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- /*
- * An async IO implementation for Linux
- * Written by Benjamin LaHaise <bcrl@kvack.org>
- *
- * Implements an efficient asynchronous io interface.
- *
- * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
- *
- * See ../COPYING for licensing terms.
- */
- #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;
- 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;
- 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;
- spinlock_t completion_lock;
- } ____cacheline_aligned_in_smp;
- struct page *internal_pages[AIO_RING_PAGES];
- struct file *aio_ring_file;
- unsigned id;
- };
- /*------ 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;
- file->private_data = ctx;
- 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, 0xa10a10a1);
- }
- /* 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(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;
- for (i = 0; i < ctx->nr_pages; i++) {
- pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
- page_count(ctx->ring_pages[i]));
- put_page(ctx->ring_pages[i]);
- }
- put_aio_ring_file(ctx);
- 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_ops = &generic_file_vm_ops;
- return 0;
- }
- static const struct file_operations aio_ring_fops = {
- .mmap = aio_ring_mmap,
- };
- static int aio_set_page_dirty(struct page *page)
- {
- return 0;
- }
- #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;
- int rc;
- /* Writeback must be complete */
- BUG_ON(PageWriteback(old));
- put_page(old);
- rc = migrate_page_move_mapping(mapping, new, old, NULL, mode);
- if (rc != MIGRATEPAGE_SUCCESS) {
- get_page(old);
- return rc;
- }
- get_page(new);
- /* We can potentially race against kioctx teardown here. Use the
- * address_space's private data lock to protect the mapping's
- * private_data.
- */
- spin_lock(&mapping->private_lock);
- ctx = mapping->private_data;
- if (ctx) {
- pgoff_t idx;
- spin_lock_irqsave(&ctx->completion_lock, flags);
- migrate_page_copy(new, old);
- idx = old->index;
- if (idx < (pgoff_t)ctx->nr_pages)
- ctx->ring_pages[idx] = new;
- spin_unlock_irqrestore(&ctx->completion_lock, flags);
- } else
- rc = -EBUSY;
- spin_unlock(&mapping->private_lock);
- return rc;
- }
- #endif
- static const struct address_space_operations aio_ctx_aops = {
- .set_page_dirty = aio_set_page_dirty,
- #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, populate;
- 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 -EAGAIN;
- }
- 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);
- SetPageDirty(page);
- unlock_page(page);
- }
- 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)
- 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 | MAP_POPULATE, 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);
- /* We must do this while still holding mmap_sem for write, as we
- * need to be protected against userspace attempting to mremap()
- * or munmap() the ring buffer.
- */
- ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
- 1, 0, ctx->ring_pages, NULL);
- /* Dropping the reference here is safe as the page cache will hold
- * onto the pages for us. It is also required so that page migration
- * can unmap the pages and get the right reference count.
- */
- for (i = 0; i < ctx->nr_pages; i++)
- put_page(ctx->ring_pages[i]);
- up_write(&mm->mmap_sem);
- if (unlikely(ctx->nr_pages != nr_pages)) {
- aio_free_ring(ctx);
- return -EAGAIN;
- }
- 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 *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)
- {
- 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);
- }
- 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);
- kmem_cache_free(kioctx_cachep, ctx);
- }
- static void free_ioctx_reqs(struct percpu_ref *ref)
- {
- struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
- 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 kiocb *req;
- 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);
- }
- 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);
- rcu_read_lock();
- table = rcu_dereference(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;
- rcu_read_unlock();
- spin_unlock(&mm->ioctx_lock);
- ring = kmap_atomic(ctx->ring_pages[0]);
- ring->id = ctx->id;
- kunmap_atomic(ring);
- return 0;
- }
- new_nr = (table ? table->nr : 1) * 4;
- rcu_read_unlock();
- 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);
- rcu_read_lock();
- old = rcu_dereference(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;
- if (percpu_ref_init(&ctx->users, free_ioctx_users))
- goto err;
- if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs))
- goto err;
- 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);
- ctx->cpu = alloc_percpu(struct kioctx_cpu);
- if (!ctx->cpu)
- goto err;
- if (aio_setup_ring(ctx) < 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;
- }
- aio_nr += ctx->max_reqs;
- spin_unlock(&aio_nr_lock);
- percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
- err = ioctx_add_table(ctx, mm);
- if (err)
- goto err_cleanup;
- 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:
- free_percpu(ctx->cpu);
- free_percpu(ctx->reqs.pcpu_count);
- free_percpu(ctx->users.pcpu_count);
- 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 void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx)
- {
- if (!atomic_xchg(&ctx->dead, 1)) {
- struct kioctx_table *table;
- spin_lock(&mm->ioctx_lock);
- rcu_read_lock();
- table = rcu_dereference(mm->ioctx_table);
- WARN_ON(ctx != table->table[ctx->id]);
- table->table[ctx->id] = NULL;
- rcu_read_unlock();
- 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);
- percpu_ref_kill(&ctx->users);
- }
- }
- /* wait_on_sync_kiocb:
- * Waits on the given sync kiocb to complete.
- */
- ssize_t wait_on_sync_kiocb(struct kiocb *req)
- {
- while (!req->ki_ctx) {
- set_current_state(TASK_UNINTERRUPTIBLE);
- if (req->ki_ctx)
- break;
- io_schedule();
- }
- __set_current_state(TASK_RUNNING);
- return req->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_table *table;
- struct kioctx *ctx;
- unsigned i = 0;
- while (1) {
- rcu_read_lock();
- table = rcu_dereference(mm->ioctx_table);
- do {
- if (!table || i >= table->nr) {
- rcu_read_unlock();
- rcu_assign_pointer(mm->ioctx_table, NULL);
- if (table)
- kfree(table);
- return;
- }
- ctx = table->table[i++];
- } while (!ctx);
- rcu_read_unlock();
- /*
- * 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(mm, ctx);
- }
- }
- static void put_reqs_available(struct kioctx *ctx, unsigned nr)
- {
- struct kioctx_cpu *kcpu;
- preempt_disable();
- 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);
- }
- preempt_enable();
- }
- static bool get_reqs_available(struct kioctx *ctx)
- {
- struct kioctx_cpu *kcpu;
- bool ret = false;
- preempt_disable();
- 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:
- preempt_enable();
- return ret;
- }
- /* aio_get_req
- * Allocate a slot for an aio request.
- * Returns NULL if no requests are free.
- */
- static inline struct kiocb *aio_get_req(struct kioctx *ctx)
- {
- struct kiocb *req;
- 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 kiocb *req)
- {
- if (req->ki_filp)
- fput(req->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.
- */
- 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)) {
- iocb->ki_user_data = res;
- smp_wmb();
- iocb->ki_ctx = ERR_PTR(-EXDEV);
- wake_up_process(iocb->ki_obj.tsk);
- return;
- }
- 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_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);
- /* 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);
- }
- 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, tail, pos;
- long ret = 0;
- int copy_ret;
- mutex_lock(&ctx->ring_lock);
- ring = kmap_atomic(ctx->ring_pages[0]);
- head = ring->head;
- tail = ring->tail;
- kunmap_atomic(ring);
- pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
- if (head == tail)
- goto out;
- 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);
- put_reqs_available(ctx, ret);
- 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(current->mm, ioctx);
- 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)) {
- kill_ioctx(current->mm, ioctx);
- percpu_ref_put(&ioctx->users);
- return 0;
- }
- pr_debug("EINVAL: io_destroy: invalid context id\n");
- return -EINVAL;
- }
- typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
- unsigned long, loff_t);
- static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
- int rw, char __user *buf,
- unsigned long *nr_segs,
- struct iovec **iovec,
- bool compat)
- {
- ssize_t ret;
- *nr_segs = kiocb->ki_nbytes;
- #ifdef CONFIG_COMPAT
- if (compat)
- ret = compat_rw_copy_check_uvector(rw,
- (struct compat_iovec __user *)buf,
- *nr_segs, 1, *iovec, iovec);
- else
- #endif
- ret = rw_copy_check_uvector(rw,
- (struct iovec __user *)buf,
- *nr_segs, 1, *iovec, 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(struct kiocb *kiocb,
- int rw, char __user *buf,
- unsigned long *nr_segs,
- struct iovec *iovec)
- {
- if (unlikely(!access_ok(!rw, buf, kiocb->ki_nbytes)))
- return -EFAULT;
- iovec->iov_base = buf;
- iovec->iov_len = kiocb->ki_nbytes;
- *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, unsigned opcode,
- char __user *buf, bool compat)
- {
- struct file *file = req->ki_filp;
- ssize_t ret;
- unsigned long nr_segs;
- int rw;
- fmode_t mode;
- aio_rw_op *rw_op;
- struct iovec inline_vec, *iovec = &inline_vec;
- switch (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 = (opcode == IOCB_CMD_PREADV ||
- opcode == IOCB_CMD_PWRITEV)
- ? aio_setup_vectored_rw(req, rw, buf, &nr_segs,
- &iovec, compat)
- : aio_setup_single_vector(req, rw, buf, &nr_segs,
- iovec);
- if (ret)
- return ret;
- ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
- if (ret < 0) {
- if (iovec != &inline_vec)
- kfree(iovec);
- return ret;
- }
- req->ki_nbytes = 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);
- ret = rw_op(req, iovec, nr_segs, req->ki_pos);
- if (rw == WRITE)
- file_end_write(file);
- 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 (iovec != &inline_vec)
- kfree(iovec);
- 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_nbytes = iocb->aio_nbytes;
- ret = aio_run_iocb(req, iocb->aio_lio_opcode,
- (char __user *)(unsigned long)iocb->aio_buf,
- 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 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 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);
- 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;
- }
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