From 5e58a2a65f0780dd7df04db1569cc5fcb63089b7 Mon Sep 17 00:00:00 2001
From: Sohei Koyama <skoyama@hpcs.cs.tsukuba.ac.jp>
Date: Tue, 8 Oct 2024 18:36:17 +0900
Subject: [PATCH] mmap support

---
 .github/workflows/ci.yaml |  2 +-
 configure.ac              |  7 +++++++
 lib/finchfs.c             | 18 +++++++++++++++---
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 7bf02d4..61cde1d 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -28,7 +28,7 @@ jobs:
       run: autoreconf -i
 
     - name: Configure the project
-      run: ./configure
+      run: ./configure --enable-mmap
 
     - name: Build the project
       run: make
diff --git a/configure.ac b/configure.ac
index d0cbeaf..ac3f900 100644
--- a/configure.ac
+++ b/configure.ac
@@ -30,6 +30,13 @@ if test x$with_pmemkv != xno; then
   PKG_CHECK_MODULES([LIBPMEMKV], [libpmemkv])
 fi
 
+AC_ARG_ENABLE([mmap],
+  [AS_HELP_STRING([--enable-mmap], [Enable mmap support])],
+  [if test "x$enable_mmap" = "xyes"; then
+     AC_DEFINE([FINCH_MMAP_SUPPORT], 1, [Enable mmap support])
+  fi],
+  [enable_mmap=no])
+
 # Checks for header files.
 AC_CHECK_HEADERS([stdlib.h string.h unistd.h stdint.h])
 
diff --git a/lib/finchfs.c b/lib/finchfs.c
index ecf7405..3d425a4 100644
--- a/lib/finchfs.c
+++ b/lib/finchfs.c
@@ -43,7 +43,9 @@ static struct fd_table {
 		uint64_t pos;
 	} getdents_state;
 } *fd_table;
+#define IS_NULL_STRING(str) (str == NULL || str[0] == '\0')
 
+#ifdef FINCH_MMAP_SUPPORT
 struct mmap_item;
 
 typedef struct mmap_item {
@@ -113,8 +115,6 @@ query_mmap(uint64_t fault_addr)
 	return (NULL);
 }
 
-#define IS_NULL_STRING(str) (str == NULL || str[0] == '\0')
-
 static void *
 fault_handler_thread(void *arg)
 {
@@ -208,6 +208,7 @@ fault_handler_thread(void *arg)
 		}
 	}
 }
+#endif
 
 int
 finchfs_init(const char *addrfile)
@@ -232,8 +233,10 @@ finchfs_init(const char *addrfile)
 		fd_table[i].path = NULL;
 		fd_table[i].eid = malloc(sizeof(uint64_t) * nvprocs);
 	}
+#ifdef FINCH_MMAP_SUPPORT
 	if ((uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK)) < 0) {
-		log_error("syscall(__NR_userfaultfd) failed errno=%d", errno);
+		log_error("NOTE: /proc/sys/vm/unprivileged_userfaultfd should "
+			  "be set 1");
 		goto init_err;
 	}
 	uffdio_api.api = UFFD_API;
@@ -246,6 +249,7 @@ finchfs_init(const char *addrfile)
 		log_error("pthread_create failed");
 		goto init_err;
 	}
+#endif
 	return (0);
 init_err:
 	finchfs_term();
@@ -1068,6 +1072,7 @@ void *
 finchfs_mmap(void *addr, size_t length, int prot, int flags, int fd,
 	     off_t offset)
 {
+#ifdef FINCH_MMAP_SUPPORT
 	struct uffdio_register uffdio_register;
 	if (fd < 0 || fd >= fd_table_size || fd_table[fd].path == NULL) {
 		errno = EBADF;
@@ -1105,11 +1110,15 @@ finchfs_mmap(void *addr, size_t length, int prot, int flags, int fd,
 	item->offset = offset;
 	add_mmap_item(item);
 	return (addr);
+#endif
+	errno = ENOTSUP;
+	return (MAP_FAILED);
 }
 
 int
 finchfs_munmap(void *addr, size_t length)
 {
+#ifdef FINCH_MMAP_SUPPORT
 	struct uffdio_range uffdio_range;
 	uffdio_range.start = (uint64_t)addr;
 	uffdio_range.len = length;
@@ -1124,4 +1133,7 @@ finchfs_munmap(void *addr, size_t length)
 		return (-1);
 	}
 	return (0);
+#endif
+	errno = ENOTSUP;
+	return (-1);
 }