io_uring: support CLOCK_BOOTTIME/REALTIME for timeouts

Certain use cases want to use CLOCK_BOOTTIME or CLOCK_REALTIME rather than
CLOCK_MONOTONIC, instead of the default CLOCK_MONOTONIC.

Add an IORING_TIMEOUT_BOOTTIME and IORING_TIMEOUT_REALTIME flag that
allows timeouts and linked timeouts to use the selected clock source.

Only one clock source may be selected, and we -EINVAL the request if more
than one is given. If neither BOOTIME nor REALTIME are selected, the
previous default of MONOTONIC is used.

Link: https://github.com/axboe/liburing/issues/369
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index edbda88..1c99f01 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -508,6 +508,7 @@ struct io_timeout_data {
        struct hrtimer                  timer;
        struct timespec64               ts;
        enum hrtimer_mode               mode;
+       u32                             flags;
 };
 
 struct io_accept {
@@ -5712,6 +5713,22 @@ static int io_timeout_cancel(struct io_ring_ctx *ctx, __u64 user_data)
        return 0;
 }
 
+static clockid_t io_timeout_get_clock(struct io_timeout_data *data)
+{
+       switch (data->flags & IORING_TIMEOUT_CLOCK_MASK) {
+       case IORING_TIMEOUT_BOOTTIME:
+               return CLOCK_BOOTTIME;
+       case IORING_TIMEOUT_REALTIME:
+               return CLOCK_REALTIME;
+       default:
+               /* can't happen, vetted at prep time */
+               WARN_ON_ONCE(1);
+               fallthrough;
+       case 0:
+               return CLOCK_MONOTONIC;
+       }
+}
+
 static int io_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
                             struct timespec64 *ts, enum hrtimer_mode mode)
        __must_hold(&ctx->timeout_lock)
@@ -5725,7 +5742,7 @@ static int io_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
        req->timeout.off = 0; /* noseq */
        data = req->async_data;
        list_add_tail(&req->timeout.list, &ctx->timeout_list);
-       hrtimer_init(&data->timer, CLOCK_MONOTONIC, mode);
+       hrtimer_init(&data->timer, io_timeout_get_clock(data), mode);
        data->timer.function = io_timeout_fn;
        hrtimer_start(&data->timer, timespec64_to_ktime(*ts), mode);
        return 0;
@@ -5807,7 +5824,10 @@ static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
        if (off && is_timeout_link)
                return -EINVAL;
        flags = READ_ONCE(sqe->timeout_flags);
-       if (flags & ~IORING_TIMEOUT_ABS)
+       if (flags & ~(IORING_TIMEOUT_ABS | IORING_TIMEOUT_CLOCK_MASK))
+               return -EINVAL;
+       /* more than one clock specified is invalid, obviously */
+       if (hweight32(flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
                return -EINVAL;
 
        req->timeout.off = off;
@@ -5819,12 +5839,13 @@ static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 
        data = req->async_data;
        data->req = req;
+       data->flags = flags;
 
        if (get_timespec64(&data->ts, u64_to_user_ptr(sqe->addr)))
                return -EFAULT;
 
        data->mode = io_translate_timeout_mode(flags);
-       hrtimer_init(&data->timer, CLOCK_MONOTONIC, data->mode);
+       hrtimer_init(&data->timer, io_timeout_get_clock(data), data->mode);
 
        if (is_timeout_link) {
                struct io_submit_link *link = &req->ctx->submit_state.link;

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 64fe809..b6d28d9 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -151,6 +151,9 @@ enum {
  */
 #define IORING_TIMEOUT_ABS     (1U << 0)
 #define IORING_TIMEOUT_UPDATE  (1U << 1)
+#define IORING_TIMEOUT_BOOTTIME        (1U << 2)
+#define IORING_TIMEOUT_REALTIME        (1U << 3)
+#define IORING_TIMEOUT_CLOCK_MASK      (IORING_TIMEOUT_BOOTTIME | IORING_TIMEOUT_REALTIME)
 
 /*
  * sqe->splice_flags