从函数 nfs4_process_layout_stateid（）看state数据结构

最新推荐文章于 2023-11-24 15:11:51 发布

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最新推荐文章于 2023-11-24 15:11:51 发布

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文章标签： layout 数据结构 generation struct fp parallel

本文链接：https://blog.youkuaiyun.com/zhang_shuai_2011/article/details/7229656

本文探讨了NFS4协议中state和delegation的概念，通过分析函数nfs4_process_layout_stateid的执行流程，揭示了stateid在服务器端如何与nfs4_file结构、全局哈希表及delegation链表交互。在open和lock操作中，stateid被分别存入不同的数据结构，用于验证和管理客户端的状态。

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对state 和 delegation一直没有准确的认识，通过下面这个函数可以大概有个了解。

服务器端，nfs4_file结构中有链表layout_state,

当客户端打开某个文件第一次获取get_layout 时候，ls = find_get_layout_state(clp, fp);是找不到对应的ls的

然后会调用verify_stateid（）函数，到lockstateid_hashtbl[hashval]和stateid_hashtbl[hashval]这两个全局变量，以及nfs4_file结构中的delegation链表中查找，看是否有相等的stateid，若有，则调用ls = alloc_init_layout_state(clp, fp, stateid);创建一个layout_stateid。

lock_stateid[]这个全局变量，会在nfsd4_lock（）这个接口中，添加进去一个nfs4_stateid，

stateid_hashtbl[]这个全局变量是在open的时候添加进去的。

static int
verify_stateid(struct nfs4_file *fp, stateid_t *stateid)
{
   struct nfs4_stateid *local = NULL;
   struct nfs4_delegation *temp = NULL;

   /* check if open or lock stateid */
   local = find_stateid(stateid, RD_STATE);
   if (local)
       return 0;
   temp = find_delegation_stateid(fp->fi_inode, stateid);
   if (temp)
       return 0;
   return nfserr_bad_stateid;
}

nfs4_process_layout_stateid(struct nfs4_client *clp, struct nfs4_file *fp,

                stateid_t *stateid, struct nfs4_layout_state **lsp)
{
   struct nfs4_layout_state *ls = NULL;
   __be32 status = 0;

   dprintk("--> %s clp %p fp %p \n", __func__, clp, fp);

   dprintk("%s: operation stateid=" STATEID_FMT "\n", __func__,
       STATEID_VAL(stateid));

   status = nfs4_check_stateid(stateid);
   if (status)
       goto out;

   /* Is this the first use of this layout ? */
   spin_lock(&layout_lock);
   ls = find_get_layout_state(clp, fp);
   spin_unlock(&layout_lock);
   if (!ls) {
       /* Only alloc layout state on layoutget (which sets lsp). */
       if (!lsp) {
           dprintk("%s ERROR: Not layoutget & no layout stateid\n",
               __func__);
           status = nfserr_bad_stateid;
           goto out;
       }
       dprintk("%s Initial stateid for layout: file %p client %p\n",
           __func__, fp, clp);

       /* verify input stateid */
       status = verify_stateid(fp, stateid);
       if (status < 0) {
           dprintk("%s ERROR: invalid open/deleg/lock stateid\n",
               __func__);
           goto out;
       }
       ls = alloc_init_layout_state(clp, fp, stateid);
       if (!ls) {
           dprintk("%s pNFS ERROR: no memory for layout state\n",
               __func__);
           status = nfserr_resource;
           goto out;
       }
   } else {
       dprintk("%s Not initial stateid. Layout state %p file %p\n",
           __func__, ls, fp);

       /* BAD STATEID */
       status = nfserr_bad_stateid;
       if (memcmp(&ls->ls_stateid.si_opaque, &stateid->si_opaque,
           sizeof(stateid_opaque_t)) != 0) {

           /* if a LAYOUTGET operation and stateid is a valid
           * open/deleg/lock stateid, accept it as a parallel
           * initial layout stateid
           */
           if (lsp && ((verify_stateid(fp, stateid)) == 0)) {
               dprintk("%s parallel initial layout state\n",
                   __func__);
               goto update;
           }

           dprintk("%s ERROR bad opaque in stateid 1\n", __func__);
           goto out_put;
       }

       /* stateid is a valid layout stateid for this file. */
       if (stateid->si_generation > ls->ls_stateid.si_generation) {
           dprintk("%s bad stateid 1\n", __func__);
           goto out_put;
       }
update:
       update_stateid(&ls->ls_stateid);
       dprintk("%s Updated ls_stateid to %d on layoutstate %p\n",
           __func__, ls->ls_stateid.si_generation, ls);
   }
   status = 0;
   /* Set the stateid to be encoded */
   memcpy(stateid, &ls->ls_stateid, sizeof(stateid_t));

   /* Return the layout state if requested */
   if (lsp) {
       get_layout_state(ls);
       *lsp = ls;
   }
   dprintk("%s: layout stateid=" STATEID_FMT "\n", __func__,
       STATEID_VAL(&ls->ls_stateid));
out_put:
   dprintk("%s PUT LO STATE:\n", __func__);
   put_layout_state(ls);
out:
   dprintk("<-- %s status %d\n", __func__, htonl(status));

   return status;