/*
   * inode.c - NILFS inode operations.
   *
   * Copyright (C) 2005-2008 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 Ryusuke Konishi <ryusuke@osrg.net>
   *
   */
  
  #include <linux/buffer_head.h>

  #include <linux/gfp.h>

  #include <linux/mpage.h>
  #include <linux/writeback.h>

  #include <linux/uio.h>

  #include "nilfs.h"

  #include "btnode.h"

  #include "segment.h"
  #include "page.h"
  #include "mdt.h"
  #include "cpfile.h"
  #include "ifile.h"

  struct nilfs_iget_args {
  	u64 ino;
  	__u64 cno;

  	struct nilfs_root *root;

  	int for_gc;
  };

  void nilfs_inode_add_blocks(struct inode *inode, int n)
  {
  	struct nilfs_root *root = NILFS_I(inode)->i_root;
  
  	inode_add_bytes(inode, (1 << inode->i_blkbits) * n);
  	if (root)
  		atomic_add(n, &root->blocks_count);
  }
  
  void nilfs_inode_sub_blocks(struct inode *inode, int n)
  {
  	struct nilfs_root *root = NILFS_I(inode)->i_root;
  
  	inode_sub_bytes(inode, (1 << inode->i_blkbits) * n);
  	if (root)
  		atomic_sub(n, &root->blocks_count);
  }

  /**
   * nilfs_get_block() - get a file block on the filesystem (callback function)
   * @inode - inode struct of the target file
   * @blkoff - file block number
   * @bh_result - buffer head to be mapped on
   * @create - indicate whether allocating the block or not when it has not
   *      been allocated yet.
   *
   * This function does not issue actual read request of the specified data
   * block. It is done by VFS.

   */
  int nilfs_get_block(struct inode *inode, sector_t blkoff,
  		    struct buffer_head *bh_result, int create)
  {
  	struct nilfs_inode_info *ii = NILFS_I(inode);

  	struct the_nilfs *nilfs = inode->i_sb->s_fs_info;

  	__u64 blknum = 0;

  	int err = 0, ret;

  	unsigned maxblocks = bh_result->b_size >> inode->i_blkbits;

  	down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);

  	ret = nilfs_bmap_lookup_contig(ii->i_bmap, blkoff, &blknum, maxblocks);

  	up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);

  	if (ret >= 0) {	/* found */

  		map_bh(bh_result, inode->i_sb, blknum);

  		if (ret > 0)
  			bh_result->b_size = (ret << inode->i_blkbits);

  		goto out;
  	}

  	/* data block was not found */
  	if (ret == -ENOENT && create) {
  		struct nilfs_transaction_info ti;
  
  		bh_result->b_blocknr = 0;
  		err = nilfs_transaction_begin(inode->i_sb, &ti, 1);
  		if (unlikely(err))
  			goto out;
  		err = nilfs_bmap_insert(ii->i_bmap, (unsigned long)blkoff,
  					(unsigned long)bh_result);

  		if (unlikely(err != 0)) {
  			if (err == -EEXIST) {
  				/*
  				 * The get_block() function could be called
  				 * from multiple callers for an inode.
  				 * However, the page having this block must
  				 * be locked in this case.
  				 */

  				printk(KERN_WARNING

  				       "nilfs_get_block: a race condition "
  				       "while inserting a data block. "
  				       "(inode number=%lu, file block "
  				       "offset=%llu)
  ",
  				       inode->i_ino,
  				       (unsigned long long)blkoff);

  				err = 0;

  			}

  			nilfs_transaction_abort(inode->i_sb);

  			goto out;
  		}

  		nilfs_mark_inode_dirty(inode);

  		nilfs_transaction_commit(inode->i_sb); /* never fails */

  		/* Error handling should be detailed */
  		set_buffer_new(bh_result);

  		set_buffer_delay(bh_result);

  		map_bh(bh_result, inode->i_sb, 0); /* dbn must be changed
  						      to proper value */
  	} else if (ret == -ENOENT) {
  		/* not found is not error (e.g. hole); must return without
  		   the mapped state flag. */
  		;
  	} else {
  		err = ret;
  	}
  
   out:
  	return err;
  }
  
  /**
   * nilfs_readpage() - implement readpage() method of nilfs_aops {}
   * address_space_operations.
   * @file - file struct of the file to be read
   * @page - the page to be read
   */
  static int nilfs_readpage(struct file *file, struct page *page)
  {
  	return mpage_readpage(page, nilfs_get_block);
  }
  
  /**
   * nilfs_readpages() - implement readpages() method of nilfs_aops {}
   * address_space_operations.
   * @file - file struct of the file to be read
   * @mapping - address_space struct used for reading multiple pages
   * @pages - the pages to be read
   * @nr_pages - number of pages to be read
   */
  static int nilfs_readpages(struct file *file, struct address_space *mapping,
  			   struct list_head *pages, unsigned nr_pages)
  {
  	return mpage_readpages(mapping, pages, nr_pages, nilfs_get_block);
  }
  
  static int nilfs_writepages(struct address_space *mapping,
  			    struct writeback_control *wbc)
  {

  	struct inode *inode = mapping->host;
  	int err = 0;
  
  	if (wbc->sync_mode == WB_SYNC_ALL)
  		err = nilfs_construct_dsync_segment(inode->i_sb, inode,
  						    wbc->range_start,
  						    wbc->range_end);
  	return err;

  }
  
  static int nilfs_writepage(struct page *page, struct writeback_control *wbc)
  {
  	struct inode *inode = page->mapping->host;
  	int err;
  
  	redirty_page_for_writepage(wbc, page);
  	unlock_page(page);
  
  	if (wbc->sync_mode == WB_SYNC_ALL) {
  		err = nilfs_construct_segment(inode->i_sb);
  		if (unlikely(err))
  			return err;
  	} else if (wbc->for_reclaim)
  		nilfs_flush_segment(inode->i_sb, inode->i_ino);
  
  	return 0;
  }
  
  static int nilfs_set_page_dirty(struct page *page)
  {
  	int ret = __set_page_dirty_buffers(page);
  
  	if (ret) {
  		struct inode *inode = page->mapping->host;

  		unsigned nr_dirty = 1 << (PAGE_SHIFT - inode->i_blkbits);

  		nilfs_set_file_dirty(inode, nr_dirty);

  	}
  	return ret;
  }
  
  static int nilfs_write_begin(struct file *file, struct address_space *mapping,
  			     loff_t pos, unsigned len, unsigned flags,
  			     struct page **pagep, void **fsdata)
  
  {
  	struct inode *inode = mapping->host;
  	int err = nilfs_transaction_begin(inode->i_sb, NULL, 1);
  
  	if (unlikely(err))
  		return err;

  	err = block_write_begin(mapping, pos, len, flags, pagep,
  				nilfs_get_block);
  	if (unlikely(err)) {
  		loff_t isize = mapping->host->i_size;
  		if (pos + len > isize)
  			vmtruncate(mapping->host, isize);

  		nilfs_transaction_abort(inode->i_sb);

  	}

  	return err;
  }
  
  static int nilfs_write_end(struct file *file, struct address_space *mapping,
  			   loff_t pos, unsigned len, unsigned copied,
  			   struct page *page, void *fsdata)
  {
  	struct inode *inode = mapping->host;
  	unsigned start = pos & (PAGE_CACHE_SIZE - 1);
  	unsigned nr_dirty;
  	int err;
  
  	nr_dirty = nilfs_page_count_clean_buffers(page, start,
  						  start + copied);
  	copied = generic_write_end(file, mapping, pos, len, copied, page,
  				   fsdata);

  	nilfs_set_file_dirty(inode, nr_dirty);

  	err = nilfs_transaction_commit(inode->i_sb);

  	return err ? : copied;
  }
  
  static ssize_t
  nilfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
  		loff_t offset, unsigned long nr_segs)
  {
  	struct file *file = iocb->ki_filp;
  	struct inode *inode = file->f_mapping->host;
  	ssize_t size;

  
  	if (rw == WRITE)
  		return 0;
  
  	/* Needs synchronization with the cleaner */

  	size = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
  				  nilfs_get_block);

  
  	/*
  	 * In case of error extending write may have instantiated a few
  	 * blocks outside i_size. Trim these off again.
  	 */
  	if (unlikely((rw & WRITE) && size < 0)) {
  		loff_t isize = i_size_read(inode);
  		loff_t end = offset + iov_length(iov, nr_segs);
  
  		if (end > isize)
  			vmtruncate(inode, isize);
  	}

  	return size;
  }

  const struct address_space_operations nilfs_aops = {

  	.writepage		= nilfs_writepage,
  	.readpage		= nilfs_readpage,

  	.writepages		= nilfs_writepages,
  	.set_page_dirty		= nilfs_set_page_dirty,
  	.readpages		= nilfs_readpages,
  	.write_begin		= nilfs_write_begin,
  	.write_end		= nilfs_write_end,
  	/* .releasepage		= nilfs_releasepage, */
  	.invalidatepage		= block_invalidatepage,
  	.direct_IO		= nilfs_direct_IO,

  	.is_partially_uptodate  = block_is_partially_uptodate,

  };

  struct inode *nilfs_new_inode(struct inode *dir, umode_t mode)

  {
  	struct super_block *sb = dir->i_sb;

  	struct the_nilfs *nilfs = sb->s_fs_info;

  	struct inode *inode;
  	struct nilfs_inode_info *ii;

  	struct nilfs_root *root;

  	int err = -ENOMEM;
  	ino_t ino;
  
  	inode = new_inode(sb);
  	if (unlikely(!inode))
  		goto failed;
  
  	mapping_set_gfp_mask(inode->i_mapping,
  			     mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);

  	root = NILFS_I(dir)->i_root;

  	ii = NILFS_I(inode);
  	ii->i_state = 1 << NILFS_I_NEW;

  	ii->i_root = root;

  	err = nilfs_ifile_create_inode(root->ifile, &ino, &ii->i_bh);

  	if (unlikely(err))
  		goto failed_ifile_create_inode;
  	/* reference count of i_bh inherits from nilfs_mdt_read_block() */

  	atomic_inc(&root->inodes_count);

  	inode_init_owner(inode, dir, mode);

  	inode->i_ino = ino;
  	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  
  	if (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)) {
  		err = nilfs_bmap_read(ii->i_bmap, NULL);
  		if (err < 0)
  			goto failed_bmap;
  
  		set_bit(NILFS_I_BMAP, &ii->i_state);
  		/* No lock is needed; iget() ensures it. */
  	}

  	ii->i_flags = nilfs_mask_flags(
  		mode, NILFS_I(dir)->i_flags & NILFS_FL_INHERITED);

  
  	/* ii->i_file_acl = 0; */
  	/* ii->i_dir_acl = 0; */

  	ii->i_dir_start_lookup = 0;

  	nilfs_set_inode_flags(inode);

  	spin_lock(&nilfs->ns_next_gen_lock);
  	inode->i_generation = nilfs->ns_next_generation++;
  	spin_unlock(&nilfs->ns_next_gen_lock);

  	insert_inode_hash(inode);
  
  	err = nilfs_init_acl(inode, dir);
  	if (unlikely(err))
  		goto failed_acl; /* never occur. When supporting
  				    nilfs_init_acl(), proper cancellation of
  				    above jobs should be considered */

  	return inode;
  
   failed_acl:
   failed_bmap:

  	clear_nlink(inode);

  	iput(inode);  /* raw_inode will be deleted through
  			 generic_delete_inode() */
  	goto failed;
  
   failed_ifile_create_inode:
  	make_bad_inode(inode);
  	iput(inode);  /* if i_nlink == 1, generic_forget_inode() will be
  			 called */
   failed:
  	return ERR_PTR(err);
  }

  void nilfs_set_inode_flags(struct inode *inode)
  {
  	unsigned int flags = NILFS_I(inode)->i_flags;
  
  	inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
  			    S_DIRSYNC);

  	if (flags & FS_SYNC_FL)

  		inode->i_flags |= S_SYNC;

  	if (flags & FS_APPEND_FL)

  		inode->i_flags |= S_APPEND;

  	if (flags & FS_IMMUTABLE_FL)

  		inode->i_flags |= S_IMMUTABLE;

  	if (flags & FS_NOATIME_FL)

  		inode->i_flags |= S_NOATIME;

  	if (flags & FS_DIRSYNC_FL)

  		inode->i_flags |= S_DIRSYNC;
  	mapping_set_gfp_mask(inode->i_mapping,
  			     mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
  }
  
  int nilfs_read_inode_common(struct inode *inode,
  			    struct nilfs_inode *raw_inode)
  {
  	struct nilfs_inode_info *ii = NILFS_I(inode);
  	int err;
  
  	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
  	inode->i_uid = (uid_t)le32_to_cpu(raw_inode->i_uid);
  	inode->i_gid = (gid_t)le32_to_cpu(raw_inode->i_gid);

  	set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));

  	inode->i_size = le64_to_cpu(raw_inode->i_size);
  	inode->i_atime.tv_sec = le64_to_cpu(raw_inode->i_mtime);
  	inode->i_ctime.tv_sec = le64_to_cpu(raw_inode->i_ctime);
  	inode->i_mtime.tv_sec = le64_to_cpu(raw_inode->i_mtime);

  	inode->i_atime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);
  	inode->i_ctime.tv_nsec = le32_to_cpu(raw_inode->i_ctime_nsec);
  	inode->i_mtime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);
  	if (inode->i_nlink == 0 && inode->i_mode == 0)

  		return -EINVAL; /* this inode is deleted */
  
  	inode->i_blocks = le64_to_cpu(raw_inode->i_blocks);
  	ii->i_flags = le32_to_cpu(raw_inode->i_flags);
  #if 0
  	ii->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
  	ii->i_dir_acl = S_ISREG(inode->i_mode) ?
  		0 : le32_to_cpu(raw_inode->i_dir_acl);
  #endif

  	ii->i_dir_start_lookup = 0;

  	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
  
  	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
  	    S_ISLNK(inode->i_mode)) {
  		err = nilfs_bmap_read(ii->i_bmap, raw_inode);
  		if (err < 0)
  			return err;
  		set_bit(NILFS_I_BMAP, &ii->i_state);
  		/* No lock is needed; iget() ensures it. */
  	}
  	return 0;
  }

  static int __nilfs_read_inode(struct super_block *sb,
  			      struct nilfs_root *root, unsigned long ino,

  			      struct inode *inode)
  {

  	struct the_nilfs *nilfs = sb->s_fs_info;

  	struct buffer_head *bh;
  	struct nilfs_inode *raw_inode;
  	int err;

  	down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);

  	err = nilfs_ifile_get_inode_block(root->ifile, ino, &bh);

  	if (unlikely(err))
  		goto bad_inode;

  	raw_inode = nilfs_ifile_map_inode(root->ifile, ino, bh);

  	err = nilfs_read_inode_common(inode, raw_inode);
  	if (err)

  		goto failed_unmap;
  
  	if (S_ISREG(inode->i_mode)) {
  		inode->i_op = &nilfs_file_inode_operations;
  		inode->i_fop = &nilfs_file_operations;
  		inode->i_mapping->a_ops = &nilfs_aops;

  	} else if (S_ISDIR(inode->i_mode)) {
  		inode->i_op = &nilfs_dir_inode_operations;
  		inode->i_fop = &nilfs_dir_operations;
  		inode->i_mapping->a_ops = &nilfs_aops;
  	} else if (S_ISLNK(inode->i_mode)) {
  		inode->i_op = &nilfs_symlink_inode_operations;
  		inode->i_mapping->a_ops = &nilfs_aops;
  	} else {
  		inode->i_op = &nilfs_special_inode_operations;
  		init_special_inode(
  			inode, inode->i_mode,

  			huge_decode_dev(le64_to_cpu(raw_inode->i_device_code)));

  	}

  	nilfs_ifile_unmap_inode(root->ifile, ino, bh);

  	brelse(bh);

  	up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);

  	nilfs_set_inode_flags(inode);
  	return 0;
  
   failed_unmap:

  	nilfs_ifile_unmap_inode(root->ifile, ino, bh);

  	brelse(bh);
  
   bad_inode:

  	up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);

  	return err;
  }

  static int nilfs_iget_test(struct inode *inode, void *opaque)
  {
  	struct nilfs_iget_args *args = opaque;
  	struct nilfs_inode_info *ii;

  	if (args->ino != inode->i_ino || args->root != NILFS_I(inode)->i_root)

  		return 0;
  
  	ii = NILFS_I(inode);
  	if (!test_bit(NILFS_I_GCINODE, &ii->i_state))
  		return !args->for_gc;
  
  	return args->for_gc && args->cno == ii->i_cno;
  }
  
  static int nilfs_iget_set(struct inode *inode, void *opaque)
  {
  	struct nilfs_iget_args *args = opaque;
  
  	inode->i_ino = args->ino;
  	if (args->for_gc) {
  		NILFS_I(inode)->i_state = 1 << NILFS_I_GCINODE;
  		NILFS_I(inode)->i_cno = args->cno;

  		NILFS_I(inode)->i_root = NULL;
  	} else {
  		if (args->root && args->ino == NILFS_ROOT_INO)
  			nilfs_get_root(args->root);
  		NILFS_I(inode)->i_root = args->root;

  	}
  	return 0;
  }

  struct inode *nilfs_ilookup(struct super_block *sb, struct nilfs_root *root,
  			    unsigned long ino)
  {
  	struct nilfs_iget_args args = {
  		.ino = ino, .root = root, .cno = 0, .for_gc = 0
  	};
  
  	return ilookup5(sb, ino, nilfs_iget_test, &args);
  }

  struct inode *nilfs_iget_locked(struct super_block *sb, struct nilfs_root *root,
  				unsigned long ino)

  {

  	struct nilfs_iget_args args = {
  		.ino = ino, .root = root, .cno = 0, .for_gc = 0
  	};

  
  	return iget5_locked(sb, ino, nilfs_iget_test, nilfs_iget_set, &args);
  }
  
  struct inode *nilfs_iget(struct super_block *sb, struct nilfs_root *root,
  			 unsigned long ino)
  {

  	struct inode *inode;
  	int err;

  	inode = nilfs_iget_locked(sb, root, ino);

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

  	err = __nilfs_read_inode(sb, root, ino, inode);

  	if (unlikely(err)) {
  		iget_failed(inode);
  		return ERR_PTR(err);
  	}
  	unlock_new_inode(inode);
  	return inode;
  }

  struct inode *nilfs_iget_for_gc(struct super_block *sb, unsigned long ino,
  				__u64 cno)
  {

  	struct nilfs_iget_args args = {
  		.ino = ino, .root = NULL, .cno = cno, .for_gc = 1
  	};

  	struct inode *inode;
  	int err;
  
  	inode = iget5_locked(sb, ino, nilfs_iget_test, nilfs_iget_set, &args);
  	if (unlikely(!inode))
  		return ERR_PTR(-ENOMEM);
  	if (!(inode->i_state & I_NEW))
  		return inode;
  
  	err = nilfs_init_gcinode(inode);
  	if (unlikely(err)) {
  		iget_failed(inode);
  		return ERR_PTR(err);
  	}
  	unlock_new_inode(inode);
  	return inode;
  }

  void nilfs_write_inode_common(struct inode *inode,
  			      struct nilfs_inode *raw_inode, int has_bmap)
  {
  	struct nilfs_inode_info *ii = NILFS_I(inode);
  
  	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
  	raw_inode->i_uid = cpu_to_le32(inode->i_uid);
  	raw_inode->i_gid = cpu_to_le32(inode->i_gid);
  	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
  	raw_inode->i_size = cpu_to_le64(inode->i_size);
  	raw_inode->i_ctime = cpu_to_le64(inode->i_ctime.tv_sec);
  	raw_inode->i_mtime = cpu_to_le64(inode->i_mtime.tv_sec);

  	raw_inode->i_ctime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);
  	raw_inode->i_mtime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);

  	raw_inode->i_blocks = cpu_to_le64(inode->i_blocks);

  	raw_inode->i_flags = cpu_to_le32(ii->i_flags);
  	raw_inode->i_generation = cpu_to_le32(inode->i_generation);

  	if (NILFS_ROOT_METADATA_FILE(inode->i_ino)) {
  		struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
  
  		/* zero-fill unused portion in the case of super root block */
  		raw_inode->i_xattr = 0;
  		raw_inode->i_pad = 0;
  		memset((void *)raw_inode + sizeof(*raw_inode), 0,
  		       nilfs->ns_inode_size - sizeof(*raw_inode));
  	}

  	if (has_bmap)
  		nilfs_bmap_write(ii->i_bmap, raw_inode);
  	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
  		raw_inode->i_device_code =

  			cpu_to_le64(huge_encode_dev(inode->i_rdev));

  	/* When extending inode, nilfs->ns_inode_size should be checked
  	   for substitutions of appended fields */
  }
  
  void nilfs_update_inode(struct inode *inode, struct buffer_head *ibh)
  {
  	ino_t ino = inode->i_ino;
  	struct nilfs_inode_info *ii = NILFS_I(inode);

  	struct inode *ifile = ii->i_root->ifile;

  	struct nilfs_inode *raw_inode;

  	raw_inode = nilfs_ifile_map_inode(ifile, ino, ibh);

  	if (test_and_clear_bit(NILFS_I_NEW, &ii->i_state))

  		memset(raw_inode, 0, NILFS_MDT(ifile)->mi_entry_size);

  	set_bit(NILFS_I_INODE_DIRTY, &ii->i_state);
  
  	nilfs_write_inode_common(inode, raw_inode, 0);
  		/* XXX: call with has_bmap = 0 is a workaround to avoid
  		   deadlock of bmap. This delays update of i_bmap to just
  		   before writing */

  	nilfs_ifile_unmap_inode(ifile, ino, ibh);

  }
  
  #define NILFS_MAX_TRUNCATE_BLOCKS	16384  /* 64MB for 4KB block */
  
  static void nilfs_truncate_bmap(struct nilfs_inode_info *ii,
  				unsigned long from)
  {
  	unsigned long b;
  	int ret;
  
  	if (!test_bit(NILFS_I_BMAP, &ii->i_state))
  		return;

  repeat:

  	ret = nilfs_bmap_last_key(ii->i_bmap, &b);
  	if (ret == -ENOENT)
  		return;
  	else if (ret < 0)
  		goto failed;
  
  	if (b < from)
  		return;
  
  	b -= min_t(unsigned long, NILFS_MAX_TRUNCATE_BLOCKS, b - from);
  	ret = nilfs_bmap_truncate(ii->i_bmap, b);
  	nilfs_relax_pressure_in_lock(ii->vfs_inode.i_sb);
  	if (!ret || (ret == -ENOMEM &&
  		     nilfs_bmap_truncate(ii->i_bmap, b) == 0))
  		goto repeat;

  failed:
  	nilfs_warning(ii->vfs_inode.i_sb, __func__,
  		      "failed to truncate bmap (ino=%lu, err=%d)",
  		      ii->vfs_inode.i_ino, ret);

  }
  
  void nilfs_truncate(struct inode *inode)
  {
  	unsigned long blkoff;
  	unsigned int blocksize;
  	struct nilfs_transaction_info ti;
  	struct super_block *sb = inode->i_sb;
  	struct nilfs_inode_info *ii = NILFS_I(inode);

  
  	if (!test_bit(NILFS_I_BMAP, &ii->i_state))
  		return;
  	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
  		return;
  
  	blocksize = sb->s_blocksize;
  	blkoff = (inode->i_size + blocksize - 1) >> sb->s_blocksize_bits;

  	nilfs_transaction_begin(sb, &ti, 0); /* never fails */

  
  	block_truncate_page(inode->i_mapping, inode->i_size, nilfs_get_block);
  
  	nilfs_truncate_bmap(ii, blkoff);
  
  	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  	if (IS_SYNC(inode))
  		nilfs_set_transaction_flag(NILFS_TI_SYNC);

  	nilfs_mark_inode_dirty(inode);

  	nilfs_set_file_dirty(inode, 0);

  	nilfs_transaction_commit(sb);

  	/* May construct a logical segment and may fail in sync mode.
  	   But truncate has no return value. */
  }

  static void nilfs_clear_inode(struct inode *inode)
  {
  	struct nilfs_inode_info *ii = NILFS_I(inode);

  	struct nilfs_mdt_info *mdi = NILFS_MDT(inode);

  
  	/*
  	 * Free resources allocated in nilfs_read_inode(), here.
  	 */
  	BUG_ON(!list_empty(&ii->i_dirty));
  	brelse(ii->i_bh);
  	ii->i_bh = NULL;

  	if (mdi && mdi->mi_palloc_cache)
  		nilfs_palloc_destroy_cache(inode);

  	if (test_bit(NILFS_I_BMAP, &ii->i_state))
  		nilfs_bmap_clear(ii->i_bmap);
  
  	nilfs_btnode_cache_clear(&ii->i_btnode_cache);

  
  	if (ii->i_root && inode->i_ino == NILFS_ROOT_INO)
  		nilfs_put_root(ii->i_root);

  }
  
  void nilfs_evict_inode(struct inode *inode)

  {
  	struct nilfs_transaction_info ti;
  	struct super_block *sb = inode->i_sb;
  	struct nilfs_inode_info *ii = NILFS_I(inode);

  	int ret;

  	if (inode->i_nlink || !ii->i_root || unlikely(is_bad_inode(inode))) {

  		if (inode->i_data.nrpages)
  			truncate_inode_pages(&inode->i_data, 0);

  		end_writeback(inode);
  		nilfs_clear_inode(inode);

  		return;
  	}

  	nilfs_transaction_begin(sb, &ti, 0); /* never fails */

  	if (inode->i_data.nrpages)
  		truncate_inode_pages(&inode->i_data, 0);

  	/* TODO: some of the following operations may fail.  */

  	nilfs_truncate_bmap(ii, 0);

  	nilfs_mark_inode_dirty(inode);

  	end_writeback(inode);

  	ret = nilfs_ifile_delete_inode(ii->i_root->ifile, inode->i_ino);
  	if (!ret)
  		atomic_dec(&ii->i_root->inodes_count);

  	nilfs_clear_inode(inode);

  	if (IS_SYNC(inode))
  		nilfs_set_transaction_flag(NILFS_TI_SYNC);

  	nilfs_transaction_commit(sb);

  	/* May construct a logical segment and may fail in sync mode.
  	   But delete_inode has no return value. */
  }
  
  int nilfs_setattr(struct dentry *dentry, struct iattr *iattr)
  {
  	struct nilfs_transaction_info ti;
  	struct inode *inode = dentry->d_inode;
  	struct super_block *sb = inode->i_sb;

  	int err;

  
  	err = inode_change_ok(inode, iattr);
  	if (err)
  		return err;
  
  	err = nilfs_transaction_begin(sb, &ti, 0);
  	if (unlikely(err))
  		return err;

  
  	if ((iattr->ia_valid & ATTR_SIZE) &&
  	    iattr->ia_size != i_size_read(inode)) {

  		inode_dio_wait(inode);

  		err = vmtruncate(inode, iattr->ia_size);
  		if (unlikely(err))
  			goto out_err;
  	}
  
  	setattr_copy(inode, iattr);
  	mark_inode_dirty(inode);
  
  	if (iattr->ia_valid & ATTR_MODE) {

  		err = nilfs_acl_chmod(inode);

  		if (unlikely(err))
  			goto out_err;
  	}
  
  	return nilfs_transaction_commit(sb);

  out_err:
  	nilfs_transaction_abort(sb);

  	return err;

  }

  int nilfs_permission(struct inode *inode, int mask)

  {

  	struct nilfs_root *root = NILFS_I(inode)->i_root;

  	if ((mask & MAY_WRITE) && root &&
  	    root->cno != NILFS_CPTREE_CURRENT_CNO)
  		return -EROFS; /* snapshot is not writable */

  	return generic_permission(inode, mask);

  }

  int nilfs_load_inode_block(struct inode *inode, struct buffer_head **pbh)

  {

  	struct the_nilfs *nilfs = inode->i_sb->s_fs_info;

  	struct nilfs_inode_info *ii = NILFS_I(inode);
  	int err;

  	spin_lock(&nilfs->ns_inode_lock);

  	if (ii->i_bh == NULL) {

  		spin_unlock(&nilfs->ns_inode_lock);

  		err = nilfs_ifile_get_inode_block(ii->i_root->ifile,
  						  inode->i_ino, pbh);

  		if (unlikely(err))
  			return err;

  		spin_lock(&nilfs->ns_inode_lock);

  		if (ii->i_bh == NULL)
  			ii->i_bh = *pbh;
  		else {
  			brelse(*pbh);
  			*pbh = ii->i_bh;
  		}
  	} else
  		*pbh = ii->i_bh;
  
  	get_bh(*pbh);

  	spin_unlock(&nilfs->ns_inode_lock);

  	return 0;
  }
  
  int nilfs_inode_dirty(struct inode *inode)
  {
  	struct nilfs_inode_info *ii = NILFS_I(inode);

  	struct the_nilfs *nilfs = inode->i_sb->s_fs_info;

  	int ret = 0;
  
  	if (!list_empty(&ii->i_dirty)) {

  		spin_lock(&nilfs->ns_inode_lock);

  		ret = test_bit(NILFS_I_DIRTY, &ii->i_state) ||
  			test_bit(NILFS_I_BUSY, &ii->i_state);

  		spin_unlock(&nilfs->ns_inode_lock);

  	}
  	return ret;
  }

  int nilfs_set_file_dirty(struct inode *inode, unsigned nr_dirty)

  {
  	struct nilfs_inode_info *ii = NILFS_I(inode);

  	struct the_nilfs *nilfs = inode->i_sb->s_fs_info;

  	atomic_add(nr_dirty, &nilfs->ns_ndirtyblks);

  	if (test_and_set_bit(NILFS_I_DIRTY, &ii->i_state))

  		return 0;

  	spin_lock(&nilfs->ns_inode_lock);

  	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
  	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
  		/* Because this routine may race with nilfs_dispose_list(),
  		   we have to check NILFS_I_QUEUED here, too. */
  		if (list_empty(&ii->i_dirty) && igrab(inode) == NULL) {
  			/* This will happen when somebody is freeing
  			   this inode. */

  			nilfs_warning(inode->i_sb, __func__,

  				      "cannot get inode (ino=%lu)
  ",
  				      inode->i_ino);

  			spin_unlock(&nilfs->ns_inode_lock);

  			return -EINVAL; /* NILFS_I_DIRTY may remain for
  					   freeing inode */
  		}

  		list_move_tail(&ii->i_dirty, &nilfs->ns_dirty_files);

  		set_bit(NILFS_I_QUEUED, &ii->i_state);
  	}

  	spin_unlock(&nilfs->ns_inode_lock);

  	return 0;
  }
  
  int nilfs_mark_inode_dirty(struct inode *inode)
  {

  	struct buffer_head *ibh;
  	int err;

  	err = nilfs_load_inode_block(inode, &ibh);

  	if (unlikely(err)) {
  		nilfs_warning(inode->i_sb, __func__,
  			      "failed to reget inode block.
  ");
  		return err;
  	}

  	nilfs_update_inode(inode, ibh);

  	mark_buffer_dirty(ibh);

  	nilfs_mdt_mark_dirty(NILFS_I(inode)->i_root->ifile);

  	brelse(ibh);
  	return 0;
  }
  
  /**
   * nilfs_dirty_inode - reflect changes on given inode to an inode block.
   * @inode: inode of the file to be registered.
   *
   * nilfs_dirty_inode() loads a inode block containing the specified
   * @inode and copies data from a nilfs_inode to a corresponding inode
   * entry in the inode block. This operation is excluded from the segment
   * construction. This function can be called both as a single operation
   * and as a part of indivisible file operations.
   */

  void nilfs_dirty_inode(struct inode *inode, int flags)

  {
  	struct nilfs_transaction_info ti;

  	struct nilfs_mdt_info *mdi = NILFS_MDT(inode);

  
  	if (is_bad_inode(inode)) {
  		nilfs_warning(inode->i_sb, __func__,
  			      "tried to mark bad_inode dirty. ignored.
  ");
  		dump_stack();
  		return;
  	}

  	if (mdi) {
  		nilfs_mdt_mark_dirty(inode);
  		return;
  	}

  	nilfs_transaction_begin(inode->i_sb, &ti, 0);

  	nilfs_mark_inode_dirty(inode);

  	nilfs_transaction_commit(inode->i_sb); /* never fails */

  }

  
  int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
  		 __u64 start, __u64 len)
  {

  	struct the_nilfs *nilfs = inode->i_sb->s_fs_info;

  	__u64 logical = 0, phys = 0, size = 0;
  	__u32 flags = 0;
  	loff_t isize;
  	sector_t blkoff, end_blkoff;
  	sector_t delalloc_blkoff;
  	unsigned long delalloc_blklen;
  	unsigned int blkbits = inode->i_blkbits;
  	int ret, n;
  
  	ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
  	if (ret)
  		return ret;
  
  	mutex_lock(&inode->i_mutex);
  
  	isize = i_size_read(inode);
  
  	blkoff = start >> blkbits;
  	end_blkoff = (start + len - 1) >> blkbits;
  
  	delalloc_blklen = nilfs_find_uncommitted_extent(inode, blkoff,
  							&delalloc_blkoff);
  
  	do {
  		__u64 blkphy;
  		unsigned int maxblocks;
  
  		if (delalloc_blklen && blkoff == delalloc_blkoff) {
  			if (size) {
  				/* End of the current extent */
  				ret = fiemap_fill_next_extent(
  					fieinfo, logical, phys, size, flags);
  				if (ret)
  					break;
  			}
  			if (blkoff > end_blkoff)
  				break;
  
  			flags = FIEMAP_EXTENT_MERGED | FIEMAP_EXTENT_DELALLOC;
  			logical = blkoff << blkbits;
  			phys = 0;
  			size = delalloc_blklen << blkbits;
  
  			blkoff = delalloc_blkoff + delalloc_blklen;
  			delalloc_blklen = nilfs_find_uncommitted_extent(
  				inode, blkoff, &delalloc_blkoff);
  			continue;
  		}
  
  		/*
  		 * Limit the number of blocks that we look up so as
  		 * not to get into the next delayed allocation extent.
  		 */
  		maxblocks = INT_MAX;
  		if (delalloc_blklen)
  			maxblocks = min_t(sector_t, delalloc_blkoff - blkoff,
  					  maxblocks);
  		blkphy = 0;
  
  		down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
  		n = nilfs_bmap_lookup_contig(
  			NILFS_I(inode)->i_bmap, blkoff, &blkphy, maxblocks);
  		up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
  
  		if (n < 0) {
  			int past_eof;
  
  			if (unlikely(n != -ENOENT))
  				break; /* error */
  
  			/* HOLE */
  			blkoff++;
  			past_eof = ((blkoff << blkbits) >= isize);
  
  			if (size) {
  				/* End of the current extent */
  
  				if (past_eof)
  					flags |= FIEMAP_EXTENT_LAST;
  
  				ret = fiemap_fill_next_extent(
  					fieinfo, logical, phys, size, flags);
  				if (ret)
  					break;
  				size = 0;
  			}
  			if (blkoff > end_blkoff || past_eof)
  				break;
  		} else {
  			if (size) {
  				if (phys && blkphy << blkbits == phys + size) {
  					/* The current extent goes on */
  					size += n << blkbits;
  				} else {
  					/* Terminate the current extent */
  					ret = fiemap_fill_next_extent(
  						fieinfo, logical, phys, size,
  						flags);
  					if (ret || blkoff > end_blkoff)
  						break;
  
  					/* Start another extent */
  					flags = FIEMAP_EXTENT_MERGED;
  					logical = blkoff << blkbits;
  					phys = blkphy << blkbits;
  					size = n << blkbits;
  				}
  			} else {
  				/* Start a new extent */
  				flags = FIEMAP_EXTENT_MERGED;
  				logical = blkoff << blkbits;
  				phys = blkphy << blkbits;
  				size = n << blkbits;
  			}
  			blkoff += n;
  		}
  		cond_resched();
  	} while (true);
  
  	/* If ret is 1 then we just hit the end of the extent array */
  	if (ret == 1)
  		ret = 0;
  
  	mutex_unlock(&inode->i_mutex);
  	return ret;
  }