From 78b10be23d42e66fc42e52b9ae620f0a6ef5b8c7 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Mon, 9 Mar 2020 21:26:20 -0700 Subject: [PATCH] null_blk: Fix changing the number of hardware queues Instead of initializing null_blk hardware queues explicitly after the request queue has been created, provide .init_hctx() and .exit_hctx() callback functions. The latter functions are not only called during request queue allocation but also when the number of hardware queues changes. Allocate nr_cpu_ids queues during initialization to support increasing the number of hardware queues above the initial hardware queue count. This change fixes increasing the number of hardware queues above the initial number of hardware queues and also keeps nullb->nr_queues in sync with the number of hardware queues. Fixes: 45919fbfe1c4 ("null_blk: Enable modifying 'submit_queues' after an instance has been configured") Signed-off-by: Bart Van Assche Cc: Johannes Thumshirn Cc: Hannes Reinecke Cc: Ming Lei Cc: Christoph Hellwig Signed-off-by: Jens Axboe --- drivers/block/null_blk_main.c | 103 +++++++++++++++++++++++++++--------------- 1 file changed, 66 insertions(+), 37 deletions(-) diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c index b8a08b8..83e31b8 100644 --- a/drivers/block/null_blk_main.c +++ b/drivers/block/null_blk_main.c @@ -302,6 +302,12 @@ static int nullb_apply_submit_queues(struct nullb_device *dev, if (!nullb) return 0; + /* + * Make sure that null_init_hctx() does not access nullb->queues[] past + * the end of that array. + */ + if (submit_queues > nr_cpu_ids) + return -EINVAL; set = nullb->tag_set; blk_mq_update_nr_hw_queues(set, submit_queues); return set->nr_hw_queues == submit_queues ? 0 : -ENOMEM; @@ -1408,12 +1414,6 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx, return null_handle_cmd(cmd, sector, nr_sectors, req_op(bd->rq)); } -static const struct blk_mq_ops null_mq_ops = { - .queue_rq = null_queue_rq, - .complete = null_complete_rq, - .timeout = null_timeout_rq, -}; - static void cleanup_queue(struct nullb_queue *nq) { kfree(nq->tag_map); @@ -1430,6 +1430,43 @@ static void cleanup_queues(struct nullb *nullb) kfree(nullb->queues); } +static void null_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx) +{ + struct nullb_queue *nq = hctx->driver_data; + struct nullb *nullb = nq->dev->nullb; + + nullb->nr_queues--; +} + +static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq) +{ + init_waitqueue_head(&nq->wait); + nq->queue_depth = nullb->queue_depth; + nq->dev = nullb->dev; +} + +static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data, + unsigned int hctx_idx) +{ + struct nullb *nullb = hctx->queue->queuedata; + struct nullb_queue *nq; + + nq = &nullb->queues[hctx_idx]; + hctx->driver_data = nq; + null_init_queue(nullb, nq); + nullb->nr_queues++; + + return 0; +} + +static const struct blk_mq_ops null_mq_ops = { + .queue_rq = null_queue_rq, + .complete = null_complete_rq, + .timeout = null_timeout_rq, + .init_hctx = null_init_hctx, + .exit_hctx = null_exit_hctx, +}; + static void null_del_dev(struct nullb *nullb) { struct nullb_device *dev = nullb->dev; @@ -1473,33 +1510,6 @@ static const struct block_device_operations null_ops = { .report_zones = null_report_zones, }; -static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq) -{ - BUG_ON(!nullb); - BUG_ON(!nq); - - init_waitqueue_head(&nq->wait); - nq->queue_depth = nullb->queue_depth; - nq->dev = nullb->dev; -} - -static void null_init_queues(struct nullb *nullb) -{ - struct request_queue *q = nullb->q; - struct blk_mq_hw_ctx *hctx; - struct nullb_queue *nq; - int i; - - queue_for_each_hw_ctx(q, hctx, i) { - if (!hctx->nr_ctx || !hctx->tags) - continue; - nq = &nullb->queues[i]; - hctx->driver_data = nq; - null_init_queue(nullb, nq); - nullb->nr_queues++; - } -} - static int setup_commands(struct nullb_queue *nq) { struct nullb_cmd *cmd; @@ -1526,8 +1536,7 @@ static int setup_commands(struct nullb_queue *nq) static int setup_queues(struct nullb *nullb) { - nullb->queues = kcalloc(nullb->dev->submit_queues, - sizeof(struct nullb_queue), + nullb->queues = kcalloc(nr_cpu_ids, sizeof(struct nullb_queue), GFP_KERNEL); if (!nullb->queues) return -ENOMEM; @@ -1673,6 +1682,27 @@ static bool null_setup_fault(void) return true; } +/* + * This function is identical to blk_mq_init_queue() except that it sets + * queuedata before .init_hctx is called. + */ +static struct request_queue *nullb_alloc_queue(struct nullb *nullb) +{ + struct request_queue *uninit_q, *q; + struct blk_mq_tag_set *set = nullb->tag_set; + + uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node); + if (!uninit_q) + return ERR_PTR(-ENOMEM); + + uninit_q->queuedata = nullb; + q = blk_mq_init_allocated_queue(set, uninit_q, false); + if (IS_ERR(q)) + blk_cleanup_queue(uninit_q); + + return q; +} + static int null_add_dev(struct nullb_device *dev) { struct nullb *nullb; @@ -1712,12 +1742,11 @@ static int null_add_dev(struct nullb_device *dev) goto out_cleanup_queues; nullb->tag_set->timeout = 5 * HZ; - nullb->q = blk_mq_init_queue(nullb->tag_set); + nullb->q = nullb_alloc_queue(nullb); if (IS_ERR(nullb->q)) { rv = -ENOMEM; goto out_cleanup_tags; } - null_init_queues(nullb); } else if (dev->queue_mode == NULL_Q_BIO) { nullb->q = blk_alloc_queue_node(GFP_KERNEL, dev->home_node); if (!nullb->q) { -- 2.7.4