Revert "io_uring: add zc notification flush requests"

This reverts commit 492dddb.

Soon we won't have the very notion of notification flushing, so remove
notification flushing requests.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8850334ca56e65b413cb34fd158db81d7b2865a3.1662027856.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: isilence

include/uapi/linux/io_uring.h

@@ -301,7 +301,6 @@ enum io_uring_op {
  */
 enum {
 	IORING_RSRC_UPDATE_FILES,
-	IORING_RSRC_UPDATE_NOTIF,
 };
 
 /*

io_uring/rsrc.c

@@ -15,7 +15,6 @@
 #include "io_uring.h"
 #include "openclose.h"
 #include "rsrc.h"
-#include "notif.h"
 
 struct io_rsrc_update {
 	struct file			*file;
@@ -741,50 +740,13 @@ static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 	return IOU_OK;
 }
 
-static int io_notif_update(struct io_kiocb *req, unsigned int issue_flags)
-{
-	struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
-	struct io_ring_ctx *ctx = req->ctx;
-	unsigned len = up->nr_args;
-	unsigned idx_end, idx = up->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 (up->arg)
-			slot->tag = up->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_set_res(req, ret, 0);
-	return IOU_OK;
-}
-
 int io_rsrc_update(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 
 	switch (up->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;
 }