[linux-block.git] / fs / file.c

/*
 *  linux/fs/file.c
 *
 *  Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
 *
 *  Manage the dynamic fd arrays in the process files_struct.
 */

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/time.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/file.h>
#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/workqueue.h>

struct fdtable_defer {
	spinlock_t lock;
	struct work_struct wq;
	struct timer_list timer;
	struct fdtable *next;
};

/*
 * We use this list to defer free fdtables that have vmalloced
 * sets/arrays. By keeping a per-cpu list, we avoid having to embed
 * the work_struct in fdtable itself which avoids a 64 byte (i386) increase in
 * this per-task structure.
 */
static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);


/*
 * Allocate an fd array, using kmalloc or vmalloc.
 * Note: the array isn't cleared at allocation time.
 */
struct file ** alloc_fd_array(int num)
{
	struct file **new_fds;
	int size = num * sizeof(struct file *);

	if (size <= PAGE_SIZE)
		new_fds = (struct file **) kmalloc(size, GFP_KERNEL);
	else 
		new_fds = (struct file **) vmalloc(size);
	return new_fds;
}

void free_fd_array(struct file **array, int num)
{
	int size = num * sizeof(struct file *);

	if (!array) {
		printk (KERN_ERR "free_fd_array: array = 0 (num = %d)\n", num);
		return;
	}

	if (num <= NR_OPEN_DEFAULT) /* Don't free the embedded fd array! */
		return;
	else if (size <= PAGE_SIZE)
		kfree(array);
	else
		vfree(array);
}

static void __free_fdtable(struct fdtable *fdt)
{
	free_fdset(fdt->open_fds, fdt->max_fdset);
	free_fdset(fdt->close_on_exec, fdt->max_fdset);
	free_fd_array(fdt->fd, fdt->max_fds);
	kfree(fdt);
}

static void fdtable_timer(unsigned long data)
{
	struct fdtable_defer *fddef = (struct fdtable_defer *)data;

	spin_lock(&fddef->lock);
	/*
	 * If someone already emptied the queue return.
	 */
	if (!fddef->next)
		goto out;
	if (!schedule_work(&fddef->wq))
		mod_timer(&fddef->timer, 5);
out:
	spin_unlock(&fddef->lock);
}

static void free_fdtable_work(struct work_struct *work)
{
	struct fdtable_defer *f =
		container_of(work, struct fdtable_defer, wq);
	struct fdtable *fdt;

	spin_lock_bh(&f->lock);
	fdt = f->next;
	f->next = NULL;
	spin_unlock_bh(&f->lock);
	while(fdt) {
		struct fdtable *next = fdt->next;
		__free_fdtable(fdt);
		fdt = next;
	}
}

static void free_fdtable_rcu(struct rcu_head *rcu)
{
	struct fdtable *fdt = container_of(rcu, struct fdtable, rcu);
	int fdset_size, fdarray_size;
	struct fdtable_defer *fddef;

	BUG_ON(!fdt);
	fdset_size = fdt->max_fdset / 8;
	fdarray_size = fdt->max_fds * sizeof(struct file *);

	if (fdt->free_files) {
		/*
		 * The this fdtable was embedded in the files structure
		 * and the files structure itself was getting destroyed.
		 * It is now safe to free the files structure.
		 */
		kmem_cache_free(files_cachep, fdt->free_files);
		return;
	}
	if (fdt->max_fdset <= EMBEDDED_FD_SET_SIZE &&
		fdt->max_fds <= NR_OPEN_DEFAULT) {
		/*
		 * The fdtable was embedded
		 */
		return;
	}
	if (fdset_size <= PAGE_SIZE && fdarray_size <= PAGE_SIZE) {
		kfree(fdt->open_fds);
		kfree(fdt->close_on_exec);
		kfree(fdt->fd);
		kfree(fdt);
	} else {
		fddef = &get_cpu_var(fdtable_defer_list);
		spin_lock(&fddef->lock);
		fdt->next = fddef->next;
		fddef->next = fdt;
		/*
		 * vmallocs are handled from the workqueue context.
		 * If the per-cpu workqueue is running, then we
		 * defer work scheduling through a timer.
		 */
		if (!schedule_work(&fddef->wq))
			mod_timer(&fddef->timer, 5);
		spin_unlock(&fddef->lock);
		put_cpu_var(fdtable_defer_list);
	}
}

void free_fdtable(struct fdtable *fdt)
{
	if (fdt->free_files ||
		fdt->max_fdset > EMBEDDED_FD_SET_SIZE ||
		fdt->max_fds > NR_OPEN_DEFAULT)
		call_rcu(&fdt->rcu, free_fdtable_rcu);
}

/*
 * Expand the fdset in the files_struct.  Called with the files spinlock
 * held for write.
 */
static void copy_fdtable(struct fdtable *nfdt, struct fdtable *fdt)
{
	int i;
	int count;

	BUG_ON(nfdt->max_fdset < fdt->max_fdset);
	BUG_ON(nfdt->max_fds < fdt->max_fds);
	/* Copy the existing tables and install the new pointers */

	i = fdt->max_fdset / (sizeof(unsigned long) * 8);
	count = (nfdt->max_fdset - fdt->max_fdset) / 8;

	/*
	 * Don't copy the entire array if the current fdset is
	 * not yet initialised.
	 */
	if (i) {
		memcpy (nfdt->open_fds, fdt->open_fds,
						fdt->max_fdset/8);
		memcpy (nfdt->close_on_exec, fdt->close_on_exec,
						fdt->max_fdset/8);
		memset (&nfdt->open_fds->fds_bits[i], 0, count);
		memset (&nfdt->close_on_exec->fds_bits[i], 0, count);
	}

	/* Don't copy/clear the array if we are creating a new
	   fd array for fork() */
	if (fdt->max_fds) {
		memcpy(nfdt->fd, fdt->fd,
			fdt->max_fds * sizeof(struct file *));
		/* clear the remainder of the array */
		memset(&nfdt->fd[fdt->max_fds], 0,
		       (nfdt->max_fds - fdt->max_fds) *
					sizeof(struct file *));
	}
}

/*
 * Allocate an fdset array, using kmalloc or vmalloc.
 * Note: the array isn't cleared at allocation time.
 */
fd_set * alloc_fdset(int num)
{
	fd_set *new_fdset;
	int size = num / 8;

	if (size <= PAGE_SIZE)
		new_fdset = (fd_set *) kmalloc(size, GFP_KERNEL);
	else
		new_fdset = (fd_set *) vmalloc(size);
	return new_fdset;
}

void free_fdset(fd_set *array, int num)
{
	if (num <= EMBEDDED_FD_SET_SIZE) /* Don't free an embedded fdset */
		return;
	else if (num <= 8 * PAGE_SIZE)
		kfree(array);
	else
		vfree(array);
}

static struct fdtable *alloc_fdtable(int nr)
{
	struct fdtable *fdt = NULL;
	int nfds = 0;
  	fd_set *new_openset = NULL, *new_execset = NULL;
	struct file **new_fds;

	fdt = kzalloc(sizeof(*fdt), GFP_KERNEL);
	if (!fdt)
  		goto out;

	nfds = max_t(int, 8 * L1_CACHE_BYTES, roundup_pow_of_two(nr + 1));
	if (nfds > NR_OPEN)
		nfds = NR_OPEN;

  	new_openset = alloc_fdset(nfds);
  	new_execset = alloc_fdset(nfds);
  	if (!new_openset || !new_execset)
  		goto out;
	fdt->open_fds = new_openset;
	fdt->close_on_exec = new_execset;
	fdt->max_fdset = nfds;

	nfds = NR_OPEN_DEFAULT;
	/*
	 * Expand to the max in easy steps, and keep expanding it until
	 * we have enough for the requested fd array size.
	 */
	do {
#if NR_OPEN_DEFAULT < 256
		if (nfds < 256)
			nfds = 256;
		else
#endif
		if (nfds < (PAGE_SIZE / sizeof(struct file *)))
			nfds = PAGE_SIZE / sizeof(struct file *);
		else {
			nfds = nfds * 2;
			if (nfds > NR_OPEN)
				nfds = NR_OPEN;
  		}
	} while (nfds <= nr);
	new_fds = alloc_fd_array(nfds);
	if (!new_fds)
		goto out2;
	fdt->fd = new_fds;
	fdt->max_fds = nfds;
	fdt->free_files = NULL;
	return fdt;
out2:
	nfds = fdt->max_fdset;
out:
	free_fdset(new_openset, nfds);
	free_fdset(new_execset, nfds);
	kfree(fdt);
	return NULL;
}

/*
 * Expand the file descriptor table.
 * This function will allocate a new fdtable and both fd array and fdset, of
 * the given size.
 * Return <0 error code on error; 1 on successful completion.
 * The files->file_lock should be held on entry, and will be held on exit.
 */
static int expand_fdtable(struct files_struct *files, int nr)
	__releases(files->file_lock)
	__acquires(files->file_lock)
{
	struct fdtable *new_fdt, *cur_fdt;

	spin_unlock(&files->file_lock);
	new_fdt = alloc_fdtable(nr);
	spin_lock(&files->file_lock);
	if (!new_fdt)
		return -ENOMEM;
	/*
	 * Check again since another task may have expanded the fd table while
	 * we dropped the lock
	 */
	cur_fdt = files_fdtable(files);
	if (nr >= cur_fdt->max_fds || nr >= cur_fdt->max_fdset) {
		/* Continue as planned */
		copy_fdtable(new_fdt, cur_fdt);
		rcu_assign_pointer(files->fdt, new_fdt);
		free_fdtable(cur_fdt);
	} else {
		/* Somebody else expanded, so undo our attempt */
		__free_fdtable(new_fdt);
	}
	return 1;
}

/*
 * Expand files.
 * This function will expand the file structures, if the requested size exceeds
 * the current capacity and there is room for expansion.
 * Return <0 error code on error; 0 when nothing done; 1 when files were
 * expanded and execution may have blocked.
 * The files->file_lock should be held on entry, and will be held on exit.
 */
int expand_files(struct files_struct *files, int nr)
{
	struct fdtable *fdt;

	fdt = files_fdtable(files);
	/* Do we need to expand? */
	if (nr < fdt->max_fdset && nr < fdt->max_fds)
		return 0;
	/* Can we expand? */
	if (fdt->max_fdset >= NR_OPEN || fdt->max_fds >= NR_OPEN ||
	    nr >= NR_OPEN)
		return -EMFILE;

	/* All good, so we try */
	return expand_fdtable(files, nr);
}

static void __devinit fdtable_defer_list_init(int cpu)
{
	struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu);
	spin_lock_init(&fddef->lock);
	INIT_WORK(&fddef->wq, free_fdtable_work);
	init_timer(&fddef->timer);
	fddef->timer.data = (unsigned long)fddef;
	fddef->timer.function = fdtable_timer;
	fddef->next = NULL;
}

void __init files_defer_init(void)
{
	int i;
	for_each_possible_cpu(i)
		fdtable_defer_list_init(i);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/file.c
	3	*
	4	* Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
	5	*
	6	* Manage the dynamic fd arrays in the process files_struct.
	7	*/
	8
	9	#include <linux/fs.h>
	10	#include <linux/mm.h>
	11	#include <linux/time.h>
	12	#include <linux/slab.h>
	13	#include <linux/vmalloc.h>
	14	#include <linux/file.h>
	15	#include <linux/bitops.h>
ab2af1f5 DS	16	#include <linux/interrupt.h>
	17	#include <linux/spinlock.h>
	18	#include <linux/rcupdate.h>
	19	#include <linux/workqueue.h>
	20
	21	struct fdtable_defer {
	22	spinlock_t lock;
	23	struct work_struct wq;
	24	struct timer_list timer;
	25	struct fdtable *next;
	26	};
	27
	28	/*
	29	* We use this list to defer free fdtables that have vmalloced
	30	* sets/arrays. By keeping a per-cpu list, we avoid having to embed
	31	* the work_struct in fdtable itself which avoids a 64 byte (i386) increase in
	32	* this per-task structure.
	33	*/
	34	static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);
1da177e4 LT	35
	36
	37	/*
	38	* Allocate an fd array, using kmalloc or vmalloc.
	39	* Note: the array isn't cleared at allocation time.
	40	*/
	41	struct file ** alloc_fd_array(int num)
	42	{
	43	struct file **new_fds;
	44	int size = num * sizeof(struct file *);
	45
	46	if (size <= PAGE_SIZE)
	47	new_fds = (struct file **) kmalloc(size, GFP_KERNEL);
	48	else
	49	new_fds = (struct file **) vmalloc(size);
	50	return new_fds;
	51	}
	52
	53	void free_fd_array(struct file **array, int num)
	54	{
	55	int size = num * sizeof(struct file *);
	56
	57	if (!array) {
	58	printk (KERN_ERR "free_fd_array: array = 0 (num = %d)\n", num);
	59	return;
	60	}
	61
	62	if (num <= NR_OPEN_DEFAULT) /* Don't free the embedded fd array! */
	63	return;
	64	else if (size <= PAGE_SIZE)
	65	kfree(array);
	66	else
	67	vfree(array);
	68	}
	69
ab2af1f5	70	static void __free_fdtable(struct fdtable *fdt)
1da177e4	71	{
0b175a7e DS	72	free_fdset(fdt->open_fds, fdt->max_fdset);
	73	free_fdset(fdt->close_on_exec, fdt->max_fdset);
	74	free_fd_array(fdt->fd, fdt->max_fds);
ab2af1f5 DS	75	kfree(fdt);
ab2af1f5 DS	76	}
1da177e4	77
ab2af1f5 DS	78	static void fdtable_timer(unsigned long data)
	79	{
	80	struct fdtable_defer fddef = (struct fdtable_defer )data;
1da177e4	81
ab2af1f5 DS	82	spin_lock(&fddef->lock);
	83	/*
	84	* If someone already emptied the queue return.
1da177e4	85	*/
ab2af1f5 DS	86	if (!fddef->next)
	87	goto out;
	88	if (!schedule_work(&fddef->wq))
	89	mod_timer(&fddef->timer, 5);
	90	out:
	91	spin_unlock(&fddef->lock);
	92	}
1da177e4	93
65f27f38	94	static void free_fdtable_work(struct work_struct *work)
ab2af1f5	95	{
65f27f38 DH	96	struct fdtable_defer *f =
65f27f38 DH	97	container_of(work, struct fdtable_defer, wq);
ab2af1f5	98	struct fdtable *fdt;
1da177e4	99
ab2af1f5 DS	100	spin_lock_bh(&f->lock);
	101	fdt = f->next;
	102	f->next = NULL;
	103	spin_unlock_bh(&f->lock);
	104	while(fdt) {
	105	struct fdtable *next = fdt->next;
	106	__free_fdtable(fdt);
	107	fdt = next;
	108	}
	109	}
1da177e4	110
ab2af1f5 DS	111	static void free_fdtable_rcu(struct rcu_head *rcu)
	112	{
	113	struct fdtable *fdt = container_of(rcu, struct fdtable, rcu);
	114	int fdset_size, fdarray_size;
	115	struct fdtable_defer *fddef;
1da177e4	116
ab2af1f5 DS	117	BUG_ON(!fdt);
	118	fdset_size = fdt->max_fdset / 8;
	119	fdarray_size = fdt->max_fds * sizeof(struct file *);
	120
	121	if (fdt->free_files) {
	122	/*
	123	* The this fdtable was embedded in the files structure
	124	* and the files structure itself was getting destroyed.
	125	* It is now safe to free the files structure.
	126	*/
	127	kmem_cache_free(files_cachep, fdt->free_files);
	128	return;
	129	}
0c9e63fd ED	130	if (fdt->max_fdset <= EMBEDDED_FD_SET_SIZE &&
0c9e63fd ED	131	fdt->max_fds <= NR_OPEN_DEFAULT) {
ab2af1f5 DS	132	/*
	133	* The fdtable was embedded
	134	*/
	135	return;
	136	}
	137	if (fdset_size <= PAGE_SIZE && fdarray_size <= PAGE_SIZE) {
	138	kfree(fdt->open_fds);
	139	kfree(fdt->close_on_exec);
	140	kfree(fdt->fd);
	141	kfree(fdt);
1da177e4	142	} else {
ab2af1f5 DS	143	fddef = &get_cpu_var(fdtable_defer_list);
	144	spin_lock(&fddef->lock);
	145	fdt->next = fddef->next;
	146	fddef->next = fdt;
	147	/*
	148	* vmallocs are handled from the workqueue context.
	149	* If the per-cpu workqueue is running, then we
	150	* defer work scheduling through a timer.
	151	*/
	152	if (!schedule_work(&fddef->wq))
	153	mod_timer(&fddef->timer, 5);
	154	spin_unlock(&fddef->lock);
	155	put_cpu_var(fdtable_defer_list);
1da177e4	156	}
ab2af1f5 DS	157	}
	158
	159	void free_fdtable(struct fdtable *fdt)
	160	{
0c9e63fd ED	161	if (fdt->free_files \|\|
	162	fdt->max_fdset > EMBEDDED_FD_SET_SIZE \|\|
	163	fdt->max_fds > NR_OPEN_DEFAULT)
ab2af1f5 DS	164	call_rcu(&fdt->rcu, free_fdtable_rcu);
	165	}
	166
	167	/*
	168	* Expand the fdset in the files_struct. Called with the files spinlock
	169	* held for write.
	170	*/
	171	static void copy_fdtable(struct fdtable nfdt, struct fdtable fdt)
	172	{
	173	int i;
	174	int count;
	175
	176	BUG_ON(nfdt->max_fdset < fdt->max_fdset);
	177	BUG_ON(nfdt->max_fds < fdt->max_fds);
	178	/* Copy the existing tables and install the new pointers */
	179
	180	i = fdt->max_fdset / (sizeof(unsigned long) * 8);
	181	count = (nfdt->max_fdset - fdt->max_fdset) / 8;
	182
	183	/*
	184	* Don't copy the entire array if the current fdset is
	185	* not yet initialised.
	186	*/
	187	if (i) {
	188	memcpy (nfdt->open_fds, fdt->open_fds,
	189	fdt->max_fdset/8);
	190	memcpy (nfdt->close_on_exec, fdt->close_on_exec,
	191	fdt->max_fdset/8);
	192	memset (&nfdt->open_fds->fds_bits[i], 0, count);
	193	memset (&nfdt->close_on_exec->fds_bits[i], 0, count);
	194	}
	195
	196	/* Don't copy/clear the array if we are creating a new
	197	fd array for fork() */
	198	if (fdt->max_fds) {
	199	memcpy(nfdt->fd, fdt->fd,
	200	fdt->max_fds * sizeof(struct file *));
	201	/* clear the remainder of the array */
	202	memset(&nfdt->fd[fdt->max_fds], 0,
	203	(nfdt->max_fds - fdt->max_fds) *
	204	sizeof(struct file *));
	205	}
1da177e4 LT	206	}
	207
	208	/*
	209	* Allocate an fdset array, using kmalloc or vmalloc.
	210	* Note: the array isn't cleared at allocation time.
	211	*/
	212	fd_set * alloc_fdset(int num)
	213	{
	214	fd_set *new_fdset;
	215	int size = num / 8;
	216
	217	if (size <= PAGE_SIZE)
	218	new_fdset = (fd_set *) kmalloc(size, GFP_KERNEL);
	219	else
	220	new_fdset = (fd_set *) vmalloc(size);
	221	return new_fdset;
	222	}
	223
	224	void free_fdset(fd_set *array, int num)
	225	{
0c9e63fd	226	if (num <= EMBEDDED_FD_SET_SIZE) /* Don't free an embedded fdset */
1da177e4	227	return;
0c9e63fd	228	else if (num <= 8 * PAGE_SIZE)
1da177e4 LT	229	kfree(array);
	230	else
	231	vfree(array);
	232	}
	233
ab2af1f5	234	static struct fdtable *alloc_fdtable(int nr)
1da177e4	235	{
ab2af1f5 DS	236	struct fdtable *fdt = NULL;
	237	int nfds = 0;
	238	fd_set new_openset = NULL, new_execset = NULL;
	239	struct file **new_fds;
1da177e4	240
0c9e63fd	241	fdt = kzalloc(sizeof(*fdt), GFP_KERNEL);
ab2af1f5 DS	242	if (!fdt)
ab2af1f5 DS	243	goto out;
1da177e4	244
a29b0b74	245	nfds = max_t(int, 8 * L1_CACHE_BYTES, roundup_pow_of_two(nr + 1));
92eb7a2f AM	246	if (nfds > NR_OPEN)
92eb7a2f AM	247	nfds = NR_OPEN;
1da177e4	248
ab2af1f5 DS	249	new_openset = alloc_fdset(nfds);
	250	new_execset = alloc_fdset(nfds);
	251	if (!new_openset \|\| !new_execset)
	252	goto out;
	253	fdt->open_fds = new_openset;
	254	fdt->close_on_exec = new_execset;
	255	fdt->max_fdset = nfds;
	256
	257	nfds = NR_OPEN_DEFAULT;
	258	/*
	259	* Expand to the max in easy steps, and keep expanding it until
	260	* we have enough for the requested fd array size.
	261	*/
	262	do {
	263	#if NR_OPEN_DEFAULT < 256
	264	if (nfds < 256)
	265	nfds = 256;
	266	else
	267	#endif
	268	if (nfds < (PAGE_SIZE / sizeof(struct file *)))
	269	nfds = PAGE_SIZE / sizeof(struct file *);
	270	else {
	271	nfds = nfds * 2;
	272	if (nfds > NR_OPEN)
	273	nfds = NR_OPEN;
	274	}
	275	} while (nfds <= nr);
	276	new_fds = alloc_fd_array(nfds);
	277	if (!new_fds)
d579091b	278	goto out2;
ab2af1f5 DS	279	fdt->fd = new_fds;
	280	fdt->max_fds = nfds;
	281	fdt->free_files = NULL;
	282	return fdt;
d579091b KK	283	out2:
d579091b KK	284	nfds = fdt->max_fdset;
ab2af1f5	285	out:
8b0e330b AM	286	free_fdset(new_openset, nfds);
8b0e330b AM	287	free_fdset(new_execset, nfds);
ab2af1f5 DS	288	kfree(fdt);
	289	return NULL;
	290	}
1da177e4	291
ab2af1f5	292	/*
74d392aa VL	293	* Expand the file descriptor table.
	294	* This function will allocate a new fdtable and both fd array and fdset, of
	295	* the given size.
	296	* Return <0 error code on error; 1 on successful completion.
	297	* The files->file_lock should be held on entry, and will be held on exit.
ab2af1f5 DS	298	*/
	299	static int expand_fdtable(struct files_struct *files, int nr)
	300	__releases(files->file_lock)
	301	__acquires(files->file_lock)
	302	{
74d392aa	303	struct fdtable new_fdt, cur_fdt;
ab2af1f5 DS	304
ab2af1f5 DS	305	spin_unlock(&files->file_lock);
74d392aa	306	new_fdt = alloc_fdtable(nr);
ab2af1f5	307	spin_lock(&files->file_lock);
74d392aa VL	308	if (!new_fdt)
74d392aa VL	309	return -ENOMEM;
ab2af1f5	310	/*
74d392aa VL	311	* Check again since another task may have expanded the fd table while
74d392aa VL	312	* we dropped the lock
ab2af1f5	313	*/
74d392aa VL	314	cur_fdt = files_fdtable(files);
	315	if (nr >= cur_fdt->max_fds \|\| nr >= cur_fdt->max_fdset) {
	316	/* Continue as planned */
	317	copy_fdtable(new_fdt, cur_fdt);
	318	rcu_assign_pointer(files->fdt, new_fdt);
	319	free_fdtable(cur_fdt);
ab2af1f5	320	} else {
74d392aa	321	/* Somebody else expanded, so undo our attempt */
74d392aa	322	__free_fdtable(new_fdt);
ab2af1f5	323	}
74d392aa	324	return 1;
1da177e4 LT	325	}
	326
	327	/*
	328	* Expand files.
74d392aa VL	329	* This function will expand the file structures, if the requested size exceeds
	330	* the current capacity and there is room for expansion.
	331	* Return <0 error code on error; 0 when nothing done; 1 when files were
	332	* expanded and execution may have blocked.
	333	* The files->file_lock should be held on entry, and will be held on exit.
1da177e4 LT	334	*/
	335	int expand_files(struct files_struct *files, int nr)
	336	{
badf1662	337	struct fdtable *fdt;
1da177e4	338
badf1662	339	fdt = files_fdtable(files);
74d392aa VL	340	/* Do we need to expand? */
	341	if (nr < fdt->max_fdset && nr < fdt->max_fds)
	342	return 0;
	343	/* Can we expand? */
	344	if (fdt->max_fdset >= NR_OPEN \|\| fdt->max_fds >= NR_OPEN \|\|
	345	nr >= NR_OPEN)
	346	return -EMFILE;
	347
	348	/* All good, so we try */
	349	return expand_fdtable(files, nr);
1da177e4	350	}
ab2af1f5 DS	351
	352	static void __devinit fdtable_defer_list_init(int cpu)
	353	{
	354	struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu);
	355	spin_lock_init(&fddef->lock);
65f27f38	356	INIT_WORK(&fddef->wq, free_fdtable_work);
ab2af1f5 DS	357	init_timer(&fddef->timer);
	358	fddef->timer.data = (unsigned long)fddef;
	359	fddef->timer.function = fdtable_timer;
	360	fddef->next = NULL;
	361	}
	362
	363	void __init files_defer_init(void)
	364	{
	365	int i;
0a945022	366	for_each_possible_cpu(i)
ab2af1f5 DS	367	fdtable_defer_list_init(i);
ab2af1f5 DS	368	}