blk-mq: rework flush sequencing logic
Witch to using a preallocated flush_rq for blk-mq similar to what's done with the old request path. This allows us to set up the request properly with a tag from the actually allowed range and ->rq_disk as needed by some drivers. To make life easier we also switch to dynamic allocation of ->flush_rq for the old path. This effectively reverts most of "blk-mq: fix for flush deadlock" and "blk-mq: Don't reserve a tag for flush request" Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
parent
ce2c350b2c
commit
18741986a4
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@ -693,11 +693,20 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
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if (!uninit_q)
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return NULL;
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uninit_q->flush_rq = kzalloc(sizeof(struct request), GFP_KERNEL);
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if (!uninit_q->flush_rq)
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goto out_cleanup_queue;
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q = blk_init_allocated_queue(uninit_q, rfn, lock);
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if (!q)
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blk_cleanup_queue(uninit_q);
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goto out_free_flush_rq;
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return q;
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out_free_flush_rq:
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kfree(uninit_q->flush_rq);
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out_cleanup_queue:
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blk_cleanup_queue(uninit_q);
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return NULL;
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}
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EXPORT_SYMBOL(blk_init_queue_node);
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@ -1127,7 +1136,7 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw,
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struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
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{
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if (q->mq_ops)
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return blk_mq_alloc_request(q, rw, gfp_mask, false);
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return blk_mq_alloc_request(q, rw, gfp_mask);
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else
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return blk_old_get_request(q, rw, gfp_mask);
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}
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@ -130,20 +130,26 @@ static void blk_flush_restore_request(struct request *rq)
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blk_clear_rq_complete(rq);
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}
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static void mq_flush_data_run(struct work_struct *work)
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static void mq_flush_run(struct work_struct *work)
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{
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struct request *rq;
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rq = container_of(work, struct request, mq_flush_data);
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rq = container_of(work, struct request, mq_flush_work);
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memset(&rq->csd, 0, sizeof(rq->csd));
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blk_mq_run_request(rq, true, false);
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}
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static void blk_mq_flush_data_insert(struct request *rq)
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static bool blk_flush_queue_rq(struct request *rq)
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{
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INIT_WORK(&rq->mq_flush_data, mq_flush_data_run);
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kblockd_schedule_work(rq->q, &rq->mq_flush_data);
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if (rq->q->mq_ops) {
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INIT_WORK(&rq->mq_flush_work, mq_flush_run);
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kblockd_schedule_work(rq->q, &rq->mq_flush_work);
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return false;
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} else {
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list_add_tail(&rq->queuelist, &rq->q->queue_head);
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return true;
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}
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}
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/**
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@ -187,12 +193,7 @@ static bool blk_flush_complete_seq(struct request *rq, unsigned int seq,
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case REQ_FSEQ_DATA:
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list_move_tail(&rq->flush.list, &q->flush_data_in_flight);
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if (q->mq_ops)
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blk_mq_flush_data_insert(rq);
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else {
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list_add(&rq->queuelist, &q->queue_head);
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queued = true;
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}
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queued = blk_flush_queue_rq(rq);
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break;
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case REQ_FSEQ_DONE:
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@ -216,9 +217,6 @@ static bool blk_flush_complete_seq(struct request *rq, unsigned int seq,
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}
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kicked = blk_kick_flush(q);
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/* blk_mq_run_flush will run queue */
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if (q->mq_ops)
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return queued;
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return kicked | queued;
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}
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@ -230,10 +228,9 @@ static void flush_end_io(struct request *flush_rq, int error)
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struct request *rq, *n;
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unsigned long flags = 0;
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if (q->mq_ops) {
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blk_mq_free_request(flush_rq);
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if (q->mq_ops)
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spin_lock_irqsave(&q->mq_flush_lock, flags);
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}
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running = &q->flush_queue[q->flush_running_idx];
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BUG_ON(q->flush_pending_idx == q->flush_running_idx);
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@ -263,48 +260,14 @@ static void flush_end_io(struct request *flush_rq, int error)
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* kblockd.
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*/
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if (queued || q->flush_queue_delayed) {
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if (!q->mq_ops)
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blk_run_queue_async(q);
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else
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/*
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* This can be optimized to only run queues with requests
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* queued if necessary.
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*/
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blk_mq_run_queues(q, true);
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WARN_ON(q->mq_ops);
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blk_run_queue_async(q);
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}
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q->flush_queue_delayed = 0;
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if (q->mq_ops)
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spin_unlock_irqrestore(&q->mq_flush_lock, flags);
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}
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static void mq_flush_work(struct work_struct *work)
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{
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struct request_queue *q;
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struct request *rq;
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q = container_of(work, struct request_queue, mq_flush_work);
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rq = blk_mq_alloc_request(q, WRITE_FLUSH|REQ_FLUSH_SEQ,
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__GFP_WAIT|GFP_ATOMIC, false);
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rq->cmd_type = REQ_TYPE_FS;
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rq->end_io = flush_end_io;
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blk_mq_run_request(rq, true, false);
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}
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/*
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* We can't directly use q->flush_rq, because it doesn't have tag and is not in
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* hctx->rqs[]. so we must allocate a new request, since we can't sleep here,
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* so offload the work to workqueue.
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*
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* Note: we assume a flush request finished in any hardware queue will flush
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* the whole disk cache.
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*/
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static void mq_run_flush(struct request_queue *q)
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{
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kblockd_schedule_work(q, &q->mq_flush_work);
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}
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/**
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* blk_kick_flush - consider issuing flush request
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* @q: request_queue being kicked
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@ -339,19 +302,31 @@ static bool blk_kick_flush(struct request_queue *q)
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* different from running_idx, which means flush is in flight.
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*/
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q->flush_pending_idx ^= 1;
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if (q->mq_ops) {
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mq_run_flush(q);
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return true;
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struct blk_mq_ctx *ctx = first_rq->mq_ctx;
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struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
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blk_mq_rq_init(hctx, q->flush_rq);
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q->flush_rq->mq_ctx = ctx;
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/*
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* Reuse the tag value from the fist waiting request,
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* with blk-mq the tag is generated during request
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* allocation and drivers can rely on it being inside
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* the range they asked for.
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*/
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q->flush_rq->tag = first_rq->tag;
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} else {
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blk_rq_init(q, q->flush_rq);
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}
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blk_rq_init(q, &q->flush_rq);
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q->flush_rq.cmd_type = REQ_TYPE_FS;
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q->flush_rq.cmd_flags = WRITE_FLUSH | REQ_FLUSH_SEQ;
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q->flush_rq.rq_disk = first_rq->rq_disk;
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q->flush_rq.end_io = flush_end_io;
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q->flush_rq->cmd_type = REQ_TYPE_FS;
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q->flush_rq->cmd_flags = WRITE_FLUSH | REQ_FLUSH_SEQ;
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q->flush_rq->rq_disk = first_rq->rq_disk;
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q->flush_rq->end_io = flush_end_io;
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list_add_tail(&q->flush_rq.queuelist, &q->queue_head);
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return true;
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return blk_flush_queue_rq(q->flush_rq);
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}
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static void flush_data_end_io(struct request *rq, int error)
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@ -407,11 +382,8 @@ void blk_insert_flush(struct request *rq)
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/*
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* @policy now records what operations need to be done. Adjust
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* REQ_FLUSH and FUA for the driver.
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* We keep REQ_FLUSH for mq to track flush requests. For !FUA,
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* we never dispatch the request directly.
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*/
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if (rq->cmd_flags & REQ_FUA)
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rq->cmd_flags &= ~REQ_FLUSH;
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rq->cmd_flags &= ~REQ_FLUSH;
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if (!(fflags & REQ_FUA))
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rq->cmd_flags &= ~REQ_FUA;
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@ -560,5 +532,4 @@ EXPORT_SYMBOL(blkdev_issue_flush);
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void blk_mq_init_flush(struct request_queue *q)
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{
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spin_lock_init(&q->mq_flush_lock);
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INIT_WORK(&q->mq_flush_work, mq_flush_work);
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}
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@ -194,27 +194,9 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
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}
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static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
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gfp_t gfp, bool reserved,
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int rw)
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gfp_t gfp, bool reserved)
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{
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struct request *req;
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bool is_flush = false;
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/*
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* flush need allocate a request, leave at least one request for
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* non-flush IO to avoid deadlock
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*/
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if ((rw & REQ_FLUSH) && !(rw & REQ_FLUSH_SEQ)) {
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if (atomic_inc_return(&hctx->pending_flush) >=
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hctx->queue_depth - hctx->reserved_tags - 1) {
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atomic_dec(&hctx->pending_flush);
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return NULL;
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}
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is_flush = true;
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}
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req = blk_mq_alloc_rq(hctx, gfp, reserved);
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if (!req && is_flush)
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atomic_dec(&hctx->pending_flush);
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return req;
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return blk_mq_alloc_rq(hctx, gfp, reserved);
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}
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static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
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struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
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struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
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rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved, rw);
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rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved);
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if (rq) {
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blk_mq_rq_ctx_init(q, ctx, rq, rw);
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break;
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return rq;
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}
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struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
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gfp_t gfp, bool reserved)
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struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp)
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{
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struct request *rq;
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if (blk_mq_queue_enter(q))
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return NULL;
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rq = blk_mq_alloc_request_pinned(q, rw, gfp, reserved);
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rq = blk_mq_alloc_request_pinned(q, rw, gfp, false);
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if (rq)
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blk_mq_put_ctx(rq->mq_ctx);
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return rq;
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@ -276,7 +257,7 @@ EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
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/*
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* Re-init and set pdu, if we have it
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*/
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static void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
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void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
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{
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blk_rq_init(hctx->queue, rq);
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@ -290,9 +271,6 @@ static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
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const int tag = rq->tag;
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struct request_queue *q = rq->q;
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if ((rq->cmd_flags & REQ_FLUSH) && !(rq->cmd_flags & REQ_FLUSH_SEQ))
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atomic_dec(&hctx->pending_flush);
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blk_mq_rq_init(hctx, rq);
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blk_mq_put_tag(hctx->tags, tag);
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@ -946,14 +924,14 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
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hctx = q->mq_ops->map_queue(q, ctx->cpu);
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trace_block_getrq(q, bio, rw);
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rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false, bio->bi_rw);
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rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
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if (likely(rq))
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blk_mq_rq_ctx_init(q, ctx, rq, bio->bi_rw);
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blk_mq_rq_ctx_init(q, ctx, rq, rw);
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else {
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blk_mq_put_ctx(ctx);
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trace_block_sleeprq(q, bio, rw);
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rq = blk_mq_alloc_request_pinned(q, bio->bi_rw,
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__GFP_WAIT|GFP_ATOMIC, false);
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rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC,
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false);
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ctx = rq->mq_ctx;
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hctx = q->mq_ops->map_queue(q, ctx->cpu);
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}
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@ -1230,9 +1208,7 @@ static int blk_mq_init_hw_queues(struct request_queue *q,
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hctx->queue_num = i;
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hctx->flags = reg->flags;
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hctx->queue_depth = reg->queue_depth;
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hctx->reserved_tags = reg->reserved_tags;
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hctx->cmd_size = reg->cmd_size;
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atomic_set(&hctx->pending_flush, 0);
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blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
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blk_mq_hctx_notify, hctx);
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@ -1412,9 +1388,14 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
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blk_mq_init_flush(q);
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blk_mq_init_cpu_queues(q, reg->nr_hw_queues);
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if (blk_mq_init_hw_queues(q, reg, driver_data))
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q->flush_rq = kzalloc(round_up(sizeof(struct request) + reg->cmd_size,
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cache_line_size()), GFP_KERNEL);
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if (!q->flush_rq)
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goto err_hw;
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if (blk_mq_init_hw_queues(q, reg, driver_data))
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goto err_flush_rq;
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blk_mq_map_swqueue(q);
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mutex_lock(&all_q_mutex);
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@ -1422,6 +1403,9 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
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mutex_unlock(&all_q_mutex);
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return q;
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err_flush_rq:
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kfree(q->flush_rq);
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err_hw:
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kfree(q->mq_map);
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err_map:
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@ -28,6 +28,7 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
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void blk_mq_init_flush(struct request_queue *q);
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void blk_mq_drain_queue(struct request_queue *q);
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void blk_mq_free_queue(struct request_queue *q);
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void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq);
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/*
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* CPU hotplug helpers
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|
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@ -549,6 +549,8 @@ static void blk_release_queue(struct kobject *kobj)
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if (q->mq_ops)
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blk_mq_free_queue(q);
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kfree(q->flush_rq);
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blk_trace_shutdown(q);
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bdi_destroy(&q->backing_dev_info);
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@ -36,15 +36,12 @@ struct blk_mq_hw_ctx {
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struct list_head page_list;
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struct blk_mq_tags *tags;
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atomic_t pending_flush;
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unsigned long queued;
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unsigned long run;
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#define BLK_MQ_MAX_DISPATCH_ORDER 10
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unsigned long dispatched[BLK_MQ_MAX_DISPATCH_ORDER];
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unsigned int queue_depth;
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unsigned int reserved_tags;
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unsigned int numa_node;
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unsigned int cmd_size; /* per-request extra data */
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@ -129,7 +126,7 @@ void blk_mq_insert_request(struct request_queue *, struct request *,
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void blk_mq_run_queues(struct request_queue *q, bool async);
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void blk_mq_free_request(struct request *rq);
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bool blk_mq_can_queue(struct blk_mq_hw_ctx *);
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struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp, bool reserved);
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struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp);
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struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw, gfp_t gfp);
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struct request *blk_mq_rq_from_tag(struct request_queue *q, unsigned int tag);
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@ -101,7 +101,7 @@ struct request {
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};
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union {
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struct call_single_data csd;
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struct work_struct mq_flush_data;
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struct work_struct mq_flush_work;
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};
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struct request_queue *q;
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@ -451,13 +451,8 @@ struct request_queue {
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unsigned long flush_pending_since;
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struct list_head flush_queue[2];
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struct list_head flush_data_in_flight;
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union {
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struct request flush_rq;
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struct {
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spinlock_t mq_flush_lock;
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struct work_struct mq_flush_work;
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};
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};
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struct request *flush_rq;
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spinlock_t mq_flush_lock;
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struct mutex sysfs_lock;
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