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8#include <linux/string.h>
9#include <linux/slab.h>
10#include <linux/file.h>
11#include <linux/fdtable.h>
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/fs.h>
15#include <linux/security.h>
16#include <linux/eventpoll.h>
17#include <linux/rcupdate.h>
18#include <linux/mount.h>
19#include <linux/capability.h>
20#include <linux/cdev.h>
21#include <linux/fsnotify.h>
22#include <linux/sysctl.h>
23#include <linux/lglock.h>
24#include <linux/percpu_counter.h>
25#include <linux/percpu.h>
26#include <linux/hardirq.h>
27#include <linux/task_work.h>
28#include <linux/ima.h>
29
30#include <linux/atomic.h>
31
32#include "internal.h"
33
34
35struct files_stat_struct files_stat = {
36 .max_files = NR_FILE
37};
38
39DEFINE_STATIC_LGLOCK(files_lglock);
40
41
42static struct kmem_cache *filp_cachep __read_mostly;
43
44static struct percpu_counter nr_files __cacheline_aligned_in_smp;
45
46static void file_free_rcu(struct rcu_head *head)
47{
48 struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
49
50 put_cred(f->f_cred);
51 kmem_cache_free(filp_cachep, f);
52}
53
54static inline void file_free(struct file *f)
55{
56 percpu_counter_dec(&nr_files);
57 file_check_state(f);
58 call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
59}
60
61
62
63
64static long get_nr_files(void)
65{
66 return percpu_counter_read_positive(&nr_files);
67}
68
69
70
71
72unsigned long get_max_files(void)
73{
74 return files_stat.max_files;
75}
76EXPORT_SYMBOL_GPL(get_max_files);
77
78
79
80
81#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
82int proc_nr_files(ctl_table *table, int write,
83 void __user *buffer, size_t *lenp, loff_t *ppos)
84{
85 files_stat.nr_files = get_nr_files();
86 return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
87}
88#else
89int proc_nr_files(ctl_table *table, int write,
90 void __user *buffer, size_t *lenp, loff_t *ppos)
91{
92 return -ENOSYS;
93}
94#endif
95
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103
104
105
106struct file *get_empty_filp(void)
107{
108 const struct cred *cred = current_cred();
109 static long old_max;
110 struct file *f;
111 int error;
112
113
114
115
116 if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
117
118
119
120
121 if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
122 goto over;
123 }
124
125 f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
126 if (unlikely(!f))
127 return ERR_PTR(-ENOMEM);
128
129 percpu_counter_inc(&nr_files);
130 f->f_cred = get_cred(cred);
131 error = security_file_alloc(f);
132 if (unlikely(error)) {
133 file_free(f);
134 return ERR_PTR(error);
135 }
136
137 INIT_LIST_HEAD(&f->f_u.fu_list);
138 atomic_long_set(&f->f_count, 1);
139 rwlock_init(&f->f_owner.lock);
140 spin_lock_init(&f->f_lock);
141 eventpoll_init_file(f);
142
143 return f;
144
145over:
146
147 if (get_nr_files() > old_max) {
148 pr_info("VFS: file-max limit %lu reached\n", get_max_files());
149 old_max = get_nr_files();
150 }
151 return ERR_PTR(-ENFILE);
152}
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168
169struct file *alloc_file(struct path *path, fmode_t mode,
170 const struct file_operations *fop)
171{
172 struct file *file;
173
174 file = get_empty_filp();
175 if (IS_ERR(file))
176 return file;
177
178 file->f_path = *path;
179 file->f_inode = path->dentry->d_inode;
180 file->f_mapping = path->dentry->d_inode->i_mapping;
181 file->f_mode = mode;
182 file->f_op = fop;
183
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189
190 if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) {
191 file_take_write(file);
192 WARN_ON(mnt_clone_write(path->mnt));
193 }
194 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
195 i_readcount_inc(path->dentry->d_inode);
196 return file;
197}
198EXPORT_SYMBOL(alloc_file);
199
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207
208static void drop_file_write_access(struct file *file)
209{
210 struct vfsmount *mnt = file->f_path.mnt;
211 struct dentry *dentry = file->f_path.dentry;
212 struct inode *inode = dentry->d_inode;
213
214 put_write_access(inode);
215
216 if (special_file(inode->i_mode))
217 return;
218 if (file_check_writeable(file) != 0)
219 return;
220 __mnt_drop_write(mnt);
221 file_release_write(file);
222}
223
224
225
226static void __fput(struct file *file)
227{
228 struct dentry *dentry = file->f_path.dentry;
229 struct vfsmount *mnt = file->f_path.mnt;
230 struct inode *inode = dentry->d_inode;
231
232 might_sleep();
233
234 fsnotify_close(file);
235
236
237
238
239 eventpoll_release(file);
240 locks_remove_flock(file);
241
242 if (unlikely(file->f_flags & FASYNC)) {
243 if (file->f_op && file->f_op->fasync)
244 file->f_op->fasync(-1, file, 0);
245 }
246 ima_file_free(file);
247 if (file->f_op && file->f_op->release)
248 file->f_op->release(inode, file);
249 security_file_free(file);
250 if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
251 !(file->f_mode & FMODE_PATH))) {
252 cdev_put(inode->i_cdev);
253 }
254 fops_put(file->f_op);
255 put_pid(file->f_owner.pid);
256 if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
257 i_readcount_dec(inode);
258 if (file->f_mode & FMODE_WRITE)
259 drop_file_write_access(file);
260 file->f_path.dentry = NULL;
261 file->f_path.mnt = NULL;
262 file->f_inode = NULL;
263 file_free(file);
264 dput(dentry);
265 mntput(mnt);
266}
267
268static DEFINE_SPINLOCK(delayed_fput_lock);
269static LIST_HEAD(delayed_fput_list);
270static void delayed_fput(struct work_struct *unused)
271{
272 LIST_HEAD(head);
273 spin_lock_irq(&delayed_fput_lock);
274 list_splice_init(&delayed_fput_list, &head);
275 spin_unlock_irq(&delayed_fput_lock);
276 while (!list_empty(&head)) {
277 struct file *f = list_first_entry(&head, struct file, f_u.fu_list);
278 list_del_init(&f->f_u.fu_list);
279 __fput(f);
280 }
281}
282
283static void ____fput(struct callback_head *work)
284{
285 __fput(container_of(work, struct file, f_u.fu_rcuhead));
286}
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298void flush_delayed_fput(void)
299{
300 delayed_fput(NULL);
301}
302
303static DECLARE_WORK(delayed_fput_work, delayed_fput);
304
305void fput(struct file *file)
306{
307 if (atomic_long_dec_and_test(&file->f_count)) {
308 struct task_struct *task = current;
309 unsigned long flags;
310
311 file_sb_list_del(file);
312 if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
313 init_task_work(&file->f_u.fu_rcuhead, ____fput);
314 if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
315 return;
316 }
317 spin_lock_irqsave(&delayed_fput_lock, flags);
318 list_add(&file->f_u.fu_list, &delayed_fput_list);
319 schedule_work(&delayed_fput_work);
320 spin_unlock_irqrestore(&delayed_fput_lock, flags);
321 }
322}
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331
332void __fput_sync(struct file *file)
333{
334 if (atomic_long_dec_and_test(&file->f_count)) {
335 struct task_struct *task = current;
336 file_sb_list_del(file);
337 BUG_ON(!(task->flags & PF_KTHREAD));
338 __fput(file);
339 }
340}
341
342EXPORT_SYMBOL(fput);
343
344void put_filp(struct file *file)
345{
346 if (atomic_long_dec_and_test(&file->f_count)) {
347 security_file_free(file);
348 file_sb_list_del(file);
349 file_free(file);
350 }
351}
352
353static inline int file_list_cpu(struct file *file)
354{
355#ifdef CONFIG_SMP
356 return file->f_sb_list_cpu;
357#else
358 return smp_processor_id();
359#endif
360}
361
362
363static inline void __file_sb_list_add(struct file *file, struct super_block *sb)
364{
365 struct list_head *list;
366#ifdef CONFIG_SMP
367 int cpu;
368 cpu = smp_processor_id();
369 file->f_sb_list_cpu = cpu;
370 list = per_cpu_ptr(sb->s_files, cpu);
371#else
372 list = &sb->s_files;
373#endif
374 list_add(&file->f_u.fu_list, list);
375}
376
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385void file_sb_list_add(struct file *file, struct super_block *sb)
386{
387 lg_local_lock(&files_lglock);
388 __file_sb_list_add(file, sb);
389 lg_local_unlock(&files_lglock);
390}
391
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397
398
399void file_sb_list_del(struct file *file)
400{
401 if (!list_empty(&file->f_u.fu_list)) {
402 lg_local_lock_cpu(&files_lglock, file_list_cpu(file));
403 list_del_init(&file->f_u.fu_list);
404 lg_local_unlock_cpu(&files_lglock, file_list_cpu(file));
405 }
406}
407
408#ifdef CONFIG_SMP
409
410
411
412
413
414#define do_file_list_for_each_entry(__sb, __file) \
415{ \
416 int i; \
417 for_each_possible_cpu(i) { \
418 struct list_head *list; \
419 list = per_cpu_ptr((__sb)->s_files, i); \
420 list_for_each_entry((__file), list, f_u.fu_list)
421
422#define while_file_list_for_each_entry \
423 } \
424}
425
426#else
427
428#define do_file_list_for_each_entry(__sb, __file) \
429{ \
430 struct list_head *list; \
431 list = &(sb)->s_files; \
432 list_for_each_entry((__file), list, f_u.fu_list)
433
434#define while_file_list_for_each_entry \
435}
436
437#endif
438
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443
444
445
446void mark_files_ro(struct super_block *sb)
447{
448 struct file *f;
449
450 lg_global_lock(&files_lglock);
451 do_file_list_for_each_entry(sb, f) {
452 if (!S_ISREG(file_inode(f)->i_mode))
453 continue;
454 if (!file_count(f))
455 continue;
456 if (!(f->f_mode & FMODE_WRITE))
457 continue;
458 spin_lock(&f->f_lock);
459 f->f_mode &= ~FMODE_WRITE;
460 spin_unlock(&f->f_lock);
461 if (file_check_writeable(f) != 0)
462 continue;
463 __mnt_drop_write(f->f_path.mnt);
464 file_release_write(f);
465 } while_file_list_for_each_entry;
466 lg_global_unlock(&files_lglock);
467}
468
469void __init files_init(unsigned long mempages)
470{
471 unsigned long n;
472
473 filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
474 SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
475
476
477
478
479
480
481 n = (mempages * (PAGE_SIZE / 1024)) / 10;
482 files_stat.max_files = max_t(unsigned long, n, NR_FILE);
483 files_defer_init();
484 lg_lock_init(&files_lglock, "files_lglock");
485 percpu_counter_init(&nr_files, 0);
486}
487