[net-next-2.6.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/smp_lock.h>
#include "sysv.h"

static int sysv_readdir(struct file *, void *, filldir_t);

const struct file_operations sysv_dir_operations = {
	.read		= generic_read_dir,
	.readdir	= sysv_readdir,
	.fsync		= sysv_sync_file,
};

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

static inline unsigned long dir_pages(struct inode *inode)
{
	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
}

static int dir_commit_chunk(struct page *page, unsigned from, unsigned to)
{
	struct inode *dir = (struct inode *)page->mapping->host;
	int err = 0;

	page->mapping->a_ops->commit_write(NULL, page, from, to);
	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)) {
		wait_on_page_locked(page);
		kmap(page);
		if (!PageUptodate(page))
			goto fail;
	}
	return page;

fail:
	dir_put_page(page);
	return ERR_PTR(-EIO);
}

static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
	unsigned long pos = filp->f_pos;
	struct inode *inode = filp->f_dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	unsigned offset = pos & ~PAGE_CACHE_MASK;
	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	unsigned long npages = dir_pages(inode);

	lock_kernel();

	pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
	if (pos >= inode->i_size)
		goto done;

	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_CACHE_SIZE - SYSV_DIRSIZE;
		for ( ;(char*)de <= limit; de++) {
			char *name = de->name;
			int over;

			if (!de->inode)
				continue;

			offset = (char *)de - kaddr;

			over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN),
					((loff_t)n<<PAGE_CACHE_SHIFT) | offset,
					fs16_to_cpu(SYSV_SB(sb), de->inode),
					DT_UNKNOWN);
			if (over) {
				dir_put_page(page);
				goto done;
			}
		}
		dir_put_page(page);
	}

done:
	filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) | offset;
	unlock_kernel();
	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 = dentry->d_parent->d_inode;
	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_CACHE_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 = dentry->d_parent->d_inode;
	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;
	unsigned from, to;
	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_CACHE_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:
	from = (char*)de - (char*)page_address(page);
	to = from + SYSV_DIRSIZE;
	lock_page(page);
	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
	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, from, to);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	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 address_space *mapping = page->mapping;
	struct inode *inode = (struct inode*)mapping->host;
	char *kaddr = (char*)page_address(page);
	unsigned from = (char*)de - kaddr;
	unsigned to = from + SYSV_DIRSIZE;
	int err;

	lock_page(page);
	err = mapping->a_ops->prepare_write(NULL, page, from, to);
	BUG_ON(err);
	de->inode = 0;
	err = dir_commit_chunk(page, from, to);
	dir_put_page(page);
	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
	mark_inode_dirty(inode);
	return err;
}

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

	if (!page)
		return -ENOMEM;
	kmap(page);
	err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * SYSV_DIRSIZE);
	if (err) {
		unlock_page(page);
		goto fail;
	}

	base = (char*)page_address(page);
	memset(base, 0, PAGE_CACHE_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,"..");

	err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
fail:
	kunmap(page);
	page_cache_release(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_CACHE_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 = (struct inode*)page->mapping->host;
	unsigned from = (char *)de-(char*)page_address(page);
	unsigned to = from + SYSV_DIRSIZE;
	int err;

	lock_page(page);
	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
	BUG_ON(err);
	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
	err = dir_commit_chunk(page, from, to);
	dir_put_page(page);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	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>
	18	#include <linux/smp_lock.h>
	19	#include "sysv.h"
	20
	21	static int sysv_readdir(struct file , void , filldir_t);
	22
4b6f5d20	23	const struct file_operations sysv_dir_operations = {
1da177e4 LT	24	.read = generic_read_dir,
	25	.readdir = sysv_readdir,
	26	.fsync = sysv_sync_file,
	27	};
	28
	29	static inline void dir_put_page(struct page *page)
	30	{
	31	kunmap(page);
	32	page_cache_release(page);
	33	}
	34
	35	static inline unsigned long dir_pages(struct inode *inode)
	36	{
	37	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
	38	}
	39
	40	static int dir_commit_chunk(struct page *page, unsigned from, unsigned to)
	41	{
	42	struct inode dir = (struct inode )page->mapping->host;
	43	int err = 0;
	44
	45	page->mapping->a_ops->commit_write(NULL, page, from, to);
	46	if (IS_DIRSYNC(dir))
	47	err = write_one_page(page, 1);
	48	else
	49	unlock_page(page);
	50	return err;
	51	}
	52
	53	static struct page * dir_get_page(struct inode *dir, unsigned long n)
	54	{
	55	struct address_space *mapping = dir->i_mapping;
090d2b18	56	struct page *page = read_mapping_page(mapping, n, NULL);
1da177e4 LT	57	if (!IS_ERR(page)) {
	58	wait_on_page_locked(page);
	59	kmap(page);
	60	if (!PageUptodate(page))
	61	goto fail;
	62	}
	63	return page;
	64
	65	fail:
	66	dir_put_page(page);
	67	return ERR_PTR(-EIO);
	68	}
	69
	70	static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)
	71	{
	72	unsigned long pos = filp->f_pos;
	73	struct inode *inode = filp->f_dentry->d_inode;
	74	struct super_block *sb = inode->i_sb;
	75	unsigned offset = pos & ~PAGE_CACHE_MASK;
	76	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	77	unsigned long npages = dir_pages(inode);
	78
	79	lock_kernel();
	80
	81	pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
	82	if (pos >= inode->i_size)
	83	goto done;
	84
	85	for ( ; n < npages; n++, offset = 0) {
	86	char kaddr, limit;
	87	struct sysv_dir_entry *de;
	88	struct page *page = dir_get_page(inode, n);
	89
	90	if (IS_ERR(page))
	91	continue;
	92	kaddr = (char *)page_address(page);
	93	de = (struct sysv_dir_entry *)(kaddr+offset);
	94	limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE;
	95	for ( ;(char*)de <= limit; de++) {
	96	char *name = de->name;
	97	int over;
	98
	99	if (!de->inode)
	100	continue;
	101
	102	offset = (char *)de - kaddr;
	103
	104	over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN),
54b21a79	105	((loff_t)n<<PAGE_CACHE_SHIFT) \| offset,
1da177e4 LT	106	fs16_to_cpu(SYSV_SB(sb), de->inode),
	107	DT_UNKNOWN);
	108	if (over) {
	109	dir_put_page(page);
	110	goto done;
	111	}
	112	}
	113	dir_put_page(page);
	114	}
	115
	116	done:
54b21a79	117	filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) \| offset;
1da177e4 LT	118	unlock_kernel();
	119	return 0;
	120	}
	121
	122	/* compare strings: name[0..len-1] (not zero-terminated) and
	123	* buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
	124	*/
	125	static inline int namecompare(int len, int maxlen,
	126	const char * name, const char * buffer)
	127	{
	128	if (len < maxlen && buffer[len])
	129	return 0;
	130	return !memcmp(name, buffer, len);
	131	}
	132
	133	/*
	134	* sysv_find_entry()
	135	*
	136	* finds an entry in the specified directory with the wanted name. It
	137	* returns the cache buffer in which the entry was found, and the entry
	138	* itself (as a parameter - res_dir). It does NOT read the inode of the
	139	* entry - you'll have to do that yourself if you want to.
	140	*/
	141	struct sysv_dir_entry sysv_find_entry(struct dentry dentry, struct page **res_page)
	142	{
	143	const char * name = dentry->d_name.name;
	144	int namelen = dentry->d_name.len;
	145	struct inode * dir = dentry->d_parent->d_inode;
	146	unsigned long start, n;
	147	unsigned long npages = dir_pages(dir);
	148	struct page *page = NULL;
	149	struct sysv_dir_entry *de;
	150
	151	*res_page = NULL;
	152
	153	start = SYSV_I(dir)->i_dir_start_lookup;
	154	if (start >= npages)
	155	start = 0;
	156	n = start;
	157
	158	do {
	159	char *kaddr;
	160	page = dir_get_page(dir, n);
	161	if (!IS_ERR(page)) {
	162	kaddr = (char*)page_address(page);
	163	de = (struct sysv_dir_entry *) kaddr;
	164	kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
	165	for ( ; (char *) de <= kaddr ; de++) {
	166	if (!de->inode)
	167	continue;
	168	if (namecompare(namelen, SYSV_NAMELEN,
	169	name, de->name))
	170	goto found;
	171	}
	172	}
	173	dir_put_page(page);
	174
	175	if (++n >= npages)
	176	n = 0;
	177	} while (n != start);
	178
	179	return NULL;
	180
	181	found:
182	SYSV_I(dir)->i_dir_start_lookup = n;
183	*res_page = page;
184	return de;
185	}
186
187	int sysv_add_link(struct dentry dentry, struct inode inode)
188	{
189	struct inode *dir = dentry->d_parent->d_inode;
190	const char * name = dentry->d_name.name;
191	int namelen = dentry->d_name.len;
192	struct page *page = NULL;
193	struct sysv_dir_entry * de;
194	unsigned long npages = dir_pages(dir);
195	unsigned long n;
196	char *kaddr;
197	unsigned from, to;
198	int err;
199
200	/* We take care of directory expansion in the same loop */
201	for (n = 0; n <= npages; n++) {
202	page = dir_get_page(dir, n);
203	err = PTR_ERR(page);
204	if (IS_ERR(page))
205	goto out;
206	kaddr = (char*)page_address(page);
207	de = (struct sysv_dir_entry *)kaddr;
208	kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
209	while ((char *)de <= kaddr) {
210	if (!de->inode)
211	goto got_it;
212	err = -EEXIST;
213	if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
214	goto out_page;
215	de++;
216	}
217	dir_put_page(page);
218	}
219	BUG();
220	return -EINVAL;
221
222	got_it:
223	from = (char)de - (char)page_address(page);
224	to = from + SYSV_DIRSIZE;
225	lock_page(page);
226	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
227	if (err)
228	goto out_unlock;
229	memcpy (de->name, name, namelen);
230	memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
231	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
232	err = dir_commit_chunk(page, from, to);
233	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
234	mark_inode_dirty(dir);
235	out_page:
236	dir_put_page(page);
237	out:
238	return err;
239	out_unlock:
240	unlock_page(page);
241	goto out_page;
242	}
243
244	int sysv_delete_entry(struct sysv_dir_entry de, struct page page)
245	{
246	struct address_space *mapping = page->mapping;
247	struct inode inode = (struct inode)mapping->host;
248	char kaddr = (char)page_address(page);
249	unsigned from = (char*)de - kaddr;
250	unsigned to = from + SYSV_DIRSIZE;
251	int err;
252
253	lock_page(page);
254	err = mapping->a_ops->prepare_write(NULL, page, from, to);
d6735bfc	255	BUG_ON(err);
1da177e4 LT	256	de->inode = 0;
	257	err = dir_commit_chunk(page, from, to);
	258	dir_put_page(page);
	259	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
	260	mark_inode_dirty(inode);
	261	return err;
	262	}
	263
	264	int sysv_make_empty(struct inode inode, struct inode dir)
	265	{
	266	struct address_space *mapping = inode->i_mapping;
	267	struct page *page = grab_cache_page(mapping, 0);
	268	struct sysv_dir_entry * de;
	269	char *base;
	270	int err;
	271
	272	if (!page)
	273	return -ENOMEM;
	274	kmap(page);
	275	err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * SYSV_DIRSIZE);
	276	if (err) {
	277	unlock_page(page);
	278	goto fail;
	279	}
	280
	281	base = (char*)page_address(page);
	282	memset(base, 0, PAGE_CACHE_SIZE);
	283
	284	de = (struct sysv_dir_entry *) base;
	285	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
	286	strcpy(de->name,".");
	287	de++;
	288	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
	289	strcpy(de->name,"..");
	290
	291	err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
	292	fail:
	293	kunmap(page);
	294	page_cache_release(page);
	295	return err;
	296	}
	297
	298	/*
	299	* routine to check that the specified directory is empty (for rmdir)
	300	*/
	301	int sysv_empty_dir(struct inode * inode)
	302	{
	303	struct super_block *sb = inode->i_sb;
	304	struct page *page = NULL;
	305	unsigned long i, npages = dir_pages(inode);
	306
	307	for (i = 0; i < npages; i++) {
	308	char *kaddr;
	309	struct sysv_dir_entry * de;
	310	page = dir_get_page(inode, i);
	311
	312	if (IS_ERR(page))
	313	continue;
	314
	315	kaddr = (char *)page_address(page);
	316	de = (struct sysv_dir_entry *)kaddr;
	317	kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE;
	318
	319	for ( ;(char *)de <= kaddr; de++) {
320	if (!de->inode)
321	continue;
322	/* check for . and .. */
323	if (de->name[0] != '.')
324	goto not_empty;
325	if (!de->name[1]) {
326	if (de->inode == cpu_to_fs16(SYSV_SB(sb),
327	inode->i_ino))
328	continue;
329	goto not_empty;
330	}
331	if (de->name[1] != '.' \|\| de->name[2])
332	goto not_empty;
333	}
334	dir_put_page(page);
335	}
336	return 1;
337
338	not_empty:
339	dir_put_page(page);
340	return 0;
341	}
342
343	/* Releases the page */
344	void sysv_set_link(struct sysv_dir_entry de, struct page page,
345	struct inode *inode)
346	{
347	struct inode dir = (struct inode)page->mapping->host;
348	unsigned from = (char )de-(char)page_address(page);
349	unsigned to = from + SYSV_DIRSIZE;
350	int err;
351
352	lock_page(page);
353	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
d6735bfc	354	BUG_ON(err);
1da177e4 LT	355	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
	356	err = dir_commit_chunk(page, from, to);
	357	dir_put_page(page);
	358	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	359	mark_inode_dirty(dir);
	360	}
	361
	362	struct sysv_dir_entry * sysv_dotdot (struct inode dir, struct page *p)
	363	{
	364	struct page *page = dir_get_page(dir, 0);
	365	struct sysv_dir_entry *de = NULL;
	366
	367	if (!IS_ERR(page)) {
	368	de = (struct sysv_dir_entry*) page_address(page) + 1;
	369	*p = page;
	370	}
	371	return de;
	372	}
	373
	374	ino_t sysv_inode_by_name(struct dentry *dentry)
	375	{
	376	struct page *page;
	377	struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
	378	ino_t res = 0;
	379
	380	if (de) {
	381	res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
	382	dir_put_page(page);
	383	}
	384	return res;
	385	}