fs/qnx4/inode.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * 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/init.h>
 #include <linux/slab.h>
 #include <linux/highuid.h>
 #include <linux/pagemap.h>
 #include <linux/buffer_head.h>
 #include <linux/writeback.h>
 #include <linux/statfs.h>
 #include "qnx4.h"

 #define QNX4_VERSION  4
 #define QNX4_BMNAME   ".bitmap"

 static const struct super_operations qnx4_sops;

 static struct inode *qnx4_alloc_inode(struct super_block *sb);
 static void qnx4_free_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,
 	.free_inode	= qnx4_free_inode,
 	.statfs		= qnx4_statfs,
 	.remount_fs	= qnx4_remount,
 };

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

 	sync_filesystem(sb);
 	qs = qnx4_sb(sb);
 	qs->Version = QNX4_VERSION;
 	*flags |= SB_RDONLY;
 	return 0;
 }

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

 	QNX4DEBUG((KERN_INFO "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);
 	}
 	return 0;
 }

 static inline u32 try_extent(qnx4_xtnt_t *extent, u32 *offset)
 {
 	u32 size = le32_to_cpu(extent->xtnt_size);
 	if (*offset < size)
 		return le32_to_cpu(extent->xtnt_blk) + *offset - 1;
 	*offset -= size;
 	return 0;
 }

 unsigned long qnx4_block_map( struct inode *inode, long iblock )
 {
 	int ix;
 	long i_xblk;
 	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);
 	u32 offset = iblock;
 	u32 block = try_extent(&qnx4_inode->di_first_xtnt, &offset);

 	if (block) {
 		// iblock is in the first extent. This is easy.
 	} else {
 		// iblock is beyond first extent. We have to follow the extent chain.
 		i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
 		ix = 0;
 		while ( --nxtnt > 0 ) {
 			if ( ix == 0 ) {
 				// read next xtnt block.
 				bh = sb_bread(inode->i_sb, i_xblk - 1);
 				if ( !bh ) {
 					QNX4DEBUG((KERN_ERR "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((KERN_ERR "qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
 					return -EIO;
 				}
 			}
 			block = try_extent(&xblk->xblk_xtnts[ix], &offset);
 			if (block) {
 				// got it!
 				break;
 			}
 			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((KERN_INFO "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;
 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

 	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;
 	buf->f_fsid    = u64_to_fsid(id);

 	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 qnx4_super_block *s)
 {
 	struct buffer_head *bh;
 	struct qnx4_inode_entry *rootdir;
 	int rd, rl;
 	int i, j;

 	if (s->RootDir.di_fname[0] != '/' || s->RootDir.di_fname[1] != '\0')
 		return "no qnx4 filesystem (no root dir).";
 	QNX4DEBUG((KERN_NOTICE "QNX4 filesystem found on dev %s.\n", sb->s_id));
 	rd = le32_to_cpu(s->RootDir.di_first_xtnt.xtnt_blk) - 1;
 	rl = le32_to_cpu(s->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.";
 		rootdir = (struct qnx4_inode_entry *) bh->b_data;
 		for (i = 0; i < QNX4_INODES_PER_BLOCK; i++, rootdir++) {
 			QNX4DEBUG((KERN_INFO "rootdir entry found : [%s]\n", rootdir->di_fname));
 			if (strcmp(rootdir->di_fname, QNX4_BMNAME) != 0)
 				continue;
 			qnx4_sb(sb)->BitMap = kmemdup(rootdir,
 						      sizeof(struct qnx4_inode_entry),
 						      GFP_KERNEL);
 			brelse(bh);
 			if (!qnx4_sb(sb)->BitMap)
 				return "not enough memory for bitmap inode";
 			/* keep bitmap inode known */
 			return NULL;
 		}
 		brelse(bh);
 	}
 	return "bitmap file not found.";
 }

 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;

 	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);

 	s->s_op = &qnx4_sops;
 	s->s_magic = QNX4_SUPER_MAGIC;
 	s->s_flags |= SB_RDONLY;	/* Yup, read-only yet */
 	s->s_time_min = 0;
 	s->s_time_max = U32_MAX;

 	/* 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(KERN_ERR "qnx4: unable to read the superblock\n");
 		return -EINVAL;
 	}

  	/* check before allocating dentries, inodes, .. */
 	errmsg = qnx4_checkroot(s, (struct qnx4_super_block *) bh->b_data);
 	brelse(bh);
 	if (errmsg != NULL) {
  		if (!silent)
 			printk(KERN_ERR "qnx4: %s\n", errmsg);
 		return -EINVAL;
 	}

  	/* 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(KERN_ERR "qnx4: get inode failed\n");
 		return PTR_ERR(root);
  	}

  	s->s_root = d_make_root(root);
  	if (s->s_root == NULL)
  		return -ENOMEM;

 	return 0;
 }

 static void qnx4_kill_sb(struct super_block *sb)
 {
 	struct qnx4_sb_info *qs = qnx4_sb(sb);
 	kill_block_super(sb);
 	if (qs) {
 		kfree(qs->BitMap);
 		kfree(qs);
 	}
 }

 static int qnx4_read_folio(struct file *file, struct folio *folio)
 {
 	return block_read_full_folio(folio, qnx4_get_block);
 }

 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 = {
 	.read_folio	= qnx4_read_folio,
 	.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((KERN_INFO "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(KERN_ERR "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);
 	i_uid_write(inode, (uid_t)le16_to_cpu(raw_inode->di_uid));
 	i_gid_write(inode, (gid_t)le16_to_cpu(raw_inode->di_gid));
 	set_nlink(inode, le16_to_cpu(raw_inode->di_nlink));
 	inode->i_size    = le32_to_cpu(raw_inode->di_size);
 	inode_set_mtime(inode, le32_to_cpu(raw_inode->di_mtime), 0);
 	inode_set_atime(inode, le32_to_cpu(raw_inode->di_atime), 0);
 	inode_set_ctime(inode, le32_to_cpu(raw_inode->di_ctime), 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_fop = &generic_ro_fops;
 		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_nohighmem(inode);
 		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 = alloc_inode_sb(sb, qnx4_inode_cachep, GFP_KERNEL);
 	if (!ei)
 		return NULL;
 	return &ei->vfs_inode;
 }

 static void qnx4_free_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|SLAB_ACCOUNT),
 					     init_once);
 	if (qnx4_inode_cachep == NULL)
 		return -ENOMEM;
 	return 0;
 }

 static void destroy_inodecache(void)
 {
 	/*
 	 * Make sure all delayed rcu free inodes are flushed before we
 	 * destroy cache.
 	 */
 	rcu_barrier();
 	kmem_cache_destroy(qnx4_inode_cachep);
 }

 static struct dentry *qnx4_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
 	return mount_bdev(fs_type, flags, dev_name, data, qnx4_fill_super);
 }

 static struct file_system_type qnx4_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "qnx4",
 	.mount		= qnx4_mount,
 	.kill_sb	= qnx4_kill_sb,
 	.fs_flags	= FS_REQUIRES_DEV,
 };
 MODULE_ALIAS_FS("qnx4");

 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(KERN_INFO "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");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* 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/init.h>
	#include <linux/slab.h>
	#include <linux/highuid.h>
	#include <linux/pagemap.h>
	#include <linux/buffer_head.h>
	#include <linux/writeback.h>
	#include <linux/statfs.h>
	#include "qnx4.h"

	#define QNX4_VERSION 4
	#define QNX4_BMNAME ".bitmap"

	static const struct super_operations qnx4_sops;

	static struct inode qnx4_alloc_inode(struct super_block sb);
	static void qnx4_free_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,
	.free_inode = qnx4_free_inode,
	.statfs = qnx4_statfs,
	.remount_fs = qnx4_remount,
	};

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

	sync_filesystem(sb);
	qs = qnx4_sb(sb);
	qs->Version = QNX4_VERSION;
	*flags \|= SB_RDONLY;
	return 0;
	}

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

	QNX4DEBUG((KERN_INFO "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);
	}
	return 0;
	}

	static inline u32 try_extent(qnx4_xtnt_t extent, u32 offset)
	{
	u32 size = le32_to_cpu(extent->xtnt_size);
	if (*offset < size)
	return le32_to_cpu(extent->xtnt_blk) + *offset - 1;
	*offset -= size;
	return 0;
	}

	unsigned long qnx4_block_map( struct inode *inode, long iblock )
	{
	int ix;
	long i_xblk;
	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);
	u32 offset = iblock;
	u32 block = try_extent(&qnx4_inode->di_first_xtnt, &offset);

	if (block) {
	// iblock is in the first extent. This is easy.
	} else {
	// iblock is beyond first extent. We have to follow the extent chain.
	i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
	ix = 0;
	while ( --nxtnt > 0 ) {
	if ( ix == 0 ) {
	// read next xtnt block.
	bh = sb_bread(inode->i_sb, i_xblk - 1);
	if ( !bh ) {
	QNX4DEBUG((KERN_ERR "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((KERN_ERR "qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
	return -EIO;
	}
	}
	block = try_extent(&xblk->xblk_xtnts[ix], &offset);
	if (block) {
	// got it!
	break;
	}
	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((KERN_INFO "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;
	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

	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;
	buf->f_fsid = u64_to_fsid(id);

	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 qnx4_super_block *s)
	{
	struct buffer_head *bh;
	struct qnx4_inode_entry *rootdir;
	int rd, rl;
	int i, j;

	if (s->RootDir.di_fname[0] != '/' \|\| s->RootDir.di_fname[1] != '\0')
	return "no qnx4 filesystem (no root dir).";
	QNX4DEBUG((KERN_NOTICE "QNX4 filesystem found on dev %s.\n", sb->s_id));
	rd = le32_to_cpu(s->RootDir.di_first_xtnt.xtnt_blk) - 1;
	rl = le32_to_cpu(s->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.";
	rootdir = (struct qnx4_inode_entry *) bh->b_data;
	for (i = 0; i < QNX4_INODES_PER_BLOCK; i++, rootdir++) {
	QNX4DEBUG((KERN_INFO "rootdir entry found : [%s]\n", rootdir->di_fname));
	if (strcmp(rootdir->di_fname, QNX4_BMNAME) != 0)
	continue;
	qnx4_sb(sb)->BitMap = kmemdup(rootdir,
	sizeof(struct qnx4_inode_entry),
	GFP_KERNEL);
	brelse(bh);
	if (!qnx4_sb(sb)->BitMap)
	return "not enough memory for bitmap inode";
	/* keep bitmap inode known */
	return NULL;
	}
	brelse(bh);
	}
	return "bitmap file not found.";
	}

	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;

	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);

	s->s_op = &qnx4_sops;
	s->s_magic = QNX4_SUPER_MAGIC;
	s->s_flags \|= SB_RDONLY; /* Yup, read-only yet */
	s->s_time_min = 0;
	s->s_time_max = U32_MAX;

	/* 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(KERN_ERR "qnx4: unable to read the superblock\n");
	return -EINVAL;
	}

	/* check before allocating dentries, inodes, .. */
	errmsg = qnx4_checkroot(s, (struct qnx4_super_block *) bh->b_data);
	brelse(bh);
	if (errmsg != NULL) {
	if (!silent)
	printk(KERN_ERR "qnx4: %s\n", errmsg);
	return -EINVAL;
	}

	/* 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(KERN_ERR "qnx4: get inode failed\n");
	return PTR_ERR(root);
	}

	s->s_root = d_make_root(root);
	if (s->s_root == NULL)
	return -ENOMEM;

	return 0;
	}

	static void qnx4_kill_sb(struct super_block *sb)
	{
	struct qnx4_sb_info *qs = qnx4_sb(sb);
	kill_block_super(sb);
	if (qs) {
	kfree(qs->BitMap);
	kfree(qs);
	}
	}

	static int qnx4_read_folio(struct file file, struct folio folio)
	{
	return block_read_full_folio(folio, qnx4_get_block);
	}

	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 = {
	.read_folio = qnx4_read_folio,
	.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((KERN_INFO "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(KERN_ERR "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);
	i_uid_write(inode, (uid_t)le16_to_cpu(raw_inode->di_uid));
	i_gid_write(inode, (gid_t)le16_to_cpu(raw_inode->di_gid));
	set_nlink(inode, le16_to_cpu(raw_inode->di_nlink));
	inode->i_size = le32_to_cpu(raw_inode->di_size);
	inode_set_mtime(inode, le32_to_cpu(raw_inode->di_mtime), 0);
	inode_set_atime(inode, le32_to_cpu(raw_inode->di_atime), 0);
	inode_set_ctime(inode, le32_to_cpu(raw_inode->di_ctime), 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_fop = &generic_ro_fops;
	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_nohighmem(inode);
	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 = alloc_inode_sb(sb, qnx4_inode_cachep, GFP_KERNEL);
	if (!ei)
	return NULL;
	return &ei->vfs_inode;
	}

	static void qnx4_free_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\|SLAB_ACCOUNT),
	init_once);
	if (qnx4_inode_cachep == NULL)
	return -ENOMEM;
	return 0;
	}

	static void destroy_inodecache(void)
	{
	/*
	* Make sure all delayed rcu free inodes are flushed before we
	* destroy cache.
	*/
	rcu_barrier();
	kmem_cache_destroy(qnx4_inode_cachep);
	}

	static struct dentry qnx4_mount(struct file_system_type fs_type,
	int flags, const char dev_name, void data)
	{
	return mount_bdev(fs_type, flags, dev_name, data, qnx4_fill_super);
	}

	static struct file_system_type qnx4_fs_type = {
	.owner = THIS_MODULE,
	.name = "qnx4",
	.mount = qnx4_mount,
	.kill_sb = qnx4_kill_sb,
	.fs_flags = FS_REQUIRES_DEV,
	};
	MODULE_ALIAS_FS("qnx4");

	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(KERN_INFO "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");