Re: New filesystem for Linux

[Jörn Engel <joern@wohnheim.fh-wedel.de>]

On Fri, 3 November 2006 14:31:46 +0100, Mikulas Patocka wrote:
> 
> Really it can batch any number of modifications into one transaction 
> (unless fsync or sync is called). Transaction is closed only on 
> fsync/sync, if 2 minutes pass (can be adjusted) or when the disk runs out 
> of space.

Interesting.  Let me pick an example and see where we're going from
there.  You have four directories, A, B, C and D, none of which is the
parent of another.  Two cross-directory renames happen:
$ mv A/foo B/
$ mv C/bar D/

This will cause four modifications, one to each of the directories.  I
would have assumed that the modifications to A and B receive one
transaction number n, C and D get a different one, n+1 if nothing else
is going on in between.

To commit the first rename, n is written into cct[entry->cc].  To
commit both, n+1 is written instead.  Committing the second
transaction without committing the first is not possible.

Now clearly we are disagreeing, so I must have misunderstood your
design somehow.  Can you see how?

Jörn

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