diff options
| -rw-r--r-- | fs/aio.c | 129 |
1 files changed, 48 insertions, 81 deletions
@@ -80,6 +80,8 @@ struct kioctx { struct percpu_ref users; atomic_t dead; + struct percpu_ref reqs; + unsigned long user_id; struct __percpu kioctx_cpu *cpu; @@ -107,7 +109,6 @@ struct kioctx { struct page **ring_pages; long nr_pages; - struct rcu_head rcu_head; struct work_struct free_work; struct { @@ -412,26 +413,34 @@ static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb) 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); @@ -445,54 +454,8 @@ static void free_ioctx(struct work_struct *work) 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) @@ -551,6 +514,16 @@ 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. */ @@ -588,8 +561,11 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 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); @@ -600,10 +576,10 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 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); @@ -615,7 +591,8 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 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; } aio_nr += ctx->max_reqs; spin_unlock(&aio_nr_lock); @@ -624,23 +601,19 @@ static struct kioctx *ioctx_alloc(unsigned nr_events) 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: aio_free_ring(ctx); -out_freepcpu: 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); @@ -675,10 +648,7 @@ static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx) * -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); @@ -810,6 +780,8 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx) if (unlikely(!req)) goto out_put; + percpu_ref_get(&ctx->reqs); + req->ki_ctx = ctx; return req; out_put: @@ -879,12 +851,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2) 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; @@ -959,7 +925,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2) if (waitqueue_active(&ctx->wait)) wake_up(&ctx->wait); - rcu_read_unlock(); + percpu_ref_put(&ctx->reqs); } EXPORT_SYMBOL(aio_complete); @@ -1370,6 +1336,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, return 0; out_put_req: put_reqs_available(ctx, 1); + percpu_ref_put(&ctx->reqs); kiocb_free(req); return ret; } |