/*
   * Copyright (c) 2000-2001 Christoph Hellwig.

   * Copyright (c) 2016 Krzysztof Blaszkowski

   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions, and the following disclaimer,
   *    without modification.
   * 2. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL").
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  /*
   * Veritas filesystem driver - superblock related routines.
   */
  #include <linux/init.h>
  #include <linux/module.h>
  
  #include <linux/blkdev.h>
  #include <linux/fs.h>
  #include <linux/buffer_head.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/stat.h>
  #include <linux/vfs.h>

  #include <linux/mount.h>

  
  #include "vxfs.h"
  #include "vxfs_extern.h"
  #include "vxfs_dir.h"
  #include "vxfs_inode.h"

  MODULE_AUTHOR("Christoph Hellwig, Krzysztof Blaszkowski");

  MODULE_DESCRIPTION("Veritas Filesystem (VxFS) driver");
  MODULE_LICENSE("Dual BSD/GPL");

  static struct kmem_cache *vxfs_inode_cachep;

  /**
   * vxfs_put_super - free superblock resources
   * @sbp:	VFS superblock.
   *
   * Description:
   *   vxfs_put_super frees all resources allocated for @sbp
   *   after the last instance of the filesystem is unmounted.
   */
  
  static void
  vxfs_put_super(struct super_block *sbp)
  {
  	struct vxfs_sb_info	*infp = VXFS_SBI(sbp);

  	iput(infp->vsi_fship);
  	iput(infp->vsi_ilist);
  	iput(infp->vsi_stilist);

  
  	brelse(infp->vsi_bp);
  	kfree(infp);
  }
  
  /**
   * vxfs_statfs - get filesystem information

   * @dentry:	VFS dentry to locate superblock

   * @bufp:	output buffer
   *
   * Description:
   *   vxfs_statfs fills the statfs buffer @bufp with information

   *   about the filesystem described by @dentry.

   *
   * Returns:
   *   Zero.
   *
   * Locking:
   *   No locks held.
   *
   * Notes:
   *   This is everything but complete...
   */
  static int

  vxfs_statfs(struct dentry *dentry, struct kstatfs *bufp)

  {

  	struct vxfs_sb_info		*infp = VXFS_SBI(dentry->d_sb);

  	struct vxfs_sb *raw_sb = infp->vsi_raw;

  
  	bufp->f_type = VXFS_SUPER_MAGIC;

  	bufp->f_bsize = dentry->d_sb->s_blocksize;

  	bufp->f_blocks = fs32_to_cpu(infp, raw_sb->vs_dsize);
  	bufp->f_bfree = fs32_to_cpu(infp, raw_sb->vs_free);

  	bufp->f_bavail = 0;
  	bufp->f_files = 0;

  	bufp->f_ffree = fs32_to_cpu(infp, raw_sb->vs_ifree);

  	bufp->f_namelen = VXFS_NAMELEN;
  
  	return 0;
  }
  
  static int vxfs_remount(struct super_block *sb, int *flags, char *data)
  {

  	sync_filesystem(sb);

  	*flags |= MS_RDONLY;
  	return 0;
  }

  static struct inode *vxfs_alloc_inode(struct super_block *sb)
  {
  	struct vxfs_inode_info *vi;
  
  	vi = kmem_cache_alloc(vxfs_inode_cachep, GFP_KERNEL);
  	if (!vi)
  		return NULL;

  	inode_init_once(&vi->vfs_inode);

  	return &vi->vfs_inode;
  }
  
  static void vxfs_i_callback(struct rcu_head *head)
  {
  	struct inode *inode = container_of(head, struct inode, i_rcu);
  
  	kmem_cache_free(vxfs_inode_cachep, VXFS_INO(inode));
  }
  
  static void vxfs_destroy_inode(struct inode *inode)
  {
  	call_rcu(&inode->i_rcu, vxfs_i_callback);
  }

  static const struct super_operations vxfs_super_ops = {

  	.alloc_inode		= vxfs_alloc_inode,
  	.destroy_inode		= vxfs_destroy_inode,

  	.evict_inode		= vxfs_evict_inode,
  	.put_super		= vxfs_put_super,
  	.statfs			= vxfs_statfs,
  	.remount_fs		= vxfs_remount,
  };

  
  static int vxfs_try_sb_magic(struct super_block *sbp, int silent,
  		unsigned blk, __fs32 magic)
  {
  	struct buffer_head *bp;
  	struct vxfs_sb *rsbp;
  	struct vxfs_sb_info *infp = VXFS_SBI(sbp);
  	int rc = -ENOMEM;
  
  	bp = sb_bread(sbp, blk);
  	do {
  		if (!bp || !buffer_mapped(bp)) {
  			if (!silent) {
  				printk(KERN_WARNING
  					"vxfs: unable to read disk superblock at %u
  ",
  					blk);
  			}
  			break;
  		}
  
  		rc = -EINVAL;
  		rsbp = (struct vxfs_sb *)bp->b_data;
  		if (rsbp->vs_magic != magic) {
  			if (!silent)
  				printk(KERN_NOTICE
  					"vxfs: WRONG superblock magic %08x at %u
  ",
  					rsbp->vs_magic, blk);
  			break;
  		}
  
  		rc = 0;
  		infp->vsi_raw = rsbp;
  		infp->vsi_bp = bp;
  	} while (0);
  
  	if (rc) {
  		infp->vsi_raw = NULL;
  		infp->vsi_bp = NULL;
  		brelse(bp);
  	}
  
  	return rc;
  }

  /**

   * vxfs_read_super - read superblock into memory and initialize filesystem

   * @sbp:		VFS superblock (to fill)
   * @dp:			fs private mount data
   * @silent:		do not complain loudly when sth is wrong
   *
   * Description:
   *   We are called on the first mount of a filesystem to read the
   *   superblock into memory and do some basic setup.
   *
   * Returns:
   *   The superblock on success, else %NULL.
   *
   * Locking:

   *   We are under @sbp->s_lock.

   */
  static int vxfs_fill_super(struct super_block *sbp, void *dp, int silent)
  {
  	struct vxfs_sb_info	*infp;
  	struct vxfs_sb		*rsbp;

  	u_long			bsize;
  	struct inode *root;

  	int ret = -EINVAL;

  	u32 j;

  
  	sbp->s_flags |= MS_RDONLY;

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

  	if (!infp) {
  		printk(KERN_WARNING "vxfs: unable to allocate incore superblock
  ");
  		return -ENOMEM;
  	}

  
  	bsize = sb_min_blocksize(sbp, BLOCK_SIZE);
  	if (!bsize) {
  		printk(KERN_WARNING "vxfs: unable to set blocksize
  ");
  		goto out;
  	}

  	sbp->s_op = &vxfs_super_ops;

  	sbp->s_fs_info = infp;

  	if (!vxfs_try_sb_magic(sbp, silent, 1,
  			(__force __fs32)cpu_to_le32(VXFS_SUPER_MAGIC))) {
  		/* Unixware, x86 */
  		infp->byte_order = VXFS_BO_LE;
  	} else if (!vxfs_try_sb_magic(sbp, silent, 8,
  			(__force __fs32)cpu_to_be32(VXFS_SUPER_MAGIC))) {
  		/* HP-UX, parisc */
  		infp->byte_order = VXFS_BO_BE;
  	} else {

  		if (!silent)

  			printk(KERN_NOTICE "vxfs: can't find superblock.
  ");

  		goto out;
  	}

  	rsbp = infp->vsi_raw;
  	j = fs32_to_cpu(infp, rsbp->vs_version);
  	if ((j < 2 || j > 4) && !silent) {
  		printk(KERN_NOTICE "vxfs: unsupported VxFS version (%d)
  ", j);

  		goto out;
  	}
  
  #ifdef DIAGNOSTIC

  	printk(KERN_DEBUG "vxfs: supported VxFS version (%d)
  ", j);
  	printk(KERN_DEBUG "vxfs: blocksize: %d
  ",
  		fs32_to_cpu(infp, rsbp->vs_bsize));

  #endif

  	sbp->s_magic = fs32_to_cpu(infp, rsbp->vs_magic);

  	infp->vsi_oltext = fs32_to_cpu(infp, rsbp->vs_oltext[0]);
  	infp->vsi_oltsize = fs32_to_cpu(infp, rsbp->vs_oltsize);

  	j = fs32_to_cpu(infp, rsbp->vs_bsize);
  	if (!sb_set_blocksize(sbp, j)) {

  		printk(KERN_WARNING "vxfs: unable to set final block size
  ");
  		goto out;
  	}
  
  	if (vxfs_read_olt(sbp, bsize)) {
  		printk(KERN_WARNING "vxfs: unable to read olt
  ");
  		goto out;
  	}
  
  	if (vxfs_read_fshead(sbp)) {
  		printk(KERN_WARNING "vxfs: unable to read fshead
  ");
  		goto out;
  	}

  	root = vxfs_iget(sbp, VXFS_ROOT_INO);
  	if (IS_ERR(root)) {
  		ret = PTR_ERR(root);
  		goto out;
  	}

  	sbp->s_root = d_make_root(root);

  	if (!sbp->s_root) {

  		printk(KERN_WARNING "vxfs: unable to get root dentry.
  ");
  		goto out_free_ilist;
  	}
  
  	return 0;
  	
  out_free_ilist:

  	iput(infp->vsi_fship);
  	iput(infp->vsi_ilist);
  	iput(infp->vsi_stilist);

  out:

  	brelse(infp->vsi_bp);

  	kfree(infp);

  	return ret;

  }
  
  /*
   * The usual module blurb.
   */

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

  {

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

  }
  
  static struct file_system_type vxfs_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "vxfs",

  	.mount		= vxfs_mount,

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

  MODULE_ALIAS_FS("vxfs"); /* makes mount -t vxfs autoload the module */

  MODULE_ALIAS("vxfs");

  
  static int __init
  vxfs_init(void)
  {

  	int rv;

  	vxfs_inode_cachep = kmem_cache_create("vxfs_inode",

  			sizeof(struct vxfs_inode_info), 0,
  			SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);

  	if (!vxfs_inode_cachep)
  		return -ENOMEM;
  	rv = register_filesystem(&vxfs_fs_type);
  	if (rv < 0)
  		kmem_cache_destroy(vxfs_inode_cachep);
  	return rv;

  }
  
  static void __exit
  vxfs_cleanup(void)
  {
  	unregister_filesystem(&vxfs_fs_type);

  	/*
  	 * Make sure all delayed rcu free inodes are flushed before we
  	 * destroy cache.
  	 */
  	rcu_barrier();

  	kmem_cache_destroy(vxfs_inode_cachep);
  }
  
  module_init(vxfs_init);
  module_exit(vxfs_cleanup);