[PATCH v4 4/5] nvme: wire-up uring-cmd support for io-passthru on char-device.

Kanchan Joshi
2022-05-05T06:15:04Z

Introduce handler for fops->uring_cmd(), implementing async passthru
on char device (/dev/ngX). The handler supports newly introduced
operation NVME_URING_CMD_IO. This operates on a new structure
nvme_uring_cmd, which is similar to struct nvme_passthru_cmd64 but
without the embedded 8b result field. This field is not needed since
uring-cmd allows to return additional result via big-CQE.

Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
drivers/nvme/host/core.c | 1 +
drivers/nvme/host/ioctl.c | 168 +++++++++++++++++++++++++++++++-
drivers/nvme/host/multipath.c | 1 +
drivers/nvme/host/nvme.h | 5 +
include/uapi/linux/nvme_ioctl.h | 25 +++++
5 files changed, 197 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index e1846d04817f..682df98db341 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3699,6 +3699,7 @@ static const struct file_operations nvme_ns_chr_fops = {
.release = nvme_ns_chr_release,
.unlocked_ioctl = nvme_ns_chr_ioctl,
.compat_ioctl = compat_ptr_ioctl,
+ .uring_cmd = nvme_ns_chr_uring_cmd,
};

static int nvme_add_ns_cdev(struct nvme_ns *ns)
diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 3531de8073a6..3687cb8d7428 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -26,6 +26,80 @@ static inline void *nvme_meta_from_bio(struct bio *bio)
return bip ? bvec_virt(bip->bip_vec) : NULL;
}

+/*
+ * This overlays struct io_uring_cmd pdu.
+ * Expect build errors if this grows larger than that.
+ */
+struct nvme_uring_cmd_pdu {
+ union {
+ struct bio *bio;
+ struct request *req;
+ };
+ void *meta; /* kernel-resident buffer */
+ void __user *meta_buffer;
+ u32 meta_len;
+};
+
+static inline struct nvme_uring_cmd_pdu *nvme_uring_cmd_pdu(
+ struct io_uring_cmd *ioucmd)
+{
+ return (struct nvme_uring_cmd_pdu *)&ioucmd->pdu;
+}
+
+static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd)
+{
+ struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
+ struct request *req = pdu->req;
+ struct bio *bio = req->bio;
+ bool write = req_op(req) == REQ_OP_DRV_OUT;
+ int status;
+ u64 result;
+
+ if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
+ status = -EINTR;
+ else
+ status = nvme_req(req)->status;
+
+ result = le64_to_cpu(nvme_req(req)->result.u64);
+ blk_mq_free_request(req);
+ if (bio)
+ blk_rq_unmap_user(bio);
+
+ if (pdu->meta && !status && !write) {
+ if (copy_to_user(pdu->meta_buffer, pdu->meta, pdu->meta_len))
+ status = -EFAULT;
+ }
+ kfree(pdu->meta);
+ io_uring_cmd_done(ioucmd, status, result);
+}
+
+static void nvme_end_async_pt(struct request *req, blk_status_t err)
+{
+ struct io_uring_cmd *ioucmd = req->end_io_data;
+ struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
+ /* extract bio before reusing the same field for request */
+ struct bio *bio = pdu->bio;
+
+ pdu->req = req;
+ req->bio = bio;
+ /* this takes care of moving rest of completion-work to task context */
+ io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_cb);
+}
+
+static void nvme_setup_uring_cmd_data(struct request *rq,
+ struct io_uring_cmd *ioucmd, void __user *meta_buffer,
+ u32 meta_len)
+{
+ struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
+
+ /* to free bio on completion, as req->bio will be null at that time */
+ pdu->bio = rq->bio;
+ pdu->meta = nvme_meta_from_bio(rq->bio);
+ pdu->meta_buffer = meta_buffer;
+ pdu->meta_len = meta_len;
+ rq->end_io_data = ioucmd;
+}
+
static void *nvme_add_user_metadata(struct bio *bio, void __user *ubuf,
unsigned len, u32 seed, bool write)
{
@@ -63,7 +137,8 @@ static void *nvme_add_user_metadata(struct bio *bio, void __user *ubuf,
static struct request *nvme_alloc_user_request(struct request_queue *q,
struct nvme_command *cmd, void __user *ubuffer,
unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
- u32 meta_seed, unsigned timeout, bool vec)
+ u32 meta_seed, unsigned timeout, bool vec, unsigned int rq_flags,
+ blk_mq_req_flags_t blk_flags)
{
bool write = nvme_is_write(cmd);
struct nvme_ns *ns = q->queuedata;
@@ -73,7 +148,7 @@ static struct request *nvme_alloc_user_request(struct request_queue *q,
void *meta = NULL;
int ret;

- req = blk_mq_alloc_request(q, nvme_req_op(cmd), 0);
+ req = blk_mq_alloc_request(q, nvme_req_op(cmd) | rq_flags, blk_flags);
if (IS_ERR(req))
return req;
nvme_init_request(req, cmd);
@@ -156,7 +231,7 @@ static int nvme_submit_user_cmd(struct request_queue *q,
struct request *req;

req = nvme_alloc_user_request(q, cmd, ubuffer, bufflen, meta_buffer,
- meta_len, meta_seed, timeout, vec);
+ meta_len, meta_seed, timeout, vec, 0, 0);
if (IS_ERR(req))
return PTR_ERR(req);
return nvme_execute_user_rq(req, meta_buffer, meta_len, result);
@@ -333,6 +408,55 @@ static int nvme_user_cmd64(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
return status;
}

+static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
+ struct io_uring_cmd *ioucmd, unsigned int issue_flags)
+{
+ struct nvme_uring_cmd *cmd =
+ (struct nvme_uring_cmd *)ioucmd->cmd;
+ struct request_queue *q = ns ? ns->queue : ctrl->admin_q;
+ struct nvme_command c;
+ struct request *req;
+ unsigned int rq_flags = 0;
+ blk_mq_req_flags_t blk_flags = 0;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EACCES;
+ if (cmd->flags)
+ return -EINVAL;
+ if (!nvme_validate_passthru_nsid(ctrl, ns, cmd->nsid))
+ return -EINVAL;
+
+ if (issue_flags & IO_URING_F_NONBLOCK) {
+ rq_flags = REQ_NOWAIT;
+ blk_flags = BLK_MQ_REQ_NOWAIT;
+ }
+ memset(&c, 0, sizeof(c));
+ c.common.opcode = cmd->opcode;
+ c.common.flags = cmd->flags;
+ c.common.nsid = cpu_to_le32(cmd->nsid);
+ c.common.cdw2[0] = cpu_to_le32(cmd->cdw2);
+ c.common.cdw2[1] = cpu_to_le32(cmd->cdw3);
+ c.common.cdw10 = cpu_to_le32(cmd->cdw10);
+ c.common.cdw11 = cpu_to_le32(cmd->cdw11);
+ c.common.cdw12 = cpu_to_le32(cmd->cdw12);
+ c.common.cdw13 = cpu_to_le32(cmd->cdw13);
+ c.common.cdw14 = cpu_to_le32(cmd->cdw14);
+ c.common.cdw15 = cpu_to_le32(cmd->cdw15);
+
+ req = nvme_alloc_user_request(q, &c, nvme_to_user_ptr(cmd->addr),
+ cmd->data_len, nvme_to_user_ptr(cmd->metadata),
+ cmd->metadata_len, 0, cmd->timeout_ms ?
+ msecs_to_jiffies(cmd->timeout_ms) : 0, 0, rq_flags,
+ blk_flags);
+ if (IS_ERR(req))
+ return PTR_ERR(req);
+
+ nvme_setup_uring_cmd_data(req, ioucmd, nvme_to_user_ptr(cmd->metadata),
+ cmd->metadata_len);
+ blk_execute_rq_nowait(req, 0, nvme_end_async_pt);
+ return -EIOCBQUEUED;
+}
+
static bool is_ctrl_ioctl(unsigned int cmd)
{
if (cmd == NVME_IOCTL_ADMIN_CMD || cmd == NVME_IOCTL_ADMIN64_CMD)
@@ -424,6 +548,32 @@ long nvme_ns_chr_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
return __nvme_ioctl(ns, cmd, (void __user *)arg);
}

+static void nvme_ns_uring_cmd(struct nvme_ns *ns, struct io_uring_cmd *ioucmd,
+ unsigned int issue_flags)
+{
+ int ret;
+
+ BUILD_BUG_ON(sizeof(struct nvme_uring_cmd_pdu) > sizeof(ioucmd->pdu));
+
+ switch (ioucmd->cmd_op) {
+ case NVME_URING_CMD_IO:
+ ret = nvme_uring_cmd_io(ns->ctrl, ns, ioucmd, issue_flags);
+ break;
+ default:
+ ret = -ENOTTY;
+ }
+
+ if (ret != -EIOCBQUEUED)
+ io_uring_cmd_done(ioucmd, ret, 0);
+}
+
+void nvme_ns_chr_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
+{
+ struct nvme_ns *ns = container_of(file_inode(ioucmd->file)->i_cdev,
+ struct nvme_ns, cdev);
+ nvme_ns_uring_cmd(ns, ioucmd, issue_flags);
+}
+
#ifdef CONFIG_NVME_MULTIPATH
static int nvme_ns_head_ctrl_ioctl(struct nvme_ns *ns, unsigned int cmd,
void __user *argp, struct nvme_ns_head *head, int srcu_idx)
@@ -490,6 +640,18 @@ long nvme_ns_head_chr_ioctl(struct file *file, unsigned int cmd,
srcu_read_unlock(&head->srcu, srcu_idx);
return ret;
}
+void nvme_ns_head_chr_uring_cmd(struct io_uring_cmd *ioucmd,
+ unsigned int issue_flags)
+{
+ 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);
+
+ if (ns)
+ nvme_ns_uring_cmd(ns, ioucmd, issue_flags);
+ srcu_read_unlock(&head->srcu, srcu_idx);
+}
#endif /* CONFIG_NVME_MULTIPATH */

static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index d464fdf978fb..d3e2440d8abb 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -437,6 +437,7 @@ static const struct file_operations nvme_ns_head_chr_fops = {
.release = nvme_ns_head_chr_release,
.unlocked_ioctl = nvme_ns_head_chr_ioctl,
.compat_ioctl = compat_ptr_ioctl,
+ .uring_cmd = nvme_ns_head_chr_uring_cmd,
};

static int nvme_add_ns_head_cdev(struct nvme_ns_head *head)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index a2b53ca63335..761ad6c629c4 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -16,6 +16,7 @@
#include <linux/rcupdate.h>
#include <linux/wait.h>
#include <linux/t10-pi.h>
+#include <linux/io_uring.h>

#include <trace/events/block.h>

@@ -782,6 +783,10 @@ long nvme_ns_head_chr_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
long nvme_dev_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
+void nvme_ns_chr_uring_cmd(struct io_uring_cmd *ioucmd,
+ unsigned int issue_flags);
+void nvme_ns_head_chr_uring_cmd(struct io_uring_cmd *ioucmd,
+ unsigned int issue_flags);
int nvme_getgeo(struct block_device *bdev, struct hd_geometry *geo);

extern const struct attribute_group *nvme_ns_id_attr_groups[];
diff --git a/include/uapi/linux/nvme_ioctl.h b/include/uapi/linux/nvme_ioctl.h
index b2e43185e3b5..04e458c649ab 100644
--- a/include/uapi/linux/nvme_ioctl.h
+++ b/include/uapi/linux/nvme_ioctl.h
@@ -70,6 +70,28 @@ struct nvme_passthru_cmd64 {
__u64 result;
};

+/* same as struct nvme_passthru_cmd64, minus the 8b result field */
+struct nvme_uring_cmd {
+ __u8 opcode;
+ __u8 flags;
+ __u16 rsvd1;
+ __u32 nsid;
+ __u32 cdw2;
+ __u32 cdw3;
+ __u64 metadata;
+ __u64 addr;
+ __u32 metadata_len;
+ __u32 data_len;
+ __u32 cdw10;
+ __u32 cdw11;
+ __u32 cdw12;
+ __u32 cdw13;
+ __u32 cdw14;
+ __u32 cdw15;
+ __u32 timeout_ms;
+ __u32 rsvd2;
+};
+
#define nvme_admin_cmd nvme_passthru_cmd

#define NVME_IOCTL_ID _IO('N', 0x40)
@@ -83,4 +105,7 @@ struct nvme_passthru_cmd64 {
#define NVME_IOCTL_IO64_CMD _IOWR('N', 0x48, struct nvme_passthru_cmd64)
#define NVME_IOCTL_IO64_CMD_VEC _IOWR('N', 0x49, struct nvme_passthru_cmd64)

+/* io_uring async commands: */
+#define NVME_URING_CMD_IO _IOWR('N', 0x80, struct nvme_uring_cmd)
+
#endif /* _UAPI_LINUX_NVME_IOCTL_H */
--
2.25.1