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>
20 /* sysctl tunables... */
21 struct files_stat_struct files_stat = {
25 EXPORT_SYMBOL(files_stat); /* Needed by unix.o */
27 /* public *and* exported. Not pretty! */
28 spinlock_t __cacheline_aligned_in_smp files_lock = SPIN_LOCK_UNLOCKED;
30 EXPORT_SYMBOL(files_lock);
32 static spinlock_t filp_count_lock = SPIN_LOCK_UNLOCKED;
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 f->f_owner.lock = RW_LOCK_UNLOCKED;
89 INIT_LIST_HEAD(&f->f_list);
95 /* Ran out of filps - report that */
96 if (files_stat.max_files >= old_max) {
97 printk(KERN_INFO "VFS: file-max limit %d reached\n",
98 files_stat.max_files);
99 old_max = files_stat.max_files;
101 /* Big problems... */
102 printk(KERN_WARNING "VFS: filp allocation failed\n");
108 EXPORT_SYMBOL(get_empty_filp);
111 * Clear and initialize a (private) struct file for the given dentry,
112 * allocate the security structure, and call the open function (if any).
113 * The file should be released using close_private_file.
115 int open_private_file(struct file *filp, struct dentry *dentry, int flags)
118 memset(filp, 0, sizeof(*filp));
119 eventpoll_init_file(filp);
120 filp->f_flags = flags;
121 filp->f_mode = (flags+1) & O_ACCMODE;
122 atomic_set(&filp->f_count, 1);
123 filp->f_dentry = dentry;
124 filp->f_mapping = dentry->d_inode->i_mapping;
125 filp->f_uid = current->fsuid;
126 filp->f_gid = current->fsgid;
127 filp->f_op = dentry->d_inode->i_fop;
128 INIT_LIST_HEAD(&filp->f_list);
129 error = security_file_alloc(filp);
131 if (filp->f_op && filp->f_op->open) {
132 error = filp->f_op->open(dentry->d_inode, filp);
134 security_file_free(filp);
139 EXPORT_SYMBOL(open_private_file);
142 * Release a private file by calling the release function (if any) and
143 * freeing the security structure.
145 void close_private_file(struct file *file)
147 struct inode * inode = file->f_dentry->d_inode;
149 if (file->f_op && file->f_op->release)
150 file->f_op->release(inode, file);
151 security_file_free(file);
154 EXPORT_SYMBOL(close_private_file);
156 void fastcall fput(struct file *file)
158 if (atomic_dec_and_test(&file->f_count))
164 /* __fput is called from task context when aio completion releases the last
165 * last use of a struct file *. Do not use otherwise.
167 void fastcall __fput(struct file *file)
169 struct dentry *dentry = file->f_dentry;
170 struct vfsmount *mnt = file->f_vfsmnt;
171 struct inode *inode = dentry->d_inode;
174 * The function eventpoll_release() should be the first called
175 * in the file cleanup chain.
177 eventpoll_release(file);
178 locks_remove_flock(file);
180 if (file->f_op && file->f_op->release)
181 file->f_op->release(inode, file);
182 security_file_free(file);
183 if (unlikely(inode->i_cdev != NULL))
184 cdev_put(inode->i_cdev);
185 fops_put(file->f_op);
186 if (file->f_mode & FMODE_WRITE)
187 put_write_access(inode);
190 file->f_dentry = NULL;
191 file->f_vfsmnt = NULL;
197 struct file fastcall *fget(unsigned int fd)
200 struct files_struct *files = current->files;
202 spin_lock(&files->file_lock);
203 file = fcheck_files(files, fd);
206 spin_unlock(&files->file_lock);
213 * Lightweight file lookup - no refcnt increment if fd table isn't shared.
214 * You can use this only if it is guranteed that the current task already
215 * holds a refcnt to that file. That check has to be done at fget() only
216 * and a flag is returned to be passed to the corresponding fput_light().
217 * There must not be a cloning between an fget_light/fput_light pair.
219 struct file fastcall *fget_light(unsigned int fd, int *fput_needed)
222 struct files_struct *files = current->files;
225 if (likely((atomic_read(&files->count) == 1))) {
226 file = fcheck_files(files, fd);
228 spin_lock(&files->file_lock);
229 file = fcheck_files(files, fd);
234 spin_unlock(&files->file_lock);
240 void put_filp(struct file *file)
242 if (atomic_dec_and_test(&file->f_count)) {
243 security_file_free(file);
249 EXPORT_SYMBOL(put_filp);
251 void file_move(struct file *file, struct list_head *list)
256 list_move(&file->f_list, list);
260 void file_kill(struct file *file)
262 if (!list_empty(&file->f_list)) {
264 list_del_init(&file->f_list);
269 int fs_may_remount_ro(struct super_block *sb)
273 /* Check that no files are currently opened for writing. */
275 list_for_each(p, &sb->s_files) {
276 struct file *file = list_entry(p, struct file, f_list);
277 struct inode *inode = file->f_dentry->d_inode;
279 /* File with pending delete? */
280 if (inode->i_nlink == 0)
283 /* Writeable file? */
284 if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
288 return 1; /* Tis' cool bro. */
294 void __init files_init(unsigned long mempages)
297 /* One file with associated inode and dcache is very roughly 1K.
298 * Per default don't use more than 10% of our memory for files.
301 n = (mempages * (PAGE_SIZE / 1024)) / 10;
302 files_stat.max_files = n;
303 if (files_stat.max_files < NR_FILE)
304 files_stat.max_files = NR_FILE;