/*
   * ifile.c - NILFS inode file
   *
   * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   *
   * Written by Amagai Yoshiji <amagai@osrg.net>.
   * Revised by Ryusuke Konishi <ryusuke@osrg.net>.
   *
   */
  
  #include <linux/types.h>
  #include <linux/buffer_head.h>
  #include "nilfs.h"
  #include "mdt.h"
  #include "alloc.h"
  #include "ifile.h"
  
  /**
   * struct nilfs_ifile_info - on-memory private data of ifile
   * @mi: on-memory private data of metadata file
   * @palloc_cache: persistent object allocator cache of ifile
   */
  struct nilfs_ifile_info {
  	struct nilfs_mdt_info mi;
  	struct nilfs_palloc_cache palloc_cache;
  };
  
  static inline struct nilfs_ifile_info *NILFS_IFILE_I(struct inode *ifile)
  {
  	return (struct nilfs_ifile_info *)NILFS_MDT(ifile);
  }
  
  /**
   * nilfs_ifile_create_inode - create a new disk inode
   * @ifile: ifile inode
   * @out_ino: pointer to a variable to store inode number
   * @out_bh: buffer_head contains newly allocated disk inode
   *
   * Return Value: On success, 0 is returned and the newly allocated inode
   * number is stored in the place pointed by @ino, and buffer_head pointer
   * that contains newly allocated disk inode structure is stored in the
   * place pointed by @out_bh
   * On error, one of the following negative error codes is returned.
   *
   * %-EIO - I/O error.
   *
   * %-ENOMEM - Insufficient amount of memory available.
   *
   * %-ENOSPC - No inode left.
   */
  int nilfs_ifile_create_inode(struct inode *ifile, ino_t *out_ino,
  			     struct buffer_head **out_bh)
  {
  	struct nilfs_palloc_req req;
  	int ret;
  
  	req.pr_entry_nr = 0;  /* 0 says find free inode from beginning of
  				 a group. dull code!! */
  	req.pr_entry_bh = NULL;
  
  	ret = nilfs_palloc_prepare_alloc_entry(ifile, &req);
  	if (!ret) {
  		ret = nilfs_palloc_get_entry_block(ifile, req.pr_entry_nr, 1,
  						   &req.pr_entry_bh);
  		if (ret < 0)
  			nilfs_palloc_abort_alloc_entry(ifile, &req);
  	}
  	if (ret < 0) {
  		brelse(req.pr_entry_bh);
  		return ret;
  	}
  	nilfs_palloc_commit_alloc_entry(ifile, &req);
  	mark_buffer_dirty(req.pr_entry_bh);
  	nilfs_mdt_mark_dirty(ifile);
  	*out_ino = (ino_t)req.pr_entry_nr;
  	*out_bh = req.pr_entry_bh;
  	return 0;
  }
  
  /**
   * nilfs_ifile_delete_inode - delete a disk inode
   * @ifile: ifile inode
   * @ino: inode number
   *
   * Return Value: On success, 0 is returned. On error, one of the following
   * negative error codes is returned.
   *
   * %-EIO - I/O error.
   *
   * %-ENOMEM - Insufficient amount of memory available.
   *
   * %-ENOENT - The inode number @ino have not been allocated.
   */
  int nilfs_ifile_delete_inode(struct inode *ifile, ino_t ino)
  {
  	struct nilfs_palloc_req req = {
  		.pr_entry_nr = ino, .pr_entry_bh = NULL
  	};
  	struct nilfs_inode *raw_inode;
  	void *kaddr;
  	int ret;
  
  	ret = nilfs_palloc_prepare_free_entry(ifile, &req);
  	if (!ret) {
  		ret = nilfs_palloc_get_entry_block(ifile, req.pr_entry_nr, 0,
  						   &req.pr_entry_bh);
  		if (ret < 0)
  			nilfs_palloc_abort_free_entry(ifile, &req);
  	}
  	if (ret < 0) {
  		brelse(req.pr_entry_bh);
  		return ret;
  	}
  
  	kaddr = kmap_atomic(req.pr_entry_bh->b_page);
  	raw_inode = nilfs_palloc_block_get_entry(ifile, req.pr_entry_nr,
  						 req.pr_entry_bh, kaddr);
  	raw_inode->i_flags = 0;
  	kunmap_atomic(kaddr);
  
  	mark_buffer_dirty(req.pr_entry_bh);
  	brelse(req.pr_entry_bh);
  
  	nilfs_palloc_commit_free_entry(ifile, &req);
  
  	return 0;
  }
  
  int nilfs_ifile_get_inode_block(struct inode *ifile, ino_t ino,
  				struct buffer_head **out_bh)
  {
  	struct super_block *sb = ifile->i_sb;
  	int err;
  
  	if (unlikely(!NILFS_VALID_INODE(sb, ino))) {
  		nilfs_error(sb, __func__, "bad inode number: %lu",
  			    (unsigned long) ino);
  		return -EINVAL;
  	}
  
  	err = nilfs_palloc_get_entry_block(ifile, ino, 0, out_bh);
  	if (unlikely(err))
  		nilfs_warning(sb, __func__, "unable to read inode: %lu",
  			      (unsigned long) ino);
  	return err;
  }
  
  /**
   * nilfs_ifile_count_free_inodes - calculate free inodes count
   * @ifile: ifile inode
   * @nmaxinodes: current maximum of available inodes count [out]
   * @nfreeinodes: free inodes count [out]
   */
  int nilfs_ifile_count_free_inodes(struct inode *ifile,
  				    u64 *nmaxinodes, u64 *nfreeinodes)
  {
  	u64 nused;
  	int err;
  
  	*nmaxinodes = 0;
  	*nfreeinodes = 0;
  
  	nused = atomic64_read(&NILFS_I(ifile)->i_root->inodes_count);
  	err = nilfs_palloc_count_max_entries(ifile, nused, nmaxinodes);
  	if (likely(!err))
  		*nfreeinodes = *nmaxinodes - nused;
  	return err;
  }
  
  /**
   * nilfs_ifile_read - read or get ifile inode
   * @sb: super block instance
   * @root: root object
   * @inode_size: size of an inode
   * @raw_inode: on-disk ifile inode
   * @inodep: buffer to store the inode
   */
  int nilfs_ifile_read(struct super_block *sb, struct nilfs_root *root,
  		     size_t inode_size, struct nilfs_inode *raw_inode,
  		     struct inode **inodep)
  {
  	struct inode *ifile;
  	int err;
  
  	ifile = nilfs_iget_locked(sb, root, NILFS_IFILE_INO);
  	if (unlikely(!ifile))
  		return -ENOMEM;
  	if (!(ifile->i_state & I_NEW))
  		goto out;
  
  	err = nilfs_mdt_init(ifile, NILFS_MDT_GFP,
  			     sizeof(struct nilfs_ifile_info));
  	if (err)
  		goto failed;
  
  	err = nilfs_palloc_init_blockgroup(ifile, inode_size);
  	if (err)
  		goto failed;
  
  	nilfs_palloc_setup_cache(ifile, &NILFS_IFILE_I(ifile)->palloc_cache);
  
  	err = nilfs_read_inode_common(ifile, raw_inode);
  	if (err)
  		goto failed;
  
  	unlock_new_inode(ifile);
   out:
  	*inodep = ifile;
  	return 0;
   failed:
  	iget_failed(ifile);
  	return err;
  }