| /* |
| * 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 <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; /* 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 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 completion *requests_done; |
| |
| 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; |
| } |
| |
| 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, |
| }; |
| return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC); |
| } |
| |
| /* 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; |
| } |
| __initcall(aio_setup); |
| |
| static void put_aio_ring_file(struct kioctx *ctx) |
| { |
| struct file *aio_ring_file = ctx->aio_ring_file; |
| if (aio_ring_file) { |
| truncate_setsize(aio_ring_file->f_inode, 0); |
| |
| /* Prevent further access to the kioctx from migratepages */ |
| spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock); |
| aio_ring_file->f_inode->i_mapping->private_data = NULL; |
| ctx->aio_ring_file = NULL; |
| spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock); |
| |
| fput(aio_ring_file); |
| } |
| } |
| |
| 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; |
| } |
| } |
| |
| static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma) |
| { |
| vma->vm_flags |= VM_DONTEXPAND; |
| vma->vm_ops = &generic_file_vm_ops; |
| return 0; |
| } |
| |
| static void aio_ring_remap(struct file *file, struct vm_area_struct *vma) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct kioctx_table *table; |
| int i; |
| |
| 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) { |
| ctx->user_id = ctx->mmap_base = vma->vm_start; |
| break; |
| } |
| } |
| |
| rcu_read_unlock(); |
| spin_unlock(&mm->ioctx_lock); |
| } |
| |
| static const struct file_operations aio_ring_fops = { |
| .mmap = aio_ring_mmap, |
| .mremap = aio_ring_remap, |
| }; |
| |
| #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; |
| } |
| #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_inode->i_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); |
| |
| down_write(&mm->mmap_sem); |
| 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; |
| } |
| |
| #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); |
| } |
| 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); |
| } |
| |
| 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); |
| } |
| |
| 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->requests_done) |
| complete(ctx->requests_done); |
| |
| INIT_WORK(&ctx->free_work, free_ioctx); |
| schedule_work(&ctx->free_work); |
| } |
| |
| /* |
| * 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); |
| } |
| |
| 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; |
| } |
| } |
| } |
| |
| 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); |
| } |
| |
| /* 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))) || |
| (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 * 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: |
| 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); |
| } |
| |
| /* 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 completion *requests_done) |
| { |
| struct kioctx_table *table; |
| |
| if (atomic_xchg(&ctx->dead, 1)) |
| return -EINVAL; |
| |
| |
| spin_lock(&mm->ioctx_lock); |
| 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->requests_done = requests_done; |
| percpu_ref_kill(&ctx->users); |
| return 0; |
| } |
| |
| /* |
| * 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); |
| int i; |
| |
| if (!table) |
| return; |
| |
| for (i = 0; i < table->nr; ++i) { |
| struct kioctx *ctx = table->table[i]; |
| struct completion requests_done = |
| COMPLETION_INITIALIZER_ONSTACK(requests_done); |
| |
| if (!ctx) |
| 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, &requests_done); |
| |
| /* Wait until all IO for the context are done. */ |
| wait_for_completion(&requests_done); |
| } |
| |
| RCU_INIT_POINTER(mm->ioctx_table, NULL); |
| kfree(table); |
| } |
| |
| 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); |
| } |
| |
| 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; |
| } |
| |
| /* 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); |
| } |
| |
| /* 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); |
| } |
| |
| /* 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; |
| } |
| |
| 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); |
| } |
| |
| 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; |
| } |
| |
| /* 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; |
| |
| /* |
| * 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); |
| } |
| |
| /* 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; |
| } |
| |
| 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. |
| */ |
| if (until.tv64 == 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; |
| } |
| |
| /* 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; |
| } |
| |
| /* 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 completion requests_done = |
| COMPLETION_INITIALIZER_ONSTACK(requests_done); |
| int ret; |
| |
| /* 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, &requests_done); |
| 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(&requests_done); |
| |
| return ret; |
| } |
| pr_debug("EINVAL: invalid context id\n"); |
| return -EINVAL; |
| } |
| |
| typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *, |
| unsigned long, loff_t); |
| typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *); |
| |
| static int aio_setup_vectored_rw(int rw, char __user *buf, size_t len, |
| struct iovec **iovec, |
| bool compat, |
| struct iov_iter *iter) |
| { |
| #ifdef CONFIG_COMPAT |
| if (compat) |
| return compat_import_iovec(rw, |
| (struct compat_iovec __user *)buf, |
| len, UIO_FASTIOV, iovec, iter); |
| #endif |
| return import_iovec(rw, (struct iovec __user *)buf, |
| len, UIO_FASTIOV, iovec, iter); |
| } |
| |
| /* |
| * aio_run_iocb: |
| * Performs the initial checks and io submission. |
| */ |
| static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode, |
| char __user *buf, size_t len, bool compat) |
| { |
| struct file *file = req->ki_filp; |
| ssize_t ret; |
| int rw; |
| fmode_t mode; |
| aio_rw_op *rw_op; |
| rw_iter_op *iter_op; |
| struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; |
| struct iov_iter iter; |
| |
| switch (opcode) { |
| case IOCB_CMD_PREAD: |
| case IOCB_CMD_PREADV: |
| mode = FMODE_READ; |
| rw = READ; |
| rw_op = file->f_op->aio_read; |
| iter_op = file->f_op->read_iter; |
| goto rw_common; |
| |
| case IOCB_CMD_PWRITE: |
| case IOCB_CMD_PWRITEV: |
| mode = FMODE_WRITE; |
| rw = WRITE; |
| rw_op = file->f_op->aio_write; |
| iter_op = file->f_op->write_iter; |
| goto rw_common; |
| rw_common: |
| if (unlikely(!(file->f_mode & mode))) |
| return -EBADF; |
| |
| if (!rw_op && !iter_op) |
| return -EINVAL; |
| |
| if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV) |
| ret = aio_setup_vectored_rw(rw, buf, len, |
| &iovec, compat, &iter); |
| else { |
| ret = import_single_range(rw, buf, len, iovec, &iter); |
| iovec = NULL; |
| } |
| if (!ret) |
| ret = rw_verify_area(rw, file, &req->ki_pos, |
| iov_iter_count(&iter)); |
| if (ret < 0) { |
| kfree(iovec); |
| return ret; |
| } |
| |
| len = ret; |
| |
| /* XXX: move/kill - rw_verify_area()? */ |
| /* This matches the pread()/pwrite() logic */ |
| if (req->ki_pos < 0) { |
| ret = -EINVAL; |
| break; |
| } |
| |
| if (rw == WRITE) |
| file_start_write(file); |
| |
| if (iter_op) { |
| ret = iter_op(req, &iter); |
| } else { |
| ret = rw_op(req, iter.iov, iter.nr_segs, req->ki_pos); |
| } |
| |
| if (rw == WRITE) |
| file_end_write(file); |
| kfree(iovec); |
| 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 aio_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: overflow check\n"); |
| return -EINVAL; |
| } |
| |
| req = aio_get_req(ctx); |
| if (unlikely(!req)) |
| return -EAGAIN; |
| |
| req->common.ki_filp = 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 = 0; |
| |
| 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; |
| |
| ret = aio_run_iocb(&req->common, iocb->aio_lio_opcode, |
| (char __user *)(unsigned long)iocb->aio_buf, |
| iocb->aio_nbytes, |
| compat); |
| if (ret) |
| goto out_put_req; |
| |
| return 0; |
| out_put_req: |
| put_reqs_available(ctx, 1); |
| percpu_ref_put(&ctx->reqs); |
| kiocb_free(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); |
| |
| percpu_ref_put(&ctx->users); |
| 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 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; |
| } |
| |
| /* 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; |
| } |