[dm-devel] [PATCH 1/3] multipath: add libmpathvalid library
Benjamin Marzinski
bmarzins at redhat.com
Thu Sep 17 23:52:42 UTC 2020
On Wed, Sep 16, 2020 at 02:18:49PM +0000, Martin Wilck wrote:
> On Tue, 2020-09-15 at 16:45 -0500, Benjamin Marzinski wrote:
> > This library allows other programs to check if a path should be
> > claimed
> > by multipath. It exports an init and exit function, a pointer to a
> > struct config, that stores the configuration which is dealt with in
> > the
> > init and exit functions, and two more functions.
> >
> > mpath_get_mode() get the configured find_multipaths mode.
> > mpath_is_path() returns whether the device is claimed by multipath,
> > and
> > optionally returns the wwid. This code works slightly different than
> > the multipath -c/u code for SMART mode. Instead of checking all the
> > existing paths to see if another has the same wwid, it expects the
> > caller to pass in an array of the already known path wwids, and
> > checks
> > if the current path matches any of those.
> >
> > The library also doesn't set up the device-mapper log fuctions. It
> > leaves this up to the caller.
> >
> > Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> > ---
> > Makefile | 3 +-
> > libmpathvalid/Makefile | 38 +++++++
> > libmpathvalid/libmpathvalid.version | 10 ++
> > libmpathvalid/mpath_valid.c | 168
> > ++++++++++++++++++++++++++++
> > libmpathvalid/mpath_valid.h | 57 ++++++++++
> > 5 files changed, 275 insertions(+), 1 deletion(-)
> > create mode 100644 libmpathvalid/Makefile
> > create mode 100644 libmpathvalid/libmpathvalid.version
> > create mode 100644 libmpathvalid/mpath_valid.c
> > create mode 100644 libmpathvalid/mpath_valid.h
> >
> > diff --git a/Makefile b/Makefile
> > index 4a3491da..f127ff91 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -9,6 +9,7 @@ BUILDDIRS := \
> > libmultipath/checkers \
> > libmultipath/foreign \
> > libmpathpersist \
> > + libmpathvalid \
> > multipath \
> > multipathd \
> > mpathpersist \
> > @@ -29,7 +30,7 @@ $(BUILDDIRS):
> > $(MAKE) -C $@
> >
> > libmultipath libdmmp: libmpathcmd
> > -libmpathpersist multipath multipathd: libmultipath
> > +libmpathpersist libmpathvalid multipath multipathd: libmultipath
> > mpathpersist multipathd: libmpathpersist
> >
> > libmultipath/checkers.install \
> > diff --git a/libmpathvalid/Makefile b/libmpathvalid/Makefile
> > new file mode 100644
> > index 00000000..70b97eca
> > --- /dev/null
> > +++ b/libmpathvalid/Makefile
> > @@ -0,0 +1,38 @@
> > +include ../Makefile.inc
> > +
> > +SONAME = 0
> > +DEVLIB = libmpathvalid.so
> > +LIBS = $(DEVLIB).$(SONAME)
> > +
> > +CFLAGS += $(LIB_CFLAGS) -I$(multipathdir) -I$(mpathcmddir)
> > +
> > +LIBDEPS += -lpthread -ldevmapper -ldl -L$(multipathdir) \
> > + -lmultipath -L$(mpathcmddir) -lmpathcmd -ludev
> > +
> > +OBJS = mpath_valid.o
> > +
> > +all: $(LIBS)
> > +
> > +$(LIBS): $(OBJS)
> > + $(CC) $(LDFLAGS) $(SHARED_FLAGS) -Wl,-soname=$@ -o $@ $(OBJS)
> > $(LIBDEPS) -Wl,--version-script=libmpathvalid.version
> > + $(LN) $(LIBS) $(DEVLIB)
> > +
> > +install: $(LIBS)
> > + $(INSTALL_PROGRAM) -m 755 -d $(DESTDIR)$(syslibdir)
> > + $(INSTALL_PROGRAM) -m 755 $(LIBS)
> > $(DESTDIR)$(syslibdir)/$(LIBS)
> > + $(LN) $(LIBS) $(DESTDIR)$(syslibdir)/$(DEVLIB)
> > + $(INSTALL_PROGRAM) -m 755 -d $(DESTDIR)$(includedir)
> > + $(INSTALL_PROGRAM) -m 644 mpath_valid.h $(DESTDIR)$(includedir)
> > +
> > +uninstall:
> > + $(RM) $(DESTDIR)$(syslibdir)/$(LIBS)
> > + $(RM) $(DESTDIR)$(syslibdir)/$(DEVLIB)
> > + $(RM) $(DESTDIR)$(includedir)/mpath_valid.h
> > +
> > +clean: dep_clean
> > + $(RM) core *.a *.o *.so *.so.* *.gz
> > +
> > +include $(wildcard $(OBJS:.o=.d))
> > +
> > +dep_clean:
> > + $(RM) $(OBJS:.o=.d)
> > diff --git a/libmpathvalid/libmpathvalid.version
> > b/libmpathvalid/libmpathvalid.version
> > new file mode 100644
> > index 00000000..4d8a8ba4
> > --- /dev/null
> > +++ b/libmpathvalid/libmpathvalid.version
> > @@ -0,0 +1,10 @@
> > +MPATH_1.0 {
> > + global:
> > + mpathvalid_conf;
> > + mpathvalid_init;
> > + mpathvalid_exit;
> > + mpathvalid_is_path;
> > + mpathvalid_get_mode;
> > + local:
> > + *;
> > +};
> > diff --git a/libmpathvalid/mpath_valid.c
> > b/libmpathvalid/mpath_valid.c
> > new file mode 100644
> > index 00000000..6153e8b7
> > --- /dev/null
> > +++ b/libmpathvalid/mpath_valid.c
> > @@ -0,0 +1,168 @@
> > +#include <stdlib.h>
> > +#include <stdio.h>
> > +#include <stdint.h>
> > +#include <libdevmapper.h>
> > +#include <libudev.h>
> > +#include <errno.h>
> > +
> > +#include "devmapper.h"
> > +#include "structs.h"
> > +#include "util.h"
> > +#include "config.h"
> > +#include "discovery.h"
> > +#include "wwids.h"
> > +#include "sysfs.h"
> > +#include "mpath_cmd.h"
> > +#include "valid.h"
> > +#include "mpath_valid.h"
> > +
> > +static struct config default_config = { .verbosity = -1 };
> > +struct config *mpathvalid_conf = &default_config;
> > +
> > +static unsigned int get_conf_mode(struct config *conf)
> > +{
> > + if (conf->find_multipaths == FIND_MULTIPATHS_SMART)
> > + return MPATH_SMART;
> > + if (conf->find_multipaths == FIND_MULTIPATHS_GREEDY)
> > + return MPATH_GREEDY;
> > + return MPATH_STRICT;
> > +}
> > +
> > +static void set_conf_mode(struct config *conf, unsigned int mode)
> > +{
> > + if (mode == MPATH_SMART)
> > + conf->find_multipaths = FIND_MULTIPATHS_SMART;
> > + else if (mode == MPATH_GREEDY)
> > + conf->find_multipaths = FIND_MULTIPATHS_GREEDY;
> > + else
> > + conf->find_multipaths = FIND_MULTIPATHS_STRICT;
> > +}
> > +
> > +unsigned int mpathvalid_get_mode(void)
> > +{
> > + int mode;
> > + struct config *conf;
> > +
> > + conf = get_multipath_config();
> > + if (!conf)
> > + return -1;
> > + mode = get_conf_mode(conf);
> > + put_multipath_config(conf);
> > + return mode;
> > +}
> > +
> > +static int convert_result(int result) {
> > + switch (result) {
> > + case PATH_IS_ERROR:
> > + return MPATH_IS_ERROR;
> > + case PATH_IS_NOT_VALID:
> > + return MPATH_IS_NOT_VALID;
> > + case PATH_IS_VALID:
> > + return MPATH_IS_VALID;
> > + case PATH_IS_VALID_NO_CHECK:
> > + return MPATH_IS_VALID_NO_CHECK;
> > + case PATH_IS_MAYBE_VALID:
> > + return MPATH_IS_MAYBE_VALID;
> > + }
> > + return MPATH_IS_ERROR;
> > +}
> > +
> > +int
> > +mpathvalid_init(int verbosity)
> > +{
> > + unsigned int version[3];
> > + struct config *conf;
> > +
> > + default_config.verbosity = verbosity;
> > + skip_libmp_dm_init();
> > + conf = load_config(DEFAULT_CONFIGFILE);
> > + if (!conf)
> > + return -1;
> > + conf->verbosity = verbosity;
> > + if (dm_prereq(version))
> > + goto fail;
> > + memcpy(conf->version, version, sizeof(version));
> > +
> > + mpathvalid_conf = conf;
> > + return 0;
> > +fail:
> > + free_config(conf);
> > + return -1;
> > +}
> > +
> > +int
> > +mpathvalid_exit(void)
> > +{
> > + struct config *conf = mpathvalid_conf;
> > +
> > + default_config.verbosity = -1;
> > + if (mpathvalid_conf == &default_config)
> > + return 0;
> > + mpathvalid_conf = &default_config;
> > + free_config(conf);
> > + return 0;
> > +}
> > +
> > +/*
> > + * name: name of path to check
> > + * mode: mode to use for determination. MPATH_DEFAULT uses
> > configured mode
> > + * info: on success, contains the path wwid
> > + * paths: array of the returned mpath_info from other claimed paths
> > + * nr_paths: the size of the paths array
> > + */
> > +int
> > +mpathvalid_is_path(const char *name, unsigned int mode, char **wwid,
> > + const char **path_wwids, unsigned int nr_paths)
> > +{
> > + struct config *conf;
> > + int r = MPATH_IS_ERROR;
> > + unsigned int i;
> > + struct path *pp;
> > +
> > + if (!name || mode >= MPATH_MAX_MODE)
> > + return r;
> > +
> > + if (nr_paths > 0 && !path_wwids)
> > + return r;
> > +
> > + pp = alloc_path();
> > + if (!pp)
> > + return r;
> > +
> > + if (wwid) {
> > + *wwid = (char *)malloc(WWID_SIZE);
> > + if (!*wwid)
> > + goto out;
> > + }
> > +
> > + conf = get_multipath_config();
> > + if (!conf || conf == &default_config)
> > + goto out_wwid;
> > + if (mode != MPATH_DEFAULT)
> > + set_conf_mode(conf, mode);
> > + r = convert_result(is_path_valid(name, conf, pp, true));
> > + put_multipath_config(conf);
> > +
> > + if (r == MPATH_IS_MAYBE_VALID) {
> > + for (i = 0; i < nr_paths; i++) {
> > + if (strncmp(path_wwids[i], pp->wwid, WWID_SIZE)
> > == 0) {
> > + r = MPATH_IS_VALID;
> > + break;
> > + }
> > + }
> > + }
> > +
> > +out_wwid:
> > + if (wwid) {
> > + if (r == MPATH_IS_VALID || r == MPATH_IS_VALID_NO_CHECK
> > ||
> > + r == MPATH_IS_MAYBE_VALID)
> > + strlcpy(*wwid, pp->wwid, WWID_SIZE);
> > + else {
> > + free(*wwid);
> > + *wwid = NULL;
> > + }
> > + }
> > +out:
> > + free_path(pp);
> > + return r;
> > +}
> > diff --git a/libmpathvalid/mpath_valid.h
> > b/libmpathvalid/mpath_valid.h
> > new file mode 100644
> > index 00000000..7fd8aa47
> > --- /dev/null
> > +++ b/libmpathvalid/mpath_valid.h
> > @@ -0,0 +1,57 @@
> > +/*
> > + * Copyright (C) 2015 Red Hat, Inc.
> > + *
> > + * This file is part of the device-mapper multipath userspace tools.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU Lesser General Public
> > License
> > + * along with this program. If not, see <
> > http://www.gnu.org/licenses/>;.
> > + */
> > +
> > +#ifndef LIB_MPATH_VALID_H
> > +#define LIB_MPATH_VALID_H
> > +
> > +#ifdef __cpluscplus
> > +extern "C" {
> > +#endif
> > +
> > +enum mpath_valid_mode {
> > + MPATH_DEFAULT,
> > + MPATH_STRICT,
> > + MPATH_SMART,
> > + MPATH_GREEDY,
> > + MPATH_MAX_MODE, /* used only for bounds checking */
> > +};
> > +
> > +/* MPATH_IS_VALID_NO_CHECK is used to skip checks to see if the
> > device
> > + * has already been unclaimed by multipath in the past */
> > +enum mpath_valid_result {
> > + MPATH_IS_ERROR = -1,
> > + MPATH_IS_NOT_VALID,
> > + MPATH_IS_VALID,
> > + MPATH_IS_VALID_NO_CHECK,
> > + MPATH_IS_MAYBE_VALID,
> > +};
> > +
> > +struct config;
> > +extern struct config *mpathvalid_conf;
>
> What do you need this for?
This isn't really necessary. Library users are expected to define
methods like
struct config *get_multipath_config(void)
{
return mpathvalid_conf;
}
void put_multipath_config(__attribute__((unused))void *conf)
{
/* Noop */
}
It would be possible to have mpathvalid_init() return
struct config *
and mpathvalid_exit() take that pointer. That would allow the caller to
name their config pointer whatever they liked. However the only thing
that the caller can effect is the verbosity, so there's never really any
point to have more than one config pointer.
If you have objections, I can switch this to make the library use a
user provided config pointer, instead of declaring one itself.
-Ben
> This looks good to me. It would be even better with a few unit
> tests...
>
> Anyway, I've been working on a patch set to spare callers to define
> the symbols {get,put}_multipath_config, udev, and logsink (we've been
> discussing that in the past). I'm going to submit it soon. I think you
> might be interested in that for this new library.
>
> Regards
> Martin
More information about the dm-devel
mailing list