Merge tag 'for-6.8/io_uring-2024-01-08' of git://git.kernel.dk/linux

Pull io_uring updates from Jens Axboe:
 "Mostly just come fixes and cleanups, but one feature as well. In
  detail:

   - Harden the check for handling IOPOLL based on return (Pavel)

   - Various minor optimizations (Pavel)

   - Drop remnants of SCM_RIGHTS fd passing support, now that it's no
     longer supported since 6.7 (me)

   - Fix for a case where bytes_done wasn't initialized properly on a
     failure condition for read/write requests (me)

   - Move the register related code to a separate file (me)

   - Add support for returning the provided ring buffer head (me)

   - Add support for adding a direct descriptor to the normal file table
     (me, Christian Brauner)

   - Fix for ensuring pending task_work for a ring with DEFER_TASKRUN is
     run even if we timeout waiting (me)"

* tag 'for-6.8/io_uring-2024-01-08' of git://git.kernel.dk/linux:
  io_uring: ensure local task_work is run on wait timeout
  io_uring/kbuf: add method for returning provided buffer ring head
  io_uring/rw: ensure io->bytes_done is always initialized
  io_uring: drop any code related to SCM_RIGHTS
  io_uring/unix: drop usage of io_uring socket
  io_uring/register: move io_uring_register(2) related code to register.c
  io_uring/openclose: add support for IORING_OP_FIXED_FD_INSTALL
  io_uring/cmd: inline io_uring_cmd_get_task
  io_uring/cmd: inline io_uring_cmd_do_in_task_lazy
  io_uring: split out cmd api into a separate header
  io_uring: optimise ltimeout for inline execution
  io_uring: don't check iopoll if request completes

include/linux/io_uring/cmd.h

@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _LINUX_IO_URING_CMD_H
+#define _LINUX_IO_URING_CMD_H
+
+#include <uapi/linux/io_uring.h>
+#include <linux/io_uring_types.h>
+
+/* only top 8 bits of sqe->uring_cmd_flags for kernel internal use */
+#define IORING_URING_CMD_CANCELABLE	(1U << 30)
+
+struct io_uring_cmd {
+	struct file	*file;
+	const struct io_uring_sqe *sqe;
+	/* callback to defer completions to task context */
+	void (*task_work_cb)(struct io_uring_cmd *cmd, unsigned);
+	u32		cmd_op;
+	u32		flags;
+	u8		pdu[32]; /* available inline for free use */
+};
+
+static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
+{
+	return sqe->cmd;
+}
+
+#if defined(CONFIG_IO_URING)
+int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
+			      struct iov_iter *iter, void *ioucmd);
+void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, ssize_t res2,
+			unsigned issue_flags);
+void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd,
+			    void (*task_work_cb)(struct io_uring_cmd *, unsigned),
+			    unsigned flags);
+
+void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
+		unsigned int issue_flags);
+
+#else
+static inline int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
+			      struct iov_iter *iter, void *ioucmd)
+{
+	return -EOPNOTSUPP;
+}
+static inline void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret,
+		ssize_t ret2, unsigned issue_flags)
+{
+}
+static inline void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd,
+			    void (*task_work_cb)(struct io_uring_cmd *, unsigned),
+			    unsigned flags)
+{
+}
+static inline void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
+		unsigned int issue_flags)
+{
+}
+#endif
+
+/* users must follow the IOU_F_TWQ_LAZY_WAKE semantics */
+static inline void io_uring_cmd_do_in_task_lazy(struct io_uring_cmd *ioucmd,
+			void (*task_work_cb)(struct io_uring_cmd *, unsigned))
+{
+	__io_uring_cmd_do_in_task(ioucmd, task_work_cb, IOU_F_TWQ_LAZY_WAKE);
+}
+
+static inline void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
+			void (*task_work_cb)(struct io_uring_cmd *, unsigned))
+{
+	__io_uring_cmd_do_in_task(ioucmd, task_work_cb, 0);
+}
+
+static inline struct task_struct *io_uring_cmd_get_task(struct io_uring_cmd *cmd)
+{
+	return cmd_to_io_kiocb(cmd)->task;
+}
+
+#endif /* _LINUX_IO_URING_CMD_H */