// SPDX-License-Identifier: GPL-2.0

  /*
   * super.c
   *
   * Copyright (c) 1999 Al Smith
   *
   * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
   */
  
  #include <linux/init.h>
  #include <linux/module.h>

  #include <linux/exportfs.h>

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

  #include <linux/blkdev.h>

  #include "efs.h"
  #include <linux/efs_vh.h>
  #include <linux/efs_fs_sb.h>

  static int efs_statfs(struct dentry *dentry, struct kstatfs *buf);

  static int efs_fill_super(struct super_block *s, void *d, int silent);

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

  {

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

  }

  static void efs_kill_sb(struct super_block *s)
  {
  	struct efs_sb_info *sbi = SUPER_INFO(s);
  	kill_block_super(s);
  	kfree(sbi);
  }

  static struct file_system_type efs_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "efs",

  	.mount		= efs_mount,

  	.kill_sb	= efs_kill_sb,

  	.fs_flags	= FS_REQUIRES_DEV,
  };

  MODULE_ALIAS_FS("efs");

  
  static struct pt_types sgi_pt_types[] = {
  	{0x00,		"SGI vh"},
  	{0x01,		"SGI trkrepl"},
  	{0x02,		"SGI secrepl"},
  	{0x03,		"SGI raw"},
  	{0x04,		"SGI bsd"},
  	{SGI_SYSV,	"SGI sysv"},
  	{0x06,		"SGI vol"},
  	{SGI_EFS,	"SGI efs"},
  	{0x08,		"SGI lv"},
  	{0x09,		"SGI rlv"},
  	{0x0A,		"SGI xfs"},
  	{0x0B,		"SGI xfslog"},
  	{0x0C,		"SGI xlv"},
  	{0x82,		"Linux swap"},
  	{0x83,		"Linux native"},
  	{0,		NULL}
  };

  static struct kmem_cache * efs_inode_cachep;

  
  static struct inode *efs_alloc_inode(struct super_block *sb)
  {
  	struct efs_inode_info *ei;

  	ei = kmem_cache_alloc(efs_inode_cachep, GFP_KERNEL);

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

  static void efs_free_inode(struct inode *inode)

  {
  	kmem_cache_free(efs_inode_cachep, INODE_INFO(inode));
  }

  static void init_once(void *foo)

  {
  	struct efs_inode_info *ei = (struct efs_inode_info *) foo;

  	inode_init_once(&ei->vfs_inode);

  }

  static int __init init_inodecache(void)

  {
  	efs_inode_cachep = kmem_cache_create("efs_inode_cache",

  				sizeof(struct efs_inode_info), 0,
  				SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD|
  				SLAB_ACCOUNT, init_once);

  	if (efs_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(efs_inode_cachep);

  }

  static int efs_remount(struct super_block *sb, int *flags, char *data)
  {

  	sync_filesystem(sb);

  	*flags |= SB_RDONLY;

  	return 0;
  }

  static const struct super_operations efs_superblock_operations = {

  	.alloc_inode	= efs_alloc_inode,

  	.free_inode	= efs_free_inode,

  	.statfs		= efs_statfs,
  	.remount_fs	= efs_remount,
  };

  static const struct export_operations efs_export_ops = {

  	.fh_to_dentry	= efs_fh_to_dentry,
  	.fh_to_parent	= efs_fh_to_parent,

  	.get_parent	= efs_get_parent,
  };
  
  static int __init init_efs_fs(void) {
  	int err;

  	pr_info(EFS_VERSION" - http://aeschi.ch.eu.org/efs/
  ");

  	err = init_inodecache();
  	if (err)
  		goto out1;
  	err = register_filesystem(&efs_fs_type);
  	if (err)
  		goto out;
  	return 0;
  out:
  	destroy_inodecache();
  out1:
  	return err;
  }
  
  static void __exit exit_efs_fs(void) {
  	unregister_filesystem(&efs_fs_type);
  	destroy_inodecache();
  }
  
  module_init(init_efs_fs)
  module_exit(exit_efs_fs)
  
  static efs_block_t efs_validate_vh(struct volume_header *vh) {
  	int		i;
  	__be32		cs, *ui;
  	int		csum;
  	efs_block_t	sblock = 0; /* shuts up gcc */
  	struct pt_types	*pt_entry;
  	int		pt_type, slice = -1;
  
  	if (be32_to_cpu(vh->vh_magic) != VHMAGIC) {
  		/*
  		 * assume that we're dealing with a partition and allow
  		 * read_super() to try and detect a valid superblock
  		 * on the next block.
  		 */
  		return 0;
  	}
  
  	ui = ((__be32 *) (vh + 1)) - 1;
  	for(csum = 0; ui >= ((__be32 *) vh);) {
  		cs = *ui--;
  		csum += be32_to_cpu(cs);
  	}
  	if (csum) {

  		pr_warn("SGI disklabel: checksum bad, label corrupted
  ");

  		return 0;
  	}
  
  #ifdef DEBUG

  	pr_debug("bf: \"%16s\"
  ", vh->vh_bootfile);

  
  	for(i = 0; i < NVDIR; i++) {
  		int	j;
  		char	name[VDNAMESIZE+1];
  
  		for(j = 0; j < VDNAMESIZE; j++) {
  			name[j] = vh->vh_vd[i].vd_name[j];
  		}
  		name[j] = (char) 0;
  
  		if (name[0]) {

  			pr_debug("vh: %8s block: 0x%08x size: 0x%08x
  ",
  				name, (int) be32_to_cpu(vh->vh_vd[i].vd_lbn),

  				(int) be32_to_cpu(vh->vh_vd[i].vd_nbytes));
  		}
  	}
  #endif
  
  	for(i = 0; i < NPARTAB; i++) {
  		pt_type = (int) be32_to_cpu(vh->vh_pt[i].pt_type);
  		for(pt_entry = sgi_pt_types; pt_entry->pt_name; pt_entry++) {
  			if (pt_type == pt_entry->pt_type) break;
  		}
  #ifdef DEBUG
  		if (be32_to_cpu(vh->vh_pt[i].pt_nblks)) {

  			pr_debug("pt %2d: start: %08d size: %08d type: 0x%02x (%s)
  ",
  				 i, (int)be32_to_cpu(vh->vh_pt[i].pt_firstlbn),
  				 (int)be32_to_cpu(vh->vh_pt[i].pt_nblks),
  				 pt_type, (pt_entry->pt_name) ?
  				 pt_entry->pt_name : "unknown");

  		}
  #endif
  		if (IS_EFS(pt_type)) {
  			sblock = be32_to_cpu(vh->vh_pt[i].pt_firstlbn);
  			slice = i;
  		}
  	}
  
  	if (slice == -1) {

  		pr_notice("partition table contained no EFS partitions
  ");

  #ifdef DEBUG
  	} else {

  		pr_info("using slice %d (type %s, offset 0x%x)
  ", slice,

  			(pt_entry->pt_name) ? pt_entry->pt_name : "unknown",
  			sblock);
  #endif
  	}

  	return sblock;

  }
  
  static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {

  	if (!IS_EFS_MAGIC(be32_to_cpu(super->fs_magic)))
  		return -1;

  
  	sb->fs_magic     = be32_to_cpu(super->fs_magic);
  	sb->total_blocks = be32_to_cpu(super->fs_size);
  	sb->first_block  = be32_to_cpu(super->fs_firstcg);
  	sb->group_size   = be32_to_cpu(super->fs_cgfsize);
  	sb->data_free    = be32_to_cpu(super->fs_tfree);
  	sb->inode_free   = be32_to_cpu(super->fs_tinode);
  	sb->inode_blocks = be16_to_cpu(super->fs_cgisize);
  	sb->total_groups = be16_to_cpu(super->fs_ncg);
      
  	return 0;    
  }
  
  static int efs_fill_super(struct super_block *s, void *d, int silent)
  {
  	struct efs_sb_info *sb;
  	struct buffer_head *bh;
  	struct inode *root;

   	sb = kzalloc(sizeof(struct efs_sb_info), GFP_KERNEL);

  	if (!sb)
  		return -ENOMEM;
  	s->s_fs_info = sb;

  	s->s_time_min = 0;
  	s->s_time_max = U32_MAX;

   
  	s->s_magic		= EFS_SUPER_MAGIC;
  	if (!sb_set_blocksize(s, EFS_BLOCKSIZE)) {

  		pr_err("device does not support %d byte blocks
  ",

  			EFS_BLOCKSIZE);

  		return -EINVAL;

  	}
    
  	/* read the vh (volume header) block */
  	bh = sb_bread(s, 0);
  
  	if (!bh) {

  		pr_err("cannot read volume header
  ");

  		return -EIO;

  	}
  
  	/*
  	 * if this returns zero then we didn't find any partition table.
  	 * this isn't (yet) an error - just assume for the moment that
  	 * the device is valid and go on to search for a superblock.
  	 */
  	sb->fs_start = efs_validate_vh((struct volume_header *) bh->b_data);
  	brelse(bh);
  
  	if (sb->fs_start == -1) {

  		return -EINVAL;

  	}
  
  	bh = sb_bread(s, sb->fs_start + EFS_SUPER);
  	if (!bh) {

  		pr_err("cannot read superblock
  ");

  		return -EIO;

  	}
  		
  	if (efs_validate_super(sb, (struct efs_super *) bh->b_data)) {
  #ifdef DEBUG

  		pr_warn("invalid superblock at block %u
  ",
  			sb->fs_start + EFS_SUPER);

  #endif
  		brelse(bh);

  		return -EINVAL;

  	}
  	brelse(bh);

  	if (!sb_rdonly(s)) {

  #ifdef DEBUG

  		pr_info("forcing read-only mode
  ");

  #endif

  		s->s_flags |= SB_RDONLY;

  	}
  	s->s_op   = &efs_superblock_operations;
  	s->s_export_op = &efs_export_ops;

  	root = efs_iget(s, EFS_ROOTINODE);
  	if (IS_ERR(root)) {

  		pr_err("get root inode failed
  ");

  		return PTR_ERR(root);

  	}

  	s->s_root = d_make_root(root);

  	if (!(s->s_root)) {

  		pr_err("get root dentry failed
  ");

  		return -ENOMEM;

  	}
  
  	return 0;

  }

  static int efs_statfs(struct dentry *dentry, struct kstatfs *buf) {

  	struct super_block *sb = dentry->d_sb;
  	struct efs_sb_info *sbi = SUPER_INFO(sb);
  	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

  
  	buf->f_type    = EFS_SUPER_MAGIC;	/* efs magic number */
  	buf->f_bsize   = EFS_BLOCKSIZE;		/* blocksize */

  	buf->f_blocks  = sbi->total_groups *	/* total data blocks */
  			(sbi->group_size - sbi->inode_blocks);
  	buf->f_bfree   = sbi->data_free;	/* free data blocks */
  	buf->f_bavail  = sbi->data_free;	/* free blocks for non-root */
  	buf->f_files   = sbi->total_groups *	/* total inodes */
  			sbi->inode_blocks *

  			(EFS_BLOCKSIZE / sizeof(struct efs_dinode));

  	buf->f_ffree   = sbi->inode_free;	/* free inodes */

  	buf->f_fsid    = u64_to_fsid(id);

  	buf->f_namelen = EFS_MAXNAMELEN;	/* max filename length */
  
  	return 0;
  }