linux/fs/file_table.c
Mingming Cao 0216bfcffe [PATCH] percpu counter data type changes to suppport more than 2**31 ext3 free blocks counter
The percpu counter data type are changed in this set of patches to support
more users like ext3 who need more than 32 bit to store the free blocks
total in the filesystem.

- Generic perpcu counters data type changes.  The size of the global counter
  and local counter were explictly specified using s64 and s32.  The global
  counter is changed from long to s64, while the local counter is changed from
  long to s32, so we could avoid doing 64 bit update in most cases.

- Users of the percpu counters are updated to make use of the new
  percpu_counter_init() routine now taking an additional parameter to allow
  users to pass the initial value of the global counter.

Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 07:43:06 -07:00

304 lines
6.7 KiB
C

/*
* linux/fs/file_table.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
*/
#include <linux/config.h>
#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/rcupdate.h>
#include <linux/mount.h>
#include <linux/capability.h>
#include <linux/cdev.h>
#include <linux/fsnotify.h>
#include <linux/sysctl.h>
#include <linux/percpu_counter.h>
#include <asm/atomic.h>
/* sysctl tunables... */
struct files_stat_struct files_stat = {
.max_files = NR_FILE
};
/* public. Not pretty! */
__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
static struct percpu_counter nr_files __cacheline_aligned_in_smp;
static inline void file_free_rcu(struct rcu_head *head)
{
struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
kmem_cache_free(filp_cachep, f);
}
static inline void file_free(struct file *f)
{
percpu_counter_dec(&nr_files);
call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
}
/*
* Return the total number of open files in the system
*/
static int get_nr_files(void)
{
return percpu_counter_read_positive(&nr_files);
}
/*
* Return the maximum number of open files in the system
*/
int get_max_files(void)
{
return files_stat.max_files;
}
EXPORT_SYMBOL_GPL(get_max_files);
/*
* Handle nr_files sysctl
*/
#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
int proc_nr_files(ctl_table *table, int write, struct file *filp,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
files_stat.nr_files = get_nr_files();
return proc_dointvec(table, write, filp, buffer, lenp, ppos);
}
#else
int proc_nr_files(ctl_table *table, int write, struct file *filp,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}
#endif
/* 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)
{
struct task_struct *tsk;
static int old_max;
struct file * f;
/*
* Privileged users can go above max_files
*/
if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
/*
* percpu_counters are inaccurate. Do an expensive check before
* we go and fail.
*/
if (percpu_counter_sum(&nr_files) >= files_stat.max_files)
goto over;
}
f = kmem_cache_alloc(filp_cachep, GFP_KERNEL);
if (f == NULL)
goto fail;
percpu_counter_inc(&nr_files);
memset(f, 0, sizeof(*f));
if (security_file_alloc(f))
goto fail_sec;
tsk = current;
INIT_LIST_HEAD(&f->f_u.fu_list);
atomic_set(&f->f_count, 1);
rwlock_init(&f->f_owner.lock);
f->f_uid = tsk->fsuid;
f->f_gid = tsk->fsgid;
eventpoll_init_file(f);
/* f->f_version: 0 */
return f;
over:
/* Ran out of filps - report that */
if (get_nr_files() > old_max) {
printk(KERN_INFO "VFS: file-max limit %d reached\n",
get_max_files());
old_max = get_nr_files();
}
goto fail;
fail_sec:
file_free(f);
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();
fsnotify_close(file);
/*
* 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;
rcu_read_lock();
file = fcheck_files(files, fd);
if (file) {
if (!atomic_inc_not_zero(&file->f_count)) {
/* File object ref couldn't be taken */
rcu_read_unlock();
return NULL;
}
}
rcu_read_unlock();
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 {
rcu_read_lock();
file = fcheck_files(files, fd);
if (file) {
if (atomic_inc_not_zero(&file->f_count))
*fput_needed = 1;
else
/* Didn't get the reference, someone's freed */
file = NULL;
}
rcu_read_unlock();
}
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_u.fu_list, list);
file_list_unlock();
}
void file_kill(struct file *file)
{
if (!list_empty(&file->f_u.fu_list)) {
file_list_lock();
list_del_init(&file->f_u.fu_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_u.fu_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;
files_defer_init();
percpu_counter_init(&nr_files, 0);
}