[Pvfs2-developers] Re: setting xattrs on pvfs2 root

[Sam Lang]

On Jun 28, 2007, at 1:30 PM, Murali Vilayannur wrote:

> Hi Sam,
> You mean remove it for good from the code, right?
> A chmod -t does not do the trick. We explicitly reset it internally  
> sadly :(

That's only on mount though, right?  Could we remove the sticky bit  
while mounted so that extended attributes can be added?  The kernel  
doesn't check if xattrs already exist on a root dir when the file is  
mounted, does it?

For the sticky bit thing -- could we set something on the server  
maintaining the root dir to specify whether to add the sticky bit  
when we mount?  The config file could have a sticky bit enable/ 
disable option.

-sam

> I will send out a patch to do this trick *if* folks are willing to
> live with no top-level
> files or dirs...
> Murali
>
> On 6/28/07, Sam Lang <slang at mcs.anl.gov> wrote:
>>
>> Hi Murali,
>>
>> Can't we just have people remove the sticky bit so they can set  
>> xattrs?
>>
>> -sam
>>
>> On Jun 28, 2007, at 12:37 PM, Murali Vilayannur wrote:
>>
>> > Phil,
>> > Umm.. The problem is that we mark the root directory as sticky  
>> so that
>> > users can create files/directories at the top level instead of  
>> having
>> > admins create directories owned by a user under top level. The  
>> kernel
>> > does not allow setxattr on inodes marked sticky..
>> >
>> > if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
>> >                if (!S_ISREG(inode->i_mode) &&
>> >                    (!S_ISDIR(inode->i_mode) || inode->i_mode &
>> > S_ISVTX)) <--
>> >                        return -EPERM;
>> >        }
>> > Thats why we don't even have a chance to subvirt those checks..
>> > What do you guys suggest? Shall we step back and make the root
>> > directory non-sticky by default? That way admins will need to
>> > explicitly create user directories etc and chown them.
>> > I think a rerun of ltp may also be required if we do this change.
>> > comments?
>> > Murali
>> >
>> > On 6/28/07, Phil Carns <pcarns at wastedcycles.org> wrote:
>> >> This is with 2.6 (both very recent and relatively old  
>> version).  Many
>> >> thanks for looking at it.
>> >>
>> >> -Phil
>> >>
>> >> Murali Vilayannur wrote:
>> >> > hi Phil,
>> >> > Are you using 2.4. kernel versions? or 2.6?
>> >> > If xattrs dont work, ACLs also won't work.
>> >> > I will dig into this and let you know what I find out..
>> >> > thanks,
>> >> > Murali
>> >> >
>> >> > On 6/28/07, Phil Carns <pcarns at wastedcycles.org> wrote:
>> >> >> I am interested in this because it would be nice to be able  
>> to set
>> >> >> tuning options at the root directory level without modifying
>> >> the server
>> >> >> side configuration files.  I also wonder if this issue would  
>> cause
>> >> >> problems for ACLs on the root directory.
>> >> >>
>> >> >> -Phil
>> >> >>
>> >> >> Murali Vilayannur wrote:
>> >> >> > Hey Phil,
>> >> >> > Sorry I forgot to get back to you on this..
>> >> >> > No I don't think this would work.
>> >> >> > It is a kernel module issue that I hadnt tracked down fully..
>> >> >> > Do you need this feature?
>> >> >> > thanks,
>> >> >> > Murali
>> >> >> >
>> >> >> > On 6/27/07, Phil Carns <pcarns at wastedcycles.org> wrote:
>> >> >> >> Just pinging on this one again- has any one else bumped into
>> >> this
>> >> >> >> problem?
>> >> >> >>
>> >> >> >> -Phil
>> >> >> >>
>> >> >> >> Phil Carns wrote:
>> >> >> >> > It looks like pvfs2 does not allow you to set xattrs on
>> >> the root
>> >> >> >> > directory.  Is this expected?
>> >> >> >> >
>> >> >> >> > # checking the mount options:
>> >> >> >> >
>> >> >> >> >  > mount -t pvfs2
>> >> >> >> > tcp://localhost:3334/pvfs2-fs on /mnt/pvfs2 type pvfs2
>> >> >> (rw,user_xattr)
>> >> >> >> >
>> >> >> >> > # confirming that xattrs can be set on a normal directory:
>> >> >> >> >
>> >> >> >> >  > setfattr -n user.pvfs2.num_dfiles -v "1" /mnt/pvfs2/ 
>> dir1
>> >> >> >> >  > getfattr -n user.pvfs2.num_dfiles /mnt/pvfs2/dir1
>> >> >> >> > getfattr: Removing leading '/' from absolute path names
>> >> >> >> > # file: mnt/pvfs2/dir1
>> >> >> >> > user.pvfs2.num_dfiles="1"
>> >> >> >> >
>> >> >> >> > # trying to set xattrs on the root directory:
>> >> >> >> >
>> >> >> >> >  > setfattr -n user.pvfs2.num_dfiles -v "1" /mnt/pvfs2
>> >> >> >> > setfattr: /mnt/pvfs2: Operation not permitted
>> >> >> >> >  > getfattr -n user.pvfs2.num_dfiles /mnt/pvfs2
>> >> >> >> > /mnt/pvfs2: user.pvfs2.num_dfiles: No such attribute
>> >> >> >> >
>> >> >> >> > All of the above is run as root.  I don't think it is
>> >> anything
>> >> >> special
>> >> >> >> > about the num_dfiles attribute either; it looks like I
>> >> can't set any
>> >> >> >> > xattrs on the root directory.  It always responds with
>> >> "Operation
>> >> >> not
>> >> >> >> > permitted".
>> >> >> >> >
>> >> >> >> > -Phil
>> >> >> >> >
>> >> >> >>
>> >> >> >> _______________________________________________
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>> >> developers
>> >> >> >>
>> >> >>
>> >> >>
>> >>
>> >>
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