/*

   *  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/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)

  static struct buffer_head *ext4_append(handle_t *handle,

  					struct inode *inode,

  					ext4_lblk_t *block)

  {
  	struct buffer_head *bh;

  	int err;

  	if (unlikely(EXT4_SB(inode->i_sb)->s_max_dir_size_kb &&
  		     ((inode->i_size >> 10) >=

  		      EXT4_SB(inode->i_sb)->s_max_dir_size_kb)))
  		return ERR_PTR(-ENOSPC);

  	*block = inode->i_size >> inode->i_sb->s_blocksize_bits;

  	bh = ext4_bread(handle, inode, *block, EXT4_GET_BLOCKS_CREATE);

  	if (IS_ERR(bh))
  		return bh;

  	inode->i_size += inode->i_sb->s_blocksize;
  	EXT4_I(inode)->i_disksize = inode->i_size;

  	BUFFER_TRACE(bh, "get_write_access");

  	err = ext4_journal_get_write_access(handle, bh);
  	if (err) {
  		brelse(bh);
  		ext4_std_error(inode->i_sb, err);
  		return ERR_PTR(err);

  	}

  	return bh;
  }

  static int ext4_dx_csum_verify(struct inode *inode,
  			       struct ext4_dir_entry *dirent);
  
  typedef enum {
  	EITHER, INDEX, DIRENT
  } dirblock_type_t;
  
  #define ext4_read_dirblock(inode, block, type) \

  	__ext4_read_dirblock((inode), (block), (type), __func__, __LINE__)

  
  static struct buffer_head *__ext4_read_dirblock(struct inode *inode,

  						ext4_lblk_t block,
  						dirblock_type_t type,
  						const char *func,
  						unsigned int line)

  {
  	struct buffer_head *bh;
  	struct ext4_dir_entry *dirent;

  	int is_dx_block = 0;

  	bh = ext4_bread(NULL, inode, block, 0);
  	if (IS_ERR(bh)) {

  		__ext4_warning(inode->i_sb, func, line,
  			       "inode #%lu: lblock %lu: comm %s: "
  			       "error %ld reading directory block",
  			       inode->i_ino, (unsigned long)block,
  			       current->comm, PTR_ERR(bh));

  
  		return bh;
  	}
  	if (!bh) {

  		ext4_error_inode(inode, func, line, block,
  				 "Directory hole found");

  		return ERR_PTR(-EFSCORRUPTED);

  	}
  	dirent = (struct ext4_dir_entry *) bh->b_data;
  	/* Determine whether or not we have an index block */
  	if (is_dx(inode)) {
  		if (block == 0)
  			is_dx_block = 1;
  		else if (ext4_rec_len_from_disk(dirent->rec_len,
  						inode->i_sb->s_blocksize) ==
  			 inode->i_sb->s_blocksize)
  			is_dx_block = 1;
  	}
  	if (!is_dx_block && type == INDEX) {

  		ext4_error_inode(inode, func, line, block,

  		       "directory leaf block found instead of index block");

  		return ERR_PTR(-EFSCORRUPTED);

  	}

  	if (!ext4_has_metadata_csum(inode->i_sb) ||

  	    buffer_verified(bh))
  		return bh;
  
  	/*
  	 * An empty leaf block can get mistaken for a index block; for
  	 * this reason, we can only check the index checksum when the
  	 * caller is sure it should be an index block.
  	 */
  	if (is_dx_block && type == INDEX) {
  		if (ext4_dx_csum_verify(inode, dirent))
  			set_buffer_verified(bh);
  		else {

  			ext4_error_inode(inode, func, line, block,
  					 "Directory index failed checksum");

  			brelse(bh);

  			return ERR_PTR(-EFSBADCRC);

  		}

  	}

  	if (!is_dx_block) {
  		if (ext4_dirent_csum_verify(inode, dirent))
  			set_buffer_verified(bh);
  		else {

  			ext4_error_inode(inode, func, line, block,
  					 "Directory block failed checksum");

  			brelse(bh);

  			return ERR_PTR(-EFSBADCRC);

  		}

  	}

  	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;

  };

  /*
   * This goes at the end of each htree block.
   */
  struct dx_tail {
  	u32 dt_reserved;
  	__le32 dt_checksum;	/* crc32c(uuid+inum+dirblock) */
  };

  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(struct ext4_filename *fname,

  				 struct inode *dir,
  				 struct dx_hash_info *hinfo,

  				 struct dx_frame *frame);

  static void dx_release(struct dx_frame *frames);

  static int dx_make_map(struct inode *dir, 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,

  		struct ext4_filename *fname,

  		struct ext4_dir_entry_2 **res_dir);

  static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,

  			     struct inode *dir, struct inode *inode);

  /* checksumming functions */

  void initialize_dirent_tail(struct ext4_dir_entry_tail *t,
  			    unsigned int blocksize)

  {
  	memset(t, 0, sizeof(struct ext4_dir_entry_tail));
  	t->det_rec_len = ext4_rec_len_to_disk(
  			sizeof(struct ext4_dir_entry_tail), blocksize);
  	t->det_reserved_ft = EXT4_FT_DIR_CSUM;
  }
  
  /* Walk through a dirent block to find a checksum "dirent" at the tail */
  static struct ext4_dir_entry_tail *get_dirent_tail(struct inode *inode,
  						   struct ext4_dir_entry *de)
  {
  	struct ext4_dir_entry_tail *t;
  
  #ifdef PARANOID
  	struct ext4_dir_entry *d, *top;
  
  	d = de;
  	top = (struct ext4_dir_entry *)(((void *)de) +
  		(EXT4_BLOCK_SIZE(inode->i_sb) -
  		sizeof(struct ext4_dir_entry_tail)));
  	while (d < top && d->rec_len)
  		d = (struct ext4_dir_entry *)(((void *)d) +
  		    le16_to_cpu(d->rec_len));
  
  	if (d != top)
  		return NULL;
  
  	t = (struct ext4_dir_entry_tail *)d;
  #else
  	t = EXT4_DIRENT_TAIL(de, EXT4_BLOCK_SIZE(inode->i_sb));
  #endif
  
  	if (t->det_reserved_zero1 ||
  	    le16_to_cpu(t->det_rec_len) != sizeof(struct ext4_dir_entry_tail) ||
  	    t->det_reserved_zero2 ||
  	    t->det_reserved_ft != EXT4_FT_DIR_CSUM)
  		return NULL;
  
  	return t;
  }
  
  static __le32 ext4_dirent_csum(struct inode *inode,
  			       struct ext4_dir_entry *dirent, int size)
  {
  	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
  	struct ext4_inode_info *ei = EXT4_I(inode);
  	__u32 csum;
  
  	csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)dirent, size);
  	return cpu_to_le32(csum);
  }

  #define warn_no_space_for_csum(inode)					\
  	__warn_no_space_for_csum((inode), __func__, __LINE__)
  
  static void __warn_no_space_for_csum(struct inode *inode, const char *func,
  				     unsigned int line)

  {

  	__ext4_warning_inode(inode, func, line,
  		"No space for directory leaf checksum. Please run e2fsck -D.");

  }

  int ext4_dirent_csum_verify(struct inode *inode, struct ext4_dir_entry *dirent)
  {
  	struct ext4_dir_entry_tail *t;

  	if (!ext4_has_metadata_csum(inode->i_sb))

  		return 1;
  
  	t = get_dirent_tail(inode, dirent);
  	if (!t) {

  		warn_no_space_for_csum(inode);

  		return 0;
  	}
  
  	if (t->det_checksum != ext4_dirent_csum(inode, dirent,
  						(void *)t - (void *)dirent))
  		return 0;
  
  	return 1;
  }
  
  static void ext4_dirent_csum_set(struct inode *inode,
  				 struct ext4_dir_entry *dirent)
  {
  	struct ext4_dir_entry_tail *t;

  	if (!ext4_has_metadata_csum(inode->i_sb))

  		return;
  
  	t = get_dirent_tail(inode, dirent);
  	if (!t) {

  		warn_no_space_for_csum(inode);

  		return;
  	}
  
  	t->det_checksum = ext4_dirent_csum(inode, dirent,
  					   (void *)t - (void *)dirent);
  }

  int ext4_handle_dirty_dirent_node(handle_t *handle,
  				  struct inode *inode,
  				  struct buffer_head *bh)

  {
  	ext4_dirent_csum_set(inode, (struct ext4_dir_entry *)bh->b_data);
  	return ext4_handle_dirty_metadata(handle, inode, bh);
  }

  static struct dx_countlimit *get_dx_countlimit(struct inode *inode,
  					       struct ext4_dir_entry *dirent,
  					       int *offset)
  {
  	struct ext4_dir_entry *dp;
  	struct dx_root_info *root;
  	int count_offset;
  
  	if (le16_to_cpu(dirent->rec_len) == EXT4_BLOCK_SIZE(inode->i_sb))
  		count_offset = 8;
  	else if (le16_to_cpu(dirent->rec_len) == 12) {
  		dp = (struct ext4_dir_entry *)(((void *)dirent) + 12);
  		if (le16_to_cpu(dp->rec_len) !=
  		    EXT4_BLOCK_SIZE(inode->i_sb) - 12)
  			return NULL;
  		root = (struct dx_root_info *)(((void *)dp + 12));
  		if (root->reserved_zero ||
  		    root->info_length != sizeof(struct dx_root_info))
  			return NULL;
  		count_offset = 32;
  	} else
  		return NULL;
  
  	if (offset)
  		*offset = count_offset;
  	return (struct dx_countlimit *)(((void *)dirent) + count_offset);
  }
  
  static __le32 ext4_dx_csum(struct inode *inode, struct ext4_dir_entry *dirent,
  			   int count_offset, int count, struct dx_tail *t)
  {
  	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
  	struct ext4_inode_info *ei = EXT4_I(inode);

  	__u32 csum;

  	int size;

  	__u32 dummy_csum = 0;
  	int offset = offsetof(struct dx_tail, dt_checksum);

  
  	size = count_offset + (count * sizeof(struct dx_entry));

  	csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)dirent, size);

  	csum = ext4_chksum(sbi, csum, (__u8 *)t, offset);
  	csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));

  
  	return cpu_to_le32(csum);
  }
  
  static int ext4_dx_csum_verify(struct inode *inode,
  			       struct ext4_dir_entry *dirent)
  {
  	struct dx_countlimit *c;
  	struct dx_tail *t;
  	int count_offset, limit, count;

  	if (!ext4_has_metadata_csum(inode->i_sb))

  		return 1;
  
  	c = get_dx_countlimit(inode, dirent, &count_offset);
  	if (!c) {
  		EXT4_ERROR_INODE(inode, "dir seems corrupt?  Run e2fsck -D.");

  		return 0;

  	}
  	limit = le16_to_cpu(c->limit);
  	count = le16_to_cpu(c->count);
  	if (count_offset + (limit * sizeof(struct dx_entry)) >
  	    EXT4_BLOCK_SIZE(inode->i_sb) - sizeof(struct dx_tail)) {

  		warn_no_space_for_csum(inode);

  		return 0;

  	}
  	t = (struct dx_tail *)(((struct dx_entry *)c) + limit);
  
  	if (t->dt_checksum != ext4_dx_csum(inode, dirent, count_offset,
  					    count, t))
  		return 0;
  	return 1;
  }
  
  static void ext4_dx_csum_set(struct inode *inode, struct ext4_dir_entry *dirent)
  {
  	struct dx_countlimit *c;
  	struct dx_tail *t;
  	int count_offset, limit, count;

  	if (!ext4_has_metadata_csum(inode->i_sb))

  		return;
  
  	c = get_dx_countlimit(inode, dirent, &count_offset);
  	if (!c) {
  		EXT4_ERROR_INODE(inode, "dir seems corrupt?  Run e2fsck -D.");
  		return;
  	}
  	limit = le16_to_cpu(c->limit);
  	count = le16_to_cpu(c->count);
  	if (count_offset + (limit * sizeof(struct dx_entry)) >
  	    EXT4_BLOCK_SIZE(inode->i_sb) - sizeof(struct dx_tail)) {

  		warn_no_space_for_csum(inode);

  		return;
  	}
  	t = (struct dx_tail *)(((struct dx_entry *)c) + limit);
  
  	t->dt_checksum = ext4_dx_csum(inode, dirent, count_offset, count, t);
  }
  
  static inline int ext4_handle_dirty_dx_node(handle_t *handle,
  					    struct inode *inode,
  					    struct buffer_head *bh)
  {
  	ext4_dx_csum_set(inode, (struct ext4_dir_entry *)bh->b_data);
  	return ext4_handle_dirty_metadata(handle, inode, bh);
  }

  /*

   * 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;

  	if (ext4_has_metadata_csum(dir->i_sb))

  		entry_space -= sizeof(struct dx_tail);

  	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);

  	if (ext4_has_metadata_csum(dir->i_sb))

  		entry_space -= sizeof(struct dx_tail);

  	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(KERN_CONT " %x->%lu",
  		       i ? dx_get_hash(entries + i) : 0,
  		       (unsigned long)dx_get_block(entries + i));

  	}

  	printk(KERN_CONT "
  ");

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

  static struct stats dx_show_leaf(struct inode *dir,
  				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)
  			{

  #ifdef CONFIG_EXT4_FS_ENCRYPTION
  				int len;
  				char *name;

  				struct fscrypt_str fname_crypto_str =
  					FSTR_INIT(NULL, 0);

  				int res = 0;

  
  				name  = de->name;
  				len = de->name_len;

  				if (ext4_encrypted_inode(dir))
  					res = fscrypt_get_encryption_info(dir);

  				if (res) {
  					printk(KERN_WARNING "Error setting up"
  					       " fname crypto: %d
  ", res);

  				}

  				if (!fscrypt_has_encryption_key(dir)) {

  					/* Directory is not encrypted */
  					ext4fs_dirhash(de->name,
  						de->name_len, &h);
  					printk("%*.s:(U)%x.%u ", len,
  					       name, h.hash,
  					       (unsigned) ((char *) de
  							   - base));
  				} else {

  					struct fscrypt_str de_name =
  						FSTR_INIT(name, len);

  					/* Directory is encrypted */

  					res = fscrypt_fname_alloc_buffer(
  						dir, len,

  						&fname_crypto_str);

  					if (res)

  						printk(KERN_WARNING "Error "
  							"allocating crypto "
  							"buffer--skipping "
  							"crypto
  ");

  					res = fscrypt_fname_disk_to_usr(dir,
  						0, 0, &de_name,
  						&fname_crypto_str);

  					if (res) {

  						printk(KERN_WARNING "Error "
  							"converting filename "
  							"from disk to usr"
  							"
  ");
  						name = "??";
  						len = 2;
  					} else {
  						name = fname_crypto_str.name;
  						len = fname_crypto_str.len;
  					}

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

  					printk("%*.s:(E)%x.%u ", len, name,
  					       h.hash, (unsigned) ((char *) de
  								   - base));

  					fscrypt_fname_free_buffer(
  							&fname_crypto_str);

  				}
  #else

  				int len = de->name_len;
  				char *name = de->name;

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

  				printk("%*.s:%x.%u ", len, name, h.hash,

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

  #endif

  			}

  			space += EXT4_DIR_REC_LEN(de->name_len);

  			names++;
  		}

  		de = ext4_next_entry(de, size);

  	}

  	printk(KERN_CONT "(%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;

  	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);

  		bh = ext4_bread(NULL,dir, block, 0);
  		if (!bh || IS_ERR(bh))
  			continue;

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

  		   dx_show_leaf(dir, 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(struct ext4_filename *fname, struct inode *dir,

  	 struct dx_hash_info *hinfo, struct dx_frame *frame_in)

  {
  	unsigned count, indirect;
  	struct dx_entry *at, *entries, *p, *q, *m;
  	struct dx_root *root;

  	struct dx_frame *frame = frame_in;

  	struct dx_frame *ret_err = ERR_PTR(ERR_BAD_DX_DIR);

  	u32 hash;

  	frame->bh = ext4_read_dirblock(dir, 0, INDEX);
  	if (IS_ERR(frame->bh))
  		return (struct dx_frame *) frame->bh;
  
  	root = (struct dx_root *) frame->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_inode(dir, "Unrecognised inode hash code %u",
  				   root->info.hash_version);

  		goto fail;
  	}

  	if (fname)
  		hinfo = &fname->hinfo;

  	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 (fname && fname_name(fname))
  		ext4fs_dirhash(fname_name(fname), fname_len(fname), hinfo);

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

  		ext4_warning_inode(dir, "Unimplemented hash flags: %#06x",
  				   root->info.unused_flags);

  		goto fail;
  	}

  	indirect = root->info.indirect_levels;
  	if (indirect > 1) {
  		ext4_warning_inode(dir, "Unimplemented hash depth: %#06x",
  				   root->info.indirect_levels);

  		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_inode(dir, "dx entry: limit %u != root limit %u",
  				   dx_get_limit(entries),
  				   dx_root_limit(dir, root->info.info_length));

  		goto fail;
  	}

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

  	while (1) {

  		count = dx_get_count(entries);

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

  			ext4_warning_inode(dir,
  					   "dx entry: count %u beyond limit %u",
  					   count, dx_get_limit(entries));

  			goto fail;

  		}

  		p = entries + 1;
  		q = entries + count - 1;

  		while (p <= q) {

  			m = p + (q - p) / 2;

  			dxtrace(printk(KERN_CONT "."));

  			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(KERN_CONT ","));

  				if (dx_get_hash(++at) > hash)
  				{
  					at--;
  					break;
  				}
  			}
  			assert (at == p - 1);
  		}
  
  		at = p - 1;

  		dxtrace(printk(KERN_CONT " %x->%u
  ",
  			       at == entries ? 0 : dx_get_hash(at),

  			       dx_get_block(at)));

  		frame->entries = entries;
  		frame->at = at;

  		if (!indirect--)
  			return frame;
  		frame++;
  		frame->bh = ext4_read_dirblock(dir, dx_get_block(at), INDEX);
  		if (IS_ERR(frame->bh)) {
  			ret_err = (struct dx_frame *) frame->bh;
  			frame->bh = NULL;
  			goto fail;

  		}

  		entries = ((struct dx_node *) frame->bh->b_data)->entries;

  		if (dx_get_limit(entries) != dx_node_limit(dir)) {
  			ext4_warning_inode(dir,
  				"dx entry: limit %u != node limit %u",
  				dx_get_limit(entries), dx_node_limit(dir));

  			goto fail;

  		}

  	}

  fail:

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

  	if (ret_err == ERR_PTR(ERR_BAD_DX_DIR))

  		ext4_warning_inode(dir,
  			"Corrupt directory, running e2fsck is recommended");

  	return ret_err;

  }

  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 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--) {

  		bh = ext4_read_dirblock(dir, dx_get_block(p->at), INDEX);
  		if (IS_ERR(bh))
  			return PTR_ERR(bh);

  		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 = 0, count = 0;

  	struct fscrypt_str fname_crypto_str = FSTR_INIT(NULL, 0), tmp_str;

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

  	bh = ext4_read_dirblock(dir, block, DIRENT);
  	if (IS_ERR(bh))
  		return PTR_ERR(bh);

  	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));

  #ifdef CONFIG_EXT4_FS_ENCRYPTION
  	/* Check if the directory is encrypted */

  	if (ext4_encrypted_inode(dir)) {

  		err = fscrypt_get_encryption_info(dir);

  		if (err < 0) {
  			brelse(bh);
  			return err;
  		}

  		err = fscrypt_fname_alloc_buffer(dir, EXT4_NAME_LEN,

  						     &fname_crypto_str);
  		if (err < 0) {

  			brelse(bh);
  			return err;
  		}
  	}
  #endif

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

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

  				bh->b_data, bh->b_size,

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

  			/* silently ignore the rest of the block */
  			break;

  		}

  		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 (!ext4_encrypted_inode(dir)) {

  			tmp_str.name = de->name;
  			tmp_str.len = de->name_len;
  			err = ext4_htree_store_dirent(dir_file,
  				   hinfo->hash, hinfo->minor_hash, de,
  				   &tmp_str);
  		} else {

  			int save_len = fname_crypto_str.len;

  			struct fscrypt_str de_name = FSTR_INIT(de->name,
  								de->name_len);

  			/* Directory is encrypted */

  			err = fscrypt_fname_disk_to_usr(dir, hinfo->hash,
  					hinfo->minor_hash, &de_name,
  					&fname_crypto_str);

  			if (err) {

  				count = err;
  				goto errout;
  			}
  			err = ext4_htree_store_dirent(dir_file,
  				   hinfo->hash, hinfo->minor_hash, de,
  					&fname_crypto_str);

  			fname_crypto_str.len = save_len;

  		}

  		if (err != 0) {

  			count = err;
  			goto errout;

  		}
  		count++;
  	}

  errout:

  	brelse(bh);

  #ifdef CONFIG_EXT4_FS_ENCRYPTION

  	fscrypt_fname_free_buffer(&fname_crypto_str);

  #endif

  	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;

  	struct fscrypt_str tmp_str;

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

  		       start_hash, start_minor_hash));

  	dir = file_inode(dir_file);

  	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;

  		if (ext4_has_inline_data(dir)) {
  			int has_inline_data = 1;
  			count = htree_inlinedir_to_tree(dir_file, dir, 0,
  							&hinfo, start_hash,
  							start_minor_hash,
  							&has_inline_data);
  			if (has_inline_data) {
  				*next_hash = ~0;
  				return count;
  			}
  		}

  		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);
  	if (IS_ERR(frame))
  		return PTR_ERR(frame);

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

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

  		tmp_str.name = de->name;
  		tmp_str.len = de->name_len;
  		err = ext4_htree_store_dirent(dir_file, 0, 0,
  					      de, &tmp_str);
  		if (err != 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);

  		tmp_str.name = de->name;
  		tmp_str.len = de->name_len;
  		err = ext4_htree_store_dirent(dir_file, 2, 0,
  					      de, &tmp_str);
  		if (err != 0)

  			goto errout;
  		count++;
  	}
  
  	while (1) {

  		if (fatal_signal_pending(current)) {
  			err = -ERESTARTSYS;
  			goto errout;
  		}
  		cond_resched();

  		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);
  }

  static inline int search_dirblock(struct buffer_head *bh,
  				  struct inode *dir,

  				  struct ext4_filename *fname,

  				  const struct qstr *d_name,
  				  unsigned int offset,
  				  struct ext4_dir_entry_2 **res_dir)
  {

  	return ext4_search_dir(bh, bh->b_data, dir->i_sb->s_blocksize, dir,
  			       fname, d_name, offset, res_dir);

  }

  /*
   * 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 inode *dir, 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);
  }

  /*

   * 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(struct ext4_filename *fname,

  			     struct ext4_dir_entry_2 *de)

  {

  	const void *name = fname_name(fname);
  	u32 len = fname_len(fname);

  	if (!de->inode)
  		return 0;

  
  #ifdef CONFIG_EXT4_FS_ENCRYPTION

  	if (unlikely(!name)) {
  		if (fname->usr_fname->name[0] == '_') {
  			int ret;
  			if (de->name_len < 16)
  				return 0;
  			ret = memcmp(de->name + de->name_len - 16,
  				     fname->crypto_buf.name + 8, 16);
  			return (ret == 0) ? 1 : 0;
  		}
  		name = fname->crypto_buf.name;
  		len = fname->crypto_buf.len;
  	}

  #endif

  	if (de->name_len != len)

  		return 0;

  	return (memcmp(de->name, name, len) == 0) ? 1 : 0;

  }
  
  /*
   * Returns 0 if not found, -1 on failure, and 1 on success
   */

  int ext4_search_dir(struct buffer_head *bh, char *search_buf, int buf_size,
  		    struct inode *dir, struct ext4_filename *fname,
  		    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;

  	int res;

  	de = (struct ext4_dir_entry_2 *)search_buf;
  	dlimit = search_buf + buf_size;

  	while ((char *) de < dlimit) {
  		/* this code is executed quadratically often */
  		/* do minimal checking `by hand' */

  		if ((char *) de + de->name_len <= dlimit) {

  			res = ext4_match(fname, de);

  			if (res < 0) {
  				res = -1;
  				goto return_result;
  			}
  			if (res > 0) {
  				/* found a match - just to be sure, do
  				 * a full check */
  				if (ext4_check_dir_entry(dir, NULL, de, bh,
  						bh->b_data,
  						 bh->b_size, offset)) {
  					res = -1;
  					goto return_result;
  				}
  				*res_dir = de;
  				res = 1;
  				goto return_result;
  			}

  		}
  		/* 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) {
  			res = -1;
  			goto return_result;
  		}

  		offset += de_len;

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

  	}

  
  	res = 0;
  return_result:

  	return res;

  }

  static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block,
  			       struct ext4_dir_entry *de)
  {
  	struct super_block *sb = dir->i_sb;
  
  	if (!is_dx(dir))
  		return 0;
  	if (block == 0)
  		return 1;
  	if (de->inode == 0 &&
  	    ext4_rec_len_from_disk(de->rec_len, sb->s_blocksize) ==
  			sb->s_blocksize)
  		return 1;
  	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,
  					int *inlined)

  {

  	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, namelen, retval;
  	struct ext4_filename fname;

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

  	namelen = d_name->len;

  	if (namelen > EXT4_NAME_LEN)

  		return NULL;

  	retval = ext4_fname_setup_filename(dir, d_name, 1, &fname);
  	if (retval)
  		return ERR_PTR(retval);

  	if (ext4_has_inline_data(dir)) {
  		int has_inline_data = 1;

  		ret = ext4_find_inline_entry(dir, &fname, d_name, res_dir,

  					     &has_inline_data);

  		if (has_inline_data) {
  			if (inlined)
  				*inlined = 1;

  			goto cleanup_and_exit;

  		}

  	}

  	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)) {

  		ret = ext4_dx_find_entry(dir, &fname, res_dir);

  		/*
  		 * On success, or if the error was file not found,
  		 * return.  Otherwise, fall back to doing a search the
  		 * old fashioned way.
  		 */

  		if (!IS_ERR(ret) || PTR_ERR(ret) != ERR_BAD_DX_DIR)
  			goto cleanup_and_exit;

  		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);

  				if (IS_ERR(bh)) {

  					if (ra_max == 0) {
  						ret = bh;
  						goto cleanup_and_exit;
  					}

  					break;
  				}

  				bh_use[ra_max] = bh;
  				if (bh)

  					ll_rw_block(REQ_OP_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;
  		}

  		if (!buffer_verified(bh) &&

  		    !is_dx_internal_node(dir, block,
  					 (struct ext4_dir_entry *)bh->b_data) &&

  		    !ext4_dirent_csum_verify(dir,
  				(struct ext4_dir_entry *)bh->b_data)) {
  			EXT4_ERROR_INODE(dir, "checksumming directory "
  					 "block %lu", (unsigned long)block);
  			brelse(bh);
  			goto next;
  		}
  		set_buffer_verified(bh);

  		i = search_dirblock(bh, dir, &fname, 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]);

  	ext4_fname_free_filename(&fname);

  	return ret;
  }

  static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
  			struct ext4_filename *fname,
  			struct ext4_dir_entry_2 **res_dir)

  {

  	struct super_block * sb = dir->i_sb;

  	struct dx_frame frames[2], *frame;

  	const struct qstr *d_name = fname->usr_fname;

  	struct buffer_head *bh;

  	ext4_lblk_t block;

  	int retval;

  #ifdef CONFIG_EXT4_FS_ENCRYPTION
  	*res_dir = NULL;
  #endif

  	frame = dx_probe(fname, dir, NULL, frames);

  	if (IS_ERR(frame))
  		return (struct buffer_head *) frame;

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

  		bh = ext4_read_dirblock(dir, block, DIRENT);

  		if (IS_ERR(bh))

  			goto errout;

  		retval = search_dirblock(bh, dir, fname, d_name,

  					 block << EXT4_BLOCK_SIZE_BITS(sb),
  					 res_dir);

  		if (retval == 1)
  			goto success;

  		brelse(bh);

  		if (retval == -1) {

  			bh = ERR_PTR(ERR_BAD_DX_DIR);

  			goto errout;
  		}

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

  		retval = ext4_htree_next_block(dir, fname->hinfo.hash, frame,

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

  			ext4_warning_inode(dir,
  				"error %d reading directory index block",
  				retval);

  			bh = ERR_PTR(retval);

  			goto errout;
  		}
  	} while (retval == 1);

  	bh = NULL;

  errout:

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

  success:
  	dx_release(frames);
  	return bh;

  }

  static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)

  {

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

  	if (ext4_encrypted_inode(dir)) {
  		int res = fscrypt_get_encryption_info(dir);

  
  		/*

  		 * DCACHE_ENCRYPTED_WITH_KEY is set if the dentry is

  		 * created while the directory was encrypted and we

  		 * have access to the key.

  		 */

  		if (fscrypt_has_encryption_key(dir))
  			fscrypt_set_encrypted_dentry(dentry);
  		fscrypt_set_d_op(dentry);
  		if (res && res != -ENOKEY)
  			return ERR_PTR(res);
  	}

         if (dentry->d_name.len > EXT4_NAME_LEN)
  	       return ERR_PTR(-ENAMETOOLONG);

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

  	if (IS_ERR(bh))
  		return (struct dentry *) bh;

  	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(-EFSCORRUPTED);

  		}

  		if (unlikely(ino == dir->i_ino)) {

  			EXT4_ERROR_INODE(dir, "'%pd' linked to parent dir",
  					 dentry);

  			return ERR_PTR(-EFSCORRUPTED);

  		}

  		inode = ext4_iget_normal(dir->i_sb, ino);

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

  			return ERR_PTR(-EFSCORRUPTED);

  		}

  		if (!IS_ERR(inode) && ext4_encrypted_inode(dir) &&

  		    (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) &&

  		    !fscrypt_has_permitted_context(dir, inode)) {

  			int nokey = ext4_encrypted_inode(inode) &&

  				!fscrypt_has_encryption_key(inode);

  			iput(inode);

  			if (nokey)
  				return ERR_PTR(-ENOKEY);

  			ext4_warning(inode->i_sb,

  				     "Inconsistent encryption contexts: %lu/%lu",

  				     (unsigned long) dir->i_ino,
  				     (unsigned long) inode->i_ino);
  			return ERR_PTR(-EPERM);
  		}

  	}
  	return d_splice_alias(inode, dentry);
  }

  struct dentry *ext4_get_parent(struct dentry *child)

  {

  	__u32 ino;

  	static const struct qstr dotdot = QSTR_INIT("..", 2);

  	struct ext4_dir_entry_2 * de;

  	struct buffer_head *bh;

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

  	if (IS_ERR(bh))
  		return (struct dentry *) bh;

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

  	if (!ext4_valid_inum(child->d_sb, ino)) {

  		EXT4_ERROR_INODE(d_inode(child),

  				 "bad parent inode number: %u", ino);

  		return ERR_PTR(-EFSCORRUPTED);

  	}

  	return d_obtain_alias(ext4_iget_normal(child->d_sb, ino));

  }

  /*
   * 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)

  {
  	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;

  	struct ext4_dir_entry_tail *t;
  	int	csum_size = 0;

  	int	err = 0, i;

  	if (ext4_has_metadata_csum(dir->i_sb))

  		csum_size = sizeof(struct ext4_dir_entry_tail);

  	bh2 = ext4_append(handle, dir, &newblock);
  	if (IS_ERR(bh2)) {

  		brelse(*bh);
  		*bh = NULL;

  		return (struct ext4_dir_entry_2 *) bh2;

  	}
  
  	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(dir, (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 - csum_size) -
  					   (char *) de,

  					   blocksize);

  	de2->rec_len = ext4_rec_len_to_disk(data2 + (blocksize - csum_size) -
  					    (char *) de2,

  					    blocksize);

  	if (csum_size) {
  		t = EXT4_DIRENT_TAIL(data2, blocksize);
  		initialize_dirent_tail(t, blocksize);
  
  		t = EXT4_DIRENT_TAIL(data1, blocksize);
  		initialize_dirent_tail(t, blocksize);
  	}

  	dxtrace(dx_show_leaf(dir, hinfo, (struct ext4_dir_entry_2 *) data1,
  			blocksize, 1));
  	dxtrace(dx_show_leaf(dir, 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_dirent_node(handle, dir, bh2);

  	if (err)
  		goto journal_error;

  	err = ext4_handle_dirty_dx_node(handle, dir, frame->bh);