[linux-block.git] / fs / sysv / dir.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  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 void dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
{
	struct address_space *mapping = page->mapping;
	struct inode *dir = mapping->host;

	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);
	}
	unlock_page(page);
}

static int sysv_handle_dirsync(struct inode *dir)
{
	int err;

	err = filemap_write_and_wait(dir->i_mapping);
	if (!err)
		err = sync_inode_metadata(dir, 1);
	return err;
}

/*
 * Calls to dir_get_page()/unmap_and_put_page() must be nested according to the
 * rules documented in mm/highmem.rst.
 *
 * NOTE: sysv_find_entry() and sysv_dotdot() act as calls to dir_get_page()
 * and must be treated accordingly for nesting purposes.
 */
static void *dir_get_page(struct inode *dir, unsigned long n, struct page **p)
{
	struct address_space *mapping = dir->i_mapping;
	struct page *page = read_mapping_page(mapping, n, NULL);
	if (IS_ERR(page))
		return ERR_CAST(page);
	*p = page;
	return kmap_local_page(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;

		kaddr = dir_get_page(inode, n, &page);
		if (IS_ERR(kaddr))
			continue;
		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)) {
				unmap_and_put_page(page, kaddr);
				return 0;
			}
		}
		unmap_and_put_page(page, kaddr);
	}
	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.
 *
 * On Success unmap_and_put_page() should be called on *res_page.
 *
 * sysv_find_entry() acts as a call to dir_get_page() and must be treated
 * accordingly for nesting purposes.
 */
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 = dir_get_page(dir, n, &page);

		if (!IS_ERR(kaddr)) {
			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;
			}
			unmap_and_put_page(page, kaddr);
		}

		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++) {
		kaddr = dir_get_page(dir, n, &page);
		if (IS_ERR(kaddr))
			return PTR_ERR(kaddr);
		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++;
		}
		unmap_and_put_page(page, kaddr);
	}
	BUG();
	return -EINVAL;

got_it:
	pos = page_offset(page) + offset_in_page(de);
	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);
	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
	mark_inode_dirty(dir);
	err = sysv_handle_dirsync(dir);
out_page:
	unmap_and_put_page(page, kaddr);
	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;
	loff_t pos = page_offset(page) + offset_in_page(de);
	int err;

	lock_page(page);
	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
	if (err) {
		unlock_page(page);
		return err;
	}
	de->inode = 0;
	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
	mark_inode_dirty(inode);
	return sysv_handle_dirsync(inode);
}

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;
	}
	base = kmap_local_page(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_local(base);
	dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
	err = sysv_handle_dirsync(inode);
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);
	char *kaddr;

	for (i = 0; i < npages; i++) {
		struct sysv_dir_entry *de;

		kaddr = dir_get_page(inode, i, &page);
		if (IS_ERR(kaddr))
			continue;

		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;
		}
		unmap_and_put_page(page, kaddr);
	}
	return 1;

not_empty:
	unmap_and_put_page(page, kaddr);
	return 0;
}

/* Releases the page */
int 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) + offset_in_page(de);
	int err;

	lock_page(page);
	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
	if (err) {
		unlock_page(page);
		return err;
	}
	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
	mark_inode_dirty(dir);
	return sysv_handle_dirsync(inode);
}

/*
 * Calls to dir_get_page()/unmap_and_put_page() must be nested according to the
 * rules documented in mm/highmem.rst.
 *
 * sysv_dotdot() acts as a call to dir_get_page() and must be treated
 * accordingly for nesting purposes.
 */
struct sysv_dir_entry *sysv_dotdot(struct inode *dir, struct page **p)
{
	struct sysv_dir_entry *de = dir_get_page(dir, 0, p);

	if (IS_ERR(de))
		return NULL;
	/* ".." is the second directory entry */
	return de + 1;
}

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);
		unmap_and_put_page(page, de);
	}
	return res;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	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>
26a6441a	19	#include <linux/swap.h>
1da177e4 LT	20	#include "sysv.h"
1da177e4 LT	21
80886298	22	static int sysv_readdir(struct file , struct dir_context );
1da177e4	23
4b6f5d20	24	const struct file_operations sysv_dir_operations = {
5ac3455a	25	.llseek = generic_file_llseek,
1da177e4	26	.read = generic_read_dir,
3b0a3c1a	27	.iterate_shared = sysv_readdir,
1b061d92	28	.fsync = generic_file_fsync,
1da177e4 LT	29	};
1da177e4 LT	30
4309093e	31	static void dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
1da177e4	32	{
26a6441a NP	33	struct address_space *mapping = page->mapping;
26a6441a NP	34	struct inode *dir = mapping->host;
1da177e4	35
26a6441a NP	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	}
4309093e CH	41	unlock_page(page);
	42	}
	43
	44	static 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);
1da177e4 LT	51	return err;
	52	}
	53
83005276	54	/*
d0e13540	55	* Calls to dir_get_page()/unmap_and_put_page() must be nested according to the
83005276 FDF	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	*/
8dd6c7b2	61	static void dir_get_page(struct inode dir, unsigned long n, struct page **p)
1da177e4 LT	62	{
1da177e4 LT	63	struct address_space *mapping = dir->i_mapping;
090d2b18	64	struct page *page = read_mapping_page(mapping, n, NULL);
8dd6c7b2 FDF	65	if (IS_ERR(page))
8dd6c7b2 FDF	66	return ERR_CAST(page);
8dd6c7b2	67	*p = page;
83005276	68	return kmap_local_page(page);
1da177e4 LT	69	}
1da177e4 LT	70
80886298	71	static int sysv_readdir(struct file file, struct dir_context ctx)
1da177e4	72	{
80886298 AV	73	unsigned long pos = ctx->pos;
80886298 AV	74	struct inode *inode = file_inode(file);
1da177e4	75	struct super_block *sb = inode->i_sb;
1da177e4	76	unsigned long npages = dir_pages(inode);
80886298 AV	77	unsigned offset;
80886298 AV	78	unsigned long n;
1da177e4	79
80886298	80	ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
1da177e4	81	if (pos >= inode->i_size)
80886298 AV	82	return 0;
80886298 AV	83
09cbfeaf KS	84	offset = pos & ~PAGE_MASK;
09cbfeaf KS	85	n = pos >> PAGE_SHIFT;
1da177e4 LT	86
	87	for ( ; n < npages; n++, offset = 0) {
	88	char kaddr, limit;
	89	struct sysv_dir_entry *de;
8dd6c7b2	90	struct page *page;
1da177e4	91
8dd6c7b2 FDF	92	kaddr = dir_get_page(inode, n, &page);
8dd6c7b2 FDF	93	if (IS_ERR(kaddr))
1da177e4	94	continue;
1da177e4	95	de = (struct sysv_dir_entry *)(kaddr+offset);
09cbfeaf	96	limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
80886298	97	for ( ;(char)de <= limit; de++, ctx->pos += sizeof(de)) {
1da177e4	98	char *name = de->name;
1da177e4 LT	99
	100	if (!de->inode)
	101	continue;
	102
80886298	103	if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
1da177e4	104	fs16_to_cpu(SYSV_SB(sb), de->inode),
80886298	105	DT_UNKNOWN)) {
d0e13540	106	unmap_and_put_page(page, kaddr);
80886298	107	return 0;
1da177e4 LT	108	}
1da177e4 LT	109	}
d0e13540	110	unmap_and_put_page(page, kaddr);
1da177e4	111	}
1da177e4 LT	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	*/
	118	static 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.
83005276	133	*
d0e13540	134	* On Success unmap_and_put_page() should be called on *res_page.
83005276 FDF	135	*
	136	* sysv_find_entry() acts as a call to dir_get_page() and must be treated
	137	* accordingly for nesting purposes.
1da177e4 LT	138	*/
	139	struct 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;
2b0143b5	143	struct inode * dir = d_inode(dentry->d_parent);
1da177e4 LT	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 {
8dd6c7b2 FDF	157	char *kaddr = dir_get_page(dir, n, &page);
	158
	159	if (!IS_ERR(kaddr)) {
	160	de = (struct sysv_dir_entry *)kaddr;
09cbfeaf	161	kaddr += PAGE_SIZE - SYSV_DIRSIZE;
1da177e4 LT	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	}
d0e13540	169	unmap_and_put_page(page, kaddr);
1da177e4	170	}
1da177e4 LT	171
	172	if (++n >= npages)
	173	n = 0;
	174	} while (n != start);
	175
	176	return NULL;
	177
	178	found:
	179	SYSV_I(dir)->i_dir_start_lookup = n;
	180	*res_page = page;
	181	return de;
	182	}
	183
	184	int sysv_add_link(struct dentry dentry, struct inode inode)
	185	{
2b0143b5	186	struct inode *dir = d_inode(dentry->d_parent);
1da177e4 LT	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;
26a6441a	194	loff_t pos;
1da177e4 LT	195	int err;
	196
	197	/* We take care of directory expansion in the same loop */
	198	for (n = 0; n <= npages; n++) {
8dd6c7b2 FDF	199	kaddr = dir_get_page(dir, n, &page);
	200	if (IS_ERR(kaddr))
	201	return PTR_ERR(kaddr);
1da177e4	202	de = (struct sysv_dir_entry *)kaddr;
09cbfeaf	203	kaddr += PAGE_SIZE - SYSV_DIRSIZE;
1da177e4 LT	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	}
d0e13540	212	unmap_and_put_page(page, kaddr);
1da177e4 LT	213	}
	214	BUG();
	215	return -EINVAL;
	216
	217	got_it:
4bb1a137	218	pos = page_offset(page) + offset_in_page(de);
1da177e4	219	lock_page(page);
f4e420dc	220	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
1da177e4 LT	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);
4309093e	226	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
ae3d362a	227	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
1da177e4	228	mark_inode_dirty(dir);
4309093e	229	err = sysv_handle_dirsync(dir);
1da177e4	230	out_page:
d0e13540	231	unmap_and_put_page(page, kaddr);
1da177e4 LT	232	return err;
	233	out_unlock:
	234	unlock_page(page);
	235	goto out_page;
	236	}
	237
	238	int sysv_delete_entry(struct sysv_dir_entry de, struct page page)
	239	{
f4e420dc	240	struct inode *inode = page->mapping->host;
4bb1a137	241	loff_t pos = page_offset(page) + offset_in_page(de);
1da177e4 LT	242	int err;
	243
	244	lock_page(page);
f4e420dc	245	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
abb7c742 AV	246	if (err) {
	247	unlock_page(page);
	248	return err;
	249	}
1da177e4	250	de->inode = 0;
4309093e	251	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
ae3d362a	252	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
1da177e4	253	mark_inode_dirty(inode);
4309093e	254	return sysv_handle_dirsync(inode);
1da177e4 LT	255	}
	256
	257	int sysv_make_empty(struct inode inode, struct inode dir)
	258	{
f4e420dc	259	struct page *page = grab_cache_page(inode->i_mapping, 0);
1da177e4 LT	260	struct sysv_dir_entry * de;
	261	char *base;
	262	int err;
	263
	264	if (!page)
	265	return -ENOMEM;
f4e420dc	266	err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
1da177e4 LT	267	if (err) {
	268	unlock_page(page);
	269	goto fail;
	270	}
83005276	271	base = kmap_local_page(page);
09cbfeaf	272	memset(base, 0, PAGE_SIZE);
1da177e4 LT	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
83005276	281	kunmap_local(base);
4309093e CH	282	dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
4309093e CH	283	err = sysv_handle_dirsync(inode);
1da177e4	284	fail:
09cbfeaf	285	put_page(page);
1da177e4 LT	286	return err;
	287	}
	288
	289	/*
	290	* routine to check that the specified directory is empty (for rmdir)
	291	*/
	292	int 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);
83005276	297	char *kaddr;
1da177e4 LT	298
1da177e4 LT	299	for (i = 0; i < npages; i++) {
83005276	300	struct sysv_dir_entry *de;
1da177e4	301
8dd6c7b2 FDF	302	kaddr = dir_get_page(inode, i, &page);
8dd6c7b2 FDF	303	if (IS_ERR(kaddr))
1da177e4 LT	304	continue;
1da177e4 LT	305
1da177e4	306	de = (struct sysv_dir_entry *)kaddr;
09cbfeaf	307	kaddr += PAGE_SIZE-SYSV_DIRSIZE;
1da177e4 LT	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	}
d0e13540	324	unmap_and_put_page(page, kaddr);
1da177e4 LT	325	}
	326	return 1;
	327
	328	not_empty:
d0e13540	329	unmap_and_put_page(page, kaddr);
1da177e4 LT	330	return 0;
	331	}
	332
	333	/* Releases the page */
abb7c742	334	int sysv_set_link(struct sysv_dir_entry de, struct page page,
1da177e4 LT	335	struct inode *inode)
1da177e4 LT	336	{
f4e420dc	337	struct inode *dir = page->mapping->host;
4bb1a137	338	loff_t pos = page_offset(page) + offset_in_page(de);
1da177e4 LT	339	int err;
	340
	341	lock_page(page);
f4e420dc	342	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
abb7c742 AV	343	if (err) {
	344	unlock_page(page);
	345	return err;
	346	}
1da177e4	347	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
4309093e	348	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
ae3d362a	349	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
1da177e4	350	mark_inode_dirty(dir);
abb7c742	351	return sysv_handle_dirsync(inode);
1da177e4 LT	352	}
1da177e4 LT	353
83005276	354	/*
d0e13540	355	* Calls to dir_get_page()/unmap_and_put_page() must be nested according to the
83005276 FDF	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	*/
8dd6c7b2	361	struct sysv_dir_entry sysv_dotdot(struct inode dir, struct page **p)
1da177e4	362	{
8dd6c7b2	363	struct sysv_dir_entry *de = dir_get_page(dir, 0, p);
1da177e4	364
8dd6c7b2 FDF	365	if (IS_ERR(de))
	366	return NULL;
	367	/* ".." is the second directory entry */
	368	return de + 1;
1da177e4 LT	369	}
	370
	371	ino_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);
d0e13540	379	unmap_and_put_page(page, de);
1da177e4 LT	380	}
	381	return res;
	382	}