/*
   * 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_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,

  	.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 |= MS_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]
  ",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])
  ", 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
  ", 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
  ",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.val[0] = (u32)id;
  	buf->f_fsid.val[1] = (u32)(id >> 32);

  	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.
  ", 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]
  ", 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 |= MS_RDONLY;	/* Yup, read-only yet */

  	/* 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
  ");

  		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
  ", 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
  ");

  		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_readpage(struct file *file, struct page *page)
  {
  	return block_read_full_page(page,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 = {

  	.readpage	= qnx4_readpage,

  	.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]
  ", ino));

  	if (!ino) {

  		printk(KERN_ERR "qnx4: bad inode number on dev %s: %lu is "
  				"out of range
  ",

  		       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
  ", 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->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_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
  ",
  			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_i_callback(struct rcu_head *head)

  {

  	struct inode *inode = container_of(head, struct inode, i_rcu);

  	kmem_cache_free(qnx4_inode_cachep, qnx4_i(inode));
  }

  static void qnx4_destroy_inode(struct inode *inode)
  {
  	call_rcu(&inode->i_rcu, qnx4_i_callback);
  }

  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.
  ");

  	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");