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From: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
To: linux-nvme@lists.infradead.org
Cc: kbusch@kernel.org, hch@lst.de,
	Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
	sagi@grimberg.me
Subject: [PATCH 12/14] nvme-core: don't check nvme_req flags for new req
Date: Tue, 16 Feb 2021 16:10:30 -0800	[thread overview]
Message-ID: <20210217001032.25741-13-chaitanya.kulkarni@wdc.com> (raw)
In-Reply-To: <20210217001032.25741-1-chaitanya.kulkarni@wdc.com>

nvme_clear_request() has a check for flag REQ_DONTPREP and it is called
from nvme_init_request() and nvme_setuo_cmd().

The function nvme_init_request() is called from nvme_alloc_request()
and nvme_alloc_request_qid(). From these two callers new request is
allocated everytime. For newly allocated request RQF_DONTPREP is never
set. Since after getting a tag, block layer sets the req->rq_flags == 0
and never sets the REQ_DONTPREP when returning the request :-

nvme_alloc_request()
	blk_mq_alloc_request()
		blk_mq_rq_ctx_init()
			rq->rq_flags = 0 <----

nvme_alloc_request_qid()
	blk_mq_alloc_request_hctx()
		blk_mq_rq_ctx_init()
			rq->rq_flags = 0 <----

The block layer does set req->rq_flags but REQ_DONTPREP is not one of
them and that is set by the driver.

That means we can unconditinally set the REQ_DONTPREP value to the
rq->rq_flags when nvme_init_request()->nvme_clear_request() is called
from above two callers.

Move the check for REQ_DONTPREP from nvme_clear_nvme_request() into
nvme_setup_cmd().

This is needed since nvme_alloc_request() now gets called from fast
path when NVMeOF target is configured with passthru backend to avoid
unnecessary checks in the fast path.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 drivers/nvme/host/core.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a0d0c3a5abff..608462df2c39 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -637,11 +637,9 @@ EXPORT_SYMBOL_NS_GPL(nvme_put_ns, NVME_TARGET_PASSTHRU);
 
 static inline void nvme_clear_nvme_request(struct request *req)
 {
-	if (!(req->rq_flags & RQF_DONTPREP)) {
-		nvme_req(req)->retries = 0;
-		nvme_req(req)->flags = 0;
-		req->rq_flags |= RQF_DONTPREP;
-	}
+	nvme_req(req)->retries = 0;
+	nvme_req(req)->flags = 0;
+	req->rq_flags |= RQF_DONTPREP;
 }
 
 static inline unsigned int nvme_req_op(struct nvme_command *cmd)
@@ -943,7 +941,8 @@ blk_status_t nvme_setup_cmd(struct nvme_ns *ns, struct request *req,
 {
 	blk_status_t ret = BLK_STS_OK;
 
-	nvme_clear_nvme_request(req);
+	if (!(req->rq_flags & RQF_DONTPREP))
+		nvme_clear_nvme_request(req);
 
 	memset(cmd, 0, sizeof(*cmd));
 	switch (req_op(req)) {
-- 
2.22.1


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  parent reply	other threads:[~2021-02-17  0:12 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-17  0:10 [PATCH 00/14] nvme: few cleanups and small improvements Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 01/14] nvme-core: remove duplicate kfree in init identify Chaitanya Kulkarni
2021-02-24 16:35   ` Christoph Hellwig
2021-02-24 22:35     ` Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 02/14] nvme-core: don't use switch for only one case use Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 03/14] nvme-core: use right type for ARRAY_SIZE check Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 04/14] nvme-core: fix the type for shutdown_timeout Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 05/14] nvme-core: add helper to init ctrl transport attr Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 06/14] nvme-core: add helper to init shutdown timeout Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 07/14] nvme-core: add helper to init ctrl subsys quirk Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 08/14] nvme-core: move util quirk at the top of the file Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 09/14] nvme-core: mark nvme_setup_passsthru() inline Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 10/14] nvme-core: remove one liner wrappers for streams Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 11/14] nvme-core: use likely in nvme_init_request() Chaitanya Kulkarni
2021-02-17  0:10 ` Chaitanya Kulkarni [this message]
2021-02-17  0:10 ` [PATCH 13/14] nvme-fc: fix the function documentation comment Chaitanya Kulkarni
2021-02-17  0:10 ` [PATCH 14/14] nvmet-fc: update function documentation Chaitanya Kulkarni
2021-02-24 15:42 ` [PATCH 00/14] nvme: few cleanups and small improvements Keith Busch
2021-02-24 21:52   ` Chaitanya Kulkarni

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