v7-0016-Convert-AIO-to-the-new-interface.patch

From 589948c6e44b99133fc6ce46ee9de33a254f4d11 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Sat, 21 Mar 2026 12:43:16 +0200
Subject: [PATCH v7 16/18] Convert AIO to the new interface

This replaces the "shmem_size" and "shmem_init" callbacks in the IO
methods table with the same ShmemCallback struct that we now use in
other subsystems
---
 src/backend/storage/aio/aio_init.c        | 119 ++++++++++++++--------
 src/backend/storage/aio/method_io_uring.c |  42 ++++----
 src/backend/storage/aio/method_worker.c   |  84 ++++++++-------
 src/backend/storage/ipc/ipci.c            |   2 -
 src/include/storage/aio_internal.h        |  16 +--
 src/include/storage/aio_subsys.h          |   4 -
 src/include/storage/subsystemlist.h       |   3 +
 7 files changed, 155 insertions(+), 115 deletions(-)

diff --git a/src/backend/storage/aio/aio_init.c b/src/backend/storage/aio/aio_init.c
index d3c68d8b04c..54ab1238131 100644
--- a/src/backend/storage/aio/aio_init.c
+++ b/src/backend/storage/aio/aio_init.c
@@ -23,16 +23,46 @@
 #include "storage/ipc.h"
 #include "storage/proc.h"
 #include "storage/shmem.h"
+#include "storage/subsystems.h"
 #include "utils/guc.h"
 
 
-
-static Size
-AioCtlShmemSize(void)
-{
-	/* pgaio_ctl itself */
-	return sizeof(PgAioCtl);
-}
+static void AioShmemRequest(void *arg);
+static void AioShmemInit(void *arg);
+static void AioShmemAttach(void *arg);
+
+const ShmemCallbacks AioShmemCallbacks = {
+	.request_fn = AioShmemRequest,
+	.init_fn = AioShmemInit,
+	.attach_fn = AioShmemAttach,
+};
+
+static ShmemStructDesc AioCtlShmemDesc = {
+	.name = "AioCtl",
+	.size = sizeof(PgAioCtl),
+	.ptr = (void **) &pgaio_ctl,
+};
+
+static PgAioBackend *AioBackendShmemPtr;
+static ShmemStructDesc AioBackendShmemDesc = {
+	.name = "AioBackend",
+	.ptr = (void **) &AioBackendShmemPtr,
+};
+static PgAioHandle *AioHandleShmemPtr;
+static ShmemStructDesc AioHandleShmemDesc = {
+	.name = "AioHandle",
+	.ptr = (void **) &AioHandleShmemPtr,
+};
+static struct iovec *AioHandleIOVShmemPtr;
+static ShmemStructDesc AioHandleIOVShmemDesc = {
+	.name = "AioHandleIOV",
+	.ptr = (void **) &AioHandleIOVShmemPtr,
+};
+static uint64 *AioHandleDataShmemPtr;
+static ShmemStructDesc AioHandleDataShmemDesc = {
+	.name = "AioHandleData",
+	.ptr = (void **) &AioHandleDataShmemPtr,
+};
 
 static uint32
 AioProcs(void)
@@ -109,10 +139,13 @@ AioChooseMaxConcurrency(void)
 	return Min(max_proportional_pins, 64);
 }
 
-Size
-AioShmemSize(void)
+/*
+ * Register shared memory area for AIO subsystem.
+ */
+static void
+AioShmemRequest(void *arg)
 {
-	Size		sz = 0;
+	/* Resolve io_max_concurrency if not already done. */
 
 	/*
 	 * We prefer to report this value's source as PGC_S_DYNAMIC_DEFAULT.
@@ -132,48 +165,41 @@ AioShmemSize(void)
 							PGC_S_OVERRIDE);
 	}
 
-	sz = add_size(sz, AioCtlShmemSize());
-	sz = add_size(sz, AioBackendShmemSize());
-	sz = add_size(sz, AioHandleShmemSize());
-	sz = add_size(sz, AioHandleIOVShmemSize());
-	sz = add_size(sz, AioHandleDataShmemSize());
+	ShmemRequestStruct(&AioCtlShmemDesc);
 
-	/* Reserve space for method specific resources. */
-	if (pgaio_method_ops->shmem_size)
-		sz = add_size(sz, pgaio_method_ops->shmem_size());
+	AioBackendShmemDesc.size = AioBackendShmemSize();
+	ShmemRequestStruct(&AioBackendShmemDesc);
 
-	return sz;
+	AioHandleShmemDesc.size = AioHandleShmemSize();
+	ShmemRequestStruct(&AioHandleShmemDesc);
+
+	AioHandleIOVShmemDesc.size = AioHandleIOVShmemSize();
+	ShmemRequestStruct(&AioHandleIOVShmemDesc);
+
+	AioHandleDataShmemDesc.size = AioHandleDataShmemSize();
+	ShmemRequestStruct(&AioHandleDataShmemDesc);
+
+	if (pgaio_method_ops->shmem_callbacks.request_fn)
+		pgaio_method_ops->shmem_callbacks.request_fn(pgaio_method_ops->shmem_callbacks.request_fn_arg);
 }
 
-void
-AioShmemInit(void)
+/*
+ * Initialize AIO shared memory during postmaster startup.
+ */
+static void
+AioShmemInit(void *arg)
 {
-	bool		found;
 	uint32		io_handle_off = 0;
 	uint32		iovec_off = 0;
 	uint32		per_backend_iovecs = io_max_concurrency * io_max_combine_limit;
 
-	pgaio_ctl = (PgAioCtl *)
-		ShmemInitStruct("AioCtl", AioCtlShmemSize(), &found);
-
-	if (found)
-		goto out;
-
-	memset(pgaio_ctl, 0, AioCtlShmemSize());
-
 	pgaio_ctl->io_handle_count = AioProcs() * io_max_concurrency;
 	pgaio_ctl->iovec_count = AioProcs() * per_backend_iovecs;
 
-	pgaio_ctl->backend_state = (PgAioBackend *)
-		ShmemInitStruct("AioBackend", AioBackendShmemSize(), &found);
-
-	pgaio_ctl->io_handles = (PgAioHandle *)
-		ShmemInitStruct("AioHandle", AioHandleShmemSize(), &found);
-
-	pgaio_ctl->iovecs = (struct iovec *)
-		ShmemInitStruct("AioHandleIOV", AioHandleIOVShmemSize(), &found);
-	pgaio_ctl->handle_data = (uint64 *)
-		ShmemInitStruct("AioHandleData", AioHandleDataShmemSize(), &found);
+	pgaio_ctl->backend_state = AioBackendShmemPtr;
+	pgaio_ctl->io_handles = AioHandleShmemPtr;
+	pgaio_ctl->iovecs = AioHandleIOVShmemPtr;
+	pgaio_ctl->handle_data = AioHandleDataShmemPtr;
 
 	for (int procno = 0; procno < AioProcs(); procno++)
 	{
@@ -208,10 +234,15 @@ AioShmemInit(void)
 		}
 	}
 
-out:
-	/* Initialize IO method specific resources. */
-	if (pgaio_method_ops->shmem_init)
-		pgaio_method_ops->shmem_init(!found);
+	if (pgaio_method_ops->shmem_callbacks.init_fn)
+		pgaio_method_ops->shmem_callbacks.init_fn(pgaio_method_ops->shmem_callbacks.init_fn_arg);
+}
+
+static void
+AioShmemAttach(void *arg)
+{
+	if (pgaio_method_ops->shmem_callbacks.attach_fn)
+		pgaio_method_ops->shmem_callbacks.attach_fn(pgaio_method_ops->shmem_callbacks.attach_fn_arg);
 }
 
 void
diff --git a/src/backend/storage/aio/method_io_uring.c b/src/backend/storage/aio/method_io_uring.c
index 4867ded35ea..df2d01d66fa 100644
--- a/src/backend/storage/aio/method_io_uring.c
+++ b/src/backend/storage/aio/method_io_uring.c
@@ -49,8 +49,8 @@
 
 
 /* Entry points for IoMethodOps. */
-static size_t pgaio_uring_shmem_size(void);
-static void pgaio_uring_shmem_init(bool first_time);
+static void pgaio_uring_shmem_request(void *arg);
+static void pgaio_uring_shmem_init(void *arg);
 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);
@@ -58,7 +58,6 @@ static void pgaio_uring_wait_one(PgAioHandle *ioh, uint64 ref_generation);
 /* helper functions */
 static void pgaio_uring_sq_from_io(PgAioHandle *ioh, struct io_uring_sqe *sqe);
 
-
 const IoMethodOps pgaio_uring_ops = {
 	/*
 	 * While io_uring mostly is OK with FDs getting closed while the IO is in
@@ -69,8 +68,8 @@ const IoMethodOps pgaio_uring_ops = {
 	 */
 	.wait_on_fd_before_close = true,
 
-	.shmem_size = pgaio_uring_shmem_size,
-	.shmem_init = pgaio_uring_shmem_init,
+	.shmem_callbacks.request_fn = pgaio_uring_shmem_request,
+	.shmem_callbacks.init_fn = pgaio_uring_shmem_init,
 	.init_backend = pgaio_uring_init_backend,
 
 	.submit = pgaio_uring_submit,
@@ -265,23 +264,34 @@ pgaio_uring_shmem_size(void)
 {
 	size_t		sz;
 
+	sz = pgaio_uring_context_shmem_size();
+	sz = add_size(sz, pgaio_uring_ring_shmem_size());
+
+	return sz;
+}
+
+static void
+pgaio_uring_shmem_request(void *arg)
+{
+	static ShmemStructDesc AioUringShmemDesc = {
+		.name = "AioUringContext",
+		.ptr = (void **) &pgaio_uring_contexts,
+	};
+
 	/*
 	 * Kernel and liburing support for various features influences how much
 	 * shmem we need, perform the necessary checks.
 	 */
 	pgaio_uring_check_capabilities();
 
-	sz = pgaio_uring_context_shmem_size();
-	sz = add_size(sz, pgaio_uring_ring_shmem_size());
-
-	return sz;
+	AioUringShmemDesc.size = pgaio_uring_shmem_size();
+	ShmemRequestStruct(&AioUringShmemDesc);
 }
 
 static void
-pgaio_uring_shmem_init(bool first_time)
+pgaio_uring_shmem_init(void *arg)
 {
 	int			TotalProcs = pgaio_uring_procs();
-	bool		found;
 	char	   *shmem;
 	size_t		ring_mem_remain = 0;
 	char	   *ring_mem_next = 0;
@@ -289,13 +299,11 @@ pgaio_uring_shmem_init(bool first_time)
 	/*
 	 * We allocate memory for all PgAioUringContext instances and, if
 	 * supported, the memory required for each of the io_uring instances, in
-	 * one ShmemInitStruct().
+	 * one combined allocation.
+	 *
+	 * pgaio_uring_contexts is already set to the base of the allocation.
 	 */
-	shmem = ShmemInitStruct("AioUringContext", pgaio_uring_shmem_size(), &found);
-	if (found)
-		return;
-
-	pgaio_uring_contexts = (PgAioUringContext *) shmem;
+	shmem = (char *) pgaio_uring_contexts;
 	shmem += pgaio_uring_context_shmem_size();
 
 	/* if supported, handle memory alignment / sizing for io_uring memory */
diff --git a/src/backend/storage/aio/method_worker.c b/src/backend/storage/aio/method_worker.c
index efe38e9f113..82c8b098a9e 100644
--- a/src/backend/storage/aio/method_worker.c
+++ b/src/backend/storage/aio/method_worker.c
@@ -41,6 +41,7 @@
 #include "storage/ipc.h"
 #include "storage/latch.h"
 #include "storage/proc.h"
+#include "storage/shmem.h"
 #include "tcop/tcopprot.h"
 #include "utils/injection_point.h"
 #include "utils/memdebug.h"
@@ -73,16 +74,20 @@ typedef struct PgAioWorkerControl
 } PgAioWorkerControl;
 
 
-static size_t pgaio_worker_shmem_size(void);
-static void pgaio_worker_shmem_init(bool first_time);
+static void pgaio_worker_shmem_request(void *arg);
+static void pgaio_worker_shmem_init(void *arg);
+static void pgaio_worker_shmem_attach(void *arg);
+
+static PgAioWorkerSubmissionQueue *io_worker_submission_queue;
 
 static bool pgaio_worker_needs_synchronous_execution(PgAioHandle *ioh);
 static int	pgaio_worker_submit(uint16 num_staged_ios, PgAioHandle **staged_ios);
 
 
 const IoMethodOps pgaio_worker_ops = {
-	.shmem_size = pgaio_worker_shmem_size,
-	.shmem_init = pgaio_worker_shmem_init,
+	.shmem_callbacks.request_fn = pgaio_worker_shmem_request,
+	.shmem_callbacks.init_fn = pgaio_worker_shmem_init,
+	.shmem_callbacks.attach_fn = pgaio_worker_shmem_attach,
 
 	.needs_synchronous_execution = pgaio_worker_needs_synchronous_execution,
 	.submit = pgaio_worker_submit,
@@ -95,7 +100,6 @@ int			io_workers = 3;
 
 static int	io_worker_queue_size = 64;
 static int	MyIoWorkerId;
-static PgAioWorkerSubmissionQueue *io_worker_submission_queue;
 static PgAioWorkerControl *io_worker_control;
 
 
@@ -116,50 +120,60 @@ pgaio_worker_control_shmem_size(void)
 		sizeof(PgAioWorkerSlot) * MAX_IO_WORKERS;
 }
 
-static size_t
-pgaio_worker_shmem_size(void)
+/*
+ * Set secondary AIO worker pointer from the combined allocation.
+ */
+static void
+pgaio_worker_set_secondary_ptr(void)
 {
-	size_t		sz;
 	int			queue_size;
+	Size		queue_sz = pgaio_worker_queue_shmem_size(&queue_size);
 
-	sz = pgaio_worker_queue_shmem_size(&queue_size);
-	sz = add_size(sz, pgaio_worker_control_shmem_size());
-
-	return sz;
+	io_worker_control = (PgAioWorkerControl *)
+		((char *) io_worker_submission_queue + MAXALIGN(queue_sz));
 }
 
 static void
-pgaio_worker_shmem_init(bool first_time)
+pgaio_worker_shmem_init(void *arg)
 {
-	bool		found;
 	int			queue_size;
 
-	io_worker_submission_queue =
-		ShmemInitStruct("AioWorkerSubmissionQueue",
-						pgaio_worker_queue_shmem_size(&queue_size),
-						&found);
-	if (!found)
-	{
-		io_worker_submission_queue->size = queue_size;
-		io_worker_submission_queue->head = 0;
-		io_worker_submission_queue->tail = 0;
-	}
+	pgaio_worker_queue_shmem_size(&queue_size);
+	io_worker_submission_queue->size = queue_size;
+	io_worker_submission_queue->head = 0;
+	io_worker_submission_queue->tail = 0;
+
+	pgaio_worker_set_secondary_ptr();
 
-	io_worker_control =
-		ShmemInitStruct("AioWorkerControl",
-						pgaio_worker_control_shmem_size(),
-						&found);
-	if (!found)
+	io_worker_control->idle_worker_mask = 0;
+	for (int i = 0; i < MAX_IO_WORKERS; ++i)
 	{
-		io_worker_control->idle_worker_mask = 0;
-		for (int i = 0; i < MAX_IO_WORKERS; ++i)
-		{
-			io_worker_control->workers[i].latch = NULL;
-			io_worker_control->workers[i].in_use = false;
-		}
+		io_worker_control->workers[i].latch = NULL;
+		io_worker_control->workers[i].in_use = false;
 	}
 }
 
+static void
+pgaio_worker_shmem_attach(void *arg)
+{
+	pgaio_worker_set_secondary_ptr();
+}
+
+static void
+pgaio_worker_shmem_request(void *arg)
+{
+	static ShmemStructDesc AioWorkerShmemDesc = {
+		.name = "AioWorkerSubmissionQueue",
+		.ptr = (void **) &io_worker_submission_queue,
+	};
+	int			queue_size;
+
+	AioWorkerShmemDesc.size =
+		MAXALIGN(pgaio_worker_queue_shmem_size(&queue_size)) +
+		pgaio_worker_control_shmem_size();
+	ShmemRequestStruct(&AioWorkerShmemDesc);
+}
+
 static int
 pgaio_worker_choose_idle(void)
 {
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 49a946d3fae..b5f3df68963 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -118,7 +118,6 @@ CalculateShmemSize(void)
 	size = add_size(size, SyncScanShmemSize());
 	size = add_size(size, StatsShmemSize());
 	size = add_size(size, SlotSyncShmemSize());
-	size = add_size(size, AioShmemSize());
 	size = add_size(size, WaitLSNShmemSize());
 	size = add_size(size, LogicalDecodingCtlShmemSize());
 
@@ -302,7 +301,6 @@ CreateOrAttachShmemStructs(void)
 	BTreeShmemInit();
 	SyncScanShmemInit();
 	StatsShmemInit();
-	AioShmemInit();
 	WaitLSNShmemInit();
 	LogicalDecodingCtlShmemInit();
 }
diff --git a/src/include/storage/aio_internal.h b/src/include/storage/aio_internal.h
index 5feea15be9e..9dd8d63b25c 100644
--- a/src/include/storage/aio_internal.h
+++ b/src/include/storage/aio_internal.h
@@ -20,6 +20,8 @@
 #include "port/pg_iovec.h"
 #include "storage/aio.h"
 #include "storage/condition_variable.h"
+#include "storage/ipc.h"
+#include "storage/shmem.h"
 
 
 /*
@@ -267,20 +269,8 @@ typedef struct IoMethodOps
 	 */
 	bool		wait_on_fd_before_close;
 
-
 	/* global initialization */
-
-	/*
-	 * Amount of additional shared memory to reserve for the io_method. Called
-	 * just like a normal ipci.c style *Size() function. Optional.
-	 */
-	size_t		(*shmem_size) (void);
-
-	/*
-	 * Initialize shared memory. First time is true if AIO's shared memory was
-	 * just initialized, false otherwise. Optional.
-	 */
-	void		(*shmem_init) (bool first_time);
+	ShmemCallbacks shmem_callbacks;
 
 	/*
 	 * Per-backend initialization. Optional.
diff --git a/src/include/storage/aio_subsys.h b/src/include/storage/aio_subsys.h
index 276cb3e31c4..dd54869351f 100644
--- a/src/include/storage/aio_subsys.h
+++ b/src/include/storage/aio_subsys.h
@@ -20,12 +20,8 @@
 
 
 /* aio_init.c */
-extern Size AioShmemSize(void);
-extern void AioShmemInit(void);
-
 extern void pgaio_init_backend(void);
 
-
 /* aio.c */
 extern void pgaio_error_cleanup(void);
 extern void AtEOXact_Aio(bool is_commit);
diff --git a/src/include/storage/subsystemlist.h b/src/include/storage/subsystemlist.h
index 63d1d60ae36..e8e06be30c2 100644
--- a/src/include/storage/subsystemlist.h
+++ b/src/include/storage/subsystemlist.h
@@ -48,3 +48,6 @@ PG_SHMEM_SUBSYSTEM(ProcSignalShmemCallbacks)
 PG_SHMEM_SUBSYSTEM(AsyncShmemCallbacks)
 PG_SHMEM_SUBSYSTEM(WaitEventCustomShmemCallbacks)
 PG_SHMEM_SUBSYSTEM(InjectionPointShmemCallbacks)
+
+/* AIO subsystem. This delegates to the method-specific callbacks */
+PG_SHMEM_SUBSYSTEM(AioShmemCallbacks)
-- 
2.47.3