blob: a04bdd81c11ca3799d4429d8c5eb3579621e0628 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/file_table.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
6 */
7
8#include <linux/string.h>
9#include <linux/slab.h>
10#include <linux/file.h>
Al Viro9f3acc32008-04-24 07:44:08 -040011#include <linux/fdtable.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/init.h>
13#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/fs.h>
15#include <linux/security.h>
16#include <linux/eventpoll.h>
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070017#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/mount.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080019#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/cdev.h>
Robert Love0eeca282005-07-12 17:06:03 -040021#include <linux/fsnotify.h>
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080022#include <linux/sysctl.h>
Nick Piggin6416ccb2010-08-18 04:37:38 +100023#include <linux/lglock.h>
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080024#include <linux/percpu_counter.h>
Nick Piggin6416ccb2010-08-18 04:37:38 +100025#include <linux/percpu.h>
Al Viro0552f872009-12-16 04:53:03 -050026#include <linux/ima.h>
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080027
28#include <asm/atomic.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
Eric Parise81e3f42009-12-04 15:47:36 -050030#include "internal.h"
31
Linus Torvalds1da177e2005-04-16 15:20:36 -070032/* sysctl tunables... */
33struct files_stat_struct files_stat = {
34 .max_files = NR_FILE
35};
36
Nick Piggin6416ccb2010-08-18 04:37:38 +100037DECLARE_LGLOCK(files_lglock);
38DEFINE_LGLOCK(files_lglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
Eric Dumazetb6b3fde2008-12-10 09:35:45 -080040/* SLAB cache for file structures */
41static struct kmem_cache *filp_cachep __read_mostly;
42
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080043static struct percpu_counter nr_files __cacheline_aligned_in_smp;
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070045static inline void file_free_rcu(struct rcu_head *head)
46{
David Howellsd76b0d92008-11-14 10:39:25 +110047 struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
48
49 put_cred(f->f_cred);
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070050 kmem_cache_free(filp_cachep, f);
51}
52
Linus Torvalds1da177e2005-04-16 15:20:36 -070053static inline void file_free(struct file *f)
54{
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080055 percpu_counter_dec(&nr_files);
Dave Hansenad775f52008-02-15 14:38:01 -080056 file_check_state(f);
Eric Dumazet2f512012005-10-30 15:02:16 -080057 call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
Linus Torvalds1da177e2005-04-16 15:20:36 -070058}
59
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080060/*
61 * Return the total number of open files in the system
62 */
63static int get_nr_files(void)
64{
65 return percpu_counter_read_positive(&nr_files);
66}
67
68/*
69 * Return the maximum number of open files in the system
70 */
71int get_max_files(void)
72{
73 return files_stat.max_files;
74}
75EXPORT_SYMBOL_GPL(get_max_files);
76
77/*
78 * Handle nr_files sysctl
79 */
80#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
Alexey Dobriyan8d65af72009-09-23 15:57:19 -070081int proc_nr_files(ctl_table *table, int write,
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080082 void __user *buffer, size_t *lenp, loff_t *ppos)
83{
84 files_stat.nr_files = get_nr_files();
Alexey Dobriyan8d65af72009-09-23 15:57:19 -070085 return proc_dointvec(table, write, buffer, lenp, ppos);
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080086}
87#else
Alexey Dobriyan8d65af72009-09-23 15:57:19 -070088int proc_nr_files(ctl_table *table, int write,
Dipankar Sarma529bf6b2006-03-07 21:55:35 -080089 void __user *buffer, size_t *lenp, loff_t *ppos)
90{
91 return -ENOSYS;
92}
93#endif
94
Linus Torvalds1da177e2005-04-16 15:20:36 -070095/* Find an unused file structure and return a pointer to it.
96 * Returns NULL, if there are no more free file structures or
97 * we run out of memory.
Dave Hansen430e2852008-02-15 14:37:26 -080098 *
99 * Be very careful using this. You are responsible for
100 * getting write access to any mount that you might assign
101 * to this filp, if it is opened for write. If this is not
102 * done, you will imbalance int the mount's writer count
103 * and a warning at __fput() time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 */
105struct file *get_empty_filp(void)
106{
David Howells86a264a2008-11-14 10:39:18 +1100107 const struct cred *cred = current_cred();
Kirill Korotaevaf4d2ec2005-06-23 00:09:50 -0700108 static int old_max;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 struct file * f;
110
111 /*
112 * Privileged users can go above max_files
113 */
Dipankar Sarma529bf6b2006-03-07 21:55:35 -0800114 if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
115 /*
116 * percpu_counters are inaccurate. Do an expensive check before
117 * we go and fail.
118 */
Peter Zijlstra52d9f3b2007-10-16 23:25:44 -0700119 if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
Dipankar Sarma529bf6b2006-03-07 21:55:35 -0800120 goto over;
121 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122
Denis Cheng4975e452007-10-16 23:26:19 -0700123 f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
Kirill Korotaevaf4d2ec2005-06-23 00:09:50 -0700124 if (f == NULL)
125 goto fail;
126
Dipankar Sarma529bf6b2006-03-07 21:55:35 -0800127 percpu_counter_inc(&nr_files);
Kirill Korotaevaf4d2ec2005-06-23 00:09:50 -0700128 if (security_file_alloc(f))
129 goto fail_sec;
130
Eric Dumazet2f512012005-10-30 15:02:16 -0800131 INIT_LIST_HEAD(&f->f_u.fu_list);
Al Viro516e0cc2008-07-26 00:39:17 -0400132 atomic_long_set(&f->f_count, 1);
Benjamin LaHaise5a6b7952006-03-23 03:01:03 -0800133 rwlock_init(&f->f_owner.lock);
David Howellsd76b0d92008-11-14 10:39:25 +1100134 f->f_cred = get_cred(cred);
Jonathan Corbet68499912009-02-06 13:52:43 -0700135 spin_lock_init(&f->f_lock);
Benjamin LaHaise5a6b7952006-03-23 03:01:03 -0800136 eventpoll_init_file(f);
137 /* f->f_version: 0 */
Kirill Korotaevaf4d2ec2005-06-23 00:09:50 -0700138 return f;
139
140over:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 /* Ran out of filps - report that */
Dipankar Sarma529bf6b2006-03-07 21:55:35 -0800142 if (get_nr_files() > old_max) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 printk(KERN_INFO "VFS: file-max limit %d reached\n",
Dipankar Sarma529bf6b2006-03-07 21:55:35 -0800144 get_max_files());
145 old_max = get_nr_files();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 }
Kirill Korotaevaf4d2ec2005-06-23 00:09:50 -0700147 goto fail;
148
149fail_sec:
150 file_free(f);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151fail:
152 return NULL;
153}
154
Dave Hansence8d2cd2007-10-16 23:31:13 -0700155/**
156 * alloc_file - allocate and initialize a 'struct file'
157 * @mnt: the vfsmount on which the file will reside
158 * @dentry: the dentry representing the new file
159 * @mode: the mode with which the new file will be opened
160 * @fop: the 'struct file_operations' for the new file
161 *
162 * Use this instead of get_empty_filp() to get a new
163 * 'struct file'. Do so because of the same initialization
164 * pitfalls reasons listed for init_file(). This is a
165 * preferred interface to using init_file().
166 *
167 * If all the callers of init_file() are eliminated, its
168 * code should be moved into this function.
169 */
Al Viro2c48b9c2009-08-09 00:52:35 +0400170struct file *alloc_file(struct path *path, fmode_t mode,
171 const struct file_operations *fop)
Dave Hansence8d2cd2007-10-16 23:31:13 -0700172{
173 struct file *file;
Dave Hansence8d2cd2007-10-16 23:31:13 -0700174
175 file = get_empty_filp();
176 if (!file)
177 return NULL;
178
Al Viro2c48b9c2009-08-09 00:52:35 +0400179 file->f_path = *path;
180 file->f_mapping = path->dentry->d_inode->i_mapping;
Dave Hansence8d2cd2007-10-16 23:31:13 -0700181 file->f_mode = mode;
182 file->f_op = fop;
Dave Hansen4a3fd212008-02-15 14:37:48 -0800183
184 /*
185 * These mounts don't really matter in practice
186 * for r/o bind mounts. They aren't userspace-
187 * visible. We do this for consistency, and so
188 * that we can do debugging checks at __fput()
189 */
Al Viro2c48b9c2009-08-09 00:52:35 +0400190 if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) {
Dave Hansenad775f52008-02-15 14:38:01 -0800191 file_take_write(file);
Roland Dreier385e3ed2009-12-16 12:48:44 -0800192 WARN_ON(mnt_clone_write(path->mnt));
Dave Hansen4a3fd212008-02-15 14:37:48 -0800193 }
Al Viro0552f872009-12-16 04:53:03 -0500194 ima_counts_get(file);
Al Viro3d1e4632009-08-08 23:56:29 +0400195 return file;
Dave Hansence8d2cd2007-10-16 23:31:13 -0700196}
Roland Dreier73efc462009-12-16 12:43:11 -0800197EXPORT_SYMBOL(alloc_file);
Dave Hansence8d2cd2007-10-16 23:31:13 -0700198
Dave Hansenaceaf782008-02-15 14:37:31 -0800199/**
200 * drop_file_write_access - give up ability to write to a file
201 * @file: the file to which we will stop writing
202 *
203 * This is a central place which will give up the ability
204 * to write to @file, along with access to write through
205 * its vfsmount.
206 */
207void drop_file_write_access(struct file *file)
208{
Dave Hansen4a3fd212008-02-15 14:37:48 -0800209 struct vfsmount *mnt = file->f_path.mnt;
Dave Hansenaceaf782008-02-15 14:37:31 -0800210 struct dentry *dentry = file->f_path.dentry;
211 struct inode *inode = dentry->d_inode;
212
213 put_write_access(inode);
Dave Hansenad775f52008-02-15 14:38:01 -0800214
215 if (special_file(inode->i_mode))
216 return;
217 if (file_check_writeable(file) != 0)
218 return;
219 mnt_drop_write(mnt);
220 file_release_write(file);
Dave Hansenaceaf782008-02-15 14:37:31 -0800221}
222EXPORT_SYMBOL_GPL(drop_file_write_access);
223
Al Virod7065da2010-05-26 15:13:55 -0400224/* the real guts of fput() - releasing the last reference to file
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 */
Al Virod7065da2010-05-26 15:13:55 -0400226static void __fput(struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800228 struct dentry *dentry = file->f_path.dentry;
229 struct vfsmount *mnt = file->f_path.mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 struct inode *inode = dentry->d_inode;
231
232 might_sleep();
Robert Love0eeca282005-07-12 17:06:03 -0400233
234 fsnotify_close(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 /*
236 * The function eventpoll_release() should be the first called
237 * in the file cleanup chain.
238 */
239 eventpoll_release(file);
240 locks_remove_flock(file);
241
Al Viro233e70f2008-10-31 23:28:30 +0000242 if (unlikely(file->f_flags & FASYNC)) {
243 if (file->f_op && file->f_op->fasync)
244 file->f_op->fasync(-1, file, 0);
245 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 if (file->f_op && file->f_op->release)
247 file->f_op->release(inode, file);
248 security_file_free(file);
Al Viro89068c52010-02-07 03:07:29 -0500249 ima_file_free(file);
Theodore Ts'o577c4eb2006-09-27 01:50:49 -0700250 if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 cdev_put(inode->i_cdev);
252 fops_put(file->f_op);
Eric W. Biederman609d7fa2006-10-02 02:17:15 -0700253 put_pid(file->f_owner.pid);
Nick Pigginee2ffa02010-08-18 04:37:35 +1000254 file_sb_list_del(file);
Dave Hansenaceaf782008-02-15 14:37:31 -0800255 if (file->f_mode & FMODE_WRITE)
256 drop_file_write_access(file);
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800257 file->f_path.dentry = NULL;
258 file->f_path.mnt = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 file_free(file);
260 dput(dentry);
261 mntput(mnt);
262}
263
Al Virod7065da2010-05-26 15:13:55 -0400264void fput(struct file *file)
265{
266 if (atomic_long_dec_and_test(&file->f_count))
267 __fput(file);
268}
269
270EXPORT_SYMBOL(fput);
271
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -0800272struct file *fget(unsigned int fd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273{
274 struct file *file;
275 struct files_struct *files = current->files;
276
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700277 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 file = fcheck_files(files, fd);
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700279 if (file) {
Al Viro516e0cc2008-07-26 00:39:17 -0400280 if (!atomic_long_inc_not_zero(&file->f_count)) {
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700281 /* File object ref couldn't be taken */
282 rcu_read_unlock();
283 return NULL;
284 }
285 }
286 rcu_read_unlock();
287
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 return file;
289}
290
291EXPORT_SYMBOL(fget);
292
293/*
Tony Battersby58939472010-08-10 18:01:29 -0700294 * Lightweight file lookup - no refcnt increment if fd table isn't shared.
295 *
296 * You can use this instead of fget if you satisfy all of the following
297 * conditions:
298 * 1) You must call fput_light before exiting the syscall and returning control
299 * to userspace (i.e. you cannot remember the returned struct file * after
300 * returning to userspace).
301 * 2) You must not call filp_close on the returned struct file * in between
302 * calls to fget_light and fput_light.
303 * 3) You must not clone the current task in between the calls to fget_light
304 * and fput_light.
305 *
306 * The fput_needed flag returned by fget_light should be passed to the
307 * corresponding fput_light.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 */
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -0800309struct file *fget_light(unsigned int fd, int *fput_needed)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310{
311 struct file *file;
312 struct files_struct *files = current->files;
313
314 *fput_needed = 0;
315 if (likely((atomic_read(&files->count) == 1))) {
316 file = fcheck_files(files, fd);
317 } else {
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700318 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 file = fcheck_files(files, fd);
320 if (file) {
Al Viro516e0cc2008-07-26 00:39:17 -0400321 if (atomic_long_inc_not_zero(&file->f_count))
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700322 *fput_needed = 1;
323 else
324 /* Didn't get the reference, someone's freed */
325 file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 }
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700327 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 }
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700329
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 return file;
331}
332
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333void put_filp(struct file *file)
334{
Al Viro516e0cc2008-07-26 00:39:17 -0400335 if (atomic_long_dec_and_test(&file->f_count)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 security_file_free(file);
Nick Pigginee2ffa02010-08-18 04:37:35 +1000337 file_sb_list_del(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 file_free(file);
339 }
340}
341
Nick Piggin6416ccb2010-08-18 04:37:38 +1000342static inline int file_list_cpu(struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343{
Nick Piggin6416ccb2010-08-18 04:37:38 +1000344#ifdef CONFIG_SMP
345 return file->f_sb_list_cpu;
346#else
347 return smp_processor_id();
348#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349}
350
Nick Piggin6416ccb2010-08-18 04:37:38 +1000351/* helper for file_sb_list_add to reduce ifdefs */
352static inline void __file_sb_list_add(struct file *file, struct super_block *sb)
353{
354 struct list_head *list;
355#ifdef CONFIG_SMP
356 int cpu;
357 cpu = smp_processor_id();
358 file->f_sb_list_cpu = cpu;
359 list = per_cpu_ptr(sb->s_files, cpu);
360#else
361 list = &sb->s_files;
362#endif
363 list_add(&file->f_u.fu_list, list);
364}
365
366/**
367 * file_sb_list_add - add a file to the sb's file list
368 * @file: file to add
369 * @sb: sb to add it to
370 *
371 * Use this function to associate a file with the superblock of the inode it
372 * refers to.
373 */
374void file_sb_list_add(struct file *file, struct super_block *sb)
375{
376 lg_local_lock(files_lglock);
377 __file_sb_list_add(file, sb);
378 lg_local_unlock(files_lglock);
379}
380
381/**
382 * file_sb_list_del - remove a file from the sb's file list
383 * @file: file to remove
384 * @sb: sb to remove it from
385 *
386 * Use this function to remove a file from its superblock.
387 */
Nick Pigginee2ffa02010-08-18 04:37:35 +1000388void file_sb_list_del(struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389{
Eric Dumazet2f512012005-10-30 15:02:16 -0800390 if (!list_empty(&file->f_u.fu_list)) {
Nick Piggin6416ccb2010-08-18 04:37:38 +1000391 lg_local_lock_cpu(files_lglock, file_list_cpu(file));
Eric Dumazet2f512012005-10-30 15:02:16 -0800392 list_del_init(&file->f_u.fu_list);
Nick Piggin6416ccb2010-08-18 04:37:38 +1000393 lg_local_unlock_cpu(files_lglock, file_list_cpu(file));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 }
395}
396
Nick Piggin6416ccb2010-08-18 04:37:38 +1000397#ifdef CONFIG_SMP
398
399/*
400 * These macros iterate all files on all CPUs for a given superblock.
401 * files_lglock must be held globally.
402 */
403#define do_file_list_for_each_entry(__sb, __file) \
404{ \
405 int i; \
406 for_each_possible_cpu(i) { \
407 struct list_head *list; \
408 list = per_cpu_ptr((__sb)->s_files, i); \
409 list_for_each_entry((__file), list, f_u.fu_list)
410
411#define while_file_list_for_each_entry \
412 } \
413}
414
415#else
416
417#define do_file_list_for_each_entry(__sb, __file) \
418{ \
419 struct list_head *list; \
420 list = &(sb)->s_files; \
421 list_for_each_entry((__file), list, f_u.fu_list)
422
423#define while_file_list_for_each_entry \
424}
425
426#endif
427
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428int fs_may_remount_ro(struct super_block *sb)
429{
Matthias Kaehlckecfdaf9e2007-10-18 23:39:56 -0700430 struct file *file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 /* Check that no files are currently opened for writing. */
Nick Piggin6416ccb2010-08-18 04:37:38 +1000432 lg_global_lock(files_lglock);
433 do_file_list_for_each_entry(sb, file) {
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800434 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435
436 /* File with pending delete? */
437 if (inode->i_nlink == 0)
438 goto too_bad;
439
440 /* Writeable file? */
441 if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
442 goto too_bad;
Nick Piggin6416ccb2010-08-18 04:37:38 +1000443 } while_file_list_for_each_entry;
444 lg_global_unlock(files_lglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 return 1; /* Tis' cool bro. */
446too_bad:
Nick Piggin6416ccb2010-08-18 04:37:38 +1000447 lg_global_unlock(files_lglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 return 0;
449}
450
npiggin@suse.de864d7c42009-04-26 20:25:56 +1000451/**
452 * mark_files_ro - mark all files read-only
453 * @sb: superblock in question
454 *
455 * All files are marked read-only. We don't care about pending
456 * delete files so this should be used in 'force' mode only.
457 */
458void mark_files_ro(struct super_block *sb)
459{
460 struct file *f;
461
462retry:
Nick Piggin6416ccb2010-08-18 04:37:38 +1000463 lg_global_lock(files_lglock);
464 do_file_list_for_each_entry(sb, f) {
npiggin@suse.de864d7c42009-04-26 20:25:56 +1000465 struct vfsmount *mnt;
466 if (!S_ISREG(f->f_path.dentry->d_inode->i_mode))
467 continue;
468 if (!file_count(f))
469 continue;
470 if (!(f->f_mode & FMODE_WRITE))
471 continue;
Wu Fengguang42e49602010-03-05 13:42:01 -0800472 spin_lock(&f->f_lock);
npiggin@suse.de864d7c42009-04-26 20:25:56 +1000473 f->f_mode &= ~FMODE_WRITE;
Wu Fengguang42e49602010-03-05 13:42:01 -0800474 spin_unlock(&f->f_lock);
npiggin@suse.de864d7c42009-04-26 20:25:56 +1000475 if (file_check_writeable(f) != 0)
476 continue;
477 file_release_write(f);
478 mnt = mntget(f->f_path.mnt);
Nick Pigginee2ffa02010-08-18 04:37:35 +1000479 /* This can sleep, so we can't hold the spinlock. */
Nick Piggin6416ccb2010-08-18 04:37:38 +1000480 lg_global_unlock(files_lglock);
npiggin@suse.de864d7c42009-04-26 20:25:56 +1000481 mnt_drop_write(mnt);
482 mntput(mnt);
483 goto retry;
Nick Piggin6416ccb2010-08-18 04:37:38 +1000484 } while_file_list_for_each_entry;
485 lg_global_unlock(files_lglock);
npiggin@suse.de864d7c42009-04-26 20:25:56 +1000486}
487
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488void __init files_init(unsigned long mempages)
489{
490 int n;
Eric Dumazetb6b3fde2008-12-10 09:35:45 -0800491
492 filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
493 SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
494
495 /*
496 * One file with associated inode and dcache is very roughly 1K.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 * Per default don't use more than 10% of our memory for files.
498 */
499
500 n = (mempages * (PAGE_SIZE / 1024)) / 10;
501 files_stat.max_files = n;
502 if (files_stat.max_files < NR_FILE)
503 files_stat.max_files = NR_FILE;
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700504 files_defer_init();
Nick Piggin6416ccb2010-08-18 04:37:38 +1000505 lg_lock_init(files_lglock);
Mingming Cao0216bfc2006-06-23 02:05:41 -0700506 percpu_counter_init(&nr_files, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507}