[PATCH] multipath: add find_multipaths feature.

[PATCH] multipath: add find_multipaths feature.

[Benjamin Marzinski]

This adds a new default feature, find_multipaths. When this is set to yes,
multipath will no longer try to create a multipath device for every
non-blacklisted device. Instead, it will only create a device when one of
three conditions are met.

1. Three are at least two non-blacklisted paths with the same wwid
2. The user manually forces the creation, by specifying a device with the
   multipath command.
3. A path has the same wwid as a multipath device that was previously crreated
   (even if that multipath device doesn't currently exist).

To do 3, multipath stores the wwid of every path that it creates in
/etc/multipath/wwids. Whenever a path is added it's wwid is checked against
this file.  If there's a match, it is multipathed, even if it's the only path.
This should allow multipath to automatically choose the correct paths to make
into multipath devics in most cases, without needing the user to edit the
blacklist.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 libmultipath/Makefile    |    2 
 libmultipath/alias.c     |  151 ---------------------------------------
 libmultipath/alias.h     |    1 
 libmultipath/config.c    |    1 
 libmultipath/config.h    |    1 
 libmultipath/configure.c |   14 +++
 libmultipath/defaults.h  |    2 
 libmultipath/dict.c      |   34 ++++++++
 libmultipath/file.c      |  178 +++++++++++++++++++++++++++++++++++++++++++++++
 libmultipath/file.h      |   11 ++
 libmultipath/finder.c    |  165 +++++++++++++++++++++++++++++++++++++++++++
 libmultipath/finder.h    |   18 ++++
 multipath/main.c         |    2 
 multipathd/main.c        |    6 +
 14 files changed, 435 insertions(+), 151 deletions(-)

Index: multipath-tools-110713/libmultipath/alias.c
===================================================================
--- multipath-tools-110713.orig/libmultipath/alias.c
+++ multipath-tools-110713/libmultipath/alias.c
@@ -3,19 +3,16 @@
  * Copyright (c) 2005 Benjamin Marzinski, Redhat
  */
 #include <stdlib.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
 #include <errno.h>
 #include <unistd.h>
 #include <string.h>
 #include <limits.h>
 #include <stdio.h>
-#include <signal.h>
 
 #include "debug.h"
 #include "uxsock.h"
 #include "alias.h"
+#include "file.h"
 
 
 /*
@@ -36,148 +33,6 @@
  * See the file COPYING included with this distribution for more details.
  */
 
-static int
-ensure_directories_exist(char *str, mode_t dir_mode)
-{
-	char *pathname;
-	char *end;
-	int err;
-
-	pathname = strdup(str);
-	if (!pathname){
-		condlog(0, "Cannot copy bindings file pathname : %s",
-			strerror(errno));
-		return -1;
-	}
-	end = pathname;
-	/* skip leading slashes */
-	while (end && *end && (*end == '/'))
-		end++;
-
-	while ((end = strchr(end, '/'))) {
-		/* if there is another slash, make the dir. */
-		*end = '\0';
-		err = mkdir(pathname, dir_mode);
-		if (err && errno != EEXIST) {
-			condlog(0, "Cannot make directory [%s] : %s",
-				pathname, strerror(errno));
-			free(pathname);
-			return -1;
-		}
-		if (!err)
-			condlog(3, "Created dir [%s]", pathname);
-		*end = '/';
-		end++;
-	}
-	free(pathname);
-	return 0;
-}
-
-static void
-sigalrm(int sig)
-{
-	/* do nothing */
-}
-
-static int
-lock_bindings_file(int fd)
-{
-	struct sigaction act, oldact;
-	sigset_t set, oldset;
-	struct flock lock;
-	int err;
-
-	memset(&lock, 0, sizeof(lock));
-	lock.l_type = F_WRLCK;
-	lock.l_whence = SEEK_SET;
-
-	act.sa_handler = sigalrm;
-	sigemptyset(&act.sa_mask);
-	act.sa_flags = 0;
-	sigemptyset(&set);
-	sigaddset(&set, SIGALRM);
-
-	sigaction(SIGALRM, &act, &oldact);
-	sigprocmask(SIG_UNBLOCK, &set, &oldset);
-
-	alarm(BINDINGS_FILE_TIMEOUT);
-	err = fcntl(fd, F_SETLKW, &lock);
-	alarm(0);
-
-	if (err) {
-		if (errno != EINTR)
-			condlog(0, "Cannot lock bindings file : %s",
-					strerror(errno));
-		else
-			condlog(0, "Bindings file is locked. Giving up.");
-	}
-
-	sigprocmask(SIG_SETMASK, &oldset, NULL);
-	sigaction(SIGALRM, &oldact, NULL);
-	return err;
-
-}
-
-
-static int
-open_bindings_file(char *file, int *can_write)
-{
-	int fd;
-	struct stat s;
-
-	if (ensure_directories_exist(file, 0700))
-		return -1;
-	*can_write = 1;
-	fd = open(file, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
-	if (fd < 0) {
-		if (errno == EROFS) {
-			*can_write = 0;
-			condlog(3, "Cannot open bindings file [%s] read/write. "
-				" trying readonly", file);
-			fd = open(file, O_RDONLY);
-			if (fd < 0) {
-				condlog(0, "Cannot open bindings file [%s] "
-					"readonly : %s", file, strerror(errno));
-				return -1;
-			}
-		}
-		else {
-			condlog(0, "Cannot open bindings file [%s] : %s", file,
-				strerror(errno));
-			return -1;
-		}
-	}
-	if (*can_write && lock_bindings_file(fd) < 0)
-		goto fail;
-
-	memset(&s, 0, sizeof(s));
-	if (fstat(fd, &s) < 0){
-		condlog(0, "Cannot stat bindings file : %s", strerror(errno));
-		goto fail;
-	}
-	if (s.st_size == 0) {
-		if (*can_write == 0)
-			goto fail;
-		/* If bindings file is empty, write the header */
-		size_t len = strlen(BINDINGS_FILE_HEADER);
-		if (write_all(fd, BINDINGS_FILE_HEADER, len) != len) {
-			condlog(0,
-				"Cannot write header to bindings file : %s",
-				strerror(errno));
-			/* cleanup partially written header */
-			ftruncate(fd, 0);
-			goto fail;
-		}
-		fsync(fd);
-		condlog(3, "Initialized new bindings file [%s]", file);
-	}
-
-	return fd;
-
-fail:
-	close(fd);
-	return -1;
-}
 
 static int
 format_devname(char *name, int id, int len, char *prefix)
@@ -366,7 +221,7 @@ get_user_friendly_alias(char *wwid, char
 		return NULL;
 	}
 
-	fd = open_bindings_file(file, &can_write);
+	fd = open_file(file, &can_write, BINDINGS_FILE_HEADER);
 	if (fd < 0)
 		return NULL;
 
@@ -416,7 +271,7 @@ get_user_friendly_wwid(char *alias, char
 		return NULL;
 	}
 
-	fd = open_bindings_file(file, &unused);
+	fd = open_file(file, &unused, BINDINGS_FILE_HEADER);
 	if (fd < 0)
 		return NULL;
 
Index: multipath-tools-110713/libmultipath/alias.h
===================================================================
--- multipath-tools-110713.orig/libmultipath/alias.h
+++ multipath-tools-110713/libmultipath/alias.h
@@ -1,4 +1,3 @@
-#define BINDINGS_FILE_TIMEOUT 30
 #define BINDINGS_FILE_HEADER \
 "# Multipath bindings, Version : 1.0\n" \
 "# NOTE: this file is automatically maintained by the multipath program.\n" \
Index: multipath-tools-110713/libmultipath/config.c
===================================================================
--- multipath-tools-110713.orig/libmultipath/config.c
+++ multipath-tools-110713/libmultipath/config.c
@@ -497,6 +497,7 @@ load_config (char * file)
 	conf->flush_on_last_del = 0;
 	conf->attribute_flags = 0;
 	conf->reassign_maps = DEFAULT_REASSIGN_MAPS;
+	conf->find_multipaths = DEFAULT_FIND_MULTIPATHS;
 
 	/*
 	 * preload default hwtable
Index: multipath-tools-110713/libmultipath/config.h
===================================================================
--- multipath-tools-110713.orig/libmultipath/config.h
+++ multipath-tools-110713/libmultipath/config.h
@@ -92,6 +92,7 @@ struct config {
 	int attribute_flags;
 	int fast_io_fail;
 	unsigned int dev_loss;
+	int find_multipaths;
 	uid_t uid;
 	gid_t gid;
 	mode_t mode;
Index: multipath-tools-110713/libmultipath/configure.c
===================================================================
--- multipath-tools-110713.orig/libmultipath/configure.c
+++ multipath-tools-110713/libmultipath/configure.c
@@ -35,6 +35,7 @@
 #include "alias.h"
 #include "prio.h"
 #include "util.h"
+#include "finder.h"
 
 extern int
 setup_map (struct multipath * mpp, char * params, int params_size)
@@ -404,6 +405,8 @@ domap (struct multipath * mpp, char * pa
 		 * DM_DEVICE_CREATE, DM_DEVICE_RENAME, or DM_DEVICE_RELOAD
 		 * succeeded
 		 */
+		if (mpp->action == ACT_CREATE)
+			remember_wwid(mpp->wwid);
 		if (!conf->daemon) {
 			/* multipath client mode */
 			dm_switchgroup(mpp->alias, mpp->bestpg);
@@ -463,6 +466,10 @@ coalesce_paths (struct vectors * vecs, v
 
 	memset(empty_buff, 0, WWID_SIZE);
 
+	/* ignore refwwid if it's empty */
+	if (refwwid && !strlen(refwwid))
+		refwwid = NULL;
+
 	if (force_reload) {
 		vector_foreach_slot (pathvec, pp1, k) {
 			pp1->mpp = NULL;
@@ -492,6 +499,13 @@ coalesce_paths (struct vectors * vecs, v
 		if (refwwid && strncmp(pp1->wwid, refwwid, WWID_SIZE))
 			continue;
 
+		/* If find_multipaths was selected check if the path is valid */
+		if (conf->find_multipaths && !refwwid &&
+		    !should_multipath(pp1, pathvec)) {
+			orphan_path(pp1);
+			continue;
+		}
+
 		/*
 		 * at this point, we know we really got a new mp
 		 */
Index: multipath-tools-110713/libmultipath/defaults.h
===================================================================
--- multipath-tools-110713.orig/libmultipath/defaults.h
+++ multipath-tools-110713/libmultipath/defaults.h
@@ -15,6 +15,7 @@
 #define DEFAULT_USER_FRIENDLY_NAMES    0
 #define DEFAULT_VERBOSITY	2
 #define DEFAULT_REASSIGN_MAPS	1
+#define DEFAULT_FIND_MULTIPATHS 0
 
 #define DEFAULT_CHECKINT	5
 #define MAX_CHECKINT(a)		(a << 2)
@@ -24,5 +25,6 @@
 #define DEFAULT_SOCKET		"/var/run/multipathd.sock"
 #define DEFAULT_CONFIGFILE	"/etc/multipath.conf"
 #define DEFAULT_BINDINGS_FILE	"/etc/multipath/bindings"
+#define DEFAULT_WWIDS_FILE	"/etc/multipath/wwids"
 
 char * set_default (char * str);
Index: multipath-tools-110713/libmultipath/dict.c
===================================================================
--- multipath-tools-110713.orig/libmultipath/dict.c
+++ multipath-tools-110713/libmultipath/dict.c
@@ -525,6 +525,27 @@ def_flush_on_last_del_handler(vector str
 }
 
 static int
+def_find_multipaths_handler(vector strvec)
+{
+	char * buff;
+
+	buff = set_value(strvec);
+
+	if (!buff)
+		return 1;
+
+	if ((strlen(buff) == 2 && !strcmp(buff, "no")) ||
+	    (strlen(buff) == 1 && !strcmp(buff, "0")))
+		conf->find_multipaths = 0;
+	else if ((strlen(buff) == 3 && !strcmp(buff, "yes")) ||
+		 (strlen(buff) == 1 && !strcmp(buff, "1")))
+		conf->find_multipaths = 1;
+
+	FREE(buff);
+	return 0;
+}
+
+static int
 names_handler(vector strvec)
 {
 	char * buff;
@@ -2338,6 +2359,18 @@ snprint_def_flush_on_last_del (char * bu
 }
 
 static int
+snprint_def_find_multipaths (char * buff, int len, void * data)
+{
+	if (conf->find_multipaths == DEFAULT_FIND_MULTIPATHS)
+		return 0;
+	if (!conf->find_multipaths)
+		return snprintf(buff, len, "no");
+
+	return snprintf(buff, len, "yes");
+}
+
+
+static int
 snprint_def_user_friendly_names (char * buff, int len, void * data)
 {
 	if (!conf->user_friendly_names)
@@ -2428,6 +2461,7 @@ init_keywords(void)
 	install_keyword("fast_io_fail_tmo", &def_fast_io_fail_handler, &snprint_def_fast_io_fail);
 	install_keyword("dev_loss_tmo", &def_dev_loss_handler, &snprint_def_dev_loss);
 	install_keyword("bindings_file", &bindings_file_handler, &snprint_def_bindings_file);
+	install_keyword("find_multipaths", &def_find_multipaths_handler, &snprint_def_find_multipaths);
 	__deprecated install_keyword("default_selector", &def_selector_handler, NULL);
 	__deprecated install_keyword("default_path_grouping_policy", &def_pgpolicy_handler, NULL);
 	__deprecated install_keyword("default_getuid_callout", &def_getuid_callout_handler, NULL);
Index: multipath-tools-110713/libmultipath/file.c
===================================================================
--- /dev/null
+++ multipath-tools-110713/libmultipath/file.c
@@ -0,0 +1,178 @@
+/*
+ * Copyright (c) 2005 Christophe Varoqui
+ * Copyright (c) 2005 Benjamin Marzinski, Redhat
+ */
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <limits.h>
+#include <stdio.h>
+#include <signal.h>
+
+#include "file.h"
+#include "debug.h"
+#include "uxsock.h"
+
+
+/*
+ * significant parts of this file were taken from iscsi-bindings.c of the
+ * linux-iscsi project.
+ * Copyright (C) 2002 Cisco Systems, Inc.
+ *
+ * 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.
+ */
+
+static int
+ensure_directories_exist(char *str, mode_t dir_mode)
+{
+	char *pathname;
+	char *end;
+	int err;
+
+	pathname = strdup(str);
+	if (!pathname){
+		condlog(0, "Cannot copy file pathname %s : %s",
+			str, strerror(errno));
+		return -1;
+	}
+	end = pathname;
+	/* skip leading slashes */
+	while (end && *end && (*end == '/'))
+		end++;
+
+	while ((end = strchr(end, '/'))) {
+		/* if there is another slash, make the dir. */
+		*end = '\0';
+		err = mkdir(pathname, dir_mode);
+		if (err && errno != EEXIST) {
+			condlog(0, "Cannot make directory [%s] : %s",
+				pathname, strerror(errno));
+			free(pathname);
+			return -1;
+		}
+		if (!err)
+			condlog(3, "Created dir [%s]", pathname);
+		*end = '/';
+		end++;
+	}
+	free(pathname);
+	return 0;
+}
+
+static void
+sigalrm(int sig)
+{
+	/* do nothing */
+}
+
+static int
+lock_file(int fd, char *file_name)
+{
+	struct sigaction act, oldact;
+	sigset_t set, oldset;
+	struct flock lock;
+	int err;
+
+	memset(&lock, 0, sizeof(lock));
+	lock.l_type = F_WRLCK;
+	lock.l_whence = SEEK_SET;
+
+	act.sa_handler = sigalrm;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	sigemptyset(&set);
+	sigaddset(&set, SIGALRM);
+
+	sigaction(SIGALRM, &act, &oldact);
+	sigprocmask(SIG_UNBLOCK, &set, &oldset);
+
+	alarm(FILE_TIMEOUT);
+	err = fcntl(fd, F_SETLKW, &lock);
+	alarm(0);
+
+	if (err) {
+		if (errno != EINTR)
+			condlog(0, "Cannot lock %s : %s", file_name,
+				strerror(errno));
+		else
+			condlog(0, "%s is locked. Giving up.", file_name);
+	}
+
+	sigprocmask(SIG_SETMASK, &oldset, NULL);
+	sigaction(SIGALRM, &oldact, NULL);
+	return err;
+}
+
+int
+open_file(char *file, int *can_write, char *header)
+{
+	int fd;
+	struct stat s;
+
+	if (ensure_directories_exist(file, 0700))
+		return -1;
+	*can_write = 1;
+	fd = open(file, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
+	if (fd < 0) {
+		if (errno == EROFS) {
+			*can_write = 0;
+			condlog(3, "Cannot open file [%s] read/write. "
+				" trying readonly", file);
+			fd = open(file, O_RDONLY);
+			if (fd < 0) {
+				condlog(0, "Cannot open file [%s] "
+					"readonly : %s", file, strerror(errno));
+				return -1;
+			}
+		}
+		else {
+			condlog(0, "Cannot open file [%s] : %s", file,
+				strerror(errno));
+			return -1;
+		}
+	}
+	if (*can_write && lock_file(fd, file) < 0)
+		goto fail;
+
+	memset(&s, 0, sizeof(s));
+	if (fstat(fd, &s) < 0){
+		condlog(0, "Cannot stat file %s : %s", file, strerror(errno));
+		goto fail;
+	}
+	if (s.st_size == 0) {
+		if (*can_write == 0)
+			goto fail;
+		/* If file is empty, write the header */
+		size_t len = strlen(header);
+		if (write_all(fd, header, len) != len) {
+			condlog(0,
+				"Cannot write header to file %s : %s", file,
+				strerror(errno));
+			/* cleanup partially written header */
+			ftruncate(fd, 0);
+			goto fail;
+		}
+		fsync(fd);
+		condlog(3, "Initialized new file [%s]", file);
+	}
+
+	return fd;
+
+fail:
+	close(fd);
+	return -1;
+}
Index: multipath-tools-110713/libmultipath/file.h
===================================================================
--- /dev/null
+++ multipath-tools-110713/libmultipath/file.h
@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2010 Benjamin Marzinski, Redhat
+ */
+
+#ifndef _FILE_H
+#define _FILE_H
+
+#define FILE_TIMEOUT 30
+int open_file(char *file, int *can_write, char *header);
+
+#endif /* _FILE_H */
Index: multipath-tools-110713/libmultipath/finder.c
===================================================================
--- /dev/null
+++ multipath-tools-110713/libmultipath/finder.c
@@ -0,0 +1,165 @@
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <limits.h>
+#include <stdio.h>
+
+#include "checkers.h"
+#include "vector.h"
+#include "structs.h"
+#include "debug.h"
+#include "uxsock.h"
+#include "file.h"
+#include "finder.h"
+#include "defaults.h"
+
+/*
+ * Copyright (c) 2010 Benjamin Marzinski, Redhat
+ */
+
+static int
+lookup_wwid(FILE *f, char *wwid) {
+	int c;
+	char buf[LINE_MAX];
+	int count;
+
+	while ((c = fgetc(f)) != EOF){
+		if (c != '/') {
+			if (fgets(buf, LINE_MAX, f) == NULL)
+				return 0;
+			else
+				continue;
+		}
+		count = 0;
+		while ((c = fgetc(f)) != '/') {
+			if (c == EOF)
+				return 0;
+			if (count >= WWID_SIZE - 1)
+				goto next;
+			if (wwid[count] == '\0')
+				goto next;
+			if (c != wwid[count++])
+				goto next;
+		}
+		if (wwid[count] == '\0')
+			return 1;
+next:
+		if (fgets(buf, LINE_MAX, f) == NULL)
+			return 0;
+	}
+	return 0;
+}
+
+static int
+write_out_wwid(int fd, char *wwid) {
+	int ret;
+	off_t offset;
+	char buf[WWID_SIZE + 3];
+
+	ret = snprintf(buf, WWID_SIZE + 3, "/%s/\n", wwid);
+	if (ret >= (WWID_SIZE + 3) || ret < 0){
+		condlog(0, "can't format wwid for writing (%d) : %s",
+			ret, strerror(errno));
+		return -1;
+	}
+	offset = lseek(fd, 0, SEEK_END);
+	if (offset < 0) {
+		condlog(0, "can't seek to the end of wwids file : %s",
+			strerror(errno));
+		return -1;
+	}
+	if (write_all(fd, buf, strlen(buf)) != strlen(buf)) {
+		condlog(0, "cannot write wwid to wwids file : %s",
+			strerror(errno));
+		ftruncate(fd, offset);
+		return -1;
+	}
+	return 1;
+}
+
+static int
+check_wwids_file(char *wwid, int write_wwid)
+{
+	int scan_fd, fd, can_write, found, ret;
+	FILE *f;
+	fd = open_file(DEFAULT_WWIDS_FILE, &can_write, WWIDS_FILE_HEADER);
+	if (fd < 0)
+		return -1;
+
+	scan_fd = dup(fd);
+	if (scan_fd < 0) {
+		condlog(0, "can't dup wwids file descriptor : %s",
+			strerror(errno));
+		close(fd);
+		return -1;
+	}
+	f = fdopen(scan_fd, "r");
+	if (!f) {
+		condlog(0,"can't fdopen wwids file : %s", strerror(errno));
+		close(fd);
+		close(scan_fd);
+		return -1;
+	}
+	found = lookup_wwid(f, wwid);
+	if (found) {
+		ret = 0;
+		goto out;
+	}
+	if (!write_wwid) {
+		ret = -1;
+		goto out;
+	}
+	if (!can_write) {
+		condlog(0, "wwids file is read-only. Can't write wwid");
+		ret = -1;
+		goto out;
+	}
+	ret = write_out_wwid(fd, wwid);
+out:
+	fclose(f);
+	close(scan_fd);
+	close(fd);
+	return ret;
+}
+
+int
+should_multipath(struct path *pp1, vector pathvec)
+{
+	int i;
+	struct path *pp2;
+
+	condlog(4, "checking if %s should be multipathed", pp1->dev);
+	vector_foreach_slot(pathvec, pp2, i) {
+		if (pp1->dev == pp2->dev)
+			continue;
+		if (strncmp(pp1->wwid, pp2->wwid, WWID_SIZE) == 0) {
+			condlog(3, "found multiple paths with wwid %s, "
+				"multipathing %s", pp1->wwid, pp1->dev);
+			return 1;
+		}
+	}
+	if (check_wwids_file(pp1->wwid, 0) < 0) {
+		condlog(3, "wwid %s not in wwids file, skipping %s",
+			pp1->wwid, pp1->dev);
+		return 0;
+	}
+	condlog(3, "found wwid %s in wwids file, multipathing %s", pp1->wwid,
+		pp1->dev);
+	return 1;
+}
+
+int
+remember_wwid(char *wwid)
+{
+	int ret = check_wwids_file(wwid, 1);
+	if (ret < 0){
+		condlog(3, "failed writing wwid %s to wwids file", wwid);
+		return -1;
+	}
+	if (ret == 1)
+		condlog(3, "wrote wwid %s to wwids file", wwid);
+	else
+		condlog(4, "wwid %s already in wwids file", wwid);
+	return 0;
+}
Index: multipath-tools-110713/libmultipath/finder.h
===================================================================
--- /dev/null
+++ multipath-tools-110713/libmultipath/finder.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2010 Benjamin Marzinski, Redhat
+ */
+
+#ifndef _FINDER_H
+#define _FINDER_H
+
+#define WWIDS_FILE_HEADER \
+"# Multipath wwids, Version : 1.0\n" \
+"# NOTE: This file is automatically maintained by multipath and multipathd.\n" \
+"# You should not need to edit this file in normal circumstances.\n" \
+"#\n" \
+"# Valid WWIDs:\n"
+
+int should_multipath(struct path *pp, vector pathvec);
+int remember_wwid(char *wwid);
+
+#endif /* _FINDER_H */
Index: multipath-tools-110713/multipath/main.c
===================================================================
--- multipath-tools-110713.orig/multipath/main.c
+++ multipath-tools-110713/multipath/main.c
@@ -313,7 +313,7 @@ configure (void)
 	/*
 	 * core logic entry point
 	 */
-	r = coalesce_paths(&vecs, NULL, NULL, conf->force_reload);
+	r = coalesce_paths(&vecs, NULL, refwwid, conf->force_reload);
 
 out:
 	if (refwwid)
Index: multipath-tools-110713/multipathd/main.c
===================================================================
--- multipath-tools-110713.orig/multipathd/main.c
+++ multipath-tools-110713/multipathd/main.c
@@ -47,6 +47,7 @@
 #include <print.h>
 #include <configure.h>
 #include <prio.h>
+#include <finder.h>
 #include <pgpolicies.h>
 #include <uevent.h>
 
@@ -447,6 +448,11 @@ rescan:
 			return 1;
 		}
 
+		if (conf->find_multipaths &&
+		    !should_multipath(pp, vecs->pathvec)) {
+			orphan_path(pp);
+			return 0;
+		}
 		condlog(4,"%s: creating new map", pp->dev);
 		if ((mpp = add_map_with_path(vecs, pp, 1))) {
 			mpp->action = ACT_CREATE;
Index: multipath-tools-110713/libmultipath/Makefile
===================================================================
--- multipath-tools-110713.orig/libmultipath/Makefile
+++ multipath-tools-110713/libmultipath/Makefile
@@ -15,7 +15,7 @@ OBJS = memory.o parser.o vector.o devmap
        pgpolicies.o debug.o regex.o defaults.o uevent.o \
        switchgroup.o uxsock.o print.o alias.o log_pthread.o \
        log.o configure.o structs_vec.o sysfs.o prio.o checkers.o \
-       lock.o waiter.o
+       lock.o waiter.o file.o finder.o
 
 LIBDM_API_FLUSH = $(shell grep -Ecs '^[a-z]*[[:space:]]+dm_task_no_flush' /usr/include/libdevmapper.h)
 

Re: [PATCH v2] multipath: add find_multipaths feature.

[Benjamin Marzinski]

This adds a new default feature, find_multipaths. When this is set to yes,
multipath will no longer try to create a multipath device for every
non-blacklisted device. Instead, it will only create a device when one of
three conditions are met.

1. Three are at least two non-blacklisted paths with the same wwid
2. The user manually forces the creation, by specifying a device with the
   multipath command.
3. A path has the same wwid as a multipath device that was previously crreated
   (even if that multipath device doesn't currently exist).

To do 3, multipath stores the wwid of every path that it creates in
/etc/multipath/wwids. Whenever a path is added it's wwid is checked against
this file.  If there's a match, it is multipathed, even if it's the only path.
This should allow multipath to automatically choose the correct paths to make
into multipath devics in most cases, without needing the user to edit the
blacklist.

This is identical to my first post, except that it includes a previously
missing call to remember_wwid. 

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 libmultipath/Makefile    |    2 
 libmultipath/alias.c     |  151 ---------------------------------------
 libmultipath/alias.h     |    1 
 libmultipath/config.c    |    1 
 libmultipath/config.h    |    1 
 libmultipath/configure.c |   14 +++
 libmultipath/defaults.h  |    2 
 libmultipath/dict.c      |   34 ++++++++
 libmultipath/file.c      |  178 +++++++++++++++++++++++++++++++++++++++++++++++
 libmultipath/file.h      |   11 ++
 libmultipath/finder.c    |  165 +++++++++++++++++++++++++++++++++++++++++++
 libmultipath/finder.h    |   18 ++++
 multipath/main.c         |    2 
 multipathd/main.c        |    6 +
 14 files changed, 435 insertions(+), 151 deletions(-)

Index: multipath-tools-110713/libmultipath/alias.c
===================================================================
--- multipath-tools-110713.orig/libmultipath/alias.c
+++ multipath-tools-110713/libmultipath/alias.c
@@ -3,19 +3,16 @@
  * Copyright (c) 2005 Benjamin Marzinski, Redhat
  */
 #include <stdlib.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
 #include <errno.h>
 #include <unistd.h>
 #include <string.h>
 #include <limits.h>
 #include <stdio.h>
-#include <signal.h>
 
 #include "debug.h"
 #include "uxsock.h"
 #include "alias.h"
+#include "file.h"
 
 
 /*
@@ -36,148 +33,6 @@
  * See the file COPYING included with this distribution for more details.
  */
 
-static int
-ensure_directories_exist(char *str, mode_t dir_mode)
-{
-	char *pathname;
-	char *end;
-	int err;
-
-	pathname = strdup(str);
-	if (!pathname){
-		condlog(0, "Cannot copy bindings file pathname : %s",
-			strerror(errno));
-		return -1;
-	}
-	end = pathname;
-	/* skip leading slashes */
-	while (end && *end && (*end == '/'))
-		end++;
-
-	while ((end = strchr(end, '/'))) {
-		/* if there is another slash, make the dir. */
-		*end = '\0';
-		err = mkdir(pathname, dir_mode);
-		if (err && errno != EEXIST) {
-			condlog(0, "Cannot make directory [%s] : %s",
-				pathname, strerror(errno));
-			free(pathname);
-			return -1;
-		}
-		if (!err)
-			condlog(3, "Created dir [%s]", pathname);
-		*end = '/';
-		end++;
-	}
-	free(pathname);
-	return 0;
-}
-
-static void
-sigalrm(int sig)
-{
-	/* do nothing */
-}
-
-static int
-lock_bindings_file(int fd)
-{
-	struct sigaction act, oldact;
-	sigset_t set, oldset;
-	struct flock lock;
-	int err;
-
-	memset(&lock, 0, sizeof(lock));
-	lock.l_type = F_WRLCK;
-	lock.l_whence = SEEK_SET;
-
-	act.sa_handler = sigalrm;
-	sigemptyset(&act.sa_mask);
-	act.sa_flags = 0;
-	sigemptyset(&set);
-	sigaddset(&set, SIGALRM);
-
-	sigaction(SIGALRM, &act, &oldact);
-	sigprocmask(SIG_UNBLOCK, &set, &oldset);
-
-	alarm(BINDINGS_FILE_TIMEOUT);
-	err = fcntl(fd, F_SETLKW, &lock);
-	alarm(0);
-
-	if (err) {
-		if (errno != EINTR)
-			condlog(0, "Cannot lock bindings file : %s",
-					strerror(errno));
-		else
-			condlog(0, "Bindings file is locked. Giving up.");
-	}
-
-	sigprocmask(SIG_SETMASK, &oldset, NULL);
-	sigaction(SIGALRM, &oldact, NULL);
-	return err;
-
-}
-
-
-static int
-open_bindings_file(char *file, int *can_write)
-{
-	int fd;
-	struct stat s;
-
-	if (ensure_directories_exist(file, 0700))
-		return -1;
-	*can_write = 1;
-	fd = open(file, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
-	if (fd < 0) {
-		if (errno == EROFS) {
-			*can_write = 0;
-			condlog(3, "Cannot open bindings file [%s] read/write. "
-				" trying readonly", file);
-			fd = open(file, O_RDONLY);
-			if (fd < 0) {
-				condlog(0, "Cannot open bindings file [%s] "
-					"readonly : %s", file, strerror(errno));
-				return -1;
-			}
-		}
-		else {
-			condlog(0, "Cannot open bindings file [%s] : %s", file,
-				strerror(errno));
-			return -1;
-		}
-	}
-	if (*can_write && lock_bindings_file(fd) < 0)
-		goto fail;
-
-	memset(&s, 0, sizeof(s));
-	if (fstat(fd, &s) < 0){
-		condlog(0, "Cannot stat bindings file : %s", strerror(errno));
-		goto fail;
-	}
-	if (s.st_size == 0) {
-		if (*can_write == 0)
-			goto fail;
-		/* If bindings file is empty, write the header */
-		size_t len = strlen(BINDINGS_FILE_HEADER);
-		if (write_all(fd, BINDINGS_FILE_HEADER, len) != len) {
-			condlog(0,
-				"Cannot write header to bindings file : %s",
-				strerror(errno));
-			/* cleanup partially written header */
-			ftruncate(fd, 0);
-			goto fail;
-		}
-		fsync(fd);
-		condlog(3, "Initialized new bindings file [%s]", file);
-	}
-
-	return fd;
-
-fail:
-	close(fd);
-	return -1;
-}
 
 static int
 format_devname(char *name, int id, int len, char *prefix)
@@ -366,7 +221,7 @@ get_user_friendly_alias(char *wwid, char
 		return NULL;
 	}
 
-	fd = open_bindings_file(file, &can_write);
+	fd = open_file(file, &can_write, BINDINGS_FILE_HEADER);
 	if (fd < 0)
 		return NULL;
 
@@ -416,7 +271,7 @@ get_user_friendly_wwid(char *alias, char
 		return NULL;
 	}
 
-	fd = open_bindings_file(file, &unused);
+	fd = open_file(file, &unused, BINDINGS_FILE_HEADER);
 	if (fd < 0)
 		return NULL;
 
Index: multipath-tools-110713/libmultipath/alias.h
===================================================================
--- multipath-tools-110713.orig/libmultipath/alias.h
+++ multipath-tools-110713/libmultipath/alias.h
@@ -1,4 +1,3 @@
-#define BINDINGS_FILE_TIMEOUT 30
 #define BINDINGS_FILE_HEADER \
 "# Multipath bindings, Version : 1.0\n" \
 "# NOTE: this file is automatically maintained by the multipath program.\n" \
Index: multipath-tools-110713/libmultipath/config.c
===================================================================
--- multipath-tools-110713.orig/libmultipath/config.c
+++ multipath-tools-110713/libmultipath/config.c
@@ -497,6 +497,7 @@ load_config (char * file)
 	conf->flush_on_last_del = 0;
 	conf->attribute_flags = 0;
 	conf->reassign_maps = DEFAULT_REASSIGN_MAPS;
+	conf->find_multipaths = DEFAULT_FIND_MULTIPATHS;
 
 	/*
 	 * preload default hwtable
Index: multipath-tools-110713/libmultipath/config.h
===================================================================
--- multipath-tools-110713.orig/libmultipath/config.h
+++ multipath-tools-110713/libmultipath/config.h
@@ -92,6 +92,7 @@ struct config {
 	int attribute_flags;
 	int fast_io_fail;
 	unsigned int dev_loss;
+	int find_multipaths;
 	uid_t uid;
 	gid_t gid;
 	mode_t mode;
Index: multipath-tools-110713/libmultipath/configure.c
===================================================================
--- multipath-tools-110713.orig/libmultipath/configure.c
+++ multipath-tools-110713/libmultipath/configure.c
@@ -35,6 +35,7 @@
 #include "alias.h"
 #include "prio.h"
 #include "util.h"
+#include "finder.h"
 
 extern int
 setup_map (struct multipath * mpp, char * params, int params_size)
@@ -404,6 +405,8 @@ domap (struct multipath * mpp, char * pa
 		 * DM_DEVICE_CREATE, DM_DEVICE_RENAME, or DM_DEVICE_RELOAD
 		 * succeeded
 		 */
+		if (mpp->action == ACT_CREATE)
+			remember_wwid(mpp->wwid);
 		if (!conf->daemon) {
 			/* multipath client mode */
 			dm_switchgroup(mpp->alias, mpp->bestpg);
@@ -463,6 +466,10 @@ coalesce_paths (struct vectors * vecs, v
 
 	memset(empty_buff, 0, WWID_SIZE);
 
+	/* ignore refwwid if it's empty */
+	if (refwwid && !strlen(refwwid))
+		refwwid = NULL;
+
 	if (force_reload) {
 		vector_foreach_slot (pathvec, pp1, k) {
 			pp1->mpp = NULL;
@@ -492,6 +499,13 @@ coalesce_paths (struct vectors * vecs, v
 		if (refwwid && strncmp(pp1->wwid, refwwid, WWID_SIZE))
 			continue;
 
+		/* If find_multipaths was selected check if the path is valid */
+		if (conf->find_multipaths && !refwwid &&
+		    !should_multipath(pp1, pathvec)) {
+			orphan_path(pp1);
+			continue;
+		}
+
 		/*
 		 * at this point, we know we really got a new mp
 		 */
Index: multipath-tools-110713/libmultipath/defaults.h
===================================================================
--- multipath-tools-110713.orig/libmultipath/defaults.h
+++ multipath-tools-110713/libmultipath/defaults.h
@@ -15,6 +15,7 @@
 #define DEFAULT_USER_FRIENDLY_NAMES    0
 #define DEFAULT_VERBOSITY	2
 #define DEFAULT_REASSIGN_MAPS	1
+#define DEFAULT_FIND_MULTIPATHS 0
 
 #define DEFAULT_CHECKINT	5
 #define MAX_CHECKINT(a)		(a << 2)
@@ -24,5 +25,6 @@
 #define DEFAULT_SOCKET		"/var/run/multipathd.sock"
 #define DEFAULT_CONFIGFILE	"/etc/multipath.conf"
 #define DEFAULT_BINDINGS_FILE	"/etc/multipath/bindings"
+#define DEFAULT_WWIDS_FILE	"/etc/multipath/wwids"
 
 char * set_default (char * str);
Index: multipath-tools-110713/libmultipath/dict.c
===================================================================
--- multipath-tools-110713.orig/libmultipath/dict.c
+++ multipath-tools-110713/libmultipath/dict.c
@@ -525,6 +525,27 @@ def_flush_on_last_del_handler(vector str
 }
 
 static int
+def_find_multipaths_handler(vector strvec)
+{
+	char * buff;
+
+	buff = set_value(strvec);
+
+	if (!buff)
+		return 1;
+
+	if ((strlen(buff) == 2 && !strcmp(buff, "no")) ||
+	    (strlen(buff) == 1 && !strcmp(buff, "0")))
+		conf->find_multipaths = 0;
+	else if ((strlen(buff) == 3 && !strcmp(buff, "yes")) ||
+		 (strlen(buff) == 1 && !strcmp(buff, "1")))
+		conf->find_multipaths = 1;
+
+	FREE(buff);
+	return 0;
+}
+
+static int
 names_handler(vector strvec)
 {
 	char * buff;
@@ -2338,6 +2359,18 @@ snprint_def_flush_on_last_del (char * bu
 }
 
 static int
+snprint_def_find_multipaths (char * buff, int len, void * data)
+{
+	if (conf->find_multipaths == DEFAULT_FIND_MULTIPATHS)
+		return 0;
+	if (!conf->find_multipaths)
+		return snprintf(buff, len, "no");
+
+	return snprintf(buff, len, "yes");
+}
+
+
+static int
 snprint_def_user_friendly_names (char * buff, int len, void * data)
 {
 	if (!conf->user_friendly_names)
@@ -2428,6 +2461,7 @@ init_keywords(void)
 	install_keyword("fast_io_fail_tmo", &def_fast_io_fail_handler, &snprint_def_fast_io_fail);
 	install_keyword("dev_loss_tmo", &def_dev_loss_handler, &snprint_def_dev_loss);
 	install_keyword("bindings_file", &bindings_file_handler, &snprint_def_bindings_file);
+	install_keyword("find_multipaths", &def_find_multipaths_handler, &snprint_def_find_multipaths);
 	__deprecated install_keyword("default_selector", &def_selector_handler, NULL);
 	__deprecated install_keyword("default_path_grouping_policy", &def_pgpolicy_handler, NULL);
 	__deprecated install_keyword("default_getuid_callout", &def_getuid_callout_handler, NULL);
Index: multipath-tools-110713/libmultipath/file.c
===================================================================
--- /dev/null
+++ multipath-tools-110713/libmultipath/file.c
@@ -0,0 +1,178 @@
+/*
+ * Copyright (c) 2005 Christophe Varoqui
+ * Copyright (c) 2005 Benjamin Marzinski, Redhat
+ */
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <limits.h>
+#include <stdio.h>
+#include <signal.h>
+
+#include "file.h"
+#include "debug.h"
+#include "uxsock.h"
+
+
+/*
+ * significant parts of this file were taken from iscsi-bindings.c of the
+ * linux-iscsi project.
+ * Copyright (C) 2002 Cisco Systems, Inc.
+ *
+ * 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.
+ */
+
+static int
+ensure_directories_exist(char *str, mode_t dir_mode)
+{
+	char *pathname;
+	char *end;
+	int err;
+
+	pathname = strdup(str);
+	if (!pathname){
+		condlog(0, "Cannot copy file pathname %s : %s",
+			str, strerror(errno));
+		return -1;
+	}
+	end = pathname;
+	/* skip leading slashes */
+	while (end && *end && (*end == '/'))
+		end++;
+
+	while ((end = strchr(end, '/'))) {
+		/* if there is another slash, make the dir. */
+		*end = '\0';
+		err = mkdir(pathname, dir_mode);
+		if (err && errno != EEXIST) {
+			condlog(0, "Cannot make directory [%s] : %s",
+				pathname, strerror(errno));
+			free(pathname);
+			return -1;
+		}
+		if (!err)
+			condlog(3, "Created dir [%s]", pathname);
+		*end = '/';
+		end++;
+	}
+	free(pathname);
+	return 0;
+}
+
+static void
+sigalrm(int sig)
+{
+	/* do nothing */
+}
+
+static int
+lock_file(int fd, char *file_name)
+{
+	struct sigaction act, oldact;
+	sigset_t set, oldset;
+	struct flock lock;
+	int err;
+
+	memset(&lock, 0, sizeof(lock));
+	lock.l_type = F_WRLCK;
+	lock.l_whence = SEEK_SET;
+
+	act.sa_handler = sigalrm;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	sigemptyset(&set);
+	sigaddset(&set, SIGALRM);
+
+	sigaction(SIGALRM, &act, &oldact);
+	sigprocmask(SIG_UNBLOCK, &set, &oldset);
+
+	alarm(FILE_TIMEOUT);
+	err = fcntl(fd, F_SETLKW, &lock);
+	alarm(0);
+
+	if (err) {
+		if (errno != EINTR)
+			condlog(0, "Cannot lock %s : %s", file_name,
+				strerror(errno));
+		else
+			condlog(0, "%s is locked. Giving up.", file_name);
+	}
+
+	sigprocmask(SIG_SETMASK, &oldset, NULL);
+	sigaction(SIGALRM, &oldact, NULL);
+	return err;
+}
+
+int
+open_file(char *file, int *can_write, char *header)
+{
+	int fd;
+	struct stat s;
+
+	if (ensure_directories_exist(file, 0700))
+		return -1;
+	*can_write = 1;
+	fd = open(file, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
+	if (fd < 0) {
+		if (errno == EROFS) {
+			*can_write = 0;
+			condlog(3, "Cannot open file [%s] read/write. "
+				" trying readonly", file);
+			fd = open(file, O_RDONLY);
+			if (fd < 0) {
+				condlog(0, "Cannot open file [%s] "
+					"readonly : %s", file, strerror(errno));
+				return -1;
+			}
+		}
+		else {
+			condlog(0, "Cannot open file [%s] : %s", file,
+				strerror(errno));
+			return -1;
+		}
+	}
+	if (*can_write && lock_file(fd, file) < 0)
+		goto fail;
+
+	memset(&s, 0, sizeof(s));
+	if (fstat(fd, &s) < 0){
+		condlog(0, "Cannot stat file %s : %s", file, strerror(errno));
+		goto fail;
+	}
+	if (s.st_size == 0) {
+		if (*can_write == 0)
+			goto fail;
+		/* If file is empty, write the header */
+		size_t len = strlen(header);
+		if (write_all(fd, header, len) != len) {
+			condlog(0,
+				"Cannot write header to file %s : %s", file,
+				strerror(errno));
+			/* cleanup partially written header */
+			ftruncate(fd, 0);
+			goto fail;
+		}
+		fsync(fd);
+		condlog(3, "Initialized new file [%s]", file);
+	}
+
+	return fd;
+
+fail:
+	close(fd);
+	return -1;
+}
Index: multipath-tools-110713/libmultipath/file.h
===================================================================
--- /dev/null
+++ multipath-tools-110713/libmultipath/file.h
@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2010 Benjamin Marzinski, Redhat
+ */
+
+#ifndef _FILE_H
+#define _FILE_H
+
+#define FILE_TIMEOUT 30
+int open_file(char *file, int *can_write, char *header);
+
+#endif /* _FILE_H */
Index: multipath-tools-110713/libmultipath/finder.c
===================================================================
--- /dev/null
+++ multipath-tools-110713/libmultipath/finder.c
@@ -0,0 +1,165 @@
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <limits.h>
+#include <stdio.h>
+
+#include "checkers.h"
+#include "vector.h"
+#include "structs.h"
+#include "debug.h"
+#include "uxsock.h"
+#include "file.h"
+#include "finder.h"
+#include "defaults.h"
+
+/*
+ * Copyright (c) 2010 Benjamin Marzinski, Redhat
+ */
+
+static int
+lookup_wwid(FILE *f, char *wwid) {
+	int c;
+	char buf[LINE_MAX];
+	int count;
+
+	while ((c = fgetc(f)) != EOF){
+		if (c != '/') {
+			if (fgets(buf, LINE_MAX, f) == NULL)
+				return 0;
+			else
+				continue;
+		}
+		count = 0;
+		while ((c = fgetc(f)) != '/') {
+			if (c == EOF)
+				return 0;
+			if (count >= WWID_SIZE - 1)
+				goto next;
+			if (wwid[count] == '\0')
+				goto next;
+			if (c != wwid[count++])
+				goto next;
+		}
+		if (wwid[count] == '\0')
+			return 1;
+next:
+		if (fgets(buf, LINE_MAX, f) == NULL)
+			return 0;
+	}
+	return 0;
+}
+
+static int
+write_out_wwid(int fd, char *wwid) {
+	int ret;
+	off_t offset;
+	char buf[WWID_SIZE + 3];
+
+	ret = snprintf(buf, WWID_SIZE + 3, "/%s/\n", wwid);
+	if (ret >= (WWID_SIZE + 3) || ret < 0){
+		condlog(0, "can't format wwid for writing (%d) : %s",
+			ret, strerror(errno));
+		return -1;
+	}
+	offset = lseek(fd, 0, SEEK_END);
+	if (offset < 0) {
+		condlog(0, "can't seek to the end of wwids file : %s",
+			strerror(errno));
+		return -1;
+	}
+	if (write_all(fd, buf, strlen(buf)) != strlen(buf)) {
+		condlog(0, "cannot write wwid to wwids file : %s",
+			strerror(errno));
+		ftruncate(fd, offset);
+		return -1;
+	}
+	return 1;
+}
+
+static int
+check_wwids_file(char *wwid, int write_wwid)
+{
+	int scan_fd, fd, can_write, found, ret;
+	FILE *f;
+	fd = open_file(DEFAULT_WWIDS_FILE, &can_write, WWIDS_FILE_HEADER);
+	if (fd < 0)
+		return -1;
+
+	scan_fd = dup(fd);
+	if (scan_fd < 0) {
+		condlog(0, "can't dup wwids file descriptor : %s",
+			strerror(errno));
+		close(fd);
+		return -1;
+	}
+	f = fdopen(scan_fd, "r");
+	if (!f) {
+		condlog(0,"can't fdopen wwids file : %s", strerror(errno));
+		close(fd);
+		close(scan_fd);
+		return -1;
+	}
+	found = lookup_wwid(f, wwid);
+	if (found) {
+		ret = 0;
+		goto out;
+	}
+	if (!write_wwid) {
+		ret = -1;
+		goto out;
+	}
+	if (!can_write) {
+		condlog(0, "wwids file is read-only. Can't write wwid");
+		ret = -1;
+		goto out;
+	}
+	ret = write_out_wwid(fd, wwid);
+out:
+	fclose(f);
+	close(scan_fd);
+	close(fd);
+	return ret;
+}
+
+int
+should_multipath(struct path *pp1, vector pathvec)
+{
+	int i;
+	struct path *pp2;
+
+	condlog(4, "checking if %s should be multipathed", pp1->dev);
+	vector_foreach_slot(pathvec, pp2, i) {
+		if (pp1->dev == pp2->dev)
+			continue;
+		if (strncmp(pp1->wwid, pp2->wwid, WWID_SIZE) == 0) {
+			condlog(3, "found multiple paths with wwid %s, "
+				"multipathing %s", pp1->wwid, pp1->dev);
+			return 1;
+		}
+	}
+	if (check_wwids_file(pp1->wwid, 0) < 0) {
+		condlog(3, "wwid %s not in wwids file, skipping %s",
+			pp1->wwid, pp1->dev);
+		return 0;
+	}
+	condlog(3, "found wwid %s in wwids file, multipathing %s", pp1->wwid,
+		pp1->dev);
+	return 1;
+}
+
+int
+remember_wwid(char *wwid)
+{
+	int ret = check_wwids_file(wwid, 1);
+	if (ret < 0){
+		condlog(3, "failed writing wwid %s to wwids file", wwid);
+		return -1;
+	}
+	if (ret == 1)
+		condlog(3, "wrote wwid %s to wwids file", wwid);
+	else
+		condlog(4, "wwid %s already in wwids file", wwid);
+	return 0;
+}
Index: multipath-tools-110713/libmultipath/finder.h
===================================================================
--- /dev/null
+++ multipath-tools-110713/libmultipath/finder.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2010 Benjamin Marzinski, Redhat
+ */
+
+#ifndef _FINDER_H
+#define _FINDER_H
+
+#define WWIDS_FILE_HEADER \
+"# Multipath wwids, Version : 1.0\n" \
+"# NOTE: This file is automatically maintained by multipath and multipathd.\n" \
+"# You should not need to edit this file in normal circumstances.\n" \
+"#\n" \
+"# Valid WWIDs:\n"
+
+int should_multipath(struct path *pp, vector pathvec);
+int remember_wwid(char *wwid);
+
+#endif /* _FINDER_H */
Index: multipath-tools-110713/multipath/main.c
===================================================================
--- multipath-tools-110713.orig/multipath/main.c
+++ multipath-tools-110713/multipath/main.c
@@ -313,7 +313,7 @@ configure (void)
 	/*
 	 * core logic entry point
 	 */
-	r = coalesce_paths(&vecs, NULL, NULL, conf->force_reload);
+	r = coalesce_paths(&vecs, NULL, refwwid, conf->force_reload);
 
 out:
 	if (refwwid)
Index: multipath-tools-110713/multipathd/main.c
===================================================================
--- multipath-tools-110713.orig/multipathd/main.c
+++ multipath-tools-110713/multipathd/main.c
@@ -47,6 +47,7 @@
 #include <print.h>
 #include <configure.h>
 #include <prio.h>
+#include <finder.h>
 #include <pgpolicies.h>
 #include <uevent.h>
 
@@ -447,6 +448,11 @@ rescan:
 			return 1;
 		}
 
+		if (conf->find_multipaths &&
+		    !should_multipath(pp, vecs->pathvec)) {
+			orphan_path(pp);
+			return 0;
+		}
 		condlog(4,"%s: creating new map", pp->dev);
 		if ((mpp = add_map_with_path(vecs, pp, 1))) {
 			mpp->action = ACT_CREATE;
Index: multipath-tools-110713/libmultipath/Makefile
===================================================================
--- multipath-tools-110713.orig/libmultipath/Makefile
+++ multipath-tools-110713/libmultipath/Makefile
@@ -15,7 +15,7 @@ OBJS = memory.o parser.o vector.o devmap
        pgpolicies.o debug.o regex.o defaults.o uevent.o \
        switchgroup.o uxsock.o print.o alias.o log_pthread.o \
        log.o configure.o structs_vec.o sysfs.o prio.o checkers.o \
-       lock.o waiter.o
+       lock.o waiter.o file.o finder.o
 
 LIBDM_API_FLUSH = $(shell grep -Ecs '^[a-z]*[[:space:]]+dm_task_no_flush' /usr/include/libdevmapper.h)
 

Re: [PATCH v2] multipath: add find_multipaths feature.

[Christophe Varoqui]

On mer., 2011-08-31 at 21:55 -0500, Benjamin Marzinski wrote:
> This adds a new default feature, find_multipaths. When this is set to yes,
> multipath will no longer try to create a multipath device for every
> non-blacklisted device. Instead, it will only create a device when one of
> three conditions are met.
> 
> 1. Three are at least two non-blacklisted paths with the same wwid
> 2. The user manually forces the creation, by specifying a device with the
>    multipath command.
> 3. A path has the same wwid as a multipath device that was previously crreated
>    (even if that multipath device doesn't currently exist).
> 
Hannes,

this patch implements complex semantics and mis-use /etc to store
variable data (/run was suggested as a replacement). Though I realize
the benefits, I'm not at ease merging it.

Mike Snitzer pushed for its inclusion, but I don't remember your
commenting. Would your care to ?

Regards,

-- 
Christophe Varoqui
OpenSVC - Tools to scale
http://www.opensvc.com/

Re: [PATCH v2] multipath: add find_multipaths feature.

[Benjamin Marzinski]

On Thu, Sep 01, 2011 at 09:14:23AM +0200, Christophe Varoqui wrote:
> On mer., 2011-08-31 at 21:55 -0500, Benjamin Marzinski wrote:
> > This adds a new default feature, find_multipaths. When this is set to yes,
> > multipath will no longer try to create a multipath device for every
> > non-blacklisted device. Instead, it will only create a device when one of
> > three conditions are met.
> > 
> > 1. Three are at least two non-blacklisted paths with the same wwid
> > 2. The user manually forces the creation, by specifying a device with the
> >    multipath command.
> > 3. A path has the same wwid as a multipath device that was previously crreated
> >    (even if that multipath device doesn't currently exist).
> > 
> Hannes,
> 
> this patch implements complex semantics and mis-use /etc to store
> variable data (/run was suggested as a replacement). Though I realize
> the benefits, I'm not at ease merging it.

This will add wwids to the wwids file at the same times that new bindings
get added to the bindings file. We decided to move the bindings file to
/etc/multipath/bindings because it caused problems during bootup, if
/var/run was not mounted.  This will have the same problems where you
will be writing to a file that eventually gets mounted over.  So I am
against using /var/run

-Ben

> 
> Mike Snitzer pushed for its inclusion, but I don't remember your
> commenting. Would your care to ?
> 
> Regards,
> 
> -- 
> Christophe Varoqui
> OpenSVC - Tools to scale
> http://www.opensvc.com/
> 
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel

Re: [PATCH v2] multipath: add find_multipaths feature.

[Benjamin Marzinski]

On Thu, Sep 01, 2011 at 07:57:20AM -0500, Benjamin Marzinski wrote:
> On Thu, Sep 01, 2011 at 09:14:23AM +0200, Christophe Varoqui wrote:
> > On mer., 2011-08-31 at 21:55 -0500, Benjamin Marzinski wrote:
> > > This adds a new default feature, find_multipaths. When this is set to yes,
> > > multipath will no longer try to create a multipath device for every
> > > non-blacklisted device. Instead, it will only create a device when one of
> > > three conditions are met.
> > > 
> > > 1. Three are at least two non-blacklisted paths with the same wwid
> > > 2. The user manually forces the creation, by specifying a device with the
> > >    multipath command.
> > > 3. A path has the same wwid as a multipath device that was previously crreated
> > >    (even if that multipath device doesn't currently exist).
> > > 
> > Hannes,
> > 
> > this patch implements complex semantics and mis-use /etc to store
> > variable data (/run was suggested as a replacement). Though I realize
> > the benefits, I'm not at ease merging it.
> 
> This will add wwids to the wwids file at the same times that new bindings
> get added to the bindings file. We decided to move the bindings file to
> /etc/multipath/bindings because it caused problems during bootup, if
> /var/run was not mounted.  This will have the same problems where you
> will be writing to a file that eventually gets mounted over.  So I am
> against using /var/run

although it looks like the systemd folks have made /run a tmpfs
filesystem, and /var/run a pointer to it (at least in Fedora), so I
guess I'm not opposed to moving things back to /var/run anymore.

-Ben

> 
> -Ben
> 
> > 
> > Mike Snitzer pushed for its inclusion, but I don't remember your
> > commenting. Would your care to ?
> > 
> > Regards,
> > 
> > -- 
> > Christophe Varoqui
> > OpenSVC - Tools to scale
> > http://www.opensvc.com/
> > 
> > --
> > dm-devel mailing list
> > dm-devel@redhat.com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> 
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel

Re: [PATCH v2] multipath: add find_multipaths feature.

[Hannes Reinecke]

On 09/01/2011 02:57 PM, Benjamin Marzinski wrote:
> On Thu, Sep 01, 2011 at 09:14:23AM +0200, Christophe Varoqui wrote:
>> On mer., 2011-08-31 at 21:55 -0500, Benjamin Marzinski wrote:
>>> This adds a new default feature, find_multipaths. When this is set to yes,
>>> multipath will no longer try to create a multipath device for every
>>> non-blacklisted device. Instead, it will only create a device when one of
>>> three conditions are met.
>>>
>>> 1. Three are at least two non-blacklisted paths with the same wwid
>>> 2. The user manually forces the creation, by specifying a device with the
>>>     multipath command.
>>> 3. A path has the same wwid as a multipath device that was previously crreated
>>>     (even if that multipath device doesn't currently exist).
>>>
>> Hannes,
>>
>> this patch implements complex semantics and mis-use /etc to store
>> variable data (/run was suggested as a replacement). Though I realize
>> the benefits, I'm not at ease merging it.
>
> This will add wwids to the wwids file at the same times that new bindings
> get added to the bindings file. We decided to move the bindings file to
> /etc/multipath/bindings because it caused problems during bootup, if
> /var/run was not mounted.  This will have the same problems where you
> will be writing to a file that eventually gets mounted over.  So I am
> against using /var/run
>
I already did a patch to allow for a different location for the 
bindings file (methinks it's upstream, isn't it?)

But that's not the issue.
The issue here is an inversion in behaviour.
Normally multipath would access / manage all devices except those
blacklisted in /etc/multipath.conf
With the patch multipath would access / manage _no_ devices except 
those listed in /etc/multipath.conf

Which is the main point of contention.
So as such I'm not happy with this, too.

However, we definitely need to figure out how integrate with systemd.
 From my understanding we need to have some 'trigger', telling 
systemd to ignore any disks multipath might hook onto.

Sure, the find_multipaths feature would be a possible solution here, 
as then systemd could evaluate the config file any everything would 
be dandy.

However, I would prefer to modify 'multipath' (which is in the 
process on becoming obsoleted currently). This could program could 
then be used to provide systemd with the required information, ie if 
a device should be ignored or not.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)

Re: [PATCH v2] multipath: add find_multipaths feature.

[Benjamin Marzinski]

On Thu, Sep 01, 2011 at 04:35:16PM +0200, Hannes Reinecke wrote:
> I already did a patch to allow for a different location for the bindings 
> file (methinks it's upstream, isn't it?)

It is.

> The issue here is an inversion in behaviour.
> Normally multipath would access / manage all devices except those
> blacklisted in /etc/multipath.conf
> With the patch multipath would access / manage _no_ devices except those 
> listed in /etc/multipath.conf

Or any devices that have two paths to them. Or devices that have, in the
past, had two paths to them. The idea behind this was to make multipath
"just work", without users needing to bother touching
/etc/multipath.conf at all, for common storage arrays.

multipathd will find all the devices with multiple paths (except the
blacklisted ones), and remember them so that in the future, as soon as
the first path becomes available, multipathd knows that it should be
multipathed.  Blacklisting works just as before. The only difference is
that you no longer need to use the blacklist to keep multipath from
grabbing devices that don't have multiple paths.  You only use it if you
have multiple paths, but for some reason you don't want to have
multipath manage them.

For devices with only one path, the user will need to specifically add
them.  But if the user want's to use multipath on single path devices,
then just don't turn on find_multipaths.

So I'm not sure I understand your objection.

> However, we definitely need to figure out how integrate with systemd.
> From my understanding we need to have some 'trigger', telling systemd to 
> ignore any disks multipath might hook onto.

With the wwids file, it's simple to be able to tell if a disk belongs to
multipath after multipath has already been setup on it once.  The only
issue is on the first time the disk is seen.  With find_multipaths this
is problem, since multipath won't know until it sees a second path to
the disk if it should be multipathed.  Without find_multipaths, we could
just assume that if the device is not blacklisted, it belongs to
multipath.

-Ben

> Sure, the find_multipaths feature would be a possible solution here, as 
> then systemd could evaluate the config file any everything would be dandy.
>
> However, I would prefer to modify 'multipath' (which is in the process on 
> becoming obsoleted currently). This could program could then be used to 
> provide systemd with the required information, ie if a device should be 
> ignored or not.
>
> Cheers,
>
> Hannes
> -- 
> Dr. Hannes Reinecke		      zSeries & Storage
> hare@suse.de			      +49 911 74053 688
> SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)

Re: [PATCH v2] multipath: add find_multipaths feature.

[Benjamin Marzinski]

On Thu, Sep 01, 2011 at 09:21:06AM -0500, Benjamin Marzinski wrote:
> 
> although it looks like the systemd folks have made /run a tmpfs
> filesystem, and /var/run a pointer to it (at least in Fedora), so I
> guess I'm not opposed to moving things back to /var/run anymore.
> 

When I wrote this, I had just finished writing an email about how
/var/run being on tmpfs made it o.k. for pidfiles, and my brain had
obviously not switched gears. While I have no problem with pidfiles on
/var/run, storing permanent configuration files on it is obviously not
an option if it is a tmpfs filesystem.

-Ben

Re: [PATCH v2] multipath: add find_multipaths feature.

[Christophe Varoqui]

[-- Attachment #1.1: Type: text/plain, Size: 111 bytes --]

Sure, i was really meaning /run.
Le 1 sept. 2011 14:57, "Benjamin Marzinski" <bmarzins@redhat.com> a écrit :

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