err)
            goto out_ino;

      inode->i_flags |= (S_NOCMTIME | S_NOATIME);
      inode->i_nlink = le32_to_cpu(ino->nlink);
      inode->i_uid   = le32_to_cpu(ino->uid);
      inode->i_gid   = le32_to_cpu(ino->gid);
      inode->i_atime.tv_sec  = (int64_t)le64_to_cpu(ino->atime_sec);
      inode->i_atime.tv_nsec = le32_to_cpu(ino->atime_nsec);
      inode->i_mtime.tv_sec  = (int64_t)le64_to_cpu(ino->mtime_sec);
      inode->i_mtime.tv_nsec = le32_to_cpu(ino->mtime_nsec);
      inode->i_ctime.tv_sec  = (int64_t)le64_to_cpu(ino->ctime_sec);
      inode->i_ctime.tv_nsec = le32_to_cpu(ino->ctime_nsec);
      inode->i_mode = le32_to_cpu(ino->mode);
      inode->i_size = le64_to_cpu(ino->size);

      ui->data_len    = le32_to_cpu(ino->data_len);
      ui->flags       = le32_to_cpu(ino->flags);
      ui->compr_type  = le16_to_cpu(ino->compr_type);
      ui->creat_sqnum = le64_to_cpu(ino->creat_sqnum);
      ui->synced_i_size = ui->ui_size = inode->i_size;

      err = validate_inode(c, inode);
      if (err)
            goto out_invalid;

      if ((inode->i_mode & S_IFMT) == S_IFLNK) {
            if (ui->data_len <= 0 || ui->data_len > UBIFS_MAX_INO_DATA) {
                  err = 12;
                  goto out_invalid;
            }
            ui->data = kmalloc(ui->data_len + 1, GFP_NOFS);
            if (!ui->data) {
                  err = -ENOMEM;
                  goto out_ino;
            }
            memcpy(ui->data, ino->data, ui->data_len);
            ((char *)ui->data)[ui->data_len] = '\0';
      }

      kfree(ino);
      inode->i_state &= ~(I_LOCK | I_NEW);
      return inode;

out_invalid:
      ubifs_err("inode %lu validation failed, error %d", inode->i_ino, err);
      dbg_dump_node(c, ino);
      dbg_dump_inode(c, inode);
      err = -EINVAL;
out_ino:
      kfree(ino);
out:
      ubifs_err("failed to read inode %lu, error %d", inode->i_ino, err);
      return ERR_PTR(err);
}

/**
 * init_constants_early - initialize UBIFS constants.
 * @c: UBIFS file-system description object
 *
 * This function initialize UBIFS constants which do not need the superblock to
 * be read. It also checks that the UBI volume satisfies basic UBIFS
 * requirements. Returns zero in case of success and a negative error code in
 * case of failure.
 */
static int init_constants_early(struct ubifs_info *c)
{
      if (c->vi.corrupted) {
            ubifs_warn("UBI volume is corrupted - read-only mode");
            c->ro_media = 1;
      }

      if (c->di.ro_mode) {
            ubifs_msg("read-only UBI device");
            c->ro_media = 1;
      }

      if (c->vi.vol_type == UBI_STATIC_VOLUME) {
            ubifs_msg("static UBI volume - read-only mode");
            c->ro_media = 1;
      }

      c->leb_cnt = c->vi.size;
      c->leb_size = c->vi.usable_leb_size;
      c->half_leb_size = c->leb_size / 2;
      c->min_io_size = c->di.min_io_size;
      c->min_io_shift = fls(c->min_io_size) - 1;

      if (c->leb_size < UBIFS_MIN_LEB_SZ) {
            ubifs_err("too small LEBs (%d bytes), min. is %d bytes",
                    c->leb_size, UBIFS_MIN_LEB_SZ);
            return -EINVAL;
      }

      if (c->leb_cnt < UBIFS_MIN_LEB_CNT) {
            ubifs_err("too few LEBs (%d), min. is %d",
                    c->leb_cnt, UBIFS_MIN_LEB_CNT);
            return -EINVAL;
      }

      if (!is_power_of_2(c->min_io_size)) {
            ubifs_err("bad min. I/O size %d", c->min_io_size);
            return -EINVAL;
      }

      /*
       * UBIFS aligns all node to 8-byte boundary, so to make function in
       * io.c simpler, assume minimum I/O unit size to be 8 bytes if it is
       * less than 8.
       */
      if (c->min_io_size < 8) {
            c->min_io_size = 8;
            c->min_io_shift = 3;
      }

      c->ref_node_alsz = ALIGN(UBIFS_REF_NODE_SZ, c->min_io_size);
      c->mst_node_alsz = ALIGN(UBIFS_MST_NODE_SZ, c->min_io_size);

      /*
       * Initialize node length ranges which are mostly needed for node
       * length validation.
       */
      c->ranges[UBIFS_PAD_NODE].len  = UBIFS_PAD_NODE_SZ;
      c->ranges[UBIFS_SB_NODE].len   = UBIFS_SB_NODE_SZ;
      c->ranges[UBIFS_MST_NODE].len  = UBIFS_MST_NODE_SZ;
      c->ranges[UBIFS_REF_NODE].len  = UBIFS_REF_NODE_SZ;
      c->ranges[UBIFS_TRUN_NODE].len = UBIFS_TRUN_NODE_SZ;
      c->ranges[UBIFS_CS_NODE].len   = UBIFS_CS_NODE_SZ;

      c->ranges[UBIFS_INO_NODE].min_len  = UBIFS_INO_NODE_SZ;
      c->ranges[UBIFS_INO_NODE].max_len  = UBIFS_MAX_INO_NODE_SZ;
      c->ranges[UBIFS_ORPH_NODE].min_len =
                        UBIFS_ORPH_NODE_SZ + sizeof(__le64);
      c->ranges[UBIFS_ORPH_NODE].max_len = c->leb_size;
      c->ranges[UBIFS_DENT_NODE].min_len = UBIFS_DENT_NODE_SZ;
      c->ranges[UBIFS_DENT_NODE].max_len = UBIFS_MAX_DENT_NODE_SZ;
      c->ranges[UBIFS_XENT_NODE].min_len = UBIFS_XENT_NODE_SZ;
      c->ranges[UBIFS_XENT_NODE].max_len = UBIFS_MAX_XENT_NODE_SZ;
      c->ranges[UBIFS_DATA_NODE].min_len = UBIFS_DATA_NODE_SZ;
      c->ranges[UBIFS_DATA_NODE].max_len = UBIFS_MAX_DATA_NODE_SZ;
      /*
       * Minimum indexing node size is amended later when superblock is
       * read and the key length is known.
       */
      c->ranges[UBIFS_IDX_NODE].min_len = UBIFS_IDX_NODE_SZ + UBIFS_BRANCH_SZ;
      /*
       * Maximum indexing node size is amended later when superblock is
       * read and the fanout is known.
       */
      c->ranges[UBIFS_IDX_NODE].max_len = INT_MAX;

      /*
       * Initialize dead and dark LEB space watermarks. See gc.c for comments
       * about these values.
       */
      c->dead_wm = ALIGN(MIN_WRITE_SZ, c->min_io_size);
      c->dark_wm = ALIGN(UBIFS_MAX_NODE_SZ, c->min_io_size);

      /*
       * Calculate how many bytes would be wasted at the end of LEB if it was
       * fully filled with data nodes of maximum size. This is used in
       * calculations when reporting free space.
       */
      c->leb_overhead = c->leb_size % UBIFS_MAX_DATA_NODE_SZ;

      return 0;
}

/*
 * init_constants_sb - initialize UBIFS constants.
 * @c: UBIFS file-system description object
 *
 * This is a helper function which initializes various UBIFS constants after
 * the superblock has been read. It also checks various UBIFS parameters and
 * makes sure they are all right. Returns zero in case of success and a
 * negative error code in case of failure.
 */
static int init_constants_sb(struct ubifs_info *c)
{
      int tmp, err;
      long long tmp64;

      c->main_bytes = (long long)c->main_lebs * c->leb_size;
      c->max_znode_sz = sizeof(struct ubifs_znode) +
                        c->fanout * sizeof(struct ubifs_zbranch);

      tmp = ubifs_idx_node_sz(c, 1);
      c->ranges[UBIFS_IDX_NODE].min_len = tmp;
      c->min_idx_node_sz = ALIGN(tmp, 8);

      tmp = ubifs_idx_node_sz(c, c->fanout);
      c->ranges[UBIFS_IDX_NODE].max_len = tmp;
      c->max_idx_node_sz = ALIGN(tmp, 8);

      /* Make sure LEB size is large enough to fit full commit */
      tmp = UBIFS_CS_NODE_SZ + UBIFS_REF_NODE_SZ * c->jhead_cnt;
      tmp = ALIGN(tmp, c->min_io_size);
      if (tmp > c->leb_size) {
            dbg_err("too small LEB size %d, at least %d needed",
                  c->leb_size, tmp);
            return -EINVAL;
      }

      /*
       * Make sure that the log is large enough to fit reference nodes for
       * all buds plus one reserved LEB.
       */
      tmp64 = c->max_bud_bytes + c->leb_size - 1;
      c->max_bud_cnt = div_u64(tmp64, c->leb_size);
      tmp = (c->ref_node_alsz * c->max_bud_cnt + c->leb_size - 1);
      tmp /= c->leb_size;
      tmp += 1;
      if (c->log_lebs < tmp) {
            dbg_err("too small log %d LEBs, required min. %d LEBs",
                  c->log_lebs, tmp);
            return -EINVAL;
      }

      /*
       * When budgeting we assume worst-case scenarios when the pages are not
       * be compressed and direntries are of the maximum size.
       *
       * Note, data, which may be stored in inodes is budgeted separately, so
       * it is not included into 'c->inode_budget'.
       */
      c->page_budget = UBIFS_MAX_DATA_NODE_SZ * UBIFS_BLOCKS_PER_PAGE;
      c->inode_budget = UBIFS_INO_NODE_SZ;
      c->dent_budget = UBIFS_MAX_DENT_NODE_SZ;

      /*
       * When the amount of flash space used by buds becomes
       * 'c->max_bud_bytes', UBIFS just blocks all writers and starts commit.
       * The writers are unblocked when the commit is finished. To avoid
       * writers to be blocked UBIFS initiates background commit in advance,
       * when number of bud bytes becomes above the limit defined below.
       */
      c->bg_bud_bytes = (c->max_bud_bytes * 13) >> 4;

      /*
       * Ensure minimum journal size. All the bytes in the journal heads are
       * considered to be used, when calculating the current journal usage.
       * Consequently, if the journal is too small, UBIFS will treat it as
       * always full.
       */
      tmp64 = (long long)(c->jhead_cnt + 1) * c->leb_size + 1;
      if (c->bg_bud_bytes < tmp64)
            c->bg_bud_bytes = tmp64;
      if (c->max_bud_bytes < tmp64 + c->leb_size)
            c->max_bud_bytes = tmp64 + c->leb_size;

      err = ubifs_calc_lpt_geom(c);
      if (err)
            return err;

      return 0;
}

/*
 * init_constants_master - initialize UBIFS constants.
 * @c: UBIFS file-system description object
 *
 * This is a helper function which initializes various UBIFS constants after
 * the master node has been read. It also checks various UBIFS parameters and
 * makes sure they are all right.
 */
static void init_constants_master(struct ubifs_info *c)
{
      long long tmp64;

      c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);

      /*
       * Calculate total amount of FS blocks. This number is not used
       * internally because it does not make much sense for UBIFS, but it is
       * necessary to report something for the 'statfs()' call.
       *
       * Subtract the LEB reserved for GC, the LEB which is reserved for
       * deletions, minimum LEBs for the index, and assume only one journal
       * head is available.
       */
      tmp64 = c->main_lebs - 1 - 1 - MIN_INDEX_LEBS - c->jhead_cnt + 1;
      tmp64 *= (long long)c->leb_size - c->leb_overhead;
      tmp64 = ubifs_reported_space(c, tmp64);
      c->block_cnt = tmp64 >> UBIFS_BLOCK_SHIFT;
}

/**
 * free_orphans - free orphans.
 * @c: UBIFS file-system description object
 */
static void free_orphans(struct ubifs_info *c)
{
      struct ubifs_orphan *orph;

      while (c->orph_dnext) {
            orph = c->orph_dnext;
            c->orph_dnext = orph->dnext;
            list_del(&orph->list);
            kfree(orph);
      }

      while (!list_empty(&c->orph_list)) {
            orph = list_entry(c->orph_list.next, struct ubifs_orphan, list);
            list_del(&orph->list);
            kfree(orph);
            dbg_err("orphan list not empty at unmount");
      }

      vfree(c->orph_buf);
      c->orph_buf = NULL;
}

/**
 * check_volume_empty - check if the UBI volume is empty.
 * @c: UBIFS file-system description object
 *
 * This function checks if the UBIFS volume is empty by looking if its LEBs are
 * mapped or not. The result of checking is stored in the @c->empty variable.
 * Returns zero in case of success and a negative error code in case of
 * failure.
 */
static int check_volume_empty(struct ubifs_info *c)
{
      int lnum, err;

      c->empty = 1;
      for (lnum = 0; lnum < c->leb_cnt; lnum++) {
            err = ubi_is_mapped(c->ubi, lnum);
            if (unlikely(err < 0))
                  return err;
            if (err == 1) {
                  c->empty = 0;
                  break;
            }

            cond_resched();
      }

      return 0;
}

/**
 * mount_ubifs - mount UBIFS file-system.
 * @c: UBIFS file-system description object
 *
 * This function mounts UBIFS file system. Returns zero in case of success and
 * a negative error code in case of failure.
 *
 * Note, the function does not de-allocate resources it it fails half way
 * through, and the caller has to do this instead.
 */
static int mount_ubifs(struct ubifs_info *c)
{
      struct super_block *sb = c->vfs_sb;
      int err, mounted_read_only = (sb->s_flags & MS_RDONLY);
      long long x;
      size_t sz;

      err = init_constants_early(c);
      if (err)
            return err;

      err = ubifs_debugging_init(c);
      if (err)
            return err;

      err = check_volume_empty(c);
      if (err)
            goto out_free;

      if (c->empty && (mounted_read_only || c->ro_media)) {
            /*
             * This UBI volume is empty, and read-only, or the file system
             * is mounted read-only - we cannot format it.
             */
            ubifs_err("can't format empty UBI volume: read-only %s",
                    c->ro_media ? "UBI volume" : "mount");
            err = -EROFS;
            goto out_free;
      }

      if (c->ro_media && !mounted_read_only) {
            ubifs_err("cannot mount read-write - read-only media");
            err = -EROFS;
            goto out_free;
      }

      /*
       * The requirement for the buffer is that it should fit indexing B-tree
       * height amount of integers. We assume the height if the TNC tree will
       * never exceed 64.
       */
      err = -ENOMEM;
      c->bottom_up_buf = kmalloc(BOTTOM_UP_HEIGHT * sizeof(int), GFP_KERNEL);
      if (!c->bottom_up_buf)
            goto out_free;

      c->sbuf = vmalloc(c->leb_size);
      if (!c->sbuf)
            goto out_free;

      /*
       * We have to check all CRCs, even for data nodes, when we mount the FS
       * (specifically, when we are replaying).
       */
      c->always_chk_crc = 1;

      err = ubifs_read_superblock(c);
      if (err)
            goto out_free;

      /*
       * Make sure the compressor which is set as default in the superblock
       * or overridden by mount options is actually compiled in.
       */
      if (!ubifs_compr_present(c->default_compr)) {
            ubifs_err("'compressor \"%s\" is not compiled in",
                    ubifs_compr_name(c->default_compr));
            goto out_free;
      }

      dbg_failure_mode_registration(c);

      err = init_constants_sb(c);
      if (err)
            goto out_free;

      sz = ALIGN(c->max_idx_node_sz, c->min_io_size);
      sz = ALIGN(sz + c->max_idx_node_sz, c->min_io_size);
      c->cbuf = kmalloc(sz, GFP_NOFS);
      if (!c->cbuf) {
            err = -ENOMEM;
            goto out_free;
      }

      sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num, c->vi.vol_id);

      err = ubifs_read_master(c);
      if (err)
            goto out_master;

      init_constants_master(c);

      if ((c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY)) != 0) {
            ubifs_msg("recovery needed");
            c->need_recovery = 1;
      }

      err = ubifs_lpt_init(c, 1, !mounted_read_only);
      if (err)
            goto out_lpt;

      err = dbg_check_idx_size(c, c->old_idx_sz);
      if (err)
            goto out_lpt;

      err = ubifs_replay_journal(c);
      if (err)
            goto out_journal;

      err = ubifs_mount_orphans(c, c->need_recovery, mounted_read_only);
      if (err)
            goto out_orphans;

      if (c->need_recovery) {
            err = ubifs_recover_size(c);
            if (err)
                  goto out_orphans;
      }

      spin_lock(&ubifs_infos_lock);
      list_add_tail(&c->infos_list, &ubifs_infos);
      spin_unlock(&ubifs_infos_lock);

      if (c->need_recovery) {
            if (mounted_read_only)
                  ubifs_msg("recovery deferred");
            else {
                  c->need_recovery = 0;
                  ubifs_msg("recovery completed");
            }
      }

      err = dbg_check_filesystem(c);
      if (err)
            goto out_infos;

      c->always_chk_crc = 0;

      ubifs_msg("mounted UBI device %d, volume %d, name \"%s\"",
              c->vi.ubi_num, c->vi.vol_id, c->vi.name);
      if (mounted_read_only)
            ubifs_msg("mounted read-only");
      x = (long long)c->main_lebs * c->leb_size;
      ubifs_msg("file system size:   %lld bytes (%lld KiB, %lld MiB, %d "
              "LEBs)", x, x >> 10, x >> 20, c->main_lebs);
      x = (long long)c->log_lebs * c->leb_size + c->max_bud_bytes;
      ubifs_msg("journal size:       %lld bytes (%lld KiB, %lld MiB, %d "
              "LEBs)", x, x >> 10, x >> 20, c->log_lebs + c->max_bud_cnt);
      ubifs_msg("media format:       w%d/r%d (latest is w%d/r%d)",
              c->fmt_version, c->ro_compat_version,
              UBIFS_FORMAT_VERSION, UBIFS_RO_COMPAT_VERSION);
      ubifs_msg("default compressor: %s", ubifs_compr_name(c->default_compr));
      ubifs_msg("reserved for root:  %llu bytes (%llu KiB)",
            c->report_rp_size, c->report_rp_size >> 10);

      dbg_msg("compiled on:         " __DATE__ " at " __TIME__);
      dbg_msg("min. I/O unit size:  %d bytes", c->min_io_size);
      dbg_msg("LEB size:            %d bytes (%d KiB)",
            c->leb_size, c->leb_size >> 10);
      dbg_msg("data journal heads:  %d",
            c->jhead_cnt - NONDATA_JHEADS_CNT);
      dbg_msg("UUID:                %02X%02X%02X%02X-%02X%02X"
             "-%02X%02X-%02X%02X-%02X%02X%02X%02X%02X%02X",
             c->uuid[0], c->uuid[1], c->uuid[2], c->uuid[3],
             c->uuid[4], c->uuid[5], c->uuid[6], c->uuid[7],
             c->uuid[8], c->uuid[9], c->uuid[10], c->uuid[11],
             c->uuid[12], c->uuid[13], c->uuid[14], c->uuid[15]);
      dbg_msg("big_lpt              %d", c->big_lpt);
      dbg_msg("log LEBs:            %d (%d - %d)",
            c->log_lebs, UBIFS_LOG_LNUM, c->log_last);
      dbg_msg("LPT area LEBs:       %d (%d - %d)",
            c->lpt_lebs, c->lpt_first, c->lpt_last);
      dbg_msg("orphan area LEBs:    %d (%d - %d)",
            c->orph_lebs, c->orph_first, c->orph_last);
      dbg_msg("main area LEBs:      %d (%d - %d)",
            c->main_lebs, c->main_first, c->leb_cnt - 1);
      dbg_msg("index LEBs:          %d", c->lst.idx_lebs);
      dbg_msg("total index bytes:   %lld (%lld KiB, %lld MiB)",
            c->old_idx_sz, c->old_idx_sz >> 10, c->old_idx_sz >> 20);
      dbg_msg("key hash type:       %d", c->key_hash_type);
      dbg_msg("tree fanout:         %d", c->fanout);
      dbg_msg("reserved GC LEB:     %d", c->gc_lnum);
      dbg_msg("first main LEB:      %d", c->main_first);
      dbg_msg("max. znode size      %d", c->max_znode_sz);
      dbg_msg("max. index node size %d", c->max_idx_node_sz);
      dbg_msg("node sizes:          data %zu, inode %zu, dentry %zu",
            UBIFS_DATA_NODE_SZ, UBIFS_INO_NODE_SZ, UBIFS_DENT_NODE_SZ);
      dbg_msg("node sizes:          trun %zu, sb %zu, master %zu",
            UBIFS_TRUN_NODE_SZ, UBIFS_SB_NODE_SZ, UBIFS_MST_NODE_SZ);
      dbg_msg("node sizes:          ref %zu, cmt. start %zu, orph %zu",
            UBIFS_REF_NODE_SZ, UBIFS_CS_NODE_SZ, UBIFS_ORPH_NODE_SZ);
      dbg_msg("max. node sizes:     data %zu, inode %zu dentry %zu",
              UBIFS_MAX_DATA_NODE_SZ, UBIFS_MAX_INO_NODE_SZ,
            UBIFS_MAX_DENT_NODE_SZ);
      dbg_msg("dead watermark:      %d", c->dead_wm);
      dbg_msg("dark watermark:      %d", c->dark_wm);
      dbg_msg("LEB overhead:        %d", c->leb_overhead);
      x = (long long)c->main_lebs * c->dark_wm;
      dbg_msg("max. dark space:     %lld (%lld KiB, %lld MiB)",
            x, x >> 10, x >> 20);
      dbg_msg("maximum bud bytes:   %lld (%lld KiB, %lld MiB)",
            c->max_bud_bytes, c->max_bud_bytes >> 10,
            c->max_bud_bytes >> 20);
      dbg_msg("BG commit bud bytes: %lld (%lld KiB, %lld MiB)",
            c->bg_bud_bytes, c->bg_bud_bytes >> 10,
            c->bg_bud_bytes >> 20);
      dbg_msg("current bud bytes    %lld (%lld KiB, %lld MiB)",
            c->bud_bytes, c->bud_bytes >> 10, c->bud_bytes >> 20);
      dbg_msg("max. seq. number:    %llu", c->max_sqnum);
      dbg_msg("commit number:       %llu", c->cmt_no);

      return 0;

out_infos:
      spin_lock(&ubifs_infos_lock);
      list_del(&c->infos_list);
      spin_unlock(&ubifs_infos_lock);
out_orphans:
      free_orphans(c);
out_journal:
out_lpt:
      ubifs_lpt_free(c, 0);
out_master:
      kfree(c->mst_node);
      kfree(c->rcvrd_mst_node);
      if (c->bgt)
            kthread_stop(c->bgt);
      kfree(c->cbuf);
out_free:
      vfree(c->ileb_buf);
      vfree(c->sbuf);
      kfree(c->bottom_up_buf);
      ubifs_debugging_exit(c);
      return err;
}

/**
 * ubifs_umount - un-mount UBIFS file-system.
 * @c: UBIFS file-system description object
 *
 * Note, this function is called to free allocated resourced when un-mounting,
 * as well as free resources when an error occurred while we were half way
 * through mounting (error path cleanup function). So it has to make sure the
 * resource was actually allocated before freeing it.
 */
static void ubifs_umount(struct ubifs_info *c)
{
      dbg_gen("un-mounting UBI device %d, volume %d", c->vi.ubi_num,
            c->vi.vol_id);

      spin_lock(&ubifs_infos_lock);
      list_del(&c->infos_list);
      spin_unlock(&ubifs_infos_lock);

      if (c->bgt)
            kthread_stop(c->bgt);

      free_orphans(c);
      ubifs_lpt_free(c, 0);

      kfree(c->cbuf);
      kfree(c->rcvrd_mst_node);
      kfree(c->mst_node);
      vfree(c->ileb_buf);
      vfree(c->sbuf);
      kfree(c->bottom_up_buf);
      ubifs_debugging_exit(c);

      /* Finally free U-Boot's global copy of superblock */
      free(ubifs_sb->s_fs_info);
      free(ubifs_sb);
}

/**
 * open_ubi - parse UBI device name string and open the UBI device.
 * @name: UBI volume name
 * @mode: UBI volume open mode
 *
 * There are several ways to specify UBI volumes when mounting UBIFS:
 * o ubiX_Y    - UBI device number X, volume Y;
 * o ubiY      - UBI device number 0, volume Y;
 * o ubiX:NAME - mount UBI device X, volume with name NAME;
 * o ubi:NAME  - mount UBI device 0, volume with name NAME.
 *
 * Alternative '!' separator may be used instead of ':' (because some shells
 * like busybox may interpret ':' as an NFS host name separator). This function
 * returns ubi volume object in case of success and a negative error code in
 * case of failure.
 */
static struct ubi_volume_desc *open_ubi(const char *name, int mode)
{
      int dev, vol;
      char *endptr;

      if (name[0] != 'u' || name[1] != 'b' || name[2] != 'i')
            return ERR_PTR(-EINVAL);

      /* ubi:NAME method */
      if ((name[3] == ':' || name[3] == '!') && name[4] != '\0')
            return ubi_open_volume_nm(0, name + 4, mode);

      if (!isdigit(name[3]))
            return ERR_PTR(-EINVAL);

      dev = simple_strtoul(name + 3, &endptr, 0);

      /* ubiY method */
      if (*endptr == '\0')
            return ubi_open_volume(0, dev, mode);

      /* ubiX_Y method */
      if (*endptr == '_' && isdigit(endptr[1])) {
            vol = simple_strtoul(endptr + 1, &endptr, 0);
            if (*endptr != '\0')
                  return ERR_PTR(-EINVAL);
            return ubi_open_volume(dev, vol, mode);
      }

      /* ubiX:NAME method */
      if ((*endptr == ':' || *endptr == '!') && endptr[1] != '\0')
            return ubi_open_volume_nm(dev, ++endptr, mode);

      return ERR_PTR(-EINVAL);
}

static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
{
      struct ubi_volume_desc *ubi = sb->s_fs_info;
      struct ubifs_info *c;
      struct inode *root;
      int err;

      c = kzalloc(sizeof(struct ubifs_info), GFP_KERNEL);
      if (!c)
            return -ENOMEM;

      spin_lock_init(&c->cnt_lock);
      spin_lock_init(&c->cs_lock);
      spin_lock_init(&c->buds_lock);
      spin_lock_init(&c->space_lock);
      spin_lock_init(&c->orphan_lock);
      init_rwsem(&c->commit_sem);
      mutex_init(&c->lp_mutex);
      mutex_init(&c->tnc_mutex);
      mutex_init(&c->log_mutex);
      mutex_init(&c->mst_mutex);
      mutex_init(&c->umount_mutex);
      init_waitqueue_head(&c->cmt_wq);
      c->buds = RB_ROOT;
      c->old_idx = RB_ROOT;
      c->size_tree = RB_ROOT;
      c->orph_tree = RB_ROOT;
      INIT_LIST_HEAD(&c->infos_list);
      INIT_LIST_HEAD(&c->idx_gc);
      INIT_LIST_HEAD(&c->replay_list);
      INIT_LIST_HEAD(&c->replay_buds);
      INIT_LIST_HEAD(&c->uncat_list);
      INIT_LIST_HEAD(&c->empty_list);
      INIT_LIST_HEAD(&c->freeable_list);
      INIT_LIST_HEAD(&c->frdi_idx_list);
      INIT_LIST_HEAD(&c->unclean_leb_list);
      INIT_LIST_HEAD(&c->old_buds);
      INIT_LIST_HEAD(&c->orph_list);
      INIT_LIST_HEAD(&c->orph_new);

      c->highest_inum = UBIFS_FIRST_INO;
      c->lhead_lnum = c->ltail_lnum = UBIFS_LOG_LNUM;

      ubi_get_volume_info(ubi, &c->vi);
      ubi_get_device_info(c->vi.ubi_num, &c->di);

      /* Re-open the UBI device in read-write mode */
      c->ubi = ubi_open_volume(c->vi.ubi_num, c->vi.vol_id, UBI_READONLY);
      if (IS_ERR(c->ubi)) {
            err = PTR_ERR(c->ubi);
            goto out_free;
      }

      c->vfs_sb = sb;

      sb->s_fs_info = c;
      sb->s_magic = UBIFS_SUPER_MAGIC;
      sb->s_blocksize = UBIFS_BLOCK_SIZE;
      sb->s_blocksize_bits = UBIFS_BLOCK_SHIFT;
      sb->s_dev = c->vi.cdev;
      sb->s_maxbytes = c->max_inode_sz = key_max_inode_size(c);
      if (c->max_inode_sz > MAX_LFS_FILESIZE)
            sb->s_maxbytes = c->max_inode_sz = MAX_LFS_FILESIZE;

      if (c->rw_incompat) {
            ubifs_err("the file-system is not R/W-compatible");
            ubifs_msg("on-flash format version is w%d/r%d, but software "
                    "only supports up to version w%d/r%d", c->fmt_version,
                    c->ro_compat_version, UBIFS_FORMAT_VERSION,
                    UBIFS_RO_COMPAT_VERSION);
            return -EROFS;
      }

      mutex_lock(&c->umount_mutex);
      err = mount_ubifs(c);
      if (err) {
            ubifs_assert(err < 0);
            goto out_unlock;
      }

      /* Read the root inode */
      root = ubifs_iget(sb, UBIFS_ROOT_INO);
      if (IS_ERR(root)) {
            err = PTR_ERR(root);
            goto out_umount;
      }

      sb->s_root = NULL;

      mutex_unlock(&c->umount_mutex);
      return 0;

out_umount:
      ubifs_umount(c);
out_unlock:
      mutex_unlock(&c->umount_mutex);
      ubi_close_volume(c->ubi);
out_free:
      kfree(c);
      return err;
}

static int sb_test(struct super_block *sb, void *data)
{
      dev_t *dev = data;

      return sb->s_dev == *dev;
}

static int ubifs_get_sb(struct file_system_type *fs_type, int flags,
                  const char *name, void *data, struct vfsmount *mnt)
{
      struct ubi_volume_desc *ubi;
      struct ubi_volume_info vi;
      struct super_block *sb;
      int err;

      dbg_gen("name %s, flags %#x", name, flags);

      /*
       * Get UBI device number and volume ID. Mount it read-only so far
       * because this might be a new mount point, and UBI allows only one
       * read-write user at a time.
       */
      ubi = open_ubi(name, UBI_READONLY);
      if (IS_ERR(ubi)) {
            ubifs_err("cannot open \"%s\", error %d",
                    name, (int)PTR_ERR(ubi));
            return PTR_ERR(ubi);
      }
      ubi_get_volume_info(ubi, &vi);

      dbg_gen("opened ubi%d_%d", vi.ubi_num, vi.vol_id);

      sb = sget(fs_type, &sb_test, &sb_set, &vi.cdev);
      if (IS_ERR(sb)) {
            err = PTR_ERR(sb);
            goto out_close;
      }

      if (sb->s_root) {
            /* A new mount point for already mounted UBIFS */
            dbg_gen("this ubi volume is already mounted");
            if ((flags ^ sb->s_flags) & MS_RDONLY) {
                  err = -EBUSY;
                  goto out_deact;
            }
      } else {
            sb->s_flags = flags;
            /*
             * Pass 'ubi' to 'fill_super()' in sb->s_fs_info where it is
             * replaced by 'c'.
             */
            sb->s_fs_info = ubi;
            err = ubifs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
            if (err)
                  goto out_deact;
            /* We do not support atime */
            sb->s_flags |= MS_ACTIVE | MS_NOATIME;
      }

      /* 'fill_super()' opens ubi again so we must close it here */
      ubi_close_volume(ubi);

      ubifs_sb = sb;
      return 0;

out_deact:
      up_write(&sb->s_umount);
out_close:
      ubi_close_volume(ubi);
      return err;
}

int __init ubifs_init(void)
{
      int err;

      BUILD_BUG_ON(sizeof(struct ubifs_ch) != 24);

      /* Make sure node sizes are 8-byte aligned */
      BUILD_BUG_ON(UBIFS_CH_SZ        & 7);
      BUILD_BUG_ON(UBIFS_INO_NODE_SZ  & 7);
      BUILD_BUG_ON(UBIFS_DENT_NODE_SZ & 7);
      BUILD_BUG_ON(UBIFS_XENT_NODE_SZ & 7);
      BUILD_BUG_ON(UBIFS_DATA_NODE_SZ & 7);
      BUILD_BUG_ON(UBIFS_TRUN_NODE_SZ & 7);
      BUILD_BUG_ON(UBIFS_SB_NODE_SZ   & 7);
      BUILD_BUG_ON(UBIFS_MST_NODE_SZ  & 7);
      BUILD_BUG_ON(UBIFS_REF_NODE_SZ  & 7);
      BUILD_BUG_ON(UBIFS_CS_NODE_SZ   & 7);
      BUILD_BUG_ON(UBIFS_ORPH_NODE_SZ & 7);

      BUILD_BUG_ON(UBIFS_MAX_DENT_NODE_SZ & 7);
      BUILD_BUG_ON(UBIFS_MAX_XENT_NODE_SZ & 7);
      BUILD_BUG_ON(UBIFS_MAX_DATA_NODE_SZ & 7);
      BUILD_BUG_ON(UBIFS_MAX_INO_NODE_SZ  & 7);
      BUILD_BUG_ON(UBIFS_MAX_NODE_SZ      & 7);
      BUILD_BUG_ON(MIN_WRITE_SZ           & 7);

      /* Check min. node size */
      BUILD_BUG_ON(UBIFS_INO_NODE_SZ  < MIN_WRITE_SZ);
      BUILD_BUG_ON(UBIFS_DENT_NODE_SZ < MIN_WRITE_SZ);
      BUILD_BUG_ON(UBIFS_XENT_NODE_SZ < MIN_WRITE_SZ);
      BUILD_BUG_ON(UBIFS_TRUN_NODE_SZ < MIN_WRITE_SZ);

      BUILD_BUG_ON(UBIFS_MAX_DENT_NODE_SZ > UBIFS_MAX_NODE_SZ);
      BUILD_BUG_ON(UBIFS_MAX_XENT_NODE_SZ > UBIFS_MAX_NODE_SZ);
      BUILD_BUG_ON(UBIFS_MAX_DATA_NODE_SZ > UBIFS_MAX_NODE_SZ);
      BUILD_BUG_ON(UBIFS_MAX_INO_NODE_SZ  > UBIFS_MAX_NODE_SZ);

      /* Defined node sizes */
      BUILD_BUG_ON(UBIFS_SB_NODE_SZ  != 4096);
      BUILD_BUG_ON(UBIFS_MST_NODE_SZ != 512);
      BUILD_BUG_ON(UBIFS_INO_NODE_SZ != 160);
      BUILD_BUG_ON(UBIFS_REF_NODE_SZ != 64);

      /*
       * We use 2 bit wide bit-fields to store compression type, which should
       * be amended if more compressors are added. The bit-fields are:
       * @compr_type in 'struct ubifs_inode', @default_compr in
       * 'struct ubifs_info' and @compr_type in 'struct ubifs_mount_opts'.
       */
      BUILD_BUG_ON(UBIFS_COMPR_TYPES_CNT > 4);

      /*
       * We require that PAGE_CACHE_SIZE is greater-than-or-equal-to
       * UBIFS_BLOCK_SIZE. It is assumed that both are powers of 2.
       */
      if (PAGE_CACHE_SIZE < UBIFS_BLOCK_SIZE) {
            ubifs_err("VFS page cache size is %u bytes, but UBIFS requires"
                    " at least 4096 bytes",
                    (unsigned int)PAGE_CACHE_SIZE);
            return -EINVAL;
      }

      err = -ENOMEM;

      err = ubifs_compressors_init();
      if (err)
            goto out_shrinker;

      return 0;

out_shrinker:
      return err;
}

/*
 * ubifsmount...
 */

static struct file_system_type ubifs_fs_type = {
      .name    = "ubifs",
      .owner   = THIS_MODULE,
      .get_sb  = ubifs_get_sb,
};

int ubifs_mount(char *vol_name)
{
      int flags;
      char name[80] = "ubi:";
      void *data;
      struct vfsmount *mnt;
      int ret;
      struct ubifs_info *c;

      /*
       * First unmount if allready mounted
       */
      if (ubifs_sb)
            ubifs_umount(ubifs_sb->s_fs_info);

      INIT_LIST_HEAD(&ubifs_infos);
      INIT_LIST_HEAD(&ubifs_fs_type.fs_supers);

      /*
       * Mount in read-only mode
       */
      flags = MS_RDONLY;
      strcat(name, vol_name);
      data = NULL;
      mnt = NULL;
      ret = ubifs_get_sb(&ubifs_fs_type, flags, name, data, mnt);
      if (ret) {
            printf("Error reading superblock on volume '%s'!\n", name);
            return -1;
      }

      c = ubifs_sb->s_fs_info;
      ubi_close_volume(c->ubi);

      return 0;
}

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