[PATCH RFC v7 12/16] fuse: {uring} Allow to queue bg requests through io-uring

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

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

Signed-off-by: Bernd Schubert <bschubert@ddn.com>
---
fs/fuse/dev.c | 26 ++++++++++++-
fs/fuse/dev_uring.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/dev_uring_i.h | 6 +++
3 files changed, 134 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c53deb690cc9c7958741cd144fcad166b5721e11..5134bd158ce0d24f77a4b622b87ccb83b8c92f3f 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -568,7 +568,25 @@ ssize_t __fuse_simple_request(struct mnt_idmap *idmap,
return ret;
}

-static bool fuse_request_queue_background(struct fuse_req *req)
+#ifdef CONFIG_FUSE_IO_URING
+static bool fuse_request_queue_background_uring(struct fuse_conn *fc,
+ struct fuse_req *req)
+{
+ struct fuse_iqueue *fiq = &fc->iq;
+
+ req->in.h.unique = fuse_get_unique(fiq);
+ req->in.h.len = sizeof(struct fuse_in_header) +
+ fuse_len_args(req->args->in_numargs,
+ (struct fuse_arg *) req->args->in_args);
+
+ return fuse_uring_queue_bq_req(req);
+}
+#endif
+
+/*
+ * @return true if queued
+ */
+static int fuse_request_queue_background(struct fuse_req *req)
{
struct fuse_mount *fm = req->fm;
struct fuse_conn *fc = fm->fc;
@@ -580,6 +598,12 @@ static bool fuse_request_queue_background(struct fuse_req *req)
atomic_inc(&fc->num_waiting);
}
__set_bit(FR_ISREPLY, &req->flags);
+
+#ifdef CONFIG_FUSE_IO_URING
+ if (fuse_uring_ready(fc))
+ return fuse_request_queue_background_uring(fc, req);
+#endif
+
spin_lock(&fc->bg_lock);
if (likely(fc->connected)) {
fc->num_background++;
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index b1c56ccf828ec2d4cd921906fb42901fefcc6cc5..66addb5d00c36d84a0d8d1f470f5ae10d8ee3f6f 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -30,10 +30,52 @@ struct fuse_uring_cmd_pdu {

const struct fuse_iqueue_ops fuse_io_uring_ops;

+static void fuse_uring_flush_bg(struct fuse_ring_queue *queue)
+{
+ struct fuse_ring *ring = queue->ring;
+ struct fuse_conn *fc = ring->fc;
+
+ lockdep_assert_held(&queue->lock);
+ lockdep_assert_held(&fc->bg_lock);
+
+ /*
+ * Allow one bg request per queue, ignoring global fc limits.
+ * This prevents a single queue from consuming all resources and
+ * eliminates the need for remote queue wake-ups when global
+ * limits are met but this queue has no more waiting requests.
+ */
+ while ((fc->active_background < fc->max_background ||
+ !queue->active_background) &&
+ (!list_empty(&queue->fuse_req_bg_queue))) {
+ struct fuse_req *req;
+
+ req = list_first_entry(&queue->fuse_req_bg_queue,
+ struct fuse_req, list);
+ fc->active_background++;
+ queue->active_background++;
+
+ list_move_tail(&req->list, &queue->fuse_req_queue);
+ }
+}
+
static void fuse_uring_req_end(struct fuse_ring_ent *ring_ent, bool set_err,
int error)
{
+ struct fuse_ring_queue *queue = ring_ent->queue;
struct fuse_req *req = ring_ent->fuse_req;
+ struct fuse_ring *ring = queue->ring;
+ struct fuse_conn *fc = ring->fc;
+
+ lockdep_assert_not_held(&queue->lock);
+ spin_lock(&queue->lock);
+ if (test_bit(FR_BACKGROUND, &req->flags)) {
+ queue->active_background--;
+ spin_lock(&fc->bg_lock);
+ fuse_uring_flush_bg(queue);
+ spin_unlock(&fc->bg_lock);
+ }
+
+ spin_unlock(&queue->lock);

if (set_err)
req->out.h.error = error;
@@ -78,6 +120,7 @@ void fuse_uring_abort_end_requests(struct fuse_ring *ring)
{
int qid;
struct fuse_ring_queue *queue;
+ struct fuse_conn *fc = ring->fc;

for (qid = 0; qid < ring->nr_queues; qid++) {
queue = READ_ONCE(ring->queues[qid]);
@@ -85,6 +128,13 @@ void fuse_uring_abort_end_requests(struct fuse_ring *ring)
continue;

queue->stopped = true;
+
+ WARN_ON_ONCE(ring->fc->max_background != UINT_MAX);
+ spin_lock(&queue->lock);
+ spin_lock(&fc->bg_lock);
+ fuse_uring_flush_bg(queue);
+ spin_unlock(&fc->bg_lock);
+ spin_unlock(&queue->lock);
fuse_uring_abort_end_queue_requests(queue);
}
}
@@ -198,6 +248,7 @@ static struct fuse_ring_queue *fuse_uring_create_queue(struct fuse_ring *ring,
INIT_LIST_HEAD(&queue->ent_w_req_queue);
INIT_LIST_HEAD(&queue->ent_in_userspace);
INIT_LIST_HEAD(&queue->fuse_req_queue);
+ INIT_LIST_HEAD(&queue->fuse_req_bg_queue);

queue->fpq.processing = pq;
fuse_pqueue_init(&queue->fpq);
@@ -1093,6 +1144,58 @@ void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req)
fuse_request_end(req);
}

+bool fuse_uring_queue_bq_req(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;
+
+ queue = fuse_uring_task_to_queue(ring);
+ if (!queue)
+ return false;
+
+ spin_lock(&queue->lock);
+ if (unlikely(queue->stopped)) {
+ spin_unlock(&queue->lock);
+ return false;
+ }
+
+ list_add_tail(&req->list, &queue->fuse_req_bg_queue);
+
+ if (!list_empty(&queue->ent_avail_queue))
+ ring_ent = list_first_entry(&queue->ent_avail_queue,
+ struct fuse_ring_ent, list);
+
+ spin_lock(&fc->bg_lock);
+ fc->num_background++;
+ if (fc->num_background == fc->max_background)
+ fc->blocked = 1;
+ fuse_uring_flush_bg(queue);
+ spin_unlock(&fc->bg_lock);
+
+ /*
+ * Due to bg_queue flush limits there might be other bg requests
+ * in the queue that need to be handled first. Or no further req
+ * might be available.
+ */
+ req = list_first_entry_or_null(&queue->fuse_req_queue, struct fuse_req,
+ list);
+ if (ring_ent && req) {
+ struct io_uring_cmd *cmd = ring_ent->cmd;
+ struct fuse_uring_cmd_pdu *pdu =
+ (struct fuse_uring_cmd_pdu *)cmd->pdu;
+
+ fuse_uring_add_req_to_ring_ent(ring_ent, req);
+
+ pdu->ring_ent = ring_ent;
+ io_uring_cmd_complete_in_task(cmd, fuse_uring_send_req_in_task);
+ }
+ spin_unlock(&queue->lock);
+
+ return true;
+}
+
const struct fuse_iqueue_ops fuse_io_uring_ops = {
/* should be send over io-uring as enhancement */
.send_forget = fuse_dev_queue_forget,
diff --git a/fs/fuse/dev_uring_i.h b/fs/fuse/dev_uring_i.h
index 19867d27894f9d985e224111ea586c82b4b4cfe8..0826fb1c03e2e38dedad56552ea09461965e248f 100644
--- a/fs/fuse/dev_uring_i.h
+++ b/fs/fuse/dev_uring_i.h
@@ -87,8 +87,13 @@ struct fuse_ring_queue {
/* fuse requests waiting for an entry slot */
struct list_head fuse_req_queue;

+ /* background fuse requests */
+ struct list_head fuse_req_bg_queue;
+
struct fuse_pqueue fpq;

+ unsigned int active_background;
+
bool stopped;
};

@@ -129,6 +134,7 @@ 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);
+bool fuse_uring_queue_bq_req(struct fuse_req *req);

static inline void fuse_uring_abort(struct fuse_conn *fc)
{

--
2.43.0