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Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux
[mirror_ubuntu-zesty-kernel.git] / fs / file.c
CommitLineData
1da177e4
LT
1/*
2 * linux/fs/file.c
3 *
4 * Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
5 *
6 * Manage the dynamic fd arrays in the process files_struct.
7 */
8
fe17f22d 9#include <linux/syscalls.h>
630d9c47 10#include <linux/export.h>
1da177e4
LT
11#include <linux/fs.h>
12#include <linux/mm.h>
6d4831c2 13#include <linux/mmzone.h>
1da177e4 14#include <linux/time.h>
d43c36dc 15#include <linux/sched.h>
1da177e4
LT
16#include <linux/slab.h>
17#include <linux/vmalloc.h>
18#include <linux/file.h>
9f3acc31 19#include <linux/fdtable.h>
1da177e4 20#include <linux/bitops.h>
ab2af1f5
DS
21#include <linux/interrupt.h>
22#include <linux/spinlock.h>
23#include <linux/rcupdate.h>
24#include <linux/workqueue.h>
25
9cfe015a 26int sysctl_nr_open __read_mostly = 1024*1024;
eceea0b3 27int sysctl_nr_open_min = BITS_PER_LONG;
7f4b36f9
AV
28/* our max() is unusable in constant expressions ;-/ */
29#define __const_max(x, y) ((x) < (y) ? (x) : (y))
30int sysctl_nr_open_max = __const_max(INT_MAX, ~(size_t)0/sizeof(void *)) &
31 -BITS_PER_LONG;
9cfe015a 32
1fd36adc 33static void *alloc_fdmem(size_t size)
1da177e4 34{
6d4831c2
AM
35 /*
36 * Very large allocations can stress page reclaim, so fall back to
37 * vmalloc() if the allocation size will be considered "large" by the VM.
38 */
39 if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
96c7a2ff 40 void *data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY);
6d4831c2
AM
41 if (data != NULL)
42 return data;
43 }
a892e2d7 44 return vmalloc(size);
1da177e4
LT
45}
46
a892e2d7 47static void __free_fdtable(struct fdtable *fdt)
1da177e4 48{
f6c0a192
AV
49 kvfree(fdt->fd);
50 kvfree(fdt->open_fds);
a892e2d7 51 kfree(fdt);
ab2af1f5 52}
1da177e4 53
7cf4dc3c 54static void free_fdtable_rcu(struct rcu_head *rcu)
ab2af1f5 55{
ac3e3c5b 56 __free_fdtable(container_of(rcu, struct fdtable, rcu));
ab2af1f5
DS
57}
58
ab2af1f5
DS
59/*
60 * Expand the fdset in the files_struct. Called with the files spinlock
61 * held for write.
62 */
5466b456 63static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
ab2af1f5 64{
5466b456 65 unsigned int cpy, set;
ab2af1f5 66
5466b456 67 BUG_ON(nfdt->max_fds < ofdt->max_fds);
5466b456
VL
68
69 cpy = ofdt->max_fds * sizeof(struct file *);
70 set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);
71 memcpy(nfdt->fd, ofdt->fd, cpy);
72 memset((char *)(nfdt->fd) + cpy, 0, set);
73
74 cpy = ofdt->max_fds / BITS_PER_BYTE;
75 set = (nfdt->max_fds - ofdt->max_fds) / BITS_PER_BYTE;
76 memcpy(nfdt->open_fds, ofdt->open_fds, cpy);
77 memset((char *)(nfdt->open_fds) + cpy, 0, set);
78 memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy);
79 memset((char *)(nfdt->close_on_exec) + cpy, 0, set);
1da177e4
LT
80}
81
5466b456 82static struct fdtable * alloc_fdtable(unsigned int nr)
1da177e4 83{
5466b456 84 struct fdtable *fdt;
1fd36adc 85 void *data;
1da177e4 86
ab2af1f5 87 /*
5466b456
VL
88 * Figure out how many fds we actually want to support in this fdtable.
89 * Allocation steps are keyed to the size of the fdarray, since it
90 * grows far faster than any of the other dynamic data. We try to fit
91 * the fdarray into comfortable page-tuned chunks: starting at 1024B
92 * and growing in powers of two from there on.
ab2af1f5 93 */
5466b456
VL
94 nr /= (1024 / sizeof(struct file *));
95 nr = roundup_pow_of_two(nr + 1);
96 nr *= (1024 / sizeof(struct file *));
5c598b34
AV
97 /*
98 * Note that this can drive nr *below* what we had passed if sysctl_nr_open
99 * had been set lower between the check in expand_files() and here. Deal
100 * with that in caller, it's cheaper that way.
101 *
102 * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise
103 * bitmaps handling below becomes unpleasant, to put it mildly...
104 */
105 if (unlikely(nr > sysctl_nr_open))
106 nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1;
bbea9f69 107
5466b456
VL
108 fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL);
109 if (!fdt)
bbea9f69 110 goto out;
5466b456
VL
111 fdt->max_fds = nr;
112 data = alloc_fdmem(nr * sizeof(struct file *));
113 if (!data)
114 goto out_fdt;
1fd36adc
DH
115 fdt->fd = data;
116
117 data = alloc_fdmem(max_t(size_t,
5466b456
VL
118 2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES));
119 if (!data)
120 goto out_arr;
1fd36adc 121 fdt->open_fds = data;
5466b456 122 data += nr / BITS_PER_BYTE;
1fd36adc 123 fdt->close_on_exec = data;
5466b456 124
ab2af1f5 125 return fdt;
5466b456
VL
126
127out_arr:
f6c0a192 128 kvfree(fdt->fd);
5466b456 129out_fdt:
ab2af1f5 130 kfree(fdt);
5466b456 131out:
ab2af1f5
DS
132 return NULL;
133}
1da177e4 134
ab2af1f5 135/*
74d392aa
VL
136 * Expand the file descriptor table.
137 * This function will allocate a new fdtable and both fd array and fdset, of
138 * the given size.
139 * Return <0 error code on error; 1 on successful completion.
140 * The files->file_lock should be held on entry, and will be held on exit.
ab2af1f5
DS
141 */
142static int expand_fdtable(struct files_struct *files, int nr)
143 __releases(files->file_lock)
144 __acquires(files->file_lock)
145{
74d392aa 146 struct fdtable *new_fdt, *cur_fdt;
ab2af1f5
DS
147
148 spin_unlock(&files->file_lock);
74d392aa 149 new_fdt = alloc_fdtable(nr);
ab2af1f5 150 spin_lock(&files->file_lock);
74d392aa
VL
151 if (!new_fdt)
152 return -ENOMEM;
5c598b34
AV
153 /*
154 * extremely unlikely race - sysctl_nr_open decreased between the check in
155 * caller and alloc_fdtable(). Cheaper to catch it here...
156 */
157 if (unlikely(new_fdt->max_fds <= nr)) {
a892e2d7 158 __free_fdtable(new_fdt);
5c598b34
AV
159 return -EMFILE;
160 }
ab2af1f5 161 /*
74d392aa
VL
162 * Check again since another task may have expanded the fd table while
163 * we dropped the lock
ab2af1f5 164 */
74d392aa 165 cur_fdt = files_fdtable(files);
bbea9f69 166 if (nr >= cur_fdt->max_fds) {
74d392aa
VL
167 /* Continue as planned */
168 copy_fdtable(new_fdt, cur_fdt);
169 rcu_assign_pointer(files->fdt, new_fdt);
ac3e3c5b 170 if (cur_fdt != &files->fdtab)
1983e781 171 call_rcu(&cur_fdt->rcu, free_fdtable_rcu);
ab2af1f5 172 } else {
74d392aa 173 /* Somebody else expanded, so undo our attempt */
a892e2d7 174 __free_fdtable(new_fdt);
ab2af1f5 175 }
74d392aa 176 return 1;
1da177e4
LT
177}
178
179/*
180 * Expand files.
74d392aa
VL
181 * This function will expand the file structures, if the requested size exceeds
182 * the current capacity and there is room for expansion.
183 * Return <0 error code on error; 0 when nothing done; 1 when files were
184 * expanded and execution may have blocked.
185 * The files->file_lock should be held on entry, and will be held on exit.
1da177e4 186 */
ad47bd72 187static int expand_files(struct files_struct *files, int nr)
1da177e4 188{
badf1662 189 struct fdtable *fdt;
1da177e4 190
badf1662 191 fdt = files_fdtable(files);
4e1e018e 192
74d392aa 193 /* Do we need to expand? */
bbea9f69 194 if (nr < fdt->max_fds)
74d392aa 195 return 0;
4e1e018e 196
74d392aa 197 /* Can we expand? */
9cfe015a 198 if (nr >= sysctl_nr_open)
74d392aa
VL
199 return -EMFILE;
200
201 /* All good, so we try */
202 return expand_fdtable(files, nr);
1da177e4 203}
ab2af1f5 204
b8318b01
AV
205static inline void __set_close_on_exec(int fd, struct fdtable *fdt)
206{
207 __set_bit(fd, fdt->close_on_exec);
208}
209
210static inline void __clear_close_on_exec(int fd, struct fdtable *fdt)
211{
212 __clear_bit(fd, fdt->close_on_exec);
213}
214
215static inline void __set_open_fd(int fd, struct fdtable *fdt)
216{
217 __set_bit(fd, fdt->open_fds);
218}
219
220static inline void __clear_open_fd(int fd, struct fdtable *fdt)
221{
222 __clear_bit(fd, fdt->open_fds);
223}
224
02afc626
AV
225static int count_open_files(struct fdtable *fdt)
226{
227 int size = fdt->max_fds;
228 int i;
229
230 /* Find the last open fd */
1fd36adc
DH
231 for (i = size / BITS_PER_LONG; i > 0; ) {
232 if (fdt->open_fds[--i])
02afc626
AV
233 break;
234 }
1fd36adc 235 i = (i + 1) * BITS_PER_LONG;
02afc626
AV
236 return i;
237}
238
02afc626
AV
239/*
240 * Allocate a new files structure and copy contents from the
241 * passed in files structure.
242 * errorp will be valid only when the returned files_struct is NULL.
243 */
244struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
245{
246 struct files_struct *newf;
247 struct file **old_fds, **new_fds;
248 int open_files, size, i;
249 struct fdtable *old_fdt, *new_fdt;
250
251 *errorp = -ENOMEM;
afbec7ff 252 newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
02afc626
AV
253 if (!newf)
254 goto out;
255
afbec7ff
AV
256 atomic_set(&newf->count, 1);
257
258 spin_lock_init(&newf->file_lock);
259 newf->next_fd = 0;
260 new_fdt = &newf->fdtab;
261 new_fdt->max_fds = NR_OPEN_DEFAULT;
1fd36adc
DH
262 new_fdt->close_on_exec = newf->close_on_exec_init;
263 new_fdt->open_fds = newf->open_fds_init;
afbec7ff 264 new_fdt->fd = &newf->fd_array[0];
afbec7ff 265
02afc626
AV
266 spin_lock(&oldf->file_lock);
267 old_fdt = files_fdtable(oldf);
02afc626
AV
268 open_files = count_open_files(old_fdt);
269
270 /*
271 * Check whether we need to allocate a larger fd array and fd set.
02afc626 272 */
adbecb12 273 while (unlikely(open_files > new_fdt->max_fds)) {
02afc626 274 spin_unlock(&oldf->file_lock);
9dec3c4d 275
a892e2d7
CG
276 if (new_fdt != &newf->fdtab)
277 __free_fdtable(new_fdt);
adbecb12 278
9dec3c4d
AV
279 new_fdt = alloc_fdtable(open_files - 1);
280 if (!new_fdt) {
281 *errorp = -ENOMEM;
282 goto out_release;
283 }
284
285 /* beyond sysctl_nr_open; nothing to do */
286 if (unlikely(new_fdt->max_fds < open_files)) {
a892e2d7 287 __free_fdtable(new_fdt);
9dec3c4d 288 *errorp = -EMFILE;
02afc626 289 goto out_release;
9dec3c4d 290 }
9dec3c4d 291
02afc626
AV
292 /*
293 * Reacquire the oldf lock and a pointer to its fd table
294 * who knows it may have a new bigger fd table. We need
295 * the latest pointer.
296 */
297 spin_lock(&oldf->file_lock);
298 old_fdt = files_fdtable(oldf);
adbecb12 299 open_files = count_open_files(old_fdt);
02afc626
AV
300 }
301
302 old_fds = old_fdt->fd;
303 new_fds = new_fdt->fd;
304
1fd36adc
DH
305 memcpy(new_fdt->open_fds, old_fdt->open_fds, open_files / 8);
306 memcpy(new_fdt->close_on_exec, old_fdt->close_on_exec, open_files / 8);
02afc626
AV
307
308 for (i = open_files; i != 0; i--) {
309 struct file *f = *old_fds++;
310 if (f) {
311 get_file(f);
312 } else {
313 /*
314 * The fd may be claimed in the fd bitmap but not yet
315 * instantiated in the files array if a sibling thread
316 * is partway through open(). So make sure that this
317 * fd is available to the new process.
318 */
1dce27c5 319 __clear_open_fd(open_files - i, new_fdt);
02afc626
AV
320 }
321 rcu_assign_pointer(*new_fds++, f);
322 }
323 spin_unlock(&oldf->file_lock);
324
325 /* compute the remainder to be cleared */
326 size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
327
328 /* This is long word aligned thus could use a optimized version */
329 memset(new_fds, 0, size);
330
331 if (new_fdt->max_fds > open_files) {
1fd36adc
DH
332 int left = (new_fdt->max_fds - open_files) / 8;
333 int start = open_files / BITS_PER_LONG;
02afc626 334
1fd36adc
DH
335 memset(&new_fdt->open_fds[start], 0, left);
336 memset(&new_fdt->close_on_exec[start], 0, left);
02afc626
AV
337 }
338
afbec7ff
AV
339 rcu_assign_pointer(newf->fdt, new_fdt);
340
02afc626
AV
341 return newf;
342
343out_release:
344 kmem_cache_free(files_cachep, newf);
345out:
346 return NULL;
347}
348
ce08b62d 349static struct fdtable *close_files(struct files_struct * files)
7cf4dc3c 350{
7cf4dc3c
AV
351 /*
352 * It is safe to dereference the fd table without RCU or
353 * ->file_lock because this is the last reference to the
ce08b62d 354 * files structure.
7cf4dc3c 355 */
ce08b62d
ON
356 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
357 int i, j = 0;
358
7cf4dc3c
AV
359 for (;;) {
360 unsigned long set;
361 i = j * BITS_PER_LONG;
362 if (i >= fdt->max_fds)
363 break;
364 set = fdt->open_fds[j++];
365 while (set) {
366 if (set & 1) {
367 struct file * file = xchg(&fdt->fd[i], NULL);
368 if (file) {
369 filp_close(file, files);
bde6c3aa 370 cond_resched_rcu_qs();
7cf4dc3c
AV
371 }
372 }
373 i++;
374 set >>= 1;
375 }
376 }
ce08b62d
ON
377
378 return fdt;
7cf4dc3c
AV
379}
380
381struct files_struct *get_files_struct(struct task_struct *task)
382{
383 struct files_struct *files;
384
385 task_lock(task);
386 files = task->files;
387 if (files)
388 atomic_inc(&files->count);
389 task_unlock(task);
390
391 return files;
392}
393
394void put_files_struct(struct files_struct *files)
395{
7cf4dc3c 396 if (atomic_dec_and_test(&files->count)) {
ce08b62d
ON
397 struct fdtable *fdt = close_files(files);
398
b9e02af0
AV
399 /* free the arrays if they are not embedded */
400 if (fdt != &files->fdtab)
401 __free_fdtable(fdt);
402 kmem_cache_free(files_cachep, files);
7cf4dc3c
AV
403 }
404}
405
406void reset_files_struct(struct files_struct *files)
407{
408 struct task_struct *tsk = current;
409 struct files_struct *old;
410
411 old = tsk->files;
412 task_lock(tsk);
413 tsk->files = files;
414 task_unlock(tsk);
415 put_files_struct(old);
416}
417
418void exit_files(struct task_struct *tsk)
419{
420 struct files_struct * files = tsk->files;
421
422 if (files) {
423 task_lock(tsk);
424 tsk->files = NULL;
425 task_unlock(tsk);
426 put_files_struct(files);
427 }
428}
429
f52111b1
AV
430struct files_struct init_files = {
431 .count = ATOMIC_INIT(1),
432 .fdt = &init_files.fdtab,
433 .fdtab = {
434 .max_fds = NR_OPEN_DEFAULT,
435 .fd = &init_files.fd_array[0],
1fd36adc
DH
436 .close_on_exec = init_files.close_on_exec_init,
437 .open_fds = init_files.open_fds_init,
f52111b1 438 },
eece09ec 439 .file_lock = __SPIN_LOCK_UNLOCKED(init_files.file_lock),
f52111b1 440};
1027abe8
AV
441
442/*
443 * allocate a file descriptor, mark it busy.
444 */
dcfadfa4
AV
445int __alloc_fd(struct files_struct *files,
446 unsigned start, unsigned end, unsigned flags)
1027abe8 447{
1027abe8
AV
448 unsigned int fd;
449 int error;
450 struct fdtable *fdt;
451
452 spin_lock(&files->file_lock);
453repeat:
454 fdt = files_fdtable(files);
455 fd = start;
456 if (fd < files->next_fd)
457 fd = files->next_fd;
458
459 if (fd < fdt->max_fds)
1fd36adc 460 fd = find_next_zero_bit(fdt->open_fds, fdt->max_fds, fd);
1027abe8 461
f33ff992
AV
462 /*
463 * N.B. For clone tasks sharing a files structure, this test
464 * will limit the total number of files that can be opened.
465 */
466 error = -EMFILE;
467 if (fd >= end)
468 goto out;
469
1027abe8
AV
470 error = expand_files(files, fd);
471 if (error < 0)
472 goto out;
473
474 /*
475 * If we needed to expand the fs array we
476 * might have blocked - try again.
477 */
478 if (error)
479 goto repeat;
480
481 if (start <= files->next_fd)
482 files->next_fd = fd + 1;
483
1dce27c5 484 __set_open_fd(fd, fdt);
1027abe8 485 if (flags & O_CLOEXEC)
1dce27c5 486 __set_close_on_exec(fd, fdt);
1027abe8 487 else
1dce27c5 488 __clear_close_on_exec(fd, fdt);
1027abe8
AV
489 error = fd;
490#if 1
491 /* Sanity check */
add1f099 492 if (rcu_access_pointer(fdt->fd[fd]) != NULL) {
1027abe8
AV
493 printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
494 rcu_assign_pointer(fdt->fd[fd], NULL);
495 }
496#endif
497
498out:
499 spin_unlock(&files->file_lock);
500 return error;
501}
502
ad47bd72 503static int alloc_fd(unsigned start, unsigned flags)
dcfadfa4
AV
504{
505 return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags);
506}
507
1a7bd226 508int get_unused_fd_flags(unsigned flags)
1027abe8 509{
dcfadfa4 510 return __alloc_fd(current->files, 0, rlimit(RLIMIT_NOFILE), flags);
1027abe8 511}
1a7bd226 512EXPORT_SYMBOL(get_unused_fd_flags);
56007cae
AV
513
514static void __put_unused_fd(struct files_struct *files, unsigned int fd)
515{
516 struct fdtable *fdt = files_fdtable(files);
517 __clear_open_fd(fd, fdt);
518 if (fd < files->next_fd)
519 files->next_fd = fd;
520}
521
522void put_unused_fd(unsigned int fd)
523{
524 struct files_struct *files = current->files;
525 spin_lock(&files->file_lock);
526 __put_unused_fd(files, fd);
527 spin_unlock(&files->file_lock);
528}
529
530EXPORT_SYMBOL(put_unused_fd);
531
532/*
533 * Install a file pointer in the fd array.
534 *
535 * The VFS is full of places where we drop the files lock between
536 * setting the open_fds bitmap and installing the file in the file
537 * array. At any such point, we are vulnerable to a dup2() race
538 * installing a file in the array before us. We need to detect this and
539 * fput() the struct file we are about to overwrite in this case.
540 *
541 * It should never happen - if we allow dup2() do it, _really_ bad things
542 * will follow.
f869e8a7
AV
543 *
544 * NOTE: __fd_install() variant is really, really low-level; don't
545 * use it unless you are forced to by truly lousy API shoved down
546 * your throat. 'files' *MUST* be either current->files or obtained
547 * by get_files_struct(current) done by whoever had given it to you,
548 * or really bad things will happen. Normally you want to use
549 * fd_install() instead.
56007cae
AV
550 */
551
f869e8a7
AV
552void __fd_install(struct files_struct *files, unsigned int fd,
553 struct file *file)
56007cae 554{
56007cae
AV
555 struct fdtable *fdt;
556 spin_lock(&files->file_lock);
557 fdt = files_fdtable(files);
558 BUG_ON(fdt->fd[fd] != NULL);
559 rcu_assign_pointer(fdt->fd[fd], file);
560 spin_unlock(&files->file_lock);
561}
562
f869e8a7
AV
563void fd_install(unsigned int fd, struct file *file)
564{
565 __fd_install(current->files, fd, file);
566}
567
56007cae 568EXPORT_SYMBOL(fd_install);
0ee8cdfe 569
483ce1d4
AV
570/*
571 * The same warnings as for __alloc_fd()/__fd_install() apply here...
572 */
573int __close_fd(struct files_struct *files, unsigned fd)
574{
575 struct file *file;
576 struct fdtable *fdt;
577
578 spin_lock(&files->file_lock);
579 fdt = files_fdtable(files);
580 if (fd >= fdt->max_fds)
581 goto out_unlock;
582 file = fdt->fd[fd];
583 if (!file)
584 goto out_unlock;
585 rcu_assign_pointer(fdt->fd[fd], NULL);
586 __clear_close_on_exec(fd, fdt);
587 __put_unused_fd(files, fd);
588 spin_unlock(&files->file_lock);
589 return filp_close(file, files);
590
591out_unlock:
592 spin_unlock(&files->file_lock);
593 return -EBADF;
594}
595
6a6d27de
AV
596void do_close_on_exec(struct files_struct *files)
597{
598 unsigned i;
599 struct fdtable *fdt;
600
601 /* exec unshares first */
6a6d27de
AV
602 spin_lock(&files->file_lock);
603 for (i = 0; ; i++) {
604 unsigned long set;
605 unsigned fd = i * BITS_PER_LONG;
606 fdt = files_fdtable(files);
607 if (fd >= fdt->max_fds)
608 break;
609 set = fdt->close_on_exec[i];
610 if (!set)
611 continue;
612 fdt->close_on_exec[i] = 0;
613 for ( ; set ; fd++, set >>= 1) {
614 struct file *file;
615 if (!(set & 1))
616 continue;
617 file = fdt->fd[fd];
618 if (!file)
619 continue;
620 rcu_assign_pointer(fdt->fd[fd], NULL);
621 __put_unused_fd(files, fd);
622 spin_unlock(&files->file_lock);
623 filp_close(file, files);
624 cond_resched();
625 spin_lock(&files->file_lock);
626 }
627
628 }
629 spin_unlock(&files->file_lock);
630}
631
1deb46e2 632static struct file *__fget(unsigned int fd, fmode_t mask)
0ee8cdfe 633{
0ee8cdfe 634 struct files_struct *files = current->files;
1deb46e2 635 struct file *file;
0ee8cdfe
AV
636
637 rcu_read_lock();
638 file = fcheck_files(files, fd);
639 if (file) {
640 /* File object ref couldn't be taken */
1deb46e2 641 if ((file->f_mode & mask) ||
0ee8cdfe
AV
642 !atomic_long_inc_not_zero(&file->f_count))
643 file = NULL;
644 }
645 rcu_read_unlock();
646
647 return file;
648}
649
1deb46e2
ON
650struct file *fget(unsigned int fd)
651{
652 return __fget(fd, FMODE_PATH);
653}
0ee8cdfe
AV
654EXPORT_SYMBOL(fget);
655
656struct file *fget_raw(unsigned int fd)
657{
1deb46e2 658 return __fget(fd, 0);
0ee8cdfe 659}
0ee8cdfe
AV
660EXPORT_SYMBOL(fget_raw);
661
662/*
663 * Lightweight file lookup - no refcnt increment if fd table isn't shared.
664 *
665 * You can use this instead of fget if you satisfy all of the following
666 * conditions:
667 * 1) You must call fput_light before exiting the syscall and returning control
668 * to userspace (i.e. you cannot remember the returned struct file * after
669 * returning to userspace).
670 * 2) You must not call filp_close on the returned struct file * in between
671 * calls to fget_light and fput_light.
672 * 3) You must not clone the current task in between the calls to fget_light
673 * and fput_light.
674 *
675 * The fput_needed flag returned by fget_light should be passed to the
676 * corresponding fput_light.
677 */
bd2a31d5 678static unsigned long __fget_light(unsigned int fd, fmode_t mask)
0ee8cdfe 679{
0ee8cdfe 680 struct files_struct *files = current->files;
ad461834 681 struct file *file;
0ee8cdfe 682
0ee8cdfe 683 if (atomic_read(&files->count) == 1) {
a8d4b834 684 file = __fcheck_files(files, fd);
bd2a31d5
AV
685 if (!file || unlikely(file->f_mode & mask))
686 return 0;
687 return (unsigned long)file;
0ee8cdfe 688 } else {
e6ff9a9f 689 file = __fget(fd, mask);
bd2a31d5
AV
690 if (!file)
691 return 0;
692 return FDPUT_FPUT | (unsigned long)file;
0ee8cdfe 693 }
0ee8cdfe 694}
bd2a31d5 695unsigned long __fdget(unsigned int fd)
ad461834 696{
bd2a31d5 697 return __fget_light(fd, FMODE_PATH);
ad461834 698}
bd2a31d5 699EXPORT_SYMBOL(__fdget);
0ee8cdfe 700
bd2a31d5 701unsigned long __fdget_raw(unsigned int fd)
0ee8cdfe 702{
bd2a31d5 703 return __fget_light(fd, 0);
0ee8cdfe 704}
fe17f22d 705
bd2a31d5
AV
706unsigned long __fdget_pos(unsigned int fd)
707{
99aea681
EB
708 unsigned long v = __fdget(fd);
709 struct file *file = (struct file *)(v & ~3);
bd2a31d5 710
99aea681 711 if (file && (file->f_mode & FMODE_ATOMIC_POS)) {
bd2a31d5
AV
712 if (file_count(file) > 1) {
713 v |= FDPUT_POS_UNLOCK;
714 mutex_lock(&file->f_pos_lock);
715 }
716 }
99aea681 717 return v;
bd2a31d5
AV
718}
719
720/*
721 * We only lock f_pos if we have threads or if the file might be
722 * shared with another process. In both cases we'll have an elevated
723 * file count (done either by fdget() or by fork()).
724 */
725
fe17f22d
AV
726void set_close_on_exec(unsigned int fd, int flag)
727{
728 struct files_struct *files = current->files;
729 struct fdtable *fdt;
730 spin_lock(&files->file_lock);
731 fdt = files_fdtable(files);
732 if (flag)
733 __set_close_on_exec(fd, fdt);
734 else
735 __clear_close_on_exec(fd, fdt);
736 spin_unlock(&files->file_lock);
737}
738
739bool get_close_on_exec(unsigned int fd)
740{
741 struct files_struct *files = current->files;
742 struct fdtable *fdt;
743 bool res;
744 rcu_read_lock();
745 fdt = files_fdtable(files);
746 res = close_on_exec(fd, fdt);
747 rcu_read_unlock();
748 return res;
749}
750
8280d161
AV
751static int do_dup2(struct files_struct *files,
752 struct file *file, unsigned fd, unsigned flags)
e983094d 753__releases(&files->file_lock)
fe17f22d 754{
8280d161 755 struct file *tofree;
fe17f22d
AV
756 struct fdtable *fdt;
757
fe17f22d
AV
758 /*
759 * We need to detect attempts to do dup2() over allocated but still
760 * not finished descriptor. NB: OpenBSD avoids that at the price of
761 * extra work in their equivalent of fget() - they insert struct
762 * file immediately after grabbing descriptor, mark it larval if
763 * more work (e.g. actual opening) is needed and make sure that
764 * fget() treats larval files as absent. Potentially interesting,
765 * but while extra work in fget() is trivial, locking implications
766 * and amount of surgery on open()-related paths in VFS are not.
767 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
768 * deadlocks in rather amusing ways, AFAICS. All of that is out of
769 * scope of POSIX or SUS, since neither considers shared descriptor
770 * tables and this condition does not arise without those.
771 */
fe17f22d 772 fdt = files_fdtable(files);
8280d161
AV
773 tofree = fdt->fd[fd];
774 if (!tofree && fd_is_open(fd, fdt))
775 goto Ebusy;
fe17f22d 776 get_file(file);
8280d161
AV
777 rcu_assign_pointer(fdt->fd[fd], file);
778 __set_open_fd(fd, fdt);
fe17f22d 779 if (flags & O_CLOEXEC)
8280d161 780 __set_close_on_exec(fd, fdt);
fe17f22d 781 else
8280d161 782 __clear_close_on_exec(fd, fdt);
fe17f22d
AV
783 spin_unlock(&files->file_lock);
784
785 if (tofree)
786 filp_close(tofree, files);
787
8280d161
AV
788 return fd;
789
790Ebusy:
791 spin_unlock(&files->file_lock);
792 return -EBUSY;
793}
794
795int replace_fd(unsigned fd, struct file *file, unsigned flags)
796{
797 int err;
798 struct files_struct *files = current->files;
799
800 if (!file)
801 return __close_fd(files, fd);
802
803 if (fd >= rlimit(RLIMIT_NOFILE))
08f05c49 804 return -EBADF;
8280d161
AV
805
806 spin_lock(&files->file_lock);
807 err = expand_files(files, fd);
808 if (unlikely(err < 0))
809 goto out_unlock;
810 return do_dup2(files, file, fd, flags);
811
812out_unlock:
813 spin_unlock(&files->file_lock);
814 return err;
815}
816
817SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
818{
819 int err = -EBADF;
820 struct file *file;
821 struct files_struct *files = current->files;
822
823 if ((flags & ~O_CLOEXEC) != 0)
824 return -EINVAL;
825
aed97647
RJ
826 if (unlikely(oldfd == newfd))
827 return -EINVAL;
828
8280d161 829 if (newfd >= rlimit(RLIMIT_NOFILE))
08f05c49 830 return -EBADF;
8280d161
AV
831
832 spin_lock(&files->file_lock);
833 err = expand_files(files, newfd);
834 file = fcheck(oldfd);
835 if (unlikely(!file))
836 goto Ebadf;
837 if (unlikely(err < 0)) {
838 if (err == -EMFILE)
839 goto Ebadf;
840 goto out_unlock;
841 }
842 return do_dup2(files, file, newfd, flags);
fe17f22d
AV
843
844Ebadf:
845 err = -EBADF;
846out_unlock:
847 spin_unlock(&files->file_lock);
848 return err;
849}
850
851SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
852{
853 if (unlikely(newfd == oldfd)) { /* corner case */
854 struct files_struct *files = current->files;
855 int retval = oldfd;
856
857 rcu_read_lock();
858 if (!fcheck_files(files, oldfd))
859 retval = -EBADF;
860 rcu_read_unlock();
861 return retval;
862 }
863 return sys_dup3(oldfd, newfd, 0);
864}
865
866SYSCALL_DEFINE1(dup, unsigned int, fildes)
867{
868 int ret = -EBADF;
869 struct file *file = fget_raw(fildes);
870
871 if (file) {
8d10a035 872 ret = get_unused_fd_flags(0);
fe17f22d
AV
873 if (ret >= 0)
874 fd_install(ret, file);
875 else
876 fput(file);
877 }
878 return ret;
879}
880
881int f_dupfd(unsigned int from, struct file *file, unsigned flags)
882{
883 int err;
884 if (from >= rlimit(RLIMIT_NOFILE))
885 return -EINVAL;
886 err = alloc_fd(from, flags);
887 if (err >= 0) {
888 get_file(file);
889 fd_install(err, file);
890 }
891 return err;
892}
c3c073f8
AV
893
894int iterate_fd(struct files_struct *files, unsigned n,
895 int (*f)(const void *, struct file *, unsigned),
896 const void *p)
897{
898 struct fdtable *fdt;
c3c073f8
AV
899 int res = 0;
900 if (!files)
901 return 0;
902 spin_lock(&files->file_lock);
a77cfcb4
AV
903 for (fdt = files_fdtable(files); n < fdt->max_fds; n++) {
904 struct file *file;
905 file = rcu_dereference_check_fdtable(files, fdt->fd[n]);
906 if (!file)
907 continue;
908 res = f(p, file, n);
909 if (res)
910 break;
c3c073f8
AV
911 }
912 spin_unlock(&files->file_lock);
913 return res;
914}
915EXPORT_SYMBOL(iterate_fd);