iscsid.c

iSCSI协议在LINUX下的源码.源代码是IBM公布的.主要是结合其OSD设备用的.

/*
 * iSCSI driver for Linux
 * Copyright (C) 2002 Cisco Systems, Inc.
 * maintained by [e-mail]
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * See the file COPYING included with this distribution for more details.
 *
 * $Id: iscsid.c,v 1.7 2005/01/11 03:47:09 mikenc Exp $
 *
 * iSCSI Daemon
 *
 */
#include <stdint.h>
#include <unistd.h>
#include <errno.h>
#include <poll.h>
#include <sys/wait.h>
#include <sysfs/libsysfs.h>

#include "iscsi-sfnet.h"
#include "iscsi-protocol.h"
#include "iscsi-discovery.h"
#include "iscsi-hooks.h"

#define ISCSI_TRANSPORT_CLASS "iscsi_transport_class"

/* global config info */
struct iscsi_daemon_config daemon_config;

/* global so that the signal handlers can reset the pids */
static struct iscsi_discovery_process_list discovery_processes;
static struct iscsi_session_process_list session_processes;
static struct iscsi_target_list targets;

static void
sigpipe_handler(int unused)
{
	debugmsg(1, "received sigpipe");
}

void
sigchld_handler(int unused)
{
	pid_t pid = 0;
	int status = 0;
	struct iscsi_discovery_process *discovery;
	struct iscsi_session_process *session;

      wait_pid:
	while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
		if (WIFEXITED(status))
			debugmsg(1, "child %d exited with status %d", pid,
				 WEXITSTATUS(status));
		if (WIFSIGNALED(status))
			debugmsg(1, "child %d exited on signal %d", pid,
				 WTERMSIG(status));
		if (WIFSTOPPED(status))
			debugmsg(1, "child %d stopped on signal %d", pid,
				 WSTOPSIG(status));

		/* reset pids if the child was a discovery or target process */
		for (discovery = discovery_processes.head; discovery;
		     discovery = discovery->next) {
			if (discovery->pid == pid) {
				discovery->pid = 0;

				if (WIFSIGNALED(status)) {
					/* if the process doesn't want a
					 * particular signal to restart it,
					 * it should catch the signal and exit
					 * (0);
					 */
					discovery->restart = 1;
					discovery_processes.changed = 1;
					debugmsg(1, "discovery process %p "
						 "needs restart because pid %d"
						 " killed by signal %d",
						 discovery, pid,
						 WTERMSIG(status));
				} else if (WIFEXITED(status)
					   && WEXITSTATUS(status)) {
					/* abnormal exit, try again */
					discovery->restart = 1;
					discovery_processes.changed = 1;
					debugmsg(1, "discovery process %p "
						 "needs restart because pid %d"
						 " exited with status 0x%x",
						 discovery, pid,
						 WEXITSTATUS(status));
				} else {
					/* normal exit. */
					discovery->remove = 1;
					discovery_processes.changed = 1;
					debugmsg(1, "discovery process %p pid "
						 "%d fd %d exited normally, "
						 "marking for removal",
						 discovery, pid,
						 discovery->pipe_fd);
				}
				goto wait_pid;
			}
		}
		for (session = session_processes.head; session;
		     session = session->next) {
			if (session->pid == pid) {
				session->pid = 0;
				if (WIFSIGNALED(status)) {
					/* if the process doesn't want a
					 * particular signal to restart it,
					 * it should catch the signal and exit
					 * (0);
					 */
					session_processes.changed = 1;
					session->restart = 1;
					debugmsg(1, "session process %p needs "
						 "restart because pid %d "
						 "killed by signal %d",
						 session, pid,
						 WTERMSIG(status));
				} else if (WIFEXITED(status)) {
					switch (WEXITSTATUS(status)) {
					case 0:
						/* normal exit.  we don't
						 * remove session processes
						 * that exit with status 0,
						 * since that always happens
						 * on Linux because the
						 * session process exits as
						 * soon as the kernel module
						 * ioctl returns, and the
						 * kernel module does all the
						 * real work
						 */
						debugmsg(1, "session process "
							 "%p with pid %d "
							 "exited normally",
							 session, pid);
						session->pid = 0;
						break;
					case ISCSI_SESSION_FAILED_NO_RETRY:
						/* the session process died
						 * after the session failed,
						 * but we don't want
						 * to restart it unless the
						 * user asks for a config
						 * reload.  This can occur if
						 * the session fails due to
						 * authentication or
						 * authorization failures to
						 * all portals.
						 * We don't want to retry
						 * because we might have
						 * discovered a target that we
						 * aren't authorized to use,
						 * and retrying forever would
						 * fill the log.
						 * We do want the user to be
						 * able to request a retry, in
						 * case they've changed
						 * the access controls on the
						 * target and we're now
						 * authorized.
						 */
						debugmsg(1, "session process "
							 "%p with pid %d "
							 "exited, no retry",
							 session, pid);
						session->pid = 0;
						session->failed = 1;
						break;
					default:
						session_processes.changed = 1;
						session->restart = 1;
						debugmsg(1, "session process "
							 "%p needs restart "
							 "becaused pid %d "
							 "exited with status "
							 "0x%x", session, pid,
							 WEXITSTATUS(status));
						break;
					}
				}
				goto wait_pid;
			}
		}
	}
}

static void
fork_discovery_process(struct iscsi_discovery_process *discovery)
{
	int pipes[2];

	discovery->in_progress = 1;

	/* make pipes */
	if (pipe(pipes) < 0) {
		discovery->restart = 1;
		return;
	}

      fork_again:
	if (iscsi_process_should_exit())
		return;

	discovery->pid = fork();
	if (discovery->pid == 0) {
		/* close the read side */
		close(pipes[0]);
		/* save the write side */
		discovery->pipe_fd = pipes[1];

		discovery->pid = getpid();
		debugmsg(3, "started discovery process %p for entry %p",
			 discovery, discovery->entry);
		discovery_process(discovery);
		exit(0);
	} else if (discovery->pid < 0) {
		errormsg("cannot fork discovery %p", discovery);
		sleep(1);
		goto fork_again;
	} else {
		/* close the write side */
		close(pipes[1]);
		/* save the read side */
		discovery->pipe_fd = pipes[0];

		debugmsg(3, "forked child %d for discovery %p, pipe fd %d",
			 discovery->pid, discovery, discovery->pipe_fd);
	}
}

static void
kill_discovery(struct iscsi_discovery_process *discovery)
{
	pid_t pid = discovery->pid;

	if (pid) {
		debugmsg(3, "kill_discovery %p sending SIGTERM to pid %d",
			 discovery, pid);
		kill(pid, SIGTERM);
	}
}

static void
trigger_rediscovery(struct iscsi_discovery_process *discovery)
{
	pid_t pid = discovery->pid;

	debugmsg(1, "triggering rediscovery from process %p", discovery);
	if (pid) {
		kill(pid, SIGHUP);
	}
}

static void
add_discovery(struct iscsi_discovery_process_list *list,
	      struct iscsi_discovery_process *discovery)
{
	sigset_t chld;

	debugmsg(7, "adding discovery %p, head %p, tail %p", discovery,
		 list->head, list->tail);

	/* block SIGCHLD while we're doing this */
	sigemptyset(&chld);
	sigaddset(&chld, SIGCHLD);
	sigprocmask(SIG_BLOCK, &chld, NULL);

	if (list->head) {
		/* append at the tail */
		discovery->next = NULL;
		discovery->prev = list->tail;
		list->tail->next = discovery;
		list->tail = discovery;
	} else {
		/* become the only list element */
		discovery->next = discovery->prev = NULL;
		list->head = list->tail = discovery;
	}
	list->count++;

	sigprocmask(SIG_UNBLOCK, &chld, NULL);
}

void
remove_discovery(struct iscsi_discovery_process_list *list,
		 struct iscsi_discovery_process *discovery)
{
	sigset_t chld;

	/* block SIGCHLD while we're doing this */
	sigemptyset(&chld);
	sigaddset(&chld, SIGCHLD);
	sigprocmask(SIG_BLOCK, &chld, NULL);

	if (discovery == list->head) {
		debugmsg(7, "removing discovery head %p, tail %p", discovery,
			 list->tail);
		list->head = discovery->next;
		if (list->head == NULL)
			list->tail = NULL;
		discovery->next = discovery->prev = NULL;
	} else if (discovery == list->tail) {
		debugmsg(7, "removing discovery tail %p, head %p", discovery,
			 list->head);
		list->tail = discovery->prev;
		list->tail->next = NULL;
		discovery->next = discovery->prev = NULL;
	} else if (discovery->next && discovery->prev) {
		debugmsg(7, "removing interior discovery %p, head %p, tail %p",
			 discovery, list->head, list->tail);
		discovery->next->prev = discovery->prev;
		discovery->prev->next = discovery->next;
		discovery->next = discovery->prev = NULL;
	} else {
		logmsg(AS_ERROR,
		       "couldn't remove discovery process %p from list %p",
		       discovery, list);
	}
	list->count--;

	sigprocmask(SIG_UNBLOCK, &chld, NULL);
}

/* recursively free dynamically allocated memory */
static void
free_discovery(struct iscsi_discovery_process *discovery)
{
	if (discovery->entry) {
		debugmsg(6, "freeing discovery %p with config %p", discovery,
			 discovery->entry);
		free_config_entry(discovery->entry);
		discovery->entry = NULL;
	} else {
		debugmsg(6, "freeing discovery %p with no config", discovery);
	}

	free(discovery);
}

void
show_target(struct iscsi_target *target)
{
	int p = 0;
	struct iscsi_portal_descriptor *portal;

	debugmsg(1, "target %p name %s", target, target->TargetName);
	for (portal = target->current_portals; portal; portal = portal->next) {
		debugmsg(1, "target %p portal[%d]=%p, address %s, ip %u.%u.%u."
			 "%u, port %d, tag %d", target, p++, portal, portal->
			 address, portal->ip[0], portal->ip[1], portal->ip[2],
			 portal->ip[3], portal->port, portal->tag);
	}
}

static void
fork_session_process(struct iscsi_session_process *process)
{
	struct iscsi_session_config *config = process->config;

      fork_again:
	if (iscsi_process_should_exit())
		return;

	process->pid = fork();
	if (process->pid == 0) {
		process->pid = getpid();
		debugmsg(2, "starting iSCSI session process %p config %p for "
			 "bus %d target %d, TargetName %s", process, config,
			 config->iscsi_bus, config->target_id,
			 config->target->TargetName);
		iscsi_session_process(process, process->config);
		exit(0);
	} else if (process->pid < 0) {
		errormsg("cannot fork session process %p", process);
		sleep(1);
		goto fork_again;
	} else {
		debugmsg(2, "forked pid %d for session process %p",
			 process->pid, process);
	}
}

void
add_session_process(struct iscsi_session_process_list *list,
		    struct iscsi_session_process *process)
{
	sigset_t chld;

	/* block SIGCHLD while we're doing this */
	sigemptyset(&chld);
	sigaddset(&chld, SIGCHLD);
	sigprocmask(SIG_BLOCK, &chld, NULL);

	debugmsg(7, "adding session process %p, head %p, tail %p", process,
		 list->head, list->tail);
	if (list->head) {
		/* append at the tail */
		process->next = NULL;
		process->prev = list->tail;
		list->tail->next = process;
		list->tail = process;
	} else {
		/* become the only list element */
		process->next = process->prev = NULL;
		list->head = list->tail = process;
	}
	list->count++;

	sigprocmask(SIG_UNBLOCK, &chld, NULL);
}

void
remove_session_process(struct iscsi_session_process_list *list,
		       struct iscsi_session_process *process)
{
	sigset_t chld;

	/* block SIGCHLD while we're doing this */
	sigemptyset(&chld);
	sigaddset(&chld, SIGCHLD);
	sigprocmask(SIG_BLOCK, &chld, NULL);

	if (process == list->head) {
		debugmsg(7, "removing session process head %p, tail %p",
			 process, list->tail);
		list->head = process->next;
		if (list->head == NULL)
			list->tail = NULL;
		process->next = process->prev = NULL;
	} else if (process == list->tail) {
		debugmsg(7, "removing session process tail %p, head %p",
			 process, list->head);
		list->tail = process->prev;
		list->tail->next = NULL;
		process->next = process->prev = NULL;
	} else if (process->next && process->prev) {
		debugmsg(7, "removing interior process %p, head %p, tail %p",
			 process, list->head, list->tail);
		process->next->prev = process->prev;
		process->prev->next = process->next;
		process->next = process->prev = NULL;
	} else {
		logmsg(AS_ERROR,
		       "couldn't remove session process %p from list %p",
		       process, list);
	}
	list->count--;

	sigprocmask(SIG_UNBLOCK, &chld, NULL);
}

void
free_session_process(struct iscsi_session_process *process)
{
	if (process->config) {
		debugmsg(6, "freeing session process %p with config %p",
			 process, process->config);
		/* Note: caller must free the config if appropriate to do so */
		process->config->process = NULL;
		process->config = NULL;