NFSv4 to be a default on RHEL-6

NFSv4 to be a default on RHEL-6

[Ondrej Valousek]

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  Hi Ian,

I have just noticed that on RHEL-6 is NFSv4 a default filesystem for NFS. However, when I browse using automounter & /net, all folders are 
mounted via NFSv3. That's a bit confusing.... shall we perhaps use nfs4 as a default in autofs, too?

Thanks,
Ondrej

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Re: NFSv4 to be a default on RHEL-6

[Ian Kent]

On Wed, 2010-12-08 at 10:16 +0100, Ondrej Valousek wrote:
> Hi Ian,
> 
> I have just noticed that on RHEL-6 is NFSv4 a default filesystem for
> NFS. However, when I browse using automounter & /net, all folders are
> mounted via NFSv3. That's a bit confusing.... shall we perhaps use
> nfs4 as a default in autofs, too?

The default should be determined by mount.nfs(8) since that's what
autofs uses to perform mounts.

There are more issues when you are using an NFSv4 global root since
there is no way for a client to know what that global root is, that
information is not present in the exports information. So, the server
must honor mounts that append the global root to the server mount path
and also those which don't.

Ian

Re: NFSv4 to be a default on RHEL-6

[Ondrej Valousek]

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  On 08.12.2010 13:36, Ian Kent wrote:
> The default should be determined by mount.nfs(8) since that's what
> autofs uses to perform mounts.
I see, but it works only if the nfs4 root export is the same as /. It does not work otherwise. Example:
Server 'dorado' exporting directory /exports which is also fsid=0 for nfs4.
There is (also shared) subdirectory 'ext1' in this one. When I do:

cd /net/dorado/exports/ext1

... the export is mounted using NFSv3. Theoretically if I did:

cd /net/dorado/ext1

... I should have the same mounted via NFSv4, right? Unfortunately it does not work. But it should because:

mount dorado:/ext1 /mnt

works (giving nfs4 mount)....
Ondrej


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Re: NFSv4 to be a default on RHEL-6

[Ian Kent]

On Wed, 2010-12-08 at 13:51 +0100, Ondrej Valousek wrote:
> On 08.12.2010 13:36, Ian Kent wrote: 
> > The default should be determined by mount.nfs(8) since that's what
> > autofs uses to perform mounts.
> I see, but it works only if the nfs4 root export is the same as /. It
> does not work otherwise. Example:
> Server 'dorado' exporting directory /exports which is also fsid=0 for
> nfs4.
> There is (also shared) subdirectory 'ext1' in this one. When I do:
> 
> cd /net/dorado/exports/ext1
> 
> ... the export is mounted using NFSv3. Theoretically if I did:
> 
> cd /net/dorado/ext1
> 
> ... I should have the same mounted via NFSv4, right? Unfortunately it
> does not work. But it should because:
> 
> mount dorado:/ext1 /mnt
> 
> works (giving nfs4 mount)....

The only information the hosts map has to go on is the export list
received from the server.

There is no way for autofs to know that /exports is the global root from
the mountd exports information. It only knows that /exports is an export
and neither does it know what NFS version the server may offer for this
mount. That information just isn't available.

As I said, I thought in recent Fedora releases (not sure now when this
should have happened), that

mount <server>:/exports /<some mount point>

and 

mount <server>:/ /<some mount point>

should both work and mount as NFSv4. Correct me if I'm wrong but your
point is that it is mounting as NFSv3 so perhaps we should log a bug and
see what the experts have to say on this.

Ian

Re: NFSv4 to be a default on RHEL-6

[Ondrej Valousek]

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  On 08.12.2010 14:45, Ian Kent wrote:
> On Wed, 2010-12-08 at 13:51 +0100, Ondrej Valousek wrote:
>> On 08.12.2010 13:36, Ian Kent wrote:
>>> The default should be determined by mount.nfs(8) since that's what
>>> autofs uses to perform mounts.
>> I see, but it works only if the nfs4 root export is the same as /. It
>> does not work otherwise. Example:
>> Server 'dorado' exporting directory /exports which is also fsid=0 for
>> nfs4.
>> There is (also shared) subdirectory 'ext1' in this one. When I do:
>>
>> cd /net/dorado/exports/ext1
>>
>> ... the export is mounted using NFSv3. Theoretically if I did:
>>
>> cd /net/dorado/ext1
>>
>> ... I should have the same mounted via NFSv4, right? Unfortunately it
>> does not work. But it should because:
>>
>> mount dorado:/ext1 /mnt
>>
>> works (giving nfs4 mount)....
> The only information the hosts map has to go on is the export list
> received from the server.
>
> There is no way for autofs to know that /exports is the global root from
> the mountd exports information. It only knows that /exports is an export
> and neither does it know what NFS version the server may offer for this
> mount. That information just isn't available.
>
> As I said, I thought in recent Fedora releases (not sure now when this
> should have happened), that
>
> mount<server>:/exports /<some mount point>
>
> and
>
> mount<server>:/ /<some mount point>
>
> should both work and mount as NFSv4. Correct me if I'm wrong but your
> point is that it is mounting as NFSv3 so perhaps we should log a bug and
> see what the experts have to say on this.
>
> Ian
>
>
Hi Ian,

I understand that autofs can not know that /exports is a global root. I just thought that mine:

cd /net/dorado/ext1

... (i.e. omitting the "exports" word) should work as this way should autofs pass something like this : "mount.nfs dorado:/ext1 
/net/dorado/ext1" which would succeed then, resulting in a nfs4 mount. What happens now is (obviously) that autofs can not find 'ext1' in 
the exports information from 'dorado' and so it fails even without trying....

Ondrej

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Re: NFSv4 to be a default on RHEL-6

[Ian Kent]

On Wed, 2010-12-08 at 15:56 +0100, Ondrej Valousek wrote:
> On 08.12.2010 14:45, Ian Kent wrote: 
> > On Wed, 2010-12-08 at 13:51 +0100, Ondrej Valousek wrote:
> > > On 08.12.2010 13:36, Ian Kent wrote: 
> > > > The default should be determined by mount.nfs(8) since that's what
> > > > autofs uses to perform mounts.
> > > I see, but it works only if the nfs4 root export is the same as /. It
> > > does not work otherwise. Example:
> > > Server 'dorado' exporting directory /exports which is also fsid=0 for
> > > nfs4.
> > > There is (also shared) subdirectory 'ext1' in this one. When I do:
> > > 
> > > cd /net/dorado/exports/ext1
> > > 
> > > ... the export is mounted using NFSv3. Theoretically if I did:
> > > 
> > > cd /net/dorado/ext1
> > > 
> > > ... I should have the same mounted via NFSv4, right? Unfortunately it
> > > does not work. But it should because:
> > > 
> > > mount dorado:/ext1 /mnt
> > > 
> > > works (giving nfs4 mount)....
> > The only information the hosts map has to go on is the export list
> > received from the server.
> > 
> > There is no way for autofs to know that /exports is the global root from
> > the mountd exports information. It only knows that /exports is an export
> > and neither does it know what NFS version the server may offer for this
> > mount. That information just isn't available.
> > 
> > As I said, I thought in recent Fedora releases (not sure now when this
> > should have happened), that
> > 
> > mount <server>:/exports /<some mount point>
> > 
> > and 
> > 
> > mount <server>:/ /<some mount point>
> > 
> > should both work and mount as NFSv4. Correct me if I'm wrong but your
> > point is that it is mounting as NFSv3 so perhaps we should log a bug and
> > see what the experts have to say on this.
> > 
> > Ian
> > 
> > 
> Hi Ian,
> 
> I understand that autofs can not know that /exports is a global root.
> I just thought that mine:
> 
> cd /net/dorado/ext1
> 
> ... (i.e. omitting the "exports" word) should work as this way should
> autofs pass something like this : "mount.nfs
> dorado:/ext1 /net/dorado/ext1" which would succeed then, resulting in
> a nfs4 mount. What happens now is (obviously) that autofs can not find
> 'ext1' in the exports information from 'dorado' and so it fails even
> without trying....

OK, third attempt.
That does not appear in the exports list from mountd.
The information to achieve this is "not" available in the exports list
you get from the server. What's more, AFAICS, you can't know which
export is a global root.

Ian

Re: NFSv4 to be a default on RHEL-6

[Steve Dickson]

On 12/08/2010 09:56 AM, Ondrej Valousek wrote:
> On 08.12.2010 14:45, Ian Kent wrote:
>> On Wed, 2010-12-08 at 13:51 +0100, Ondrej Valousek wrote:
>>> On 08.12.2010 13:36, Ian Kent wrote: 
>>>> The default should be determined by mount.nfs(8) since that's what
>>>> autofs uses to perform mounts.
>>> I see, but it works only if the nfs4 root export is the same as /. It
>>> does not work otherwise. Example:
>>> Server 'dorado' exporting directory /exports which is also fsid=0 for
>>> nfs4.
>>> There is (also shared) subdirectory 'ext1' in this one. When I do:
>>>
>>> cd /net/dorado/exports/ext1
>>>
>>> ... the export is mounted using NFSv3. Theoretically if I did:
>>>
>>> cd /net/dorado/ext1
>>>
>>> ... I should have the same mounted via NFSv4, right? Unfortunately it
>>> does not work. But it should because:
>>>
>>> mount dorado:/ext1 /mnt
>>>
>>> works (giving nfs4 mount)....
>> The only information the hosts map has to go on is the export list
>> received from the server.
>>
>> There is no way for autofs to know that /exports is the global root from
>> the mountd exports information. It only knows that /exports is an export
>> and neither does it know what NFS version the server may offer for this
>> mount. That information just isn't available.
>>
>> As I said, I thought in recent Fedora releases (not sure now when this
>> should have happened), that
>>
>> mount <server>:/exports /<some mount point>
>>
>> and 
>>
>> mount <server>:/ /<some mount point>
>>
>> should both work and mount as NFSv4. Correct me if I'm wrong but your
>> point is that it is mounting as NFSv3 so perhaps we should log a bug and
>> see what the experts have to say on this.
>>
>> Ian
>>
>>
> Hi Ian,
> 
> I understand that autofs can not know that /exports is a global root. I just thought that mine:
> 
> cd /net/dorado/ext1
> 
> ... (i.e. omitting the "exports" word) should work as this way should autofs pass something like this : "mount.nfs dorado:/ext1 /net/dorado/ext1" which would succeed then, resulting in a nfs4 mount. What happens now is (obviously) that autofs can not find 'ext1' in the exports information from 'dorado' and so it fails even without trying....
It depends on your server... If your server does not support v4, the
mount will roll back to v3. An rpcinfo -p <server> will show if 
the server support v4.

steved.

Re: NFSv4 to be a default on RHEL-6

[Ian Kent]

On Thu, 2010-12-09 at 07:51 -0500, Steve Dickson wrote:
> 
> On 12/08/2010 09:56 AM, Ondrej Valousek wrote:
> > On 08.12.2010 14:45, Ian Kent wrote:
> >> On Wed, 2010-12-08 at 13:51 +0100, Ondrej Valousek wrote:
> >>> On 08.12.2010 13:36, Ian Kent wrote: 
> >>>> The default should be determined by mount.nfs(8) since that's what
> >>>> autofs uses to perform mounts.
> >>> I see, but it works only if the nfs4 root export is the same as /. It
> >>> does not work otherwise. Example:
> >>> Server 'dorado' exporting directory /exports which is also fsid=0 for
> >>> nfs4.
> >>> There is (also shared) subdirectory 'ext1' in this one. When I do:
> >>>
> >>> cd /net/dorado/exports/ext1
> >>>
> >>> ... the export is mounted using NFSv3. Theoretically if I did:
> >>>
> >>> cd /net/dorado/ext1
> >>>
> >>> ... I should have the same mounted via NFSv4, right? Unfortunately it
> >>> does not work. But it should because:
> >>>
> >>> mount dorado:/ext1 /mnt
> >>>
> >>> works (giving nfs4 mount)....
> >> The only information the hosts map has to go on is the export list
> >> received from the server.
> >>
> >> There is no way for autofs to know that /exports is the global root from
> >> the mountd exports information. It only knows that /exports is an export
> >> and neither does it know what NFS version the server may offer for this
> >> mount. That information just isn't available.
> >>
> >> As I said, I thought in recent Fedora releases (not sure now when this
> >> should have happened), that
> >>
> >> mount <server>:/exports /<some mount point>
> >>
> >> and 
> >>
> >> mount <server>:/ /<some mount point>
> >>
> >> should both work and mount as NFSv4. Correct me if I'm wrong but your
> >> point is that it is mounting as NFSv3 so perhaps we should log a bug and
> >> see what the experts have to say on this.
> >>
> >> Ian
> >>
> >>
> > Hi Ian,
> > 
> > I understand that autofs can not know that /exports is a global root. I just thought that mine:
> > 
> > cd /net/dorado/ext1
> > 
> > ... (i.e. omitting the "exports" word) should work as this way should autofs pass something like this : "mount.nfs dorado:/ext1 /net/dorado/ext1" which would succeed then, resulting in a nfs4 mount. What happens now is (obviously) that autofs can not find 'ext1' in the exports information from 'dorado' and so it fails even without trying....
> It depends on your server... If your server does not support v4, the
> mount will roll back to v3. An rpcinfo -p <server> will show if 
> the server support v4.

Knowing that the server supports NFSv4 doesn't tell me which export is a
global root though (does it?).

I guess I could code the rpcinfo calls and rewrite the mount code to
retry if v4 is supported. Not sure I like that idea though.

My problem is knowing for sure what the global root is and then I also
don't know what mount.nfs(8) will do with it. If I did have some way of
knowing what the global root was then trying to accommodate it will
cause mounts that fall back to v3 to fail.

I thought that the recent NFS server changes were meant to allow both
the mount paths above to function, like I think they do on other OSes
(I'll check on that if you really want me to)?

Ian