[RFC net-next v3 20/29] io_uring: add zc notification flush requests

From: Pavel Begunkov
Date: Tue Jun 28 2022 - 15:04:15 EST


Overlay notification control onto IORING_OP_RSRC_UPDATE (former
IORING_OP_FILES_UPDATE). It allows to flush a range of zc notifications
from slots with indexes [sqe->off, sqe->off+sqe->len). If sqe->arg is
not zero, it also copies sqe->arg as a new tag for all flushed
notifications.

Note, it doesn't flush a notification of a slot if there was no requests
attached to it (since last flush or registration).

Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
fs/io_uring.c | 47 +++++++++++++++++++++++++++++++++++
include/uapi/linux/io_uring.h | 1 +
2 files changed, 48 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e9fc7e076c7f..a88c9c73ed1d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1284,6 +1284,7 @@ static const struct io_op_def io_op_defs[] = {
[IORING_OP_RSRC_UPDATE] = {
.audit_skip = 1,
.iopoll = 1,
+ .ioprio = 1,
},
[IORING_OP_STATX] = {
.audit_skip = 1,
@@ -2953,6 +2954,16 @@ static void io_notif_slot_flush(struct io_notif_slot *slot)
io_notif_complete(notif);
}

+static inline void io_notif_slot_flush_submit(struct io_notif_slot *slot,
+ unsigned int issue_flags)
+{
+ if (!(issue_flags & IO_URING_F_UNLOCKED)) {
+ slot->notif->task = current;
+ io_get_task_refs(1);
+ }
+ io_notif_slot_flush(slot);
+}
+
static __cold int io_notif_unregister(struct io_ring_ctx *ctx)
__must_hold(&ctx->uring_lock)
{
@@ -8286,6 +8297,40 @@ static int io_rsrc_update_prep(struct io_kiocb *req,
return 0;
}

+static int io_notif_update(struct io_kiocb *req, unsigned int issue_flags)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+ unsigned len = req->rsrc_update.nr_args;
+ unsigned idx_end, idx = req->rsrc_update.offset;
+ int ret = 0;
+
+ io_ring_submit_lock(ctx, issue_flags);
+ if (unlikely(check_add_overflow(idx, len, &idx_end))) {
+ ret = -EOVERFLOW;
+ goto out;
+ }
+ if (unlikely(idx_end > ctx->nr_notif_slots)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ for (; idx < idx_end; idx++) {
+ struct io_notif_slot *slot = &ctx->notif_slots[idx];
+
+ if (!slot->notif)
+ continue;
+ if (req->rsrc_update.arg)
+ slot->tag = req->rsrc_update.arg;
+ io_notif_slot_flush_submit(slot, issue_flags);
+ }
+out:
+ io_ring_submit_unlock(ctx, issue_flags);
+ if (ret < 0)
+ req_set_fail(req);
+ __io_req_complete(req, issue_flags, ret, 0);
+ return 0;
+}
+
static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_ring_ctx *ctx = req->ctx;
@@ -8315,6 +8360,8 @@ static int io_rsrc_update(struct io_kiocb *req, unsigned int issue_flags)
switch (req->rsrc_update.type) {
case IORING_RSRC_UPDATE_FILES:
return io_files_update(req, issue_flags);
+ case IORING_RSRC_UPDATE_NOTIF:
+ return io_notif_update(req, issue_flags);
}
return -EINVAL;
}
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 5f574558b96c..19b9d7a2da29 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -266,6 +266,7 @@ enum io_uring_op {
*/
enum {
IORING_RSRC_UPDATE_FILES,
+ IORING_RSRC_UPDATE_NOTIF,
};

/*
--
2.36.1