From b0facd028859ff463122c53e02584dbf60ba9a50 Mon Sep 17 00:00:00 2001
From: Howard Chu <hyc@openldap.org>
Date: Wed, 15 Apr 2026 15:14:37 +0100
Subject: [PATCH] ITS#10054 lmdb: break up large overflow page writes

We were ignoring MAX_WRITE when a single overflow page was larger.
Now we guarantee that all writes are <= MAX_WRITE (1GB).
---
 libraries/liblmdb/mdb.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 8ea3213773..c785f13042 100644
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -4198,6 +4198,14 @@ retry_write:
 				wres = pwritev(fd, iov, n, wpos);
 #else
 				if (n == 1) {
+					while (wsize > MAX_WRITE) {
+						wsize -= MAX_WRITE;
+						wres = pwrite(fd, iov[0].iov_base, MAX_WRITE, wpos);
+						if (wres != MAX_WRITE)
+							goto bad_write;;
+						wpos += MAX_WRITE;
+						iov[0].iov_base += MAX_WRITE;
+					}
 					wres = pwrite(fd, iov[0].iov_base, wsize, wpos);
 				} else {
 retry_seek:
@@ -4213,6 +4221,7 @@ retry_seek:
 					}
 				}
 #endif
+bad_write:
 				if (wres != wsize) {
 					if (wres < 0) {
 						rc = ErrCode();