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TOMOYO Linux Cross Reference
Linux/fs/fcntl.c

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  1 /*
  2  *  linux/fs/fcntl.c
  3  *
  4  *  Copyright (C) 1991, 1992  Linus Torvalds
  5  */
  6 
  7 #include <linux/syscalls.h>
  8 #include <linux/init.h>
  9 #include <linux/mm.h>
 10 #include <linux/fs.h>
 11 #include <linux/file.h>
 12 #include <linux/fdtable.h>
 13 #include <linux/capability.h>
 14 #include <linux/dnotify.h>
 15 #include <linux/slab.h>
 16 #include <linux/module.h>
 17 #include <linux/pipe_fs_i.h>
 18 #include <linux/security.h>
 19 #include <linux/ptrace.h>
 20 #include <linux/signal.h>
 21 #include <linux/rcupdate.h>
 22 #include <linux/pid_namespace.h>
 23 #include <linux/user_namespace.h>
 24 
 25 #include <asm/poll.h>
 26 #include <asm/siginfo.h>
 27 #include <asm/uaccess.h>
 28 
 29 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
 30 
 31 static int setfl(int fd, struct file * filp, unsigned long arg)
 32 {
 33         struct inode * inode = file_inode(filp);
 34         int error = 0;
 35 
 36         /*
 37          * O_APPEND cannot be cleared if the file is marked as append-only
 38          * and the file is open for write.
 39          */
 40         if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
 41                 return -EPERM;
 42 
 43         /* O_NOATIME can only be set by the owner or superuser */
 44         if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
 45                 if (!inode_owner_or_capable(inode))
 46                         return -EPERM;
 47 
 48         /* required for strict SunOS emulation */
 49         if (O_NONBLOCK != O_NDELAY)
 50                if (arg & O_NDELAY)
 51                    arg |= O_NONBLOCK;
 52 
 53         if (arg & O_DIRECT) {
 54                 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
 55                         !filp->f_mapping->a_ops->direct_IO)
 56                                 return -EINVAL;
 57         }
 58 
 59         if (filp->f_op->check_flags)
 60                 error = filp->f_op->check_flags(arg);
 61         if (error)
 62                 return error;
 63 
 64         /*
 65          * ->fasync() is responsible for setting the FASYNC bit.
 66          */
 67         if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
 68                 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
 69                 if (error < 0)
 70                         goto out;
 71                 if (error > 0)
 72                         error = 0;
 73         }
 74         spin_lock(&filp->f_lock);
 75         filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
 76         spin_unlock(&filp->f_lock);
 77 
 78  out:
 79         return error;
 80 }
 81 
 82 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
 83                      int force)
 84 {
 85         write_lock_irq(&filp->f_owner.lock);
 86         if (force || !filp->f_owner.pid) {
 87                 put_pid(filp->f_owner.pid);
 88                 filp->f_owner.pid = get_pid(pid);
 89                 filp->f_owner.pid_type = type;
 90 
 91                 if (pid) {
 92                         const struct cred *cred = current_cred();
 93                         filp->f_owner.uid = cred->uid;
 94                         filp->f_owner.euid = cred->euid;
 95                 }
 96         }
 97         write_unlock_irq(&filp->f_owner.lock);
 98 }
 99 
100 int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
101                 int force)
102 {
103         int err;
104 
105         err = security_file_set_fowner(filp);
106         if (err)
107                 return err;
108 
109         f_modown(filp, pid, type, force);
110         return 0;
111 }
112 EXPORT_SYMBOL(__f_setown);
113 
114 int f_setown(struct file *filp, unsigned long arg, int force)
115 {
116         enum pid_type type;
117         struct pid *pid;
118         int who = arg;
119         int result;
120         type = PIDTYPE_PID;
121         if (who < 0) {
122                 type = PIDTYPE_PGID;
123                 who = -who;
124         }
125         rcu_read_lock();
126         pid = find_vpid(who);
127         result = __f_setown(filp, pid, type, force);
128         rcu_read_unlock();
129         return result;
130 }
131 EXPORT_SYMBOL(f_setown);
132 
133 void f_delown(struct file *filp)
134 {
135         f_modown(filp, NULL, PIDTYPE_PID, 1);
136 }
137 
138 pid_t f_getown(struct file *filp)
139 {
140         pid_t pid;
141         read_lock(&filp->f_owner.lock);
142         pid = pid_vnr(filp->f_owner.pid);
143         if (filp->f_owner.pid_type == PIDTYPE_PGID)
144                 pid = -pid;
145         read_unlock(&filp->f_owner.lock);
146         return pid;
147 }
148 
149 static int f_setown_ex(struct file *filp, unsigned long arg)
150 {
151         struct f_owner_ex __user *owner_p = (void __user *)arg;
152         struct f_owner_ex owner;
153         struct pid *pid;
154         int type;
155         int ret;
156 
157         ret = copy_from_user(&owner, owner_p, sizeof(owner));
158         if (ret)
159                 return -EFAULT;
160 
161         switch (owner.type) {
162         case F_OWNER_TID:
163                 type = PIDTYPE_MAX;
164                 break;
165 
166         case F_OWNER_PID:
167                 type = PIDTYPE_PID;
168                 break;
169 
170         case F_OWNER_PGRP:
171                 type = PIDTYPE_PGID;
172                 break;
173 
174         default:
175                 return -EINVAL;
176         }
177 
178         rcu_read_lock();
179         pid = find_vpid(owner.pid);
180         if (owner.pid && !pid)
181                 ret = -ESRCH;
182         else
183                 ret = __f_setown(filp, pid, type, 1);
184         rcu_read_unlock();
185 
186         return ret;
187 }
188 
189 static int f_getown_ex(struct file *filp, unsigned long arg)
190 {
191         struct f_owner_ex __user *owner_p = (void __user *)arg;
192         struct f_owner_ex owner;
193         int ret = 0;
194 
195         read_lock(&filp->f_owner.lock);
196         owner.pid = pid_vnr(filp->f_owner.pid);
197         switch (filp->f_owner.pid_type) {
198         case PIDTYPE_MAX:
199                 owner.type = F_OWNER_TID;
200                 break;
201 
202         case PIDTYPE_PID:
203                 owner.type = F_OWNER_PID;
204                 break;
205 
206         case PIDTYPE_PGID:
207                 owner.type = F_OWNER_PGRP;
208                 break;
209 
210         default:
211                 WARN_ON(1);
212                 ret = -EINVAL;
213                 break;
214         }
215         read_unlock(&filp->f_owner.lock);
216 
217         if (!ret) {
218                 ret = copy_to_user(owner_p, &owner, sizeof(owner));
219                 if (ret)
220                         ret = -EFAULT;
221         }
222         return ret;
223 }
224 
225 #ifdef CONFIG_CHECKPOINT_RESTORE
226 static int f_getowner_uids(struct file *filp, unsigned long arg)
227 {
228         struct user_namespace *user_ns = current_user_ns();
229         uid_t __user *dst = (void __user *)arg;
230         uid_t src[2];
231         int err;
232 
233         read_lock(&filp->f_owner.lock);
234         src[0] = from_kuid(user_ns, filp->f_owner.uid);
235         src[1] = from_kuid(user_ns, filp->f_owner.euid);
236         read_unlock(&filp->f_owner.lock);
237 
238         err  = put_user(src[0], &dst[0]);
239         err |= put_user(src[1], &dst[1]);
240 
241         return err;
242 }
243 #else
244 static int f_getowner_uids(struct file *filp, unsigned long arg)
245 {
246         return -EINVAL;
247 }
248 #endif
249 
250 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
251                 struct file *filp)
252 {
253         long err = -EINVAL;
254 
255         switch (cmd) {
256         case F_DUPFD:
257                 err = f_dupfd(arg, filp, 0);
258                 break;
259         case F_DUPFD_CLOEXEC:
260                 err = f_dupfd(arg, filp, O_CLOEXEC);
261                 break;
262         case F_GETFD:
263                 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
264                 break;
265         case F_SETFD:
266                 err = 0;
267                 set_close_on_exec(fd, arg & FD_CLOEXEC);
268                 break;
269         case F_GETFL:
270                 err = filp->f_flags;
271                 break;
272         case F_SETFL:
273                 err = setfl(fd, filp, arg);
274                 break;
275         case F_GETLK:
276                 err = fcntl_getlk(filp, (struct flock __user *) arg);
277                 break;
278         case F_SETLK:
279         case F_SETLKW:
280                 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
281                 break;
282         case F_GETOWN:
283                 /*
284                  * XXX If f_owner is a process group, the
285                  * negative return value will get converted
286                  * into an error.  Oops.  If we keep the
287                  * current syscall conventions, the only way
288                  * to fix this will be in libc.
289                  */
290                 err = f_getown(filp);
291                 force_successful_syscall_return();
292                 break;
293         case F_SETOWN:
294                 err = f_setown(filp, arg, 1);
295                 break;
296         case F_GETOWN_EX:
297                 err = f_getown_ex(filp, arg);
298                 break;
299         case F_SETOWN_EX:
300                 err = f_setown_ex(filp, arg);
301                 break;
302         case F_GETOWNER_UIDS:
303                 err = f_getowner_uids(filp, arg);
304                 break;
305         case F_GETSIG:
306                 err = filp->f_owner.signum;
307                 break;
308         case F_SETSIG:
309                 /* arg == 0 restores default behaviour. */
310                 if (!valid_signal(arg)) {
311                         break;
312                 }
313                 err = 0;
314                 filp->f_owner.signum = arg;
315                 break;
316         case F_GETLEASE:
317                 err = fcntl_getlease(filp);
318                 break;
319         case F_SETLEASE:
320                 err = fcntl_setlease(fd, filp, arg);
321                 break;
322         case F_NOTIFY:
323                 err = fcntl_dirnotify(fd, filp, arg);
324                 break;
325         case F_SETPIPE_SZ:
326         case F_GETPIPE_SZ:
327                 err = pipe_fcntl(filp, cmd, arg);
328                 break;
329         default:
330                 break;
331         }
332         return err;
333 }
334 
335 static int check_fcntl_cmd(unsigned cmd)
336 {
337         switch (cmd) {
338         case F_DUPFD:
339         case F_DUPFD_CLOEXEC:
340         case F_GETFD:
341         case F_SETFD:
342         case F_GETFL:
343                 return 1;
344         }
345         return 0;
346 }
347 
348 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
349 {       
350         struct fd f = fdget_raw(fd);
351         long err = -EBADF;
352 
353         if (!f.file)
354                 goto out;
355 
356         if (unlikely(f.file->f_mode & FMODE_PATH)) {
357                 if (!check_fcntl_cmd(cmd))
358                         goto out1;
359         }
360 
361         err = security_file_fcntl(f.file, cmd, arg);
362         if (!err)
363                 err = do_fcntl(fd, cmd, arg, f.file);
364 
365 out1:
366         fdput(f);
367 out:
368         return err;
369 }
370 
371 #if BITS_PER_LONG == 32
372 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
373                 unsigned long, arg)
374 {       
375         struct fd f = fdget_raw(fd);
376         long err = -EBADF;
377 
378         if (!f.file)
379                 goto out;
380 
381         if (unlikely(f.file->f_mode & FMODE_PATH)) {
382                 if (!check_fcntl_cmd(cmd))
383                         goto out1;
384         }
385 
386         err = security_file_fcntl(f.file, cmd, arg);
387         if (err)
388                 goto out1;
389         
390         switch (cmd) {
391                 case F_GETLK64:
392                         err = fcntl_getlk64(f.file, (struct flock64 __user *) arg);
393                         break;
394                 case F_SETLK64:
395                 case F_SETLKW64:
396                         err = fcntl_setlk64(fd, f.file, cmd,
397                                         (struct flock64 __user *) arg);
398                         break;
399                 default:
400                         err = do_fcntl(fd, cmd, arg, f.file);
401                         break;
402         }
403 out1:
404         fdput(f);
405 out:
406         return err;
407 }
408 #endif
409 
410 /* Table to convert sigio signal codes into poll band bitmaps */
411 
412 static const long band_table[NSIGPOLL] = {
413         POLLIN | POLLRDNORM,                    /* POLL_IN */
414         POLLOUT | POLLWRNORM | POLLWRBAND,      /* POLL_OUT */
415         POLLIN | POLLRDNORM | POLLMSG,          /* POLL_MSG */
416         POLLERR,                                /* POLL_ERR */
417         POLLPRI | POLLRDBAND,                   /* POLL_PRI */
418         POLLHUP | POLLERR                       /* POLL_HUP */
419 };
420 
421 static inline int sigio_perm(struct task_struct *p,
422                              struct fown_struct *fown, int sig)
423 {
424         const struct cred *cred;
425         int ret;
426 
427         rcu_read_lock();
428         cred = __task_cred(p);
429         ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
430                 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
431                 uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
432                !security_file_send_sigiotask(p, fown, sig));
433         rcu_read_unlock();
434         return ret;
435 }
436 
437 static void send_sigio_to_task(struct task_struct *p,
438                                struct fown_struct *fown,
439                                int fd, int reason, int group)
440 {
441         /*
442          * F_SETSIG can change ->signum lockless in parallel, make
443          * sure we read it once and use the same value throughout.
444          */
445         int signum = ACCESS_ONCE(fown->signum);
446 
447         if (!sigio_perm(p, fown, signum))
448                 return;
449 
450         switch (signum) {
451                 siginfo_t si;
452                 default:
453                         /* Queue a rt signal with the appropriate fd as its
454                            value.  We use SI_SIGIO as the source, not 
455                            SI_KERNEL, since kernel signals always get 
456                            delivered even if we can't queue.  Failure to
457                            queue in this case _should_ be reported; we fall
458                            back to SIGIO in that case. --sct */
459                         si.si_signo = signum;
460                         si.si_errno = 0;
461                         si.si_code  = reason;
462                         /* Make sure we are called with one of the POLL_*
463                            reasons, otherwise we could leak kernel stack into
464                            userspace.  */
465                         BUG_ON((reason & __SI_MASK) != __SI_POLL);
466                         if (reason - POLL_IN >= NSIGPOLL)
467                                 si.si_band  = ~0L;
468                         else
469                                 si.si_band = band_table[reason - POLL_IN];
470                         si.si_fd    = fd;
471                         if (!do_send_sig_info(signum, &si, p, group))
472                                 break;
473                 /* fall-through: fall back on the old plain SIGIO signal */
474                 case 0:
475                         do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
476         }
477 }
478 
479 void send_sigio(struct fown_struct *fown, int fd, int band)
480 {
481         struct task_struct *p;
482         enum pid_type type;
483         struct pid *pid;
484         int group = 1;
485         
486         read_lock(&fown->lock);
487 
488         type = fown->pid_type;
489         if (type == PIDTYPE_MAX) {
490                 group = 0;
491                 type = PIDTYPE_PID;
492         }
493 
494         pid = fown->pid;
495         if (!pid)
496                 goto out_unlock_fown;
497         
498         read_lock(&tasklist_lock);
499         do_each_pid_task(pid, type, p) {
500                 send_sigio_to_task(p, fown, fd, band, group);
501         } while_each_pid_task(pid, type, p);
502         read_unlock(&tasklist_lock);
503  out_unlock_fown:
504         read_unlock(&fown->lock);
505 }
506 
507 static void send_sigurg_to_task(struct task_struct *p,
508                                 struct fown_struct *fown, int group)
509 {
510         if (sigio_perm(p, fown, SIGURG))
511                 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
512 }
513 
514 int send_sigurg(struct fown_struct *fown)
515 {
516         struct task_struct *p;
517         enum pid_type type;
518         struct pid *pid;
519         int group = 1;
520         int ret = 0;
521         
522         read_lock(&fown->lock);
523 
524         type = fown->pid_type;
525         if (type == PIDTYPE_MAX) {
526                 group = 0;
527                 type = PIDTYPE_PID;
528         }
529 
530         pid = fown->pid;
531         if (!pid)
532                 goto out_unlock_fown;
533 
534         ret = 1;
535         
536         read_lock(&tasklist_lock);
537         do_each_pid_task(pid, type, p) {
538                 send_sigurg_to_task(p, fown, group);
539         } while_each_pid_task(pid, type, p);
540         read_unlock(&tasklist_lock);
541  out_unlock_fown:
542         read_unlock(&fown->lock);
543         return ret;
544 }
545 
546 static DEFINE_SPINLOCK(fasync_lock);
547 static struct kmem_cache *fasync_cache __read_mostly;
548 
549 static void fasync_free_rcu(struct rcu_head *head)
550 {
551         kmem_cache_free(fasync_cache,
552                         container_of(head, struct fasync_struct, fa_rcu));
553 }
554 
555 /*
556  * Remove a fasync entry. If successfully removed, return
557  * positive and clear the FASYNC flag. If no entry exists,
558  * do nothing and return 0.
559  *
560  * NOTE! It is very important that the FASYNC flag always
561  * match the state "is the filp on a fasync list".
562  *
563  */
564 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
565 {
566         struct fasync_struct *fa, **fp;
567         int result = 0;
568 
569         spin_lock(&filp->f_lock);
570         spin_lock(&fasync_lock);
571         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
572                 if (fa->fa_file != filp)
573                         continue;
574 
575                 spin_lock_irq(&fa->fa_lock);
576                 fa->fa_file = NULL;
577                 spin_unlock_irq(&fa->fa_lock);
578 
579                 *fp = fa->fa_next;
580                 call_rcu(&fa->fa_rcu, fasync_free_rcu);
581                 filp->f_flags &= ~FASYNC;
582                 result = 1;
583                 break;
584         }
585         spin_unlock(&fasync_lock);
586         spin_unlock(&filp->f_lock);
587         return result;
588 }
589 
590 struct fasync_struct *fasync_alloc(void)
591 {
592         return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
593 }
594 
595 /*
596  * NOTE! This can be used only for unused fasync entries:
597  * entries that actually got inserted on the fasync list
598  * need to be released by rcu - see fasync_remove_entry.
599  */
600 void fasync_free(struct fasync_struct *new)
601 {
602         kmem_cache_free(fasync_cache, new);
603 }
604 
605 /*
606  * Insert a new entry into the fasync list.  Return the pointer to the
607  * old one if we didn't use the new one.
608  *
609  * NOTE! It is very important that the FASYNC flag always
610  * match the state "is the filp on a fasync list".
611  */
612 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
613 {
614         struct fasync_struct *fa, **fp;
615 
616         spin_lock(&filp->f_lock);
617         spin_lock(&fasync_lock);
618         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
619                 if (fa->fa_file != filp)
620                         continue;
621 
622                 spin_lock_irq(&fa->fa_lock);
623                 fa->fa_fd = fd;
624                 spin_unlock_irq(&fa->fa_lock);
625                 goto out;
626         }
627 
628         spin_lock_init(&new->fa_lock);
629         new->magic = FASYNC_MAGIC;
630         new->fa_file = filp;
631         new->fa_fd = fd;
632         new->fa_next = *fapp;
633         rcu_assign_pointer(*fapp, new);
634         filp->f_flags |= FASYNC;
635 
636 out:
637         spin_unlock(&fasync_lock);
638         spin_unlock(&filp->f_lock);
639         return fa;
640 }
641 
642 /*
643  * Add a fasync entry. Return negative on error, positive if
644  * added, and zero if did nothing but change an existing one.
645  */
646 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
647 {
648         struct fasync_struct *new;
649 
650         new = fasync_alloc();
651         if (!new)
652                 return -ENOMEM;
653 
654         /*
655          * fasync_insert_entry() returns the old (update) entry if
656          * it existed.
657          *
658          * So free the (unused) new entry and return 0 to let the
659          * caller know that we didn't add any new fasync entries.
660          */
661         if (fasync_insert_entry(fd, filp, fapp, new)) {
662                 fasync_free(new);
663                 return 0;
664         }
665 
666         return 1;
667 }
668 
669 /*
670  * fasync_helper() is used by almost all character device drivers
671  * to set up the fasync queue, and for regular files by the file
672  * lease code. It returns negative on error, 0 if it did no changes
673  * and positive if it added/deleted the entry.
674  */
675 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
676 {
677         if (!on)
678                 return fasync_remove_entry(filp, fapp);
679         return fasync_add_entry(fd, filp, fapp);
680 }
681 
682 EXPORT_SYMBOL(fasync_helper);
683 
684 /*
685  * rcu_read_lock() is held
686  */
687 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
688 {
689         while (fa) {
690                 struct fown_struct *fown;
691                 unsigned long flags;
692 
693                 if (fa->magic != FASYNC_MAGIC) {
694                         printk(KERN_ERR "kill_fasync: bad magic number in "
695                                "fasync_struct!\n");
696                         return;
697                 }
698                 spin_lock_irqsave(&fa->fa_lock, flags);
699                 if (fa->fa_file) {
700                         fown = &fa->fa_file->f_owner;
701                         /* Don't send SIGURG to processes which have not set a
702                            queued signum: SIGURG has its own default signalling
703                            mechanism. */
704                         if (!(sig == SIGURG && fown->signum == 0))
705                                 send_sigio(fown, fa->fa_fd, band);
706                 }
707                 spin_unlock_irqrestore(&fa->fa_lock, flags);
708                 fa = rcu_dereference(fa->fa_next);
709         }
710 }
711 
712 void kill_fasync(struct fasync_struct **fp, int sig, int band)
713 {
714         /* First a quick test without locking: usually
715          * the list is empty.
716          */
717         if (*fp) {
718                 rcu_read_lock();
719                 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
720                 rcu_read_unlock();
721         }
722 }
723 EXPORT_SYMBOL(kill_fasync);
724 
725 static int __init fcntl_init(void)
726 {
727         /*
728          * Please add new bits here to ensure allocation uniqueness.
729          * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
730          * is defined as O_NONBLOCK on some platforms and not on others.
731          */
732         BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
733                 O_RDONLY        | O_WRONLY      | O_RDWR        |
734                 O_CREAT         | O_EXCL        | O_NOCTTY      |
735                 O_TRUNC         | O_APPEND      | /* O_NONBLOCK | */
736                 __O_SYNC        | O_DSYNC       | FASYNC        |
737                 O_DIRECT        | O_LARGEFILE   | O_DIRECTORY   |
738                 O_NOFOLLOW      | O_NOATIME     | O_CLOEXEC     |
739                 __FMODE_EXEC    | O_PATH        | __O_TMPFILE
740                 ));
741 
742         fasync_cache = kmem_cache_create("fasync_cache",
743                 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
744         return 0;
745 }
746 
747 module_init(fcntl_init)
748 

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