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![Tang Chen](/assets/img/avatar_default.png)
ctx->ctx_lock should be ctx->completion_lock. Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1319 lines
33 KiB
C
1319 lines
33 KiB
C
/*
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* An async IO implementation for Linux
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* Written by Benjamin LaHaise <bcrl@kvack.org>
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*
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* Implements an efficient asynchronous io interface.
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*
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* Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
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*
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* See ../COPYING for licensing terms.
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*/
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#define pr_fmt(fmt) "%s: " fmt, __func__
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/aio_abi.h>
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#include <linux/export.h>
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#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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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/mmu_context.h>
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#include <linux/slab.h>
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#include <linux/timer.h>
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#include <linux/aio.h>
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#include <linux/highmem.h>
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#include <linux/workqueue.h>
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#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>
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#include <asm/uaccess.h>
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#include "internal.h"
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#define AIO_RING_MAGIC 0xa10a10a1
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#define AIO_RING_COMPAT_FEATURES 1
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#define AIO_RING_INCOMPAT_FEATURES 0
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struct aio_ring {
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unsigned id; /* kernel internal index number */
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unsigned nr; /* number of io_events */
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unsigned head;
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unsigned tail;
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unsigned magic;
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unsigned compat_features;
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unsigned incompat_features;
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unsigned header_length; /* size of aio_ring */
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struct io_event io_events[0];
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}; /* 128 bytes + ring size */
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#define AIO_RING_PAGES 8
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struct kioctx {
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atomic_t users;
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atomic_t dead;
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/* This needs improving */
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unsigned long user_id;
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struct hlist_node list;
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/*
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* This is what userspace passed to io_setup(), it's not used for
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* anything but counting against the global max_reqs quota.
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*
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* The real limit is nr_events - 1, which will be larger (see
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* aio_setup_ring())
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*/
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unsigned max_reqs;
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/* Size of ringbuffer, in units of struct io_event */
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unsigned nr_events;
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unsigned long mmap_base;
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unsigned long mmap_size;
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struct page **ring_pages;
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long nr_pages;
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struct rcu_head rcu_head;
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struct work_struct rcu_work;
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struct {
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atomic_t reqs_active;
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} ____cacheline_aligned_in_smp;
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struct {
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spinlock_t ctx_lock;
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struct list_head active_reqs; /* used for cancellation */
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} ____cacheline_aligned_in_smp;
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struct {
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struct mutex ring_lock;
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wait_queue_head_t wait;
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} ____cacheline_aligned_in_smp;
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struct {
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unsigned tail;
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spinlock_t completion_lock;
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} ____cacheline_aligned_in_smp;
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struct page *internal_pages[AIO_RING_PAGES];
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};
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/*------ sysctl variables----*/
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static DEFINE_SPINLOCK(aio_nr_lock);
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unsigned long aio_nr; /* current system wide number of aio requests */
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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;
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static struct kmem_cache *kioctx_cachep;
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/* aio_setup
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* Creates the slab caches used by the aio routines, panic on
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* failure as this is done early during the boot sequence.
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*/
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static int __init aio_setup(void)
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{
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kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
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kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
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pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
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return 0;
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}
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__initcall(aio_setup);
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static void aio_free_ring(struct kioctx *ctx)
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{
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long i;
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for (i = 0; i < ctx->nr_pages; i++)
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put_page(ctx->ring_pages[i]);
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if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
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kfree(ctx->ring_pages);
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}
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static int aio_setup_ring(struct kioctx *ctx)
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{
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struct aio_ring *ring;
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unsigned nr_events = ctx->max_reqs;
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struct mm_struct *mm = current->mm;
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unsigned long size, populate;
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int nr_pages;
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/* Compensate for the ring buffer's head/tail overlap entry */
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nr_events += 2; /* 1 is required, 2 for good luck */
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size = sizeof(struct aio_ring);
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size += sizeof(struct io_event) * nr_events;
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nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
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if (nr_pages < 0)
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return -EINVAL;
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nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
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ctx->nr_events = 0;
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ctx->ring_pages = ctx->internal_pages;
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if (nr_pages > AIO_RING_PAGES) {
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ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
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GFP_KERNEL);
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if (!ctx->ring_pages)
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return -ENOMEM;
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}
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ctx->mmap_size = nr_pages * PAGE_SIZE;
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pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
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down_write(&mm->mmap_sem);
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ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size,
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PROT_READ|PROT_WRITE,
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MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate);
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if (IS_ERR((void *)ctx->mmap_base)) {
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up_write(&mm->mmap_sem);
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ctx->mmap_size = 0;
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aio_free_ring(ctx);
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return -EAGAIN;
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}
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pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
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ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
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1, 0, ctx->ring_pages, NULL);
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up_write(&mm->mmap_sem);
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if (unlikely(ctx->nr_pages != nr_pages)) {
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aio_free_ring(ctx);
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return -EAGAIN;
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}
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if (populate)
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mm_populate(ctx->mmap_base, populate);
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ctx->user_id = ctx->mmap_base;
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ctx->nr_events = nr_events; /* trusted copy */
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ring = kmap_atomic(ctx->ring_pages[0]);
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ring->nr = nr_events; /* user copy */
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ring->id = ctx->user_id;
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ring->head = ring->tail = 0;
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ring->magic = AIO_RING_MAGIC;
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ring->compat_features = AIO_RING_COMPAT_FEATURES;
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ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
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ring->header_length = sizeof(struct aio_ring);
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kunmap_atomic(ring);
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flush_dcache_page(ctx->ring_pages[0]);
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return 0;
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}
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#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
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#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
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#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
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void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
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{
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struct kioctx *ctx = req->ki_ctx;
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unsigned long flags;
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spin_lock_irqsave(&ctx->ctx_lock, flags);
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if (!req->ki_list.next)
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list_add(&req->ki_list, &ctx->active_reqs);
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req->ki_cancel = cancel;
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spin_unlock_irqrestore(&ctx->ctx_lock, flags);
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}
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EXPORT_SYMBOL(kiocb_set_cancel_fn);
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static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb,
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struct io_event *res)
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{
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kiocb_cancel_fn *old, *cancel;
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int ret = -EINVAL;
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/*
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* Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
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* actually has a cancel function, hence the cmpxchg()
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*/
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cancel = ACCESS_ONCE(kiocb->ki_cancel);
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do {
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if (!cancel || cancel == KIOCB_CANCELLED)
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return ret;
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old = cancel;
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cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
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} while (cancel != old);
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atomic_inc(&kiocb->ki_users);
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spin_unlock_irq(&ctx->ctx_lock);
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memset(res, 0, sizeof(*res));
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res->obj = (u64)(unsigned long)kiocb->ki_obj.user;
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res->data = kiocb->ki_user_data;
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ret = cancel(kiocb, res);
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spin_lock_irq(&ctx->ctx_lock);
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return ret;
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}
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static void free_ioctx_rcu(struct rcu_head *head)
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{
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struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
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kmem_cache_free(kioctx_cachep, ctx);
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}
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/*
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* When this function runs, the kioctx has been removed from the "hash table"
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* and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
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* now it's safe to cancel any that need to be.
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*/
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static void free_ioctx(struct kioctx *ctx)
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{
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struct aio_ring *ring;
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struct io_event res;
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struct kiocb *req;
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unsigned head, avail;
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spin_lock_irq(&ctx->ctx_lock);
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while (!list_empty(&ctx->active_reqs)) {
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req = list_first_entry(&ctx->active_reqs,
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struct kiocb, ki_list);
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list_del_init(&req->ki_list);
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kiocb_cancel(ctx, req, &res);
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}
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spin_unlock_irq(&ctx->ctx_lock);
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ring = kmap_atomic(ctx->ring_pages[0]);
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head = ring->head;
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kunmap_atomic(ring);
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while (atomic_read(&ctx->reqs_active) > 0) {
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wait_event(ctx->wait,
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head != ctx->tail ||
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atomic_read(&ctx->reqs_active) <= 0);
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avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
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atomic_sub(avail, &ctx->reqs_active);
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head += avail;
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head %= ctx->nr_events;
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}
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WARN_ON(atomic_read(&ctx->reqs_active) < 0);
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aio_free_ring(ctx);
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pr_debug("freeing %p\n", ctx);
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/*
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* Here the call_rcu() is between the wait_event() for reqs_active to
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* hit 0, and freeing the ioctx.
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*
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* aio_complete() decrements reqs_active, but it has to touch the ioctx
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* after to issue a wakeup so we use rcu.
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*/
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call_rcu(&ctx->rcu_head, free_ioctx_rcu);
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}
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static void put_ioctx(struct kioctx *ctx)
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{
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if (unlikely(atomic_dec_and_test(&ctx->users)))
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free_ioctx(ctx);
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}
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/* ioctx_alloc
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* Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
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*/
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static struct kioctx *ioctx_alloc(unsigned nr_events)
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{
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struct mm_struct *mm = current->mm;
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struct kioctx *ctx;
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int err = -ENOMEM;
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/* Prevent overflows */
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if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
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(nr_events > (0x10000000U / sizeof(struct kiocb)))) {
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pr_debug("ENOMEM: nr_events too high\n");
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return ERR_PTR(-EINVAL);
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}
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if (!nr_events || (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)
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return ERR_PTR(-ENOMEM);
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ctx->max_reqs = nr_events;
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atomic_set(&ctx->users, 2);
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atomic_set(&ctx->dead, 0);
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spin_lock_init(&ctx->ctx_lock);
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spin_lock_init(&ctx->completion_lock);
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mutex_init(&ctx->ring_lock);
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init_waitqueue_head(&ctx->wait);
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INIT_LIST_HEAD(&ctx->active_reqs);
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if (aio_setup_ring(ctx) < 0)
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goto out_freectx;
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/* limit the number of system wide aios */
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spin_lock(&aio_nr_lock);
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if (aio_nr + nr_events > aio_max_nr ||
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aio_nr + nr_events < aio_nr) {
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spin_unlock(&aio_nr_lock);
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goto out_cleanup;
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}
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aio_nr += ctx->max_reqs;
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spin_unlock(&aio_nr_lock);
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/* now link into global list. */
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spin_lock(&mm->ioctx_lock);
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hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
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spin_unlock(&mm->ioctx_lock);
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pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
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ctx, ctx->user_id, mm, ctx->nr_events);
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return ctx;
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out_cleanup:
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err = -EAGAIN;
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aio_free_ring(ctx);
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out_freectx:
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kmem_cache_free(kioctx_cachep, ctx);
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pr_debug("error allocating ioctx %d\n", err);
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return ERR_PTR(err);
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}
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static void kill_ioctx_work(struct work_struct *work)
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{
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struct kioctx *ctx = container_of(work, struct kioctx, rcu_work);
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wake_up_all(&ctx->wait);
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put_ioctx(ctx);
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}
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static void kill_ioctx_rcu(struct rcu_head *head)
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{
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struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
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INIT_WORK(&ctx->rcu_work, kill_ioctx_work);
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schedule_work(&ctx->rcu_work);
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}
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/* kill_ioctx
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* Cancels all outstanding aio requests on an aio context. Used
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* when the processes owning a context have all exited to encourage
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* the rapid destruction of the kioctx.
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*/
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static void kill_ioctx(struct kioctx *ctx)
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{
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if (!atomic_xchg(&ctx->dead, 1)) {
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hlist_del_rcu(&ctx->list);
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|
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/*
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* It'd be more correct to do this in free_ioctx(), after all
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* the outstanding kiocbs have finished - but by then io_destroy
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* has already returned, so io_setup() could potentially return
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* -EAGAIN with no ioctxs actually in use (as far as userspace
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* could tell).
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*/
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spin_lock(&aio_nr_lock);
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BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
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aio_nr -= ctx->max_reqs;
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spin_unlock(&aio_nr_lock);
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if (ctx->mmap_size)
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vm_munmap(ctx->mmap_base, ctx->mmap_size);
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/* Between hlist_del_rcu() and dropping the initial ref */
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call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
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}
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}
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|
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/* wait_on_sync_kiocb:
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* Waits on the given sync kiocb to complete.
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*/
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ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
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{
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while (atomic_read(&iocb->ki_users)) {
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set_current_state(TASK_UNINTERRUPTIBLE);
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if (!atomic_read(&iocb->ki_users))
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break;
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io_schedule();
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}
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__set_current_state(TASK_RUNNING);
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return iocb->ki_user_data;
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}
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EXPORT_SYMBOL(wait_on_sync_kiocb);
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|
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/*
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* exit_aio: called when the last user of mm goes away. At this point, there is
|
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* no way for any new requests to be submited or any of the io_* syscalls to be
|
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* called on the context.
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*
|
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* There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
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* them.
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*/
|
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void exit_aio(struct mm_struct *mm)
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{
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struct kioctx *ctx;
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struct hlist_node *n;
|
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|
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hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) {
|
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if (1 != atomic_read(&ctx->users))
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printk(KERN_DEBUG
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"exit_aio:ioctx still alive: %d %d %d\n",
|
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atomic_read(&ctx->users),
|
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atomic_read(&ctx->dead),
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atomic_read(&ctx->reqs_active));
|
|
/*
|
|
* We don't need to bother with munmap() here -
|
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* exit_mmap(mm) is coming and it'll unmap everything.
|
|
* Since aio_free_ring() uses non-zero ->mmap_size
|
|
* as indicator that it needs to unmap the area,
|
|
* just set it to 0; aio_free_ring() is the only
|
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* place that uses ->mmap_size, so it's safe.
|
|
*/
|
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ctx->mmap_size = 0;
|
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|
|
kill_ioctx(ctx);
|
|
}
|
|
}
|
|
|
|
/* aio_get_req
|
|
* Allocate a slot for an aio request. Increments the ki_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->ki_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.
|
|
*/
|
|
static inline struct kiocb *aio_get_req(struct kioctx *ctx)
|
|
{
|
|
struct kiocb *req;
|
|
|
|
if (atomic_read(&ctx->reqs_active) >= ctx->nr_events)
|
|
return NULL;
|
|
|
|
if (atomic_inc_return(&ctx->reqs_active) > ctx->nr_events - 1)
|
|
goto out_put;
|
|
|
|
req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
|
|
if (unlikely(!req))
|
|
goto out_put;
|
|
|
|
atomic_set(&req->ki_users, 2);
|
|
req->ki_ctx = ctx;
|
|
|
|
return req;
|
|
out_put:
|
|
atomic_dec(&ctx->reqs_active);
|
|
return NULL;
|
|
}
|
|
|
|
static void kiocb_free(struct kiocb *req)
|
|
{
|
|
if (req->ki_filp)
|
|
fput(req->ki_filp);
|
|
if (req->ki_eventfd != NULL)
|
|
eventfd_ctx_put(req->ki_eventfd);
|
|
if (req->ki_dtor)
|
|
req->ki_dtor(req);
|
|
if (req->ki_iovec != &req->ki_inline_vec)
|
|
kfree(req->ki_iovec);
|
|
kmem_cache_free(kiocb_cachep, req);
|
|
}
|
|
|
|
void aio_put_req(struct kiocb *req)
|
|
{
|
|
if (atomic_dec_and_test(&req->ki_users))
|
|
kiocb_free(req);
|
|
}
|
|
EXPORT_SYMBOL(aio_put_req);
|
|
|
|
static struct kioctx *lookup_ioctx(unsigned long ctx_id)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct kioctx *ctx, *ret = NULL;
|
|
|
|
rcu_read_lock();
|
|
|
|
hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) {
|
|
if (ctx->user_id == ctx_id) {
|
|
atomic_inc(&ctx->users);
|
|
ret = ctx;
|
|
break;
|
|
}
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
/* aio_complete
|
|
* Called when the io request on the given iocb is complete.
|
|
*/
|
|
void aio_complete(struct kiocb *iocb, long res, long res2)
|
|
{
|
|
struct kioctx *ctx = iocb->ki_ctx;
|
|
struct aio_ring *ring;
|
|
struct io_event *ev_page, *event;
|
|
unsigned long flags;
|
|
unsigned tail, pos;
|
|
|
|
/*
|
|
* 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
|
|
*/
|
|
if (is_sync_kiocb(iocb)) {
|
|
BUG_ON(atomic_read(&iocb->ki_users) != 1);
|
|
iocb->ki_user_data = res;
|
|
atomic_set(&iocb->ki_users, 0);
|
|
wake_up_process(iocb->ki_obj.tsk);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Take rcu_read_lock() in case the kioctx is being destroyed, as we
|
|
* need to issue a wakeup after decrementing reqs_active.
|
|
*/
|
|
rcu_read_lock();
|
|
|
|
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);
|
|
}
|
|
|
|
/*
|
|
* cancelled requests don't get events, userland was given one
|
|
* when the event got cancelled.
|
|
*/
|
|
if (unlikely(xchg(&iocb->ki_cancel,
|
|
KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
|
|
atomic_dec(&ctx->reqs_active);
|
|
/* Still need the wake_up in case free_ioctx is waiting */
|
|
goto put_rq;
|
|
}
|
|
|
|
/*
|
|
* 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_obj.user;
|
|
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_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 */
|
|
|
|
ctx->tail = tail;
|
|
|
|
ring = kmap_atomic(ctx->ring_pages[0]);
|
|
ring->tail = tail;
|
|
kunmap_atomic(ring);
|
|
flush_dcache_page(ctx->ring_pages[0]);
|
|
|
|
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);
|
|
|
|
put_rq:
|
|
/* everything turned out well, dispose of the aiocb. */
|
|
aio_put_req(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);
|
|
|
|
rcu_read_unlock();
|
|
}
|
|
EXPORT_SYMBOL(aio_complete);
|
|
|
|
/* aio_read_events
|
|
* 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, pos;
|
|
long ret = 0;
|
|
int copy_ret;
|
|
|
|
mutex_lock(&ctx->ring_lock);
|
|
|
|
ring = kmap_atomic(ctx->ring_pages[0]);
|
|
head = ring->head;
|
|
kunmap_atomic(ring);
|
|
|
|
pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events);
|
|
|
|
if (head == ctx->tail)
|
|
goto out;
|
|
|
|
while (ret < nr) {
|
|
long avail;
|
|
struct io_event *ev;
|
|
struct page *page;
|
|
|
|
avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
|
|
if (head == ctx->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, ctx->tail);
|
|
|
|
atomic_sub(ret, &ctx->reqs_active);
|
|
out:
|
|
mutex_unlock(&ctx->ring_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
static long read_events(struct kioctx *ctx, long min_nr, long nr,
|
|
struct io_event __user *event,
|
|
struct timespec __user *timeout)
|
|
{
|
|
ktime_t until = { .tv64 = 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.
|
|
*/
|
|
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;
|
|
}
|
|
|
|
/* 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: io_setup: 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(ioctx);
|
|
put_ioctx(ioctx);
|
|
}
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/* sys_io_destroy:
|
|
* Destroy the aio_context specified. May cancel any outstanding
|
|
* AIOs and block on completion. Will fail with -ENOSYS if not
|
|
* implemented. May fail with -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)) {
|
|
kill_ioctx(ioctx);
|
|
put_ioctx(ioctx);
|
|
return 0;
|
|
}
|
|
pr_debug("EINVAL: io_destroy: invalid context id\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
|
|
{
|
|
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++;
|
|
}
|
|
}
|
|
|
|
/* the caller should not have done more io than what fit in
|
|
* the remaining iovecs */
|
|
BUG_ON(ret > 0 && iocb->ki_left == 0);
|
|
}
|
|
|
|
typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
|
|
unsigned long, loff_t);
|
|
|
|
static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
ssize_t ret = 0;
|
|
|
|
/* This matches the pread()/pwrite() logic */
|
|
if (iocb->ki_pos < 0)
|
|
return -EINVAL;
|
|
|
|
if (rw == WRITE)
|
|
file_start_write(file);
|
|
do {
|
|
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 &&
|
|
(rw == WRITE ||
|
|
(!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
|
|
if (rw == WRITE)
|
|
file_end_write(file);
|
|
|
|
/* This means we must have transferred all that we could */
|
|
/* No need to retry anymore */
|
|
if ((ret == 0) || (iocb->ki_left == 0))
|
|
ret = iocb->ki_nbytes - iocb->ki_left;
|
|
|
|
/* If we managed to write some out we return that, rather than
|
|
* the eventual error. */
|
|
if (rw == WRITE
|
|
&& ret < 0 && ret != -EIOCBQUEUED
|
|
&& iocb->ki_nbytes - iocb->ki_left)
|
|
ret = iocb->ki_nbytes - iocb->ki_left;
|
|
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
|
|
{
|
|
ssize_t ret;
|
|
|
|
kiocb->ki_nr_segs = kiocb->ki_nbytes;
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
if (compat)
|
|
ret = compat_rw_copy_check_uvector(rw,
|
|
(struct compat_iovec __user *)kiocb->ki_buf,
|
|
kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
|
|
&kiocb->ki_iovec);
|
|
else
|
|
#endif
|
|
ret = rw_copy_check_uvector(rw,
|
|
(struct iovec __user *)kiocb->ki_buf,
|
|
kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
|
|
&kiocb->ki_iovec);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
/* ki_nbytes now reflect bytes instead of segs */
|
|
kiocb->ki_nbytes = ret;
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
|
|
{
|
|
if (unlikely(!access_ok(!rw, kiocb->ki_buf, kiocb->ki_nbytes)))
|
|
return -EFAULT;
|
|
|
|
kiocb->ki_iovec = &kiocb->ki_inline_vec;
|
|
kiocb->ki_iovec->iov_base = kiocb->ki_buf;
|
|
kiocb->ki_iovec->iov_len = kiocb->ki_nbytes;
|
|
kiocb->ki_nr_segs = 1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* aio_setup_iocb:
|
|
* Performs the initial checks and aio retry method
|
|
* setup for the kiocb at the time of io submission.
|
|
*/
|
|
static ssize_t aio_run_iocb(struct kiocb *req, bool compat)
|
|
{
|
|
struct file *file = req->ki_filp;
|
|
ssize_t ret;
|
|
int rw;
|
|
fmode_t mode;
|
|
aio_rw_op *rw_op;
|
|
|
|
switch (req->ki_opcode) {
|
|
case IOCB_CMD_PREAD:
|
|
case IOCB_CMD_PREADV:
|
|
mode = FMODE_READ;
|
|
rw = READ;
|
|
rw_op = file->f_op->aio_read;
|
|
goto rw_common;
|
|
|
|
case IOCB_CMD_PWRITE:
|
|
case IOCB_CMD_PWRITEV:
|
|
mode = FMODE_WRITE;
|
|
rw = WRITE;
|
|
rw_op = file->f_op->aio_write;
|
|
goto rw_common;
|
|
rw_common:
|
|
if (unlikely(!(file->f_mode & mode)))
|
|
return -EBADF;
|
|
|
|
if (!rw_op)
|
|
return -EINVAL;
|
|
|
|
ret = (req->ki_opcode == IOCB_CMD_PREADV ||
|
|
req->ki_opcode == IOCB_CMD_PWRITEV)
|
|
? aio_setup_vectored_rw(rw, req, compat)
|
|
: aio_setup_single_vector(rw, req);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
req->ki_nbytes = ret;
|
|
req->ki_left = ret;
|
|
|
|
ret = aio_rw_vect_retry(req, rw, rw_op);
|
|
break;
|
|
|
|
case IOCB_CMD_FDSYNC:
|
|
if (!file->f_op->aio_fsync)
|
|
return -EINVAL;
|
|
|
|
ret = file->f_op->aio_fsync(req, 1);
|
|
break;
|
|
|
|
case IOCB_CMD_FSYNC:
|
|
if (!file->f_op->aio_fsync)
|
|
return -EINVAL;
|
|
|
|
ret = file->f_op->aio_fsync(req, 0);
|
|
break;
|
|
|
|
default:
|
|
pr_debug("EINVAL: no operation provided\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (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;
|
|
aio_complete(req, ret, 0);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
|
|
struct iocb *iocb, bool compat)
|
|
{
|
|
struct kiocb *req;
|
|
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: io_submit: overflow check\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
req = aio_get_req(ctx);
|
|
if (unlikely(!req))
|
|
return -EAGAIN;
|
|
|
|
req->ki_filp = fget(iocb->aio_fildes);
|
|
if (unlikely(!req->ki_filp)) {
|
|
ret = -EBADF;
|
|
goto out_put_req;
|
|
}
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
|
|
if (unlikely(ret)) {
|
|
pr_debug("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;
|
|
|
|
ret = aio_run_iocb(req, compat);
|
|
if (ret)
|
|
goto out_put_req;
|
|
|
|
aio_put_req(req); /* drop extra ref to req */
|
|
return 0;
|
|
out_put_req:
|
|
atomic_dec(&ctx->reqs_active);
|
|
aio_put_req(req); /* drop extra ref to req */
|
|
aio_put_req(req); /* drop i/o ref to req */
|
|
return ret;
|
|
}
|
|
|
|
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);
|
|
|
|
put_ioctx(ctx);
|
|
return i ? i : ret;
|
|
}
|
|
|
|
/* sys_io_submit:
|
|
* Queue the nr iocbs pointed to by iocbpp for processing. Returns
|
|
* the number of iocbs queued. May return -EINVAL if the aio_context
|
|
* specified by ctx_id is invalid, if nr is < 0, if the iocb at
|
|
* *iocbpp[0] is not properly initialized, if the operation specified
|
|
* is invalid for the file descriptor in the iocb. May fail with
|
|
* -EFAULT if any of the data structures point to invalid data. May
|
|
* fail with -EBADF if the file descriptor specified in the first
|
|
* iocb is invalid. May fail with -EAGAIN if insufficient resources
|
|
* are available to queue any iocbs. Will return 0 if nr is 0. Will
|
|
* fail with -ENOSYS if not implemented.
|
|
*/
|
|
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);
|
|
}
|
|
|
|
/* lookup_kiocb
|
|
* Finds a given iocb for cancellation.
|
|
*/
|
|
static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
|
|
u32 key)
|
|
{
|
|
struct list_head *pos;
|
|
|
|
assert_spin_locked(&ctx->ctx_lock);
|
|
|
|
if (key != KIOCB_KEY)
|
|
return NULL;
|
|
|
|
/* 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)
|
|
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.
|
|
*/
|
|
SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
|
|
struct io_event __user *, result)
|
|
{
|
|
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);
|
|
|
|
kiocb = lookup_kiocb(ctx, iocb, key);
|
|
if (kiocb)
|
|
ret = kiocb_cancel(ctx, kiocb, &res);
|
|
else
|
|
ret = -EINVAL;
|
|
|
|
spin_unlock_irq(&ctx->ctx_lock);
|
|
|
|
if (!ret) {
|
|
/* Cancellation succeeded -- copy the result
|
|
* into the user's buffer.
|
|
*/
|
|
if (copy_to_user(result, &res, sizeof(res)))
|
|
ret = -EFAULT;
|
|
}
|
|
|
|
put_ioctx(ctx);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* io_getevents:
|
|
* Attempts to read at least min_nr events and up to nr events from
|
|
* the completion queue for the aio_context specified by ctx_id. 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);
|
|
put_ioctx(ioctx);
|
|
}
|
|
return ret;
|
|
}
|