/*
   *	fs/bfs/inode.c
   *	BFS superblock and inode operations.

   *	Copyright (C) 1999-2006 Tigran Aivazian <tigran@aivazian.fsnet.co.uk>

   *	From fs/minix, Copyright (C) 1991, 1992 Linus Torvalds.

   *
   *      Made endianness-clean by Andrew Stribblehill <ads@wompom.org>, 2005.

   */
  
  #include <linux/module.h>
  #include <linux/mm.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <linux/fs.h>

  #include <linux/buffer_head.h>
  #include <linux/vfs.h>

  #include <linux/writeback.h>

  #include <linux/uio.h>

  #include <asm/uaccess.h>
  #include "bfs.h"

  MODULE_AUTHOR("Tigran Aivazian <tigran@aivazian.fsnet.co.uk>");

  MODULE_DESCRIPTION("SCO UnixWare BFS filesystem for Linux");
  MODULE_LICENSE("GPL");
  
  #undef DEBUG
  
  #ifdef DEBUG
  #define dprintf(x...)	printf(x)
  #else
  #define dprintf(x...)
  #endif

  struct inode *bfs_iget(struct super_block *sb, unsigned long ino)

  {

  	struct bfs_inode *di;

  	struct inode *inode;

  	struct buffer_head *bh;

  	int block, off;

  	inode = iget_locked(sb, ino);

  	if (!inode)

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

  	if ((ino < BFS_ROOT_INO) || (ino > BFS_SB(inode->i_sb)->si_lasti)) {

  		printf("Bad inode number %s:%08lx
  ", inode->i_sb->s_id, ino);

  		goto error;

  	}

  	block = (ino - BFS_ROOT_INO) / BFS_INODES_PER_BLOCK + 1;

  	bh = sb_bread(inode->i_sb, block);
  	if (!bh) {

  		printf("Unable to read inode %s:%08lx
  ", inode->i_sb->s_id,
  									ino);

  		goto error;

  	}
  
  	off = (ino - BFS_ROOT_INO) % BFS_INODES_PER_BLOCK;
  	di = (struct bfs_inode *)bh->b_data + off;

  	inode->i_mode = 0x0000FFFF & le32_to_cpu(di->i_mode);

  	if (le32_to_cpu(di->i_vtype) == BFS_VDIR) {

  		inode->i_mode |= S_IFDIR;
  		inode->i_op = &bfs_dir_inops;
  		inode->i_fop = &bfs_dir_operations;

  	} else if (le32_to_cpu(di->i_vtype) == BFS_VREG) {

  		inode->i_mode |= S_IFREG;
  		inode->i_op = &bfs_file_inops;
  		inode->i_fop = &bfs_file_operations;
  		inode->i_mapping->a_ops = &bfs_aops;
  	}

  	BFS_I(inode)->i_sblock =  le32_to_cpu(di->i_sblock);
  	BFS_I(inode)->i_eblock =  le32_to_cpu(di->i_eblock);

  	BFS_I(inode)->i_dsk_ino = le16_to_cpu(di->i_ino);

  	i_uid_write(inode, le32_to_cpu(di->i_uid));
  	i_gid_write(inode,  le32_to_cpu(di->i_gid));

  	set_nlink(inode, le32_to_cpu(di->i_nlink));

  	inode->i_size = BFS_FILESIZE(di);
  	inode->i_blocks = BFS_FILEBLOCKS(di);

  	inode->i_atime.tv_sec =  le32_to_cpu(di->i_atime);
  	inode->i_mtime.tv_sec =  le32_to_cpu(di->i_mtime);
  	inode->i_ctime.tv_sec =  le32_to_cpu(di->i_ctime);

  	inode->i_atime.tv_nsec = 0;
  	inode->i_mtime.tv_nsec = 0;
  	inode->i_ctime.tv_nsec = 0;

  
  	brelse(bh);

  	unlock_new_inode(inode);
  	return inode;
  
  error:
  	iget_failed(inode);
  	return ERR_PTR(-EIO);

  }

  static struct bfs_inode *find_inode(struct super_block *sb, u16 ino, struct buffer_head **p)
  {
  	if ((ino < BFS_ROOT_INO) || (ino > BFS_SB(sb)->si_lasti)) {
  		printf("Bad inode number %s:%08x
  ", sb->s_id, ino);
  		return ERR_PTR(-EIO);
  	}
  
  	ino -= BFS_ROOT_INO;
  
  	*p = sb_bread(sb, 1 + ino / BFS_INODES_PER_BLOCK);
  	if (!*p) {
  		printf("Unable to read inode %s:%08x
  ", sb->s_id, ino);
  		return ERR_PTR(-EIO);
  	}
  
  	return (struct bfs_inode *)(*p)->b_data +  ino % BFS_INODES_PER_BLOCK;
  }

  static int bfs_write_inode(struct inode *inode, struct writeback_control *wbc)

  {

  	struct bfs_sb_info *info = BFS_SB(inode->i_sb);

  	unsigned int ino = (u16)inode->i_ino;
          unsigned long i_sblock;

  	struct bfs_inode *di;
  	struct buffer_head *bh;

  	int err = 0;

          dprintf("ino=%08x
  ", ino);

  	di = find_inode(inode->i_sb, ino, &bh);
  	if (IS_ERR(di))
  		return PTR_ERR(di);

  	mutex_lock(&info->bfs_lock);

  	if (ino == BFS_ROOT_INO)
  		di->i_vtype = cpu_to_le32(BFS_VDIR);

  	else

  		di->i_vtype = cpu_to_le32(BFS_VREG);
  
  	di->i_ino = cpu_to_le16(ino);
  	di->i_mode = cpu_to_le32(inode->i_mode);

  	di->i_uid = cpu_to_le32(i_uid_read(inode));
  	di->i_gid = cpu_to_le32(i_gid_read(inode));

  	di->i_nlink = cpu_to_le32(inode->i_nlink);
  	di->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
  	di->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
  	di->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
          i_sblock = BFS_I(inode)->i_sblock;
  	di->i_sblock = cpu_to_le32(i_sblock);
  	di->i_eblock = cpu_to_le32(BFS_I(inode)->i_eblock);
  	di->i_eoffset = cpu_to_le32(i_sblock * BFS_BSIZE + inode->i_size - 1);

  
  	mark_buffer_dirty(bh);

  	if (wbc->sync_mode == WB_SYNC_ALL) {

  		sync_dirty_buffer(bh);
  		if (buffer_req(bh) && !buffer_uptodate(bh))
  			err = -EIO;
  	}

  	brelse(bh);

  	mutex_unlock(&info->bfs_lock);

  	return err;

  }

  static void bfs_evict_inode(struct inode *inode)

  {
  	unsigned long ino = inode->i_ino;

  	struct bfs_inode *di;
  	struct buffer_head *bh;

  	struct super_block *s = inode->i_sb;
  	struct bfs_sb_info *info = BFS_SB(s);
  	struct bfs_inode_info *bi = BFS_I(inode);

  	dprintf("ino=%08lx
  ", ino);

  	truncate_inode_pages_final(&inode->i_data);

  	invalidate_inode_buffers(inode);

  	clear_inode(inode);

  	if (inode->i_nlink)

  		return;

  	di = find_inode(s, inode->i_ino, &bh);
  	if (IS_ERR(di))

  		return;

  
  	mutex_lock(&info->bfs_lock);
  	/* clear on-disk inode */
  	memset(di, 0, sizeof(struct bfs_inode));

  	mark_buffer_dirty(bh);
  	brelse(bh);

          if (bi->i_dsk_ino) {

  		if (bi->i_sblock)
  			info->si_freeb += bi->i_eblock + 1 - bi->i_sblock;

  		info->si_freei++;

  		clear_bit(ino, info->si_imap);

  		bfs_dump_imap("delete_inode", s);

          }

  	/*
  	 * If this was the last file, make the previous block
  	 * "last block of the last file" even if there is no
  	 * real file there, saves us 1 gap.
  	 */

  	if (info->si_lf_eblk == bi->i_eblock)

  		info->si_lf_eblk = bi->i_sblock - 1;

  	mutex_unlock(&info->bfs_lock);

  }
  
  static void bfs_put_super(struct super_block *s)
  {
  	struct bfs_sb_info *info = BFS_SB(s);

  	if (!info)
  		return;

  	mutex_destroy(&info->bfs_lock);

  	kfree(info->si_imap);
  	kfree(info);
  	s->s_fs_info = NULL;
  }

  static int bfs_statfs(struct dentry *dentry, struct kstatfs *buf)

  {

  	struct super_block *s = dentry->d_sb;

  	struct bfs_sb_info *info = BFS_SB(s);
  	u64 id = huge_encode_dev(s->s_bdev->bd_dev);
  	buf->f_type = BFS_MAGIC;
  	buf->f_bsize = s->s_blocksize;
  	buf->f_blocks = info->si_blocks;
  	buf->f_bfree = buf->f_bavail = info->si_freeb;
  	buf->f_files = info->si_lasti + 1 - BFS_ROOT_INO;
  	buf->f_ffree = info->si_freei;
  	buf->f_fsid.val[0] = (u32)id;
  	buf->f_fsid.val[1] = (u32)(id >> 32);
  	buf->f_namelen = BFS_NAMELEN;
  	return 0;
  }

  static struct kmem_cache *bfs_inode_cachep;

  
  static struct inode *bfs_alloc_inode(struct super_block *sb)
  {
  	struct bfs_inode_info *bi;

  	bi = kmem_cache_alloc(bfs_inode_cachep, GFP_KERNEL);

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

  static void bfs_i_callback(struct rcu_head *head)

  {

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

  	kmem_cache_free(bfs_inode_cachep, BFS_I(inode));
  }

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

  static void init_once(void *foo)

  {
  	struct bfs_inode_info *bi = foo;

  	inode_init_once(&bi->vfs_inode);

  }

  static int __init init_inodecache(void)

  {
  	bfs_inode_cachep = kmem_cache_create("bfs_inode_cache",
  					     sizeof(struct bfs_inode_info),

  					     0, (SLAB_RECLAIM_ACCOUNT|

  						SLAB_MEM_SPREAD|SLAB_ACCOUNT),

  					     init_once);

  	if (bfs_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(bfs_inode_cachep);

  }

  static const struct super_operations bfs_sops = {

  	.alloc_inode	= bfs_alloc_inode,
  	.destroy_inode	= bfs_destroy_inode,

  	.write_inode	= bfs_write_inode,

  	.evict_inode	= bfs_evict_inode,

  	.put_super	= bfs_put_super,

  	.statfs		= bfs_statfs,
  };

  void bfs_dump_imap(const char *prefix, struct super_block *s)

  {

  #ifdef DEBUG

  	int i;
  	char *tmpbuf = (char *)get_zeroed_page(GFP_KERNEL);
  
  	if (!tmpbuf)
  		return;

  	for (i = BFS_SB(s)->si_lasti; i >= 0; i--) {
  		if (i > PAGE_SIZE - 100) break;

  		if (test_bit(i, BFS_SB(s)->si_imap))
  			strcat(tmpbuf, "1");
  		else
  			strcat(tmpbuf, "0");
  	}

  	printf("BFS-fs: %s: lasti=%08lx <%s>
  ",
  				prefix, BFS_SB(s)->si_lasti, tmpbuf);

  	free_page((unsigned long)tmpbuf);
  #endif
  }
  
  static int bfs_fill_super(struct super_block *s, void *data, int silent)
  {

  	struct buffer_head *bh, *sbh;

  	struct bfs_super_block *bfs_sb;
  	struct inode *inode;

  	unsigned i, imap_len;

  	struct bfs_sb_info *info;

  	int ret = -EINVAL;

  	unsigned long i_sblock, i_eblock, i_eoff, s_size;

  	info = kzalloc(sizeof(*info), GFP_KERNEL);

  	if (!info)

  		return -ENOMEM;

  	mutex_init(&info->bfs_lock);

  	s->s_fs_info = info;

  
  	sb_set_blocksize(s, BFS_BSIZE);

  	sbh = sb_bread(s, 0);
  	if (!sbh)

  		goto out;

  	bfs_sb = (struct bfs_super_block *)sbh->b_data;

  	if (le32_to_cpu(bfs_sb->s_magic) != BFS_MAGIC) {

  		if (!silent)
  			printf("No BFS filesystem on %s (magic=%08x)
  ", 

  				s->s_id,  le32_to_cpu(bfs_sb->s_magic));

  		goto out1;

  	}
  	if (BFS_UNCLEAN(bfs_sb, s) && !silent)
  		printf("%s is unclean, continuing
  ", s->s_id);
  
  	s->s_magic = BFS_MAGIC;

  
  	if (le32_to_cpu(bfs_sb->s_start) > le32_to_cpu(bfs_sb->s_end)) {
  		printf("Superblock is corrupted
  ");

  		goto out1;

  	}

  	info->si_lasti = (le32_to_cpu(bfs_sb->s_start) - BFS_BSIZE) /
  					sizeof(struct bfs_inode)
  					+ BFS_ROOT_INO - 1;
  	imap_len = (info->si_lasti / 8) + 1;

  	info->si_imap = kzalloc(imap_len, GFP_KERNEL);

  	if (!info->si_imap)

  		goto out1;

  	for (i = 0; i < BFS_ROOT_INO; i++)

  		set_bit(i, info->si_imap);
  
  	s->s_op = &bfs_sops;

  	inode = bfs_iget(s, BFS_ROOT_INO);
  	if (IS_ERR(inode)) {
  		ret = PTR_ERR(inode);

  		goto out2;

  	}

  	s->s_root = d_make_root(inode);

  	if (!s->s_root) {

  		ret = -ENOMEM;

  		goto out2;

  	}

  	info->si_blocks = (le32_to_cpu(bfs_sb->s_end) + 1) >> BFS_BSIZE_BITS;
  	info->si_freeb = (le32_to_cpu(bfs_sb->s_end) + 1
  			- le32_to_cpu(bfs_sb->s_start)) >> BFS_BSIZE_BITS;

  	info->si_freei = 0;
  	info->si_lf_eblk = 0;

  
  	/* can we read the last block? */
  	bh = sb_bread(s, info->si_blocks - 1);
  	if (!bh) {
  		printf("Last block not available: %lu
  ", info->si_blocks - 1);

  		ret = -EIO;

  		goto out3;

  	}
  	brelse(bh);

  	bh = NULL;

  	for (i = BFS_ROOT_INO; i <= info->si_lasti; i++) {

  		struct bfs_inode *di;

  		int block = (i - BFS_ROOT_INO) / BFS_INODES_PER_BLOCK + 1;

  		int off = (i - BFS_ROOT_INO) % BFS_INODES_PER_BLOCK;

  		unsigned long eblock;

  
  		if (!off) {
  			brelse(bh);
  			bh = sb_bread(s, block);
  		}
  
  		if (!bh)
  			continue;
  
  		di = (struct bfs_inode *)bh->b_data + off;

  		/* test if filesystem is not corrupted */
  
  		i_eoff = le32_to_cpu(di->i_eoffset);
  		i_sblock = le32_to_cpu(di->i_sblock);
  		i_eblock = le32_to_cpu(di->i_eblock);
  		s_size = le32_to_cpu(bfs_sb->s_end);
  
  		if (i_sblock > info->si_blocks ||
  			i_eblock > info->si_blocks ||
  			i_sblock > i_eblock ||
  			i_eoff > s_size ||
  			i_sblock * BFS_BSIZE > i_eoff) {
  
  			printf("Inode 0x%08x corrupted
  ", i);
  
  			brelse(bh);

  			ret = -EIO;
  			goto out3;

  		}

  		if (!di->i_ino) {

  			info->si_freei++;

  			continue;
  		}
  		set_bit(i, info->si_imap);
  		info->si_freeb -= BFS_FILEBLOCKS(di);

  		eblock =  le32_to_cpu(di->i_eblock);

  		if (eblock > info->si_lf_eblk)

  			info->si_lf_eblk = eblock;

  	}

  	brelse(bh);

  	brelse(sbh);

  	bfs_dump_imap("read_super", s);

  	return 0;

  out3:
  	dput(s->s_root);
  	s->s_root = NULL;
  out2:
  	kfree(info->si_imap);
  out1:

  	brelse(sbh);

  out:

  	mutex_destroy(&info->bfs_lock);

  	kfree(info);
  	s->s_fs_info = NULL;

  	return ret;

  }

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

  {

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

  }
  
  static struct file_system_type bfs_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "bfs",

  	.mount		= bfs_mount,

  	.kill_sb	= kill_block_super,
  	.fs_flags	= FS_REQUIRES_DEV,
  };

  MODULE_ALIAS_FS("bfs");

  
  static int __init init_bfs_fs(void)
  {
  	int err = init_inodecache();
  	if (err)
  		goto out1;
          err = register_filesystem(&bfs_fs_type);
  	if (err)
  		goto out;
  	return 0;
  out:
  	destroy_inodecache();
  out1:
  	return err;
  }
  
  static void __exit exit_bfs_fs(void)
  {
  	unregister_filesystem(&bfs_fs_type);
  	destroy_inodecache();
  }
  
  module_init(init_bfs_fs)
  module_exit(exit_bfs_fs)