// SPDX-License-Identifier: GPL-2.0-only

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

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #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 <linux/sched.h>

  #include <linux/cred.h>

  #include <linux/exportfs.h>

  #include <linux/seq_file.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 *, struct dir_context *);

  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 *,
  				  unsigned int);

  static struct inode *befs_iget(struct super_block *, unsigned long);

  static struct inode *befs_alloc_inode(struct super_block *sb);

  static void befs_free_inode(struct inode *inode);

  static void befs_destroy_inodecache(void);

  static int befs_symlink_readpage(struct file *, struct page *);

  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 befs_show_options(struct seq_file *, struct dentry *);

  static int parse_options(char *, struct befs_mount_options *);

  static struct dentry *befs_fh_to_dentry(struct super_block *sb,
  				struct fid *fid, int fh_len, int fh_type);
  static struct dentry *befs_fh_to_parent(struct super_block *sb,
  				struct fid *fid, int fh_len, int fh_type);

  static struct dentry *befs_get_parent(struct dentry *child);

  
  static const struct super_operations befs_sops = {

  	.alloc_inode	= befs_alloc_inode,	/* allocate a new inode */

  	.free_inode	= befs_free_inode, /* deallocate an inode */

  	.put_super	= befs_put_super,	/* uninit super */
  	.statfs		= befs_statfs,	/* statfs */
  	.remount_fs	= befs_remount,

  	.show_options	= befs_show_options,

  };
  
  /* 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,

  	.iterate_shared	= befs_readdir,

  	.llseek		= generic_file_llseek,

  };

  static const struct inode_operations befs_dir_inode_operations = {

  	.lookup		= befs_lookup,
  };

  static const struct address_space_operations befs_aops = {

  	.readpage	= befs_readpage,

  	.bmap		= befs_bmap,
  };

  static const struct address_space_operations befs_symlink_aops = {
  	.readpage	= befs_symlink_readpage,

  };

  static const struct export_operations befs_export_operations = {
  	.fh_to_dentry	= befs_fh_to_dentry,
  	.fh_to_parent	= befs_fh_to_parent,

  	.get_parent	= befs_get_parent,

  };

  /*

   * 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.

   */
  
  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;

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

  		   (unsigned long)inode->i_ino, (long)block);

  	if (create) {
  		befs_error(sb, "befs_get_block() was asked to write to "

  			   "block %ld in inode %lu", (long)block,
  			   (unsigned long)inode->i_ino);

  		return -EPERM;
  	}
  
  	res = befs_fblock2brun(sb, ds, block, &run);
  	if (res != BEFS_OK) {
  		befs_error(sb,

  			   "<--- %s for inode %lu, block %ld ERROR",
  			   __func__, (unsigned long)inode->i_ino,
  			   (long)block);

  		return -EFBIG;
  	}
  
  	disk_off = (ulong) iaddr2blockno(sb, &run);
  
  	map_bh(bh_result, inode->i_sb, disk_off);

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

  
  	return 0;
  }
  
  static struct dentry *

  befs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)

  {

  	struct inode *inode;

  	struct super_block *sb = dir->i_sb;

  	const 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, "---> %s name %pd inode %ld", __func__,
  		   dentry, 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, "<--- %s ERROR", __func__);

  			return ERR_PTR(ret);
  		}
  		ret = befs_btree_find(sb, ds, utfname, &offset);
  		kfree(utfname);
  
  	} else {

  		ret = befs_btree_find(sb, ds, name, &offset);

  	}
  
  	if (ret == BEFS_BT_NOT_FOUND) {

  		befs_debug(sb, "<--- %s %pd not found", __func__, dentry);

  		inode = NULL;

  	} else if (ret != BEFS_OK || offset == 0) {

  		befs_error(sb, "<--- %s Error", __func__);

  		inode = ERR_PTR(-ENODATA);
  	} else {
  		inode = befs_iget(dir->i_sb, (ino_t) offset);

  	}

  	befs_debug(sb, "<--- %s", __func__);

  	return d_splice_alias(inode, dentry);

  }
  
  static int

  befs_readdir(struct file *file, struct dir_context *ctx)

  {

  	struct inode *inode = file_inode(file);

  	struct super_block *sb = inode->i_sb;

  	const befs_data_stream *ds = &BEFS_I(inode)->i_data.ds;

  	befs_off_t value;
  	int result;
  	size_t keysize;

  	char keybuf[BEFS_NAME_LEN + 1];

  	befs_debug(sb, "---> %s name %pD, inode %ld, ctx->pos %lld",
  		  __func__, file, inode->i_ino, ctx->pos);

  	while (1) {
  		result = befs_btree_read(sb, ds, ctx->pos, BEFS_NAME_LEN + 1,
  					 keybuf, &keysize, &value);

  		if (result == BEFS_ERR) {

  			befs_debug(sb, "<--- %s ERROR", __func__);

  			befs_error(sb, "IO error reading %pD (inode %lu)",
  				   file, inode->i_ino);
  			return -EIO;

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

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

  		}

  
  		/* Convert to NLS */
  		if (BEFS_SB(sb)->nls) {
  			char *nlsname;
  			int nlsnamelen;
  
  			result =
  			    befs_utf2nls(sb, keybuf, keysize, &nlsname,
  					 &nlsnamelen);
  			if (result < 0) {
  				befs_debug(sb, "<--- %s ERROR", __func__);
  				return result;
  			}
  			if (!dir_emit(ctx, nlsname, nlsnamelen,
  				      (ino_t) value, DT_UNKNOWN)) {
  				kfree(nlsname);
  				return 0;
  			}

  			kfree(nlsname);

  		} else {
  			if (!dir_emit(ctx, keybuf, keysize,
  				      (ino_t) value, DT_UNKNOWN))
  				return 0;

  		}

  		ctx->pos++;

  	}

  }
  
  static struct inode *
  befs_alloc_inode(struct super_block *sb)
  {

  	struct befs_inode_info *bi;
  
  	bi = kmem_cache_alloc(befs_inode_cachep, GFP_KERNEL);

  	if (!bi)
  		return NULL;
  	return &bi->vfs_inode;

  }

  static void befs_free_inode(struct inode *inode)

  {

  	kmem_cache_free(befs_inode_cachep, BEFS_I(inode));

  }

  static void init_once(void *foo)

  {

  	struct befs_inode_info *bi = (struct befs_inode_info *) foo;

  
  	inode_init_once(&bi->vfs_inode);

  }

  static struct inode *befs_iget(struct super_block *sb, unsigned long ino)

  {

  	struct buffer_head *bh;

  	befs_inode *raw_inode;

  	struct befs_sb_info *befs_sb = BEFS_SB(sb);

  	struct befs_inode_info *befs_ino;

  	struct inode *inode;

  	befs_debug(sb, "---> %s inode = %lu", __func__, ino);

  
  	inode = iget_locked(sb, ino);

  	if (!inode)
  		return ERR_PTR(-ENOMEM);

  	if (!(inode->i_state & I_NEW))
  		return inode;

  
  	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 = sb_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 :
  		make_kuid(&init_user_ns, fs32_to_cpu(sb, raw_inode->uid));

  	inode->i_gid = befs_sb->mount_opts.use_gid ?

  		befs_sb->mount_opts.gid :
  		make_kgid(&init_user_ns, fs32_to_cpu(sb, raw_inode->gid));

  	set_nlink(inode, 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;

  		strlcpy(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)) {

  		if (befs_ino->i_flags & BEFS_LONG_SYMLINK) {

  			inode->i_op = &page_symlink_inode_operations;

  			inode_nohighmem(inode);

  			inode->i_mapping->a_ops = &befs_symlink_aops;

  		} else {
  			inode->i_link = befs_ino->i_data.symlink;
  			inode->i_op = &simple_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, "<--- %s", __func__);

  	unlock_new_inode(inode);
  	return inode;

  unacquire_bh:

  	brelse(bh);

  unacquire_none:

  	iget_failed(inode);

  	befs_debug(sb, "<--- %s - Bad inode", __func__);

  	return ERR_PTR(-EIO);

  }
  
  /* Initialize the inode cache. Called at fs setup.

   *

   * Taken from NFS implementation by Al Viro.
   */

  static int __init

  befs_init_inodecache(void)
  {

  	befs_inode_cachep = kmem_cache_create_usercopy("befs_inode_cache",
  				sizeof(struct befs_inode_info), 0,
  				(SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD|
  					SLAB_ACCOUNT),
  				offsetof(struct befs_inode_info,
  					i_data.symlink),
  				sizeof_field(struct befs_inode_info,
  					i_data.symlink),
  				init_once);

  	if (befs_inode_cachep == NULL)

  		return -ENOMEM;

  	return 0;
  }
  
  /* Called at fs teardown.

   *

   * Taken from NFS implementation by Al Viro.
   */
  static void
  befs_destroy_inodecache(void)
  {

  	/*
  	 * Make sure all delayed rcu free inodes are flushed before we
  	 * destroy cache.
  	 */
  	rcu_barrier();

  	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 int befs_symlink_readpage(struct file *unused, struct page *page)

  {

  	struct inode *inode = page->mapping->host;
  	struct super_block *sb = inode->i_sb;
  	struct befs_inode_info *befs_ino = BEFS_I(inode);

  	befs_data_stream *data = &befs_ino->i_data.ds;
  	befs_off_t len = data->size;

  	char *link = page_address(page);

  	if (len == 0 || len > PAGE_SIZE) {

  		befs_error(sb, "Long symlink with illegal length");

  		goto fail;

  	}

  	befs_debug(sb, "Follow long symlink");

  	if (befs_read_lsymlink(sb, data, link, len) != len) {

  		befs_error(sb, "Failed to read entire long symlink");

  		goto fail;

  	}
  	link[len - 1] = '\0';

  	SetPageUptodate(page);

  	unlock_page(page);
  	return 0;
  fail:
  	SetPageError(page);

  	unlock_page(page);
  	return -EIO;

  }

  /*

   * UTF-8 to NLS charset convert routine

   *

   * Uses 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;

  	unicode_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, "---> %s", __func__);

  
  	if (!nls) {

  		befs_error(sb, "%s called with no NLS table loaded", __func__);

  		return -EINVAL;
  	}
  
  	*out = result = kmalloc(maxlen, GFP_NOFS);

  	if (!*out)

  		return -ENOMEM;

  
  	for (i = o = 0; i < in_len; i += utflen, o += unilen) {
  
  		/* convert from UTF-8 to Unicode */

  		utflen = utf8_to_utf32(&in[i], in_len - i, &uni);
  		if (utflen < 0)

  			goto conv_err;

  
  		/* convert from Unicode to nls */

  		if (uni > MAX_WCHAR_T)
  			goto conv_err;

  		unilen = nls->uni2char(uni, &result[o], in_len - o);

  		if (unilen < 0)

  			goto conv_err;

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

  	befs_debug(sb, "<--- %s", __func__);

  
  	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, "<--- %s", __func__);

  	kfree(result);
  	return -EILSEQ;
  }
  
  /**
   * befs_nls2utf - Convert NLS string to utf8 encodeing
   * @sb: Superblock

   * @in: Input string buffer in NLS format
   * @in_len: Length of input string in bytes
   * @out: The output string in UTF-8 format
   * @out_len: Length of the output buffer

   *

   * Converts input string @in, which is in the format of the loaded NLS map,

   * into a utf8 string.

   *

   * The destination string @out is allocated by this function and the caller is

   * responsible for freeing it with kfree()

   *

   * On return, *@out_len is the length of @out in bytes.

   *
   * On success, the return value is the number of utf8 characters written to

   * the output buffer @out.

   *

   * 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 are nls characters that will translate to 3-chars-wide UTF-8
  	 * characters, an additional byte is needed to save the final \0

  	 * in special cases
  	 */

  	int maxlen = (3 * in_len) + 1;

  	befs_debug(sb, "---> %s
  ", __func__);

  
  	if (!nls) {

  		befs_error(sb, "%s called with no NLS table loaded.",
  			   __func__);

  		return -EINVAL;
  	}
  
  	*out = result = kmalloc(maxlen, GFP_NOFS);
  	if (!*out) {

  		*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 = utf32_to_utf8(uni, &result[o], 3);
  		if (utflen <= 0)

  			goto conv_err;

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

  	befs_debug(sb, "<--- %s", __func__);

  
  	return i;

  conv_err:

  	befs_error(sb, "Name using character set %s contains a character that "

  		   "cannot be converted to unicode.", nls->charset);

  	befs_debug(sb, "<--- %s", __func__);

  	kfree(result);
  	return -EILSEQ;
  }

  static struct inode *befs_nfs_get_inode(struct super_block *sb, uint64_t ino,
  					 uint32_t generation)
  {
  	/* No need to handle i_generation */
  	return befs_iget(sb, ino);
  }
  
  /*
   * Map a NFS file handle to a corresponding dentry
   */
  static struct dentry *befs_fh_to_dentry(struct super_block *sb,
  				struct fid *fid, int fh_len, int fh_type)
  {
  	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
  				    befs_nfs_get_inode);
  }
  
  /*
   * Find the parent for a file specified by NFS handle
   */
  static struct dentry *befs_fh_to_parent(struct super_block *sb,
  				struct fid *fid, int fh_len, int fh_type)
  {
  	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
  				    befs_nfs_get_inode);
  }

  static struct dentry *befs_get_parent(struct dentry *child)
  {
  	struct inode *parent;
  	struct befs_inode_info *befs_ino = BEFS_I(d_inode(child));
  
  	parent = befs_iget(child->d_sb,
  			   (unsigned long)befs_ino->i_parent.start);
  	if (IS_ERR(parent))
  		return ERR_CAST(parent);
  
  	return d_obtain_alias(parent);
  }

  enum {
  	Opt_uid, Opt_gid, Opt_charset, Opt_debug, Opt_err,
  };

  static const 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, struct befs_mount_options *opts)

  {
  	char *p;
  	substring_t args[MAX_OPT_ARGS];
  	int option;

  	kuid_t uid;
  	kgid_t gid;

  
  	/* Initialize options */

  	opts->uid = GLOBAL_ROOT_UID;
  	opts->gid = GLOBAL_ROOT_GID;

  	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;

  			uid = INVALID_UID;
  			if (option >= 0)
  				uid = make_kuid(current_user_ns(), option);
  			if (!uid_valid(uid)) {

  				pr_err("Invalid uid %d, "
  				       "using default
  ", option);

  				break;
  			}

  			opts->uid = uid;

  			opts->use_uid = 1;
  			break;
  		case Opt_gid:
  			if (match_int(&args[0], &option))
  				return 0;

  			gid = INVALID_GID;
  			if (option >= 0)
  				gid = make_kgid(current_user_ns(), option);
  			if (!gid_valid(gid)) {

  				pr_err("Invalid gid %d, "
  				       "using default
  ", option);

  				break;
  			}

  			opts->gid = gid;

  			opts->use_gid = 1;
  			break;
  		case Opt_charset:
  			kfree(opts->iocharset);
  			opts->iocharset = match_strdup(&args[0]);
  			if (!opts->iocharset) {

  				pr_err("allocation failure for "
  				       "iocharset string
  ");

  				return 0;
  			}
  			break;
  		case Opt_debug:
  			opts->debug = 1;
  			break;
  		default:

  			pr_err("Unrecognized mount option \"%s\" "
  			       "or missing value
  ", p);

  			return 0;
  		}
  	}
  	return 1;
  }

  static int befs_show_options(struct seq_file *m, struct dentry *root)
  {
  	struct befs_sb_info *befs_sb = BEFS_SB(root->d_sb);
  	struct befs_mount_options *opts = &befs_sb->mount_opts;
  
  	if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
  		seq_printf(m, ",uid=%u",
  			   from_kuid_munged(&init_user_ns, opts->uid));
  	if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
  		seq_printf(m, ",gid=%u",
  			   from_kgid_munged(&init_user_ns, opts->gid));
  	if (opts->iocharset)
  		seq_printf(m, ",charset=%s", opts->iocharset);
  	if (opts->debug)
  		seq_puts(m, ",debug");
  	return 0;
  }

  /* This function has the responsibiltiy of getting the

   * filesystem ready for unmounting.

   * Basically, 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;

  	unload_nls(BEFS_SB(sb)->nls);

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

  }
  
  /* 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;

  	struct befs_sb_info *befs_sb;

  	befs_super_block *disk_sb;
  	struct inode *root;

  	long ret = -EINVAL;

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

  	int blocksize;

  	sb->s_fs_info = kzalloc(sizeof(*befs_sb), GFP_KERNEL);

  	if (sb->s_fs_info == NULL)

  		goto unacquire_none;

  	befs_sb = BEFS_SB(sb);

  
  	if (!parse_options((char *) data, &befs_sb->mount_opts)) {

  		if (!silent)
  			befs_error(sb, "cannot parse mount options");

  		goto unacquire_priv_sbp;

  	}

  	befs_debug(sb, "---> %s", __func__);

  	if (!sb_rdonly(sb)) {

  		befs_warning(sb,
  			     "No write support. Marking filesystem read-only");

  		sb->s_flags |= SB_RDONLY;

  	}

  
  	/*
  	 * 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 logical block size for the device. But we also need to read at

  	 * least 1k to get the second 512 bytes of the volume.

  	 */

  	blocksize = sb_min_blocksize(sb, 1024);
  	if (!blocksize) {

  		if (!silent)
  			befs_error(sb, "unable to set blocksize");

  		goto unacquire_priv_sbp;
  	}

  	bh = sb_bread(sb, sb_block);
  	if (!bh) {

  		if (!silent)
  			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 ((disk_sb->magic1 == BEFS_SUPER_MAGIC1_LE) ||
  	    (disk_sb->magic1 == BEFS_SUPER_MAGIC1_BE)) {

  		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) ||
  	    (befs_check_sb(sb) != BEFS_OK))

  		goto unacquire_bh;

  
  	befs_dump_super_block(sb, disk_sb);
  
  	brelse(bh);

  	if (befs_sb->num_blocks > ~((sector_t)0)) {

  		if (!silent)
  			befs_error(sb, "blocks count: %llu 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 = &befs_sops;

  	sb->s_export_op = &befs_export_operations;

  	sb->s_time_min = 0;
  	sb->s_time_max = 0xffffffffffffll;

  	root = befs_iget(sb, iaddr2blockno(sb, &(befs_sb->root_dir)));
  	if (IS_ERR(root)) {
  		ret = PTR_ERR(root);
  		goto unacquire_priv_sbp;
  	}

  	sb->s_root = d_make_root(root);

  	if (!sb->s_root) {

  		if (!silent)
  			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(befs_sb->mount_opts.iocharset);

  	kfree(sb->s_fs_info);

  	sb->s_fs_info = NULL;

  unacquire_none:

  	return ret;

  }
  
  static int
  befs_remount(struct super_block *sb, int *flags, char *data)
  {

  	sync_filesystem(sb);

  	if (!(*flags & SB_RDONLY))

  		return -EINVAL;
  	return 0;
  }
  
  static int

  befs_statfs(struct dentry *dentry, struct kstatfs *buf)

  {

  	struct super_block *sb = dentry->d_sb;

  	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

  	befs_debug(sb, "---> %s", __func__);

  
  	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_fsid.val[0] = (u32)id;
  	buf->f_fsid.val[1] = (u32)(id >> 32);

  	buf->f_namelen = BEFS_NAME_LEN;

  	befs_debug(sb, "<--- %s", __func__);

  
  	return 0;
  }

  static struct dentry *
  befs_mount(struct file_system_type *fs_type, int flags, const char *dev_name,
  	    void *data)

  {

  	return mount_bdev(fs_type, flags, dev_name, data, befs_fill_super);

  }
  
  static struct file_system_type befs_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "befs",

  	.mount		= befs_mount,

  	.kill_sb	= kill_block_super,

  	.fs_flags	= FS_REQUIRES_DEV,

  };

  MODULE_ALIAS_FS("befs");

  
  static int __init
  init_befs_fs(void)
  {
  	int err;

  	pr_info("version: %s
  ", 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)