This source file includes following definitions.
- fcntl_init_locks
- fcntl_getlk
- fcntl_setlk
- fcntl_remove_locks
- copy_flock
- conflict
- overlap
- lock_it
- unlock_it
- alloc_lock
- free_lock
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13 #include <asm/segment.h>
14
15 #include <linux/sched.h>
16 #include <linux/kernel.h>
17 #include <linux/errno.h>
18 #include <linux/stat.h>
19 #include <linux/fcntl.h>
20
21 #define OFFSET_MAX 0x7fffffff
22
23 static int copy_flock(struct file *filp, struct file_lock *fl, struct flock *l);
24 static int conflict(struct file_lock *caller_fl, struct file_lock *sys_fl);
25 static int overlap(struct file_lock *fl1, struct file_lock *fl2);
26 static int lock_it(struct file *filp, struct file_lock *caller);
27 static int unlock_it(struct file *filp, struct file_lock *caller);
28 static struct file_lock *alloc_lock(struct file *filp, struct file_lock *template);
29 static void free_lock(struct file *filp, struct file_lock *fl);
30
31 static struct file_lock file_lock_table[NR_FILE_LOCKS];
32 static struct file_lock *file_lock_free_list;
33
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36
37
38 void fcntl_init_locks(void)
39 {
40 struct file_lock *fl;
41
42 for (fl = &file_lock_table[0]; fl < file_lock_table + NR_FILE_LOCKS - 1; fl++) {
43 fl->fl_next = fl + 1;
44 fl->fl_owner = NULL;
45 }
46 file_lock_table[NR_FILE_LOCKS - 1].fl_next = NULL;
47 file_lock_table[NR_FILE_LOCKS - 1].fl_owner = NULL;
48 file_lock_free_list = &file_lock_table[0];
49 }
50
51 int fcntl_getlk(unsigned int fd, struct flock *l)
52 {
53 struct flock flock;
54 struct file *filp;
55 struct file_lock *fl,file_lock;
56
57 if (fd >= NR_OPEN || !(filp = current->filp[fd]))
58 return -EBADF;
59 verify_area(l, sizeof(*l));
60 memcpy_fromfs(&flock, l, sizeof(flock));
61 if (flock.l_type == F_UNLCK)
62 return -EINVAL;
63 if (!copy_flock(filp, &file_lock, &flock))
64 return -EINVAL;
65
66 for (fl = filp->f_inode->i_flock; fl != NULL; fl = fl->fl_next) {
67 if (conflict(&file_lock, fl)) {
68 flock.l_pid = fl->fl_owner->pid;
69 flock.l_start = fl->fl_start;
70 flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
71 fl->fl_end - fl->fl_start + 1;
72 flock.l_whence = fl->fl_whence;
73 flock.l_type = fl->fl_type;
74 memcpy_tofs(l, &flock, sizeof(flock));
75 return 0;
76 }
77 }
78
79 flock.l_type = F_UNLCK;
80 memcpy_tofs(l, &flock, sizeof(flock));
81 return 0;
82 }
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87
88 int fcntl_setlk(unsigned int fd, unsigned int cmd, struct flock *l)
89 {
90 struct file *filp;
91 struct file_lock *fl,file_lock;
92 struct flock flock;
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98 if (fd >= NR_OPEN || !(filp = current->filp[fd]))
99 return -EBADF;
100 verify_area(l, sizeof(*l));
101 memcpy_fromfs(&flock, l, sizeof(flock));
102 if (!copy_flock(filp, &file_lock, &flock))
103 return -EINVAL;
104 switch (file_lock.fl_type) {
105 case F_RDLCK :
106 if (!(filp->f_mode & 1))
107 return -EBADF;
108 break;
109 case F_WRLCK :
110 if (!(filp->f_mode & 2))
111 return -EBADF;
112 break;
113 case F_UNLCK :
114 break;
115 }
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120
121 if (file_lock.fl_type == F_UNLCK)
122 return unlock_it(filp, &file_lock);
123
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127
128 repeat:
129 for (fl = filp->f_inode->i_flock; fl != NULL; fl = fl->fl_next) {
130 if (!conflict(&file_lock, fl))
131 continue;
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137 if (cmd == F_SETLKW) {
138 interruptible_sleep_on(&fl->fl_wait);
139 goto repeat;
140 }
141 return -EAGAIN;
142 }
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148 return lock_it(filp, &file_lock);
149 }
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154
155 void fcntl_remove_locks(struct task_struct *task, struct file *filp)
156 {
157 struct file_lock *fl,*next;
158
159 for (fl = filp->f_inode->i_flock; fl != NULL; ) {
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164 next = fl->fl_next;
165 if (fl->fl_owner == task)
166 free_lock(filp, fl);
167 fl = next;
168 }
169 }
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175
176 static int copy_flock(struct file *filp, struct file_lock *fl, struct flock *l)
177 {
178 off_t start;
179
180 if (!filp->f_inode)
181 return 0;
182 if (!S_ISREG(filp->f_inode->i_mode))
183 return 0;
184 if (l->l_type != F_UNLCK && l->l_type != F_RDLCK && l->l_type != F_WRLCK)
185 return 0;
186 switch (l->l_whence) {
187 case 0 : start = 0; break;
188 case 1 : start = filp->f_pos; break;
189 case 2 : start = filp->f_inode->i_size; break;
190 default : return 0;
191 }
192 if ((start += l->l_start) < 0 || l->l_len < 0)
193 return 0;
194 fl->fl_type = l->l_type;
195 fl->fl_start = start;
196 fl->fl_whence = 0;
197 if (l->l_len == 0 || (fl->fl_end = start + l->l_len - 1) < 0)
198 fl->fl_end = OFFSET_MAX;
199 fl->fl_owner = current;
200 fl->fl_wait = NULL;
201 return 1;
202 }
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207
208 static int conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
209 {
210 if (caller_fl->fl_owner == sys_fl->fl_owner)
211 return 0;
212 if (!overlap(caller_fl, sys_fl))
213 return 0;
214 switch (caller_fl->fl_type) {
215 case F_RDLCK :
216 return sys_fl->fl_type != F_RDLCK;
217 case F_WRLCK :
218 return 1;
219 }
220 return 0;
221 }
222
223 static int overlap(struct file_lock *fl1, struct file_lock *fl2)
224 {
225 if (fl1->fl_start <= fl2->fl_start) {
226 return fl1->fl_end >= fl2->fl_start;
227 } else {
228 return fl2->fl_end >= fl1->fl_start;
229 }
230 }
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246 static int lock_it(struct file *filp, struct file_lock *caller)
247 {
248 struct file_lock *fl,*new;
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258 if ((caller = alloc_lock(filp, caller)) == NULL)
259 return -ENOLCK;
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265 for (fl = filp->f_inode->i_flock; fl != NULL; fl = fl->fl_next) {
266 if (caller->fl_owner != fl->fl_owner)
267 continue;
268 if (caller == fl)
269 continue;
270 if (!overlap(caller, fl)) {
271
272
273
274 if (caller->fl_type != fl->fl_type)
275 continue;
276 if (caller->fl_end + 1 == fl->fl_start) {
277 fl->fl_start = caller->fl_start;
278 free_lock(filp, caller);
279 caller = fl;
280
281 } else if (caller->fl_start - 1 == fl->fl_end) {
282 fl->fl_end = caller->fl_end;
283 free_lock(filp, caller);
284 caller = fl;
285
286 }
287 continue;
288 }
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293 if (caller->fl_type != fl->fl_type) {
294 if (caller->fl_start > fl->fl_start && caller->fl_end < fl->fl_end) {
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300 if ((new = alloc_lock(filp, fl)) == NULL) {
301 free_lock(filp, caller);
302 return -ENOLCK;
303 }
304 fl->fl_end = caller->fl_start - 1;
305 new->fl_start = caller->fl_end + 1;
306 return 0;
307 }
308 if (caller->fl_start <= fl->fl_start && caller->fl_end >= fl->fl_end) {
309
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312 free_lock(filp, fl);
313 return 0;
314 }
315 if (caller->fl_end < fl->fl_end) {
316 fl->fl_start = caller->fl_end + 1;
317
318 } else if (caller->fl_start > fl->fl_start) {
319 fl->fl_end = caller->fl_start - 1;
320
321 } else {
322 printk("lock_it: program bug: unanticipated overlap\n");
323 free_lock(filp, caller);
324 return -ENOLCK;
325 }
326 } else {
327 int grew = 0;
328
329 if (caller->fl_start < fl->fl_start) {
330 fl->fl_start = caller->fl_start;
331 grew = 1;
332 }
333 if (caller->fl_end > fl->fl_end) {
334 fl->fl_end = caller->fl_end;
335 grew = 1;
336 }
337 free_lock(filp, caller);
338 caller = fl;
339 if (!grew)
340 return 0;
341
342 }
343 }
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349
350 return 0;
351 }
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359 static int unlock_it(struct file *filp, struct file_lock *caller)
360 {
361 int one_unlocked = 0;
362 struct file_lock *fl,*next;
363
364 for (fl = filp->f_inode->i_flock; fl != NULL; ) {
365 if (caller->fl_owner != fl->fl_owner || !overlap(caller, fl)) {
366 fl = fl->fl_next;
367 continue;
368 }
369 one_unlocked = 1;
370 if (caller->fl_start > fl->fl_start && caller->fl_end < fl->fl_end) {
371
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374
375 if ((next = alloc_lock(filp, fl)) == NULL)
376 return -ENOLCK;
377 fl->fl_end = caller->fl_start - 1;
378 next->fl_start = caller->fl_end + 1;
379 return 0;
380 }
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398 next = fl->fl_next;
399 if (caller->fl_start <= fl->fl_start && caller->fl_end >= fl->fl_end) {
400 free_lock(filp, fl);
401 } else if (caller->fl_start > fl->fl_start) {
402 fl->fl_end = caller->fl_start - 1;
403 } else {
404
405 fl->fl_start = caller->fl_end + 1;
406 }
407 if (caller->fl_start >= fl->fl_start && caller->fl_end <= fl->fl_end)
408 return 0;
409 fl = next;
410
411 }
412
413 return one_unlocked ? 0 : -EINVAL;
414 }
415
416 static struct file_lock *alloc_lock(struct file *filp, struct file_lock *template)
417 {
418 struct file_lock *new;
419
420 if (file_lock_free_list == NULL)
421 return NULL;
422 if (file_lock_free_list->fl_owner != NULL)
423 panic("alloc_lock: broken free list\n");
424
425 new = file_lock_free_list;
426 file_lock_free_list = file_lock_free_list->fl_next;
427
428 *new = *template;
429
430 new->fl_next = filp->f_inode->i_flock;
431 filp->f_inode->i_flock = new;
432
433 new->fl_owner = current;
434 new->fl_wait = NULL;
435 return new;
436 }
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443
444 static void free_lock(struct file *filp, struct file_lock *fl)
445 {
446 struct file_lock **fl_p;
447
448 if (fl->fl_owner == NULL)
449 panic("free_lock: broken lock list\n");
450
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456 for (fl_p = &filp->f_inode->i_flock; *fl_p != NULL; fl_p = &(*fl_p)->fl_next) {
457 if (*fl_p == fl)
458 break;
459 }
460 if (*fl_p == NULL) {
461 printk("free_lock: lock is not in file's lock list\n");
462 } else {
463 *fl_p = (*fl_p)->fl_next;
464 }
465
466 fl->fl_next = file_lock_free_list;
467 file_lock_free_list = fl;
468 fl->fl_owner = NULL;
469
470 wake_up(&fl->fl_wait);
471 }