[PATCH 5/8] io_uring: draft files cancel based on inflight cnt

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

Do same thing for files cancellation as we do for task cancellations, in
particular keep trying to cancel while corresponding inflight counters
are not zero.

It's a preparation patch, io_uring_try_task_cancel still guarantees to
kill all requests matching files at first attempt. It also deduplicate a
bit those two functions allowing exporting only __io_uring_task_cancel()
from them to the core.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c            | 29 +++++++++++++++--------------
 include/linux/io_uring.h | 12 +++++-------
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1794ad4bfa39..d20a2a96c3f8 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8909,7 +8909,7 @@ static void io_uring_attempt_task_drop(struct file *file)
 		io_uring_del_task_file(current->io_uring, file);
 }
 
-void __io_uring_files_cancel(struct files_struct *files)
+static void io_uring_try_task_cancel(struct files_struct *files)
 {
 	struct io_uring_task *tctx = current->io_uring;
 	struct file *file;
@@ -8917,15 +8917,8 @@ void __io_uring_files_cancel(struct files_struct *files)
 
 	/* make sure overflow events are dropped */
 	atomic_inc(&tctx->in_idle);
-
-	xa_for_each(&tctx->xa, index, file) {
-		struct io_ring_ctx *ctx = file->private_data;
-
-		io_uring_cancel_task_requests(ctx, files);
-		if (files)
-			io_uring_del_task_file(tctx, file);
-	}
-
+	xa_for_each(&tctx->xa, index, file)
+		io_uring_cancel_task_requests(file->private_data, files);
 	atomic_dec(&tctx->in_idle);
 }
 
@@ -8968,7 +8961,7 @@ static s64 tctx_inflight(struct io_uring_task *tctx, bool files)
  * Find any io_uring fd that this task has registered or done IO on, and cancel
  * requests.
  */
-void __io_uring_task_cancel(void)
+void __io_uring_task_cancel(struct files_struct *files)
 {
 	struct io_uring_task *tctx = current->io_uring;
 	DEFINE_WAIT(wait);
@@ -8979,10 +8972,10 @@ void __io_uring_task_cancel(void)
 
 	do {
 		/* read completions before cancelations */
-		inflight = tctx_inflight(tctx, false);
+		inflight = tctx_inflight(tctx, !!files);
 		if (!inflight)
 			break;
-		__io_uring_files_cancel(NULL);
+		io_uring_try_task_cancel(files);
 
 		prepare_to_wait(&tctx->wait, &wait, TASK_UNINTERRUPTIBLE);
 
@@ -8990,13 +8983,21 @@ void __io_uring_task_cancel(void)
 		 * If we've seen completions, retry. This avoids a race where
 		 * a completion comes in before we did prepare_to_wait().
 		 */
-		if (inflight != tctx_inflight(tctx, false))
+		if (inflight != tctx_inflight(tctx, !!files))
 			continue;
 		schedule();
 	} while (1);
 
 	finish_wait(&tctx->wait, &wait);
 	atomic_dec(&tctx->in_idle);
+
+	if (files) {
+		struct file *file;
+		unsigned long index;
+
+		xa_for_each(&tctx->xa, index, file)
+			io_uring_del_task_file(tctx, file);
+	}
 }
 
 static int io_uring_flush(struct file *file, void *data)
diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index e1ff6f235d03..282f02bd04a5 100644
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -37,19 +37,17 @@ struct io_uring_task {
 
 #if defined(CONFIG_IO_URING)
 struct sock *io_uring_get_socket(struct file *file);
-void __io_uring_task_cancel(void);
-void __io_uring_files_cancel(struct files_struct *files);
+void __io_uring_task_cancel(struct files_struct *files);
 void __io_uring_free(struct task_struct *tsk);
 
-static inline void io_uring_task_cancel(void)
+static inline void io_uring_files_cancel(struct files_struct *files)
 {
 	if (current->io_uring && !xa_empty(&current->io_uring->xa))
-		__io_uring_task_cancel();
+		__io_uring_task_cancel(files);
 }
-static inline void io_uring_files_cancel(struct files_struct *files)
+static inline void io_uring_task_cancel(void)
 {
-	if (current->io_uring && !xa_empty(&current->io_uring->xa))
-		__io_uring_files_cancel(files);
+	io_uring_files_cancel(NULL);
 }
 static inline void io_uring_free(struct task_struct *tsk)
 {
-- 
2.24.0