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io_uring: add support for 128-byte SQEs

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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>
This commit is contained in:
Jens Axboe 2022-03-31 19:27:52 -06:00
parent b5ba65df47
commit ebdeb7c01d
2 changed files with 19 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

14
fs/io_uring.c
View file

@ -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);

8
include/uapi/linux/io_uring.h
View file

@ -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,