NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Erez Zadok]

I get a "permission denied" when trying to mount a localhost nfsv2/3
exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:

# mount -t ext2 /dev/hdb1 /n/lower/b0
# exportfs -o no_root_squash,rw localhost:/n/lower/b0
# mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt

Erez.

Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[J. Bruce Fields]

On Thu, Dec 06, 2007 at 09:20:41PM -0500, Erez Zadok wrote:
> I get a "permission denied" when trying to mount a localhost nfsv2/3
> exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> 
> # mount -t ext2 /dev/hdb1 /n/lower/b0
> # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt

What do you see if you watch the network traffic in ethereal?

--b.

Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Erez Zadok]

In message <20071207025504.GA3070@fieldses.org>, "J. Bruce Fields" writes:
> On Thu, Dec 06, 2007 at 09:20:41PM -0500, Erez Zadok wrote:
> > I get a "permission denied" when trying to mount a localhost nfsv2/3
> > exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> > It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> > 
> > # mount -t ext2 /dev/hdb1 /n/lower/b0
> > # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> > # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt
> 
> What do you see if you watch the network traffic in ethereal?
> 
> --b.

Bruce, I'm using nfs-utils-1.0.10-14.fc6 on an FC6 system with all latest
FC6 patches.  Using git-bisect I was able to find the patch which broke it:

commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
Author: Eric W. Biederman <ebiederm@xmission.com>
Date:   Sun Dec 2 00:33:17 2007 +1100

    [NETNS]: Fix /proc/net breakage
    
    Well I clearly goofed when I added the initial network namespace support
    for /proc/net.  Currently things work but there are odd details visible to
    user space, even when we have a single network namespace.
    
    Since we do not cache proc_dir_entry dentries at the moment we can just
    modify ->lookup to return a different directory inode depending on the
    network namespace of the process looking at /proc/net, replacing the
    current technique of using a magic and fragile follow_link method.
    
    To accomplish that this patch:
    - introduces a shadow_proc method to allow different dentries to
      be returned from proc_lookup.
    - Removes the old /proc/net follow_link magic
    - Fixes a weakness in our not caching of proc generic dentries.
    
    As shadow_proc uses a task struct to decided which dentry to return we can
    go back later and fix the proc generic caching without modifying any code
    that uses the shadow_proc method.
    
    Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    Cc: Pavel Machek <pavel@ucw.cz>
    Cc: Pavel Emelyanov <xemul@openvz.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Ingo Molnar <mingo@elte.hu>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Herbert Xu <herbert-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org>

With the above patch, rpc.mountd is unable to open /proc/fs/nfsd/filehandle.
Strace shows:

open("/proc/fs/nfsd/filehandle", O_RDWR|O_LARGEFILE) = -1 ENOENT (No such file or directory)

Without the above patch, /proc/fs/nfsd is populated with a number of files,
including "filehandle".

Erez.

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Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Erez Zadok]

In message <20071207025504.GA3070@fieldses.org>, "J. Bruce Fields" writes:
> On Thu, Dec 06, 2007 at 09:20:41PM -0500, Erez Zadok wrote:
> > I get a "permission denied" when trying to mount a localhost nfsv2/3
> > exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> > It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> > 
> > # mount -t ext2 /dev/hdb1 /n/lower/b0
> > # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> > # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt
> 
> What do you see if you watch the network traffic in ethereal?
> 
> --b.

Bruce, I'm using nfs-utils-1.0.10-14.fc6 on an FC6 system with all latest
FC6 patches.  Using git-bisect I was able to find the patch which broke it:

commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
Author: Eric W. Biederman <ebiederm@xmission.com>
Date:   Sun Dec 2 00:33:17 2007 +1100

    [NETNS]: Fix /proc/net breakage
    
    Well I clearly goofed when I added the initial network namespace support
    for /proc/net.  Currently things work but there are odd details visible to
    user space, even when we have a single network namespace.
    
    Since we do not cache proc_dir_entry dentries at the moment we can just
    modify ->lookup to return a different directory inode depending on the
    network namespace of the process looking at /proc/net, replacing the
    current technique of using a magic and fragile follow_link method.
    
    To accomplish that this patch:
    - introduces a shadow_proc method to allow different dentries to
      be returned from proc_lookup.
    - Removes the old /proc/net follow_link magic
    - Fixes a weakness in our not caching of proc generic dentries.
    
    As shadow_proc uses a task struct to decided which dentry to return we can
    go back later and fix the proc generic caching without modifying any code
    that uses the shadow_proc method.
    
    Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    Cc: Pavel Machek <pavel@ucw.cz>
    Cc: Pavel Emelyanov <xemul@openvz.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Ingo Molnar <mingo@elte.hu>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

With the above patch, rpc.mountd is unable to open /proc/fs/nfsd/filehandle.
Strace shows:

open("/proc/fs/nfsd/filehandle", O_RDWR|O_LARGEFILE) = -1 ENOENT (No such file or directory)

Without the above patch, /proc/fs/nfsd is populated with a number of files,
including "filehandle".

Erez.

Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[J. Bruce Fields]

On Fri, Dec 07, 2007 at 03:00:13PM -0500, Erez Zadok wrote:
> In message <20071207025504.GA3070@fieldses.org>, "J. Bruce Fields" writes:
> > On Thu, Dec 06, 2007 at 09:20:41PM -0500, Erez Zadok wrote:
> > > I get a "permission denied" when trying to mount a localhost nfsv2/3
> > > exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> > > It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> > > 
> > > # mount -t ext2 /dev/hdb1 /n/lower/b0
> > > # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> > > # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt
> > 
> > What do you see if you watch the network traffic in ethereal?
> > 
> > --b.
> 
> Bruce, I'm using nfs-utils-1.0.10-14.fc6 on an FC6 system with all latest
> FC6 patches.  Using git-bisect I was able to find the patch which broke it:

Wow, thanks for your work finding that.

> 
> commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
> Author: Eric W. Biederman <ebiederm@xmission.com>
> Date:   Sun Dec 2 00:33:17 2007 +1100
> 
>     [NETNS]: Fix /proc/net breakage
>     
>     Well I clearly goofed when I added the initial network namespace support
>     for /proc/net.  Currently things work but there are odd details visible to
>     user space, even when we have a single network namespace.
>     
>     Since we do not cache proc_dir_entry dentries at the moment we can just
>     modify ->lookup to return a different directory inode depending on the
>     network namespace of the process looking at /proc/net, replacing the
>     current technique of using a magic and fragile follow_link method.
>     
>     To accomplish that this patch:
>     - introduces a shadow_proc method to allow different dentries to
>       be returned from proc_lookup.
>     - Removes the old /proc/net follow_link magic
>     - Fixes a weakness in our not caching of proc generic dentries.
>     
>     As shadow_proc uses a task struct to decided which dentry to return we can
>     go back later and fix the proc generic caching without modifying any code
>     that uses the shadow_proc method.
>     
>     Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
>     Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
>     Cc: Pavel Machek <pavel@ucw.cz>
>     Cc: Pavel Emelyanov <xemul@openvz.org>
>     Cc: "David S. Miller" <davem@davemloft.net>
>     Cc: Ingo Molnar <mingo@elte.hu>
>     Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>     Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
> 
> With the above patch, rpc.mountd is unable to open /proc/fs/nfsd/filehandle.
> Strace shows:
> 
> open("/proc/fs/nfsd/filehandle", O_RDWR|O_LARGEFILE) = -1 ENOENT (No such file or directory)
> 
> Without the above patch, /proc/fs/nfsd is populated with a number of files,
> including "filehandle".

Those files are actually in a separate filesystem (of type "nfsd") which
is supposed to be mounted on /proc/fs/nfsd/.   So that mount must have
failed in the bad case?  It's not immediately obvious to me what this
patch has to do with that.  Hm.

--b.

Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Erez Zadok]

In message <20071207200655.GD2204@fieldses.org>, "J. Bruce Fields" writes:
> On Fri, Dec 07, 2007 at 03:00:13PM -0500, Erez Zadok wrote:
[...]
> Those files are actually in a separate filesystem (of type "nfsd") which
> is supposed to be mounted on /proc/fs/nfsd/.   So that mount must have
> failed in the bad case?  It's not immediately obvious to me what this
> patch has to do with that.  Hm.

Yes, it is indeed a separate mount in both cases, but in the broken case,
/proc/fs/nfsd is empty.

The patch in question introduces a proc ->d_revalidate method which does
this:

static int proc_revalidate_dentry(struct dentry *dentry, struct nameidata *nd)
{
	d_drop(dentry);
	return 0;
}

I'm not sure why it drops the dentry and then returns OK to the VFS; is it
to force the VFS to revalidate the dentry?  In that case, I think it should
return -ESTALE.  I also don't know why /proc needs a ->d_revalidate in the
first place (it was fine up until now).  Perhaps what proc does now is
correct, but its behavior has changed such that nfsd's /proc/fs/nfsd needs
to do something different (like grab an extra dentry ref?).

Anyway, if I comment out the d_drop line in proc_revalidate_dentry, or
remove proc's ->d_revalidate method, nfs exporting works again.

Someone more familiar with this patch and /proc should investigate.  Until
then, nfsv2/3 exporting are broken in 2.6.24-rc4.

> --b.

Cheers,
Erez.

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Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Erez Zadok]

In message <20071207200655.GD2204@fieldses.org>, "J. Bruce Fields" writes:
> On Fri, Dec 07, 2007 at 03:00:13PM -0500, Erez Zadok wrote:
[...]
> Those files are actually in a separate filesystem (of type "nfsd") which
> is supposed to be mounted on /proc/fs/nfsd/.   So that mount must have
> failed in the bad case?  It's not immediately obvious to me what this
> patch has to do with that.  Hm.

Yes, it is indeed a separate mount in both cases, but in the broken case,
/proc/fs/nfsd is empty.

The patch in question introduces a proc ->d_revalidate method which does
this:

static int proc_revalidate_dentry(struct dentry *dentry, struct nameidata *nd)
{
	d_drop(dentry);
	return 0;
}

I'm not sure why it drops the dentry and then returns OK to the VFS; is it
to force the VFS to revalidate the dentry?  In that case, I think it should
return -ESTALE.  I also don't know why /proc needs a ->d_revalidate in the
first place (it was fine up until now).  Perhaps what proc does now is
correct, but its behavior has changed such that nfsd's /proc/fs/nfsd needs
to do something different (like grab an extra dentry ref?).

Anyway, if I comment out the d_drop line in proc_revalidate_dentry, or
remove proc's ->d_revalidate method, nfs exporting works again.

Someone more familiar with this patch and /proc should investigate.  Until
then, nfsv2/3 exporting are broken in 2.6.24-rc4.

> --b.

Cheers,
Erez.

Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Valdis.Kletnieks]

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On Fri, 07 Dec 2007 15:06:55 EST, "J. Bruce Fields" said:
> On Fri, Dec 07, 2007 at 03:00:13PM -0500, Erez Zadok wrote:

> > commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
> > Author: Eric W. Biederman <ebiederm@xmission.com>
> > Date:   Sun Dec 2 00:33:17 2007 +1100

> Those files are actually in a separate filesystem (of type "nfsd") which
> is supposed to be mounted on /proc/fs/nfsd/.   So that mount must have
> failed in the bad case?  It's not immediately obvious to me what this
> patch has to do with that.  Hm.

For what it's worth, the startup scripts for 'wine' and 'jexec' fail as well,
and at shutdown, I get complaints about being unable to dismount 
/proc/sys/fs/binfmt_misc. 'strace' says:

open("/proc/sys/fs/binfmt_misc/windows", O_WRONLY|O_CREAT|O_TRUNC, 0666) = -1 EN
OENT (No such file or directory)

# grep binfmt /proc/mounts
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0

I have to wonder if the fact there's 2 of them mounted is related to the
fact that 2 startup scripts tried to touch files under fs/binfmt_misc/ ?


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Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Valdis.Kletnieks]

[-- Attachment #1.1: Type: text/plain, Size: 1099 bytes --]

On Fri, 07 Dec 2007 15:06:55 EST, "J. Bruce Fields" said:
> On Fri, Dec 07, 2007 at 03:00:13PM -0500, Erez Zadok wrote:

> > commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
> > Author: Eric W. Biederman <ebiederm@xmission.com>
> > Date:   Sun Dec 2 00:33:17 2007 +1100

> Those files are actually in a separate filesystem (of type "nfsd") which
> is supposed to be mounted on /proc/fs/nfsd/.   So that mount must have
> failed in the bad case?  It's not immediately obvious to me what this
> patch has to do with that.  Hm.

For what it's worth, the startup scripts for 'wine' and 'jexec' fail as well,
and at shutdown, I get complaints about being unable to dismount 
/proc/sys/fs/binfmt_misc. 'strace' says:

open("/proc/sys/fs/binfmt_misc/windows", O_WRONLY|O_CREAT|O_TRUNC, 0666) = -1 EN
OENT (No such file or directory)

# grep binfmt /proc/mounts
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0

I have to wonder if the fact there's 2 of them mounted is related to the
fact that 2 startup scripts tried to touch files under fs/binfmt_misc/ ?


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Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[J. Bruce Fields]

On Fri, Dec 07, 2007 at 03:00:13PM -0500, Erez Zadok wrote:
> In message <20071207025504.GA3070@fieldses.org>, "J. Bruce Fields" writes:
> > On Thu, Dec 06, 2007 at 09:20:41PM -0500, Erez Zadok wrote:
> > > I get a "permission denied" when trying to mount a localhost nfsv2/3
> > > exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> > > It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> > > 
> > > # mount -t ext2 /dev/hdb1 /n/lower/b0
> > > # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> > > # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt
> > 
> > What do you see if you watch the network traffic in ethereal?
> > 
> > --b.
> 
> Bruce, I'm using nfs-utils-1.0.10-14.fc6 on an FC6 system with all latest
> FC6 patches.  Using git-bisect I was able to find the patch which broke it:

Wow, thanks for your work finding that.

> 
> commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
> Author: Eric W. Biederman <ebiederm@xmission.com>
> Date:   Sun Dec 2 00:33:17 2007 +1100
> 
>     [NETNS]: Fix /proc/net breakage
>     
>     Well I clearly goofed when I added the initial network namespace support
>     for /proc/net.  Currently things work but there are odd details visible to
>     user space, even when we have a single network namespace.
>     
>     Since we do not cache proc_dir_entry dentries at the moment we can just
>     modify ->lookup to return a different directory inode depending on the
>     network namespace of the process looking at /proc/net, replacing the
>     current technique of using a magic and fragile follow_link method.
>     
>     To accomplish that this patch:
>     - introduces a shadow_proc method to allow different dentries to
>       be returned from proc_lookup.
>     - Removes the old /proc/net follow_link magic
>     - Fixes a weakness in our not caching of proc generic dentries.
>     
>     As shadow_proc uses a task struct to decided which dentry to return we can
>     go back later and fix the proc generic caching without modifying any code
>     that uses the shadow_proc method.
>     
>     Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
>     Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
>     Cc: Pavel Machek <pavel@ucw.cz>
>     Cc: Pavel Emelyanov <xemul@openvz.org>
>     Cc: "David S. Miller" <davem@davemloft.net>
>     Cc: Ingo Molnar <mingo@elte.hu>
>     Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>     Signed-off-by: Herbert Xu <herbert-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org>
> 
> With the above patch, rpc.mountd is unable to open /proc/fs/nfsd/filehandle.
> Strace shows:
> 
> open("/proc/fs/nfsd/filehandle", O_RDWR|O_LARGEFILE) = -1 ENOENT (No such file or directory)
> 
> Without the above patch, /proc/fs/nfsd is populated with a number of files,
> including "filehandle".

Those files are actually in a separate filesystem (of type "nfsd") which
is supposed to be mounted on /proc/fs/nfsd/.   So that mount must have
failed in the bad case?  It's not immediately obvious to me what this
patch has to do with that.  Hm.

--b.

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Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Erez Zadok]

In message <20071207025504.GA3070@fieldses.org>, "J. Bruce Fields" writes:
> On Thu, Dec 06, 2007 at 09:20:41PM -0500, Erez Zadok wrote:
> > I get a "permission denied" when trying to mount a localhost nfsv2/3
> > exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> > It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> > 
> > # mount -t ext2 /dev/hdb1 /n/lower/b0
> > # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> > # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt
> 
> What do you see if you watch the network traffic in ethereal?
> 
> --b.

Bruce, I'm using nfs-utils-1.0.10-14.fc6 on an FC6 system with all latest
FC6 patches.  Using git-bisect I was able to find the patch which broke it:

commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
Author: Eric W. Biederman <ebiederm@xmission.com>
Date:   Sun Dec 2 00:33:17 2007 +1100

    [NETNS]: Fix /proc/net breakage
    
    Well I clearly goofed when I added the initial network namespace support
    for /proc/net.  Currently things work but there are odd details visible to
    user space, even when we have a single network namespace.
    
    Since we do not cache proc_dir_entry dentries at the moment we can just
    modify ->lookup to return a different directory inode depending on the
    network namespace of the process looking at /proc/net, replacing the
    current technique of using a magic and fragile follow_link method.
    
    To accomplish that this patch:
    - introduces a shadow_proc method to allow different dentries to
      be returned from proc_lookup.
    - Removes the old /proc/net follow_link magic
    - Fixes a weakness in our not caching of proc generic dentries.
    
    As shadow_proc uses a task struct to decided which dentry to return we can
    go back later and fix the proc generic caching without modifying any code
    that uses the shadow_proc method.
    
    Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    Cc: Pavel Machek <pavel@ucw.cz>
    Cc: Pavel Emelyanov <xemul@openvz.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Ingo Molnar <mingo@elte.hu>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

With the above patch, rpc.mountd is unable to open /proc/fs/nfsd/filehandle.
Strace shows:

open("/proc/fs/nfsd/filehandle", O_RDWR|O_LARGEFILE) = -1 ENOENT (No such file or directory)

Without the above patch, /proc/fs/nfsd is populated with a number of files,
including "filehandle".

Erez.

Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Erez Zadok]

In message <20071207025504.GA3070@fieldses.org>, "J. Bruce Fields" writes:
> On Thu, Dec 06, 2007 at 09:20:41PM -0500, Erez Zadok wrote:
> > I get a "permission denied" when trying to mount a localhost nfsv2/3
> > exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> > It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> > 
> > # mount -t ext2 /dev/hdb1 /n/lower/b0
> > # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> > # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt
> 
> What do you see if you watch the network traffic in ethereal?
> 
> --b.

Bruce, I'm using nfs-utils-1.0.10-14.fc6 on an FC6 system with all latest
FC6 patches.  Using git-bisect I was able to find the patch which broke it:

commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
Author: Eric W. Biederman <ebiederm@xmission.com>
Date:   Sun Dec 2 00:33:17 2007 +1100

    [NETNS]: Fix /proc/net breakage
    
    Well I clearly goofed when I added the initial network namespace support
    for /proc/net.  Currently things work but there are odd details visible to
    user space, even when we have a single network namespace.
    
    Since we do not cache proc_dir_entry dentries at the moment we can just
    modify ->lookup to return a different directory inode depending on the
    network namespace of the process looking at /proc/net, replacing the
    current technique of using a magic and fragile follow_link method.
    
    To accomplish that this patch:
    - introduces a shadow_proc method to allow different dentries to
      be returned from proc_lookup.
    - Removes the old /proc/net follow_link magic
    - Fixes a weakness in our not caching of proc generic dentries.
    
    As shadow_proc uses a task struct to decided which dentry to return we can
    go back later and fix the proc generic caching without modifying any code
    that uses the shadow_proc method.
    
    Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    Cc: Pavel Machek <pavel@ucw.cz>
    Cc: Pavel Emelyanov <xemul@openvz.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Ingo Molnar <mingo@elte.hu>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Herbert Xu <herbert-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org>

With the above patch, rpc.mountd is unable to open /proc/fs/nfsd/filehandle.
Strace shows:

open("/proc/fs/nfsd/filehandle", O_RDWR|O_LARGEFILE) = -1 ENOENT (No such file or directory)

Without the above patch, /proc/fs/nfsd is populated with a number of files,
including "filehandle".

Erez.

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Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[J. Bruce Fields]

On Thu, Dec 06, 2007 at 09:20:41PM -0500, Erez Zadok wrote:
> I get a "permission denied" when trying to mount a localhost nfsv2/3
> exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> 
> # mount -t ext2 /dev/hdb1 /n/lower/b0
> # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt

What do you see if you watch the network traffic in ethereal?

--b.

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[NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Erez Zadok]

I get a "permission denied" when trying to mount a localhost nfsv2/3
exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:

# mount -t ext2 /dev/hdb1 /n/lower/b0
# exportfs -o no_root_squash,rw localhost:/n/lower/b0
# mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt

Erez.

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Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[Mikael Pettersson]

On Thu, 6 Dec 2007 21:20:41 -0500, Erez Zadok wrote:
> I get a "permission denied" when trying to mount a localhost nfsv2/3
> exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> 
> # mount -t ext2 /dev/hdb1 /n/lower/b0
> # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt

I'm seeing something similar too. NFSv3 export of an ext3 partition
to another machine in my lan fails (client gets permission denied)
when the server runs 2.6.24-rc4. It worked fine in 2.6.24-rc3.

There's no NFSv4 of any kind on either client or server.

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Re: [NFS] NFSv2/3 broken exporting/mounting (permission denied) in 2.6.24-rc4

[J. Bruce Fields]

On Fri, Dec 07, 2007 at 11:54:38AM +0100, Mikael Pettersson wrote:
> On Thu, 6 Dec 2007 21:20:41 -0500, Erez Zadok wrote:
> > I get a "permission denied" when trying to mount a localhost nfsv2/3
> > exported volume, on v2.6.24-rc4-124-gf194d13.  It works w/ nfsv4 mounting.
> > It worked fine in 2.6.24-rc3.  Here's a sequence of ops I tried:
> > 
> > # mount -t ext2 /dev/hdb1 /n/lower/b0
> > # exportfs -o no_root_squash,rw localhost:/n/lower/b0
> > # mount -t nfs -o nfsvers=3 localhost:/n/lower/b0 /mnt
> 
> I'm seeing something similar too. NFSv3 export of an ext3 partition
> to another machine in my lan fails (client gets permission denied)
> when the server runs 2.6.24-rc4. It worked fine in 2.6.24-rc3.
> 
> There's no NFSv4 of any kind on either client or server.

And you're not varying the client at all, you're only changing the
kernel version on the server?

There are literally no commits between v2.6.24-rc3 and v2.6.24-rc4 which
touch fs/nfsd/.  What filesystem are you exporting?  Are the nfs-utils
versions the same in both cases?

Also, could you get a network trace showing the failure?

--b.

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