[mirror_ubuntu-artful-kernel.git] / fs / file_table.c

/*
 *  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/fdtable.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/cred.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 <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/task_work.h>
#include <linux/ima.h>
#include <linux/swap.h>

#include <linux/atomic.h>

#include "internal.h"

/* sysctl tunables... */
struct files_stat_struct files_stat = {
	.max_files = NR_FILE
};

/* SLAB cache for file structures */
static struct kmem_cache *filp_cachep __read_mostly;

static struct percpu_counter nr_files __cacheline_aligned_in_smp;

static void file_free_rcu(struct rcu_head *head)
{
	struct file *f = container_of(head, struct file, f_u.fu_rcuhead);

	put_cred(f->f_cred);
	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 long get_nr_files(void)
{
	return percpu_counter_read_positive(&nr_files);
}

/*
 * Return the maximum number of open files in the system
 */
unsigned long 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(struct ctl_table *table, int write,
                     void __user *buffer, size_t *lenp, loff_t *ppos)
{
	files_stat.nr_files = get_nr_files();
	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}
#else
int proc_nr_files(struct ctl_table *table, int write,
                     void __user *buffer, size_t *lenp, loff_t *ppos)
{
	return -ENOSYS;
}
#endif

/* Find an unused file structure and return a pointer to it.
 * Returns an error pointer if some error happend e.g. we over file
 * structures limit, run out of memory or operation is not permitted.
 *
 * Be very careful using this.  You are responsible for
 * getting write access to any mount that you might assign
 * to this filp, if it is opened for write.  If this is not
 * done, you will imbalance int the mount's writer count
 * and a warning at __fput() time.
 */
struct file *get_empty_filp(void)
{
	const struct cred *cred = current_cred();
	static long old_max;
	struct file *f;
	int error;

	/*
	 * 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_positive(&nr_files) >= files_stat.max_files)
			goto over;
	}

	f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
	if (unlikely(!f))
		return ERR_PTR(-ENOMEM);

	percpu_counter_inc(&nr_files);
	f->f_cred = get_cred(cred);
	error = security_file_alloc(f);
	if (unlikely(error)) {
		file_free(f);
		return ERR_PTR(error);
	}

	atomic_long_set(&f->f_count, 1);
	rwlock_init(&f->f_owner.lock);
	spin_lock_init(&f->f_lock);
	mutex_init(&f->f_pos_lock);
	eventpoll_init_file(f);
	/* f->f_version: 0 */
	return f;

over:
	/* Ran out of filps - report that */
	if (get_nr_files() > old_max) {
		pr_info("VFS: file-max limit %lu reached\n", get_max_files());
		old_max = get_nr_files();
	}
	return ERR_PTR(-ENFILE);
}
EXPORT_SYMBOL_GPL(get_empty_filp);

/**
 * alloc_file - allocate and initialize a 'struct file'
 *
 * @path: the (dentry, vfsmount) pair for the new file
 * @mode: the mode with which the new file will be opened
 * @fop: the 'struct file_operations' for the new file
 */
struct file *alloc_file(const struct path *path, fmode_t mode,
		const struct file_operations *fop)
{
	struct file *file;

	file = get_empty_filp();
	if (IS_ERR(file))
		return file;

	file->f_path = *path;
	file->f_inode = path->dentry->d_inode;
	file->f_mapping = path->dentry->d_inode->i_mapping;
	file->f_wb_err = filemap_sample_wb_err(file->f_mapping);
	if ((mode & FMODE_READ) &&
	     likely(fop->read || fop->read_iter))
		mode |= FMODE_CAN_READ;
	if ((mode & FMODE_WRITE) &&
	     likely(fop->write || fop->write_iter))
		mode |= FMODE_CAN_WRITE;
	file->f_mode = mode;
	file->f_op = fop;
	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		i_readcount_inc(path->dentry->d_inode);
	return file;
}
EXPORT_SYMBOL(alloc_file);

/* the real guts of fput() - releasing the last reference to file
 */
static void __fput(struct file *file)
{
	struct dentry *dentry = file->f_path.dentry;
	struct vfsmount *mnt = file->f_path.mnt;
	struct inode *inode = file->f_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_file(file);

	if (unlikely(file->f_flags & FASYNC)) {
		if (file->f_op->fasync)
			file->f_op->fasync(-1, file, 0);
	}
	ima_file_free(file);
	if (file->f_op->release)
		file->f_op->release(inode, file);
	security_file_free(file);
	if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
		     !(file->f_mode & FMODE_PATH))) {
		cdev_put(inode->i_cdev);
	}
	fops_put(file->f_op);
	put_pid(file->f_owner.pid);
	if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		i_readcount_dec(inode);
	if (file->f_mode & FMODE_WRITER) {
		put_write_access(inode);
		__mnt_drop_write(mnt);
	}
	file->f_path.dentry = NULL;
	file->f_path.mnt = NULL;
	file->f_inode = NULL;
	file_free(file);
	dput(dentry);
	mntput(mnt);
}

static LLIST_HEAD(delayed_fput_list);
static void delayed_fput(struct work_struct *unused)
{
	struct llist_node *node = llist_del_all(&delayed_fput_list);
	struct llist_node *next;

	for (; node; node = next) {
		next = llist_next(node);
		__fput(llist_entry(node, struct file, f_u.fu_llist));
	}
}

static void ____fput(struct callback_head *work)
{
	__fput(container_of(work, struct file, f_u.fu_rcuhead));
}

/*
 * If kernel thread really needs to have the final fput() it has done
 * to complete, call this.  The only user right now is the boot - we
 * *do* need to make sure our writes to binaries on initramfs has
 * not left us with opened struct file waiting for __fput() - execve()
 * won't work without that.  Please, don't add more callers without
 * very good reasons; in particular, never call that with locks
 * held and never call that from a thread that might need to do
 * some work on any kind of umount.
 */
void flush_delayed_fput(void)
{
	delayed_fput(NULL);
}
EXPORT_SYMBOL_GPL(flush_delayed_fput);

static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);

void fput(struct file *file)
{
	if (atomic_long_dec_and_test(&file->f_count)) {
		struct task_struct *task = current;

		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
			init_task_work(&file->f_u.fu_rcuhead, ____fput);
			if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
				return;
			/*
			 * After this task has run exit_task_work(),
			 * task_work_add() will fail.  Fall through to delayed
			 * fput to avoid leaking *file.
			 */
		}

		if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))
			schedule_delayed_work(&delayed_fput_work, 1);
	}
}

/*
 * synchronous analog of fput(); for kernel threads that might be needed
 * in some umount() (and thus can't use flush_delayed_fput() without
 * risking deadlocks), need to wait for completion of __fput() and know
 * for this specific struct file it won't involve anything that would
 * need them.  Use only if you really need it - at the very least,
 * don't blindly convert fput() by kernel thread to that.
 */
void __fput_sync(struct file *file)
{
	if (atomic_long_dec_and_test(&file->f_count)) {
		struct task_struct *task = current;
		BUG_ON(!(task->flags & PF_KTHREAD));
		__fput(file);
	}
}

EXPORT_SYMBOL(fput);
EXPORT_SYMBOL_GPL(__fput_sync);

void put_filp(struct file *file)
{
	if (atomic_long_dec_and_test(&file->f_count)) {
		security_file_free(file);
		file_free(file);
	}
}
EXPORT_SYMBOL_GPL(put_filp);

void __init files_init(void)
{ 
	filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
			SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
	percpu_counter_init(&nr_files, 0, GFP_KERNEL);
}

/*
 * One file with associated inode and dcache is very roughly 1K. Per default
 * do not use more than 10% of our memory for files.
 */
void __init files_maxfiles_init(void)
{
	unsigned long n;
	unsigned long memreserve = (totalram_pages - nr_free_pages()) * 3/2;

	memreserve = min(memreserve, totalram_pages - 1);
	n = ((totalram_pages - memreserve) * (PAGE_SIZE / 1024)) / 10;

	files_stat.max_files = max_t(unsigned long, n, NR_FILE);
}
Commit	Line	Data
1da177e4 LT	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>
9f3acc31	11	#include <linux/fdtable.h>
1da177e4 LT	12	#include <linux/init.h>
1da177e4 LT	13	#include <linux/module.h>
1da177e4 LT	14	#include <linux/fs.h>
1da177e4 LT	15	#include <linux/security.h>
5b825c3a	16	#include <linux/cred.h>
1da177e4	17	#include <linux/eventpoll.h>
ab2af1f5	18	#include <linux/rcupdate.h>
1da177e4	19	#include <linux/mount.h>
16f7e0fe	20	#include <linux/capability.h>
1da177e4	21	#include <linux/cdev.h>
0eeca283	22	#include <linux/fsnotify.h>
529bf6be DS	23	#include <linux/sysctl.h>
529bf6be DS	24	#include <linux/percpu_counter.h>
6416ccb7	25	#include <linux/percpu.h>
4a9d4b02 AV	26	#include <linux/hardirq.h>
4a9d4b02 AV	27	#include <linux/task_work.h>
0552f879	28	#include <linux/ima.h>
4248b0da	29	#include <linux/swap.h>
529bf6be	30
60063497	31	#include <linux/atomic.h>
1da177e4	32
e81e3f4d EP	33	#include "internal.h"
e81e3f4d EP	34
1da177e4 LT	35	/* sysctl tunables... */
	36	struct files_stat_struct files_stat = {
	37	.max_files = NR_FILE
	38	};
	39
b6b3fdea ED	40	/* SLAB cache for file structures */
	41	static struct kmem_cache *filp_cachep __read_mostly;
	42
529bf6be	43	static struct percpu_counter nr_files __cacheline_aligned_in_smp;
1da177e4	44
5c33b183	45	static void file_free_rcu(struct rcu_head *head)
1da177e4	46	{
d76b0d9b DH	47	struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
	48
	49	put_cred(f->f_cred);
529bf6be	50	kmem_cache_free(filp_cachep, f);
1da177e4 LT	51	}
1da177e4 LT	52
529bf6be	53	static inline void file_free(struct file *f)
1da177e4	54	{
529bf6be DS	55	percpu_counter_dec(&nr_files);
529bf6be DS	56	call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
1da177e4 LT	57	}
1da177e4 LT	58
529bf6be DS	59	/*
	60	* Return the total number of open files in the system
	61	*/
518de9b3	62	static long get_nr_files(void)
1da177e4	63	{
529bf6be	64	return percpu_counter_read_positive(&nr_files);
1da177e4 LT	65	}
1da177e4 LT	66
529bf6be DS	67	/*
	68	* Return the maximum number of open files in the system
	69	*/
518de9b3	70	unsigned long get_max_files(void)
ab2af1f5	71	{
529bf6be	72	return files_stat.max_files;
ab2af1f5	73	}
529bf6be DS	74	EXPORT_SYMBOL_GPL(get_max_files);
	75
	76	/*
	77	* Handle nr_files sysctl
	78	*/
	79	#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
1f7e0616	80	int proc_nr_files(struct ctl_table *table, int write,
529bf6be DS	81	void __user buffer, size_t lenp, loff_t *ppos)
	82	{
	83	files_stat.nr_files = get_nr_files();
518de9b3	84	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
529bf6be DS	85	}
529bf6be DS	86	#else
1f7e0616	87	int proc_nr_files(struct ctl_table *table, int write,
529bf6be DS	88	void __user buffer, size_t lenp, loff_t *ppos)
	89	{
	90	return -ENOSYS;
	91	}
	92	#endif
ab2af1f5	93
1da177e4	94	/* Find an unused file structure and return a pointer to it.
1afc99be AV	95	* Returns an error pointer if some error happend e.g. we over file
1afc99be AV	96	* structures limit, run out of memory or operation is not permitted.
430e285e DH	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.
1da177e4 LT	103	*/
	104	struct file *get_empty_filp(void)
	105	{
86a264ab	106	const struct cred *cred = current_cred();
518de9b3	107	static long old_max;
1afc99be AV	108	struct file *f;
1afc99be AV	109	int error;
1da177e4 LT	110
	111	/*
	112	* Privileged users can go above max_files
	113	*/
529bf6be DS	114	if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
	115	/*
	116	* percpu_counters are inaccurate. Do an expensive check before
	117	* we go and fail.
	118	*/
52d9f3b4	119	if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
529bf6be DS	120	goto over;
529bf6be DS	121	}
af4d2ecb	122
4975e45f	123	f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
1afc99be AV	124	if (unlikely(!f))
1afc99be AV	125	return ERR_PTR(-ENOMEM);
af4d2ecb	126
529bf6be	127	percpu_counter_inc(&nr_files);
78d29788	128	f->f_cred = get_cred(cred);
1afc99be AV	129	error = security_file_alloc(f);
	130	if (unlikely(error)) {
	131	file_free(f);
	132	return ERR_PTR(error);
	133	}
1da177e4	134
516e0cc5	135	atomic_long_set(&f->f_count, 1);
af4d2ecb	136	rwlock_init(&f->f_owner.lock);
68499914	137	spin_lock_init(&f->f_lock);
9c225f26	138	mutex_init(&f->f_pos_lock);
5a6b7951	139	eventpoll_init_file(f);
af4d2ecb	140	/* f->f_version: 0 */
af4d2ecb KK	141	return f;
	142
	143	over:
1da177e4	144	/* Ran out of filps - report that */
529bf6be	145	if (get_nr_files() > old_max) {
518de9b3	146	pr_info("VFS: file-max limit %lu reached\n", get_max_files());
529bf6be	147	old_max = get_nr_files();
1da177e4	148	}
1afc99be	149	return ERR_PTR(-ENFILE);
1da177e4	150	}
b6450630	151	EXPORT_SYMBOL_GPL(get_empty_filp);
1da177e4	152
ce8d2cdf DH	153	/**
ce8d2cdf DH	154	* alloc_file - allocate and initialize a 'struct file'
a457606a EB	155	*
a457606a EB	156	* @path: the (dentry, vfsmount) pair for the new file
ce8d2cdf DH	157	* @mode: the mode with which the new file will be opened
ce8d2cdf DH	158	* @fop: the 'struct file_operations' for the new file
ce8d2cdf	159	*/
a4141d7c	160	struct file alloc_file(const struct path path, fmode_t mode,
2c48b9c4	161	const struct file_operations *fop)
ce8d2cdf DH	162	{
ce8d2cdf DH	163	struct file *file;
ce8d2cdf DH	164
ce8d2cdf DH	165	file = get_empty_filp();
1afc99be	166	if (IS_ERR(file))
39b65252	167	return file;
ce8d2cdf	168
2c48b9c4	169	file->f_path = *path;
dd37978c	170	file->f_inode = path->dentry->d_inode;
2c48b9c4	171	file->f_mapping = path->dentry->d_inode->i_mapping;
5660e13d	172	file->f_wb_err = filemap_sample_wb_err(file->f_mapping);
293bc982	173	if ((mode & FMODE_READ) &&
84363182	174	likely(fop->read \|\| fop->read_iter))
7f7f25e8	175	mode \|= FMODE_CAN_READ;
293bc982	176	if ((mode & FMODE_WRITE) &&
84363182	177	likely(fop->write \|\| fop->write_iter))
7f7f25e8	178	mode \|= FMODE_CAN_WRITE;
ce8d2cdf DH	179	file->f_mode = mode;
ce8d2cdf DH	180	file->f_op = fop;
890275b5 MZ	181	if ((mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_READ)
890275b5 MZ	182	i_readcount_inc(path->dentry->d_inode);
3d1e4631	183	return file;
ce8d2cdf	184	}
73efc468	185	EXPORT_SYMBOL(alloc_file);
ce8d2cdf	186
d7065da0	187	/* the real guts of fput() - releasing the last reference to file
1da177e4	188	*/
d7065da0	189	static void __fput(struct file *file)
1da177e4	190	{
0f7fc9e4 JJS	191	struct dentry *dentry = file->f_path.dentry;
0f7fc9e4 JJS	192	struct vfsmount *mnt = file->f_path.mnt;
c77cecee	193	struct inode *inode = file->f_inode;
1da177e4 LT	194
1da177e4 LT	195	might_sleep();
0eeca283 RL	196
0eeca283 RL	197	fsnotify_close(file);
1da177e4 LT	198	/*
	199	* The function eventpoll_release() should be the first called
	200	* in the file cleanup chain.
	201	*/
	202	eventpoll_release(file);
78ed8a13	203	locks_remove_file(file);
1da177e4	204
233e70f4	205	if (unlikely(file->f_flags & FASYNC)) {
72c2d531	206	if (file->f_op->fasync)
233e70f4 AV	207	file->f_op->fasync(-1, file, 0);
233e70f4 AV	208	}
4199d35c	209	ima_file_free(file);
72c2d531	210	if (file->f_op->release)
1da177e4 LT	211	file->f_op->release(inode, file);
1da177e4 LT	212	security_file_free(file);
60ed8cf7 MS	213	if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
60ed8cf7 MS	214	!(file->f_mode & FMODE_PATH))) {
1da177e4	215	cdev_put(inode->i_cdev);
60ed8cf7	216	}
1da177e4	217	fops_put(file->f_op);
609d7fa9	218	put_pid(file->f_owner.pid);
890275b5 MZ	219	if ((file->f_mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_READ)
890275b5 MZ	220	i_readcount_dec(inode);
83f936c7 AV	221	if (file->f_mode & FMODE_WRITER) {
	222	put_write_access(inode);
	223	__mnt_drop_write(mnt);
	224	}
0f7fc9e4 JJS	225	file->f_path.dentry = NULL;
0f7fc9e4 JJS	226	file->f_path.mnt = NULL;
dd37978c	227	file->f_inode = NULL;
1da177e4 LT	228	file_free(file);
	229	dput(dentry);
	230	mntput(mnt);
	231	}
	232
4f5e65a1	233	static LLIST_HEAD(delayed_fput_list);
4a9d4b02 AV	234	static void delayed_fput(struct work_struct *unused)
4a9d4b02 AV	235	{
4f5e65a1 ON	236	struct llist_node *node = llist_del_all(&delayed_fput_list);
	237	struct llist_node *next;
	238
	239	for (; node; node = next) {
	240	next = llist_next(node);
	241	__fput(llist_entry(node, struct file, f_u.fu_llist));
4a9d4b02 AV	242	}
	243	}
	244
	245	static void ____fput(struct callback_head *work)
	246	{
	247	__fput(container_of(work, struct file, f_u.fu_rcuhead));
	248	}
	249
	250	/*
	251	* If kernel thread really needs to have the final fput() it has done
	252	* to complete, call this. The only user right now is the boot - we
	253	* do need to make sure our writes to binaries on initramfs has
	254	* not left us with opened struct file waiting for __fput() - execve()
	255	* won't work without that. Please, don't add more callers without
	256	* very good reasons; in particular, never call that with locks
	257	* held and never call that from a thread that might need to do
	258	* some work on any kind of umount.
	259	*/
	260	void flush_delayed_fput(void)
	261	{
	262	delayed_fput(NULL);
	263	}
b6450630	264	EXPORT_SYMBOL_GPL(flush_delayed_fput);
4a9d4b02	265
c7314d74	266	static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
4a9d4b02	267
d7065da0 AV	268	void fput(struct file *file)
d7065da0 AV	269	{
4a9d4b02 AV	270	if (atomic_long_dec_and_test(&file->f_count)) {
4a9d4b02 AV	271	struct task_struct *task = current;
e7b2c406	272
e7b2c406 ON	273	if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
	274	init_task_work(&file->f_u.fu_rcuhead, ____fput);
	275	if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
	276	return;
64372501 AM	277	/*
64372501 AM	278	* After this task has run exit_task_work(),
be49b30a	279	* task_work_add() will fail. Fall through to delayed
64372501 AM	280	* fput to avoid leaking *file.
64372501 AM	281	*/
4a9d4b02	282	}
4f5e65a1 ON	283
4f5e65a1 ON	284	if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))
c7314d74	285	schedule_delayed_work(&delayed_fput_work, 1);
4a9d4b02 AV	286	}
	287	}
	288
	289	/*
	290	* synchronous analog of fput(); for kernel threads that might be needed
	291	* in some umount() (and thus can't use flush_delayed_fput() without
	292	* risking deadlocks), need to wait for completion of __fput() and know
	293	* for this specific struct file it won't involve anything that would
	294	* need them. Use only if you really need it - at the very least,
	295	* don't blindly convert fput() by kernel thread to that.
	296	*/
	297	void __fput_sync(struct file *file)
	298	{
	299	if (atomic_long_dec_and_test(&file->f_count)) {
	300	struct task_struct *task = current;
4a9d4b02	301	BUG_ON(!(task->flags & PF_KTHREAD));
d7065da0	302	__fput(file);
4a9d4b02	303	}
d7065da0 AV	304	}
	305
	306	EXPORT_SYMBOL(fput);
b6450630	307	EXPORT_SYMBOL_GPL(__fput_sync);
d7065da0	308
1da177e4 LT	309	void put_filp(struct file *file)
1da177e4 LT	310	{
516e0cc5	311	if (atomic_long_dec_and_test(&file->f_count)) {
1da177e4	312	security_file_free(file);
1da177e4 LT	313	file_free(file);
	314	}
	315	}
b6450630	316	EXPORT_SYMBOL_GPL(put_filp);
1da177e4	317
4248b0da	318	void __init files_init(void)
1da177e4	319	{
b6b3fdea ED	320	filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
b6b3fdea ED	321	SLAB_HWCACHE_ALIGN \| SLAB_PANIC, NULL);
4248b0da MG	322	percpu_counter_init(&nr_files, 0, GFP_KERNEL);
4248b0da MG	323	}
b6b3fdea	324
4248b0da MG	325	/*
	326	* One file with associated inode and dcache is very roughly 1K. Per default
	327	* do not use more than 10% of our memory for files.
	328	*/
	329	void __init files_maxfiles_init(void)
	330	{
	331	unsigned long n;
	332	unsigned long memreserve = (totalram_pages - nr_free_pages()) * 3/2;
	333
	334	memreserve = min(memreserve, totalram_pages - 1);
	335	n = ((totalram_pages - memreserve) * (PAGE_SIZE / 1024)) / 10;
1da177e4	336
518de9b3	337	files_stat.max_files = max_t(unsigned long, n, NR_FILE);
1da177e4	338	}