blk-mq: initialize struct request fields individually
This allows us to avoid a non-atomic memset over ->atomic_flags as well as killing lots of duplicate initializations. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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@ -82,9 +82,7 @@ static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
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tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
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if (tag != BLK_MQ_TAG_FAIL) {
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rq = hctx->tags->rqs[tag];
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blk_rq_init(hctx->queue, rq);
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rq->tag = tag;
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return rq;
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}
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@ -187,10 +185,54 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
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if (blk_queue_io_stat(q))
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rw_flags |= REQ_IO_STAT;
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INIT_LIST_HEAD(&rq->queuelist);
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/* csd/requeue_work/fifo_time is initialized before use */
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rq->q = q;
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rq->mq_ctx = ctx;
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rq->cmd_flags = rw_flags;
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rq->cmd_type = 0;
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/* do not touch atomic flags, it needs atomic ops against the timer */
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rq->cpu = -1;
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rq->__data_len = 0;
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rq->__sector = (sector_t) -1;
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rq->bio = NULL;
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rq->biotail = NULL;
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INIT_HLIST_NODE(&rq->hash);
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RB_CLEAR_NODE(&rq->rb_node);
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memset(&rq->flush, 0, max(sizeof(rq->flush), sizeof(rq->elv)));
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rq->rq_disk = NULL;
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rq->part = NULL;
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rq->start_time = jiffies;
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#ifdef CONFIG_BLK_CGROUP
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rq->rl = NULL;
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set_start_time_ns(rq);
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rq->io_start_time_ns = 0;
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#endif
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rq->nr_phys_segments = 0;
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#if defined(CONFIG_BLK_DEV_INTEGRITY)
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rq->nr_integrity_segments = 0;
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#endif
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rq->ioprio = 0;
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rq->special = NULL;
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/* tag was already set */
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rq->errors = 0;
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memset(rq->__cmd, 0, sizeof(rq->__cmd));
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rq->cmd = rq->__cmd;
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rq->cmd_len = BLK_MAX_CDB;
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rq->extra_len = 0;
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rq->sense_len = 0;
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rq->resid_len = 0;
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rq->sense = NULL;
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rq->deadline = 0;
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INIT_LIST_HEAD(&rq->timeout_list);
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rq->timeout = 0;
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rq->retries = 0;
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rq->end_io = NULL;
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rq->end_io_data = NULL;
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rq->next_rq = NULL;
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ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
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}
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@ -258,6 +300,7 @@ 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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clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
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blk_mq_put_tag(hctx->tags, tag);
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blk_mq_queue_exit(q);
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}
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@ -90,9 +90,10 @@ enum rq_cmd_type_bits {
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#define BLK_MAX_CDB 16
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/*
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* try to put the fields that are referenced together in the same cacheline.
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* if you modify this structure, be sure to check block/blk-core.c:blk_rq_init()
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* as well!
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* Try to put the fields that are referenced together in the same cacheline.
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*
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* If you modify this structure, make sure to update blk_rq_init() and
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* especially blk_mq_rq_ctx_init() to take care of the added fields.
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*/
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struct request {
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struct list_head queuelist;
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