Can't we just not go through the scheduler for reserved tags? Obviously there is no point in scheduling them...Right, that would be possible. But I'd rather not treat any requests differently, it's a huge pain in the ass that flush request currently insert with a driver tag already allocated. So it's not because scheduling will add anything at all, it's more that I'd like to move flush requests to use regular inserts as well and not deal with some request being "special" in any way. The below should hopefully work. Totally untested... diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 54c84363c1b2..e48bc2c72615 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -181,7 +181,7 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags, struct blk_mq_ctx *ctx, unsigned int tag) { - if (tag >= tags->nr_reserved_tags) { + if (!blk_mq_tag_is_reserved(tags, tag)) { const int real_tag = tag - tags->nr_reserved_tags; BUG_ON(real_tag >= tags->nr_tags); diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h index 63497423c5cd..5cb51e53cc03 100644 --- a/block/blk-mq-tag.h +++ b/block/blk-mq-tag.h @@ -85,4 +85,10 @@ static inline void blk_mq_tag_set_rq(struct blk_mq_hw_ctx *hctx, hctx->tags->rqs[tag] = rq; } +static inline bool blk_mq_tag_is_reserved(struct blk_mq_tags *tags, + unsigned int tag) +{ + return tag < tags->nr_reserved_tags; +} + #endif diff --git a/block/blk-mq.c b/block/blk-mq.c index 9611cd9920e9..293e79c1ee95 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -853,6 +853,9 @@ bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx, return true; } + if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag)) + data.flags |= BLK_MQ_REQ_RESERVED; + rq->tag = blk_mq_get_tag(&data); if (rq->tag >= 0) { if (blk_mq_tag_busy(data.hctx)) {
Both patches look they'd work, I'll test. Thanks.
