/*

   *  linux/fs/ext4/namei.c

   *
   * Copyright (C) 1992, 1993, 1994, 1995
   * Remy Card (card@masi.ibp.fr)
   * Laboratoire MASI - Institut Blaise Pascal
   * Universite Pierre et Marie Curie (Paris VI)
   *
   *  from
   *
   *  linux/fs/minix/namei.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   *
   *  Big-endian to little-endian byte-swapping/bitmaps by
   *        David S. Miller (davem@caip.rutgers.edu), 1995
   *  Directory entry file type support and forward compatibility hooks
   *	for B-tree directories by Theodore Ts'o (tytso@mit.edu), 1998
   *  Hash Tree Directory indexing (c)
   *	Daniel Phillips, 2001
   *  Hash Tree Directory indexing porting
   *	Christopher Li, 2002
   *  Hash Tree Directory indexing cleanup
   *	Theodore Ts'o, 2002
   */
  
  #include <linux/fs.h>
  #include <linux/pagemap.h>

  #include <linux/jbd2.h>

  #include <linux/time.h>

  #include <linux/fcntl.h>
  #include <linux/stat.h>
  #include <linux/string.h>
  #include <linux/quotaops.h>
  #include <linux/buffer_head.h>
  #include <linux/bio.h>

  #include "ext4.h"
  #include "ext4_jbd2.h"

  #include "xattr.h"
  #include "acl.h"

  #include <trace/events/ext4.h>

  /*
   * define how far ahead to read directories while searching them.
   */
  #define NAMEI_RA_CHUNKS  2
  #define NAMEI_RA_BLOCKS  4

  #define NAMEI_RA_SIZE	     (NAMEI_RA_CHUNKS * NAMEI_RA_BLOCKS)

  #define NAMEI_RA_INDEX(c,b)  (((c) * NAMEI_RA_BLOCKS) + (b))

  static struct buffer_head *ext4_append(handle_t *handle,

  					struct inode *inode,

  					ext4_lblk_t *block, int *err)

  {
  	struct buffer_head *bh;
  
  	*block = inode->i_size >> inode->i_sb->s_blocksize_bits;

  	bh = ext4_bread(handle, inode, *block, 1, err);
  	if (bh) {

  		inode->i_size += inode->i_sb->s_blocksize;

  		EXT4_I(inode)->i_disksize = inode->i_size;

  		*err = ext4_journal_get_write_access(handle, bh);
  		if (*err) {
  			brelse(bh);
  			bh = NULL;
  		}

  	}
  	return bh;
  }
  
  #ifndef assert
  #define assert(test) J_ASSERT(test)
  #endif

  #ifdef DX_DEBUG
  #define dxtrace(command) command
  #else
  #define dxtrace(command)
  #endif
  
  struct fake_dirent
  {
  	__le32 inode;
  	__le16 rec_len;
  	u8 name_len;
  	u8 file_type;
  };
  
  struct dx_countlimit
  {
  	__le16 limit;
  	__le16 count;
  };
  
  struct dx_entry
  {
  	__le32 hash;
  	__le32 block;
  };
  
  /*
   * dx_root_info is laid out so that if it should somehow get overlaid by a
   * dirent the two low bits of the hash version will be zero.  Therefore, the
   * hash version mod 4 should never be 0.  Sincerely, the paranoia department.
   */
  
  struct dx_root
  {
  	struct fake_dirent dot;
  	char dot_name[4];
  	struct fake_dirent dotdot;
  	char dotdot_name[4];
  	struct dx_root_info
  	{
  		__le32 reserved_zero;
  		u8 hash_version;
  		u8 info_length; /* 8 */
  		u8 indirect_levels;
  		u8 unused_flags;
  	}
  	info;
  	struct dx_entry	entries[0];
  };
  
  struct dx_node
  {
  	struct fake_dirent fake;
  	struct dx_entry	entries[0];
  };
  
  
  struct dx_frame
  {
  	struct buffer_head *bh;
  	struct dx_entry *entries;
  	struct dx_entry *at;
  };
  
  struct dx_map_entry
  {
  	u32 hash;

  	u16 offs;
  	u16 size;

  };

  static inline ext4_lblk_t dx_get_block(struct dx_entry *entry);
  static void dx_set_block(struct dx_entry *entry, ext4_lblk_t value);

  static inline unsigned dx_get_hash(struct dx_entry *entry);
  static void dx_set_hash(struct dx_entry *entry, unsigned value);
  static unsigned dx_get_count(struct dx_entry *entries);
  static unsigned dx_get_limit(struct dx_entry *entries);
  static void dx_set_count(struct dx_entry *entries, unsigned value);
  static void dx_set_limit(struct dx_entry *entries, unsigned value);
  static unsigned dx_root_limit(struct inode *dir, unsigned infosize);
  static unsigned dx_node_limit(struct inode *dir);

  static struct dx_frame *dx_probe(const struct qstr *d_name,

  				 struct inode *dir,
  				 struct dx_hash_info *hinfo,
  				 struct dx_frame *frame,
  				 int *err);

  static void dx_release(struct dx_frame *frames);

  static int dx_make_map(struct ext4_dir_entry_2 *de, unsigned blocksize,

  		       struct dx_hash_info *hinfo, struct dx_map_entry map[]);

  static void dx_sort_map(struct dx_map_entry *map, unsigned count);

  static struct ext4_dir_entry_2 *dx_move_dirents(char *from, char *to,

  		struct dx_map_entry *offsets, int count, unsigned blocksize);

  static struct ext4_dir_entry_2* dx_pack_dirents(char *base, unsigned blocksize);

  static void dx_insert_block(struct dx_frame *frame,
  					u32 hash, ext4_lblk_t block);

  static int ext4_htree_next_block(struct inode *dir, __u32 hash,

  				 struct dx_frame *frame,
  				 struct dx_frame *frames,
  				 __u32 *start_hash);

  static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
  		const struct qstr *d_name,
  		struct ext4_dir_entry_2 **res_dir,
  		int *err);

  static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,

  			     struct inode *inode);
  
  /*

   * p is at least 6 bytes before the end of page
   */
  static inline struct ext4_dir_entry_2 *

  ext4_next_entry(struct ext4_dir_entry_2 *p, unsigned long blocksize)

  {
  	return (struct ext4_dir_entry_2 *)((char *)p +

  		ext4_rec_len_from_disk(p->rec_len, blocksize));

  }
  
  /*

   * Future: use high four bits of block for coalesce-on-delete flags
   * Mask them off for now.
   */

  static inline ext4_lblk_t dx_get_block(struct dx_entry *entry)

  {
  	return le32_to_cpu(entry->block) & 0x00ffffff;
  }

  static inline void dx_set_block(struct dx_entry *entry, ext4_lblk_t value)

  {
  	entry->block = cpu_to_le32(value);
  }

  static inline unsigned dx_get_hash(struct dx_entry *entry)

  {
  	return le32_to_cpu(entry->hash);
  }

  static inline void dx_set_hash(struct dx_entry *entry, unsigned value)

  {
  	entry->hash = cpu_to_le32(value);
  }

  static inline unsigned dx_get_count(struct dx_entry *entries)

  {
  	return le16_to_cpu(((struct dx_countlimit *) entries)->count);
  }

  static inline unsigned dx_get_limit(struct dx_entry *entries)

  {
  	return le16_to_cpu(((struct dx_countlimit *) entries)->limit);
  }

  static inline void dx_set_count(struct dx_entry *entries, unsigned value)

  {
  	((struct dx_countlimit *) entries)->count = cpu_to_le16(value);
  }

  static inline void dx_set_limit(struct dx_entry *entries, unsigned value)

  {
  	((struct dx_countlimit *) entries)->limit = cpu_to_le16(value);
  }

  static inline unsigned dx_root_limit(struct inode *dir, unsigned infosize)

  {

  	unsigned entry_space = dir->i_sb->s_blocksize - EXT4_DIR_REC_LEN(1) -
  		EXT4_DIR_REC_LEN(2) - infosize;

  	return entry_space / sizeof(struct dx_entry);

  }

  static inline unsigned dx_node_limit(struct inode *dir)

  {

  	unsigned entry_space = dir->i_sb->s_blocksize - EXT4_DIR_REC_LEN(0);

  	return entry_space / sizeof(struct dx_entry);

  }
  
  /*
   * Debug
   */
  #ifdef DX_DEBUG

  static void dx_show_index(char * label, struct dx_entry *entries)

  {

  	int i, n = dx_get_count (entries);

  	printk(KERN_DEBUG "%s index ", label);

  	for (i = 0; i < n; i++) {

  		printk("%x->%lu ", i ? dx_get_hash(entries + i) :

  				0, (unsigned long)dx_get_block(entries + i));

  	}
  	printk("
  ");

  }
  
  struct stats
  {
  	unsigned names;
  	unsigned space;
  	unsigned bcount;
  };

  static struct stats dx_show_leaf(struct dx_hash_info *hinfo, struct ext4_dir_entry_2 *de,

  				 int size, int show_names)
  {
  	unsigned names = 0, space = 0;
  	char *base = (char *) de;
  	struct dx_hash_info h = *hinfo;
  
  	printk("names: ");
  	while ((char *) de < base + size)
  	{
  		if (de->inode)
  		{
  			if (show_names)
  			{
  				int len = de->name_len;
  				char *name = de->name;
  				while (len--) printk("%c", *name++);

  				ext4fs_dirhash(de->name, de->name_len, &h);

  				printk(":%x.%u ", h.hash,

  				       (unsigned) ((char *) de - base));

  			}

  			space += EXT4_DIR_REC_LEN(de->name_len);

  			names++;
  		}

  		de = ext4_next_entry(de, size);

  	}
  	printk("(%i)
  ", names);
  	return (struct stats) { names, space, 1 };
  }
  
  struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir,
  			     struct dx_entry *entries, int levels)
  {
  	unsigned blocksize = dir->i_sb->s_blocksize;

  	unsigned count = dx_get_count(entries), names = 0, space = 0, i;

  	unsigned bcount = 0;
  	struct buffer_head *bh;
  	int err;
  	printk("%i indexed blocks...
  ", count);
  	for (i = 0; i < count; i++, entries++)
  	{

  		ext4_lblk_t block = dx_get_block(entries);
  		ext4_lblk_t hash  = i ? dx_get_hash(entries): 0;

  		u32 range = i < count - 1? (dx_get_hash(entries + 1) - hash): ~hash;
  		struct stats stats;
  		printk("%s%3u:%03u hash %8x/%8x ",levels?"":"   ", i, block, hash, range);

  		if (!(bh = ext4_bread (NULL,dir, block, 0,&err))) continue;

  		stats = levels?
  		   dx_show_entries(hinfo, dir, ((struct dx_node *) bh->b_data)->entries, levels - 1):

  		   dx_show_leaf(hinfo, (struct ext4_dir_entry_2 *) bh->b_data, blocksize, 0);

  		names += stats.names;
  		space += stats.space;
  		bcount += stats.bcount;

  		brelse(bh);

  	}
  	if (bcount)

  		printk(KERN_DEBUG "%snames %u, fullness %u (%u%%)
  ",

  		       levels ? "" : "   ", names, space/bcount,
  		       (space/bcount)*100/blocksize);

  	return (struct stats) { names, space, bcount};
  }
  #endif /* DX_DEBUG */
  
  /*
   * Probe for a directory leaf block to search.
   *
   * dx_probe can return ERR_BAD_DX_DIR, which means there was a format
   * error in the directory index, and the caller should fall back to
   * searching the directory normally.  The callers of dx_probe **MUST**
   * check for this error code, and make sure it never gets reflected
   * back to userspace.
   */
  static struct dx_frame *

  dx_probe(const struct qstr *d_name, struct inode *dir,

  	 struct dx_hash_info *hinfo, struct dx_frame *frame_in, int *err)
  {
  	unsigned count, indirect;
  	struct dx_entry *at, *entries, *p, *q, *m;
  	struct dx_root *root;
  	struct buffer_head *bh;
  	struct dx_frame *frame = frame_in;
  	u32 hash;
  
  	frame->bh = NULL;

  	if (!(bh = ext4_bread (NULL,dir, 0, 0, err)))

  		goto fail;
  	root = (struct dx_root *) bh->b_data;
  	if (root->info.hash_version != DX_HASH_TEA &&
  	    root->info.hash_version != DX_HASH_HALF_MD4 &&
  	    root->info.hash_version != DX_HASH_LEGACY) {

  		ext4_warning(dir->i_sb, "Unrecognised inode hash code %d",

  			     root->info.hash_version);
  		brelse(bh);
  		*err = ERR_BAD_DX_DIR;
  		goto fail;
  	}
  	hinfo->hash_version = root->info.hash_version;

  	if (hinfo->hash_version <= DX_HASH_TEA)
  		hinfo->hash_version += EXT4_SB(dir->i_sb)->s_hash_unsigned;

  	hinfo->seed = EXT4_SB(dir->i_sb)->s_hash_seed;

  	if (d_name)
  		ext4fs_dirhash(d_name->name, d_name->len, hinfo);

  	hash = hinfo->hash;
  
  	if (root->info.unused_flags & 1) {

  		ext4_warning(dir->i_sb, "Unimplemented inode hash flags: %#06x",

  			     root->info.unused_flags);
  		brelse(bh);
  		*err = ERR_BAD_DX_DIR;
  		goto fail;
  	}
  
  	if ((indirect = root->info.indirect_levels) > 1) {

  		ext4_warning(dir->i_sb, "Unimplemented inode hash depth: %#06x",

  			     root->info.indirect_levels);
  		brelse(bh);
  		*err = ERR_BAD_DX_DIR;
  		goto fail;
  	}
  
  	entries = (struct dx_entry *) (((char *)&root->info) +
  				       root->info.info_length);

  
  	if (dx_get_limit(entries) != dx_root_limit(dir,
  						   root->info.info_length)) {

  		ext4_warning(dir->i_sb, "dx entry: limit != root limit");

  		brelse(bh);
  		*err = ERR_BAD_DX_DIR;
  		goto fail;
  	}

  	dxtrace(printk("Look up %x", hash));

  	while (1)
  	{
  		count = dx_get_count(entries);

  		if (!count || count > dx_get_limit(entries)) {

  			ext4_warning(dir->i_sb,

  				     "dx entry: no count or count > limit");
  			brelse(bh);
  			*err = ERR_BAD_DX_DIR;
  			goto fail2;
  		}

  		p = entries + 1;
  		q = entries + count - 1;
  		while (p <= q)
  		{
  			m = p + (q - p)/2;
  			dxtrace(printk("."));
  			if (dx_get_hash(m) > hash)
  				q = m - 1;
  			else
  				p = m + 1;
  		}
  
  		if (0) // linear search cross check
  		{
  			unsigned n = count - 1;
  			at = entries;
  			while (n--)
  			{
  				dxtrace(printk(","));
  				if (dx_get_hash(++at) > hash)
  				{
  					at--;
  					break;
  				}
  			}
  			assert (at == p - 1);
  		}
  
  		at = p - 1;
  		dxtrace(printk(" %x->%u
  ", at == entries? 0: dx_get_hash(at), dx_get_block(at)));
  		frame->bh = bh;
  		frame->entries = entries;
  		frame->at = at;
  		if (!indirect--) return frame;

  		if (!(bh = ext4_bread (NULL,dir, dx_get_block(at), 0, err)))

  			goto fail2;
  		at = entries = ((struct dx_node *) bh->b_data)->entries;

  		if (dx_get_limit(entries) != dx_node_limit (dir)) {

  			ext4_warning(dir->i_sb,

  				     "dx entry: limit != node limit");
  			brelse(bh);
  			*err = ERR_BAD_DX_DIR;
  			goto fail2;
  		}

  		frame++;

  		frame->bh = NULL;

  	}
  fail2:
  	while (frame >= frame_in) {
  		brelse(frame->bh);
  		frame--;
  	}
  fail:

  	if (*err == ERR_BAD_DX_DIR)

  		ext4_warning(dir->i_sb,

  			     "Corrupt dir inode %ld, running e2fsck is "
  			     "recommended.", dir->i_ino);

  	return NULL;
  }
  
  static void dx_release (struct dx_frame *frames)
  {
  	if (frames[0].bh == NULL)
  		return;
  
  	if (((struct dx_root *) frames[0].bh->b_data)->info.indirect_levels)
  		brelse(frames[1].bh);
  	brelse(frames[0].bh);
  }
  
  /*
   * This function increments the frame pointer to search the next leaf
   * block, and reads in the necessary intervening nodes if the search
   * should be necessary.  Whether or not the search is necessary is
   * controlled by the hash parameter.  If the hash value is even, then
   * the search is only continued if the next block starts with that
   * hash value.  This is used if we are searching for a specific file.
   *
   * If the hash value is HASH_NB_ALWAYS, then always go to the next block.
   *
   * This function returns 1 if the caller should continue to search,
   * or 0 if it should not.  If there is an error reading one of the
   * index blocks, it will a negative error code.
   *
   * If start_hash is non-null, it will be filled in with the starting
   * hash of the next page.
   */

  static int ext4_htree_next_block(struct inode *dir, __u32 hash,

  				 struct dx_frame *frame,
  				 struct dx_frame *frames,
  				 __u32 *start_hash)
  {
  	struct dx_frame *p;
  	struct buffer_head *bh;
  	int err, num_frames = 0;
  	__u32 bhash;
  
  	p = frame;
  	/*
  	 * Find the next leaf page by incrementing the frame pointer.
  	 * If we run out of entries in the interior node, loop around and
  	 * increment pointer in the parent node.  When we break out of
  	 * this loop, num_frames indicates the number of interior
  	 * nodes need to be read.
  	 */
  	while (1) {
  		if (++(p->at) < p->entries + dx_get_count(p->entries))
  			break;
  		if (p == frames)
  			return 0;
  		num_frames++;
  		p--;
  	}
  
  	/*
  	 * If the hash is 1, then continue only if the next page has a
  	 * continuation hash of any value.  This is used for readdir
  	 * handling.  Otherwise, check to see if the hash matches the
  	 * desired contiuation hash.  If it doesn't, return since
  	 * there's no point to read in the successive index pages.
  	 */
  	bhash = dx_get_hash(p->at);
  	if (start_hash)
  		*start_hash = bhash;
  	if ((hash & 1) == 0) {
  		if ((bhash & ~1) != hash)
  			return 0;
  	}
  	/*
  	 * If the hash is HASH_NB_ALWAYS, we always go to the next
  	 * block so no check is necessary
  	 */
  	while (num_frames--) {

  		if (!(bh = ext4_bread(NULL, dir, dx_get_block(p->at),

  				      0, &err)))
  			return err; /* Failure */
  		p++;

  		brelse(p->bh);

  		p->bh = bh;
  		p->at = p->entries = ((struct dx_node *) bh->b_data)->entries;
  	}
  	return 1;
  }
  
  
  /*

   * This function fills a red-black tree with information from a
   * directory block.  It returns the number directory entries loaded
   * into the tree.  If there is an error it is returned in err.
   */
  static int htree_dirblock_to_tree(struct file *dir_file,

  				  struct inode *dir, ext4_lblk_t block,

  				  struct dx_hash_info *hinfo,
  				  __u32 start_hash, __u32 start_minor_hash)
  {
  	struct buffer_head *bh;

  	struct ext4_dir_entry_2 *de, *top;

  	int err, count = 0;

  	dxtrace(printk(KERN_INFO "In htree dirblock_to_tree: block %lu
  ",
  							(unsigned long)block));

  	if (!(bh = ext4_bread (NULL, dir, block, 0, &err)))

  		return err;

  	de = (struct ext4_dir_entry_2 *) bh->b_data;
  	top = (struct ext4_dir_entry_2 *) ((char *) de +

  					   dir->i_sb->s_blocksize -

  					   EXT4_DIR_REC_LEN(0));

  	for (; de < top; de = ext4_next_entry(de, dir->i_sb->s_blocksize)) {

  		if (ext4_check_dir_entry(dir, NULL, de, bh,

  				(block<<EXT4_BLOCK_SIZE_BITS(dir->i_sb))
  					 + ((char *)de - bh->b_data))) {

  			/* On error, skip the f_pos to the next block. */
  			dir_file->f_pos = (dir_file->f_pos |
  					(dir->i_sb->s_blocksize - 1)) + 1;

  			brelse(bh);

  			return count;
  		}

  		ext4fs_dirhash(de->name, de->name_len, hinfo);

  		if ((hinfo->hash < start_hash) ||
  		    ((hinfo->hash == start_hash) &&
  		     (hinfo->minor_hash < start_minor_hash)))
  			continue;
  		if (de->inode == 0)
  			continue;

  		if ((err = ext4_htree_store_dirent(dir_file,

  				   hinfo->hash, hinfo->minor_hash, de)) != 0) {
  			brelse(bh);
  			return err;
  		}
  		count++;
  	}
  	brelse(bh);
  	return count;
  }
  
  
  /*
   * This function fills a red-black tree with information from a
   * directory.  We start scanning the directory in hash order, starting
   * at start_hash and start_minor_hash.
   *
   * This function returns the number of entries inserted into the tree,
   * or a negative error code.
   */

  int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,

  			 __u32 start_minor_hash, __u32 *next_hash)
  {
  	struct dx_hash_info hinfo;

  	struct ext4_dir_entry_2 *de;

  	struct dx_frame frames[2], *frame;
  	struct inode *dir;

  	ext4_lblk_t block;

  	int count = 0;

  	int ret, err;

  	__u32 hashval;

  	dxtrace(printk(KERN_DEBUG "In htree_fill_tree, start hash: %x:%x
  ",

  		       start_hash, start_minor_hash));

  	dir = dir_file->f_path.dentry->d_inode;

  	if (!(ext4_test_inode_flag(dir, EXT4_INODE_INDEX))) {

  		hinfo.hash_version = EXT4_SB(dir->i_sb)->s_def_hash_version;

  		if (hinfo.hash_version <= DX_HASH_TEA)
  			hinfo.hash_version +=
  				EXT4_SB(dir->i_sb)->s_hash_unsigned;

  		hinfo.seed = EXT4_SB(dir->i_sb)->s_hash_seed;

  		count = htree_dirblock_to_tree(dir_file, dir, 0, &hinfo,
  					       start_hash, start_minor_hash);
  		*next_hash = ~0;
  		return count;
  	}
  	hinfo.hash = start_hash;
  	hinfo.minor_hash = 0;

  	frame = dx_probe(NULL, dir, &hinfo, frames, &err);

  	if (!frame)
  		return err;
  
  	/* Add '.' and '..' from the htree header */
  	if (!start_hash && !start_minor_hash) {

  		de = (struct ext4_dir_entry_2 *) frames[0].bh->b_data;
  		if ((err = ext4_htree_store_dirent(dir_file, 0, 0, de)) != 0)

  			goto errout;
  		count++;
  	}
  	if (start_hash < 2 || (start_hash ==2 && start_minor_hash==0)) {

  		de = (struct ext4_dir_entry_2 *) frames[0].bh->b_data;

  		de = ext4_next_entry(de, dir->i_sb->s_blocksize);

  		if ((err = ext4_htree_store_dirent(dir_file, 2, 0, de)) != 0)

  			goto errout;
  		count++;
  	}
  
  	while (1) {
  		block = dx_get_block(frame->at);
  		ret = htree_dirblock_to_tree(dir_file, dir, block, &hinfo,
  					     start_hash, start_minor_hash);
  		if (ret < 0) {
  			err = ret;
  			goto errout;
  		}
  		count += ret;
  		hashval = ~0;

  		ret = ext4_htree_next_block(dir, HASH_NB_ALWAYS,

  					    frame, frames, &hashval);
  		*next_hash = hashval;
  		if (ret < 0) {
  			err = ret;
  			goto errout;
  		}
  		/*
  		 * Stop if:  (a) there are no more entries, or
  		 * (b) we have inserted at least one entry and the
  		 * next hash value is not a continuation
  		 */
  		if ((ret == 0) ||
  		    (count && ((hashval & 1) == 0)))
  			break;
  	}
  	dx_release(frames);

  	dxtrace(printk(KERN_DEBUG "Fill tree: returned %d entries, "
  		       "next hash: %x
  ", count, *next_hash));

  	return count;
  errout:
  	dx_release(frames);
  	return (err);
  }
  
  
  /*
   * Directory block splitting, compacting
   */

  /*
   * Create map of hash values, offsets, and sizes, stored at end of block.
   * Returns number of entries mapped.
   */

  static int dx_make_map(struct ext4_dir_entry_2 *de, unsigned blocksize,
  		       struct dx_hash_info *hinfo,
  		       struct dx_map_entry *map_tail)

  {
  	int count = 0;
  	char *base = (char *) de;
  	struct dx_hash_info h = *hinfo;

  	while ((char *) de < base + blocksize) {

  		if (de->name_len && de->inode) {

  			ext4fs_dirhash(de->name, de->name_len, &h);

  			map_tail--;
  			map_tail->hash = h.hash;

  			map_tail->offs = ((char *) de - base)>>2;

  			map_tail->size = le16_to_cpu(de->rec_len);

  			count++;
  			cond_resched();
  		}
  		/* XXX: do we need to check rec_len == 0 case? -Chris */

  		de = ext4_next_entry(de, blocksize);

  	}
  	return count;
  }

  /* Sort map by hash value */

  static void dx_sort_map (struct dx_map_entry *map, unsigned count)
  {

  	struct dx_map_entry *p, *q, *top = map + count - 1;
  	int more;
  	/* Combsort until bubble sort doesn't suck */
  	while (count > 2) {
  		count = count*10/13;
  		if (count - 9 < 2) /* 9, 10 -> 11 */
  			count = 11;
  		for (p = top, q = p - count; q >= map; p--, q--)
  			if (p->hash < q->hash)
  				swap(*p, *q);
  	}
  	/* Garden variety bubble sort */
  	do {
  		more = 0;
  		q = top;
  		while (q-- > map) {
  			if (q[1].hash >= q[0].hash)

  				continue;

  			swap(*(q+1), *q);
  			more = 1;

  		}
  	} while(more);
  }

  static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)

  {
  	struct dx_entry *entries = frame->entries;
  	struct dx_entry *old = frame->at, *new = old + 1;
  	int count = dx_get_count(entries);
  
  	assert(count < dx_get_limit(entries));
  	assert(old < entries + count);
  	memmove(new + 1, new, (char *)(entries + count) - (char *)(new));
  	dx_set_hash(new, hash);
  	dx_set_block(new, block);
  	dx_set_count(entries, count + 1);
  }

  static void ext4_update_dx_flag(struct inode *inode)

  {

  	if (!EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
  				     EXT4_FEATURE_COMPAT_DIR_INDEX))

  		ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);

  }
  
  /*

   * NOTE! unlike strncmp, ext4_match returns 1 for success, 0 for failure.

   *

   * `len <= EXT4_NAME_LEN' is guaranteed by caller.

   * `de != NULL' is guaranteed by caller.
   */

  static inline int ext4_match (int len, const char * const name,
  			      struct ext4_dir_entry_2 * de)

  {
  	if (len != de->name_len)
  		return 0;
  	if (!de->inode)
  		return 0;
  	return !memcmp(name, de->name, len);
  }
  
  /*
   * Returns 0 if not found, -1 on failure, and 1 on success
   */

  static inline int search_dirblock(struct buffer_head *bh,

  				  struct inode *dir,

  				  const struct qstr *d_name,

  				  unsigned int offset,

  				  struct ext4_dir_entry_2 ** res_dir)

  {

  	struct ext4_dir_entry_2 * de;

  	char * dlimit;
  	int de_len;

  	const char *name = d_name->name;
  	int namelen = d_name->len;

  	de = (struct ext4_dir_entry_2 *) bh->b_data;

  	dlimit = bh->b_data + dir->i_sb->s_blocksize;
  	while ((char *) de < dlimit) {
  		/* this code is executed quadratically often */
  		/* do minimal checking `by hand' */
  
  		if ((char *) de + namelen <= dlimit &&

  		    ext4_match (namelen, name, de)) {

  			/* found a match - just to be sure, do a full check */

  			if (ext4_check_dir_entry(dir, NULL, de, bh, offset))

  				return -1;
  			*res_dir = de;
  			return 1;
  		}
  		/* prevent looping on a bad block */

  		de_len = ext4_rec_len_from_disk(de->rec_len,
  						dir->i_sb->s_blocksize);

  		if (de_len <= 0)
  			return -1;
  		offset += de_len;

  		de = (struct ext4_dir_entry_2 *) ((char *) de + de_len);

  	}
  	return 0;
  }
  
  
  /*

   *	ext4_find_entry()

   *
   * finds an entry in the specified directory with the wanted name. It
   * returns the cache buffer in which the entry was found, and the entry
   * itself (as a parameter - res_dir). It does NOT read the inode of the
   * entry - you'll have to do that yourself if you want to.
   *
   * The returned buffer_head has ->b_count elevated.  The caller is expected
   * to brelse() it when appropriate.
   */

  static struct buffer_head * ext4_find_entry (struct inode *dir,
  					const struct qstr *d_name,

  					struct ext4_dir_entry_2 ** res_dir)

  {

  	struct super_block *sb;
  	struct buffer_head *bh_use[NAMEI_RA_SIZE];
  	struct buffer_head *bh, *ret = NULL;

  	ext4_lblk_t start, block, b;

  	const u8 *name = d_name->name;

  	int ra_max = 0;		/* Number of bh's in the readahead
  				   buffer, bh_use[] */
  	int ra_ptr = 0;		/* Current index into readahead
  				   buffer */
  	int num = 0;

  	ext4_lblk_t  nblocks;
  	int i, err;

  	int namelen;

  
  	*res_dir = NULL;
  	sb = dir->i_sb;

  	namelen = d_name->len;

  	if (namelen > EXT4_NAME_LEN)

  		return NULL;

  	if ((namelen <= 2) && (name[0] == '.') &&

  	    (name[1] == '.' || name[1] == '\0')) {

  		/*
  		 * "." or ".." will only be in the first block
  		 * NFS may look up ".."; "." should be handled by the VFS
  		 */
  		block = start = 0;
  		nblocks = 1;
  		goto restart;
  	}

  	if (is_dx(dir)) {

  		bh = ext4_dx_find_entry(dir, d_name, res_dir, &err);

  		/*
  		 * On success, or if the error was file not found,
  		 * return.  Otherwise, fall back to doing a search the
  		 * old fashioned way.
  		 */
  		if (bh || (err != ERR_BAD_DX_DIR))
  			return bh;

  		dxtrace(printk(KERN_DEBUG "ext4_find_entry: dx failed, "
  			       "falling back
  "));

  	}

  	nblocks = dir->i_size >> EXT4_BLOCK_SIZE_BITS(sb);
  	start = EXT4_I(dir)->i_dir_start_lookup;

  	if (start >= nblocks)
  		start = 0;
  	block = start;
  restart:
  	do {
  		/*
  		 * We deal with the read-ahead logic here.
  		 */
  		if (ra_ptr >= ra_max) {
  			/* Refill the readahead buffer */
  			ra_ptr = 0;
  			b = block;
  			for (ra_max = 0; ra_max < NAMEI_RA_SIZE; ra_max++) {
  				/*
  				 * Terminate if we reach the end of the
  				 * directory and must wrap, or if our
  				 * search has finished at this block.
  				 */
  				if (b >= nblocks || (num && block == start)) {
  					bh_use[ra_max] = NULL;
  					break;
  				}
  				num++;

  				bh = ext4_getblk(NULL, dir, b++, 0, &err);

  				bh_use[ra_max] = bh;
  				if (bh)

  					ll_rw_block(READ | REQ_META | REQ_PRIO,
  						    1, &bh);

  			}
  		}
  		if ((bh = bh_use[ra_ptr++]) == NULL)
  			goto next;
  		wait_on_buffer(bh);
  		if (!buffer_uptodate(bh)) {
  			/* read error, skip block & hope for the best */

  			EXT4_ERROR_INODE(dir, "reading directory lblock %lu",
  					 (unsigned long) block);

  			brelse(bh);
  			goto next;
  		}

  		i = search_dirblock(bh, dir, d_name,

  			    block << EXT4_BLOCK_SIZE_BITS(sb), res_dir);

  		if (i == 1) {

  			EXT4_I(dir)->i_dir_start_lookup = block;

  			ret = bh;
  			goto cleanup_and_exit;
  		} else {
  			brelse(bh);
  			if (i < 0)
  				goto cleanup_and_exit;
  		}
  	next:
  		if (++block >= nblocks)
  			block = 0;
  	} while (block != start);
  
  	/*
  	 * If the directory has grown while we were searching, then
  	 * search the last part of the directory before giving up.
  	 */
  	block = nblocks;

  	nblocks = dir->i_size >> EXT4_BLOCK_SIZE_BITS(sb);

  	if (block < nblocks) {
  		start = 0;
  		goto restart;
  	}
  
  cleanup_and_exit:
  	/* Clean up the read-ahead blocks */
  	for (; ra_ptr < ra_max; ra_ptr++)

  		brelse(bh_use[ra_ptr]);

  	return ret;
  }

  static struct buffer_head * ext4_dx_find_entry(struct inode *dir, const struct qstr *d_name,

  		       struct ext4_dir_entry_2 **res_dir, int *err)

  {

  	struct super_block * sb = dir->i_sb;

  	struct dx_hash_info	hinfo;

  	struct dx_frame frames[2], *frame;

  	struct buffer_head *bh;

  	ext4_lblk_t block;

  	int retval;

  	if (!(frame = dx_probe(d_name, dir, &hinfo, frames, err)))
  		return NULL;

  	do {
  		block = dx_get_block(frame->at);

  		if (!(bh = ext4_bread(NULL, dir, block, 0, err)))

  			goto errout;

  		retval = search_dirblock(bh, dir, d_name,
  					 block << EXT4_BLOCK_SIZE_BITS(sb),
  					 res_dir);
  		if (retval == 1) { 	/* Success! */
  			dx_release(frames);
  			return bh;

  		}

  		brelse(bh);

  		if (retval == -1) {
  			*err = ERR_BAD_DX_DIR;
  			goto errout;
  		}

  		/* Check to see if we should continue to search */

  		retval = ext4_htree_next_block(dir, hinfo.hash, frame,

  					       frames, NULL);
  		if (retval < 0) {

  			ext4_warning(sb,

  			     "error reading index page in directory #%lu",
  			     dir->i_ino);
  			*err = retval;
  			goto errout;
  		}
  	} while (retval == 1);
  
  	*err = -ENOENT;
  errout:

  	dxtrace(printk(KERN_DEBUG "%s not found
  ", d_name->name));

  	dx_release (frames);
  	return NULL;
  }

  static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)

  {

  	struct inode *inode;
  	struct ext4_dir_entry_2 *de;
  	struct buffer_head *bh;

  	if (dentry->d_name.len > EXT4_NAME_LEN)

  		return ERR_PTR(-ENAMETOOLONG);

  	bh = ext4_find_entry(dir, &dentry->d_name, &de);

  	inode = NULL;
  	if (bh) {

  		__u32 ino = le32_to_cpu(de->inode);

  		brelse(bh);

  		if (!ext4_valid_inum(dir->i_sb, ino)) {

  			EXT4_ERROR_INODE(dir, "bad inode number: %u", ino);

  			return ERR_PTR(-EIO);

  		}

  		inode = ext4_iget(dir->i_sb, ino);

  		if (inode == ERR_PTR(-ESTALE)) {
  			EXT4_ERROR_INODE(dir,
  					 "deleted inode referenced: %u",
  					 ino);
  			return ERR_PTR(-EIO);

  		}

  	}
  	return d_splice_alias(inode, dentry);
  }

  struct dentry *ext4_get_parent(struct dentry *child)

  {

  	__u32 ino;

  	static const struct qstr dotdot = {
  		.name = "..",
  		.len = 2,
  	};

  	struct ext4_dir_entry_2 * de;

  	struct buffer_head *bh;

  	bh = ext4_find_entry(child->d_inode, &dotdot, &de);

  	if (!bh)
  		return ERR_PTR(-ENOENT);
  	ino = le32_to_cpu(de->inode);
  	brelse(bh);

  	if (!ext4_valid_inum(child->d_inode->i_sb, ino)) {

  		EXT4_ERROR_INODE(child->d_inode,
  				 "bad parent inode number: %u", ino);

  		return ERR_PTR(-EIO);

  	}

  	return d_obtain_alias(ext4_iget(child->d_inode->i_sb, ino));

  }
  
  #define S_SHIFT 12

  static unsigned char ext4_type_by_mode[S_IFMT >> S_SHIFT] = {
  	[S_IFREG >> S_SHIFT]	= EXT4_FT_REG_FILE,
  	[S_IFDIR >> S_SHIFT]	= EXT4_FT_DIR,
  	[S_IFCHR >> S_SHIFT]	= EXT4_FT_CHRDEV,
  	[S_IFBLK >> S_SHIFT]	= EXT4_FT_BLKDEV,
  	[S_IFIFO >> S_SHIFT]	= EXT4_FT_FIFO,
  	[S_IFSOCK >> S_SHIFT]	= EXT4_FT_SOCK,
  	[S_IFLNK >> S_SHIFT]	= EXT4_FT_SYMLINK,

  };

  static inline void ext4_set_de_type(struct super_block *sb,
  				struct ext4_dir_entry_2 *de,

  				umode_t mode) {

  	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE))
  		de->file_type = ext4_type_by_mode[(mode & S_IFMT)>>S_SHIFT];

  }

  /*
   * Move count entries from end of map between two memory locations.
   * Returns pointer to last entry moved.
   */

  static struct ext4_dir_entry_2 *

  dx_move_dirents(char *from, char *to, struct dx_map_entry *map, int count,
  		unsigned blocksize)

  {
  	unsigned rec_len = 0;
  
  	while (count--) {

  		struct ext4_dir_entry_2 *de = (struct ext4_dir_entry_2 *)

  						(from + (map->offs<<2));

  		rec_len = EXT4_DIR_REC_LEN(de->name_len);

  		memcpy (to, de, rec_len);

  		((struct ext4_dir_entry_2 *) to)->rec_len =

  				ext4_rec_len_to_disk(rec_len, blocksize);

  		de->inode = 0;
  		map++;
  		to += rec_len;
  	}

  	return (struct ext4_dir_entry_2 *) (to - rec_len);

  }

  /*
   * Compact each dir entry in the range to the minimal rec_len.
   * Returns pointer to last entry in range.
   */

  static struct ext4_dir_entry_2* dx_pack_dirents(char *base, unsigned blocksize)

  {

  	struct ext4_dir_entry_2 *next, *to, *prev, *de = (struct ext4_dir_entry_2 *) base;

  	unsigned rec_len = 0;
  
  	prev = to = de;

  	while ((char*)de < base + blocksize) {

  		next = ext4_next_entry(de, blocksize);

  		if (de->inode && de->name_len) {

  			rec_len = EXT4_DIR_REC_LEN(de->name_len);

  			if (de > to)
  				memmove(to, de, rec_len);

  			to->rec_len = ext4_rec_len_to_disk(rec_len, blocksize);

  			prev = to;

  			to = (struct ext4_dir_entry_2 *) (((char *) to) + rec_len);

  		}
  		de = next;
  	}
  	return prev;
  }

  /*
   * Split a full leaf block to make room for a new dir entry.
   * Allocate a new block, and move entries so that they are approx. equally full.
   * Returns pointer to de in block into which the new entry will be inserted.
   */

  static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,

  			struct buffer_head **bh,struct dx_frame *frame,
  			struct dx_hash_info *hinfo, int *error)
  {
  	unsigned blocksize = dir->i_sb->s_blocksize;
  	unsigned count, continued;
  	struct buffer_head *bh2;

  	ext4_lblk_t newblock;

  	u32 hash2;
  	struct dx_map_entry *map;
  	char *data1 = (*bh)->b_data, *data2;

  	unsigned split, move, size;

  	struct ext4_dir_entry_2 *de = NULL, *de2;

  	int	err = 0, i;

  	bh2 = ext4_append (handle, dir, &newblock, &err);

  	if (!(bh2)) {
  		brelse(*bh);
  		*bh = NULL;
  		goto errout;
  	}
  
  	BUFFER_TRACE(*bh, "get_write_access");

  	err = ext4_journal_get_write_access(handle, *bh);

  	if (err)
  		goto journal_error;

  	BUFFER_TRACE(frame->bh, "get_write_access");

  	err = ext4_journal_get_write_access(handle, frame->bh);

  	if (err)
  		goto journal_error;
  
  	data2 = bh2->b_data;
  
  	/* create map in the end of data2 block */
  	map = (struct dx_map_entry *) (data2 + blocksize);

  	count = dx_make_map((struct ext4_dir_entry_2 *) data1,

  			     blocksize, hinfo, map);
  	map -= count;

  	dx_sort_map(map, count);

  	/* Split the existing block in the middle, size-wise */
  	size = 0;
  	move = 0;
  	for (i = count-1; i >= 0; i--) {
  		/* is more than half of this entry in 2nd half of the block? */
  		if (size + map[i].size/2 > blocksize/2)
  			break;
  		size += map[i].size;
  		move++;
  	}
  	/* map index at which we will split */
  	split = count - move;

  	hash2 = map[split].hash;
  	continued = hash2 == map[split - 1].hash;

  	dxtrace(printk(KERN_INFO "Split block %lu at %x, %i/%i
  ",
  			(unsigned long)dx_get_block(frame->at),
  					hash2, split, count-split));

  
  	/* Fancy dance to stay within two buffers */

  	de2 = dx_move_dirents(data1, data2, map + split, count - split, blocksize);

  	de = dx_pack_dirents(data1, blocksize);

  	de->rec_len = ext4_rec_len_to_disk(data1 + blocksize - (char *) de,
  					   blocksize);
  	de2->rec_len = ext4_rec_len_to_disk(data2 + blocksize - (char *) de2,
  					    blocksize);

  	dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data1, blocksize, 1));
  	dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data2, blocksize, 1));

  
  	/* Which block gets the new entry? */
  	if (hinfo->hash >= hash2)
  	{
  		swap(*bh, bh2);
  		de = de2;
  	}

  	dx_insert_block(frame, hash2 + continued, newblock);

  	err = ext4_handle_dirty_metadata(handle, dir, bh2);

  	if (err)
  		goto journal_error;

  	err = ext4_handle_dirty_metadata(handle, dir, frame->bh);

  	if (err)
  		goto journal_error;

  	brelse(bh2);
  	dxtrace(dx_show_index("frame", frame->entries));

  	return de;

  
  journal_error:
  	brelse(*bh);
  	brelse(bh2);
  	*bh = NULL;
  	ext4_std_error(dir->i_sb, err);
  errout:
  	*error = err;
  	return NULL;

  }

  
  /*
   * Add a new entry into a directory (leaf) block.  If de is non-NULL,
   * it points to a directory entry which is guaranteed to be large
   * enough for new directory entry.  If de is NULL, then
   * add_dirent_to_buf will attempt search the directory block for
   * space.  It will return -ENOSPC if no space is available, and -EIO
   * and -EEXIST if directory entry already exists.

   */
  static int add_dirent_to_buf(handle_t *handle, struct dentry *dentry,

  			     struct inode *inode, struct ext4_dir_entry_2 *de,

  			     struct buffer_head *bh)

  {
  	struct inode	*dir = dentry->d_parent->d_inode;
  	const char	*name = dentry->d_name.name;
  	int		namelen = dentry->d_name.len;

  	unsigned int	offset = 0;

  	unsigned int	blocksize = dir->i_sb->s_blocksize;

  	unsigned short	reclen;
  	int		nlen, rlen, err;
  	char		*top;

  	reclen = EXT4_DIR_REC_LEN(namelen);

  	if (!de) {

  		de = (struct ext4_dir_entry_2 *)bh->b_data;

  		top = bh->b_data + blocksize - reclen;

  		while ((char *) de <= top) {

  			if (ext4_check_dir_entry(dir, NULL, de, bh, offset))

  				return -EIO;

  			if (ext4_match(namelen, name, de))

  				return -EEXIST;

  			nlen = EXT4_DIR_REC_LEN(de->name_len);

  			rlen = ext4_rec_len_from_disk(de->rec_len, blocksize);

  			if ((de->inode? rlen - nlen: rlen) >= reclen)
  				break;

  			de = (struct ext4_dir_entry_2 *)((char *)de + rlen);

  			offset += rlen;
  		}
  		if ((char *) de > top)
  			return -ENOSPC;
  	}
  	BUFFER_TRACE(bh, "get_write_access");

  	err = ext4_journal_get_write_access(handle, bh);

  	if (err) {

  		ext4_std_error(dir->i_sb, err);

  		return err;
  	}
  
  	/* By now the buffer is marked for journaling */

  	nlen = EXT4_DIR_REC_LEN(de->name_len);

  	rlen = ext4_rec_len_from_disk(de->rec_len, blocksize);

  	if (de->inode) {

  		struct ext4_dir_entry_2 *de1 = (struct ext4_dir_entry_2 *)((char *)de + nlen);

  		de1->rec_len = ext4_rec_len_to_disk(rlen - nlen, blocksize);
  		de->rec_len = ext4_rec_len_to_disk(nlen, blocksize);

  		de = de1;
  	}

  	de->file_type = EXT4_FT_UNKNOWN;

  	if (inode) {
  		de->inode = cpu_to_le32(inode->i_ino);

  		ext4_set_de_type(dir->i_sb, de, inode->i_mode);

  	} else
  		de->inode = 0;
  	de->name_len = namelen;

  	memcpy(de->name, name, namelen);

  	/*
  	 * XXX shouldn't update any times until successful
  	 * completion of syscall, but too many callers depend
  	 * on this.
  	 *
  	 * XXX similarly, too many callers depend on

  	 * ext4_new_inode() setting the times, but error

  	 * recovery deletes the inode, so the worst that can
  	 * happen is that the times are slightly out of date
  	 * and/or different from the directory change time.
  	 */

  	dir->i_mtime = dir->i_ctime = ext4_current_time(dir);

  	ext4_update_dx_flag(dir);

  	dir->i_version++;

  	ext4_mark_inode_dirty(handle, dir);

  	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
  	err = ext4_handle_dirty_metadata(handle, dir, bh);

  	if (err)

  		ext4_std_error(dir->i_sb, err);

  	return 0;
  }

  /*
   * This converts a one block unindexed directory to a 3 block indexed
   * directory, and adds the dentry to the indexed directory.
   */
  static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
  			    struct inode *inode, struct buffer_head *bh)
  {
  	struct inode	*dir = dentry->d_parent->d_inode;
  	const char	*name = dentry->d_name.name;
  	int		namelen = dentry->d_name.len;
  	struct buffer_head *bh2;
  	struct dx_root	*root;
  	struct dx_frame	frames[2], *frame;
  	struct dx_entry *entries;

  	struct ext4_dir_entry_2	*de, *de2;

  	char		*data1, *top;
  	unsigned	len;
  	int		retval;
  	unsigned	blocksize;
  	struct dx_hash_info hinfo;

  	ext4_lblk_t  block;

  	struct fake_dirent *fde;
  
  	blocksize =  dir->i_sb->s_blocksize;

  	dxtrace(printk(KERN_DEBUG "Creating index: inode %lu
  ", dir->i_ino));

  	retval = ext4_journal_get_write_access(handle, bh);

  	if (retval) {

  		ext4_std_error(dir->i_sb, retval);

  		brelse(bh);
  		return retval;
  	}
  	root = (struct dx_root *) bh->b_data;

  	/* The 0th block becomes the root, move the dirents out */
  	fde = &root->dotdot;
  	de = (struct ext4_dir_entry_2 *)((char *)fde +

  		ext4_rec_len_from_disk(fde->rec_len, blocksize));

  	if ((char *) de >= (((char *) root) + blocksize)) {

  		EXT4_ERROR_INODE(dir, "invalid rec_len for '..'");

  		brelse(bh);
  		return -EIO;
  	}
  	len = ((char *) root) + blocksize - (char *) de;
  
  	/* Allocate new block for the 0th block's dirents */

  	bh2 = ext4_append(handle, dir, &block, &retval);

  	if (!(bh2)) {
  		brelse(bh);
  		return retval;
  	}

  	ext4_set_inode_flag(dir, EXT4_INODE_INDEX);

  	data1 = bh2->b_data;

  	memcpy (data1, de, len);

  	de = (struct ext4_dir_entry_2 *) data1;

  	top = data1 + len;

  	while ((char *)(de2 = ext4_next_entry(de, blocksize)) < top)

  		de = de2;

  	de->rec_len = ext4_rec_len_to_disk(data1 + blocksize - (char *) de,
  					   blocksize);

  	/* Initialize the root; the dot dirents already exist */

  	de = (struct ext4_dir_entry_2 *) (&root->dotdot);

  	de->rec_len = ext4_rec_len_to_disk(blocksize - EXT4_DIR_REC_LEN(2),
  					   blocksize);

  	memset (&root->info, 0, sizeof(root->info));
  	root->info.info_length = sizeof(root->info);

  	root->info.hash_version = EXT4_SB(dir->i_sb)->s_def_hash_version;

  	entries = root->entries;

  	dx_set_block(entries, 1);
  	dx_set_count(entries, 1);
  	dx_set_limit(entries, dx_root_limit(dir, sizeof(root->info)));

  
  	/* Initialize as for dx_probe */
  	hinfo.hash_version = root->info.hash_version;

  	if (hinfo.hash_version <= DX_HASH_TEA)
  		hinfo.hash_version += EXT4_SB(dir->i_sb)->s_hash_unsigned;

  	hinfo.seed = EXT4_SB(dir->i_sb)->s_hash_seed;
  	ext4fs_dirhash(name, namelen, &hinfo);

  	frame = frames;
  	frame->entries = entries;
  	frame->at = entries;
  	frame->bh = bh;
  	bh = bh2;

  
  	ext4_handle_dirty_metadata(handle, dir, frame->bh);
  	ext4_handle_dirty_metadata(handle, dir, bh);

  	de = do_split(handle,dir, &bh, frame, &hinfo, &retval);

  	if (!de) {
  		/*
  		 * Even if the block split failed, we have to properly write
  		 * out all the changes we did so far. Otherwise we can end up
  		 * with corrupted filesystem.
  		 */
  		ext4_mark_inode_dirty(handle, dir);

  		dx_release(frames);

  		return retval;

  	}
  	dx_release(frames);

  	retval = add_dirent_to_buf(handle, dentry, inode, de, bh);
  	brelse(bh);
  	return retval;

  }

  
  /*

   *	ext4_add_entry()

   *
   * adds a file entry to the specified directory, using the same

   * semantics as ext4_find_entry(). It returns NULL if it failed.

   *
   * NOTE!! The inode part of 'de' is left at 0 - which means you
   * may not sleep between calling this and putting something into
   * the entry, as someone else might have used it while you slept.
   */

  static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
  			  struct inode *inode)

  {
  	struct inode *dir = dentry->d_parent->d_inode;

  	struct buffer_head *bh;

  	struct ext4_dir_entry_2 *de;

  	struct super_block *sb;

  	int	retval;

  	int	dx_fallback=0;

  	unsigned blocksize;

  	ext4_lblk_t block, blocks;

  
  	sb = dir->i_sb;
  	blocksize = sb->s_blocksize;
  	if (!dentry->d_name.len)
  		return -EINVAL;

  	if (is_dx(dir)) {

  		retval = ext4_dx_add_entry(handle, dentry, inode);

  		if (!retval || (retval != ERR_BAD_DX_DIR))
  			return retval;

  		ext4_clear_inode_flag(dir, EXT4_INODE_INDEX);

  		dx_fallback++;

  		ext4_mark_inode_dirty(handle, dir);

  	}

  	blocks = dir->i_size >> sb->s_blocksize_bits;

  	for (block = 0; block < blocks; block++) {

  		bh = ext4_bread(handle, dir, block, 0, &retval);

  		if(!bh)
  			return retval;
  		retval = add_dirent_to_buf(handle, dentry, inode, NULL, bh);

  		if (retval != -ENOSPC) {
  			brelse(bh);

  			return retval;

  		}

  		if (blocks == 1 && !dx_fallback &&

  		    EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_DIR_INDEX))
  			return make_indexed_dir(handle, dentry, inode, bh);

  		brelse(bh);
  	}

  	bh = ext4_append(handle, dir, &block, &retval);

  	if (!bh)
  		return retval;

  	de = (struct ext4_dir_entry_2 *) bh->b_data;

  	de->inode = 0;

  	de->rec_len = ext4_rec_len_to_disk(blocksize, blocksize);

  	retval = add_dirent_to_buf(handle, dentry, inode, de, bh);
  	brelse(bh);

  	if (retval == 0)
  		ext4_set_inode_state(inode, EXT4_STATE_NEWENTRY);

  	return retval;

  }

  /*
   * Returns 0 for success, or a negative error value
   */

  static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,

  			     struct inode *inode)
  {
  	struct dx_frame frames[2], *frame;
  	struct dx_entry *entries, *at;
  	struct dx_hash_info hinfo;

  	struct buffer_head *bh;

  	struct inode *dir = dentry->d_parent->d_inode;

  	struct super_block *sb = dir->i_sb;

  	struct ext4_dir_entry_2 *de;

  	int err;

  	frame = dx_probe(&dentry->d_name, dir, &hinfo, frames, &err);

  	if (!frame)
  		return err;
  	entries = frame->entries;
  	at = frame->at;

  	if (!(bh = ext4_bread(handle,dir, dx_get_block(frame->at), 0, &err)))

  		goto cleanup;
  
  	BUFFER_TRACE(bh, "get_write_access");

  	err = ext4_journal_get_write_access(handle, bh);

  	if (err)
  		goto journal_error;
  
  	err = add_dirent_to_buf(handle, dentry, inode, NULL, bh);

  	if (err != -ENOSPC)

  		goto cleanup;

  
  	/* Block full, should compress but for now just split */

  	dxtrace(printk(KERN_DEBUG "using %u of %u node entries
  ",

  		       dx_get_count(entries), dx_get_limit(entries)));
  	/* Need to split index? */
  	if (dx_get_count(entries) == dx_get_limit(entries)) {

  		ext4_lblk_t newblock;

  		unsigned icount = dx_get_count(entries);
  		int levels = frame - frames;
  		struct dx_entry *entries2;
  		struct dx_node *node2;
  		struct buffer_head *bh2;
  
  		if (levels && (dx_get_count(frames->entries) ==
  			       dx_get_limit(frames->entries))) {

  			ext4_warning(sb, "Directory index full!");

  			err = -ENOSPC;
  			goto cleanup;
  		}

  		bh2 = ext4_append (handle, dir, &newblock, &err);

  		if (!(bh2))
  			goto cleanup;
  		node2 = (struct dx_node *)(bh2->b_data);
  		entries2 = node2->entries;

  		memset(&node2->fake, 0, sizeof(struct fake_dirent));

  		node2->fake.rec_len = ext4_rec_len_to_disk(sb->s_blocksize,
  							   sb->s_blocksize);

  		BUFFER_TRACE(frame->bh, "get_write_access");

  		err = ext4_journal_get_write_access(handle, frame->bh);

  		if (err)
  			goto journal_error;
  		if (levels) {
  			unsigned icount1 = icount/2, icount2 = icount - icount1;
  			unsigned hash2 = dx_get_hash(entries + icount1);

  			dxtrace(printk(KERN_DEBUG "Split index %i/%i
  ",
  				       icount1, icount2));

  
  			BUFFER_TRACE(frame->bh, "get_write_access"); /* index root */

  			err = ext4_journal_get_write_access(handle,

  							     frames[0].bh);
  			if (err)
  				goto journal_error;

  			memcpy((char *) entries2, (char *) (entries + icount1),
  			       icount2 * sizeof(struct dx_entry));
  			dx_set_count(entries, icount1);
  			dx_set_count(entries2, icount2);
  			dx_set_limit(entries2, dx_node_limit(dir));

  
  			/* Which index block gets the new entry? */
  			if (at - entries >= icount1) {
  				frame->at = at = at - entries - icount1 + entries2;
  				frame->entries = entries = entries2;
  				swap(frame->bh, bh2);
  			}

  			dx_insert_block(frames + 0, hash2, newblock);
  			dxtrace(dx_show_index("node", frames[1].entries));
  			dxtrace(dx_show_index("node",

  			       ((struct dx_node *) bh2->b_data)->entries));

  			err = ext4_handle_dirty_metadata(handle, dir, bh2);

  			if (err)
  				goto journal_error;
  			brelse (bh2);
  		} else {

  			dxtrace(printk(KERN_DEBUG
  				       "Creating second level index...
  "));

  			memcpy((char *) entries2, (char *) entries,
  			       icount * sizeof(struct dx_entry));
  			dx_set_limit(entries2, dx_node_limit(dir));
  
  			/* Set up root */
  			dx_set_count(entries, 1);
  			dx_set_block(entries + 0, newblock);
  			((struct dx_root *) frames[0].bh->b_data)->info.indirect_levels = 1;
  
  			/* Add new access path frame */
  			frame = frames + 1;
  			frame->at = at = at - entries + entries2;
  			frame->entries = entries = entries2;
  			frame->bh = bh2;

  			err = ext4_journal_get_write_access(handle,

  							     frame->bh);
  			if (err)
  				goto journal_error;
  		}

  		err = ext4_handle_dirty_metadata(handle, dir, frames[0].bh);

  		if (err) {
  			ext4_std_error(inode->i_sb, err);
  			goto cleanup;
  		}

  	}
  	de = do_split(handle, dir, &bh, frame, &hinfo, &err);
  	if (!de)
  		goto cleanup;
  	err = add_dirent_to_buf(handle, dentry, inode, de, bh);

  	goto cleanup;
  
  journal_error:

  	ext4_std_error(dir->i_sb, err);

  cleanup:
  	if (bh)
  		brelse(bh);
  	dx_release(frames);
  	return err;
  }

  
  /*

   * ext4_delete_entry deletes a directory entry by merging it with the

   * previous entry
   */

  static int ext4_delete_entry(handle_t *handle,
  			     struct inode *dir,
  			     struct ext4_dir_entry_2 *de_del,
  			     struct buffer_head *bh)

  {

  	struct ext4_dir_entry_2 *de, *pde;

  	unsigned int blocksize = dir->i_sb->s_blocksize;

  	int i, err;

  
  	i = 0;
  	pde = NULL;

  	de = (struct ext4_dir_entry_2 *) bh->b_data;

  	while (i < bh->b_size) {

  		if (ext4_check_dir_entry(dir, NULL, de, bh, i))

  			return -EIO;
  		if (de == de_del)  {
  			BUFFER_TRACE(bh, "get_write_access");

  			err = ext4_journal_get_write_access(handle, bh);
  			if (unlikely(err)) {
  				ext4_std_error(dir->i_sb, err);
  				return err;
  			}

  			if (pde)

  				pde->rec_len = ext4_rec_len_to_disk(

  					ext4_rec_len_from_disk(pde->rec_len,
  							       blocksize) +
  					ext4_rec_len_from_disk(de->rec_len,
  							       blocksize),
  					blocksize);

  			else
  				de->inode = 0;
  			dir->i_version++;

  			BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");

  			err = ext4_handle_dirty_metadata(handle, dir, bh);
  			if (unlikely(err)) {
  				ext4_std_error(dir->i_sb, err);
  				return err;
  			}

  			return 0;
  		}

  		i += ext4_rec_len_from_disk(de->rec_len, blocksize);

  		pde = de;

  		de = ext4_next_entry(de, blocksize);

  	}
  	return -ENOENT;
  }

  /*
   * DIR_NLINK feature is set if 1) nlinks > EXT4_LINK_MAX or 2) nlinks == 2,
   * since this indicates that nlinks count was previously 1.
   */
  static void ext4_inc_count(handle_t *handle, struct inode *inode)
  {
  	inc_nlink(inode);
  	if (is_dx(inode) && inode->i_nlink > 1) {
  		/* limit is 16-bit i_links_count */
  		if (inode->i_nlink >= EXT4_LINK_MAX || inode->i_nlink == 2) {

  			set_nlink(inode, 1);

  			EXT4_SET_RO_COMPAT_FEATURE(inode->i_sb,
  					      EXT4_FEATURE_RO_COMPAT_DIR_NLINK);
  		}
  	}
  }
  
  /*
   * If a directory had nlink == 1, then we should let it be 1. This indicates
   * directory has >EXT4_LINK_MAX subdirs.
   */
  static void ext4_dec_count(handle_t *handle, struct inode *inode)
  {

  	if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
  		drop_nlink(inode);

  }

  static int ext4_add_nondir(handle_t *handle,

  		struct dentry *dentry, struct inode *inode)
  {

  	int err = ext4_add_entry(handle, dentry, inode);

  	if (!err) {

  		ext4_mark_inode_dirty(handle, inode);

  		d_instantiate(dentry, inode);

  		unlock_new_inode(inode);

  		return 0;
  	}

  	drop_nlink(inode);

  	unlock_new_inode(inode);

  	iput(inode);
  	return err;
  }
  
  /*
   * By the time this is called, we already have created
   * the directory cache entry for the new file, but it
   * is so far negative - it has no inode.
   *
   * If the create succeeds, we fill in the inode information
   * with d_instantiate().
   */

  static int ext4_create(struct inode *dir, struct dentry *dentry, umode_t mode,

  		       struct nameidata *nd)

  {
  	handle_t *handle;

  	struct inode *inode;

  	int err, retries = 0;

  	dquot_initialize(dir);

  retry:

  	handle = ext4_journal_start(dir, EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
  					EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +

  					EXT4_MAXQUOTAS_INIT_BLOCKS(dir->i_sb));

  	if (IS_ERR(handle))
  		return PTR_ERR(handle);
  
  	if (IS_DIRSYNC(dir))

  		ext4_handle_sync(handle);

  	inode = ext4_new_inode(handle, dir, mode, &dentry->d_name, 0, NULL);

  	err = PTR_ERR(inode);
  	if (!IS_ERR(inode)) {

  		inode->i_op = &ext4_file_inode_operations;
  		inode->i_fop = &ext4_file_operations;
  		ext4_set_aops(inode);
  		err = ext4_add_nondir(handle, dentry, inode);

  	}

  	ext4_journal_stop(handle);
  	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))

  		goto retry;
  	return err;
  }

  static int ext4_mknod(struct inode *dir, struct dentry *dentry,