block: generic request_queue reference counting
Allow pmem, and other synchronous/bio-based block drivers, to fallback on a per-cpu reference count managed by the core for tracking queue live/dead state. The existing per-cpu reference count for the blk_mq case is promoted to be used in all block i/o scenarios. This involves initializing it by default, waiting for it to drop to zero at exit, and holding a live reference over the invocation of q->make_request_fn() in generic_make_request(). The blk_mq code continues to take its own reference per blk_mq request and retains the ability to freeze the queue, but the check that the queue is frozen is moved to generic_make_request(). This fixes crash signatures like the following: BUG: unable to handle kernel paging request at ffff880140000000 [..] Call Trace: [<ffffffff8145e8bf>] ? copy_user_handle_tail+0x5f/0x70 [<ffffffffa004e1e0>] pmem_do_bvec.isra.11+0x70/0xf0 [nd_pmem] [<ffffffffa004e331>] pmem_make_request+0xd1/0x200 [nd_pmem] [<ffffffff811c3162>] ? mempool_alloc+0x72/0x1a0 [<ffffffff8141f8b6>] generic_make_request+0xd6/0x110 [<ffffffff8141f966>] submit_bio+0x76/0x170 [<ffffffff81286dff>] submit_bh_wbc+0x12f/0x160 [<ffffffff81286e62>] submit_bh+0x12/0x20 [<ffffffff813395bd>] jbd2_write_superblock+0x8d/0x170 [<ffffffff8133974d>] jbd2_mark_journal_empty+0x5d/0x90 [<ffffffff813399cb>] jbd2_journal_destroy+0x24b/0x270 [<ffffffff810bc4ca>] ? put_pwq_unlocked+0x2a/0x30 [<ffffffff810bc6f5>] ? destroy_workqueue+0x225/0x250 [<ffffffff81303494>] ext4_put_super+0x64/0x360 [<ffffffff8124ab1a>] generic_shutdown_super+0x6a/0xf0 Cc: Jens Axboe <axboe@kernel.dk> Cc: Keith Busch <keith.busch@intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Suggested-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Dan Williams
Jens Axboe
parent
4cfc766e07
commit
3ef28e83ab
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@ -554,13 +554,10 @@ void blk_cleanup_queue(struct request_queue *q)
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* Drain all requests queued before DYING marking. Set DEAD flag to
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* prevent that q->request_fn() gets invoked after draining finished.
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*/
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if (q->mq_ops) {
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blk_mq_freeze_queue(q);
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spin_lock_irq(lock);
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} else {
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spin_lock_irq(lock);
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blk_freeze_queue(q);
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spin_lock_irq(lock);
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if (!q->mq_ops)
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__blk_drain_queue(q, true);
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}
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queue_flag_set(QUEUE_FLAG_DEAD, q);
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spin_unlock_irq(lock);
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@ -570,6 +567,7 @@ void blk_cleanup_queue(struct request_queue *q)
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if (q->mq_ops)
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blk_mq_free_queue(q);
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percpu_ref_exit(&q->q_usage_counter);
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spin_lock_irq(lock);
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if (q->queue_lock != &q->__queue_lock)
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@ -629,6 +627,40 @@ struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
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}
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EXPORT_SYMBOL(blk_alloc_queue);
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int blk_queue_enter(struct request_queue *q, gfp_t gfp)
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{
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while (true) {
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int ret;
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if (percpu_ref_tryget_live(&q->q_usage_counter))
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return 0;
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if (!(gfp & __GFP_WAIT))
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return -EBUSY;
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ret = wait_event_interruptible(q->mq_freeze_wq,
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!atomic_read(&q->mq_freeze_depth) ||
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blk_queue_dying(q));
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if (blk_queue_dying(q))
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return -ENODEV;
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if (ret)
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return ret;
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}
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}
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void blk_queue_exit(struct request_queue *q)
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{
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percpu_ref_put(&q->q_usage_counter);
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}
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static void blk_queue_usage_counter_release(struct percpu_ref *ref)
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{
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struct request_queue *q =
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container_of(ref, struct request_queue, q_usage_counter);
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wake_up_all(&q->mq_freeze_wq);
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}
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struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
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{
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struct request_queue *q;
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@ -690,11 +722,22 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
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init_waitqueue_head(&q->mq_freeze_wq);
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if (blkcg_init_queue(q))
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/*
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* Init percpu_ref in atomic mode so that it's faster to shutdown.
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* See blk_register_queue() for details.
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*/
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if (percpu_ref_init(&q->q_usage_counter,
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blk_queue_usage_counter_release,
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PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
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goto fail_bdi;
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if (blkcg_init_queue(q))
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goto fail_ref;
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return q;
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fail_ref:
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percpu_ref_exit(&q->q_usage_counter);
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fail_bdi:
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bdi_destroy(&q->backing_dev_info);
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fail_split:
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@ -1966,9 +2009,19 @@ void generic_make_request(struct bio *bio)
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do {
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struct request_queue *q = bdev_get_queue(bio->bi_bdev);
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q->make_request_fn(q, bio);
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if (likely(blk_queue_enter(q, __GFP_WAIT) == 0)) {
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bio = bio_list_pop(current->bio_list);
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q->make_request_fn(q, bio);
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blk_queue_exit(q);
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bio = bio_list_pop(current->bio_list);
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} else {
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struct bio *bio_next = bio_list_pop(current->bio_list);
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bio_io_error(bio);
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bio = bio_next;
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}
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} while (bio);
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current->bio_list = NULL; /* deactivate */
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}
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@ -413,12 +413,6 @@ static void blk_mq_sysfs_init(struct request_queue *q)
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kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
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}
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/* see blk_register_queue() */
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void blk_mq_finish_init(struct request_queue *q)
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{
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percpu_ref_switch_to_percpu(&q->mq_usage_counter);
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}
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int blk_mq_register_disk(struct gendisk *disk)
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{
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struct device *dev = disk_to_dev(disk);
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@ -78,47 +78,13 @@ static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
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clear_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
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}
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static int blk_mq_queue_enter(struct request_queue *q, gfp_t gfp)
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{
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while (true) {
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int ret;
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if (percpu_ref_tryget_live(&q->mq_usage_counter))
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return 0;
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if (!(gfp & __GFP_WAIT))
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return -EBUSY;
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ret = wait_event_interruptible(q->mq_freeze_wq,
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!atomic_read(&q->mq_freeze_depth) ||
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blk_queue_dying(q));
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if (blk_queue_dying(q))
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return -ENODEV;
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if (ret)
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return ret;
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}
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}
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static void blk_mq_queue_exit(struct request_queue *q)
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{
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percpu_ref_put(&q->mq_usage_counter);
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}
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static void blk_mq_usage_counter_release(struct percpu_ref *ref)
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{
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struct request_queue *q =
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container_of(ref, struct request_queue, mq_usage_counter);
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wake_up_all(&q->mq_freeze_wq);
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}
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void blk_mq_freeze_queue_start(struct request_queue *q)
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{
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int freeze_depth;
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freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
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if (freeze_depth == 1) {
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percpu_ref_kill(&q->mq_usage_counter);
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percpu_ref_kill(&q->q_usage_counter);
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blk_mq_run_hw_queues(q, false);
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}
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}
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@ -126,18 +92,34 @@ EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
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static void blk_mq_freeze_queue_wait(struct request_queue *q)
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{
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wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
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wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
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}
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/*
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* Guarantee no request is in use, so we can change any data structure of
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* the queue afterward.
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*/
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void blk_mq_freeze_queue(struct request_queue *q)
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void blk_freeze_queue(struct request_queue *q)
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{
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/*
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* In the !blk_mq case we are only calling this to kill the
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* q_usage_counter, otherwise this increases the freeze depth
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* and waits for it to return to zero. For this reason there is
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* no blk_unfreeze_queue(), and blk_freeze_queue() is not
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* exported to drivers as the only user for unfreeze is blk_mq.
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*/
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blk_mq_freeze_queue_start(q);
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blk_mq_freeze_queue_wait(q);
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}
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void blk_mq_freeze_queue(struct request_queue *q)
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{
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/*
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* ...just an alias to keep freeze and unfreeze actions balanced
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* in the blk_mq_* namespace
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*/
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blk_freeze_queue(q);
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}
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EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
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void blk_mq_unfreeze_queue(struct request_queue *q)
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@ -147,7 +129,7 @@ void blk_mq_unfreeze_queue(struct request_queue *q)
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freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
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WARN_ON_ONCE(freeze_depth < 0);
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if (!freeze_depth) {
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percpu_ref_reinit(&q->mq_usage_counter);
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percpu_ref_reinit(&q->q_usage_counter);
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wake_up_all(&q->mq_freeze_wq);
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}
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}
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@ -256,7 +238,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp,
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struct blk_mq_alloc_data alloc_data;
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int ret;
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ret = blk_mq_queue_enter(q, gfp);
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ret = blk_queue_enter(q, gfp);
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if (ret)
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return ERR_PTR(ret);
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@ -279,7 +261,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp,
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}
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blk_mq_put_ctx(ctx);
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if (!rq) {
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blk_mq_queue_exit(q);
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blk_queue_exit(q);
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return ERR_PTR(-EWOULDBLOCK);
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}
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return rq;
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@ -298,7 +280,7 @@ static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
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clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
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blk_mq_put_tag(hctx, tag, &ctx->last_tag);
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blk_mq_queue_exit(q);
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blk_queue_exit(q);
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}
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void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
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@ -1177,11 +1159,7 @@ static struct request *blk_mq_map_request(struct request_queue *q,
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int rw = bio_data_dir(bio);
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struct blk_mq_alloc_data alloc_data;
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if (unlikely(blk_mq_queue_enter(q, GFP_KERNEL))) {
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bio_io_error(bio);
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return NULL;
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}
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blk_queue_enter_live(q);
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ctx = blk_mq_get_ctx(q);
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hctx = q->mq_ops->map_queue(q, ctx->cpu);
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@ -2000,14 +1978,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
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hctxs[i]->queue_num = i;
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}
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/*
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* Init percpu_ref in atomic mode so that it's faster to shutdown.
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* See blk_register_queue() for details.
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*/
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if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release,
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PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
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goto err_hctxs;
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setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
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blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
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@ -2088,8 +2058,6 @@ void blk_mq_free_queue(struct request_queue *q)
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blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
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blk_mq_free_hw_queues(q, set);
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percpu_ref_exit(&q->mq_usage_counter);
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}
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/* Basically redo blk_mq_init_queue with queue frozen */
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@ -599,9 +599,8 @@ int blk_register_queue(struct gendisk *disk)
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*/
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if (!blk_queue_init_done(q)) {
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queue_flag_set_unlocked(QUEUE_FLAG_INIT_DONE, q);
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percpu_ref_switch_to_percpu(&q->q_usage_counter);
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blk_queue_bypass_end(q);
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if (q->mq_ops)
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blk_mq_finish_init(q);
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}
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ret = blk_trace_init_sysfs(dev);
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14
block/blk.h
14
block/blk.h
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@ -72,6 +72,20 @@ void blk_dequeue_request(struct request *rq);
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void __blk_queue_free_tags(struct request_queue *q);
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bool __blk_end_bidi_request(struct request *rq, int error,
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unsigned int nr_bytes, unsigned int bidi_bytes);
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int blk_queue_enter(struct request_queue *q, gfp_t gfp);
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void blk_queue_exit(struct request_queue *q);
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void blk_freeze_queue(struct request_queue *q);
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static inline void blk_queue_enter_live(struct request_queue *q)
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{
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/*
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* Given that running in generic_make_request() context
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* guarantees that a live reference against q_usage_counter has
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* been established, further references under that same context
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* need not check that the queue has been frozen (marked dead).
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*/
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percpu_ref_get(&q->q_usage_counter);
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}
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void blk_rq_timed_out_timer(unsigned long data);
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unsigned long blk_rq_timeout(unsigned long timeout);
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@ -166,7 +166,6 @@ enum {
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struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *);
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struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
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struct request_queue *q);
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void blk_mq_finish_init(struct request_queue *q);
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int blk_mq_register_disk(struct gendisk *);
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void blk_mq_unregister_disk(struct gendisk *);
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@ -450,7 +450,7 @@ struct request_queue {
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#endif
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struct rcu_head rcu_head;
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wait_queue_head_t mq_freeze_wq;
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struct percpu_ref mq_usage_counter;
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struct percpu_ref q_usage_counter;
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struct list_head all_q_node;
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struct blk_mq_tag_set *tag_set;
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