[PATCH 6/8] io_uring: remove old files cancel mechanism

[Pavel Begunkov <asml.silence@gmail.com>]

files cancellation is now based on counters, remove the old way we were
doing that with keeping a list of such requests.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 65 +++++++--------------------------------------------
 1 file changed, 9 insertions(+), 56 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index d20a2a96c3f8..4bf709d9db32 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -379,7 +379,6 @@ struct io_ring_ctx {
 		bool			poll_multi_file;
 
 		spinlock_t		inflight_lock;
-		struct list_head	inflight_list;
 	} ____cacheline_aligned_in_smp;
 
 	struct delayed_work		file_put_work;
@@ -719,10 +718,7 @@ struct io_kiocb {
 	struct io_kiocb			*link;
 	struct percpu_ref		*fixed_file_refs;
 
-	/*
-	 * 1. used with ctx->iopoll_list with reads/writes
-	 * 2. to track reqs with ->files (see io_op_def::file_table)
-	 */
+	/* ctx->iopoll_list, tracks rw requests for iopoll_list */
 	struct list_head		inflight_entry;
 	struct callback_head		task_work;
 	/* for polled requests, i.e. IORING_OP_POLL_ADD and async armed poll */
@@ -1308,7 +1304,6 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	INIT_LIST_HEAD(&ctx->defer_list);
 	INIT_LIST_HEAD(&ctx->timeout_list);
 	spin_lock_init(&ctx->inflight_lock);
-	INIT_LIST_HEAD(&ctx->inflight_list);
 	INIT_DELAYED_WORK(&ctx->file_put_work, io_file_put_work);
 	init_llist_head(&ctx->file_put_llist);
 	return ctx;
@@ -1498,7 +1493,6 @@ static bool io_grab_identity(struct io_kiocb *req)
 
 		spin_lock_irq(&ctx->inflight_lock);
 		atomic_inc(&current->io_uring->inflight_files);
-		list_add(&req->inflight_entry, &ctx->inflight_list);
 		spin_unlock_irq(&ctx->inflight_lock);
 		req->work.flags |= IO_WQ_WORK_FILES;
 	}
@@ -6101,7 +6095,6 @@ static void io_req_drop_files(struct io_kiocb *req)
 	put_files_struct(req->work.identity->files);
 	put_nsproxy(req->work.identity->nsproxy);
 	spin_lock_irqsave(&ctx->inflight_lock, flags);
-	list_del(&req->inflight_entry);
 	atomic_dec(&tctx->inflight_files);
 	spin_unlock_irqrestore(&ctx->inflight_lock, flags);
 	req->flags &= ~REQ_F_INFLIGHT;
@@ -8739,48 +8732,12 @@ static void io_cancel_defer_files(struct io_ring_ctx *ctx,
 	}
 }
 
-static void io_uring_cancel_files(struct io_ring_ctx *ctx,
-				  struct task_struct *task,
-				  struct files_struct *files)
-{
-	while (!list_empty_careful(&ctx->inflight_list)) {
-		struct io_task_cancel cancel = { .task = task, .files = files };
-		struct io_kiocb *req;
-		DEFINE_WAIT(wait);
-		bool found = false;
-
-		spin_lock_irq(&ctx->inflight_lock);
-		list_for_each_entry(req, &ctx->inflight_list, inflight_entry) {
-			if (req->task != task ||
-			    req->work.identity->files != files)
-				continue;
-			found = true;
-			break;
-		}
-		if (found)
-			prepare_to_wait(&task->io_uring->wait, &wait,
-					TASK_UNINTERRUPTIBLE);
-		spin_unlock_irq(&ctx->inflight_lock);
-
-		/* We need to keep going until we don't find a matching req */
-		if (!found)
-			break;
-
-		io_wq_cancel_cb(ctx->io_wq, io_cancel_task_cb, &cancel, true);
-		io_poll_remove_all(ctx, task, files);
-		io_kill_timeouts(ctx, task, files);
-		/* cancellations _may_ trigger task work */
-		io_run_task_work();
-		schedule();
-		finish_wait(&task->io_uring->wait, &wait);
-	}
-}
-
 static void __io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
-					    struct task_struct *task)
+					    struct task_struct *task,
+					    struct files_struct *files)
 {
 	while (1) {
-		struct io_task_cancel cancel = { .task = task, .files = NULL, };
+		struct io_task_cancel cancel = { .task = task, .files = files };
 		enum io_wq_cancel cret;
 		bool ret = false;
 
@@ -8789,18 +8746,18 @@ static void __io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
 			ret = true;
 
 		/* SQPOLL thread does its own polling */
-		if (!(ctx->flags & IORING_SETUP_SQPOLL)) {
+		if (!(ctx->flags & IORING_SETUP_SQPOLL) && !files) {
 			while (!list_empty_careful(&ctx->iopoll_list)) {
 				io_iopoll_try_reap_events(ctx);
 				ret = true;
 			}
 		}
 
-		ret |= io_poll_remove_all(ctx, task, NULL);
-		ret |= io_kill_timeouts(ctx, task, NULL);
+		ret |= io_poll_remove_all(ctx, task, files);
+		ret |= io_kill_timeouts(ctx, task, files);
+		io_run_task_work();
 		if (!ret)
 			break;
-		io_run_task_work();
 		cond_resched();
 	}
 }
@@ -8825,11 +8782,7 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
 	io_ring_submit_lock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));
 	io_cqring_overflow_flush(ctx, true, task, files);
 	io_ring_submit_unlock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));
-
-	if (!files)
-		__io_uring_cancel_task_requests(ctx, task);
-	else
-		io_uring_cancel_files(ctx, task, files);
+	__io_uring_cancel_task_requests(ctx, task, files);
 
 	if ((ctx->flags & IORING_SETUP_SQPOLL) && ctx->sq_data) {
 		atomic_dec(&task->io_uring->in_idle);
-- 
2.24.0