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8#include <linux/string.h>
9#include <linux/slab.h>
10#include <linux/file.h>
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/fs.h>
14#include <linux/security.h>
15#include <linux/eventpoll.h>
16#include <linux/rcupdate.h>
17#include <linux/mount.h>
18#include <linux/capability.h>
19#include <linux/cdev.h>
20#include <linux/fsnotify.h>
21#include <linux/sysctl.h>
22#include <linux/percpu_counter.h>
23
24#include <asm/atomic.h>
25
26
27struct files_stat_struct files_stat = {
28 .max_files = NR_FILE
29};
30
31
32__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
33
34static struct percpu_counter nr_files __cacheline_aligned_in_smp;
35
36static inline void file_free_rcu(struct rcu_head *head)
37{
38 struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
39 kmem_cache_free(filp_cachep, f);
40}
41
42static inline void file_free(struct file *f)
43{
44 percpu_counter_dec(&nr_files);
45 call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
46}
47
48
49
50
51static int get_nr_files(void)
52{
53 return percpu_counter_read_positive(&nr_files);
54}
55
56
57
58
59int get_max_files(void)
60{
61 return files_stat.max_files;
62}
63EXPORT_SYMBOL_GPL(get_max_files);
64
65
66
67
68#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
69int proc_nr_files(ctl_table *table, int write, struct file *filp,
70 void __user *buffer, size_t *lenp, loff_t *ppos)
71{
72 files_stat.nr_files = get_nr_files();
73 return proc_dointvec(table, write, filp, buffer, lenp, ppos);
74}
75#else
76int proc_nr_files(ctl_table *table, int write, struct file *filp,
77 void __user *buffer, size_t *lenp, loff_t *ppos)
78{
79 return -ENOSYS;
80}
81#endif
82
83
84
85
86
87struct file *get_empty_filp(void)
88{
89 struct task_struct *tsk;
90 static int old_max;
91 struct file * f;
92
93
94
95
96 if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
97
98
99
100
101 if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
102 goto over;
103 }
104
105 f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
106 if (f == NULL)
107 goto fail;
108
109 percpu_counter_inc(&nr_files);
110 if (security_file_alloc(f))
111 goto fail_sec;
112
113 tsk = current;
114 INIT_LIST_HEAD(&f->f_u.fu_list);
115 atomic_set(&f->f_count, 1);
116 rwlock_init(&f->f_owner.lock);
117 f->f_uid = tsk->fsuid;
118 f->f_gid = tsk->fsgid;
119 eventpoll_init_file(f);
120
121 return f;
122
123over:
124
125 if (get_nr_files() > old_max) {
126 printk(KERN_INFO "VFS: file-max limit %d reached\n",
127 get_max_files());
128 old_max = get_nr_files();
129 }
130 goto fail;
131
132fail_sec:
133 file_free(f);
134fail:
135 return NULL;
136}
137
138EXPORT_SYMBOL(get_empty_filp);
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154
155struct file *alloc_file(struct vfsmount *mnt, struct dentry *dentry,
156 mode_t mode, const struct file_operations *fop)
157{
158 struct file *file;
159 struct path;
160
161 file = get_empty_filp();
162 if (!file)
163 return NULL;
164
165 init_file(file, mnt, dentry, mode, fop);
166 return file;
167}
168EXPORT_SYMBOL(alloc_file);
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186
187int init_file(struct file *file, struct vfsmount *mnt, struct dentry *dentry,
188 mode_t mode, const struct file_operations *fop)
189{
190 int error = 0;
191 file->f_path.dentry = dentry;
192 file->f_path.mnt = mntget(mnt);
193 file->f_mapping = dentry->d_inode->i_mapping;
194 file->f_mode = mode;
195 file->f_op = fop;
196 return error;
197}
198EXPORT_SYMBOL(init_file);
199
200void fastcall fput(struct file *file)
201{
202 if (atomic_dec_and_test(&file->f_count))
203 __fput(file);
204}
205
206EXPORT_SYMBOL(fput);
207
208
209
210
211void fastcall __fput(struct file *file)
212{
213 struct dentry *dentry = file->f_path.dentry;
214 struct vfsmount *mnt = file->f_path.mnt;
215 struct inode *inode = dentry->d_inode;
216
217 might_sleep();
218
219 fsnotify_close(file);
220
221
222
223
224 eventpoll_release(file);
225 locks_remove_flock(file);
226
227 if (file->f_op && file->f_op->release)
228 file->f_op->release(inode, file);
229 security_file_free(file);
230 if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL))
231 cdev_put(inode->i_cdev);
232 fops_put(file->f_op);
233 if (file->f_mode & FMODE_WRITE)
234 put_write_access(inode);
235 put_pid(file->f_owner.pid);
236 file_kill(file);
237 file->f_path.dentry = NULL;
238 file->f_path.mnt = NULL;
239 file_free(file);
240 dput(dentry);
241 mntput(mnt);
242}
243
244struct file fastcall *fget(unsigned int fd)
245{
246 struct file *file;
247 struct files_struct *files = current->files;
248
249 rcu_read_lock();
250 file = fcheck_files(files, fd);
251 if (file) {
252 if (!atomic_inc_not_zero(&file->f_count)) {
253
254 rcu_read_unlock();
255 return NULL;
256 }
257 }
258 rcu_read_unlock();
259
260 return file;
261}
262
263EXPORT_SYMBOL(fget);
264
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271
272struct file fastcall *fget_light(unsigned int fd, int *fput_needed)
273{
274 struct file *file;
275 struct files_struct *files = current->files;
276
277 *fput_needed = 0;
278 if (likely((atomic_read(&files->count) == 1))) {
279 file = fcheck_files(files, fd);
280 } else {
281 rcu_read_lock();
282 file = fcheck_files(files, fd);
283 if (file) {
284 if (atomic_inc_not_zero(&file->f_count))
285 *fput_needed = 1;
286 else
287
288 file = NULL;
289 }
290 rcu_read_unlock();
291 }
292
293 return file;
294}
295
296
297void put_filp(struct file *file)
298{
299 if (atomic_dec_and_test(&file->f_count)) {
300 security_file_free(file);
301 file_kill(file);
302 file_free(file);
303 }
304}
305
306void file_move(struct file *file, struct list_head *list)
307{
308 if (!list)
309 return;
310 file_list_lock();
311 list_move(&file->f_u.fu_list, list);
312 file_list_unlock();
313}
314
315void file_kill(struct file *file)
316{
317 if (!list_empty(&file->f_u.fu_list)) {
318 file_list_lock();
319 list_del_init(&file->f_u.fu_list);
320 file_list_unlock();
321 }
322}
323
324int fs_may_remount_ro(struct super_block *sb)
325{
326 struct file *file;
327
328
329 file_list_lock();
330 list_for_each_entry(file, &sb->s_files, f_u.fu_list) {
331 struct inode *inode = file->f_path.dentry->d_inode;
332
333
334 if (inode->i_nlink == 0)
335 goto too_bad;
336
337
338 if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
339 goto too_bad;
340 }
341 file_list_unlock();
342 return 1;
343too_bad:
344 file_list_unlock();
345 return 0;
346}
347
348void __init files_init(unsigned long mempages)
349{
350 int n;
351
352
353
354
355 n = (mempages * (PAGE_SIZE / 1024)) / 10;
356 files_stat.max_files = n;
357 if (files_stat.max_files < NR_FILE)
358 files_stat.max_files = NR_FILE;
359 files_defer_init();
360 percpu_counter_init(&nr_files, 0);
361}
362