Max. number of subdirectories dump

[Manuel Wiesinger <manuel%bsdstammtisch.at@localhost>]

Hello,

I am working on a defrag tool for UFS2/FFSv2 as Google Summer of Code 
Project.

The size of a directory offset is of type int32_t (see 
src/sys/ufs/ufs/dir.h), which is a signed integer. So the maximum size 
can be (2^31)-1.

When testing, the maximum number of subdirectories was 32767, which is 
(2^15)-1, when trying to add a 32767th directory, I got the error 
message: "Too many links".
When my tools reads only the single indirect blocks, it get all 32767 
subdirectories.

In some Oracle documentation[1] of UFS2 says, this is the defined 
maximum of subdirectories. But this is another implementation.

When studying the sourcecode of dump(8), I found out that in traverse.c 
there is a function dirindir(), which iterates recursively through all 
indirect blocks of directories, even through triple indirect blocks.

My question is:
Is the number of subdirectories really limited by (2^15)-1?
If, yes why does dump iterate the indirect blocks, when looking for 
subdirectories?

Thanks,
Manuel

[1] 
http://docs.oracle.com/cd/E18752_01/html/817-5093/fsfilesysappx-20581.html#fsfilesysappx-5