![[first]](../icons/first.png){kind=icon}
![[previous]](../icons/n_left.png){kind=icon}
![[next]](../icons/n_right.png){kind=icon}
![[last]](../icons/last.png){kind=icon}
![[top]](../icons/n_top.png){kind=icon}
![[bottom]](../icons/bottom.png){kind=icon}
![[index]](../icons/index.png){kind=icon}
![[help]](../icons/help.png){kind=icon}
*/
1 /*
2 * linux/fs/umsdos/inode.c
3 *
4 * Written 1993 by Jacques Gelinas
5 * Inspired from linux/fs/msdos/... by Werner Almesberger
6 *
7 */
8
9 #include <linux/module.h>
10
11 #include <linux/fs.h>
12 #include <linux/msdos_fs.h>
13 #include <linux/kernel.h>
14 #include <linux/sched.h>
15 #include <linux/errno.h>
16 #include <asm/segment.h>
17 #include <linux/string.h>
18 #include <linux/stat.h>
19 #include <linux/umsdos_fs.h>
20
21 struct inode *pseudo_root=NULL; /* Useful to simulate the pseudo DOS */
22 /* directory. See UMSDOS_readdir_x() */
23
24 /* #Specification: convention / PRINTK Printk and printk
25 Here is the convention for the use of printk inside fs/umsdos
26
27 printk carry important message (error or status).
28 Printk is for debugging (it is a macro defined at the beginning of
29 most source.
30 PRINTK is a nulled Printk macro.
31
32 This convention makes the source easier to read, and Printk easier
33 to shut off.
34 */
35 #define PRINTK(x)
36 #define Printk(x) printk x
37
38
39 void UMSDOS_put_inode(struct inode *inode)
/* ![[next]](../icons/right.png)
![[first]](../icons/n_first.png)
![[top]](../icons/top.png)
*/
40 {
41 PRINTK (("put inode %x owner %x pos %d dir %x\n",inode
42 ,inode->u.umsdos_i.i_emd_owner,inode->u.umsdos_i.pos
43 ,inode->u.umsdos_i.i_emd_dir));
44 if (inode != NULL && inode == pseudo_root){
45 printk ("Umsdos: Oops releasing pseudo_root. Notify jacques@solucorp.qc.ca\n");
46 }
47 msdos_put_inode(inode);
48 }
49
50
51 void UMSDOS_put_super(struct super_block *sb)
/* ![[previous]](../icons/left.png)
*/
52 {
53 msdos_put_super(sb);
54 MOD_DEC_USE_COUNT;
55 }
56
57
58 void UMSDOS_statfs(struct super_block *sb,struct statfs *buf, int bufsiz)
/* */
59 {
60 msdos_statfs(sb,buf,bufsiz);
61 }
62
63
64 /*
65 Call msdos_lookup, but set back the original msdos function table.
66 Return 0 if ok, or a negative error code if not.
67 */
68 int umsdos_real_lookup (
/* */
69 struct inode *dir,
70 const char *name,
71 int len,
72 struct inode **result) /* Will hold inode of the file, if successful */
73 {
74 int ret;
75 dir->i_count++;
76 ret = msdos_lookup (dir,name,len,result);
77 return ret;
78 }
79 /*
80 Complete the setup of an directory inode.
81 First, it completes the function pointers, then
82 it locates the EMD file. If the EMD is there, then plug the
83 umsdos function table. If not, use the msdos one.
84 */
85 void umsdos_setup_dir_inode (struct inode *inode)
/* */
86 {
87 inode->u.umsdos_i.i_emd_dir = 0;
88 {
89 struct inode *emd_dir = umsdos_emd_dir_lookup (inode,0);
90 extern struct inode_operations umsdos_rdir_inode_operations;
91 inode->i_op = emd_dir != NULL
92 ? &umsdos_dir_inode_operations
93 : &umsdos_rdir_inode_operations;
94 iput (emd_dir);
95 }
96 }
97 /*
98 Add some info into an inode so it can find its owner quickly
99 */
100 void umsdos_set_dirinfo(
/* */
101 struct inode *inode,
102 struct inode *dir,
103 off_t f_pos)
104 {
105 struct inode *emd_owner = umsdos_emd_dir_lookup(dir,1);
106 inode->u.umsdos_i.i_dir_owner = dir->i_ino;
107 inode->u.umsdos_i.i_emd_owner = emd_owner->i_ino;
108 iput (emd_owner);
109 inode->u.umsdos_i.pos = f_pos;
110 }
111 /*
112 Tells if an Umsdos inode has been "patched" once.
113 Return != 0 if so.
114 */
115 int umsdos_isinit (struct inode *inode)
/* */
116 {
117 #if 1
118 return inode->u.umsdos_i.i_emd_owner != 0;
119 #elif 0
120 return inode->i_atime != 0;
121 #else
122 return inode->i_count > 1;
123 #endif
124 }
125 /*
126 Connect the proper tables in the inode and add some info.
127 */
128 void umsdos_patch_inode (
/* */
129 struct inode *inode,
130 struct inode *dir, /* May be NULL */
131 off_t f_pos)
132 {
133 /*
134 This function is called very early to setup the inode, somewhat
135 too early (called by UMSDOS_read_inode). At this point, we can't
136 do to much, such as lookup up EMD files and so on. This causes
137 confusion in the kernel. This is why some initialisation
138 will be done when dir != NULL only.
139
140 UMSDOS do run piggy back on top of msdos fs. It looks like something
141 is missing in the VFS to accommodate stacked fs. Still unclear what
142 (quite honestly).
143
144 Well, maybe one! A new entry "may_unmount" which would allow
145 the stacked fs to allocate some inode permanently and release
146 them at the end. Doing that now introduce a problem. unmount
147 always fail because some inodes are in use.
148 */
149 if (!umsdos_isinit(inode)){
150 inode->u.umsdos_i.i_emd_dir = 0;
151 if (S_ISREG(inode->i_mode)){
152 if (inode->i_op->bmap != NULL){
153 inode->i_op = &umsdos_file_inode_operations;
154 }else{
155 inode->i_op = &umsdos_file_inode_operations_no_bmap;
156 }
157 }else if (S_ISDIR(inode->i_mode)){
158 if (dir != NULL){
159 umsdos_setup_dir_inode(inode);
160 }
161 }else if (S_ISLNK(inode->i_mode)){
162 inode->i_op = &umsdos_symlink_inode_operations;
163 }else if (S_ISCHR(inode->i_mode)){
164 inode->i_op = &chrdev_inode_operations;
165 }else if (S_ISBLK(inode->i_mode)){
166 inode->i_op = &blkdev_inode_operations;
167 }else if (S_ISFIFO(inode->i_mode)){
168 init_fifo(inode);
169 }
170 if (dir != NULL){
171 /* #Specification: inode / umsdos info
172 The first time an inode is seen (inode->i_count == 1),
173 the inode number of the EMD file which control this inode
174 is tagged to this inode. It allows operation such
175 as notify_change to be handled.
176 */
177 /*
178 This is done last because it also control the
179 status of umsdos_isinit()
180 */
181 umsdos_set_dirinfo (inode,dir,f_pos);
182 }
183 }else if (dir != NULL){
184 /*
185 Test to see if the info is maintained.
186 This should be removed when the file system will be proven.
187 */
188 struct inode *emd_owner = umsdos_emd_dir_lookup(dir,1);
189 iput (emd_owner);
190 if (emd_owner->i_ino != inode->u.umsdos_i.i_emd_owner){
191 printk ("UMSDOS: *** EMD_OWNER ??? *** ino = %ld %ld <> %ld "
192 ,inode->i_ino,emd_owner->i_ino,inode->u.umsdos_i.i_emd_owner);
193 }
194 }
195 }
196 /*
197 Get the inode of the directory which owns this inode.
198 Return 0 if ok, -EIO if error.
199 */
200 int umsdos_get_dirowner(
/* */
201 struct inode *inode,
202 struct inode **result) /* Hold NULL if any error */
203 /* else, the inode of the directory */
204 {
205 int ret = -EIO;
206 unsigned long ino = inode->u.umsdos_i.i_dir_owner;
207 *result = NULL;
208 if (ino == 0){
209 printk ("UMSDOS: umsdos_get_dirowner ino == 0\n");
210 }else{
211 struct inode *dir = *result = iget(inode->i_sb,ino);
212 if (dir != NULL){
213 umsdos_patch_inode (dir,NULL,0);
214 ret = 0;
215 }
216 }
217 return ret;
218 }
219 /*
220 Load an inode from disk.
221 */
222 void UMSDOS_read_inode(struct inode *inode)
/* */
223 {
224 PRINTK (("read inode %x ino = %d ",inode,inode->i_ino));
225 msdos_read_inode(inode);
226 PRINTK (("ino = %d %d\n",inode->i_ino,inode->i_count));
227 if (S_ISDIR(inode->i_mode)
228 && (inode->u.umsdos_i.u.dir_info.creating != 0
229 || inode->u.umsdos_i.u.dir_info.looking != 0
230 || inode->u.umsdos_i.u.dir_info.p != NULL)){
231 Printk (("read inode %d %d %p\n"
232 ,inode->u.umsdos_i.u.dir_info.creating
233 ,inode->u.umsdos_i.u.dir_info.looking
234 ,inode->u.umsdos_i.u.dir_info.p));
235 }
236 /* #Specification: Inode / post initialisation
237 To completely initialise an inode, we need access to the owner
238 directory, so we can locate more info in the EMD file. This is
239 not available the first time the inode is access, we use
240 a value in the inode to tell if it has been finally initialised.
241
242 At first, we have tried testing i_count but it was causing
243 problem. It is possible that two or more process use the
244 newly accessed inode. While the first one block during
245 the initialisation (probably while reading the EMD file), the
246 others believe all is well because i_count > 1. They go banana
247 with a broken inode. See umsdos_lookup_patch and umsdos_patch_inode.
248 */
249 umsdos_patch_inode(inode,NULL,0);
250 }
251
252 /*
253 Update the disk with the inode content
254 */
255 void UMSDOS_write_inode(struct inode *inode)
/* */
256 {
257 struct iattr newattrs;
258
259 PRINTK (("UMSDOS_write_inode emd %d\n",inode->u.umsdos_i.i_emd_owner));
260 msdos_write_inode(inode);
261 newattrs.ia_mtime = inode->i_mtime;
262 newattrs.ia_atime = inode->i_atime;
263 newattrs.ia_ctime = inode->i_ctime;
264 newattrs.ia_valid = ATTR_MTIME | ATTR_ATIME | ATTR_CTIME;
265 /*
266 UMSDOS_notify_change is convenient to call here
267 to update the EMD entry associated with this inode.
268 But it has the side effect to re"dirt" the inode.
269 */
270 UMSDOS_notify_change (inode, &newattrs);
271 inode->i_dirt = 0;
272 }
273
274 int UMSDOS_notify_change(struct inode *inode, struct iattr *attr)
/* */
275 {
276 int ret = 0;
277
278 if ((ret = inode_change_ok(inode, attr)) != 0)
279 return ret;
280
281 if (inode->i_nlink > 0){
282 /* #Specification: notify_change / i_nlink > 0
283 notify change is only done for inode with nlink > 0. An inode
284 with nlink == 0 is no longer associated with any entry in
285 the EMD file, so there is nothing to update.
286 */
287 unsigned long i_emd_owner = inode->u.umsdos_i.i_emd_owner;
288 if (inode == inode->i_sb->s_mounted){
289 /* #Specification: root inode / attributes
290 I don't know yet how this should work. Normally
291 the attributes (permissions bits, owner, times) of
292 a directory are stored in the EMD file of its parent.
293
294 One thing we could do is store the attributes of the root
295 inode in its own EMD file. A simple entry named "." could
296 be used for this special case. It would be read once
297 when the file system is mounted and update in
298 UMSDOS_notify_change() (right here).
299
300 I am not sure of the behavior of the root inode for
301 a real UNIX file system. For now, this is a nop.
302 */
303 }else if (i_emd_owner != 0xffffffff && i_emd_owner != 0){
304 /* This inode is not a EMD file nor an inode used internally
305 by MSDOS, so we can update its status.
306 See emd.c
307 */
308 struct inode *emd_owner = iget (inode->i_sb,i_emd_owner);
309 PRINTK (("notify change %p ",inode));
310 if (emd_owner == NULL){
311 printk ("UMSDOS: emd_owner = NULL ???");
312 ret = -EPERM;
313 }else{
314 struct file filp;
315 struct umsdos_dirent entry;
316 filp.f_pos = inode->u.umsdos_i.pos;
317 filp.f_reada = 0;
318 PRINTK (("pos = %d ",filp.f_pos));
319 /* Read only the start of the entry since we don't touch */
320 /* the name */
321 ret = umsdos_emd_dir_read (emd_owner,&filp,(char*)&entry
322 ,UMSDOS_REC_SIZE);
323 if (ret == 0){
324 if (attr->ia_valid & ATTR_UID)
325 entry.uid = attr->ia_uid;
326 if (attr->ia_valid & ATTR_GID)
327 entry.gid = attr->ia_gid;
328 if (attr->ia_valid & ATTR_MODE)
329 entry.mode = attr->ia_mode;
330 if (attr->ia_valid & ATTR_ATIME)
331 entry.atime = attr->ia_atime;
332 if (attr->ia_valid & ATTR_MTIME)
333 entry.mtime = attr->ia_mtime;
334 if (attr->ia_valid & ATTR_CTIME)
335 entry.ctime = attr->ia_ctime;
336
337 entry.nlink = inode->i_nlink;
338 filp.f_pos = inode->u.umsdos_i.pos;
339 ret = umsdos_emd_dir_write (emd_owner,&filp,(char*)&entry
340 ,UMSDOS_REC_SIZE);
341
342 PRINTK (("notify pos %d ret %d nlink %d "
343 ,inode->u.umsdos_i.pos
344 ,ret,entry.nlink));
345 /* #Specification: notify_change / msdos fs
346 notify_change operation are done only on the
347 EMD file. The msdos fs is not even called.
348 */
349 }
350 iput (emd_owner);
351 }
352 PRINTK (("\n"));
353 }
354 }
355 if (ret == 0)
356 inode_setattr(inode, attr);
357 return ret;
358 }
359
360 /* #Specification: function name / convention
361 A simple convention for function name has been used in
362 the UMSDOS file system. First all function use the prefix
363 umsdos_ to avoid name clash with other part of the kernel.
364
365 And standard VFS entry point use the prefix UMSDOS (upper case)
366 so it's easier to tell them apart.
367 */
368
369 static struct super_operations umsdos_sops = {
370 UMSDOS_read_inode,
371 UMSDOS_notify_change,
372 UMSDOS_write_inode,
373 UMSDOS_put_inode,
374 UMSDOS_put_super,
375 NULL, /* added in 0.96c */
376 UMSDOS_statfs,
377 NULL
378 };
379
380 /*
381 Read the super block of an Extended MS-DOS FS.
382 */
383 struct super_block *UMSDOS_read_super(
/* */
384 struct super_block *s,
385 void *data,
386 int silent)
387 {
388 /* #Specification: mount / options
389 Umsdos run on top of msdos. Currently, it supports no
390 mount option, but happily pass all option received to
391 the msdos driver. I am not sure if all msdos mount option
392 make sense with Umsdos. Here are at least those who
393 are useful.
394 uid=
395 gid=
396
397 These options affect the operation of umsdos in directories
398 which do not have an EMD file. They behave like normal
399 msdos directory, with all limitation of msdos.
400 */
401 struct super_block *sb;
402 MOD_INC_USE_COUNT;
403 sb = msdos_read_super(s,data,silent);
404 printk ("UMSDOS Beta 0.6 (compatibility level %d.%d, fast msdos)\n"
405 ,UMSDOS_VERSION,UMSDOS_RELEASE);
406 if (sb != NULL){
407 MSDOS_SB(sb)->dotsOK = 0; /* disable hidden==dotfile */
408 sb->s_op = &umsdos_sops;
409 PRINTK (("umsdos_read_super %p\n",sb->s_mounted));
410 umsdos_setup_dir_inode (sb->s_mounted);
411 PRINTK (("End umsdos_read_super\n"));
412 if (s == super_blocks){
413 /* #Specification: pseudo root / mount
414 When a umsdos fs is mounted, a special handling is done
415 if it is the root partition. We check for the presence
416 of the file /linux/etc/init or /linux/etc/rc or
417 /linux/sbin/init. If one is there, we do a chroot("/linux").
418
419 We check both because (see init/main.c) the kernel
420 try to exec init at different place and if it fails
421 it tries /bin/sh /etc/rc. To be consistent with
422 init/main.c, many more test would have to be done
423 to locate init. Any complain ?
424
425 The chroot is done manually in init/main.c but the
426 info (the inode) is located at mount time and store
427 in a global variable (pseudo_root) which is used at
428 different place in the umsdos driver. There is no
429 need to store this variable elsewhere because it
430 will always be one, not one per mount.
431
432 This feature allows the installation
433 of a linux system within a DOS system in a subdirectory.
434
435 A user may install its linux stuff in c:\linux
436 avoiding any clash with existing DOS file and subdirectory.
437 When linux boots, it hides this fact, showing a normal
438 root directory with /etc /bin /tmp ...
439
440 The word "linux" is hardcoded in /usr/include/linux/umsdos_fs.h
441 in the macro UMSDOS_PSDROOT_NAME.
442 */
443
444 struct inode *pseudo;
445 Printk (("Mounting root\n"));
446 if (umsdos_real_lookup (sb->s_mounted,UMSDOS_PSDROOT_NAME
447 ,UMSDOS_PSDROOT_LEN,&pseudo)==0
448 && S_ISDIR(pseudo->i_mode)){
449 struct inode *etc = NULL;
450 struct inode *sbin = NULL;
451 int pseudo_ok = 0;
452 Printk (("/%s is there\n",UMSDOS_PSDROOT_NAME));
453 if (umsdos_real_lookup (pseudo,"etc",3,&etc)==0
454 && S_ISDIR(etc->i_mode)){
455 struct inode *init = NULL;
456 struct inode *rc = NULL;
457 Printk (("/%s/etc is there\n",UMSDOS_PSDROOT_NAME));
458 if ((umsdos_real_lookup (etc,"init",4,&init)==0
459 && S_ISREG(init->i_mode))
460 || (umsdos_real_lookup (etc,"rc",2,&rc)==0
461 && S_ISREG(rc->i_mode))){
462 pseudo_ok = 1;
463 }
464 iput (init);
465 iput (rc);
466 }
467 if (!pseudo_ok
468 && umsdos_real_lookup (pseudo,"sbin",4,&sbin)==0
469 && S_ISDIR(sbin->i_mode)){
470 struct inode *init = NULL;
471 Printk (("/%s/sbin is there\n",UMSDOS_PSDROOT_NAME));
472 if (umsdos_real_lookup (sbin,"init",4,&init)==0
473 && S_ISREG(init->i_mode)){
474 pseudo_ok = 1;
475 }
476 iput (init);
477 }
478 if (pseudo_ok){
479 umsdos_setup_dir_inode (pseudo);
480 Printk (("Activating pseudo root /%s\n",UMSDOS_PSDROOT_NAME));
481 pseudo_root = pseudo;
482 pseudo->i_count++;
483 pseudo = NULL;
484 }
485 iput (sbin);
486 iput (etc);
487 }
488 iput (pseudo);
489 }
490 } else {
491 MOD_DEC_USE_COUNT;
492 }
493 return sb;
494 }
495
496
497 #ifdef MODULE
498
499 static struct file_system_type umsdos_fs_type = {
500 UMSDOS_read_super, "umsdos", 1, NULL
501 };
502
503 int init_module(void)
/* */
504 {
505 return register_filesystem(&umsdos_fs_type);
506 }
507
508 void cleanup_module(void)
/* ![[last]](../icons/n_last.png)
*/
509 {
510 unregister_filesystem(&umsdos_fs_type);
511 }
512
513 #endif
514
![[bottom]](../icons/n_bottom.png){kind=icon}
*/