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9#include <linux/module.h>
10#include <linux/fs.h>
11#include <linux/mm.h>
12#include <linux/mmzone.h>
13#include <linux/time.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
16#include <linux/vmalloc.h>
17#include <linux/file.h>
18#include <linux/fdtable.h>
19#include <linux/bitops.h>
20#include <linux/interrupt.h>
21#include <linux/spinlock.h>
22#include <linux/rcupdate.h>
23#include <linux/workqueue.h>
24
25struct fdtable_defer {
26 spinlock_t lock;
27 struct work_struct wq;
28 struct fdtable *next;
29};
30
31int sysctl_nr_open __read_mostly = 1024*1024;
32int sysctl_nr_open_min = BITS_PER_LONG;
33int sysctl_nr_open_max = 1024 * 1024;
34
35
36
37
38
39
40
41static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);
42
43static void *alloc_fdmem(unsigned int size)
44{
45
46
47
48
49 if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
50 void *data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN);
51 if (data != NULL)
52 return data;
53 }
54 return vmalloc(size);
55}
56
57static void free_fdmem(void *ptr)
58{
59 is_vmalloc_addr(ptr) ? vfree(ptr) : kfree(ptr);
60}
61
62static void __free_fdtable(struct fdtable *fdt)
63{
64 free_fdmem(fdt->fd);
65 free_fdmem(fdt->open_fds);
66 kfree(fdt);
67}
68
69static void free_fdtable_work(struct work_struct *work)
70{
71 struct fdtable_defer *f =
72 container_of(work, struct fdtable_defer, wq);
73 struct fdtable *fdt;
74
75 spin_lock_bh(&f->lock);
76 fdt = f->next;
77 f->next = NULL;
78 spin_unlock_bh(&f->lock);
79 while(fdt) {
80 struct fdtable *next = fdt->next;
81
82 __free_fdtable(fdt);
83 fdt = next;
84 }
85}
86
87void free_fdtable_rcu(struct rcu_head *rcu)
88{
89 struct fdtable *fdt = container_of(rcu, struct fdtable, rcu);
90 struct fdtable_defer *fddef;
91
92 BUG_ON(!fdt);
93
94 if (fdt->max_fds <= NR_OPEN_DEFAULT) {
95
96
97
98
99 kmem_cache_free(files_cachep,
100 container_of(fdt, struct files_struct, fdtab));
101 return;
102 }
103 if (!is_vmalloc_addr(fdt->fd) && !is_vmalloc_addr(fdt->open_fds)) {
104 kfree(fdt->fd);
105 kfree(fdt->open_fds);
106 kfree(fdt);
107 } else {
108 fddef = &get_cpu_var(fdtable_defer_list);
109 spin_lock(&fddef->lock);
110 fdt->next = fddef->next;
111 fddef->next = fdt;
112
113 schedule_work(&fddef->wq);
114 spin_unlock(&fddef->lock);
115 put_cpu_var(fdtable_defer_list);
116 }
117}
118
119
120
121
122
123static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
124{
125 unsigned int cpy, set;
126
127 BUG_ON(nfdt->max_fds < ofdt->max_fds);
128
129 cpy = ofdt->max_fds * sizeof(struct file *);
130 set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);
131 memcpy(nfdt->fd, ofdt->fd, cpy);
132 memset((char *)(nfdt->fd) + cpy, 0, set);
133
134 cpy = ofdt->max_fds / BITS_PER_BYTE;
135 set = (nfdt->max_fds - ofdt->max_fds) / BITS_PER_BYTE;
136 memcpy(nfdt->open_fds, ofdt->open_fds, cpy);
137 memset((char *)(nfdt->open_fds) + cpy, 0, set);
138 memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy);
139 memset((char *)(nfdt->close_on_exec) + cpy, 0, set);
140}
141
142static struct fdtable * alloc_fdtable(unsigned int nr)
143{
144 struct fdtable *fdt;
145 char *data;
146
147
148
149
150
151
152
153
154 nr /= (1024 / sizeof(struct file *));
155 nr = roundup_pow_of_two(nr + 1);
156 nr *= (1024 / sizeof(struct file *));
157
158
159
160
161
162
163
164
165 if (unlikely(nr > sysctl_nr_open))
166 nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1;
167
168 fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL);
169 if (!fdt)
170 goto out;
171 fdt->max_fds = nr;
172 data = alloc_fdmem(nr * sizeof(struct file *));
173 if (!data)
174 goto out_fdt;
175 fdt->fd = (struct file **)data;
176 data = alloc_fdmem(max_t(unsigned int,
177 2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES));
178 if (!data)
179 goto out_arr;
180 fdt->open_fds = (fd_set *)data;
181 data += nr / BITS_PER_BYTE;
182 fdt->close_on_exec = (fd_set *)data;
183 fdt->next = NULL;
184
185 return fdt;
186
187out_arr:
188 free_fdmem(fdt->fd);
189out_fdt:
190 kfree(fdt);
191out:
192 return NULL;
193}
194
195
196
197
198
199
200
201
202static int expand_fdtable(struct files_struct *files, int nr)
203 __releases(files->file_lock)
204 __acquires(files->file_lock)
205{
206 struct fdtable *new_fdt, *cur_fdt;
207
208 spin_unlock(&files->file_lock);
209 new_fdt = alloc_fdtable(nr);
210 spin_lock(&files->file_lock);
211 if (!new_fdt)
212 return -ENOMEM;
213
214
215
216
217 if (unlikely(new_fdt->max_fds <= nr)) {
218 __free_fdtable(new_fdt);
219 return -EMFILE;
220 }
221
222
223
224
225 cur_fdt = files_fdtable(files);
226 if (nr >= cur_fdt->max_fds) {
227
228 copy_fdtable(new_fdt, cur_fdt);
229 rcu_assign_pointer(files->fdt, new_fdt);
230 if (cur_fdt->max_fds > NR_OPEN_DEFAULT)
231 free_fdtable(cur_fdt);
232 } else {
233
234 __free_fdtable(new_fdt);
235 }
236 return 1;
237}
238
239
240
241
242
243
244
245
246
247int expand_files(struct files_struct *files, int nr)
248{
249 struct fdtable *fdt;
250
251 fdt = files_fdtable(files);
252
253
254
255
256
257 if (nr >= rlimit(RLIMIT_NOFILE))
258 return -EMFILE;
259
260
261 if (nr < fdt->max_fds)
262 return 0;
263
264
265 if (nr >= sysctl_nr_open)
266 return -EMFILE;
267
268
269 return expand_fdtable(files, nr);
270}
271
272static int count_open_files(struct fdtable *fdt)
273{
274 int size = fdt->max_fds;
275 int i;
276
277
278 for (i = size/(8*sizeof(long)); i > 0; ) {
279 if (fdt->open_fds->fds_bits[--i])
280 break;
281 }
282 i = (i+1) * 8 * sizeof(long);
283 return i;
284}
285
286
287
288
289
290
291struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
292{
293 struct files_struct *newf;
294 struct file **old_fds, **new_fds;
295 int open_files, size, i;
296 struct fdtable *old_fdt, *new_fdt;
297
298 *errorp = -ENOMEM;
299 newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
300 if (!newf)
301 goto out;
302
303 atomic_set(&newf->count, 1);
304
305 spin_lock_init(&newf->file_lock);
306 newf->next_fd = 0;
307 new_fdt = &newf->fdtab;
308 new_fdt->max_fds = NR_OPEN_DEFAULT;
309 new_fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
310 new_fdt->open_fds = (fd_set *)&newf->open_fds_init;
311 new_fdt->fd = &newf->fd_array[0];
312 new_fdt->next = NULL;
313
314 spin_lock(&oldf->file_lock);
315 old_fdt = files_fdtable(oldf);
316 open_files = count_open_files(old_fdt);
317
318
319
320
321 while (unlikely(open_files > new_fdt->max_fds)) {
322 spin_unlock(&oldf->file_lock);
323
324 if (new_fdt != &newf->fdtab)
325 __free_fdtable(new_fdt);
326
327 new_fdt = alloc_fdtable(open_files - 1);
328 if (!new_fdt) {
329 *errorp = -ENOMEM;
330 goto out_release;
331 }
332
333
334 if (unlikely(new_fdt->max_fds < open_files)) {
335 __free_fdtable(new_fdt);
336 *errorp = -EMFILE;
337 goto out_release;
338 }
339
340
341
342
343
344
345 spin_lock(&oldf->file_lock);
346 old_fdt = files_fdtable(oldf);
347 open_files = count_open_files(old_fdt);
348 }
349
350 old_fds = old_fdt->fd;
351 new_fds = new_fdt->fd;
352
353 memcpy(new_fdt->open_fds->fds_bits,
354 old_fdt->open_fds->fds_bits, open_files/8);
355 memcpy(new_fdt->close_on_exec->fds_bits,
356 old_fdt->close_on_exec->fds_bits, open_files/8);
357
358 for (i = open_files; i != 0; i--) {
359 struct file *f = *old_fds++;
360 if (f) {
361 get_file(f);
362 } else {
363
364
365
366
367
368
369 FD_CLR(open_files - i, new_fdt->open_fds);
370 }
371 rcu_assign_pointer(*new_fds++, f);
372 }
373 spin_unlock(&oldf->file_lock);
374
375
376 size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
377
378
379 memset(new_fds, 0, size);
380
381 if (new_fdt->max_fds > open_files) {
382 int left = (new_fdt->max_fds-open_files)/8;
383 int start = open_files / (8 * sizeof(unsigned long));
384
385 memset(&new_fdt->open_fds->fds_bits[start], 0, left);
386 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
387 }
388
389 rcu_assign_pointer(newf->fdt, new_fdt);
390
391 return newf;
392
393out_release:
394 kmem_cache_free(files_cachep, newf);
395out:
396 return NULL;
397}
398
399static void __devinit fdtable_defer_list_init(int cpu)
400{
401 struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu);
402 spin_lock_init(&fddef->lock);
403 INIT_WORK(&fddef->wq, free_fdtable_work);
404 fddef->next = NULL;
405}
406
407void __init files_defer_init(void)
408{
409 int i;
410 for_each_possible_cpu(i)
411 fdtable_defer_list_init(i);
412 sysctl_nr_open_max = min((size_t)INT_MAX, ~(size_t)0/sizeof(void *)) &
413 -BITS_PER_LONG;
414}
415
416struct files_struct init_files = {
417 .count = ATOMIC_INIT(1),
418 .fdt = &init_files.fdtab,
419 .fdtab = {
420 .max_fds = NR_OPEN_DEFAULT,
421 .fd = &init_files.fd_array[0],
422 .close_on_exec = (fd_set *)&init_files.close_on_exec_init,
423 .open_fds = (fd_set *)&init_files.open_fds_init,
424 },
425 .file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock),
426};
427
428
429
430
431int alloc_fd(unsigned start, unsigned flags)
432{
433 struct files_struct *files = current->files;
434 unsigned int fd;
435 int error;
436 struct fdtable *fdt;
437
438 spin_lock(&files->file_lock);
439repeat:
440 fdt = files_fdtable(files);
441 fd = start;
442 if (fd < files->next_fd)
443 fd = files->next_fd;
444
445 if (fd < fdt->max_fds)
446 fd = find_next_zero_bit(fdt->open_fds->fds_bits,
447 fdt->max_fds, fd);
448
449 error = expand_files(files, fd);
450 if (error < 0)
451 goto out;
452
453
454
455
456
457 if (error)
458 goto repeat;
459
460 if (start <= files->next_fd)
461 files->next_fd = fd + 1;
462
463 FD_SET(fd, fdt->open_fds);
464 if (flags & O_CLOEXEC)
465 FD_SET(fd, fdt->close_on_exec);
466 else
467 FD_CLR(fd, fdt->close_on_exec);
468 error = fd;
469#if 1
470
471 if (rcu_dereference_raw(fdt->fd[fd]) != NULL) {
472 printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
473 rcu_assign_pointer(fdt->fd[fd], NULL);
474 }
475#endif
476
477out:
478 spin_unlock(&files->file_lock);
479 return error;
480}
481
482int get_unused_fd(void)
483{
484 return alloc_fd(0, 0);
485}
486EXPORT_SYMBOL(get_unused_fd);
487