[Ocfs2-tools-devel] [PATCH 6/7] tunefs.ocfs2: Turn on and off the extended slot map

[Joel Becker]

On Fri, Jan 11, 2008 at 09:51:39AM +0800, tao.ma wrote:
> You patch does touch increasing slot.
> Although current ocfs2_extend_slot is only 8 bytes and the minimum  
> cluster size is 4K and 8 * 255 << 4k, do you think we have any future  
> improvement in future which will exceed the limit? ;)
> Maybe a call of ocfs2_format_slot_map is needed for increasing slot?

	Let's see if I'm reading this right.  The current add_slot()
code ignores the slotmap, because it assumes the slotmap is fully
formatted and always big enough to hold 255 noes (the max for o2nm).
	With the new format, we do intend to allow an arbitrary number
of slots (even though we all know >255 nodes is hard to make work in
practice).  Thus, adding slots could grow beyond 4K - never mind a 1K
blocksize.  So I do need to do something at add_slot() time.  It should
be something as trivial as format_slotmap().  This will do nothing if
the slotmap is already big enough.
	Do we support online adding of slots?  If so, that needs to be
handled as well.

Joel

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Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127