Re: [nfs-utils PATCH] nfsdctl: tweak the version subcommand behavior

[Jeff Layton <jlayton@kernel.org>]

On Thu, 2025-01-09 at 10:32 -0500, Scott Mayhew wrote:
> On Thu, 09 Jan 2025, Jeff Layton wrote:
> 
> > On Wed, 2025-01-08 at 17:54 -0500, Scott Mayhew wrote:
> > > The section for the 'nfsdctl version' subcommand on the man page states
> > > that the minorversion is optional, and if omitted it will cause all
> > > minorversions to be enabled/disabled, but it currently doesn't work that
> > > way.
> > > 
> > > Make it work that way, with one exception.  If v4.0 is disabled, then
> > > 'nfsdctl version +4' will not re-enable it; instead it must be
> > > explicitly re-enabled via 'nfsdctl version +4.0'.  This mirrors the way
> > > /proc/fs/nfsd/versions works.
> > > 
> > 
> > The question is: do we want to mirror that particular quirk in the
> > interface? I'm not sure if there was a logical reason for making +4
> > work that way in the /proc interface, so it's not clear to me that we
> > want to replicate that here.
> 
> Digging thru my email archive it seems that the reason for that was to
> deal with really old kernels that understood +4/-4 but not +4.0/-4.0.
> Since old kernels obviously won't have a netlink interface for nfsd it
> seems we can drop this quirk at least.
> > 
> > Honestly, it may be better to just require explicit minorversions in
> > this interface and not worry about trying to interpret what +4
> > means. You'd need to specify "+4.1 +4.2" instead of just saying "+4",
> > but that doesn't seem too onerous.
> > 
> > Thoughts?
> 
> It seems to me main alternatives are 
> 
> 1. Drop the special handling for v4.0 but allow +4/-4 to always
> enable/disable all minor versions, including v4.0.  So a small
> adjustment to this patch.
> 
> 2. Require the minor versions to be explicitly specified for v4.  So allow
> +2/-2/+3/-3, but emit an error if +4/-4 is specified.  Maybe emit an error
> if +2.0/-2.0/+3.0/-3.0 is specified.
> 
> 3. Leave the code alone (so +4/-4 would be interpreted as +4.0/-4.1) and
> just update the man page.
> 
> 4. Make the 'nfsdctl version' behavior consistent with the nfs.conf option
> handling in 'nfsdctl autostart'.  Currently thats:
> 
>         * vers4=y turns on all minor versions.  vers4.x=n on top of that
>           will turn off those specific minor versions.
>         * vers4=n turns off all minor versions.  vers4.x=y on top of
>           that has no effect.
> 
> I don't really have a strong preference as long as the behavior matches
> whatever the man page says it is.  If I had to vote I'd just say go with
> option 3, but if it's important for the behaviors of the different
> subcommands to be consistent, then we really don't have a choice and
> have to go with option 4.
> 

Now that you've laid them out, I think option #1 sounds best. Having to
specify a minorversion is a departure from the current interface, and
probably more effort than it's worth.

The behavior in #1 also seems the most intuitive if we're going to keep
the ability to accept a value that doesn't have a minorversion.


> > > Link: https://issues.redhat.com/browse/RHEL-72477
> > > Signed-off-by: Scott Mayhew <smayhew@redhat.com>
> > > ---
> > >  utils/nfsdctl/nfsdctl.8    |  9 ++++--
> > >  utils/nfsdctl/nfsdctl.adoc |  5 +++-
> > >  utils/nfsdctl/nfsdctl.c    | 58 +++++++++++++++++++++++++++++++++++---
> > >  3 files changed, 64 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/utils/nfsdctl/nfsdctl.8 b/utils/nfsdctl/nfsdctl.8
> > > index b08fe803..835d60b4 100644
> > > --- a/utils/nfsdctl/nfsdctl.8
> > > +++ b/utils/nfsdctl/nfsdctl.8
> > > @@ -2,12 +2,12 @@
> > >  .\"     Title: nfsdctl
> > >  .\"    Author: Jeff Layton
> > >  .\" Generator: Asciidoctor 2.0.20
> > > -.\"      Date: 2024-12-30
> > > +.\"      Date: 2025-01-08
> > >  .\"    Manual: \ \&
> > >  .\"    Source: \ \&
> > >  .\"  Language: English
> > >  .\"
> > > -.TH "NFSDCTL" "8" "2024-12-30" "\ \&" "\ \&"
> > > +.TH "NFSDCTL" "8" "2025-01-08" "\ \&" "\ \&"
> > >  .ie \n(.g .ds Aq \(aq
> > >  .el       .ds Aq '
> > >  .ss \n[.ss] 0
> > > @@ -172,7 +172,10 @@ MINOR: the minor version integer value
> > >  .nf
> > >  .fam C
> > >  The minorversion field is optional. If not given, it will disable or enable
> > > -all minorversions for that major version.
> > > +all minorversions for that major version.  Note however that if NFSv4.0 was
> > > +previously disabled, it can only be re\-enabled by explicitly specifying the
> > > +minorversion (this mirrors the behavior of the /proc/fs/nfsd/versions
> > > +interface).
> > >  .fam
> > >  .fi
> > >  .if n .RE
> > > diff --git a/utils/nfsdctl/nfsdctl.adoc b/utils/nfsdctl/nfsdctl.adoc
> > > index c5921458..20e9bf8e 100644
> > > --- a/utils/nfsdctl/nfsdctl.adoc
> > > +++ b/utils/nfsdctl/nfsdctl.adoc
> > > @@ -91,7 +91,10 @@ Each subcommand can also accept its own set of options and arguments. The
> > >      MINOR: the minor version integer value
> > >  
> > >    The minorversion field is optional. If not given, it will disable or enable
> > > -  all minorversions for that major version.
> > > +  all minorversions for that major version.  Note however that if NFSv4.0 was
> > > +  previously disabled, it can only be re-enabled by explicitly specifying the
> > > +  minorversion (this mirrors the behavior of the /proc/fs/nfsd/versions
> > > +  interface).
> > >  
> > >    Note that versions can only be set when there are no nfsd threads running.
> > >  
> > > diff --git a/utils/nfsdctl/nfsdctl.c b/utils/nfsdctl/nfsdctl.c
> > > index 722bf4a0..d86ff80e 100644
> > > --- a/utils/nfsdctl/nfsdctl.c
> > > +++ b/utils/nfsdctl/nfsdctl.c
> > > @@ -761,6 +761,32 @@ static int update_nfsd_version(int major, int minor, bool enabled)
> > >  	return -EINVAL;
> > >  }
> > >  
> > > +static bool v40_is_disabled(void)
> > > +{
> > > +	int i;
> > > +
> > > +	for (i = 0; i < MAX_NFS_VERSIONS; ++i) {
> > > +		if (nfsd_versions[i].major == 0)
> > > +			break;
> > > +		if (nfsd_versions[i].major == 4 && nfsd_versions[i].minor == 0)
> > > +			return !nfsd_versions[i].enabled;
> > > +	}
> > > +	return false;
> > > +}
> > > +
> > > +static int get_max_minorversion(void)
> > > +{
> > > +	int i, max = 0;
> > > +
> > > +	for (i = 0; i < MAX_NFS_VERSIONS; ++i) {
> > > +		if (nfsd_versions[i].major == 0)
> > > +			break;
> > > +		if (nfsd_versions[i].major == 4 && nfsd_versions[i].minor > max)
> > > +			max = nfsd_versions[i].minor;
> > > +	}
> > > +	return max;
> > > +}
> > > +
> > >  static void version_usage(void)
> > >  {
> > >  	printf("Usage: %s version { {+,-}major.minor } ...\n", taskname);
> > > @@ -778,7 +804,8 @@ static void version_usage(void)
> > >  
> > >  static int version_func(struct nl_sock *sock, int argc, char ** argv)
> > >  {
> > > -	int ret, i;
> > > +	int ret, i, j, max_minor;
> > > +	bool v40_disabled;
> > >  
> > >  	/* help is only valid as first argument after command */
> > >  	if (argc > 1 &&
> > > @@ -792,6 +819,9 @@ static int version_func(struct nl_sock *sock, int argc, char ** argv)
> > >  		return ret;
> > >  
> > >  	if (argc > 1) {
> > > +		v40_disabled = v40_is_disabled();
> > > +		max_minor = get_max_minorversion();
> > > +
> > >  		for (i = 1; i < argc; ++i) {
> > >  			int ret, major, minor = 0;
> > >  			char sign = '\0', *str = argv[i];
> > > @@ -815,9 +845,29 @@ static int version_func(struct nl_sock *sock, int argc, char ** argv)
> > >  				return -EINVAL;
> > >  			}
> > >  
> > > -			ret = update_nfsd_version(major, minor, enabled);
> > > -			if (ret)
> > > -				return ret;
> > > +			/*
> > > +			 * The minorversion field is optional. If omitted, it should
> > > +			 * cause all the minor versions for that major version to be
> > > +			 * enabled/disabled.
> > > +			 *
> > > +			 * HOWEVER, we do not enable v4.0 in this manner if it was
> > > +			 * previously disabled - it has to be explicitly enabled
> > > +			 * instead.  This is to retain the behavior of the old
> > > +			 * /proc/fs/nfsd/versions interface.
> > > +			 */
> > > +			if (major == 4 && ret == 2) {
> > > +				for (j = 0; j <= max_minor; ++j) {
> > > +					if (j == 0 && enabled && v40_disabled)
> > > +						continue;
> > > +					ret = update_nfsd_version(major, j, enabled);
> > > +					if (ret)
> > > +						return ret;
> > > +				}
> > > +			} else {
> > > +				ret = update_nfsd_version(major, minor, enabled);
> > > +				if (ret)
> > > +					return ret;
> > > +			}
> > >  		}
> > >  		return set_nfsd_versions(sock);
> > >  	}
> > 
> > -- 
> > Jeff Layton <jlayton@kernel.org>
> > 
> 

-- 
Jeff Layton <jlayton@kernel.org>