1 files changed, 184 insertions, 0 deletions
diff --git a/src/backend/storage/aio/aio_io.c b/src/backend/storage/aio/aio_io.c
new file mode 100644
index 00000000000..36d2c1f492d
--- /dev/null
+++ b/src/backend/storage/aio/aio_io.c
@@ -0,0 +1,184 @@
+/*-------------------------------------------------------------------------
+ *
+ * aio_io.c
+ *    AIO - Low Level IO Handling
+ *
+ * Functions related to associating IO operations to IO Handles and IO-method
+ * independent support functions for actually performing IO.
+ *
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *    src/backend/storage/aio/aio_io.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "miscadmin.h"
+#include "storage/aio.h"
+#include "storage/aio_internal.h"
+#include "storage/fd.h"
+#include "utils/wait_event.h"
+
+
+static void pgaio_io_before_prep(PgAioHandle *ioh);
+
+
+
+/* --------------------------------------------------------------------------------
+ * Public IO related functions operating on IO Handles
+ * --------------------------------------------------------------------------------
+ */
+
+/*
+ * Scatter/gather IO needs to associate an iovec with the Handle. To support
+ * worker mode this data needs to be in shared memory.
+ */
+int
+pgaio_io_get_iovec(PgAioHandle *ioh, struct iovec **iov)
+{
+	Assert(ioh->state == PGAIO_HS_HANDED_OUT);
+
+	*iov = &pgaio_ctl->iovecs[ioh->iovec_off];
+
+	return PG_IOV_MAX;
+}
+
+PgAioOp
+pgaio_io_get_op(PgAioHandle *ioh)
+{
+	return ioh->op;
+}
+
+PgAioOpData *
+pgaio_io_get_op_data(PgAioHandle *ioh)
+{
+	return &ioh->op_data;
+}
+
+
+
+/* --------------------------------------------------------------------------------
+ * "Preparation" routines for individual IO operations
+ *
+ * These are called by the code actually initiating an IO, to associate the IO
+ * specific data with an AIO handle.
+ *
+ * Each of the preparation routines first needs to call
+ * pgaio_io_before_prep(), then fill IO specific fields in the handle and then
+ * finally call pgaio_io_stage().
+ * --------------------------------------------------------------------------------
+ */
+
+void
+pgaio_io_prep_readv(PgAioHandle *ioh,
+					int fd, int iovcnt, uint64 offset)
+{
+	pgaio_io_before_prep(ioh);
+
+	ioh->op_data.read.fd = fd;
+	ioh->op_data.read.offset = offset;
+	ioh->op_data.read.iov_length = iovcnt;
+
+	pgaio_io_stage(ioh, PGAIO_OP_READV);
+}
+
+void
+pgaio_io_prep_writev(PgAioHandle *ioh,
+					 int fd, int iovcnt, uint64 offset)
+{
+	pgaio_io_before_prep(ioh);
+
+	ioh->op_data.write.fd = fd;
+	ioh->op_data.write.offset = offset;
+	ioh->op_data.write.iov_length = iovcnt;
+
+	pgaio_io_stage(ioh, PGAIO_OP_WRITEV);
+}
+
+
+
+/* --------------------------------------------------------------------------------
+ * Internal IO related functions operating on IO Handles
+ * --------------------------------------------------------------------------------
+ */
+
+/*
+ * Execute IO operation synchronously. This is implemented here, not in
+ * method_sync.c, because other IO methods also might use it / fall back to
+ * it.
+ */
+void
+pgaio_io_perform_synchronously(PgAioHandle *ioh)
+{
+	ssize_t		result = 0;
+	struct iovec *iov = &pgaio_ctl->iovecs[ioh->iovec_off];
+
+	START_CRIT_SECTION();
+
+	/* Perform IO. */
+	switch (ioh->op)
+	{
+		case PGAIO_OP_READV:
+			pgstat_report_wait_start(WAIT_EVENT_DATA_FILE_READ);
+			result = pg_preadv(ioh->op_data.read.fd, iov,
+							   ioh->op_data.read.iov_length,
+							   ioh->op_data.read.offset);
+			pgstat_report_wait_end();
+			break;
+		case PGAIO_OP_WRITEV:
+			pgstat_report_wait_start(WAIT_EVENT_DATA_FILE_WRITE);
+			result = pg_pwritev(ioh->op_data.write.fd, iov,
+								ioh->op_data.write.iov_length,
+								ioh->op_data.write.offset);
+			pgstat_report_wait_end();
+			break;
+		case PGAIO_OP_INVALID:
+			elog(ERROR, "trying to execute invalid IO operation");
+	}
+
+	ioh->result = result < 0 ? -errno : result;
+
+	pgaio_io_process_completion(ioh, ioh->result);
+
+	END_CRIT_SECTION();
+}
+
+/*
+ * Helper function to be called by IO operation preparation functions, before
+ * any data in the handle is set.  Mostly to centralize assertions.
+ */
+static void
+pgaio_io_before_prep(PgAioHandle *ioh)
+{
+	Assert(ioh->state == PGAIO_HS_HANDED_OUT);
+	Assert(pgaio_my_backend->handed_out_io == ioh);
+	Assert(pgaio_io_has_target(ioh));
+	Assert(ioh->op == PGAIO_OP_INVALID);
+}
+
+/*
+ * Could be made part of the public interface, but it's not clear there's
+ * really a use case for that.
+ */
+const char *
+pgaio_io_get_op_name(PgAioHandle *ioh)
+{
+	Assert(ioh->op >= 0 && ioh->op < PGAIO_OP_COUNT);
+
+	switch (ioh->op)
+	{
+		case PGAIO_OP_INVALID:
+			return "invalid";
+		case PGAIO_OP_READV:
+			return "read";
+		case PGAIO_OP_WRITEV:
+			return "write";
+	}
+
+	return NULL;				/* silence compiler */
+}