bindfs - Mount a directory elsewhere with changed permissions.

今天阅读fanstore论文时，发现其使用bindfs做了实验；我个人对filesystem比较感兴趣，进行初步使用一下并进行记录；

项目地址：https://github.com/mpartel/bindfs

项目网站：https://bindfs.org/

项目功能：使用不同的权限，重新在本机挂载一个文件系统；

原理：使用libfuse实现的stackfs; 其中做了属性的控制；

bindfs is a FUSE filesystem for mirroring a directory to another directory, similarly to mount --bind. 
The permissions of the mirrored directory can be altered in various ways.

Some things bindfs can be used for:

　　1. Making a directory read-only.
　　2. Making all executables non-executable.
　　3. Sharing a directory with a list of users (or groups).
　　4. Modifying permission bits using rules with chmod-like syntax.
　　5. Changing the permissions with which files are created.
　　6. Non-root users can use almost all features, but most interesting use-cases need user_allow_other to be defined in /etc/fuse.conf.

如果允许非root用户使用，需要设置：

Non-root users can use almost all features, but most interesting use-cases need user_allow_other to be defined in /etc/fuse.conf.

测试结果：

使用 bindfs 可以达到和 mount --bind 同样的效果，并且多了权限控制的功能；但是从性能上来说，因为bindfs为用户态文件系统，所以bindfs的性能会低于mount --bind的方式。

具体性能对比测试，我这里没有进行，你可以简单使用工具进行对比；

常用命令：

Make a directory read-only for non-root users.
bindfs --perms=a-w somedir somedir

Share a directory with some other users without modifying /etc/group.
bindfs --mirror-only=joe,bob,@wheel ~/some/dir shared

Make all new files uploaded to an FTP share owned by you and seen by everyone.
bindfs --create-for-user=me --create-with-perms=u+rw,a+rD /var/ftp/uploads /var/ftp/uploads

Make your website available to the webserver process read-only.
bindfs --force-user=www --perms=0000:u=rD ~/stuff/website ~/public_html

The corresponding /etc/fstab entry.
/home/bob/stuff/website /home/bob/public_html fuse.bindfs force-user=www,perms=0000:u+rD 0 0

保持更新；cnblogs.com/xuyaowen;