1 // SPDX-License-Identifier: GPL-2.0
6 * Copyright (C) 1991, 1992 Linus Torvalds
9 * Copyright (C) 1993 Pascal Haible, Bruno Haible
12 * Copyright (C) 1993 Bruno Haible
14 * SystemV/Coherent directory handling functions
17 #include <linux/pagemap.h>
18 #include <linux/highmem.h>
19 #include <linux/swap.h>
22 static int sysv_readdir(struct file *, struct dir_context *);
24 const 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,
31 inline void dir_put_page(struct page *page, void *page_addr)
33 kunmap_local((void *)((unsigned long)page_addr & PAGE_MASK));
37 static void dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
39 struct address_space *mapping = page->mapping;
40 struct inode *dir = mapping->host;
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);
50 static int sysv_handle_dirsync(struct inode *dir)
54 err = filemap_write_and_wait(dir->i_mapping);
56 err = sync_inode_metadata(dir, 1);
61 * Calls to dir_get_page()/dir_put_page() must be nested according to the
62 * rules documented in mm/highmem.rst.
64 * NOTE: sysv_find_entry() and sysv_dotdot() act as calls to dir_get_page()
65 * and must be treated accordingly for nesting purposes.
67 static void *dir_get_page(struct inode *dir, unsigned long n, struct page **p)
69 struct address_space *mapping = dir->i_mapping;
70 struct page *page = read_mapping_page(mapping, n, NULL);
72 return ERR_CAST(page);
74 return kmap_local_page(page);
77 static int sysv_readdir(struct file *file, struct dir_context *ctx)
79 unsigned long pos = ctx->pos;
80 struct inode *inode = file_inode(file);
81 struct super_block *sb = inode->i_sb;
82 unsigned long npages = dir_pages(inode);
86 ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
87 if (pos >= inode->i_size)
90 offset = pos & ~PAGE_MASK;
91 n = pos >> PAGE_SHIFT;
93 for ( ; n < npages; n++, offset = 0) {
95 struct sysv_dir_entry *de;
98 kaddr = dir_get_page(inode, n, &page);
101 de = (struct sysv_dir_entry *)(kaddr+offset);
102 limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
103 for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
104 char *name = de->name;
109 if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
110 fs16_to_cpu(SYSV_SB(sb), de->inode),
112 dir_put_page(page, kaddr);
116 dir_put_page(page, kaddr);
121 /* compare strings: name[0..len-1] (not zero-terminated) and
122 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
124 static inline int namecompare(int len, int maxlen,
125 const char * name, const char * buffer)
127 if (len < maxlen && buffer[len])
129 return !memcmp(name, buffer, len);
135 * finds an entry in the specified directory with the wanted name. It
136 * returns the cache buffer in which the entry was found, and the entry
137 * itself (as a parameter - res_dir). It does NOT read the inode of the
138 * entry - you'll have to do that yourself if you want to.
140 * On Success dir_put_page() should be called on *res_page.
142 * sysv_find_entry() acts as a call to dir_get_page() and must be treated
143 * accordingly for nesting purposes.
145 struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
147 const char * name = dentry->d_name.name;
148 int namelen = dentry->d_name.len;
149 struct inode * dir = d_inode(dentry->d_parent);
150 unsigned long start, n;
151 unsigned long npages = dir_pages(dir);
152 struct page *page = NULL;
153 struct sysv_dir_entry *de;
157 start = SYSV_I(dir)->i_dir_start_lookup;
163 char *kaddr = dir_get_page(dir, n, &page);
165 if (!IS_ERR(kaddr)) {
166 de = (struct sysv_dir_entry *)kaddr;
167 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
168 for ( ; (char *) de <= kaddr ; de++) {
171 if (namecompare(namelen, SYSV_NAMELEN,
175 dir_put_page(page, kaddr);
180 } while (n != start);
185 SYSV_I(dir)->i_dir_start_lookup = n;
190 int sysv_add_link(struct dentry *dentry, struct inode *inode)
192 struct inode *dir = d_inode(dentry->d_parent);
193 const char * name = dentry->d_name.name;
194 int namelen = dentry->d_name.len;
195 struct page *page = NULL;
196 struct sysv_dir_entry * de;
197 unsigned long npages = dir_pages(dir);
203 /* We take care of directory expansion in the same loop */
204 for (n = 0; n <= npages; n++) {
205 kaddr = dir_get_page(dir, n, &page);
207 return PTR_ERR(kaddr);
208 de = (struct sysv_dir_entry *)kaddr;
209 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
210 while ((char *)de <= kaddr) {
214 if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
218 dir_put_page(page, kaddr);
224 pos = page_offset(page) + offset_in_page(de);
226 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
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 dir_commit_chunk(page, pos, SYSV_DIRSIZE);
233 dir->i_mtime = dir->i_ctime = current_time(dir);
234 mark_inode_dirty(dir);
235 err = sysv_handle_dirsync(dir);
237 dir_put_page(page, kaddr);
244 int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
246 struct inode *inode = page->mapping->host;
247 loff_t pos = page_offset(page) + offset_in_page(de);
251 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
257 dir_commit_chunk(page, pos, SYSV_DIRSIZE);
258 inode->i_ctime = inode->i_mtime = current_time(inode);
259 mark_inode_dirty(inode);
260 return sysv_handle_dirsync(inode);
263 int sysv_make_empty(struct inode *inode, struct inode *dir)
265 struct page *page = grab_cache_page(inode->i_mapping, 0);
266 struct sysv_dir_entry * de;
272 err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
277 base = kmap_local_page(page);
278 memset(base, 0, PAGE_SIZE);
280 de = (struct sysv_dir_entry *) base;
281 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
282 strcpy(de->name,".");
284 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
285 strcpy(de->name,"..");
288 dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
289 err = sysv_handle_dirsync(inode);
296 * routine to check that the specified directory is empty (for rmdir)
298 int sysv_empty_dir(struct inode * inode)
300 struct super_block *sb = inode->i_sb;
301 struct page *page = NULL;
302 unsigned long i, npages = dir_pages(inode);
305 for (i = 0; i < npages; i++) {
306 struct sysv_dir_entry *de;
308 kaddr = dir_get_page(inode, i, &page);
312 de = (struct sysv_dir_entry *)kaddr;
313 kaddr += PAGE_SIZE-SYSV_DIRSIZE;
315 for ( ;(char *)de <= kaddr; de++) {
318 /* check for . and .. */
319 if (de->name[0] != '.')
322 if (de->inode == cpu_to_fs16(SYSV_SB(sb),
327 if (de->name[1] != '.' || de->name[2])
330 dir_put_page(page, kaddr);
335 dir_put_page(page, kaddr);
339 /* Releases the page */
340 int sysv_set_link(struct sysv_dir_entry *de, struct page *page,
343 struct inode *dir = page->mapping->host;
344 loff_t pos = page_offset(page) + offset_in_page(de);
348 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
353 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
354 dir_commit_chunk(page, pos, SYSV_DIRSIZE);
355 dir->i_mtime = dir->i_ctime = current_time(dir);
356 mark_inode_dirty(dir);
357 return sysv_handle_dirsync(inode);
361 * Calls to dir_get_page()/dir_put_page() must be nested according to the
362 * rules documented in mm/highmem.rst.
364 * sysv_dotdot() acts as a call to dir_get_page() and must be treated
365 * accordingly for nesting purposes.
367 struct sysv_dir_entry *sysv_dotdot(struct inode *dir, struct page **p)
369 struct sysv_dir_entry *de = dir_get_page(dir, 0, p);
373 /* ".." is the second directory entry */
377 ino_t sysv_inode_by_name(struct dentry *dentry)
380 struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
384 res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
385 dir_put_page(page, de);