aio.c 47.9 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/backing-dev.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>
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#include <linux/mmu_context.h>
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#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 <linux/blkdev.h>
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#include <linux/compat.h>
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#include <asm/kmap_types.h>
#include <asm/uaccess.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 = alloc_workqueue("aio", 0, 1);	/* used to limit concurrency */
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	BUG_ON(!aio_wq);
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	pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));

	return 0;
}
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__initcall(aio_setup);
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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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}

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static inline void get_ioctx(struct kioctx *kioctx)
{
	BUG_ON(atomic_read(&kioctx->users) <= 0);
	atomic_inc(&kioctx->users);
}

static inline int try_get_ioctx(struct kioctx *kioctx)
{
	return atomic_inc_not_zero(&kioctx->users);
}

static inline void put_ioctx(struct kioctx *kioctx)
{
	BUG_ON(atomic_read(&kioctx->users) <= 0);
	if (unlikely(atomic_dec_and_test(&kioctx->users)))
		__put_ioctx(kioctx);
}
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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;
}
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EXPORT_SYMBOL(wait_on_sync_kiocb);
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/* 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;

	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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	return req;
}

/*
 * struct kiocb's are allocated in batches to reduce the number of
 * times the ctx lock is acquired and released.
 */
#define KIOCB_BATCH_SIZE	32L
struct kiocb_batch {
	struct list_head head;
	long count; /* number of requests left to allocate */
};

static void kiocb_batch_init(struct kiocb_batch *batch, long total)
{
	INIT_LIST_HEAD(&batch->head);
	batch->count = total;
}

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static void kiocb_batch_free(struct kioctx *ctx, struct kiocb_batch *batch)
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{
	struct kiocb *req, *n;

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	if (list_empty(&batch->head))
		return;

	spin_lock_irq(&ctx->ctx_lock);
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	list_for_each_entry_safe(req, n, &batch->head, ki_batch) {
		list_del(&req->ki_batch);
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		list_del(&req->ki_list);
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		kmem_cache_free(kiocb_cachep, req);
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		ctx->reqs_active--;
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	}
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	spin_unlock_irq(&ctx->ctx_lock);
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}

/*
 * Allocate a batch of kiocbs.  This avoids taking and dropping the
 * context lock a lot during setup.
 */
static int kiocb_batch_refill(struct kioctx *ctx, struct kiocb_batch *batch)
{
	unsigned short allocated, to_alloc;
	long avail;
	bool called_fput = false;
	struct kiocb *req, *n;
	struct aio_ring *ring;

	to_alloc = min(batch->count, KIOCB_BATCH_SIZE);
	for (allocated = 0; allocated < to_alloc; allocated++) {
		req = __aio_get_req(ctx);
		if (!req)
			/* allocation failed, go with what we've got */
			break;
		list_add(&req->ki_batch, &batch->head);
	}

	if (allocated == 0)
		goto out;

retry:
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	spin_lock_irq(&ctx->ctx_lock);
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	ring = kmap_atomic(ctx->ring_info.ring_pages[0]);

	avail = aio_ring_avail(&ctx->ring_info, ring) - ctx->reqs_active;
	BUG_ON(avail < 0);
	if (avail == 0 && !called_fput) {
		/*
		 * Handle a potential starvation case.  It is possible that
		 * we hold the last reference on a struct file, causing us
		 * to delay the final fput to non-irq context.  In this case,
		 * ctx->reqs_active is artificially high.  Calling the fput
		 * routine here may free up a slot in the event completion
		 * ring, allowing this allocation to succeed.
		 */
		kunmap_atomic(ring);
		spin_unlock_irq(&ctx->ctx_lock);
		aio_fput_routine(NULL);
		called_fput = true;
		goto retry;
	}

	if (avail < allocated) {
		/* Trim back the number of requests. */
		list_for_each_entry_safe(req, n, &batch->head, ki_batch) {
			list_del(&req->ki_batch);
			kmem_cache_free(kiocb_cachep, req);
			if (--allocated <= avail)
				break;
		}
	}

	batch->count -= allocated;
	list_for_each_entry(req, &batch->head, ki_batch) {
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		list_add(&req->ki_list, &ctx->active_reqs);
		ctx->reqs_active++;
	}

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	kunmap_atomic(ring);
	spin_unlock_irq(&ctx->ctx_lock);
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out:
	return allocated;
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}

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static inline struct kiocb *aio_get_req(struct kioctx *ctx,
					struct kiocb_batch *batch)
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{
	struct kiocb *req;
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	if (list_empty(&batch->head))
		if (kiocb_batch_refill(ctx, batch) == 0)
			return NULL;
	req = list_first_entry(&batch->head, struct kiocb, ki_batch);
	list_del(&req->ki_batch);
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	return req;
}

static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
{
580 581
	assert_spin_locked(&ctx->ctx_lock);

582 583
	if (req->ki_eventfd != NULL)
		eventfd_ctx_put(req->ki_eventfd);
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	if (req->ki_dtor)
		req->ki_dtor(req);
B
Badari Pulavarty 已提交
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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))
592
		wake_up_all(&ctx->wait);
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}

595
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);

605 606
		/* Complete the fput(s) */
		if (req->ki_filp != NULL)
607
			fput(req->ki_filp);
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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)
{
A
Al Viro 已提交
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	dprintk(KERN_DEBUG "aio_put(%p): f_count=%ld\n",
		req, atomic_long_read(&req->ki_filp->f_count));
L
Linus Torvalds 已提交
627

628 629
	assert_spin_locked(&ctx->ctx_lock);

630
	req->ki_users--;
E
Eric Sesterhenn 已提交
631
	BUG_ON(req->ki_users < 0);
L
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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;

638 639
	/*
	 * Try to optimize the aio and eventfd file* puts, by avoiding to
640
	 * schedule work in case it is not final fput() time. In normal cases,
641 642
	 * we would not be holding the last reference to the file*, so
	 * this function will be executed w/out any aio kthread wakeup.
L
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643
	 */
644
	if (unlikely(!fput_atomic(req->ki_filp))) {
L
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		get_ioctx(ctx);
		spin_lock(&fput_lock);
		list_add(&req->ki_list, &fput_head);
		spin_unlock(&fput_lock);
649
		schedule_work(&fput_work);
650 651
	} else {
		req->ki_filp = NULL;
L
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652
		really_put_req(ctx, req);
653
	}
L
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	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.
 */
661
int aio_put_req(struct kiocb *req)
L
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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;
}
670
EXPORT_SYMBOL(aio_put_req);
L
Linus Torvalds 已提交
671

A
Adrian Bunk 已提交
672
static struct kioctx *lookup_ioctx(unsigned long ctx_id)
L
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673
{
J
Jens Axboe 已提交
674
	struct mm_struct *mm = current->mm;
675
	struct kioctx *ctx, *ret = NULL;
J
Jens Axboe 已提交
676
	struct hlist_node *n;
L
Linus Torvalds 已提交
677

J
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678 679 680
	rcu_read_lock();

	hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) {
N
Nick Piggin 已提交
681 682 683 684 685 686 687
		/*
		 * RCU protects us against accessing freed memory but
		 * we have to be careful not to get a reference when the
		 * reference count already dropped to 0 (ctx->dead test
		 * is unreliable because of races).
		 */
		if (ctx->user_id == ctx_id && !ctx->dead && try_get_ioctx(ctx)){
688
			ret = ctx;
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			break;
		}
J
Jens Axboe 已提交
691
	}
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J
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693
	rcu_read_unlock();
694
	return ret;
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}

/*
 * 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;

710 711
	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
L
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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
793
	 * context.
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	 */
	ret = retry(iocb);

797 798 799 800 801 802 803 804
	if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
		/*
		 * There's no easy way to restart the syscall since other AIO's
		 * may be already running. Just fail this IO with EINTR.
		 */
		if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
			     ret == -ERESTARTNOHAND || ret == -ERESTART_RESTARTBLOCK))
			ret = -EINTR;
805
		aio_complete(iocb, ret, 0);
806
	}
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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);
824 825 826 827 828 829 830 831

			/*
			 * __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
842
 * context.
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 */
static int __aio_run_iocbs(struct kioctx *ctx)
{
	struct kiocb *iocb;
847
	struct list_head run_list;
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849 850
	assert_spin_locked(&ctx->ctx_lock);

851
	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);
861
		__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);
}

/*
J
Jeff Moyer 已提交
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 * aio_run_all_iocbs:
 *	Process all pending retries queued on the ioctx
 *	run list, and keep running them until the list
 *	stays empty.
 * Assumes it is operating within the aio issuer's mm context.
L
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 */
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.
 */
907
static void aio_kick_handler(struct work_struct *work)
L
Linus Torvalds 已提交
908
{
909
	struct kioctx *ctx = container_of(work, struct kioctx, wq.work);
L
Linus Torvalds 已提交
910
	mm_segment_t oldfs = get_fs();
911
	struct mm_struct *mm;
L
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912 913 914 915 916 917
	int requeue;

	set_fs(USER_DS);
	use_mm(ctx->mm);
	spin_lock_irq(&ctx->ctx_lock);
	requeue =__aio_run_iocbs(ctx);
918
	mm = ctx->mm;
L
Linus Torvalds 已提交
919
	spin_unlock_irq(&ctx->ctx_lock);
920
 	unuse_mm(mm);
L
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921 922 923 924 925
	set_fs(oldfs);
	/*
	 * we're in a worker thread already, don't use queue_delayed_work,
	 */
	if (requeue)
926
		queue_delayed_work(aio_wq, &ctx->wq, 0);
L
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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
 */
935
static void try_queue_kicked_iocb(struct kiocb *iocb)
L
Linus Torvalds 已提交
936 937 938 939 940 941
{
 	struct kioctx	*ctx = iocb->ki_ctx;
	unsigned long flags;
	int run = 0;

	spin_lock_irqsave(&ctx->ctx_lock, flags);
942 943 944 945
	/* 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);
L
Linus Torvalds 已提交
946
	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
K
Ken Chen 已提交
947
	if (run)
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948 949 950 951 952 953
		aio_queue_work(ctx);
}

/*
 * kick_iocb:
 *      Called typically from a wait queue callback context
S
Shaohua Li 已提交
954
 *      to trigger a retry of the iocb.
L
Linus Torvalds 已提交
955 956 957
 *      The retry is usually executed by aio workqueue
 *      threads (See aio_kick_handler).
 */
958
void kick_iocb(struct kiocb *iocb)
L
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959 960 961 962 963 964 965 966 967
{
	/* 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;
	}

968
	try_queue_kicked_iocb(iocb);
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Linus Torvalds 已提交
969 970 971 972 973 974 975 976
}
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.
 */
977
int aio_complete(struct kiocb *iocb, long res, long res2)
L
Linus Torvalds 已提交
978 979 980 981 982 983 984 985 986
{
	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;

987 988 989 990 991 992
	/*
	 * 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
Linus Torvalds 已提交
993 994
	 */
	if (is_sync_kiocb(iocb)) {
995
		BUG_ON(iocb->ki_users != 1);
L
Linus Torvalds 已提交
996
		iocb->ki_user_data = res;
997
		iocb->ki_users = 0;
L
Linus Torvalds 已提交
998
		wake_up_process(iocb->ki_obj.tsk);
999
		return 1;
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1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025
	}

	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);
1026 1027
	if (++tail >= info->nr)
		tail = 0;
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Linus Torvalds 已提交
1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049

	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);
D
Davide Libenzi 已提交
1050 1051 1052 1053 1054 1055

	/*
	 * 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.
	 */
1056
	if (iocb->ki_eventfd != NULL)
D
Davide Libenzi 已提交
1057 1058
		eventfd_signal(iocb->ki_eventfd, 1);

L
Linus Torvalds 已提交
1059 1060 1061 1062
put_rq:
	/* everything turned out well, dispose of the aiocb. */
	ret = __aio_put_req(ctx, iocb);

1063 1064 1065 1066 1067 1068 1069 1070
	/*
	 * 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();

L
Linus Torvalds 已提交
1071 1072 1073
	if (waitqueue_active(&ctx->wait))
		wake_up(&ctx->wait);

1074
	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
L
Linus Torvalds 已提交
1075 1076
	return ret;
}
1077
EXPORT_SYMBOL(aio_complete);
L
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1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136

/* 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)
{
1137
	setup_timer_on_stack(&to->timer, timeout_func, (unsigned long) to);
L
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1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230
	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;
1231 1232 1233 1234
			if (unlikely(ctx->dead)) {
				ret = -EINVAL;
				break;
			}
L
Linus Torvalds 已提交
1235 1236
			if (to.timed_out)	/* Only check after read evt */
				break;
1237 1238 1239 1240 1241 1242
			/* 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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1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269
			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:
1270
	destroy_timer_on_stack(&to.timer);
L
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	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
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	spin_lock(&mm->ioctx_lock);
L
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1284 1285
	was_dead = ioctx->dead;
	ioctx->dead = 1;
J
Jens Axboe 已提交
1286 1287
	hlist_del_rcu(&ioctx->list);
	spin_unlock(&mm->ioctx_lock);
L
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1288 1289 1290 1291 1292 1293 1294

	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);
1295 1296 1297 1298 1299 1300

	/*
	 * 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.
	 */
1301
	wake_up_all(&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.
 */
1318
SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
L
Linus Torvalds 已提交
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{
	struct kioctx *ioctx = NULL;
	unsigned long ctx;
	long ret;

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

	ret = -EINVAL;
1329 1330 1331
	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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1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352
		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
1353
 *	implemented.  May fail with -EINVAL if the context pointed to
L
Linus Torvalds 已提交
1354 1355
 *	is invalid.
 */
1356
SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
L
Linus Torvalds 已提交
1357 1358 1359 1360 1361 1362 1363 1364 1365 1366
{
	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
1367
static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
L
Linus Torvalds 已提交
1368
{
B
Badari Pulavarty 已提交
1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381
	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++;
1382
		}
B
Badari Pulavarty 已提交
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	}
L
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1384

B
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1385 1386 1387
	/* 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
1390
static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
L
Linus Torvalds 已提交
1391 1392
{
	struct file *file = iocb->ki_filp;
B
Badari Pulavarty 已提交
1393 1394 1395 1396
	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
1397
	ssize_t ret = 0;
B
Badari Pulavarty 已提交
1398 1399 1400 1401 1402 1403 1404 1405 1406 1407
	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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1409 1410 1411 1412
	/* This matches the pread()/pwrite() logic */
	if (iocb->ki_pos < 0)
		return -EINVAL;

1413
	do {
B
Badari Pulavarty 已提交
1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424
		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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1425

B
Badari Pulavarty 已提交
1426 1427
	/* This means we must have transferred all that we could */
	/* No need to retry anymore */
L
Linus Torvalds 已提交
1428 1429 1430
	if ((ret == 0) || (iocb->ki_left == 0))
		ret = iocb->ki_nbytes - iocb->ki_left;

1431 1432 1433 1434 1435 1436 1437
	/* 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;
}

1461
static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
B
Badari Pulavarty 已提交
1462 1463 1464
{
	ssize_t ret;

1465 1466 1467 1468 1469
#ifdef CONFIG_COMPAT
	if (compat)
		ret = compat_rw_copy_check_uvector(type,
				(struct compat_iovec __user *)kiocb->ki_buf,
				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
C
Christopher Yeoh 已提交
1470
				&kiocb->ki_iovec, 1);
1471 1472 1473 1474 1475
	else
#endif
		ret = rw_copy_check_uvector(type,
				(struct iovec __user *)kiocb->ki_buf,
				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
C
Christopher Yeoh 已提交
1476
				&kiocb->ki_iovec, 1);
B
Badari Pulavarty 已提交
1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500
	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
1501 1502 1503 1504 1505
/*
 * aio_setup_iocb:
 *	Performs the initial checks and aio retry method
 *	setup for the kiocb at the time of io submission.
 */
1506
static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
L
Linus Torvalds 已提交
1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519
{
	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;
1520 1521 1522
		ret = security_file_permission(file, MAY_READ);
		if (unlikely(ret))
			break;
B
Badari Pulavarty 已提交
1523 1524 1525
		ret = aio_setup_single_vector(kiocb);
		if (ret)
			break;
L
Linus Torvalds 已提交
1526 1527
		ret = -EINVAL;
		if (file->f_op->aio_read)
B
Badari Pulavarty 已提交
1528
			kiocb->ki_retry = aio_rw_vect_retry;
L
Linus Torvalds 已提交
1529 1530 1531 1532 1533 1534 1535 1536 1537
		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;
1538 1539 1540
		ret = security_file_permission(file, MAY_WRITE);
		if (unlikely(ret))
			break;
B
Badari Pulavarty 已提交
1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554
		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;
1555
		ret = aio_setup_vectored_rw(READ, kiocb, compat);
B
Badari Pulavarty 已提交
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568
		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;
1569
		ret = aio_setup_vectored_rw(WRITE, kiocb, compat);
B
Badari Pulavarty 已提交
1570 1571
		if (ret)
			break;
L
Linus Torvalds 已提交
1572 1573
		ret = -EINVAL;
		if (file->f_op->aio_write)
B
Badari Pulavarty 已提交
1574
			kiocb->ki_retry = aio_rw_vect_retry;
L
Linus Torvalds 已提交
1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596
		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;
}

A
Adrian Bunk 已提交
1597
static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
J
Jeff Moyer 已提交
1598 1599
			 struct iocb *iocb, struct kiocb_batch *batch,
			 bool compat)
L
Linus Torvalds 已提交
1600 1601 1602 1603 1604 1605
{
	struct kiocb *req;
	struct file *file;
	ssize_t ret;

	/* enforce forwards compatibility on users */
1606
	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
L
Linus Torvalds 已提交
1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624
		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;

J
Jeff Moyer 已提交
1625
	req = aio_get_req(ctx, batch);  /* returns with 2 references to req */
L
Linus Torvalds 已提交
1626 1627 1628 1629
	if (unlikely(!req)) {
		fput(file);
		return -EAGAIN;
	}
Y
Yan Zheng 已提交
1630
	req->ki_filp = file;
1631 1632 1633 1634 1635 1636 1637
	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.
		 */
1638
		req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1639
		if (IS_ERR(req->ki_eventfd)) {
1640
			ret = PTR_ERR(req->ki_eventfd);
1641
			req->ki_eventfd = NULL;
1642 1643 1644
			goto out_put_req;
		}
	}
L
Linus Torvalds 已提交
1645

1646
	ret = put_user(req->ki_key, &user_iocb->aio_key);
L
Linus Torvalds 已提交
1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659
	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;

1660
	ret = aio_setup_iocb(req, compat);
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	if (ret)
		goto out_put_req;

	spin_lock_irq(&ctx->ctx_lock);
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	/*
	 * We could have raced with io_destroy() and are currently holding a
	 * reference to ctx which should be destroyed. We cannot submit IO
	 * since ctx gets freed as soon as io_submit() puts its reference.  The
	 * check here is reliable: io_destroy() sets ctx->dead before waiting
	 * for outstanding IO and the barrier between these two is realized by
	 * unlock of mm->ioctx_lock and lock of ctx->ctx_lock.  Analogously we
	 * increment ctx->reqs_active before checking for ctx->dead and the
	 * barrier is realized by unlock and lock of ctx->ctx_lock. Thus if we
	 * don't see ctx->dead set here, io_destroy() waits for our IO to
	 * finish.
	 */
	if (ctx->dead) {
		spin_unlock_irq(&ctx->ctx_lock);
		ret = -EINVAL;
		goto out_put_req;
	}
1683 1684
	aio_run_iocb(req);
	if (!list_empty(&ctx->run_list)) {
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		/* drain the run list */
		while (__aio_run_iocbs(ctx))
			;
	}
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	spin_unlock_irq(&ctx->ctx_lock);
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	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;
}

1700 1701
long do_io_submit(aio_context_t ctx_id, long nr,
		  struct iocb __user *__user *iocbpp, bool compat)
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{
	struct kioctx *ctx;
	long ret = 0;
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	int i = 0;
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Shaohua Li 已提交
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	struct blk_plug plug;
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	struct kiocb_batch batch;
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	if (unlikely(nr < 0))
		return -EINVAL;

1712 1713 1714
	if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
		nr = LONG_MAX/sizeof(*iocbpp);

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	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;
	}

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	kiocb_batch_init(&batch, nr);

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Shaohua Li 已提交
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	blk_start_plug(&plug);

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	/*
	 * 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;
		}

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		ret = io_submit_one(ctx, user_iocb, &tmp, &batch, compat);
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		if (ret)
			break;
	}
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Shaohua Li 已提交
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	blk_finish_plug(&plug);
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1752
	kiocb_batch_free(ctx, &batch);
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	put_ioctx(ctx);
	return i ? i : ret;
}

1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774
/* 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.
 */
SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
		struct iocb __user * __user *, iocbpp)
{
	return do_io_submit(ctx_id, nr, iocbpp, 0);
}

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/* lookup_kiocb
 *	Finds a given iocb for cancellation.
 */
1778 1779
static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
				  u32 key)
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{
	struct list_head *pos;
1782 1783 1784

	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.
 */
1804 1805
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
1847
		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
1856 1857 1858 1859 1860 1861 1862 1863 1864 1865
 *	the completion queue for the aio_context specified by ctx_id. If
 *	it succeeds, the number of read events is returned. May fail with
 *	-EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
 *	out of range, if timeout is out of range.  May fail with -EFAULT
 *	if any of the memory specified is invalid.  May return 0 or
 *	< min_nr if the timeout specified by timeout has elapsed
 *	before sufficient events are available, where timeout == NULL
 *	specifies an infinite timeout. Note that the timeout pointed to by
 *	timeout is relative and will be updated if not NULL and the
 *	operation blocks. Will fail with -ENOSYS if not implemented.
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Linus Torvalds 已提交
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 */
1867 1868 1869 1870 1871
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)) {
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Namhyung Kim 已提交
1877
		if (likely(min_nr <= nr && min_nr >= 0))
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			ret = read_events(ioctx, min_nr, nr, events, timeout);
		put_ioctx(ioctx);
	}

1882
	asmlinkage_protect(5, ret, ctx_id, min_nr, nr, events, timeout);
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	return ret;
}