for-5.19/io_uring-2022-05-22

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Merge tag 'for-5.19/io_uring-2022-05-22' of git://git.kernel.dk/linux-block

Pull io_uring updates from Jens Axboe:
 "Here are the main io_uring changes for 5.19. This contains:

   - Fixes for sparse type warnings (Christoph, Vasily)

   - Support for multi-shot accept (Hao)

   - Support for io_uring managed fixed files, rather than always
     needing the applicationt o manage the indices (me)

   - Fix for a spurious poll wakeup (Dylan)

   - CQE overflow fixes (Dylan)

   - Support more types of cancelations (me)

   - Support for co-operative task_work signaling, rather than always
     forcing an IPI (me)

   - Support for doing poll first when appropriate, rather than always
     attempting a transfer first (me)

   - Provided buffer cleanups and support for mapped buffers (me)

   - Improve how io_uring handles inflight SCM files (Pavel)

   - Speedups for registered files (Pavel, me)

   - Organize the completion data in a struct in io_kiocb rather than
     keep it in separate spots (Pavel)

   - task_work improvements (Pavel)

   - Cleanup and optimize the submission path, in general and for
     handling links (Pavel)

   - Speedups for registered resource handling (Pavel)

   - Support sparse buffers and file maps (Pavel, me)

   - Various fixes and cleanups (Almog, Pavel, me)"

* tag 'for-5.19/io_uring-2022-05-22' of git://git.kernel.dk/linux-block: (111 commits)
  io_uring: fix incorrect __kernel_rwf_t cast
  io_uring: disallow mixed provided buffer group registrations
  io_uring: initialize io_buffer_list head when shared ring is unregistered
  io_uring: add fully sparse buffer registration
  io_uring: use rcu_dereference in io_close
  io_uring: consistently use the EPOLL* defines
  io_uring: make apoll_events a __poll_t
  io_uring: drop a spurious inline on a forward declaration
  io_uring: don't use ERR_PTR for user pointers
  io_uring: use a rwf_t for io_rw.flags
  io_uring: add support for ring mapped supplied buffers
  io_uring: add io_pin_pages() helper
  io_uring: add buffer selection support to IORING_OP_NOP
  io_uring: fix locking state for empty buffer group
  io_uring: implement multishot mode for accept
  io_uring: let fast poll support multishot
  io_uring: add REQ_F_APOLL_MULTISHOT for requests
  io_uring: add IORING_ACCEPT_MULTISHOT for accept
  io_uring: only wake when the correct events are set
  io_uring: avoid io-wq -EAGAIN looping for !IOPOLL
  ...

fs/io-wq.c

@@ -871,7 +871,7 @@ static bool io_wq_for_each_worker(struct io_wqe *wqe,
 
 static bool io_wq_worker_wake(struct io_worker *worker, void *data)
 {
-	set_notify_signal(worker->task);
+	__set_notify_signal(worker->task);
 	wake_up_process(worker->task);
 	return false;
 }
@@ -991,7 +991,7 @@ static bool __io_wq_worker_cancel(struct io_worker *worker,
 {
 	if (work && match->fn(work, match->data)) {
 		work->flags |= IO_WQ_WORK_CANCEL;
-		set_notify_signal(worker->task);
+		__set_notify_signal(worker->task);
 		return true;
 	}
 

fs/io-wq.h

@@ -155,6 +155,7 @@ struct io_wq_work_node *wq_stack_extract(struct io_wq_work_node *stack)
 struct io_wq_work {
 	struct io_wq_work_node list;
 	unsigned flags;
+	int cancel_seq;
 };
 
 static inline struct io_wq_work *wq_next_work(struct io_wq_work *work)

include/linux/sched/signal.h

@@ -355,14 +355,23 @@ static inline void clear_notify_signal(void)
 	smp_mb__after_atomic();
 }
 
+/*
+ * Returns 'true' if kick_process() is needed to force a transition from
+ * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
+ */
+static inline bool __set_notify_signal(struct task_struct *task)
+{
+	return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
+	       !wake_up_state(task, TASK_INTERRUPTIBLE);
+}
+
 /*
  * Called to break out of interruptible wait loops, and enter the
  * exit_to_user_mode_loop().
  */
 static inline void set_notify_signal(struct task_struct *task)
 {
-	if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
+	if (__set_notify_signal(task))
-	    !wake_up_state(task, TASK_INTERRUPTIBLE))
 		kick_process(task);
 }
 

include/linux/task_work.h

@@ -17,6 +17,7 @@ enum task_work_notify_mode {
 	TWA_NONE,
 	TWA_RESUME,
 	TWA_SIGNAL,
+	TWA_SIGNAL_NO_IPI,
 };
 
 static inline bool task_work_pending(struct task_struct *task)

include/trace/events/io_uring.h

@@ -520,7 +520,7 @@ TRACE_EVENT(io_uring_req_failed,
 		__entry->off		= sqe->off;
 		__entry->addr		= sqe->addr;
 		__entry->len		= sqe->len;
-		__entry->op_flags	= sqe->rw_flags;
+		__entry->op_flags	= sqe->poll32_events;
 		__entry->buf_index	= sqe->buf_index;
 		__entry->personality	= sqe->personality;
 		__entry->file_index	= sqe->file_index;
@@ -530,7 +530,7 @@ TRACE_EVENT(io_uring_req_failed,
 	),
 
 	TP_printk("ring %p, req %p, user_data 0x%llx, "
-		"op %d, flags 0x%x, prio=%d, off=%llu, addr=%llu, "
+		  "op %d, flags 0x%x, prio=%d, off=%llu, addr=%llu, "
 		  "len=%u, rw_flags=0x%x, buf_index=%d, "
 		  "personality=%d, file_index=%d, pad=0x%llx/%llx, error=%d",
 		  __entry->ctx, __entry->req, __entry->user_data,
@@ -543,6 +543,46 @@ TRACE_EVENT(io_uring_req_failed,
 		  (unsigned long long) __entry->pad2, __entry->error)
 );
 
+
+/*
+ * io_uring_cqe_overflow - a CQE overflowed
+ *
+ * @ctx:		pointer to a ring context structure
+ * @user_data:		user data associated with the request
+ * @res:		CQE result
+ * @cflags:		CQE flags
+ * @ocqe:		pointer to the overflow cqe (if available)
+ *
+ */
+TRACE_EVENT(io_uring_cqe_overflow,
+
+	TP_PROTO(void *ctx, unsigned long long user_data, s32 res, u32 cflags,
+		 void *ocqe),
+
+	TP_ARGS(ctx, user_data, res, cflags, ocqe),
+
+	TP_STRUCT__entry (
+		__field(  void *,		ctx		)
+		__field(  unsigned long long,	user_data	)
+		__field(  s32,			res		)
+		__field(  u32,			cflags		)
+		__field(  void *,		ocqe		)
+	),
+
+	TP_fast_assign(
+		__entry->ctx		= ctx;
+		__entry->user_data	= user_data;
+		__entry->res		= res;
+		__entry->cflags		= cflags;
+		__entry->ocqe		= ocqe;
+	),
+
+	TP_printk("ring %p, user_data 0x%llx, res %d, flags %x, "
+		  "overflow_cqe %p",
+		  __entry->ctx, __entry->user_data, __entry->res,
+		  __entry->cflags, __entry->ocqe)
+);
+
 #endif /* _TRACE_IO_URING_H */
 
 /* This part must be outside protection */

include/uapi/linux/io_uring.h

@@ -63,6 +63,15 @@ struct io_uring_sqe {
 	__u64	__pad2[2];
 };
 
+/*
+ * If sqe->file_index is set to this for opcodes that instantiate a new
+ * direct descriptor (like openat/openat2/accept), then io_uring will allocate
+ * an available direct descriptor instead of having the application pass one
+ * in. The picked direct descriptor will be returned in cqe->res, or -ENFILE
+ * if the space is full.
+ */
+#define IORING_FILE_INDEX_ALLOC		(~0U)
+
 enum {
 	IOSQE_FIXED_FILE_BIT,
 	IOSQE_IO_DRAIN_BIT,
@@ -102,6 +111,20 @@ enum {
 #define IORING_SETUP_ATTACH_WQ	(1U << 5)	/* attach to existing wq */
 #define IORING_SETUP_R_DISABLED	(1U << 6)	/* start with ring disabled */
 #define IORING_SETUP_SUBMIT_ALL	(1U << 7)	/* continue submit on error */
+/*
+ * Cooperative task running. When requests complete, they often require
+ * forcing the submitter to transition to the kernel to complete. If this
+ * flag is set, work will be done when the task transitions anyway, rather
+ * than force an inter-processor interrupt reschedule. This avoids interrupting
+ * a task running in userspace, and saves an IPI.
+ */
+#define IORING_SETUP_COOP_TASKRUN	(1U << 8)
+/*
+ * If COOP_TASKRUN is set, get notified if task work is available for
+ * running and a kernel transition would be needed to run it. This sets
+ * IORING_SQ_TASKRUN in the sq ring flags. Not valid with COOP_TASKRUN.
+ */
+#define IORING_SETUP_TASKRUN_FLAG	(1U << 9)
 
 enum {
 	IORING_OP_NOP,
@@ -187,6 +210,33 @@ enum {
 #define IORING_POLL_UPDATE_EVENTS	(1U << 1)
 #define IORING_POLL_UPDATE_USER_DATA	(1U << 2)
 
+/*
+ * ASYNC_CANCEL flags.
+ *
+ * IORING_ASYNC_CANCEL_ALL	Cancel all requests that match the given key
+ * IORING_ASYNC_CANCEL_FD	Key off 'fd' for cancelation rather than the
+ *				request 'user_data'
+ * IORING_ASYNC_CANCEL_ANY	Match any request
+ */
+#define IORING_ASYNC_CANCEL_ALL	(1U << 0)
+#define IORING_ASYNC_CANCEL_FD	(1U << 1)
+#define IORING_ASYNC_CANCEL_ANY	(1U << 2)
+
+/*
+ * send/sendmsg and recv/recvmsg flags (sqe->addr2)
+ *
+ * IORING_RECVSEND_POLL_FIRST	If set, instead of first attempting to send
+ *				or receive and arm poll if that yields an
+ *				-EAGAIN result, arm poll upfront and skip
+ *				the initial transfer attempt.
+ */
+#define IORING_RECVSEND_POLL_FIRST	(1U << 0)
+
+/*
+ * accept flags stored in sqe->ioprio
+ */
+#define IORING_ACCEPT_MULTISHOT	(1U << 0)
+
 /*
  * IO completion data structure (Completion Queue Entry)
  */
@@ -236,6 +286,7 @@ struct io_sqring_offsets {
  */
 #define IORING_SQ_NEED_WAKEUP	(1U << 0) /* needs io_uring_enter wakeup */
 #define IORING_SQ_CQ_OVERFLOW	(1U << 1) /* CQ ring is overflown */
+#define IORING_SQ_TASKRUN	(1U << 2) /* task should enter the kernel */
 
 struct io_cqring_offsets {
 	__u32 head;
@@ -333,6 +384,10 @@ enum {
 	IORING_REGISTER_RING_FDS		= 20,
 	IORING_UNREGISTER_RING_FDS		= 21,
 
+	/* register ring based provide buffer group */
+	IORING_REGISTER_PBUF_RING		= 22,
+	IORING_UNREGISTER_PBUF_RING		= 23,
+
 	/* this goes last */
 	IORING_REGISTER_LAST
 };
@@ -350,9 +405,15 @@ struct io_uring_files_update {
 	__aligned_u64 /* __s32 * */ fds;
 };
 
+/*
+ * Register a fully sparse file space, rather than pass in an array of all
+ * -1 file descriptors.
+ */
+#define IORING_RSRC_REGISTER_SPARSE	(1U << 0)
+
 struct io_uring_rsrc_register {
 	__u32 nr;
-	__u32 resv;
+	__u32 flags;
 	__u64 resv2;
 	__aligned_u64 data;
 	__aligned_u64 tags;
@@ -404,6 +465,38 @@ struct io_uring_restriction {
 	__u32 resv2[3];
 };
 
+struct io_uring_buf {
+	__u64	addr;
+	__u32	len;
+	__u16	bid;
+	__u16	resv;
+};
+
+struct io_uring_buf_ring {
+	union {
+		/*
+		 * To avoid spilling into more pages than we need to, the
+		 * ring tail is overlaid with the io_uring_buf->resv field.
+		 */
+		struct {
+			__u64	resv1;
+			__u32	resv2;
+			__u16	resv3;
+			__u16	tail;
+		};
+		struct io_uring_buf	bufs[0];
+	};
+};
+
+/* argument for IORING_(UN)REGISTER_PBUF_RING */
+struct io_uring_buf_reg {
+	__u64	ring_addr;
+	__u32	ring_entries;
+	__u16	bgid;
+	__u16	pad;
+	__u64	resv[3];
+};
+
 /*
  * io_uring_restriction->opcode values
  */

kernel/task_work.c

@@ -12,12 +12,22 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */
  * @notify: how to notify the targeted task
  *
  * Queue @work for task_work_run() below and notify the @task if @notify
- * is @TWA_RESUME or @TWA_SIGNAL. @TWA_SIGNAL works like signals, in that the
+ * is @TWA_RESUME, @TWA_SIGNAL, or @TWA_SIGNAL_NO_IPI.
- * it will interrupt the targeted task and run the task_work. @TWA_RESUME
+ *
- * work is run only when the task exits the kernel and returns to user mode,
+ * @TWA_SIGNAL works like signals, in that the it will interrupt the targeted
- * or before entering guest mode. Fails if the @task is exiting/exited and thus
+ * task and run the task_work, regardless of whether the task is currently
- * it can't process this @work. Otherwise @work->func() will be called when the
+ * running in the kernel or userspace.
- * @task goes through one of the aforementioned transitions, or exits.
+ * @TWA_SIGNAL_NO_IPI works like @TWA_SIGNAL, except it doesn't send a
+ * reschedule IPI to force the targeted task to reschedule and run task_work.
+ * This can be advantageous if there's no strict requirement that the
+ * task_work be run as soon as possible, just whenever the task enters the
+ * kernel anyway.
+ * @TWA_RESUME work is run only when the task exits the kernel and returns to
+ * user mode, or before entering guest mode.
+ *
+ * Fails if the @task is exiting/exited and thus it can't process this @work.
+ * Otherwise @work->func() will be called when the @task goes through one of
+ * the aforementioned transitions, or exits.
  *
  * If the targeted task is exiting, then an error is returned and the work item
  * is not queued. It's up to the caller to arrange for an alternative mechanism
@@ -53,6 +63,9 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
 	case TWA_SIGNAL:
 		set_notify_signal(task);
 		break;
+	case TWA_SIGNAL_NO_IPI:
+		__set_notify_signal(task);
+		break;
 	default:
 		WARN_ON_ONCE(1);
 		break;