fs/omfs/dir.c - arm/linux - Git at Google

 /*
  * OMFS (as used by RIO Karma) directory operations.
  * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
  * Released under GPL v2.
  */

 #include <linux/fs.h>
 #include <linux/ctype.h>
 #include <linux/buffer_head.h>
 #include "omfs.h"

 static int omfs_hash(const char *name, int namelen, int mod)
 {
 	int i, hash = 0;
 	for (i = 0; i < namelen; i++)
 		hash ^= tolower(name[i]) << (i % 24);
 	return hash % mod;
 }

 /*
  * Finds the bucket for a given name and reads the containing block;
  * *ofs is set to the offset of the first list entry.
  */
 static struct buffer_head *omfs_get_bucket(struct inode *dir,
 		const char *name, int namelen, int *ofs)
 {
 	int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
 	int bucket = omfs_hash(name, namelen, nbuckets);

 	*ofs = OMFS_DIR_START + bucket * 8;
 	return omfs_bread(dir->i_sb, dir->i_ino);
 }

 static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
 				const char *name, int namelen,
 				u64 *prev_block)
 {
 	struct buffer_head *bh;
 	struct omfs_inode *oi;
 	int err = -ENOENT;
 	*prev_block = ~0;

 	while (block != ~0) {
 		bh = omfs_bread(dir->i_sb, block);
 		if (!bh) {
 			err = -EIO;
 			goto err;
 		}

 		oi = (struct omfs_inode *) bh->b_data;
 		if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
 			brelse(bh);
 			goto err;
 		}

 		if (strncmp(oi->i_name, name, namelen) == 0)
 			return bh;

 		*prev_block = block;
 		block = be64_to_cpu(oi->i_sibling);
 		brelse(bh);
 	}
 err:
 	return ERR_PTR(err);
 }

 static struct buffer_head *omfs_find_entry(struct inode *dir,
 					   const char *name, int namelen)
 {
 	struct buffer_head *bh;
 	int ofs;
 	u64 block, dummy;

 	bh = omfs_get_bucket(dir, name, namelen, &ofs);
 	if (!bh)
 		return ERR_PTR(-EIO);

 	block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
 	brelse(bh);

 	return omfs_scan_list(dir, block, name, namelen, &dummy);
 }

 int omfs_make_empty(struct inode *inode, struct super_block *sb)
 {
 	struct omfs_sb_info *sbi = OMFS_SB(sb);
 	struct buffer_head *bh;
 	struct omfs_inode *oi;

 	bh = omfs_bread(sb, inode->i_ino);
 	if (!bh)
 		return -ENOMEM;

 	memset(bh->b_data, 0, sizeof(struct omfs_inode));

 	if (S_ISDIR(inode->i_mode)) {
 		memset(&bh->b_data[OMFS_DIR_START], 0xff,
 			sbi->s_sys_blocksize - OMFS_DIR_START);
 	} else
 		omfs_make_empty_table(bh, OMFS_EXTENT_START);

 	oi = (struct omfs_inode *) bh->b_data;
 	oi->i_head.h_self = cpu_to_be64(inode->i_ino);
 	oi->i_sibling = ~cpu_to_be64(0ULL);

 	mark_buffer_dirty(bh);
 	brelse(bh);
 	return 0;
 }

 static int omfs_add_link(struct dentry *dentry, struct inode *inode)
 {
 	struct inode *dir = d_inode(dentry->d_parent);
 	const char *name = dentry->d_name.name;
 	int namelen = dentry->d_name.len;
 	struct omfs_inode *oi;
 	struct buffer_head *bh;
 	u64 block;
 	__be64 *entry;
 	int ofs;

 	/* just prepend to head of queue in proper bucket */
 	bh = omfs_get_bucket(dir, name, namelen, &ofs);
 	if (!bh)
 		goto out;

 	entry = (__be64 *) &bh->b_data[ofs];
 	block = be64_to_cpu(*entry);
 	*entry = cpu_to_be64(inode->i_ino);
 	mark_buffer_dirty(bh);
 	brelse(bh);

 	/* now set the sibling and parent pointers on the new inode */
 	bh = omfs_bread(dir->i_sb, inode->i_ino);
 	if (!bh)
 		goto out;

 	oi = (struct omfs_inode *) bh->b_data;
 	memcpy(oi->i_name, name, namelen);
 	memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
 	oi->i_sibling = cpu_to_be64(block);
 	oi->i_parent = cpu_to_be64(dir->i_ino);
 	mark_buffer_dirty(bh);
 	brelse(bh);

 	dir->i_ctime = CURRENT_TIME_SEC;

 	/* mark affected inodes dirty to rebuild checksums */
 	mark_inode_dirty(dir);
 	mark_inode_dirty(inode);
 	return 0;
 out:
 	return -ENOMEM;
 }

 static int omfs_delete_entry(struct dentry *dentry)
 {
 	struct inode *dir = d_inode(dentry->d_parent);
 	struct inode *dirty;
 	const char *name = dentry->d_name.name;
 	int namelen = dentry->d_name.len;
 	struct omfs_inode *oi;
 	struct buffer_head *bh, *bh2;
 	__be64 *entry, next;
 	u64 block, prev;
 	int ofs;
 	int err = -ENOMEM;

 	/* delete the proper node in the bucket's linked list */
 	bh = omfs_get_bucket(dir, name, namelen, &ofs);
 	if (!bh)
 		goto out;

 	entry = (__be64 *) &bh->b_data[ofs];
 	block = be64_to_cpu(*entry);

 	bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
 	if (IS_ERR(bh2)) {
 		err = PTR_ERR(bh2);
 		goto out_free_bh;
 	}

 	oi = (struct omfs_inode *) bh2->b_data;
 	next = oi->i_sibling;
 	brelse(bh2);

 	if (prev != ~0) {
 		/* found in middle of list, get list ptr */
 		brelse(bh);
 		bh = omfs_bread(dir->i_sb, prev);
 		if (!bh)
 			goto out;

 		oi = (struct omfs_inode *) bh->b_data;
 		entry = &oi->i_sibling;
 	}

 	*entry = next;
 	mark_buffer_dirty(bh);

 	if (prev != ~0) {
 		dirty = omfs_iget(dir->i_sb, prev);
 		if (!IS_ERR(dirty)) {
 			mark_inode_dirty(dirty);
 			iput(dirty);
 		}
 	}

 	err = 0;
 out_free_bh:
 	brelse(bh);
 out:
 	return err;
 }

 static int omfs_dir_is_empty(struct inode *inode)
 {
 	int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
 	struct buffer_head *bh;
 	u64 *ptr;
 	int i;

 	bh = omfs_bread(inode->i_sb, inode->i_ino);

 	if (!bh)
 		return 0;

 	ptr = (u64 *) &bh->b_data[OMFS_DIR_START];

 	for (i = 0; i < nbuckets; i++, ptr++)
 		if (*ptr != ~0)
 			break;

 	brelse(bh);
 	return *ptr != ~0;
 }

 static int omfs_remove(struct inode *dir, struct dentry *dentry)
 {
 	struct inode *inode = d_inode(dentry);
 	int ret;


 	if (S_ISDIR(inode->i_mode) &&
 	    !omfs_dir_is_empty(inode))
 		return -ENOTEMPTY;

 	ret = omfs_delete_entry(dentry);
 	if (ret)
 		return ret;

 	clear_nlink(inode);
 	mark_inode_dirty(inode);
 	mark_inode_dirty(dir);
 	return 0;
 }

 static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	int err;
 	struct inode *inode = omfs_new_inode(dir, mode);

 	if (IS_ERR(inode))
 		return PTR_ERR(inode);

 	err = omfs_make_empty(inode, dir->i_sb);
 	if (err)
 		goto out_free_inode;

 	err = omfs_add_link(dentry, inode);
 	if (err)
 		goto out_free_inode;

 	d_instantiate(dentry, inode);
 	return 0;

 out_free_inode:
 	iput(inode);
 	return err;
 }

 static int omfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	return omfs_add_node(dir, dentry, mode | S_IFDIR);
 }

 static int omfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 		bool excl)
 {
 	return omfs_add_node(dir, dentry, mode | S_IFREG);
 }

 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
 				  unsigned int flags)
 {
 	struct buffer_head *bh;
 	struct inode *inode = NULL;

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

 	bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
 	if (!IS_ERR(bh)) {
 		struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
 		ino_t ino = be64_to_cpu(oi->i_head.h_self);
 		brelse(bh);
 		inode = omfs_iget(dir->i_sb, ino);
 		if (IS_ERR(inode))
 			return ERR_CAST(inode);
 	}
 	d_add(dentry, inode);
 	return NULL;
 }

 /* sanity check block's self pointer */
 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
 	u64 fsblock)
 {
 	int is_bad;
 	u64 ino = be64_to_cpu(header->h_self);
 	is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
 		(ino > sbi->s_num_blocks));

 	if (is_bad)
 		printk(KERN_WARNING "omfs: bad hash chain detected\n");

 	return is_bad;
 }

 static bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx,
 		u64 fsblock, int hindex)
 {
 	/* follow chain in this bucket */
 	while (fsblock != ~0) {
 		struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock);
 		struct omfs_inode *oi;
 		u64 self;
 		unsigned char d_type;

 		if (!bh)
 			return true;

 		oi = (struct omfs_inode *) bh->b_data;
 		if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
 			brelse(bh);
 			return true;
 		}

 		self = fsblock;
 		fsblock = be64_to_cpu(oi->i_sibling);

 		/* skip visited nodes */
 		if (hindex) {
 			hindex--;
 			brelse(bh);
 			continue;
 		}

 		d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;

 		if (!dir_emit(ctx, oi->i_name,
 			      strnlen(oi->i_name, OMFS_NAMELEN),
 			      self, d_type)) {
 			brelse(bh);
 			return false;
 		}
 		brelse(bh);
 		ctx->pos++;
 	}
 	return true;
 }

 static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		       struct inode *new_dir, struct dentry *new_dentry,
 		       unsigned int flags)
 {
 	struct inode *new_inode = d_inode(new_dentry);
 	struct inode *old_inode = d_inode(old_dentry);
 	int err;

 	if (flags & ~RENAME_NOREPLACE)
 		return -EINVAL;

 	if (new_inode) {
 		/* overwriting existing file/dir */
 		err = omfs_remove(new_dir, new_dentry);
 		if (err)
 			goto out;
 	}

 	/* since omfs locates files by name, we need to unlink _before_
 	 * adding the new link or we won't find the old one */
 	err = omfs_delete_entry(old_dentry);
 	if (err)
 		goto out;

 	mark_inode_dirty(old_dir);
 	err = omfs_add_link(new_dentry, old_inode);
 	if (err)
 		goto out;

 	old_inode->i_ctime = CURRENT_TIME_SEC;
 	mark_inode_dirty(old_inode);
 out:
 	return err;
 }

 static int omfs_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct inode *dir = file_inode(file);
 	struct buffer_head *bh;
 	__be64 *p;
 	unsigned int hchain, hindex;
 	int nbuckets;

 	if (ctx->pos >> 32)
 		return -EINVAL;

 	if (ctx->pos < 1 << 20) {
 		if (!dir_emit_dots(file, ctx))
 			return 0;
 		ctx->pos = 1 << 20;
 	}

 	nbuckets = (dir->i_size - OMFS_DIR_START) / 8;

 	/* high 12 bits store bucket + 1 and low 20 bits store hash index */
 	hchain = (ctx->pos >> 20) - 1;
 	hindex = ctx->pos & 0xfffff;

 	bh = omfs_bread(dir->i_sb, dir->i_ino);
 	if (!bh)
 		return -EINVAL;

 	p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain;

 	for (; hchain < nbuckets; hchain++) {
 		__u64 fsblock = be64_to_cpu(*p++);
 		if (!omfs_fill_chain(dir, ctx, fsblock, hindex))
 			break;
 		hindex = 0;
 		ctx->pos = (hchain+2) << 20;
 	}
 	brelse(bh);
 	return 0;
 }

 const struct inode_operations omfs_dir_inops = {
 	.lookup = omfs_lookup,
 	.mkdir = omfs_mkdir,
 	.rename = omfs_rename,
 	.create = omfs_create,
 	.unlink = omfs_remove,
 	.rmdir = omfs_remove,
 };

 const struct file_operations omfs_dir_operations = {
 	.read = generic_read_dir,
 	.iterate_shared = omfs_readdir,
 	.llseek = generic_file_llseek,
 };
	/*
	* OMFS (as used by RIO Karma) directory operations.
	* Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
	* Released under GPL v2.
	*/

	#include <linux/fs.h>
	#include <linux/ctype.h>
	#include <linux/buffer_head.h>
	#include "omfs.h"

	static int omfs_hash(const char *name, int namelen, int mod)
	{
	int i, hash = 0;
	for (i = 0; i < namelen; i++)
	hash ^= tolower(name[i]) << (i % 24);
	return hash % mod;
	}

	/*
	* Finds the bucket for a given name and reads the containing block;
	* *ofs is set to the offset of the first list entry.
	*/
	static struct buffer_head omfs_get_bucket(struct inode dir,
	const char name, int namelen, int ofs)
	{
	int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
	int bucket = omfs_hash(name, namelen, nbuckets);

	ofs = OMFS_DIR_START + bucket 8;
	return omfs_bread(dir->i_sb, dir->i_ino);
	}

	static struct buffer_head omfs_scan_list(struct inode dir, u64 block,
	const char *name, int namelen,
	u64 *prev_block)
	{
	struct buffer_head *bh;
	struct omfs_inode *oi;
	int err = -ENOENT;
	*prev_block = ~0;

	while (block != ~0) {
	bh = omfs_bread(dir->i_sb, block);
	if (!bh) {
	err = -EIO;
	goto err;
	}

	oi = (struct omfs_inode *) bh->b_data;
	if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
	brelse(bh);
	goto err;
	}

	if (strncmp(oi->i_name, name, namelen) == 0)
	return bh;

	*prev_block = block;
	block = be64_to_cpu(oi->i_sibling);
	brelse(bh);
	}
	err:
	return ERR_PTR(err);
	}

	static struct buffer_head omfs_find_entry(struct inode dir,
	const char *name, int namelen)
	{
	struct buffer_head *bh;
	int ofs;
	u64 block, dummy;

	bh = omfs_get_bucket(dir, name, namelen, &ofs);
	if (!bh)
	return ERR_PTR(-EIO);

	block = be64_to_cpu(((__be64 ) &bh->b_data[ofs]));
	brelse(bh);

	return omfs_scan_list(dir, block, name, namelen, &dummy);
	}

	int omfs_make_empty(struct inode inode, struct super_block sb)
	{
	struct omfs_sb_info *sbi = OMFS_SB(sb);
	struct buffer_head *bh;
	struct omfs_inode *oi;

	bh = omfs_bread(sb, inode->i_ino);
	if (!bh)
	return -ENOMEM;

	memset(bh->b_data, 0, sizeof(struct omfs_inode));

	if (S_ISDIR(inode->i_mode)) {
	memset(&bh->b_data[OMFS_DIR_START], 0xff,
	sbi->s_sys_blocksize - OMFS_DIR_START);
	} else
	omfs_make_empty_table(bh, OMFS_EXTENT_START);

	oi = (struct omfs_inode *) bh->b_data;
	oi->i_head.h_self = cpu_to_be64(inode->i_ino);
	oi->i_sibling = ~cpu_to_be64(0ULL);

	mark_buffer_dirty(bh);
	brelse(bh);
	return 0;
	}

	static int omfs_add_link(struct dentry dentry, struct inode inode)
	{
	struct inode *dir = d_inode(dentry->d_parent);
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	struct omfs_inode *oi;
	struct buffer_head *bh;
	u64 block;
	__be64 *entry;
	int ofs;

	/* just prepend to head of queue in proper bucket */
	bh = omfs_get_bucket(dir, name, namelen, &ofs);
	if (!bh)
	goto out;

	entry = (__be64 *) &bh->b_data[ofs];
	block = be64_to_cpu(*entry);
	*entry = cpu_to_be64(inode->i_ino);
	mark_buffer_dirty(bh);
	brelse(bh);

	/* now set the sibling and parent pointers on the new inode */
	bh = omfs_bread(dir->i_sb, inode->i_ino);
	if (!bh)
	goto out;

	oi = (struct omfs_inode *) bh->b_data;
	memcpy(oi->i_name, name, namelen);
	memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
	oi->i_sibling = cpu_to_be64(block);
	oi->i_parent = cpu_to_be64(dir->i_ino);
	mark_buffer_dirty(bh);
	brelse(bh);

	dir->i_ctime = CURRENT_TIME_SEC;

	/* mark affected inodes dirty to rebuild checksums */
	mark_inode_dirty(dir);
	mark_inode_dirty(inode);
	return 0;
	out:
	return -ENOMEM;
	}

	static int omfs_delete_entry(struct dentry *dentry)
	{
	struct inode *dir = d_inode(dentry->d_parent);
	struct inode *dirty;
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	struct omfs_inode *oi;
	struct buffer_head bh, bh2;
	__be64 *entry, next;
	u64 block, prev;
	int ofs;
	int err = -ENOMEM;

	/* delete the proper node in the bucket's linked list */
	bh = omfs_get_bucket(dir, name, namelen, &ofs);
	if (!bh)
	goto out;

	entry = (__be64 *) &bh->b_data[ofs];
	block = be64_to_cpu(*entry);

	bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
	if (IS_ERR(bh2)) {
	err = PTR_ERR(bh2);
	goto out_free_bh;
	}

	oi = (struct omfs_inode *) bh2->b_data;
	next = oi->i_sibling;
	brelse(bh2);

	if (prev != ~0) {
	/* found in middle of list, get list ptr */
	brelse(bh);
	bh = omfs_bread(dir->i_sb, prev);
	if (!bh)
	goto out;

	oi = (struct omfs_inode *) bh->b_data;
	entry = &oi->i_sibling;
	}

	*entry = next;
	mark_buffer_dirty(bh);

	if (prev != ~0) {
	dirty = omfs_iget(dir->i_sb, prev);
	if (!IS_ERR(dirty)) {
	mark_inode_dirty(dirty);
	iput(dirty);
	}
	}

	err = 0;
	out_free_bh:
	brelse(bh);
	out:
	return err;
	}

	static int omfs_dir_is_empty(struct inode *inode)
	{
	int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
	struct buffer_head *bh;
	u64 *ptr;
	int i;

	bh = omfs_bread(inode->i_sb, inode->i_ino);

	if (!bh)
	return 0;

	ptr = (u64 *) &bh->b_data[OMFS_DIR_START];

	for (i = 0; i < nbuckets; i++, ptr++)
	if (*ptr != ~0)
	break;

	brelse(bh);
	return *ptr != ~0;
	}

	static int omfs_remove(struct inode dir, struct dentry dentry)
	{
	struct inode *inode = d_inode(dentry);
	int ret;


	if (S_ISDIR(inode->i_mode) &&
	!omfs_dir_is_empty(inode))
	return -ENOTEMPTY;

	ret = omfs_delete_entry(dentry);
	if (ret)
	return ret;

	clear_nlink(inode);
	mark_inode_dirty(inode);
	mark_inode_dirty(dir);
	return 0;
	}

	static int omfs_add_node(struct inode dir, struct dentry dentry, umode_t mode)
	{
	int err;
	struct inode *inode = omfs_new_inode(dir, mode);

	if (IS_ERR(inode))
	return PTR_ERR(inode);

	err = omfs_make_empty(inode, dir->i_sb);
	if (err)
	goto out_free_inode;

	err = omfs_add_link(dentry, inode);
	if (err)
	goto out_free_inode;

	d_instantiate(dentry, inode);
	return 0;

	out_free_inode:
	iput(inode);
	return err;
	}

	static int omfs_mkdir(struct inode dir, struct dentry dentry, umode_t mode)
	{
	return omfs_add_node(dir, dentry, mode \| S_IFDIR);
	}

	static int omfs_create(struct inode dir, struct dentry dentry, umode_t mode,
	bool excl)
	{
	return omfs_add_node(dir, dentry, mode \| S_IFREG);
	}

	static struct dentry omfs_lookup(struct inode dir, struct dentry *dentry,
	unsigned int flags)
	{
	struct buffer_head *bh;
	struct inode *inode = NULL;

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

	bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
	if (!IS_ERR(bh)) {
	struct omfs_inode oi = (struct omfs_inode )bh->b_data;
	ino_t ino = be64_to_cpu(oi->i_head.h_self);
	brelse(bh);
	inode = omfs_iget(dir->i_sb, ino);
	if (IS_ERR(inode))
	return ERR_CAST(inode);
	}
	d_add(dentry, inode);
	return NULL;
	}

	/* sanity check block's self pointer */
	int omfs_is_bad(struct omfs_sb_info sbi, struct omfs_header header,
	u64 fsblock)
	{
	int is_bad;
	u64 ino = be64_to_cpu(header->h_self);
	is_bad = ((ino != fsblock) \|\| (ino < sbi->s_root_ino) \|\|
	(ino > sbi->s_num_blocks));

	if (is_bad)
	printk(KERN_WARNING "omfs: bad hash chain detected\n");

	return is_bad;
	}

	static bool omfs_fill_chain(struct inode dir, struct dir_context ctx,
	u64 fsblock, int hindex)
	{
	/* follow chain in this bucket */
	while (fsblock != ~0) {
	struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock);
	struct omfs_inode *oi;
	u64 self;
	unsigned char d_type;

	if (!bh)
	return true;

	oi = (struct omfs_inode *) bh->b_data;
	if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
	brelse(bh);
	return true;
	}

	self = fsblock;
	fsblock = be64_to_cpu(oi->i_sibling);

	/* skip visited nodes */
	if (hindex) {
	hindex--;
	brelse(bh);
	continue;
	}

	d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;

	if (!dir_emit(ctx, oi->i_name,
	strnlen(oi->i_name, OMFS_NAMELEN),
	self, d_type)) {
	brelse(bh);
	return false;
	}
	brelse(bh);
	ctx->pos++;
	}
	return true;
	}

	static int omfs_rename(struct inode old_dir, struct dentry old_dentry,
	struct inode new_dir, struct dentry new_dentry,
	unsigned int flags)
	{
	struct inode *new_inode = d_inode(new_dentry);
	struct inode *old_inode = d_inode(old_dentry);
	int err;

	if (flags & ~RENAME_NOREPLACE)
	return -EINVAL;

	if (new_inode) {
	/* overwriting existing file/dir */
	err = omfs_remove(new_dir, new_dentry);
	if (err)
	goto out;
	}

	/* since omfs locates files by name, we need to unlink _before_
	* adding the new link or we won't find the old one */
	err = omfs_delete_entry(old_dentry);
	if (err)
	goto out;

	mark_inode_dirty(old_dir);
	err = omfs_add_link(new_dentry, old_inode);
	if (err)
	goto out;

	old_inode->i_ctime = CURRENT_TIME_SEC;
	mark_inode_dirty(old_inode);
	out:
	return err;
	}

	static int omfs_readdir(struct file file, struct dir_context ctx)
	{
	struct inode *dir = file_inode(file);
	struct buffer_head *bh;
	__be64 *p;
	unsigned int hchain, hindex;
	int nbuckets;

	if (ctx->pos >> 32)
	return -EINVAL;

	if (ctx->pos < 1 << 20) {
	if (!dir_emit_dots(file, ctx))
	return 0;
	ctx->pos = 1 << 20;
	}

	nbuckets = (dir->i_size - OMFS_DIR_START) / 8;

	/* high 12 bits store bucket + 1 and low 20 bits store hash index */
	hchain = (ctx->pos >> 20) - 1;
	hindex = ctx->pos & 0xfffff;

	bh = omfs_bread(dir->i_sb, dir->i_ino);
	if (!bh)
	return -EINVAL;

	p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain;

	for (; hchain < nbuckets; hchain++) {
	__u64 fsblock = be64_to_cpu(*p++);
	if (!omfs_fill_chain(dir, ctx, fsblock, hindex))
	break;
	hindex = 0;
	ctx->pos = (hchain+2) << 20;
	}
	brelse(bh);
	return 0;
	}

	const struct inode_operations omfs_dir_inops = {
	.lookup = omfs_lookup,
	.mkdir = omfs_mkdir,
	.rename = omfs_rename,
	.create = omfs_create,
	.unlink = omfs_remove,
	.rmdir = omfs_remove,
	};

	const struct file_operations omfs_dir_operations = {
	.read = generic_read_dir,
	.iterate_shared = omfs_readdir,
	.llseek = generic_file_llseek,
	};