[PATCH v8 04/10] nvme-multipath: pass I/O type to nvme_find_path()
Nilay Shroff
nilay at linux.ibm.com
Sat Aug 15 10:34:26 PDT 2026
Currently, nvme_find_path() only accepts an nvme_ns_head argument.
However, the upcoming latency-aware I/O policy also needs to know
the I/O type (read/write/other) associated with the request in order
to make path selection decisions.
Update nvme_find_path() to accept an additional argument describing
the I/O type. Classify requests into three categories: READ, WRITE,
and OTHER. Admin commands and I/O requests that are neither reads nor
writes are classified as OTHER.
This patch does not introduce any functional change and only prepares
the interface for subsequent latency-policy changes.
Reviewed-by: Guixin Liu <kanie at linux.alibaba.com>
Reviewed-by: Hannes Reinecke <hare at suse.de>
Signed-off-by: Nilay Shroff <nilay at linux.ibm.com>
---
drivers/nvme/host/ioctl.c | 44 +++++++++++++++++++++++++++---
drivers/nvme/host/multipath.c | 9 ++++---
drivers/nvme/host/nvme.h | 50 ++++++++++++++++++++++++++++++++++-
drivers/nvme/host/pr.c | 6 +++--
drivers/nvme/host/sysfs.c | 2 +-
5 files changed, 100 insertions(+), 11 deletions(-)
diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 6539d4750098..b0538ed2adbc 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -751,12 +751,25 @@ int nvme_ns_head_ioctl(struct block_device *bdev, blk_mode_t mode,
struct nvme_ns *ns;
int srcu_idx, ret = -EWOULDBLOCK;
unsigned int flags = 0;
+ unsigned int op_type = NVME_STAT_GROUP_OTHER;
if (bdev_is_partition(bdev))
flags |= NVME_IOCTL_PARTITION;
+ if (cmd == NVME_IOCTL_SUBMIT_IO) {
+ u8 opcode;
+
+ if (get_user(opcode, (u8 *)argp))
+ return -EFAULT;
+
+ if (opcode == nvme_cmd_write)
+ op_type = NVME_STAT_GROUP_WRITE;
+ else if (opcode == nvme_cmd_read)
+ op_type = NVME_STAT_GROUP_READ;
+ }
+
srcu_idx = srcu_read_lock(&head->srcu);
- ns = nvme_find_path(head);
+ ns = nvme_find_path(head, op_type);
if (!ns)
goto out_unlock;
@@ -785,9 +798,22 @@ long nvme_ns_head_chr_ioctl(struct file *file, unsigned int cmd,
void __user *argp = (void __user *)arg;
struct nvme_ns *ns;
int srcu_idx, ret = -EWOULDBLOCK;
+ unsigned int op_type = NVME_STAT_GROUP_OTHER;
+
+ if (cmd == NVME_IOCTL_SUBMIT_IO) {
+ u8 opcode;
+
+ if (get_user(opcode, (u8 *)argp))
+ return -EFAULT;
+
+ if (opcode == nvme_cmd_write)
+ op_type = NVME_STAT_GROUP_WRITE;
+ else if (opcode == nvme_cmd_read)
+ op_type = NVME_STAT_GROUP_READ;
+ }
srcu_idx = srcu_read_lock(&head->srcu);
- ns = nvme_find_path(head);
+ ns = nvme_find_path(head, op_type);
if (!ns)
goto out_unlock;
@@ -804,12 +830,24 @@ long nvme_ns_head_chr_ioctl(struct file *file, unsigned int cmd,
int nvme_ns_head_chr_uring_cmd(struct io_uring_cmd *ioucmd,
unsigned int issue_flags)
{
+ struct nvme_ns *ns;
+ unsigned int op_type;
struct cdev *cdev = file_inode(ioucmd->file)->i_cdev;
struct nvme_ns_head *head = container_of(cdev, struct nvme_ns_head, cdev);
int srcu_idx = srcu_read_lock(&head->srcu);
- struct nvme_ns *ns = nvme_find_path(head);
int ret = -EINVAL;
+ const struct nvme_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe,
+ struct nvme_uring_cmd);
+ __u8 opcode = READ_ONCE(cmd->opcode);
+
+ if (opcode == nvme_cmd_write)
+ op_type = NVME_STAT_GROUP_WRITE;
+ else if (opcode == nvme_cmd_read)
+ op_type = NVME_STAT_GROUP_READ;
+ else
+ op_type = NVME_STAT_GROUP_OTHER;
+ ns = nvme_find_path(head, op_type);
if (ns)
ret = nvme_ns_uring_cmd(ns, ioucmd, issue_flags);
srcu_read_unlock(&head->srcu, srcu_idx);
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 75dbb58286a3..95768eaef843 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -484,7 +484,8 @@ static struct nvme_ns *nvme_numa_path(struct nvme_ns_head *head)
return ns;
}
-inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
+inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head,
+ enum nvme_stat_group op_type)
{
switch (READ_ONCE(head->subsys->iopolicy)) {
case NVME_IOPOLICY_QD:
@@ -547,7 +548,7 @@ static void nvme_ns_head_submit_bio(struct bio *bio)
return;
srcu_idx = srcu_read_lock(&head->srcu);
- ns = nvme_find_path(head);
+ ns = nvme_find_path(head, __nvme_get_stat_group(bio_op(bio)));
if (likely(ns)) {
bio_set_dev(bio, ns->disk->part0);
/*
@@ -597,7 +598,7 @@ static int nvme_ns_head_get_unique_id(struct gendisk *disk, u8 id[16],
int srcu_idx, ret = -EWOULDBLOCK;
srcu_idx = srcu_read_lock(&head->srcu);
- ns = nvme_find_path(head);
+ ns = nvme_find_path(head, NVME_STAT_GROUP_OTHER);
if (ns)
ret = nvme_ns_get_unique_id(ns, id, type);
srcu_read_unlock(&head->srcu, srcu_idx);
@@ -613,7 +614,7 @@ static int nvme_ns_head_report_zones(struct gendisk *disk, sector_t sector,
int srcu_idx, ret = -EWOULDBLOCK;
srcu_idx = srcu_read_lock(&head->srcu);
- ns = nvme_find_path(head);
+ ns = nvme_find_path(head, NVME_STAT_GROUP_OTHER);
if (ns)
ret = nvme_ns_report_zones(ns, sector, nr_zones, args);
srcu_read_unlock(&head->srcu, srcu_idx);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 75e5d5a8a77c..5af272cf2f49 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -531,6 +531,20 @@ struct nvme_ns_ids {
u8 csi;
};
+/*
+ * Enum used to classify NVMe I/O type into a stat group. Read and write
+ * I/Os are classified as NVME_STAT_GROUP_READ and NVME_STAT_GROUP_WRITE
+ * respectively; all other I/Os or admin commands are classified as
+ * NVME_STAT_GROUP_OTHER.
+ */
+enum nvme_stat_group {
+ NVME_STAT_GROUP_READ,
+ NVME_STAT_GROUP_WRITE,
+ NVME_STAT_GROUP_OTHER,
+
+ NVME_NUM_STAT_GROUPS
+};
+
/*
* Anchor structure for namespaces. There is one for each namespace in a
* NVMe subsystem that any of our controllers can see, and the namespace
@@ -1046,8 +1060,42 @@ extern const struct attribute_group *nvme_dev_attr_groups[];
extern const struct block_device_operations nvme_bdev_ops;
void nvme_delete_ctrl_sync(struct nvme_ctrl *ctrl);
-struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
+struct nvme_ns *nvme_find_path(struct nvme_ns_head *head,
+ enum nvme_stat_group op_type)
__must_hold_shared(&head->srcu);
+
+static inline enum nvme_stat_group __nvme_get_stat_group(const enum req_op op)
+{
+ if (op == REQ_OP_READ)
+ return NVME_STAT_GROUP_READ;
+ else if (op == REQ_OP_WRITE)
+ return NVME_STAT_GROUP_WRITE;
+ else
+ return NVME_STAT_GROUP_OTHER;
+}
+
+static inline enum nvme_stat_group __nvme_get_passthru_stat_group(
+ enum nvme_opcode op)
+{
+ if (op == nvme_cmd_read)
+ return NVME_STAT_GROUP_READ;
+ else if (op == nvme_cmd_write)
+ return NVME_STAT_GROUP_WRITE;
+ else
+ return NVME_STAT_GROUP_OTHER;
+}
+
+static inline enum nvme_stat_group nvme_get_stat_group(struct request *req)
+{
+ if (blk_rq_is_passthrough(req)) {
+ struct nvme_request *nr = nvme_req(req);
+
+ return __nvme_get_passthru_stat_group(nr->cmd->common.opcode);
+ }
+
+ return __nvme_get_stat_group(req_op(req));
+}
+
#ifdef CONFIG_NVME_MULTIPATH
static inline bool nvme_ctrl_use_ana(struct nvme_ctrl *ctrl)
{
diff --git a/drivers/nvme/host/pr.c b/drivers/nvme/host/pr.c
index fe7dbe264815..715e6c242bd1 100644
--- a/drivers/nvme/host/pr.c
+++ b/drivers/nvme/host/pr.c
@@ -53,10 +53,12 @@ static int nvme_send_ns_head_pr_command(struct block_device *bdev,
struct nvme_command *c, void *data, unsigned int data_len)
{
struct nvme_ns_head *head = bdev->bd_disk->private_data;
- int srcu_idx = srcu_read_lock(&head->srcu);
- struct nvme_ns *ns = nvme_find_path(head);
+ int srcu_idx;
+ struct nvme_ns *ns;
int ret = -EWOULDBLOCK;
+ srcu_idx = srcu_read_lock(&head->srcu);
+ ns = nvme_find_path(head, NVME_STAT_GROUP_OTHER);
if (ns) {
c->common.nsid = cpu_to_le32(ns->head->ns_id);
ret = nvme_submit_sync_cmd(ns->queue, c, data, data_len);
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index abf8edaae371..e95543fecb2a 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -195,7 +195,7 @@ static int ns_head_update_nuse(struct nvme_ns_head *head)
return 0;
srcu_idx = srcu_read_lock(&head->srcu);
- ns = nvme_find_path(head);
+ ns = nvme_find_path(head, NVME_STAT_GROUP_OTHER);
if (!ns)
goto out_unlock;
--
2.53.0
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