​fixed storoge.reserve检测磁盘预留空闲时间间隔问题

//这里的{username}是你从glusterfs社区fork过来的你自己的分支，比如我自己的perrynzhou,这里的username就是perrynzhou
git clone git@github.com:${username}/glusterfs.git
cd glusterfs/
git remote add upstream git@github.com:gluster/glusterfs.git
git fetch upstream
git rebase upstream/devel
git checkout -b perryn/dev
//进行修改，修改完毕后执行
git commit -m 'xxx'
//修改提交信息，Change-Id可以从git log查看commit id，设置Change-Id 为commit id
git commit --amend
/---------------修改git message----------------/
change to an option for time checking storage.reserve
storage/posix: change to an option for time checking storage.reserve (#2120)


Change-Id: 66e34de17b1e6e308a5b648fc2232f543047b40d
Fixed: #2120
Signed-off-by: perrynzhou <perrynzhou@gmail.com>
/---------------修改git message----------------/    
./rfc.sh
git push origin perryn/dev
//通过社区的code view如果没有问题可以把perryn/dev分支代码merge到glusterfs社区分支，需要提一个PR
//基于自己的分支来提一个PR，让社区的小伙伴进行code review

// 添加gluster cli支持的参数
//glusterfs-8.3/xlators/mgmt/glusterd/src/glusterd-volume-set.c:2410
struct volopt_map_entry glusterd_volopt_map[] = {
{
      .key = "storage.reserve",
      .voltype = "storage/posix",
      .op_version = GD_OP_VERSION_3_13_0,
  },
  {
      .key = "storage.reserve-check-interval",
      .voltype = "storage/posix",
      .op_version = GD_OP_VERSION_4_0_0,
  }
}

// 在storage/posix xlator中的posix_private添加一个字段，用户存储来自客户端的传进来的storage.reserve-check-interval值
//glusterfs-8.3/xlators/storage/posix/src/posix.h
struct posix_private {
	    double disk_reserve;
    /* seconds for check disk reversion  */
    uint32_t disk_reserve_check_interval;
}

// 需要在posix_init中初始化reserve-check-interval的值
//glusterfs-8.3/xlator/storage/posix/src/posix-common.c
int posix_init(xlator_t *this)
{

    GF_OPTION_INIT("reserve", _private->disk_reserve, percent_or_size, out);
    //在这里添加在storage/posix xlator中的初始化值，这个值依赖于posix_options配置的默认值
    // add disk reserve internal seconds for reserve check
    GF_OPTION_INIT("reserve-check-interval", _private->disk_reserve_check_interval, uint32, out);
}
struct volume_options posix_options[] = {
     {.key = {"reserve-check-interval"},
     .type = GF_OPTION_TYPE_INT,
     .min = 1,
     .default_value = "5",
     .validate = GF_OPT_VALIDATE_MIN,
     .description =  "Interval in second to check disk reserve",
     .op_version = {GD_OP_VERSION_4_0_0},
     .flags = OPT_FLAG_SETTABLE | OPT_FLAG_DOC},
   }

// glusterfs-8.3/xlator/storage/posix/src/posix-common.c
int posix_reconfigure(xlator_t *this, dict_t *options)
{
    GF_OPTION_RECONF("reserve", priv->disk_reserve, options, percent_or_size,
                     out);
    // add config reconfig
    GF_OPTION_RECONF("reserve-check-interval", priv->disk_reserve_check_interval, options, uint32,
                     out);
}

  /********glusterfs 8.x版本修改方式********/

//glusterfs-8.3/xlator/storage/posix/src/posix-helpers.c
static void *posix_disk_space_check_thread_proc(void *data)
{
  xlator_t *this = NULL;
  struct posix_private *priv = NULL;
  int ret = -1;

  this = data;
  priv = this->private;

  gf_msg_debug(this->name, 0,
               "disk-space thread started, "
               "interval = %d seconds",
               interval);
  while (1) {
      ret = sleep(priv->reserve-check-interval);
      if (ret > 0)
          break;
      pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
      // 磁盘检查函数
      posix_disk_space_check(this);
      if (!priv->disk_space_check_active)
          goto out;
      pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
  }

  return NULL;
}


/********glusterfs 9.x版本以及以上版本********/
int posix_spawn_disk_space_check_thread(xlator_t *this)
{
    //修改gf_thread_create函数由原来传递的glusterfs_ctx_t修改为xlator,每次storage.reserve重新开启都会在Debug日志中打印reserve-check-interval时间
    ret = gf_thread_create(&ctx->disk_space_check, NULL,posix_ctx_disk_thread_proc, this,"posixctxres");
}

// 实际做磁盘检查的线程工作，posix_ctx_disk_thread_proc原来传递的是glusterfs_ctx_t指针修改为xlator指针，在函数内部从xlator指针获取glusterfs_ctx_t指针
static void *posix_ctx_disk_thread_proc(void *data)
{
  struct posix_private *priv = NULL;
  glusterfs_ctx_t *ctx = NULL;
  priv = this->private;
  ctx = this->ctx;
  pthread_mutex_lock(&ctx->xl_lock);
  {
    while (ctx->diskxl_count > 0) {
        list_for_each_entry(pthis, &ctx->diskth_xl, list)
        {
            timespec_now_realtime(&sleep_till);
            // 每次累计priv->disk_reserve_check_interval;直到超时priv->disk_reserve_check_interval
            sleep_till.tv_sec += priv->disk_reserve_check_interval;
            (void)pthread_cond_timedwait(&ctx->xl_cond, &ctx->xl_lock,
                                     &sleep_till);
        }
    }
    pthread_mutex_unlock(&ctx->xl_lock);

    return NULL;
}

[root@CentOS glusterfs]# git status
# On branch perryn/storage-reserve-option-dev
# Changes not staged for commit:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#       modified:   xlators/mgmt/glusterd/src/glusterd-volume-set.c
#       modified:   xlators/storage/posix/src/posix-common.c
#       modified:   xlators/storage/posix/src/posix-helpers.c
#       modified:   xlators/storage/posix/src/posix.h