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Linux/fs/ext2/namei.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * linux/fs/ext2/namei.c
  4  *
  5  * Rewrite to pagecache. Almost all code had been changed, so blame me
  6  * if the things go wrong. Please, send bug reports to
  7  * viro@parcelfarce.linux.theplanet.co.uk
  8  *
  9  * Stuff here is basically a glue between the VFS and generic UNIXish
 10  * filesystem that keeps everything in pagecache. All knowledge of the
 11  * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
 12  * and it's easier to debug that way. In principle we might want to
 13  * generalize that a bit and turn it into a library. Or not.
 14  *
 15  * The only non-static object here is ext2_dir_inode_operations.
 16  *
 17  * TODO: get rid of kmap() use, add readahead.
 18  *
 19  * Copyright (C) 1992, 1993, 1994, 1995
 20  * Remy Card (card@masi.ibp.fr)
 21  * Laboratoire MASI - Institut Blaise Pascal
 22  * Universite Pierre et Marie Curie (Paris VI)
 23  *
 24  *  from
 25  *
 26  *  linux/fs/minix/namei.c
 27  *
 28  *  Copyright (C) 1991, 1992  Linus Torvalds
 29  *
 30  *  Big-endian to little-endian byte-swapping/bitmaps by
 31  *        David S. Miller (davem@caip.rutgers.edu), 1995
 32  */
 33 
 34 #include <linux/pagemap.h>
 35 #include <linux/quotaops.h>
 36 #include "ext2.h"
 37 #include "xattr.h"
 38 #include "acl.h"
 39 
 40 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
 41 {
 42         int err = ext2_add_link(dentry, inode);
 43         if (!err) {
 44                 d_instantiate_new(dentry, inode);
 45                 return 0;
 46         }
 47         inode_dec_link_count(inode);
 48         discard_new_inode(inode);
 49         return err;
 50 }
 51 
 52 /*
 53  * Methods themselves.
 54  */
 55 
 56 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
 57 {
 58         struct inode * inode;
 59         ino_t ino;
 60         
 61         if (dentry->d_name.len > EXT2_NAME_LEN)
 62                 return ERR_PTR(-ENAMETOOLONG);
 63 
 64         ino = ext2_inode_by_name(dir, &dentry->d_name);
 65         inode = NULL;
 66         if (ino) {
 67                 inode = ext2_iget(dir->i_sb, ino);
 68                 if (inode == ERR_PTR(-ESTALE)) {
 69                         ext2_error(dir->i_sb, __func__,
 70                                         "deleted inode referenced: %lu",
 71                                         (unsigned long) ino);
 72                         return ERR_PTR(-EIO);
 73                 }
 74         }
 75         return d_splice_alias(inode, dentry);
 76 }
 77 
 78 struct dentry *ext2_get_parent(struct dentry *child)
 79 {
 80         struct qstr dotdot = QSTR_INIT("..", 2);
 81         unsigned long ino = ext2_inode_by_name(d_inode(child), &dotdot);
 82         if (!ino)
 83                 return ERR_PTR(-ENOENT);
 84         return d_obtain_alias(ext2_iget(child->d_sb, ino));
 85 } 
 86 
 87 /*
 88  * By the time this is called, we already have created
 89  * the directory cache entry for the new file, but it
 90  * is so far negative - it has no inode.
 91  *
 92  * If the create succeeds, we fill in the inode information
 93  * with d_instantiate(). 
 94  */
 95 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
 96 {
 97         struct inode *inode;
 98         int err;
 99 
100         err = dquot_initialize(dir);
101         if (err)
102                 return err;
103 
104         inode = ext2_new_inode(dir, mode, &dentry->d_name);
105         if (IS_ERR(inode))
106                 return PTR_ERR(inode);
107 
108         ext2_set_file_ops(inode);
109         mark_inode_dirty(inode);
110         return ext2_add_nondir(dentry, inode);
111 }
112 
113 static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
114 {
115         struct inode *inode = ext2_new_inode(dir, mode, NULL);
116         if (IS_ERR(inode))
117                 return PTR_ERR(inode);
118 
119         ext2_set_file_ops(inode);
120         mark_inode_dirty(inode);
121         d_tmpfile(dentry, inode);
122         unlock_new_inode(inode);
123         return 0;
124 }
125 
126 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
127 {
128         struct inode * inode;
129         int err;
130 
131         err = dquot_initialize(dir);
132         if (err)
133                 return err;
134 
135         inode = ext2_new_inode (dir, mode, &dentry->d_name);
136         err = PTR_ERR(inode);
137         if (!IS_ERR(inode)) {
138                 init_special_inode(inode, inode->i_mode, rdev);
139 #ifdef CONFIG_EXT2_FS_XATTR
140                 inode->i_op = &ext2_special_inode_operations;
141 #endif
142                 mark_inode_dirty(inode);
143                 err = ext2_add_nondir(dentry, inode);
144         }
145         return err;
146 }
147 
148 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
149         const char * symname)
150 {
151         struct super_block * sb = dir->i_sb;
152         int err = -ENAMETOOLONG;
153         unsigned l = strlen(symname)+1;
154         struct inode * inode;
155 
156         if (l > sb->s_blocksize)
157                 goto out;
158 
159         err = dquot_initialize(dir);
160         if (err)
161                 goto out;
162 
163         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
164         err = PTR_ERR(inode);
165         if (IS_ERR(inode))
166                 goto out;
167 
168         if (l > sizeof (EXT2_I(inode)->i_data)) {
169                 /* slow symlink */
170                 inode->i_op = &ext2_symlink_inode_operations;
171                 inode_nohighmem(inode);
172                 if (test_opt(inode->i_sb, NOBH))
173                         inode->i_mapping->a_ops = &ext2_nobh_aops;
174                 else
175                         inode->i_mapping->a_ops = &ext2_aops;
176                 err = page_symlink(inode, symname, l);
177                 if (err)
178                         goto out_fail;
179         } else {
180                 /* fast symlink */
181                 inode->i_op = &ext2_fast_symlink_inode_operations;
182                 inode->i_link = (char*)EXT2_I(inode)->i_data;
183                 memcpy(inode->i_link, symname, l);
184                 inode->i_size = l-1;
185         }
186         mark_inode_dirty(inode);
187 
188         err = ext2_add_nondir(dentry, inode);
189 out:
190         return err;
191 
192 out_fail:
193         inode_dec_link_count(inode);
194         discard_new_inode(inode);
195         goto out;
196 }
197 
198 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
199         struct dentry *dentry)
200 {
201         struct inode *inode = d_inode(old_dentry);
202         int err;
203 
204         err = dquot_initialize(dir);
205         if (err)
206                 return err;
207 
208         inode->i_ctime = current_time(inode);
209         inode_inc_link_count(inode);
210         ihold(inode);
211 
212         err = ext2_add_link(dentry, inode);
213         if (!err) {
214                 d_instantiate(dentry, inode);
215                 return 0;
216         }
217         inode_dec_link_count(inode);
218         iput(inode);
219         return err;
220 }
221 
222 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
223 {
224         struct inode * inode;
225         int err;
226 
227         err = dquot_initialize(dir);
228         if (err)
229                 return err;
230 
231         inode_inc_link_count(dir);
232 
233         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
234         err = PTR_ERR(inode);
235         if (IS_ERR(inode))
236                 goto out_dir;
237 
238         inode->i_op = &ext2_dir_inode_operations;
239         inode->i_fop = &ext2_dir_operations;
240         if (test_opt(inode->i_sb, NOBH))
241                 inode->i_mapping->a_ops = &ext2_nobh_aops;
242         else
243                 inode->i_mapping->a_ops = &ext2_aops;
244 
245         inode_inc_link_count(inode);
246 
247         err = ext2_make_empty(inode, dir);
248         if (err)
249                 goto out_fail;
250 
251         err = ext2_add_link(dentry, inode);
252         if (err)
253                 goto out_fail;
254 
255         d_instantiate_new(dentry, inode);
256 out:
257         return err;
258 
259 out_fail:
260         inode_dec_link_count(inode);
261         inode_dec_link_count(inode);
262         discard_new_inode(inode);
263 out_dir:
264         inode_dec_link_count(dir);
265         goto out;
266 }
267 
268 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
269 {
270         struct inode * inode = d_inode(dentry);
271         struct ext2_dir_entry_2 * de;
272         struct page * page;
273         int err;
274 
275         err = dquot_initialize(dir);
276         if (err)
277                 goto out;
278 
279         de = ext2_find_entry (dir, &dentry->d_name, &page);
280         if (!de) {
281                 err = -ENOENT;
282                 goto out;
283         }
284 
285         err = ext2_delete_entry (de, page);
286         if (err)
287                 goto out;
288 
289         inode->i_ctime = dir->i_ctime;
290         inode_dec_link_count(inode);
291         err = 0;
292 out:
293         return err;
294 }
295 
296 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
297 {
298         struct inode * inode = d_inode(dentry);
299         int err = -ENOTEMPTY;
300 
301         if (ext2_empty_dir(inode)) {
302                 err = ext2_unlink(dir, dentry);
303                 if (!err) {
304                         inode->i_size = 0;
305                         inode_dec_link_count(inode);
306                         inode_dec_link_count(dir);
307                 }
308         }
309         return err;
310 }
311 
312 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
313                         struct inode * new_dir, struct dentry * new_dentry,
314                         unsigned int flags)
315 {
316         struct inode * old_inode = d_inode(old_dentry);
317         struct inode * new_inode = d_inode(new_dentry);
318         struct page * dir_page = NULL;
319         struct ext2_dir_entry_2 * dir_de = NULL;
320         struct page * old_page;
321         struct ext2_dir_entry_2 * old_de;
322         int err;
323 
324         if (flags & ~RENAME_NOREPLACE)
325                 return -EINVAL;
326 
327         err = dquot_initialize(old_dir);
328         if (err)
329                 goto out;
330 
331         err = dquot_initialize(new_dir);
332         if (err)
333                 goto out;
334 
335         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
336         if (!old_de) {
337                 err = -ENOENT;
338                 goto out;
339         }
340 
341         if (S_ISDIR(old_inode->i_mode)) {
342                 err = -EIO;
343                 dir_de = ext2_dotdot(old_inode, &dir_page);
344                 if (!dir_de)
345                         goto out_old;
346         }
347 
348         if (new_inode) {
349                 struct page *new_page;
350                 struct ext2_dir_entry_2 *new_de;
351 
352                 err = -ENOTEMPTY;
353                 if (dir_de && !ext2_empty_dir (new_inode))
354                         goto out_dir;
355 
356                 err = -ENOENT;
357                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
358                 if (!new_de)
359                         goto out_dir;
360                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
361                 new_inode->i_ctime = current_time(new_inode);
362                 if (dir_de)
363                         drop_nlink(new_inode);
364                 inode_dec_link_count(new_inode);
365         } else {
366                 err = ext2_add_link(new_dentry, old_inode);
367                 if (err)
368                         goto out_dir;
369                 if (dir_de)
370                         inode_inc_link_count(new_dir);
371         }
372 
373         /*
374          * Like most other Unix systems, set the ctime for inodes on a
375          * rename.
376          */
377         old_inode->i_ctime = current_time(old_inode);
378         mark_inode_dirty(old_inode);
379 
380         ext2_delete_entry (old_de, old_page);
381 
382         if (dir_de) {
383                 if (old_dir != new_dir)
384                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
385                 else {
386                         kunmap(dir_page);
387                         put_page(dir_page);
388                 }
389                 inode_dec_link_count(old_dir);
390         }
391         return 0;
392 
393 
394 out_dir:
395         if (dir_de) {
396                 kunmap(dir_page);
397                 put_page(dir_page);
398         }
399 out_old:
400         kunmap(old_page);
401         put_page(old_page);
402 out:
403         return err;
404 }
405 
406 const struct inode_operations ext2_dir_inode_operations = {
407         .create         = ext2_create,
408         .lookup         = ext2_lookup,
409         .link           = ext2_link,
410         .unlink         = ext2_unlink,
411         .symlink        = ext2_symlink,
412         .mkdir          = ext2_mkdir,
413         .rmdir          = ext2_rmdir,
414         .mknod          = ext2_mknod,
415         .rename         = ext2_rename,
416 #ifdef CONFIG_EXT2_FS_XATTR
417         .listxattr      = ext2_listxattr,
418 #endif
419         .getattr        = ext2_getattr,
420         .setattr        = ext2_setattr,
421         .get_acl        = ext2_get_acl,
422         .set_acl        = ext2_set_acl,
423         .tmpfile        = ext2_tmpfile,
424 };
425 
426 const struct inode_operations ext2_special_inode_operations = {
427 #ifdef CONFIG_EXT2_FS_XATTR
428         .listxattr      = ext2_listxattr,
429 #endif
430         .getattr        = ext2_getattr,
431         .setattr        = ext2_setattr,
432         .get_acl        = ext2_get_acl,
433         .set_acl        = ext2_set_acl,
434 };
435 

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