/* * 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/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 <asm/kmap_types.h> #include <asm/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; 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 { atomic_t users; atomic_t dead; /* This needs improving */ unsigned long user_id; struct hlist_node list; /* * 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 rcu_head rcu_head; struct work_struct rcu_work; struct { atomic_t reqs_active; } ____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; spinlock_t completion_lock; } ____cacheline_aligned_in_smp; struct page *internal_pages[AIO_RING_PAGES]; }; /*------ 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; /* 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) { kiocb_cachep = KMEM_CACHE(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; } __initcall(aio_setup); static void aio_free_ring(struct kioctx *ctx) { long i; for (i = 0; i < ctx->nr_pages; i++) put_page(ctx->ring_pages[i]); if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) kfree(ctx->ring_pages); } 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, populate; int nr_pages; /* Compensate for the ring buffer's head/tail overlap entry */ nr_events += 2; /* 1 is required, 2 for good luck */ size = sizeof(struct aio_ring); size += sizeof(struct io_event) * nr_events; nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; if (nr_pages < 0) return -EINVAL; nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); ctx->nr_events = 0; 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) return -ENOMEM; } ctx->mmap_size = nr_pages * PAGE_SIZE; pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size); down_write(&mm->mmap_sem); ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate); if (IS_ERR((void *)ctx->mmap_base)) { up_write(&mm->mmap_sem); ctx->mmap_size = 0; aio_free_ring(ctx); return -EAGAIN; } pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base); ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages, 1, 0, ctx->ring_pages, NULL); up_write(&mm->mmap_sem); if (unlikely(ctx->nr_pages != nr_pages)) { aio_free_ring(ctx); return -EAGAIN; } if (populate) mm_populate(ctx->mmap_base, populate); 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 = ctx->user_id; ring->head = ring->tail = 0; ring->magic = AIO_RING_MAGIC; ring->compat_features = AIO_RING_COMPAT_FEATURES; ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; ring->header_length = sizeof(struct aio_ring); kunmap_atomic(ring); flush_dcache_page(ctx->ring_pages[0]); return 0; } #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 *req, kiocb_cancel_fn *cancel) { 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); } EXPORT_SYMBOL(kiocb_set_cancel_fn); static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb, struct io_event *res) { kiocb_cancel_fn *old, *cancel; int ret = -EINVAL; /* * 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 ret; old = cancel; cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED); } while (cancel != old); atomic_inc(&kiocb->ki_users); spin_unlock_irq(&ctx->ctx_lock); memset(res, 0, sizeof(*res)); res->obj = (u64)(unsigned long)kiocb->ki_obj.user; res->data = kiocb->ki_user_data; ret = cancel(kiocb, res); spin_lock_irq(&ctx->ctx_lock); return ret; } static void free_ioctx_rcu(struct rcu_head *head) { struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); kmem_cache_free(kioctx_cachep, ctx); } /* * 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(struct kioctx *ctx) { struct aio_ring *ring; struct io_event res; struct kiocb *req; unsigned head, avail; spin_lock_irq(&ctx->ctx_lock); while (!list_empty(&ctx->active_reqs)) { req = list_first_entry(&ctx->active_reqs, struct kiocb, ki_list); list_del_init(&req->ki_list); kiocb_cancel(ctx, req, &res); } spin_unlock_irq(&ctx->ctx_lock); ring = kmap_atomic(ctx->ring_pages[0]); head = ring->head; kunmap_atomic(ring); while (atomic_read(&ctx->reqs_active) > 0) { wait_event(ctx->wait, head != ctx->tail || atomic_read(&ctx->reqs_active) <= 0); avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; atomic_sub(avail, &ctx->reqs_active); head += avail; head %= ctx->nr_events; } WARN_ON(atomic_read(&ctx->reqs_active) < 0); aio_free_ring(ctx); pr_debug("freeing %p\n", ctx); /* * Here the call_rcu() is between the wait_event() for reqs_active to * hit 0, and freeing the ioctx. * * aio_complete() decrements reqs_active, but it has to touch the ioctx * after to issue a wakeup so we use rcu. */ call_rcu(&ctx->rcu_head, free_ioctx_rcu); } static void put_ioctx(struct kioctx *ctx) { if (unlikely(atomic_dec_and_test(&ctx->users))) free_ioctx(ctx); } /* 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; /* Prevent overflows */ if ((nr_events > (0x10000000U / sizeof(struct io_event))) || (nr_events > (0x10000000U / sizeof(struct kiocb)))) { pr_debug("ENOMEM: nr_events too high\n"); return ERR_PTR(-EINVAL); } if (!nr_events || (unsigned long)nr_events > aio_max_nr) return ERR_PTR(-EAGAIN); ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); if (!ctx) return ERR_PTR(-ENOMEM); ctx->max_reqs = nr_events; atomic_set(&ctx->users, 2); atomic_set(&ctx->dead, 0); spin_lock_init(&ctx->ctx_lock); spin_lock_init(&ctx->completion_lock); mutex_init(&ctx->ring_lock); init_waitqueue_head(&ctx->wait); INIT_LIST_HEAD(&ctx->active_reqs); if (aio_setup_ring(ctx) < 0) goto out_freectx; /* limit the number of system wide aios */ spin_lock(&aio_nr_lock); if (aio_nr + nr_events > aio_max_nr || aio_nr + nr_events < aio_nr) { spin_unlock(&aio_nr_lock); goto out_cleanup; } aio_nr += ctx->max_reqs; spin_unlock(&aio_nr_lock); /* now link into global list. */ spin_lock(&mm->ioctx_lock); hlist_add_head_rcu(&ctx->list, &mm->ioctx_list); spin_unlock(&mm->ioctx_lock); pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", ctx, ctx->user_id, mm, ctx->nr_events); return ctx; out_cleanup: err = -EAGAIN; aio_free_ring(ctx); out_freectx: kmem_cache_free(kioctx_cachep, ctx); pr_debug("error allocating ioctx %d\n", err); return ERR_PTR(err); } static void kill_ioctx_work(struct work_struct *work) { struct kioctx *ctx = container_of(work, struct kioctx, rcu_work); wake_up_all(&ctx->wait); put_ioctx(ctx); } static void kill_ioctx_rcu(struct rcu_head *head) { struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); INIT_WORK(&ctx->rcu_work, kill_ioctx_work); schedule_work(&ctx->rcu_work); } /* 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 void kill_ioctx(struct kioctx *ctx) { if (!atomic_xchg(&ctx->dead, 1)) { hlist_del_rcu(&ctx->list); /* * 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). */ spin_lock(&aio_nr_lock); BUG_ON(aio_nr - ctx->max_reqs > aio_nr); aio_nr -= ctx->max_reqs; spin_unlock(&aio_nr_lock); if (ctx->mmap_size) vm_munmap(ctx->mmap_base, ctx->mmap_size); /* Between hlist_del_rcu() and dropping the initial ref */ call_rcu(&ctx->rcu_head, kill_ioctx_rcu); } } /* wait_on_sync_kiocb: * Waits on the given sync kiocb to complete. */ ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { while (atomic_read(&iocb->ki_users)) { set_current_state(TASK_UNINTERRUPTIBLE); if (!atomic_read(&iocb->ki_users)) break; io_schedule(); } __set_current_state(TASK_RUNNING); return iocb->ki_user_data; } EXPORT_SYMBOL(wait_on_sync_kiocb); /* * 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 *ctx; struct hlist_node *n; hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) { if (1 != atomic_read(&ctx->users)) printk(KERN_DEBUG "exit_aio:ioctx still alive: %d %d %d\n", atomic_read(&ctx->users), atomic_read(&ctx->dead), atomic_read(&ctx->reqs_active)); /* * We don't need to bother with munmap() here - * 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 * place that uses ->mmap_size, so it's safe. */ ctx->mmap_size = 0; 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; }