2 * memfd test file-system
3 * This file uses FUSE to create a dummy file-system with only one file /memfd.
4 * This file is read-only and takes 1s per read.
6 * This file-system is used by the memfd test-cases to force the kernel to pin
7 * pages during reads(). Due to the 1s delay of this file-system, this is a
8 * nice way to test race-conditions against get_user_pages() in the kernel.
10 * We use direct_io==1 to force the kernel to use direct-IO for this
14 #define FUSE_USE_VERSION 26
23 static const char memfd_content[] = "memfd-example-content";
24 static const char memfd_path[] = "/memfd";
26 static int memfd_getattr(const char *path, struct stat *st)
28 memset(st, 0, sizeof(*st));
30 if (!strcmp(path, "/")) {
31 st->st_mode = S_IFDIR | 0755;
33 } else if (!strcmp(path, memfd_path)) {
34 st->st_mode = S_IFREG | 0444;
36 st->st_size = strlen(memfd_content);
44 static int memfd_readdir(const char *path,
46 fuse_fill_dir_t filler,
48 struct fuse_file_info *fi)
50 if (strcmp(path, "/"))
53 filler(buf, ".", NULL, 0);
54 filler(buf, "..", NULL, 0);
55 filler(buf, memfd_path + 1, NULL, 0);
60 static int memfd_open(const char *path, struct fuse_file_info *fi)
62 if (strcmp(path, memfd_path))
65 if ((fi->flags & 3) != O_RDONLY)
74 static int memfd_read(const char *path,
78 struct fuse_file_info *fi)
82 if (strcmp(path, memfd_path) != 0)
87 len = strlen(memfd_content);
89 if (offset + size > len)
92 memcpy(buf, memfd_content + offset, size);
100 static struct fuse_operations memfd_ops = {
101 .getattr = memfd_getattr,
102 .readdir = memfd_readdir,
107 int main(int argc, char *argv[])
109 return fuse_main(argc, argv, &memfd_ops, NULL);