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> |
| 16 | #include <linux/eventpoll.h> |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 17 | #include <linux/rcupdate.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | #include <linux/mount.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 19 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | #include <linux/cdev.h> |
Robert Love | 0eeca28 | 2005-07-12 17:06:03 -0400 | [diff] [blame] | 21 | #include <linux/fsnotify.h> |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 22 | #include <linux/sysctl.h> |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 23 | #include <linux/lglock.h> |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 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 | 0552f87 | 2009-12-16 04:53:03 -0500 | [diff] [blame] | 26 | #include <linux/ima.h> |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 27 | |
Arun Sharma | 60063497 | 2011-07-26 16:09:06 -0700 | [diff] [blame] | 28 | #include <linux/atomic.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | |
Eric Paris | e81e3f4 | 2009-12-04 15:47:36 -0500 | [diff] [blame] | 30 | #include "internal.h" |
| 31 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | /* sysctl tunables... */ |
| 33 | struct files_stat_struct files_stat = { |
| 34 | .max_files = NR_FILE |
| 35 | }; |
| 36 | |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 37 | DEFINE_LGLOCK(files_lglock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | |
Eric Dumazet | b6b3fde | 2008-12-10 09:35:45 -0800 | [diff] [blame] | 39 | /* SLAB cache for file structures */ |
| 40 | static struct kmem_cache *filp_cachep __read_mostly; |
| 41 | |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 42 | static struct percpu_counter nr_files __cacheline_aligned_in_smp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 44 | static inline void file_free_rcu(struct rcu_head *head) |
| 45 | { |
David Howells | d76b0d9 | 2008-11-14 10:39:25 +1100 | [diff] [blame] | 46 | struct file *f = container_of(head, struct file, f_u.fu_rcuhead); |
| 47 | |
| 48 | put_cred(f->f_cred); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 49 | kmem_cache_free(filp_cachep, f); |
| 50 | } |
| 51 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | static inline void file_free(struct file *f) |
| 53 | { |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 54 | percpu_counter_dec(&nr_files); |
Dave Hansen | ad775f5 | 2008-02-15 14:38:01 -0800 | [diff] [blame] | 55 | file_check_state(f); |
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) |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 80 | int proc_nr_files(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 |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 87 | int proc_nr_files(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. |
| 95 | * Returns NULL, if there are no more free file structures or |
| 96 | * we run out of memory. |
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; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | struct file * f; |
| 109 | |
| 110 | /* |
| 111 | * Privileged users can go above max_files |
| 112 | */ |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 113 | if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) { |
| 114 | /* |
| 115 | * percpu_counters are inaccurate. Do an expensive check before |
| 116 | * we go and fail. |
| 117 | */ |
Peter Zijlstra | 52d9f3b | 2007-10-16 23:25:44 -0700 | [diff] [blame] | 118 | if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files) |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 119 | goto over; |
| 120 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 121 | |
Denis Cheng | 4975e45 | 2007-10-16 23:26:19 -0700 | [diff] [blame] | 122 | f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL); |
Kirill Korotaev | af4d2ec | 2005-06-23 00:09:50 -0700 | [diff] [blame] | 123 | if (f == NULL) |
| 124 | goto fail; |
| 125 | |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 126 | percpu_counter_inc(&nr_files); |
Tetsuo Handa | 78d2978 | 2011-02-04 18:13:24 +0000 | [diff] [blame] | 127 | f->f_cred = get_cred(cred); |
Kirill Korotaev | af4d2ec | 2005-06-23 00:09:50 -0700 | [diff] [blame] | 128 | if (security_file_alloc(f)) |
| 129 | goto fail_sec; |
| 130 | |
Eric Dumazet | 2f51201 | 2005-10-30 15:02:16 -0800 | [diff] [blame] | 131 | INIT_LIST_HEAD(&f->f_u.fu_list); |
Al Viro | 516e0cc | 2008-07-26 00:39:17 -0400 | [diff] [blame] | 132 | atomic_long_set(&f->f_count, 1); |
Benjamin LaHaise | 5a6b7951 | 2006-03-23 03:01:03 -0800 | [diff] [blame] | 133 | rwlock_init(&f->f_owner.lock); |
Jonathan Corbet | 6849991 | 2009-02-06 13:52:43 -0700 | [diff] [blame] | 134 | spin_lock_init(&f->f_lock); |
Benjamin LaHaise | 5a6b7951 | 2006-03-23 03:01:03 -0800 | [diff] [blame] | 135 | eventpoll_init_file(f); |
| 136 | /* f->f_version: 0 */ |
Kirill Korotaev | af4d2ec | 2005-06-23 00:09:50 -0700 | [diff] [blame] | 137 | return f; |
| 138 | |
| 139 | over: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | /* Ran out of filps - report that */ |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 141 | if (get_nr_files() > old_max) { |
Eric Dumazet | 518de9b | 2010-10-26 14:22:44 -0700 | [diff] [blame] | 142 | pr_info("VFS: file-max limit %lu reached\n", get_max_files()); |
Dipankar Sarma | 529bf6b | 2006-03-07 21:55:35 -0800 | [diff] [blame] | 143 | old_max = get_nr_files(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 144 | } |
Kirill Korotaev | af4d2ec | 2005-06-23 00:09:50 -0700 | [diff] [blame] | 145 | goto fail; |
| 146 | |
| 147 | fail_sec: |
| 148 | file_free(f); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 149 | fail: |
| 150 | return NULL; |
| 151 | } |
| 152 | |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 153 | /** |
| 154 | * alloc_file - allocate and initialize a 'struct file' |
| 155 | * @mnt: the vfsmount on which the file will reside |
| 156 | * @dentry: the dentry representing the new file |
| 157 | * @mode: the mode with which the new file will be opened |
| 158 | * @fop: the 'struct file_operations' for the new file |
| 159 | * |
| 160 | * Use this instead of get_empty_filp() to get a new |
| 161 | * 'struct file'. Do so because of the same initialization |
| 162 | * pitfalls reasons listed for init_file(). This is a |
| 163 | * preferred interface to using init_file(). |
| 164 | * |
| 165 | * If all the callers of init_file() are eliminated, its |
| 166 | * code should be moved into this function. |
| 167 | */ |
Al Viro | 2c48b9c | 2009-08-09 00:52:35 +0400 | [diff] [blame] | 168 | struct file *alloc_file(struct path *path, fmode_t mode, |
| 169 | const struct file_operations *fop) |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 170 | { |
| 171 | struct file *file; |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 172 | |
| 173 | file = get_empty_filp(); |
| 174 | if (!file) |
| 175 | return NULL; |
| 176 | |
Al Viro | 2c48b9c | 2009-08-09 00:52:35 +0400 | [diff] [blame] | 177 | file->f_path = *path; |
| 178 | file->f_mapping = path->dentry->d_inode->i_mapping; |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 179 | file->f_mode = mode; |
| 180 | file->f_op = fop; |
Dave Hansen | 4a3fd21 | 2008-02-15 14:37:48 -0800 | [diff] [blame] | 181 | |
| 182 | /* |
| 183 | * These mounts don't really matter in practice |
| 184 | * for r/o bind mounts. They aren't userspace- |
| 185 | * visible. We do this for consistency, and so |
| 186 | * that we can do debugging checks at __fput() |
| 187 | */ |
Al Viro | 2c48b9c | 2009-08-09 00:52:35 +0400 | [diff] [blame] | 188 | if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) { |
Dave Hansen | ad775f5 | 2008-02-15 14:38:01 -0800 | [diff] [blame] | 189 | file_take_write(file); |
Roland Dreier | 385e3ed | 2009-12-16 12:48:44 -0800 | [diff] [blame] | 190 | WARN_ON(mnt_clone_write(path->mnt)); |
Dave Hansen | 4a3fd21 | 2008-02-15 14:37:48 -0800 | [diff] [blame] | 191 | } |
Mimi Zohar | 890275b5 | 2010-11-02 10:13:07 -0400 | [diff] [blame] | 192 | if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) |
| 193 | i_readcount_inc(path->dentry->d_inode); |
Al Viro | 3d1e463 | 2009-08-08 23:56:29 +0400 | [diff] [blame] | 194 | return file; |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 195 | } |
Roland Dreier | 73efc46 | 2009-12-16 12:43:11 -0800 | [diff] [blame] | 196 | EXPORT_SYMBOL(alloc_file); |
Dave Hansen | ce8d2cd | 2007-10-16 23:31:13 -0700 | [diff] [blame] | 197 | |
Dave Hansen | aceaf78 | 2008-02-15 14:37:31 -0800 | [diff] [blame] | 198 | /** |
| 199 | * drop_file_write_access - give up ability to write to a file |
| 200 | * @file: the file to which we will stop writing |
| 201 | * |
| 202 | * This is a central place which will give up the ability |
| 203 | * to write to @file, along with access to write through |
| 204 | * its vfsmount. |
| 205 | */ |
Al Viro | b57ce96 | 2012-02-12 02:38:16 -0500 | [diff] [blame] | 206 | static void drop_file_write_access(struct file *file) |
Dave Hansen | aceaf78 | 2008-02-15 14:37:31 -0800 | [diff] [blame] | 207 | { |
Dave Hansen | 4a3fd21 | 2008-02-15 14:37:48 -0800 | [diff] [blame] | 208 | struct vfsmount *mnt = file->f_path.mnt; |
Dave Hansen | aceaf78 | 2008-02-15 14:37:31 -0800 | [diff] [blame] | 209 | struct dentry *dentry = file->f_path.dentry; |
| 210 | struct inode *inode = dentry->d_inode; |
| 211 | |
| 212 | put_write_access(inode); |
Dave Hansen | ad775f5 | 2008-02-15 14:38:01 -0800 | [diff] [blame] | 213 | |
| 214 | if (special_file(inode->i_mode)) |
| 215 | return; |
| 216 | if (file_check_writeable(file) != 0) |
| 217 | return; |
| 218 | mnt_drop_write(mnt); |
| 219 | file_release_write(file); |
Dave Hansen | aceaf78 | 2008-02-15 14:37:31 -0800 | [diff] [blame] | 220 | } |
Dave Hansen | aceaf78 | 2008-02-15 14:37:31 -0800 | [diff] [blame] | 221 | |
Al Viro | d7065da | 2010-05-26 15:13:55 -0400 | [diff] [blame] | 222 | /* the real guts of fput() - releasing the last reference to file |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 223 | */ |
Al Viro | d7065da | 2010-05-26 15:13:55 -0400 | [diff] [blame] | 224 | static void __fput(struct file *file) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 225 | { |
Josef "Jeff" Sipek | 0f7fc9e | 2006-12-08 02:36:35 -0800 | [diff] [blame] | 226 | struct dentry *dentry = file->f_path.dentry; |
| 227 | struct vfsmount *mnt = file->f_path.mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 228 | struct inode *inode = dentry->d_inode; |
| 229 | |
| 230 | might_sleep(); |
Robert Love | 0eeca28 | 2005-07-12 17:06:03 -0400 | [diff] [blame] | 231 | |
| 232 | fsnotify_close(file); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 233 | /* |
| 234 | * The function eventpoll_release() should be the first called |
| 235 | * in the file cleanup chain. |
| 236 | */ |
| 237 | eventpoll_release(file); |
| 238 | locks_remove_flock(file); |
| 239 | |
Al Viro | 233e70f | 2008-10-31 23:28:30 +0000 | [diff] [blame] | 240 | if (unlikely(file->f_flags & FASYNC)) { |
| 241 | if (file->f_op && file->f_op->fasync) |
| 242 | file->f_op->fasync(-1, file, 0); |
| 243 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 244 | if (file->f_op && file->f_op->release) |
| 245 | file->f_op->release(inode, file); |
| 246 | security_file_free(file); |
Al Viro | 89068c5 | 2010-02-07 03:07:29 -0500 | [diff] [blame] | 247 | ima_file_free(file); |
Miklos Szeredi | 60ed8cf | 2011-03-16 18:17:54 +0100 | [diff] [blame] | 248 | if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL && |
| 249 | !(file->f_mode & FMODE_PATH))) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 250 | cdev_put(inode->i_cdev); |
Miklos Szeredi | 60ed8cf | 2011-03-16 18:17:54 +0100 | [diff] [blame] | 251 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 252 | fops_put(file->f_op); |
Eric W. Biederman | 609d7fa | 2006-10-02 02:17:15 -0700 | [diff] [blame] | 253 | put_pid(file->f_owner.pid); |
Nick Piggin | ee2ffa0 | 2010-08-18 04:37:35 +1000 | [diff] [blame] | 254 | file_sb_list_del(file); |
Mimi Zohar | 890275b5 | 2010-11-02 10:13:07 -0400 | [diff] [blame] | 255 | if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) |
| 256 | i_readcount_dec(inode); |
Dave Hansen | aceaf78 | 2008-02-15 14:37:31 -0800 | [diff] [blame] | 257 | if (file->f_mode & FMODE_WRITE) |
| 258 | drop_file_write_access(file); |
Josef "Jeff" Sipek | 0f7fc9e | 2006-12-08 02:36:35 -0800 | [diff] [blame] | 259 | file->f_path.dentry = NULL; |
| 260 | file->f_path.mnt = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 261 | file_free(file); |
| 262 | dput(dentry); |
| 263 | mntput(mnt); |
| 264 | } |
| 265 | |
Al Viro | d7065da | 2010-05-26 15:13:55 -0400 | [diff] [blame] | 266 | void fput(struct file *file) |
| 267 | { |
| 268 | if (atomic_long_dec_and_test(&file->f_count)) |
| 269 | __fput(file); |
| 270 | } |
| 271 | |
| 272 | EXPORT_SYMBOL(fput); |
| 273 | |
Harvey Harrison | fc9b52c | 2008-02-08 04:19:52 -0800 | [diff] [blame] | 274 | struct file *fget(unsigned int fd) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 275 | { |
| 276 | struct file *file; |
| 277 | struct files_struct *files = current->files; |
| 278 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 279 | rcu_read_lock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 280 | file = fcheck_files(files, fd); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 281 | if (file) { |
Al Viro | 1abf0c7 | 2011-03-13 03:51:11 -0400 | [diff] [blame] | 282 | /* File object ref couldn't be taken */ |
| 283 | if (file->f_mode & FMODE_PATH || |
| 284 | !atomic_long_inc_not_zero(&file->f_count)) |
| 285 | file = NULL; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 286 | } |
| 287 | rcu_read_unlock(); |
| 288 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 289 | return file; |
| 290 | } |
| 291 | |
| 292 | EXPORT_SYMBOL(fget); |
| 293 | |
Al Viro | 1abf0c7 | 2011-03-13 03:51:11 -0400 | [diff] [blame] | 294 | struct file *fget_raw(unsigned int fd) |
| 295 | { |
| 296 | struct file *file; |
| 297 | struct files_struct *files = current->files; |
| 298 | |
| 299 | rcu_read_lock(); |
| 300 | file = fcheck_files(files, fd); |
| 301 | if (file) { |
| 302 | /* File object ref couldn't be taken */ |
| 303 | if (!atomic_long_inc_not_zero(&file->f_count)) |
| 304 | file = NULL; |
| 305 | } |
| 306 | rcu_read_unlock(); |
| 307 | |
| 308 | return file; |
| 309 | } |
| 310 | |
Al Viro | 326be7b | 2011-03-13 17:08:22 -0400 | [diff] [blame] | 311 | EXPORT_SYMBOL(fget_raw); |
| 312 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 313 | /* |
Tony Battersby | 5893947 | 2010-08-10 18:01:29 -0700 | [diff] [blame] | 314 | * Lightweight file lookup - no refcnt increment if fd table isn't shared. |
| 315 | * |
| 316 | * You can use this instead of fget if you satisfy all of the following |
| 317 | * conditions: |
| 318 | * 1) You must call fput_light before exiting the syscall and returning control |
| 319 | * to userspace (i.e. you cannot remember the returned struct file * after |
| 320 | * returning to userspace). |
| 321 | * 2) You must not call filp_close on the returned struct file * in between |
| 322 | * calls to fget_light and fput_light. |
| 323 | * 3) You must not clone the current task in between the calls to fget_light |
| 324 | * and fput_light. |
| 325 | * |
| 326 | * The fput_needed flag returned by fget_light should be passed to the |
| 327 | * corresponding fput_light. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 328 | */ |
Harvey Harrison | fc9b52c | 2008-02-08 04:19:52 -0800 | [diff] [blame] | 329 | struct file *fget_light(unsigned int fd, int *fput_needed) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 330 | { |
| 331 | struct file *file; |
| 332 | struct files_struct *files = current->files; |
| 333 | |
| 334 | *fput_needed = 0; |
Steven Rostedt | 3bc0ba4 | 2010-12-13 19:38:09 -0500 | [diff] [blame] | 335 | if (atomic_read(&files->count) == 1) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 336 | file = fcheck_files(files, fd); |
Al Viro | 1abf0c7 | 2011-03-13 03:51:11 -0400 | [diff] [blame] | 337 | if (file && (file->f_mode & FMODE_PATH)) |
| 338 | file = NULL; |
| 339 | } else { |
| 340 | rcu_read_lock(); |
| 341 | file = fcheck_files(files, fd); |
| 342 | if (file) { |
| 343 | if (!(file->f_mode & FMODE_PATH) && |
| 344 | atomic_long_inc_not_zero(&file->f_count)) |
| 345 | *fput_needed = 1; |
| 346 | else |
| 347 | /* Didn't get the reference, someone's freed */ |
| 348 | file = NULL; |
| 349 | } |
| 350 | rcu_read_unlock(); |
| 351 | } |
| 352 | |
| 353 | return file; |
| 354 | } |
| 355 | |
| 356 | struct file *fget_raw_light(unsigned int fd, int *fput_needed) |
| 357 | { |
| 358 | struct file *file; |
| 359 | struct files_struct *files = current->files; |
| 360 | |
| 361 | *fput_needed = 0; |
| 362 | if (atomic_read(&files->count) == 1) { |
| 363 | file = fcheck_files(files, fd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 364 | } else { |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 365 | rcu_read_lock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 366 | file = fcheck_files(files, fd); |
| 367 | if (file) { |
Al Viro | 516e0cc | 2008-07-26 00:39:17 -0400 | [diff] [blame] | 368 | if (atomic_long_inc_not_zero(&file->f_count)) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 369 | *fput_needed = 1; |
| 370 | else |
| 371 | /* Didn't get the reference, someone's freed */ |
| 372 | file = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 373 | } |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 374 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 375 | } |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 376 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 377 | return file; |
| 378 | } |
| 379 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 380 | void put_filp(struct file *file) |
| 381 | { |
Al Viro | 516e0cc | 2008-07-26 00:39:17 -0400 | [diff] [blame] | 382 | if (atomic_long_dec_and_test(&file->f_count)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 383 | security_file_free(file); |
Nick Piggin | ee2ffa0 | 2010-08-18 04:37:35 +1000 | [diff] [blame] | 384 | file_sb_list_del(file); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 385 | file_free(file); |
| 386 | } |
| 387 | } |
| 388 | |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 389 | static inline int file_list_cpu(struct file *file) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 390 | { |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 391 | #ifdef CONFIG_SMP |
| 392 | return file->f_sb_list_cpu; |
| 393 | #else |
| 394 | return smp_processor_id(); |
| 395 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 396 | } |
| 397 | |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 398 | /* helper for file_sb_list_add to reduce ifdefs */ |
| 399 | static inline void __file_sb_list_add(struct file *file, struct super_block *sb) |
| 400 | { |
| 401 | struct list_head *list; |
| 402 | #ifdef CONFIG_SMP |
| 403 | int cpu; |
| 404 | cpu = smp_processor_id(); |
| 405 | file->f_sb_list_cpu = cpu; |
| 406 | list = per_cpu_ptr(sb->s_files, cpu); |
| 407 | #else |
| 408 | list = &sb->s_files; |
| 409 | #endif |
| 410 | list_add(&file->f_u.fu_list, list); |
| 411 | } |
| 412 | |
| 413 | /** |
| 414 | * file_sb_list_add - add a file to the sb's file list |
| 415 | * @file: file to add |
| 416 | * @sb: sb to add it to |
| 417 | * |
| 418 | * Use this function to associate a file with the superblock of the inode it |
| 419 | * refers to. |
| 420 | */ |
| 421 | void file_sb_list_add(struct file *file, struct super_block *sb) |
| 422 | { |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 423 | lg_local_lock(&files_lglock); |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 424 | __file_sb_list_add(file, sb); |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 425 | lg_local_unlock(&files_lglock); |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 426 | } |
| 427 | |
| 428 | /** |
| 429 | * file_sb_list_del - remove a file from the sb's file list |
| 430 | * @file: file to remove |
| 431 | * @sb: sb to remove it from |
| 432 | * |
| 433 | * Use this function to remove a file from its superblock. |
| 434 | */ |
Nick Piggin | ee2ffa0 | 2010-08-18 04:37:35 +1000 | [diff] [blame] | 435 | void file_sb_list_del(struct file *file) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 436 | { |
Eric Dumazet | 2f51201 | 2005-10-30 15:02:16 -0800 | [diff] [blame] | 437 | if (!list_empty(&file->f_u.fu_list)) { |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 438 | lg_local_lock_cpu(&files_lglock, file_list_cpu(file)); |
Eric Dumazet | 2f51201 | 2005-10-30 15:02:16 -0800 | [diff] [blame] | 439 | list_del_init(&file->f_u.fu_list); |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 440 | lg_local_unlock_cpu(&files_lglock, file_list_cpu(file)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 441 | } |
| 442 | } |
| 443 | |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 444 | #ifdef CONFIG_SMP |
| 445 | |
| 446 | /* |
| 447 | * These macros iterate all files on all CPUs for a given superblock. |
| 448 | * files_lglock must be held globally. |
| 449 | */ |
| 450 | #define do_file_list_for_each_entry(__sb, __file) \ |
| 451 | { \ |
| 452 | int i; \ |
| 453 | for_each_possible_cpu(i) { \ |
| 454 | struct list_head *list; \ |
| 455 | list = per_cpu_ptr((__sb)->s_files, i); \ |
| 456 | list_for_each_entry((__file), list, f_u.fu_list) |
| 457 | |
| 458 | #define while_file_list_for_each_entry \ |
| 459 | } \ |
| 460 | } |
| 461 | |
| 462 | #else |
| 463 | |
| 464 | #define do_file_list_for_each_entry(__sb, __file) \ |
| 465 | { \ |
| 466 | struct list_head *list; \ |
| 467 | list = &(sb)->s_files; \ |
| 468 | list_for_each_entry((__file), list, f_u.fu_list) |
| 469 | |
| 470 | #define while_file_list_for_each_entry \ |
| 471 | } |
| 472 | |
| 473 | #endif |
| 474 | |
npiggin@suse.de | 864d7c4 | 2009-04-26 20:25:56 +1000 | [diff] [blame] | 475 | /** |
| 476 | * mark_files_ro - mark all files read-only |
| 477 | * @sb: superblock in question |
| 478 | * |
| 479 | * All files are marked read-only. We don't care about pending |
| 480 | * delete files so this should be used in 'force' mode only. |
| 481 | */ |
| 482 | void mark_files_ro(struct super_block *sb) |
| 483 | { |
| 484 | struct file *f; |
| 485 | |
| 486 | retry: |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 487 | lg_global_lock(&files_lglock); |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 488 | do_file_list_for_each_entry(sb, f) { |
npiggin@suse.de | 864d7c4 | 2009-04-26 20:25:56 +1000 | [diff] [blame] | 489 | struct vfsmount *mnt; |
| 490 | if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) |
| 491 | continue; |
| 492 | if (!file_count(f)) |
| 493 | continue; |
| 494 | if (!(f->f_mode & FMODE_WRITE)) |
| 495 | continue; |
Wu Fengguang | 42e4960 | 2010-03-05 13:42:01 -0800 | [diff] [blame] | 496 | spin_lock(&f->f_lock); |
npiggin@suse.de | 864d7c4 | 2009-04-26 20:25:56 +1000 | [diff] [blame] | 497 | f->f_mode &= ~FMODE_WRITE; |
Wu Fengguang | 42e4960 | 2010-03-05 13:42:01 -0800 | [diff] [blame] | 498 | spin_unlock(&f->f_lock); |
npiggin@suse.de | 864d7c4 | 2009-04-26 20:25:56 +1000 | [diff] [blame] | 499 | if (file_check_writeable(f) != 0) |
| 500 | continue; |
| 501 | file_release_write(f); |
| 502 | mnt = mntget(f->f_path.mnt); |
Nick Piggin | ee2ffa0 | 2010-08-18 04:37:35 +1000 | [diff] [blame] | 503 | /* This can sleep, so we can't hold the spinlock. */ |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 504 | lg_global_unlock(&files_lglock); |
npiggin@suse.de | 864d7c4 | 2009-04-26 20:25:56 +1000 | [diff] [blame] | 505 | mnt_drop_write(mnt); |
| 506 | mntput(mnt); |
| 507 | goto retry; |
Nick Piggin | 6416ccb | 2010-08-18 04:37:38 +1000 | [diff] [blame] | 508 | } while_file_list_for_each_entry; |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 509 | lg_global_unlock(&files_lglock); |
npiggin@suse.de | 864d7c4 | 2009-04-26 20:25:56 +1000 | [diff] [blame] | 510 | } |
| 511 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 512 | void __init files_init(unsigned long mempages) |
| 513 | { |
Eric Dumazet | 518de9b | 2010-10-26 14:22:44 -0700 | [diff] [blame] | 514 | unsigned long n; |
Eric Dumazet | b6b3fde | 2008-12-10 09:35:45 -0800 | [diff] [blame] | 515 | |
| 516 | filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, |
| 517 | SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
| 518 | |
| 519 | /* |
| 520 | * One file with associated inode and dcache is very roughly 1K. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 521 | * Per default don't use more than 10% of our memory for files. |
| 522 | */ |
| 523 | |
| 524 | n = (mempages * (PAGE_SIZE / 1024)) / 10; |
Eric Dumazet | 518de9b | 2010-10-26 14:22:44 -0700 | [diff] [blame] | 525 | files_stat.max_files = max_t(unsigned long, n, NR_FILE); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 526 | files_defer_init(); |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 527 | lg_lock_init(&files_lglock, "files_lglock"); |
Mingming Cao | 0216bfc | 2006-06-23 02:05:41 -0700 | [diff] [blame] | 528 | percpu_counter_init(&nr_files, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 529 | } |