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Re: [dm-devel] [RESEND][PATCH] multipath: don't set queue_if_no_path without multipathd



On jeu., 2011-09-22 at 23:41 -0500, Benjamin Marzinski wrote:
> If multipathd is not running, when all paths to a device have failed, there's
> no way for them to automatically get restored.  If the device is set to queue,
> whatever is accessing it will hang forever. This can lead to problems if it
> happens at boot-up.  This patch unsets queue_if_no_path for all devices created
> when multipathd is not running. When multipathd starts, it will automatically
> get reset queue_if_no_path to the proper value.  This new behaviour can be
> overridden using the new "-q" option to multipath.
> 
> This patch applies against the current head, instead of building on my
> find_multipaths patch.  It moves pidfile.[ch] into libmultipath, but is
> functionally identical to the last version.
> 
As stated by Hannes recently, it would be better not to add more users
of the pidfile. May be you could switch to test the unix socket
instead ?

May we could also reverse the -q meaning ... making multipath default
behaviour to not honor queueing by default when multipathd is not
running. As you said, multipathd starting will update the maps.

What do you think ?

Regards,
cvaroqui
> Signed-off-by: Benjamin Marzinski <bmarzins redhat com>
> ---
>  libmultipath/Makefile    |    2 
>  libmultipath/config.h    |    1 
>  libmultipath/configure.c |   13 +++++-
>  libmultipath/pidfile.c   |   95 +++++++++++++++++++++++++++++++++++++++++++++++
>  libmultipath/pidfile.h   |    2 
>  multipath/main.c         |    8 ++-
>  multipathd/Makefile      |    2 
>  multipathd/main.c        |    2 
>  multipathd/pidfile.c     |   67 ---------------------------------
>  multipathd/pidfile.h     |    1 
>  10 files changed, 119 insertions(+), 74 deletions(-)
> 
> Index: multipath-tools-110916/libmultipath/config.h
> ===================================================================
> --- multipath-tools-110916.orig/libmultipath/config.h
> +++ multipath-tools-110916/libmultipath/config.h
> @@ -92,6 +92,7 @@ struct config {
>  	int attribute_flags;
>  	int fast_io_fail;
>  	unsigned int dev_loss;
> +	int allow_queueing;
>  	uid_t uid;
>  	gid_t gid;
>  	mode_t mode;
> Index: multipath-tools-110916/libmultipath/configure.c
> ===================================================================
> --- multipath-tools-110916.orig/libmultipath/configure.c
> +++ multipath-tools-110916/libmultipath/configure.c
> @@ -35,6 +35,7 @@
>  #include "alias.h"
>  #include "prio.h"
>  #include "util.h"
> +#include "pidfile.h"
>  
>  extern int
>  setup_map (struct multipath * mpp, char * params, int params_size)
> @@ -555,7 +556,17 @@ coalesce_paths (struct vectors * vecs, v
>  		if (r == DOMAP_DRY)
>  			continue;
>  
> -		if (mpp->no_path_retry != NO_PATH_RETRY_UNDEF) {
> +		if (!conf->daemon && !conf->allow_queueing &&
> +		    !pidfile_check(DEFAULT_PIDFILE)) {
> +			if (mpp->no_path_retry != NO_PATH_RETRY_UNDEF &&
> +			    mpp->no_path_retry != NO_PATH_RETRY_FAIL)
> +				condlog(3, "%s: multipathd not running, unset "
> +					"queue_if_no_path feature", mpp->alias);
> +			if (!dm_queue_if_no_path(mpp->alias, 0))
> +				remove_feature(&mpp->features,
> +					       "queue_if_no_path");
> +		}
> +		else if (mpp->no_path_retry != NO_PATH_RETRY_UNDEF) {
>  			if (mpp->no_path_retry == NO_PATH_RETRY_FAIL) {
>  				condlog(3, "%s: unset queue_if_no_path feature",
>  					mpp->alias);
> Index: multipath-tools-110916/multipath/main.c
> ===================================================================
> --- multipath-tools-110916.orig/multipath/main.c
> +++ multipath-tools-110916/multipath/main.c
> @@ -79,7 +79,7 @@ usage (char * progname)
>  {
>  	fprintf (stderr, VERSION_STRING);
>  	fprintf (stderr, "Usage:\n");
> -	fprintf (stderr, "  %s [-d] [-r] [-v lvl] [-p pol] [-b fil] [dev]\n", progname);
> +	fprintf (stderr, "  %s [-d] [-r] [-v lvl] [-p pol] [-b fil] [-q] [dev]\n", progname);
>  	fprintf (stderr, "  %s -l|-ll|-f [-v lvl] [-b fil] [dev]\n", progname);
>  	fprintf (stderr, "  %s -F [-v lvl]\n", progname);
>  	fprintf (stderr, "  %s -t\n", progname);
> @@ -92,6 +92,7 @@ usage (char * progname)
>  		"  -ll     show multipath topology (maximum info)\n" \
>  		"  -f      flush a multipath device map\n" \
>  		"  -F      flush all multipath device maps\n" \
> +		"  -q      allow queue_if_no_path when multipathd is not running\n"\
>  		"  -d      dry run, do not create or update devmaps\n" \
>  		"  -t      dump internal hardware table\n" \
>  		"  -r      force devmap reload\n" \
> @@ -397,7 +398,7 @@ main (int argc, char *argv[])
>  		condlog(0, "multipath tools need sysfs mounted");
>  		exit(1);
>  	}
> -	while ((arg = getopt(argc, argv, ":dhl::FfM:v:p:b:Brt")) != EOF ) {
> +	while ((arg = getopt(argc, argv, ":dhl::FfM:v:p:b:Brtq")) != EOF ) {
>  		switch(arg) {
>  		case 1: printf("optarg : %s\n",optarg);
>  			break;
> @@ -414,6 +415,9 @@ main (int argc, char *argv[])
>  		case 'B':
>  			conf->bindings_read_only = 1;
>  			break;
> +		case 'q':
> +			conf->allow_queueing = 1;
> +			break;
>  		case 'd':
>  			conf->dry_run = 1;
>  			break;
> Index: multipath-tools-110916/multipathd/pidfile.c
> ===================================================================
> --- multipath-tools-110916.orig/multipathd/pidfile.c
> +++ /dev/null
> @@ -1,67 +0,0 @@
> -#include <sys/types.h> /* for pid_t */
> -#include <sys/stat.h>  /* for open */
> -#include <signal.h>    /* for kill() */
> -#include <errno.h>     /* for ESHRC */
> -#include <stdio.h>     /* for f...() */
> -#include <string.h>    /* for memset() */
> -#include <stdlib.h>    /* for atoi() */
> -#include <unistd.h>    /* for unlink() */
> -#include <fcntl.h>     /* for fcntl() */
> -
> -#include <debug.h>
> -
> -#include "pidfile.h"
> -
> -int pidfile_create(const char *pidFile, pid_t pid)
> -{
> -	char buf[20];
> -	struct flock lock;
> -	int fd, value;
> -
> -	if((fd = open(pidFile, O_WRONLY | O_CREAT,
> -		       (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH))) < 0) {
> -		condlog(0, "Cannot open pidfile [%s], error was [%s]",
> -			pidFile, strerror(errno));
> -		return 1;
> -	}
> -	lock.l_type = F_WRLCK;
> -	lock.l_start = 0;
> -	lock.l_whence = SEEK_SET;
> -	lock.l_len = 0;
> -
> -	if (fcntl(fd, F_SETLK, &lock) < 0) {
> -		if (errno != EACCES && errno != EAGAIN)
> -			condlog(0, "Cannot lock pidfile [%s], error was [%s]",
> -				pidFile, strerror(errno));
> -		else
> -			condlog(0, "process is already running");
> -		goto fail;
> -	}
> -	if (ftruncate(fd, 0) < 0) {
> -		condlog(0, "Cannot truncate pidfile [%s], error was [%s]",
> -			pidFile, strerror(errno));
> -		goto fail;
> -	}
> -	memset(buf, 0, sizeof(buf));
> -	snprintf(buf, sizeof(buf)-1, "%u", pid);
> -	if (write(fd, buf, strlen(buf)) != strlen(buf)) {
> -		condlog(0, "Cannot write pid to pidfile [%s], error was [%s]",
> -			pidFile, strerror(errno));
> -		goto fail;
> -	}
> -	if ((value = fcntl(fd, F_GETFD, 0)) < 0) {
> -		condlog(0, "Cannot get close-on-exec flag from pidfile [%s], "
> -			"error was [%s]", pidFile, strerror(errno));
> -		goto fail;
> -	}
> -	value |= FD_CLOEXEC;
> -	if (fcntl(fd, F_SETFD, value) < 0) {
> -		condlog(0, "Cannot set close-on-exec flag from pidfile [%s], "
> -			"error was [%s]", pidFile, strerror(errno));
> -		goto fail;
> -	}
> -	return 0;
> -fail:
> -	close(fd);
> -	return 1;
> -}
> Index: multipath-tools-110916/multipathd/pidfile.h
> ===================================================================
> --- multipath-tools-110916.orig/multipathd/pidfile.h
> +++ /dev/null
> @@ -1 +0,0 @@
> -int pidfile_create(const char *pidFile, pid_t pid);
> Index: multipath-tools-110916/libmultipath/Makefile
> ===================================================================
> --- multipath-tools-110916.orig/libmultipath/Makefile
> +++ multipath-tools-110916/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 pidfile.o
>  
>  LIBDM_API_FLUSH = $(shell grep -Ecs '^[a-z]*[[:space:]]+dm_task_no_flush' /usr/include/libdevmapper.h)
>  
> Index: multipath-tools-110916/libmultipath/pidfile.c
> ===================================================================
> --- /dev/null
> +++ multipath-tools-110916/libmultipath/pidfile.c
> @@ -0,0 +1,95 @@
> +#include <sys/types.h> /* for pid_t */
> +#include <sys/stat.h>  /* for open */
> +#include <signal.h>    /* for kill() */
> +#include <errno.h>     /* for ESHRC */
> +#include <stdio.h>     /* for f...() */
> +#include <string.h>    /* for memset() */
> +#include <stdlib.h>    /* for atoi() */
> +#include <unistd.h>    /* for unlink() */
> +#include <fcntl.h>     /* for fcntl() */
> +
> +#include "debug.h"
> +#include "pidfile.h"
> +
> +int pidfile_create(const char *pidFile, pid_t pid)
> +{
> +	char buf[20];
> +	struct flock lock;
> +	int fd, value;
> +
> +	if((fd = open(pidFile, O_WRONLY | O_CREAT,
> +		       (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH))) < 0) {
> +		condlog(0, "Cannot open pidfile [%s], error was [%s]",
> +			pidFile, strerror(errno));
> +		return 1;
> +	}
> +	lock.l_type = F_WRLCK;
> +	lock.l_start = 0;
> +	lock.l_whence = SEEK_SET;
> +	lock.l_len = 0;
> +
> +	if (fcntl(fd, F_SETLK, &lock) < 0) {
> +		if (errno != EACCES && errno != EAGAIN)
> +			condlog(0, "Cannot lock pidfile [%s], error was [%s]",
> +				pidFile, strerror(errno));
> +		else
> +			condlog(0, "process is already running");
> +		goto fail;
> +	}
> +	if (ftruncate(fd, 0) < 0) {
> +		condlog(0, "Cannot truncate pidfile [%s], error was [%s]",
> +			pidFile, strerror(errno));
> +		goto fail;
> +	}
> +	memset(buf, 0, sizeof(buf));
> +	snprintf(buf, sizeof(buf)-1, "%u", pid);
> +	if (write(fd, buf, strlen(buf)) != strlen(buf)) {
> +		condlog(0, "Cannot write pid to pidfile [%s], error was [%s]",
> +			pidFile, strerror(errno));
> +		goto fail;
> +	}
> +	if ((value = fcntl(fd, F_GETFD, 0)) < 0) {
> +		condlog(0, "Cannot get close-on-exec flag from pidfile [%s], "
> +			"error was [%s]", pidFile, strerror(errno));
> +		goto fail;
> +	}
> +	value |= FD_CLOEXEC;
> +	if (fcntl(fd, F_SETFD, value) < 0) {
> +		condlog(0, "Cannot set close-on-exec flag from pidfile [%s], "
> +			"error was [%s]", pidFile, strerror(errno));
> +		goto fail;
> +	}
> +	return 0;
> +fail:
> +	close(fd);
> +	return 1;
> +}
> +
> +int pidfile_check(const char *file)
> +{
> +	int fd;
> +	struct flock lock;
> +
> +	fd = open(file, O_RDONLY);
> +	if (fd < 0) {
> +		if (errno == ENOENT)
> +			return 0;
> +		condlog(0, "Cannot open pidfile, %s : %s", file,
> +				strerror(errno));
> +		return -1;
> +	}
> +	lock.l_type = F_WRLCK;
> +	lock.l_start = 0;
> +	lock.l_whence = SEEK_SET;
> +	lock.l_len = 0;
> +
> +	if (fcntl(fd, F_GETLK, &lock) < 0) {
> +		condlog(0, "Cannot check lock on pidfile, %s : %s", file,
> +				strerror(errno));
> +		return -1;
> +	}
> +	close(fd);
> +	if (lock.l_type == F_UNLCK)
> +		return 0;
> +	return 1;
> +}
> Index: multipath-tools-110916/libmultipath/pidfile.h
> ===================================================================
> --- /dev/null
> +++ multipath-tools-110916/libmultipath/pidfile.h
> @@ -0,0 +1,2 @@
> +int pidfile_create(const char *pidFile, pid_t pid);
> +int pidfile_check(const char *file);
> Index: multipath-tools-110916/multipathd/Makefile
> ===================================================================
> --- multipath-tools-110916.orig/multipathd/Makefile
> +++ multipath-tools-110916/multipathd/Makefile
> @@ -19,7 +19,7 @@ LDFLAGS += -lpthread -ldevmapper -lreadl
>  #
>  # object files
>  #
> -OBJS = main.o pidfile.o uxlsnr.o uxclnt.o cli.o cli_handlers.o
> +OBJS = main.o uxlsnr.o uxclnt.o cli.o cli_handlers.o
>  
> 
>  #
> Index: multipath-tools-110916/multipathd/main.c
> ===================================================================
> --- multipath-tools-110916.orig/multipathd/main.c
> +++ multipath-tools-110916/multipathd/main.c
> @@ -49,9 +49,9 @@
>  #include <prio.h>
>  #include <pgpolicies.h>
>  #include <uevent.h>
> +#include <pidfile.h>
>  
>  #include "main.h"
> -#include "pidfile.h"
>  #include "uxlsnr.h"
>  #include "uxclnt.h"
>  #include "cli.h"



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