On 08/18/2016 09:45 PM, NeilBrown wrote:
> Commit: 1e41488f428c ("systemd: Order NFS server before client")
>
> added an ordering dependency between network mounts and nfs-server.
> This is good for loop-back NFS mounts as it ensures the server
> will remain until after the mountpoint is unmounted.
>
> However is is bad for _net mounts (such as those via iSCSI) which
> are being NFS exported.
>
> nfs-server needs to be start *after* exported filesystems are mounted,
> and *before* NFS filesystems are mounted. systemd isn't able to make
> this distinction natively, so we need to help it.
>
> This patch adds a systemd generator which creates a drop-in for
> nfs-server.services so that it is started "After" any "nfs" or "nfs4"
> mount, and so that it has a "RequiresMountsFor" dependency on any
> exported filesystem. This creates the required ordering.
>
> Note that if you try to export an "nfs" mount, systemd will detect an
> ordering loop and will refused to start the nfs server. This is
> probably the correct thing to do.
>
> This patch also removes the ordering dependency with
> remote-fs-pre.target which the above-mentioned commit added. It is no
> longer needed.
>
> Signed-off-by: NeilBrown <neilb@xxxxxxxx>
> ---
> systemd/Makefile.am | 8 ++
> systemd/nfs-server-generator.c | 144 ++++++++++++++++++++++++++++++++++++++++
> systemd/nfs-server.service | 3 -
> 3 files changed, 152 insertions(+), 3 deletions(-)
> create mode 100644 systemd/nfs-server-generator.c
>
> diff --git a/systemd/Makefile.am b/systemd/Makefile.am
> index 03f96e93dccf..49c9b8d3b459 100644
> --- a/systemd/Makefile.am
> +++ b/systemd/Makefile.am
> @@ -39,8 +39,16 @@ endif
> EXTRA_DIST = $(unit_files)
>
> unit_dir = /usr/lib/systemd/system
> +generator_dir = /usr/lib/systemd/system-generators
> +
> +EXTRA_PROGRAMS = nfs-server-generator
> +genexecdir = $(generator_dir)
> +nfs_server_generator_LDADD = ../support/export/libexport.a \
> + ../support/nfs/libnfs.a \
> + ../support/misc/libmisc.a
>
> if INSTALL_SYSTEMD
> +genexec_PROGRAMS = nfs-server-generator
> install-data-hook: $(unit_files)
> mkdir -p $(DESTDIR)/$(unitdir)
> cp $(unit_files) $(DESTDIR)/$(unitdir)
These automake command are not compiling or installing the generator...
I'm looking into it but I was just wondering how you tested this code,
you compiled the code by hand?
Also looking at the other system-generators these seems to
stick to a particular naming convention 'system-<component>-generator
So I'm thinking we change the name to
systemd-nfs-server-generator
steved.
> diff --git a/systemd/nfs-server-generator.c b/systemd/nfs-server-generator.c
> new file mode 100644
> index 000000000000..af8bb52bfbd7
> --- /dev/null
> +++ b/systemd/nfs-server-generator.c
> @@ -0,0 +1,144 @@
> +/*
> + * nfs-server-generator:
> + * systemd generator to create ordering dependencies between
> + * nfs-server and various filesystem mounts
> + *
> + * 1/ nfs-server should start Before any 'nfs' mountpoints are
> + * mounted, in case they are loop-back mounts. This ordering is particularly
> + * important for the shutdown side, so the nfs-server is stopped
> + * after the filesystems are unmounted.
> + * 2/ nfs-server should start After all exported filesystems are mounted
> + * so there is no risk of exporting the underlying directory.
> + * This is particularly important for _net mounts which
> + * are not caught by "local-fs.target".
> + */
> +
> +#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 <mntent.h>
> +
> +#include "misc.h"
> +#include "nfslib.h"
> +#include "exportfs.h"
> +
> +/* A simple "set of strings" to remove duplicates
> + * found in /etc/exports
> + */
> +struct list {
> + struct list *next;
> + char *name;
> +};
> +static int is_unique(struct list **lp, char *path)
> +{
> + struct list *l = *lp;
> +
> + while (l) {
> + if (strcmp(l->name, path) == 0)
> + return 0;
> + l = l->next;
> + }
> + l = malloc(sizeof(*l));
> + l->name = path;
> + l->next = *lp;
> + *lp = l;
> + return 1;
> +}
> +
> +/* 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 == '.')
> + fputc(c, f);
> + else
> + fprintf(f, "\\x%02x", c & 0xff);
> + }
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + char *path;
> + char dirbase[] = "/nfs-server.service.d";
> + char filebase[] = "/order-with-mounts.conf";
> + nfs_export *exp;
> + int i;
> + struct list *list = NULL;
> + FILE *f, *fstab;
> + struct mntent *mnt;
> +
> + if (argc != 4 || argv[1][0] != '/') {
> + fprintf(stderr, "nfs-server-generator: create systemd dependencies for nfs-server\n");
> + fprintf(stderr, "Usage: normal-dir early-dir late-dir\n");
> + exit(1);
> + }
> +
> + path = malloc(strlen(argv[1]) + sizeof(dirbase) + sizeof(filebase));
> + if (!path)
> + exit(2);
> + if (export_read(_PATH_EXPORTS) +
> + export_d_read(_PATH_EXPORTS_D) == 0)
> + /* Nothing is exported, so nothing to do */
> + exit(0);
> +
> + strcat(strcpy(path, argv[1]), dirbase);
> + mkdir(path, 0755);
> + strcat(path, filebase);
> + f = fopen(path, "w");
> + if (!f)
> + return 1;
> + fprintf(f, "# Automatically generated by nfs-server-generator\n\n[Unit]\n");
> +
> + for (i = 0; i < MCL_MAXTYPES; i++) {
> + for (exp = exportlist[i].p_head; exp; exp = exp->m_next) {
> + if (!is_unique(&list, exp->m_export.e_path))
> + continue;
> + if (strchr(exp->m_export.e_path, ' '))
> + fprintf(f, "RequiresMountsFor=\"%s\"\n",
> + exp->m_export.e_path);
> + else
> + fprintf(f, "RequiresMountsFor=%s\n",
> + exp->m_export.e_path);
> + }
> + }
> +
> + fstab = setmntent("/etc/fstab", "r");
> + while ((mnt = getmntent(fstab)) != NULL) {
> + if (strcmp(mnt->mnt_type, "nfs") != 0 &&
> + strcmp(mnt->mnt_type, "nfs4") != 0)
> + continue;
> + fprintf(f, "Before= ");
> + systemd_escape(f, mnt->mnt_dir);
> + fprintf(f, ".mount\n");
> + }
> +
> + fclose(f);
> +
> + exit(0);
> +}
> diff --git a/systemd/nfs-server.service b/systemd/nfs-server.service
> index 2ccdc6344cd5..196c81849ff4 100644
> --- a/systemd/nfs-server.service
> +++ b/systemd/nfs-server.service
> @@ -16,9 +16,6 @@ Before= rpc-statd-notify.service
> Wants=auth-rpcgss-module.service
> After=rpc-gssd.service gssproxy.service rpc-svcgssd.service
>
> -# start/stop server before/after client
> -Before=remote-fs-pre.target
> -
> Wants=nfs-config.service
> After=nfs-config.service
>
>
>
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