io_uring: add support for 128-byte SQEs

Normal SQEs are 64-bytes in length, which is fine for all the commands
we support. However, in preparation for supporting passthrough IO,
provide an option for setting up a ring with 128-byte SQEs.

We continue to use the same type for io_uring_sqe, it's marked and
commented with a zero sized array pad at the end. This provides up
to 80 bytes of data for a passthrough command - 64 bytes for the
extra added data, and 16 bytes available at the end of the existing
SQE.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 53e54fc..106a0db 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8519,8 +8519,12 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
         *    though the application is the one updating it.
         */
        head = READ_ONCE(ctx->sq_array[sq_idx]);
-       if (likely(head < ctx->sq_entries))
+       if (likely(head < ctx->sq_entries)) {
+               /* double index for 128-byte SQEs, twice as long */
+               if (ctx->flags & IORING_SETUP_SQE128)
+                       head <<= 1;
                return &ctx->sq_sqes[head];
+       }
 
        /* drop invalid entries */
        ctx->cq_extra--;
@@ -11689,7 +11693,10 @@ static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
        rings->sq_ring_entries = p->sq_entries;
        rings->cq_ring_entries = p->cq_entries;
 
-       size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
+       if (p->flags & IORING_SETUP_SQE128)
+               size = array_size(2 * sizeof(struct io_uring_sqe), p->sq_entries);
+       else
+               size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
        if (size == SIZE_MAX) {
                io_mem_free(ctx->rings);
                ctx->rings = NULL;
@@ -11933,7 +11940,8 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
                        IORING_SETUP_SQ_AFF | IORING_SETUP_CQSIZE |
                        IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ |
                        IORING_SETUP_R_DISABLED | IORING_SETUP_SUBMIT_ALL |
-                       IORING_SETUP_COOP_TASKRUN | IORING_SETUP_TASKRUN_FLAG))
+                       IORING_SETUP_COOP_TASKRUN | IORING_SETUP_TASKRUN_FLAG |
+                       IORING_SETUP_SQE128))
                return -EINVAL;
 
        return io_uring_create(entries, &p, params);

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 31e719f..ee84132 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -63,6 +63,12 @@ struct io_uring_sqe {
        };
        __u64   addr3;
        __u64   __pad2[1];
+
+       /*
+        * If the ring is initialized with IORING_SETUP_SQE128, then this field
+        * contains 64-bytes of padding, doubling the size of the SQE.
+        */
+       __u64   __big_sqe_pad[0];
 };
 
 enum {
@@ -119,6 +125,8 @@ enum {
  */
 #define IORING_SETUP_TASKRUN_FLAG      (1U << 9)
 
+#define IORING_SETUP_SQE128            (1U << 10) /* SQEs are 128 byte */
+
 enum io_uring_op {
        IORING_OP_NOP,
        IORING_OP_READV,