2 * linux/fs/file_table.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
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/smp_lock.h>
15 #include <linux/security.h>
16 #include <linux/eventpoll.h>
17 #include <linux/mount.h>
18 #include <linux/cdev.h>
19 #include <linux/vs_limit.h>
20 #include <linux/vs_context.h>
22 /* sysctl tunables... */
23 struct files_stat_struct files_stat = {
27 EXPORT_SYMBOL(files_stat); /* Needed by unix.o */
29 /* public. Not pretty! */
30 __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
32 static DEFINE_SPINLOCK(filp_count_lock);
34 /* slab constructors and destructors are called from arbitrary
35 * context and must be fully threaded - use a local spinlock
36 * to protect files_stat.nr_files
38 void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags)
40 if ((cflags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
41 SLAB_CTOR_CONSTRUCTOR) {
43 spin_lock_irqsave(&filp_count_lock, flags);
44 files_stat.nr_files++;
45 spin_unlock_irqrestore(&filp_count_lock, flags);
49 void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags)
52 spin_lock_irqsave(&filp_count_lock, flags);
53 files_stat.nr_files--;
54 spin_unlock_irqrestore(&filp_count_lock, flags);
57 static inline void file_free(struct file *f)
59 kmem_cache_free(filp_cachep, f);
62 /* Find an unused file structure and return a pointer to it.
63 * Returns NULL, if there are no more free file structures or
64 * we run out of memory.
66 struct file *get_empty_filp(void)
72 * Privileged users can go above max_files
74 if (files_stat.nr_files < files_stat.max_files ||
75 capable(CAP_SYS_ADMIN)) {
76 f = kmem_cache_alloc(filp_cachep, GFP_KERNEL);
78 memset(f, 0, sizeof(*f));
79 if (security_file_alloc(f)) {
83 eventpoll_init_file(f);
84 atomic_set(&f->f_count, 1);
85 f->f_uid = current->fsuid;
86 f->f_gid = current->fsgid;
87 rwlock_init(&f->f_owner.lock);
89 INIT_LIST_HEAD(&f->f_list);
90 // set_vx_info(&f->f_vx_info, current->vx_info);
91 f->f_xid = vx_current_xid();
93 f->f_maxcount = INT_MAX;
98 /* Ran out of filps - report that */
99 if (files_stat.max_files >= old_max) {
100 printk(KERN_INFO "VFS: file-max limit %d reached\n",
101 files_stat.max_files);
102 old_max = files_stat.max_files;
104 /* Big problems... */
105 printk(KERN_WARNING "VFS: filp allocation failed\n");
111 EXPORT_SYMBOL(get_empty_filp);
113 void fastcall fput(struct file *file)
115 if (atomic_dec_and_test(&file->f_count))
121 /* __fput is called from task context when aio completion releases the last
122 * last use of a struct file *. Do not use otherwise.
124 void fastcall __fput(struct file *file)
126 struct dentry *dentry = file->f_dentry;
127 struct vfsmount *mnt = file->f_vfsmnt;
128 struct inode *inode = dentry->d_inode;
132 * The function eventpoll_release() should be the first called
133 * in the file cleanup chain.
135 eventpoll_release(file);
136 locks_remove_flock(file);
138 if (file->f_op && file->f_op->release)
139 file->f_op->release(inode, file);
140 security_file_free(file);
141 if (unlikely(inode->i_cdev != NULL))
142 cdev_put(inode->i_cdev);
143 fops_put(file->f_op);
144 if (file->f_mode & FMODE_WRITE)
145 put_write_access(inode);
149 file->f_dentry = NULL;
150 file->f_vfsmnt = NULL;
156 struct file fastcall *fget(unsigned int fd)
159 struct files_struct *files = current->files;
161 spin_lock(&files->file_lock);
162 file = fcheck_files(files, fd);
165 spin_unlock(&files->file_lock);
172 * Lightweight file lookup - no refcnt increment if fd table isn't shared.
173 * You can use this only if it is guranteed that the current task already
174 * holds a refcnt to that file. That check has to be done at fget() only
175 * and a flag is returned to be passed to the corresponding fput_light().
176 * There must not be a cloning between an fget_light/fput_light pair.
178 struct file fastcall *fget_light(unsigned int fd, int *fput_needed)
181 struct files_struct *files = current->files;
184 if (likely((atomic_read(&files->count) == 1))) {
185 file = fcheck_files(files, fd);
187 spin_lock(&files->file_lock);
188 file = fcheck_files(files, fd);
193 spin_unlock(&files->file_lock);
199 void put_filp(struct file *file)
201 if (atomic_dec_and_test(&file->f_count)) {
202 security_file_free(file);
210 void file_move(struct file *file, struct list_head *list)
215 list_move(&file->f_list, list);
219 void file_kill(struct file *file)
221 if (!list_empty(&file->f_list)) {
223 list_del_init(&file->f_list);
228 int fs_may_remount_ro(struct super_block *sb)
232 /* Check that no files are currently opened for writing. */
234 list_for_each(p, &sb->s_files) {
235 struct file *file = list_entry(p, struct file, f_list);
236 struct inode *inode = file->f_dentry->d_inode;
238 /* File with pending delete? */
239 if (inode->i_nlink == 0)
242 /* Writeable file? */
243 if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
247 return 1; /* Tis' cool bro. */
253 void __init files_init(unsigned long mempages)
256 /* One file with associated inode and dcache is very roughly 1K.
257 * Per default don't use more than 10% of our memory for files.
260 n = (mempages * (PAGE_SIZE / 1024)) / 10;
261 files_stat.max_files = n;
262 if (files_stat.max_files < NR_FILE)
263 files_stat.max_files = NR_FILE;