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Date: Mon, 5 Dec 2016 11:27:00 -0700
From: Jens Axboe <axboe@...com>
To: <axboe@...nel.dk>, <linux-block@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
CC: <paolo.valente@...aro.org>, Jens Axboe <axboe@...com>
Subject: [PATCH 1/7] block: use legacy path for flush requests for MQ with a scheduler
No functional changes with this patch, it's just in preparation for
supporting legacy schedulers on blk-mq.
Signed-off-by: Jens Axboe <axboe@...com>
---
block/blk-core.c | 2 +-
block/blk-exec.c | 2 +-
block/blk-flush.c | 26 ++++++++++++++------------
block/blk.h | 12 +++++++++++-
4 files changed, 27 insertions(+), 15 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 4b7ec5958055..813c448453bf 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1310,7 +1310,7 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw,
struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
{
- if (q->mq_ops)
+ if (!blk_use_sched_path(q))
return blk_mq_alloc_request(q, rw,
(gfp_mask & __GFP_DIRECT_RECLAIM) ?
0 : BLK_MQ_REQ_NOWAIT);
diff --git a/block/blk-exec.c b/block/blk-exec.c
index 3ecb00a6cf45..3356dff5508c 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -64,7 +64,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
* don't check dying flag for MQ because the request won't
* be reused after dying flag is set
*/
- if (q->mq_ops) {
+ if (!blk_use_sched_path(q)) {
blk_mq_insert_request(rq, at_head, true, false);
return;
}
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 1bdbb3d3e5f5..040c36b83ef7 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -133,14 +133,16 @@ static void blk_flush_restore_request(struct request *rq)
static bool blk_flush_queue_rq(struct request *rq, bool add_front)
{
- if (rq->q->mq_ops) {
+ struct request_queue *q = rq->q;
+
+ if (!blk_use_sched_path(q)) {
blk_mq_add_to_requeue_list(rq, add_front, true);
return false;
} else {
if (add_front)
- list_add(&rq->queuelist, &rq->q->queue_head);
+ list_add(&rq->queuelist, &q->queue_head);
else
- list_add_tail(&rq->queuelist, &rq->q->queue_head);
+ list_add_tail(&rq->queuelist, &q->queue_head);
return true;
}
}
@@ -201,7 +203,7 @@ static bool blk_flush_complete_seq(struct request *rq,
BUG_ON(!list_empty(&rq->queuelist));
list_del_init(&rq->flush.list);
blk_flush_restore_request(rq);
- if (q->mq_ops)
+ if (!blk_use_sched_path(q))
blk_mq_end_request(rq, error);
else
__blk_end_request_all(rq, error);
@@ -224,7 +226,7 @@ static void flush_end_io(struct request *flush_rq, int error)
unsigned long flags = 0;
struct blk_flush_queue *fq = blk_get_flush_queue(q, flush_rq->mq_ctx);
- if (q->mq_ops) {
+ if (!blk_use_sched_path(q)) {
struct blk_mq_hw_ctx *hctx;
/* release the tag's ownership to the req cloned from */
@@ -240,7 +242,7 @@ static void flush_end_io(struct request *flush_rq, int error)
/* account completion of the flush request */
fq->flush_running_idx ^= 1;
- if (!q->mq_ops)
+ if (blk_use_sched_path(q))
elv_completed_request(q, flush_rq);
/* and push the waiting requests to the next stage */
@@ -267,7 +269,7 @@ static void flush_end_io(struct request *flush_rq, int error)
blk_run_queue_async(q);
}
fq->flush_queue_delayed = 0;
- if (q->mq_ops)
+ if (!blk_use_sched_path(q))
spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
}
@@ -315,7 +317,7 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq)
* be in flight at the same time. And acquire the tag's
* ownership for flush req.
*/
- if (q->mq_ops) {
+ if (!blk_use_sched_path(q)) {
struct blk_mq_hw_ctx *hctx;
flush_rq->mq_ctx = first_rq->mq_ctx;
@@ -409,7 +411,7 @@ void blk_insert_flush(struct request *rq)
* complete the request.
*/
if (!policy) {
- if (q->mq_ops)
+ if (!blk_use_sched_path(q))
blk_mq_end_request(rq, 0);
else
__blk_end_bidi_request(rq, 0, 0, 0);
@@ -425,9 +427,9 @@ void blk_insert_flush(struct request *rq)
*/
if ((policy & REQ_FSEQ_DATA) &&
!(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
- if (q->mq_ops) {
+ if (!blk_use_sched_path(q))
blk_mq_insert_request(rq, false, false, true);
- } else
+ else
list_add_tail(&rq->queuelist, &q->queue_head);
return;
}
@@ -440,7 +442,7 @@ void blk_insert_flush(struct request *rq)
INIT_LIST_HEAD(&rq->flush.list);
rq->rq_flags |= RQF_FLUSH_SEQ;
rq->flush.saved_end_io = rq->end_io; /* Usually NULL */
- if (q->mq_ops) {
+ if (!blk_use_sched_path(q)) {
rq->end_io = mq_flush_data_end_io;
spin_lock_irq(&fq->mq_flush_lock);
diff --git a/block/blk.h b/block/blk.h
index 041185e5f129..600e22ea62e9 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -36,10 +36,20 @@ extern struct kmem_cache *request_cachep;
extern struct kobj_type blk_queue_ktype;
extern struct ida blk_queue_ida;
+/*
+ * Use the MQ path if we have mq_ops, but not if we are using an IO
+ * scheduler. For the scheduler, we should use the legacy path. Only
+ * for internal use in the block layer.
+ */
+static inline bool blk_use_sched_path(struct request_queue *q)
+{
+ return !q->mq_ops || q->elevator;
+}
+
static inline struct blk_flush_queue *blk_get_flush_queue(
struct request_queue *q, struct blk_mq_ctx *ctx)
{
- if (q->mq_ops)
+ if (!blk_use_sched_path(q))
return blk_mq_map_queue(q, ctx->cpu)->fq;
return q->fq;
}
--
2.7.4
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