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io_uring: don't cache number of dropped SQEs 

Kill ->cached_sq_dropped and wire DRAIN sequence number correction via
->cq_extra, which is there exactly for that purpose. User visible
dropped counter will be populated by incrementing it instead of keeping
a copy, similarly as it was done not so long ago with cq_overflow.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/088aceb2707a534d531e2770267c4498e0507cc1.1623709150.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-06-14 23:37:24 +01:00 committed by Jens Axboe
parent 17d3aeb33c
commit 15641e4270
1 changed files with 5 additions and 7 deletions
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12
fs/io_uring.c
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@ -370,7 +370,6 @@ struct io_ring_ctx {
struct io_uring_sqe *sq_sqes;
unsigned cached_sq_head;
unsigned sq_entries;
unsigned cached_sq_dropped;
unsigned long sq_check_overflow;
struct list_head defer_list;
@ -5994,13 +5993,11 @@ static u32 io_get_sequence(struct io_kiocb *req)
{
struct io_kiocb *pos;
struct io_ring_ctx *ctx = req->ctx;
u32 total_submitted, nr_reqs = 0;
u32 nr_reqs = 0;
io_for_each_link(pos, req)
nr_reqs++;
total_submitted = ctx->cached_sq_head - ctx->cached_sq_dropped;
return total_submitted - nr_reqs;
return ctx->cached_sq_head - nr_reqs;
}
static int io_req_defer(struct io_kiocb *req)
@ -6701,8 +6698,9 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
return &ctx->sq_sqes[head];
/* drop invalid entries */
ctx->cached_sq_dropped++;
WRITE_ONCE(ctx->rings->sq_dropped, ctx->cached_sq_dropped);
ctx->cq_extra--;
WRITE_ONCE(ctx->rings->sq_dropped,
READ_ONCE(ctx->rings->sq_dropped) + 1);
return NULL;
}