readdir在安装的CIF目录上花费很长时间

Question

I'm running the following code:

void EnumerateFolder(std::string folder)
{ 
    DIR* directory;
    struct dirent* entry;

    directory = opendir(folder.c_str());
    if(directory != NULL)
    {
        while((entry = readdir(directory)) != NULL)
        {
            std::cout << entry->d_name;
        }
    }
}

When it gets to a mounted CIFS folder that I have readdir() sometimes takes 15 minutes to return. Anyone care to enlighten me as to what is happenening and how I can achieve a friendlier experience? This happens every time I run the code and the computer with the shared folder is offline. It also happens arbitrarily(as far as I can tell), perhaps when the computer with the shared folders harddrive is "idle".

How is the folder mounted you say?

cat /etc/fstab
//192.168.0.6/MyShare /home/MyUser/MountedShare cifs guest 0 0

192.168.0.6 is running Windows 8, if that matters. Thanks!

Answer 1

15 seconds is the standard CIFS Send2 timeout . If you want it to fail faster, you can put a timeo option on the mount options. Specify the timeout in tenths of a second.

The filesystem doesn't really know why the application wants to read the file. Fast timeouts could break long-running processes if they were, for example, faulting in pages of executable code. So generally speaking, network filesystems try to mimic the semantics of local filesystems which is to wait for as long as needed for the underlying storage to respond.