On Tue, 31 Aug 2010 15:32:40 -0400
Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> This patch is the second attempt at fixing this problem. It's basically
> the same as the first patch, but adds some xlog() calls to log info
> when there are problems. I also changed the NFSD_*_FILE definitions
> around so that they are defined based on another constant that holds
> the nfsdfs mountpoint.
>
> ---------------------------[snip]-------------------------
> There's a bit of a chicken and egg problem when nfsd is run the first
> time. On Fedora/RHEL at least, /proc/fs/nfsd is mounted up whenever nfsd
> is plugged in via a modprobe.conf "install" directive.
>
> If someone runs rpc.nfsd without plugging in nfsd.ko first,
> /proc/fs/nfsd won't be mounted and rpc.nfsd will end up using the legacy
> nfsctl interface. After that, nfsd will be plugged in and subsequent
> rpc.nfsd invocations will use that instead.
>
> This is a problem as some nfsd command-line options are ignored when the
> legacy interface is used. It'll also be a problem for people who want
> IPv6 enabled servers. The upshot is that we really don't want to use the
> legacy interface unless there is no other option.
>
> To avoid this situation, have rpc.nfsd check to see if the "threads"
> file is already present. If it's not, then make an attempt to mount
> /proc/fs/nfsd. This is a "best-effort" sort of thing, however so we
> just ignore the return code from the mount attempt and fall back to
> using nfsctl() if it fails.
>
> Full disclosure: I'm not 100% thrilled with this patch. It seems ugly
> and kludgey, but I don't see a better way to handle this problem.
> Suggestions welcome.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> utils/nfsd/nfsd.c | 3 ++
> utils/nfsd/nfssvc.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++--
> utils/nfsd/nfssvc.h | 1 +
> 3 files changed, 54 insertions(+), 3 deletions(-)
>
> diff --git a/utils/nfsd/nfsd.c b/utils/nfsd/nfsd.c
> index 1cda1e5..6bbf697 100644
> --- a/utils/nfsd/nfsd.c
> +++ b/utils/nfsd/nfsd.c
> @@ -246,6 +246,9 @@ main(int argc, char **argv)
> exit(1);
> }
>
> + /* make sure nfsdfs is mounted if it's available */
> + nfssvc_mount_nfsdfs();
> +
> /* can only change number of threads if nfsd is already up */
> if (nfssvc_inuse()) {
> socket_up = 1;
> diff --git a/utils/nfsd/nfssvc.c b/utils/nfsd/nfssvc.c
> index 34c67ca..636b403 100644
> --- a/utils/nfsd/nfssvc.c
> +++ b/utils/nfsd/nfssvc.c
> @@ -15,9 +15,11 @@
> #include <netdb.h>
> #include <netinet/in.h>
> #include <arpa/inet.h>
> +#include <sys/stat.h>
> #include <unistd.h>
> #include <fcntl.h>
> #include <errno.h>
> +#include <stdlib.h>
>
> #include "nfslib.h"
> #include "xlog.h"
> @@ -31,9 +33,10 @@
> */
> #undef IPV6_SUPPORTED
>
> -#define NFSD_PORTS_FILE "/proc/fs/nfsd/portlist"
> -#define NFSD_VERS_FILE "/proc/fs/nfsd/versions"
> -#define NFSD_THREAD_FILE "/proc/fs/nfsd/threads"
> +#define NFSD_FS_DIR "/proc/fs/nfsd"
> +#define NFSD_PORTS_FILE NFSD_FS_DIR "/portlist"
> +#define NFSD_VERS_FILE NFSD_FS_DIR "/versions"
> +#define NFSD_THREAD_FILE NFSD_FS_DIR "/threads"
>
> /*
> * declaring a common static scratch buffer here keeps us from having to
> @@ -44,6 +47,50 @@
> char buf[128];
>
> /*
> + * Using the "new" interfaces for nfsd requires that /proc/fs/nfsd is
> + * actually mounted. Make an attempt to mount it here if it doesn't appear
> + * to be. If the mount attempt fails, no big deal -- fall back to using nfsctl
> + * instead.
> + */
> +void
> +nfssvc_mount_nfsdfs(void)
> +{
> + int err;
> + struct stat statbuf;
> +
> + err = stat(NFSD_THREAD_FILE, &statbuf);
> + if (err == 0)
> + return;
> + else if (errno != ENOENT) {
> + xlog(L_ERROR, "Unable to stat %s: errno %d (%m)",
> + NFSD_THREAD_FILE, errno);
> + return;
> + }
> +
> + /*
> + * this call can return an error if modprobe is set up to automatically
> + * mount nfsdfs when nfsd.ko is plugged in. So, ignore the return
> + * code from it and just check for the "threads" file afterward.
> + */
> + system("/bin/mount -t nfsd nfsd " NFSD_FS_DIR " >/dev/null 2>&1");
> +
> + err = stat(NFSD_THREAD_FILE, &statbuf);
> + if (err == 0)
> + return;
> +
> + if (errno == ENOENT)
> + xlog(L_ERROR, "Unable to mount nfsdfs on %s. Falling back "
> + "to legacy nfsctl() interface. Some command "
> + "line options may not work correctly.",
> + NFSD_FS_DIR);
> + else
> + xlog(L_ERROR, "Unable to stat %s after attempting to mount "
> + "%s. Falling back to legacy nfsctl() interface: "
> + "errno %d (%m)",
> + NFSD_THREAD_FILE, NFSD_FS_DIR, errno);
> +}
> +
> +/*
> * Are there already sockets configured? If not, then it is safe to try to
> * open some and pass them through.
> *
> diff --git a/utils/nfsd/nfssvc.h b/utils/nfsd/nfssvc.h
> index 0c69bd6..ff81165 100644
> --- a/utils/nfsd/nfssvc.h
> +++ b/utils/nfsd/nfssvc.h
> @@ -20,6 +20,7 @@
> *
> */
>
> +void nfssvc_mount_nfsdfs(void);
> int nfssvc_inuse(void);
> int nfssvc_set_sockets(const int family, const unsigned int protobits,
> const char *host, const char *port);
Hi Steve,
It's been a couple of weeks and this latest patch hasn't been committed...
IIRC, you wanted changes to the xlog messages and were going to send an
alternate patch. I'd like to see this in the next release of nfs-utils.
What do we need to do to move this to resolution?
Thanks,
--
Jeff Layton <jlayton@xxxxxxxxxx>
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