Mysterious block count (reproducible)

[Oliver Fromme]

Bernd Walter wrote:
 > Oliver Fromme wrote:
 > > [...]
 > > $ BLOCKSIZE=16K ls -s foo
 > >  15 foo
 > > # fsdb -r /dev/md0
 > > [...]
 > >    fsdb (inum: 5)> blocks
 > >    Blocks for inode 5:
 > >    Direct blocks:
 > >    2136, 2144, 2152, 2160, 2168, 2176, 2184, 2192, 2248, 2256, 2264, 2272
 > >    Indirect blocks:
 > >    2280, 2288,
 > >    fsdb (inum: 5)> 
 > > 
 > > It lists 12 direct blocks and 2 indirect blocks, that's
 > > still 14 blocks, not 15.
 > > 
 > > Where did the 15th block go?!?  Or is there a bug in
 > > the calculation of ls -s output?

(Meanwhile I found out that ls(1) doesn't really calculate
anything; it simply displays the st_blocks value from the
stat structure rounded to $BLOCKSIZE, of course.)

 > Don't forget the block needed for the indirect table.
 > fsdb only shows data blocks it seems.

Oh, OK ...  I really assumed that fsdb would display them
as soon as they come into play.  :-(

What I'm trying to do is to write a small script that
calculates the allocation vs. virtual size ratio of
sparse files.  For that purpose I have to find out how
many blocks a file would require if it wasn't sparse.
Is there are an easy way to get that information?

I have currently hardcoded some information in the
script, but it's an ugly hack:

http://www.secnetix.de/~olli/scripts/sparsecheck

Best regards
   Oliver

-- 
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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