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authorSagi Grimberg <sagi@grimberg.me>2018-11-19 14:11:12 -0800
committerJens Axboe <axboe@kernel.dk>2018-12-07 22:26:57 -0700
commite6a622fd6d66b83779357e3400f487fc159a7d83 (patch)
tree23c128b4f918466bea9dc3c7a2669ea9916ea849 /drivers/nvme
parent6e2e312ea7ff73acfafaa5c9851e151e9483c761 (diff)
nvmet: support fabrics sq flow control
Technical proposal 8005 "fabrics SQ flow control" introduces a mode where a host and controller agree to omit sq_head pointer updates when sending nvme completions. In case the host indicated desire to operate in this mode (connect attribute) the controller will return back a connect completion with sq_head value of 0xffff as indication that it will omit sq_head pointer updates. This mode saves us an atomic update in the I/O path. Reviewed-by: Hannes Reinecke <hare@suse.com> [hch: suggested better implementation] Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/nvme')
-rw-r--r--drivers/nvme/target/core.c23
-rw-r--r--drivers/nvme/target/fabrics-cmd.c6
-rw-r--r--drivers/nvme/target/nvmet.h1
3 files changed, 20 insertions, 10 deletions
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 5aa5a3cc5395..2df70010e9f2 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -597,26 +597,28 @@ struct nvmet_ns *nvmet_ns_alloc(struct nvmet_subsys *subsys, u32 nsid)
return ns;
}
-static void __nvmet_req_complete(struct nvmet_req *req, u16 status)
+static void nvmet_update_sq_head(struct nvmet_req *req)
{
- u32 old_sqhd, new_sqhd;
- u16 sqhd;
-
- if (status)
- nvmet_set_status(req, status);
-
if (req->sq->size) {
+ u32 old_sqhd, new_sqhd;
+
do {
old_sqhd = req->sq->sqhd;
new_sqhd = (old_sqhd + 1) % req->sq->size;
} while (cmpxchg(&req->sq->sqhd, old_sqhd, new_sqhd) !=
old_sqhd);
}
- sqhd = req->sq->sqhd & 0x0000FFFF;
- req->rsp->sq_head = cpu_to_le16(sqhd);
+ req->rsp->sq_head = cpu_to_le16(req->sq->sqhd & 0x0000FFFF);
+}
+
+static void __nvmet_req_complete(struct nvmet_req *req, u16 status)
+{
+ if (!req->sq->sqhd_disabled)
+ nvmet_update_sq_head(req);
req->rsp->sq_id = cpu_to_le16(req->sq->qid);
req->rsp->command_id = req->cmd->common.command_id;
-
+ if (status)
+ nvmet_set_status(req, status);
if (req->ns)
nvmet_put_namespace(req->ns);
req->ops->queue_response(req);
@@ -765,6 +767,7 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
req->sg_cnt = 0;
req->transfer_len = 0;
req->rsp->status = 0;
+ req->rsp->sq_head = 0;
req->ns = NULL;
/* no support for fused commands yet */
diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
index d84ae004cb85..328ae46d8344 100644
--- a/drivers/nvme/target/fabrics-cmd.c
+++ b/drivers/nvme/target/fabrics-cmd.c
@@ -115,6 +115,12 @@ static u16 nvmet_install_queue(struct nvmet_ctrl *ctrl, struct nvmet_req *req)
/* note: convert queue size from 0's-based value to 1's-based value */
nvmet_cq_setup(ctrl, req->cq, qid, sqsize + 1);
nvmet_sq_setup(ctrl, req->sq, qid, sqsize + 1);
+
+ if (c->cattr & NVME_CONNECT_DISABLE_SQFLOW) {
+ req->sq->sqhd_disabled = true;
+ req->rsp->sq_head = cpu_to_le16(0xffff);
+ }
+
return 0;
}
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 03988fe9d915..547108c41ce9 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -106,6 +106,7 @@ struct nvmet_sq {
u16 qid;
u16 size;
u32 sqhd;
+ bool sqhd_disabled;
struct completion free_done;
struct completion confirm_done;
};