[PATCH RFC v7 11/16] fuse: {uring} Allow to queue fg requests through io-uring

Bernd Schubert
2024-11-27T13:41:00Z

This prepares queueing and sending foreground requests through
io-uring.

Signed-off-by: Bernd Schubert <bschubert@ddn.com>
---
fs/fuse/dev.c | 5 +-
fs/fuse/dev_uring.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/dev_uring_i.h | 8 +++
fs/fuse/fuse_dev_i.h | 5 ++
4 files changed, 175 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index ed85a5f2d6c360b8401b174bc97cc135d87e90d9..c53deb690cc9c7958741cd144fcad166b5721e11 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -237,7 +237,8 @@ __releases(fiq->lock)
spin_unlock(&fiq->lock);
}

-static void fuse_dev_queue_forget(struct fuse_iqueue *fiq, struct fuse_forget_link *forget)
+void fuse_dev_queue_forget(struct fuse_iqueue *fiq,
+ struct fuse_forget_link *forget)
{
spin_lock(&fiq->lock);
if (fiq->connected) {
@@ -250,7 +251,7 @@ static void fuse_dev_queue_forget(struct fuse_iqueue *fiq, struct fuse_forget_li
}
}

-static void fuse_dev_queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
+void fuse_dev_queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
{
spin_lock(&fiq->lock);
if (list_empty(&req->intr_entry)) {
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index b5bb78b5f5902c8b87f3e196baaa05640380046d..b1c56ccf828ec2d4cd921906fb42901fefcc6cc5 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -24,6 +24,12 @@ bool fuse_uring_enabled(void)
return enable_uring;
}

+struct fuse_uring_cmd_pdu {
+ struct fuse_ring_ent *ring_ent;
+};
+
+const struct fuse_iqueue_ops fuse_io_uring_ops;
+
static void fuse_uring_req_end(struct fuse_ring_ent *ring_ent, bool set_err,
int error)
{
@@ -773,6 +779,31 @@ static int fuse_uring_commit_fetch(struct io_uring_cmd *cmd, int issue_flags,
return 0;
}

+static bool is_ring_ready(struct fuse_ring *ring, int current_qid)
+{
+ int qid;
+ struct fuse_ring_queue *queue;
+ bool ready = true;
+
+ for (qid = 0; qid < ring->nr_queues && ready; qid++) {
+ if (current_qid == qid)
+ continue;
+
+ queue = ring->queues[qid];
+ if (!queue) {
+ ready = false;
+ break;
+ }
+
+ spin_lock(&queue->lock);
+ if (list_empty(&queue->ent_avail_queue))
+ ready = false;
+ spin_unlock(&queue->lock);
+ }
+
+ return ready;
+}
+
/*
* fuse_uring_req_fetch command handling
*/
@@ -781,11 +812,23 @@ static void _fuse_uring_fetch(struct fuse_ring_ent *ring_ent,
unsigned int issue_flags)
{
struct fuse_ring_queue *queue = ring_ent->queue;
+ struct fuse_ring *ring = queue->ring;
+ struct fuse_conn *fc = ring->fc;
+ struct fuse_iqueue *fiq = &fc->iq;

spin_lock(&queue->lock);
fuse_uring_ent_avail(ring_ent, queue);
ring_ent->cmd = cmd;
spin_unlock(&queue->lock);
+
+ if (!ring->ready) {
+ bool ready = is_ring_ready(ring, queue->qid);
+
+ if (ready) {
+ WRITE_ONCE(ring->ready, true);
+ fiq->ops = &fuse_io_uring_ops;
+ }
+ }
}

/*
@@ -945,3 +988,119 @@ int fuse_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)

return -EIOCBQUEUED;
}
+
+/*
+ * This prepares and sends the ring request in fuse-uring task context.
+ * User buffers are not mapped yet - the application does not have permission
+ * to write to it - this has to be executed in ring task context.
+ */
+static void
+fuse_uring_send_req_in_task(struct io_uring_cmd *cmd,
+ unsigned int issue_flags)
+{
+ struct fuse_uring_cmd_pdu *pdu = (struct fuse_uring_cmd_pdu *)cmd->pdu;
+ struct fuse_ring_ent *ring_ent = pdu->ring_ent;
+ struct fuse_ring_queue *queue = ring_ent->queue;
+ int err;
+
+ BUILD_BUG_ON(sizeof(pdu) > sizeof(cmd->pdu));
+
+ err = fuse_uring_prepare_send(ring_ent);
+ if (err)
+ goto err;
+
+ io_uring_cmd_done(cmd, 0, 0, issue_flags);
+
+ spin_lock(&queue->lock);
+ ring_ent->state = FRRS_USERSPACE;
+ list_move(&ring_ent->list, &queue->ent_in_userspace);
+ spin_unlock(&queue->lock);
+ return;
+err:
+ fuse_uring_next_fuse_req(ring_ent, queue);
+}
+
+static struct fuse_ring_queue *fuse_uring_task_to_queue(struct fuse_ring *ring)
+{
+ unsigned int qid;
+ struct fuse_ring_queue *queue;
+
+ qid = task_cpu(current);
+
+ if (WARN_ONCE(qid >= ring->nr_queues,
+ "Core number (%u) exceeds nr ueues (%zu)\n", qid,
+ ring->nr_queues))
+ qid = 0;
+
+ queue = ring->queues[qid];
+ if (WARN_ONCE(!queue, "Missing queue for qid %d\n", qid))
+ return NULL;
+
+ return queue;
+}
+
+/* queue a fuse request and send it if a ring entry is available */
+void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req)
+{
+ struct fuse_conn *fc = req->fm->fc;
+ struct fuse_ring *ring = fc->ring;
+ struct fuse_ring_queue *queue;
+ struct fuse_ring_ent *ring_ent = NULL;
+ int err;
+
+ err = -EINVAL;
+ queue = fuse_uring_task_to_queue(ring);
+ if (!queue)
+ goto err;
+
+ if (req->in.h.opcode != FUSE_NOTIFY_REPLY)
+ req->in.h.unique = fuse_get_unique(fiq);
+ spin_lock(&queue->lock);
+ err = -ENOTCONN;
+ if (unlikely(queue->stopped))
+ goto err_unlock;
+
+ if (!list_empty(&queue->ent_avail_queue)) {
+ ring_ent = list_first_entry(&queue->ent_avail_queue,
+ struct fuse_ring_ent, list);
+
+ fuse_uring_add_req_to_ring_ent(ring_ent, req);
+ } else {
+ list_add_tail(&req->list, &queue->fuse_req_queue);
+ }
+ spin_unlock(&queue->lock);
+
+ if (ring_ent) {
+ struct io_uring_cmd *cmd = ring_ent->cmd;
+ struct fuse_uring_cmd_pdu *pdu =
+ (struct fuse_uring_cmd_pdu *)cmd->pdu;
+
+ err = -EIO;
+ if (WARN_ON_ONCE(ring_ent->state != FRRS_FUSE_REQ))
+ goto err;
+
+ pdu->ring_ent = ring_ent;
+ io_uring_cmd_complete_in_task(cmd, fuse_uring_send_req_in_task);
+ }
+
+ return;
+
+err_unlock:
+ spin_unlock(&queue->lock);
+err:
+ req->out.h.error = err;
+ clear_bit(FR_PENDING, &req->flags);
+ fuse_request_end(req);
+}
+
+const struct fuse_iqueue_ops fuse_io_uring_ops = {
+ /* should be send over io-uring as enhancement */
+ .send_forget = fuse_dev_queue_forget,
+
+ /*
+ * could be send over io-uring, but interrupts should be rare,
+ * no need to make the code complex
+ */
+ .send_interrupt = fuse_dev_queue_interrupt,
+ .send_req = fuse_uring_queue_fuse_req,
+};
diff --git a/fs/fuse/dev_uring_i.h b/fs/fuse/dev_uring_i.h
index 52259714ffc59a38b21f834ae5e317fe818863dc..19867d27894f9d985e224111ea586c82b4b4cfe8 100644
--- a/fs/fuse/dev_uring_i.h
+++ b/fs/fuse/dev_uring_i.h
@@ -119,6 +119,8 @@ struct fuse_ring {
unsigned long teardown_time;

atomic_t queue_refs;
+
+ bool ready;
};

bool fuse_uring_enabled(void);
@@ -126,6 +128,7 @@ void fuse_uring_destruct(struct fuse_conn *fc);
void fuse_uring_stop_queues(struct fuse_ring *ring);
void fuse_uring_abort_end_requests(struct fuse_ring *ring);
int fuse_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags);
+void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req);

static inline void fuse_uring_abort(struct fuse_conn *fc)
{
@@ -149,6 +152,11 @@ static inline void fuse_uring_wait_stopped_queues(struct fuse_conn *fc)
atomic_read(&ring->queue_refs) == 0);
}

+static inline bool fuse_uring_ready(struct fuse_conn *fc)
+{
+ return fc->ring && fc->ring->ready;
+}
+
#else /* CONFIG_FUSE_IO_URING */

struct fuse_ring;
diff --git a/fs/fuse/fuse_dev_i.h b/fs/fuse/fuse_dev_i.h
index d7bf72dabd84c3896d1447380649e2f4d20b0643..1d1c1e9848fba8dae46651e28809f73e165e74fe 100644
--- a/fs/fuse/fuse_dev_i.h
+++ b/fs/fuse/fuse_dev_i.h
@@ -17,6 +17,8 @@ struct fuse_arg;
struct fuse_args;
struct fuse_pqueue;
struct fuse_req;
+struct fuse_iqueue;
+struct fuse_forget_link;

struct fuse_copy_state {
int write;
@@ -58,6 +60,9 @@ int fuse_copy_args(struct fuse_copy_state *cs, unsigned int numargs,
int zeroing);
int fuse_copy_out_args(struct fuse_copy_state *cs, struct fuse_args *args,
unsigned int nbytes);
+void fuse_dev_queue_forget(struct fuse_iqueue *fiq,
+ struct fuse_forget_link *forget);
+void fuse_dev_queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req);

#endif

--
2.43.0