/*
   * inode.c
   *
   * PURPOSE
   *  Inode handling routines for the OSTA-UDF(tm) filesystem.
   *

   * COPYRIGHT
   *  This file is distributed under the terms of the GNU General Public
   *  License (GPL). Copies of the GPL can be obtained from:
   *    ftp://prep.ai.mit.edu/pub/gnu/GPL
   *  Each contributing author retains all rights to their own work.
   *
   *  (C) 1998 Dave Boynton
   *  (C) 1998-2004 Ben Fennema
   *  (C) 1999-2000 Stelias Computing Inc
   *
   * HISTORY
   *
   *  10/04/98 dgb  Added rudimentary directory functions
   *  10/07/98      Fully working udf_block_map! It works!
   *  11/25/98      bmap altered to better support extents

   *  12/06/98 blf  partition support in udf_iget, udf_block_map
   *                and udf_read_inode

   *  12/12/98      rewrote udf_block_map to handle next extents and descs across
   *                block boundaries (which is not actually allowed)
   *  12/20/98      added support for strategy 4096
   *  03/07/99      rewrote udf_block_map (again)
   *                New funcs, inode_bmap, udf_next_aext
   *  04/19/99      Support for writing device EA's for major/minor #
   */
  
  #include "udfdecl.h"
  #include <linux/mm.h>

  #include <linux/module.h>
  #include <linux/pagemap.h>

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

  #include <linux/crc-itu-t.h>

  #include <linux/mpage.h>

  #include <linux/uio.h>

  
  #include "udf_i.h"
  #include "udf_sb.h"
  
  MODULE_AUTHOR("Ben Fennema");
  MODULE_DESCRIPTION("Universal Disk Format Filesystem");
  MODULE_LICENSE("GPL");
  
  #define EXTENT_MERGE_SIZE 5

  static umode_t udf_convert_permissions(struct fileEntry *);

  static int udf_update_inode(struct inode *, int);

  static int udf_sync_inode(struct inode *inode);

  static int udf_alloc_i_data(struct inode *inode, size_t size);

  static sector_t inode_getblk(struct inode *, sector_t, int *, int *);

  static int8_t udf_insert_aext(struct inode *, struct extent_position,

  			      struct kernel_lb_addr, uint32_t);

  static void udf_split_extents(struct inode *, int *, int, int,

  			      struct kernel_long_ad[EXTENT_MERGE_SIZE], int *);

  static void udf_prealloc_extents(struct inode *, int, int,

  				 struct kernel_long_ad[EXTENT_MERGE_SIZE], int *);

  static void udf_merge_extents(struct inode *,

  			      struct kernel_long_ad[EXTENT_MERGE_SIZE], int *);

  static void udf_update_extents(struct inode *,

  			       struct kernel_long_ad[EXTENT_MERGE_SIZE], int, int,

  			       struct extent_position *);

  static int udf_get_block(struct inode *, sector_t, struct buffer_head *, int);

  static void __udf_clear_extent_cache(struct inode *inode)
  {
  	struct udf_inode_info *iinfo = UDF_I(inode);
  
  	if (iinfo->cached_extent.lstart != -1) {
  		brelse(iinfo->cached_extent.epos.bh);
  		iinfo->cached_extent.lstart = -1;
  	}
  }
  
  /* Invalidate extent cache */
  static void udf_clear_extent_cache(struct inode *inode)
  {
  	struct udf_inode_info *iinfo = UDF_I(inode);
  
  	spin_lock(&iinfo->i_extent_cache_lock);
  	__udf_clear_extent_cache(inode);
  	spin_unlock(&iinfo->i_extent_cache_lock);
  }
  
  /* Return contents of extent cache */
  static int udf_read_extent_cache(struct inode *inode, loff_t bcount,
  				 loff_t *lbcount, struct extent_position *pos)
  {
  	struct udf_inode_info *iinfo = UDF_I(inode);
  	int ret = 0;
  
  	spin_lock(&iinfo->i_extent_cache_lock);
  	if ((iinfo->cached_extent.lstart <= bcount) &&
  	    (iinfo->cached_extent.lstart != -1)) {
  		/* Cache hit */
  		*lbcount = iinfo->cached_extent.lstart;
  		memcpy(pos, &iinfo->cached_extent.epos,
  		       sizeof(struct extent_position));
  		if (pos->bh)
  			get_bh(pos->bh);
  		ret = 1;
  	}
  	spin_unlock(&iinfo->i_extent_cache_lock);
  	return ret;
  }
  
  /* Add extent to extent cache */
  static void udf_update_extent_cache(struct inode *inode, loff_t estart,
  				    struct extent_position *pos, int next_epos)
  {
  	struct udf_inode_info *iinfo = UDF_I(inode);
  
  	spin_lock(&iinfo->i_extent_cache_lock);
  	/* Invalidate previously cached extent */
  	__udf_clear_extent_cache(inode);
  	if (pos->bh)
  		get_bh(pos->bh);
  	memcpy(&iinfo->cached_extent.epos, pos,
  	       sizeof(struct extent_position));
  	iinfo->cached_extent.lstart = estart;
  	if (next_epos)
  		switch (iinfo->i_alloc_type) {
  		case ICBTAG_FLAG_AD_SHORT:
  			iinfo->cached_extent.epos.offset -=
  			sizeof(struct short_ad);
  			break;
  		case ICBTAG_FLAG_AD_LONG:
  			iinfo->cached_extent.epos.offset -=
  			sizeof(struct long_ad);
  		}
  	spin_unlock(&iinfo->i_extent_cache_lock);
  }

  void udf_evict_inode(struct inode *inode)

  {

  	struct udf_inode_info *iinfo = UDF_I(inode);

  	int want_delete = 0;

  	if (!inode->i_nlink && !is_bad_inode(inode)) {
  		want_delete = 1;

  		udf_setsize(inode, 0);

  		udf_update_inode(inode, IS_SYNC(inode));

  	}
  	truncate_inode_pages_final(&inode->i_data);

  	invalidate_inode_buffers(inode);

  	clear_inode(inode);

  	if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB &&
  	    inode->i_size != iinfo->i_lenExtents) {

  		udf_warn(inode->i_sb, "Inode %lu (mode %o) has inode size %llu different from extent length %llu. Filesystem need not be standards compliant.
  ",
  			 inode->i_ino, inode->i_mode,
  			 (unsigned long long)inode->i_size,
  			 (unsigned long long)iinfo->i_lenExtents);

  	}

  	kfree(iinfo->i_ext.i_data);
  	iinfo->i_ext.i_data = NULL;

  	udf_clear_extent_cache(inode);

  	if (want_delete) {

  		udf_free_inode(inode);

  	}

  }

  static void udf_write_failed(struct address_space *mapping, loff_t to)
  {
  	struct inode *inode = mapping->host;
  	struct udf_inode_info *iinfo = UDF_I(inode);
  	loff_t isize = inode->i_size;
  
  	if (to > isize) {

  		truncate_pagecache(inode, isize);

  		if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
  			down_write(&iinfo->i_data_sem);

  			udf_clear_extent_cache(inode);

  			udf_truncate_extents(inode);
  			up_write(&iinfo->i_data_sem);
  		}
  	}
  }

  static int udf_writepage(struct page *page, struct writeback_control *wbc)
  {
  	return block_write_full_page(page, udf_get_block, wbc);
  }

  static int udf_writepages(struct address_space *mapping,
  			struct writeback_control *wbc)
  {
  	return mpage_writepages(mapping, wbc, udf_get_block);
  }

  static int udf_readpage(struct file *file, struct page *page)
  {

  	return mpage_readpage(page, udf_get_block);
  }
  
  static int udf_readpages(struct file *file, struct address_space *mapping,
  			struct list_head *pages, unsigned nr_pages)
  {
  	return mpage_readpages(mapping, pages, nr_pages, udf_get_block);

  }

  static int udf_write_begin(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned flags,
  			struct page **pagep, void **fsdata)

  {

  	int ret;
  
  	ret = block_write_begin(mapping, pos, len, flags, pagep, udf_get_block);

  	if (unlikely(ret))
  		udf_write_failed(mapping, pos + len);
  	return ret;
  }

  static ssize_t udf_direct_IO(struct kiocb *iocb, struct iov_iter *iter)

  {
  	struct file *file = iocb->ki_filp;
  	struct address_space *mapping = file->f_mapping;
  	struct inode *inode = mapping->host;

  	size_t count = iov_iter_count(iter);

  	ssize_t ret;

  	ret = blockdev_direct_IO(iocb, inode, iter, udf_get_block);

  	if (unlikely(ret < 0 && iov_iter_rw(iter) == WRITE))

  		udf_write_failed(mapping, iocb->ki_pos + count);

  	return ret;

  }
  
  static sector_t udf_bmap(struct address_space *mapping, sector_t block)
  {

  	return generic_block_bmap(mapping, block, udf_get_block);

  }

  const struct address_space_operations udf_aops = {

  	.readpage	= udf_readpage,

  	.readpages	= udf_readpages,

  	.writepage	= udf_writepage,

  	.writepages	= udf_writepages,

  	.write_begin	= udf_write_begin,
  	.write_end	= generic_write_end,
  	.direct_IO	= udf_direct_IO,

  	.bmap		= udf_bmap,

  };

  /*
   * Expand file stored in ICB to a normal one-block-file
   *
   * This function requires i_data_sem for writing and releases it.
   * This function requires i_mutex held
   */

  int udf_expand_file_adinicb(struct inode *inode)

  {
  	struct page *page;
  	char *kaddr;

  	struct udf_inode_info *iinfo = UDF_I(inode);

  	int err;

  	struct writeback_control udf_wbc = {
  		.sync_mode = WB_SYNC_NONE,
  		.nr_to_write = 1,
  	};

  	WARN_ON_ONCE(!inode_is_locked(inode));

  	if (!iinfo->i_lenAlloc) {

  		if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_SHORT_AD))

  			iinfo->i_alloc_type = ICBTAG_FLAG_AD_SHORT;

  		else

  			iinfo->i_alloc_type = ICBTAG_FLAG_AD_LONG;

  		/* from now on we have normal address_space methods */
  		inode->i_data.a_ops = &udf_aops;

  		up_write(&iinfo->i_data_sem);

  		mark_inode_dirty(inode);

  		return 0;

  	}

  	/*
  	 * Release i_data_sem so that we can lock a page - page lock ranks
  	 * above i_data_sem. i_mutex still protects us against file changes.
  	 */
  	up_write(&iinfo->i_data_sem);

  	page = find_or_create_page(inode->i_mapping, 0, GFP_NOFS);
  	if (!page)
  		return -ENOMEM;

  	if (!PageUptodate(page)) {

  		kaddr = kmap(page);

  		memset(kaddr + iinfo->i_lenAlloc, 0x00,

  		       PAGE_SIZE - iinfo->i_lenAlloc);

  		memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr,
  			iinfo->i_lenAlloc);

  		flush_dcache_page(page);
  		SetPageUptodate(page);
  		kunmap(page);
  	}

  	down_write(&iinfo->i_data_sem);

  	memset(iinfo->i_ext.i_data + iinfo->i_lenEAttr, 0x00,
  	       iinfo->i_lenAlloc);
  	iinfo->i_lenAlloc = 0;

  	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_SHORT_AD))

  		iinfo->i_alloc_type = ICBTAG_FLAG_AD_SHORT;

  	else

  		iinfo->i_alloc_type = ICBTAG_FLAG_AD_LONG;

  	/* from now on we have normal address_space methods */
  	inode->i_data.a_ops = &udf_aops;

  	up_write(&iinfo->i_data_sem);

  	err = inode->i_data.a_ops->writepage(page, &udf_wbc);
  	if (err) {
  		/* Restore everything back so that we don't lose data... */
  		lock_page(page);
  		kaddr = kmap(page);

  		down_write(&iinfo->i_data_sem);

  		memcpy(iinfo->i_ext.i_data + iinfo->i_lenEAttr, kaddr,
  		       inode->i_size);
  		kunmap(page);
  		unlock_page(page);
  		iinfo->i_alloc_type = ICBTAG_FLAG_AD_IN_ICB;
  		inode->i_data.a_ops = &udf_adinicb_aops;

  		up_write(&iinfo->i_data_sem);

  	}

  	put_page(page);

  	mark_inode_dirty(inode);

  
  	return err;

  }

  struct buffer_head *udf_expand_dir_adinicb(struct inode *inode, int *block,
  					   int *err)

  {
  	int newblock;

  	struct buffer_head *dbh = NULL;

  	struct kernel_lb_addr eloc;

  	uint8_t alloctype;

  	struct extent_position epos;

  
  	struct udf_fileident_bh sfibh, dfibh;

  	loff_t f_pos = udf_ext0_offset(inode);
  	int size = udf_ext0_offset(inode) + inode->i_size;

  	struct fileIdentDesc cfi, *sfi, *dfi;

  	struct udf_inode_info *iinfo = UDF_I(inode);

  
  	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_SHORT_AD))
  		alloctype = ICBTAG_FLAG_AD_SHORT;
  	else
  		alloctype = ICBTAG_FLAG_AD_LONG;

  	if (!inode->i_size) {

  		iinfo->i_alloc_type = alloctype;

  		mark_inode_dirty(inode);
  		return NULL;
  	}
  
  	/* alloc block, and copy data to it */
  	*block = udf_new_block(inode->i_sb, inode,

  			       iinfo->i_location.partitionReferenceNum,
  			       iinfo->i_location.logicalBlockNum, err);

  	if (!(*block))
  		return NULL;
  	newblock = udf_get_pblock(inode->i_sb, *block,

  				  iinfo->i_location.partitionReferenceNum,

  				0);

  	if (!newblock)
  		return NULL;
  	dbh = udf_tgetblk(inode->i_sb, newblock);
  	if (!dbh)
  		return NULL;
  	lock_buffer(dbh);
  	memset(dbh->b_data, 0x00, inode->i_sb->s_blocksize);
  	set_buffer_uptodate(dbh);
  	unlock_buffer(dbh);
  	mark_buffer_dirty_inode(dbh, inode);

  	sfibh.soffset = sfibh.eoffset =

  			f_pos & (inode->i_sb->s_blocksize - 1);

  	sfibh.sbh = sfibh.ebh = NULL;

  	dfibh.soffset = dfibh.eoffset = 0;
  	dfibh.sbh = dfibh.ebh = dbh;

  	while (f_pos < size) {

  		iinfo->i_alloc_type = ICBTAG_FLAG_AD_IN_ICB;

  		sfi = udf_fileident_read(inode, &f_pos, &sfibh, &cfi, NULL,
  					 NULL, NULL, NULL);

  		if (!sfi) {

  			brelse(dbh);

  			return NULL;
  		}

  		iinfo->i_alloc_type = alloctype;

  		sfi->descTag.tagLocation = cpu_to_le32(*block);
  		dfibh.soffset = dfibh.eoffset;
  		dfibh.eoffset += (sfibh.eoffset - sfibh.soffset);
  		dfi = (struct fileIdentDesc *)(dbh->b_data + dfibh.soffset);
  		if (udf_write_fi(inode, sfi, dfi, &dfibh, sfi->impUse,

  				 sfi->fileIdent +
  					le16_to_cpu(sfi->lengthOfImpUse))) {

  			iinfo->i_alloc_type = ICBTAG_FLAG_AD_IN_ICB;

  			brelse(dbh);

  			return NULL;
  		}
  	}
  	mark_buffer_dirty_inode(dbh, inode);

  	memset(iinfo->i_ext.i_data + iinfo->i_lenEAttr, 0,
  		iinfo->i_lenAlloc);
  	iinfo->i_lenAlloc = 0;

  	eloc.logicalBlockNum = *block;

  	eloc.partitionReferenceNum =

  				iinfo->i_location.partitionReferenceNum;

  	iinfo->i_lenExtents = inode->i_size;

  	epos.bh = NULL;

  	epos.block = iinfo->i_location;

  	epos.offset = udf_file_entry_alloc_offset(inode);

  	udf_add_aext(inode, &epos, &eloc, inode->i_size, 0);

  	/* UniqueID stuff */

  	brelse(epos.bh);

  	mark_inode_dirty(inode);
  	return dbh;
  }

  static int udf_get_block(struct inode *inode, sector_t block,
  			 struct buffer_head *bh_result, int create)

  {
  	int err, new;

  	sector_t phys = 0;

  	struct udf_inode_info *iinfo;

  	if (!create) {

  		phys = udf_block_map(inode, block);
  		if (phys)
  			map_bh(bh_result, inode->i_sb, phys);
  		return 0;
  	}
  
  	err = -EIO;
  	new = 0;

  	iinfo = UDF_I(inode);

  
  	down_write(&iinfo->i_data_sem);

  	if (block == iinfo->i_next_alloc_block + 1) {
  		iinfo->i_next_alloc_block++;
  		iinfo->i_next_alloc_goal++;

  	}

  	udf_clear_extent_cache(inode);

  	phys = inode_getblk(inode, block, &err, &new);
  	if (!phys)

  		goto abort;

  
  	if (new)
  		set_buffer_new(bh_result);
  	map_bh(bh_result, inode->i_sb, phys);

  
  abort:

  	up_write(&iinfo->i_data_sem);

  	return err;

  }

  static struct buffer_head *udf_getblk(struct inode *inode, long block,
  				      int create, int *err)

  {

  	struct buffer_head *bh;

  	struct buffer_head dummy;
  
  	dummy.b_state = 0;
  	dummy.b_blocknr = -1000;
  	*err = udf_get_block(inode, block, &dummy, create);

  	if (!*err && buffer_mapped(&dummy)) {

  		bh = sb_getblk(inode->i_sb, dummy.b_blocknr);

  		if (buffer_new(&dummy)) {

  			lock_buffer(bh);
  			memset(bh->b_data, 0x00, inode->i_sb->s_blocksize);
  			set_buffer_uptodate(bh);
  			unlock_buffer(bh);
  			mark_buffer_dirty_inode(bh, inode);
  		}
  		return bh;
  	}

  	return NULL;
  }

  /* Extend the file by 'blocks' blocks, return the number of extents added */

  static int udf_do_extend_file(struct inode *inode,
  			      struct extent_position *last_pos,
  			      struct kernel_long_ad *last_ext,
  			      sector_t blocks)

  {
  	sector_t add;
  	int count = 0, fake = !(last_ext->extLength & UDF_EXTENT_LENGTH_MASK);
  	struct super_block *sb = inode->i_sb;

  	struct kernel_lb_addr prealloc_loc = {};

  	int prealloc_len = 0;

  	struct udf_inode_info *iinfo;

  	int err;

  
  	/* The previous extent is fake and we should not extend by anything
  	 * - there's nothing to do... */
  	if (!blocks && fake)
  		return 0;

  	iinfo = UDF_I(inode);

  	/* Round the last extent up to a multiple of block size */
  	if (last_ext->extLength & (sb->s_blocksize - 1)) {
  		last_ext->extLength =

  			(last_ext->extLength & UDF_EXTENT_FLAG_MASK) |
  			(((last_ext->extLength & UDF_EXTENT_LENGTH_MASK) +
  			  sb->s_blocksize - 1) & ~(sb->s_blocksize - 1));

  		iinfo->i_lenExtents =
  			(iinfo->i_lenExtents + sb->s_blocksize - 1) &

  			~(sb->s_blocksize - 1);

  	}

  	/* Last extent are just preallocated blocks? */

  	if ((last_ext->extLength & UDF_EXTENT_FLAG_MASK) ==
  						EXT_NOT_RECORDED_ALLOCATED) {

  		/* Save the extent so that we can reattach it to the end */
  		prealloc_loc = last_ext->extLocation;
  		prealloc_len = last_ext->extLength;
  		/* Mark the extent as a hole */
  		last_ext->extLength = EXT_NOT_RECORDED_NOT_ALLOCATED |

  			(last_ext->extLength & UDF_EXTENT_LENGTH_MASK);

  		last_ext->extLocation.logicalBlockNum = 0;

  		last_ext->extLocation.partitionReferenceNum = 0;

  	}

  	/* Can we merge with the previous extent? */

  	if ((last_ext->extLength & UDF_EXTENT_FLAG_MASK) ==
  					EXT_NOT_RECORDED_NOT_ALLOCATED) {
  		add = ((1 << 30) - sb->s_blocksize -
  			(last_ext->extLength & UDF_EXTENT_LENGTH_MASK)) >>
  			sb->s_blocksize_bits;

  		if (add > blocks)
  			add = blocks;
  		blocks -= add;
  		last_ext->extLength += add << sb->s_blocksize_bits;
  	}
  
  	if (fake) {

  		udf_add_aext(inode, last_pos, &last_ext->extLocation,

  			     last_ext->extLength, 1);

  		count++;

  	} else {
  		struct kernel_lb_addr tmploc;
  		uint32_t tmplen;

  		udf_write_aext(inode, last_pos, &last_ext->extLocation,

  				last_ext->extLength, 1);

  		/*
  		 * We've rewritten the last extent but there may be empty
  		 * indirect extent after it - enter it.
  		 */
  		udf_next_aext(inode, last_pos, &tmploc, &tmplen, 0);
  	}

  	/* Managed to do everything necessary? */
  	if (!blocks)
  		goto out;
  
  	/* All further extents will be NOT_RECORDED_NOT_ALLOCATED */
  	last_ext->extLocation.logicalBlockNum = 0;

  	last_ext->extLocation.partitionReferenceNum = 0;

  	add = (1 << (30-sb->s_blocksize_bits)) - 1;

  	last_ext->extLength = EXT_NOT_RECORDED_NOT_ALLOCATED |
  				(add << sb->s_blocksize_bits);

  	/* Create enough extents to cover the whole hole */
  	while (blocks > add) {
  		blocks -= add;

  		err = udf_add_aext(inode, last_pos, &last_ext->extLocation,
  				   last_ext->extLength, 1);
  		if (err)
  			return err;

  		count++;
  	}
  	if (blocks) {
  		last_ext->extLength = EXT_NOT_RECORDED_NOT_ALLOCATED |

  			(blocks << sb->s_blocksize_bits);

  		err = udf_add_aext(inode, last_pos, &last_ext->extLocation,
  				   last_ext->extLength, 1);
  		if (err)
  			return err;

  		count++;
  	}

  
  out:

  	/* Do we have some preallocated blocks saved? */
  	if (prealloc_len) {

  		err = udf_add_aext(inode, last_pos, &prealloc_loc,
  				   prealloc_len, 1);
  		if (err)
  			return err;

  		last_ext->extLocation = prealloc_loc;
  		last_ext->extLength = prealloc_len;
  		count++;
  	}

  	/* last_pos should point to the last written extent... */

  	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)

  		last_pos->offset -= sizeof(struct short_ad);

  	else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)

  		last_pos->offset -= sizeof(struct long_ad);

  	else

  		return -EIO;

  	return count;
  }

  static int udf_extend_file(struct inode *inode, loff_t newsize)
  {
  
  	struct extent_position epos;
  	struct kernel_lb_addr eloc;
  	uint32_t elen;
  	int8_t etype;
  	struct super_block *sb = inode->i_sb;
  	sector_t first_block = newsize >> sb->s_blocksize_bits, offset;
  	int adsize;
  	struct udf_inode_info *iinfo = UDF_I(inode);
  	struct kernel_long_ad extent;
  	int err;
  
  	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
  		adsize = sizeof(struct short_ad);
  	else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
  		adsize = sizeof(struct long_ad);
  	else
  		BUG();
  
  	etype = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset);
  
  	/* File has extent covering the new size (could happen when extending
  	 * inside a block)? */
  	if (etype != -1)
  		return 0;
  	if (newsize & (sb->s_blocksize - 1))
  		offset++;
  	/* Extended file just to the boundary of the last file block? */
  	if (offset == 0)
  		return 0;
  
  	/* Truncate is extending the file by 'offset' blocks */
  	if ((!epos.bh && epos.offset == udf_file_entry_alloc_offset(inode)) ||
  	    (epos.bh && epos.offset == sizeof(struct allocExtDesc))) {
  		/* File has no extents at all or has empty last
  		 * indirect extent! Create a fake extent... */
  		extent.extLocation.logicalBlockNum = 0;
  		extent.extLocation.partitionReferenceNum = 0;
  		extent.extLength = EXT_NOT_RECORDED_NOT_ALLOCATED;
  	} else {
  		epos.offset -= adsize;
  		etype = udf_next_aext(inode, &epos, &extent.extLocation,
  				      &extent.extLength, 0);
  		extent.extLength |= etype << 30;
  	}
  	err = udf_do_extend_file(inode, &epos, &extent, offset);
  	if (err < 0)
  		goto out;
  	err = 0;
  	iinfo->i_lenExtents = newsize;
  out:
  	brelse(epos.bh);
  	return err;
  }

  static sector_t inode_getblk(struct inode *inode, sector_t block,
  			     int *err, int *new)

  {

  	struct kernel_long_ad laarr[EXTENT_MERGE_SIZE];

  	struct extent_position prev_epos, cur_epos, next_epos;

  	int count = 0, startnum = 0, endnum = 0;

  	uint32_t elen = 0, tmpelen;

  	struct kernel_lb_addr eloc, tmpeloc;

  	int c = 1;

  	loff_t lbcount = 0, b_off = 0;
  	uint32_t newblocknum, newblock;
  	sector_t offset = 0;

  	int8_t etype;

  	struct udf_inode_info *iinfo = UDF_I(inode);
  	int goal = 0, pgoal = iinfo->i_location.logicalBlockNum;

  	int lastblock = 0;

  	bool isBeyondEOF;

  	*err = 0;
  	*new = 0;

  	prev_epos.offset = udf_file_entry_alloc_offset(inode);

  	prev_epos.block = iinfo->i_location;

  	prev_epos.bh = NULL;
  	cur_epos = next_epos = prev_epos;

  	b_off = (loff_t)block << inode->i_sb->s_blocksize_bits;

  
  	/* find the extent which contains the block we are looking for.

  	   alternate between laarr[0] and laarr[1] for locations of the
  	   current extent, and the previous extent */
  	do {
  		if (prev_epos.bh != cur_epos.bh) {

  			brelse(prev_epos.bh);
  			get_bh(cur_epos.bh);

  			prev_epos.bh = cur_epos.bh;

  		}

  		if (cur_epos.bh != next_epos.bh) {

  			brelse(cur_epos.bh);
  			get_bh(next_epos.bh);

  			cur_epos.bh = next_epos.bh;

  		}
  
  		lbcount += elen;

  		prev_epos.block = cur_epos.block;
  		cur_epos.block = next_epos.block;

  		prev_epos.offset = cur_epos.offset;
  		cur_epos.offset = next_epos.offset;

  		etype = udf_next_aext(inode, &next_epos, &eloc, &elen, 1);
  		if (etype == -1)

  			break;
  
  		c = !c;
  
  		laarr[c].extLength = (etype << 30) | elen;
  		laarr[c].extLocation = eloc;
  
  		if (etype != (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
  			pgoal = eloc.logicalBlockNum +

  				((elen + inode->i_sb->s_blocksize - 1) >>
  				 inode->i_sb->s_blocksize_bits);

  		count++;

  	} while (lbcount + elen <= b_off);
  
  	b_off -= lbcount;
  	offset = b_off >> inode->i_sb->s_blocksize_bits;

  	/*
  	 * Move prev_epos and cur_epos into indirect extent if we are at
  	 * the pointer to it
  	 */
  	udf_next_aext(inode, &prev_epos, &tmpeloc, &tmpelen, 0);
  	udf_next_aext(inode, &cur_epos, &tmpeloc, &tmpelen, 0);

  
  	/* if the extent is allocated and recorded, return the block

  	   if the extent is not a multiple of the blocksize, round up */

  	if (etype == (EXT_RECORDED_ALLOCATED >> 30)) {
  		if (elen & (inode->i_sb->s_blocksize - 1)) {

  			elen = EXT_RECORDED_ALLOCATED |

  				((elen + inode->i_sb->s_blocksize - 1) &
  				 ~(inode->i_sb->s_blocksize - 1));

  			udf_write_aext(inode, &cur_epos, &eloc, elen, 1);

  		}

  		brelse(prev_epos.bh);
  		brelse(cur_epos.bh);
  		brelse(next_epos.bh);

  		newblock = udf_get_lb_pblock(inode->i_sb, &eloc, offset);

  		return newblock;

  	}

  	/* Are we beyond EOF? */

  	if (etype == -1) {

  		int ret;

  		isBeyondEOF = true;

  		if (count) {
  			if (c)
  				laarr[0] = laarr[1];
  			startnum = 1;

  		} else {

  			/* Create a fake extent when there's not one */

  			memset(&laarr[0].extLocation, 0x00,

  				sizeof(struct kernel_lb_addr));

  			laarr[0].extLength = EXT_NOT_RECORDED_NOT_ALLOCATED;

  			/* Will udf_do_extend_file() create real extent from

  			   a fake one? */

  			startnum = (offset > 0);
  		}
  		/* Create extents for the hole between EOF and offset */

  		ret = udf_do_extend_file(inode, &prev_epos, laarr, offset);
  		if (ret < 0) {

  			brelse(prev_epos.bh);
  			brelse(cur_epos.bh);
  			brelse(next_epos.bh);

  			*err = ret;

  			return 0;

  		}
  		c = 0;
  		offset = 0;
  		count += ret;
  		/* We are not covered by a preallocated extent? */

  		if ((laarr[0].extLength & UDF_EXTENT_FLAG_MASK) !=
  						EXT_NOT_RECORDED_ALLOCATED) {

  			/* Is there any real extent? - otherwise we overwrite
  			 * the fake one... */
  			if (count)
  				c = !c;
  			laarr[c].extLength = EXT_NOT_RECORDED_NOT_ALLOCATED |

  				inode->i_sb->s_blocksize;

  			memset(&laarr[c].extLocation, 0x00,

  				sizeof(struct kernel_lb_addr));

  			count++;

  		}

  		endnum = c + 1;

  		lastblock = 1;

  	} else {

  		isBeyondEOF = false;

  		endnum = startnum = ((count > 2) ? 2 : count);

  		/* if the current extent is in position 0,
  		   swap it with the previous */

  		if (!c && count != 1) {

  			laarr[2] = laarr[0];
  			laarr[0] = laarr[1];
  			laarr[1] = laarr[2];
  			c = 1;
  		}

  		/* if the current block is located in an extent,
  		   read the next extent */
  		etype = udf_next_aext(inode, &next_epos, &eloc, &elen, 0);
  		if (etype != -1) {

  			laarr[c + 1].extLength = (etype << 30) | elen;
  			laarr[c + 1].extLocation = eloc;
  			count++;
  			startnum++;
  			endnum++;

  		} else

  			lastblock = 1;
  	}

  
  	/* if the current extent is not recorded but allocated, get the

  	 * block in the extent corresponding to the requested block */

  	if ((laarr[c].extLength >> 30) == (EXT_NOT_RECORDED_ALLOCATED >> 30))

  		newblocknum = laarr[c].extLocation.logicalBlockNum + offset;

  	else { /* otherwise, allocate a new block */

  		if (iinfo->i_next_alloc_block == block)
  			goal = iinfo->i_next_alloc_goal;

  		if (!goal) {

  			if (!(goal = pgoal)) /* XXX: what was intended here? */

  				goal = iinfo->i_location.logicalBlockNum + 1;

  		}

  		newblocknum = udf_new_block(inode->i_sb, inode,

  				iinfo->i_location.partitionReferenceNum,

  				goal, err);
  		if (!newblocknum) {

  			brelse(prev_epos.bh);

  			brelse(cur_epos.bh);
  			brelse(next_epos.bh);

  			*err = -ENOSPC;

  			return 0;

  		}

  		if (isBeyondEOF)
  			iinfo->i_lenExtents += inode->i_sb->s_blocksize;

  	}

  	/* if the extent the requsted block is located in contains multiple
  	 * blocks, split the extent into at most three extents. blocks prior
  	 * to requested block, requested block, and blocks after requested
  	 * block */

  	udf_split_extents(inode, &c, offset, newblocknum, laarr, &endnum);
  
  #ifdef UDF_PREALLOCATE

  	/* We preallocate blocks only for regular files. It also makes sense
  	 * for directories but there's a problem when to drop the
  	 * preallocation. We might use some delayed work for that but I feel
  	 * it's overengineering for a filesystem like UDF. */
  	if (S_ISREG(inode->i_mode))
  		udf_prealloc_extents(inode, c, lastblock, laarr, &endnum);

  #endif
  
  	/* merge any continuous blocks in laarr */
  	udf_merge_extents(inode, laarr, &endnum);
  
  	/* write back the new extents, inserting new extents if the new number

  	 * of extents is greater than the old number, and deleting extents if
  	 * the new number of extents is less than the old number */

  	udf_update_extents(inode, laarr, startnum, endnum, &prev_epos);

  	brelse(prev_epos.bh);

  	brelse(cur_epos.bh);
  	brelse(next_epos.bh);

  	newblock = udf_get_pblock(inode->i_sb, newblocknum,

  				iinfo->i_location.partitionReferenceNum, 0);

  	if (!newblock) {
  		*err = -EIO;
  		return 0;
  	}

  	*new = 1;

  	iinfo->i_next_alloc_block = block;
  	iinfo->i_next_alloc_goal = newblocknum;

  	inode->i_ctime = current_time(inode);

  
  	if (IS_SYNC(inode))
  		udf_sync_inode(inode);
  	else
  		mark_inode_dirty(inode);

  	return newblock;

  }

  static void udf_split_extents(struct inode *inode, int *c, int offset,
  			      int newblocknum,

  			      struct kernel_long_ad laarr[EXTENT_MERGE_SIZE],

  			      int *endnum)

  {

  	unsigned long blocksize = inode->i_sb->s_blocksize;
  	unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;

  	if ((laarr[*c].extLength >> 30) == (EXT_NOT_RECORDED_ALLOCATED >> 30) ||

  	    (laarr[*c].extLength >> 30) ==
  				(EXT_NOT_RECORDED_NOT_ALLOCATED >> 30)) {

  		int curr = *c;
  		int blen = ((laarr[curr].extLength & UDF_EXTENT_LENGTH_MASK) +

  			    blocksize - 1) >> blocksize_bits;

  		int8_t etype = (laarr[curr].extLength >> 30);

  		if (blen == 1)

  			;

  		else if (!offset || blen == offset + 1) {

  			laarr[curr + 2] = laarr[curr + 1];
  			laarr[curr + 1] = laarr[curr];
  		} else {
  			laarr[curr + 3] = laarr[curr + 1];
  			laarr[curr + 2] = laarr[curr + 1] = laarr[curr];
  		}
  
  		if (offset) {
  			if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {

  				udf_free_blocks(inode->i_sb, inode,

  						&laarr[curr].extLocation,

  						0, offset);
  				laarr[curr].extLength =
  					EXT_NOT_RECORDED_NOT_ALLOCATED |
  					(offset << blocksize_bits);

  				laarr[curr].extLocation.logicalBlockNum = 0;

  				laarr[curr].extLocation.
  						partitionReferenceNum = 0;
  			} else

  				laarr[curr].extLength = (etype << 30) |

  					(offset << blocksize_bits);

  			curr++;
  			(*c)++;
  			(*endnum)++;

  		}

  		laarr[curr].extLocation.logicalBlockNum = newblocknum;
  		if (etype == (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
  			laarr[curr].extLocation.partitionReferenceNum =

  				UDF_I(inode)->i_location.partitionReferenceNum;

  		laarr[curr].extLength = EXT_RECORDED_ALLOCATED |

  			blocksize;

  		curr++;

  		if (blen != offset + 1) {

  			if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30))

  				laarr[curr].extLocation.logicalBlockNum +=
  								offset + 1;

  			laarr[curr].extLength = (etype << 30) |

  				((blen - (offset + 1)) << blocksize_bits);

  			curr++;
  			(*endnum)++;

  		}
  	}
  }
  
  static void udf_prealloc_extents(struct inode *inode, int c, int lastblock,

  				 struct kernel_long_ad laarr[EXTENT_MERGE_SIZE],

  				 int *endnum)

  {
  	int start, length = 0, currlength = 0, i;

  	if (*endnum >= (c + 1)) {

  		if (!lastblock)
  			return;
  		else
  			start = c;

  	} else {

  		if ((laarr[c + 1].extLength >> 30) ==
  					(EXT_NOT_RECORDED_ALLOCATED >> 30)) {

  			start = c + 1;

  			length = currlength =
  				(((laarr[c + 1].extLength &
  					UDF_EXTENT_LENGTH_MASK) +
  				inode->i_sb->s_blocksize - 1) >>
  				inode->i_sb->s_blocksize_bits);
  		} else

  			start = c;
  	}

  	for (i = start + 1; i <= *endnum; i++) {
  		if (i == *endnum) {

  			if (lastblock)
  				length += UDF_DEFAULT_PREALLOC_BLOCKS;

  		} else if ((laarr[i].extLength >> 30) ==
  				(EXT_NOT_RECORDED_NOT_ALLOCATED >> 30)) {
  			length += (((laarr[i].extLength &
  						UDF_EXTENT_LENGTH_MASK) +
  				    inode->i_sb->s_blocksize - 1) >>
  				    inode->i_sb->s_blocksize_bits);
  		} else

  			break;
  	}

  	if (length) {

  		int next = laarr[start].extLocation.logicalBlockNum +

  			(((laarr[start].extLength & UDF_EXTENT_LENGTH_MASK) +

  			  inode->i_sb->s_blocksize - 1) >>
  			  inode->i_sb->s_blocksize_bits);

  		int numalloc = udf_prealloc_blocks(inode->i_sb, inode,

  				laarr[start].extLocation.partitionReferenceNum,
  				next, (UDF_DEFAULT_PREALLOC_BLOCKS > length ?
  				length : UDF_DEFAULT_PREALLOC_BLOCKS) -
  				currlength);

  		if (numalloc) 	{

  			if (start == (c + 1))

  				laarr[start].extLength +=

  					(numalloc <<
  					 inode->i_sb->s_blocksize_bits);
  			else {

  				memmove(&laarr[c + 2], &laarr[c + 1],

  					sizeof(struct long_ad) * (*endnum - (c + 1)));

  				(*endnum)++;
  				laarr[c + 1].extLocation.logicalBlockNum = next;
  				laarr[c + 1].extLocation.partitionReferenceNum =

  					laarr[c].extLocation.
  							partitionReferenceNum;
  				laarr[c + 1].extLength =
  					EXT_NOT_RECORDED_ALLOCATED |
  					(numalloc <<
  					 inode->i_sb->s_blocksize_bits);

  				start = c + 1;

  			}

  			for (i = start + 1; numalloc && i < *endnum; i++) {

  				int elen = ((laarr[i].extLength &
  						UDF_EXTENT_LENGTH_MASK) +
  					    inode->i_sb->s_blocksize - 1) >>
  					    inode->i_sb->s_blocksize_bits;

  				if (elen > numalloc) {

  					laarr[i].extLength -=

  						(numalloc <<
  						 inode->i_sb->s_blocksize_bits);

  					numalloc = 0;

  				} else {

  					numalloc -= elen;

  					if (*endnum > (i + 1))

  						memmove(&laarr[i],
  							&laarr[i + 1],

  							sizeof(struct long_ad) *

  							(*endnum - (i + 1)));

  					i--;
  					(*endnum)--;

  				}
  			}

  			UDF_I(inode)->i_lenExtents +=

  				numalloc << inode->i_sb->s_blocksize_bits;

  		}
  	}
  }
  
  static void udf_merge_extents(struct inode *inode,

  			      struct kernel_long_ad laarr[EXTENT_MERGE_SIZE],

  			      int *endnum)

  {
  	int i;

  	unsigned long blocksize = inode->i_sb->s_blocksize;
  	unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;

  	for (i = 0; i < (*endnum - 1); i++) {

  		struct kernel_long_ad *li /*l[i]*/ = &laarr[i];
  		struct kernel_long_ad *lip1 /*l[i plus 1]*/ = &laarr[i + 1];

  
  		if (((li->extLength >> 30) == (lip1->extLength >> 30)) &&
  			(((li->extLength >> 30) ==
  				(EXT_NOT_RECORDED_NOT_ALLOCATED >> 30)) ||
  			((lip1->extLocation.logicalBlockNum -
  			  li->extLocation.logicalBlockNum) ==
  			(((li->extLength & UDF_EXTENT_LENGTH_MASK) +
  			blocksize - 1) >> blocksize_bits)))) {
  
  			if (((li->extLength & UDF_EXTENT_LENGTH_MASK) +
  				(lip1->extLength & UDF_EXTENT_LENGTH_MASK) +
  				blocksize - 1) & ~UDF_EXTENT_LENGTH_MASK) {
  				lip1->extLength = (lip1->extLength -
  						  (li->extLength &
  						   UDF_EXTENT_LENGTH_MASK) +
  						   UDF_EXTENT_LENGTH_MASK) &
  							~(blocksize - 1);
  				li->extLength = (li->extLength &
  						 UDF_EXTENT_FLAG_MASK) +
  						(UDF_EXTENT_LENGTH_MASK + 1) -
  						blocksize;
  				lip1->extLocation.logicalBlockNum =
  					li->extLocation.logicalBlockNum +
  					((li->extLength &
  						UDF_EXTENT_LENGTH_MASK) >>
  						blocksize_bits);
  			} else {
  				li->extLength = lip1->extLength +
  					(((li->extLength &
  						UDF_EXTENT_LENGTH_MASK) +
  					 blocksize - 1) & ~(blocksize - 1));
  				if (*endnum > (i + 2))
  					memmove(&laarr[i + 1], &laarr[i + 2],

  						sizeof(struct long_ad) *

  						(*endnum - (i + 2)));
  				i--;
  				(*endnum)--;

  			}

  		} else if (((li->extLength >> 30) ==
  				(EXT_NOT_RECORDED_ALLOCATED >> 30)) &&
  			   ((lip1->extLength >> 30) ==
  				(EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))) {

  			udf_free_blocks(inode->i_sb, inode, &li->extLocation, 0,

  					((li->extLength &
  					  UDF_EXTENT_LENGTH_MASK) +
  					 blocksize - 1) >> blocksize_bits);
  			li->extLocation.logicalBlockNum = 0;
  			li->extLocation.partitionReferenceNum = 0;
  
  			if (((li->extLength & UDF_EXTENT_LENGTH_MASK) +
  			     (lip1->extLength & UDF_EXTENT_LENGTH_MASK) +
  			     blocksize - 1) & ~UDF_EXTENT_LENGTH_MASK) {
  				lip1->extLength = (lip1->extLength -
  						   (li->extLength &
  						   UDF_EXTENT_LENGTH_MASK) +
  						   UDF_EXTENT_LENGTH_MASK) &
  						   ~(blocksize - 1);
  				li->extLength = (li->extLength &
  						 UDF_EXTENT_FLAG_MASK) +
  						(UDF_EXTENT_LENGTH_MASK + 1) -
  						blocksize;

  			} else {

  				li->extLength = lip1->extLength +
  					(((li->extLength &
  						UDF_EXTENT_LENGTH_MASK) +
  					  blocksize - 1) & ~(blocksize - 1));

  				if (*endnum > (i + 2))
  					memmove(&laarr[i + 1], &laarr[i + 2],

  						sizeof(struct long_ad) *

  						(*endnum - (i + 2)));

  				i--;
  				(*endnum)--;

  			}

  		} else if ((li->extLength >> 30) ==
  					(EXT_NOT_RECORDED_ALLOCATED >> 30)) {
  			udf_free_blocks(inode->i_sb, inode,

  					&li->extLocation, 0,

  					((li->extLength &
  						UDF_EXTENT_LENGTH_MASK) +
  					 blocksize - 1) >> blocksize_bits);
  			li->extLocation.logicalBlockNum = 0;
  			li->extLocation.partitionReferenceNum = 0;
  			li->extLength = (li->extLength &
  						UDF_EXTENT_LENGTH_MASK) |
  						EXT_NOT_RECORDED_NOT_ALLOCATED;

  		}
  	}
  }
  
  static void udf_update_extents(struct inode *inode,

  			       struct kernel_long_ad laarr[EXTENT_MERGE_SIZE],

  			       int startnum, int endnum,
  			       struct extent_position *epos)

  {
  	int start = 0, i;

  	struct kernel_lb_addr tmploc;

  	uint32_t tmplen;

  	if (startnum > endnum) {
  		for (i = 0; i < (startnum - endnum); i++)

  			udf_delete_aext(inode, *epos, laarr[i].extLocation,

  					laarr[i].extLength);
  	} else if (startnum < endnum) {
  		for (i = 0; i < (endnum - startnum); i++) {

  			udf_insert_aext(inode, *epos, laarr[i].extLocation,

  					laarr[i].extLength);

  			udf_next_aext(inode, epos, &laarr[i].extLocation,

  				      &laarr[i].extLength, 1);
  			start++;

  		}
  	}

  	for (i = start; i < endnum; i++) {

  		udf_next_aext(inode, epos, &tmploc, &tmplen, 0);

  		udf_write_aext(inode, epos, &laarr[i].extLocation,

  			       laarr[i].extLength, 1);

  	}
  }

  struct buffer_head *udf_bread(struct inode *inode, int block,
  			      int create, int *err)

  {

  	struct buffer_head *bh = NULL;

  
  	bh = udf_getblk(inode, block, create, err);
  	if (!bh)
  		return NULL;
  
  	if (buffer_uptodate(bh))
  		return bh;

  	ll_rw_block(REQ_OP_READ, 0, 1, &bh);

  	wait_on_buffer(bh);
  	if (buffer_uptodate(bh))
  		return bh;

  	brelse(bh);
  	*err = -EIO;
  	return NULL;
  }

  int udf_setsize(struct inode *inode, loff_t newsize)

  {

  	int err;

  	struct udf_inode_info *iinfo;

  	int bsize = 1 << inode->i_blkbits;

  
  	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||

  	      S_ISLNK(inode->i_mode)))

  		return -EINVAL;

  	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))

  		return -EPERM;

  	iinfo = UDF_I(inode);

  	if (newsize > inode->i_size) {

  		down_write(&iinfo->i_data_sem);

  		if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
  			if (bsize <
  			    (udf_file_entry_alloc_offset(inode) + newsize)) {
  				err = udf_expand_file_adinicb(inode);

  				if (err)

  					return err;

  				down_write(&iinfo->i_data_sem);

  			} else {

  				iinfo->i_lenAlloc = newsize;

  				goto set_size;
  			}

  		}
  		err = udf_extend_file(inode, newsize);
  		if (err) {
  			up_write(&iinfo->i_data_sem);
  			return err;

  		}

  set_size:

  		truncate_setsize(inode, newsize);

  		up_write(&iinfo->i_data_sem);

  	} else {

  		if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
  			down_write(&iinfo->i_data_sem);

  			udf_clear_extent_cache(inode);

  			memset(iinfo->i_ext.i_data + iinfo->i_lenEAttr + newsize,
  			       0x00, bsize - newsize -
  			       udf_file_entry_alloc_offset(inode));
  			iinfo->i_lenAlloc = newsize;
  			truncate_setsize(inode, newsize);
  			up_write(&iinfo->i_data_sem);
  			goto update_time;
  		}
  		err = block_truncate_page(inode->i_mapping, newsize,
  					  udf_get_block);
  		if (err)
  			return err;

  		down_write(&iinfo->i_data_sem);

  		udf_clear_extent_cache(inode);

  		truncate_setsize(inode, newsize);

  		udf_truncate_extents(inode);

  		up_write(&iinfo->i_data_sem);

  	}

  update_time:

  	inode->i_mtime = inode->i_ctime = current_time(inode);

  	if (IS_SYNC(inode))

  		udf_sync_inode(inode);

  	else
  		mark_inode_dirty(inode);

  	return 0;

  }

  /*
   * Maximum length of linked list formed by ICB hierarchy. The chosen number is
   * arbitrary - just that we hopefully don't limit any real use of rewritten
   * inode on write-once media but avoid looping for too long on corrupted media.
   */
  #define UDF_MAX_ICB_NESTING 1024

  static int udf_read_inode(struct inode *inode, bool hidden_inode)

  {
  	struct buffer_head *bh = NULL;
  	struct fileEntry *fe;

  	struct extendedFileEntry *efe;

  	uint16_t ident;

  	struct udf_inode_info *iinfo = UDF_I(inode);

  	struct udf_sb_info *sbi = UDF_SB(inode->i_sb);

  	struct kernel_lb_addr *iloc = &iinfo->i_location;

  	unsigned int link_count;

  	unsigned int indirections = 0;

  	int bs = inode->i_sb->s_blocksize;

  	int ret = -EIO;

  reread:

  	if (iloc->logicalBlockNum >=
  	    sbi->s_partmaps[iloc->partitionReferenceNum].s_partition_len) {
  		udf_debug("block=%d, partition=%d out of range
  ",
  			  iloc->logicalBlockNum, iloc->partitionReferenceNum);
  		return -EIO;
  	}

  	/*
  	 * Set defaults, but the inode is still incomplete!
  	 * Note: get_new_inode() sets the following on a new inode:
  	 *      i_sb = sb
  	 *      i_no = ino
  	 *      i_flags = sb->s_flags
  	 *      i_state = 0
  	 * clean_inode(): zero fills and sets
  	 *      i_count = 1
  	 *      i_nlink = 1
  	 *      i_op = NULL;
  	 */

  	bh = udf_read_ptagged(inode->i_sb, iloc, 0, &ident);

  	if (!bh) {

  		udf_err(inode->i_sb, "(ino %ld) failed !bh
  ", inode->i_ino);

  		return -EIO;

  	}
  
  	if (ident != TAG_IDENT_FE && ident != TAG_IDENT_EFE &&

  	    ident != TAG_IDENT_USE) {

  		udf_err(inode->i_sb, "(ino %ld) failed ident=%d
  ",
  			inode->i_ino, ident);

  		goto out;

  	}
  
  	fe = (struct fileEntry *)bh->b_data;

  	efe = (struct extendedFileEntry *)bh->b_data;

  	if (fe->icbTag.strategyType == cpu_to_le16(4096)) {

  		struct buffer_head *ibh;

  		ibh = udf_read_ptagged(inode->i_sb, iloc, 1, &ident);

  		if (ident == TAG_IDENT_IE && ibh) {

  			struct kernel_lb_addr loc;

  			struct indirectEntry *ie;
  
  			ie = (struct indirectEntry *)ibh->b_data;
  			loc = lelb_to_cpu(ie->indirectICB.extLocation);

  			if (ie->indirectICB.extLength) {

  				brelse(ibh);
  				memcpy(&iinfo->i_location, &loc,
  				       sizeof(struct kernel_lb_addr));
  				if (++indirections > UDF_MAX_ICB_NESTING) {
  					udf_err(inode->i_sb,
  						"too many ICBs in ICB hierarchy"
  						" (max %d supported)
  ",
  						UDF_MAX_ICB_NESTING);

  					goto out;

  				}

  				brelse(bh);

  				goto reread;

  			}

  		}

  		brelse(ibh);

  	} else if (fe->icbTag.strategyType != cpu_to_le16(4)) {

  		udf_err(inode->i_sb, "unsupported strategy type: %d
  ",
  			le16_to_cpu(fe->icbTag.strategyType));

  		goto out;

  	}

  	if (fe->icbTag.strategyType == cpu_to_le16(4))

  		iinfo->i_strat4096 = 0;

  	else /* if (fe->icbTag.strategyType == cpu_to_le16(4096)) */

  		iinfo->i_strat4096 = 1;

  	iinfo->i_alloc_type = le16_to_cpu(fe->icbTag.flags) &

  							ICBTAG_FLAG_AD_MASK;

  	iinfo->i_unique = 0;
  	iinfo->i_lenEAttr = 0;
  	iinfo->i_lenExtents = 0;
  	iinfo->i_lenAlloc = 0;
  	iinfo->i_next_alloc_block = 0;
  	iinfo->i_next_alloc_goal = 0;

  	if (fe->descTag.tagIdent == cpu_to_le16(TAG_IDENT_EFE)) {

  		iinfo->i_efe = 1;
  		iinfo->i_use = 0;

  		ret = udf_alloc_i_data(inode, bs -

  					sizeof(struct extendedFileEntry));
  		if (ret)
  			goto out;

  		memcpy(iinfo->i_ext.i_data,

  		       bh->b_data + sizeof(struct extendedFileEntry),

  		       bs - sizeof(struct extendedFileEntry));

  	} else if (fe->descTag.tagIdent == cpu_to_le16(TAG_IDENT_FE)) {

  		iinfo->i_efe = 0;
  		iinfo->i_use = 0;

  		ret = udf_alloc_i_data(inode, bs - sizeof(struct fileEntry));

  		if (ret)
  			goto out;

  		memcpy(iinfo->i_ext.i_data,

  		       bh->b_data + sizeof(struct fileEntry),

  		       bs - sizeof(struct fileEntry));

  	} else if (fe->descTag.tagIdent == cpu_to_le16(TAG_IDENT_USE)) {

  		iinfo->i_efe = 0;
  		iinfo->i_use = 1;
  		iinfo->i_lenAlloc = le32_to_cpu(

  				((struct unallocSpaceEntry *)bh->b_data)->
  				 lengthAllocDescs);

  		ret = udf_alloc_i_data(inode, bs -

  					sizeof(struct unallocSpaceEntry));
  		if (ret)
  			goto out;

  		memcpy(iinfo->i_ext.i_data,

  		       bh->b_data + sizeof(struct unallocSpaceEntry),

  		       bs - sizeof(struct unallocSpaceEntry));

  		return 0;

  	}

  	ret = -EIO;

  	read_lock(&sbi->s_cred_lock);

  	i_uid_write(inode, le32_to_cpu(fe->uid));
  	if (!uid_valid(inode->i_uid) ||

  	    UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_UID_IGNORE) ||
  	    UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_UID_SET))

  		inode->i_uid = UDF_SB(inode->i_sb)->s_uid;

  	i_gid_write(inode, le32_to_cpu(fe->gid));
  	if (!gid_valid(inode->i_gid) ||

  	    UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_GID_IGNORE) ||
  	    UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_GID_SET))

  		inode->i_gid = UDF_SB(inode->i_sb)->s_gid;