diff options
Diffstat (limited to 'fs/aio.c')
| -rw-r--r-- | fs/aio.c | 748 |
1 files changed, 488 insertions, 260 deletions
@@ -26,6 +26,7 @@ #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> @@ -35,6 +36,10 @@ #include <linux/eventfd.h> #include <linux/blkdev.h> #include <linux/compat.h> +#include <linux/anon_inodes.h> +#include <linux/migrate.h> +#include <linux/ramfs.h> +#include <linux/percpu-refcount.h> #include <asm/kmap_types.h> #include <asm/uaccess.h> @@ -61,14 +66,29 @@ struct aio_ring { #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 { - atomic_t users; + struct percpu_ref users; atomic_t dead; - /* This needs improving */ unsigned long user_id; - struct hlist_node list; + 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. @@ -88,10 +108,18 @@ struct kioctx { long nr_pages; struct rcu_head rcu_head; - struct work_struct rcu_work; + struct work_struct free_work; struct { - atomic_t reqs_active; + /* + * 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 { @@ -110,6 +138,9 @@ struct kioctx { } ____cacheline_aligned_in_smp; struct page *internal_pages[AIO_RING_PAGES]; + struct file *aio_ring_file; + + unsigned id; }; /*------ sysctl variables----*/ @@ -136,17 +167,102 @@ static int __init aio_setup(void) } __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) { - long i; + int i; - for (i = 0; i < ctx->nr_pages; 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); } +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; @@ -154,20 +270,45 @@ static int aio_setup_ring(struct kioctx *ctx) 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 = (size + PAGE_SIZE-1) >> PAGE_SHIFT; + nr_pages = PFN_UP(size); if (nr_pages < 0) return -EINVAL; - nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); + file = anon_inode_getfile_private("[aio]", &aio_ring_fops, ctx, O_RDWR); + if (IS_ERR(file)) { + ctx->aio_ring_file = NULL; + return -EAGAIN; + } + + file->f_inode->i_mapping->a_ops = &aio_ctx_aops; + file->f_inode->i_mapping->private_data = ctx; + file->f_inode->i_size = PAGE_SIZE * (loff_t)nr_pages; + + 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->nr_events = 0; ctx->ring_pages = ctx->internal_pages; if (nr_pages > AIO_RING_PAGES) { ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *), @@ -178,10 +319,11 @@ static int aio_setup_ring(struct kioctx *ctx) 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); + 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; @@ -190,23 +332,34 @@ static int aio_setup_ring(struct kioctx *ctx) } 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; } - 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->id = ~0U; ring->head = ring->tail = 0; ring->magic = AIO_RING_MAGIC; ring->compat_features = AIO_RING_COMPAT_FEATURES; @@ -238,11 +391,9 @@ void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel) } EXPORT_SYMBOL(kiocb_set_cancel_fn); -static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb, - struct io_event *res) +static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb) { kiocb_cancel_fn *old, *cancel; - int ret = -EINVAL; /* * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it @@ -252,28 +403,20 @@ static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb, cancel = ACCESS_ONCE(kiocb->ki_cancel); do { if (!cancel || cancel == KIOCB_CANCELLED) - return ret; + return -EINVAL; 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; + return cancel(kiocb); } static void free_ioctx_rcu(struct rcu_head *head) { struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); + + free_percpu(ctx->cpu); kmem_cache_free(kioctx_cachep, ctx); } @@ -282,12 +425,13 @@ static void free_ioctx_rcu(struct rcu_head *head) * 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) +static void free_ioctx(struct work_struct *work) { + struct kioctx *ctx = container_of(work, struct kioctx, free_work); struct aio_ring *ring; - struct io_event res; struct kiocb *req; - unsigned head, avail; + unsigned cpu, avail; + DEFINE_WAIT(wait); spin_lock_irq(&ctx->ctx_lock); @@ -296,28 +440,38 @@ static void free_ioctx(struct kioctx *ctx) struct kiocb, ki_list); list_del_init(&req->ki_list); - kiocb_cancel(ctx, req, &res); + kiocb_cancel(ctx, req); } spin_unlock_irq(&ctx->ctx_lock); - ring = kmap_atomic(ctx->ring_pages[0]); - head = ring->head; - kunmap_atomic(ring); + for_each_possible_cpu(cpu) { + struct kioctx_cpu *kcpu = per_cpu_ptr(ctx->cpu, cpu); + + atomic_add(kcpu->reqs_available, &ctx->reqs_available); + kcpu->reqs_available = 0; + } - while (atomic_read(&ctx->reqs_active) > 0) { - wait_event(ctx->wait, - head != ctx->tail || - atomic_read(&ctx->reqs_active) <= 0); + while (1) { + prepare_to_wait(&ctx->wait, &wait, TASK_UNINTERRUPTIBLE); - avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; + ring = kmap_atomic(ctx->ring_pages[0]); + avail = (ring->head <= ring->tail) + ? ring->tail - ring->head + : ctx->nr_events - ring->head + ring->tail; - atomic_sub(avail, &ctx->reqs_active); - head += avail; - head %= ctx->nr_events; + atomic_add(avail, &ctx->reqs_available); + ring->head = ring->tail; + kunmap_atomic(ring); + + if (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1) + break; + + schedule(); } + finish_wait(&ctx->wait, &wait); - WARN_ON(atomic_read(&ctx->reqs_active) < 0); + WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr_events - 1); aio_free_ring(ctx); @@ -333,10 +487,68 @@ static void free_ioctx(struct kioctx *ctx) call_rcu(&ctx->rcu_head, free_ioctx_rcu); } -static void put_ioctx(struct kioctx *ctx) +static void free_ioctx_ref(struct percpu_ref *ref) { - if (unlikely(atomic_dec_and_test(&ctx->users))) - free_ioctx(ctx); + struct kioctx *ctx = container_of(ref, struct kioctx, users); + + INIT_WORK(&ctx->free_work, free_ioctx); + schedule_work(&ctx->free_work); +} + +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; + } + } } /* ioctx_alloc @@ -348,6 +560,18 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 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)))) { @@ -355,7 +579,7 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) return ERR_PTR(-EINVAL); } - if (!nr_events || (unsigned long)nr_events > aio_max_nr) + if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL)) return ERR_PTR(-EAGAIN); ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); @@ -364,8 +588,9 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) ctx->max_reqs = nr_events; - atomic_set(&ctx->users, 2); - atomic_set(&ctx->dead, 0); + if (percpu_ref_init(&ctx->users, free_ioctx_ref)) + goto out_freectx; + spin_lock_init(&ctx->ctx_lock); spin_lock_init(&ctx->completion_lock); mutex_init(&ctx->ring_lock); @@ -373,12 +598,21 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) INIT_LIST_HEAD(&ctx->active_reqs); + ctx->cpu = alloc_percpu(struct kioctx_cpu); + if (!ctx->cpu) + goto out_freeref; + if (aio_setup_ring(ctx) < 0) - goto out_freectx; + goto out_freepcpu; + + 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 || + if (aio_nr + nr_events > (aio_max_nr * 2UL) || aio_nr + nr_events < aio_nr) { spin_unlock(&aio_nr_lock); goto out_cleanup; @@ -386,49 +620,53 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 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); + percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */ + + err = ioctx_add_table(ctx, mm); + if (err) + goto out_cleanup_put; pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", ctx, ctx->user_id, mm, ctx->nr_events); return ctx; +out_cleanup_put: + percpu_ref_put(&ctx->users); out_cleanup: err = -EAGAIN; aio_free_ring(ctx); +out_freepcpu: + free_percpu(ctx->cpu); +out_freeref: + free_percpu(ctx->users.pcpu_count); out_freectx: + put_aio_ring_file(ctx); 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) +static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx) { if (!atomic_xchg(&ctx->dead, 1)) { - hlist_del_rcu(&ctx->list); + 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 @@ -445,24 +683,23 @@ static void kill_ioctx(struct kioctx *ctx) 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); + 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 *iocb) +ssize_t wait_on_sync_kiocb(struct kiocb *req) { - while (atomic_read(&iocb->ki_users)) { + while (!req->ki_ctx) { set_current_state(TASK_UNINTERRUPTIBLE); - if (!atomic_read(&iocb->ki_users)) + if (req->ki_ctx) break; io_schedule(); } __set_current_state(TASK_RUNNING); - return iocb->ki_user_data; + return req->ki_user_data; } EXPORT_SYMBOL(wait_on_sync_kiocb); @@ -476,16 +713,28 @@ EXPORT_SYMBOL(wait_on_sync_kiocb); */ void exit_aio(struct mm_struct *mm) { + struct kioctx_table *table; 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)); + 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. @@ -496,40 +745,75 @@ void exit_aio(struct mm_struct *mm) */ ctx->mmap_size = 0; - kill_ioctx(ctx); + 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. 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. + * 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 (atomic_read(&ctx->reqs_active) >= ctx->nr_events) + if (!get_reqs_available(ctx)) 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); + put_reqs_available(ctx, 1); return NULL; } @@ -539,35 +823,32 @@ static void kiocb_free(struct kiocb *req) 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 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); - hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) { - if (ctx->user_id == ctx_id) { - atomic_inc(&ctx->users); - ret = ctx; - break; - } - } + 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; } @@ -591,16 +872,16 @@ void aio_complete(struct kiocb *iocb, long res, long res2) * - 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); + smp_wmb(); + iocb->ki_ctx = ERR_PTR(-EXDEV); 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. + * need to issue a wakeup after incrementing reqs_available. */ rcu_read_lock(); @@ -613,17 +894,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2) } /* - * 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. @@ -675,9 +945,8 @@ void aio_complete(struct kiocb *iocb, long res, long res2) 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); + kiocb_free(iocb); /* * We have to order our ring_info tail store above and test @@ -702,7 +971,7 @@ static long aio_read_events_ring(struct kioctx *ctx, struct io_event __user *event, long nr) { struct aio_ring *ring; - unsigned head, pos; + unsigned head, tail, pos; long ret = 0; int copy_ret; @@ -710,11 +979,12 @@ static long aio_read_events_ring(struct kioctx *ctx, 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, ctx->tail, ctx->nr_events); + pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events); - if (head == ctx->tail) + if (head == tail) goto out; while (ret < nr) { @@ -722,8 +992,8 @@ static long aio_read_events_ring(struct kioctx *ctx, struct io_event *ev; struct page *page; - avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; - if (head == ctx->tail) + avail = (head <= tail ? tail : ctx->nr_events) - head; + if (head == tail) break; avail = min(avail, nr - ret); @@ -754,9 +1024,9 @@ static long aio_read_events_ring(struct kioctx *ctx, kunmap_atomic(ring); flush_dcache_page(ctx->ring_pages[0]); - pr_debug("%li h%u t%u\n", ret, head, ctx->tail); + pr_debug("%li h%u t%u\n", ret, head, tail); - atomic_sub(ret, &ctx->reqs_active); + put_reqs_available(ctx, ret); out: mutex_unlock(&ctx->ring_lock); @@ -854,8 +1124,8 @@ SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp) if (!IS_ERR(ioctx)) { ret = put_user(ioctx->user_id, ctxp); if (ret) - kill_ioctx(ioctx); - put_ioctx(ioctx); + kill_ioctx(current->mm, ioctx); + percpu_ref_put(&ioctx->users); } out: @@ -872,101 +1142,37 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx) { struct kioctx *ioctx = lookup_ioctx(ctx); if (likely(NULL != ioctx)) { - kill_ioctx(ioctx); - put_ioctx(ioctx); + kill_ioctx(current->mm, ioctx); + percpu_ref_put(&ioctx->users); 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) +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; - kiocb->ki_nr_segs = kiocb->ki_nbytes; + *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); + (struct compat_iovec __user *)buf, + *nr_segs, 1, *iovec, 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); + (struct iovec __user *)buf, + *nr_segs, 1, *iovec, iovec); if (ret < 0) return ret; @@ -975,15 +1181,17 @@ static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat) return 0; } -static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb) +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, kiocb->ki_buf, kiocb->ki_nbytes))) + if (unlikely(!access_ok(!rw, 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; + iovec->iov_base = buf; + iovec->iov_len = kiocb->ki_nbytes; + *nr_segs = 1; return 0; } @@ -992,15 +1200,18 @@ static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb) * 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) +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 (req->ki_opcode) { + switch (opcode) { case IOCB_CMD_PREAD: case IOCB_CMD_PREADV: mode = FMODE_READ; @@ -1021,21 +1232,38 @@ rw_common: 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); + 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 (ret < 0) { + if (iovec != &inline_vec) + kfree(iovec); return ret; + } req->ki_nbytes = ret; - req->ki_left = ret; - ret = aio_rw_vect_retry(req, rw, rw_op); + /* 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: @@ -1057,6 +1285,9 @@ rw_common: return -EINVAL; } + if (iovec != &inline_vec) + kfree(iovec); + if (ret != -EIOCBQUEUED) { /* * There's no easy way to restart the syscall since other AIO's @@ -1128,21 +1359,18 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 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; - 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); + ret = aio_run_iocb(req, iocb->aio_lio_opcode, + (char __user *)(unsigned long)iocb->aio_buf, + 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 */ + put_reqs_available(ctx, 1); + kiocb_free(req); return ret; } @@ -1195,7 +1423,7 @@ long do_io_submit(aio_context_t ctx_id, long nr, } blk_finish_plug(&plug); - put_ioctx(ctx); + percpu_ref_put(&ctx->users); return i ? i : ret; } @@ -1252,7 +1480,6 @@ static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 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; @@ -1270,21 +1497,22 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, kiocb = lookup_kiocb(ctx, iocb, key); if (kiocb) - ret = kiocb_cancel(ctx, kiocb, &res); + ret = kiocb_cancel(ctx, kiocb); else ret = -EINVAL; spin_unlock_irq(&ctx->ctx_lock); if (!ret) { - /* Cancellation succeeded -- copy the result - * into the user's buffer. + /* + * The result argument is no longer used - the io_event is + * always delivered via the ring buffer. -EINPROGRESS indicates + * cancellation is progress: */ - if (copy_to_user(result, &res, sizeof(res))) - ret = -EFAULT; + ret = -EINPROGRESS; } - put_ioctx(ctx); + percpu_ref_put(&ctx->users); return ret; } @@ -1313,7 +1541,7 @@ SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id, if (likely(ioctx)) { if (likely(min_nr <= nr && min_nr >= 0)) ret = read_events(ioctx, min_nr, nr, events, timeout); - put_ioctx(ioctx); + percpu_ref_put(&ioctx->users); } return ret; } |