/*
* linux/fs/file_table.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
*/
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/eventpoll.h>
#include <linux/mount.h>
#include <linux/cdev.h>
/* sysctl tunables... */
struct files_stat_struct files_stat = {
.max_files = NR_FILE
};
EXPORT_SYMBOL(files_stat); /* Needed by unix.o */
/* public. Not pretty! */
__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
static DEFINE_SPINLOCK(filp_count_lock);
/* slab constructors and destructors are called from arbitrary
* context and must be fully threaded - use a local spinlock
* to protect files_stat.nr_files
*/
void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags)
{
if ((cflags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
SLAB_CTOR_CONSTRUCTOR) {
unsigned long flags;
spin_lock_irqsave(&filp_count_lock, flags);
files_stat.nr_files++;
spin_unlock_irqrestore(&filp_count_lock, flags);
}
}
void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags)
{
unsigned long flags;
spin_lock_irqsave(&filp_count_lock, flags);
files_stat.nr_files--;
spin_unlock_irqrestore(&filp_count_lock, flags);
}
static inline void file_free(struct file *f)
{
kmem_cache_free(filp_cachep, f);
}
/* Find an unused file structure and return a pointer to it.
* Returns NULL, if there are no more free file structures or
* we run out of memory.
*/
struct file *get_empty_filp(void)
{
static int old_max;
struct file * f;
/*
* Privileged users can go above max_files
*/
if (files_stat.nr_files < files_stat.max_files ||
capable(CAP_SYS_ADMIN)) {
f = kmem_cache_alloc(filp_cachep, GFP_KERNEL);
if (f) {
memset(f, 0, sizeof(*f));
if (security_file_alloc(f)) {
file_free(f);
goto fail;
}
eventpoll_init_file(f);
atomic_set(&f->f_count, 1);
f->f_uid = current->fsuid;
f->f_gid = current->fsgid;
rwlock_init(&f->f_owner.lock);
/* f->f_version: 0 */
INIT_LIST_HEAD(&f->f_list);
f->f_maxcount = INT_MAX;
return f;
}
}
/* Ran out of filps - report that */
if (files_stat.max_files >= old_max) {
printk(KERN_INFO "VFS: file-max limit %d reached\n",
files_stat.max_files);
old_max = files_stat.max_files;
} else {
/* Big problems... */
printk(KERN_WARNING "VFS: filp allocation failed\n");
}
fail:
return NULL;
}
EXPORT_SYMBOL(get_empty_filp);
void fastcall fput(struct file *file)
{
if (atomic_dec_and_test(&file->f_count))
__fput(file);
}
EXPORT_SYMBOL(fput);
/* __fput is called from task context when aio completion releases the last
* last use of a struct file *. Do not use otherwise.
*/
void fastcall __fput(struct file *file)
{
struct dentry *dentry = file->f_dentry;
struct vfsmount *mnt = file->f_vfsmnt;
struct inode *inode = dentry->d_inode;
might_sleep();
/*
* The function eventpoll_release() should be the first called
* in the file cleanup chain.
*/
eventpoll_release(file);
locks_remove_flock(file);
if (file->f_op && file->f_op->release)
file->f_op->release(inode, file);
security_file_free(file);
if (unlikely(inode->i_cdev != NULL))
cdev_put(inode->i_cdev);
fops_put(file->f_op);
if (file->f_mode & FMODE_WRITE)
put_write_access(inode);
file_kill(file);
file->f_dentry = NULL;
file->f_vfsmnt = NULL;
file_free(file);
dput(dentry);
mntput(mnt);
}
struct file fastcall *fget(unsigned int fd)
{
struct file *file;
struct files_struct *files = current->files;
spin_lock(&files->file_lock);
file = fcheck_files(files, fd);
if (file)
get_file(file);
spin_unlock(&files->file_lock);
return file;
}
EXPORT_SYMBOL(fget);
/*
* Lightweight file lookup - no refcnt increment if fd table isn't shared.
* You can use this only if it is guranteed that the current task already
* holds a refcnt to that file. That check has to be done at fget() only
* and a flag is returned to be passed to the corresponding fput_light().
* There must not be a cloning between an fget_light/fput_light pair.
*/
struct file fastcall *fget_light(unsigned int fd, int *fput_needed)
{
struct file *file;
struct files_struct *files = current->files;
*fput_needed = 0;
if (likely((atomic_read(&files->count) == 1))) {
file = fcheck_files(files, fd);
} else {
spin_lock(&files->file_lock);
file = fcheck_files(files, fd);
if (file) {
get_file(file);
*fput_needed = 1;
}
spin_unlock(&files->file_lock);
}
return file;
}
void put_filp(struct file *file)
{
if (atomic_dec_and_test(&file->f_count)) {
security_file_free(file);
file_kill(file);
file_free(file);
}
}
void file_move(struct file *file, struct list_head *list)
{
if (!list)
return;
file_list_lock();
list_move(&file->f_list, list);
file_list_unlock();
}
void file_kill(struct file *file)
{
if (!list_empty(&file->f_list)) {
file_list_lock();
list_del_init(&file->f_list);
file_list_unlock();
}
}
int fs_may_remount_ro(struct super_block *sb)
{
struct list_head *p;
/* Check that no files are currently opened for writing. */
file_list_lock();
list_for_each(p, &sb->s_files) {
struct file *file = list_entry(p, struct file, f_list);
struct inode *inode = file->f_dentry->d_inode;
/* File with pending delete? */
if (inode->i_nlink == 0)
goto too_bad;
/* Writeable file? */
if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
goto too_bad;
}
file_list_unlock();
return 1; /* Tis' cool bro. */
too_bad:
file_list_unlock();
return 0;
}
void __init files_init(unsigned long mempages)
{
int n;
/* One file with associated inode and dcache is very roughly 1K.
* Per default don't use more than 10% of our memory for files.
*/
n = (mempages * (PAGE_SIZE / 1024)) / 10;
files_stat.max_files = n;
if (files_stat.max_files < NR_FILE)
files_stat.max_files = NR_FILE;
}
