/* *  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 = 8 * L1_CACHE_BYTES;  	/* Expand to the max in easy steps */  	while (nfds <= nr) {		nfds = nfds * 2;		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 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;	for_each_possible_cpu(i)		fdtable_defer_list_init(i);}