fs/hfs/super.c - kernel/msm-4.19 - Gitiles

 /*
  *  linux/fs/hfs/super.c
  *
  * Copyright (C) 1995-1997  Paul H. Hargrove
  * (C) 2003 Ardis Technologies <roman@ardistech.com>
  * This file may be distributed under the terms of the GNU General Public License.
  *
  * This file contains hfs_read_super(), some of the super_ops and
  * init_hfs_fs() and exit_hfs_fs().  The remaining super_ops are in
  * inode.c since they deal with inodes.
  *
  * Based on the minix file system code, (C) 1991, 1992 by Linus Torvalds
  */

 #include <linux/module.h>
 #include <linux/blkdev.h>
 #include <linux/mount.h>
 #include <linux/init.h>
 #include <linux/nls.h>
 #include <linux/parser.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/vfs.h>

 #include "hfs_fs.h"
 #include "btree.h"

 static struct kmem_cache *hfs_inode_cachep;

 MODULE_LICENSE("GPL");

 /*
  * hfs_write_super()
  *
  * Description:
  *   This function is called by the VFS only. When the filesystem
  *   is mounted r/w it updates the MDB on disk.
  * Input Variable(s):
  *   struct super_block *sb: Pointer to the hfs superblock
  * Output Variable(s):
  *   NONE
  * Returns:
  *   void
  * Preconditions:
  *   'sb' points to a "valid" (struct super_block).
  * Postconditions:
  *   The MDB is marked 'unsuccessfully unmounted' by clearing bit 8 of drAtrb
  *   (hfs_put_super() must set this flag!). Some MDB fields are updated
  *   and the MDB buffer is written to disk by calling hfs_mdb_commit().
  */
 static void hfs_write_super(struct super_block *sb)
 {
 	sb->s_dirt = 0;

 	/* sync everything to the buffers */
 	hfs_mdb_commit(sb);
 }

 static int hfs_sync_fs(struct super_block *sb, int wait)
 {
 	hfs_mdb_commit(sb);
 	sb->s_dirt = 0;

 	return 0;
 }

 /*
  * hfs_put_super()
  *
  * This is the put_super() entry in the super_operations structure for
  * HFS filesystems.  The purpose is to release the resources
  * associated with the superblock sb.
  */
 static void hfs_put_super(struct super_block *sb)
 {
 	hfs_mdb_close(sb);
 	/* release the MDB's resources */
 	hfs_mdb_put(sb);
 }

 /*
  * hfs_statfs()
  *
  * This is the statfs() entry in the super_operations structure for
  * HFS filesystems.  The purpose is to return various data about the
  * filesystem.
  *
  * changed f_files/f_ffree to reflect the fs_ablock/free_ablocks.
  */
 static int hfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;
 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

 	buf->f_type = HFS_SUPER_MAGIC;
 	buf->f_bsize = sb->s_blocksize;
 	buf->f_blocks = (u32)HFS_SB(sb)->fs_ablocks * HFS_SB(sb)->fs_div;
 	buf->f_bfree = (u32)HFS_SB(sb)->free_ablocks * HFS_SB(sb)->fs_div;
 	buf->f_bavail = buf->f_bfree;
 	buf->f_files = HFS_SB(sb)->fs_ablocks;
 	buf->f_ffree = HFS_SB(sb)->free_ablocks;
 	buf->f_fsid.val[0] = (u32)id;
 	buf->f_fsid.val[1] = (u32)(id >> 32);
 	buf->f_namelen = HFS_NAMELEN;

 	return 0;
 }

 static int hfs_remount(struct super_block *sb, int *flags, char *data)
 {
 	*flags |= MS_NODIRATIME;
 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 		return 0;
 	if (!(*flags & MS_RDONLY)) {
 		if (!(HFS_SB(sb)->mdb->drAtrb & cpu_to_be16(HFS_SB_ATTRIB_UNMNT))) {
 			printk(KERN_WARNING "hfs: filesystem was not cleanly unmounted, "
 			       "running fsck.hfs is recommended.  leaving read-only.\n");
 			sb->s_flags |= MS_RDONLY;
 			*flags |= MS_RDONLY;
 		} else if (HFS_SB(sb)->mdb->drAtrb & cpu_to_be16(HFS_SB_ATTRIB_SLOCK)) {
 			printk(KERN_WARNING "hfs: filesystem is marked locked, leaving read-only.\n");
 			sb->s_flags |= MS_RDONLY;
 			*flags |= MS_RDONLY;
 		}
 	}
 	return 0;
 }

 static int hfs_show_options(struct seq_file *seq, struct dentry *root)
 {
 	struct hfs_sb_info *sbi = HFS_SB(root->d_sb);

 	if (sbi->s_creator != cpu_to_be32(0x3f3f3f3f))
 		seq_printf(seq, ",creator=%.4s", (char *)&sbi->s_creator);
 	if (sbi->s_type != cpu_to_be32(0x3f3f3f3f))
 		seq_printf(seq, ",type=%.4s", (char *)&sbi->s_type);
 	seq_printf(seq, ",uid=%u,gid=%u", sbi->s_uid, sbi->s_gid);
 	if (sbi->s_file_umask != 0133)
 		seq_printf(seq, ",file_umask=%o", sbi->s_file_umask);
 	if (sbi->s_dir_umask != 0022)
 		seq_printf(seq, ",dir_umask=%o", sbi->s_dir_umask);
 	if (sbi->part >= 0)
 		seq_printf(seq, ",part=%u", sbi->part);
 	if (sbi->session >= 0)
 		seq_printf(seq, ",session=%u", sbi->session);
 	if (sbi->nls_disk)
 		seq_printf(seq, ",codepage=%s", sbi->nls_disk->charset);
 	if (sbi->nls_io)
 		seq_printf(seq, ",iocharset=%s", sbi->nls_io->charset);
 	if (sbi->s_quiet)
 		seq_printf(seq, ",quiet");
 	return 0;
 }

 static struct inode *hfs_alloc_inode(struct super_block *sb)
 {
 	struct hfs_inode_info *i;

 	i = kmem_cache_alloc(hfs_inode_cachep, GFP_KERNEL);
 	return i ? &i->vfs_inode : NULL;
 }

 static void hfs_i_callback(struct rcu_head *head)
 {
 	struct inode *inode = container_of(head, struct inode, i_rcu);
 	kmem_cache_free(hfs_inode_cachep, HFS_I(inode));
 }

 static void hfs_destroy_inode(struct inode *inode)
 {
 	call_rcu(&inode->i_rcu, hfs_i_callback);
 }

 static const struct super_operations hfs_super_operations = {
 	.alloc_inode	= hfs_alloc_inode,
 	.destroy_inode	= hfs_destroy_inode,
 	.write_inode	= hfs_write_inode,
 	.evict_inode	= hfs_evict_inode,
 	.put_super	= hfs_put_super,
 	.write_super	= hfs_write_super,
 	.sync_fs	= hfs_sync_fs,
 	.statfs		= hfs_statfs,
 	.remount_fs     = hfs_remount,
 	.show_options	= hfs_show_options,
 };

 enum {
 	opt_uid, opt_gid, opt_umask, opt_file_umask, opt_dir_umask,
 	opt_part, opt_session, opt_type, opt_creator, opt_quiet,
 	opt_codepage, opt_iocharset,
 	opt_err
 };

 static const match_table_t tokens = {
 	{ opt_uid, "uid=%u" },
 	{ opt_gid, "gid=%u" },
 	{ opt_umask, "umask=%o" },
 	{ opt_file_umask, "file_umask=%o" },
 	{ opt_dir_umask, "dir_umask=%o" },
 	{ opt_part, "part=%u" },
 	{ opt_session, "session=%u" },
 	{ opt_type, "type=%s" },
 	{ opt_creator, "creator=%s" },
 	{ opt_quiet, "quiet" },
 	{ opt_codepage, "codepage=%s" },
 	{ opt_iocharset, "iocharset=%s" },
 	{ opt_err, NULL }
 };

 static inline int match_fourchar(substring_t *arg, u32 *result)
 {
 	if (arg->to - arg->from != 4)
 		return -EINVAL;
 	memcpy(result, arg->from, 4);
 	return 0;
 }

 /*
  * parse_options()
  *
  * adapted from linux/fs/msdos/inode.c written 1992,93 by Werner Almesberger
  * This function is called by hfs_read_super() to parse the mount options.
  */
 static int parse_options(char *options, struct hfs_sb_info *hsb)
 {
 	char *p;
 	substring_t args[MAX_OPT_ARGS];
 	int tmp, token;

 	/* initialize the sb with defaults */
 	hsb->s_uid = current_uid();
 	hsb->s_gid = current_gid();
 	hsb->s_file_umask = 0133;
 	hsb->s_dir_umask = 0022;
 	hsb->s_type = hsb->s_creator = cpu_to_be32(0x3f3f3f3f);	/* == '????' */
 	hsb->s_quiet = 0;
 	hsb->part = -1;
 	hsb->session = -1;

 	if (!options)
 		return 1;

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

 		token = match_token(p, tokens, args);
 		switch (token) {
 		case opt_uid:
 			if (match_int(&args[0], &tmp)) {
 				printk(KERN_ERR "hfs: uid requires an argument\n");
 				return 0;
 			}
 			hsb->s_uid = (uid_t)tmp;
 			break;
 		case opt_gid:
 			if (match_int(&args[0], &tmp)) {
 				printk(KERN_ERR "hfs: gid requires an argument\n");
 				return 0;
 			}
 			hsb->s_gid = (gid_t)tmp;
 			break;
 		case opt_umask:
 			if (match_octal(&args[0], &tmp)) {
 				printk(KERN_ERR "hfs: umask requires a value\n");
 				return 0;
 			}
 			hsb->s_file_umask = (umode_t)tmp;
 			hsb->s_dir_umask = (umode_t)tmp;
 			break;
 		case opt_file_umask:
 			if (match_octal(&args[0], &tmp)) {
 				printk(KERN_ERR "hfs: file_umask requires a value\n");
 				return 0;
 			}
 			hsb->s_file_umask = (umode_t)tmp;
 			break;
 		case opt_dir_umask:
 			if (match_octal(&args[0], &tmp)) {
 				printk(KERN_ERR "hfs: dir_umask requires a value\n");
 				return 0;
 			}
 			hsb->s_dir_umask = (umode_t)tmp;
 			break;
 		case opt_part:
 			if (match_int(&args[0], &hsb->part)) {
 				printk(KERN_ERR "hfs: part requires an argument\n");
 				return 0;
 			}
 			break;
 		case opt_session:
 			if (match_int(&args[0], &hsb->session)) {
 				printk(KERN_ERR "hfs: session requires an argument\n");
 				return 0;
 			}
 			break;
 		case opt_type:
 			if (match_fourchar(&args[0], &hsb->s_type)) {
 				printk(KERN_ERR "hfs: type requires a 4 character value\n");
 				return 0;
 			}
 			break;
 		case opt_creator:
 			if (match_fourchar(&args[0], &hsb->s_creator)) {
 				printk(KERN_ERR "hfs: creator requires a 4 character value\n");
 				return 0;
 			}
 			break;
 		case opt_quiet:
 			hsb->s_quiet = 1;
 			break;
 		case opt_codepage:
 			if (hsb->nls_disk) {
 				printk(KERN_ERR "hfs: unable to change codepage\n");
 				return 0;
 			}
 			p = match_strdup(&args[0]);
 			if (p)
 				hsb->nls_disk = load_nls(p);
 			if (!hsb->nls_disk) {
 				printk(KERN_ERR "hfs: unable to load codepage \"%s\"\n", p);
 				kfree(p);
 				return 0;
 			}
 			kfree(p);
 			break;
 		case opt_iocharset:
 			if (hsb->nls_io) {
 				printk(KERN_ERR "hfs: unable to change iocharset\n");
 				return 0;
 			}
 			p = match_strdup(&args[0]);
 			if (p)
 				hsb->nls_io = load_nls(p);
 			if (!hsb->nls_io) {
 				printk(KERN_ERR "hfs: unable to load iocharset \"%s\"\n", p);
 				kfree(p);
 				return 0;
 			}
 			kfree(p);
 			break;
 		default:
 			return 0;
 		}
 	}

 	if (hsb->nls_disk && !hsb->nls_io) {
 		hsb->nls_io = load_nls_default();
 		if (!hsb->nls_io) {
 			printk(KERN_ERR "hfs: unable to load default iocharset\n");
 			return 0;
 		}
 	}
 	hsb->s_dir_umask &= 0777;
 	hsb->s_file_umask &= 0577;

 	return 1;
 }

 /*
  * hfs_read_super()
  *
  * This is the function that is responsible for mounting an HFS
  * filesystem.	It performs all the tasks necessary to get enough data
  * from the disk to read the root inode.  This includes parsing the
  * mount options, dealing with Macintosh partitions, reading the
  * superblock and the allocation bitmap blocks, calling
  * hfs_btree_init() to get the necessary data about the extents and
  * catalog B-trees and, finally, reading the root inode into memory.
  */
 static int hfs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct hfs_sb_info *sbi;
 	struct hfs_find_data fd;
 	hfs_cat_rec rec;
 	struct inode *root_inode;
 	int res;

 	sbi = kzalloc(sizeof(struct hfs_sb_info), GFP_KERNEL);
 	if (!sbi)
 		return -ENOMEM;

 	sb->s_fs_info = sbi;

 	res = -EINVAL;
 	if (!parse_options((char *)data, sbi)) {
 		printk(KERN_ERR "hfs: unable to parse mount options.\n");
 		goto bail;
 	}

 	sb->s_op = &hfs_super_operations;
 	sb->s_flags |= MS_NODIRATIME;
 	mutex_init(&sbi->bitmap_lock);

 	res = hfs_mdb_get(sb);
 	if (res) {
 		if (!silent)
 			printk(KERN_WARNING "hfs: can't find a HFS filesystem on dev %s.\n",
 				hfs_mdb_name(sb));
 		res = -EINVAL;
 		goto bail;
 	}

 	/* try to get the root inode */
 	hfs_find_init(HFS_SB(sb)->cat_tree, &fd);
 	res = hfs_cat_find_brec(sb, HFS_ROOT_CNID, &fd);
 	if (!res) {
 		if (fd.entrylength > sizeof(rec) || fd.entrylength < 0) {
 			res =  -EIO;
 			goto bail;
 		}
 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset, fd.entrylength);
 	}
 	if (res) {
 		hfs_find_exit(&fd);
 		goto bail_no_root;
 	}
 	res = -EINVAL;
 	root_inode = hfs_iget(sb, &fd.search_key->cat, &rec);
 	hfs_find_exit(&fd);
 	if (!root_inode)
 		goto bail_no_root;

 	sb->s_d_op = &hfs_dentry_operations;
 	res = -ENOMEM;
 	sb->s_root = d_make_root(root_inode);
 	if (!sb->s_root)
 		goto bail_no_root;

 	/* everything's okay */
 	return 0;

 bail_no_root:
 	printk(KERN_ERR "hfs: get root inode failed.\n");
 bail:
 	hfs_mdb_put(sb);
 	return res;
 }

 static struct dentry *hfs_mount(struct file_system_type *fs_type,
 		      int flags, const char *dev_name, void *data)
 {
 	return mount_bdev(fs_type, flags, dev_name, data, hfs_fill_super);
 }

 static struct file_system_type hfs_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "hfs",
 	.mount		= hfs_mount,
 	.kill_sb	= kill_block_super,
 	.fs_flags	= FS_REQUIRES_DEV,
 };

 static void hfs_init_once(void *p)
 {
 	struct hfs_inode_info *i = p;

 	inode_init_once(&i->vfs_inode);
 }

 static int __init init_hfs_fs(void)
 {
 	int err;

 	hfs_inode_cachep = kmem_cache_create("hfs_inode_cache",
 		sizeof(struct hfs_inode_info), 0, SLAB_HWCACHE_ALIGN,
 		hfs_init_once);
 	if (!hfs_inode_cachep)
 		return -ENOMEM;
 	err = register_filesystem(&hfs_fs_type);
 	if (err)
 		kmem_cache_destroy(hfs_inode_cachep);
 	return err;
 }

 static void __exit exit_hfs_fs(void)
 {
 	unregister_filesystem(&hfs_fs_type);
 	kmem_cache_destroy(hfs_inode_cachep);
 }

 module_init(init_hfs_fs)
 module_exit(exit_hfs_fs)
	/*
	* linux/fs/hfs/super.c
	*
	* Copyright (C) 1995-1997 Paul H. Hargrove
	* (C) 2003 Ardis Technologies <roman@ardistech.com>
	* This file may be distributed under the terms of the GNU General Public License.
	*
	* This file contains hfs_read_super(), some of the super_ops and
	* init_hfs_fs() and exit_hfs_fs(). The remaining super_ops are in
	* inode.c since they deal with inodes.
	*
	* Based on the minix file system code, (C) 1991, 1992 by Linus Torvalds
	*/

	#include <linux/module.h>
	#include <linux/blkdev.h>
	#include <linux/mount.h>
	#include <linux/init.h>
	#include <linux/nls.h>
	#include <linux/parser.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>
	#include <linux/vfs.h>

	#include "hfs_fs.h"
	#include "btree.h"

	static struct kmem_cache *hfs_inode_cachep;

	MODULE_LICENSE("GPL");

	/*
	* hfs_write_super()
	*
	* Description:
	* This function is called by the VFS only. When the filesystem
	* is mounted r/w it updates the MDB on disk.
	* Input Variable(s):
	* struct super_block *sb: Pointer to the hfs superblock
	* Output Variable(s):
	* NONE
	* Returns:
	* void
	* Preconditions:
	* 'sb' points to a "valid" (struct super_block).
	* Postconditions:
	* The MDB is marked 'unsuccessfully unmounted' by clearing bit 8 of drAtrb
	* (hfs_put_super() must set this flag!). Some MDB fields are updated
	* and the MDB buffer is written to disk by calling hfs_mdb_commit().
	*/
	static void hfs_write_super(struct super_block *sb)
	{
	sb->s_dirt = 0;

	/* sync everything to the buffers */
	hfs_mdb_commit(sb);
	}

	static int hfs_sync_fs(struct super_block *sb, int wait)
	{
	hfs_mdb_commit(sb);
	sb->s_dirt = 0;

	return 0;
	}

	/*
	* hfs_put_super()
	*
	* This is the put_super() entry in the super_operations structure for
	* HFS filesystems. The purpose is to release the resources
	* associated with the superblock sb.
	*/
	static void hfs_put_super(struct super_block *sb)
	{
	hfs_mdb_close(sb);
	/* release the MDB's resources */
	hfs_mdb_put(sb);
	}

	/*
	* hfs_statfs()
	*
	* This is the statfs() entry in the super_operations structure for
	* HFS filesystems. The purpose is to return various data about the
	* filesystem.
	*
	* changed f_files/f_ffree to reflect the fs_ablock/free_ablocks.
	*/
	static int hfs_statfs(struct dentry dentry, struct kstatfs buf)
	{
	struct super_block *sb = dentry->d_sb;
	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

	buf->f_type = HFS_SUPER_MAGIC;
	buf->f_bsize = sb->s_blocksize;
	buf->f_blocks = (u32)HFS_SB(sb)->fs_ablocks * HFS_SB(sb)->fs_div;
	buf->f_bfree = (u32)HFS_SB(sb)->free_ablocks * HFS_SB(sb)->fs_div;
	buf->f_bavail = buf->f_bfree;
	buf->f_files = HFS_SB(sb)->fs_ablocks;
	buf->f_ffree = HFS_SB(sb)->free_ablocks;
	buf->f_fsid.val[0] = (u32)id;
	buf->f_fsid.val[1] = (u32)(id >> 32);
	buf->f_namelen = HFS_NAMELEN;

	return 0;
	}

	static int hfs_remount(struct super_block sb, int flags, char *data)
	{
	*flags \|= MS_NODIRATIME;
	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
	return 0;
	if (!(*flags & MS_RDONLY)) {
	if (!(HFS_SB(sb)->mdb->drAtrb & cpu_to_be16(HFS_SB_ATTRIB_UNMNT))) {
	printk(KERN_WARNING "hfs: filesystem was not cleanly unmounted, "
	"running fsck.hfs is recommended. leaving read-only.\n");
	sb->s_flags \|= MS_RDONLY;
	*flags \|= MS_RDONLY;
	} else if (HFS_SB(sb)->mdb->drAtrb & cpu_to_be16(HFS_SB_ATTRIB_SLOCK)) {
	printk(KERN_WARNING "hfs: filesystem is marked locked, leaving read-only.\n");
	sb->s_flags \|= MS_RDONLY;
	*flags \|= MS_RDONLY;
	}
	}
	return 0;
	}

	static int hfs_show_options(struct seq_file seq, struct dentry root)
	{
	struct hfs_sb_info *sbi = HFS_SB(root->d_sb);

	if (sbi->s_creator != cpu_to_be32(0x3f3f3f3f))
	seq_printf(seq, ",creator=%.4s", (char *)&sbi->s_creator);
	if (sbi->s_type != cpu_to_be32(0x3f3f3f3f))
	seq_printf(seq, ",type=%.4s", (char *)&sbi->s_type);
	seq_printf(seq, ",uid=%u,gid=%u", sbi->s_uid, sbi->s_gid);
	if (sbi->s_file_umask != 0133)
	seq_printf(seq, ",file_umask=%o", sbi->s_file_umask);
	if (sbi->s_dir_umask != 0022)
	seq_printf(seq, ",dir_umask=%o", sbi->s_dir_umask);
	if (sbi->part >= 0)
	seq_printf(seq, ",part=%u", sbi->part);
	if (sbi->session >= 0)
	seq_printf(seq, ",session=%u", sbi->session);
	if (sbi->nls_disk)
	seq_printf(seq, ",codepage=%s", sbi->nls_disk->charset);
	if (sbi->nls_io)
	seq_printf(seq, ",iocharset=%s", sbi->nls_io->charset);
	if (sbi->s_quiet)
	seq_printf(seq, ",quiet");
	return 0;
	}

	static struct inode hfs_alloc_inode(struct super_block sb)
	{
	struct hfs_inode_info *i;

	i = kmem_cache_alloc(hfs_inode_cachep, GFP_KERNEL);
	return i ? &i->vfs_inode : NULL;
	}

	static void hfs_i_callback(struct rcu_head *head)
	{
	struct inode *inode = container_of(head, struct inode, i_rcu);
	kmem_cache_free(hfs_inode_cachep, HFS_I(inode));
	}

	static void hfs_destroy_inode(struct inode *inode)
	{
	call_rcu(&inode->i_rcu, hfs_i_callback);
	}

	static const struct super_operations hfs_super_operations = {
	.alloc_inode = hfs_alloc_inode,
	.destroy_inode = hfs_destroy_inode,
	.write_inode = hfs_write_inode,
	.evict_inode = hfs_evict_inode,
	.put_super = hfs_put_super,
	.write_super = hfs_write_super,
	.sync_fs = hfs_sync_fs,
	.statfs = hfs_statfs,
	.remount_fs = hfs_remount,
	.show_options = hfs_show_options,
	};

	enum {
	opt_uid, opt_gid, opt_umask, opt_file_umask, opt_dir_umask,
	opt_part, opt_session, opt_type, opt_creator, opt_quiet,
	opt_codepage, opt_iocharset,
	opt_err
	};

	static const match_table_t tokens = {
	{ opt_uid, "uid=%u" },
	{ opt_gid, "gid=%u" },
	{ opt_umask, "umask=%o" },
	{ opt_file_umask, "file_umask=%o" },
	{ opt_dir_umask, "dir_umask=%o" },
	{ opt_part, "part=%u" },
	{ opt_session, "session=%u" },
	{ opt_type, "type=%s" },
	{ opt_creator, "creator=%s" },
	{ opt_quiet, "quiet" },
	{ opt_codepage, "codepage=%s" },
	{ opt_iocharset, "iocharset=%s" },
	{ opt_err, NULL }
	};

	static inline int match_fourchar(substring_t arg, u32 result)
	{
	if (arg->to - arg->from != 4)
	return -EINVAL;
	memcpy(result, arg->from, 4);
	return 0;
	}

	/*
	* parse_options()
	*
	* adapted from linux/fs/msdos/inode.c written 1992,93 by Werner Almesberger
	* This function is called by hfs_read_super() to parse the mount options.
	*/
	static int parse_options(char options, struct hfs_sb_info hsb)
	{
	char *p;
	substring_t args[MAX_OPT_ARGS];
	int tmp, token;

	/* initialize the sb with defaults */
	hsb->s_uid = current_uid();
	hsb->s_gid = current_gid();
	hsb->s_file_umask = 0133;
	hsb->s_dir_umask = 0022;
	hsb->s_type = hsb->s_creator = cpu_to_be32(0x3f3f3f3f); /* == '????' */
	hsb->s_quiet = 0;
	hsb->part = -1;
	hsb->session = -1;

	if (!options)
	return 1;

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

	token = match_token(p, tokens, args);
	switch (token) {
	case opt_uid:
	if (match_int(&args[0], &tmp)) {
	printk(KERN_ERR "hfs: uid requires an argument\n");
	return 0;
	}
	hsb->s_uid = (uid_t)tmp;
	break;
	case opt_gid:
	if (match_int(&args[0], &tmp)) {
	printk(KERN_ERR "hfs: gid requires an argument\n");
	return 0;
	}
	hsb->s_gid = (gid_t)tmp;
	break;
	case opt_umask:
	if (match_octal(&args[0], &tmp)) {
	printk(KERN_ERR "hfs: umask requires a value\n");
	return 0;
	}
	hsb->s_file_umask = (umode_t)tmp;
	hsb->s_dir_umask = (umode_t)tmp;
	break;
	case opt_file_umask:
	if (match_octal(&args[0], &tmp)) {
	printk(KERN_ERR "hfs: file_umask requires a value\n");
	return 0;
	}
	hsb->s_file_umask = (umode_t)tmp;
	break;
	case opt_dir_umask:
	if (match_octal(&args[0], &tmp)) {
	printk(KERN_ERR "hfs: dir_umask requires a value\n");
	return 0;
	}
	hsb->s_dir_umask = (umode_t)tmp;
	break;
	case opt_part:
	if (match_int(&args[0], &hsb->part)) {
	printk(KERN_ERR "hfs: part requires an argument\n");
	return 0;
	}
	break;
	case opt_session:
	if (match_int(&args[0], &hsb->session)) {
	printk(KERN_ERR "hfs: session requires an argument\n");
	return 0;
	}
	break;
	case opt_type:
	if (match_fourchar(&args[0], &hsb->s_type)) {
	printk(KERN_ERR "hfs: type requires a 4 character value\n");
	return 0;
	}
	break;
	case opt_creator:
	if (match_fourchar(&args[0], &hsb->s_creator)) {
	printk(KERN_ERR "hfs: creator requires a 4 character value\n");
	return 0;
	}
	break;
	case opt_quiet:
	hsb->s_quiet = 1;
	break;
	case opt_codepage:
	if (hsb->nls_disk) {
	printk(KERN_ERR "hfs: unable to change codepage\n");
	return 0;
	}
	p = match_strdup(&args[0]);
	if (p)
	hsb->nls_disk = load_nls(p);
	if (!hsb->nls_disk) {
	printk(KERN_ERR "hfs: unable to load codepage \"%s\"\n", p);
	kfree(p);
	return 0;
	}
	kfree(p);
	break;
	case opt_iocharset:
	if (hsb->nls_io) {
	printk(KERN_ERR "hfs: unable to change iocharset\n");
	return 0;
	}
	p = match_strdup(&args[0]);
	if (p)
	hsb->nls_io = load_nls(p);
	if (!hsb->nls_io) {
	printk(KERN_ERR "hfs: unable to load iocharset \"%s\"\n", p);
	kfree(p);
	return 0;
	}
	kfree(p);
	break;
	default:
	return 0;
	}
	}

	if (hsb->nls_disk && !hsb->nls_io) {
	hsb->nls_io = load_nls_default();
	if (!hsb->nls_io) {
	printk(KERN_ERR "hfs: unable to load default iocharset\n");
	return 0;
	}
	}
	hsb->s_dir_umask &= 0777;
	hsb->s_file_umask &= 0577;

	return 1;
	}

	/*
	* hfs_read_super()
	*
	* This is the function that is responsible for mounting an HFS
	* filesystem. It performs all the tasks necessary to get enough data
	* from the disk to read the root inode. This includes parsing the
	* mount options, dealing with Macintosh partitions, reading the
	* superblock and the allocation bitmap blocks, calling
	* hfs_btree_init() to get the necessary data about the extents and
	* catalog B-trees and, finally, reading the root inode into memory.
	*/
	static int hfs_fill_super(struct super_block sb, void data, int silent)
	{
	struct hfs_sb_info *sbi;
	struct hfs_find_data fd;
	hfs_cat_rec rec;
	struct inode *root_inode;
	int res;

	sbi = kzalloc(sizeof(struct hfs_sb_info), GFP_KERNEL);
	if (!sbi)
	return -ENOMEM;

	sb->s_fs_info = sbi;

	res = -EINVAL;
	if (!parse_options((char *)data, sbi)) {
	printk(KERN_ERR "hfs: unable to parse mount options.\n");
	goto bail;
	}

	sb->s_op = &hfs_super_operations;
	sb->s_flags \|= MS_NODIRATIME;
	mutex_init(&sbi->bitmap_lock);

	res = hfs_mdb_get(sb);
	if (res) {
	if (!silent)
	printk(KERN_WARNING "hfs: can't find a HFS filesystem on dev %s.\n",
	hfs_mdb_name(sb));
	res = -EINVAL;
	goto bail;
	}

	/* try to get the root inode */
	hfs_find_init(HFS_SB(sb)->cat_tree, &fd);
	res = hfs_cat_find_brec(sb, HFS_ROOT_CNID, &fd);
	if (!res) {
	if (fd.entrylength > sizeof(rec) \|\| fd.entrylength < 0) {
	res = -EIO;
	goto bail;
	}
	hfs_bnode_read(fd.bnode, &rec, fd.entryoffset, fd.entrylength);
	}
	if (res) {
	hfs_find_exit(&fd);
	goto bail_no_root;
	}
	res = -EINVAL;
	root_inode = hfs_iget(sb, &fd.search_key->cat, &rec);
	hfs_find_exit(&fd);
	if (!root_inode)
	goto bail_no_root;

	sb->s_d_op = &hfs_dentry_operations;
	res = -ENOMEM;
	sb->s_root = d_make_root(root_inode);
	if (!sb->s_root)
	goto bail_no_root;

	/* everything's okay */
	return 0;

	bail_no_root:
	printk(KERN_ERR "hfs: get root inode failed.\n");
	bail:
	hfs_mdb_put(sb);
	return res;
	}

	static struct dentry hfs_mount(struct file_system_type fs_type,
	int flags, const char dev_name, void data)
	{
	return mount_bdev(fs_type, flags, dev_name, data, hfs_fill_super);
	}

	static struct file_system_type hfs_fs_type = {
	.owner = THIS_MODULE,
	.name = "hfs",
	.mount = hfs_mount,
	.kill_sb = kill_block_super,
	.fs_flags = FS_REQUIRES_DEV,
	};

	static void hfs_init_once(void *p)
	{
	struct hfs_inode_info *i = p;

	inode_init_once(&i->vfs_inode);
	}

	static int __init init_hfs_fs(void)
	{
	int err;

	hfs_inode_cachep = kmem_cache_create("hfs_inode_cache",
	sizeof(struct hfs_inode_info), 0, SLAB_HWCACHE_ALIGN,
	hfs_init_once);
	if (!hfs_inode_cachep)
	return -ENOMEM;
	err = register_filesystem(&hfs_fs_type);
	if (err)
	kmem_cache_destroy(hfs_inode_cachep);
	return err;
	}

	static void __exit exit_hfs_fs(void)
	{
	unregister_filesystem(&hfs_fs_type);
	kmem_cache_destroy(hfs_inode_cachep);
	}

	module_init(init_hfs_fs)
	module_exit(exit_hfs_fs)