io_uring: add support for link with drain
To support the link with drain, we need to do two parts.
There is an sqes:
0 1 2 3 4 5 6
+-----+-----+-----+-----+-----+-----+-----+
| N | L | L | L+D | N | N | N |
+-----+-----+-----+-----+-----+-----+-----+
First, we need to ensure that the io before the link is completed,
there is a easy way is set drain flag to the link list's head, so
all subsequent io will be inserted into the defer_list.
+-----+
(0) | N |
+-----+
| (2) (3) (4)
+-----+ +-----+ +-----+ +-----+
(1) | L+D | --> | L | --> | L+D | --> | N |
+-----+ +-----+ +-----+ +-----+
|
+-----+
(5) | N |
+-----+
|
+-----+
(6) | N |
+-----+
Second, ensure that the following IO will not be completed first,
an easy way is to create a mirror of drain io and insert it into
defer_list, in this way, as long as drain io is not processed, the
following io in the defer_list will not be actively process.
+-----+
(0) | N |
+-----+
| (2) (3) (4)
+-----+ +-----+ +-----+ +-----+
(1) | L+D | --> | L | --> | L+D | --> | N |
+-----+ +-----+ +-----+ +-----+
|
+-----+
('3) | D | <== This is a shadow of (3)
+-----+
|
+-----+
(5) | N |
+-----+
|
+-----+
(6) | N |
+-----+
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jackie Liu
Jens Axboe
Родитель
8776f3fa15
Коммит
4fe2c96315
112
fs/io_uring.c
112
fs/io_uring.c
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@ -312,6 +312,7 @@ struct io_kiocb {
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#define REQ_F_LINK 64 /* linked sqes */
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#define REQ_F_LINK_DONE 128 /* linked sqes done */
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#define REQ_F_FAIL_LINK 256 /* fail rest of links */
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#define REQ_F_SHADOW_DRAIN 512 /* link-drain shadow req */
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u64 user_data;
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u32 result;
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u32 sequence;
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@ -343,6 +344,7 @@ struct io_submit_state {
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};
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static void io_sq_wq_submit_work(struct work_struct *work);
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static void __io_free_req(struct io_kiocb *req);
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static struct kmem_cache *req_cachep;
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@ -448,6 +450,11 @@ static void io_commit_cqring(struct io_ring_ctx *ctx)
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__io_commit_cqring(ctx);
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while ((req = io_get_deferred_req(ctx)) != NULL) {
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if (req->flags & REQ_F_SHADOW_DRAIN) {
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/* Just for drain, free it. */
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__io_free_req(req);
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continue;
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}
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req->flags |= REQ_F_IO_DRAINED;
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queue_work(ctx->sqo_wq, &req->work);
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}
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@ -2015,10 +2022,14 @@ static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
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flags = READ_ONCE(s->sqe->flags);
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fd = READ_ONCE(s->sqe->fd);
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if (flags & IOSQE_IO_DRAIN) {
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if (flags & IOSQE_IO_DRAIN)
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req->flags |= REQ_F_IO_DRAIN;
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/*
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* All io need record the previous position, if LINK vs DARIN,
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* it can be used to mark the position of the first IO in the
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* link list.
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*/
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req->sequence = s->sequence;
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}
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if (!io_op_needs_file(s->sqe))
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return 0;
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@ -2040,20 +2051,11 @@ static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
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return 0;
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}
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static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
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static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
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struct sqe_submit *s)
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{
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int ret;
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ret = io_req_defer(ctx, req, s->sqe);
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if (ret) {
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if (ret != -EIOCBQUEUED) {
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io_free_req(req);
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io_cqring_add_event(ctx, s->sqe->user_data, ret);
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}
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return 0;
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}
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ret = __io_submit_sqe(ctx, req, s, true);
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if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) {
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struct io_uring_sqe *sqe_copy;
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@ -2096,6 +2098,64 @@ static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
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return ret;
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}
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static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
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struct sqe_submit *s)
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{
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int ret;
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ret = io_req_defer(ctx, req, s->sqe);
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if (ret) {
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if (ret != -EIOCBQUEUED) {
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io_free_req(req);
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io_cqring_add_event(ctx, s->sqe->user_data, ret);
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}
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return 0;
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}
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return __io_queue_sqe(ctx, req, s);
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}
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static int io_queue_link_head(struct io_ring_ctx *ctx, struct io_kiocb *req,
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struct sqe_submit *s, struct io_kiocb *shadow)
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{
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int ret;
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int need_submit = false;
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if (!shadow)
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return io_queue_sqe(ctx, req, s);
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/*
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* Mark the first IO in link list as DRAIN, let all the following
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* IOs enter the defer list. all IO needs to be completed before link
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* list.
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*/
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req->flags |= REQ_F_IO_DRAIN;
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ret = io_req_defer(ctx, req, s->sqe);
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if (ret) {
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if (ret != -EIOCBQUEUED) {
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io_free_req(req);
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io_cqring_add_event(ctx, s->sqe->user_data, ret);
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return 0;
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}
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} else {
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/*
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* If ret == 0 means that all IOs in front of link io are
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* running done. let's queue link head.
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*/
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need_submit = true;
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}
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/* Insert shadow req to defer_list, blocking next IOs */
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spin_lock_irq(&ctx->completion_lock);
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list_add_tail(&shadow->list, &ctx->defer_list);
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spin_unlock_irq(&ctx->completion_lock);
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if (need_submit)
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return __io_queue_sqe(ctx, req, s);
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return 0;
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}
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#define SQE_VALID_FLAGS (IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK)
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static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
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@ -2241,6 +2301,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
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{
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struct io_submit_state state, *statep = NULL;
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struct io_kiocb *link = NULL;
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struct io_kiocb *shadow_req = NULL;
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bool prev_was_link = false;
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int i, submitted = 0;
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@ -2255,11 +2316,20 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
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* that's the end of the chain. Submit the previous link.
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*/
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if (!prev_was_link && link) {
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io_queue_sqe(ctx, link, &link->submit);
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io_queue_link_head(ctx, link, &link->submit, shadow_req);
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link = NULL;
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}
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prev_was_link = (sqes[i].sqe->flags & IOSQE_IO_LINK) != 0;
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if (link && (sqes[i].sqe->flags & IOSQE_IO_DRAIN)) {
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if (!shadow_req) {
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shadow_req = io_get_req(ctx, NULL);
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shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
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refcount_dec(&shadow_req->refs);
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}
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shadow_req->sequence = sqes[i].sequence;
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}
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if (unlikely(mm_fault)) {
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io_cqring_add_event(ctx, sqes[i].sqe->user_data,
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-EFAULT);
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@ -2273,7 +2343,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
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}
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if (link)
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io_queue_sqe(ctx, link, &link->submit);
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io_queue_link_head(ctx, link, &link->submit, shadow_req);
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if (statep)
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io_submit_state_end(&state);
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@ -2409,6 +2479,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
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{
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struct io_submit_state state, *statep = NULL;
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struct io_kiocb *link = NULL;
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struct io_kiocb *shadow_req = NULL;
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bool prev_was_link = false;
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int i, submit = 0;
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@ -2428,11 +2499,20 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
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* that's the end of the chain. Submit the previous link.
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*/
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if (!prev_was_link && link) {
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io_queue_sqe(ctx, link, &link->submit);
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io_queue_link_head(ctx, link, &link->submit, shadow_req);
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link = NULL;
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}
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prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
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if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
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if (!shadow_req) {
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shadow_req = io_get_req(ctx, NULL);
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shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
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refcount_dec(&shadow_req->refs);
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}
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shadow_req->sequence = s.sequence;
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}
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s.has_user = true;
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s.needs_lock = false;
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s.needs_fixed_file = false;
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@ -2442,7 +2522,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
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io_commit_sqring(ctx);
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if (link)
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io_queue_sqe(ctx, link, &link->submit);
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io_queue_link_head(ctx, link, &link->submit, shadow_req);
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if (statep)
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io_submit_state_end(statep);
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