[PATCH 1/5] blk-mq: Move flush queue allocation into blk_mq_init_hctx()
From: Ming Lei <hidden>
Date: 2025-08-01 11:45:00
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Move flush queue allocation into blk_mq_init_hctx() and its release into blk_mq_exit_hctx(), and prepare for replacing tags->lock with SRCU to draining inflight request walking. blk_mq_exit_hctx() is the last chance for us to get valid `tag_set` reference, and we need to add one SRCU to `tag_set` for freeing flush request via call_srcu(). It is safe to move flush queue & request release into blk_mq_exit_hctx(), because blk_mq_clear_flush_rq_mapping() clears the flush request reference int driver tags inflight request table, meantime inflight request walking is drained. Signed-off-by: Ming Lei <redacted> --- block/blk-mq-sysfs.c | 1 - block/blk-mq.c | 20 +++++++++++++------- 2 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 24656980f443..c8dfed6c1c96 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c@@ -34,7 +34,6 @@ static void blk_mq_hw_sysfs_release(struct kobject *kobj) struct blk_mq_hw_ctx *hctx = container_of(kobj, struct blk_mq_hw_ctx, kobj); - blk_free_flush_queue(hctx->fq); sbitmap_free(&hctx->ctx_map); free_cpumask_var(hctx->cpumask); kfree(hctx->ctxs);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9692fa4c3ef2..c6a1366dbe77 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c@@ -3939,6 +3939,9 @@ static void blk_mq_exit_hctx(struct request_queue *q, if (set->ops->exit_hctx) set->ops->exit_hctx(hctx, hctx_idx); + blk_free_flush_queue(hctx->fq); + hctx->fq = NULL; + xa_erase(&q->hctx_table, hctx_idx); spin_lock(&q->unused_hctx_lock);
@@ -3964,13 +3967,19 @@ static int blk_mq_init_hctx(struct request_queue *q, struct blk_mq_tag_set *set, struct blk_mq_hw_ctx *hctx, unsigned hctx_idx) { + gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY; + + hctx->fq = blk_alloc_flush_queue(hctx->numa_node, set->cmd_size, gfp); + if (!hctx->fq) + goto fail; + hctx->queue_num = hctx_idx; hctx->tags = set->tags[hctx_idx]; if (set->ops->init_hctx && set->ops->init_hctx(hctx, set->driver_data, hctx_idx)) - goto fail; + goto fail_free_fq; if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx, hctx->numa_node))
@@ -3987,6 +3996,9 @@ static int blk_mq_init_hctx(struct request_queue *q, exit_hctx: if (set->ops->exit_hctx) set->ops->exit_hctx(hctx, hctx_idx); + fail_free_fq: + blk_free_flush_queue(hctx->fq); + hctx->fq = NULL; fail: return -1; }
@@ -4038,16 +4050,10 @@ blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set, init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake); INIT_LIST_HEAD(&hctx->dispatch_wait.entry); - hctx->fq = blk_alloc_flush_queue(hctx->numa_node, set->cmd_size, gfp); - if (!hctx->fq) - goto free_bitmap; - blk_mq_hctx_kobj_init(hctx); return hctx; - free_bitmap: - sbitmap_free(&hctx->ctx_map); free_ctxs: kfree(hctx->ctxs); free_cpumask:
--
2.47.0