[cpp]
long do_mount(char *dev_name, char *dir_name, char *type_page, unsigned long flags, void *data_page) { struct path path; int retval = 0; int mnt_flags = 0; /* Discard magic */ if ((flags & MS_MGC_MSK) == MS_MGC_VAL) flags &= ~MS_MGC_MSK; /* Basic sanity checks */ if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) return -EINVAL; if (data_page) ((char *)data_page)[PAGE_SIZE - 1] = 0; /* Default to relatime unless overriden */ if (!(flags & MS_NOATIME)) mnt_flags |= MNT_RELATIME; /* Separate the per-mountpoint flags */ if (flags & MS_NOSUID) mnt_flags |= MNT_NOSUID; if (flags & MS_NODEV) mnt_flags |= MNT_NODEV; if (flags & MS_NOEXEC) mnt_flags |= MNT_NOEXEC; if (flags & MS_NOATIME) mnt_flags |= MNT_NOATIME; if (flags & MS_NODIRATIME) mnt_flags |= MNT_NODIRATIME; if (flags & MS_STRICTATIME) mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); if (flags & MS_RDONLY) mnt_flags |= MNT_READONLY; flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | MS_STRICTATIME); /* ... and get the mountpoint */ /*获得安装点path结构*/ retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); if (retval) return retval; retval = security_sb_mount(dev_name, &path, type_page, flags, data_page); if (retval) goto dput_out; if (flags & MS_REMOUNT) /*修改已经存在的文件系统参数,即改变超级块对象s_flags 字段的安装标志*/ retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, data_page); else if (flags & MS_BIND) /*要求在系统目录树的另一个安装点上得文件或目录能够可见*/ retval = do_loopback(&path, dev_name, flags & MS_REC); else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) /*is responsible for handling shared, slave, and unbindable mounts by changing the mount flags or building up the required data structure connections between the vfsmount instances involved.*/ retval = do_change_type(&path, flags); else if (flags & MS_MOVE) /*改变已安装文件的安装点*/ /*used to move a mounted filesystem*/ retval = do_move_mount(&path, dev_name); else /*handles normal mount operations. This is the default situation, so no special flags are required*/ /*当用户要求安装一个特殊文件系统或存放在磁盘分区 中的普通文件系统时，调用*/ retval = do_new_mount(&path, type_page, flags, mnt_flags, dev_name, data_page); dput_out: path_put(&path); return retval; }