struct percpu_ref users;
atomic_t dead;
+ struct percpu_ref reqs;
+
unsigned long user_id;
struct __percpu kioctx_cpu *cpu;
struct page **ring_pages;
long nr_pages;
- struct rcu_head rcu_head;
struct work_struct free_work;
struct {
int i;
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]));
- put_page(ctx->ring_pages[i]);
+ page = ctx->ring_pages[i];
+ if (!page)
+ continue;
+ ctx->ring_pages[i] = NULL;
+ put_page(page);
}
put_aio_ring_file(ctx);
- if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
+ 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)
unsigned long flags;
int rc;
+ rc = 0;
+
+ /* Make sure the old page hasn't already been changed */
+ spin_lock(&mapping->private_lock);
+ ctx = mapping->private_data;
+ if (ctx) {
+ pgoff_t idx;
+ spin_lock_irqsave(&ctx->completion_lock, flags);
+ idx = old->index;
+ if (idx < (pgoff_t)ctx->nr_pages) {
+ if (ctx->ring_pages[idx] != old)
+ rc = -EAGAIN;
+ } else
+ rc = -EINVAL;
+ spin_unlock_irqrestore(&ctx->completion_lock, flags);
+ } else
+ rc = -EINVAL;
+ spin_unlock(&mapping->private_lock);
+
+ if (rc != 0)
+ return rc;
+
/* Writeback must be complete */
BUG_ON(PageWriteback(old));
- put_page(old);
+ get_page(new);
- rc = migrate_page_move_mapping(mapping, new, old, NULL, mode);
+ rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
if (rc != MIGRATEPAGE_SUCCESS) {
- get_page(old);
+ put_page(new);
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_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;
+ if (idx < (pgoff_t)ctx->nr_pages) {
+ /* And only do the move if things haven't changed */
+ if (ctx->ring_pages[idx] == old)
+ ctx->ring_pages[idx] = new;
+ else
+ rc = -EAGAIN;
+ } else
+ rc = -EINVAL;
spin_unlock_irqrestore(&ctx->completion_lock, flags);
} else
rc = -EBUSY;
spin_unlock(&mapping->private_lock);
+ if (rc == MIGRATEPAGE_SUCCESS)
+ put_page(old);
+ else
+ put_page(new);
+
return rc;
}
#endif
struct aio_ring *ring;
unsigned nr_events = ctx->max_reqs;
struct mm_struct *mm = current->mm;
- unsigned long size, populate;
+ unsigned long size, unused;
int nr_pages;
int i;
struct file *file;
return -EAGAIN;
}
+ 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,
SetPageUptodate(page);
SetPageDirty(page);
unlock_page(page);
+
+ ctx->ring_pages[i] = page;
}
- ctx->aio_ring_file = file;
- nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
- / sizeof(struct io_event);
+ ctx->nr_pages = i;
- 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;
+ if (unlikely(i != nr_pages)) {
+ aio_free_ring(ctx);
+ return -EAGAIN;
}
ctx->mmap_size = nr_pages * PAGE_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);
+ MAP_SHARED, 0, &unused);
+ up_write(&mm->mmap_sem);
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 */
return cancel(kiocb);
}
-static void free_ioctx_rcu(struct rcu_head *head)
+static void free_ioctx(struct work_struct *work)
{
- struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
+ 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(struct work_struct *work)
+static void free_ioctx_users(struct percpu_ref *ref)
{
- struct kioctx *ctx = container_of(work, struct kioctx, free_work);
- struct aio_ring *ring;
+ struct kioctx *ctx = container_of(ref, struct kioctx, users);
struct kiocb *req;
- unsigned cpu, avail;
- DEFINE_WAIT(wait);
spin_lock_irq(&ctx->ctx_lock);
spin_unlock_irq(&ctx->ctx_lock);
- 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 (1) {
- prepare_to_wait(&ctx->wait, &wait, TASK_UNINTERRUPTIBLE);
-
- ring = kmap_atomic(ctx->ring_pages[0]);
- avail = (ring->head <= ring->tail)
- ? ring->tail - ring->head
- : ctx->nr_events - ring->head + ring->tail;
-
- 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_available) > ctx->nr_events - 1);
-
- aio_free_ring(ctx);
-
- pr_debug("freeing %p\n", ctx);
-
- /*
- * Here the call_rcu() is between the wait_event() for reqs_active to
- * hit 0, and freeing the ioctx.
- *
- * aio_complete() decrements reqs_active, but it has to touch the ioctx
- * after to issue a wakeup so we use rcu.
- */
- call_rcu(&ctx->rcu_head, free_ioctx_rcu);
-}
-
-static void free_ioctx_ref(struct percpu_ref *ref)
-{
- struct kioctx *ctx = container_of(ref, struct kioctx, users);
-
- INIT_WORK(&ctx->free_work, free_ioctx);
- schedule_work(&ctx->free_work);
+ percpu_ref_kill(&ctx->reqs);
+ percpu_ref_put(&ctx->reqs);
}
static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
}
}
+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.
*/
ctx->max_reqs = nr_events;
- if (percpu_ref_init(&ctx->users, free_ioctx_ref))
- goto out_freectx;
+ 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);
ctx->cpu = alloc_percpu(struct kioctx_cpu);
if (!ctx->cpu)
- goto out_freeref;
+ goto err;
if (aio_setup_ring(ctx) < 0)
- goto out_freepcpu;
+ goto err;
atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
aio_nr + nr_events < aio_nr) {
spin_unlock(&aio_nr_lock);
- goto out_cleanup;
+ 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->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 out_cleanup_put;
+ 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;
-out_cleanup_put:
- percpu_ref_put(&ctx->users);
-out_cleanup:
- err = -EAGAIN;
+err_cleanup:
+ aio_nr_sub(ctx->max_reqs);
+err_ctx:
aio_free_ring(ctx);
-out_freepcpu:
+err:
free_percpu(ctx->cpu);
-out_freeref:
+ free_percpu(ctx->reqs.pcpu_count);
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);
* -EAGAIN with no ioctxs actually in use (as far as userspace
* could tell).
*/
- spin_lock(&aio_nr_lock);
- BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
- aio_nr -= ctx->max_reqs;
- spin_unlock(&aio_nr_lock);
+ aio_nr_sub(ctx->max_reqs);
if (ctx->mmap_size)
vm_munmap(ctx->mmap_base, ctx->mmap_size);
if (unlikely(!req))
goto out_put;
+ percpu_ref_get(&ctx->reqs);
+
req->ki_ctx = ctx;
return req;
out_put:
return;
}
- /*
- * Take rcu_read_lock() in case the kioctx is being destroyed, as we
- * need to issue a wakeup after incrementing reqs_available.
- */
- rcu_read_lock();
-
if (iocb->ki_list.next) {
unsigned long flags;
if (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
- rcu_read_unlock();
+ percpu_ref_put(&ctx->reqs);
}
EXPORT_SYMBOL(aio_complete);
return 0;
out_put_req:
put_reqs_available(ctx, 1);
+ percpu_ref_put(&ctx->reqs);
kiocb_free(req);
return ret;
}
projects / ~andy / linux / blobdiff