Commit 500a373d authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: assign new io_identity for task if members have changed 



This avoids doing a copy for each new async IO, if some parts of the
io_identity has changed. We avoid reference counting for the normal
fast path of nothing ever changing.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5c3462cf

fs/io_uring.c

+15 −4
Original line number Diff line number Diff line
@@ -1066,12 +1066,18 @@ static void io_init_identity(struct io_identity *id) 
 */

static inline void io_req_init_async(struct io_kiocb *req)

{

	struct io_uring_task *tctx = current->io_uring;



	if (req->flags & REQ_F_WORK_INITIALIZED)

		return;



	memset(&req->work, 0, sizeof(req->work));

	req->flags |= REQ_F_WORK_INITIALIZED;

	req->work.identity = &current->io_uring->identity;



	/* Grab a ref if this isn't our static identity */

	req->work.identity = tctx->identity;

	if (tctx->identity != &tctx->__identity)

		refcount_inc(&req->work.identity->count);

}



static inline bool io_async_submit(struct io_ring_ctx *ctx)
@@ -1179,7 +1185,7 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx) 


static void io_put_identity(struct io_uring_task *tctx, struct io_kiocb *req)

{

	if (req->work.identity == &tctx->identity)

	if (req->work.identity == &tctx->__identity)

		return;

	if (refcount_dec_and_test(&req->work.identity->count))

		kfree(req->work.identity);
@@ -1254,11 +1260,12 @@ static bool io_identity_cow(struct io_kiocb *req) 
	refcount_inc(&id->count);



	/* drop old identity, assign new one. one ref for req, one for tctx */

	if (req->work.identity != &tctx->identity &&

	if (req->work.identity != tctx->identity &&

	    refcount_sub_and_test(2, &req->work.identity->count))

		kfree(req->work.identity);



	req->work.identity = id;

	tctx->identity = id;

	return true;

}
@@ -7691,7 +7698,8 @@ static int io_uring_alloc_task_context(struct task_struct *task) 
	tctx->in_idle = 0;

	atomic_long_set(&tctx->req_issue, 0);

	atomic_long_set(&tctx->req_complete, 0);

	io_init_identity(&tctx->identity);

	io_init_identity(&tctx->__identity);

	tctx->identity = &tctx->__identity;

	task->io_uring = tctx;

	return 0;

}
@@ -7701,6 +7709,9 @@ void __io_uring_free(struct task_struct *tsk) 
	struct io_uring_task *tctx = tsk->io_uring;



	WARN_ON_ONCE(!xa_empty(&tctx->xa));

	WARN_ON_ONCE(refcount_read(&tctx->identity->count) != 1);

	if (tctx->identity != &tctx->__identity)

		kfree(tctx->identity);

	kfree(tctx);

	tsk->io_uring = NULL;

}

include/linux/io_uring.h

+2 −1
Original line number Diff line number Diff line
@@ -24,7 +24,8 @@ struct io_uring_task { 
	struct wait_queue_head	wait;

	struct file		*last;

	atomic_long_t		req_issue;

	struct io_identity	identity;

	struct io_identity	__identity;

	struct io_identity	*identity;



	/* completion side */

	bool			in_idle ____cacheline_aligned_in_smp;