io_uring: fix linked command file table usage

We're not consistent in how the file table is grabbed and assigned if we
have a command linked that requires the use of it.

Add ->file_table to the io_op_defs[] array, and use that to determine
when to grab the table instead of having the handlers set it if they
need to defer. This also means we can kill the IO_WQ_WORK_NEEDS_FILES
flag. We always initialize work->files, so io-wq can just check for
that.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io-wq.c

@@ -476,8 +476,7 @@ static void io_worker_handle_work(struct io_worker *worker)
 		if (work->flags & IO_WQ_WORK_CB)
 			work->func(&work);
 
-		if ((work->flags & IO_WQ_WORK_NEEDS_FILES) &&
-		    current->files != work->files) {
+		if (work->files && current->files != work->files) {
 			task_lock(current);
 			current->files = work->files;
 			task_unlock(current);

fs/io-wq.h

@@ -7,7 +7,6 @@ enum {
 	IO_WQ_WORK_CANCEL	= 1,
 	IO_WQ_WORK_HAS_MM	= 2,
 	IO_WQ_WORK_HASHED	= 4,
-	IO_WQ_WORK_NEEDS_FILES	= 16,
 	IO_WQ_WORK_UNBOUND	= 32,
 	IO_WQ_WORK_INTERNAL	= 64,
 	IO_WQ_WORK_CB		= 128,

fs/io_uring.c

@@ -603,6 +603,8 @@ struct io_op_def {
 	unsigned		unbound_nonreg_file : 1;
 	/* opcode is not supported by this kernel */
 	unsigned		not_supported : 1;
+	/* needs file table */
+	unsigned		file_table : 1;
 };
 
 static const struct io_op_def io_op_defs[] = {
@@ -661,6 +663,7 @@ static const struct io_op_def io_op_defs[] = {
 		.needs_mm		= 1,
 		.needs_file		= 1,
 		.unbound_nonreg_file	= 1,
+		.file_table		= 1,
 	},
 	[IORING_OP_ASYNC_CANCEL] = {},
 	[IORING_OP_LINK_TIMEOUT] = {
@@ -679,12 +682,15 @@ static const struct io_op_def io_op_defs[] = {
 	[IORING_OP_OPENAT] = {
 		.needs_file		= 1,
 		.fd_non_neg		= 1,
+		.file_table		= 1,
 	},
 	[IORING_OP_CLOSE] = {
 		.needs_file		= 1,
+		.file_table		= 1,
 	},
 	[IORING_OP_FILES_UPDATE] = {
 		.needs_mm		= 1,
+		.file_table		= 1,
 	},
 	[IORING_OP_STATX] = {
 		.needs_mm		= 1,
@@ -720,6 +726,7 @@ static const struct io_op_def io_op_defs[] = {
 	[IORING_OP_OPENAT2] = {
 		.needs_file		= 1,
 		.fd_non_neg		= 1,
+		.file_table		= 1,
 	},
 };
 
@@ -732,6 +739,7 @@ static void io_queue_linked_timeout(struct io_kiocb *req);
 static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 				 struct io_uring_files_update *ip,
 				 unsigned nr_args);
+static int io_grab_files(struct io_kiocb *req);
 
 static struct kmem_cache *req_cachep;
 
@@ -2568,10 +2576,8 @@ static int io_openat2(struct io_kiocb *req, struct io_kiocb **nxt,
 	struct file *file;
 	int ret;
 
-	if (force_nonblock) {
-		req->work.flags |= IO_WQ_WORK_NEEDS_FILES;
+	if (force_nonblock)
 		return -EAGAIN;
-	}
 
 	ret = build_open_flags(&req->open.how, &op);
 	if (ret)
@@ -2797,10 +2803,8 @@ static int io_close(struct io_kiocb *req, struct io_kiocb **nxt,
 		return ret;
 
 	/* if the file has a flush method, be safe and punt to async */
-	if (req->close.put_file->f_op->flush && !io_wq_current_is_worker()) {
-		req->work.flags |= IO_WQ_WORK_NEEDS_FILES;
+	if (req->close.put_file->f_op->flush && !io_wq_current_is_worker())
 		goto eagain;
-	}
 
 	/*
 	 * No ->flush(), safely close from here and just punt the
@@ -3244,7 +3248,6 @@ static int io_accept(struct io_kiocb *req, struct io_kiocb **nxt,
 	ret = __io_accept(req, nxt, force_nonblock);
 	if (ret == -EAGAIN && force_nonblock) {
 		req->work.func = io_accept_finish;
-		req->work.flags |= IO_WQ_WORK_NEEDS_FILES;
 		io_put_req(req);
 		return -EAGAIN;
 	}
@@ -3967,10 +3970,8 @@ static int io_files_update(struct io_kiocb *req, bool force_nonblock)
 	struct io_uring_files_update up;
 	int ret;
 
-	if (force_nonblock) {
-		req->work.flags |= IO_WQ_WORK_NEEDS_FILES;
+	if (force_nonblock)
 		return -EAGAIN;
-	}
 
 	up.offset = req->files_update.offset;
 	up.fds = req->files_update.arg;
@@ -3991,6 +3992,12 @@ static int io_req_defer_prep(struct io_kiocb *req,
 {
 	ssize_t ret = 0;
 
+	if (io_op_defs[req->opcode].file_table) {
+		ret = io_grab_files(req);
+		if (unlikely(ret))
+			return ret;
+	}
+
 	io_req_work_grab_env(req, &io_op_defs[req->opcode]);
 
 	switch (req->opcode) {
@@ -4424,6 +4431,8 @@ static int io_grab_files(struct io_kiocb *req)
 	int ret = -EBADF;
 	struct io_ring_ctx *ctx = req->ctx;
 
+	if (req->work.files)
+		return 0;
 	if (!ctx->ring_file)
 		return -EBADF;
 
@@ -4542,7 +4551,7 @@ static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (ret == -EAGAIN && (!(req->flags & REQ_F_NOWAIT) ||
 	    (req->flags & REQ_F_MUST_PUNT))) {
 punt:
-		if (req->work.flags & IO_WQ_WORK_NEEDS_FILES) {
+		if (io_op_defs[req->opcode].file_table) {
 			ret = io_grab_files(req);
 			if (ret)
 				goto err;