Re: Problem report: cannot run nilfs_cleanerd on full filesystem

[Reinoud Zandijk <reinoud-qavaossjCcEdnm+yROfE0A@public.gmane.org>]

On Mon, Mar 21, 2011 at 08:07:06PM +0900, Ryusuke Konishi wrote:
> > So IMHO the .nilfs file is a hack in itself :-D
> 
> The ".nilfs" file is used for two purposes:
> 
>  1) As the file on which the nilfs library issues ioctls.
> 
>  2) For advisory locks (i.e. fcntl(F_GETLK/F_SETLK/FSETLKW)).  This
>     works as a mutex between the cleaner and other nilfs-tools.
> 
> Note that the nilfs2 kernel code never uses the .nilfs file; it's just
> a regular file for nilfs2.
> 
> As for the item (1), we can use the root directory of each filesystem
> instead.  And for (2), a Posix semaphore or other lock primitives may
> be available.

In NetBSD this is normally resolved by looking up the device the directory is
residing and then opening/locking the device file etc. I think this is a
better way of operating!

It also doesn't allow two cleanerds to be started on one device; otherwise one
could be started on the head and the other on a snapshot, or not?

With regards,
Reinoud

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