mount 中的文件系统类型

adfs, affs, autofs, cifs, coda, coherent, cramfs,
debugfs, devpts, efs, ext, ext2, ext3, hfs, hfsplus, hpfs,
iso9660, jfs, minix, msdos, ncpfs, nfs, nfs4, ntfs, proc, qnx4,
ramfs, reiserfs, romfs, smbfs, sysv, tmpfs, udf, ufs, umsdos,
usbfs, vfat, xenix, xfs, xiafs.