Subject: Re: [nfs-utils PATCH] systemd: add generators for the rpc_pipefs
 mountpoint
To: Scott Mayhew <smayhew@redhat.com>
References: <20170328133703.19325-1-smayhew@redhat.com>
Cc: linux-nfs@vger.kernel.org
From: Steve Dickson <SteveD@RedHat.com>
Message-ID: <2aace10d-1b9b-b8e8-4f85-caf31f5f51bf@RedHat.com>
Date: Wed, 29 Mar 2017 09:42:28 -0400
MIME-Version: 1.0
In-Reply-To: <20170328133703.19325-1-smayhew@redhat.com>
Content-Type: text/plain; charset=windows-1252
Sender: linux-nfs-owner@vger.kernel.org

Hello,

On 03/28/2017 09:37 AM, Scott Mayhew wrote:
> The nfs.conf and idmapd.conf files both have config options for the
> pipefs mountpoint.  Currently, changing these from the defaults also
> requires manually overriding the systemd unit files that are hard-coded
> to mount the filesystem on /var/lib/nfs/rpc_pipefs.
The Pipefs-Directory config variable is not documented in either
idmapd.conf(5) or rpc.idmapd(8) or nfsidmap(5) so the only way
to know about it as to read the code. I would not call that
a supported interface and can easily be removed. IMHO.
The same thing goes for the Cache-Expiration variable. 

> 
> This patch adds two generators to create drop-in config files to
> override the dependencies for the systemd units that require the pipefs.
> There are two because rpc.idmapd uses a separate configuration file.  If
> idmapd's configurations are ever folded into the nfs.conf, then the
> idmapd-rpc-pipefs-generator.c can be deleted and generate=1 can be
> specified for idmapd in rpc-pipefs-generator.c.
So I'm thinking we just read Pipefs-Directory out of 
one spot that would be /etc/nfs.conf. That way we would only 
have to support one of these generators.

Also please document the Pipefs-Directory variable in both
the nfs.conf man page and in the example nfs.conf file
in the git tree. 

> 
> This patch also adds a unit file to mount the pipefs on /run/rpc_pipefs,
> since that is the most logical alternate location for the pipefs
> filesystem.  Users wanting to use some other location besides
> /var/lib/nfs/rpc_pipefs or /run/rpc_pipefs would have to create their
> own systemd mount unit file, but the generators would take care of the
> rest.
I'm not sure I understand why this new unit file, run-rpc_pipefs.mount,
is needed, especially since it is not being install (aka no updates
to the Makefile.am files).

steved.

> 
> Finally, this patch removes the dependency on the pipefs from the
> rpc-svcgssd.service unit file.  rpc.svcgssd uses the sunrpc cache
> mechanism to exchange data with the kernel, not the pipefs.
> 
> Signed-off-by: Scott Mayhew <smayhew@redhat.com>
> ---
>  systemd/Makefile.am                   |   5 +-
>  systemd/idmapd-rpc-pipefs-generator.c |  99 ++++++++++++++++++++++
>  systemd/rpc-pipefs-generator.c        | 153 ++++++++++++++++++++++++++++++++++
>  systemd/rpc-svcgssd.service           |   3 +-
>  systemd/run-rpc_pipefs.mount          |  10 +++
>  5 files changed, 267 insertions(+), 3 deletions(-)
>  create mode 100644 systemd/idmapd-rpc-pipefs-generator.c
>  create mode 100644 systemd/rpc-pipefs-generator.c
>  create mode 100644 systemd/run-rpc_pipefs.mount
> 
> diff --git a/systemd/Makefile.am b/systemd/Makefile.am
> index 0d15b9f..f09be00 100644
> --- a/systemd/Makefile.am
> +++ b/systemd/Makefile.am
> @@ -42,12 +42,15 @@ EXTRA_DIST = $(unit_files) $(man5_MANS) $(man7_MANS)
>  unit_dir = /usr/lib/systemd/system
>  generator_dir = /usr/lib/systemd/system-generators
>  
> -EXTRA_PROGRAMS	= nfs-server-generator
> +EXTRA_PROGRAMS	= nfs-server-generator rpc-pipefs-generator idmapd-rpc-pipefs-generator
>  genexecdir = $(generator_dir)
>  nfs_server_generator_LDADD = ../support/export/libexport.a \
>  			     ../support/nfs/libnfs.a \
>  			     ../support/misc/libmisc.a
>  
> +rpc_pipefs_generator_LDADD = ../support/nfs/libnfs.a
> +idmapd_rpc_pipefs_generator_LDADD = ../support/nfs/libnfs.a
> +
>  if INSTALL_SYSTEMD
>  genexec_PROGRAMS = nfs-server-generator
>  install-data-hook: $(unit_files)
> diff --git a/systemd/idmapd-rpc-pipefs-generator.c b/systemd/idmapd-rpc-pipefs-generator.c
> new file mode 100644
> index 0000000..6b0e382
> --- /dev/null
> +++ b/systemd/idmapd-rpc-pipefs-generator.c
> @@ -0,0 +1,99 @@
> +/*
> + * idmapd-rpc-pipefs-generator:
> + *   systemd generator to create ordering dependencies between
> + *   the nfs-idmapd service and the rpc_pipefs mount
> + */
> +
> +#ifdef HAVE_CONFIG_H
> +#include <config.h>
> +#endif
> +
> +#include <sys/stat.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <ctype.h>
> +#include <stdio.h>
> +
> +#include "nfslib.h"
> +#include "conffile.h"
> +
> +#define RPC_PIPEFS_DEFAULT "/var/lib/nfs/rpc_pipefs"
> +char *conf_path = _PATH_IDMAPDCONF;
> +
> +/* We need to convert a path name to a systemd unit
> + * name.  This requires some translation ('/' -> '-')
> + * and some escaping.
> + */
> +static void systemd_escape(FILE *f, char *path)
> +{
> +	while (*path == '/')
> +		path++;
> +	if (!*path) {
> +		/* "/" becomes "-", otherwise leading "/" is ignored */
> +		fputs("-", f);
> +		return;
> +	}
> +	while (*path) {
> +		char c = *path++;
> +
> +		if (c == '/') {
> +			/* multiple non-trailing slashes become '-' */
> +			while (*path == '/')
> +				path++;
> +			if (*path)
> +				fputs("-", f);
> +		} else if (isalnum(c) || c == ':' || c == '.' || c == '_')
> +			fputc(c, f);
> +		else
> +			fprintf(f, "\\x%02x", c & 0xff);
> +	}
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	char	*path;
> +	char	dirbase[] = "/nfs-idmapd.service.d";
> +	char	filebase[] = "/10-pipefs.conf";
> +	FILE	*f;
> +	char	*s;
> +
> +	/* Avoid using any external services */
> +	xlog_syslog(0);
> +
> +	if (argc != 4 || argv[1][0] != '/') {
> +		fprintf(stderr, "idmapd-rpc-pipefs-generator: create systemd dependencies for nfs-idmapd\n");
> +		fprintf(stderr, "Usage: normal-dir early-dir late-dir\n");
> +		exit(1);
> +	}
> +
> +	conf_init();
> +	s = conf_get_str("General", "pipefs-directory");
> +	if (!s)
> +		exit(0);
> +	if (strlen(s) == strlen(RPC_PIPEFS_DEFAULT) &&
> +			strcmp(s, RPC_PIPEFS_DEFAULT) == 0)
> +		exit(0);
> +
> +	path = malloc(strlen(argv[1]) + sizeof(dirbase) + sizeof(filebase));
> +	if (!path)
> +		exit(2);
> +	strcat(strcpy(path, argv[1]), dirbase);
> +	mkdir(path, 0755);
> +	strcat(path, filebase);
> +	f = fopen(path, "w");
> +	if (!f)
> +		exit(1);
> +
> +	fprintf(f, "# Automatically generated by idmapd-rpc-pipefs-generator\n\n[Unit]\n");
> +	fprintf(f, "Requires=\nRequires=");
> +	systemd_escape(f, s);
> +	fprintf(f, ".mount\n");
> +	fprintf(f, "After=\nAfter=");
> +	systemd_escape(f, s);
> +	fprintf(f, ".mount local-fs.target\n");
> +	fclose(f);
> +
> +	exit(0);
> +}
> diff --git a/systemd/rpc-pipefs-generator.c b/systemd/rpc-pipefs-generator.c
> new file mode 100644
> index 0000000..fc65cc9
> --- /dev/null
> +++ b/systemd/rpc-pipefs-generator.c
> @@ -0,0 +1,153 @@
> +/*
> + * rpc-pipefs-generator:
> + *   systemd generator to create ordering dependencies between
> + *   nfs services and the rpc_pipefs mount(s)
> + */
> +
> +#ifdef HAVE_CONFIG_H
> +#include <config.h>
> +#endif
> +
> +#include <sys/stat.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <ctype.h>
> +#include <stdio.h>
> +
> +#include "nfslib.h"
> +#include "conffile.h"
> +
> +#define NUM_PIPEFS_USERS 3
> +#define RPC_PIPEFS_DEFAULT "/var/lib/nfs/rpc_pipefs"
> +char *conf_path = NFS_CONFFILE;
> +
> +/*
> + * conf_name - the name as it appears (or would appear, in the case of idmapd,
> + *             in the /etc/nfs.conf
> + * unit_name - the name of the systemd service unit file (minus '.service')
> + * after_local_fs - should the After= directive have local-fs.target or not
> + * generate - should a drop-in config be generated or not
> + */
> +struct pipefs_user {
> +	char	*conf_name;
> +	char	*unit_name;
> +	int	after_local_fs;
> +	int	generate;
> +};
> +
> +/*
> + * blkmapd and idmapd are placeholders for now, hence generate=0.  blkmapd
> + * because it does not have nfs.conf support and because the pipefs directory
> + * cannot be overriden.  idmapd because it uses a different config file.
> + */
> +static struct pipefs_user	pipefs_users[NUM_PIPEFS_USERS] = {
> +	{
> +		.conf_name = "gssd",
> +		.unit_name = "rpc-gssd",
> +		.after_local_fs = 0,
> +		.generate = 1,
> +	},
> +	{
> +		.conf_name = "blkmapd",
> +		.unit_name = "nfs-blkmap",
> +		.after_local_fs = 0,
> +		.generate = 0,
> +	},
> +	{
> +		.conf_name = "idmapd",
> +		.unit_name = "nfs-idmapd",
> +		.after_local_fs = 1,
> +		.generate = 0,
> +	}
> +};
> +
> +/* We need to convert a path name to a systemd unit
> + * name.  This requires some translation ('/' -> '-')
> + * and some escaping.
> + */
> +static void systemd_escape(FILE *f, char *path)
> +{
> +	while (*path == '/')
> +		path++;
> +	if (!*path) {
> +		/* "/" becomes "-", otherwise leading "/" is ignored */
> +		fputs("-", f);
> +		return;
> +	}
> +	while (*path) {
> +		char c = *path++;
> +
> +		if (c == '/') {
> +			/* multiple non-trailing slashes become '-' */
> +			while (*path == '/')
> +				path++;
> +			if (*path)
> +				fputs("-", f);
> +		} else if (isalnum(c) || c == ':' || c == '.' || c == '_')
> +			fputc(c, f);
> +		else
> +			fprintf(f, "\\x%02x", c & 0xff);
> +	}
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	char	*path;
> +	char	dirbase[] = ".service.d";
> +	char	filebase[] = "/10-pipefs.conf";
> +	FILE	*f;
> +	char	*s;
> +	int	i;
> +	struct	pipefs_user p;
> +
> +	/* Avoid using any external services */
> +	xlog_syslog(0);
> +
> +	if (argc != 4 || argv[1][0] != '/') {
> +		fprintf(stderr, "rpc-pipefs-generator: create systemd dependencies for nfs services\n");
> +		fprintf(stderr, "Usage: normal-dir early-dir late-dir\n");
> +		exit(1);
> +	}
> +
> +	conf_init();
> +	for (i = 0; i < NUM_PIPEFS_USERS; i++) {
> +		p = pipefs_users[i];
> +		if (!p.generate)
> +			continue;
> +
> +		s = conf_get_str(p.conf_name, "pipefs-directory");
> +		if (!s)
> +			continue;
> +		if (strlen(s) == strlen(RPC_PIPEFS_DEFAULT) &&
> +				strcmp(s, RPC_PIPEFS_DEFAULT) == 0)
> +			continue;
> +
> +		path = malloc(strlen(argv[1]) + 1 + sizeof(p.unit_name) +
> +				sizeof(dirbase) + sizeof(filebase));
> +		if (!path)
> +			exit(2);
> +		sprintf(path, "%s/%s%s", argv[1], p.unit_name, dirbase);
> +		mkdir(path, 0755);
> +		strcat(path, filebase);
> +		f = fopen(path, "w");
> +		if (!f)
> +			exit(1);
> +
> +		fprintf(f, "# Automatically generated by rpc-pipefs-generator\n\n[Unit]\n");
> +		fprintf(f, "Requires=\nRequires=");
> +		systemd_escape(f, s);
> +		fprintf(f, ".mount\n");
> +		fprintf(f, "After=\nAfter=");
> +		systemd_escape(f, s);
> +		fprintf(f, ".mount");
> +		if (p.after_local_fs)
> +			fprintf(f, " local-fs.target");
> +		fprintf(f, "\n");
> +
> +		fclose(f);
> +	}
> +
> +	exit(0);
> +}
> diff --git a/systemd/rpc-svcgssd.service b/systemd/rpc-svcgssd.service
> index 7187e3c..cb2bcd4 100644
> --- a/systemd/rpc-svcgssd.service
> +++ b/systemd/rpc-svcgssd.service
> @@ -1,8 +1,7 @@
>  [Unit]
>  Description=RPC security service for NFS server
>  DefaultDependencies=no
> -Requires=var-lib-nfs-rpc_pipefs.mount
> -After=var-lib-nfs-rpc_pipefs.mount local-fs.target
> +After=local-fs.target
>  PartOf=nfs-server.service
>  PartOf=nfs-utils.service
>  
> diff --git a/systemd/run-rpc_pipefs.mount b/systemd/run-rpc_pipefs.mount
> new file mode 100644
> index 0000000..aab3145
> --- /dev/null
> +++ b/systemd/run-rpc_pipefs.mount
> @@ -0,0 +1,10 @@
> +[Unit]
> +Description=RPC Pipe File System
> +DefaultDependencies=no
> +After=systemd-tmpfiles-setup.service
> +Conflicts=umount.target
> +
> +[Mount]
> +What=sunrpc
> +Where=/run/rpc_pipefs
> +Type=rpc_pipefs
>