cfuselibfuse

How to allow pass kernel options to libfuse?

I have a small utility which uses libfuse3

    struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
    struct fuse_cmdline_opts fuse_cmdline_opts;
    if (fuse_parse_cmdline(&args, &fuse_cmdline_opts) != -1) {
        struct fuse_session *se;
        se = fuse_session_new(&args, &httpfs_oper, sizeof(httpfs_oper), NULL);
        if (se != NULL) {
            if (fuse_set_signal_handlers(se) != -1) {
                fuse_session_mount(se, fuse_cmdline_opts.mountpoint);
                fprintf(stderr, "resource ready\n");
                err = fuse_session_loop_mt(se, NULL);
                fuse_remove_signal_handlers(se);
                fuse_session_unmount(se);
           }
        }
    }

I do not undestand, how I can pass kernel options (like max_reads, max_write) to fuse?

fuse: unknown option(s): `-o max_write=1024'

I expected libfuse will grab options from command line by himself

Solution

  • There is no native way to pass max_write through command line.

    max_write is a member of struct fuse_conn_info. You can set it through the fuse ->init() method. You can implement your own such cmd line arg and later set appropriately, like: conn->max_write = argv_parsed_value.

    See this libfuse example fs doing something similar: https://github.com/libfuse/libfuse/blob/a466241b45d1dd0bf685513bdeefd6448b63beb6/example/passthrough_ll.c#L168

    Please notice your code tries to parse cmd line args into struct fuse_cmdline_opts. max_write is not included there: https://github.com/libfuse/libfuse/blob/a466241b45d1dd0bf685513bdeefd6448b63beb6/include/fuse_lowlevel.h#L1941