前面可以看出，处理控制中心还是iscsid守护进程，其他进程都是向它发出服务请求，然后它做出响应，而它完成一些操作又是向底层驱动发出指令。在前面的源码中可以发现，重要是一个mgmt_ipc_functions的函数指针数组是一个操作函数集合，其中的函数分别处理不同的服务，服务id就是它在函数指针数组中的索引。
/*不同任务id对应的处理函数地址*/
static mgmt_ipc_fn_t * mgmt_ipc_functions[__MGMT_IPC_MAX_COMMAND] = {
[MGMT_IPC_SESSION_LOGIN] = mgmt_ipc_session_login, /*和iscsi target建立连接*/
[MGMT_IPC_SESSION_LOGOUT] = mgmt_ipc_session_logout, /*与target断开会话*/
[MGMT_IPC_SESSION_SYNC] = mgmt_ipc_session_sync, /*同步会话*/
[MGMT_IPC_SESSION_STATS] = mgmt_ipc_session_getstats, /*查询会话状态*/
[MGMT_IPC_SEND_TARGETS] = mgmt_ipc_send_targets, /*发送targets*/
[MGMT_IPC_SESSION_INFO] = mgmt_ipc_session_info, /*查询会话信息*/
[MGMT_IPC_CONN_ADD] = mgmt_ipc_conn_add, /*增加连接*/
[MGMT_IPC_CONN_REMOVE] = mgmt_ipc_conn_remove, /*删除连接*/
[MGMT_IPC_CONFIG_INAME] = mgmt_ipc_cfg_initiatorname, /*iscsi 配置，获取initiatorname*/
[MGMT_IPC_CONFIG_IALIAS] = mgmt_ipc_cfg_initiatoralias, /*获取initiator 别名*/
[MGMT_IPC_CONFIG_FILE] = mgmt_ipc_cfg_filename, /*获取配置文件路径*/
[MGMT_IPC_IMMEDIATE_STOP] = mgmt_ipc_immediate_stop,/*停止*/
[MGMT_IPC_NOTIFY_ADD_NODE] = mgmt_ipc_notify_add_node, /*增加一个node*/
[MGMT_IPC_NOTIFY_DEL_NODE] = mgmt_ipc_notify_del_node, /*删除一个node*/
[MGMT_IPC_NOTIFY_ADD_PORTAL] = mgmt_ipc_notify_add_portal, /*增加端口*/
[MGMT_IPC_NOTIFY_DEL_PORTAL] = mgmt_ipc_notify_del_portal, /*删除端口*/
};
现在分析第一个操作函数mgmt_ipc_session_login。
/*建立会话*/
static int
mgmt_ipc_session_login(queue_task_t *qtask)
{
/*专门传入task结构中会话请求的数据结构*/
return session_login_task(&qtask->req.u.session.rec, qtask);
}
/*login建立initiator和target的会话*/
int
session_login_task(node_rec_t *rec, queue_task_t *qtask)
{
iscsi_session_t *session;
iscsi_conn_t *conn;
struct iscsi_transport *t;
int rc;
/*判断这个连接是否已经存在*/
if (session_is_running(rec)) {
if (rec->session.multiple)
log_debug(2, "Adding a copy of an existing session");
else
return ISCSI_ERR_SESS_EXISTS;
}
先贴出这些，接着进入session_is_running函数进行分析：
/*
* a session could be running in the kernel but not in iscsid
* due to a resync or becuase some other app started the session
*/
/*判断是否已经存在这个会话连接*/
static int session_is_running(node_rec_t *rec)
{
int nr_found = 0;
/*通过会话请求结构在系统中查找*/
if (session_find_by_rec(rec))
return 1;
/*在sys目录下查找*/
if (iscsi_sysfs_for_each_session(rec, &nr_found, iscsi_match_session))
return 1;
return 0;
}
/*根据会话请求结构返回系统中已存在的会话结构*/
static iscsi_session_t* session_find_by_rec(node_rec_t *rec)
{
struct iscsi_transport *t;
iscsi_session_t *session;
/*遍历系统中的每个transport结构*/
list_for_each_entry(t, &transports, list) {
list_for_each_entry(session, &t->sessions, list) { /*transport链中的每个是session链的头结点，还要遍历*/
if (__iscsi_match_session(rec, session->nrec.name, //targetname
session->nrec.conn[0].address, //target ip
session->nrec.conn[0].port, //target port
&session->nrec.iface, //网络接口
MATCH_ANY_SID))
return session;
}
}
return NULL;
}
//对会话结构进行比较匹配
int __iscsi_match_session(node_rec_t *rec, char *targetname,
char *address, int port, struct iface_rec *iface,
unsigned sid)
{
if (!rec) {
log_debug(6, "no rec info to match\n");
return 1;
}
log_debug(6, "match session [%s,%s,%d][%s %s,%s,%s]:%u",
rec->name, rec->conn[0].address, rec->conn[0].port,
rec->iface.name, rec->iface.transport_name,
rec->iface.hwaddress, rec->iface.ipaddress,
rec->session.sid);
if (iface)
log_debug(6, "to [%s,%s,%d][%s %s,%s,%s]:%u",
targetname, address, port, iface->name,
iface->transport_name, iface->hwaddress,
iface->ipaddress, sid);
/*若指定会话sid匹配，又匹配不上，则直接返回*/
if (rec->session.sid && sid && rec->session.sid != sid)
return 0;
/*比较target name*/
if (strlen(rec->name) && strcmp(rec->name, targetname))
return 0;
/*比较ip地址*/
if (!iscsi_addr_match(rec->conn[0].address, address))
return 0;
/*端口比较*/
if (rec->conn[0].port != -1 && port != rec->conn[0].port)
return 0;
/*iface网络接口比较*/
if (!iface_match(&rec->iface, iface))
return 0;
return 1;
}
/**
* iscsi_addr_match - check if the addrs are to the same ip
* @address1: pattern
* @address2: address to check
*
* If address1 is blank then it matches any string passed in.
*/
static int iscsi_addr_match(char *address1, char *address2)
{
struct addrinfo hints1, hints2, *res1, *res2;
int rc;
if (!strlen(address1)) /*address1为空 则匹配中任何ip*/
return 1;
if (!strcmp(address1, address2))/*直接ip字符串匹配*/
return 1;
memset(&hints1, 0, sizeof(struct addrinfo));
hints1.ai_family = AF_UNSPEC;
hints1.ai_socktype = SOCK_STREAM;
memset(&hints2, 0, sizeof(struct addrinfo));
hints2.ai_family = AF_UNSPEC;
hints2.ai_socktype = SOCK_STREAM;
/*
* didn't match so we have to resolve to see if one is a dnsname
* that matches a ip address.
*/
/*若上面没有匹配中，则要查看是否传入的是域名，需要先解析*/
rc = getaddrinfo(address1, NULL, &hints1, &res1);
if (rc) {
log_debug(1, "Match error. Could not resolve %s: %s", address1,
gai_strerror(rc));
return 0;
}
rc = getaddrinfo(address2, NULL, &hints2, &res2);
if (rc) {
log_debug(1, "Match error. Could not resolve %s: %s", address2,
gai_strerror(rc));
rc = 0;
goto free_res1;
}
/*将返回的ip进行比较*/
if ((res1->ai_addrlen != res2->ai_addrlen) ||
memcmp(res1->ai_addr, res2->ai_addr, res2->ai_addrlen))
rc = 0;
else
rc = 1;
freeaddrinfo(res2);
free_res1:
freeaddrinfo(res1);
return rc;
}
/*iface网络接口比较 */
int iface_match(struct iface_rec *pattern, struct iface_rec *iface)
{
if (!pattern || !iface) //任一为空，则匹配中
return 1;
if (!strlen(pattern->name))
return 1;
if (!strcmp(pattern->name, iface->name)) {
if (!strcmp(pattern->name, DEFAULT_IFACENAME))
return 1;
/*
* For default we allow the same name, but different
* transports.
*/
if (!strlen(pattern->transport_name))
return 1;
if (!strcmp(pattern->transport_name, iface->transport_name))
return 1;
/* fall through */
}
return 0;
}
另一个查找路径：
/*在sys目录下查找*/
int iscsi_sysfs_for_each_session(void *data, int *nr_found,
iscsi_sysfs_session_op_fn *fn)
{
struct dirent **namelist;
int rc = 0, n, i;
struct session_info *info;
info = calloc(1, sizeof(*info));
if (!info)
return ISCSI_ERR_NOMEM;
//扫描目录下的所有目录名和文件，但不会进入子目录扫面
n = scandir(ISCSI_SESSION_DIR, &namelist, trans_filter,
alphasort);
if (n <= 0)
goto free_info;
for (i = 0; i < n; i++) {
rc = iscsi_sysfs_get_sessioninfo_by_id(info, //根据会话名返回会话的信息
namelist[i]->d_name);
if (rc) {
log_error("could not find session info for %s",
namelist[i]->d_name);
/* raced. session was shutdown while looping */
rc = 0;
continue;
}
rc = fn(data, info);
if (rc > 0)
break;
else if (rc == 0)
(*nr_found)++;
else
/* if less than zero it means it was not a match */
rc = 0;
}
for (i = 0; i < n; i++)
free(namelist[i]);
free(namelist);
free_info:
free(info);
return rc;
}
/*根据会话id，返回会话信息*/
int iscsi_sysfs_get_sessioninfo_by_id(struct session_info *info, char *session)
{
char id[NAME_SIZE];
int ret, pers_failed = 0;
uint32_t host_no;
if (sscanf(session, "session%d", &info->sid) != 1) { //获取会话id
log_error("invalid session '%s'", session);
return ISCSI_ERR_INVAL;
}
ret = sysfs_get_str(session, ISCSI_SESSION_SUBSYS, "targetname",
info->targetname, sizeof(info->targetname));
if (ret) {
log_error("could not read session targetname: %d", ret);
return ISCSI_ERR_SYSFS_LOOKUP;
}
ret = sysfs_get_str(session, ISCSI_SESSION_SUBSYS, "username",
(info->chap).username,
sizeof((info->chap).username));
if (ret)
log_debug(5, "could not read username: %d", ret);
ret = sysfs_get_str(session, ISCSI_SESSION_SUBSYS, "password",
(info->chap).password,
sizeof((info->chap).password));
if (ret)
log_debug(5, "could not read password: %d", ret);
ret = sysfs_get_str(session, ISCSI_SESSION_SUBSYS, "username_in",
(info->chap).username_in,
sizeof((info->chap).username_in));
if (ret)
log_debug(5, "could not read username in: %d", ret);
ret = sysfs_get_str(session, ISCSI_SESSION_SUBSYS, "password_in",
(info->chap).password_in,
sizeof((info->chap).password_in));
if (ret)
log_debug(5, "could not read password in: %d", ret);
ret = sysfs_get_int(session, ISCSI_SESSION_SUBSYS, "recovery_tmo",
&((info->tmo).recovery_tmo));
if (ret)
(info->tmo).recovery_tmo = -1;
ret = sysfs_get_int(session, ISCSI_SESSION_SUBSYS, "lu_reset_tmo",
&((info->tmo).lu_reset_tmo));
if (ret)
(info->tmo).lu_reset_tmo = -1;
ret = sysfs_get_int(session, ISCSI_SESSION_SUBSYS, "tgt_reset_tmo",
&((info->tmo).tgt_reset_tmo));
if (ret)
(info->tmo).lu_reset_tmo = -1;
sysfs_get_int(session, ISCSI_SESSION_SUBSYS, "abort_tmo",
&((info->tmo).abort_tmo));
if (ret)
(info->tmo).abort_tmo = -1;
ret = sysfs_get_int(session, ISCSI_SESSION_SUBSYS, "tpgt",
&info->tpgt);
if (ret) {
log_error("could not read session tpgt: %d", ret);
return ISCSI_ERR_SYSFS_LOOKUP;
}
snprintf(id, sizeof(id), ISCSI_CONN_ID, info->sid);
/* some HW drivers do not export addr and port */
memset(info->persistent_address, 0, NI_MAXHOST);
ret = sysfs_get_str(id, ISCSI_CONN_SUBSYS, "persistent_address",
info->persistent_address,
sizeof(info->persistent_address));
if (ret) {
pers_failed = 1;
/* older qlogic does not support this */
log_debug(5, "could not read pers conn addr: %d", ret);
}
memset(info->address, 0, NI_MAXHOST);
ret = sysfs_get_str(id, ISCSI_CONN_SUBSYS, "address",
info->address, sizeof(info->address));
if (ret) {
log_debug(5, "could not read curr addr: %d", ret);
/* iser did not export this */
if (!pers_failed)
strcpy(info->address, info->persistent_address);
} else if (pers_failed)
/*
* for qla if we could not get the persistent addr
* we will use the current for both addrs
*/
strcpy(info->persistent_address, info->address);
pers_failed = 0;
info->persistent_port = -1;
ret = sysfs_get_int(id, ISCSI_CONN_SUBSYS, "persistent_port",
&info->persistent_port);
if (ret) {
pers_failed = 1;
log_debug(5, "Could not read pers conn port %d", ret);
}
info->port = -1;
ret = sysfs_get_int(id, ISCSI_CONN_SUBSYS, "port", &info->port);
if (ret) {
/* iser did not export this */
if (!pers_failed)
info->port = info->persistent_port;
log_debug(5, "Could not read curr conn port %d", ret);
} else if (pers_failed)
/*
* for qla if we could not get the persistent addr
* we will use the current for both addrs
*/
info->persistent_port = info->port;
ret = 0;
host_no = iscsi_sysfs_get_host_no_from_sid(info->sid, &ret);
if (ret) {
log_error("could not get host_no for session%d: %s.",
info->sid, iscsi_err_to_str(ret));
return ret;
}
iscsi_sysfs_read_iface(&info->iface, host_no, session, NULL);
log_debug(7, "found targetname %s address %s pers address %s port %d "
"pers port %d driver %s iface name %s ipaddress %s "
"netdev %s hwaddress %s iname %s",
info->targetname, info->address ? info->address : "NA",
info->persistent_address ? info->persistent_address : "NA",
info->port, info->persistent_port, info->iface.transport_name,
info->iface.name, info->iface.ipaddress,
info->iface.netdev, info->iface.hwaddress,
info->iface.iname);
return 0;
}
判断会话是否存在后。若存在则直接返回，否则接着进行创建会话等：
open-iscsi支持这几种传输模式：
static struct iscsi_transport_template *iscsi_transport_templates[] = {
&iscsi_tcp,
&iscsi_iser,
&cxgb3i,
&cxgb4i,
&bnx2i,
&qla4xxx,
&be2iscsi,
NULL
};
对应的是一个结构体，这个结构体中是一些操作函数：
truct iscsi_transport_template iscsi_tcp = {
.name = "tcp",
.ep_connect = iscsi_io_tcp_connect,
.ep_poll = iscsi_io_tcp_poll,
.ep_disconnect = iscsi_io_tcp_disconnect,
};
struct iscsi_transport_template iscsi_iser = {
.name = "iser",
.rdma = 1,
.ep_connect = ktransport_ep_connect,
.ep_poll = ktransport_ep_poll,
.ep_disconnect = ktransport_ep_disconnect,
.create_conn = iser_create_conn,
};
struct iscsi_transport_template cxgb3i = {
.name = "cxgb3i",
.set_host_ip = 1,
.ep_connect = ktransport_ep_connect,
.ep_poll = ktransport_ep_poll,
.ep_disconnect = ktransport_ep_disconnect,
.create_conn = cxgbi_create_conn,
};
struct iscsi_transport_template cxgb4i = {
.name = "cxgb4i",
.set_host_ip = 1,
.ep_connect = ktransport_ep_connect,
.ep_poll = ktransport_ep_poll,
.ep_disconnect = ktransport_ep_disconnect,
.create_conn = cxgbi_create_conn,
};
struct iscsi_transport_template bnx2i = {
.name = "bnx2i",
.set_host_ip = 1,
.ep_connect = ktransport_ep_connect,
.ep_poll = ktransport_ep_poll,
.ep_disconnect = ktransport_ep_disconnect,
};
struct iscsi_transport_template be2iscsi = {
.name = "be2iscsi",
.create_conn = be2iscsi_create_conn,
.ep_connect = ktransport_ep_connect,
.ep_poll = ktransport_ep_poll,
.ep_disconnect = ktransport_ep_disconnect,
};
struct iscsi_transport_template qla4xxx = {
.name = "qla4xxx",
.set_host_ip = 0,
.ep_connect = ktransport_ep_connect,
.ep_poll = ktransport_ep_poll,
.ep_disconnect = ktransport_ep_disconnect,
};
在查找会话是否存在后，搜索对应的transport模式：
t = iscsi_sysfs_get_transport_by_name(rec->iface.transport_name);
在创建会话，建立连接的过程中需要用到传输模式对应结构中的连接函数。
/*根据传输模式的名称，返回这个结构体*/
struct iscsi_transport *iscsi_sysfs_get_transport_by_name(char *transport_name)
{
struct iscsi_transport *t;
int retry = 0;
retry:
/* sync up kernel and userspace */
/*将内核和用户空间支持的传输模式进行同步*/
read_transports();
/* check if the transport is loaded and matches */
list_for_each_entry(t, &transports, list) {
if (t->handle && !strncmp(t->name, transport_name,
ISCSI_TRANSPORT_NAME_MAXLEN))
return t;
}
if (retry < 1) {
retry++;
if (!transport_load_kmod(transport_name)) //判断对应的内核模块是否加载
goto retry;
}
return NULL;
}
/*将用户空间支持的传输模式和内核同步*/
static int read_transports(void)
{
struct dirent **namelist;
int i, n, found;
struct iscsi_transport *t;
log_debug(7, "in %s", __FUNCTION__);
//对ISCSI_TRANSPORT_DIR目录进行扫描
//这个目录下的软链接名称就是系统支持的传输模式
n = scandir(ISCSI_TRANSPORT_DIR, &namelist, trans_filter,
alphasort);
if (n < 0) {
log_error("Could not scan %s.", ISCSI_TRANSPORT_DIR);
return n;
}
for (i = 0; i < n; i++) {
found = 0;
list_for_each_entry(t, &transports, list) { //在系统的全局变量链表transports中查找
if (!strcmp(t->name, namelist[i]->d_name)) { //找到了transport名称
found = 1;
break;
}
}
if (!found) {
/* copy new transport */
t = malloc(sizeof(*t)); //没有这个名称，则分配一个transport结构
if (!t)
continue;
log_debug(7, "Adding new transport %s",
namelist[i]->d_name);
INIT_LIST_HEAD(&t->sessions);
INIT_LIST_HEAD(&t->list);
strlcpy(t->name, namelist[i]->d_name,
ISCSI_TRANSPORT_NAME_MAXLEN);
if (set_transport_template(t)) { //设置对应的模版操作函数
free(t);
return -1;
}
} else
log_debug(7, "Updating transport %s",
namelist[i]->d_name);
if (sysfs_get_uint64(t->name, ISCSI_TRANSPORT_SUBSYS,
"handle", &t->handle)) { //在iscsi錩transport目录下获取handle值，handle是一个文件名，值在这个文件中
if (list_empty(&t->list))
free(t);
else
log_error("Could not update %s.\n",
t->name);
continue;
}
if (sysfs_get_uint(t->name, ISCSI_TRANSPORT_SUBSYS,
"caps", &t->caps)) { //同上，回去caps值
if (list_empty(&t->list))
free(t);
else
log_error("Could not update %s.\n",
t->name);
continue;
}
/*
* tmp hack for qla4xx compat
*/
if (!strcmp(t->name, "qla4xxx")) {
t->caps |= CAP_DATA_PATH_OFFLOAD;
}
if (list_empty(&t->list))
list_add_tail(&t->list, &transports); //将新建的tranport结构体加入到全局变量链表中
}
for (i = 0; i < n; i++) //释放scandir分配的结构
free(namelist[i]);
free(namelist);
num_transports = n; //支持的传输模式数量
return 0;
}
#ifdef USE_KMOD
int transport_load_kmod(char *transport_name)
{
struct kmod_ctx *ctx;
struct kmod_module *mod;
int rc;
ctx = kmod_new(NULL, NULL);
if (!ctx) {
log_error("Could not load transport module %s. Out of "
"memory.", transport_name);
return ISCSI_ERR_NOMEM;
}
kmod_load_resources(ctx);
/*
* dumb dumb dumb - named iscsi_tcp and ib_iser differently from
* transport name
*/
if (!strcmp(transport_name, "tcp"))
rc = kmod_module_new_from_name(ctx, "iscsi_tcp", &mod);
else if (!strcmp(transport_name, "iser"))
rc = kmod_module_new_from_name(ctx, "ib_iser", &mod);
else
rc = kmod_module_new_from_name(ctx, transport_name, &mod);
if (rc) {
log_error("Failed to load module %s.", transport_name);
rc = ISCSI_ERR_TRANS_NOT_FOUND;
goto unref_mod;
}
rc = kmod_module_probe_insert_module(mod, KMOD_PROBE_APPLY_BLACKLIST,
NULL, NULL, NULL, NULL);
if (rc) {
log_error("Could not insert module %s. Kmod error %d",
transport_name, rc);
rc = ISCSI_ERR_TRANS_NOT_FOUND;
}
kmod_module_unref(mod);
unref_mod:
kmod_unref(ctx);
return rc;
}
#else
int transport_load_kmod(char *transport_name)
{
char *cmdline[4];
pid_t pid;
cmdline[0] = "/sbin/modprobe";
cmdline[1] = "-qb";
cmdline[3] = NULL;
/*
* dumb dumb mistake - named iscsi_tcp and ib_iser differently from
* transport name
*/
if (!strcmp(transport_name, "tcp"))
cmdline[2] = "iscsi_tcp";
else if (!strcmp(transport_name, "iser"))
cmdline[2] = "ib_iser";
else
cmdline[2] = transport_name;
if (iscsi_sysfs_is_transport_loaded(cmdline[2]))
return 0;
pid = fork();
if (pid == 0) {
if (execv("/sbin/modprobe", cmdline) < 0) {
log_error("Failed to load module %s: %s",
transport_name, strerror(errno));
exit(-errno);
}
exit(0);
} else if (pid < 0) {
log_error("Failed to fork process to load module %s: %s",
transport_name, strerror(errno));
return ISCSI_ERR_TRANS_NOT_FOUND;
}
if (waitpid(pid, NULL, 0) < 0) {
log_error("Failed to load module %s", transport_name);
return ISCSI_ERR_TRANS_NOT_FOUND;
}
return 0;
}
#endif
/*设置对应传输模式的模版操作函数*/
int set_transport_template(struct iscsi_transport *t)
{
struct iscsi_transport_template *tmpl;
int j;
for (j = 0; iscsi_transport_templates[j] != NULL; j++) { //已支持的传输模式的模版函数数组
tmpl = iscsi_transport_templates[j];
if (!strcmp(tmpl->name, t->name)) { //比较传输模式名称是否相同
t->template = tmpl; /*一样则设置模版函数*/
log_debug(3, "Matched transport %s\n", t->name);
return 0;
}
}
log_error("Could not find template for %s. An updated iscsiadm "
"is probably needed.\n", t->name);
return ENOSYS;
}
//进入最主要的工作，创建会话
session = __session_create(rec, t);
*这里主要是分配一个session结构，并进行一些设置*/
static iscsi_session_t*
__session_create(node_rec_t *rec, struct iscsi_transport *t)
{
iscsi_session_t *session;
int hostno, rc = 0;
session = calloc(1, sizeof (*session)); //分配session结构
if (session == NULL) {
log_debug(1, "can not allocate memory for session");
return NULL;
}
log_debug(2, "Allocted session %p", session);
INIT_LIST_HEAD(&session->list);
session->t = t; //设置其transport结构
session->reopen_qtask.mgmt_ipc_fd = -1;
session->id = -1;
session->use_ipc = 1;
/* save node record. we might need it for redirection */
memcpy(&session->nrec, rec, sizeof(node_rec_t)); //保存node记录
session->portal_group_tag = rec->tpgt;
session->type = ISCSI_SESSION_TYPE_NORMAL;
session->r_stage = R_STAGE_NO_CHANGE;
strlcpy(session->target_name, rec->name, TARGET_NAME_MAXLEN);
if (strlen(session->nrec.iface.iname))
session->initiator_name = session->nrec.iface.iname;
else if (dconfig->initiator_name)
session->initiator_name = dconfig->initiator_name;
else {
log_error("No initiator name set. Cannot create session.");
free(session);
return NULL;
}
if (strlen(session->nrec.iface.alias))
session->initiator_alias = session->nrec.iface.alias;
else
session->initiator_alias = dconfig->initiator_alias;
/* session's eh parameters */
session->replacement_timeout = rec->session.timeo.replacement_timeout;
session->fast_abort = rec->session.iscsi.FastAbort;
session->abort_timeout = rec->session.err_timeo.abort_timeout;
session->lu_reset_timeout = rec->session.err_timeo.lu_reset_timeout;
session->tgt_reset_timeout = rec->session.err_timeo.tgt_reset_timeout;
session->host_reset_timeout = rec->session.err_timeo.host_reset_timeout;
/* OUI and uniqifying number */
session->isid[0] = DRIVER_ISID_0;
session->isid[1] = DRIVER_ISID_1;
session->isid[2] = DRIVER_ISID_2;
session->isid[3] = 0;
session->isid[4] = 0;
session->isid[5] = 0;
/* setup authentication variables for the session*/
iscsi_setup_authentication(session, &rec->session.auth);
session->param_mask = ~0ULL;
if (!(t->caps & CAP_MULTI_R2T))
session->param_mask &= ~ISCSI_MAX_R2T;
if (!(t->caps & CAP_HDRDGST))
session->param_mask &= ~ISCSI_HDRDGST_EN;
if (!(t->caps & CAP_DATADGST))
session->param_mask &= ~ISCSI_DATADGST_EN;
if (!(t->caps & CAP_MARKERS)) {
session->param_mask &= ~ISCSI_IFMARKER_EN;
session->param_mask &= ~ISCSI_OFMARKER_EN;
}
hostno = iscsi_sysfs_get_host_no_from_hwinfo(&rec->iface, &rc);
if (!rc) {
/*
* if the netdev or mac was set, then we are going to want
* to want to bind the all the conns/eps to a specific host
* if offload is used.
*/
session->conn[0].bind_ep = 1;
session->hostno = hostno;
}
list_add_tail(&session->list, &t->sessions);//将新建的session结构，加入系统session链表中
return session;
}
//与target端建立连接
rc = __session_conn_create(session, 0);
if (rc) {
__session_destroy(session);
return rc;
}
conn = &session->conn[0];
qtask->conn = conn;
//与target端建立连接
static int
__session_conn_create(iscsi_session_t *session, int cid)
{
iscsi_conn_t *conn = &session->conn[cid];
conn_rec_t *conn_rec = &session->nrec.conn[cid];
int err;
if (iscsi_ev_context_alloc(conn)) {
log_error("cannot allocate context_pool for conn cid %d", cid);
return ISCSI_ERR_NOMEM;
}
conn->state = ISCSI_CONN_STATE_FREE;
conn->session = session;
/*
* TODO: we must export the socket_fd/transport_eph from sysfs
* so if iscsid is resyncing up we can pick that up and cleanup up
* the old connection. Right now we leak a connection.
* We can also probably merge these two fields.
*/
conn->socket_fd = -1;
conn->transport_ep_handle = -1;
/* connection's timeouts */
conn->id = cid;
conn->logout_timeout = conn_rec->timeo.logout_timeout;
if (!conn->logout_timeout) {
log_error("Invalid timeo.logout_timeout. Must be greater "
"than zero. Using default %d.\n",
DEF_LOGOUT_TIMEO);
conn->logout_timeout = DEF_LOGOUT_TIMEO;
}
conn->login_timeout = conn_rec->timeo.login_timeout;
if (!conn->login_timeout) {
log_error("Invalid timeo.login_timeout. Must be greater "
"than zero. Using default %d.\n",
DEF_LOGIN_TIMEO);
conn->login_timeout = DEF_LOGIN_TIMEO;
}
conn->auth_timeout = conn_rec->timeo.auth_timeout;
/* noop-out setting */
conn->noop_out_interval = conn_rec->timeo.noop_out_interval;
conn->noop_out_timeout = conn_rec->timeo.noop_out_timeout;
if (conn->noop_out_interval && !conn->noop_out_timeout) {
log_error("Invalid timeo.noop_out_timeout. Must be greater "
"than zero. Using default %d.\n",
DEF_NOOP_OUT_TIMEO);
conn->noop_out_timeout = DEF_NOOP_OUT_TIMEO;
}
if (conn->noop_out_timeout && !conn->noop_out_interval) {
log_error("Invalid timeo.noop_out_interval. Must be greater "
"than zero. Using default %d.\n",
DEF_NOOP_OUT_INTERVAL);
conn->noop_out_interval = DEF_NOOP_OUT_INTERVAL;
}
//复制参数
iscsi_copy_operational_params(conn, &session->nrec.session.iscsi,
&conn_rec->iscsi);
/* TCP options */
conn->tcp_window_size = conn_rec->tcp.window_size;
/* FIXME: type_of_service */
/* resolve the string address to an IP address */
err = iscsi_setup_portal(conn, conn_rec->address, conn_rec->port);
if (err)
return err;
return 0;
}
if (iscsi_host_set_net_params(&rec->iface, session)) {
__session_destroy(session);
return ISCSI_ERR_LOGIN;
}
if (gettimeofday(&conn->initial_connect_time, NULL))
log_error("Could not get initial connect time. If "
"login errors iscsid may give up the initial "
"login early. You should manually login.");
conn->state = ISCSI_CONN_STATE_XPT_WAIT;
qtask->rsp.command = MGMT_IPC_SESSION_LOGIN;
qtask->rsp.err = ISCSI_SUCCESS;
//连接
if (iscsi_conn_connect(conn, qtask)) {
log_debug(4, "Initial connect failed. Waiting %u seconds "
"before trying to reconnect.\n",
ISCSI_CONN_ERR_REOPEN_DELAY);
queue_delayed_reopen(qtask, ISCSI_CONN_ERR_REOPEN_DELAY);
}
return ISCSI_SUCCESS;
到这里，会话就建立了，然后就是handle函数向请求返回结果了。
参考资料：
1.
