From 9ac7b993a71c1459eb707b596adf9f9a4e722651 Mon Sep 17 00:00:00 2001
From: Lucas DRAESCHER <git@draescher.fr>
Date: Tue, 17 Mar 2026 17:26:11 +0100
Subject: [PATCH v3] Release io_uring resources on shmem exit

io_uring_queue_init() allocates resources for each io_uring
instance, but pgaio_uring_shmem_init() never registers a
cleanup callback to free them.

Add a shmem_cleanup callback to IoMethodOps registered in
AioShmemInit().

Implement the shmem_cleanup for method_io_uring.c as
pgaio_uring_shmem_cleanup() which calls
io_uring_queue_exit().
---
 src/backend/storage/aio/aio_init.c        | 18 ++++++++++++++++++
 src/backend/storage/aio/method_io_uring.c | 18 ++++++++++++++++++
 src/include/storage/aio_internal.h        |  6 ++++++
 3 files changed, 42 insertions(+)

diff --git a/src/backend/storage/aio/aio_init.c b/src/backend/storage/aio/aio_init.c
index da30d792a88..0f3572d4dba 100644
--- a/src/backend/storage/aio/aio_init.c
+++ b/src/backend/storage/aio/aio_init.c
@@ -172,6 +172,20 @@ AioShmemRequest(void *arg)
 		pgaio_method_ops->shmem_callbacks.request_fn(pgaio_method_ops->shmem_callbacks.opaque_arg);
 }
 
+/*
+ * Wrapper around pgaio_method_ops->shmem_cleanup to satisfy the
+ * on_shmem_exit() callback signature.
+ */
+static void
+pgaio_shmem_cleanup(int code, Datum arg)
+{
+	/*
+	 * No null check needed here; AioShmemInit only registers this callback
+	 * when shmem_cleanup is non-null.
+	 */
+	pgaio_method_ops->shmem_cleanup();
+}
+
 /*
  * Initialize AIO shared memory during postmaster startup.
  */
@@ -225,6 +239,10 @@ AioShmemInit(void *arg)
 
 	if (pgaio_method_ops->shmem_callbacks.init_fn)
 		pgaio_method_ops->shmem_callbacks.init_fn(pgaio_method_ops->shmem_callbacks.opaque_arg);
+
+	/* Register callback to release any resources allocated above. */
+	if (pgaio_method_ops->shmem_cleanup)
+		on_shmem_exit(pgaio_shmem_cleanup, 0);
 }
 
 static void
diff --git a/src/backend/storage/aio/method_io_uring.c b/src/backend/storage/aio/method_io_uring.c
index c0f9fc9c303..09f36102920 100644
--- a/src/backend/storage/aio/method_io_uring.c
+++ b/src/backend/storage/aio/method_io_uring.c
@@ -51,6 +51,7 @@
 /* Entry points for IoMethodOps. */
 static void pgaio_uring_shmem_request(void *arg);
 static void pgaio_uring_shmem_init(void *arg);
+static void pgaio_uring_shmem_cleanup(void);
 static void pgaio_uring_init_backend(void);
 static int	pgaio_uring_submit(uint16 num_staged_ios, PgAioHandle **staged_ios);
 static void pgaio_uring_wait_one(PgAioHandle *ioh, uint64 ref_generation);
@@ -72,6 +73,7 @@ const IoMethodOps pgaio_uring_ops = {
 
 	.shmem_callbacks.request_fn = pgaio_uring_shmem_request,
 	.shmem_callbacks.init_fn = pgaio_uring_shmem_init,
+	.shmem_cleanup = pgaio_uring_shmem_cleanup,
 	.init_backend = pgaio_uring_init_backend,
 
 	.submit = pgaio_uring_submit,
@@ -403,6 +405,22 @@ pgaio_uring_shmem_init(void *arg)
 	}
 }
 
+static void
+pgaio_uring_shmem_cleanup(void)
+{
+	if (pgaio_uring_contexts != NULL)
+	{
+		int			TotalProcs = pgaio_uring_procs();
+
+		elog(DEBUG1, "cleaning up %d io_uring processes", TotalProcs);
+
+		for (int i = 0; i < TotalProcs; i++)
+			io_uring_queue_exit(&pgaio_uring_contexts[i].io_uring_ring);
+
+		pgaio_uring_contexts = NULL;
+	}
+}
+
 static void
 pgaio_uring_init_backend(void)
 {
diff --git a/src/include/storage/aio_internal.h b/src/include/storage/aio_internal.h
index 9ca4087aa7f..96a3f86ea97 100644
--- a/src/include/storage/aio_internal.h
+++ b/src/include/storage/aio_internal.h
@@ -272,6 +272,12 @@ typedef struct IoMethodOps
 	/* global initialization */
 	ShmemCallbacks shmem_callbacks;
 
+	/*
+	 * Clean up shared memory resources before shutdown. Called during shmem
+	 * exit. Optional.
+	 */
+	void		(*shmem_cleanup) (void);
+
 	/*
 	 * Per-backend initialization. Optional.
 	 */
-- 
2.53.0