dm-mpath.c

linux 内核源代码

	return 0;
}

struct arg_set {
	unsigned argc;
	char **argv;
};

static char *shift(struct arg_set *as)
{
	char *r;

	if (as->argc) {
		as->argc--;
		r = *as->argv;
		as->argv++;
		return r;
	}

	return NULL;
}

static void consume(struct arg_set *as, unsigned n)
{
	BUG_ON (as->argc < n);
	as->argc -= n;
	as->argv += n;
}

static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
			       struct dm_target *ti)
{
	int r;
	struct path_selector_type *pst;
	unsigned ps_argc;

	static struct param _params[] = {
		{0, 1024, "invalid number of path selector args"},
	};

	pst = dm_get_path_selector(shift(as));
	if (!pst) {
		ti->error = "unknown path selector type";
		return -EINVAL;
	}

	r = read_param(_params, shift(as), &ps_argc, &ti->error);
	if (r)
		return -EINVAL;

	r = pst->create(&pg->ps, ps_argc, as->argv);
	if (r) {
		dm_put_path_selector(pst);
		ti->error = "path selector constructor failed";
		return r;
	}

	pg->ps.type = pst;
	consume(as, ps_argc);

	return 0;
}

static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
			       struct dm_target *ti)
{
	int r;
	struct pgpath *p;

	/* we need at least a path arg */
	if (as->argc < 1) {
		ti->error = "no device given";
		return NULL;
	}

	p = alloc_pgpath();
	if (!p)
		return NULL;

	r = dm_get_device(ti, shift(as), ti->begin, ti->len,
			  dm_table_get_mode(ti->table), &p->path.dev);
	if (r) {
		ti->error = "error getting device";
		goto bad;
	}

	r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
	if (r) {
		dm_put_device(ti, p->path.dev);
		goto bad;
	}

	return p;

 bad:
	free_pgpath(p);
	return NULL;
}

static struct priority_group *parse_priority_group(struct arg_set *as,
						   struct multipath *m)
{
	static struct param _params[] = {
		{1, 1024, "invalid number of paths"},
		{0, 1024, "invalid number of selector args"}
	};

	int r;
	unsigned i, nr_selector_args, nr_params;
	struct priority_group *pg;
	struct dm_target *ti = m->ti;

	if (as->argc < 2) {
		as->argc = 0;
		ti->error = "not enough priority group aruments";
		return NULL;
	}

	pg = alloc_priority_group();
	if (!pg) {
		ti->error = "couldn't allocate priority group";
		return NULL;
	}
	pg->m = m;

	r = parse_path_selector(as, pg, ti);
	if (r)
		goto bad;

	/*
	 * read the paths
	 */
	r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
	if (r)
		goto bad;

	r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
	if (r)
		goto bad;

	nr_params = 1 + nr_selector_args;
	for (i = 0; i < pg->nr_pgpaths; i++) {
		struct pgpath *pgpath;
		struct arg_set path_args;

		if (as->argc < nr_params)
			goto bad;

		path_args.argc = nr_params;
		path_args.argv = as->argv;

		pgpath = parse_path(&path_args, &pg->ps, ti);
		if (!pgpath)
			goto bad;

		pgpath->pg = pg;
		list_add_tail(&pgpath->list, &pg->pgpaths);
		consume(as, nr_params);
	}

	return pg;

 bad:
	free_priority_group(pg, ti);
	return NULL;
}

static int parse_hw_handler(struct arg_set *as, struct multipath *m)
{
	int r;
	struct hw_handler_type *hwht;
	unsigned hw_argc;
	struct dm_target *ti = m->ti;

	static struct param _params[] = {
		{0, 1024, "invalid number of hardware handler args"},
	};

	r = read_param(_params, shift(as), &hw_argc, &ti->error);
	if (r)
		return -EINVAL;

	if (!hw_argc)
		return 0;

	hwht = dm_get_hw_handler(shift(as));
	if (!hwht) {
		ti->error = "unknown hardware handler type";
		return -EINVAL;
	}

	m->hw_handler.md = dm_table_get_md(ti->table);
	dm_put(m->hw_handler.md);

	r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv);
	if (r) {
		dm_put_hw_handler(hwht);
		ti->error = "hardware handler constructor failed";
		return r;
	}

	m->hw_handler.type = hwht;
	consume(as, hw_argc - 1);

	return 0;
}

static int parse_features(struct arg_set *as, struct multipath *m)
{
	int r;
	unsigned argc;
	struct dm_target *ti = m->ti;
	const char *param_name;

	static struct param _params[] = {
		{0, 3, "invalid number of feature args"},
		{1, 50, "pg_init_retries must be between 1 and 50"},
	};

	r = read_param(_params, shift(as), &argc, &ti->error);
	if (r)
		return -EINVAL;

	if (!argc)
		return 0;

	do {
		param_name = shift(as);
		argc--;

		if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) {
			r = queue_if_no_path(m, 1, 0);
			continue;
		}

		if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
		    (argc >= 1)) {
			r = read_param(_params + 1, shift(as),
				       &m->pg_init_retries, &ti->error);
			argc--;
			continue;
		}

		ti->error = "Unrecognised multipath feature request";
		r = -EINVAL;
	} while (argc && !r);

	return r;
}

static int multipath_ctr(struct dm_target *ti, unsigned int argc,
			 char **argv)
{
	/* target parameters */
	static struct param _params[] = {
		{1, 1024, "invalid number of priority groups"},
		{1, 1024, "invalid initial priority group number"},
	};

	int r;
	struct multipath *m;
	struct arg_set as;
	unsigned pg_count = 0;
	unsigned next_pg_num;

	as.argc = argc;
	as.argv = argv;

	m = alloc_multipath(ti);
	if (!m) {
		ti->error = "can't allocate multipath";
		return -EINVAL;
	}

	r = parse_features(&as, m);
	if (r)
		goto bad;

	r = parse_hw_handler(&as, m);
	if (r)
		goto bad;

	r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
	if (r)
		goto bad;

	r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
	if (r)
		goto bad;

	/* parse the priority groups */
	while (as.argc) {
		struct priority_group *pg;

		pg = parse_priority_group(&as, m);
		if (!pg) {
			r = -EINVAL;
			goto bad;
		}

		m->nr_valid_paths += pg->nr_pgpaths;
		list_add_tail(&pg->list, &m->priority_groups);
		pg_count++;
		pg->pg_num = pg_count;
		if (!--next_pg_num)
			m->next_pg = pg;
	}

	if (pg_count != m->nr_priority_groups) {
		ti->error = "priority group count mismatch";
		r = -EINVAL;
		goto bad;
	}

	return 0;

 bad:
	free_multipath(m);
	return r;
}

static void multipath_dtr(struct dm_target *ti)
{
	struct multipath *m = (struct multipath *) ti->private;

	flush_workqueue(kmultipathd);
	free_multipath(m);
}

/*
 * Map bios, recording original fields for later in case we have to resubmit
 */
static int multipath_map(struct dm_target *ti, struct bio *bio,
			 union map_info *map_context)
{
	int r;
	struct dm_mpath_io *mpio;
	struct multipath *m = (struct multipath *) ti->private;

	mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
	dm_bio_record(&mpio->details, bio);

	map_context->ptr = mpio;
	bio->bi_rw |= (1 << BIO_RW_FAILFAST);
	r = map_io(m, bio, mpio, 0);
	if (r < 0 || r == DM_MAPIO_REQUEUE)
		mempool_free(mpio, m->mpio_pool);

	return r;
}

/*
 * Take a path out of use.
 */
static int fail_path(struct pgpath *pgpath)
{
	unsigned long flags;
	struct multipath *m = pgpath->pg->m;

	spin_lock_irqsave(&m->lock, flags);

	if (!pgpath->path.is_active)
		goto out;

	DMWARN("Failing path %s.", pgpath->path.dev->name);

	pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
	pgpath->path.is_active = 0;
	pgpath->fail_count++;

	m->nr_valid_paths--;

	if (pgpath == m->current_pgpath)
		m->current_pgpath = NULL;

	dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
		      pgpath->path.dev->name, m->nr_valid_paths);

	queue_work(kmultipathd, &m->trigger_event);

out:
	spin_unlock_irqrestore(&m->lock, flags);

	return 0;
}

/*
 * Reinstate a previously-failed path
 */
static int reinstate_path(struct pgpath *pgpath)
{
	int r = 0;
	unsigned long flags;
	struct multipath *m = pgpath->pg->m;

	spin_lock_irqsave(&m->lock, flags);

	if (pgpath->path.is_active)
		goto out;

	if (!pgpath->pg->ps.type) {
		DMWARN("Reinstate path not supported by path selector %s",
		       pgpath->pg->ps.type->name);
		r = -EINVAL;
		goto out;
	}

	r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
	if (r)
		goto out;

	pgpath->path.is_active = 1;

	m->current_pgpath = NULL;
	if (!m->nr_valid_paths++ && m->queue_size)
		queue_work(kmultipathd, &m->process_queued_ios);

	dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
		      pgpath->path.dev->name, m->nr_valid_paths);

	queue_work(kmultipathd, &m->trigger_event);

out:
	spin_unlock_irqrestore(&m->lock, flags);

	return r;
}

/*
 * Fail or reinstate all paths that match the provided struct dm_dev.
 */
static int action_dev(struct multipath *m, struct dm_dev *dev,
		      action_fn action)
{
	int r = 0;
	struct pgpath *pgpath;
	struct priority_group *pg;

	list_for_each_entry(pg, &m->priority_groups, list) {
		list_for_each_entry(pgpath, &pg->pgpaths, list) {
			if (pgpath->path.dev == dev)
				r = action(pgpath);
		}
	}

	return r;
}

/*
 * Temporarily try to avoid having to use the specified PG
 */
static void bypass_pg(struct multipath *m, struct priority_group *pg,
		      int bypassed)
{
	unsigned long flags;

	spin_lock_irqsave(&m->lock, flags);

	pg->bypassed = bypassed;
	m->current_pgpath = NULL;
	m->current_pg = NULL;

	spin_unlock_irqrestore(&m->lock, flags);

	queue_work(kmultipathd, &m->trigger_event);
}

/*
 * Switch to using the specified PG from the next I/O that gets mapped
 */
static int switch_pg_num(struct multipath *m, const char *pgstr)
{
	struct priority_group *pg;
	unsigned pgnum;
	unsigned long flags;

	if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
	    (pgnum > m->nr_priority_groups)) {
		DMWARN("invalid PG number supplied to switch_pg_num");
		return -EINVAL;
	}

	spin_lock_irqsave(&m->lock, flags);