/*
   *  linux/fs/sysv/inode.c
   *
   *  minix/inode.c
   *  Copyright (C) 1991, 1992  Linus Torvalds
   *
   *  xenix/inode.c
   *  Copyright (C) 1992  Doug Evans
   *
   *  coh/inode.c
   *  Copyright (C) 1993  Pascal Haible, Bruno Haible
   *
   *  sysv/inode.c
   *  Copyright (C) 1993  Paul B. Monday
   *
   *  sysv/inode.c
   *  Copyright (C) 1993  Bruno Haible
   *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
   *
   *  This file contains code for allocating/freeing inodes and for read/writing
   *  the superblock.
   */

  #include <linux/highuid.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <linux/buffer_head.h>
  #include <linux/vfs.h>

  #include <linux/writeback.h>

  #include <linux/namei.h>

  #include <asm/byteorder.h>
  #include "sysv.h"

  static int sysv_sync_fs(struct super_block *sb, int wait)

  {
  	struct sysv_sb_info *sbi = SYSV_SB(sb);
  	unsigned long time = get_seconds(), old_time;

  	lock_super(sb);

  
  	/*
  	 * If we are going to write out the super block,
  	 * then attach current time stamp.
  	 * But if the filesystem was marked clean, keep it clean.
  	 */

  	sb->s_dirt = 0;

  	old_time = fs32_to_cpu(sbi, *sbi->s_sb_time);
  	if (sbi->s_type == FSTYPE_SYSV4) {
  		if (*sbi->s_sb_state == cpu_to_fs32(sbi, 0x7c269d38 - old_time))
  			*sbi->s_sb_state = cpu_to_fs32(sbi, 0x7c269d38 - time);
  		*sbi->s_sb_time = cpu_to_fs32(sbi, time);
  		mark_buffer_dirty(sbi->s_bh2);
  	}

  	unlock_super(sb);

  
  	return 0;
  }
  
  static void sysv_write_super(struct super_block *sb)
  {
  	if (!(sb->s_flags & MS_RDONLY))
  		sysv_sync_fs(sb, 1);
  	else
  		sb->s_dirt = 0;

  }
  
  static int sysv_remount(struct super_block *sb, int *flags, char *data)
  {
  	struct sysv_sb_info *sbi = SYSV_SB(sb);

  	lock_super(sb);

  	if (sbi->s_forced_ro)
  		*flags |= MS_RDONLY;

  	if (*flags & MS_RDONLY)
  		sysv_write_super(sb);

  	unlock_super(sb);

  	return 0;
  }
  
  static void sysv_put_super(struct super_block *sb)
  {
  	struct sysv_sb_info *sbi = SYSV_SB(sb);

  	if (sb->s_dirt)
  		sysv_write_super(sb);

  	if (!(sb->s_flags & MS_RDONLY)) {
  		/* XXX ext2 also updates the state here */
  		mark_buffer_dirty(sbi->s_bh1);
  		if (sbi->s_bh1 != sbi->s_bh2)
  			mark_buffer_dirty(sbi->s_bh2);
  	}
  
  	brelse(sbi->s_bh1);
  	if (sbi->s_bh1 != sbi->s_bh2)
  		brelse(sbi->s_bh2);
  
  	kfree(sbi);
  }

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

  {

  	struct super_block *sb = dentry->d_sb;

  	struct sysv_sb_info *sbi = SYSV_SB(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 = sbi->s_ndatazones;
  	buf->f_bavail = buf->f_bfree = sysv_count_free_blocks(sb);
  	buf->f_files = sbi->s_ninodes;
  	buf->f_ffree = sysv_count_free_inodes(sb);
  	buf->f_namelen = SYSV_NAMELEN;

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

  	return 0;
  }
  
  /* 
   * NXI <-> N0XI for PDP, XIN <-> XIN0 for le32, NIX <-> 0NIX for be32
   */
  static inline void read3byte(struct sysv_sb_info *sbi,
  	unsigned char * from, unsigned char * to)
  {
  	if (sbi->s_bytesex == BYTESEX_PDP) {
  		to[0] = from[0];
  		to[1] = 0;
  		to[2] = from[1];
  		to[3] = from[2];
  	} else if (sbi->s_bytesex == BYTESEX_LE) {
  		to[0] = from[0];
  		to[1] = from[1];
  		to[2] = from[2];
  		to[3] = 0;
  	} else {
  		to[0] = 0;
  		to[1] = from[0];
  		to[2] = from[1];
  		to[3] = from[2];
  	}
  }
  
  static inline void write3byte(struct sysv_sb_info *sbi,
  	unsigned char * from, unsigned char * to)
  {
  	if (sbi->s_bytesex == BYTESEX_PDP) {
  		to[0] = from[0];
  		to[1] = from[2];
  		to[2] = from[3];
  	} else if (sbi->s_bytesex == BYTESEX_LE) {
  		to[0] = from[0];
  		to[1] = from[1];
  		to[2] = from[2];
  	} else {
  		to[0] = from[1];
  		to[1] = from[2];
  		to[2] = from[3];
  	}
  }

  static const struct inode_operations sysv_symlink_inode_operations = {

  	.readlink	= generic_readlink,
  	.follow_link	= page_follow_link_light,
  	.put_link	= page_put_link,
  	.getattr	= sysv_getattr,
  };
  
  void sysv_set_inode(struct inode *inode, dev_t rdev)
  {
  	if (S_ISREG(inode->i_mode)) {
  		inode->i_op = &sysv_file_inode_operations;
  		inode->i_fop = &sysv_file_operations;
  		inode->i_mapping->a_ops = &sysv_aops;
  	} else if (S_ISDIR(inode->i_mode)) {
  		inode->i_op = &sysv_dir_inode_operations;
  		inode->i_fop = &sysv_dir_operations;
  		inode->i_mapping->a_ops = &sysv_aops;
  	} else if (S_ISLNK(inode->i_mode)) {
  		if (inode->i_blocks) {
  			inode->i_op = &sysv_symlink_inode_operations;
  			inode->i_mapping->a_ops = &sysv_aops;

  		} else {

  			inode->i_op = &sysv_fast_symlink_inode_operations;

  			nd_terminate_link(SYSV_I(inode)->i_data, inode->i_size,
  				sizeof(SYSV_I(inode)->i_data) - 1);
  		}

  	} else
  		init_special_inode(inode, inode->i_mode, rdev);
  }

  struct inode *sysv_iget(struct super_block *sb, unsigned int ino)

  {

  	struct sysv_sb_info * sbi = SYSV_SB(sb);
  	struct buffer_head * bh;
  	struct sysv_inode * raw_inode;
  	struct sysv_inode_info * si;

  	struct inode *inode;
  	unsigned int block;

  
  	if (!ino || ino > sbi->s_ninodes) {
  		printk("Bad inode number on dev %s: %d is out of range
  ",

  		       sb->s_id, ino);
  		return ERR_PTR(-EIO);

  	}

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

  	raw_inode = sysv_raw_inode(sb, ino, &bh);
  	if (!raw_inode) {
  		printk("Major problem: unable to read inode from dev %s
  ",
  		       inode->i_sb->s_id);
  		goto bad_inode;
  	}
  	/* SystemV FS: kludge permissions if ino==SYSV_ROOT_INO ?? */
  	inode->i_mode = fs16_to_cpu(sbi, raw_inode->i_mode);
  	inode->i_uid = (uid_t)fs16_to_cpu(sbi, raw_inode->i_uid);
  	inode->i_gid = (gid_t)fs16_to_cpu(sbi, raw_inode->i_gid);

  	set_nlink(inode, fs16_to_cpu(sbi, raw_inode->i_nlink));

  	inode->i_size = fs32_to_cpu(sbi, raw_inode->i_size);
  	inode->i_atime.tv_sec = fs32_to_cpu(sbi, raw_inode->i_atime);
  	inode->i_mtime.tv_sec = fs32_to_cpu(sbi, raw_inode->i_mtime);
  	inode->i_ctime.tv_sec = fs32_to_cpu(sbi, raw_inode->i_ctime);
  	inode->i_ctime.tv_nsec = 0;
  	inode->i_atime.tv_nsec = 0;
  	inode->i_mtime.tv_nsec = 0;

  	inode->i_blocks = 0;

  
  	si = SYSV_I(inode);
  	for (block = 0; block < 10+1+1+1; block++)
  		read3byte(sbi, &raw_inode->i_data[3*block],
  				(u8 *)&si->i_data[block]);
  	brelse(bh);
  	si->i_dir_start_lookup = 0;
  	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
  		sysv_set_inode(inode,
  			       old_decode_dev(fs32_to_cpu(sbi, si->i_data[0])));
  	else
  		sysv_set_inode(inode, 0);

  	unlock_new_inode(inode);
  	return inode;

  
  bad_inode:

  	iget_failed(inode);
  	return ERR_PTR(-EIO);

  }

  static int __sysv_write_inode(struct inode *inode, int wait)

  {
  	struct super_block * sb = inode->i_sb;
  	struct sysv_sb_info * sbi = SYSV_SB(sb);
  	struct buffer_head * bh;
  	struct sysv_inode * raw_inode;
  	struct sysv_inode_info * si;
  	unsigned int ino, block;

  	int err = 0;

  
  	ino = inode->i_ino;
  	if (!ino || ino > sbi->s_ninodes) {
  		printk("Bad inode number on dev %s: %d is out of range
  ",
  		       inode->i_sb->s_id, ino);

  		return -EIO;

  	}
  	raw_inode = sysv_raw_inode(sb, ino, &bh);
  	if (!raw_inode) {
  		printk("unable to read i-node block
  ");

  		return -EIO;

  	}
  
  	raw_inode->i_mode = cpu_to_fs16(sbi, inode->i_mode);
  	raw_inode->i_uid = cpu_to_fs16(sbi, fs_high2lowuid(inode->i_uid));
  	raw_inode->i_gid = cpu_to_fs16(sbi, fs_high2lowgid(inode->i_gid));
  	raw_inode->i_nlink = cpu_to_fs16(sbi, inode->i_nlink);
  	raw_inode->i_size = cpu_to_fs32(sbi, inode->i_size);
  	raw_inode->i_atime = cpu_to_fs32(sbi, inode->i_atime.tv_sec);
  	raw_inode->i_mtime = cpu_to_fs32(sbi, inode->i_mtime.tv_sec);
  	raw_inode->i_ctime = cpu_to_fs32(sbi, inode->i_ctime.tv_sec);
  
  	si = SYSV_I(inode);
  	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
  		si->i_data[0] = cpu_to_fs32(sbi, old_encode_dev(inode->i_rdev));
  	for (block = 0; block < 10+1+1+1; block++)
  		write3byte(sbi, (u8 *)&si->i_data[block],
  			&raw_inode->i_data[3*block]);
  	mark_buffer_dirty(bh);

  	if (wait) {
                  sync_dirty_buffer(bh);
                  if (buffer_req(bh) && !buffer_uptodate(bh)) {
                          printk ("IO error syncing sysv inode [%s:%08x]
  ",
                                  sb->s_id, ino);
                          err = -EIO;
                  }
          }

  	brelse(bh);

  	return 0;
  }

  int sysv_write_inode(struct inode *inode, struct writeback_control *wbc)
  {
  	return __sysv_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
  }

  int sysv_sync_inode(struct inode *inode)

  {

  	return __sysv_write_inode(inode, 1);

  }

  static void sysv_evict_inode(struct inode *inode)

  {

  	truncate_inode_pages(&inode->i_data, 0);

  	if (!inode->i_nlink) {
  		inode->i_size = 0;
  		sysv_truncate(inode);
  	}
  	invalidate_inode_buffers(inode);
  	end_writeback(inode);
  	if (!inode->i_nlink)
  		sysv_free_inode(inode);

  }

  static struct kmem_cache *sysv_inode_cachep;

  
  static struct inode *sysv_alloc_inode(struct super_block *sb)
  {
  	struct sysv_inode_info *si;

  	si = kmem_cache_alloc(sysv_inode_cachep, GFP_KERNEL);

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

  static void sysv_i_callback(struct rcu_head *head)

  {

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

  	kmem_cache_free(sysv_inode_cachep, SYSV_I(inode));
  }

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

  static void init_once(void *p)

  {
  	struct sysv_inode_info *si = (struct sysv_inode_info *)p;

  	inode_init_once(&si->vfs_inode);

  }

  const struct super_operations sysv_sops = {

  	.alloc_inode	= sysv_alloc_inode,
  	.destroy_inode	= sysv_destroy_inode,

  	.write_inode	= sysv_write_inode,

  	.evict_inode	= sysv_evict_inode,

  	.put_super	= sysv_put_super,
  	.write_super	= sysv_write_super,

  	.sync_fs	= sysv_sync_fs,

  	.remount_fs	= sysv_remount,
  	.statfs		= sysv_statfs,
  };
  
  int __init sysv_init_icache(void)
  {
  	sysv_inode_cachep = kmem_cache_create("sysv_inode_cache",
  			sizeof(struct sysv_inode_info), 0,

  			SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,

  			init_once);

  	if (!sysv_inode_cachep)
  		return -ENOMEM;
  	return 0;
  }
  
  void sysv_destroy_icache(void)
  {
  	kmem_cache_destroy(sysv_inode_cachep);
  }