From 0b07749fbac8b933f8ea7b25a34b350b8ac47ba1 Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Wed, 26 Jul 2017 11:34:07 +0300
Subject: [PATCH] mdbx: major fix - madvise(MADV_REMOVE) only for exclusive
 mode.

Change-Id: I6799df7b85eaf32a1c46f251ca64a4df4ff092b2
---
 src/mdbx.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/mdbx.c b/src/mdbx.c
index dde2f598..7668e608 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -4205,9 +4205,10 @@ static int __cold mdbx_env_map(MDBX_env *env, size_t usedsize) {
 #endif
 
 #ifdef MADV_REMOVE
-  if (env->me_flags & MDBX_WRITEMAP)
+  if (usedsize && (env->me_flags & MDBX_WRITEMAP)) {
     (void)madvise(env->me_map + usedsize, env->me_mapsize - usedsize,
                   MADV_REMOVE);
+  }
 #else
   (void)usedsize;
 #endif
@@ -4619,8 +4620,10 @@ static int __cold mdbx_setup_dxb(MDBX_env *env, int lck_rc) {
     }
   }
 
-  err = mdbx_env_map(env, expected_bytes);
-  if (err)
+  err = mdbx_env_map(env, (lck_rc != /* lck exclusive */ MDBX_RESULT_TRUE)
+                              ? 0
+                              : expected_bytes);
+  if (err != MDBX_SUCCESS)
     return err;
 
   const unsigned meta_clash_mask = mdbx_meta_eq_mask(env);