fs/file.c - kernel/msm - Gitiles

 /*
  *  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 <= __FD_SETSIZE && 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 > __FD_SETSIZE ||
 					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 *));
 	}
 	nfdt->next_fd = fdt->next_fd;
 }

 /*
  * 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)
 {
 	int size = num / 8;

 	if (num <= __FD_SETSIZE) /* Don't free an embedded fdset */
 		return;
 	else if (size <= 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 = kmalloc(sizeof(*fdt), GFP_KERNEL);
 	if (!fdt)
   		goto out;
 	memset(fdt, 0, sizeof(*fdt));

 	nfds = __FD_SETSIZE;
   	/* Expand to the max in easy steps */
   	do {
 		if (nfds < (PAGE_SIZE * 8))
 			nfds = PAGE_SIZE * 8;
 		else {
 			nfds = nfds * 2;
 			if (nfds > NR_OPEN)
 				nfds = NR_OPEN;
 		}
 	} while (nfds <= nr);

   	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 out;
 	fdt->fd = new_fds;
 	fdt->max_fds = nfds;
 	fdt->free_files = NULL;
 	return fdt;
 out:
   	if (new_openset)
   		free_fdset(new_openset, nfds);
   	if (new_execset)
   		free_fdset(new_execset, nfds);
 	kfree(fdt);
 	return NULL;
 }

 /*
  * Expands the file descriptor table - it will allocate a new fdtable and
  * both fd array and fdset. It is expected to be called with the
  * files_lock held.
  */
 static int expand_fdtable(struct files_struct *files, int nr)
 	__releases(files->file_lock)
 	__acquires(files->file_lock)
 {
 	int error = 0;
 	struct fdtable *fdt;
 	struct fdtable *nfdt = NULL;

 	spin_unlock(&files->file_lock);
 	nfdt = alloc_fdtable(nr);
 	if (!nfdt) {
 		error = -ENOMEM;
 		spin_lock(&files->file_lock);
 		goto out;
 	}

 	spin_lock(&files->file_lock);
 	fdt = files_fdtable(files);
 	/*
 	 * Check again since another task may have expanded the
 	 * fd table while we dropped the lock
 	 */
 	if (nr >= fdt->max_fds || nr >= fdt->max_fdset) {
 		copy_fdtable(nfdt, fdt);
 	} else {
 		/* Somebody expanded while we dropped file_lock */
 		spin_unlock(&files->file_lock);
 		__free_fdtable(nfdt);
 		spin_lock(&files->file_lock);
 		goto out;
 	}
 	rcu_assign_pointer(files->fdt, nfdt);
 	free_fdtable(fdt);
 out:
 	return error;
 }

 /*
  * Expand files.
  * Return <0 on error; 0 nothing done; 1 files expanded, we may have blocked.
  * Should be called with the files->file_lock spinlock held for write.
  */
 int expand_files(struct files_struct *files, int nr)
 {
 	int err, expand = 0;
 	struct fdtable *fdt;

 	fdt = files_fdtable(files);
 	if (nr >= fdt->max_fdset || nr >= fdt->max_fds) {
 		if (fdt->max_fdset >= NR_OPEN ||
 			fdt->max_fds >= NR_OPEN || nr >= NR_OPEN) {
 			err = -EMFILE;
 			goto out;
 		}
 		expand = 1;
 		if ((err = expand_fdtable(files, nr)))
 			goto out;
 	}
 	err = expand;
 out:
 	return err;
 }

 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;
 	/* Really early - can't use for_each_cpu */
 	for (i = 0; i < NR_CPUS; i++)
 		fdtable_defer_list_init(i);
 }
	/*
	* 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 <= __FD_SETSIZE && 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 > __FD_SETSIZE \|\|
	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 *));
	}
	nfdt->next_fd = fdt->next_fd;
	}

	/*
	* 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)
	{
	int size = num / 8;

	if (num <= __FD_SETSIZE) /* Don't free an embedded fdset */
	return;
	else if (size <= 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 = kmalloc(sizeof(*fdt), GFP_KERNEL);
	if (!fdt)
	goto out;
	memset(fdt, 0, sizeof(*fdt));

	nfds = __FD_SETSIZE;
	/* Expand to the max in easy steps */
	do {
	if (nfds < (PAGE_SIZE * 8))
	nfds = PAGE_SIZE * 8;
	else {
	nfds = nfds * 2;
	if (nfds > NR_OPEN)
	nfds = NR_OPEN;
	}
	} while (nfds <= nr);

	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 out;
	fdt->fd = new_fds;
	fdt->max_fds = nfds;
	fdt->free_files = NULL;
	return fdt;
	out:
	if (new_openset)
	free_fdset(new_openset, nfds);
	if (new_execset)
	free_fdset(new_execset, nfds);
	kfree(fdt);
	return NULL;
	}

	/*
	* Expands the file descriptor table - it will allocate a new fdtable and
	* both fd array and fdset. It is expected to be called with the
	* files_lock held.
	*/
	static int expand_fdtable(struct files_struct *files, int nr)
	__releases(files->file_lock)
	__acquires(files->file_lock)
	{
	int error = 0;
	struct fdtable *fdt;
	struct fdtable *nfdt = NULL;

	spin_unlock(&files->file_lock);
	nfdt = alloc_fdtable(nr);
	if (!nfdt) {
	error = -ENOMEM;
	spin_lock(&files->file_lock);
	goto out;
	}

	spin_lock(&files->file_lock);
	fdt = files_fdtable(files);
	/*
	* Check again since another task may have expanded the
	* fd table while we dropped the lock
	*/
	if (nr >= fdt->max_fds \|\| nr >= fdt->max_fdset) {
	copy_fdtable(nfdt, fdt);
	} else {
	/* Somebody expanded while we dropped file_lock */
	spin_unlock(&files->file_lock);
	__free_fdtable(nfdt);
	spin_lock(&files->file_lock);
	goto out;
	}
	rcu_assign_pointer(files->fdt, nfdt);
	free_fdtable(fdt);
	out:
	return error;
	}

	/*
	* Expand files.
	* Return <0 on error; 0 nothing done; 1 files expanded, we may have blocked.
	* Should be called with the files->file_lock spinlock held for write.
	*/
	int expand_files(struct files_struct *files, int nr)
	{
	int err, expand = 0;
	struct fdtable *fdt;

	fdt = files_fdtable(files);
	if (nr >= fdt->max_fdset \|\| nr >= fdt->max_fds) {
	if (fdt->max_fdset >= NR_OPEN \|\|
	fdt->max_fds >= NR_OPEN \|\| nr >= NR_OPEN) {
	err = -EMFILE;
	goto out;
	}
	expand = 1;
	if ((err = expand_fdtable(files, nr)))
	goto out;
	}
	err = expand;
	out:
	return err;
	}

	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;
	/* Really early - can't use for_each_cpu */
	for (i = 0; i < NR_CPUS; i++)
	fdtable_defer_list_init(i);
	}