[mirror_ubuntu-zesty-kernel.git] / fs / sysv / dir.c

/*
 *  linux/fs/sysv/dir.c
 *
 *  minix/dir.c
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  coh/dir.c
 *  Copyright (C) 1993  Pascal Haible, Bruno Haible
 *
 *  sysv/dir.c
 *  Copyright (C) 1993  Bruno Haible
 *
 *  SystemV/Coherent directory handling functions
 */

#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/swap.h>
#include "sysv.h"

static int sysv_readdir(struct file *, struct dir_context *);

const struct file_operations sysv_dir_operations = {
	.llseek		= generic_file_llseek,
	.read		= generic_read_dir,
	.iterate_shared	= sysv_readdir,
	.fsync		= generic_file_fsync,
};

static inline void dir_put_page(struct page *page)
{
	kunmap(page);
	put_page(page);
}

static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
{
	struct address_space *mapping = page->mapping;
	struct inode *dir = mapping->host;
	int err = 0;

	block_write_end(NULL, mapping, pos, len, len, page, NULL);
	if (pos+len > dir->i_size) {
		i_size_write(dir, pos+len);
		mark_inode_dirty(dir);
	}
	if (IS_DIRSYNC(dir))
		err = write_one_page(page, 1);
	else
		unlock_page(page);
	return err;
}

static struct page * dir_get_page(struct inode *dir, unsigned long n)
{
	struct address_space *mapping = dir->i_mapping;
	struct page *page = read_mapping_page(mapping, n, NULL);
	if (!IS_ERR(page))
		kmap(page);
	return page;
}

static int sysv_readdir(struct file *file, struct dir_context *ctx)
{
	unsigned long pos = ctx->pos;
	struct inode *inode = file_inode(file);
	struct super_block *sb = inode->i_sb;
	unsigned long npages = dir_pages(inode);
	unsigned offset;
	unsigned long n;

	ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
	if (pos >= inode->i_size)
		return 0;

	offset = pos & ~PAGE_MASK;
	n = pos >> PAGE_SHIFT;

	for ( ; n < npages; n++, offset = 0) {
		char *kaddr, *limit;
		struct sysv_dir_entry *de;
		struct page *page = dir_get_page(inode, n);

		if (IS_ERR(page))
			continue;
		kaddr = (char *)page_address(page);
		de = (struct sysv_dir_entry *)(kaddr+offset);
		limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
		for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
			char *name = de->name;

			if (!de->inode)
				continue;

			if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
					fs16_to_cpu(SYSV_SB(sb), de->inode),
					DT_UNKNOWN)) {
				dir_put_page(page);
				return 0;
			}
		}
		dir_put_page(page);
	}
	return 0;
}

/* compare strings: name[0..len-1] (not zero-terminated) and
 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
 */
static inline int namecompare(int len, int maxlen,
	const char * name, const char * buffer)
{
	if (len < maxlen && buffer[len])
		return 0;
	return !memcmp(name, buffer, len);
}

/*
 *	sysv_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.
 */
struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
{
	const char * name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	struct inode * dir = d_inode(dentry->d_parent);
	unsigned long start, n;
	unsigned long npages = dir_pages(dir);
	struct page *page = NULL;
	struct sysv_dir_entry *de;

	*res_page = NULL;

	start = SYSV_I(dir)->i_dir_start_lookup;
	if (start >= npages)
		start = 0;
	n = start;

	do {
		char *kaddr;
		page = dir_get_page(dir, n);
		if (!IS_ERR(page)) {
			kaddr = (char*)page_address(page);
			de = (struct sysv_dir_entry *) kaddr;
			kaddr += PAGE_SIZE - SYSV_DIRSIZE;
			for ( ; (char *) de <= kaddr ; de++) {
				if (!de->inode)
					continue;
				if (namecompare(namelen, SYSV_NAMELEN,
							name, de->name))
					goto found;
			}
			dir_put_page(page);
		}

		if (++n >= npages)
			n = 0;
	} while (n != start);

	return NULL;

found:
	SYSV_I(dir)->i_dir_start_lookup = n;
	*res_page = page;
	return de;
}

int sysv_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 page *page = NULL;
	struct sysv_dir_entry * de;
	unsigned long npages = dir_pages(dir);
	unsigned long n;
	char *kaddr;
	loff_t pos;
	int err;

	/* We take care of directory expansion in the same loop */
	for (n = 0; n <= npages; n++) {
		page = dir_get_page(dir, n);
		err = PTR_ERR(page);
		if (IS_ERR(page))
			goto out;
		kaddr = (char*)page_address(page);
		de = (struct sysv_dir_entry *)kaddr;
		kaddr += PAGE_SIZE - SYSV_DIRSIZE;
		while ((char *)de <= kaddr) {
			if (!de->inode)
				goto got_it;
			err = -EEXIST;
			if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) 
				goto out_page;
			de++;
		}
		dir_put_page(page);
	}
	BUG();
	return -EINVAL;

got_it:
	pos = page_offset(page) +
			(char*)de - (char*)page_address(page);
	lock_page(page);
	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
	if (err)
		goto out_unlock;
	memcpy (de->name, name, namelen);
	memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
	dir->i_mtime = dir->i_ctime = current_time(dir);
	mark_inode_dirty(dir);
out_page:
	dir_put_page(page);
out:
	return err;
out_unlock:
	unlock_page(page);
	goto out_page;
}

int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
{
	struct inode *inode = page->mapping->host;
	char *kaddr = (char*)page_address(page);
	loff_t pos = page_offset(page) + (char *)de - kaddr;
	int err;

	lock_page(page);
	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
	BUG_ON(err);
	de->inode = 0;
	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
	dir_put_page(page);
	inode->i_ctime = inode->i_mtime = current_time(inode);
	mark_inode_dirty(inode);
	return err;
}

int sysv_make_empty(struct inode *inode, struct inode *dir)
{
	struct page *page = grab_cache_page(inode->i_mapping, 0);
	struct sysv_dir_entry * de;
	char *base;
	int err;

	if (!page)
		return -ENOMEM;
	err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
	if (err) {
		unlock_page(page);
		goto fail;
	}
	kmap(page);

	base = (char*)page_address(page);
	memset(base, 0, PAGE_SIZE);

	de = (struct sysv_dir_entry *) base;
	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
	strcpy(de->name,".");
	de++;
	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
	strcpy(de->name,"..");

	kunmap(page);
	err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
fail:
	put_page(page);
	return err;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
int sysv_empty_dir(struct inode * inode)
{
	struct super_block *sb = inode->i_sb;
	struct page *page = NULL;
	unsigned long i, npages = dir_pages(inode);

	for (i = 0; i < npages; i++) {
		char *kaddr;
		struct sysv_dir_entry * de;
		page = dir_get_page(inode, i);

		if (IS_ERR(page))
			continue;

		kaddr = (char *)page_address(page);
		de = (struct sysv_dir_entry *)kaddr;
		kaddr += PAGE_SIZE-SYSV_DIRSIZE;

		for ( ;(char *)de <= kaddr; de++) {
			if (!de->inode)
				continue;
			/* check for . and .. */
			if (de->name[0] != '.')
				goto not_empty;
			if (!de->name[1]) {
				if (de->inode == cpu_to_fs16(SYSV_SB(sb),
							inode->i_ino))
					continue;
				goto not_empty;
			}
			if (de->name[1] != '.' || de->name[2])
				goto not_empty;
		}
		dir_put_page(page);
	}
	return 1;

not_empty:
	dir_put_page(page);
	return 0;
}

/* Releases the page */
void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
	struct inode *inode)
{
	struct inode *dir = page->mapping->host;
	loff_t pos = page_offset(page) +
			(char *)de-(char*)page_address(page);
	int err;

	lock_page(page);
	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
	BUG_ON(err);
	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
	dir_put_page(page);
	dir->i_mtime = dir->i_ctime = current_time(dir);
	mark_inode_dirty(dir);
}

struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
{
	struct page *page = dir_get_page(dir, 0);
	struct sysv_dir_entry *de = NULL;

	if (!IS_ERR(page)) {
		de = (struct sysv_dir_entry*) page_address(page) + 1;
		*p = page;
	}
	return de;
}

ino_t sysv_inode_by_name(struct dentry *dentry)
{
	struct page *page;
	struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
	ino_t res = 0;
	
	if (de) {
		res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
		dir_put_page(page);
	}
	return res;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/sysv/dir.c
	3	*
	4	* minix/dir.c
	5	* Copyright (C) 1991, 1992 Linus Torvalds
	6	*
	7	* coh/dir.c
	8	* Copyright (C) 1993 Pascal Haible, Bruno Haible
	9	*
	10	* sysv/dir.c
	11	* Copyright (C) 1993 Bruno Haible
	12	*
	13	* SystemV/Coherent directory handling functions
	14	*/
	15
	16	#include <linux/pagemap.h>
	17	#include <linux/highmem.h>
26a6441a	18	#include <linux/swap.h>
1da177e4 LT	19	#include "sysv.h"
1da177e4 LT	20
80886298	21	static int sysv_readdir(struct file , struct dir_context );
1da177e4	22
4b6f5d20	23	const struct file_operations sysv_dir_operations = {
5ac3455a	24	.llseek = generic_file_llseek,
1da177e4	25	.read = generic_read_dir,
3b0a3c1a	26	.iterate_shared = sysv_readdir,
1b061d92	27	.fsync = generic_file_fsync,
1da177e4 LT	28	};
	29
	30	static inline void dir_put_page(struct page *page)
	31	{
	32	kunmap(page);
09cbfeaf	33	put_page(page);
1da177e4 LT	34	}
1da177e4 LT	35
26a6441a	36	static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
1da177e4	37	{
26a6441a NP	38	struct address_space *mapping = page->mapping;
26a6441a NP	39	struct inode *dir = mapping->host;
1da177e4 LT	40	int err = 0;
1da177e4 LT	41
26a6441a NP	42	block_write_end(NULL, mapping, pos, len, len, page, NULL);
	43	if (pos+len > dir->i_size) {
	44	i_size_write(dir, pos+len);
	45	mark_inode_dirty(dir);
	46	}
1da177e4 LT	47	if (IS_DIRSYNC(dir))
	48	err = write_one_page(page, 1);
	49	else
	50	unlock_page(page);
	51	return err;
	52	}
	53
	54	static struct page * dir_get_page(struct inode *dir, unsigned long n)
	55	{
	56	struct address_space *mapping = dir->i_mapping;
090d2b18	57	struct page *page = read_mapping_page(mapping, n, NULL);
6fe6900e	58	if (!IS_ERR(page))
1da177e4	59	kmap(page);
1da177e4	60	return page;
1da177e4 LT	61	}
1da177e4 LT	62
80886298	63	static int sysv_readdir(struct file file, struct dir_context ctx)
1da177e4	64	{
80886298 AV	65	unsigned long pos = ctx->pos;
80886298 AV	66	struct inode *inode = file_inode(file);
1da177e4	67	struct super_block *sb = inode->i_sb;
1da177e4	68	unsigned long npages = dir_pages(inode);
80886298 AV	69	unsigned offset;
80886298 AV	70	unsigned long n;
1da177e4	71
80886298	72	ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
1da177e4	73	if (pos >= inode->i_size)
80886298 AV	74	return 0;
80886298 AV	75
09cbfeaf KS	76	offset = pos & ~PAGE_MASK;
09cbfeaf KS	77	n = pos >> PAGE_SHIFT;
1da177e4 LT	78
	79	for ( ; n < npages; n++, offset = 0) {
	80	char kaddr, limit;
	81	struct sysv_dir_entry *de;
	82	struct page *page = dir_get_page(inode, n);
	83
	84	if (IS_ERR(page))
	85	continue;
	86	kaddr = (char *)page_address(page);
	87	de = (struct sysv_dir_entry *)(kaddr+offset);
09cbfeaf	88	limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
80886298	89	for ( ;(char)de <= limit; de++, ctx->pos += sizeof(de)) {
1da177e4	90	char *name = de->name;
1da177e4 LT	91
	92	if (!de->inode)
	93	continue;
	94
80886298	95	if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
1da177e4	96	fs16_to_cpu(SYSV_SB(sb), de->inode),
80886298	97	DT_UNKNOWN)) {
1da177e4	98	dir_put_page(page);
80886298	99	return 0;
1da177e4 LT	100	}
	101	}
	102	dir_put_page(page);
	103	}
1da177e4 LT	104	return 0;
	105	}
	106
	107	/* compare strings: name[0..len-1] (not zero-terminated) and
	108	* buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
	109	*/
	110	static inline int namecompare(int len, int maxlen,
	111	const char * name, const char * buffer)
	112	{
	113	if (len < maxlen && buffer[len])
	114	return 0;
	115	return !memcmp(name, buffer, len);
	116	}
	117
	118	/*
	119	* sysv_find_entry()
	120	*
	121	* finds an entry in the specified directory with the wanted name. It
	122	* returns the cache buffer in which the entry was found, and the entry
	123	* itself (as a parameter - res_dir). It does NOT read the inode of the
	124	* entry - you'll have to do that yourself if you want to.
	125	*/
	126	struct sysv_dir_entry sysv_find_entry(struct dentry dentry, struct page **res_page)
	127	{
	128	const char * name = dentry->d_name.name;
	129	int namelen = dentry->d_name.len;
2b0143b5	130	struct inode * dir = d_inode(dentry->d_parent);
1da177e4 LT	131	unsigned long start, n;
	132	unsigned long npages = dir_pages(dir);
	133	struct page *page = NULL;
	134	struct sysv_dir_entry *de;
	135
	136	*res_page = NULL;
	137
	138	start = SYSV_I(dir)->i_dir_start_lookup;
	139	if (start >= npages)
	140	start = 0;
	141	n = start;
	142
	143	do {
	144	char *kaddr;
	145	page = dir_get_page(dir, n);
	146	if (!IS_ERR(page)) {
	147	kaddr = (char*)page_address(page);
	148	de = (struct sysv_dir_entry *) kaddr;
09cbfeaf	149	kaddr += PAGE_SIZE - SYSV_DIRSIZE;
1da177e4 LT	150	for ( ; (char *) de <= kaddr ; de++) {
	151	if (!de->inode)
	152	continue;
	153	if (namecompare(namelen, SYSV_NAMELEN,
	154	name, de->name))
	155	goto found;
	156	}
404e7812	157	dir_put_page(page);
1da177e4	158	}
1da177e4 LT	159
	160	if (++n >= npages)
	161	n = 0;
	162	} while (n != start);
	163
	164	return NULL;
	165
	166	found:
	167	SYSV_I(dir)->i_dir_start_lookup = n;
	168	*res_page = page;
	169	return de;
	170	}
	171
	172	int sysv_add_link(struct dentry dentry, struct inode inode)
	173	{
2b0143b5	174	struct inode *dir = d_inode(dentry->d_parent);
1da177e4 LT	175	const char * name = dentry->d_name.name;
	176	int namelen = dentry->d_name.len;
	177	struct page *page = NULL;
	178	struct sysv_dir_entry * de;
	179	unsigned long npages = dir_pages(dir);
	180	unsigned long n;
	181	char *kaddr;
26a6441a	182	loff_t pos;
1da177e4 LT	183	int err;
	184
	185	/* We take care of directory expansion in the same loop */
	186	for (n = 0; n <= npages; n++) {
	187	page = dir_get_page(dir, n);
	188	err = PTR_ERR(page);
	189	if (IS_ERR(page))
	190	goto out;
	191	kaddr = (char*)page_address(page);
	192	de = (struct sysv_dir_entry *)kaddr;
09cbfeaf	193	kaddr += PAGE_SIZE - SYSV_DIRSIZE;
1da177e4 LT	194	while ((char *)de <= kaddr) {
	195	if (!de->inode)
	196	goto got_it;
	197	err = -EEXIST;
	198	if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
	199	goto out_page;
	200	de++;
	201	}
	202	dir_put_page(page);
	203	}
	204	BUG();
	205	return -EINVAL;
	206
	207	got_it:
26a6441a NP	208	pos = page_offset(page) +
26a6441a NP	209	(char)de - (char)page_address(page);
1da177e4	210	lock_page(page);
f4e420dc	211	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
1da177e4 LT	212	if (err)
	213	goto out_unlock;
	214	memcpy (de->name, name, namelen);
	215	memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
	216	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
26a6441a	217	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
02027d42	218	dir->i_mtime = dir->i_ctime = current_time(dir);
1da177e4 LT	219	mark_inode_dirty(dir);
	220	out_page:
	221	dir_put_page(page);
	222	out:
	223	return err;
	224	out_unlock:
	225	unlock_page(page);
	226	goto out_page;
	227	}
	228
	229	int sysv_delete_entry(struct sysv_dir_entry de, struct page page)
	230	{
f4e420dc	231	struct inode *inode = page->mapping->host;
1da177e4	232	char kaddr = (char)page_address(page);
26a6441a	233	loff_t pos = page_offset(page) + (char *)de - kaddr;
1da177e4 LT	234	int err;
	235
	236	lock_page(page);
f4e420dc	237	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
d6735bfc	238	BUG_ON(err);
1da177e4	239	de->inode = 0;
26a6441a	240	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
1da177e4	241	dir_put_page(page);
02027d42	242	inode->i_ctime = inode->i_mtime = current_time(inode);
1da177e4 LT	243	mark_inode_dirty(inode);
	244	return err;
	245	}
	246
	247	int sysv_make_empty(struct inode inode, struct inode dir)
	248	{
f4e420dc	249	struct page *page = grab_cache_page(inode->i_mapping, 0);
1da177e4 LT	250	struct sysv_dir_entry * de;
	251	char *base;
	252	int err;
	253
	254	if (!page)
	255	return -ENOMEM;
f4e420dc	256	err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
1da177e4 LT	257	if (err) {
	258	unlock_page(page);
	259	goto fail;
	260	}
26a6441a	261	kmap(page);
1da177e4 LT	262
1da177e4 LT	263	base = (char*)page_address(page);
09cbfeaf	264	memset(base, 0, PAGE_SIZE);
1da177e4 LT	265
	266	de = (struct sysv_dir_entry *) base;
	267	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
	268	strcpy(de->name,".");
	269	de++;
	270	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
	271	strcpy(de->name,"..");
	272
26a6441a	273	kunmap(page);
1da177e4 LT	274	err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
1da177e4 LT	275	fail:
09cbfeaf	276	put_page(page);
1da177e4 LT	277	return err;
	278	}
	279
	280	/*
	281	* routine to check that the specified directory is empty (for rmdir)
	282	*/
	283	int sysv_empty_dir(struct inode * inode)
	284	{
	285	struct super_block *sb = inode->i_sb;
	286	struct page *page = NULL;
	287	unsigned long i, npages = dir_pages(inode);
	288
	289	for (i = 0; i < npages; i++) {
	290	char *kaddr;
	291	struct sysv_dir_entry * de;
	292	page = dir_get_page(inode, i);
	293
	294	if (IS_ERR(page))
	295	continue;
	296
	297	kaddr = (char *)page_address(page);
	298	de = (struct sysv_dir_entry *)kaddr;
09cbfeaf	299	kaddr += PAGE_SIZE-SYSV_DIRSIZE;
1da177e4 LT	300
	301	for ( ;(char *)de <= kaddr; de++) {
	302	if (!de->inode)
	303	continue;
	304	/* check for . and .. */
	305	if (de->name[0] != '.')
	306	goto not_empty;
	307	if (!de->name[1]) {
	308	if (de->inode == cpu_to_fs16(SYSV_SB(sb),
	309	inode->i_ino))
	310	continue;
	311	goto not_empty;
	312	}
	313	if (de->name[1] != '.' \|\| de->name[2])
	314	goto not_empty;
	315	}
	316	dir_put_page(page);
	317	}
	318	return 1;
	319
	320	not_empty:
	321	dir_put_page(page);
	322	return 0;
	323	}
	324
	325	/* Releases the page */
	326	void sysv_set_link(struct sysv_dir_entry de, struct page page,
	327	struct inode *inode)
	328	{
f4e420dc	329	struct inode *dir = page->mapping->host;
26a6441a NP	330	loff_t pos = page_offset(page) +
26a6441a NP	331	(char )de-(char)page_address(page);
1da177e4 LT	332	int err;
	333
	334	lock_page(page);
f4e420dc	335	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
d6735bfc	336	BUG_ON(err);
1da177e4	337	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
26a6441a	338	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
1da177e4	339	dir_put_page(page);
02027d42	340	dir->i_mtime = dir->i_ctime = current_time(dir);
1da177e4 LT	341	mark_inode_dirty(dir);
	342	}
	343
	344	struct sysv_dir_entry * sysv_dotdot (struct inode dir, struct page *p)
	345	{
	346	struct page *page = dir_get_page(dir, 0);
	347	struct sysv_dir_entry *de = NULL;
	348
	349	if (!IS_ERR(page)) {
	350	de = (struct sysv_dir_entry*) page_address(page) + 1;
	351	*p = page;
	352	}
	353	return de;
	354	}
	355
	356	ino_t sysv_inode_by_name(struct dentry *dentry)
	357	{
	358	struct page *page;
	359	struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
	360	ino_t res = 0;
	361
	362	if (de) {
	363	res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
	364	dir_put_page(page);
	365	}
	366	return res;
	367	}