text: /*
   *  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)
  
  struct buffer_head *ext4_append(handle_t *handle,
  					struct inode *inode,
  					ext4_lblk_t *block)
  {
  	struct buffer_head *bh;
  	struct ext4_inode_info *ei = EXT4_I(inode);
  	int err = 0;
  
  	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);
  
  	/* with parallel dir operations all appends
  	* have to be serialized -bzzz */
  	down(&ei->i_append_sem);
  
  	*block = inode->i_size >> inode->i_sb->s_blocksize_bits;
  
  	bh = ext4_bread(handle, inode, *block, 1, &err);
  	if (!bh) {
  		up(&ei->i_append_sem);
  		return ERR_PTR(err);
  	}
  	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);
  	up(&ei->i_append_sem);
  	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), __LINE__)
  
  static struct buffer_head *__ext4_read_dirblock(struct inode *inode,
  					      ext4_lblk_t block,
  					      dirblock_type_t type,
  					      unsigned int line)
  {
  	struct buffer_head *bh;
  	struct ext4_dir_entry *dirent;
  	int err = 0, is_dx_block = 0;
  
  	bh = ext4_bread(NULL, inode, block, 0, &err);
  	if (!bh) {
  		if (err == 0) {
  			ext4_error_inode(inode, __func__, line, block,
  					       "Directory hole found");
  			return ERR_PTR(-EIO);
  		}
  		__ext4_warning(inode->i_sb, __func__, line,
  			       "error reading directory block "
  			       "(ino %lu, block %lu)", inode->i_ino,
  			       (unsigned long) block);
  		return ERR_PTR(err);
  	}
  	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(-EIO);
  	}
  	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(-EIO);
  		}
  	}
  	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(-EIO);
  		}
  	}
  	return bh;
  }
  EXPORT_SYMBOL(ext4_append);
  
  #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_info
  {
  	__le32 reserved_zero;
  	u8 hash_version;
  	u8 info_length; /* 8 */
  	u8 indirect_levels;
  	u8 unused_flags;
  };
  
  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 inline unsigned dx_root_limit(struct inode *dir,
  		struct ext4_dir_entry_2 *dot_de, 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,
  				 struct htree_lock *lck, 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, struct htree_lock *lck);
  static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
  		const struct qstr *d_name,
  		struct ext4_dir_entry_2 **res_dir,
  		struct htree_lock *lck, int *err);
  static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
  			     struct inode *inode, struct htree_lock *lck);
  
  /* 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);
  }
  
  static void warn_no_space_for_csum(struct inode *inode)
  {
  	ext4_warning(inode->i_sb, "no space in directory inode %lu leaf for "
  		     "checksum.  Please run e2fsck -D.", inode->i_ino);
  }
  
  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;
  	__le32 save_csum;
  	int size;
  
  	size = count_offset + (count * sizeof(struct dx_entry));
  	save_csum = t->dt_checksum;
  	t->dt_checksum = 0;
  	csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)dirent, size);
  	csum = ext4_chksum(sbi, csum, (__u8 *)t, sizeof(struct dx_tail));
  	t->dt_checksum = save_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 1;
  	}
  	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 1;
  	}
  	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.
   */
  struct dx_root_info *dx_get_dx_info(struct ext4_dir_entry_2 *de)
  {
  	BUG_ON(de->name_len != 1);
  	/* get dotdot first */
  	de = (struct ext4_dir_entry_2 *)((char *)de + EXT4_DIR_REC_LEN(de));
  
  	/* dx root info is after dotdot entry */
  	de = (struct ext4_dir_entry_2 *)((char *)de + EXT4_DIR_REC_LEN(de));
  
  	return (struct dx_root_info *)de;
  }
  
  static inline ext4_lblk_t dx_get_block(struct dx_entry *entry)
  {
  	return le32_to_cpu(entry->block) & 0x0fffffff;
  }
  
  static inline int
  ext4_dir_htree_level(struct super_block *sb)
  {
  	return EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_LARGEDIR) ?
  		EXT4_HTREE_LEVEL : EXT4_HTREE_LEVEL_COMPAT;
  }
  
  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,
  		struct ext4_dir_entry_2 *dot_de, unsigned infosize)
  {
  	struct ext4_dir_entry_2 *dotdot_de;
  	unsigned entry_space;
  
  	BUG_ON(dot_de->name_len != 1);
  	dotdot_de = ext4_next_entry(dot_de, dir->i_sb->s_blocksize);
  	entry_space = dir->i_sb->s_blocksize - EXT4_DIR_REC_LEN(dot_de) -
  			 EXT4_DIR_REC_LEN(dotdot_de) - 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("%x->%lu ", i ? dx_get_hash(entries + i) :
  				0, (unsigned long)dx_get_block(entries + i));
  	}
  	printk("\n");
  }
  
  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);
  			names++;
  		}
  		de = ext4_next_entry(de, size);
  	}
  	printk("(%i)\n", 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...\n", 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%%)\n",
  		       levels ? "" : "   ", names, space/bcount,
  		       (space/bcount)*100/blocksize);
  	return (struct stats) { names, space, bcount};
  }
  #endif /* DX_DEBUG */
  
  /* private data for htree_lock */
  struct ext4_dir_lock_data {
  	unsigned		ld_flags;  /* bits-map for lock types */
  	unsigned		ld_count;  /* # entries of the last DX block */
  	struct dx_entry		ld_at_entry; /* copy of leaf dx_entry */
  	struct dx_entry		*ld_at;	   /* position of leaf dx_entry */
  };
  
  #define ext4_htree_lock_data(l)	((struct ext4_dir_lock_data *)(l)->lk_private)
  #define ext4_find_entry(dir, name, dirent, inline) \
  			__ext4_find_entry(dir, name, dirent, inline, NULL)
  
  /* NB: ext4_lblk_t is 32 bits so we use high bits to identify invalid blk */
  #define EXT4_HTREE_NODE_CHANGED	(0xcafeULL << 32)
  
  inline int ext4_add_entry(handle_t *handle, struct dentry *dentry,
  			  struct inode *inode)
  {
  	int ret = __ext4_add_entry(handle, dentry, inode, NULL);
  
  	if (ret == -ENOBUFS)
  		ret = 0;
  	return ret;
  }
  
  static void ext4_htree_event_cb(void *target, void *event)
  {
  	u64 *block = (u64 *)target;
  
  	if (*block == dx_get_block((struct dx_entry *)event))
  		*block = EXT4_HTREE_NODE_CHANGED;
  }
  
  struct htree_lock_head *ext4_htree_lock_head_alloc(unsigned hbits)
  {
  	struct htree_lock_head *lhead;
  
  	lhead = htree_lock_head_alloc(EXT4_LK_MAX, hbits, 0);
  	if (lhead != NULL) {
  		htree_lock_event_attach(lhead, EXT4_LK_SPIN, HTREE_EVENT_WR,
  					ext4_htree_event_cb);
  	}
  	return lhead;
  }
  EXPORT_SYMBOL(ext4_htree_lock_head_alloc);
  
  struct htree_lock *ext4_htree_lock_alloc(void)
  {
  	return htree_lock_alloc(EXT4_LK_MAX,
  				sizeof(struct ext4_dir_lock_data));
  }
  EXPORT_SYMBOL(ext4_htree_lock_alloc);
  
  static htree_lock_mode_t ext4_htree_mode(unsigned flags)
  {
  	switch (flags) {
  	default: /* 0 or unknown flags require EX lock */
  		return HTREE_LOCK_EX;
  	case EXT4_HLOCK_READDIR:
  		return HTREE_LOCK_PR;
  	case EXT4_HLOCK_LOOKUP:
  		return HTREE_LOCK_CR;
  	case EXT4_HLOCK_DEL:
  	case EXT4_HLOCK_ADD:
  		return HTREE_LOCK_CW;
  	}
  }
  
  /* return PR for read-only operations, otherwise return EX */
  static inline htree_lock_mode_t ext4_htree_safe_mode(unsigned flags)
  {
  	int writer = (flags & EXT4_LB_DE) == EXT4_LB_DE;
  
  	/* 0 requires EX lock */
  	return (flags == 0 || writer) ? HTREE_LOCK_EX : HTREE_LOCK_PR;
  }
  
  static int ext4_htree_safe_locked(struct htree_lock *lck)
  {
  	int writer;
  
  	if (lck == NULL || lck->lk_mode == HTREE_LOCK_EX)
  		return 1;
  
  	writer = (ext4_htree_lock_data(lck)->ld_flags & EXT4_LB_DE) ==
  		 EXT4_LB_DE;
  	if (writer) /* all readers & writers are excluded? */
  		return lck->lk_mode == HTREE_LOCK_EX;
  
  	/* all writers are excluded? */
  	return lck->lk_mode == HTREE_LOCK_PR ||
  	       lck->lk_mode == HTREE_LOCK_PW ||
  	       lck->lk_mode == HTREE_LOCK_EX;
  }
  
  /* relock htree_lock with EX mode if it's change operation, otherwise
   * relock it with PR mode. It's noop if PDO is disabled. */
  static void ext4_htree_safe_relock(struct htree_lock *lck)
  {
  	if (!ext4_htree_safe_locked(lck)) {
  		unsigned flags = ext4_htree_lock_data(lck)->ld_flags;
  
  		htree_change_lock(lck, ext4_htree_safe_mode(flags));
  	}
  }
  
  void ext4_htree_lock(struct htree_lock *lck, struct htree_lock_head *lhead,
  		     struct inode *dir, unsigned flags)
  {
  	htree_lock_mode_t mode = is_dx(dir) ? ext4_htree_mode(flags) :
  					      ext4_htree_safe_mode(flags);
  
  	ext4_htree_lock_data(lck)->ld_flags = flags;
  	htree_lock(lck, lhead, mode);
  	if (!is_dx(dir))
  		ext4_htree_safe_relock(lck); /* make sure it's safe locked */
  }
  EXPORT_SYMBOL(ext4_htree_lock);
  
  static int ext4_htree_node_lock(struct htree_lock *lck, struct dx_entry *at,
  				unsigned lmask, int wait, void *ev)
  {
  	u32	key = (at == NULL) ? 0 : dx_get_block(at);
  	u32	mode;
  
  	/* NOOP if htree is well protected or caller doesn't require the lock */
  	if (ext4_htree_safe_locked(lck) ||
  	   !(ext4_htree_lock_data(lck)->ld_flags & lmask))
  		return 1;
  
  	mode = (ext4_htree_lock_data(lck)->ld_flags & lmask) == lmask ?
  		HTREE_LOCK_PW : HTREE_LOCK_PR;
  	while (1) {
  		if (htree_node_lock_try(lck, mode, key, ffz(~lmask), wait, ev))
  			return 1;
  		if (!(lmask & EXT4_LB_SPIN)) /* not a spinlock */
  			return 0;
  		cpu_relax(); /* spin until granted */
  	}
  }
  
  static int ext4_htree_node_locked(struct htree_lock *lck, unsigned lmask)
  {
  	return ext4_htree_safe_locked(lck) ||
  	       htree_node_is_granted(lck, ffz(~lmask));
  }
  
  static void ext4_htree_node_unlock(struct htree_lock *lck,
  				   unsigned lmask, void *buf)
  {
  	/* NB: it's safe to call mutiple times or even it's not locked */
  	if (!ext4_htree_safe_locked(lck) &&
  	     htree_node_is_granted(lck, ffz(~lmask)))
  		htree_node_unlock(lck, ffz(~lmask), buf);
  }
  
  #define ext4_htree_dx_lock(lck, key)		\
  	ext4_htree_node_lock(lck, key, EXT4_LB_DX, 1, NULL)
  #define ext4_htree_dx_lock_try(lck, key)	\
  	ext4_htree_node_lock(lck, key, EXT4_LB_DX, 0, NULL)
  #define ext4_htree_dx_unlock(lck)		\
  	ext4_htree_node_unlock(lck, EXT4_LB_DX, NULL)
  #define ext4_htree_dx_locked(lck)		\
  	ext4_htree_node_locked(lck, EXT4_LB_DX)
  
  static void ext4_htree_dx_need_lock(struct htree_lock *lck)
  {
  	struct ext4_dir_lock_data *ld;
  
  	if (ext4_htree_safe_locked(lck))
  		return;
  
  	ld = ext4_htree_lock_data(lck);
  	switch (ld->ld_flags) {
  	default:
  		return;
  	case EXT4_HLOCK_LOOKUP:
  		ld->ld_flags = EXT4_HLOCK_LOOKUP_SAFE;
  		return;
  	case EXT4_HLOCK_DEL:
  		ld->ld_flags = EXT4_HLOCK_DEL_SAFE;
  		return;
  	case EXT4_HLOCK_ADD:
  		ld->ld_flags = EXT4_HLOCK_SPLIT;
  		return;
  	}
  }
  
  #define ext4_htree_de_lock(lck, key)		\
  	ext4_htree_node_lock(lck, key, EXT4_LB_DE, 1, NULL)
  #define ext4_htree_de_unlock(lck)		\
  	ext4_htree_node_unlock(lck, EXT4_LB_DE, NULL)
  
  #define ext4_htree_spin_lock(lck, key, event)	\
  	ext4_htree_node_lock(lck, key, EXT4_LB_SPIN, 0, event)
  #define ext4_htree_spin_unlock(lck)		\
  	ext4_htree_node_unlock(lck, EXT4_LB_SPIN, NULL)
  #define ext4_htree_spin_unlock_listen(lck, p)	\
  	ext4_htree_node_unlock(lck, EXT4_LB_SPIN, p)
  
  static void ext4_htree_spin_stop_listen(struct htree_lock *lck)
  {
  	if (!ext4_htree_safe_locked(lck) &&
  	    htree_node_is_listening(lck, ffz(~EXT4_LB_SPIN)))
  		htree_node_stop_listen(lck, ffz(~EXT4_LB_SPIN));
  }
  
  enum {
  	DX_HASH_COL_IGNORE,	/* ignore collision while probing frames */
  	DX_HASH_COL_YES,	/* there is collision and it does matter */
  	DX_HASH_COL_NO,		/* there is no collision */
  };
  
  static int dx_probe_hash_collision(struct htree_lock *lck,
  				   struct dx_entry *entries,
  				   struct dx_entry *at, u32 hash)
  {
  	if (!(ext4_htree_lock_data(lck)->ld_flags & EXT4_LB_EXACT)) {
  		return DX_HASH_COL_IGNORE; /* don't care about collision */
  
  	} else if (at == entries + dx_get_count(entries) - 1) {
  		return DX_HASH_COL_IGNORE; /* not in any leaf of this DX */
  
  	} else { /* hash collision? */
  		return ((dx_get_hash(at + 1) & ~1) == hash) ?
  			DX_HASH_COL_YES : DX_HASH_COL_NO;
  	}
  }
  
  /*
   * 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,
  	 struct htree_lock *lck, int *err)
  {
  	unsigned count, indirect;
  	struct dx_entry *at, *entries, *p, *q, *m, *dx = NULL;
  	struct dx_root_info *info;
  	struct buffer_head *bh;
  	struct dx_frame *frame = frame_in;
  	u32 hash;
  
  	memset(frame_in, 0, EXT4_HTREE_LEVEL * sizeof(frame_in[0]));
  	bh = ext4_read_dirblock(dir, 0, INDEX);
  	if (IS_ERR(bh)) {
  		*err = PTR_ERR(bh);
  		goto fail;
  	}
  
  	info = dx_get_dx_info((struct ext4_dir_entry_2 *)bh->b_data);
  	if (info->hash_version != DX_HASH_TEA &&
  	    info->hash_version != DX_HASH_HALF_MD4 &&
  	    info->hash_version != DX_HASH_LEGACY) {
  		ext4_warning(dir->i_sb, "inode #%lu: unrecognised hash code %u",
  			     dir->i_ino, info->hash_version);
  		brelse(bh);
  		*err = ERR_BAD_DX_DIR;
  		goto fail;
  	}
  	hinfo->hash_version = 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 (info->unused_flags & 1) {
  		ext4_warning(dir->i_sb,
  			     "inode #%lu: unimplemented hash flags: %#06x",
  			     dir->i_ino, info->unused_flags);
  		brelse(bh);
  		*err = ERR_BAD_DX_DIR;
  		goto fail;
  	}
  
  	indirect = info->indirect_levels;
  	if (indirect >= ext4_dir_htree_level(dir->i_sb)) {
  		ext4_warning(dir->i_sb,
  			     "inode #%lu: comm %s: htree depth %#06x exceed max depth %u",
  			     dir->i_ino, current->comm, indirect,
  			     ext4_dir_htree_level(dir->i_sb));
  		if (ext4_dir_htree_level(dir->i_sb) < EXT4_HTREE_LEVEL) {
  			ext4_warning(dir->i_sb, "Enable large directory "
  						"feature to access it");
  		}
  		brelse(bh);
  		*err = ERR_BAD_DX_DIR;
  		goto fail;
  	}
  
  	entries = (struct dx_entry *)(((char *)info) + info->info_length);
  
  	if (dx_get_limit(entries) !=
  	    dx_root_limit(dir, (struct ext4_dir_entry_2 *)bh->b_data,
  			  info->info_length)) {
  		ext4_warning(dir->i_sb, "dx entry: limit != root limit "
  			     "inode #%lu: dx entry: limit %u != root limit %u",
  			     dir->i_ino, dx_get_limit(entries),
  			     dx_root_limit(dir,
  					  (struct ext4_dir_entry_2 *)bh->b_data,
  					  info->info_length));
  		brelse(bh);
  		*err = ERR_BAD_DX_DIR;
  		goto fail;
  	}
  
  	dxtrace(printk("Look up %x", hash));
  	while (1)
  	{
  		if (indirect == 0) { /* the last index level */
  			/* NB: ext4_htree_dx_lock() could be noop if
  			 * DX-lock flag is not set for current operation */
  			ext4_htree_dx_lock(lck, dx);
  			ext4_htree_spin_lock(lck, dx, NULL);
  		}
  		count = dx_get_count(entries);
  		if (count == 0 || count > dx_get_limit(entries)) {
  			ext4_htree_spin_unlock(lck); /* release spin */
  			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\n", at == entries? 0: dx_get_hash(at), dx_get_block(at)));
  		frame->bh = bh;
  		frame->entries = entries;
  		frame->at = at;
  
  		if (indirect == 0) { /* the last index level */
  			struct ext4_dir_lock_data *ld;
  			u64 myblock;
  
  			/* By default we only lock DE-block, however, we will
  			 * also lock the last level DX-block if:
  			 * a) there is hash collision
  			 *    we will set DX-lock flag (a few lines below)
  			 *    and redo to lock DX-block
  			 *    see detail in dx_probe_hash_collision()
  			 * b) it's a retry from splitting
  			 *    we need to lock the last level DX-block so nobody
  			 *    else can split any leaf blocks under the same
  			 *    DX-block, see detail in ext4_dx_add_entry()
  			 */
  			if (ext4_htree_dx_locked(lck)) {
  				/* DX-block is locked, just lock DE-block
  				 * and return */
  				ext4_htree_spin_unlock(lck);
  				if (!ext4_htree_safe_locked(lck))
  					ext4_htree_de_lock(lck, frame->at);
  				return frame;
  			}
  			/* it's pdirop and no DX lock */
  			if (dx_probe_hash_collision(lck, entries, at, hash) ==
  			    DX_HASH_COL_YES) {
  				/* found hash collision, set DX-lock flag
  				 * and retry to abtain DX-lock */
  				ext4_htree_spin_unlock(lck);
  				ext4_htree_dx_need_lock(lck);
  				continue;
  			}
  			ld = ext4_htree_lock_data(lck);
  			/* because I don't lock DX, so @at can't be trusted
  			 * after I release spinlock so I have to save it */
  			ld->ld_at = at;
  			ld->ld_at_entry = *at;
  			ld->ld_count = dx_get_count(entries);
  
  			frame->at = &ld->ld_at_entry;
  			myblock = dx_get_block(at);
  
  			/* NB: ordering locking */
  			ext4_htree_spin_unlock_listen(lck, &myblock);
  			/* other thread can split this DE-block because:
  			 * a) I don't have lock for the DE-block yet
  			 * b) I released spinlock on DX-block
  			 * if it happened I can detect it by listening
  			 * splitting event on this DE-block */
  			ext4_htree_de_lock(lck, frame->at);
  			ext4_htree_spin_stop_listen(lck);
  
  			if (myblock == EXT4_HTREE_NODE_CHANGED) {
  				/* someone split this DE-block before
  				 * I locked it, I need to retry and lock
  				 * valid DE-block */
  				ext4_htree_de_unlock(lck);
  				continue;
  			}
  			return frame;
  		}
  		dx = at;
  		indirect--;
  		bh = ext4_read_dirblock(dir, dx_get_block(at), INDEX);
  		if (IS_ERR(bh)) {
  			*err = PTR_ERR(bh);
  			goto fail2;
  		}
  		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 %lu, running e2fsck is "
  			     "recommended.", dir->i_ino);
  	return NULL;
  }
  
  static void dx_release (struct dx_frame *frames)
  {
  	struct dx_root_info *info;
  	int i;
  
  	if (frames[0].bh == NULL)
  		return;
  
  	info = dx_get_dx_info((struct ext4_dir_entry_2 *)frames[0].bh->b_data);
  	for (i = 0; i <= info->indirect_levels; i++) {
  		if (frames[i].bh == NULL)
  			break;
  		brelse(frames[i].bh);
  		frames[i].bh = NULL;
  	}
  }
  
  /*
   * 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 htree_lock *lck)
  {
  	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.
  	 */
  	ext4_htree_de_unlock(lck);
  	while (1) {
  		if (num_frames > 0 || ext4_htree_dx_locked(lck)) {
  			/* num_frames > 0 :
  			 *   DX block
  			 * ext4_htree_dx_locked:
  			 *   frame->at is reliable pointer returned by dx_probe,
  			 *   otherwise dx_probe already knew no collision */
  			if (++(p->at) < p->entries + dx_get_count(p->entries))
  				break;
  		}
  		if (p == frames)
  			return 0;
  		num_frames++;
  		if (num_frames == 1)
  			ext4_htree_dx_unlock(lck);
  		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 (num_frames == 0) {
  			/* it's not always necessary, we just don't want to
  			 * detect hash collision again */
  			ext4_htree_dx_need_lock(lck);
  			ext4_htree_dx_lock(lck, p->at);
  		}
  
  		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;
  	}
  	ext4_htree_de_lock(lck, p->at);
  	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;
  
  	dxtrace(printk(KERN_INFO "In htree dirblock_to_tree: block %lu\n",
  							(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));
  	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 ((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[EXT4_HTREE_LEVEL], *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\n",
  		       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;
  	/* assume it's PR locked */
  	frame = dx_probe(NULL, dir, &hinfo, frames, NULL, &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, NULL);
  		*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\n", count, *next_hash));
  	return count;
  errout:
  	dx_release(frames);
  	return (err);
  }
  
  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)
  {
  	return search_dir(bh, bh->b_data, dir->i_sb->s_blocksize, dir,
  			  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 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 (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
   */
  int search_dir(struct buffer_head *bh,
  	       char *search_buf,
  	       int buf_size,
  	       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 *)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 + 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, bh->b_data,
  						 bh->b_size, 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;
  }
  
  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.
   */
  struct buffer_head *__ext4_find_entry(struct inode *dir,
  					const struct qstr *d_name,
  					struct ext4_dir_entry_2 **res_dir,
  					int *inlined, struct htree_lock *lck)
  {
  	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 = 0;
  	int namelen;
  
  	*res_dir = NULL;
  	sb = dir->i_sb;
  	namelen = d_name->len;
  	if (namelen > EXT4_NAME_LEN)
  		return NULL;
  
  	if (ext4_has_inline_data(dir)) {
  		int has_inline_data = 1;
  		ret = ext4_find_inline_entry(dir, d_name, res_dir,
  					     &has_inline_data);
  		if (has_inline_data) {
  			if (inlined)
  				*inlined = 1;
  			return ret;
  		}
  	}
  
  	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, lck, &err);
  		/*
  		 * On success, or if the error was file not found,
  		 * return.  Otherwise, fall back to doing a search the
  		 * old fashioned way.
  		 */
  		if (err == -ENOENT)
  			return NULL;
  		if (err && err != ERR_BAD_DX_DIR)
  			return ERR_PTR(err);
  		if (bh)
  			return bh;
  		dxtrace(printk(KERN_DEBUG "ext4_find_entry: dx failed, "
  			       "falling back\n"));
  		ext4_htree_safe_relock(lck);
  	}
  	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);
  				if (unlikely(err)) {
  					if (ra_max == 0)
  						return ERR_PTR(err);
  					break;
  				}
  				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;
  		}
  		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, 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;
  }
  EXPORT_SYMBOL(__ext4_find_entry);
  
  static struct buffer_head *ext4_dx_find_entry(struct inode *dir,
  				const struct qstr *d_name,
  				struct ext4_dir_entry_2 **res_dir,
  				struct htree_lock *lck, int *err)
  {
  	struct super_block * sb = dir->i_sb;
  	struct dx_hash_info	hinfo;
  	struct dx_frame frames[EXT4_HTREE_LEVEL], *frame;
  	struct buffer_head *bh;
  	ext4_lblk_t block;
  	int retval;
  
  	if (!(frame = dx_probe(d_name, dir, &hinfo, frames, lck, err)))
  		return NULL;
  	do {
  		block = dx_get_block(frame->at);
  		bh = ext4_read_dirblock(dir, block, DIRENT);
  		if (IS_ERR(bh)) {
  			*err = PTR_ERR(bh);
  			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, lck);
  		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\n", d_name->name));
  	dx_release (frames);
  	return NULL;
  }
  
  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 (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(-EIO);
  		}
  		if (unlikely(ino == dir->i_ino)) {
  			EXT4_ERROR_INODE(dir, "'%pd' linked to parent dir",
  					 dentry);
  			return ERR_PTR(-EIO);
  		}
  		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(-EIO);
  		}
  	}
  	/* ".." shouldn't go into dcache to preserve dcache hierarchy
  	 * otherwise we'll get parent being a child of actual child.
  	 * see bug 10458 for details -bzzz */
  	if (inode && (dentry->d_name.name[0] == '.' &&
  		      (dentry->d_name.len == 1 || (dentry->d_name.len == 2 &&
  					     dentry->d_name.name[1] == '.')))) {
  		struct dentry *goal = NULL;
  
  		/* first, look for an existing dentry - any one is good */
  		goal = d_find_any_alias(inode);
  		if (goal == NULL) {
  			spin_lock(&dentry->d_lock);
  			/* there is no alias, we need to make current dentry:
  			 *  a) inaccessible for __d_lookup()
  			 *  b) inaccessible for iopen */
  			J_ASSERT(hlist_unhashed(&dentry->d_alias));
  			dentry->d_flags |= DCACHE_NFSFS_RENAMED;
  			/* this is d_instantiate() ... */
  			hlist_add_head(&dentry->d_alias, &inode->i_dentry);
  			dentry->d_inode = inode;
  			spin_unlock(&dentry->d_lock);
  		}
  		if (goal)
  			iput(inode);
  		return goal;
  	}
  
  	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(child->d_inode, &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_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_normal(child->d_inode->i_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);
  		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);
  			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 *frames,
  			struct dx_frame *frame, struct dx_hash_info *hinfo,
  			struct htree_lock *lck, 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;
  	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;
  		*error = PTR_ERR(bh2);
  		return NULL;
  	}
  
  	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\n",
  			(unsigned long)dx_get_block(frame->at),
  					hash2, split, count-split));
  
  	/* Fancy dance to stay within two buffers */
  	if (hinfo->hash < hash2) {
  		de2 = dx_move_dirents(data1, data2, map + split,
  				      count - split, blocksize);
  	} else {
  		/* make sure we will add entry to the same block which
  		 * we have already locked */
  		de2 = dx_move_dirents(data1, data2, map, 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 (hinfo, (struct ext4_dir_entry_2 *) data1, blocksize, 1));
  	dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data2, blocksize, 1));
  
  	ext4_htree_spin_lock(lck, frame > frames ? (frame - 1)->at : NULL,
  			     frame->at); /* notify block is being split */
  	if (hinfo->hash < hash2) {
  		dx_insert_block(frame, hash2 + continued, newblock);
  
  	} else {
  		/* switch block number */
  		dx_insert_block(frame, hash2 + continued,
  				dx_get_block(frame->at));
  		dx_set_block(frame->at, newblock);
  		(frame->at)++;
  	}
  	ext4_htree_spin_unlock(lck);
  	ext4_htree_dx_unlock(lck);
  
  	err = ext4_handle_dirty_dirent_node(handle, dir, bh2);
  	if (err)
  		goto journal_error;
  	err = ext4_handle_dirty_dx_node(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);
  	*error = err;
  	return NULL;
  }
  
  int ext4_find_dest_de(struct inode *dir, struct inode *inode,
  		      struct buffer_head *bh,
  		      void *buf, int buf_size,
  		      const char *name, int namelen,
  		      struct ext4_dir_entry_2 **dest_de, int *dlen)
  {
  	struct ext4_dir_entry_2 *de;
  	unsigned short reclen = __EXT4_DIR_REC_LEN(namelen) +
  							(dlen ? *dlen : 0);
  	int nlen, rlen;
  	unsigned int offset = 0;
  	char *top;
  
  	dlen ? *dlen = 0 : 0; /* default set to 0 */
  	de = (struct ext4_dir_entry_2 *)buf;
  	top = buf + buf_size - reclen;
  	while ((char *) de <= top) {
  		if (ext4_check_dir_entry(dir, NULL, de, bh,
  					 buf, buf_size, offset))
  			return -EIO;
  		if (ext4_match(namelen, name, de))
  			return -EEXIST;
  		nlen = EXT4_DIR_REC_LEN(de);
  		rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
  		if ((de->inode ? rlen - nlen : rlen) >= reclen)
  			break;
  		/* Then for dotdot entries, check for the smaller space
  		 * required for just the entry, no FID */
  		if (namelen == 2 && memcmp(name, "..", 2) == 0) {
  			if ((de->inode ? rlen - nlen : rlen) >=
  			    __EXT4_DIR_REC_LEN(namelen)) {
  				/* set dlen=1 to indicate not
  				 * enough space store fid */
  				dlen ? *dlen = 1 : 0;
  				break;
  			}
  			/* The new ".." entry must be written over the
  			 * previous ".." entry, which is the first
  			 * entry traversed by this scan. If it doesn't
  			 * fit, something is badly wrong, so -EIO. */
  			return -EIO;
  		}
  		de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
  		offset += rlen;
  	}
  	if ((char *) de > top)
  		return -ENOSPC;
  
  	*dest_de = de;
  	return 0;
  }
  
  void ext4_insert_dentry(struct inode *inode,
  			struct ext4_dir_entry_2 *de,
  			int buf_size,
  			const char *name, int namelen, void *data)
  {
  
  	int nlen, rlen;
  
  	nlen = EXT4_DIR_REC_LEN(de);
  	rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
  	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, buf_size);
  		de->rec_len = ext4_rec_len_to_disk(nlen, buf_size);
  		de = de1;
  	}
  	de->file_type = EXT4_FT_UNKNOWN;
  	de->inode = cpu_to_le32(inode->i_ino);
  	ext4_set_de_type(inode->i_sb, de, inode->i_mode);
  	de->name_len = namelen;
  	memcpy(de->name, name, namelen);
  	if (data) {
  		de->name[namelen] = 0;
  		memcpy(&de->name[namelen + 1], data, *(char *)data);
  		de->file_type |= EXT4_DIRENT_LUFID;
  	}
  }
  /*
   * 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	blocksize = dir->i_sb->s_blocksize;
  	int		csum_size = 0;
  	int		err, dlen = 0;
  	unsigned char	*data;
  
  	data = ext4_dentry_get_data(inode->i_sb, (struct ext4_dentry_param *)
  						dentry->d_fsdata);
  	if (ext4_has_metadata_csum(inode->i_sb))
  		csum_size = sizeof(struct ext4_dir_entry_tail);
  
  	if (!de) {
  		if (data)
  			dlen = (*data) + 1;
  		err = ext4_find_dest_de(dir, inode,
  					bh, bh->b_data, blocksize - csum_size,
  					name, namelen, &de, &dlen);
  		if (err)
  			return err;
  	}
  	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 */
  	/* If writing the short form of "dotdot", don't add the data section */
  	if (dlen == 1)
  		data = NULL;
  	ext4_insert_dentry(inode, de, blocksize, name, namelen, data);
  
  	/*
  	 * 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_dirent_node(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_frame	frames[EXT4_HTREE_LEVEL], *frame;
  	struct dx_entry *entries;
  	struct ext4_dir_entry_2 *de, *de2, *dot_de, *dotdot_de;
  	struct ext4_dir_entry_tail *t;
  	char		*data1, *top;
  	unsigned	len;
  	int		retval;
  	unsigned	blocksize;
  	struct dx_hash_info hinfo;
  	ext4_lblk_t  block;
  	struct dx_root_info *dx_info;
  	int		csum_size = 0;
  
  	if (ext4_has_metadata_csum(inode->i_sb))
  		csum_size = sizeof(struct ext4_dir_entry_tail);
  
  	blocksize =  dir->i_sb->s_blocksize;
  	dxtrace(printk(KERN_DEBUG "Creating index: inode %lu\n", dir->i_ino));
  	BUFFER_TRACE(bh, "get_write_access");
  	retval = ext4_journal_get_write_access(handle, bh);
  	if (retval) {
  		ext4_std_error(dir->i_sb, retval);
  		brelse(bh);
  		return retval;
  	}
  
  	dot_de = (struct ext4_dir_entry_2 *)bh->b_data;
  	dotdot_de = ext4_next_entry(dot_de, blocksize);
  
  	/* The 0th block becomes the root, move the dirents out */
  	de = (struct ext4_dir_entry_2 *)((char *)dotdot_de +
  		ext4_rec_len_from_disk(dotdot_de->rec_len, blocksize));
  	if ((char *)de >= (((char *)dot_de) + blocksize)) {
  		EXT4_ERROR_INODE(dir, "invalid rec_len for '..'");
  		brelse(bh);
  		return -EIO;
  	}
  	len = ((char *)dot_de) + (blocksize - csum_size) - (char *)de;
  
  	/* Allocate new block for the 0th block's dirents */
  	bh2 = ext4_append(handle, dir, &block);
  	if (IS_ERR(bh2)) {
  		brelse(bh);
  		return PTR_ERR(bh2);
  	}
  	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 - csum_size) -
  					   (char *) de,
  					   blocksize);
  
  	if (csum_size) {
  		t = EXT4_DIRENT_TAIL(data1, blocksize);
  		initialize_dirent_tail(t, blocksize);
  	}
  
  	/* Initialize the root; the dot dirents already exist */
  	dotdot_de->rec_len =
  		ext4_rec_len_to_disk(blocksize - le16_to_cpu(dot_de->rec_len),
  				     blocksize);
  
  	/* initialize hashing info */
  	dx_info = dx_get_dx_info(dot_de);
  	memset(dx_info, 0, sizeof(*dx_info));
  	dx_info->info_length = sizeof(*dx_info);
  	dx_info->hash_version = EXT4_SB(dir->i_sb)->s_def_hash_version;
  
  	entries = (void *)dx_info + sizeof(*dx_info);
  
  	dx_set_block(entries, 1);
  	dx_set_count(entries, 1);
  	dx_set_limit(entries, dx_root_limit(dir,
  					 dot_de, sizeof(*dx_info)));
  
  	/* Initialize as for dx_probe */
  	hinfo.hash_version = dx_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);
  	memset(frames, 0, sizeof(frames));
  	frame = frames;
  	frame->entries = entries;
  	frame->at = entries;
  	frame->bh = bh;
  
  	retval = ext4_handle_dirty_dx_node(handle, dir, frame->bh);
  	if (retval)
  		goto out_frames;	
  	retval = ext4_handle_dirty_dirent_node(handle, dir, bh2);
  	if (retval)
  		goto out_frames;	
  
  	de = do_split(handle, dir, &bh2, frames, frame, &hinfo, NULL, &retval);
  	if (!de) {
  		goto out_frames;
  	}
  
  	retval = add_dirent_to_buf(handle, dentry, inode, de, bh2);
  out_frames:
  	/*
  	 * 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.
  	 */
  	if (retval)
  		ext4_mark_inode_dirty(handle, dir);
  	dx_release(frames);
  	brelse(bh2);
  	return retval;
  }
  
  /* update ".." for hash-indexed directory, split the item "." if necessary */
  static int ext4_update_dotdot(handle_t *handle, struct dentry *dentry,
  			      struct inode *inode)
  {
  	struct inode *dir = dentry->d_parent->d_inode;
  	struct buffer_head *dir_block;
  	struct ext4_dir_entry_2 *de;
  	int len, journal = 0, err = 0;
  	int dlen = 0;
  	char *data;
  
  	if (IS_ERR(handle))
  		return PTR_ERR(handle);
  
  	if (IS_DIRSYNC(dir))
  		handle->h_sync = 1;
  
  	dir_block = ext4_bread(handle, dir, 0, 0, &err);
  	if (!dir_block)
  		goto out;
  
  	de = (struct ext4_dir_entry_2 *)dir_block->b_data;
  	/* the first item must be "." */
  	assert(de->name_len == 1 && de->name[0] == '.');
  	len = le16_to_cpu(de->rec_len);
  	assert(len >= __EXT4_DIR_REC_LEN(1));
  	if (len > __EXT4_DIR_REC_LEN(1)) {
  		BUFFER_TRACE(dir_block, "get_write_access");
  		err = ext4_journal_get_write_access(handle, dir_block);
  		if (err)
  			goto out_journal;
  
  		journal = 1;
  		de->rec_len = cpu_to_le16(EXT4_DIR_REC_LEN(de));
  	}
  
  	len -= EXT4_DIR_REC_LEN(de);
  	data = ext4_dentry_get_data(dir->i_sb,
  			(struct ext4_dentry_param *)dentry->d_fsdata);
  	if (data)
  		dlen = *data + 1;
  	assert(len == 0 || len >= __EXT4_DIR_REC_LEN(2 + dlen));
  
  	de = (struct ext4_dir_entry_2 *)
  			((char *) de + le16_to_cpu(de->rec_len));
  	if (!journal) {
  		BUFFER_TRACE(dir_block, "get_write_access");
  		err = ext4_journal_get_write_access(handle, dir_block);
  		if (err)
  			goto out_journal;
  	}
  
  	de->inode = cpu_to_le32(inode->i_ino);
  	if (len > 0)
  		de->rec_len = cpu_to_le16(len);
  	else
  		assert(le16_to_cpu(de->rec_len) >= __EXT4_DIR_REC_LEN(2));
  	de->name_len = 2;
  	strcpy(de->name, "..");
  	if (data != NULL && ext4_get_dirent_data_len(de) >= dlen) {
  		de->name[2] = 0;
  		memcpy(&de->name[2 + 1], data, *data);
  		ext4_set_de_type(dir->i_sb, de, S_IFDIR);
  		de->file_type |= EXT4_DIRENT_LUFID;
  	}
  
  out_journal:
  	if (journal) {
  		BUFFER_TRACE(dir_block, "call ext4_handle_dirty_metadata");
  		err = ext4_handle_dirty_dirent_node(handle, dir, dir_block);
  		ext4_mark_inode_dirty(handle, dir);
  	}
  	brelse(dir_block);
  
  out:
  	return err;
  }
  
  /*
   *	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.
   */
  int __ext4_add_entry(handle_t *handle, struct dentry *dentry,
  		      struct inode *inode, struct htree_lock *lck)
  {
  	struct inode *dir = dentry->d_parent->d_inode;
  	struct buffer_head *bh = NULL;
  	struct ext4_dir_entry_2 *de;
  	struct ext4_dir_entry_tail *t;
  	struct super_block *sb;
  	int	retval;
  	int	dx_fallback=0;
  	unsigned blocksize;
  	ext4_lblk_t block, blocks;
  	int	csum_size = 0;
  
  	if (ext4_has_metadata_csum(inode->i_sb))
  		csum_size = sizeof(struct ext4_dir_entry_tail);
  
  	sb = dir->i_sb;
  	blocksize = sb->s_blocksize;
  	if (!dentry->d_name.len)
  		return -EINVAL;
  
  	if (ext4_has_inline_data(dir)) {
  		retval = ext4_try_add_inline_entry(handle, dentry, inode);
  		if (retval < 0)
  			return retval;
  		if (retval == 1) {
  			retval = 0;
  			goto out;
  		}
  	}
  
  	if (is_dx(dir)) {
  		if (dentry->d_name.len == 2 &&
  		    memcmp(dentry->d_name.name, "..", 2) == 0)
  			return ext4_update_dotdot(handle, dentry, inode);
  		retval = ext4_dx_add_entry(handle, dentry, inode, lck);
  		if (!retval || (retval != ERR_BAD_DX_DIR))
  			goto out;
  		ext4_htree_safe_relock(lck);
  		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_read_dirblock(dir, block, DIRENT);
  		if (IS_ERR(bh))
  			return PTR_ERR(bh);
  
  		retval = add_dirent_to_buf(handle, dentry, inode, NULL, bh);
  		if (retval != -ENOSPC)
  			goto out;
  
  		if (blocks == 1 && !dx_fallback &&
  		    EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_DIR_INDEX)) {
  			retval = make_indexed_dir(handle, dentry, inode, bh);
  			bh = NULL; /* make_indexed_dir releases bh */
  			goto out;
  		}
  		brelse(bh);
  	}
  	bh = ext4_append(handle, dir, &block);
  	if (IS_ERR(bh))
  		return PTR_ERR(bh);
  	de = (struct ext4_dir_entry_2 *) bh->b_data;
  	de->inode = 0;
  	de->rec_len = ext4_rec_len_to_disk(blocksize - csum_size, blocksize);
  
  	if (csum_size) {
  		t = EXT4_DIRENT_TAIL(bh->b_data, blocksize);
  		initialize_dirent_tail(t, blocksize);
  	}
  
  	retval = add_dirent_to_buf(handle, dentry, inode, de, bh);
  out:
  	brelse(bh);
  	if (retval == 0)
  		ext4_set_inode_state(inode, EXT4_STATE_NEWENTRY);
  	return retval;
  }
  EXPORT_SYMBOL(__ext4_add_entry);
  
  static unsigned long __ext4_max_dir_size(struct dx_frame *frames,
  			       struct dx_frame *frame, struct inode *dir)
  {
  	unsigned long max_dir_size;
  
  	if (EXT4_SB(dir->i_sb)->s_max_dir_size_kb) {
  		max_dir_size = EXT4_SB(dir->i_sb)->s_max_dir_size_kb << 10;
  	} else {
  		max_dir_size = EXT4_BLOCK_SIZE(dir->i_sb);
  		while (frame >= frames) {
  			max_dir_size *= dx_get_limit(frame->entries);
  			if (frame == frames)
  				break;
  			frame--;
  		}
  		/* use 75% of max dir size in average */
  		max_dir_size = max_dir_size / 4 * 3;
  	}
  	return max_dir_size;
  }
  
  /*
   * With hash tree growing, it is easy to hit ENOSPC, but it is hard
   * to predict when it will happen. let's give administrators warning
   * when reaching 3/5 and 2/3 of limit
   */
  static inline bool dir_size_in_warning_range(struct dx_frame *frames,
  					     struct dx_frame *frame,
  					     struct inode *dir)
  {
  	unsigned long size1, size2;
  	struct super_block *sb = dir->i_sb;
  
  	if (unlikely(!EXT4_SB(sb)->s_warning_dir_size))
  		EXT4_SB(sb)->s_warning_dir_size =
  			__ext4_max_dir_size(frames, frame, dir);
  
  	size1 = EXT4_SB(sb)->s_warning_dir_size / 16 * 10;
  	size1 = size1 & ~(EXT4_BLOCK_SIZE(sb) - 1);
  	size2 = EXT4_SB(sb)->s_warning_dir_size / 16 * 11;
  	size2 = size2 & ~(EXT4_BLOCK_SIZE(sb) - 1);
  	if (in_range(dir->i_size, size1, EXT4_BLOCK_SIZE(sb)) ||
  	    in_range(dir->i_size, size2, EXT4_BLOCK_SIZE(sb)))
  		return true;
  
  	return false;
  }
  
  /*
   * 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 htree_lock *lck)
  {
  	struct dx_frame frames[EXT4_HTREE_LEVEL], *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 restart;
  	int err;
  	bool ret_warn = false;
  
  again:
  	restart = 0;
  	frame = dx_probe(&dentry->d_name, dir, &hinfo, frames, lck, &err);
  	if (!frame)
  		return err;
  	entries = frame->entries;
  	at = frame->at;
  	bh = ext4_read_dirblock(dir, dx_get_block(frame->at), DIRENT);
  	if (IS_ERR(bh)) {
  		err = PTR_ERR(bh);
  		bh = NULL;
  		goto cleanup;
  	}
  
  	err = add_dirent_to_buf(handle, dentry, inode, NULL, bh);
  	if (err != -ENOSPC)
  		goto cleanup;
  
  	err = 0;
  	/* Block full, should compress but for now just split */
  	dxtrace(printk(KERN_DEBUG "using %u of %u node entries\n",
  		       dx_get_count(entries), dx_get_limit(entries)));
  
  	if (frame - frames + 1 >= ext4_dir_htree_level(sb) ||
  	    EXT4_SB(sb)->s_warning_dir_size)
  		ret_warn = dir_size_in_warning_range(frames, frame, dir);
  
  	/* Need to split index? */
  	if (dx_get_count(entries) == dx_get_limit(entries)) {
  		ext4_lblk_t newblock;
  		int levels = frame - frames + 1;
  		unsigned icount;
  		int add_level = 1;
  		struct dx_entry *entries2;
  		struct dx_node *node2;
  		struct buffer_head *bh2;
  
  		if (!ext4_htree_safe_locked(lck)) { /* retry with EX lock */
  			ext4_htree_safe_relock(lck);
  			restart = 1;
  			goto cleanup;
  		}
  		while (frame > frames) {
  			if (dx_get_count((frame - 1)->entries) <
  			    dx_get_limit((frame - 1)->entries)) {
  				add_level = 0;
  				break;
  			}
  			frame--; /* split higher index block */
  			at = frame->at;
  			entries = frame->entries;
  			restart = 1;
  		}
  		if (add_level && levels == ext4_dir_htree_level(sb)) {
  			ext4_warning(sb, "inode %lu: comm %s: index %u: reach max htree level %u",
  					 dir->i_ino, current->comm, levels,
  					 ext4_dir_htree_level(sb));
  			if (ext4_dir_htree_level(sb) < EXT4_HTREE_LEVEL) {
  				ext4_warning(sb, "Large directory feature is "
  						 "not enabled on this "
  						 "filesystem");
  			}
  			err = -ENOSPC;
  			goto cleanup;
  		}
  		icount = dx_get_count(entries);
  		bh2 = ext4_append(handle, dir, &newblock);
  		if (IS_ERR(bh2)) {
  			err = PTR_ERR(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 (!add_level) {
  			unsigned icount1 = icount/2, icount2 = icount - icount1;
  			unsigned hash2 = dx_get_hash(entries + icount1);
  			dxtrace(printk(KERN_DEBUG "Split index %i/%i\n",
  				       icount1, icount2));
  
  			BUFFER_TRACE(frame->bh, "get_write_access"); /* index root */
  			err = ext4_journal_get_write_access(handle,
  							    (frame - 1)->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(frame - 1, hash2, newblock);
  			dxtrace(dx_show_index("node", frame->entries));
  			dxtrace(dx_show_index("node",
  			       ((struct dx_node *)bh2->b_data)->entries));
  			err = ext4_handle_dirty_dx_node(handle, dir, bh2);
  			if (err)
  				goto journal_error;
  			brelse (bh2);
  			ext4_handle_dirty_dirent_node(handle, dir,
  						      (frame - 1)->bh);
  			if (restart) {
  				ext4_handle_dirty_dirent_node(handle, dir,
  							      frame->bh);
  				goto cleanup;
  			}
  		} else {
  			struct dx_root_info *info;
  
  			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);
  			info = dx_get_dx_info((struct ext4_dir_entry_2 *)
  					      frames[0].bh->b_data);
  			info->indirect_levels += 1;
  			dxtrace(printk(KERN_DEBUG
  				       "Creating %d level index...\n",
  				       info->indirect_levels));
  			ext4_handle_dirty_dirent_node(handle, dir, frame->bh);
  			ext4_handle_dirty_dirent_node(handle, dir, bh2);
  			brelse(bh2);
  			restart = 1;
  			goto cleanup;
  		}
  	} else if (!ext4_htree_dx_locked(lck)) {
  		struct ext4_dir_lock_data *ld = ext4_htree_lock_data(lck);
  
  		/* not well protected, require DX lock */
  		ext4_htree_dx_need_lock(lck);
  		at = frame > frames ? (frame - 1)->at : NULL;
  
  		/* NB: no risk of deadlock because it's just a try.
  		 *
  		 * NB: we check ld_count for twice, the first time before
  		 * having DX lock, the second time after holding DX lock.
  		 *
  		 * NB: We never free blocks for directory so far, which
  		 * means value returned by dx_get_count() should equal to
  		 * ld->ld_count if nobody split any DE-block under @at,
  		 * and ld->ld_at still points to valid dx_entry. */
  		if ((ld->ld_count != dx_get_count(entries)) ||
  		    !ext4_htree_dx_lock_try(lck, at) ||
  		    (ld->ld_count != dx_get_count(entries))) {
  			restart = 1;
  			goto cleanup;
  		}
  		/* OK, I've got DX lock and nothing changed */
  		frame->at = ld->ld_at;
  	}
  	de = do_split(handle, dir, &bh, frames, frame, &hinfo, lck, &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:
  	ext4_htree_dx_unlock(lck);
  	ext4_htree_de_unlock(lck);
  	brelse(bh);
  	dx_release(frames);
  	/* @restart is true means htree-path has been changed, we need to
  	 * repeat dx_probe() to find out valid htree-path */
  	if (restart && err == 0)
  		goto again;
  	if (err == 0 && ret_warn)
  		err = -ENOBUFS;
  	return err;
  }
  
  /*
   * ext4_generic_delete_entry deletes a directory entry by merging it
   * with the previous entry
   */
  int ext4_generic_delete_entry(handle_t *handle,
  			      struct inode *dir,
  			      struct ext4_dir_entry_2 *de_del,
  			      struct buffer_head *bh,
  			      void *entry_buf,
  			      int buf_size,
  			      int csum_size)
  {
  	struct ext4_dir_entry_2 *de, *pde;
  	unsigned int blocksize = dir->i_sb->s_blocksize;
  	int i;
  
  	i = 0;
  	pde = NULL;
  	de = (struct ext4_dir_entry_2 *)entry_buf;
  	while (i < buf_size - csum_size) {
  		if (ext4_check_dir_entry(dir, NULL, de, bh,
  					 bh->b_data, bh->b_size, i))
  			return -EIO;
  		if (de == de_del)  {
  			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++;
  			return 0;
  		}
  		i += ext4_rec_len_from_disk(de->rec_len, blocksize);
  		pde = de;
  		de = ext4_next_entry(de, blocksize);
  	}
  	return -ENOENT;
  }
  
  int ext4_delete_entry(handle_t *handle,
  			     struct inode *dir,
  			     struct ext4_dir_entry_2 *de_del,
  			     struct buffer_head *bh)
  {
  	int err, csum_size = 0;
  
  	if (ext4_has_inline_data(dir)) {
  		int has_inline_data = 1;
  		err = ext4_delete_inline_entry(handle, dir, de_del, bh,
  					       &has_inline_data);
  		if (has_inline_data)
  			return err;
  	}
  
  	if (ext4_has_metadata_csum(dir->i_sb))
  		csum_size = sizeof(struct ext4_dir_entry_tail);
  
  	BUFFER_TRACE(bh, "get_write_access");
  	err = ext4_journal_get_write_access(handle, bh);
  	if (unlikely(err))
  		goto out;
  
  	err = ext4_generic_delete_entry(handle, dir, de_del,
  					bh, bh->b_data,
  					dir->i_sb->s_blocksize, csum_size);
  	if (err)
  		goto out;
  
  	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
  	err = ext4_handle_dirty_dirent_node(handle, dir, bh);
  	if (unlikely(err))
  		goto out;
  
  	return 0;
  out:
  	if (err != -ENOENT)
  		ext4_std_error(dir->i_sb, err);
  	return err;
  }
  EXPORT_SYMBOL(ext4_delete_entry);
  /*
   * DIR_NLINK feature is set if 1) nlinks > EXT4_LINK_MAX or 2) nlinks == 2,
   * since this indicates that nlinks count was previously 1.
   */
  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);
  		}
  	}
  }
  EXPORT_SYMBOL(ext4_inc_count);
  
  /*
   * If a directory had nlink == 1, then we should let it be 1. This indicates
   * directory has >EXT4_LINK_MAX subdirs.
   */
  void ext4_dec_count(handle_t *handle, struct inode *inode)
  {
  	if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
  		drop_nlink(inode);
  }
  EXPORT_SYMBOL(ext4_dec_count);
  
  
  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);
  		unlock_new_inode(inode);
  		d_instantiate(dentry, inode);
  		return 0;
  	}
  	drop_nlink(inode);
  	unlock_new_inode(inode);
  	iput(inode);
  	return err;
  }
  
   /* Return locked inode, then the caller can modify the inode's states/flags
    * before others finding it. The caller should unlock the inode by itself. */
  struct inode *ext4_create_inode(handle_t *handle, struct inode *dir, int mode)
  {
  	struct inode *inode;
  
  	inode = ext4_new_inode(handle, dir, mode, NULL, 0, NULL);
  	if (!IS_ERR(inode)) {
  		if (S_ISCHR(mode) || S_ISBLK(mode) || S_ISFIFO(mode)) {
  #ifdef CONFIG_LDISKFS_FS_XATTR
  			inode->i_op = &ext4_special_inode_operations;
  #endif
  		} else {
  			inode->i_op = &ext4_file_inode_operations;
  			inode->i_fop = &ext4_file_operations.kabi_fops;
  			ext4_set_aops(inode);
  		}
  	}
  	return inode;
  }
  EXPORT_SYMBOL(ext4_create_inode);
  
  /*
   * 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,
  		       bool excl)
  {
  	handle_t *handle;
  	struct inode *inode;
  	int err, credits, retries = 0;
  
  	dquot_initialize(dir);
  
  	credits = (EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
  		   EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3);
  retry:
  	inode = ext4_new_inode_start_handle(dir, mode, &dentry->d_name, 0,
  					    NULL, EXT4_HT_DIR, credits);
  	handle = ext4_journal_current_handle();
  	err = PTR_ERR(inode);
  	if (!IS_ERR(inode)) {
  		inode->i_op = &ext4_file_inode_operations;
  		inode->i_fop = &ext4_file_operations.kabi_fops;
  		ext4_set_aops(inode);
  		err = ext4_add_nondir(handle, dentry, inode);
  		if (!err && IS_DIRSYNC(dir))
  			ext4_handle_sync(handle);
  	}
  	if (handle)
  		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,
  		      umode_t mode, dev_t rdev)
  {
  	handle_t *handle;
  	struct inode *inode;
  	int err, credits, retries = 0;
  
  	if (!new_valid_dev(rdev))
  		return -EINVAL;
  
  	dquot_initialize(dir);
  
  	credits = (EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
  		   EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3);
  retry:
  	inode = ext4_new_inode_start_handle(dir, mode, &dentry->d_name, 0,
  					    NULL, EXT4_HT_DIR, credits);
  	handle = ext4_journal_current_handle();
  	err = PTR_ERR(inode);
  	if (!IS_ERR(inode)) {
  		init_special_inode(inode, inode->i_mode, rdev);
  		inode->i_op = &ext4_special_inode_operations;
  		err = ext4_add_nondir(handle, dentry, inode);
  		if (!err && IS_DIRSYNC(dir))
  			ext4_handle_sync(handle);
  	}
  	if (handle)
  		ext4_journal_stop(handle);
  	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
  		goto retry;
  	return err;
  }
  
  static int ext4_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
  {
  	handle_t *handle;
  	struct inode *inode;
  	int err, retries = 0;
  
  	dquot_initialize(dir);
  
  retry:
  	inode = ext4_new_inode_start_handle(dir, mode,
  					    NULL, 0, NULL,
  					    EXT4_HT_DIR,
  			EXT4_MAXQUOTAS_INIT_BLOCKS(dir->i_sb) +
  			  4 + EXT4_XATTR_TRANS_BLOCKS);
  	handle = ext4_journal_current_handle();
  	err = PTR_ERR(inode);
  	if (!IS_ERR(inode)) {
  		inode->i_op = &ext4_file_inode_operations;
  		inode->i_fop = &ext4_file_operations.kabi_fops;
  		ext4_set_aops(inode);
  		d_tmpfile(dentry, inode);
  		err = ext4_orphan_add(handle, inode);
  		if (err)
  			goto err_unlock_inode;
  		mark_inode_dirty(inode);
  		unlock_new_inode(inode);
  	}
  	if (handle)
  		ext4_journal_stop(handle);
  	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
  		goto retry;
  	return err;
  err_unlock_inode:
  	ext4_journal_stop(handle);
  	unlock_new_inode(inode);
  	return err;
  }
  
  struct tp_block {
  	struct inode *inode;
  	void *data1;
  	void *data2;
  };
  
  struct ext4_dir_entry_2 *ext4_init_dot_dotdot(struct inode *inode,
  			  struct ext4_dir_entry_2 *de,
  			  int blocksize, int csum_size,
  			  unsigned int parent_ino, int dotdot_real_len)
  {
  	void *data1 = NULL, *data2 = NULL;
  	int dot_reclen = 0;
  
  	if (dotdot_real_len == 10) {
  		struct tp_block *tpb = (struct tp_block *)inode;
  		data1 = tpb->data1;
  		data2 = tpb->data2;
  		inode = tpb->inode;
  		dotdot_real_len = 0;
  	}
  	de->inode = cpu_to_le32(inode->i_ino);
  	de->name_len = 1;
  	strcpy(de->name, ".");
  	ext4_set_de_type(inode->i_sb, de, S_IFDIR);
  
  	/* get packed fid data*/
  	data1 = ext4_dentry_get_data(inode->i_sb,
  				(struct ext4_dentry_param *) data1);
  	if (data1) {
  		de->name[1] = 0;
  		memcpy(&de->name[2], data1, *(char *) data1);
  		de->file_type |= EXT4_DIRENT_LUFID;
  	}
  	de->rec_len = cpu_to_le16(EXT4_DIR_REC_LEN(de));
  	dot_reclen = cpu_to_le16(de->rec_len);
  	de = ext4_next_entry(de, blocksize);
  	de->inode = cpu_to_le32(parent_ino);
  	de->name_len = 2;
  	strcpy(de->name, "..");
  	ext4_set_de_type(inode->i_sb, de, S_IFDIR);
  	data2 = ext4_dentry_get_data(inode->i_sb,
  			(struct ext4_dentry_param *) data2);
  	if (data2) {
  		de->name[2] = 0;
  		memcpy(&de->name[3], data2, *(char *) data2);
  		de->file_type |= EXT4_DIRENT_LUFID;
  	}
  	if (!dotdot_real_len)
  		de->rec_len = ext4_rec_len_to_disk(blocksize -
  					(csum_size + dot_reclen),
  					blocksize);
  	else
  		de->rec_len = ext4_rec_len_to_disk(
  				EXT4_DIR_REC_LEN(de), blocksize);
  
  	return ext4_next_entry(de, blocksize);
  }
  
  static int ext4_init_new_dir(handle_t *handle, struct inode *dir,
  			     struct inode *inode,
  			     const void *data1, const void *data2)
  {
  	struct tp_block param;
  	struct buffer_head *dir_block = NULL;
  	struct ext4_dir_entry_2 *de;
  	struct ext4_dir_entry_tail *t;
  	ext4_lblk_t block = 0;
  	unsigned int blocksize = dir->i_sb->s_blocksize;
  	int csum_size = 0;
  	int err;
  
  	if (ext4_has_metadata_csum(dir->i_sb))
  		csum_size = sizeof(struct ext4_dir_entry_tail);
  
  	if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
  		err = ext4_try_create_inline_dir(handle, dir, inode);
  		if (err < 0 && err != -ENOSPC)
  			goto out;
  		if (!err)
  			goto out;
  	}
  
  	inode->i_size = 0;
  	dir_block = ext4_append(handle, inode, &block);
  	if (IS_ERR(dir_block))
  		return PTR_ERR(dir_block);
  	de = (struct ext4_dir_entry_2 *)dir_block->b_data;
  	param.inode = inode;
  	param.data1 = (void *)data1;
  	param.data2 = (void *)data2;
  	ext4_init_dot_dotdot((struct inode *)(&param), de, blocksize,
  			     csum_size, dir->i_ino, 10);
  	set_nlink(inode, 2);
  	if (csum_size) {
  		t = EXT4_DIRENT_TAIL(dir_block->b_data, blocksize);
  		initialize_dirent_tail(t, blocksize);
  	}
  
  	BUFFER_TRACE(dir_block, "call ext4_handle_dirty_metadata");
  	err = ext4_handle_dirty_dirent_node(handle, inode, dir_block);
  	if (err)
  		goto out;
  	set_buffer_verified(dir_block);
  out:
  	brelse(dir_block);
  	return err;
  }
  
  /* Initialize @inode as a subdirectory of @dir, and add the
   * "." and ".." entries into the first directory block. */
  int ext4_add_dot_dotdot(handle_t *handle, struct inode *dir,
  			struct inode *inode,
  			const void *data1, const void *data2)
  {
  	int rc;
  
  	if (IS_ERR(handle))
  		return PTR_ERR(handle);
  
  	if (IS_DIRSYNC(dir))
  		ext4_handle_sync(handle);
  
  	inode->i_op = &ext4_dir_inode_operations.ops;
  	inode->i_fop = &ext4_dir_operations;
  	rc = ext4_init_new_dir(handle, dir, inode, data1, data2);
  	if (!rc)
  		rc = ext4_mark_inode_dirty(handle, inode);
  	return rc;
  }
  EXPORT_SYMBOL(ext4_add_dot_dotdot);
  
  static int ext4_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
  {
  	handle_t *handle;
  	struct inode *inode;
  	int err, credits, retries = 0;
  
  	if (EXT4_DIR_LINK_MAX(dir))
  		return -EMLINK;
  
  	dquot_initialize(dir);
  
  	credits = (EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
  		   EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3);
  retry:
  	inode = ext4_new_inode_start_handle(dir, S_IFDIR | mode,
  					    &dentry->d_name,
  					    0, NULL, EXT4_HT_DIR, credits);
  	handle = ext4_journal_current_handle();
  	err = PTR_ERR(inode);
  	if (IS_ERR(inode))
  		goto out_stop;
  
  	inode->i_op = &ext4_dir_inode_operations.ops;
  	inode->i_fop = &ext4_dir_operations;
  	inode->i_flags |= S_IOPS_WRAPPER;
  	err = ext4_init_new_dir(handle, dir, inode, NULL, NULL);
  	if (err)
  		goto out_clear_inode;
  	err = ext4_mark_inode_dirty(handle, inode);
  	if (!err)
  		err = ext4_add_entry(handle, dentry, inode);
  	if (err) {
  out_clear_inode:
  		clear_nlink(inode);
  		unlock_new_inode(inode);
  		ext4_mark_inode_dirty(handle, inode);
  		iput(inode);
  		goto out_stop;
  	}
  	ext4_inc_count(handle, dir);
  	ext4_update_dx_flag(dir);
  	err = ext4_mark_inode_dirty(handle, dir);
  	if (err)
  		goto out_clear_inode;
  	unlock_new_inode(inode);
  	d_instantiate(dentry, inode);
  	if (IS_DIRSYNC(dir))
  		ext4_handle_sync(handle);
  
  out_stop:
  	if (handle)
  		ext4_journal_stop(handle);
  	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
  		goto retry;
  	return err;
  }
  
  /*
   * routine to check that the specified directory is empty (for rmdir)
   */
  static int empty_dir(struct inode *inode)
  {
  	unsigned int offset;
  	struct buffer_head *bh;
  	struct ext4_dir_entry_2 *de, *de1;
  	struct super_block *sb;
  	int err = 0;
  
  	if (ext4_has_inline_data(inode)) {
  		int has_inline_data = 1;
  
  		err = empty_inline_dir(inode, &has_inline_data);
  		if (has_inline_data)
  			return err;
  	}
  
  	sb = inode->i_sb;
  	if (inode->i_size < __EXT4_DIR_REC_LEN(1) + __EXT4_DIR_REC_LEN(2)) {
  		EXT4_ERROR_INODE(inode, "invalid size");
  		return 1;
  	}
  	bh = ext4_read_dirblock(inode, 0, EITHER);
  	if (IS_ERR(bh))
  		return 1;
  
  	de = (struct ext4_dir_entry_2 *) bh->b_data;
  	de1 = ext4_next_entry(de, sb->s_blocksize);
  	if (le32_to_cpu(de->inode) != inode->i_ino ||
  			!le32_to_cpu(de1->inode) ||
  			strcmp(".", de->name) ||
  			strcmp("..", de1->name)) {
  		ext4_warning(inode->i_sb,
  			     "bad directory (dir #%lu) - no `.' or `..'",
  			     inode->i_ino);
  		brelse(bh);
  		return 1;
  	}
  	offset = ext4_rec_len_from_disk(de->rec_len, sb->s_blocksize) +
  		 ext4_rec_len_from_disk(de1->rec_len, sb->s_blocksize);
  	de = ext4_next_entry(de1, sb->s_blocksize);
  	while (offset < inode->i_size) {
  		if ((void *) de >= (void *) (bh->b_data+sb->s_blocksize)) {
  			unsigned int lblock;
  			err = 0;
  			brelse(bh);
  			lblock = offset >> EXT4_BLOCK_SIZE_BITS(sb);
  			bh = ext4_read_dirblock(inode, lblock, EITHER);
  			if (IS_ERR(bh))
  				return 1;
  			de = (struct ext4_dir_entry_2 *) bh->b_data;
  		}
  		if (ext4_check_dir_entry(inode, NULL, de, bh,
  					 bh->b_data, bh->b_size, offset)) {
  			de = (struct ext4_dir_entry_2 *)(bh->b_data +
  							 sb->s_blocksize);
  			offset = (offset | (sb->s_blocksize - 1)) + 1;
  			continue;
  		}
  		if (le32_to_cpu(de->inode)) {
  			brelse(bh);
  			return 0;
  		}
  		offset += ext4_rec_len_from_disk(de->rec_len, sb->s_blocksize);
  		de = ext4_next_entry(de, sb->s_blocksize);
  	}
  	brelse(bh);
  	return 1;
  }
  
  /*
   * ext4_orphan_add() links an unlinked or truncated inode into a list of
   * such inodes, starting at the superblock, in case we crash before the
   * file is closed/deleted, or in case the inode truncate spans multiple
   * transactions and the last transaction is not recovered after a crash.
   *
   * At filesystem recovery time, we walk this list deleting unlinked
   * inodes and truncating linked inodes in ext4_orphan_cleanup().
   *
   * Orphan list manipulation functions must be called under i_mutex unless
   * we are just creating the inode or deleting it.
   */
  int ext4_orphan_add(handle_t *handle, struct inode *inode)
  {
  	struct super_block *sb = inode->i_sb;
  	struct ext4_sb_info *sbi = EXT4_SB(sb);
  	struct ext4_iloc iloc;
  	int err = 0, rc;
  	bool dirty = false;
  
  	if (!sbi->s_journal || is_bad_inode(inode))
  		return 0;
  
  	/*
  	 * Exit early if inode already is on orphan list. This is a big speedup
  	 * since we don't have to contend on the global s_orphan_lock.
  	 */
  	if (!list_empty(&EXT4_I(inode)->i_orphan))
  		return 0;
  
  	/*
  	 * Orphan handling is only valid for files with data blocks
  	 * being truncated, or files being unlinked. Note that we either
  	 * hold i_mutex, or the inode can not be referenced from outside,
  	 * so i_nlink should not be bumped due to race
  	 */
  	J_ASSERT((S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
  		  S_ISLNK(inode->i_mode)) || inode->i_nlink == 0);
  
  	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
  	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
  	if (err)
  		goto out;
  
  	err = ext4_reserve_inode_write(handle, inode, &iloc);
  	if (err)
  		goto out;
  
  	mutex_lock(&sbi->s_orphan_lock);
  	/*
  	 * Due to previous errors inode may be already a part of on-disk
  	 * orphan list. If so skip on-disk list modification.
  	 */
  	if (!NEXT_ORPHAN(inode) || NEXT_ORPHAN(inode) >
  	    (le32_to_cpu(sbi->s_es->s_inodes_count))) {
  		/* Insert this inode at the head of the on-disk orphan list */
  		NEXT_ORPHAN(inode) = le32_to_cpu(sbi->s_es->s_last_orphan);
  		sbi->s_es->s_last_orphan = cpu_to_le32(inode->i_ino);
  		dirty = true;
  	}
  	list_add(&EXT4_I(inode)->i_orphan, &sbi->s_orphan);
  	mutex_unlock(&sbi->s_orphan_lock);
  
  	if (dirty) {
  		err = ext4_handle_dirty_super(handle, sb);
  		rc = ext4_mark_iloc_dirty(handle, inode, &iloc);
  		if (!err)
  			err = rc;
  		if (err) {
  			/*
  			 * We have to remove inode from in-memory list if
  			 * addition to on disk orphan list failed. Stray orphan
  			 * list entries can cause panics at unmount time.
  			 */
  			mutex_lock(&sbi->s_orphan_lock);
  			list_del_init(&EXT4_I(inode)->i_orphan);
  			mutex_unlock(&sbi->s_orphan_lock);
  		}
  	}
  	jbd_debug(4, "superblock will point to %lu\n", inode->i_ino);
  	jbd_debug(4, "orphan inode %lu will point to %d\n",
  			inode->i_ino, NEXT_ORPHAN(inode));
  out:
  	ext4_std_error(sb, err);
  	return err;
  }
  
  /*
   * ext4_orphan_del() removes an unlinked or truncated inode from the list
   * of such inodes stored on disk, because it is finally being cleaned up.
   */
  int ext4_orphan_del(handle_t *handle, struct inode *inode)
  {
  	struct list_head *prev;
  	struct ext4_inode_info *ei = EXT4_I(inode);
  	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
  	__u32 ino_next;
  	struct ext4_iloc iloc;
  	int err = 0;
  
  	if (!sbi->s_journal && !(sbi->s_mount_state & EXT4_ORPHAN_FS))
  		return 0;
  
  	/* Do this quick check before taking global s_orphan_lock. */
  	if (list_empty(&ei->i_orphan))
  		return 0;
  
  	if (handle) {
  		/* Grab inode buffer early before taking global s_orphan_lock */
  		err = ext4_reserve_inode_write(handle, inode, &iloc);
  	}
  
  	mutex_lock(&sbi->s_orphan_lock);
  	jbd_debug(4, "remove inode %lu from orphan list\n", inode->i_ino);
  
  	prev = ei->i_orphan.prev;
  	list_del_init(&ei->i_orphan);
  
  	/* If we're on an error path, we may not have a valid
  	 * transaction handle with which to update the orphan list on
  	 * disk, but we still need to remove the inode from the linked
  	 * list in memory. */
  	if (!handle || err) {
  		mutex_unlock(&sbi->s_orphan_lock);
  		goto out_err;
  	}
  
  	ino_next = NEXT_ORPHAN(inode);
  	if (prev == &sbi->s_orphan) {
  		jbd_debug(4, "superblock will point to %u\n", ino_next);
  		BUFFER_TRACE(sbi->s_sbh, "get_write_access");
  		err = ext4_journal_get_write_access(handle, sbi->s_sbh);
  		if (err) {
  			mutex_unlock(&sbi->s_orphan_lock);
  			goto out_brelse;
  		}
  		sbi->s_es->s_last_orphan = cpu_to_le32(ino_next);
  		mutex_unlock(&sbi->s_orphan_lock);
  		err = ext4_handle_dirty_super(handle, inode->i_sb);
  	} else {
  		struct ext4_iloc iloc2;
  		struct inode *i_prev =
  			&list_entry(prev, struct ext4_inode_info, i_orphan)->vfs_inode;
  
  		jbd_debug(4, "orphan inode %lu will point to %u\n",
  			  i_prev->i_ino, ino_next);
  		err = ext4_reserve_inode_write(handle, i_prev, &iloc2);
  		if (err) {
  			mutex_unlock(&sbi->s_orphan_lock);
  			goto out_brelse;
  		}
  		NEXT_ORPHAN(i_prev) = ino_next;
  		err = ext4_mark_iloc_dirty(handle, i_prev, &iloc2);
  		mutex_unlock(&sbi->s_orphan_lock);
  	}
  	if (err)
  		goto out_brelse;
  	NEXT_ORPHAN(inode) = 0;
  	err = ext4_mark_iloc_dirty(handle, inode, &iloc);
  out_err:
  	ext4_std_error(inode->i_sb, err);
  	return err;
  
  out_brelse:
  	brelse(iloc.bh);
  	goto out_err;
  }
  
  static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
  {
  	int retval;
  	struct inode *inode;
  	struct buffer_head *bh;
  	struct ext4_dir_entry_2 *de;
  	handle_t *handle = NULL;
  
  	/* Initialize quotas before so that eventual writes go in
  	 * separate transaction */
  	dquot_initialize(dir);
  	dquot_initialize(dentry->d_inode);
  
  	retval = -ENOENT;
  	bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
  	if (IS_ERR(bh))
  		return PTR_ERR(bh);
  	if (!bh)
  		goto end_rmdir;
  
  	inode = dentry->d_inode;
  
  	retval = -EIO;
  	if (le32_to_cpu(de->inode) != inode->i_ino)
  		goto end_rmdir;
  
  	retval = -ENOTEMPTY;
  	if (!empty_dir(inode))
  		goto end_rmdir;
  
  	handle = ext4_journal_start(dir, EXT4_HT_DIR,
  				    EXT4_DATA_TRANS_BLOCKS(dir->i_sb));
  	if (IS_ERR(handle)) {
  		retval = PTR_ERR(handle);
  		handle = NULL;
  		goto end_rmdir;
  	}
  
  	if (IS_DIRSYNC(dir))
  		ext4_handle_sync(handle);
  
  	retval = ext4_delete_entry(handle, dir, de, bh);
  	if (retval)
  		goto end_rmdir;
  	if (!EXT4_DIR_LINK_EMPTY(inode))
  		ext4_warning(inode->i_sb,
  			     "empty directory has too many links (%d)",
  			     inode->i_nlink);
  	inode->i_version++;
  	clear_nlink(inode);
  	/* There's no need to set i_disksize: the fact that i_nlink is
  	 * zero will ensure that the right thing happens during any
  	 * recovery. */
  	inode->i_size = 0;
  	ext4_orphan_add(handle, inode);
  	inode->i_ctime = dir->i_ctime = dir->i_mtime = ext4_current_time(inode);
  	ext4_mark_inode_dirty(handle, inode);
  	ext4_dec_count(handle, dir);
  	ext4_update_dx_flag(dir);
  	ext4_mark_inode_dirty(handle, dir);
  
  end_rmdir:
  	brelse(bh);
  	if (handle)
  		ext4_journal_stop(handle);
  	return retval;
  }
  
  static int ext4_unlink(struct inode *dir, struct dentry *dentry)
  {
  	int retval;
  	struct inode *inode;
  	struct buffer_head *bh;
  	struct ext4_dir_entry_2 *de;
  	handle_t *handle = NULL;
  
  	trace_ext4_unlink_enter(dir, dentry);
  	/* Initialize quotas before so that eventual writes go
  	 * in separate transaction */
  	dquot_initialize(dir);
  	dquot_initialize(dentry->d_inode);
  
  	retval = -ENOENT;
  	bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
  	if (IS_ERR(bh))
  		return PTR_ERR(bh);
  	if (!bh)
  		goto end_unlink;
  
  	inode = dentry->d_inode;
  
  	retval = -EIO;
  	if (le32_to_cpu(de->inode) != inode->i_ino)
  		goto end_unlink;
  
  	handle = ext4_journal_start(dir, EXT4_HT_DIR,
  				    EXT4_DATA_TRANS_BLOCKS(dir->i_sb));
  	if (IS_ERR(handle)) {
  		retval = PTR_ERR(handle);
  		handle = NULL;
  		goto end_unlink;
  	}
  
  	if (IS_DIRSYNC(dir))
  		ext4_handle_sync(handle);
  
  	if (!inode->i_nlink) {
  		ext4_warning(inode->i_sb,
  			     "Deleting nonexistent file (%lu), %d",
  			     inode->i_ino, inode->i_nlink);
  		set_nlink(inode, 1);
  	}
  	retval = ext4_delete_entry(handle, dir, de, bh);
  	if (retval)
  		goto end_unlink;
  	dir->i_ctime = dir->i_mtime = ext4_current_time(dir);
  	ext4_update_dx_flag(dir);
  	ext4_mark_inode_dirty(handle, dir);
  	drop_nlink(inode);
  	if (!inode->i_nlink)
  		ext4_orphan_add(handle, inode);
  	inode->i_ctime = ext4_current_time(inode);
  	ext4_mark_inode_dirty(handle, inode);
  
  end_unlink:
  	brelse(bh);
  	if (handle)
  		ext4_journal_stop(handle);
  	trace_ext4_unlink_exit(dentry, retval);
  	return retval;
  }
  
  static int ext4_symlink(struct inode *dir,
  			struct dentry *dentry, const char *symname)
  {
  	handle_t *handle;
  	struct inode *inode;
  	int l, err, retries = 0;
  	int credits;
  
  	l = strlen(symname)+1;
  	if (l > dir->i_sb->s_blocksize)
  		return -ENAMETOOLONG;
  
  	dquot_initialize(dir);
  
  	if (l > EXT4_N_BLOCKS * 4) {
  		/*
  		 * For non-fast symlinks, we just allocate inode and put it on
  		 * orphan list in the first transaction => we need bitmap,
  		 * group descriptor, sb, inode block, quota blocks, and
  		 * possibly selinux xattr blocks.
  		 */
  		credits = 4 + EXT4_MAXQUOTAS_INIT_BLOCKS(dir->i_sb) +
  			  EXT4_XATTR_TRANS_BLOCKS;
  	} else {
  		/*
  		 * Fast symlink. We have to add entry to directory
  		 * (EXT4_DATA_TRANS_BLOCKS + EXT4_INDEX_EXTRA_TRANS_BLOCKS),
  		 * allocate new inode (bitmap, group descriptor, inode block,
  		 * quota blocks, sb is already counted in previous macros).
  		 */
  		credits = EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
  			  EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3;
  	}
  retry:
  	inode = ext4_new_inode_start_handle(dir, S_IFLNK|S_IRWXUGO,
  					    &dentry->d_name, 0, NULL,
  					    EXT4_HT_DIR, credits);
  	handle = ext4_journal_current_handle();
  	err = PTR_ERR(inode);
  	if (IS_ERR(inode))
  		goto out_stop;
  
  	if (l > EXT4_N_BLOCKS * 4) {
  		inode->i_op = &ext4_symlink_inode_operations;
  		ext4_set_aops(inode);
  		/*
  		 * We cannot call page_symlink() with transaction started
  		 * because it calls into ext4_write_begin() which can wait
  		 * for transaction commit if we are running out of space
  		 * and thus we deadlock. So we have to stop transaction now
  		 * and restart it when symlink contents is written.
  		 * 
  		 * To keep fs consistent in case of crash, we have to put inode
  		 * to orphan list in the mean time.
  		 */
  		drop_nlink(inode);
  		err = ext4_orphan_add(handle, inode);
  		ext4_journal_stop(handle);
  		if (err)
  			goto err_drop_inode;
  		err = __page_symlink(inode, symname, l, 1);
  		if (err)
  			goto err_drop_inode;
  		/*
  		 * Now inode is being linked into dir (EXT4_DATA_TRANS_BLOCKS
  		 * + EXT4_INDEX_EXTRA_TRANS_BLOCKS), inode is also modified
  		 */
  		handle = ext4_journal_start(dir, EXT4_HT_DIR,
  				EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
  				EXT4_INDEX_EXTRA_TRANS_BLOCKS + 1);
  		if (IS_ERR(handle)) {
  			err = PTR_ERR(handle);
  			goto err_drop_inode;
  		}
  		set_nlink(inode, 1);
  		err = ext4_orphan_del(handle, inode);
  		if (err) {
  			ext4_journal_stop(handle);
  			clear_nlink(inode);
  			goto err_drop_inode;
  		}
  	} else {
  		/* clear the extent format for fast symlink */
  		ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
  		inode->i_op = &ext4_fast_symlink_inode_operations;
  		memcpy((char *)&EXT4_I(inode)->i_data, symname, l);
  		inode->i_size = l-1;
  	}
  	EXT4_I(inode)->i_disksize = inode->i_size;
  	err = ext4_add_nondir(handle, dentry, inode);
  	if (!err && IS_DIRSYNC(dir))
  		ext4_handle_sync(handle);
  
  out_stop:
  	if (handle)
  		ext4_journal_stop(handle);
  	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
  		goto retry;
  	return err;
  err_drop_inode:
  	unlock_new_inode(inode);
  	iput(inode);
  	return err;
  }
  
  static int ext4_link(struct dentry *old_dentry,
  		     struct inode *dir, struct dentry *dentry)
  {
  	handle_t *handle;
  	struct inode *inode = old_dentry->d_inode;
  	int err, retries = 0;
  
  	if (inode->i_nlink >= EXT4_LINK_MAX)
  		return -EMLINK;
  
  	if ((ext4_test_inode_flag(dir, EXT4_INODE_PROJINHERIT)) &&
  	    (!projid_eq(EXT4_I(dir)->i_projid,
  			EXT4_I(old_dentry->d_inode)->i_projid)))
  		return -EXDEV;
  
  	dquot_initialize(dir);
  
  retry:
  	handle = ext4_journal_start(dir, EXT4_HT_DIR,
  		(EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
  		 EXT4_INDEX_EXTRA_TRANS_BLOCKS) + 1);
  	if (IS_ERR(handle))
  		return PTR_ERR(handle);
  
  	if (IS_DIRSYNC(dir))
  		ext4_handle_sync(handle);
  
  	inode->i_ctime = ext4_current_time(inode);
  	ext4_inc_count(handle, inode);
  	ihold(inode);
  
  	err = ext4_add_entry(handle, dentry, inode);
  	if (!err) {
  		ext4_mark_inode_dirty(handle, inode);
  		/* this can happen only for tmpfile being
  		 * linked the first time
  		 */
  		if (inode->i_nlink == 1)
  			ext4_orphan_del(handle, inode);
  		d_instantiate(dentry, inode);
  	} else {
  		drop_nlink(inode);
  		iput(inode);
  	}
  	ext4_journal_stop(handle);
  	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
  		goto retry;
  	return err;
  }
  
  
  /*
   * Try to find buffer head where contains the parent block.
   * It should be the inode block if it is inlined or the 1st block
   * if it is a normal dir.
   */
  static struct buffer_head *ext4_get_first_dir_block(handle_t *handle,
  					struct inode *inode,
  					int *retval,
  					struct ext4_dir_entry_2 **parent_de,
  					int *inlined)
  {
  	struct buffer_head *bh;
  
  	if (!ext4_has_inline_data(inode)) {
  		bh = ext4_read_dirblock(inode, 0, EITHER);
  		if (IS_ERR(bh)) {
  			*retval = PTR_ERR(bh);
  			return NULL;
  		}
  		*parent_de = ext4_next_entry(
  					(struct ext4_dir_entry_2 *)bh->b_data,
  					inode->i_sb->s_blocksize);
  		return bh;
  	}
  
  	*inlined = 1;
  	return ext4_get_first_inline_block(inode, parent_de, retval);
  }
  
  struct ext4_renament {
  	struct inode *dir;
  	struct dentry *dentry;
  	struct inode *inode;
  	bool is_dir;
  	int dir_nlink_delta;
  
  	/* entry for "dentry" */
  	struct buffer_head *bh;
  	struct ext4_dir_entry_2 *de;
  	int inlined;
  
  	/* entry for ".." in inode if it's a directory */
  	struct buffer_head *dir_bh;
  	struct ext4_dir_entry_2 *parent_de;
  	int dir_inlined;
  };
  
  static int ext4_rename_dir_prepare(handle_t *handle, struct ext4_renament *ent)
  {
  	int retval;
  
  	ent->dir_bh = ext4_get_first_dir_block(handle, ent->inode,
  					      &retval, &ent->parent_de,
  					      &ent->dir_inlined);
  	if (!ent->dir_bh)
  		return retval;
  	if (le32_to_cpu(ent->parent_de->inode) != ent->dir->i_ino)
  		return -EIO;
  	BUFFER_TRACE(ent->dir_bh, "get_write_access");
  	return ext4_journal_get_write_access(handle, ent->dir_bh);
  }
  
  static int ext4_rename_dir_finish(handle_t *handle, struct ext4_renament *ent,
  				  unsigned dir_ino)
  {
  	int retval;
  
  	ent->parent_de->inode = cpu_to_le32(dir_ino);
  	BUFFER_TRACE(ent->dir_bh, "call ext4_handle_dirty_metadata");
  	if (!ent->dir_inlined) {
  		if (is_dx(ent->inode)) {
  			retval = ext4_handle_dirty_dx_node(handle,
  							   ent->inode,
  							   ent->dir_bh);
  		} else {
  			retval = ext4_handle_dirty_dirent_node(handle,
  							       ent->inode,
  							       ent->dir_bh);
  		}
  	} else {
  		retval = ext4_mark_inode_dirty(handle, ent->inode);
  	}
  	if (retval) {
  		ext4_std_error(ent->dir->i_sb, retval);
  		return retval;
  	}
  	return 0;
  }
  
  static int ext4_setent(handle_t *handle, struct ext4_renament *ent,
  		       unsigned ino, unsigned file_type)
  {
  	int retval;
  
  	BUFFER_TRACE(ent->bh, "get write access");
  	retval = ext4_journal_get_write_access(handle, ent->bh);
  	if (retval)
  		return retval;
  	ent->de->inode = cpu_to_le32(ino);
  	if (EXT4_HAS_INCOMPAT_FEATURE(ent->dir->i_sb,
  				      EXT4_FEATURE_INCOMPAT_FILETYPE))
  		ent->de->file_type = file_type;
  	ent->dir->i_version++;
  	ent->dir->i_ctime = ent->dir->i_mtime =
  		ext4_current_time(ent->dir);
  	ext4_mark_inode_dirty(handle, ent->dir);
  	BUFFER_TRACE(ent->bh, "call ext4_handle_dirty_metadata");
  	if (!ent->inlined) {
  		retval = ext4_handle_dirty_dirent_node(handle,
  						       ent->dir, ent->bh);
  		if (unlikely(retval)) {
  			ext4_std_error(ent->dir->i_sb, retval);
  			return retval;
  		}
  	}
  	brelse(ent->bh);
  	ent->bh = NULL;
  
  	return 0;
  }
  
  static int ext4_find_delete_entry(handle_t *handle, struct inode *dir,
  				  const struct qstr *d_name)
  {
  	int retval = -ENOENT;
  	struct buffer_head *bh;
  	struct ext4_dir_entry_2 *de;
  
  	bh = ext4_find_entry(dir, d_name, &de, NULL);
  	if (IS_ERR(bh))
  		return PTR_ERR(bh);
  	if (bh) {
  		retval = ext4_delete_entry(handle, dir, de, bh);
  		brelse(bh);
  	}
  	return retval;
  }
  
  static void ext4_rename_delete(handle_t *handle, struct ext4_renament *ent,
  			       int force_reread)
  {
  	int retval;
  	/*
  	 * ent->de could have moved from under us during htree split, so make
  	 * sure that we are deleting the right entry.  We might also be pointing
  	 * to a stale entry in the unused part of ent->bh so just checking inum
  	 * and the name isn't enough.
  	 */
  	if (le32_to_cpu(ent->de->inode) != ent->inode->i_ino ||
  	    ent->de->name_len != ent->dentry->d_name.len ||
  	    strncmp(ent->de->name, ent->dentry->d_name.name,
  		    ent->de->name_len) ||
  	    force_reread) {
  		retval = ext4_find_delete_entry(handle, ent->dir,
  						&ent->dentry->d_name);
  	} else {
  		retval = ext4_delete_entry(handle, ent->dir, ent->de, ent->bh);
  		if (retval == -ENOENT) {
  			retval = ext4_find_delete_entry(handle, ent->dir,
  							&ent->dentry->d_name);
  		}
  	}
  
  	if (retval) {
  		ext4_warning(ent->dir->i_sb,
  				"Deleting old file (%lu), %d, error=%d",
  				ent->dir->i_ino, ent->dir->i_nlink, retval);
  	}
  }
  
  static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent)
  {
  	if (ent->dir_nlink_delta) {
  		if (ent->dir_nlink_delta == -1)
  			ext4_dec_count(handle, ent->dir);
  		else
  			ext4_inc_count(handle, ent->dir);
  		ext4_mark_inode_dirty(handle, ent->dir);
  	}
  }
  
  static struct inode *ext4_whiteout_for_rename(struct ext4_renament *ent,
  					      int credits, handle_t **h)
  {
  	struct inode *wh;
  	handle_t *handle;
  	int retries = 0;
  
  	/*
  	 * for inode block, sb block, group summaries,
  	 * and inode bitmap
  	 */
  	credits += (EXT4_MAXQUOTAS_TRANS_BLOCKS(ent->dir->i_sb) +
  		    EXT4_XATTR_TRANS_BLOCKS + 4);
  retry:
  	wh = ext4_new_inode_start_handle(ent->dir, S_IFCHR | WHITEOUT_MODE,
  					 &ent->dentry->d_name, 0, NULL,
  					 EXT4_HT_DIR, credits);
  
  	handle = ext4_journal_current_handle();
  	if (IS_ERR(wh)) {
  		if (handle)
  			ext4_journal_stop(handle);
  		if (PTR_ERR(wh) == -ENOSPC &&
  		    ext4_should_retry_alloc(ent->dir->i_sb, &retries))
  			goto retry;
  	} else {
  		*h = handle;
  		init_special_inode(wh, wh->i_mode, WHITEOUT_DEV);
  		wh->i_op = &ext4_special_inode_operations;
  	}
  	return wh;
  }
  
  /*
   * Anybody can rename anything with this: the permission checks are left to the
   * higher-level routines.
   *
   * n.b.  old_{dentry,inode) refers to the source dentry/inode
   * while new_{dentry,inode) refers to the destination dentry/inode
   * This comes from rename(const char *oldpath, const char *newpath)
   */
  static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
  		       struct inode *new_dir, struct dentry *new_dentry,
  		       unsigned int flags)
  {
  	handle_t *handle = NULL;
  	struct ext4_renament old = {
  		.dir = old_dir,
  		.dentry = old_dentry,
  		.inode = old_dentry->d_inode,
  	};
  	struct ext4_renament new = {
  		.dir = new_dir,
  		.dentry = new_dentry,
  		.inode = new_dentry->d_inode,
  	};
  	int force_reread;
  	int retval;
  	struct inode *whiteout = NULL;
  	int credits;
  	u8 old_file_type;
  
  	if ((ext4_test_inode_flag(new_dir, EXT4_INODE_PROJINHERIT)) &&
  	    (!projid_eq(EXT4_I(new_dir)->i_projid,
  			EXT4_I(old_dentry->d_inode)->i_projid)))
  		return -EXDEV;
  
  	dquot_initialize(old.dir);
  	dquot_initialize(new.dir);
  
  	/* Initialize quotas before so that eventual writes go
  	 * in separate transaction */
  	if (new.inode)
  		dquot_initialize(new.inode);
  
  	old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL);
  	if (IS_ERR(old.bh))
  		return PTR_ERR(old.bh);
  	/*
  	 *  Check for inode number is _not_ due to possible IO errors.
  	 *  We might rmdir the source, keep it as pwd of some process
  	 *  and merrily kill the link to whatever was created under the
  	 *  same name. Goodbye sticky bit ;-<
  	 */
  	retval = -ENOENT;
  	if (!old.bh || le32_to_cpu(old.de->inode) != old.inode->i_ino)
  		goto end_rename;
  
  	new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
  				 &new.de, &new.inlined);
  	if (IS_ERR(new.bh)) {
  		retval = PTR_ERR(new.bh);
  		new.bh = NULL;
  		goto end_rename;
  	}
  	if (new.bh) {
  		if (!new.inode) {
  			brelse(new.bh);
  			new.bh = NULL;
  		}
  	}
  	if (new.inode && !test_opt(new.dir->i_sb, NO_AUTO_DA_ALLOC))
  		ext4_alloc_da_blocks(old.inode);
  
  	credits = (2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
  		   EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2);
  	if (!(flags & RENAME_WHITEOUT)) {
  		handle = ext4_journal_start(old.dir, EXT4_HT_DIR, credits);
  		if (IS_ERR(handle)) {
  			retval = PTR_ERR(handle);
  			handle = NULL;
  			goto end_rename;
  		}
  	} else {
  		whiteout = ext4_whiteout_for_rename(&old, credits, &handle);
  		if (IS_ERR(whiteout)) {
  			retval = PTR_ERR(whiteout);
  			whiteout = NULL;
  			goto end_rename;
  		}
  	}
  
  	if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
  		ext4_handle_sync(handle);
  
  	if (S_ISDIR(old.inode->i_mode)) {
  		if (new.inode) {
  			retval = -ENOTEMPTY;
  			if (!empty_dir(new.inode))
  				goto end_rename;
  		} else {
  			retval = -EMLINK;
  			if (new.dir != old.dir && EXT4_DIR_LINK_MAX(new.dir))
  				goto end_rename;
  		}
  		retval = ext4_rename_dir_prepare(handle, &old);
  		if (retval)
  			goto end_rename;
  	}
  	/*
  	 * If we're renaming a file within an inline_data dir and adding or
  	 * setting the new dirent causes a conversion from inline_data to
  	 * extents/blockmap, we need to force the dirent delete code to
  	 * re-read the directory, or else we end up trying to delete a dirent
  	 * from what is now the extent tree root (or a block map).
  	 */
  	force_reread = (new.dir->i_ino == old.dir->i_ino &&
  			ext4_test_inode_flag(new.dir, EXT4_INODE_INLINE_DATA));
  
  	old_file_type = old.de->file_type;
  	if (whiteout) {
  		/*
  		 * Do this before adding a new entry, so the old entry is sure
  		 * to be still pointing to the valid old entry.
  		 */
  		retval = ext4_setent(handle, &old, whiteout->i_ino,
  				     EXT4_FT_CHRDEV);
  		if (retval)
  			goto end_rename;
  		ext4_mark_inode_dirty(handle, whiteout);
  	}
  	if (!new.bh) {
  		retval = ext4_add_entry(handle, new.dentry, old.inode);
  		if (retval)
  			goto end_rename;
  	} else {
  		retval = ext4_setent(handle, &new,
  				     old.inode->i_ino, old_file_type);
  		if (retval)
  			goto end_rename;
  	}
  	if (force_reread)
  		force_reread = !ext4_test_inode_flag(new.dir,
  						     EXT4_INODE_INLINE_DATA);
  
  	/*
  	 * Like most other Unix systems, set the ctime for inodes on a
  	 * rename.
  	 */
  	old.inode->i_ctime = ext4_current_time(old.inode);
  	ext4_mark_inode_dirty(handle, old.inode);
  
  	if (!whiteout) {
  		/*
  		 * ok, that's it
  		 */
  		ext4_rename_delete(handle, &old, force_reread);
  	}
  
  	if (new.inode) {
  		ext4_dec_count(handle, new.inode);
  		new.inode->i_ctime = ext4_current_time(new.inode);
  	}
  	old.dir->i_ctime = old.dir->i_mtime = ext4_current_time(old.dir);
  	ext4_update_dx_flag(old.dir);
  	if (old.dir_bh) {
  		retval = ext4_rename_dir_finish(handle, &old, new.dir->i_ino);
  		if (retval)
  			goto end_rename;
  
  		ext4_dec_count(handle, old.dir);
  		if (new.inode) {
  			/* checked empty_dir above, can't have another parent,
  			 * ext4_dec_count() won't work for many-linked dirs */
  			clear_nlink(new.inode);
  		} else {
  			ext4_inc_count(handle, new.dir);
  			ext4_update_dx_flag(new.dir);
  			ext4_mark_inode_dirty(handle, new.dir);
  		}
  	}
  	ext4_mark_inode_dirty(handle, old.dir);
  	if (new.inode) {
  		ext4_mark_inode_dirty(handle, new.inode);
  		if (!new.inode->i_nlink)
  			ext4_orphan_add(handle, new.inode);
  	}
  	retval = 0;
  
  end_rename:
  	brelse(old.dir_bh);
  	brelse(old.bh);
  	brelse(new.bh);
  	if (whiteout) {
  		if (retval)
  			drop_nlink(whiteout);
  		unlock_new_inode(whiteout);
  		iput(whiteout);
  	}
  	if (handle)
  		ext4_journal_stop(handle);
  	return retval;
  }
  
  static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
  			     struct inode *new_dir, struct dentry *new_dentry)
  {
  	handle_t *handle = NULL;
  	struct ext4_renament old = {
  		.dir = old_dir,
  		.dentry = old_dentry,
  		.inode = old_dentry->d_inode,
  	};
  	struct ext4_renament new = {
  		.dir = new_dir,
  		.dentry = new_dentry,
  		.inode = new_dentry->d_inode,
  	};
  	u8 new_file_type;
  	int retval;
  
  	if ((ext4_test_inode_flag(new_dir, EXT4_INODE_PROJINHERIT) &&
  	     !projid_eq(EXT4_I(new_dir)->i_projid,
  			EXT4_I(old_dentry->d_inode)->i_projid)) ||
  	    (ext4_test_inode_flag(old_dir, EXT4_INODE_PROJINHERIT) &&
  	     !projid_eq(EXT4_I(old_dir)->i_projid,
  			EXT4_I(new_dentry->d_inode)->i_projid)))
  		return -EXDEV;
  
  	dquot_initialize(old.dir);
  	dquot_initialize(new.dir);
  
  	old.bh = ext4_find_entry(old.dir, &old.dentry->d_name,
  				 &old.de, &old.inlined);
  	/*
  	 *  Check for inode number is _not_ due to possible IO errors.
  	 *  We might rmdir the source, keep it as pwd of some process
  	 *  and merrily kill the link to whatever was created under the
  	 *  same name. Goodbye sticky bit ;-<
  	 */
  	retval = -ENOENT;
  	if (!old.bh || le32_to_cpu(old.de->inode) != old.inode->i_ino)
  		goto end_rename;
  
  	new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
  				 &new.de, &new.inlined);
  
  	/* RENAME_EXCHANGE case: old *and* new must both exist */
  	if (!new.bh || le32_to_cpu(new.de->inode) != new.inode->i_ino)
  		goto end_rename;
  
  	handle = ext4_journal_start(old.dir, EXT4_HT_DIR,
  		(2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
  		 2 * EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2));
  	if (IS_ERR(handle)) {
  		retval = PTR_ERR(handle);
  		handle = NULL;
  		goto end_rename;
  	}
  
  	if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
  		ext4_handle_sync(handle);
  
  	if (S_ISDIR(old.inode->i_mode)) {
  		old.is_dir = true;
  		retval = ext4_rename_dir_prepare(handle, &old);
  		if (retval)
  			goto end_rename;
  	}
  	if (S_ISDIR(new.inode->i_mode)) {
  		new.is_dir = true;
  		retval = ext4_rename_dir_prepare(handle, &new);
  		if (retval)
  			goto end_rename;
  	}
  
  	/*
  	 * Other than the special case of overwriting a directory, parents'
  	 * nlink only needs to be modified if this is a cross directory rename.
  	 */
  	if (old.dir != new.dir && old.is_dir != new.is_dir) {
  		old.dir_nlink_delta = old.is_dir ? -1 : 1;
  		new.dir_nlink_delta = -old.dir_nlink_delta;
  		retval = -EMLINK;
  		if ((old.dir_nlink_delta > 0 && EXT4_DIR_LINK_MAX(old.dir)) ||
  		    (new.dir_nlink_delta > 0 && EXT4_DIR_LINK_MAX(new.dir)))
  			goto end_rename;
  	}
  
  	new_file_type = new.de->file_type;
  	retval = ext4_setent(handle, &new, old.inode->i_ino, old.de->file_type);
  	if (retval)
  		goto end_rename;
  
  	retval = ext4_setent(handle, &old, new.inode->i_ino, new_file_type);
  	if (retval)
  		goto end_rename;
  
  	/*
  	 * Like most other Unix systems, set the ctime for inodes on a
  	 * rename.
  	 */
  	old.inode->i_ctime = ext4_current_time(old.inode);
  	new.inode->i_ctime = ext4_current_time(new.inode);
  	ext4_mark_inode_dirty(handle, old.inode);
  	ext4_mark_inode_dirty(handle, new.inode);
  
  	if (old.dir_bh) {
  		retval = ext4_rename_dir_finish(handle, &old, new.dir->i_ino);
  		if (retval)
  			goto end_rename;
  	}
  	if (new.dir_bh) {
  		retval = ext4_rename_dir_finish(handle, &new, old.dir->i_ino);
  		if (retval)
  			goto end_rename;
  	}
  	ext4_update_dir_count(handle, &old);
  	ext4_update_dir_count(handle, &new);
  	retval = 0;
  
  end_rename:
  	brelse(old.dir_bh);
  	brelse(new.dir_bh);
  	brelse(old.bh);
  	brelse(new.bh);
  	if (handle)
  		ext4_journal_stop(handle);
  	return retval;
  }
  
  static int ext4_rename2(struct inode *old_dir, struct dentry *old_dentry,
  			struct inode *new_dir, struct dentry *new_dentry,
  			unsigned int flags)
  {
  	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
  		return -EINVAL;
  
  	if (flags & RENAME_EXCHANGE) {
  		return ext4_cross_rename(old_dir, old_dentry,
  					 new_dir, new_dentry);
  	}
  
  	return ext4_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
  }
  
  static int ext4_rename_old(struct inode *old_dir, struct dentry *old_dentry,
  			   struct inode *new_dir, struct dentry *new_dentry)
  {
  	return ext4_rename(old_dir, old_dentry, new_dir, new_dentry, 0);
  }
  
  /*
   * directories can handle most operations...
   */
  const struct inode_operations_wrapper ext4_dir_inode_operations = {
  	.ops = {
  	.create		= ext4_create,
  	.lookup		= ext4_lookup,
  	.link		= ext4_link,
  	.unlink		= ext4_unlink,
  	.symlink	= ext4_symlink,
  	.mkdir		= ext4_mkdir,
  	.rmdir		= ext4_rmdir,
  	.mknod		= ext4_mknod,
  	.rename		= ext4_rename_old,
  	.setattr	= ext4_setattr,
  	.setxattr	= generic_setxattr,
  	.getxattr	= generic_getxattr,
  	.listxattr	= ext4_listxattr,
  	.removexattr	= generic_removexattr,
  	.get_acl	= ext4_get_acl,
  	.fiemap         = ext4_fiemap,
  	},
  	.rename2	= ext4_rename2,
  	.tmpfile	= ext4_tmpfile,
  };
  
  const struct inode_operations ext4_special_inode_operations = {
  	.setattr	= ext4_setattr,
  	.setxattr	= generic_setxattr,
  	.getxattr	= generic_getxattr,
  	.listxattr	= ext4_listxattr,
  	.removexattr	= generic_removexattr,
  	.get_acl	= ext4_get_acl,
  };
  