Make sure packedgitwindowsize is multiple of (pagesize * 2)

The next patch depends on this.

Signed-off-by: Junio C Hamano <junkio@cox.net>

config.c

@@ -310,12 +310,14 @@ int git_default_config(const char *var, const char *value)
 	}
 
 	if (!strcmp(var, "core.packedgitwindowsize")) {
-		int pgsz = getpagesize();
+		int pgsz_x2 = getpagesize() * 2;
 		packed_git_window_size = git_config_int(var, value);
-		packed_git_window_size /= pgsz;
-		if (packed_git_window_size < 2)
-			packed_git_window_size = 2;
-		packed_git_window_size *= pgsz;
+
+		/* This value must be multiple of (pagesize * 2) */
+		packed_git_window_size /= pgsz_x2;
+		if (packed_git_window_size < 1)
+			packed_git_window_size = 1;
+		packed_git_window_size *= pgsz_x2;
 		return 0;
 	}
 

git-compat-util.h

@@ -96,11 +96,14 @@ extern void set_warn_routine(void (*routine)(const char *warn, va_list params));
 extern void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);
 extern int git_munmap(void *start, size_t length);
 
+/* This value must be multiple of (pagesize * 2) */
 #define DEFAULT_PACKED_GIT_WINDOW_SIZE (1 * 1024 * 1024)
 
 #else /* NO_MMAP */
 
 #include <sys/mman.h>
+
+/* This value must be multiple of (pagesize * 2) */
 #define DEFAULT_PACKED_GIT_WINDOW_SIZE \
 	(sizeof(void*) >= 8 \
 		?  1 * 1024 * 1024 * 1024 \