fs/qnx4/inode.c - kernel/msm-4.9 - Gitiles

 /*
  * QNX4 file system, Linux implementation.
  *
  * Version : 0.2.1
  *
  * Using parts of the xiafs filesystem.
  *
  * History :
  *
  * 01-06-1998 by Richard Frowijn : first release.
  * 20-06-1998 by Frank Denis : Linux 2.1.99+ support, boot signature, misc.
  * 30-06-1998 by Frank Denis : first step to write inodes.
  */

 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
 #include <linux/qnx4_fs.h>
 #include <linux/init.h>
 #include <linux/highuid.h>
 #include <linux/smp_lock.h>
 #include <linux/pagemap.h>
 #include <linux/buffer_head.h>
 #include <linux/vfs.h>
 #include <asm/uaccess.h>

 #define QNX4_VERSION  4
 #define QNX4_BMNAME   ".bitmap"

 static const struct super_operations qnx4_sops;

 #ifdef CONFIG_QNX4FS_RW

 int qnx4_sync_inode(struct inode *inode)
 {
 	int err = 0;
 # if 0
 	struct buffer_head *bh;

    	bh = qnx4_update_inode(inode);
 	if (bh && buffer_dirty(bh))
 	{
 		sync_dirty_buffer(bh);
 		if (buffer_req(bh) && !buffer_uptodate(bh))
 		{
 			printk ("IO error syncing qnx4 inode [%s:%08lx]\n",
 				inode->i_sb->s_id, inode->i_ino);
 			err = -1;
 		}
 	        brelse (bh);
 	} else if (!bh) {
 		err = -1;
 	}
 # endif

 	return err;
 }

 static void qnx4_delete_inode(struct inode *inode)
 {
 	QNX4DEBUG(("qnx4: deleting inode [%lu]\n", (unsigned long) inode->i_ino));
 	truncate_inode_pages(&inode->i_data, 0);
 	inode->i_size = 0;
 	qnx4_truncate(inode);
 	lock_kernel();
 	qnx4_free_inode(inode);
 	unlock_kernel();
 }

 static void qnx4_write_super(struct super_block *sb)
 {
 	lock_kernel();
 	QNX4DEBUG(("qnx4: write_super\n"));
 	sb->s_dirt = 0;
 	unlock_kernel();
 }

 static int qnx4_write_inode(struct inode *inode, int unused)
 {
 	struct qnx4_inode_entry *raw_inode;
 	int block, ino;
 	struct buffer_head *bh;
 	ino = inode->i_ino;

 	QNX4DEBUG(("qnx4: write inode 1.\n"));
 	if (inode->i_nlink == 0) {
 		return 0;
 	}
 	if (!ino) {
 		printk("qnx4: bad inode number on dev %s: %d is out of range\n",
 		       inode->i_sb->s_id, ino);
 		return -EIO;
 	}
 	QNX4DEBUG(("qnx4: write inode 2.\n"));
 	block = ino / QNX4_INODES_PER_BLOCK;
 	lock_kernel();
 	if (!(bh = sb_bread(inode->i_sb, block))) {
 		printk("qnx4: major problem: unable to read inode from dev "
 		       "%s\n", inode->i_sb->s_id);
 		unlock_kernel();
 		return -EIO;
 	}
 	raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
 	    (ino % QNX4_INODES_PER_BLOCK);
 	raw_inode->di_mode  = cpu_to_le16(inode->i_mode);
 	raw_inode->di_uid   = cpu_to_le16(fs_high2lowuid(inode->i_uid));
 	raw_inode->di_gid   = cpu_to_le16(fs_high2lowgid(inode->i_gid));
 	raw_inode->di_nlink = cpu_to_le16(inode->i_nlink);
 	raw_inode->di_size  = cpu_to_le32(inode->i_size);
 	raw_inode->di_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
 	raw_inode->di_atime = cpu_to_le32(inode->i_atime.tv_sec);
 	raw_inode->di_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
 	raw_inode->di_first_xtnt.xtnt_size = cpu_to_le32(inode->i_blocks);
 	mark_buffer_dirty(bh);
 	brelse(bh);
 	unlock_kernel();
 	return 0;
 }

 #endif

 static void qnx4_put_super(struct super_block *sb);
 static struct inode *qnx4_alloc_inode(struct super_block *sb);
 static void qnx4_destroy_inode(struct inode *inode);
 static int qnx4_remount(struct super_block *sb, int *flags, char *data);
 static int qnx4_statfs(struct dentry *, struct kstatfs *);

 static const struct super_operations qnx4_sops =
 {
 	.alloc_inode	= qnx4_alloc_inode,
 	.destroy_inode	= qnx4_destroy_inode,
 	.put_super	= qnx4_put_super,
 	.statfs		= qnx4_statfs,
 	.remount_fs	= qnx4_remount,
 #ifdef CONFIG_QNX4FS_RW
 	.write_inode	= qnx4_write_inode,
 	.delete_inode	= qnx4_delete_inode,
 	.write_super	= qnx4_write_super,
 #endif
 };

 static int qnx4_remount(struct super_block *sb, int *flags, char *data)
 {
 	struct qnx4_sb_info *qs;

 	qs = qnx4_sb(sb);
 	qs->Version = QNX4_VERSION;
 #ifndef CONFIG_QNX4FS_RW
 	*flags |= MS_RDONLY;
 #endif
 	if (*flags & MS_RDONLY) {
 		return 0;
 	}

 	mark_buffer_dirty(qs->sb_buf);

 	return 0;
 }

 static struct buffer_head *qnx4_getblk(struct inode *inode, int nr,
 				       int create)
 {
 	struct buffer_head *result = NULL;

 	if ( nr >= 0 )
 		nr = qnx4_block_map( inode, nr );
 	if (nr) {
 		result = sb_getblk(inode->i_sb, nr);
 		return result;
 	}
 	if (!create) {
 		return NULL;
 	}
 #if 0
 	tmp = qnx4_new_block(inode->i_sb);
 	if (!tmp) {
 		return NULL;
 	}
 	result = sb_getblk(inode->i_sb, tmp);
 	if (tst) {
 		qnx4_free_block(inode->i_sb, tmp);
 		brelse(result);
 		goto repeat;
 	}
 	tst = tmp;
 #endif
 	inode->i_ctime = CURRENT_TIME_SEC;
 	mark_inode_dirty(inode);
 	return result;
 }

 struct buffer_head *qnx4_bread(struct inode *inode, int block, int create)
 {
 	struct buffer_head *bh;

 	bh = qnx4_getblk(inode, block, create);
 	if (!bh || buffer_uptodate(bh)) {
 		return bh;
 	}
 	ll_rw_block(READ, 1, &bh);
 	wait_on_buffer(bh);
 	if (buffer_uptodate(bh)) {
 		return bh;
 	}
 	brelse(bh);

 	return NULL;
 }

 static int qnx4_get_block( struct inode *inode, sector_t iblock, struct buffer_head *bh, int create )
 {
 	unsigned long phys;

 	QNX4DEBUG(("qnx4: qnx4_get_block inode=[%ld] iblock=[%ld]\n",inode->i_ino,iblock));

 	phys = qnx4_block_map( inode, iblock );
 	if ( phys ) {
 		// logical block is before EOF
 		map_bh(bh, inode->i_sb, phys);
 	} else if ( create ) {
 		// to be done.
 	}
 	return 0;
 }

 unsigned long qnx4_block_map( struct inode *inode, long iblock )
 {
 	int ix;
 	long offset, i_xblk;
 	unsigned long block = 0;
 	struct buffer_head *bh = NULL;
 	struct qnx4_xblk *xblk = NULL;
 	struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
 	u16 nxtnt = le16_to_cpu(qnx4_inode->di_num_xtnts);

 	if ( iblock < le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size) ) {
 		// iblock is in the first extent. This is easy.
 		block = le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_blk) + iblock - 1;
 	} else {
 		// iblock is beyond first extent. We have to follow the extent chain.
 		i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
 		offset = iblock - le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size);
 		ix = 0;
 		while ( --nxtnt > 0 ) {
 			if ( ix == 0 ) {
 				// read next xtnt block.
 				bh = sb_bread(inode->i_sb, i_xblk - 1);
 				if ( !bh ) {
 					QNX4DEBUG(("qnx4: I/O error reading xtnt block [%ld])\n", i_xblk - 1));
 					return -EIO;
 				}
 				xblk = (struct qnx4_xblk*)bh->b_data;
 				if ( memcmp( xblk->xblk_signature, "IamXblk", 7 ) ) {
 					QNX4DEBUG(("qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
 					return -EIO;
 				}
 			}
 			if ( offset < le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size) ) {
 				// got it!
 				block = le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_blk) + offset - 1;
 				break;
 			}
 			offset -= le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size);
 			if ( ++ix >= xblk->xblk_num_xtnts ) {
 				i_xblk = le32_to_cpu(xblk->xblk_next_xblk);
 				ix = 0;
 				brelse( bh );
 				bh = NULL;
 			}
 		}
 		if ( bh )
 			brelse( bh );
 	}

 	QNX4DEBUG(("qnx4: mapping block %ld of inode %ld = %ld\n",iblock,inode->i_ino,block));
 	return block;
 }

 static int qnx4_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;

 	lock_kernel();

 	buf->f_type    = sb->s_magic;
 	buf->f_bsize   = sb->s_blocksize;
 	buf->f_blocks  = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size) * 8;
 	buf->f_bfree   = qnx4_count_free_blocks(sb);
 	buf->f_bavail  = buf->f_bfree;
 	buf->f_namelen = QNX4_NAME_MAX;

 	unlock_kernel();

 	return 0;
 }

 /*
  * Check the root directory of the filesystem to make sure
  * it really _is_ a qnx4 filesystem, and to check the size
  * of the directory entry.
  */
 static const char *qnx4_checkroot(struct super_block *sb)
 {
 	struct buffer_head *bh;
 	struct qnx4_inode_entry *rootdir;
 	int rd, rl;
 	int i, j;
 	int found = 0;

 	if (*(qnx4_sb(sb)->sb->RootDir.di_fname) != '/') {
 		return "no qnx4 filesystem (no root dir).";
 	} else {
 		QNX4DEBUG(("QNX4 filesystem found on dev %s.\n", sb->s_id));
 		rd = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_blk) - 1;
 		rl = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_size);
 		for (j = 0; j < rl; j++) {
 			bh = sb_bread(sb, rd + j);	/* root dir, first block */
 			if (bh == NULL) {
 				return "unable to read root entry.";
 			}
 			for (i = 0; i < QNX4_INODES_PER_BLOCK; i++) {
 				rootdir = (struct qnx4_inode_entry *) (bh->b_data + i * QNX4_DIR_ENTRY_SIZE);
 				if (rootdir->di_fname != NULL) {
 					QNX4DEBUG(("Rootdir entry found : [%s]\n", rootdir->di_fname));
 					if (!strncmp(rootdir->di_fname, QNX4_BMNAME, sizeof QNX4_BMNAME)) {
 						found = 1;
 						qnx4_sb(sb)->BitMap = kmalloc( sizeof( struct qnx4_inode_entry ), GFP_KERNEL );
 						if (!qnx4_sb(sb)->BitMap) {
 							brelse (bh);
 							return "not enough memory for bitmap inode";
 						}
 						memcpy( qnx4_sb(sb)->BitMap, rootdir, sizeof( struct qnx4_inode_entry ) );	/* keep bitmap inode known */
 						break;
 					}
 				}
 			}
 			brelse(bh);
 			if (found != 0) {
 				break;
 			}
 		}
 		if (found == 0) {
 			return "bitmap file not found.";
 		}
 	}
 	return NULL;
 }

 static int qnx4_fill_super(struct super_block *s, void *data, int silent)
 {
 	struct buffer_head *bh;
 	struct inode *root;
 	const char *errmsg;
 	struct qnx4_sb_info *qs;
 	int ret = -EINVAL;

 	qs = kzalloc(sizeof(struct qnx4_sb_info), GFP_KERNEL);
 	if (!qs)
 		return -ENOMEM;
 	s->s_fs_info = qs;

 	sb_set_blocksize(s, QNX4_BLOCK_SIZE);

 	/* Check the superblock signature. Since the qnx4 code is
 	   dangerous, we should leave as quickly as possible
 	   if we don't belong here... */
 	bh = sb_bread(s, 1);
 	if (!bh) {
 		printk("qnx4: unable to read the superblock\n");
 		goto outnobh;
 	}
 	if ( le32_to_cpup((__le32*) bh->b_data) != QNX4_SUPER_MAGIC ) {
 		if (!silent)
 			printk("qnx4: wrong fsid in superblock.\n");
 		goto out;
 	}
 	s->s_op = &qnx4_sops;
 	s->s_magic = QNX4_SUPER_MAGIC;
 #ifndef CONFIG_QNX4FS_RW
 	s->s_flags |= MS_RDONLY;	/* Yup, read-only yet */
 #endif
 	qnx4_sb(s)->sb_buf = bh;
 	qnx4_sb(s)->sb = (struct qnx4_super_block *) bh->b_data;


  	/* check before allocating dentries, inodes, .. */
 	errmsg = qnx4_checkroot(s);
 	if (errmsg != NULL) {
  		if (!silent)
  			printk("qnx4: %s\n", errmsg);
 		goto out;
 	}

  	/* does root not have inode number QNX4_ROOT_INO ?? */
 	root = qnx4_iget(s, QNX4_ROOT_INO * QNX4_INODES_PER_BLOCK);
 	if (IS_ERR(root)) {
  		printk("qnx4: get inode failed\n");
 		ret = PTR_ERR(root);
  		goto out;
  	}

 	ret = -ENOMEM;
  	s->s_root = d_alloc_root(root);
  	if (s->s_root == NULL)
  		goto outi;

 	brelse(bh);

 	return 0;

       outi:
 	iput(root);
       out:
 	brelse(bh);
       outnobh:
 	kfree(qs);
 	s->s_fs_info = NULL;
 	return ret;
 }

 static void qnx4_put_super(struct super_block *sb)
 {
 	struct qnx4_sb_info *qs = qnx4_sb(sb);
 	kfree( qs->BitMap );
 	kfree( qs );
 	sb->s_fs_info = NULL;
 	return;
 }

 static int qnx4_writepage(struct page *page, struct writeback_control *wbc)
 {
 	return block_write_full_page(page,qnx4_get_block, wbc);
 }

 static int qnx4_readpage(struct file *file, struct page *page)
 {
 	return block_read_full_page(page,qnx4_get_block);
 }

 static int qnx4_write_begin(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len, unsigned flags,
 			struct page **pagep, void **fsdata)
 {
 	struct qnx4_inode_info *qnx4_inode = qnx4_i(mapping->host);
 	*pagep = NULL;
 	return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
 				qnx4_get_block,
 				&qnx4_inode->mmu_private);
 }
 static sector_t qnx4_bmap(struct address_space *mapping, sector_t block)
 {
 	return generic_block_bmap(mapping,block,qnx4_get_block);
 }
 static const struct address_space_operations qnx4_aops = {
 	.readpage	= qnx4_readpage,
 	.writepage	= qnx4_writepage,
 	.sync_page	= block_sync_page,
 	.write_begin	= qnx4_write_begin,
 	.write_end	= generic_write_end,
 	.bmap		= qnx4_bmap
 };

 struct inode *qnx4_iget(struct super_block *sb, unsigned long ino)
 {
 	struct buffer_head *bh;
 	struct qnx4_inode_entry *raw_inode;
 	int block;
 	struct qnx4_inode_entry *qnx4_inode;
 	struct inode *inode;

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

 	qnx4_inode = qnx4_raw_inode(inode);
 	inode->i_mode = 0;

 	QNX4DEBUG(("Reading inode : [%d]\n", ino));
 	if (!ino) {
 		printk(KERN_ERR "qnx4: bad inode number on dev %s: %lu is "
 				"out of range\n",
 		       sb->s_id, ino);
 		iget_failed(inode);
 		return ERR_PTR(-EIO);
 	}
 	block = ino / QNX4_INODES_PER_BLOCK;

 	if (!(bh = sb_bread(sb, block))) {
 		printk("qnx4: major problem: unable to read inode from dev "
 		       "%s\n", sb->s_id);
 		iget_failed(inode);
 		return ERR_PTR(-EIO);
 	}
 	raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
 	    (ino % QNX4_INODES_PER_BLOCK);

 	inode->i_mode    = le16_to_cpu(raw_inode->di_mode);
 	inode->i_uid     = (uid_t)le16_to_cpu(raw_inode->di_uid);
 	inode->i_gid     = (gid_t)le16_to_cpu(raw_inode->di_gid);
 	inode->i_nlink   = le16_to_cpu(raw_inode->di_nlink);
 	inode->i_size    = le32_to_cpu(raw_inode->di_size);
 	inode->i_mtime.tv_sec   = le32_to_cpu(raw_inode->di_mtime);
 	inode->i_mtime.tv_nsec = 0;
 	inode->i_atime.tv_sec   = le32_to_cpu(raw_inode->di_atime);
 	inode->i_atime.tv_nsec = 0;
 	inode->i_ctime.tv_sec   = le32_to_cpu(raw_inode->di_ctime);
 	inode->i_ctime.tv_nsec = 0;
 	inode->i_blocks  = le32_to_cpu(raw_inode->di_first_xtnt.xtnt_size);

 	memcpy(qnx4_inode, raw_inode, QNX4_DIR_ENTRY_SIZE);
 	if (S_ISREG(inode->i_mode)) {
 		inode->i_op = &qnx4_file_inode_operations;
 		inode->i_fop = &qnx4_file_operations;
 		inode->i_mapping->a_ops = &qnx4_aops;
 		qnx4_i(inode)->mmu_private = inode->i_size;
 	} else if (S_ISDIR(inode->i_mode)) {
 		inode->i_op = &qnx4_dir_inode_operations;
 		inode->i_fop = &qnx4_dir_operations;
 	} else if (S_ISLNK(inode->i_mode)) {
 		inode->i_op = &page_symlink_inode_operations;
 		inode->i_mapping->a_ops = &qnx4_aops;
 		qnx4_i(inode)->mmu_private = inode->i_size;
 	} else {
 		printk(KERN_ERR "qnx4: bad inode %lu on dev %s\n",
 			ino, sb->s_id);
 		iget_failed(inode);
 		brelse(bh);
 		return ERR_PTR(-EIO);
 	}
 	brelse(bh);
 	unlock_new_inode(inode);
 	return inode;
 }

 static struct kmem_cache *qnx4_inode_cachep;

 static struct inode *qnx4_alloc_inode(struct super_block *sb)
 {
 	struct qnx4_inode_info *ei;
 	ei = kmem_cache_alloc(qnx4_inode_cachep, GFP_KERNEL);
 	if (!ei)
 		return NULL;
 	return &ei->vfs_inode;
 }

 static void qnx4_destroy_inode(struct inode *inode)
 {
 	kmem_cache_free(qnx4_inode_cachep, qnx4_i(inode));
 }

 static void init_once(void *foo)
 {
 	struct qnx4_inode_info *ei = (struct qnx4_inode_info *) foo;

 	inode_init_once(&ei->vfs_inode);
 }

 static int init_inodecache(void)
 {
 	qnx4_inode_cachep = kmem_cache_create("qnx4_inode_cache",
 					     sizeof(struct qnx4_inode_info),
 					     0, (SLAB_RECLAIM_ACCOUNT|
 						SLAB_MEM_SPREAD),
 					     init_once);
 	if (qnx4_inode_cachep == NULL)
 		return -ENOMEM;
 	return 0;
 }

 static void destroy_inodecache(void)
 {
 	kmem_cache_destroy(qnx4_inode_cachep);
 }

 static int qnx4_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, qnx4_fill_super,
 			   mnt);
 }

 static struct file_system_type qnx4_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "qnx4",
 	.get_sb		= qnx4_get_sb,
 	.kill_sb	= kill_block_super,
 	.fs_flags	= FS_REQUIRES_DEV,
 };

 static int __init init_qnx4_fs(void)
 {
 	int err;

 	err = init_inodecache();
 	if (err)
 		return err;

 	err = register_filesystem(&qnx4_fs_type);
 	if (err) {
 		destroy_inodecache();
 		return err;
 	}

 	printk("QNX4 filesystem 0.2.3 registered.\n");
 	return 0;
 }

 static void __exit exit_qnx4_fs(void)
 {
 	unregister_filesystem(&qnx4_fs_type);
 	destroy_inodecache();
 }

 module_init(init_qnx4_fs)
 module_exit(exit_qnx4_fs)
 MODULE_LICENSE("GPL");
	/*
	* QNX4 file system, Linux implementation.
	*
	* Version : 0.2.1
	*
	* Using parts of the xiafs filesystem.
	*
	* History :
	*
	* 01-06-1998 by Richard Frowijn : first release.
	* 20-06-1998 by Frank Denis : Linux 2.1.99+ support, boot signature, misc.
	* 30-06-1998 by Frank Denis : first step to write inodes.
	*/

	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/string.h>
	#include <linux/errno.h>
	#include <linux/slab.h>
	#include <linux/fs.h>
	#include <linux/qnx4_fs.h>
	#include <linux/init.h>
	#include <linux/highuid.h>
	#include <linux/smp_lock.h>
	#include <linux/pagemap.h>
	#include <linux/buffer_head.h>
	#include <linux/vfs.h>
	#include <asm/uaccess.h>

	#define QNX4_VERSION 4
	#define QNX4_BMNAME ".bitmap"

	static const struct super_operations qnx4_sops;

	#ifdef CONFIG_QNX4FS_RW

	int qnx4_sync_inode(struct inode *inode)
	{
	int err = 0;
	# if 0
	struct buffer_head *bh;

	bh = qnx4_update_inode(inode);
	if (bh && buffer_dirty(bh))
	{
	sync_dirty_buffer(bh);
	if (buffer_req(bh) && !buffer_uptodate(bh))
	{
	printk ("IO error syncing qnx4 inode [%s:%08lx]\n",
	inode->i_sb->s_id, inode->i_ino);
	err = -1;
	}
	brelse (bh);
	} else if (!bh) {
	err = -1;
	}
	# endif

	return err;
	}

	static void qnx4_delete_inode(struct inode *inode)
	{
	QNX4DEBUG(("qnx4: deleting inode [%lu]\n", (unsigned long) inode->i_ino));
	truncate_inode_pages(&inode->i_data, 0);
	inode->i_size = 0;
	qnx4_truncate(inode);
	lock_kernel();
	qnx4_free_inode(inode);
	unlock_kernel();
	}

	static void qnx4_write_super(struct super_block *sb)
	{
	lock_kernel();
	QNX4DEBUG(("qnx4: write_super\n"));
	sb->s_dirt = 0;
	unlock_kernel();
	}

	static int qnx4_write_inode(struct inode *inode, int unused)
	{
	struct qnx4_inode_entry *raw_inode;
	int block, ino;
	struct buffer_head *bh;
	ino = inode->i_ino;

	QNX4DEBUG(("qnx4: write inode 1.\n"));
	if (inode->i_nlink == 0) {
	return 0;
	}
	if (!ino) {
	printk("qnx4: bad inode number on dev %s: %d is out of range\n",
	inode->i_sb->s_id, ino);
	return -EIO;
	}
	QNX4DEBUG(("qnx4: write inode 2.\n"));
	block = ino / QNX4_INODES_PER_BLOCK;
	lock_kernel();
	if (!(bh = sb_bread(inode->i_sb, block))) {
	printk("qnx4: major problem: unable to read inode from dev "
	"%s\n", inode->i_sb->s_id);
	unlock_kernel();
	return -EIO;
	}
	raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
	(ino % QNX4_INODES_PER_BLOCK);
	raw_inode->di_mode = cpu_to_le16(inode->i_mode);
	raw_inode->di_uid = cpu_to_le16(fs_high2lowuid(inode->i_uid));
	raw_inode->di_gid = cpu_to_le16(fs_high2lowgid(inode->i_gid));
	raw_inode->di_nlink = cpu_to_le16(inode->i_nlink);
	raw_inode->di_size = cpu_to_le32(inode->i_size);
	raw_inode->di_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
	raw_inode->di_atime = cpu_to_le32(inode->i_atime.tv_sec);
	raw_inode->di_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
	raw_inode->di_first_xtnt.xtnt_size = cpu_to_le32(inode->i_blocks);
	mark_buffer_dirty(bh);
	brelse(bh);
	unlock_kernel();
	return 0;
	}

	#endif

	static void qnx4_put_super(struct super_block *sb);
	static struct inode qnx4_alloc_inode(struct super_block sb);
	static void qnx4_destroy_inode(struct inode *inode);
	static int qnx4_remount(struct super_block sb, int flags, char *data);
	static int qnx4_statfs(struct dentry , struct kstatfs );

	static const struct super_operations qnx4_sops =
	{
	.alloc_inode = qnx4_alloc_inode,
	.destroy_inode = qnx4_destroy_inode,
	.put_super = qnx4_put_super,
	.statfs = qnx4_statfs,
	.remount_fs = qnx4_remount,
	#ifdef CONFIG_QNX4FS_RW
	.write_inode = qnx4_write_inode,
	.delete_inode = qnx4_delete_inode,
	.write_super = qnx4_write_super,
	#endif
	};

	static int qnx4_remount(struct super_block sb, int flags, char *data)
	{
	struct qnx4_sb_info *qs;

	qs = qnx4_sb(sb);
	qs->Version = QNX4_VERSION;
	#ifndef CONFIG_QNX4FS_RW
	*flags \|= MS_RDONLY;
	#endif
	if (*flags & MS_RDONLY) {
	return 0;
	}

	mark_buffer_dirty(qs->sb_buf);

	return 0;
	}

	static struct buffer_head qnx4_getblk(struct inode inode, int nr,
	int create)
	{
	struct buffer_head *result = NULL;

	if ( nr >= 0 )
	nr = qnx4_block_map( inode, nr );
	if (nr) {
	result = sb_getblk(inode->i_sb, nr);
	return result;
	}
	if (!create) {
	return NULL;
	}
	#if 0
	tmp = qnx4_new_block(inode->i_sb);
	if (!tmp) {
	return NULL;
	}
	result = sb_getblk(inode->i_sb, tmp);
	if (tst) {
	qnx4_free_block(inode->i_sb, tmp);
	brelse(result);
	goto repeat;
	}
	tst = tmp;
	#endif
	inode->i_ctime = CURRENT_TIME_SEC;
	mark_inode_dirty(inode);
	return result;
	}

	struct buffer_head qnx4_bread(struct inode inode, int block, int create)
	{
	struct buffer_head *bh;

	bh = qnx4_getblk(inode, block, create);
	if (!bh \|\| buffer_uptodate(bh)) {
	return bh;
	}
	ll_rw_block(READ, 1, &bh);
	wait_on_buffer(bh);
	if (buffer_uptodate(bh)) {
	return bh;
	}
	brelse(bh);

	return NULL;
	}

	static int qnx4_get_block( struct inode inode, sector_t iblock, struct buffer_head bh, int create )
	{
	unsigned long phys;

	QNX4DEBUG(("qnx4: qnx4_get_block inode=[%ld] iblock=[%ld]\n",inode->i_ino,iblock));

	phys = qnx4_block_map( inode, iblock );
	if ( phys ) {
	// logical block is before EOF
	map_bh(bh, inode->i_sb, phys);
	} else if ( create ) {
	// to be done.
	}
	return 0;
	}

	unsigned long qnx4_block_map( struct inode *inode, long iblock )
	{
	int ix;
	long offset, i_xblk;
	unsigned long block = 0;
	struct buffer_head *bh = NULL;
	struct qnx4_xblk *xblk = NULL;
	struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
	u16 nxtnt = le16_to_cpu(qnx4_inode->di_num_xtnts);

	if ( iblock < le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size) ) {
	// iblock is in the first extent. This is easy.
	block = le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_blk) + iblock - 1;
	} else {
	// iblock is beyond first extent. We have to follow the extent chain.
	i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
	offset = iblock - le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size);
	ix = 0;
	while ( --nxtnt > 0 ) {
	if ( ix == 0 ) {
	// read next xtnt block.
	bh = sb_bread(inode->i_sb, i_xblk - 1);
	if ( !bh ) {
	QNX4DEBUG(("qnx4: I/O error reading xtnt block [%ld])\n", i_xblk - 1));
	return -EIO;
	}
	xblk = (struct qnx4_xblk*)bh->b_data;
	if ( memcmp( xblk->xblk_signature, "IamXblk", 7 ) ) {
	QNX4DEBUG(("qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
	return -EIO;
	}
	}
	if ( offset < le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size) ) {
	// got it!
	block = le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_blk) + offset - 1;
	break;
	}
	offset -= le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size);
	if ( ++ix >= xblk->xblk_num_xtnts ) {
	i_xblk = le32_to_cpu(xblk->xblk_next_xblk);
	ix = 0;
	brelse( bh );
	bh = NULL;
	}
	}
	if ( bh )
	brelse( bh );
	}

	QNX4DEBUG(("qnx4: mapping block %ld of inode %ld = %ld\n",iblock,inode->i_ino,block));
	return block;
	}

	static int qnx4_statfs(struct dentry dentry, struct kstatfs buf)
	{
	struct super_block *sb = dentry->d_sb;

	lock_kernel();

	buf->f_type = sb->s_magic;
	buf->f_bsize = sb->s_blocksize;
	buf->f_blocks = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size) * 8;
	buf->f_bfree = qnx4_count_free_blocks(sb);
	buf->f_bavail = buf->f_bfree;
	buf->f_namelen = QNX4_NAME_MAX;

	unlock_kernel();

	return 0;
	}

	/*
	* Check the root directory of the filesystem to make sure
	* it really _is_ a qnx4 filesystem, and to check the size
	* of the directory entry.
	*/
	static const char qnx4_checkroot(struct super_block sb)
	{
	struct buffer_head *bh;
	struct qnx4_inode_entry *rootdir;
	int rd, rl;
	int i, j;
	int found = 0;

	if (*(qnx4_sb(sb)->sb->RootDir.di_fname) != '/') {
	return "no qnx4 filesystem (no root dir).";
	} else {
	QNX4DEBUG(("QNX4 filesystem found on dev %s.\n", sb->s_id));
	rd = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_blk) - 1;
	rl = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_size);
	for (j = 0; j < rl; j++) {
	bh = sb_bread(sb, rd + j); /* root dir, first block */
	if (bh == NULL) {
	return "unable to read root entry.";
	}
	for (i = 0; i < QNX4_INODES_PER_BLOCK; i++) {
	rootdir = (struct qnx4_inode_entry ) (bh->b_data + i QNX4_DIR_ENTRY_SIZE);
	if (rootdir->di_fname != NULL) {
	QNX4DEBUG(("Rootdir entry found : [%s]\n", rootdir->di_fname));
	if (!strncmp(rootdir->di_fname, QNX4_BMNAME, sizeof QNX4_BMNAME)) {
	found = 1;
	qnx4_sb(sb)->BitMap = kmalloc( sizeof( struct qnx4_inode_entry ), GFP_KERNEL );
	if (!qnx4_sb(sb)->BitMap) {
	brelse (bh);
	return "not enough memory for bitmap inode";
	}
	memcpy( qnx4_sb(sb)->BitMap, rootdir, sizeof( struct qnx4_inode_entry ) ); /* keep bitmap inode known */
	break;
	}
	}
	}
	brelse(bh);
	if (found != 0) {
	break;
	}
	}
	if (found == 0) {
	return "bitmap file not found.";
	}
	}
	return NULL;
	}

	static int qnx4_fill_super(struct super_block s, void data, int silent)
	{
	struct buffer_head *bh;
	struct inode *root;
	const char *errmsg;
	struct qnx4_sb_info *qs;
	int ret = -EINVAL;

	qs = kzalloc(sizeof(struct qnx4_sb_info), GFP_KERNEL);
	if (!qs)
	return -ENOMEM;
	s->s_fs_info = qs;

	sb_set_blocksize(s, QNX4_BLOCK_SIZE);

	/* Check the superblock signature. Since the qnx4 code is
	dangerous, we should leave as quickly as possible
	if we don't belong here... */
	bh = sb_bread(s, 1);
	if (!bh) {
	printk("qnx4: unable to read the superblock\n");
	goto outnobh;
	}
	if ( le32_to_cpup((__le32*) bh->b_data) != QNX4_SUPER_MAGIC ) {
	if (!silent)
	printk("qnx4: wrong fsid in superblock.\n");
	goto out;
	}
	s->s_op = &qnx4_sops;
	s->s_magic = QNX4_SUPER_MAGIC;
	#ifndef CONFIG_QNX4FS_RW
	s->s_flags \|= MS_RDONLY; /* Yup, read-only yet */
	#endif
	qnx4_sb(s)->sb_buf = bh;
	qnx4_sb(s)->sb = (struct qnx4_super_block *) bh->b_data;


	/* check before allocating dentries, inodes, .. */
	errmsg = qnx4_checkroot(s);
	if (errmsg != NULL) {
	if (!silent)
	printk("qnx4: %s\n", errmsg);
	goto out;
	}

	/* does root not have inode number QNX4_ROOT_INO ?? */
	root = qnx4_iget(s, QNX4_ROOT_INO * QNX4_INODES_PER_BLOCK);
	if (IS_ERR(root)) {
	printk("qnx4: get inode failed\n");
	ret = PTR_ERR(root);
	goto out;
	}

	ret = -ENOMEM;
	s->s_root = d_alloc_root(root);
	if (s->s_root == NULL)
	goto outi;

	brelse(bh);

	return 0;

	outi:
	iput(root);
	out:
	brelse(bh);
	outnobh:
	kfree(qs);
	s->s_fs_info = NULL;
	return ret;
	}

	static void qnx4_put_super(struct super_block *sb)
	{
	struct qnx4_sb_info *qs = qnx4_sb(sb);
	kfree( qs->BitMap );
	kfree( qs );
	sb->s_fs_info = NULL;
	return;
	}

	static int qnx4_writepage(struct page page, struct writeback_control wbc)
	{
	return block_write_full_page(page,qnx4_get_block, wbc);
	}

	static int qnx4_readpage(struct file file, struct page page)
	{
	return block_read_full_page(page,qnx4_get_block);
	}

	static int qnx4_write_begin(struct file file, struct address_space mapping,
	loff_t pos, unsigned len, unsigned flags,
	struct page pagep, void fsdata)
	{
	struct qnx4_inode_info *qnx4_inode = qnx4_i(mapping->host);
	*pagep = NULL;
	return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
	qnx4_get_block,
	&qnx4_inode->mmu_private);
	}
	static sector_t qnx4_bmap(struct address_space *mapping, sector_t block)
	{
	return generic_block_bmap(mapping,block,qnx4_get_block);
	}
	static const struct address_space_operations qnx4_aops = {
	.readpage = qnx4_readpage,
	.writepage = qnx4_writepage,
	.sync_page = block_sync_page,
	.write_begin = qnx4_write_begin,
	.write_end = generic_write_end,
	.bmap = qnx4_bmap
	};

	struct inode qnx4_iget(struct super_block sb, unsigned long ino)
	{
	struct buffer_head *bh;
	struct qnx4_inode_entry *raw_inode;
	int block;
	struct qnx4_inode_entry *qnx4_inode;
	struct inode *inode;

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

	qnx4_inode = qnx4_raw_inode(inode);
	inode->i_mode = 0;

	QNX4DEBUG(("Reading inode : [%d]\n", ino));
	if (!ino) {
	printk(KERN_ERR "qnx4: bad inode number on dev %s: %lu is "
	"out of range\n",
	sb->s_id, ino);
	iget_failed(inode);
	return ERR_PTR(-EIO);
	}
	block = ino / QNX4_INODES_PER_BLOCK;

	if (!(bh = sb_bread(sb, block))) {
	printk("qnx4: major problem: unable to read inode from dev "
	"%s\n", sb->s_id);
	iget_failed(inode);
	return ERR_PTR(-EIO);
	}
	raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
	(ino % QNX4_INODES_PER_BLOCK);

	inode->i_mode = le16_to_cpu(raw_inode->di_mode);
	inode->i_uid = (uid_t)le16_to_cpu(raw_inode->di_uid);
	inode->i_gid = (gid_t)le16_to_cpu(raw_inode->di_gid);
	inode->i_nlink = le16_to_cpu(raw_inode->di_nlink);
	inode->i_size = le32_to_cpu(raw_inode->di_size);
	inode->i_mtime.tv_sec = le32_to_cpu(raw_inode->di_mtime);
	inode->i_mtime.tv_nsec = 0;
	inode->i_atime.tv_sec = le32_to_cpu(raw_inode->di_atime);
	inode->i_atime.tv_nsec = 0;
	inode->i_ctime.tv_sec = le32_to_cpu(raw_inode->di_ctime);
	inode->i_ctime.tv_nsec = 0;
	inode->i_blocks = le32_to_cpu(raw_inode->di_first_xtnt.xtnt_size);

	memcpy(qnx4_inode, raw_inode, QNX4_DIR_ENTRY_SIZE);
	if (S_ISREG(inode->i_mode)) {
	inode->i_op = &qnx4_file_inode_operations;
	inode->i_fop = &qnx4_file_operations;
	inode->i_mapping->a_ops = &qnx4_aops;
	qnx4_i(inode)->mmu_private = inode->i_size;
	} else if (S_ISDIR(inode->i_mode)) {
	inode->i_op = &qnx4_dir_inode_operations;
	inode->i_fop = &qnx4_dir_operations;
	} else if (S_ISLNK(inode->i_mode)) {
	inode->i_op = &page_symlink_inode_operations;
	inode->i_mapping->a_ops = &qnx4_aops;
	qnx4_i(inode)->mmu_private = inode->i_size;
	} else {
	printk(KERN_ERR "qnx4: bad inode %lu on dev %s\n",
	ino, sb->s_id);
	iget_failed(inode);
	brelse(bh);
	return ERR_PTR(-EIO);
	}
	brelse(bh);
	unlock_new_inode(inode);
	return inode;
	}

	static struct kmem_cache *qnx4_inode_cachep;

	static struct inode qnx4_alloc_inode(struct super_block sb)
	{
	struct qnx4_inode_info *ei;
	ei = kmem_cache_alloc(qnx4_inode_cachep, GFP_KERNEL);
	if (!ei)
	return NULL;
	return &ei->vfs_inode;
	}

	static void qnx4_destroy_inode(struct inode *inode)
	{
	kmem_cache_free(qnx4_inode_cachep, qnx4_i(inode));
	}

	static void init_once(void *foo)
	{
	struct qnx4_inode_info ei = (struct qnx4_inode_info ) foo;

	inode_init_once(&ei->vfs_inode);
	}

	static int init_inodecache(void)
	{
	qnx4_inode_cachep = kmem_cache_create("qnx4_inode_cache",
	sizeof(struct qnx4_inode_info),
	0, (SLAB_RECLAIM_ACCOUNT\|
	SLAB_MEM_SPREAD),
	init_once);
	if (qnx4_inode_cachep == NULL)
	return -ENOMEM;
	return 0;
	}

	static void destroy_inodecache(void)
	{
	kmem_cache_destroy(qnx4_inode_cachep);
	}

	static int qnx4_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, qnx4_fill_super,
	mnt);
	}

	static struct file_system_type qnx4_fs_type = {
	.owner = THIS_MODULE,
	.name = "qnx4",
	.get_sb = qnx4_get_sb,
	.kill_sb = kill_block_super,
	.fs_flags = FS_REQUIRES_DEV,
	};

	static int __init init_qnx4_fs(void)
	{
	int err;

	err = init_inodecache();
	if (err)
	return err;

	err = register_filesystem(&qnx4_fs_type);
	if (err) {
	destroy_inodecache();
	return err;
	}

	printk("QNX4 filesystem 0.2.3 registered.\n");
	return 0;
	}

	static void __exit exit_qnx4_fs(void)
	{
	unregister_filesystem(&qnx4_fs_type);
	destroy_inodecache();
	}

	module_init(init_qnx4_fs)
	module_exit(exit_qnx4_fs)
	MODULE_LICENSE("GPL");