xref: /openbmc/linux/fs/sysv/namei.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  *  linux/fs/sysv/namei.c
3  *
4  *  minix/namei.c
5  *  Copyright (C) 1991, 1992  Linus Torvalds
6  *
7  *  coh/namei.c
8  *  Copyright (C) 1993  Pascal Haible, Bruno Haible
9  *
10  *  sysv/namei.c
11  *  Copyright (C) 1993  Bruno Haible
12  *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
13  */
14 
15 #include <linux/pagemap.h>
16 #include <linux/smp_lock.h>
17 #include "sysv.h"
18 
19 static inline void inc_count(struct inode *inode)
20 {
21 	inode->i_nlink++;
22 	mark_inode_dirty(inode);
23 }
24 
25 static inline void dec_count(struct inode *inode)
26 {
27 	inode->i_nlink--;
28 	mark_inode_dirty(inode);
29 }
30 
31 static int add_nondir(struct dentry *dentry, struct inode *inode)
32 {
33 	int err = sysv_add_link(dentry, inode);
34 	if (!err) {
35 		d_instantiate(dentry, inode);
36 		return 0;
37 	}
38 	dec_count(inode);
39 	iput(inode);
40 	return err;
41 }
42 
43 static int sysv_hash(struct dentry *dentry, struct qstr *qstr)
44 {
45 	/* Truncate the name in place, avoids having to define a compare
46 	   function. */
47 	if (qstr->len > SYSV_NAMELEN) {
48 		qstr->len = SYSV_NAMELEN;
49 		qstr->hash = full_name_hash(qstr->name, qstr->len);
50 	}
51 	return 0;
52 }
53 
54 struct dentry_operations sysv_dentry_operations = {
55 	.d_hash		= sysv_hash,
56 };
57 
58 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
59 {
60 	struct inode * inode = NULL;
61 	ino_t ino;
62 
63 	dentry->d_op = dir->i_sb->s_root->d_op;
64 	if (dentry->d_name.len > SYSV_NAMELEN)
65 		return ERR_PTR(-ENAMETOOLONG);
66 	ino = sysv_inode_by_name(dentry);
67 
68 	if (ino) {
69 		inode = iget(dir->i_sb, ino);
70 		if (!inode)
71 			return ERR_PTR(-EACCES);
72 	}
73 	d_add(dentry, inode);
74 	return NULL;
75 }
76 
77 static int sysv_mknod(struct inode * dir, struct dentry * dentry, int mode, dev_t rdev)
78 {
79 	struct inode * inode;
80 	int err;
81 
82 	if (!old_valid_dev(rdev))
83 		return -EINVAL;
84 
85 	inode = sysv_new_inode(dir, mode);
86 	err = PTR_ERR(inode);
87 
88 	if (!IS_ERR(inode)) {
89 		sysv_set_inode(inode, rdev);
90 		mark_inode_dirty(inode);
91 		err = add_nondir(dentry, inode);
92 	}
93 	return err;
94 }
95 
96 static int sysv_create(struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
97 {
98 	return sysv_mknod(dir, dentry, mode, 0);
99 }
100 
101 static int sysv_symlink(struct inode * dir, struct dentry * dentry,
102 	const char * symname)
103 {
104 	int err = -ENAMETOOLONG;
105 	int l = strlen(symname)+1;
106 	struct inode * inode;
107 
108 	if (l > dir->i_sb->s_blocksize)
109 		goto out;
110 
111 	inode = sysv_new_inode(dir, S_IFLNK|0777);
112 	err = PTR_ERR(inode);
113 	if (IS_ERR(inode))
114 		goto out;
115 
116 	sysv_set_inode(inode, 0);
117 	err = page_symlink(inode, symname, l);
118 	if (err)
119 		goto out_fail;
120 
121 	mark_inode_dirty(inode);
122 	err = add_nondir(dentry, inode);
123 out:
124 	return err;
125 
126 out_fail:
127 	dec_count(inode);
128 	iput(inode);
129 	goto out;
130 }
131 
132 static int sysv_link(struct dentry * old_dentry, struct inode * dir,
133 	struct dentry * dentry)
134 {
135 	struct inode *inode = old_dentry->d_inode;
136 
137 	if (inode->i_nlink >= SYSV_SB(inode->i_sb)->s_link_max)
138 		return -EMLINK;
139 
140 	inode->i_ctime = CURRENT_TIME_SEC;
141 	inc_count(inode);
142 	atomic_inc(&inode->i_count);
143 
144 	return add_nondir(dentry, inode);
145 }
146 
147 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, int mode)
148 {
149 	struct inode * inode;
150 	int err = -EMLINK;
151 
152 	if (dir->i_nlink >= SYSV_SB(dir->i_sb)->s_link_max)
153 		goto out;
154 	inc_count(dir);
155 
156 	inode = sysv_new_inode(dir, S_IFDIR|mode);
157 	err = PTR_ERR(inode);
158 	if (IS_ERR(inode))
159 		goto out_dir;
160 
161 	sysv_set_inode(inode, 0);
162 
163 	inc_count(inode);
164 
165 	err = sysv_make_empty(inode, dir);
166 	if (err)
167 		goto out_fail;
168 
169 	err = sysv_add_link(dentry, inode);
170 	if (err)
171 		goto out_fail;
172 
173         d_instantiate(dentry, inode);
174 out:
175 	return err;
176 
177 out_fail:
178 	dec_count(inode);
179 	dec_count(inode);
180 	iput(inode);
181 out_dir:
182 	dec_count(dir);
183 	goto out;
184 }
185 
186 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
187 {
188 	struct inode * inode = dentry->d_inode;
189 	struct page * page;
190 	struct sysv_dir_entry * de;
191 	int err = -ENOENT;
192 
193 	de = sysv_find_entry(dentry, &page);
194 	if (!de)
195 		goto out;
196 
197 	err = sysv_delete_entry (de, page);
198 	if (err)
199 		goto out;
200 
201 	inode->i_ctime = dir->i_ctime;
202 	dec_count(inode);
203 out:
204 	return err;
205 }
206 
207 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
208 {
209 	struct inode *inode = dentry->d_inode;
210 	int err = -ENOTEMPTY;
211 
212 	if (sysv_empty_dir(inode)) {
213 		err = sysv_unlink(dir, dentry);
214 		if (!err) {
215 			inode->i_size = 0;
216 			dec_count(inode);
217 			dec_count(dir);
218 		}
219 	}
220 	return err;
221 }
222 
223 /*
224  * Anybody can rename anything with this: the permission checks are left to the
225  * higher-level routines.
226  */
227 static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
228 		  struct inode * new_dir, struct dentry * new_dentry)
229 {
230 	struct inode * old_inode = old_dentry->d_inode;
231 	struct inode * new_inode = new_dentry->d_inode;
232 	struct page * dir_page = NULL;
233 	struct sysv_dir_entry * dir_de = NULL;
234 	struct page * old_page;
235 	struct sysv_dir_entry * old_de;
236 	int err = -ENOENT;
237 
238 	old_de = sysv_find_entry(old_dentry, &old_page);
239 	if (!old_de)
240 		goto out;
241 
242 	if (S_ISDIR(old_inode->i_mode)) {
243 		err = -EIO;
244 		dir_de = sysv_dotdot(old_inode, &dir_page);
245 		if (!dir_de)
246 			goto out_old;
247 	}
248 
249 	if (new_inode) {
250 		struct page * new_page;
251 		struct sysv_dir_entry * new_de;
252 
253 		err = -ENOTEMPTY;
254 		if (dir_de && !sysv_empty_dir(new_inode))
255 			goto out_dir;
256 
257 		err = -ENOENT;
258 		new_de = sysv_find_entry(new_dentry, &new_page);
259 		if (!new_de)
260 			goto out_dir;
261 		inc_count(old_inode);
262 		sysv_set_link(new_de, new_page, old_inode);
263 		new_inode->i_ctime = CURRENT_TIME_SEC;
264 		if (dir_de)
265 			new_inode->i_nlink--;
266 		dec_count(new_inode);
267 	} else {
268 		if (dir_de) {
269 			err = -EMLINK;
270 			if (new_dir->i_nlink >= SYSV_SB(new_dir->i_sb)->s_link_max)
271 				goto out_dir;
272 		}
273 		inc_count(old_inode);
274 		err = sysv_add_link(new_dentry, old_inode);
275 		if (err) {
276 			dec_count(old_inode);
277 			goto out_dir;
278 		}
279 		if (dir_de)
280 			inc_count(new_dir);
281 	}
282 
283 	sysv_delete_entry(old_de, old_page);
284 	dec_count(old_inode);
285 
286 	if (dir_de) {
287 		sysv_set_link(dir_de, dir_page, new_dir);
288 		dec_count(old_dir);
289 	}
290 	return 0;
291 
292 out_dir:
293 	if (dir_de) {
294 		kunmap(dir_page);
295 		page_cache_release(dir_page);
296 	}
297 out_old:
298 	kunmap(old_page);
299 	page_cache_release(old_page);
300 out:
301 	return err;
302 }
303 
304 /*
305  * directories can handle most operations...
306  */
307 struct inode_operations sysv_dir_inode_operations = {
308 	.create		= sysv_create,
309 	.lookup		= sysv_lookup,
310 	.link		= sysv_link,
311 	.unlink		= sysv_unlink,
312 	.symlink	= sysv_symlink,
313 	.mkdir		= sysv_mkdir,
314 	.rmdir		= sysv_rmdir,
315 	.mknod		= sysv_mknod,
316 	.rename		= sysv_rename,
317 	.getattr	= sysv_getattr,
318 };
319