Re: Question on how file tails are stored

[Edward Shishkin <edward.shishkin@gmail.com>]

Bo Brantén wrote:
>
> Hello,

Hello.

>
> I would like to ask you how file tails are stored on ReiserFs 3.6, am
> I right that they are stored as either one or two items but not more
> than two?

Yes, if you mean (default) "small" tail suppression policy.

Indeed, a data flow of size < blocksize can not be
split into more then 2 chunks, if you partition it by a lattice
which has a step == blocksize. 

>
> Also I found this statement on the Internet:
>
> "If a tail is larger than the maximum size of a file that can fit into
> a formatted node but is smaller than the unformatted node size (4K),
> then it is stored in an unformatted node, 

Right.
It fits perfectly the "small" policy .


> and a pointer to it plus a count of the space used is stored in an
> indirect item."

This looks like some not related calculation..

>
> Does this represent a third case not covered of what I said above, and
> if so how does one detect this case and find the tail data?

There is no special interfaces to access tail data.
You can try to parse debugreiserfs -d output..

Thanks,
Edward.
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