From be4c427809b0a746aff54dbb8ef663f0184291d0 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Fri, 19 May 2023 06:40:47 +0200
Subject: [PATCH] blk-mq: use the I/O scheduler for writes from the flush state
machine
Send write requests issued by the flush state machine through the normal
I/O submission path including the I/O scheduler (if present) so that I/O
scheduler policies are applied to writes with the FUA flag set.
Separate the I/O scheduler members from the flush members in struct
request since now a request may pass through both an I/O scheduler
and the flush machinery.
Note that the actual flush requests, which have no bio attached to the
request still bypass the I/O schedulers.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[hch: rebased]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230519044050.107790-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
block/blk-mq.c | 4 ++--
include/linux/blk-mq.h | 27 +++++++++++----------------
2 files changed, 13 insertions(+), 18 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index c0b394096b6b6..aac67bc3d3680 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -458,7 +458,7 @@ static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
* Flush/passthrough requests are special and go directly to the
* dispatch list.
*/
- if (!op_is_flush(data->cmd_flags) &&
+ if ((data->cmd_flags & REQ_OP_MASK) != REQ_OP_FLUSH &&
!blk_op_is_passthrough(data->cmd_flags)) {
struct elevator_mq_ops *ops = &q->elevator->type->ops;
@@ -2497,7 +2497,7 @@ static void blk_mq_insert_request(struct request *rq, blk_insert_t flags)
* dispatch it given we prioritize requests in hctx->dispatch.
*/
blk_mq_request_bypass_insert(rq, flags);
- } else if (rq->rq_flags & RQF_FLUSH_SEQ) {
+ } else if (req_op(rq) == REQ_OP_FLUSH) {
/*
* Firstly normal IO request is inserted to scheduler queue or
* sw queue, meantime we add flush request to dispatch queue(
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 49d14b1acfa5d..935201c897437 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -169,25 +169,20 @@ struct request {
void *completion_data;
};
-
/*
* Three pointers are available for the IO schedulers, if they need
- * more they have to dynamically allocate it. Flush requests are
- * never put on the IO scheduler. So let the flush fields share
- * space with the elevator data.
+ * more they have to dynamically allocate it.
*/
- union {
- struct {
- struct io_cq *icq;
- void *priv[2];
- } elv;
-
- struct {
- unsigned int seq;
- struct list_head list;
- rq_end_io_fn *saved_end_io;
- } flush;
- };
+ struct {
+ struct io_cq *icq;
+ void *priv[2];
+ } elv;
+
+ struct {
+ unsigned int seq;
+ struct list_head list;
+ rq_end_io_fn *saved_end_io;
+ } flush;
union {
struct __call_single_data csd;
--
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