[linux.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 fdtable_defer *f)
{
	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, (void (*)(void *))free_fdtable_work, fddef);
	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
ab2af1f5 DS	94	static void free_fdtable_work(struct fdtable_defer *f)
	95	{
	96	struct fdtable *fdt;
1da177e4	97
ab2af1f5 DS	98	spin_lock_bh(&f->lock);
	99	fdt = f->next;
	100	f->next = NULL;
	101	spin_unlock_bh(&f->lock);
	102	while(fdt) {
	103	struct fdtable *next = fdt->next;
	104	__free_fdtable(fdt);
	105	fdt = next;
	106	}
	107	}
1da177e4	108
ab2af1f5 DS	109	static void free_fdtable_rcu(struct rcu_head *rcu)
	110	{
	111	struct fdtable *fdt = container_of(rcu, struct fdtable, rcu);
	112	int fdset_size, fdarray_size;
	113	struct fdtable_defer *fddef;
1da177e4	114
ab2af1f5 DS	115	BUG_ON(!fdt);
	116	fdset_size = fdt->max_fdset / 8;
	117	fdarray_size = fdt->max_fds * sizeof(struct file *);
	118
	119	if (fdt->free_files) {
	120	/*
	121	* The this fdtable was embedded in the files structure
	122	* and the files structure itself was getting destroyed.
	123	* It is now safe to free the files structure.
	124	*/
	125	kmem_cache_free(files_cachep, fdt->free_files);
	126	return;
	127	}
0c9e63fd ED	128	if (fdt->max_fdset <= EMBEDDED_FD_SET_SIZE &&
0c9e63fd ED	129	fdt->max_fds <= NR_OPEN_DEFAULT) {
ab2af1f5 DS	130	/*
	131	* The fdtable was embedded
	132	*/
	133	return;
	134	}
	135	if (fdset_size <= PAGE_SIZE && fdarray_size <= PAGE_SIZE) {
	136	kfree(fdt->open_fds);
	137	kfree(fdt->close_on_exec);
	138	kfree(fdt->fd);
	139	kfree(fdt);
1da177e4	140	} else {
ab2af1f5 DS	141	fddef = &get_cpu_var(fdtable_defer_list);
	142	spin_lock(&fddef->lock);
	143	fdt->next = fddef->next;
	144	fddef->next = fdt;
	145	/*
	146	* vmallocs are handled from the workqueue context.
	147	* If the per-cpu workqueue is running, then we
	148	* defer work scheduling through a timer.
	149	*/
	150	if (!schedule_work(&fddef->wq))
	151	mod_timer(&fddef->timer, 5);
	152	spin_unlock(&fddef->lock);
	153	put_cpu_var(fdtable_defer_list);
1da177e4	154	}
ab2af1f5 DS	155	}
	156
	157	void free_fdtable(struct fdtable *fdt)
	158	{
0c9e63fd ED	159	if (fdt->free_files \|\|
	160	fdt->max_fdset > EMBEDDED_FD_SET_SIZE \|\|
	161	fdt->max_fds > NR_OPEN_DEFAULT)
ab2af1f5 DS	162	call_rcu(&fdt->rcu, free_fdtable_rcu);
	163	}
	164
	165	/*
	166	* Expand the fdset in the files_struct. Called with the files spinlock
	167	* held for write.
	168	*/
	169	static void copy_fdtable(struct fdtable nfdt, struct fdtable fdt)
	170	{
	171	int i;
	172	int count;
	173
	174	BUG_ON(nfdt->max_fdset < fdt->max_fdset);
	175	BUG_ON(nfdt->max_fds < fdt->max_fds);
	176	/* Copy the existing tables and install the new pointers */
	177
	178	i = fdt->max_fdset / (sizeof(unsigned long) * 8);
	179	count = (nfdt->max_fdset - fdt->max_fdset) / 8;
	180
	181	/*
	182	* Don't copy the entire array if the current fdset is
	183	* not yet initialised.
	184	*/
	185	if (i) {
	186	memcpy (nfdt->open_fds, fdt->open_fds,
	187	fdt->max_fdset/8);
	188	memcpy (nfdt->close_on_exec, fdt->close_on_exec,
	189	fdt->max_fdset/8);
	190	memset (&nfdt->open_fds->fds_bits[i], 0, count);
	191	memset (&nfdt->close_on_exec->fds_bits[i], 0, count);
	192	}
	193
	194	/* Don't copy/clear the array if we are creating a new
	195	fd array for fork() */
	196	if (fdt->max_fds) {
	197	memcpy(nfdt->fd, fdt->fd,
	198	fdt->max_fds * sizeof(struct file *));
	199	/* clear the remainder of the array */
	200	memset(&nfdt->fd[fdt->max_fds], 0,
	201	(nfdt->max_fds - fdt->max_fds) *
	202	sizeof(struct file *));
	203	}
1da177e4 LT	204	}
	205
	206	/*
	207	* Allocate an fdset array, using kmalloc or vmalloc.
	208	* Note: the array isn't cleared at allocation time.
	209	*/
	210	fd_set * alloc_fdset(int num)
	211	{
	212	fd_set *new_fdset;
	213	int size = num / 8;
	214
	215	if (size <= PAGE_SIZE)
	216	new_fdset = (fd_set *) kmalloc(size, GFP_KERNEL);
	217	else
	218	new_fdset = (fd_set *) vmalloc(size);
	219	return new_fdset;
	220	}
	221
	222	void free_fdset(fd_set *array, int num)
	223	{
0c9e63fd	224	if (num <= EMBEDDED_FD_SET_SIZE) /* Don't free an embedded fdset */
1da177e4	225	return;
0c9e63fd	226	else if (num <= 8 * PAGE_SIZE)
1da177e4 LT	227	kfree(array);
	228	else
	229	vfree(array);
	230	}
	231
ab2af1f5	232	static struct fdtable *alloc_fdtable(int nr)
1da177e4	233	{
ab2af1f5 DS	234	struct fdtable *fdt = NULL;
	235	int nfds = 0;
	236	fd_set new_openset = NULL, new_execset = NULL;
	237	struct file **new_fds;
1da177e4	238
0c9e63fd	239	fdt = kzalloc(sizeof(*fdt), GFP_KERNEL);
ab2af1f5 DS	240	if (!fdt)
ab2af1f5 DS	241	goto out;
1da177e4	242
a29b0b74	243	nfds = max_t(int, 8 * L1_CACHE_BYTES, roundup_pow_of_two(nr + 1));
92eb7a2f AM	244	if (nfds > NR_OPEN)
92eb7a2f AM	245	nfds = NR_OPEN;
1da177e4	246
ab2af1f5 DS	247	new_openset = alloc_fdset(nfds);
	248	new_execset = alloc_fdset(nfds);
	249	if (!new_openset \|\| !new_execset)
	250	goto out;
	251	fdt->open_fds = new_openset;
	252	fdt->close_on_exec = new_execset;
	253	fdt->max_fdset = nfds;
	254
	255	nfds = NR_OPEN_DEFAULT;
	256	/*
	257	* Expand to the max in easy steps, and keep expanding it until
	258	* we have enough for the requested fd array size.
	259	*/
	260	do {
	261	#if NR_OPEN_DEFAULT < 256
	262	if (nfds < 256)
	263	nfds = 256;
	264	else
	265	#endif
	266	if (nfds < (PAGE_SIZE / sizeof(struct file *)))
	267	nfds = PAGE_SIZE / sizeof(struct file *);
	268	else {
	269	nfds = nfds * 2;
	270	if (nfds > NR_OPEN)
	271	nfds = NR_OPEN;
	272	}
	273	} while (nfds <= nr);
	274	new_fds = alloc_fd_array(nfds);
	275	if (!new_fds)
d579091b	276	goto out2;
ab2af1f5 DS	277	fdt->fd = new_fds;
	278	fdt->max_fds = nfds;
	279	fdt->free_files = NULL;
	280	return fdt;
d579091b KK	281	out2:
d579091b KK	282	nfds = fdt->max_fdset;
ab2af1f5	283	out:
8b0e330b AM	284	free_fdset(new_openset, nfds);
8b0e330b AM	285	free_fdset(new_execset, nfds);
ab2af1f5 DS	286	kfree(fdt);
	287	return NULL;
	288	}
1da177e4	289
ab2af1f5	290	/*
74d392aa VL	291	* Expand the file descriptor table.
	292	* This function will allocate a new fdtable and both fd array and fdset, of
	293	* the given size.
	294	* Return <0 error code on error; 1 on successful completion.
	295	* The files->file_lock should be held on entry, and will be held on exit.
ab2af1f5 DS	296	*/
	297	static int expand_fdtable(struct files_struct *files, int nr)
	298	__releases(files->file_lock)
	299	__acquires(files->file_lock)
	300	{
74d392aa	301	struct fdtable new_fdt, cur_fdt;
ab2af1f5 DS	302
ab2af1f5 DS	303	spin_unlock(&files->file_lock);
74d392aa	304	new_fdt = alloc_fdtable(nr);
ab2af1f5	305	spin_lock(&files->file_lock);
74d392aa VL	306	if (!new_fdt)
74d392aa VL	307	return -ENOMEM;
ab2af1f5	308	/*
74d392aa VL	309	* Check again since another task may have expanded the fd table while
74d392aa VL	310	* we dropped the lock
ab2af1f5	311	*/
74d392aa VL	312	cur_fdt = files_fdtable(files);
	313	if (nr >= cur_fdt->max_fds \|\| nr >= cur_fdt->max_fdset) {
	314	/* Continue as planned */
	315	copy_fdtable(new_fdt, cur_fdt);
	316	rcu_assign_pointer(files->fdt, new_fdt);
	317	free_fdtable(cur_fdt);
ab2af1f5	318	} else {
74d392aa	319	/* Somebody else expanded, so undo our attempt */
74d392aa	320	__free_fdtable(new_fdt);
ab2af1f5	321	}
74d392aa	322	return 1;
1da177e4 LT	323	}
	324
	325	/*
	326	* Expand files.
74d392aa VL	327	* This function will expand the file structures, if the requested size exceeds
	328	* the current capacity and there is room for expansion.
	329	* Return <0 error code on error; 0 when nothing done; 1 when files were
	330	* expanded and execution may have blocked.
	331	* The files->file_lock should be held on entry, and will be held on exit.
1da177e4 LT	332	*/
	333	int expand_files(struct files_struct *files, int nr)
	334	{
badf1662	335	struct fdtable *fdt;
1da177e4	336
badf1662	337	fdt = files_fdtable(files);
74d392aa VL	338	/* Do we need to expand? */
	339	if (nr < fdt->max_fdset && nr < fdt->max_fds)
	340	return 0;
	341	/* Can we expand? */
	342	if (fdt->max_fdset >= NR_OPEN \|\| fdt->max_fds >= NR_OPEN \|\|
	343	nr >= NR_OPEN)
	344	return -EMFILE;
	345
	346	/* All good, so we try */
	347	return expand_fdtable(files, nr);
1da177e4	348	}
ab2af1f5 DS	349
	350	static void __devinit fdtable_defer_list_init(int cpu)
	351	{
	352	struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu);
	353	spin_lock_init(&fddef->lock);
	354	INIT_WORK(&fddef->wq, (void ()(void ))free_fdtable_work, fddef);
	355	init_timer(&fddef->timer);
	356	fddef->timer.data = (unsigned long)fddef;
	357	fddef->timer.function = fdtable_timer;
	358	fddef->next = NULL;
	359	}
	360
	361	void __init files_defer_init(void)
	362	{
	363	int i;
0a945022	364	for_each_possible_cpu(i)
ab2af1f5 DS	365	fdtable_defer_list_init(i);
ab2af1f5 DS	366	}