aio.c 46.5 KB
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/*
 *	An async IO implementation for Linux
 *	Written by Benjamin LaHaise <bcrl@kvack.org>
 *
 *	Implements an efficient asynchronous io interface.
 *
 *	Copyright 2000, 2001, 2002 Red Hat, Inc.  All Rights Reserved.
 *
 *	See ../COPYING for licensing terms.
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/aio_abi.h>
#include <linux/module.h>
#include <linux/syscalls.h>
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#include <linux/uio.h>
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#define DEBUG 0

#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/aio.h>
#include <linux/highmem.h>
#include <linux/workqueue.h>
#include <linux/security.h>
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#include <linux/eventfd.h>
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#include <asm/kmap_types.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>

#if DEBUG > 1
#define dprintk		printk
#else
#define dprintk(x...)	do { ; } while (0)
#endif

/*------ sysctl variables----*/
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static DEFINE_SPINLOCK(aio_nr_lock);
unsigned long aio_nr;		/* current system wide number of aio requests */
unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
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/*----end sysctl variables---*/

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static struct kmem_cache	*kiocb_cachep;
static struct kmem_cache	*kioctx_cachep;
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static struct workqueue_struct *aio_wq;

/* Used for rare fput completion. */
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static void aio_fput_routine(struct work_struct *);
static DECLARE_WORK(fput_work, aio_fput_routine);
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static DEFINE_SPINLOCK(fput_lock);
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static LIST_HEAD(fput_head);
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static void aio_kick_handler(struct work_struct *);
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static void aio_queue_work(struct kioctx *);
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/* aio_setup
 *	Creates the slab caches used by the aio routines, panic on
 *	failure as this is done early during the boot sequence.
 */
static int __init aio_setup(void)
{
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	kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
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	aio_wq = create_workqueue("aio");

	pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));

	return 0;
}

static void aio_free_ring(struct kioctx *ctx)
{
	struct aio_ring_info *info = &ctx->ring_info;
	long i;

	for (i=0; i<info->nr_pages; i++)
		put_page(info->ring_pages[i]);

	if (info->mmap_size) {
		down_write(&ctx->mm->mmap_sem);
		do_munmap(ctx->mm, info->mmap_base, info->mmap_size);
		up_write(&ctx->mm->mmap_sem);
	}

	if (info->ring_pages && info->ring_pages != info->internal_pages)
		kfree(info->ring_pages);
	info->ring_pages = NULL;
	info->nr = 0;
}

static int aio_setup_ring(struct kioctx *ctx)
{
	struct aio_ring *ring;
	struct aio_ring_info *info = &ctx->ring_info;
	unsigned nr_events = ctx->max_reqs;
	unsigned long size;
	int nr_pages;

	/* Compensate for the ring buffer's head/tail overlap entry */
	nr_events += 2;	/* 1 is required, 2 for good luck */

	size = sizeof(struct aio_ring);
	size += sizeof(struct io_event) * nr_events;
	nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;

	if (nr_pages < 0)
		return -EINVAL;

	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);

	info->nr = 0;
	info->ring_pages = info->internal_pages;
	if (nr_pages > AIO_RING_PAGES) {
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		info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
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		if (!info->ring_pages)
			return -ENOMEM;
	}

	info->mmap_size = nr_pages * PAGE_SIZE;
	dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
	down_write(&ctx->mm->mmap_sem);
	info->mmap_base = do_mmap(NULL, 0, info->mmap_size, 
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				  PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE,
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				  0);
	if (IS_ERR((void *)info->mmap_base)) {
		up_write(&ctx->mm->mmap_sem);
		info->mmap_size = 0;
		aio_free_ring(ctx);
		return -EAGAIN;
	}

	dprintk("mmap address: 0x%08lx\n", info->mmap_base);
	info->nr_pages = get_user_pages(current, ctx->mm,
					info->mmap_base, nr_pages, 
					1, 0, info->ring_pages, NULL);
	up_write(&ctx->mm->mmap_sem);

	if (unlikely(info->nr_pages != nr_pages)) {
		aio_free_ring(ctx);
		return -EAGAIN;
	}

	ctx->user_id = info->mmap_base;

	info->nr = nr_events;		/* trusted copy */

	ring = kmap_atomic(info->ring_pages[0], KM_USER0);
	ring->nr = nr_events;	/* user copy */
	ring->id = ctx->user_id;
	ring->head = ring->tail = 0;
	ring->magic = AIO_RING_MAGIC;
	ring->compat_features = AIO_RING_COMPAT_FEATURES;
	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
	ring->header_length = sizeof(struct aio_ring);
	kunmap_atomic(ring, KM_USER0);

	return 0;
}


/* aio_ring_event: returns a pointer to the event at the given index from
 * kmap_atomic(, km).  Release the pointer with put_aio_ring_event();
 */
#define AIO_EVENTS_PER_PAGE	(PAGE_SIZE / sizeof(struct io_event))
#define AIO_EVENTS_FIRST_PAGE	((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
#define AIO_EVENTS_OFFSET	(AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)

#define aio_ring_event(info, nr, km) ({					\
	unsigned pos = (nr) + AIO_EVENTS_OFFSET;			\
	struct io_event *__event;					\
	__event = kmap_atomic(						\
			(info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \
	__event += pos % AIO_EVENTS_PER_PAGE;				\
	__event;							\
})

#define put_aio_ring_event(event, km) do {	\
	struct io_event *__event = (event);	\
	(void)__event;				\
	kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \
} while(0)

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static void ctx_rcu_free(struct rcu_head *head)
{
	struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
	unsigned nr_events = ctx->max_reqs;

	kmem_cache_free(kioctx_cachep, ctx);

	if (nr_events) {
		spin_lock(&aio_nr_lock);
		BUG_ON(aio_nr - nr_events > aio_nr);
		aio_nr -= nr_events;
		spin_unlock(&aio_nr_lock);
	}
}
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/* __put_ioctx
 *	Called when the last user of an aio context has gone away,
 *	and the struct needs to be freed.
 */
static void __put_ioctx(struct kioctx *ctx)
{
	BUG_ON(ctx->reqs_active);

	cancel_delayed_work(&ctx->wq);
	cancel_work_sync(&ctx->wq.work);
	aio_free_ring(ctx);
	mmdrop(ctx->mm);
	ctx->mm = NULL;
	pr_debug("__put_ioctx: freeing %p\n", ctx);
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	call_rcu(&ctx->rcu_head, ctx_rcu_free);
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}

#define get_ioctx(kioctx) do {						\
	BUG_ON(atomic_read(&(kioctx)->users) <= 0);			\
	atomic_inc(&(kioctx)->users);					\
} while (0)
#define put_ioctx(kioctx) do {						\
	BUG_ON(atomic_read(&(kioctx)->users) <= 0);			\
	if (unlikely(atomic_dec_and_test(&(kioctx)->users))) 		\
		__put_ioctx(kioctx);					\
} while (0)

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/* ioctx_alloc
 *	Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
 */
static struct kioctx *ioctx_alloc(unsigned nr_events)
{
	struct mm_struct *mm;
	struct kioctx *ctx;
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	int did_sync = 0;
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	/* Prevent overflows */
	if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
	    (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
		pr_debug("ENOMEM: nr_events too high\n");
		return ERR_PTR(-EINVAL);
	}

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	if ((unsigned long)nr_events > aio_max_nr)
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		return ERR_PTR(-EAGAIN);

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	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
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	if (!ctx)
		return ERR_PTR(-ENOMEM);

	ctx->max_reqs = nr_events;
	mm = ctx->mm = current->mm;
	atomic_inc(&mm->mm_count);

	atomic_set(&ctx->users, 1);
	spin_lock_init(&ctx->ctx_lock);
	spin_lock_init(&ctx->ring_info.ring_lock);
	init_waitqueue_head(&ctx->wait);

	INIT_LIST_HEAD(&ctx->active_reqs);
	INIT_LIST_HEAD(&ctx->run_list);
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	INIT_DELAYED_WORK(&ctx->wq, aio_kick_handler);
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	if (aio_setup_ring(ctx) < 0)
		goto out_freectx;

	/* limit the number of system wide aios */
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	do {
		spin_lock_bh(&aio_nr_lock);
		if (aio_nr + nr_events > aio_max_nr ||
		    aio_nr + nr_events < aio_nr)
			ctx->max_reqs = 0;
		else
			aio_nr += ctx->max_reqs;
		spin_unlock_bh(&aio_nr_lock);
		if (ctx->max_reqs || did_sync)
			break;

		/* wait for rcu callbacks to have completed before giving up */
		synchronize_rcu();
		did_sync = 1;
		ctx->max_reqs = nr_events;
	} while (1);

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	if (ctx->max_reqs == 0)
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		goto out_cleanup;

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	/* now link into global list. */
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	spin_lock(&mm->ioctx_lock);
	hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
	spin_unlock(&mm->ioctx_lock);
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	dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
		ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
	return ctx;

out_cleanup:
	__put_ioctx(ctx);
	return ERR_PTR(-EAGAIN);

out_freectx:
	mmdrop(mm);
	kmem_cache_free(kioctx_cachep, ctx);
	ctx = ERR_PTR(-ENOMEM);

	dprintk("aio: error allocating ioctx %p\n", ctx);
	return ctx;
}

/* aio_cancel_all
 *	Cancels all outstanding aio requests on an aio context.  Used 
 *	when the processes owning a context have all exited to encourage 
 *	the rapid destruction of the kioctx.
 */
static void aio_cancel_all(struct kioctx *ctx)
{
	int (*cancel)(struct kiocb *, struct io_event *);
	struct io_event res;
	spin_lock_irq(&ctx->ctx_lock);
	ctx->dead = 1;
	while (!list_empty(&ctx->active_reqs)) {
		struct list_head *pos = ctx->active_reqs.next;
		struct kiocb *iocb = list_kiocb(pos);
		list_del_init(&iocb->ki_list);
		cancel = iocb->ki_cancel;
		kiocbSetCancelled(iocb);
		if (cancel) {
			iocb->ki_users++;
			spin_unlock_irq(&ctx->ctx_lock);
			cancel(iocb, &res);
			spin_lock_irq(&ctx->ctx_lock);
		}
	}
	spin_unlock_irq(&ctx->ctx_lock);
}

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static void wait_for_all_aios(struct kioctx *ctx)
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{
	struct task_struct *tsk = current;
	DECLARE_WAITQUEUE(wait, tsk);

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	spin_lock_irq(&ctx->ctx_lock);
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	if (!ctx->reqs_active)
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		goto out;
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	add_wait_queue(&ctx->wait, &wait);
	set_task_state(tsk, TASK_UNINTERRUPTIBLE);
	while (ctx->reqs_active) {
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		spin_unlock_irq(&ctx->ctx_lock);
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		io_schedule();
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		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
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		spin_lock_irq(&ctx->ctx_lock);
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	}
	__set_task_state(tsk, TASK_RUNNING);
	remove_wait_queue(&ctx->wait, &wait);
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out:
	spin_unlock_irq(&ctx->ctx_lock);
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}

/* wait_on_sync_kiocb:
 *	Waits on the given sync kiocb to complete.
 */
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ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
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{
	while (iocb->ki_users) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (!iocb->ki_users)
			break;
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		io_schedule();
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	}
	__set_current_state(TASK_RUNNING);
	return iocb->ki_user_data;
}

/* exit_aio: called when the last user of mm goes away.  At this point, 
 * there is no way for any new requests to be submited or any of the 
 * io_* syscalls to be called on the context.  However, there may be 
 * outstanding requests which hold references to the context; as they 
 * go away, they will call put_ioctx and release any pinned memory
 * associated with the request (held via struct page * references).
 */
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void exit_aio(struct mm_struct *mm)
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{
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	struct kioctx *ctx;

	while (!hlist_empty(&mm->ioctx_list)) {
		ctx = hlist_entry(mm->ioctx_list.first, struct kioctx, list);
		hlist_del_rcu(&ctx->list);

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		aio_cancel_all(ctx);

		wait_for_all_aios(ctx);
		/*
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		 * Ensure we don't leave the ctx on the aio_wq
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		 */
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		cancel_work_sync(&ctx->wq.work);
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		if (1 != atomic_read(&ctx->users))
			printk(KERN_DEBUG
				"exit_aio:ioctx still alive: %d %d %d\n",
				atomic_read(&ctx->users), ctx->dead,
				ctx->reqs_active);
		put_ioctx(ctx);
	}
}

/* aio_get_req
 *	Allocate a slot for an aio request.  Increments the users count
 * of the kioctx so that the kioctx stays around until all requests are
 * complete.  Returns NULL if no requests are free.
 *
 * Returns with kiocb->users set to 2.  The io submit code path holds
 * an extra reference while submitting the i/o.
 * This prevents races between the aio code path referencing the
 * req (after submitting it) and aio_complete() freeing the req.
 */
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static struct kiocb *__aio_get_req(struct kioctx *ctx)
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{
	struct kiocb *req = NULL;
	struct aio_ring *ring;
	int okay = 0;

	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
	if (unlikely(!req))
		return NULL;

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	req->ki_flags = 0;
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	req->ki_users = 2;
	req->ki_key = 0;
	req->ki_ctx = ctx;
	req->ki_cancel = NULL;
	req->ki_retry = NULL;
	req->ki_dtor = NULL;
	req->private = NULL;
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	req->ki_iovec = NULL;
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	INIT_LIST_HEAD(&req->ki_run_list);
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	req->ki_eventfd = NULL;
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	/* Check if the completion queue has enough free space to
	 * accept an event from this io.
	 */
	spin_lock_irq(&ctx->ctx_lock);
	ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0);
	if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) {
		list_add(&req->ki_list, &ctx->active_reqs);
		ctx->reqs_active++;
		okay = 1;
	}
	kunmap_atomic(ring, KM_USER0);
	spin_unlock_irq(&ctx->ctx_lock);

	if (!okay) {
		kmem_cache_free(kiocb_cachep, req);
		req = NULL;
	}

	return req;
}

static inline struct kiocb *aio_get_req(struct kioctx *ctx)
{
	struct kiocb *req;
	/* Handle a potential starvation case -- should be exceedingly rare as 
	 * requests will be stuck on fput_head only if the aio_fput_routine is 
	 * delayed and the requests were the last user of the struct file.
	 */
	req = __aio_get_req(ctx);
	if (unlikely(NULL == req)) {
		aio_fput_routine(NULL);
		req = __aio_get_req(ctx);
	}
	return req;
}

static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
{
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	assert_spin_locked(&ctx->ctx_lock);

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	if (req->ki_dtor)
		req->ki_dtor(req);
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	if (req->ki_iovec != &req->ki_inline_vec)
		kfree(req->ki_iovec);
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	kmem_cache_free(kiocb_cachep, req);
	ctx->reqs_active--;

	if (unlikely(!ctx->reqs_active && ctx->dead))
		wake_up(&ctx->wait);
}

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static void aio_fput_routine(struct work_struct *data)
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{
	spin_lock_irq(&fput_lock);
	while (likely(!list_empty(&fput_head))) {
		struct kiocb *req = list_kiocb(fput_head.next);
		struct kioctx *ctx = req->ki_ctx;

		list_del(&req->ki_list);
		spin_unlock_irq(&fput_lock);

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		/* Complete the fput(s) */
		if (req->ki_filp != NULL)
			__fput(req->ki_filp);
		if (req->ki_eventfd != NULL)
			__fput(req->ki_eventfd);
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		/* Link the iocb into the context's free list */
		spin_lock_irq(&ctx->ctx_lock);
		really_put_req(ctx, req);
		spin_unlock_irq(&ctx->ctx_lock);

		put_ioctx(ctx);
		spin_lock_irq(&fput_lock);
	}
	spin_unlock_irq(&fput_lock);
}

/* __aio_put_req
 *	Returns true if this put was the last user of the request.
 */
static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
{
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	int schedule_putreq = 0;

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	dprintk(KERN_DEBUG "aio_put(%p): f_count=%ld\n",
		req, atomic_long_read(&req->ki_filp->f_count));
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	assert_spin_locked(&ctx->ctx_lock);

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	req->ki_users--;
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	BUG_ON(req->ki_users < 0);
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	if (likely(req->ki_users))
		return 0;
	list_del(&req->ki_list);		/* remove from active_reqs */
	req->ki_cancel = NULL;
	req->ki_retry = NULL;

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	/*
	 * Try to optimize the aio and eventfd file* puts, by avoiding to
	 * schedule work in case it is not __fput() time. In normal cases,
	 * we would not be holding the last reference to the file*, so
	 * this function will be executed w/out any aio kthread wakeup.
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	 */
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	if (unlikely(atomic_long_dec_and_test(&req->ki_filp->f_count)))
		schedule_putreq++;
	else
		req->ki_filp = NULL;
	if (req->ki_eventfd != NULL) {
		if (unlikely(atomic_long_dec_and_test(&req->ki_eventfd->f_count)))
			schedule_putreq++;
		else
			req->ki_eventfd = NULL;
	}
	if (unlikely(schedule_putreq)) {
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		get_ioctx(ctx);
		spin_lock(&fput_lock);
		list_add(&req->ki_list, &fput_head);
		spin_unlock(&fput_lock);
		queue_work(aio_wq, &fput_work);
	} else
		really_put_req(ctx, req);
	return 1;
}

/* aio_put_req
 *	Returns true if this put was the last user of the kiocb,
 *	false if the request is still in use.
 */
577
int aio_put_req(struct kiocb *req)
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{
	struct kioctx *ctx = req->ki_ctx;
	int ret;
	spin_lock_irq(&ctx->ctx_lock);
	ret = __aio_put_req(ctx, req);
	spin_unlock_irq(&ctx->ctx_lock);
	return ret;
}

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Adrian Bunk 已提交
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static struct kioctx *lookup_ioctx(unsigned long ctx_id)
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{
J
Jens Axboe 已提交
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	struct mm_struct *mm = current->mm;
590
	struct kioctx *ctx, *ret = NULL;
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591
	struct hlist_node *n;
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592

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	rcu_read_lock();

	hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) {
		if (ctx->user_id == ctx_id && !ctx->dead) {
			get_ioctx(ctx);
598
			ret = ctx;
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			break;
		}
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601
	}
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603
	rcu_read_unlock();
604
	return ret;
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}

/*
 * use_mm
 *	Makes the calling kernel thread take on the specified
 *	mm context.
 *	Called by the retry thread execute retries within the
 *	iocb issuer's mm context, so that copy_from/to_user
 *	operations work seamlessly for aio.
 *	(Note: this routine is intended to be called only
 *	from a kernel thread context)
 */
static void use_mm(struct mm_struct *mm)
{
	struct mm_struct *active_mm;
	struct task_struct *tsk = current;

	task_lock(tsk);
	active_mm = tsk->active_mm;
	atomic_inc(&mm->mm_count);
	tsk->mm = mm;
	tsk->active_mm = mm;
627
	switch_mm(active_mm, mm, tsk);
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	task_unlock(tsk);

	mmdrop(active_mm);
}

/*
 * unuse_mm
 *	Reverses the effect of use_mm, i.e. releases the
 *	specified mm context which was earlier taken on
 *	by the calling kernel thread
 *	(Note: this routine is intended to be called only
 *	from a kernel thread context)
 */
641
static void unuse_mm(struct mm_struct *mm)
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{
	struct task_struct *tsk = current;

	task_lock(tsk);
	tsk->mm = NULL;
	/* active_mm is still 'mm' */
	enter_lazy_tlb(mm, tsk);
	task_unlock(tsk);
}

/*
 * Queue up a kiocb to be retried. Assumes that the kiocb
 * has already been marked as kicked, and places it on
 * the retry run list for the corresponding ioctx, if it
 * isn't already queued. Returns 1 if it actually queued
 * the kiocb (to tell the caller to activate the work
 * queue to process it), or 0, if it found that it was
 * already queued.
 */
static inline int __queue_kicked_iocb(struct kiocb *iocb)
{
	struct kioctx *ctx = iocb->ki_ctx;

665 666
	assert_spin_locked(&ctx->ctx_lock);

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	if (list_empty(&iocb->ki_run_list)) {
		list_add_tail(&iocb->ki_run_list,
			&ctx->run_list);
		return 1;
	}
	return 0;
}

/* aio_run_iocb
 *	This is the core aio execution routine. It is
 *	invoked both for initial i/o submission and
 *	subsequent retries via the aio_kick_handler.
 *	Expects to be invoked with iocb->ki_ctx->lock
A
Andreas Mohr 已提交
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 *	already held. The lock is released and reacquired
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 *	as needed during processing.
 *
 * Calls the iocb retry method (already setup for the
 * iocb on initial submission) for operation specific
 * handling, but takes care of most of common retry
 * execution details for a given iocb. The retry method
 * needs to be non-blocking as far as possible, to avoid
 * holding up other iocbs waiting to be serviced by the
 * retry kernel thread.
 *
 * The trickier parts in this code have to do with
 * ensuring that only one retry instance is in progress
 * for a given iocb at any time. Providing that guarantee
 * simplifies the coding of individual aio operations as
 * it avoids various potential races.
 */
static ssize_t aio_run_iocb(struct kiocb *iocb)
{
	struct kioctx	*ctx = iocb->ki_ctx;
	ssize_t (*retry)(struct kiocb *);
	ssize_t ret;

	if (!(retry = iocb->ki_retry)) {
		printk("aio_run_iocb: iocb->ki_retry = NULL\n");
		return 0;
	}

	/*
	 * We don't want the next retry iteration for this
	 * operation to start until this one has returned and
	 * updated the iocb state. However, wait_queue functions
	 * can trigger a kick_iocb from interrupt context in the
	 * meantime, indicating that data is available for the next
	 * iteration. We want to remember that and enable the
	 * next retry iteration _after_ we are through with
	 * this one.
	 *
	 * So, in order to be able to register a "kick", but
	 * prevent it from being queued now, we clear the kick
	 * flag, but make the kick code *think* that the iocb is
	 * still on the run list until we are actually done.
	 * When we are done with this iteration, we check if
	 * the iocb was kicked in the meantime and if so, queue
	 * it up afresh.
	 */

	kiocbClearKicked(iocb);

	/*
	 * This is so that aio_complete knows it doesn't need to
	 * pull the iocb off the run list (We can't just call
	 * INIT_LIST_HEAD because we don't want a kick_iocb to
	 * queue this on the run list yet)
	 */
	iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
	spin_unlock_irq(&ctx->ctx_lock);

	/* Quit retrying if the i/o has been cancelled */
	if (kiocbIsCancelled(iocb)) {
		ret = -EINTR;
		aio_complete(iocb, ret, 0);
		/* must not access the iocb after this */
		goto out;
	}

	/*
	 * Now we are all set to call the retry method in async
748
	 * context.
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	 */
	ret = retry(iocb);

752 753 754
	if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
		BUG_ON(!list_empty(&iocb->ki_wait.task_list));
		aio_complete(iocb, ret, 0);
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	}
out:
	spin_lock_irq(&ctx->ctx_lock);

	if (-EIOCBRETRY == ret) {
		/*
		 * OK, now that we are done with this iteration
		 * and know that there is more left to go,
		 * this is where we let go so that a subsequent
		 * "kick" can start the next iteration
		 */

		/* will make __queue_kicked_iocb succeed from here on */
		INIT_LIST_HEAD(&iocb->ki_run_list);
		/* we must queue the next iteration ourselves, if it
		 * has already been kicked */
		if (kiocbIsKicked(iocb)) {
			__queue_kicked_iocb(iocb);
773 774 775 776 777 778 779 780

			/*
			 * __queue_kicked_iocb will always return 1 here, because
			 * iocb->ki_run_list is empty at this point so it should
			 * be safe to unconditionally queue the context into the
			 * work queue.
			 */
			aio_queue_work(ctx);
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		}
	}
	return ret;
}

/*
 * __aio_run_iocbs:
 * 	Process all pending retries queued on the ioctx
 * 	run list.
 * Assumes it is operating within the aio issuer's mm
791
 * context.
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 */
static int __aio_run_iocbs(struct kioctx *ctx)
{
	struct kiocb *iocb;
796
	struct list_head run_list;
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798 799
	assert_spin_locked(&ctx->ctx_lock);

800
	list_replace_init(&ctx->run_list, &run_list);
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	while (!list_empty(&run_list)) {
		iocb = list_entry(run_list.next, struct kiocb,
			ki_run_list);
		list_del(&iocb->ki_run_list);
		/*
		 * Hold an extra reference while retrying i/o.
		 */
		iocb->ki_users++;       /* grab extra reference */
		aio_run_iocb(iocb);
810
		__aio_put_req(ctx, iocb);
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 	}
	if (!list_empty(&ctx->run_list))
		return 1;
	return 0;
}

static void aio_queue_work(struct kioctx * ctx)
{
	unsigned long timeout;
	/*
	 * if someone is waiting, get the work started right
	 * away, otherwise, use a longer delay
	 */
	smp_mb();
	if (waitqueue_active(&ctx->wait))
		timeout = 1;
	else
		timeout = HZ/10;
	queue_delayed_work(aio_wq, &ctx->wq, timeout);
}


/*
 * aio_run_iocbs:
 * 	Process all pending retries queued on the ioctx
 * 	run list.
 * Assumes it is operating within the aio issuer's mm
 * context.
 */
static inline void aio_run_iocbs(struct kioctx *ctx)
{
	int requeue;

	spin_lock_irq(&ctx->ctx_lock);

	requeue = __aio_run_iocbs(ctx);
	spin_unlock_irq(&ctx->ctx_lock);
	if (requeue)
		aio_queue_work(ctx);
}

/*
 * just like aio_run_iocbs, but keeps running them until
 * the list stays empty
 */
static inline void aio_run_all_iocbs(struct kioctx *ctx)
{
	spin_lock_irq(&ctx->ctx_lock);
	while (__aio_run_iocbs(ctx))
		;
	spin_unlock_irq(&ctx->ctx_lock);
}

/*
 * aio_kick_handler:
 * 	Work queue handler triggered to process pending
 * 	retries on an ioctx. Takes on the aio issuer's
 *	mm context before running the iocbs, so that
 *	copy_xxx_user operates on the issuer's address
 *      space.
 * Run on aiod's context.
 */
873
static void aio_kick_handler(struct work_struct *work)
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{
875
	struct kioctx *ctx = container_of(work, struct kioctx, wq.work);
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	mm_segment_t oldfs = get_fs();
877
	struct mm_struct *mm;
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	int requeue;

	set_fs(USER_DS);
	use_mm(ctx->mm);
	spin_lock_irq(&ctx->ctx_lock);
	requeue =__aio_run_iocbs(ctx);
884
	mm = ctx->mm;
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	spin_unlock_irq(&ctx->ctx_lock);
886
 	unuse_mm(mm);
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	set_fs(oldfs);
	/*
	 * we're in a worker thread already, don't use queue_delayed_work,
	 */
	if (requeue)
892
		queue_delayed_work(aio_wq, &ctx->wq, 0);
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}


/*
 * Called by kick_iocb to queue the kiocb for retry
 * and if required activate the aio work queue to process
 * it
 */
901
static void try_queue_kicked_iocb(struct kiocb *iocb)
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{
 	struct kioctx	*ctx = iocb->ki_ctx;
	unsigned long flags;
	int run = 0;

907 908 909 910 911 912
	/* We're supposed to be the only path putting the iocb back on the run
	 * list.  If we find that the iocb is *back* on a wait queue already
	 * than retry has happened before we could queue the iocb.  This also
	 * means that the retry could have completed and freed our iocb, no
	 * good. */
	BUG_ON((!list_empty(&iocb->ki_wait.task_list)));
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	spin_lock_irqsave(&ctx->ctx_lock, flags);
915 916 917 918
	/* set this inside the lock so that we can't race with aio_run_iocb()
	 * testing it and putting the iocb on the run list under the lock */
	if (!kiocbTryKick(iocb))
		run = __queue_kicked_iocb(iocb);
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	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
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	if (run)
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		aio_queue_work(ctx);
}

/*
 * kick_iocb:
 *      Called typically from a wait queue callback context
 *      (aio_wake_function) to trigger a retry of the iocb.
 *      The retry is usually executed by aio workqueue
 *      threads (See aio_kick_handler).
 */
931
void kick_iocb(struct kiocb *iocb)
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{
	/* sync iocbs are easy: they can only ever be executing from a 
	 * single context. */
	if (is_sync_kiocb(iocb)) {
		kiocbSetKicked(iocb);
	        wake_up_process(iocb->ki_obj.tsk);
		return;
	}

941
	try_queue_kicked_iocb(iocb);
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}
EXPORT_SYMBOL(kick_iocb);

/* aio_complete
 *	Called when the io request on the given iocb is complete.
 *	Returns true if this is the last user of the request.  The 
 *	only other user of the request can be the cancellation code.
 */
950
int aio_complete(struct kiocb *iocb, long res, long res2)
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{
	struct kioctx	*ctx = iocb->ki_ctx;
	struct aio_ring_info	*info;
	struct aio_ring	*ring;
	struct io_event	*event;
	unsigned long	flags;
	unsigned long	tail;
	int		ret;

960 961 962 963 964 965
	/*
	 * Special case handling for sync iocbs:
	 *  - events go directly into the iocb for fast handling
	 *  - the sync task with the iocb in its stack holds the single iocb
	 *    ref, no other paths have a way to get another ref
	 *  - the sync task helpfully left a reference to itself in the iocb
L
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	 */
	if (is_sync_kiocb(iocb)) {
968
		BUG_ON(iocb->ki_users != 1);
L
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969
		iocb->ki_user_data = res;
970
		iocb->ki_users = 0;
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		wake_up_process(iocb->ki_obj.tsk);
972
		return 1;
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	}

	info = &ctx->ring_info;

	/* add a completion event to the ring buffer.
	 * must be done holding ctx->ctx_lock to prevent
	 * other code from messing with the tail
	 * pointer since we might be called from irq
	 * context.
	 */
	spin_lock_irqsave(&ctx->ctx_lock, flags);

	if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
		list_del_init(&iocb->ki_run_list);

	/*
	 * cancelled requests don't get events, userland was given one
	 * when the event got cancelled.
	 */
	if (kiocbIsCancelled(iocb))
		goto put_rq;

	ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);

	tail = info->tail;
	event = aio_ring_event(info, tail, KM_IRQ0);
999 1000
	if (++tail >= info->nr)
		tail = 0;
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	event->obj = (u64)(unsigned long)iocb->ki_obj.user;
	event->data = iocb->ki_user_data;
	event->res = res;
	event->res2 = res2;

	dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
		ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
		res, res2);

	/* after flagging the request as done, we
	 * must never even look at it again
	 */
	smp_wmb();	/* make event visible before updating tail */

	info->tail = tail;
	ring->tail = tail;

	put_aio_ring_event(event, KM_IRQ0);
	kunmap_atomic(ring, KM_IRQ1);

	pr_debug("added to ring %p at [%lu]\n", iocb, tail);
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	/*
	 * Check if the user asked us to deliver the result through an
	 * eventfd. The eventfd_signal() function is safe to be called
	 * from IRQ context.
	 */
1029
	if (iocb->ki_eventfd != NULL)
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		eventfd_signal(iocb->ki_eventfd, 1);

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put_rq:
	/* everything turned out well, dispose of the aiocb. */
	ret = __aio_put_req(ctx, iocb);

1036 1037 1038 1039 1040 1041 1042 1043
	/*
	 * We have to order our ring_info tail store above and test
	 * of the wait list below outside the wait lock.  This is
	 * like in wake_up_bit() where clearing a bit has to be
	 * ordered with the unlocked test.
	 */
	smp_mb();

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	if (waitqueue_active(&ctx->wait))
		wake_up(&ctx->wait);

1047
	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
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	return ret;
}

/* aio_read_evt
 *	Pull an event off of the ioctx's event ring.  Returns the number of 
 *	events fetched (0 or 1 ;-)
 *	FIXME: make this use cmpxchg.
 *	TODO: make the ringbuffer user mmap()able (requires FIXME).
 */
static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent)
{
	struct aio_ring_info *info = &ioctx->ring_info;
	struct aio_ring *ring;
	unsigned long head;
	int ret = 0;

	ring = kmap_atomic(info->ring_pages[0], KM_USER0);
	dprintk("in aio_read_evt h%lu t%lu m%lu\n",
		 (unsigned long)ring->head, (unsigned long)ring->tail,
		 (unsigned long)ring->nr);

	if (ring->head == ring->tail)
		goto out;

	spin_lock(&info->ring_lock);

	head = ring->head % info->nr;
	if (head != ring->tail) {
		struct io_event *evp = aio_ring_event(info, head, KM_USER1);
		*ent = *evp;
		head = (head + 1) % info->nr;
		smp_mb(); /* finish reading the event before updatng the head */
		ring->head = head;
		ret = 1;
		put_aio_ring_event(evp, KM_USER1);
	}
	spin_unlock(&info->ring_lock);

out:
	kunmap_atomic(ring, KM_USER0);
	dprintk("leaving aio_read_evt: %d  h%lu t%lu\n", ret,
		 (unsigned long)ring->head, (unsigned long)ring->tail);
	return ret;
}

struct aio_timeout {
	struct timer_list	timer;
	int			timed_out;
	struct task_struct	*p;
};

static void timeout_func(unsigned long data)
{
	struct aio_timeout *to = (struct aio_timeout *)data;

	to->timed_out = 1;
	wake_up_process(to->p);
}

static inline void init_timeout(struct aio_timeout *to)
{
1109
	setup_timer_on_stack(&to->timer, timeout_func, (unsigned long) to);
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	to->timed_out = 0;
	to->p = current;
}

static inline void set_timeout(long start_jiffies, struct aio_timeout *to,
			       const struct timespec *ts)
{
	to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
	if (time_after(to->timer.expires, jiffies))
		add_timer(&to->timer);
	else
		to->timed_out = 1;
}

static inline void clear_timeout(struct aio_timeout *to)
{
	del_singleshot_timer_sync(&to->timer);
}

static int read_events(struct kioctx *ctx,
			long min_nr, long nr,
			struct io_event __user *event,
			struct timespec __user *timeout)
{
	long			start_jiffies = jiffies;
	struct task_struct	*tsk = current;
	DECLARE_WAITQUEUE(wait, tsk);
	int			ret;
	int			i = 0;
	struct io_event		ent;
	struct aio_timeout	to;
	int			retry = 0;

	/* needed to zero any padding within an entry (there shouldn't be 
	 * any, but C is fun!
	 */
	memset(&ent, 0, sizeof(ent));
retry:
	ret = 0;
	while (likely(i < nr)) {
		ret = aio_read_evt(ctx, &ent);
		if (unlikely(ret <= 0))
			break;

		dprintk("read event: %Lx %Lx %Lx %Lx\n",
			ent.data, ent.obj, ent.res, ent.res2);

		/* Could we split the check in two? */
		ret = -EFAULT;
		if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
			dprintk("aio: lost an event due to EFAULT.\n");
			break;
		}
		ret = 0;

		/* Good, event copied to userland, update counts. */
		event ++;
		i ++;
	}

	if (min_nr <= i)
		return i;
	if (ret)
		return ret;

	/* End fast path */

	/* racey check, but it gets redone */
	if (!retry && unlikely(!list_empty(&ctx->run_list))) {
		retry = 1;
		aio_run_all_iocbs(ctx);
		goto retry;
	}

	init_timeout(&to);
	if (timeout) {
		struct timespec	ts;
		ret = -EFAULT;
		if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
			goto out;

		set_timeout(start_jiffies, &to, &ts);
	}

	while (likely(i < nr)) {
		add_wait_queue_exclusive(&ctx->wait, &wait);
		do {
			set_task_state(tsk, TASK_INTERRUPTIBLE);
			ret = aio_read_evt(ctx, &ent);
			if (ret)
				break;
			if (min_nr <= i)
				break;
1203 1204 1205 1206
			if (unlikely(ctx->dead)) {
				ret = -EINVAL;
				break;
			}
L
Linus Torvalds 已提交
1207 1208
			if (to.timed_out)	/* Only check after read evt */
				break;
1209 1210 1211 1212 1213 1214
			/* Try to only show up in io wait if there are ops
			 *  in flight */
			if (ctx->reqs_active)
				io_schedule();
			else
				schedule();
L
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1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241
			if (signal_pending(tsk)) {
				ret = -EINTR;
				break;
			}
			/*ret = aio_read_evt(ctx, &ent);*/
		} while (1) ;

		set_task_state(tsk, TASK_RUNNING);
		remove_wait_queue(&ctx->wait, &wait);

		if (unlikely(ret <= 0))
			break;

		ret = -EFAULT;
		if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
			dprintk("aio: lost an event due to EFAULT.\n");
			break;
		}

		/* Good, event copied to userland, update counts. */
		event ++;
		i ++;
	}

	if (timeout)
		clear_timeout(&to);
out:
1242
	destroy_timer_on_stack(&to.timer);
L
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1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254
	return i ? i : ret;
}

/* Take an ioctx and remove it from the list of ioctx's.  Protects 
 * against races with itself via ->dead.
 */
static void io_destroy(struct kioctx *ioctx)
{
	struct mm_struct *mm = current->mm;
	int was_dead;

	/* delete the entry from the list is someone else hasn't already */
J
Jens Axboe 已提交
1255
	spin_lock(&mm->ioctx_lock);
L
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1256 1257
	was_dead = ioctx->dead;
	ioctx->dead = 1;
J
Jens Axboe 已提交
1258 1259
	hlist_del_rcu(&ioctx->list);
	spin_unlock(&mm->ioctx_lock);
L
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1260 1261 1262 1263 1264 1265 1266

	dprintk("aio_release(%p)\n", ioctx);
	if (likely(!was_dead))
		put_ioctx(ioctx);	/* twice for the list */

	aio_cancel_all(ioctx);
	wait_for_all_aios(ioctx);
1267 1268 1269 1270 1271 1272 1273

	/*
	 * Wake up any waiters.  The setting of ctx->dead must be seen
	 * by other CPUs at this point.  Right now, we rely on the
	 * locking done by the above calls to ensure this consistency.
	 */
	wake_up(&ioctx->wait);
L
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	put_ioctx(ioctx);	/* once for the lookup */
}

/* sys_io_setup:
 *	Create an aio_context capable of receiving at least nr_events.
 *	ctxp must not point to an aio_context that already exists, and
 *	must be initialized to 0 prior to the call.  On successful
 *	creation of the aio_context, *ctxp is filled in with the resulting 
 *	handle.  May fail with -EINVAL if *ctxp is not initialized,
 *	if the specified nr_events exceeds internal limits.  May fail 
 *	with -EAGAIN if the specified nr_events exceeds the user's limit 
 *	of available events.  May fail with -ENOMEM if insufficient kernel
 *	resources are available.  May fail with -EFAULT if an invalid
 *	pointer is passed for ctxp.  Will fail with -ENOSYS if not
 *	implemented.
 */
1290
SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
L
Linus Torvalds 已提交
1291 1292 1293 1294 1295 1296 1297 1298 1299 1300
{
	struct kioctx *ioctx = NULL;
	unsigned long ctx;
	long ret;

	ret = get_user(ctx, ctxp);
	if (unlikely(ret))
		goto out;

	ret = -EINVAL;
1301 1302 1303
	if (unlikely(ctx || nr_events == 0)) {
		pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
		         ctx, nr_events);
L
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		goto out;
	}

	ioctx = ioctx_alloc(nr_events);
	ret = PTR_ERR(ioctx);
	if (!IS_ERR(ioctx)) {
		ret = put_user(ioctx->user_id, ctxp);
		if (!ret)
			return 0;

		get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
		io_destroy(ioctx);
	}

out:
	return ret;
}

/* sys_io_destroy:
 *	Destroy the aio_context specified.  May cancel any outstanding 
 *	AIOs and block on completion.  Will fail with -ENOSYS if not
 *	implemented.  May fail with -EFAULT if the context pointed to
 *	is invalid.
 */
1328
SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
L
Linus Torvalds 已提交
1329 1330 1331 1332 1333 1334 1335 1336 1337 1338
{
	struct kioctx *ioctx = lookup_ioctx(ctx);
	if (likely(NULL != ioctx)) {
		io_destroy(ioctx);
		return 0;
	}
	pr_debug("EINVAL: io_destroy: invalid context id\n");
	return -EINVAL;
}

B
Badari Pulavarty 已提交
1339
static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
L
Linus Torvalds 已提交
1340
{
B
Badari Pulavarty 已提交
1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353
	struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];

	BUG_ON(ret <= 0);

	while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
		ssize_t this = min((ssize_t)iov->iov_len, ret);
		iov->iov_base += this;
		iov->iov_len -= this;
		iocb->ki_left -= this;
		ret -= this;
		if (iov->iov_len == 0) {
			iocb->ki_cur_seg++;
			iov++;
1354
		}
B
Badari Pulavarty 已提交
1355
	}
L
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B
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1357 1358 1359
	/* the caller should not have done more io than what fit in
	 * the remaining iovecs */
	BUG_ON(ret > 0 && iocb->ki_left == 0);
L
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}

B
Badari Pulavarty 已提交
1362
static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
L
Linus Torvalds 已提交
1363 1364
{
	struct file *file = iocb->ki_filp;
B
Badari Pulavarty 已提交
1365 1366 1367 1368
	struct address_space *mapping = file->f_mapping;
	struct inode *inode = mapping->host;
	ssize_t (*rw_op)(struct kiocb *, const struct iovec *,
			 unsigned long, loff_t);
L
Linus Torvalds 已提交
1369
	ssize_t ret = 0;
B
Badari Pulavarty 已提交
1370 1371 1372 1373 1374 1375 1376 1377 1378 1379
	unsigned short opcode;

	if ((iocb->ki_opcode == IOCB_CMD_PREADV) ||
		(iocb->ki_opcode == IOCB_CMD_PREAD)) {
		rw_op = file->f_op->aio_read;
		opcode = IOCB_CMD_PREADV;
	} else {
		rw_op = file->f_op->aio_write;
		opcode = IOCB_CMD_PWRITEV;
	}
L
Linus Torvalds 已提交
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1381 1382 1383 1384
	/* This matches the pread()/pwrite() logic */
	if (iocb->ki_pos < 0)
		return -EINVAL;

1385
	do {
B
Badari Pulavarty 已提交
1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396
		ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
			    iocb->ki_nr_segs - iocb->ki_cur_seg,
			    iocb->ki_pos);
		if (ret > 0)
			aio_advance_iovec(iocb, ret);

	/* retry all partial writes.  retry partial reads as long as its a
	 * regular file. */
	} while (ret > 0 && iocb->ki_left > 0 &&
		 (opcode == IOCB_CMD_PWRITEV ||
		  (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
L
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B
Badari Pulavarty 已提交
1398 1399
	/* This means we must have transferred all that we could */
	/* No need to retry anymore */
L
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1400 1401 1402
	if ((ret == 0) || (iocb->ki_left == 0))
		ret = iocb->ki_nbytes - iocb->ki_left;

1403 1404 1405 1406 1407 1408 1409
	/* If we managed to write some out we return that, rather than
	 * the eventual error. */
	if (opcode == IOCB_CMD_PWRITEV
	    && ret < 0 && ret != -EIOCBQUEUED && ret != -EIOCBRETRY
	    && iocb->ki_nbytes - iocb->ki_left)
		ret = iocb->ki_nbytes - iocb->ki_left;

L
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	return ret;
}

static ssize_t aio_fdsync(struct kiocb *iocb)
{
	struct file *file = iocb->ki_filp;
	ssize_t ret = -EINVAL;

	if (file->f_op->aio_fsync)
		ret = file->f_op->aio_fsync(iocb, 1);
	return ret;
}

static ssize_t aio_fsync(struct kiocb *iocb)
{
	struct file *file = iocb->ki_filp;
	ssize_t ret = -EINVAL;

	if (file->f_op->aio_fsync)
		ret = file->f_op->aio_fsync(iocb, 0);
	return ret;
}

B
Badari Pulavarty 已提交
1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463
static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb)
{
	ssize_t ret;

	ret = rw_copy_check_uvector(type, (struct iovec __user *)kiocb->ki_buf,
				    kiocb->ki_nbytes, 1,
				    &kiocb->ki_inline_vec, &kiocb->ki_iovec);
	if (ret < 0)
		goto out;

	kiocb->ki_nr_segs = kiocb->ki_nbytes;
	kiocb->ki_cur_seg = 0;
	/* ki_nbytes/left now reflect bytes instead of segs */
	kiocb->ki_nbytes = ret;
	kiocb->ki_left = ret;

	ret = 0;
out:
	return ret;
}

static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
{
	kiocb->ki_iovec = &kiocb->ki_inline_vec;
	kiocb->ki_iovec->iov_base = kiocb->ki_buf;
	kiocb->ki_iovec->iov_len = kiocb->ki_left;
	kiocb->ki_nr_segs = 1;
	kiocb->ki_cur_seg = 0;
	return 0;
}

L
Linus Torvalds 已提交
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/*
 * aio_setup_iocb:
 *	Performs the initial checks and aio retry method
 *	setup for the kiocb at the time of io submission.
 */
1469
static ssize_t aio_setup_iocb(struct kiocb *kiocb)
L
Linus Torvalds 已提交
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{
	struct file *file = kiocb->ki_filp;
	ssize_t ret = 0;

	switch (kiocb->ki_opcode) {
	case IOCB_CMD_PREAD:
		ret = -EBADF;
		if (unlikely(!(file->f_mode & FMODE_READ)))
			break;
		ret = -EFAULT;
		if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
			kiocb->ki_left)))
			break;
1483 1484 1485
		ret = security_file_permission(file, MAY_READ);
		if (unlikely(ret))
			break;
B
Badari Pulavarty 已提交
1486 1487 1488
		ret = aio_setup_single_vector(kiocb);
		if (ret)
			break;
L
Linus Torvalds 已提交
1489 1490
		ret = -EINVAL;
		if (file->f_op->aio_read)
B
Badari Pulavarty 已提交
1491
			kiocb->ki_retry = aio_rw_vect_retry;
L
Linus Torvalds 已提交
1492 1493 1494 1495 1496 1497 1498 1499 1500
		break;
	case IOCB_CMD_PWRITE:
		ret = -EBADF;
		if (unlikely(!(file->f_mode & FMODE_WRITE)))
			break;
		ret = -EFAULT;
		if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
			kiocb->ki_left)))
			break;
1501 1502 1503
		ret = security_file_permission(file, MAY_WRITE);
		if (unlikely(ret))
			break;
B
Badari Pulavarty 已提交
1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534
		ret = aio_setup_single_vector(kiocb);
		if (ret)
			break;
		ret = -EINVAL;
		if (file->f_op->aio_write)
			kiocb->ki_retry = aio_rw_vect_retry;
		break;
	case IOCB_CMD_PREADV:
		ret = -EBADF;
		if (unlikely(!(file->f_mode & FMODE_READ)))
			break;
		ret = security_file_permission(file, MAY_READ);
		if (unlikely(ret))
			break;
		ret = aio_setup_vectored_rw(READ, kiocb);
		if (ret)
			break;
		ret = -EINVAL;
		if (file->f_op->aio_read)
			kiocb->ki_retry = aio_rw_vect_retry;
		break;
	case IOCB_CMD_PWRITEV:
		ret = -EBADF;
		if (unlikely(!(file->f_mode & FMODE_WRITE)))
			break;
		ret = security_file_permission(file, MAY_WRITE);
		if (unlikely(ret))
			break;
		ret = aio_setup_vectored_rw(WRITE, kiocb);
		if (ret)
			break;
L
Linus Torvalds 已提交
1535 1536
		ret = -EINVAL;
		if (file->f_op->aio_write)
B
Badari Pulavarty 已提交
1537
			kiocb->ki_retry = aio_rw_vect_retry;
L
Linus Torvalds 已提交
1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
		break;
	case IOCB_CMD_FDSYNC:
		ret = -EINVAL;
		if (file->f_op->aio_fsync)
			kiocb->ki_retry = aio_fdsync;
		break;
	case IOCB_CMD_FSYNC:
		ret = -EINVAL;
		if (file->f_op->aio_fsync)
			kiocb->ki_retry = aio_fsync;
		break;
	default:
		dprintk("EINVAL: io_submit: no operation provided\n");
		ret = -EINVAL;
	}

	if (!kiocb->ki_retry)
		return ret;

	return 0;
}

/*
 * aio_wake_function:
 * 	wait queue callback function for aio notification,
 * 	Simply triggers a retry of the operation via kick_iocb.
 *
 * 	This callback is specified in the wait queue entry in
1566
 *	a kiocb.
L
Linus Torvalds 已提交
1567 1568 1569 1570 1571 1572 1573 1574
 *
 * Note:
 * This routine is executed with the wait queue lock held.
 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests
 * the ioctx lock inside the wait queue lock. This is safe
 * because this callback isn't used for wait queues which
 * are nested inside ioctx lock (i.e. ctx->wait)
 */
1575 1576
static int aio_wake_function(wait_queue_t *wait, unsigned mode,
			     int sync, void *key)
L
Linus Torvalds 已提交
1577 1578 1579 1580 1581 1582 1583 1584
{
	struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait);

	list_del_init(&wait->task_list);
	kick_iocb(iocb);
	return 1;
}

A
Adrian Bunk 已提交
1585
static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
L
Linus Torvalds 已提交
1586 1587 1588 1589 1590 1591 1592
			 struct iocb *iocb)
{
	struct kiocb *req;
	struct file *file;
	ssize_t ret;

	/* enforce forwards compatibility on users */
1593
	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
L
Linus Torvalds 已提交
1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616
		pr_debug("EINVAL: io_submit: reserve field set\n");
		return -EINVAL;
	}

	/* prevent overflows */
	if (unlikely(
	    (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
	    (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
	    ((ssize_t)iocb->aio_nbytes < 0)
	   )) {
		pr_debug("EINVAL: io_submit: overflow check\n");
		return -EINVAL;
	}

	file = fget(iocb->aio_fildes);
	if (unlikely(!file))
		return -EBADF;

	req = aio_get_req(ctx);		/* returns with 2 references to req */
	if (unlikely(!req)) {
		fput(file);
		return -EAGAIN;
	}
Y
Yan Zheng 已提交
1617
	req->ki_filp = file;
1618 1619 1620 1621 1622 1623 1624 1625
	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
		/*
		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
		 * instance of the file* now. The file descriptor must be
		 * an eventfd() fd, and will be signaled for each completed
		 * event using the eventfd_signal() function.
		 */
		req->ki_eventfd = eventfd_fget((int) iocb->aio_resfd);
1626
		if (IS_ERR(req->ki_eventfd)) {
1627
			ret = PTR_ERR(req->ki_eventfd);
1628
			req->ki_eventfd = NULL;
1629 1630 1631
			goto out_put_req;
		}
	}
L
Linus Torvalds 已提交
1632

1633
	ret = put_user(req->ki_key, &user_iocb->aio_key);
L
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1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654
	if (unlikely(ret)) {
		dprintk("EFAULT: aio_key\n");
		goto out_put_req;
	}

	req->ki_obj.user = user_iocb;
	req->ki_user_data = iocb->aio_data;
	req->ki_pos = iocb->aio_offset;

	req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
	req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
	req->ki_opcode = iocb->aio_lio_opcode;
	init_waitqueue_func_entry(&req->ki_wait, aio_wake_function);
	INIT_LIST_HEAD(&req->ki_wait.task_list);

	ret = aio_setup_iocb(req);

	if (ret)
		goto out_put_req;

	spin_lock_irq(&ctx->ctx_lock);
1655 1656
	aio_run_iocb(req);
	if (!list_empty(&ctx->run_list)) {
K
Ken Chen 已提交
1657 1658 1659 1660
		/* drain the run list */
		while (__aio_run_iocbs(ctx))
			;
	}
L
Linus Torvalds 已提交
1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682
	spin_unlock_irq(&ctx->ctx_lock);
	aio_put_req(req);	/* drop extra ref to req */
	return 0;

out_put_req:
	aio_put_req(req);	/* drop extra ref to req */
	aio_put_req(req);	/* drop i/o ref to req */
	return ret;
}

/* sys_io_submit:
 *	Queue the nr iocbs pointed to by iocbpp for processing.  Returns
 *	the number of iocbs queued.  May return -EINVAL if the aio_context
 *	specified by ctx_id is invalid, if nr is < 0, if the iocb at
 *	*iocbpp[0] is not properly initialized, if the operation specified
 *	is invalid for the file descriptor in the iocb.  May fail with
 *	-EFAULT if any of the data structures point to invalid data.  May
 *	fail with -EBADF if the file descriptor specified in the first
 *	iocb is invalid.  May fail with -EAGAIN if insufficient resources
 *	are available to queue any iocbs.  Will return 0 if nr is 0.  Will
 *	fail with -ENOSYS if not implemented.
 */
1683 1684
SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
		struct iocb __user * __user *, iocbpp)
L
Linus Torvalds 已提交
1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731
{
	struct kioctx *ctx;
	long ret = 0;
	int i;

	if (unlikely(nr < 0))
		return -EINVAL;

	if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
		return -EFAULT;

	ctx = lookup_ioctx(ctx_id);
	if (unlikely(!ctx)) {
		pr_debug("EINVAL: io_submit: invalid context id\n");
		return -EINVAL;
	}

	/*
	 * AKPM: should this return a partial result if some of the IOs were
	 * successfully submitted?
	 */
	for (i=0; i<nr; i++) {
		struct iocb __user *user_iocb;
		struct iocb tmp;

		if (unlikely(__get_user(user_iocb, iocbpp + i))) {
			ret = -EFAULT;
			break;
		}

		if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
			ret = -EFAULT;
			break;
		}

		ret = io_submit_one(ctx, user_iocb, &tmp);
		if (ret)
			break;
	}

	put_ioctx(ctx);
	return i ? i : ret;
}

/* lookup_kiocb
 *	Finds a given iocb for cancellation.
 */
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static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
				  u32 key)
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{
	struct list_head *pos;
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	assert_spin_locked(&ctx->ctx_lock);

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	/* TODO: use a hash or array, this sucks. */
	list_for_each(pos, &ctx->active_reqs) {
		struct kiocb *kiocb = list_kiocb(pos);
		if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
			return kiocb;
	}
	return NULL;
}

/* sys_io_cancel:
 *	Attempts to cancel an iocb previously passed to io_submit.  If
 *	the operation is successfully cancelled, the resulting event is
 *	copied into the memory pointed to by result without being placed
 *	into the completion queue and 0 is returned.  May fail with
 *	-EFAULT if any of the data structures pointed to are invalid.
 *	May fail with -EINVAL if aio_context specified by ctx_id is
 *	invalid.  May fail with -EAGAIN if the iocb specified was not
 *	cancelled.  Will fail with -ENOSYS if not implemented.
 */
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SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
		struct io_event __user *, result)
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{
	int (*cancel)(struct kiocb *iocb, struct io_event *res);
	struct kioctx *ctx;
	struct kiocb *kiocb;
	u32 key;
	int ret;

	ret = get_user(key, &iocb->aio_key);
	if (unlikely(ret))
		return -EFAULT;

	ctx = lookup_ioctx(ctx_id);
	if (unlikely(!ctx))
		return -EINVAL;

	spin_lock_irq(&ctx->ctx_lock);
	ret = -EAGAIN;
	kiocb = lookup_kiocb(ctx, iocb, key);
	if (kiocb && kiocb->ki_cancel) {
		cancel = kiocb->ki_cancel;
		kiocb->ki_users ++;
		kiocbSetCancelled(kiocb);
	} else
		cancel = NULL;
	spin_unlock_irq(&ctx->ctx_lock);

	if (NULL != cancel) {
		struct io_event tmp;
		pr_debug("calling cancel\n");
		memset(&tmp, 0, sizeof(tmp));
		tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
		tmp.data = kiocb->ki_user_data;
		ret = cancel(kiocb, &tmp);
		if (!ret) {
			/* Cancellation succeeded -- copy the result
			 * into the user's buffer.
			 */
			if (copy_to_user(result, &tmp, sizeof(tmp)))
				ret = -EFAULT;
		}
	} else
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		ret = -EINVAL;
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	put_ioctx(ctx);

	return ret;
}

/* io_getevents:
 *	Attempts to read at least min_nr events and up to nr events from
 *	the completion queue for the aio_context specified by ctx_id.  May
 *	fail with -EINVAL if ctx_id is invalid, if min_nr is out of range,
 *	if nr is out of range, if when is out of range.  May fail with
 *	-EFAULT if any of the memory specified to is invalid.  May return
 *	0 or < min_nr if no events are available and the timeout specified
 *	by when	has elapsed, where when == NULL specifies an infinite
 *	timeout.  Note that the timeout pointed to by when is relative and
 *	will be updated if not NULL and the operation blocks.  Will fail
 *	with -ENOSYS if not implemented.
 */
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SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
		long, min_nr,
		long, nr,
		struct io_event __user *, events,
		struct timespec __user *, timeout)
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{
	struct kioctx *ioctx = lookup_ioctx(ctx_id);
	long ret = -EINVAL;

	if (likely(ioctx)) {
		if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0))
			ret = read_events(ioctx, min_nr, nr, events, timeout);
		put_ioctx(ioctx);
	}

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	asmlinkage_protect(5, ret, ctx_id, min_nr, nr, events, timeout);
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	return ret;
}

__initcall(aio_setup);

EXPORT_SYMBOL(aio_complete);
EXPORT_SYMBOL(aio_put_req);
EXPORT_SYMBOL(wait_on_sync_kiocb);