Release 4.10 fs/aio.c

/*
 *      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.
 */

#define pr_fmt(fmt) "%s: " fmt, __func__

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/aio_abi.h>
#include <linux/export.h>
#include <linux/syscalls.h>
#include <linux/backing-dev.h>
#include <linux/uio.h>

#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/mmu_context.h>
#include <linux/percpu.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>
#include <linux/eventfd.h>
#include <linux/blkdev.h>
#include <linux/compat.h>
#include <linux/migrate.h>
#include <linux/ramfs.h>
#include <linux/percpu-refcount.h>
#include <linux/mount.h>

#include <asm/kmap_types.h>
#include <linux/uaccess.h>

#include "internal.h"


#define AIO_RING_MAGIC			0xa10a10a1

#define AIO_RING_COMPAT_FEATURES	1

#define AIO_RING_INCOMPAT_FEATURES	0

struct aio_ring {
	
unsigned	id;	/* kernel internal index number */
	
unsigned	nr;	/* number of io_events */
	
unsigned	head;	/* Written to by userland or under ring_lock
                                 * mutex by aio_read_events_ring(). */
	
unsigned	tail;

	
unsigned	magic;
	
unsigned	compat_features;
	
unsigned	incompat_features;
	
unsigned	header_length;	/* size of aio_ring */


	
struct io_event		io_events[0];
}; /* 128 bytes + ring size */


#define AIO_RING_PAGES	8


struct kioctx_table {
	
struct rcu_head	rcu;
	
unsigned	nr;
	
struct kioctx	*table[];
};


struct kioctx_cpu {
	
unsigned		reqs_available;
};


struct ctx_rq_wait {
	
struct completion comp;
	
atomic_t count;
};


struct kioctx {
	
struct percpu_ref	users;
	
atomic_t		dead;

	
struct percpu_ref	reqs;

	
unsigned long		user_id;

	
struct __percpu kioctx_cpu *cpu;

	/*
         * For percpu reqs_available, number of slots we move to/from global
         * counter at a time:
         */
	
unsigned		req_batch;
	/*
         * This is what userspace passed to io_setup(), it's not used for
         * anything but counting against the global max_reqs quota.
         *
         * The real limit is nr_events - 1, which will be larger (see
         * aio_setup_ring())
         */
	
unsigned		max_reqs;

	/* Size of ringbuffer, in units of struct io_event */
	
unsigned		nr_events;

	
unsigned long		mmap_base;
	
unsigned long		mmap_size;

	
struct page		**ring_pages;
	
long			nr_pages;

	
struct work_struct	free_work;

	/*
         * signals when all in-flight requests are done
         */
	
struct ctx_rq_wait	*rq_wait;

	struct {
		/*
                 * This counts the number of available slots in the ringbuffer,
                 * so we avoid overflowing it: it's decremented (if positive)
                 * when allocating a kiocb and incremented when the resulting
                 * io_event is pulled off the ringbuffer.
                 *
                 * We batch accesses to it with a percpu version.
                 */
		
atomic_t	reqs_available;
	} 
____cacheline_aligned_in_smp;

	struct {
		
spinlock_t	ctx_lock;
		
struct list_head active_reqs;	/* used for cancellation */
	} 
____cacheline_aligned_in_smp;

	struct {
		
struct mutex	ring_lock;
		
wait_queue_head_t wait;
	} 
____cacheline_aligned_in_smp;

	struct {
		
unsigned	tail;
		
unsigned	completed_events;
		
spinlock_t	completion_lock;
	} 
____cacheline_aligned_in_smp;

	
struct page		*internal_pages[AIO_RING_PAGES];
	
struct file		*aio_ring_file;

	
unsigned		id;
};

/*
 * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
 * cancelled or completed (this makes a certain amount of sense because
 * successful cancellation - io_cancel() - does deliver the completion to
 * userspace).
 *
 * And since most things don't implement kiocb cancellation and we'd really like
 * kiocb completion to be lockless when possible, we use ki_cancel to
 * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED
 * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel().
 */

#define KIOCB_CANCELLED		((void *) (~0ULL))


struct aio_kiocb {
	
struct kiocb		common;

	
struct kioctx		*ki_ctx;
	
kiocb_cancel_fn		*ki_cancel;

	
struct iocb __user	*ki_user_iocb;	/* user's aiocb */
	
__u64			ki_user_data;	/* user's data for completion */

	
struct list_head	ki_list;	/* the aio core uses this
                                                 * for cancellation */

	/*
         * If the aio_resfd field of the userspace iocb is not zero,
         * this is the underlying eventfd context to deliver events to.
         */
	
struct eventfd_ctx	*ki_eventfd;
};

/*------ sysctl variables----*/
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 */
/*----end sysctl variables---*/


static struct kmem_cache	*kiocb_cachep;

static struct kmem_cache	*kioctx_cachep;


static struct vfsmount *aio_mnt;


static const struct file_operations aio_ring_fops;

static const struct address_space_operations aio_ctx_aops;



static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
{
	struct qstr this = QSTR_INIT("[aio]", 5);
	struct file *file;
	struct path path;
	struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
	if (IS_ERR(inode))
		return ERR_CAST(inode);

	inode->i_mapping->a_ops = &aio_ctx_aops;
	inode->i_mapping->private_data = ctx;
	inode->i_size = PAGE_SIZE * nr_pages;

	path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
	if (!path.dentry) {
		iput(inode);
		return ERR_PTR(-ENOMEM);
	}
	path.mnt = mntget(aio_mnt);

	d_instantiate(path.dentry, inode);
	file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
	if (IS_ERR(file)) {
		path_put(&path);
		return file;
	}

	file->f_flags = O_RDWR;
	return file;
}

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181
100.00%
2
100.00%



static struct dentry *aio_mount(struct file_system_type *fs_type,
				int flags, const char *dev_name, void *data)
{
	static const struct dentry_operations ops = {
		.d_dname	= simple_dname,
        };
	struct dentry *root = mount_pseudo(fs_type, "aio:", NULL, &ops,
					   AIO_RING_MAGIC);

	if (!IS_ERR(root))
		root->d_sb->s_iflags |= SB_I_NOEXEC;
	return root;
}

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benjamin lahaise
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jann horn
24
31.58%
1
33.33%
gu zheng
gu zheng
1
1.32%
1
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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)
{
	static struct file_system_type aio_fs = {
		.name		= "aio",
		.mount		= aio_mount,
		.kill_sb	= kill_anon_super,
        };
	aio_mnt = kern_mount(&aio_fs);
	if (IS_ERR(aio_mnt))
		panic("Failed to create aio fs mount.");

	kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);

	pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));

	return 0;
}
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benjamin lahaise
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28.57%
andrew morton
andrew morton
4
4.60%
1
14.29%
christoph lameter
christoph lameter
2
2.30%
1
14.29%
christoph hellwig
christoph hellwig
1
1.15%
1
14.29%
kent overstreet
kent overstreet
1
1.15%
1
14.29%
stephen hemminger
stephen hemminger
1
1.15%
1
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__initcall(aio_setup);



static void put_aio_ring_file(struct kioctx *ctx)
{
	struct file *aio_ring_file = ctx->aio_ring_file;
	struct address_space *i_mapping;

	if (aio_ring_file) {
		truncate_setsize(file_inode(aio_ring_file), 0);

		/* Prevent further access to the kioctx from migratepages */
		i_mapping = aio_ring_file->f_mapping;
		spin_lock(&i_mapping->private_lock);
		i_mapping->private_data = NULL;
		ctx->aio_ring_file = NULL;
		spin_unlock(&i_mapping->private_lock);

		fput(aio_ring_file);
	}
}

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benjamin lahaise
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rasmus villemoes
12
14.81%
1
20.00%
gu zheng
gu zheng
9
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al viro
al viro
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5
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static void aio_free_ring(struct kioctx *ctx)
{
	int i;

	/* Disconnect the kiotx from the ring file.  This prevents future
         * accesses to the kioctx from page migration.
         */
	put_aio_ring_file(ctx);

	for (i = 0; i < ctx->nr_pages; i++) {
		struct page *page;
		pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
				page_count(ctx->ring_pages[i]));
		page = ctx->ring_pages[i];
		if (!page)
			continue;
		ctx->ring_pages[i] = NULL;
		put_page(page);
	}

	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
		kfree(ctx->ring_pages);
		ctx->ring_pages = NULL;
	}
}

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19.83%
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14.29%
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sasha levin
8
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1
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kent overstreet
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static int aio_ring_mremap(struct vm_area_struct *vma)
{
	struct file *file = vma->vm_file;
	struct mm_struct *mm = vma->vm_mm;
	struct kioctx_table *table;
	int i, res = -EINVAL;

	spin_lock(&mm->ioctx_lock);
	rcu_read_lock();
	table = rcu_dereference(mm->ioctx_table);
	for (i = 0; i < table->nr; i++) {
		struct kioctx *ctx;

		ctx = table->table[i];
		if (ctx && ctx->aio_ring_file == file) {
			if (!atomic_read(&ctx->dead)) {
				ctx->user_id = ctx->mmap_base = vma->vm_start;
				res = 0;
			}
			break;
		}
	}

	rcu_read_unlock();
	spin_unlock(&mm->ioctx_lock);
	return res;
}

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gu zheng
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oleg nesterov
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static const struct vm_operations_struct aio_ring_vm_ops = {
	.mremap		= aio_ring_mremap,
#if IS_ENABLED(CONFIG_MMU)
	.fault		= filemap_fault,
	.map_pages	= filemap_map_pages,
	.page_mkwrite	= filemap_page_mkwrite,
#endif
};



static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
{
	vma->vm_flags |= VM_DONTEXPAND;
	vma->vm_ops = &aio_ring_vm_ops;
	return 0;
}

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static const struct file_operations aio_ring_fops = {
	.mmap = aio_ring_mmap,
};

#if IS_ENABLED(CONFIG_MIGRATION)


static int aio_migratepage(struct address_space *mapping, struct page *new,
			struct page *old, enum migrate_mode mode)
{
	struct kioctx *ctx;
	unsigned long flags;
	pgoff_t idx;
	int rc;

	rc = 0;

	/* mapping->private_lock here protects against the kioctx teardown.  */
	spin_lock(&mapping->private_lock);
	ctx = mapping->private_data;
	if (!ctx) {
		rc = -EINVAL;
		goto out;
	}

	/* The ring_lock mutex.  The prevents aio_read_events() from writing
         * to the ring's head, and prevents page migration from mucking in
         * a partially initialized kiotx.
         */
	if (!mutex_trylock(&ctx->ring_lock)) {
		rc = -EAGAIN;
		goto out;
	}

	idx = old->index;
	if (idx < (pgoff_t)ctx->nr_pages) {
		/* Make sure the old page hasn't already been changed */
		if (ctx->ring_pages[idx] != old)
			rc = -EAGAIN;
	} else
		rc = -EINVAL;

	if (rc != 0)
		goto out_unlock;

	/* Writeback must be complete */
	BUG_ON(PageWriteback(old));
	get_page(new);

	rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
	if (rc != MIGRATEPAGE_SUCCESS) {
		put_page(new);
		goto out_unlock;
	}

	/* Take completion_lock to prevent other writes to the ring buffer
         * while the old page is copied to the new.  This prevents new
         * events from being lost.
         */
	spin_lock_irqsave(&ctx->completion_lock, flags);
	migrate_page_copy(new, old);
	BUG_ON(ctx->ring_pages[idx] != old);
	ctx->ring_pages[idx] = new;
	spin_unlock_irqrestore(&ctx->completion_lock, flags);

	/* The old page is no longer accessible. */
	put_page(old);

out_unlock:
	mutex_unlock(&ctx->ring_lock);
out:
	spin_unlock(&mapping->private_lock);
	return rc;
}
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#endif


static const struct address_space_operations aio_ctx_aops = {
	.set_page_dirty = __set_page_dirty_no_writeback,
#if IS_ENABLED(CONFIG_MIGRATION)
	.migratepage	= aio_migratepage,
#endif
};



static int aio_setup_ring(struct kioctx *ctx)
{
	struct aio_ring *ring;
	unsigned nr_events = ctx->max_reqs;
	struct mm_struct *mm = current->mm;
	unsigned long size, unused;
	int nr_pages;
	int i;
	struct file *file;

	/* 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 = PFN_UP(size);
	if (nr_pages < 0)
		return -EINVAL;

	file = aio_private_file(ctx, nr_pages);
	if (IS_ERR(file)) {
		ctx->aio_ring_file = NULL;
		return -ENOMEM;
	}

	ctx->aio_ring_file = file;
	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
			/ sizeof(struct io_event);

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

	for (i = 0; i < nr_pages; i++) {
		struct page *page;
		page = find_or_create_page(file->f_mapping,
					   i, GFP_HIGHUSER | __GFP_ZERO);
		if (!page)
			break;
		pr_debug("pid(%d) page[%d]->count=%d\n",
			 current->pid, i, page_count(page));
		SetPageUptodate(page);
		unlock_page(page);

		ctx->ring_pages[i] = page;
	}
	ctx->nr_pages = i;

	if (unlikely(i != nr_pages)) {
		aio_free_ring(ctx);
		return -ENOMEM;
	}

	ctx->mmap_size = nr_pages * PAGE_SIZE;
	pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);

	if (down_write_killable(&mm->mmap_sem)) {
		ctx->mmap_size = 0;
		aio_free_ring(ctx);
		return -EINTR;
	}

	ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
				       PROT_READ | PROT_WRITE,
				       MAP_SHARED, 0, &unused);
	up_write(&mm->mmap_sem);
	if (IS_ERR((void *)ctx->mmap_base)) {
		ctx->mmap_size = 0;
		aio_free_ring(ctx);
		return -ENOMEM;
	}

	pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);

	ctx->user_id = ctx->mmap_base;
	ctx->nr_events = nr_events; /* trusted copy */

	ring = kmap_atomic(ctx->ring_pages[0]);
	ring->nr = nr_events;	/* user copy */
	ring->id = ~0U;
	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);
	flush_dcache_page(ctx->ring_pages[0]);

	return 0;
}

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3.89%
1
5.88%
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zach brown
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1.75%
1
5.88%
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michel lespinasse
3
0.58%
2
11.76%
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al viro
2
0.39%
2
11.76%
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oliver neukum
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1
5.88%
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#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)



void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
{
	struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common);
	struct kioctx *ctx = req->ki_ctx;
	unsigned long flags;

	spin_lock_irqsave(&ctx->ctx_lock, flags);

	if (!req->ki_list.next)
		list_add(&req->ki_list, &ctx->active_reqs);

	req->ki_cancel = cancel;

	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
}
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EXPORT_SYMBOL(kiocb_set_cancel_fn);



static int kiocb_cancel(struct aio_kiocb *kiocb)
{
	kiocb_cancel_fn *old, *cancel;

	/*
         * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
         * actually has a cancel function, hence the cmpxchg()
         */

	cancel = ACCESS_ONCE(kiocb->ki_cancel);
	do {
		if (!cancel || cancel == KIOCB_CANCELLED)
			return -EINVAL;

		old = cancel;
		cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
	} while (cancel != old);

	return cancel(&kiocb->common);
}

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static void free_ioctx(struct work_struct *work)
{
	struct kioctx *ctx = container_of(work, struct kioctx, free_work);

	pr_debug("freeing %p\n", ctx);

	aio_free_ring(ctx);
	free_percpu(ctx->cpu);
	percpu_ref_exit(&ctx->reqs);
	percpu_ref_exit(&ctx->users);
	kmem_cache_free(kioctx_cachep, ctx);
}

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benjamin lahaise
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static void free_ioctx_reqs(struct percpu_ref *ref)
{
	struct kioctx *ctx = container_of(ref, struct kioctx, reqs);

	/* At this point we know that there are no any in-flight requests */
	if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
		complete(&ctx->rq_wait->comp);

	INIT_WORK(&ctx->free_work, free_ioctx);
	schedule_work(&ctx->free_work);
}

Contributors
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kent overstreet
kent overstreet
44
61.97%
3
60.00%
jens axboe
jens axboe
15
21.13%
1
20.00%
anatol pomozov
anatol pomozov
12
16.90%
1
20.00%
Total
71
100.00%
5
100.00%

/*
 * When this function runs, the kioctx has been removed from the "hash table"
 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
 * now it's safe to cancel any that need to be.
 */


static void free_ioctx_users(struct percpu_ref *ref)
{
	struct kioctx *ctx = container_of(ref, struct kioctx, users);
	struct aio_kiocb *req;

	spin_lock_irq(&ctx->ctx_lock);

	while (!list_empty(&ctx->active_reqs)) {
		req = list_first_entry(&ctx->active_reqs,
				       struct aio_kiocb, ki_list);

		list_del_init(&req->ki_list);
		kiocb_cancel(req);
	}

	spin_unlock_irq(&ctx->ctx_lock);

	percpu_ref_kill(&ctx->reqs);
	percpu_ref_put(&ctx->reqs);
}

Contributors
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kent overstreet
kent overstreet
89
85.58%
4
66.67%
benjamin lahaise
benjamin lahaise
13
12.50%
1
16.67%
christoph hellwig
christoph hellwig
2
1.92%
1
16.67%
Total
104
100.00%
6
100.00%



static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
{
	unsigned i, new_nr;
	struct kioctx_table *table, *old;
	struct aio_ring *ring;

	spin_lock(&mm->ioctx_lock);
	table = rcu_dereference_raw(mm->ioctx_table);

	while (1) {
		if (table)
			for (i = 0; i < table->nr; i++)
				if (!table->table[i]) {
					ctx->id = i;
					table->table[i] = ctx;
					spin_unlock(&mm->ioctx_lock);

					/* While kioctx setup is in progress,
                                         * we are protected from page migration
                                         * changes ring_pages by ->ring_lock.
                                         */
					ring = kmap_atomic(ctx->ring_pages[0]);
					ring->id = ctx->id;
					kunmap_atomic(ring);
					return 0;
				}

		new_nr = (table ? table->nr : 1) * 4;
		spin_unlock(&mm->ioctx_lock);

		table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
				new_nr, GFP_KERNEL);
		if (!table)
			return -ENOMEM;

		table->nr = new_nr;

		spin_lock(&mm->ioctx_lock);
		old = rcu_dereference_raw(mm->ioctx_table);

		if (!old) {
			rcu_assign_pointer(mm->ioctx_table, table);
		} else if (table->nr > old->nr) {
			memcpy(table->table, old->table,
			       old->nr * sizeof(struct kioctx *));

			rcu_assign_pointer(mm->ioctx_table, table);
			kfree_rcu(old, rcu);
		} else {
			kfree(table);
			table = old;
		}
	}
}

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benjamin lahaise
benjamin lahaise
285
96.61%
3
50.00%
kent overstreet
kent overstreet
8
2.71%
2
33.33%
oleg nesterov
oleg nesterov
2
0.68%
1
16.67%
Total
295
100.00%
6
100.00%



static void aio_nr_sub(unsigned nr)
{
	spin_lock(&aio_nr_lock);
	if (WARN_ON(aio_nr - nr > aio_nr))
		aio_nr = 0;
	else
		aio_nr -= nr;
	spin_unlock(&aio_nr_lock);
}

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kent overstreet
kent overstreet
41
100.00%
1
100.00%
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41
100.00%
1
100.00%

/* 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 = current->mm;
	struct kioctx *ctx;
	int err = -ENOMEM;

	/*
         * We keep track of the number of available ringbuffer slots, to prevent
         * overflow (reqs_available), and we also use percpu counters for this.
         *
         * So since up to half the slots might be on other cpu's percpu counters
         * and unavailable, double nr_events so userspace sees what they
         * expected: additionally, we move req_batch slots to/from percpu
         * counters at a time, so make sure that isn't 0:
         */
	nr_events = max(nr_events, num_possible_cpus() * 4);
	nr_events *= 2;

	/* Prevent overflows */
	if (nr_events > (0x10000000U / sizeof(struct io_event))) {
		pr_debug("ENOMEM: nr_events too high\n");
		return ERR_PTR(-EINVAL);
	}

	if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL))
		return ERR_PTR(-EAGAIN);

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

	ctx->max_reqs = nr_events;

	spin_lock_init(&ctx->ctx_lock);
	spin_lock_init(&ctx->completion_lock);
	mutex_init(&ctx->ring_lock);
	/* Protect against page migration throughout kiotx setup by keeping
         * the ring_lock mutex held until setup is complete. */
	mutex_lock(&ctx->ring_lock);
	init_waitqueue_head(&ctx->wait);

	INIT_LIST_HEAD(&ctx->active_reqs);

	if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
		goto err;

	if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
		goto err;

	ctx->cpu = alloc_percpu(struct kioctx_cpu);
	if (!ctx->cpu)
		goto err;

	err = aio_setup_ring(ctx);
	if (err < 0)
		goto err;

	atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
	ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
	if (ctx->req_batch < 1)
		ctx->req_batch = 1;

	/* limit the number of system wide aios */
	spin_lock(&aio_nr_lock);
	if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
	    aio_nr + nr_events < aio_nr) {
		spin_unlock(&aio_nr_lock);
		err = -EAGAIN;
		goto err_ctx;
	}
	aio_nr += ctx->max_reqs;
	spin_unlock(&aio_nr_lock);

	percpu_ref_get(&ctx->users);	/* io_setup() will drop this ref */
	percpu_ref_get(&ctx->reqs);	/* free_ioctx_users() will drop this */

	err = ioctx_add_table(ctx, mm);
	if (err)
		goto err_cleanup;

	/* Release the ring_lock mutex now that all setup is complete. */
	mutex_unlock(&ctx->ring_lock);

	pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
		 ctx, ctx->user_id, mm, ctx->nr_events);
	return ctx;

err_cleanup:
	aio_nr_sub(ctx->max_reqs);
err_ctx:
	atomic_set(&ctx->dead, 1);
	if (ctx->mmap_size)
		vm_munmap(ctx->mmap_base, ctx->mmap_size);
	aio_free_ring(ctx);
err:
	mutex_unlock(&ctx->ring_lock);
	free_percpu(ctx->cpu);
	percpu_ref_exit(&ctx->reqs);
	percpu_ref_exit(&ctx->users);
	kmem_cache_free(kioctx_cachep, ctx);
	pr_debug("error allocating ioctx %d\n", err);
	return ERR_PTR(err);
}

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benjamin lahaise
benjamin lahaise
241
47.25%
7
25.00%
kent overstreet
kent overstreet
172
33.73%
8
28.57%
al viro
al viro
47
9.22%
4
14.29%
zach brown
zach brown
23
4.51%
1
3.57%
gu zheng
gu zheng
12
2.35%
2
7.14%
tejun heo
tejun heo
12
2.35%
4
14.29%
jens axboe
jens axboe
2
0.39%
1
3.57%
robert p. j. day
robert p. j. day
1
0.20%
1
3.57%
Total
510
100.00%
28
100.00%

/* kill_ioctx
 *      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 int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
		      struct ctx_rq_wait *wait)
{
	struct kioctx_table *table;

	spin_lock(&mm->ioctx_lock);
	if (atomic_xchg(&ctx->dead, 1)) {
		spin_unlock(&mm->ioctx_lock);
		return -EINVAL;
	}

	table = rcu_dereference_raw(mm->ioctx_table);
	WARN_ON(ctx != table->table[ctx->id]);
	table->table[ctx->id] = NULL;
	spin_unlock(&mm->ioctx_lock);

	/* percpu_ref_kill() will do the necessary call_rcu() */
	wake_up_all(&ctx->wait);

	/*
         * It'd be more correct to do this in free_ioctx(), after all
         * the outstanding kiocbs have finished - but by then io_destroy
         * has already returned, so io_setup() could potentially return
         * -EAGAIN with no ioctxs actually in use (as far as userspace
         *  could tell).
         */
	aio_nr_sub(ctx->max_reqs);

	if (ctx->mmap_size)
		vm_munmap(ctx->mmap_base, ctx->mmap_size);

	ctx->rq_wait = wait;
	percpu_ref_kill(&ctx->users);
	return 0;
}

Contributors
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benjamin lahaise
benjamin lahaise
66
43.14%
5
33.33%
kent overstreet
kent overstreet
50
32.68%
5
33.33%
al viro
al viro
15
9.80%
1
6.67%
ken chen
ken chen
10
6.54%
1
6.67%
anatol pomozov
anatol pomozov
7
4.58%
1
6.67%
jens axboe
jens axboe
4
2.61%
1
6.67%
oleg nesterov
oleg nesterov
1
0.65%
1
6.67%
Total
153
100.00%
15
100.00%

/*
 * 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.
 *
 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
 * them.
 */


void exit_aio(struct mm_struct *mm)
{
	struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
	struct ctx_rq_wait wait;
	int i, skipped;

	if (!table)
		return;

	atomic_set(&wait.count, table->nr);
	init_completion(&wait.comp);

	skipped = 0;
	for (i = 0; i < table->nr; ++i) {
		struct kioctx *ctx = table->table[i];

		if (!ctx) {
			skipped++;
			continue;
		}

		/*
                 * We don't need to bother with munmap() here - exit_mmap(mm)
                 * is coming and it'll unmap everything. And we simply can't,
                 * this is not necessarily our ->mm.
                 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
                 * that it needs to unmap the area, just set it to 0.
                 */
		ctx->mmap_size = 0;
		kill_ioctx(mm, ctx, &wait);
	}

	if (!atomic_sub_and_test(skipped, &wait.count)) {
		/* Wait until all IO for the context are done. */
		wait_for_completion(&wait.comp);
	}

	RCU_INIT_POINTER(mm->ioctx_table, NULL);
	kfree(table);
}

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jens axboe
jens axboe
54
34.62%
1
11.11%
benjamin lahaise
benjamin lahaise
44
28.21%
2
22.22%
oleg nesterov
oleg nesterov
40
25.64%
1
11.11%
gu zheng
gu zheng
7
4.49%
1
11.11%
al viro
al viro
6
3.85%
1
11.11%
kent overstreet
kent overstreet
4
2.56%
2
22.22%
anatol pomozov
anatol pomozov
1
0.64%
1
11.11%
Total
156
100.00%
9
100.00%



static void put_reqs_available(struct kioctx *ctx, unsigned nr)
{
	struct kioctx_cpu *kcpu;
	unsigned long flags;

	local_irq_save(flags);
	kcpu = this_cpu_ptr(ctx->cpu);
	kcpu->reqs_available += nr;

	while (kcpu->reqs_available >= ctx->req_batch * 2) {
		kcpu->reqs_available -= ctx->req_batch;
		atomic_add(ctx->req_batch, &ctx->reqs_available);
	}

	local_irq_restore(flags);
}

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kent overstreet
kent overstreet
69
84.15%
1
33.33%
benjamin lahaise
benjamin lahaise
13
15.85%
2
66.67%
Total
82
100.00%
3
100.00%



static bool get_reqs_available(struct kioctx *ctx)
{
	struct kioctx_cpu *kcpu;
	bool ret = false;
	unsigned long flags;

	local_irq_save(flags);
	kcpu = this_cpu_ptr(ctx->cpu);
	if (!kcpu->reqs_available) {
		int old, avail = atomic_read(&ctx->reqs_available);

		do {
			if (avail < ctx->req_batch)
				goto out;

			old = avail;
			avail = atomic_cmpxchg(&ctx->reqs_available,
					       avail, avail - ctx->req_batch);
		} while (avail != old);

		kcpu->reqs_available += ctx->req_batch;
	}

	ret = true;
	kcpu->reqs_available--;
out:
	local_irq_restore(flags);
	return ret;
}

Contributors
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kent overstreet
kent overstreet
118
90.08%
1
33.33%
benjamin lahaise
benjamin lahaise
13
9.92%
2
66.67%
Total
131
100.00%
3
100.00%

/* refill_reqs_available
 *      Updates the reqs_available reference counts used for tracking the
 *      number of free slots in the completion ring.  This can be called
 *      from aio_complete() (to optimistically update reqs_available) or
 *      from aio_get_req() (the we're out of events case).  It must be
 *      called holding ctx->completion_lock.
 */


static void refill_reqs_available(struct kioctx *ctx, unsigned head,
                                  unsigned tail)
{
	unsigned events_in_ring, completed;

	/* Clamp head since userland can write to it. */
	head %= ctx->nr_events;
	if (head <= tail)
		events_in_ring = tail - head;
	else
		events_in_ring = ctx->nr_events - (head - tail);

	completed = ctx->completed_events;
	if (events_in_ring < completed)
		completed -= events_in_ring;
	else
		completed = 0;

	if (!completed)
		return;

	ctx->completed_events -= completed;
	put_reqs_available(ctx, completed);
}

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benjamin lahaise
benjamin lahaise
94
100.00%
1
100.00%
Total
94
100.00%
1
100.00%

/* user_refill_reqs_available
 *      Called to refill reqs_available when aio_get_req() encounters an
 *      out of space in the completion ring.
 */


static void user_refill_reqs_available(struct kioctx *ctx)
{
	spin_lock_irq(&ctx->completion_lock);
	if (ctx->completed_events) {
		struct aio_ring *ring;
		unsigned head;

		/* Access of ring->head may race with aio_read_events_ring()
                 * here, but that's okay since whether we read the old version
                 * or the new version, and either will be valid.  The important
                 * part is that head cannot pass tail since we prevent
                 * aio_complete() from updating tail by holding
                 * ctx->completion_lock.  Even if head is invalid, the check
                 * against ctx->completed_events below will make sure we do the
                 * safe/right thing.
                 */
		ring = kmap_atomic(ctx->ring_pages[0]);
		head = ring->head;
		kunmap_atomic(ring);

		refill_reqs_available(ctx, head, ctx->tail);
	}

	spin_unlock_irq(&ctx->completion_lock);
}

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benjamin lahaise
benjamin lahaise
78
100.00%
1
100.00%
Total
78
100.00%
1
100.00%

/* aio_get_req
 *      Allocate a slot for an aio request.
 * Returns NULL if no requests are free.
 */


static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
{
	struct aio_kiocb *req;

	if (!get_reqs_available(ctx)) {
		user_refill_reqs_available(ctx);
		if (!get_reqs_available(ctx))
			return NULL;
	}

	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
	if (unlikely(!req))
		goto out_put;

	percpu_ref_get(&ctx->reqs);

	req->ki_ctx = ctx;
	return req;
out_put:
	put_reqs_available(ctx, 1);
	return NULL;
}

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CommitProp
kent overstreet
kent overstreet
41
42.71%
4
44.44%
benjamin lahaise
benjamin lahaise
28
29.17%
2
22.22%
jeff moyer
jeff moyer
19
19.79%
1
11.11%
gleb natapov
gleb natapov
6
6.25%
1
11.11%
christoph hellwig
christoph hellwig
2
2.08%
1
11.11%
Total
96
100.00%
9
100.00%



static void kiocb_free(struct aio_kiocb *req)
{
	if (req->common.ki_filp)
		fput(req->common.ki_filp);
	if (req->ki_eventfd != NULL)
		eventfd_ctx_put(req->ki_eventfd);
	kmem_cache_free(kiocb_cachep, req);
}

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benjamin lahaise
benjamin lahaise
16
32.00%
1
16.67%
kent overstreet
kent overstreet
14
28.00%
2
33.33%
davide libenzi
davide libenzi
11
22.00%
1
16.67%
christoph hellwig
christoph hellwig
5
10.00%
1
16.67%
william lee irwin iii
william lee irwin iii
4
8.00%
1
16.67%
Total
50
100.00%
6
100.00%



static struct kioctx *lookup_ioctx(unsigned long ctx_id)
{
	struct aio_ring __user *ring  = (void __user *)ctx_id;
	struct mm_struct *mm = current->mm;
	struct kioctx *ctx, *ret = NULL;
	struct kioctx_table *table;
	unsigned id;

	if (get_user(id, &ring->id))
		return NULL;

	rcu_read_lock();
	table = rcu_dereference(mm->ioctx_table);

	if (!table || id >= table->nr)
		goto out;

	ctx = table->table[id];
	if (ctx && ctx->user_id == ctx_id) {
		percpu_ref_get(&ctx->users);
		ret = ctx;
	}
out:
	rcu_read_unlock();
	return ret;
}

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benjamin lahaise
benjamin lahaise
73
54.48%
3
42.86%
zach brown
zach brown
46
34.33%
1
14.29%
suparna bhattacharya
suparna bhattacharya
8
5.97%
1
14.29%
kent overstreet
kent overstreet
7
5.22%
2
28.57%
Total
134
100.00%
7
100.00%

/* aio_complete
 *      Called when the io request on the given iocb is complete.
 */


static void aio_complete(struct kiocb *kiocb, long res, long res2)
{
	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common);
	struct kioctx	*ctx = iocb->ki_ctx;
	struct aio_ring	*ring;
	struct io_event	*ev_page, *event;
	unsigned tail, pos, head;
	unsigned long	flags;

	if (kiocb->ki_flags & IOCB_WRITE) {
		struct file *file = kiocb->ki_filp;

		/*
                 * Tell lockdep we inherited freeze protection from submission
                 * thread.
                 */
		if (S_ISREG(file_inode(file)->i_mode))
			__sb_writers_acquired(file_inode(file)->i_sb, SB_FREEZE_WRITE);
		file_end_write(file);
	}

	/*
         * 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
         */
	BUG_ON(is_sync_kiocb(kiocb));

	if (iocb->ki_list.next) {
		unsigned long flags;

		spin_lock_irqsave(&ctx->ctx_lock, flags);
		list_del(&iocb->ki_list);
		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
	}

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

	tail = ctx->tail;
	pos = tail + AIO_EVENTS_OFFSET;

	if (++tail >= ctx->nr_events)
		tail = 0;

	ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
	event = ev_page + pos % AIO_EVENTS_PER_PAGE;

	event->obj = (u64)(unsigned long)iocb->ki_user_iocb;
	event->data = iocb->ki_user_data;
	event->res = res;
	event->res2 = res2;

	kunmap_atomic(ev_page);
	flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);

	pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
		 ctx, tail, iocb, iocb->ki_user_iocb, 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 */

	ctx->tail = tail;

	ring = kmap_atomic(ctx->ring_pages[0]);
	head = ring->head;
	ring->tail = tail;
	kunmap_atomic(ring);
	flush_dcache_page(ctx->ring_pages[0]);

	ctx->completed_events++;
	if (ctx->completed_events > 1)
		refill_reqs_available(ctx, head, tail);
	spin_unlock_irqrestore(&ctx->completion_lock, flags);

	pr_debug("added to ring %p at [%u]\n", iocb, tail);

	/*
         * 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.
         */
	if (iocb->ki_eventfd != NULL)
		eventfd_signal(iocb->ki_eventfd, 1);

	/* everything turned out well, dispose of the aiocb. */
	kiocb_free(iocb);

	/*
         * 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();

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

	percpu_ref_put(&ctx->reqs);
}

Contributors
Person
Tokens
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Commits
CommitProp
kent overstreet
kent overstreet
139
31.38%
9
40.91%
suparna bhattacharya
suparna bhattacharya
132
29.80%
1
4.55%
benjamin lahaise
benjamin lahaise
70
15.80%
2
9.09%
jan kara
jan kara
37
8.35%
1
4.55%
christoph hellwig
christoph hellwig
21
4.74%
2
9.09%
davide libenzi
davide libenzi
18
4.06%
2
9.09%
shaohua li
shaohua li
12
2.71%
1
4.55%
kenneth w. chen
kenneth w. chen
8
1.81%
1
4.55%
quentin barnes
quentin barnes
4
0.90%
1
4.55%
tang chen
tang chen
1
0.23%
1
4.55%
zach brown
zach brown
1
0.23%
1
4.55%
Total
443
100.00%
22
100.00%

/* aio_read_events_ring
 *      Pull an event off of the ioctx's event ring.  Returns the number of
 *      events fetched
 */


static long aio_read_events_ring(struct kioctx *ctx,
				 struct io_event __user *event, long nr)
{
	struct aio_ring *ring;
	unsigned head, tail, pos;
	long ret = 0;
	int copy_ret;

	/*
         * The mutex can block and wake us up and that will cause
         * wait_event_interruptible_hrtimeout() to schedule without sleeping
         * and repeat. This should be rare enough that it doesn't cause
         * peformance issues. See the comment in read_events() for more detail.
         */
	sched_annotate_sleep();
	mutex_lock(&ctx->ring_lock);

	/* Access to ->ring_pages here is protected by ctx->ring_lock. */
	ring = kmap_atomic(ctx->ring_pages[0]);
	head = ring->head;
	tail = ring->tail;
	kunmap_atomic(ring);

	/*
         * Ensure that once we've read the current tail pointer, that
         * we also see the events that were stored up to the tail.
         */
	smp_rmb();

	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);

	if (head == tail)
		goto out;

	head %= ctx->nr_events;
	tail %= ctx->nr_events;

	while (ret < nr) {
		long avail;
		struct io_event *ev;
		struct page *page;

		avail = (head <= tail ?  tail : ctx->nr_events) - head;
		if (head == tail)
			break;

		avail = min(avail, nr - ret);
		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
			    ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));

		pos = head + AIO_EVENTS_OFFSET;
		page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
		pos %= AIO_EVENTS_PER_PAGE;

		ev = kmap(page);
		copy_ret = copy_to_user(event + ret, ev + pos,
					sizeof(*ev) * avail);
		kunmap(page);

		if (unlikely(copy_ret)) {
			ret = -EFAULT;
			goto out;
		}

		ret += avail;
		head += avail;
		head %= ctx->nr_events;
	}

	ring = kmap_atomic(ctx->ring_pages[0]);
	ring->head = head;
	kunmap_atomic(ring);
	flush_dcache_page(ctx->ring_pages[0]);

	pr_debug("%li  h%u t%u\n", ret, head, tail);
out:
	mutex_unlock(&ctx->ring_lock);

	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
kent overstreet
kent overstreet
220
65.09%
5
45.45%
suparna bhattacharya
suparna bhattacharya
90
26.63%
1
9.09%
benjamin lahaise
benjamin lahaise
20
5.92%
3
27.27%
jeff moyer
jeff moyer
4
1.18%
1
9.09%
dave chinner
dave chinner
4
1.18%
1
9.09%
Total
338
100.00%
11
100.00%



static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
			    struct io_event __user *event, long *i)
{
	long ret = aio_read_events_ring(ctx, event + *i, nr - *i);

	if (ret > 0)
		*i += ret;

	if (unlikely(atomic_read(&ctx->dead)))
		ret = -EINVAL;

	if (!*i)
		*i = ret;

	return ret < 0 || *i >= min_nr;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
kent overstreet
kent overstreet
68
71.58%
1
33.33%
benjamin lahaise
benjamin lahaise
20
21.05%
1
33.33%
andrew morton
andrew morton
7
7.37%
1
33.33%
Total
95
100.00%
3
100.00%



static long read_events(struct kioctx *ctx, long min_nr, long nr,
			struct io_event __user *event,
			struct timespec __user *timeout)
{
	ktime_t until = KTIME_MAX;
	long ret = 0;

	if (timeout) {
		struct timespec	ts;

		if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
			return -EFAULT;

		until = timespec_to_ktime(ts);
	}

	/*
         * Note that aio_read_events() is being called as the conditional - i.e.
         * we're calling it after prepare_to_wait() has set task state to
         * TASK_INTERRUPTIBLE.
         *
         * But aio_read_events() can block, and if it blocks it's going to flip
         * the task state back to TASK_RUNNING.
         *
         * This should be ok, provided it doesn't flip the state back to
         * TASK_RUNNING and return 0 too much - that causes us to spin. That
         * will only happen if the mutex_lock() call blocks, and we then find
         * the ringbuffer empty. So in practice we should be ok, but it's
         * something to be aware of when touching this code.
         */
	if (until == 0)
		aio_read_events(ctx, min_nr, nr, event, &ret);
	else
		wait_event_interruptible_hrtimeout(ctx->wait,
				aio_read_events(ctx, min_nr, nr, event, &ret),
				until);

	if (!ret && signal_pending(current))
		ret = -EINTR;

	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
suparna bhattacharya
suparna bhattacharya
55
39.01%
1
14.29%
benjamin lahaise
benjamin lahaise
31
21.99%
1
14.29%
kent overstreet
kent overstreet
31
21.99%
2
28.57%
fam zheng
fam zheng
21
14.89%
1
14.29%
linus torvalds
linus torvalds
2
1.42%
1
14.29%
thomas gleixner
thomas gleixner
1
0.71%
1
14.29%
Total
141
100.00%
7
100.00%

/* 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.
 */

SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
{
	struct kioctx *ioctx = NULL;
	unsigned long ctx;
	long ret;

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

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

	ioctx = ioctx_alloc(nr_events);
	ret = PTR_ERR(ioctx);
	if (!IS_ERR(ioctx)) {
		ret = put_user(ioctx->user_id, ctxp);
		if (ret)
			kill_ioctx(current->mm, ioctx, NULL);
		percpu_ref_put(&ioctx->users);
	}

out:
	return ret;
}

#ifdef CONFIG_COMPAT

COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
{
	struct kioctx *ioctx = NULL;
	unsigned long ctx;
	long ret;

	ret = get_user(ctx, ctx32p);
	if (unlikely(ret))
		goto out;

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

	ioctx = ioctx_alloc(nr_events);
	ret = PTR_ERR(ioctx);
	if (!IS_ERR(ioctx)) {
		/* truncating is ok because it's a user address */
		ret = put_user((u32)ioctx->user_id, ctx32p);
		if (ret)
			kill_ioctx(current->mm, ioctx, NULL);
		percpu_ref_put(&ioctx->users);
	}

out:
	return ret;
}
#endif

/* 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 -EINVAL if the context pointed to
 *      is invalid.
 */

SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
{
	struct kioctx *ioctx = lookup_ioctx(ctx);
	if (likely(NULL != ioctx)) {
		struct ctx_rq_wait wait;
		int ret;

		init_completion(&wait.comp);
		atomic_set(&wait.count, 1);

		/* Pass requests_done to kill_ioctx() where it can be set
                 * in a thread-safe way. If we try to set it here then we have
                 * a race condition if two io_destroy() called simultaneously.
                 */
		ret = kill_ioctx(current->mm, ioctx, &wait);
		percpu_ref_put(&ioctx->users);

		/* Wait until all IO for the context are done. Otherwise kernel
                 * keep using user-space buffers even if user thinks the context
                 * is destroyed.
                 */
		if (!ret)
			wait_for_completion(&wait.comp);

		return ret;
	}
	pr_debug("EINVAL: invalid context id\n");
	return -EINVAL;
}



static int aio_setup_rw(int rw, struct iocb *iocb, struct iovec **iovec,
		bool vectored, bool compat, struct iov_iter *iter)
{
	void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
	size_t len = iocb->aio_nbytes;

	if (!vectored) {
		ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
		*iovec = NULL;
		return ret;
	}
#ifdef CONFIG_COMPAT
	if (compat)
		return compat_import_iovec(rw, buf, len, UIO_FASTIOV, iovec,
				iter);
#endif
	return import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
christoph hellwig
christoph hellwig
63
49.22%
1
9.09%
jeff moyer
jeff moyer
19
14.84%
1
9.09%
al viro
al viro
15
11.72%
3
27.27%
kent overstreet
kent overstreet
13
10.16%
2
18.18%
badari pulavarty
badari pulavarty
9
7.03%
1
9.09%
suparna bhattacharya
suparna bhattacharya
6
4.69%
1
9.09%
gu zheng
gu zheng
2
1.56%
1
9.09%
linus torvalds
linus torvalds
1
0.78%
1
9.09%
Total
128
100.00%
11
100.00%



static inline ssize_t aio_ret(struct kiocb *req, ssize_t ret)
{
	switch (ret) {
	case -EIOCBQUEUED:
		return ret;
	case -ERESTARTSYS:
	case -ERESTARTNOINTR:
	case -ERESTARTNOHAND:
	case -ERESTART_RESTARTBLOCK:
		/*
                 * There's no easy way to restart the syscall since other AIO's
                 * may be already running. Just fail this IO with EINTR.
                 */
		ret = -EINTR;
		/*FALLTHRU*/
	default:
		aio_complete(req, ret, 0);
		return 0;
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
christoph hellwig
christoph hellwig
56
87.50%
1
16.67%
suparna bhattacharya
suparna bhattacharya
3
4.69%
1
16.67%
benjamin lahaise
benjamin lahaise
2
3.12%
1
16.67%
adrian bunk
adrian bunk
1
1.56%
1
16.67%
jeff moyer
jeff moyer
1
1.56%
1
16.67%
kent overstreet
kent overstreet
1
1.56%
1
16.67%
Total
64
100.00%
6
100.00%



static ssize_t aio_read(struct kiocb *req, struct iocb *iocb, bool vectored,
		bool compat)
{
	struct file *file = req->ki_filp;
	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
	struct iov_iter iter;
	ssize_t ret;

	if (unlikely(!(file->f_mode & FMODE_READ)))
		return -EBADF;
	if (unlikely(!file->f_op->read_iter))
		return -EINVAL;

	ret = aio_setup_rw(READ, iocb, &iovec, vectored, compat, &iter);
	if (ret)
		return ret;
	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
	if (!ret)
		ret = aio_ret(req, file->f_op->read_iter(req, &iter));
	kfree(iovec);
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
christoph hellwig
christoph hellwig
113
69.75%
2
18.18%
al viro
al viro
15
9.26%
1
9.09%
kent overstreet
kent overstreet
11
6.79%
2
18.18%
suparna bhattacharya
suparna bhattacharya
6
3.70%
1
9.09%
benjamin lahaise
benjamin lahaise
6
3.70%
2
18.18%
gu zheng
gu zheng
5
3.09%
1
9.09%
badari pulavarty
badari pulavarty
4
2.47%
1
9.09%
jeff moyer
jeff moyer
2
1.23%
1
9.09%
Total
162
100.00%
11
100.00%



static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored,
		bool compat)
{
	struct file *file = req->ki_filp;
	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
	struct iov_iter iter;
	ssize_t ret;

	if (unlikely(!(file->f_mode & FMODE_WRITE)))
		return -EBADF;
	if (unlikely(!file->f_op->write_iter))
		return -EINVAL;

	ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, compat, &iter);
	if (ret)
		return ret;
	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
	if (!ret) {
		req->ki_flags |= IOCB_WRITE;
		file_start_write(file);
		ret = aio_ret(req, file->f_op->write_iter(req, &iter));
		/*
                 * We release freeze protection in aio_complete().  Fool lockdep
                 * by telling it the lock got released so that it doesn't
                 * complain about held lock when we return to userspace.
                 */
		if (S_ISREG(file_inode(file)->i_mode))
			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
	}
	kfree(iovec);
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
christoph hellwig
christoph hellwig
87
43.50%
3
18.75%
kent overstreet
kent overstreet
37
18.50%
3
18.75%
al viro
al viro
21
10.50%
4
25.00%
badari pulavarty
badari pulavarty
21
10.50%
1
6.25%
jan kara
jan kara
15
7.50%
1
6.25%
shaohua li
shaohua li
12
6.00%
1
6.25%
suparna bhattacharya
suparna bhattacharya
5
2.50%
1
6.25%
jeff moyer
jeff moyer
1
0.50%
1
6.25%
benjamin lahaise
benjamin lahaise
1
0.50%
1
6.25%
Total
200
100.00%
16
100.00%



static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
			 struct iocb *iocb, bool compat)
{
	struct aio_kiocb *req;
	struct file *file;
	ssize_t ret;

	/* enforce forwards compatibility on users */
	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
		pr_debug("EINVAL: 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: overflow check\n");
		return -EINVAL;
	}

	req = aio_get_req(ctx);
	if (unlikely(!req))
		return -EAGAIN;

	req->common.ki_filp = file = fget(iocb->aio_fildes);
	if (unlikely(!req->common.ki_filp)) {
		ret = -EBADF;
		goto out_put_req;
	}
	req->common.ki_pos = iocb->aio_offset;
	req->common.ki_complete = aio_complete;
	req->common.ki_flags = iocb_flags(req->common.ki_filp);

	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_ctx_fdget((int) iocb->aio_resfd);
		if (IS_ERR(req->ki_eventfd)) {
			ret = PTR_ERR(req->ki_eventfd);
			req->ki_eventfd = NULL;
			goto out_put_req;
		}

		req->common.ki_flags |= IOCB_EVENTFD;
	}

	ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
	if (unlikely(ret)) {
		pr_debug("EFAULT: aio_key\n");
		goto out_put_req;
	}

	req->ki_user_iocb = user_iocb;
	req->ki_user_data = iocb->aio_data;

	get_file(file);
	switch (iocb->aio_lio_opcode) {
	case IOCB_CMD_PREAD:
		ret = aio_read(&req->common, iocb, false, compat);
		break;
	case IOCB_CMD_PWRITE:
		ret = aio_write(&req->common, iocb, false, compat);
		break;
	case IOCB_CMD_PREADV:
		ret = aio_read(&req->common, iocb, true, compat);
		break;
	case IOCB_CMD_PWRITEV:
		ret = aio_write(&req->common, iocb, true, compat);
		break;
	default:
		pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
		ret = -EINVAL;
		break;
	}
	fput(file);

	if (ret && ret != -EIOCBQUEUED)
		goto out_put_req;
	return 0;
out_put_req:
	put_reqs_available(ctx, 1);
	percpu_ref_put(&ctx->reqs);
	kiocb_free(req);
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
benjamin lahaise
benjamin lahaise
164
35.19%
2
8.00%
christoph hellwig
christoph hellwig
151
32.40%
3
12.00%
davide libenzi
davide libenzi
54
11.59%
3
12.00%
kent overstreet
kent overstreet
47
10.09%
8
32.00%
suparna bhattacharya
suparna bhattacharya
25
5.36%
1
4.00%
al viro
al viro
8
1.72%
1
4.00%
james morris
james morris
7
1.50%
1
4.00%
jeff moyer
jeff moyer
5
1.07%
2
8.00%
yan zheng
yan zheng
2
0.43%
1
4.00%
kinglong mee
kinglong mee
1
0.21%
1
4.00%
adrian bunk
adrian bunk
1
0.21%
1
4.00%
andrew morton
andrew morton
1
0.21%
1
4.00%
Total
466
100.00%
25
100.00%



static long do_io_submit(aio_context_t ctx_id, long nr,
			  struct iocb __user *__user *iocbpp, bool compat)
{
	struct kioctx *ctx;
	long ret = 0;
	int i = 0;
	struct blk_plug plug;

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

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

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

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

	blk_start_plug(&plug);

	/*
         * 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, compat);
		if (ret)
			break;
	}
	blk_finish_plug(&plug);

	percpu_ref_put(&ctx->users);
	return i ? i : ret;
}

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benjamin lahaise
benjamin lahaise
176
69.57%
2
16.67%
jeff moyer
jeff moyer
54
21.34%
4
33.33%
li shaohua
li shaohua
11
4.35%
1
8.33%
andrew morton
andrew morton
5
1.98%
1
8.33%
kent overstreet
kent overstreet
5
1.98%
2
16.67%
andrea arcangeli
andrea arcangeli
1
0.40%
1
8.33%
al viro
al viro
1
0.40%
1
8.33%
Total
253
100.00%
12
100.00%

/* 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);
}

#ifdef CONFIG_COMPAT

static inline long

copy_iocb(long nr, u32 __user *ptr32, struct iocb __user * __user *ptr64)
{
	compat_uptr_t uptr;
	int i;

	for (i = 0; i < nr; ++i) {
		if (get_user(uptr, ptr32 + i))
			return -EFAULT;
		if (put_user(compat_ptr(uptr), ptr64 + i))
			return -EFAULT;
	}
	return 0;
}

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al viro
al viro
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80
100.00%
1
100.00%


#define MAX_AIO_SUBMITS 	(PAGE_SIZE/sizeof(struct iocb *))


COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
		       int, nr, u32 __user *, iocb)
{
	struct iocb __user * __user *iocb64;
	long ret;

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

	if (nr > MAX_AIO_SUBMITS)
		nr = MAX_AIO_SUBMITS;

	iocb64 = compat_alloc_user_space(nr * sizeof(*iocb64));
	ret = copy_iocb(nr, iocb, iocb64);
	if (!ret)
		ret = do_io_submit(ctx_id, nr, iocb64, 1);
	return ret;
}
#endif

/* lookup_kiocb
 *      Finds a given iocb for cancellation.
 */

static struct aio_kiocb *

lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key)
{
	struct aio_kiocb *kiocb;

	assert_spin_locked(&ctx->ctx_lock);

	if (key != KIOCB_KEY)
		return NULL;

	/* TODO: use a hash or array, this sucks. */
	list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
		if (kiocb->ki_user_iocb == iocb)
			return kiocb;
	}
	return NULL;
}

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benjamin lahaise
42
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2
28.57%
kent overstreet
kent overstreet
9
13.04%
1
14.29%
christoph hellwig
christoph hellwig
8
11.59%
1
14.29%
zach brown
zach brown
8
11.59%
1
14.29%
linus torvalds
linus torvalds
1
1.45%
1
14.29%
adrian bunk
adrian bunk
1
1.45%
1
14.29%
Total
69
100.00%
7
100.00%

/* 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.
 */

SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
		struct io_event __user *, result)
{
	struct kioctx *ctx;
	struct aio_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);

	kiocb = lookup_kiocb(ctx, iocb, key);
	if (kiocb)
		ret = kiocb_cancel(kiocb);
	else
		ret = -EINVAL;

	spin_unlock_irq(&ctx->ctx_lock);

	if (!ret) {
		/*
                 * The result argument is no longer used - the io_event is
                 * always delivered via the ring buffer. -EINPROGRESS indicates
                 * cancellation is progress:
                 */
		ret = -EINPROGRESS;
	}

	percpu_ref_put(&ctx->users);

	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. 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.  Will fail with -ENOSYS if not implemented.
 */

SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
		long, min_nr,
		long, nr,
		struct io_event __user *, events,
		struct timespec __user *, timeout)
{
	struct kioctx *ioctx = lookup_ioctx(ctx_id);
	long ret = -EINVAL;

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

#ifdef CONFIG_COMPAT

COMPAT_SYSCALL_DEFINE5(io_getevents, compat_aio_context_t, ctx_id,
		       compat_long_t, min_nr,
		       compat_long_t, nr,
		       struct io_event __user *, events,
		       struct compat_timespec __user *, timeout)
{
	struct timespec t;
	struct timespec __user *ut = NULL;

	if (timeout) {
		if (compat_get_timespec(&t, timeout))
			return -EFAULT;

		ut = compat_alloc_user_space(sizeof(*ut));
		if (copy_to_user(ut, &t, sizeof(t)))
			return -EFAULT;
	}
	return sys_io_getevents(ctx_id, min_nr, nr, events, ut);
}
#endif
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benjamin lahaise
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kent overstreet
1678
22.08%
26
16.67%
al viro
al viro
608
8.00%
16
10.26%
christoph hellwig
christoph hellwig
575
7.57%
5
3.21%
suparna bhattacharya
suparna bhattacharya
426
5.61%
1
0.64%
gu zheng
gu zheng
337
4.43%
7
4.49%
jeff moyer
jeff moyer
143
1.88%
6
3.85%
jens axboe
jens axboe
117
1.54%
3
1.92%
oleg nesterov
oleg nesterov
117
1.54%
3
1.92%
pavel emelianov
pavel emelianov
110
1.45%
1
0.64%
linus torvalds
linus torvalds
107
1.41%
5
3.21%
zach brown
zach brown
102
1.34%
4
2.56%
davide libenzi
davide libenzi
86
1.13%
4
2.56%
heiko carstens
heiko carstens
60
0.79%
1
0.64%
jan kara
jan kara
52
0.68%
1
0.64%
anatol pomozov
anatol pomozov
37
0.49%
1
0.64%
badari pulavarty
badari pulavarty
37
0.49%
2
1.28%
andrew morton
andrew morton
33
0.43%
6
3.85%
tejun heo
tejun heo
28
0.37%
4
2.56%
jann horn
jann horn
24
0.32%
1
0.64%
shaohua li
shaohua li
24
0.32%
1
0.64%
fam zheng
fam zheng
21
0.28%
1
0.64%
michal hocko
michal hocko
20
0.26%
1
0.64%
rasmus villemoes
rasmus villemoes
12
0.16%
1
0.64%
li shaohua
li shaohua
11
0.14%
1
0.64%
james morris
james morris
10
0.13%
1
0.64%
ken chen
ken chen
10
0.13%
1
0.64%
kenneth w. chen
kenneth w. chen
8
0.11%
1
0.64%
sasha levin
sasha levin
8
0.11%
1
0.64%
christoph lameter
christoph lameter
6
0.08%
2
1.28%
gleb natapov
gleb natapov
6
0.08%
1
0.64%
h hartley sweeten
h hartley sweeten
5
0.07%
1
0.64%
dan carpenter
dan carpenter
5
0.07%
1
0.64%
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darrick j. wong
4
0.05%
1
0.64%
quentin barnes
quentin barnes
4
0.05%
1
0.64%
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dave chinner
4
0.05%
1
0.64%
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adrian bunk
4
0.05%
3
1.92%
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william lee irwin iii
4
0.05%
1
0.64%
kinglong mee
kinglong mee
3
0.04%
1
0.64%
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michel lespinasse
3
0.04%
2
1.28%
arnd bergmann
arnd bergmann
3
0.04%
1
0.64%
michael s. tsirkin
michael s. tsirkin
3
0.04%
1
0.64%
ingo molnar
ingo molnar
2
0.03%
1
0.64%
yan zheng
yan zheng
2
0.03%
1
0.64%
tang chen
tang chen
1
0.01%
1
0.64%
thomas gleixner
thomas gleixner
1
0.01%
1
0.64%
robert p. j. day
robert p. j. day
1
0.01%
1
0.64%
oliver neukum
oliver neukum
1
0.01%
1
0.64%
satoru takeuchi
satoru takeuchi
1
0.01%
1
0.64%
paul gortmaker
paul gortmaker
1
0.01%
1
0.64%
stephen hemminger
stephen hemminger
1
0.01%
1
0.64%
andrea arcangeli
andrea arcangeli
1
0.01%
1
0.64%
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7600
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156
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