This is to avoid using async completion tasks
(i.e. context switches) when not needed.
Cc: io-uring@xxxxxxxxxxxxxxx
Signed-off-by: Bernd Schubert <bschubert@xxxxxxx>
---
This condition should be better verified by io-uring developers.
} else if (current->io_uring) {
/* There are two cases here
* 1) fuse-server side uses multiple threads accessing
* the ring
* 2) IO requests through io-uring
*/
send_in_task = true;
issue_flags = 0;
---
fs/fuse/dev_uring.c | 57 ++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 46 insertions(+), 11 deletions(-)
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index cdc5836edb6e..74407e5e86fa 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -32,7 +32,8 @@
#include <linux/io_uring/cmd.h>
static void fuse_uring_req_end_and_get_next(struct fuse_ring_ent *ring_ent,
- bool set_err, int error);
+ bool set_err, int error,
+ unsigned int issue_flags);
static void fuse_ring_ring_ent_unset_userspace(struct fuse_ring_ent *ent)
{
@@ -682,7 +683,9 @@ static int fuse_uring_copy_to_ring(struct fuse_ring *ring, struct fuse_req *req,
* userspace will read it
* This is comparable with classical read(/dev/fuse)
*/
-static void fuse_uring_send_to_ring(struct fuse_ring_ent *ring_ent)
+static void fuse_uring_send_to_ring(struct fuse_ring_ent *ring_ent,
+ unsigned int issue_flags,
+ bool send_in_task)
{
struct fuse_ring *ring = ring_ent->queue->ring;
struct fuse_ring_req *rreq = ring_ent->rreq;
@@ -723,13 +726,16 @@ static void fuse_uring_send_to_ring(struct fuse_ring_ent *ring_ent)
__func__, ring_ent->queue->qid, ring_ent->tag, ring_ent->state,
rreq->in.opcode, rreq->in.unique);
- io_uring_cmd_complete_in_task(ring_ent->cmd,
- fuse_uring_async_send_to_ring);
+ if (send_in_task)
+ io_uring_cmd_complete_in_task(ring_ent->cmd,
+ fuse_uring_async_send_to_ring);
+ else
+ io_uring_cmd_done(ring_ent->cmd, 0, 0, issue_flags);
return;
err:
- fuse_uring_req_end_and_get_next(ring_ent, true, err);
+ fuse_uring_req_end_and_get_next(ring_ent, true, err, issue_flags);
}
/*
@@ -806,7 +812,8 @@ static bool fuse_uring_ent_release_and_fetch(struct fuse_ring_ent *ring_ent)
* has lock/unlock/lock to avoid holding the lock on calling fuse_request_end
*/
static void fuse_uring_req_end_and_get_next(struct fuse_ring_ent *ring_ent,
- bool set_err, int error)
+ bool set_err, int error,
+ unsigned int issue_flags)
{
struct fuse_req *req = ring_ent->fuse_req;
int has_next;
@@ -822,7 +829,7 @@ static void fuse_uring_req_end_and_get_next(struct fuse_ring_ent *ring_ent,
has_next = fuse_uring_ent_release_and_fetch(ring_ent);
if (has_next) {
/* called within uring context - use provided flags */
- fuse_uring_send_to_ring(ring_ent);
+ fuse_uring_send_to_ring(ring_ent, issue_flags, false);
}
}
@@ -857,7 +864,7 @@ static void fuse_uring_commit_and_release(struct fuse_dev *fud,
out:
pr_devel("%s:%d ret=%zd op=%d req-ret=%d\n", __func__, __LINE__, err,
req->args->opcode, req->out.h.error);
- fuse_uring_req_end_and_get_next(ring_ent, set_err, err);
+ fuse_uring_req_end_and_get_next(ring_ent, set_err, err, issue_flags);
}
/*
@@ -1156,10 +1163,12 @@ int fuse_uring_queue_fuse_req(struct fuse_conn *fc, struct fuse_req *req)
struct fuse_ring_queue *queue;
struct fuse_ring_ent *ring_ent = NULL;
int res;
- int async = test_bit(FR_BACKGROUND, &req->flags) &&
- !req->args->async_blocking;
+ int async_req = test_bit(FR_BACKGROUND, &req->flags);
+ int async = async_req && !req->args->async_blocking;
struct list_head *ent_queue, *req_queue;
int qid;
+ bool send_in_task;
+ unsigned int issue_flags;
qid = fuse_uring_get_req_qid(req, ring, async);
queue = fuse_uring_get_queue(ring, qid);
@@ -1182,11 +1191,37 @@ int fuse_uring_queue_fuse_req(struct fuse_conn *fc, struct fuse_req *req)
list_first_entry(ent_queue, struct fuse_ring_ent, list);
list_del(&ring_ent->list);
fuse_uring_add_req_to_ring_ent(ring_ent, req);
+ if (current == queue->server_task) {
+ issue_flags = queue->uring_cmd_issue_flags;
+ } else if (current->io_uring) {
+ /* There are two cases here
+ * 1) fuse-server side uses multiple threads accessing
+ * the ring. We only have stored issue_flags for
+ * into the queue for one thread (the first one
+ * that submits FUSE_URING_REQ_FETCH)
+ * 2) IO requests through io-uring, we do not have
+ * issue flags at all for these
+ */
+ send_in_task = true;
+ issue_flags = 0;
+ } else {
+ if (async_req) {
+ /*
+ * page cache writes might hold an upper
+ * spinlockl, which conflicts with the io-uring
+ * mutex
+ */
+ send_in_task = true;
+ issue_flags = 0;
+ } else {
+ issue_flags = IO_URING_F_UNLOCKED;
+ }
+ }
}
spin_unlock(&queue->lock);
if (ring_ent != NULL)
- fuse_uring_send_to_ring(ring_ent);
+ fuse_uring_send_to_ring(ring_ent, issue_flags, send_in_task);
return 0;
--
2.40.1
