embedded-linux – 在Linux中使用NFS挂载系统调用

mount -t nfs -o nolock 10.126.62.45:/vol/home/avinoba/Sky /mnt

if(mount("10.126.62.45:/vol/home/avinoba/Sky","/mnt","nfs",MS_MGC_VAL,"nolock") == -1)
{
     printf("ERROR: mount failed: %s n",strerror(errno));
}

我很惊讶这里有关于NFS挂载的任何手册页都没有涵盖这一点.潜入内核代码,在函数nfs_validate_text_mount_data中,函数nfs_parse_mount_options负责解析作为mount系统调用中第五个参数传递的多个逗号分隔选项.

struct sockaddr *sap = (struct sockaddr *)&args->nfs_server.address;

if (nfs_parse_mount_options((char *)options,args) == 0)
    return -EINVAL;

if (!nfs_verify_server_address(sap))
    goto out_no_address;

在上面的代码块中,最后一个if语句检查nfs服务器地址和套接字系列是否定义为有效值.如果它们未在nfs_parse_mount_options中更新,则mount将最终返回无效参数.

如果遍历nfs_parse_mount_options的实现,则可以看出,仅对于Opt_addr的情况,通过解析options参数来更新nfs服务器地址和套接字系列.

case Opt_addr:
    string = match_strdup(args);
    if (string == NULL)
        goto out_nomem;
    mnt->nfs_server.addrlen =
        rpc_pton(mnt->net,string,strlen(string),(struct sockaddr *)
            &mnt->nfs_server.address,sizeof(mnt->nfs_server.address));
    kfree(string);
    if (mnt->nfs_server.addrlen == 0)
        goto out_invalid_address;
    break;

Opt_addr的情况对应于“addr = nfs server ip”选项.因此,要使系统调用工作,必须定义此选项.据我所知,所有描述nfs挂载的手册页都完全没有.

所以现在考虑问题陈述,请尝试更改为以下代码

if(mount(":/vol/home/avinoba/Sky","nolock,addr=10.126.62.45") == -1)
{
     printf("ERROR: mount failed: %s n",strerror(errno));
}

Also note that when the addr option is put in the argument,the ip address in front of the nfs server path becomes optional. However the ‘:’ is must,as this acts as the delimiter to parse the nfs server path.