for-linus-20190420

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Merge tag 'for-linus-20190420' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "A set of small fixes that should go into this series. This contains:

   - Removal of unused queue member (Hou)

   - Overflow bvec fix (Ming)

   - Various little io_uring tweaks (me)
       - kthread parking
       - Only call cpu_possible() for verified CPU
       - Drop unused 'file' argument to io_file_put()
       - io_uring_enter vs io_uring_register deadlock fix
       - CQ overflow fix

   - BFQ internal depth update fix (me)"

* tag 'for-linus-20190420' of git://git.kernel.dk/linux-block:
  block: make sure that bvec length can't be overflow
  block: kill all_q_node in request_queue
  io_uring: fix CQ overflow condition
  io_uring: fix possible deadlock between io_uring_{enter,register}
  io_uring: drop io_file_put() 'file' argument
  bfq: update internal depth state when queue depth changes
  io_uring: only test SQPOLL cpu after we've verified it
  io_uring: park SQPOLL thread if it's percpu

block/bfq-iosched.c

@@ -5396,7 +5396,7 @@ static unsigned int bfq_update_depths(struct bfq_data *bfqd,
 	return min_shallow;
 }
 
-static int bfq_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int index)
+static void bfq_depth_updated(struct blk_mq_hw_ctx *hctx)
 {
 	struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
 	struct blk_mq_tags *tags = hctx->sched_tags;
@@ -5404,6 +5404,11 @@ static int bfq_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int index)
 
 	min_shallow = bfq_update_depths(bfqd, &tags->bitmap_tags);
 	sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, min_shallow);
+}
+
+static int bfq_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int index)
+{
+	bfq_depth_updated(hctx);
 	return 0;
 }
 
@@ -5826,6 +5831,7 @@ static struct elevator_type iosched_bfq_mq = {
 		.requests_merged	= bfq_requests_merged,
 		.request_merged		= bfq_request_merged,
 		.has_work		= bfq_has_work,
+		.depth_updated		= bfq_depth_updated,
 		.init_hctx		= bfq_init_hctx,
 		.init_sched		= bfq_init_queue,
 		.exit_sched		= bfq_exit_queue,

block/blk-mq.c

@@ -3135,6 +3135,8 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 		}
 		if (ret)
 			break;
+		if (q->elevator && q->elevator->type->ops.depth_updated)
+			q->elevator->type->ops.depth_updated(hctx);
 	}
 
 	if (!ret)

fs/io_uring.c

@@ -338,7 +338,7 @@ static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
 	tail = ctx->cached_cq_tail;
 	/* See comment at the top of the file */
 	smp_rmb();
-	if (tail + 1 == READ_ONCE(ring->r.head))
+	if (tail - READ_ONCE(ring->r.head) == ring->ring_entries)
 		return NULL;
 
 	ctx->cached_cq_tail++;
@@ -682,11 +682,9 @@ static void io_iopoll_req_issued(struct io_kiocb *req)
 		list_add_tail(&req->list, &ctx->poll_list);
 }
 
-static void io_file_put(struct io_submit_state *state, struct file *file)
+static void io_file_put(struct io_submit_state *state)
 {
-	if (!state) {
-		fput(file);
-	} else if (state->file) {
+	if (state->file) {
 		int diff = state->has_refs - state->used_refs;
 
 		if (diff)
@@ -711,7 +709,7 @@ static struct file *io_file_get(struct io_submit_state *state, int fd)
 			state->ios_left--;
 			return state->file;
 		}
-		io_file_put(state, NULL);
+		io_file_put(state);
 	}
 	state->file = fget_many(fd, state->ios_left);
 	if (!state->file)
@@ -1671,7 +1669,7 @@ out:
 static void io_submit_state_end(struct io_submit_state *state)
 {
 	blk_finish_plug(&state->plug);
-	io_file_put(state, NULL);
+	io_file_put(state);
 	if (state->free_reqs)
 		kmem_cache_free_bulk(req_cachep, state->free_reqs,
 					&state->reqs[state->cur_req]);
@@ -1920,6 +1918,10 @@ static int io_sq_thread(void *data)
 		unuse_mm(cur_mm);
 		mmput(cur_mm);
 	}
+
+	if (kthread_should_park())
+		kthread_parkme();
+
 	return 0;
 }
 
@@ -2054,6 +2056,7 @@ static void io_sq_thread_stop(struct io_ring_ctx *ctx)
 	if (ctx->sqo_thread) {
 		ctx->sqo_stop = 1;
 		mb();
+		kthread_park(ctx->sqo_thread);
 		kthread_stop(ctx->sqo_thread);
 		ctx->sqo_thread = NULL;
 	}
@@ -2236,10 +2239,6 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
 	mmgrab(current->mm);
 	ctx->sqo_mm = current->mm;
 
-	ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
-	if (!ctx->sq_thread_idle)
-		ctx->sq_thread_idle = HZ;
-
 	ret = -EINVAL;
 	if (!cpu_possible(p->sq_thread_cpu))
 		goto err;
@@ -2249,10 +2248,18 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
 		if (!capable(CAP_SYS_ADMIN))
 			goto err;
 
+		ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
+		if (!ctx->sq_thread_idle)
+			ctx->sq_thread_idle = HZ;
+
 		if (p->flags & IORING_SETUP_SQ_AFF) {
 			int cpu;
 
 			cpu = array_index_nospec(p->sq_thread_cpu, NR_CPUS);
+			ret = -EINVAL;
+			if (!cpu_possible(p->sq_thread_cpu))
+				goto err;
+
 			ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread,
 							ctx, cpu,
 							"io_uring-sq");
@@ -2922,11 +2929,23 @@ SYSCALL_DEFINE2(io_uring_setup, u32, entries,
 
 static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 			       void __user *arg, unsigned nr_args)
+	__releases(ctx->uring_lock)
+	__acquires(ctx->uring_lock)
 {
 	int ret;
 
 	percpu_ref_kill(&ctx->refs);
+
+	/*
+	 * Drop uring mutex before waiting for references to exit. If another
+	 * thread is currently inside io_uring_enter() it might need to grab
+	 * the uring_lock to make progress. If we hold it here across the drain
+	 * wait, then we can deadlock. It's safe to drop the mutex here, since
+	 * no new references will come in after we've killed the percpu ref.
+	 */
+	mutex_unlock(&ctx->uring_lock);
 	wait_for_completion(&ctx->ctx_done);
+	mutex_lock(&ctx->uring_lock);
 
 	switch (opcode) {
 	case IORING_REGISTER_BUFFERS:

include/linux/blkdev.h

@@ -548,7 +548,6 @@ struct request_queue {
 	struct rcu_head		rcu_head;
 	wait_queue_head_t	mq_freeze_wq;
 	struct percpu_ref	q_usage_counter;
-	struct list_head	all_q_node;
 
 	struct blk_mq_tag_set	*tag_set;
 	struct list_head	tag_set_list;

include/linux/bvec.h

@@ -160,8 +160,9 @@ static inline void bvec_advance(const struct bio_vec *bvec,
 		bv->bv_page = nth_page(bv->bv_page, 1);
 		bv->bv_offset = 0;
 	} else {
-		bv->bv_page = bvec->bv_page;
-		bv->bv_offset = bvec->bv_offset;
+		bv->bv_page = bvec_nth_page(bvec->bv_page, bvec->bv_offset /
+					    PAGE_SIZE);
+		bv->bv_offset = bvec->bv_offset & ~PAGE_MASK;
 	}
 	bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,
 			   bvec->bv_len - iter_all->done);

include/linux/elevator.h

@@ -31,6 +31,7 @@ struct elevator_mq_ops {
 	void (*exit_sched)(struct elevator_queue *);
 	int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
 	void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
+	void (*depth_updated)(struct blk_mq_hw_ctx *);
 
 	bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
 	bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);