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v3.5.6
 
  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/swap.h>
 19#include "sysv.h"
 20
 21static int sysv_readdir(struct file *, void *, filldir_t);
 22
 23const struct file_operations sysv_dir_operations = {
 24	.llseek		= generic_file_llseek,
 25	.read		= generic_read_dir,
 26	.readdir	= sysv_readdir,
 27	.fsync		= generic_file_fsync,
 28};
 29
 30static inline void dir_put_page(struct page *page)
 31{
 32	kunmap(page);
 33	page_cache_release(page);
 34}
 35
 36static inline unsigned long dir_pages(struct inode *inode)
 37{
 38	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
 39}
 40
 41static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
 42{
 43	struct address_space *mapping = page->mapping;
 44	struct inode *dir = mapping->host;
 45	int err = 0;
 46
 47	block_write_end(NULL, mapping, pos, len, len, page, NULL);
 48	if (pos+len > dir->i_size) {
 49		i_size_write(dir, pos+len);
 50		mark_inode_dirty(dir);
 51	}
 52	if (IS_DIRSYNC(dir))
 53		err = write_one_page(page, 1);
 54	else
 55		unlock_page(page);
 
 
 
 
 
 
 56	return err;
 57}
 58
 59static struct page * dir_get_page(struct inode *dir, unsigned long n)
 
 
 
 
 
 
 
 60{
 61	struct address_space *mapping = dir->i_mapping;
 62	struct page *page = read_mapping_page(mapping, n, NULL);
 63	if (!IS_ERR(page))
 64		kmap(page);
 65	return page;
 
 66}
 67
 68static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)
 69{
 70	unsigned long pos = filp->f_pos;
 71	struct inode *inode = filp->f_path.dentry->d_inode;
 72	struct super_block *sb = inode->i_sb;
 73	unsigned offset = pos & ~PAGE_CACHE_MASK;
 74	unsigned long n = pos >> PAGE_CACHE_SHIFT;
 75	unsigned long npages = dir_pages(inode);
 
 
 76
 77	pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
 78	if (pos >= inode->i_size)
 79		goto done;
 
 
 
 80
 81	for ( ; n < npages; n++, offset = 0) {
 82		char *kaddr, *limit;
 83		struct sysv_dir_entry *de;
 84		struct page *page = dir_get_page(inode, n);
 85
 86		if (IS_ERR(page))
 
 87			continue;
 88		kaddr = (char *)page_address(page);
 89		de = (struct sysv_dir_entry *)(kaddr+offset);
 90		limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE;
 91		for ( ;(char*)de <= limit; de++) {
 92			char *name = de->name;
 93			int over;
 94
 95			if (!de->inode)
 96				continue;
 97
 98			offset = (char *)de - kaddr;
 99
100			over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN),
101					((loff_t)n<<PAGE_CACHE_SHIFT) | offset,
102					fs16_to_cpu(SYSV_SB(sb), de->inode),
103					DT_UNKNOWN);
104			if (over) {
105				dir_put_page(page);
106				goto done;
107			}
108		}
109		dir_put_page(page);
110	}
111
112done:
113	filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) | offset;
114	return 0;
115}
116
117/* compare strings: name[0..len-1] (not zero-terminated) and
118 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
119 */
120static inline int namecompare(int len, int maxlen,
121	const char * name, const char * buffer)
122{
123	if (len < maxlen && buffer[len])
124		return 0;
125	return !memcmp(name, buffer, len);
126}
127
128/*
129 *	sysv_find_entry()
130 *
131 * finds an entry in the specified directory with the wanted name. It
132 * returns the cache buffer in which the entry was found, and the entry
133 * itself (as a parameter - res_dir). It does NOT read the inode of the
134 * entry - you'll have to do that yourself if you want to.
 
 
 
 
 
135 */
136struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
137{
138	const char * name = dentry->d_name.name;
139	int namelen = dentry->d_name.len;
140	struct inode * dir = dentry->d_parent->d_inode;
141	unsigned long start, n;
142	unsigned long npages = dir_pages(dir);
143	struct page *page = NULL;
144	struct sysv_dir_entry *de;
145
146	*res_page = NULL;
147
148	start = SYSV_I(dir)->i_dir_start_lookup;
149	if (start >= npages)
150		start = 0;
151	n = start;
152
153	do {
154		char *kaddr;
155		page = dir_get_page(dir, n);
156		if (!IS_ERR(page)) {
157			kaddr = (char*)page_address(page);
158			de = (struct sysv_dir_entry *) kaddr;
159			kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
160			for ( ; (char *) de <= kaddr ; de++) {
161				if (!de->inode)
162					continue;
163				if (namecompare(namelen, SYSV_NAMELEN,
164							name, de->name))
165					goto found;
166			}
167			dir_put_page(page);
168		}
169
170		if (++n >= npages)
171			n = 0;
172	} while (n != start);
173
174	return NULL;
175
176found:
177	SYSV_I(dir)->i_dir_start_lookup = n;
178	*res_page = page;
179	return de;
180}
181
182int sysv_add_link(struct dentry *dentry, struct inode *inode)
183{
184	struct inode *dir = dentry->d_parent->d_inode;
185	const char * name = dentry->d_name.name;
186	int namelen = dentry->d_name.len;
187	struct page *page = NULL;
188	struct sysv_dir_entry * de;
189	unsigned long npages = dir_pages(dir);
190	unsigned long n;
191	char *kaddr;
192	loff_t pos;
193	int err;
194
195	/* We take care of directory expansion in the same loop */
196	for (n = 0; n <= npages; n++) {
197		page = dir_get_page(dir, n);
198		err = PTR_ERR(page);
199		if (IS_ERR(page))
200			goto out;
201		kaddr = (char*)page_address(page);
202		de = (struct sysv_dir_entry *)kaddr;
203		kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
204		while ((char *)de <= kaddr) {
205			if (!de->inode)
206				goto got_it;
207			err = -EEXIST;
208			if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) 
209				goto out_page;
210			de++;
211		}
212		dir_put_page(page);
213	}
214	BUG();
215	return -EINVAL;
216
217got_it:
218	pos = page_offset(page) +
219			(char*)de - (char*)page_address(page);
220	lock_page(page);
221	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
222	if (err)
223		goto out_unlock;
224	memcpy (de->name, name, namelen);
225	memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
226	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
227	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
228	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
229	mark_inode_dirty(dir);
 
230out_page:
231	dir_put_page(page);
232out:
233	return err;
234out_unlock:
235	unlock_page(page);
236	goto out_page;
237}
238
239int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
240{
241	struct inode *inode = page->mapping->host;
242	char *kaddr = (char*)page_address(page);
243	loff_t pos = page_offset(page) + (char *)de - kaddr;
244	int err;
245
246	lock_page(page);
247	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
248	BUG_ON(err);
 
 
 
249	de->inode = 0;
250	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
251	dir_put_page(page);
252	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
253	mark_inode_dirty(inode);
254	return err;
255}
256
257int sysv_make_empty(struct inode *inode, struct inode *dir)
258{
259	struct page *page = grab_cache_page(inode->i_mapping, 0);
260	struct sysv_dir_entry * de;
261	char *base;
262	int err;
263
264	if (!page)
265		return -ENOMEM;
266	err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
267	if (err) {
268		unlock_page(page);
269		goto fail;
270	}
271	kmap(page);
272
273	base = (char*)page_address(page);
274	memset(base, 0, PAGE_CACHE_SIZE);
275
276	de = (struct sysv_dir_entry *) base;
277	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
278	strcpy(de->name,".");
279	de++;
280	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
281	strcpy(de->name,"..");
282
283	kunmap(page);
284	err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
 
285fail:
286	page_cache_release(page);
287	return err;
288}
289
290/*
291 * routine to check that the specified directory is empty (for rmdir)
292 */
293int sysv_empty_dir(struct inode * inode)
294{
295	struct super_block *sb = inode->i_sb;
296	struct page *page = NULL;
297	unsigned long i, npages = dir_pages(inode);
 
298
299	for (i = 0; i < npages; i++) {
300		char *kaddr;
301		struct sysv_dir_entry * de;
302		page = dir_get_page(inode, i);
303
304		if (IS_ERR(page))
 
305			continue;
306
307		kaddr = (char *)page_address(page);
308		de = (struct sysv_dir_entry *)kaddr;
309		kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE;
310
311		for ( ;(char *)de <= kaddr; de++) {
312			if (!de->inode)
313				continue;
314			/* check for . and .. */
315			if (de->name[0] != '.')
316				goto not_empty;
317			if (!de->name[1]) {
318				if (de->inode == cpu_to_fs16(SYSV_SB(sb),
319							inode->i_ino))
320					continue;
321				goto not_empty;
322			}
323			if (de->name[1] != '.' || de->name[2])
324				goto not_empty;
325		}
326		dir_put_page(page);
327	}
328	return 1;
329
330not_empty:
331	dir_put_page(page);
332	return 0;
333}
334
335/* Releases the page */
336void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
337	struct inode *inode)
338{
339	struct inode *dir = page->mapping->host;
340	loff_t pos = page_offset(page) +
341			(char *)de-(char*)page_address(page);
342	int err;
343
344	lock_page(page);
345	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
346	BUG_ON(err);
 
 
 
347	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
348	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
349	dir_put_page(page);
350	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
351	mark_inode_dirty(dir);
 
352}
353
354struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
 
 
 
 
 
 
 
355{
356	struct page *page = dir_get_page(dir, 0);
357	struct sysv_dir_entry *de = NULL;
358
359	if (!IS_ERR(page)) {
360		de = (struct sysv_dir_entry*) page_address(page) + 1;
361		*p = page;
362	}
363	return de;
364}
365
366ino_t sysv_inode_by_name(struct dentry *dentry)
367{
368	struct page *page;
369	struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
370	ino_t res = 0;
371	
372	if (de) {
373		res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
374		dir_put_page(page);
375	}
376	return res;
377}
v6.8
  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *  linux/fs/sysv/dir.c
  4 *
  5 *  minix/dir.c
  6 *  Copyright (C) 1991, 1992  Linus Torvalds
  7 *
  8 *  coh/dir.c
  9 *  Copyright (C) 1993  Pascal Haible, Bruno Haible
 10 *
 11 *  sysv/dir.c
 12 *  Copyright (C) 1993  Bruno Haible
 13 *
 14 *  SystemV/Coherent directory handling functions
 15 */
 16
 17#include <linux/pagemap.h>
 18#include <linux/highmem.h>
 19#include <linux/swap.h>
 20#include "sysv.h"
 21
 22static int sysv_readdir(struct file *, struct dir_context *);
 23
 24const struct file_operations sysv_dir_operations = {
 25	.llseek		= generic_file_llseek,
 26	.read		= generic_read_dir,
 27	.iterate_shared	= sysv_readdir,
 28	.fsync		= generic_file_fsync,
 29};
 30
 31static void dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
 
 
 
 
 
 
 
 
 
 
 
 32{
 33	struct address_space *mapping = page->mapping;
 34	struct inode *dir = mapping->host;
 
 35
 36	block_write_end(NULL, mapping, pos, len, len, page, NULL);
 37	if (pos+len > dir->i_size) {
 38		i_size_write(dir, pos+len);
 39		mark_inode_dirty(dir);
 40	}
 41	unlock_page(page);
 42}
 43
 44static int sysv_handle_dirsync(struct inode *dir)
 45{
 46	int err;
 47
 48	err = filemap_write_and_wait(dir->i_mapping);
 49	if (!err)
 50		err = sync_inode_metadata(dir, 1);
 51	return err;
 52}
 53
 54/*
 55 * Calls to dir_get_page()/unmap_and_put_page() must be nested according to the
 56 * rules documented in mm/highmem.rst.
 57 *
 58 * NOTE: sysv_find_entry() and sysv_dotdot() act as calls to dir_get_page()
 59 * and must be treated accordingly for nesting purposes.
 60 */
 61static void *dir_get_page(struct inode *dir, unsigned long n, struct page **p)
 62{
 63	struct address_space *mapping = dir->i_mapping;
 64	struct page *page = read_mapping_page(mapping, n, NULL);
 65	if (IS_ERR(page))
 66		return ERR_CAST(page);
 67	*p = page;
 68	return kmap_local_page(page);
 69}
 70
 71static int sysv_readdir(struct file *file, struct dir_context *ctx)
 72{
 73	unsigned long pos = ctx->pos;
 74	struct inode *inode = file_inode(file);
 75	struct super_block *sb = inode->i_sb;
 
 
 76	unsigned long npages = dir_pages(inode);
 77	unsigned offset;
 78	unsigned long n;
 79
 80	ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
 81	if (pos >= inode->i_size)
 82		return 0;
 83
 84	offset = pos & ~PAGE_MASK;
 85	n = pos >> PAGE_SHIFT;
 86
 87	for ( ; n < npages; n++, offset = 0) {
 88		char *kaddr, *limit;
 89		struct sysv_dir_entry *de;
 90		struct page *page;
 91
 92		kaddr = dir_get_page(inode, n, &page);
 93		if (IS_ERR(kaddr))
 94			continue;
 
 95		de = (struct sysv_dir_entry *)(kaddr+offset);
 96		limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
 97		for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
 98			char *name = de->name;
 
 99
100			if (!de->inode)
101				continue;
102
103			if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
 
 
 
104					fs16_to_cpu(SYSV_SB(sb), de->inode),
105					DT_UNKNOWN)) {
106				unmap_and_put_page(page, kaddr);
107				return 0;
 
108			}
109		}
110		unmap_and_put_page(page, kaddr);
111	}
 
 
 
112	return 0;
113}
114
115/* compare strings: name[0..len-1] (not zero-terminated) and
116 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
117 */
118static inline int namecompare(int len, int maxlen,
119	const char * name, const char * buffer)
120{
121	if (len < maxlen && buffer[len])
122		return 0;
123	return !memcmp(name, buffer, len);
124}
125
126/*
127 *	sysv_find_entry()
128 *
129 * finds an entry in the specified directory with the wanted name. It
130 * returns the cache buffer in which the entry was found, and the entry
131 * itself (as a parameter - res_dir). It does NOT read the inode of the
132 * entry - you'll have to do that yourself if you want to.
133 *
134 * On Success unmap_and_put_page() should be called on *res_page.
135 *
136 * sysv_find_entry() acts as a call to dir_get_page() and must be treated
137 * accordingly for nesting purposes.
138 */
139struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
140{
141	const char * name = dentry->d_name.name;
142	int namelen = dentry->d_name.len;
143	struct inode * dir = d_inode(dentry->d_parent);
144	unsigned long start, n;
145	unsigned long npages = dir_pages(dir);
146	struct page *page = NULL;
147	struct sysv_dir_entry *de;
148
149	*res_page = NULL;
150
151	start = SYSV_I(dir)->i_dir_start_lookup;
152	if (start >= npages)
153		start = 0;
154	n = start;
155
156	do {
157		char *kaddr = dir_get_page(dir, n, &page);
158
159		if (!IS_ERR(kaddr)) {
160			de = (struct sysv_dir_entry *)kaddr;
161			kaddr += PAGE_SIZE - SYSV_DIRSIZE;
 
162			for ( ; (char *) de <= kaddr ; de++) {
163				if (!de->inode)
164					continue;
165				if (namecompare(namelen, SYSV_NAMELEN,
166							name, de->name))
167					goto found;
168			}
169			unmap_and_put_page(page, kaddr);
170		}
171
172		if (++n >= npages)
173			n = 0;
174	} while (n != start);
175
176	return NULL;
177
178found:
179	SYSV_I(dir)->i_dir_start_lookup = n;
180	*res_page = page;
181	return de;
182}
183
184int sysv_add_link(struct dentry *dentry, struct inode *inode)
185{
186	struct inode *dir = d_inode(dentry->d_parent);
187	const char * name = dentry->d_name.name;
188	int namelen = dentry->d_name.len;
189	struct page *page = NULL;
190	struct sysv_dir_entry * de;
191	unsigned long npages = dir_pages(dir);
192	unsigned long n;
193	char *kaddr;
194	loff_t pos;
195	int err;
196
197	/* We take care of directory expansion in the same loop */
198	for (n = 0; n <= npages; n++) {
199		kaddr = dir_get_page(dir, n, &page);
200		if (IS_ERR(kaddr))
201			return PTR_ERR(kaddr);
 
 
202		de = (struct sysv_dir_entry *)kaddr;
203		kaddr += PAGE_SIZE - SYSV_DIRSIZE;
204		while ((char *)de <= kaddr) {
205			if (!de->inode)
206				goto got_it;
207			err = -EEXIST;
208			if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) 
209				goto out_page;
210			de++;
211		}
212		unmap_and_put_page(page, kaddr);
213	}
214	BUG();
215	return -EINVAL;
216
217got_it:
218	pos = page_offset(page) + offset_in_page(de);
 
219	lock_page(page);
220	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
221	if (err)
222		goto out_unlock;
223	memcpy (de->name, name, namelen);
224	memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
225	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
226	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
227	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
228	mark_inode_dirty(dir);
229	err = sysv_handle_dirsync(dir);
230out_page:
231	unmap_and_put_page(page, kaddr);
 
232	return err;
233out_unlock:
234	unlock_page(page);
235	goto out_page;
236}
237
238int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
239{
240	struct inode *inode = page->mapping->host;
241	loff_t pos = page_offset(page) + offset_in_page(de);
 
242	int err;
243
244	lock_page(page);
245	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
246	if (err) {
247		unlock_page(page);
248		return err;
249	}
250	de->inode = 0;
251	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
252	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
 
253	mark_inode_dirty(inode);
254	return sysv_handle_dirsync(inode);
255}
256
257int sysv_make_empty(struct inode *inode, struct inode *dir)
258{
259	struct page *page = grab_cache_page(inode->i_mapping, 0);
260	struct sysv_dir_entry * de;
261	char *base;
262	int err;
263
264	if (!page)
265		return -ENOMEM;
266	err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
267	if (err) {
268		unlock_page(page);
269		goto fail;
270	}
271	base = kmap_local_page(page);
272	memset(base, 0, PAGE_SIZE);
 
 
273
274	de = (struct sysv_dir_entry *) base;
275	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
276	strcpy(de->name,".");
277	de++;
278	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
279	strcpy(de->name,"..");
280
281	kunmap_local(base);
282	dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
283	err = sysv_handle_dirsync(inode);
284fail:
285	put_page(page);
286	return err;
287}
288
289/*
290 * routine to check that the specified directory is empty (for rmdir)
291 */
292int sysv_empty_dir(struct inode * inode)
293{
294	struct super_block *sb = inode->i_sb;
295	struct page *page = NULL;
296	unsigned long i, npages = dir_pages(inode);
297	char *kaddr;
298
299	for (i = 0; i < npages; i++) {
300		struct sysv_dir_entry *de;
 
 
301
302		kaddr = dir_get_page(inode, i, &page);
303		if (IS_ERR(kaddr))
304			continue;
305
 
306		de = (struct sysv_dir_entry *)kaddr;
307		kaddr += PAGE_SIZE-SYSV_DIRSIZE;
308
309		for ( ;(char *)de <= kaddr; de++) {
310			if (!de->inode)
311				continue;
312			/* check for . and .. */
313			if (de->name[0] != '.')
314				goto not_empty;
315			if (!de->name[1]) {
316				if (de->inode == cpu_to_fs16(SYSV_SB(sb),
317							inode->i_ino))
318					continue;
319				goto not_empty;
320			}
321			if (de->name[1] != '.' || de->name[2])
322				goto not_empty;
323		}
324		unmap_and_put_page(page, kaddr);
325	}
326	return 1;
327
328not_empty:
329	unmap_and_put_page(page, kaddr);
330	return 0;
331}
332
333/* Releases the page */
334int sysv_set_link(struct sysv_dir_entry *de, struct page *page,
335	struct inode *inode)
336{
337	struct inode *dir = page->mapping->host;
338	loff_t pos = page_offset(page) + offset_in_page(de);
 
339	int err;
340
341	lock_page(page);
342	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
343	if (err) {
344		unlock_page(page);
345		return err;
346	}
347	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
348	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
349	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
 
350	mark_inode_dirty(dir);
351	return sysv_handle_dirsync(inode);
352}
353
354/*
355 * Calls to dir_get_page()/unmap_and_put_page() must be nested according to the
356 * rules documented in mm/highmem.rst.
357 *
358 * sysv_dotdot() acts as a call to dir_get_page() and must be treated
359 * accordingly for nesting purposes.
360 */
361struct sysv_dir_entry *sysv_dotdot(struct inode *dir, struct page **p)
362{
363	struct sysv_dir_entry *de = dir_get_page(dir, 0, p);
 
364
365	if (IS_ERR(de))
366		return NULL;
367	/* ".." is the second directory entry */
368	return de + 1;
 
369}
370
371ino_t sysv_inode_by_name(struct dentry *dentry)
372{
373	struct page *page;
374	struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
375	ino_t res = 0;
376	
377	if (de) {
378		res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
379		unmap_and_put_page(page, de);
380	}
381	return res;
382}