nullfs and named pipes.

[Eric Anderson]

On 02/03/07 20:37, Josef Karthauser wrote:
> Hey guys, does anyone know off the top of their heads why named pipes
> don't appear to work across null_fs mounted partitions?  i.e. if I have
> a named pipe in a file system,
> 
>     # ls -ld /mysql/mysql.sock 
>     srwxrwxrwx  1 mysql  wheel  0 Feb  3 19:01 /mysql/mysql.sock
> 
>     # mysql --socket=/mysql/mysql.sock
>     Welcome to the MySQL monitor.  Commands end with ; or \g.
>     Your MySQL connection id is 6
>     Server version: 5.0.33-log FreeBSD port: mysql-server-5.0.33
> 
>     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
> 
>     mysql> 
> 
> However if I make this available elsewhere via a null_fs mount:
> 
>     # mkdir /foo
>     # mount_nullfs /mysql /foo
>     # ls -ld /foo/mysql.sock 
>     srwxrwxrwx  1 mysql  wheel  0 Feb  3 19:01 /foo/mysql.sock
> 
>     # mysql --socket=/foo/mysql.sock -p
>     Enter password: 
>     ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/foo/mysql.sock' (61)
> 
> the socket stops working.
> 
> However a hardlink to the socket works:
> 
>     # umount /foo
>     # ln /mysql/mysql.sock /foo/mysql.sock
> 
>     # mysql --socket=/foo/mysql.sock
>     Welcome to the MySQL monitor.  Commands end with ; or \g.
>     Your MySQL connection id is 10
>     Server version: 5.0.33-log FreeBSD port: mysql-server-5.0.33
> 
>     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
> 
> Is this a fundamental design issue with null_fs or a bug?
> 
> There appears to be a lot of confusion on the lists about this point
> as many people are trying to do this so as to make a single mysql
> server available from within a number of jails, for instance.  However
> people appear to think that this is a limitation of the jail code, not a
> limitation of the null_fs code.  Having named pipes work in null_fs
> filesystems would be a very handy thing indeed.
> 
> I'd appreciate any insights into this.

Just wanted to say that it seems like this should work, and I'm not yet 
certain why it doesn't.  I've looked into it a bit, but my time is very 
limited, so I doubt I'll be able to put much more into it..

Eric