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Linux/fs/sysv/namei.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  linux/fs/sysv/namei.c
  4  *
  5  *  minix/namei.c
  6  *  Copyright (C) 1991, 1992  Linus Torvalds
  7  *
  8  *  coh/namei.c
  9  *  Copyright (C) 1993  Pascal Haible, Bruno Haible
 10  *
 11  *  sysv/namei.c
 12  *  Copyright (C) 1993  Bruno Haible
 13  *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
 14  */
 15 
 16 #include <linux/pagemap.h>
 17 #include "sysv.h"
 18 
 19 static int add_nondir(struct dentry *dentry, struct inode *inode)
 20 {
 21         int err = sysv_add_link(dentry, inode);
 22         if (!err) {
 23                 d_instantiate(dentry, inode);
 24                 return 0;
 25         }
 26         inode_dec_link_count(inode);
 27         iput(inode);
 28         return err;
 29 }
 30 
 31 static int sysv_hash(const struct dentry *dentry, struct qstr *qstr)
 32 {
 33         /* Truncate the name in place, avoids having to define a compare
 34            function. */
 35         if (qstr->len > SYSV_NAMELEN) {
 36                 qstr->len = SYSV_NAMELEN;
 37                 qstr->hash = full_name_hash(dentry, qstr->name, qstr->len);
 38         }
 39         return 0;
 40 }
 41 
 42 const struct dentry_operations sysv_dentry_operations = {
 43         .d_hash         = sysv_hash,
 44 };
 45 
 46 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
 47 {
 48         struct inode * inode = NULL;
 49         ino_t ino;
 50 
 51         if (dentry->d_name.len > SYSV_NAMELEN)
 52                 return ERR_PTR(-ENAMETOOLONG);
 53         ino = sysv_inode_by_name(dentry);
 54         if (ino)
 55                 inode = sysv_iget(dir->i_sb, ino);
 56         return d_splice_alias(inode, dentry);
 57 }
 58 
 59 static int sysv_mknod(struct inode * dir, struct dentry * dentry, umode_t mode, dev_t rdev)
 60 {
 61         struct inode * inode;
 62         int err;
 63 
 64         if (!old_valid_dev(rdev))
 65                 return -EINVAL;
 66 
 67         inode = sysv_new_inode(dir, mode);
 68         err = PTR_ERR(inode);
 69 
 70         if (!IS_ERR(inode)) {
 71                 sysv_set_inode(inode, rdev);
 72                 mark_inode_dirty(inode);
 73                 err = add_nondir(dentry, inode);
 74         }
 75         return err;
 76 }
 77 
 78 static int sysv_create(struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
 79 {
 80         return sysv_mknod(dir, dentry, mode, 0);
 81 }
 82 
 83 static int sysv_symlink(struct inode * dir, struct dentry * dentry, 
 84         const char * symname)
 85 {
 86         int err = -ENAMETOOLONG;
 87         int l = strlen(symname)+1;
 88         struct inode * inode;
 89 
 90         if (l > dir->i_sb->s_blocksize)
 91                 goto out;
 92 
 93         inode = sysv_new_inode(dir, S_IFLNK|0777);
 94         err = PTR_ERR(inode);
 95         if (IS_ERR(inode))
 96                 goto out;
 97         
 98         sysv_set_inode(inode, 0);
 99         err = page_symlink(inode, symname, l);
100         if (err)
101                 goto out_fail;
102 
103         mark_inode_dirty(inode);
104         err = add_nondir(dentry, inode);
105 out:
106         return err;
107 
108 out_fail:
109         inode_dec_link_count(inode);
110         iput(inode);
111         goto out;
112 }
113 
114 static int sysv_link(struct dentry * old_dentry, struct inode * dir, 
115         struct dentry * dentry)
116 {
117         struct inode *inode = d_inode(old_dentry);
118 
119         inode->i_ctime = current_time(inode);
120         inode_inc_link_count(inode);
121         ihold(inode);
122 
123         return add_nondir(dentry, inode);
124 }
125 
126 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
127 {
128         struct inode * inode;
129         int err;
130 
131         inode_inc_link_count(dir);
132 
133         inode = sysv_new_inode(dir, S_IFDIR|mode);
134         err = PTR_ERR(inode);
135         if (IS_ERR(inode))
136                 goto out_dir;
137 
138         sysv_set_inode(inode, 0);
139 
140         inode_inc_link_count(inode);
141 
142         err = sysv_make_empty(inode, dir);
143         if (err)
144                 goto out_fail;
145 
146         err = sysv_add_link(dentry, inode);
147         if (err)
148                 goto out_fail;
149 
150         d_instantiate(dentry, inode);
151 out:
152         return err;
153 
154 out_fail:
155         inode_dec_link_count(inode);
156         inode_dec_link_count(inode);
157         iput(inode);
158 out_dir:
159         inode_dec_link_count(dir);
160         goto out;
161 }
162 
163 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
164 {
165         struct inode * inode = d_inode(dentry);
166         struct page * page;
167         struct sysv_dir_entry * de;
168         int err = -ENOENT;
169 
170         de = sysv_find_entry(dentry, &page);
171         if (!de)
172                 goto out;
173 
174         err = sysv_delete_entry (de, page);
175         if (err)
176                 goto out;
177 
178         inode->i_ctime = dir->i_ctime;
179         inode_dec_link_count(inode);
180 out:
181         return err;
182 }
183 
184 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
185 {
186         struct inode *inode = d_inode(dentry);
187         int err = -ENOTEMPTY;
188 
189         if (sysv_empty_dir(inode)) {
190                 err = sysv_unlink(dir, dentry);
191                 if (!err) {
192                         inode->i_size = 0;
193                         inode_dec_link_count(inode);
194                         inode_dec_link_count(dir);
195                 }
196         }
197         return err;
198 }
199 
200 /*
201  * Anybody can rename anything with this: the permission checks are left to the
202  * higher-level routines.
203  */
204 static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
205                        struct inode * new_dir, struct dentry * new_dentry,
206                        unsigned int flags)
207 {
208         struct inode * old_inode = d_inode(old_dentry);
209         struct inode * new_inode = d_inode(new_dentry);
210         struct page * dir_page = NULL;
211         struct sysv_dir_entry * dir_de = NULL;
212         struct page * old_page;
213         struct sysv_dir_entry * old_de;
214         int err = -ENOENT;
215 
216         if (flags & ~RENAME_NOREPLACE)
217                 return -EINVAL;
218 
219         old_de = sysv_find_entry(old_dentry, &old_page);
220         if (!old_de)
221                 goto out;
222 
223         if (S_ISDIR(old_inode->i_mode)) {
224                 err = -EIO;
225                 dir_de = sysv_dotdot(old_inode, &dir_page);
226                 if (!dir_de)
227                         goto out_old;
228         }
229 
230         if (new_inode) {
231                 struct page * new_page;
232                 struct sysv_dir_entry * new_de;
233 
234                 err = -ENOTEMPTY;
235                 if (dir_de && !sysv_empty_dir(new_inode))
236                         goto out_dir;
237 
238                 err = -ENOENT;
239                 new_de = sysv_find_entry(new_dentry, &new_page);
240                 if (!new_de)
241                         goto out_dir;
242                 sysv_set_link(new_de, new_page, old_inode);
243                 new_inode->i_ctime = current_time(new_inode);
244                 if (dir_de)
245                         drop_nlink(new_inode);
246                 inode_dec_link_count(new_inode);
247         } else {
248                 err = sysv_add_link(new_dentry, old_inode);
249                 if (err)
250                         goto out_dir;
251                 if (dir_de)
252                         inode_inc_link_count(new_dir);
253         }
254 
255         sysv_delete_entry(old_de, old_page);
256         mark_inode_dirty(old_inode);
257 
258         if (dir_de) {
259                 sysv_set_link(dir_de, dir_page, new_dir);
260                 inode_dec_link_count(old_dir);
261         }
262         return 0;
263 
264 out_dir:
265         if (dir_de) {
266                 kunmap(dir_page);
267                 put_page(dir_page);
268         }
269 out_old:
270         kunmap(old_page);
271         put_page(old_page);
272 out:
273         return err;
274 }
275 
276 /*
277  * directories can handle most operations...
278  */
279 const struct inode_operations sysv_dir_inode_operations = {
280         .create         = sysv_create,
281         .lookup         = sysv_lookup,
282         .link           = sysv_link,
283         .unlink         = sysv_unlink,
284         .symlink        = sysv_symlink,
285         .mkdir          = sysv_mkdir,
286         .rmdir          = sysv_rmdir,
287         .mknod          = sysv_mknod,
288         .rename         = sysv_rename,
289         .getattr        = sysv_getattr,
290 };
291 

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