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linuxvfs.c

/*
 * linux/fs/befs/linuxvfs.c
 *
 * Copyright (C) 2001 Will Dyson <will_dyson@pobox.com
 *
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/nls.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>
#include <linux/parser.h>
#include <linux/namei.h>

#include "befs.h"
#include "btree.h"
#include "inode.h"
#include "datastream.h"
#include "super.h"
#include "io.h"

MODULE_DESCRIPTION("BeOS File System (BeFS) driver");
MODULE_AUTHOR("Will Dyson");
MODULE_LICENSE("GPL");

/* The units the vfs expects inode->i_blocks to be in */
#define VFS_BLOCK_SIZE 512

static int befs_readdir(struct file *, void *, filldir_t);
static int befs_get_block(struct inode *, sector_t, struct buffer_head *, int);
static int befs_readpage(struct file *file, struct page *page);
static sector_t befs_bmap(struct address_space *mapping, sector_t block);
static struct dentry *befs_lookup(struct inode *, struct dentry *, struct nameidata *);
static void befs_read_inode(struct inode *ino);
static struct inode *befs_alloc_inode(struct super_block *sb);
static void befs_destroy_inode(struct inode *inode);
static int befs_init_inodecache(void);
static void befs_destroy_inodecache(void);
static void *befs_follow_link(struct dentry *, struct nameidata *);
static void befs_put_link(struct dentry *, struct nameidata *, void *);
static int befs_utf2nls(struct super_block *sb, const char *in, int in_len,
                  char **out, int *out_len);
static int befs_nls2utf(struct super_block *sb, const char *in, int in_len,
                  char **out, int *out_len);
static void befs_put_super(struct super_block *);
static int befs_remount(struct super_block *, int *, char *);
static int befs_statfs(struct dentry *, struct kstatfs *);
static int parse_options(char *, befs_mount_options *);

static const struct super_operations befs_sops = {
      .read_inode = befs_read_inode,      /* initialize & read inode */
      .alloc_inode      = befs_alloc_inode,     /* allocate a new inode */
      .destroy_inode    = befs_destroy_inode, /* deallocate an inode */
      .put_super  = befs_put_super, /* uninit super */
      .statfs           = befs_statfs,    /* statfs */
      .remount_fs = befs_remount,
};

/* slab cache for befs_inode_info objects */
static struct kmem_cache *befs_inode_cachep;

static const struct file_operations befs_dir_operations = {
      .read       = generic_read_dir,
      .readdir    = befs_readdir,
};

static const struct inode_operations befs_dir_inode_operations = {
      .lookup           = befs_lookup,
};

static const struct address_space_operations befs_aops = {
      .readpage   = befs_readpage,
      .sync_page  = block_sync_page,
      .bmap       = befs_bmap,
};

static const struct inode_operations befs_symlink_inode_operations = {
      .readlink   = generic_readlink,
      .follow_link      = befs_follow_link,
      .put_link   = befs_put_link,
};

/* 
 * Called by generic_file_read() to read a page of data
 * 
 * In turn, simply calls a generic block read function and
 * passes it the address of befs_get_block, for mapping file
 * positions to disk blocks.
 */
static int
befs_readpage(struct file *file, struct page *page)
{
      return block_read_full_page(page, befs_get_block);
}

static sector_t
befs_bmap(struct address_space *mapping, sector_t block)
{
      return generic_block_bmap(mapping, block, befs_get_block);
}

/* 
 * Generic function to map a file position (block) to a 
 * disk offset (passed back in bh_result).
 *
 * Used by many higher level functions.
 *
 * Calls befs_fblock2brun() in datastream.c to do the real work.
 *
 * -WD 10-26-01
 */

static int
befs_get_block(struct inode *inode, sector_t block,
             struct buffer_head *bh_result, int create)
{
      struct super_block *sb = inode->i_sb;
      befs_data_stream *ds = &BEFS_I(inode)->i_data.ds;
      befs_block_run run = BAD_IADDR;
      int res = 0;
      ulong disk_off;

      befs_debug(sb, "---> befs_get_block() for inode %lu, block %ld",
               inode->i_ino, block);

      if (block < 0) {
            befs_error(sb, "befs_get_block() was asked for a block "
                     "number less than zero: block %ld in inode %lu",
                     block, inode->i_ino);
            return -EIO;
      }

      if (create) {
            befs_error(sb, "befs_get_block() was asked to write to "
                     "block %ld in inode %lu", block, inode->i_ino);
            return -EPERM;
      }

      res = befs_fblock2brun(sb, ds, block, &run);
      if (res != BEFS_OK) {
            befs_error(sb,
                     "<--- befs_get_block() for inode %lu, block "
                     "%ld ERROR", inode->i_ino, block);
            return -EFBIG;
      }

      disk_off = (ulong) iaddr2blockno(sb, &run);

      map_bh(bh_result, inode->i_sb, disk_off);

      befs_debug(sb, "<--- befs_get_block() for inode %lu, block %ld, "
               "disk address %lu", inode->i_ino, block, disk_off);

      return 0;
}

static struct dentry *
befs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
      struct inode *inode = NULL;
      struct super_block *sb = dir->i_sb;
      befs_data_stream *ds = &BEFS_I(dir)->i_data.ds;
      befs_off_t offset;
      int ret;
      int utfnamelen;
      char *utfname;
      const char *name = dentry->d_name.name;

      befs_debug(sb, "---> befs_lookup() "
               "name %s inode %ld", dentry->d_name.name, dir->i_ino);

      /* Convert to UTF-8 */
      if (BEFS_SB(sb)->nls) {
            ret =
                befs_nls2utf(sb, name, strlen(name), &utfname, &utfnamelen);
            if (ret < 0) {
                  befs_debug(sb, "<--- befs_lookup() ERROR");
                  return ERR_PTR(ret);
            }
            ret = befs_btree_find(sb, ds, utfname, &offset);
            kfree(utfname);

      } else {
            ret = befs_btree_find(sb, ds, dentry->d_name.name, &offset);
      }

      if (ret == BEFS_BT_NOT_FOUND) {
            befs_debug(sb, "<--- befs_lookup() %s not found",
                     dentry->d_name.name);
            return ERR_PTR(-ENOENT);

      } else if (ret != BEFS_OK || offset == 0) {
            befs_warning(sb, "<--- befs_lookup() Error");
            return ERR_PTR(-ENODATA);
      }

      inode = iget(dir->i_sb, (ino_t) offset);
      if (!inode)
            return ERR_PTR(-EACCES);

      d_add(dentry, inode);

      befs_debug(sb, "<--- befs_lookup()");

      return NULL;
}

static int
befs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
      struct inode *inode = filp->f_path.dentry->d_inode;
      struct super_block *sb = inode->i_sb;
      befs_data_stream *ds = &BEFS_I(inode)->i_data.ds;
      befs_off_t value;
      int result;
      size_t keysize;
      unsigned char d_type;
      char keybuf[BEFS_NAME_LEN + 1];
      char *nlsname;
      int nlsnamelen;
      const char *dirname = filp->f_path.dentry->d_name.name;

      befs_debug(sb, "---> befs_readdir() "
               "name %s, inode %ld, filp->f_pos %Ld",
               dirname, inode->i_ino, filp->f_pos);

      result = befs_btree_read(sb, ds, filp->f_pos, BEFS_NAME_LEN + 1,
                         keybuf, &keysize, &value);

      if (result == BEFS_ERR) {
            befs_debug(sb, "<--- befs_readdir() ERROR");
            befs_error(sb, "IO error reading %s (inode %lu)",
                     dirname, inode->i_ino);
            return -EIO;

      } else if (result == BEFS_BT_END) {
            befs_debug(sb, "<--- befs_readdir() END");
            return 0;

      } else if (result == BEFS_BT_EMPTY) {
            befs_debug(sb, "<--- befs_readdir() Empty directory");
            return 0;
      }

      d_type = DT_UNKNOWN;

      /* Convert to NLS */
      if (BEFS_SB(sb)->nls) {
            result =
                befs_utf2nls(sb, keybuf, keysize, &nlsname, &nlsnamelen);
            if (result < 0) {
                  befs_debug(sb, "<--- befs_readdir() ERROR");
                  return result;
            }
            result = filldir(dirent, nlsname, nlsnamelen, filp->f_pos,
                         (ino_t) value, d_type);
            kfree(nlsname);

      } else {
            result = filldir(dirent, keybuf, keysize, filp->f_pos,
                         (ino_t) value, d_type);
      }

      filp->f_pos++;

      befs_debug(sb, "<--- befs_readdir() filp->f_pos %Ld", filp->f_pos);

      return 0;
}

static struct inode *
befs_alloc_inode(struct super_block *sb)
{
        struct befs_inode_info *bi;
        bi = (struct befs_inode_info *)kmem_cache_alloc(befs_inode_cachep,
                                          GFP_KERNEL);
        if (!bi)
                return NULL;
        return &bi->vfs_inode;
}

static void
befs_destroy_inode(struct inode *inode)
{
        kmem_cache_free(befs_inode_cachep, BEFS_I(inode));
}

static void init_once(struct kmem_cache *cachep, void *foo)
{
        struct befs_inode_info *bi = (struct befs_inode_info *) foo;

      inode_init_once(&bi->vfs_inode);
}

static void
befs_read_inode(struct inode *inode)
{
      struct buffer_head *bh = NULL;
      befs_inode *raw_inode = NULL;

      struct super_block *sb = inode->i_sb;
      befs_sb_info *befs_sb = BEFS_SB(sb);
      befs_inode_info *befs_ino = NULL;

      befs_debug(sb, "---> befs_read_inode() " "inode = %lu", inode->i_ino);

      befs_ino = BEFS_I(inode);

      /* convert from vfs's inode number to befs's inode number */
      befs_ino->i_inode_num = blockno2iaddr(sb, inode->i_ino);

      befs_debug(sb, "  real inode number [%u, %hu, %hu]",
               befs_ino->i_inode_num.allocation_group,
               befs_ino->i_inode_num.start, befs_ino->i_inode_num.len);

      bh = befs_bread(sb, inode->i_ino);
      if (!bh) {
            befs_error(sb, "unable to read inode block - "
                     "inode = %lu", inode->i_ino);
            goto unacquire_none;
      }

      raw_inode = (befs_inode *) bh->b_data;

      befs_dump_inode(sb, raw_inode);

      if (befs_check_inode(sb, raw_inode, inode->i_ino) != BEFS_OK) {
            befs_error(sb, "Bad inode: %lu", inode->i_ino);
            goto unacquire_bh;
      }

      inode->i_mode = (umode_t) fs32_to_cpu(sb, raw_inode->mode);

      /*
       * set uid and gid.  But since current BeOS is single user OS, so
       * you can change by "uid" or "gid" options.
       */   

      inode->i_uid = befs_sb->mount_opts.use_uid ?
          befs_sb->mount_opts.uid : (uid_t) fs32_to_cpu(sb, raw_inode->uid);
      inode->i_gid = befs_sb->mount_opts.use_gid ?
          befs_sb->mount_opts.gid : (gid_t) fs32_to_cpu(sb, raw_inode->gid);

      inode->i_nlink = 1;

      /*
       * BEFS's time is 64 bits, but current VFS is 32 bits...
       * BEFS don't have access time. Nor inode change time. VFS
       * doesn't have creation time.
       * Also, the lower 16 bits of the last_modified_time and 
       * create_time are just a counter to help ensure uniqueness
       * for indexing purposes. (PFD, page 54)
       */

      inode->i_mtime.tv_sec =
          fs64_to_cpu(sb, raw_inode->last_modified_time) >> 16;
      inode->i_mtime.tv_nsec = 0;   /* lower 16 bits are not a time */  
      inode->i_ctime = inode->i_mtime;
      inode->i_atime = inode->i_mtime;

      befs_ino->i_inode_num = fsrun_to_cpu(sb, raw_inode->inode_num);
      befs_ino->i_parent = fsrun_to_cpu(sb, raw_inode->parent);
      befs_ino->i_attribute = fsrun_to_cpu(sb, raw_inode->attributes);
      befs_ino->i_flags = fs32_to_cpu(sb, raw_inode->flags);

      if (S_ISLNK(inode->i_mode) && !(befs_ino->i_flags & BEFS_LONG_SYMLINK)){
            inode->i_size = 0;
            inode->i_blocks = befs_sb->block_size / VFS_BLOCK_SIZE;
            strncpy(befs_ino->i_data.symlink, raw_inode->data.symlink,
                  BEFS_SYMLINK_LEN);
      } else {
            int num_blks;

            befs_ino->i_data.ds =
                fsds_to_cpu(sb, raw_inode->data.datastream);

            num_blks = befs_count_blocks(sb, &befs_ino->i_data.ds);
            inode->i_blocks =
                num_blks * (befs_sb->block_size / VFS_BLOCK_SIZE);
            inode->i_size = befs_ino->i_data.ds.size;
      }

      inode->i_mapping->a_ops = &befs_aops;

      if (S_ISREG(inode->i_mode)) {
            inode->i_fop = &generic_ro_fops;
      } else if (S_ISDIR(inode->i_mode)) {
            inode->i_op = &befs_dir_inode_operations;
            inode->i_fop = &befs_dir_operations;
      } else if (S_ISLNK(inode->i_mode)) {
            inode->i_op = &befs_symlink_inode_operations;
      } else {
            befs_error(sb, "Inode %lu is not a regular file, "
                     "directory or symlink. THAT IS WRONG! BeFS has no "
                     "on disk special files", inode->i_ino);
            goto unacquire_bh;
      }

      brelse(bh);
      befs_debug(sb, "<--- befs_read_inode()");
      return;

      unacquire_bh:
      brelse(bh);

      unacquire_none:
      make_bad_inode(inode);
      befs_debug(sb, "<--- befs_read_inode() - Bad inode");
      return;
}

/* Initialize the inode cache. Called at fs setup.
 *
 * Taken from NFS implementation by Al Viro.
 */
static int
befs_init_inodecache(void)
{
      befs_inode_cachep = kmem_cache_create("befs_inode_cache",
                                    sizeof (struct befs_inode_info),
                                    0, (SLAB_RECLAIM_ACCOUNT|
                                    SLAB_MEM_SPREAD),
                                    init_once);
      if (befs_inode_cachep == NULL) {
            printk(KERN_ERR "befs_init_inodecache: "
                   "Couldn't initalize inode slabcache\n");
            return -ENOMEM;
      }

      return 0;
}

/* Called at fs teardown.
 * 
 * Taken from NFS implementation by Al Viro.
 */
static void
befs_destroy_inodecache(void)
{
      kmem_cache_destroy(befs_inode_cachep);
}

/*
 * The inode of symbolic link is different to data stream.
 * The data stream become link name. Unless the LONG_SYMLINK
 * flag is set.
 */
static void *
befs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
      befs_inode_info *befs_ino = BEFS_I(dentry->d_inode);
      char *link;

      if (befs_ino->i_flags & BEFS_LONG_SYMLINK) {
            struct super_block *sb = dentry->d_sb;
            befs_data_stream *data = &befs_ino->i_data.ds;
            befs_off_t len = data->size;

            befs_debug(sb, "Follow long symlink");

            link = kmalloc(len, GFP_NOFS);
            if (!link) {
                  link = ERR_PTR(-ENOMEM);
            } else if (befs_read_lsymlink(sb, data, link, len) != len) {
                  kfree(link);
                  befs_error(sb, "Failed to read entire long symlink");
                  link = ERR_PTR(-EIO);
            }
      } else {
            link = befs_ino->i_data.symlink;
      }

      nd_set_link(nd, link);
      return NULL;
}

static void befs_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
{
      befs_inode_info *befs_ino = BEFS_I(dentry->d_inode);
      if (befs_ino->i_flags & BEFS_LONG_SYMLINK) {
            char *p = nd_get_link(nd);
            if (!IS_ERR(p))
                  kfree(p);
      }
}

/*
 * UTF-8 to NLS charset  convert routine
 * 
 *
 * Changed 8/10/01 by Will Dyson. Now use uni2char() / char2uni() rather than
 * the nls tables directly
 */

static int
befs_utf2nls(struct super_block *sb, const char *in,
           int in_len, char **out, int *out_len)
{
      struct nls_table *nls = BEFS_SB(sb)->nls;
      int i, o;
      wchar_t uni;
      int unilen, utflen;
      char *result;
      /* The utf8->nls conversion won't make the final nls string bigger
       * than the utf one, but if the string is pure ascii they'll have the
       * same width and an extra char is needed to save the additional \0
       */
      int maxlen = in_len + 1;

      befs_debug(sb, "---> utf2nls()");

      if (!nls) {
            befs_error(sb, "befs_utf2nls called with no NLS table loaded");
            return -EINVAL;
      }

      *out = result = kmalloc(maxlen, GFP_NOFS);
      if (!*out) {
            befs_error(sb, "befs_utf2nls() cannot allocate memory");
            *out_len = 0;
            return -ENOMEM;
      }

      for (i = o = 0; i < in_len; i += utflen, o += unilen) {

            /* convert from UTF-8 to Unicode */
            utflen = utf8_mbtowc(&uni, &in[i], in_len - i);
            if (utflen < 0) {
                  goto conv_err;
            }

            /* convert from Unicode to nls */
            unilen = nls->uni2char(uni, &result[o], in_len - o);
            if (unilen < 0) {
                  goto conv_err;
            }
      }
      result[o] = '\0';
      *out_len = o;

      befs_debug(sb, "<--- utf2nls()");

      return o;

      conv_err:
      befs_error(sb, "Name using character set %s contains a character that "
               "cannot be converted to unicode.", nls->charset);
      befs_debug(sb, "<--- utf2nls()");
      kfree(result);
      return -EILSEQ;
}

/**
 * befs_nls2utf - Convert NLS string to utf8 encodeing
 * @sb: Superblock
 * @src: Input string buffer in NLS format
 * @srclen: Length of input string in bytes
 * @dest: The output string in UTF-8 format
 * @destlen: Length of the output buffer
 * 
 * Converts input string @src, which is in the format of the loaded NLS map,
 * into a utf8 string.
 * 
 * The destination string @dest is allocated by this function and the caller is
 * responsible for freeing it with kfree()
 * 
 * On return, *@destlen is the length of @dest in bytes.
 *
 * On success, the return value is the number of utf8 characters written to
 * the output buffer @dest.
 *  
 * On Failure, a negative number coresponding to the error code is returned.
 */

static int
befs_nls2utf(struct super_block *sb, const char *in,
           int in_len, char **out, int *out_len)
{
      struct nls_table *nls = BEFS_SB(sb)->nls;
      int i, o;
      wchar_t uni;
      int unilen, utflen;
      char *result;
      /* There're nls characters that will translate to 3-chars-wide UTF-8
       * characters, a additional byte is needed to save the final \0
       * in special cases */
      int maxlen = (3 * in_len) + 1;

      befs_debug(sb, "---> nls2utf()\n");

      if (!nls) {
            befs_error(sb, "befs_nls2utf called with no NLS table loaded.");
            return -EINVAL;
      }

      *out = result = kmalloc(maxlen, GFP_NOFS);
      if (!*out) {
            befs_error(sb, "befs_nls2utf() cannot allocate memory");
            *out_len = 0;
            return -ENOMEM;
      }

      for (i = o = 0; i < in_len; i += unilen, o += utflen) {

            /* convert from nls to unicode */
            unilen = nls->char2uni(&in[i], in_len - i, &uni);
            if (unilen < 0) {
                  goto conv_err;
            }

            /* convert from unicode to UTF-8 */
            utflen = utf8_wctomb(&result[o], uni, 3);
            if (utflen <= 0) {
                  goto conv_err;
            }
      }

      result[o] = '\0';
      *out_len = o;

      befs_debug(sb, "<--- nls2utf()");

      return i;

      conv_err:
      befs_error(sb, "Name using charecter set %s contains a charecter that "
               "cannot be converted to unicode.", nls->charset);
      befs_debug(sb, "<--- nls2utf()");
      kfree(result);
      return -EILSEQ;
}

/**
 * Use the
 *
 */
enum {
      Opt_uid, Opt_gid, Opt_charset, Opt_debug, Opt_err,
};

static match_table_t befs_tokens = {
      {Opt_uid, "uid=%d"},
      {Opt_gid, "gid=%d"},
      {Opt_charset, "iocharset=%s"},
      {Opt_debug, "debug"},
      {Opt_err, NULL}
};

static int
parse_options(char *options, befs_mount_options * opts)
{
      char *p;
      substring_t args[MAX_OPT_ARGS];
      int option;

      /* Initialize options */
      opts->uid = 0;
      opts->gid = 0;
      opts->use_uid = 0;
      opts->use_gid = 0;
      opts->iocharset = NULL;
      opts->debug = 0;

      if (!options)
            return 1;

      while ((p = strsep(&options, ",")) != NULL) {
            int token;
            if (!*p)
                  continue;

            token = match_token(p, befs_tokens, args);
            switch (token) {
            case Opt_uid:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0) {
                        printk(KERN_ERR "BeFS: Invalid uid %d, "
                                    "using default\n", option);
                        break;
                  }
                  opts->uid = option;
                  opts->use_uid = 1;
                  break;
            case Opt_gid:
                  if (match_int(&args[0], &option))
                        return 0;
                  if (option < 0) {
                        printk(KERN_ERR "BeFS: Invalid gid %d, "
                                    "using default\n", option);
                        break;
                  }
                  opts->gid = option;
                  opts->use_gid = 1;
                  break;
            case Opt_charset:
                  kfree(opts->iocharset);
                  opts->iocharset = match_strdup(&args[0]);
                  if (!opts->iocharset) {
                        printk(KERN_ERR "BeFS: allocation failure for "
                                    "iocharset string\n");
                        return 0;
                  }
                  break;
            case Opt_debug:
                  opts->debug = 1;
                  break;
            default:
                  printk(KERN_ERR "BeFS: Unrecognized mount option \"%s\" "
                              "or missing value\n", p);
                  return 0;
            }
      }
      return 1;
}

/* This function has the responsibiltiy of getting the
 * filesystem ready for unmounting. 
 * Basicly, we free everything that we allocated in
 * befs_read_inode
 */
static void
befs_put_super(struct super_block *sb)
{
      kfree(BEFS_SB(sb)->mount_opts.iocharset);
      BEFS_SB(sb)->mount_opts.iocharset = NULL;

      if (BEFS_SB(sb)->nls) {
            unload_nls(BEFS_SB(sb)->nls);
            BEFS_SB(sb)->nls = NULL;
      }

      kfree(sb->s_fs_info);
      sb->s_fs_info = NULL;
      return;
}

/* Allocate private field of the superblock, fill it.
 *
 * Finish filling the public superblock fields
 * Make the root directory
 * Load a set of NLS translations if needed.
 */
static int
befs_fill_super(struct super_block *sb, void *data, int silent)
{
      struct buffer_head *bh;
      befs_sb_info *befs_sb;
      befs_super_block *disk_sb;
      struct inode *root;

      const unsigned long sb_block = 0;
      const off_t x86_sb_off = 512;

      sb->s_fs_info = kmalloc(sizeof (*befs_sb), GFP_KERNEL);
      if (sb->s_fs_info == NULL) {
            printk(KERN_ERR
                   "BeFS(%s): Unable to allocate memory for private "
                   "portion of superblock. Bailing.\n", sb->s_id);
            goto unacquire_none;
      }
      befs_sb = BEFS_SB(sb);
      memset(befs_sb, 0, sizeof(befs_sb_info));

      if (!parse_options((char *) data, &befs_sb->mount_opts)) {
            befs_error(sb, "cannot parse mount options");
            goto unacquire_priv_sbp;
      }

      befs_debug(sb, "---> befs_fill_super()");

#ifndef CONFIG_BEFS_RW
      if (!(sb->s_flags & MS_RDONLY)) {
            befs_warning(sb,
                       "No write support. Marking filesystem read-only");
            sb->s_flags |= MS_RDONLY;
      }
#endif                        /* CONFIG_BEFS_RW */

      /*
       * Set dummy blocksize to read super block.
       * Will be set to real fs blocksize later.
       *
       * Linux 2.4.10 and later refuse to read blocks smaller than
       * the hardsect size for the device. But we also need to read at 
       * least 1k to get the second 512 bytes of the volume.
       * -WD 10-26-01
       */ 
      sb_min_blocksize(sb, 1024);

      if (!(bh = sb_bread(sb, sb_block))) {
            befs_error(sb, "unable to read superblock");
            goto unacquire_priv_sbp;
      }

      /* account for offset of super block on x86 */
      disk_sb = (befs_super_block *) bh->b_data;
      if ((le32_to_cpu(disk_sb->magic1) == BEFS_SUPER_MAGIC1) ||
          (be32_to_cpu(disk_sb->magic1) == BEFS_SUPER_MAGIC1)) {
            befs_debug(sb, "Using PPC superblock location");
      } else {
            befs_debug(sb, "Using x86 superblock location");
            disk_sb =
                (befs_super_block *) ((void *) bh->b_data + x86_sb_off);
      }

      if (befs_load_sb(sb, disk_sb) != BEFS_OK)
            goto unacquire_bh;

      befs_dump_super_block(sb, disk_sb);

      brelse(bh);

      if (befs_check_sb(sb) != BEFS_OK)
            goto unacquire_priv_sbp;

      if( befs_sb->num_blocks > ~((sector_t)0) ) {
            befs_error(sb, "blocks count: %Lu "
                  "is larger than the host can use",
                  befs_sb->num_blocks);
            goto unacquire_priv_sbp;
      }

      /*
       * set up enough so that it can read an inode
       * Fill in kernel superblock fields from private sb
       */
      sb->s_magic = BEFS_SUPER_MAGIC;
      /* Set real blocksize of fs */
      sb_set_blocksize(sb, (ulong) befs_sb->block_size);
      sb->s_op = (struct super_operations *) &befs_sops;
      root = iget(sb, iaddr2blockno(sb, &(befs_sb->root_dir)));
      sb->s_root = d_alloc_root(root);
      if (!sb->s_root) {
            iput(root);
            befs_error(sb, "get root inode failed");
            goto unacquire_priv_sbp;
      }

      /* load nls library */
      if (befs_sb->mount_opts.iocharset) {
            befs_debug(sb, "Loading nls: %s",
                     befs_sb->mount_opts.iocharset);
            befs_sb->nls = load_nls(befs_sb->mount_opts.iocharset);
            if (!befs_sb->nls) {
                  befs_warning(sb, "Cannot load nls %s"
                              " loading default nls",
                              befs_sb->mount_opts.iocharset);
                  befs_sb->nls = load_nls_default();
            }
      /* load default nls if none is specified  in mount options */
      } else {
            befs_debug(sb, "Loading default nls");
            befs_sb->nls = load_nls_default();
      }

      return 0;
/*****************/
      unacquire_bh:
      brelse(bh);

      unacquire_priv_sbp:
      kfree(sb->s_fs_info);

      unacquire_none:
      sb->s_fs_info = NULL;
      return -EINVAL;
}

static int
befs_remount(struct super_block *sb, int *flags, char *data)
{
      if (!(*flags & MS_RDONLY))
            return -EINVAL;
      return 0;
}

static int
befs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
      struct super_block *sb = dentry->d_sb;

      befs_debug(sb, "---> befs_statfs()");

      buf->f_type = BEFS_SUPER_MAGIC;
      buf->f_bsize = sb->s_blocksize;
      buf->f_blocks = BEFS_SB(sb)->num_blocks;
      buf->f_bfree = BEFS_SB(sb)->num_blocks - BEFS_SB(sb)->used_blocks;
      buf->f_bavail = buf->f_bfree;
      buf->f_files = 0; /* UNKNOWN */
      buf->f_ffree = 0; /* UNKNOWN */
      buf->f_namelen = BEFS_NAME_LEN;

      befs_debug(sb, "<--- befs_statfs()");

      return 0;
}

static int
befs_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name,
          void *data, struct vfsmount *mnt)
{
      return get_sb_bdev(fs_type, flags, dev_name, data, befs_fill_super,
                     mnt);
}

static struct file_system_type befs_fs_type = {
      .owner            = THIS_MODULE,
      .name       = "befs",
      .get_sb           = befs_get_sb,
      .kill_sb    = kill_block_super,
      .fs_flags   = FS_REQUIRES_DEV,      
};

static int __init
init_befs_fs(void)
{
      int err;

      printk(KERN_INFO "BeFS version: %s\n", BEFS_VERSION);

      err = befs_init_inodecache();
      if (err)
            goto unacquire_none;

      err = register_filesystem(&befs_fs_type);
      if (err)
            goto unacquire_inodecache;

      return 0;

unacquire_inodecache:
      befs_destroy_inodecache();

unacquire_none:
      return err;
}

static void __exit
exit_befs_fs(void)
{
      befs_destroy_inodecache();

      unregister_filesystem(&befs_fs_type);
}

/*
Macros that typecheck the init and exit functions,
ensures that they are called at init and cleanup,
and eliminates warnings about unused functions.
*/
module_init(init_befs_fs)
module_exit(exit_befs_fs)

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