Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 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 Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 11 | #include <linux/fdtable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 12 | #include <linux/init.h> |
| 13 | #include <linux/module.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | #include <linux/fs.h> |
| 15 | #include <linux/security.h> |
Ingo Molnar | 5b825c3 | 2017-02-02 17:54:15 +0100 | [diff] [blame] | 16 | #include <linux/cred.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | #include <linux/eventpoll.h> |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 18 | #include <linux/rcupdate.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 19 | #include <linux/mount.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 20 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | #include <linux/cdev.h> |
Robert Love | 0eeca28 | 2005-07-12 17:06:03 -0400 | [diff] [blame] | 22 | #include <linux/fsnotify.h> |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 23 | #include <linux/sysctl.h> |
| 24 | #include <linux/percpu_counter.h> |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 25 | #include <linux/percpu.h> |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 26 | #include <linux/hardirq.h> |
| 27 | #include <linux/task_work.h> |
Al Viro | 0552f87 | 2009-12-16 04:53:03 -0500 | [diff] [blame] | 28 | #include <linux/ima.h> |
Mel Gorman | 4248b0d | 2015-08-06 15:46:20 -0700 | [diff] [blame] | 29 | #include <linux/swap.h> |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 30 | |
Arun Sharma | 60063497 | 2011-07-26 16:09:06 -0700 | [diff] [blame] | 31 | #include <linux/atomic.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | |
Eric Paris | e81e3f4 | 2009-12-04 15:47:36 -0500 | [diff] [blame] | 33 | #include "internal.h" |
| 34 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 35 | /* sysctl tunables... */ |
| 36 | struct files_stat_struct files_stat = { |
| 37 | .max_files = NR_FILE |
| 38 | }; |
| 39 | |
Eric Dumazet | b6b3fde | 2008-12-10 09:35:45 -0800 | [diff] [blame] | 40 | /* SLAB cache for file structures */ |
| 41 | static struct kmem_cache *filp_cachep __read_mostly; |
| 42 | |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 43 | static struct percpu_counter nr_files __cacheline_aligned_in_smp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | |
Al Viro | 5c33b18 | 2012-07-20 23:05:59 +0400 | [diff] [blame] | 45 | static void file_free_rcu(struct rcu_head *head) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 46 | { |
David Howells | d76b0d9 | 2008-11-14 10:39:25 +1100 | [diff] [blame] | 47 | struct file *f = container_of(head, struct file, f_u.fu_rcuhead); |
| 48 | |
| 49 | put_cred(f->f_cred); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 50 | kmem_cache_free(filp_cachep, f); |
| 51 | } |
| 52 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 53 | static inline void file_free(struct file *f) |
| 54 | { |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 55 | percpu_counter_dec(&nr_files); |
Eric Dumazet | 2f51201 | 2005-10-30 15:02:16 -0800 | [diff] [blame] | 56 | call_rcu(&f->f_u.fu_rcuhead, file_free_rcu); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | } |
| 58 | |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 59 | /* |
| 60 | * Return the total number of open files in the system |
| 61 | */ |
Eric Dumazet | 518de9b | 2010-10-26 14:22:44 -0700 | [diff] [blame] | 62 | static long get_nr_files(void) |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 63 | { |
| 64 | return percpu_counter_read_positive(&nr_files); |
| 65 | } |
| 66 | |
| 67 | /* |
| 68 | * Return the maximum number of open files in the system |
| 69 | */ |
Eric Dumazet | 518de9b | 2010-10-26 14:22:44 -0700 | [diff] [blame] | 70 | unsigned long get_max_files(void) |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 71 | { |
| 72 | return files_stat.max_files; |
| 73 | } |
| 74 | EXPORT_SYMBOL_GPL(get_max_files); |
| 75 | |
| 76 | /* |
| 77 | * Handle nr_files sysctl |
| 78 | */ |
| 79 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) |
Joe Perches | 1f7e061 | 2014-06-06 14:38:05 -0700 | [diff] [blame] | 80 | int proc_nr_files(struct ctl_table *table, int write, |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 81 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 82 | { |
| 83 | files_stat.nr_files = get_nr_files(); |
Eric Dumazet | 518de9b | 2010-10-26 14:22:44 -0700 | [diff] [blame] | 84 | return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 85 | } |
| 86 | #else |
Joe Perches | 1f7e061 | 2014-06-06 14:38:05 -0700 | [diff] [blame] | 87 | int proc_nr_files(struct ctl_table *table, int write, |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 88 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 89 | { |
| 90 | return -ENOSYS; |
| 91 | } |
| 92 | #endif |
| 93 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 94 | /* Find an unused file structure and return a pointer to it. |
Al Viro | 1afc99b | 2013-02-14 20:41:04 -0500 | [diff] [blame] | 95 | * Returns an error pointer if some error happend e.g. we over file |
| 96 | * structures limit, run out of memory or operation is not permitted. |
Dave Hansen | 430e285 | 2008-02-15 14:37:26 -0800 | [diff] [blame] | 97 | * |
| 98 | * Be very careful using this. You are responsible for |
| 99 | * getting write access to any mount that you might assign |
| 100 | * to this filp, if it is opened for write. If this is not |
| 101 | * done, you will imbalance int the mount's writer count |
| 102 | * and a warning at __fput() time. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | */ |
| 104 | struct file *get_empty_filp(void) |
| 105 | { |
David Howells | 86a264a | 2008-11-14 10:39:18 +1100 | [diff] [blame] | 106 | const struct cred *cred = current_cred(); |
Eric Dumazet | 518de9b | 2010-10-26 14:22:44 -0700 | [diff] [blame] | 107 | static long old_max; |
Al Viro | 1afc99b | 2013-02-14 20:41:04 -0500 | [diff] [blame] | 108 | struct file *f; |
| 109 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | |
| 111 | /* |
| 112 | * Privileged users can go above max_files |
| 113 | */ |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 114 | 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 Zijlstra | 52d9f3b | 2007-10-16 23:25:44 -0700 | [diff] [blame] | 119 | if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files) |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 120 | goto over; |
| 121 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 122 | |
Denis Cheng | 4975e45 | 2007-10-16 23:26:19 -0700 | [diff] [blame] | 123 | f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL); |
Al Viro | 1afc99b | 2013-02-14 20:41:04 -0500 | [diff] [blame] | 124 | if (unlikely(!f)) |
| 125 | return ERR_PTR(-ENOMEM); |
Kirill Korotaev | af4d2ec | 2005-06-23 00:09:50 -0700 | [diff] [blame] | 126 | |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 127 | percpu_counter_inc(&nr_files); |
Tetsuo Handa | 78d2978 | 2011-02-04 18:13:24 +0000 | [diff] [blame] | 128 | f->f_cred = get_cred(cred); |
Al Viro | 1afc99b | 2013-02-14 20:41:04 -0500 | [diff] [blame] | 129 | error = security_file_alloc(f); |
| 130 | if (unlikely(error)) { |
| 131 | file_free(f); |
| 132 | return ERR_PTR(error); |
| 133 | } |
Kirill Korotaev | af4d2ec | 2005-06-23 00:09:50 -0700 | [diff] [blame] | 134 | |
Al Viro | 516e0cc | 2008-07-26 00:39:17 -0400 | [diff] [blame] | 135 | atomic_long_set(&f->f_count, 1); |
Benjamin LaHaise | 5a6b795 | 2006-03-23 03:01:03 -0800 | [diff] [blame] | 136 | rwlock_init(&f->f_owner.lock); |
Jonathan Corbet | 6849991 | 2009-02-06 13:52:43 -0700 | [diff] [blame] | 137 | spin_lock_init(&f->f_lock); |
Linus Torvalds | 9c225f2 | 2014-03-03 09:36:58 -0800 | [diff] [blame] | 138 | mutex_init(&f->f_pos_lock); |
Benjamin LaHaise | 5a6b795 | 2006-03-23 03:01:03 -0800 | [diff] [blame] | 139 | eventpoll_init_file(f); |
| 140 | /* f->f_version: 0 */ |
Kirill Korotaev | af4d2ec | 2005-06-23 00:09:50 -0700 | [diff] [blame] | 141 | return f; |
| 142 | |
| 143 | over: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 144 | /* Ran out of filps - report that */ |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 145 | if (get_nr_files() > old_max) { |
Eric Dumazet | 518de9b | 2010-10-26 14:22:44 -0700 | [diff] [blame] | 146 | pr_info("VFS: file-max limit %lu reached\n", get_max_files()); |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 147 | old_max = get_nr_files(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 148 | } |
Al Viro | 1afc99b | 2013-02-14 20:41:04 -0500 | [diff] [blame] | 149 | return ERR_PTR(-ENFILE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 150 | } |
| 151 | |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 152 | /** |
| 153 | * alloc_file - allocate and initialize a 'struct file' |
Eric Biggers | a457606 | 2014-10-12 14:29:29 -0500 | [diff] [blame] | 154 | * |
| 155 | * @path: the (dentry, vfsmount) pair for the new file |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 156 | * @mode: the mode with which the new file will be opened |
| 157 | * @fop: the 'struct file_operations' for the new file |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 158 | */ |
Al Viro | a4141d7 | 2016-11-20 20:28:12 -0500 | [diff] [blame] | 159 | struct file *alloc_file(const struct path *path, fmode_t mode, |
Al Viro | 2c48b9c | 2009-08-09 00:52:35 +0400 | [diff] [blame] | 160 | const struct file_operations *fop) |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 161 | { |
| 162 | struct file *file; |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 163 | |
| 164 | file = get_empty_filp(); |
Al Viro | 1afc99b | 2013-02-14 20:41:04 -0500 | [diff] [blame] | 165 | if (IS_ERR(file)) |
Anatol Pomozov | 39b6525 | 2012-09-12 20:11:55 -0700 | [diff] [blame] | 166 | return file; |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 167 | |
Al Viro | 2c48b9c | 2009-08-09 00:52:35 +0400 | [diff] [blame] | 168 | file->f_path = *path; |
Al Viro | dd37978 | 2013-03-01 19:48:30 -0500 | [diff] [blame] | 169 | file->f_inode = path->dentry->d_inode; |
Al Viro | 2c48b9c | 2009-08-09 00:52:35 +0400 | [diff] [blame] | 170 | file->f_mapping = path->dentry->d_inode->i_mapping; |
Jeff Layton | 5660e13 | 2017-07-06 07:02:25 -0400 | [diff] [blame] | 171 | file->f_wb_err = filemap_sample_wb_err(file->f_mapping); |
Al Viro | 293bc98 | 2014-02-11 18:37:41 -0500 | [diff] [blame] | 172 | if ((mode & FMODE_READ) && |
Al Viro | 8436318 | 2015-04-04 01:14:53 -0400 | [diff] [blame] | 173 | likely(fop->read || fop->read_iter)) |
Al Viro | 7f7f25e | 2014-02-11 17:49:24 -0500 | [diff] [blame] | 174 | mode |= FMODE_CAN_READ; |
Al Viro | 293bc98 | 2014-02-11 18:37:41 -0500 | [diff] [blame] | 175 | if ((mode & FMODE_WRITE) && |
Al Viro | 8436318 | 2015-04-04 01:14:53 -0400 | [diff] [blame] | 176 | likely(fop->write || fop->write_iter)) |
Al Viro | 7f7f25e | 2014-02-11 17:49:24 -0500 | [diff] [blame] | 177 | mode |= FMODE_CAN_WRITE; |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 178 | file->f_mode = mode; |
| 179 | file->f_op = fop; |
Mimi Zohar | 890275b5 | 2010-11-02 10:13:07 -0400 | [diff] [blame] | 180 | if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) |
| 181 | i_readcount_inc(path->dentry->d_inode); |
Al Viro | 3d1e463 | 2009-08-08 23:56:29 +0400 | [diff] [blame] | 182 | return file; |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 183 | } |
Roland Dreier | 73efc46 | 2009-12-16 12:43:11 -0800 | [diff] [blame] | 184 | EXPORT_SYMBOL(alloc_file); |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 185 | |
Al Viro | d7065da | 2010-05-26 15:13:55 -0400 | [diff] [blame] | 186 | /* the real guts of fput() - releasing the last reference to file |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 187 | */ |
Al Viro | d7065da | 2010-05-26 15:13:55 -0400 | [diff] [blame] | 188 | static void __fput(struct file *file) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 189 | { |
Josef "Jeff" Sipek | 0f7fc9e | 2006-12-08 02:36:35 -0800 | [diff] [blame] | 190 | struct dentry *dentry = file->f_path.dentry; |
| 191 | struct vfsmount *mnt = file->f_path.mnt; |
David Howells | c77cece | 2013-06-13 23:37:49 +0100 | [diff] [blame] | 192 | struct inode *inode = file->f_inode; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | |
| 194 | might_sleep(); |
Robert Love | 0eeca28 | 2005-07-12 17:06:03 -0400 | [diff] [blame] | 195 | |
| 196 | fsnotify_close(file); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | /* |
| 198 | * The function eventpoll_release() should be the first called |
| 199 | * in the file cleanup chain. |
| 200 | */ |
| 201 | eventpoll_release(file); |
Jeff Layton | 78ed8a1 | 2014-02-03 12:13:08 -0500 | [diff] [blame] | 202 | locks_remove_file(file); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | |
Al Viro | 233e70f | 2008-10-31 23:28:30 +0000 | [diff] [blame] | 204 | if (unlikely(file->f_flags & FASYNC)) { |
Al Viro | 72c2d53 | 2013-09-22 16:27:52 -0400 | [diff] [blame] | 205 | if (file->f_op->fasync) |
Al Viro | 233e70f | 2008-10-31 23:28:30 +0000 | [diff] [blame] | 206 | file->f_op->fasync(-1, file, 0); |
| 207 | } |
Mimi Zohar | 4199d35 | 2011-03-16 22:48:43 -0400 | [diff] [blame] | 208 | ima_file_free(file); |
Al Viro | 72c2d53 | 2013-09-22 16:27:52 -0400 | [diff] [blame] | 209 | if (file->f_op->release) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 210 | file->f_op->release(inode, file); |
| 211 | security_file_free(file); |
Miklos Szeredi | 60ed8cf | 2011-03-16 18:17:54 +0100 | [diff] [blame] | 212 | if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL && |
| 213 | !(file->f_mode & FMODE_PATH))) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | cdev_put(inode->i_cdev); |
Miklos Szeredi | 60ed8cf | 2011-03-16 18:17:54 +0100 | [diff] [blame] | 215 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 216 | fops_put(file->f_op); |
Eric W. Biederman | 609d7fa | 2006-10-02 02:17:15 -0700 | [diff] [blame] | 217 | put_pid(file->f_owner.pid); |
Mimi Zohar | 890275b5 | 2010-11-02 10:13:07 -0400 | [diff] [blame] | 218 | if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) |
| 219 | i_readcount_dec(inode); |
Al Viro | 83f936c | 2014-03-14 12:02:47 -0400 | [diff] [blame] | 220 | if (file->f_mode & FMODE_WRITER) { |
| 221 | put_write_access(inode); |
| 222 | __mnt_drop_write(mnt); |
| 223 | } |
Josef "Jeff" Sipek | 0f7fc9e | 2006-12-08 02:36:35 -0800 | [diff] [blame] | 224 | file->f_path.dentry = NULL; |
| 225 | file->f_path.mnt = NULL; |
Al Viro | dd37978 | 2013-03-01 19:48:30 -0500 | [diff] [blame] | 226 | file->f_inode = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 227 | file_free(file); |
| 228 | dput(dentry); |
| 229 | mntput(mnt); |
| 230 | } |
| 231 | |
Oleg Nesterov | 4f5e65a | 2013-07-08 14:24:16 -0700 | [diff] [blame] | 232 | static LLIST_HEAD(delayed_fput_list); |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 233 | static void delayed_fput(struct work_struct *unused) |
| 234 | { |
Oleg Nesterov | 4f5e65a | 2013-07-08 14:24:16 -0700 | [diff] [blame] | 235 | struct llist_node *node = llist_del_all(&delayed_fput_list); |
| 236 | struct llist_node *next; |
| 237 | |
| 238 | for (; node; node = next) { |
| 239 | next = llist_next(node); |
| 240 | __fput(llist_entry(node, struct file, f_u.fu_llist)); |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 241 | } |
| 242 | } |
| 243 | |
| 244 | static void ____fput(struct callback_head *work) |
| 245 | { |
| 246 | __fput(container_of(work, struct file, f_u.fu_rcuhead)); |
| 247 | } |
| 248 | |
| 249 | /* |
| 250 | * If kernel thread really needs to have the final fput() it has done |
| 251 | * to complete, call this. The only user right now is the boot - we |
| 252 | * *do* need to make sure our writes to binaries on initramfs has |
| 253 | * not left us with opened struct file waiting for __fput() - execve() |
| 254 | * won't work without that. Please, don't add more callers without |
| 255 | * very good reasons; in particular, never call that with locks |
| 256 | * held and never call that from a thread that might need to do |
| 257 | * some work on any kind of umount. |
| 258 | */ |
| 259 | void flush_delayed_fput(void) |
| 260 | { |
| 261 | delayed_fput(NULL); |
| 262 | } |
| 263 | |
Al Viro | c7314d7 | 2013-10-20 08:44:39 -0400 | [diff] [blame] | 264 | static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 265 | |
Al Viro | d7065da | 2010-05-26 15:13:55 -0400 | [diff] [blame] | 266 | void fput(struct file *file) |
| 267 | { |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 268 | if (atomic_long_dec_and_test(&file->f_count)) { |
| 269 | struct task_struct *task = current; |
Oleg Nesterov | e7b2c40 | 2013-06-14 21:09:47 +0200 | [diff] [blame] | 270 | |
Oleg Nesterov | e7b2c40 | 2013-06-14 21:09:47 +0200 | [diff] [blame] | 271 | if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) { |
| 272 | init_task_work(&file->f_u.fu_rcuhead, ____fput); |
| 273 | if (!task_work_add(task, &file->f_u.fu_rcuhead, true)) |
| 274 | return; |
Andrew Morton | 6437250 | 2013-07-08 14:24:15 -0700 | [diff] [blame] | 275 | /* |
| 276 | * After this task has run exit_task_work(), |
Andrew Morton | be49b30 | 2013-09-11 14:24:34 -0700 | [diff] [blame] | 277 | * task_work_add() will fail. Fall through to delayed |
Andrew Morton | 6437250 | 2013-07-08 14:24:15 -0700 | [diff] [blame] | 278 | * fput to avoid leaking *file. |
| 279 | */ |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 280 | } |
Oleg Nesterov | 4f5e65a | 2013-07-08 14:24:16 -0700 | [diff] [blame] | 281 | |
| 282 | if (llist_add(&file->f_u.fu_llist, &delayed_fput_list)) |
Al Viro | c7314d7 | 2013-10-20 08:44:39 -0400 | [diff] [blame] | 283 | schedule_delayed_work(&delayed_fput_work, 1); |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 284 | } |
| 285 | } |
| 286 | |
| 287 | /* |
| 288 | * synchronous analog of fput(); for kernel threads that might be needed |
| 289 | * in some umount() (and thus can't use flush_delayed_fput() without |
| 290 | * risking deadlocks), need to wait for completion of __fput() and know |
| 291 | * for this specific struct file it won't involve anything that would |
| 292 | * need them. Use only if you really need it - at the very least, |
| 293 | * don't blindly convert fput() by kernel thread to that. |
| 294 | */ |
| 295 | void __fput_sync(struct file *file) |
| 296 | { |
| 297 | if (atomic_long_dec_and_test(&file->f_count)) { |
| 298 | struct task_struct *task = current; |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 299 | BUG_ON(!(task->flags & PF_KTHREAD)); |
Al Viro | d7065da | 2010-05-26 15:13:55 -0400 | [diff] [blame] | 300 | __fput(file); |
Al Viro | 4a9d4b0 | 2012-06-24 09:56:45 +0400 | [diff] [blame] | 301 | } |
Al Viro | d7065da | 2010-05-26 15:13:55 -0400 | [diff] [blame] | 302 | } |
| 303 | |
| 304 | EXPORT_SYMBOL(fput); |
| 305 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 306 | void put_filp(struct file *file) |
| 307 | { |
Al Viro | 516e0cc | 2008-07-26 00:39:17 -0400 | [diff] [blame] | 308 | if (atomic_long_dec_and_test(&file->f_count)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 309 | security_file_free(file); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 310 | file_free(file); |
| 311 | } |
| 312 | } |
| 313 | |
Mel Gorman | 4248b0d | 2015-08-06 15:46:20 -0700 | [diff] [blame] | 314 | void __init files_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 315 | { |
Eric Dumazet | b6b3fde | 2008-12-10 09:35:45 -0800 | [diff] [blame] | 316 | filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, |
| 317 | SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
Tejun Heo | 908c7f1 | 2014-09-08 09:51:29 +0900 | [diff] [blame] | 318 | percpu_counter_init(&nr_files, 0, GFP_KERNEL); |
Mel Gorman | 4248b0d | 2015-08-06 15:46:20 -0700 | [diff] [blame] | 319 | } |
| 320 | |
| 321 | /* |
| 322 | * One file with associated inode and dcache is very roughly 1K. Per default |
| 323 | * do not use more than 10% of our memory for files. |
| 324 | */ |
| 325 | void __init files_maxfiles_init(void) |
| 326 | { |
| 327 | unsigned long n; |
| 328 | unsigned long memreserve = (totalram_pages - nr_free_pages()) * 3/2; |
| 329 | |
| 330 | memreserve = min(memreserve, totalram_pages - 1); |
| 331 | n = ((totalram_pages - memreserve) * (PAGE_SIZE / 1024)) / 10; |
| 332 | |
| 333 | files_stat.max_files = max_t(unsigned long, n, NR_FILE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 334 | } |