[dm-devel] [PATCH 1/3] multipath: add libmpathvalid library
Martin Wilck
martin.wilck at suse.com
Wed Sep 16 14:18:49 UTC 2020
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 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
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