io_uring: remove REQ_F_MUST_PUNT

REQ_F_MUST_PUNT may seem looking good and clear, but it's the same
as not having REQ_F_NOWAIT set. That rather creates more confusion.
Moreover, it doesn't even affect any behaviour (e.g. see the patch
removing it from io_{read,write}).

Kill theg flag and update already outdated comments.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -534,7 +534,6 @@ enum {
 	REQ_F_LINK_TIMEOUT_BIT,
 	REQ_F_TIMEOUT_BIT,
 	REQ_F_ISREG_BIT,
-	REQ_F_MUST_PUNT_BIT,
 	REQ_F_TIMEOUT_NOSEQ_BIT,
 	REQ_F_COMP_LOCKED_BIT,
 	REQ_F_NEED_CLEANUP_BIT,
@@ -582,8 +581,6 @@ enum {
 	REQ_F_TIMEOUT		= BIT(REQ_F_TIMEOUT_BIT),
 	/* regular file */
 	REQ_F_ISREG		= BIT(REQ_F_ISREG_BIT),
-	/* must be punted even for NONBLOCK */
-	REQ_F_MUST_PUNT		= BIT(REQ_F_MUST_PUNT_BIT),
 	/* no timeout sequence */
 	REQ_F_TIMEOUT_NOSEQ	= BIT(REQ_F_TIMEOUT_NOSEQ_BIT),
 	/* completion under lock */
@@ -2894,10 +2891,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock)
 	if (req->flags & REQ_F_LINK_HEAD)
 		req->result = io_size;
 
-	/*
-	 * If the file doesn't support async, mark it as REQ_F_MUST_PUNT so
-	 * we know to async punt it even if it was opened O_NONBLOCK
-	 */
+	/* If the file doesn't support async, just async punt */
 	if (force_nonblock && !io_file_supports_async(req->file, READ))
 		goto copy_iov;
 
@@ -2993,10 +2987,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock)
 	if (req->flags & REQ_F_LINK_HEAD)
 		req->result = io_size;
 
-	/*
-	 * If the file doesn't support async, mark it as REQ_F_MUST_PUNT so
-	 * we know to async punt it even if it was opened O_NONBLOCK
-	 */
+	/* If the file doesn't support async, just async punt */
 	if (force_nonblock && !io_file_supports_async(req->file, WRITE))
 		goto copy_iov;
 
@@ -3717,8 +3708,10 @@ static int io_close(struct io_kiocb *req, bool force_nonblock)
 
 	/* if the file has a flush method, be safe and punt to async */
 	if (close->put_file->f_op->flush && force_nonblock) {
+		/* was never set, but play safe */
+		req->flags &= ~REQ_F_NOWAIT;
 		/* avoid grabbing files - we don't need the files */
-		req->flags |= REQ_F_NO_FILE_TABLE | REQ_F_MUST_PUNT;
+		req->flags |= REQ_F_NO_FILE_TABLE;
 		return -EAGAIN;
 	}
 
@@ -4645,7 +4638,7 @@ static bool io_arm_poll_handler(struct io_kiocb *req)
 
 	if (!req->file || !file_can_poll(req->file))
 		return false;
-	if (req->flags & (REQ_F_MUST_PUNT | REQ_F_POLLED))
+	if (req->flags & REQ_F_POLLED)
 		return false;
 	if (!def->pollin && !def->pollout)
 		return false;
@@ -5852,8 +5845,7 @@ static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	 * We async punt it if the file wasn't marked NOWAIT, or if the file
 	 * doesn't support non-blocking read/write attempts
 	 */
-	if (ret == -EAGAIN && (!(req->flags & REQ_F_NOWAIT) ||
-	    (req->flags & REQ_F_MUST_PUNT))) {
+	if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) {
 		if (io_arm_poll_handler(req)) {
 			if (linked_timeout)
 				io_queue_linked_timeout(linked_timeout);