[RFC PATCH 3/4] nvme: add async ioctl support

From: Kanchan Joshi
Date: Wed Jan 27 2021 - 10:09:48 EST

Next message: Piotr Figiel: "Re: [PATCH v3] fs/proc: Expose RSEQ configuration"
Previous message: Kanchan Joshi: "[RFC PATCH 4/4] io_uring: add async passthrough ioctl support"
In reply to: Kanchan Joshi: "[RFC PATCH 4/4] io_uring: add async passthrough ioctl support"
Next in thread: Pavel Begunkov: "Re: [RFC PATCH 0/4] Asynchronous passthrough ioctl"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Add async_ioctl handler that implements asynchronous handling of ioctl
operation. If requested ioctl opcode does not involve submitting a
command to device (e.g. NVME_IOCTL_ID), it is made to return instantly.
Otherwise, ioctl-completion is decoupled from submission, and
-EIOCBQUEUED is returned post submission. When completion arrives from
device, nvme calls the ioctl-completion handler supplied by upper-layer.
But there is execption to that. An ioctl completion may also require
updating certain ioctl-specific user buffers/fields which can be
accessed only in context of original submitter-task. For such ioctl,
nvme-completion schedules a task-work which first updates ioctl-specific
buffers/fields and after that invokes the ioctl-completion handler.

Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
---
drivers/nvme/host/core.c | 347 +++++++++++++++++++++++++++++++--------
1 file changed, 280 insertions(+), 67 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 200bdd672c28..57f3040bae34 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -21,6 +21,7 @@
#include <linux/nvme_ioctl.h>
#include <linux/pm_qos.h>
#include <asm/unaligned.h>
+#include <linux/task_work.h>

#include "nvme.h"
#include "fabrics.h"
@@ -1092,7 +1093,107 @@ static void nvme_passthru_end(struct nvme_ctrl *ctrl, u32 effects)
}
}

-void nvme_execute_passthru_rq(struct request *rq)
+struct async_pt_desc {
+ struct bio *bio;
+ int status; /* command status */
+ u64 result; /* nvme cmd result */
+ void __user *res_ptr; /* can be null, 32bit addr or 64 bit addr */
+ void __user *meta_ptr;
+ void *meta; /* kernel-space resident buffer */
+ unsigned metalen; /* length of meta */
+ bool is_res64 : 1; /* res_ptr refers to 64bit of space */
+ bool is_write : 1;
+ bool is_taskwork : 1;
+};
+
+static int nvme_add_task_work(struct task_struct *tsk,
+ struct callback_head *twork,
+ task_work_func_t work_func)
+{
+ int ret;
+
+ get_task_struct(tsk);
+ init_task_work(twork, work_func);
+ ret = task_work_add(tsk, twork, TWA_SIGNAL);
+ if (!ret)
+ wake_up_process(tsk);
+ return ret;
+}
+
+static void async_pt_update_work(struct callback_head *cbh)
+{
+ struct pt_ioctl_ctx *ptioc;
+ struct async_pt_desc *ptd;
+ struct task_struct *tsk;
+ int ret;
+
+ ptioc = container_of(cbh, struct pt_ioctl_ctx, pt_work);
+ ptd = ptioc->ioc_data;
+ tsk = ptioc->task;
+
+ /* handle meta update */
+ if (ptd->meta) {
+ if (!ptd->status && !ptd->is_write)
+ if (copy_to_user(ptd->meta_ptr, ptd->meta, ptd->metalen))
+ ptd->status = -EFAULT;
+ kfree(ptd->meta);
+ }
+ /* handle result update */
+ if (ptd->res_ptr) {
+ if (!ptd->is_res64)
+ ret = put_user(ptd->result, (u32 __user *)ptd->res_ptr);
+ else
+ ret = put_user(ptd->result, (u64 __user *)ptd->res_ptr);
+ if (ret)
+ ptd->status = -EFAULT;
+ }
+
+ ptioc->pt_complete(ptioc, ptd->status);
+ put_task_struct(tsk);
+ kfree(ptd);
+}
+
+static void nvme_end_async_pt(struct request *req, blk_status_t err)
+{
+ struct pt_ioctl_ctx *ptioc;
+ struct async_pt_desc *ptd;
+ struct bio *bio;
+
+ ptioc = req->end_io_data;
+ ptd = ptioc->ioc_data;
+
+ if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
+ ptd->status = -EINTR;
+ else
+ ptd->status = nvme_req(req)->status;
+
+ ptd->result = le64_to_cpu(nvme_req(req)->result.u64);
+ bio = ptd->bio;
+ /* setup task work if needed */
+ if (ptd->is_taskwork) {
+ int ret = nvme_add_task_work(ptioc->task, &ptioc->pt_work,
+ async_pt_update_work);
+ /* update failure if task-work could not be setup */
+ if (ret < 0) {
+ put_task_struct(ptioc->task);
+ ptioc->pt_complete(ptioc, ret);
+ kfree(ptd->meta);
+ kfree(ptd);
+ }
+ } else {
+ /* return status via callback, nothing else to update */
+ ptioc->pt_complete(ptioc, ptd->status);
+ kfree(ptd);
+ }
+
+ /* unmap pages, free bio, nvme command and request */
+ blk_rq_unmap_user(bio);
+ kfree(nvme_req(req)->cmd);
+ blk_mq_free_request(req);
+}
+
+
+void nvme_execute_passthru_rq_common(struct request *rq, int async)
{
struct nvme_command *cmd = nvme_req(rq)->cmd;
struct nvme_ctrl *ctrl = nvme_req(rq)->ctrl;
@@ -1101,15 +1202,52 @@ void nvme_execute_passthru_rq(struct request *rq)
u32 effects;

effects = nvme_passthru_start(ctrl, ns, cmd->common.opcode);
- blk_execute_rq(rq->q, disk, rq, 0);
+ if (!async)
+ blk_execute_rq(rq->q, disk, rq, 0);
+ else
+ blk_execute_rq_nowait(rq->q, disk, rq, 0, nvme_end_async_pt);
nvme_passthru_end(ctrl, effects);
}
+
+void nvme_execute_passthru_rq(struct request *rq)
+{
+ return nvme_execute_passthru_rq_common(rq, 0);
+}
EXPORT_SYMBOL_NS_GPL(nvme_execute_passthru_rq, NVME_TARGET_PASSTHRU);

+static int setup_async_pt_desc(struct request *rq, struct pt_ioctl_ctx *ptioc,
+ void __user *resptr, void __user *meta_buffer, void *meta,
+ unsigned meta_len, bool write, bool is_res64)
+{
+ struct async_pt_desc *ptd;
+
+ ptd = kzalloc(sizeof(struct async_pt_desc), GFP_KERNEL);
+ if (!ptd)
+ return -ENOMEM;
+
+ /* to free bio on completion, as req->bio will be null at that time */
+ ptd->bio = rq->bio;
+ ptd->res_ptr = resptr;
+ ptd->is_write = write;
+ ptd->is_res64 = is_res64;
+ if (meta) {
+ ptd->meta_ptr = meta_buffer;
+ ptd->meta = meta;
+ ptd->metalen = meta_len;
+ }
+ if (resptr)
+ ptd->is_taskwork = 1;
+
+ ptioc->ioc_data = ptd;
+ rq->end_io_data = ptioc;
+ return 0;
+}
+
static int nvme_submit_user_cmd(struct request_queue *q,
struct nvme_command *cmd, void __user *ubuffer,
unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
- u32 meta_seed, u64 *result, unsigned timeout)
+ u32 meta_seed, u64 *result, unsigned timeout,
+ struct pt_ioctl_ctx *ptioc, bool is_res64)
{
bool write = nvme_is_write(cmd);
struct nvme_ns *ns = q->queuedata;
@@ -1145,6 +1283,18 @@ static int nvme_submit_user_cmd(struct request_queue *q,
}
}

+ if (ptioc) { /* async handling */
+ ret = setup_async_pt_desc(req, ptioc, result, meta_buffer,
+ meta, meta_len, write, is_res64);
+ if (ret) {
+ kfree(meta);
+ goto out_unmap;
+ }
+ /* send request for async processing */
+ nvme_execute_passthru_rq_common(req, 1);
+ return ret;
+ }
+ /* sync handling */
nvme_execute_passthru_rq(req);
if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
ret = -EINTR;
@@ -1521,10 +1671,11 @@ static void __user *nvme_to_user_ptr(uintptr_t ptrval)
return (void __user *)ptrval;
}

-static int nvme_submit_io(struct nvme_ns *ns, struct nvme_user_io __user *uio)
+static int nvme_submit_io(struct nvme_ns *ns, struct nvme_user_io __user *uio,
+ struct pt_ioctl_ctx *ptioc)
{
struct nvme_user_io io;
- struct nvme_command c;
+ struct nvme_command c, *cptr;
unsigned length, meta_len;
void __user *metadata;

@@ -1554,31 +1705,42 @@ static int nvme_submit_io(struct nvme_ns *ns, struct nvme_user_io __user *uio)
return -EINVAL;
}

- memset(&c, 0, sizeof(c));
- c.rw.opcode = io.opcode;
- c.rw.flags = io.flags;
- c.rw.nsid = cpu_to_le32(ns->head->ns_id);
- c.rw.slba = cpu_to_le64(io.slba);
- c.rw.length = cpu_to_le16(io.nblocks);
- c.rw.control = cpu_to_le16(io.control);
- c.rw.dsmgmt = cpu_to_le32(io.dsmgmt);
- c.rw.reftag = cpu_to_le32(io.reftag);
- c.rw.apptag = cpu_to_le16(io.apptag);
- c.rw.appmask = cpu_to_le16(io.appmask);
-
- return nvme_submit_user_cmd(ns->queue, &c,
+ if (!ptioc)
+ cptr = &c;
+ else { /* for async - allocate cmd dynamically */
+ cptr = kmalloc(sizeof(struct nvme_command), GFP_KERNEL);
+ if (!cptr)
+ return -ENOMEM;
+ }
+
+ memset(cptr, 0, sizeof(c));
+ cptr->rw.opcode = io.opcode;
+ cptr->rw.flags = io.flags;
+ cptr->rw.nsid = cpu_to_le32(ns->head->ns_id);
+ cptr->rw.slba = cpu_to_le64(io.slba);
+ cptr->rw.length = cpu_to_le16(io.nblocks);
+ cptr->rw.control = cpu_to_le16(io.control);
+ cptr->rw.dsmgmt = cpu_to_le32(io.dsmgmt);
+ cptr->rw.reftag = cpu_to_le32(io.reftag);
+ cptr->rw.apptag = cpu_to_le16(io.apptag);
+ cptr->rw.appmask = cpu_to_le16(io.appmask);
+
+ return nvme_submit_user_cmd(ns->queue, cptr,
nvme_to_user_ptr(io.addr), length,
- metadata, meta_len, lower_32_bits(io.slba), NULL, 0);
+ metadata, meta_len, lower_32_bits(io.slba), NULL, 0,
+ ptioc, 0);
}

static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
- struct nvme_passthru_cmd __user *ucmd)
+ struct nvme_passthru_cmd __user *ucmd,
+ struct pt_ioctl_ctx *ptioc)
{
struct nvme_passthru_cmd cmd;
- struct nvme_command c;
+ struct nvme_command c, *cptr;
unsigned timeout = 0;
u64 result;
int status;
+ void *resptr;

if (!capable(CAP_SYS_ADMIN))
return -EACCES;
@@ -1586,43 +1748,61 @@ static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
return -EFAULT;
if (cmd.flags)
return -EINVAL;
+ if (!ptioc) {
+ cptr = &c;
+ resptr = &result;
+ } else {
+ /*
+ * for async - (a) allocate cmd dynamically
+ * (b) use user-space result addr
+ */
+ cptr = kmalloc(sizeof(struct nvme_command), GFP_KERNEL);
+ if (!cptr)
+ return -ENOMEM;
+ resptr = &ucmd->result;
+ }

- 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);
+ memset(cptr, 0, sizeof(c));
+ cptr->common.opcode = cmd.opcode;
+ cptr->common.flags = cmd.flags;
+ cptr->common.nsid = cpu_to_le32(cmd.nsid);
+ cptr->common.cdw2[0] = cpu_to_le32(cmd.cdw2);
+ cptr->common.cdw2[1] = cpu_to_le32(cmd.cdw3);
+ cptr->common.cdw10 = cpu_to_le32(cmd.cdw10);
+ cptr->common.cdw11 = cpu_to_le32(cmd.cdw11);
+ cptr->common.cdw12 = cpu_to_le32(cmd.cdw12);
+ cptr->common.cdw13 = cpu_to_le32(cmd.cdw13);
+ cptr->common.cdw14 = cpu_to_le32(cmd.cdw14);
+ cptr->common.cdw15 = cpu_to_le32(cmd.cdw15);

if (cmd.timeout_ms)
timeout = msecs_to_jiffies(cmd.timeout_ms);

- status = nvme_submit_user_cmd(ns ? ns->queue : ctrl->admin_q, &c,
+ status = nvme_submit_user_cmd(ns ? ns->queue : ctrl->admin_q, cptr,
nvme_to_user_ptr(cmd.addr), cmd.data_len,
nvme_to_user_ptr(cmd.metadata), cmd.metadata_len,
- 0, &result, timeout);
+ 0, resptr, timeout, ptioc, 0);

- if (status >= 0) {
+ if (!ptioc && status >= 0) {
if (put_user(result, &ucmd->result))
return -EFAULT;
}
+ /* async case, free cmd in case of error */
+ if (ptioc && status < 0)
+ kfree(cptr);

return status;
}

static int nvme_user_cmd64(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
- struct nvme_passthru_cmd64 __user *ucmd)
+ struct nvme_passthru_cmd64 __user *ucmd,
+ struct pt_ioctl_ctx *ptioc)
{
struct nvme_passthru_cmd64 cmd;
- struct nvme_command c;
+ struct nvme_command c, *cptr;
unsigned timeout = 0;
int status;
+ void *resptr;

if (!capable(CAP_SYS_ADMIN))
return -EACCES;
@@ -1631,31 +1811,43 @@ static int nvme_user_cmd64(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
if (cmd.flags)
return -EINVAL;

- 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);
+ if (!ptioc) {
+ cptr = &c;
+ resptr = &cmd.result;
+ } else {
+ cptr = kmalloc(sizeof(struct nvme_command), GFP_KERNEL);
+ if (!cptr)
+ return -ENOMEM;
+ resptr = &ucmd->result;
+ }
+
+ memset(cptr, 0, sizeof(struct nvme_command));
+ cptr->common.opcode = cmd.opcode;
+ cptr->common.flags = cmd.flags;
+ cptr->common.nsid = cpu_to_le32(cmd.nsid);
+ cptr->common.cdw2[0] = cpu_to_le32(cmd.cdw2);
+ cptr->common.cdw2[1] = cpu_to_le32(cmd.cdw3);
+ cptr->common.cdw10 = cpu_to_le32(cmd.cdw10);
+ cptr->common.cdw11 = cpu_to_le32(cmd.cdw11);
+ cptr->common.cdw12 = cpu_to_le32(cmd.cdw12);
+ cptr->common.cdw13 = cpu_to_le32(cmd.cdw13);
+ cptr->common.cdw14 = cpu_to_le32(cmd.cdw14);
+ cptr->common.cdw15 = cpu_to_le32(cmd.cdw15);

if (cmd.timeout_ms)
timeout = msecs_to_jiffies(cmd.timeout_ms);

- status = nvme_submit_user_cmd(ns ? ns->queue : ctrl->admin_q, &c,
+ status = nvme_submit_user_cmd(ns ? ns->queue : ctrl->admin_q, cptr,
nvme_to_user_ptr(cmd.addr), cmd.data_len,
nvme_to_user_ptr(cmd.metadata), cmd.metadata_len,
- 0, &cmd.result, timeout);
+ 0, resptr, timeout, ptioc, 1);

- if (status >= 0) {
+ if (!ptioc && status >= 0) {
if (put_user(cmd.result, &ucmd->result))
return -EFAULT;
}
+ if (ptioc && status < 0)
+ kfree(cptr);

return status;
}
@@ -1702,7 +1894,8 @@ static bool is_ctrl_ioctl(unsigned int cmd)
static int nvme_handle_ctrl_ioctl(struct nvme_ns *ns, unsigned int cmd,
void __user *argp,
struct nvme_ns_head *head,
- int srcu_idx)
+ int srcu_idx,
+ struct pt_ioctl_ctx *ptioc)
{
struct nvme_ctrl *ctrl = ns->ctrl;
int ret;
@@ -1712,21 +1905,24 @@ static int nvme_handle_ctrl_ioctl(struct nvme_ns *ns, unsigned int cmd,

switch (cmd) {
case NVME_IOCTL_ADMIN_CMD:
- ret = nvme_user_cmd(ctrl, NULL, argp);
+ ret = nvme_user_cmd(ctrl, NULL, argp, ptioc);
break;
case NVME_IOCTL_ADMIN64_CMD:
- ret = nvme_user_cmd64(ctrl, NULL, argp);
+ ret = nvme_user_cmd64(ctrl, NULL, argp, ptioc);
break;
default:
- ret = sed_ioctl(ctrl->opal_dev, cmd, argp);
+ if (!ptioc)
+ ret = sed_ioctl(ctrl->opal_dev, cmd, argp);
+ else
+ ret = -EOPNOTSUPP; /* RFP: no support for now */
break;
}
nvme_put_ctrl(ctrl);
return ret;
}

-static int nvme_ioctl(struct block_device *bdev, fmode_t mode,
- unsigned int cmd, unsigned long arg)
+static int nvme_async_ioctl(struct block_device *bdev, fmode_t mode,
+ unsigned int cmd, unsigned long arg, struct pt_ioctl_ctx *ptioc)
{
struct nvme_ns_head *head = NULL;
void __user *argp = (void __user *)arg;
@@ -1743,33 +1939,49 @@ static int nvme_ioctl(struct block_device *bdev, fmode_t mode,
* deadlock when deleting namespaces using the passthrough interface.
*/
if (is_ctrl_ioctl(cmd))
- return nvme_handle_ctrl_ioctl(ns, cmd, argp, head, srcu_idx);
+ return nvme_handle_ctrl_ioctl(ns, cmd, argp, head, srcu_idx, ptioc);

switch (cmd) {
case NVME_IOCTL_ID:
force_successful_syscall_return();
ret = ns->head->ns_id;
+ if (ptioc)
+ goto put_ns; /* return in sync fashion always */
break;
case NVME_IOCTL_IO_CMD:
- ret = nvme_user_cmd(ns->ctrl, ns, argp);
+ ret = nvme_user_cmd(ns->ctrl, ns, argp, ptioc);
break;
case NVME_IOCTL_SUBMIT_IO:
- ret = nvme_submit_io(ns, argp);
+ ret = nvme_submit_io(ns, argp, ptioc);
break;
case NVME_IOCTL_IO64_CMD:
- ret = nvme_user_cmd64(ns->ctrl, ns, argp);
+ ret = nvme_user_cmd64(ns->ctrl, ns, argp, ptioc);
break;
default:
+ if (ptioc) {
+ /* RFP- don't support this for now */
+ ret = -EOPNOTSUPP;
+ break;
+ }
if (ns->ndev)
ret = nvme_nvm_ioctl(ns, cmd, arg);
else
ret = -ENOTTY;
}
-
+ /* if there is no error, return queued for async-ioctl */
+ if (ptioc && ret >= 0)
+ ret = -EIOCBQUEUED;
+ put_ns:
nvme_put_ns_from_disk(head, srcu_idx);
return ret;
}

+static int nvme_ioctl(struct block_device *bdev, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ return nvme_async_ioctl(bdev, mode, cmd, arg, NULL);
+}
+
#ifdef CONFIG_COMPAT
struct nvme_user_io32 {
__u8 opcode;
@@ -2324,6 +2536,7 @@ EXPORT_SYMBOL_GPL(nvme_sec_submit);
static const struct block_device_operations nvme_bdev_ops = {
.owner = THIS_MODULE,
.ioctl = nvme_ioctl,
+ .async_ioctl = nvme_async_ioctl,
.compat_ioctl = nvme_compat_ioctl,
.open = nvme_open,
.release = nvme_release,
@@ -3261,7 +3474,7 @@ static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp)
kref_get(&ns->kref);
up_read(&ctrl->namespaces_rwsem);

- ret = nvme_user_cmd(ctrl, ns, argp);
+ ret = nvme_user_cmd(ctrl, ns, argp, NULL);
nvme_put_ns(ns);
return ret;

@@ -3278,9 +3491,9 @@ static long nvme_dev_ioctl(struct file *file, unsigned int cmd,

switch (cmd) {
case NVME_IOCTL_ADMIN_CMD:
- return nvme_user_cmd(ctrl, NULL, argp);
+ return nvme_user_cmd(ctrl, NULL, argp, NULL);
case NVME_IOCTL_ADMIN64_CMD:
- return nvme_user_cmd64(ctrl, NULL, argp);
+ return nvme_user_cmd64(ctrl, NULL, argp, NULL);
case NVME_IOCTL_IO_CMD:
return nvme_dev_user_cmd(ctrl, argp);
case NVME_IOCTL_RESET:
--
2.25.1

Next message: Piotr Figiel: "Re: [PATCH v3] fs/proc: Expose RSEQ configuration"
Previous message: Kanchan Joshi: "[RFC PATCH 4/4] io_uring: add async passthrough ioctl support"
In reply to: Kanchan Joshi: "[RFC PATCH 4/4] io_uring: add async passthrough ioctl support"
Next in thread: Pavel Begunkov: "Re: [RFC PATCH 0/4] Asynchronous passthrough ioctl"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]