This is an optional ioctl to avoid running the stop monitor
(delayed workq) at run time in intervals - saves cpu cycles.
When the FUSE_DEV_IOC_URING ioctl with subcommand
FUSE_URING_IOCTL_CMD_WAIT is received it cancels the stop monitor
(delayed workq) and then goes into a an interruptible waitq - on
process termination it gets woken up and schedules the stop monitor
again.
As the submitting thread is waiting forever in a waitq,
userspace daemon side has to create a separate thread for it.
The additional ioctl subcommand FUSE_URING_IOCTL_CMD_STOP exits
to let userspace explicitly initiate fuse uring shutdown and to wake up
the FUSE_URING_IOCTL_CMD_WAIT waiting thread.
Signed-off-by: Bernd Schubert <bschubert@xxxxxxx>
cc: Miklos Szeredi <miklos@xxxxxxxxxx>
cc: linux-fsdevel@xxxxxxxxxxxxxxx
cc: Amir Goldstein <amir73il@xxxxxxxxx>
cc: fuse-devel@xxxxxxxxxxxxxxxxxxxxx
---
fs/fuse/dev_uring.c | 47 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index ade341d86c03..e19c652e7071 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -425,6 +425,49 @@ static int fuse_uring_cfg(struct fuse_conn *fc, unsigned int qid,
return rc;
}
+/**
+ * Wait until uring shall be destructed and then release uring resources
+ */
+static int fuse_uring_wait_stop(struct fuse_conn *fc)
+{
+ struct fuse_iqueue *fiq = &fc->iq;
+
+ pr_devel("%s stop_requested=%d", __func__, fc->ring.stop_requested);
+
+ if (fc->ring.stop_requested)
+ return -EINTR;
+
+ /* This userspace thread can stop uring on process stop, no need
+ * for the interval worker
+ */
+ pr_devel("%s cancel stop monitor\n", __func__);
+ cancel_delayed_work_sync(&fc->ring.stop_monitor);
+
+ wait_event_interruptible(fc->ring.stop_waitq,
+ !fiq->connected ||
+ fc->ring.stop_requested);
+
+ /* The userspace task gets scheduled to back userspace, we need
+ * the interval worker again. It runs immediately for quick cleanup
+ * in shutdown/process kill.
+ */
+
+ mutex_lock(&fc->ring.start_stop_lock);
+ if (!fc->ring.queues_stopped)
+ mod_delayed_work(system_wq, &fc->ring.stop_monitor, 0);
+ mutex_unlock(&fc->ring.start_stop_lock);
+
+ return 0;
+}
+
+static int fuse_uring_shutdown_wakeup(struct fuse_conn *fc)
+{
+ fc->ring.stop_requested = 1;
+ wake_up_all(&fc->ring.stop_waitq);
+
+ return 0;
+}
+
int fuse_uring_ioctl(struct file *file, struct fuse_uring_cfg *cfg)
{
struct fuse_dev *fud = fuse_get_dev(file);
@@ -443,6 +486,10 @@ int fuse_uring_ioctl(struct file *file, struct fuse_uring_cfg *cfg)
switch (cfg->cmd) {
case FUSE_URING_IOCTL_CMD_QUEUE_CFG:
return fuse_uring_cfg(fc, cfg->qid, cfg);
+ case FUSE_URING_IOCTL_CMD_WAIT:
+ return fuse_uring_wait_stop(fc);
+ case FUSE_URING_IOCTL_CMD_STOP:
+ return fuse_uring_shutdown_wakeup(fc);
default:
return -EINVAL;
}
--
2.37.2
