On Wed, 1 Sep 2010 16:48:18 -0400
"J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
> On Tue, Aug 31, 2010 at 03:32:40PM -0400, Jeff Layton 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.
>
> Seems OK to me. If it's running /bin/mount instead of doing the mount
> by hand that bothers you, we could just decide not to care about
> /etc/mtab.
>
> --b.
>
Thanks.
Sorry, I just cut and pasted that from the original email...I should
have probably trimmed that out.
I'm less leery of it now that we've discussed it. I think the patch is
probably ok as-is. After all, modprobe calls the exact same command.
While /etc/mtab isn't what I'd call reliable info, it's probably best
to try and keep it updated.
That said, Steve mentioned to me privately that he thought the log
messages ought to be reworded. He was going to send a new patch that
does that. I'm sort of waiting on that at this point...
> >
> > 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);
> > --
> > 1.7.1
> >
--
Jeff Layton <jlayton@xxxxxxxxxx>
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
