JFFS3 & deletion dirents RFC

Artem B. Bityuckiy dedekind at infradead.org
Thu Mar 24 04:18:22 EST 2005


Jared Hulbert wrote:
> Forgive me if my ignorance is obvious...
> Are there any implications to non-dirent nodes?
No, in data nodes versions play another and very important role. 
Basically, they help to distinguish between valid and obsolete data when 
the data nodes' data ranges overlap.

> Shouldn't this speed
> up the GC, mount time for any node?  If not then the version field for
> non-dirent nodes is utterly wasted, right?  If the version field is
> wasted for all non-dirent nodes (in other words, most nodes) then it
> seems like a bad idea to add a WORD or DWORD to each node. If there is
> a way to make version field only apply to dirent nodes then it would
> be much better, of course that sounds ugly without even thinking it
> through too far.

We can't get rid of version in data nodes.

Example:

data node A has data that covers file's range 0-100
data node B has data that covers file's range 10-110

How can we detect from which node should we fetch data of the 10-100 
range? JFFS2 uses version for this reason.

Dirents' versions play another role.

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.




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