Re: Max. number of subdirectories dump

[Johnny Billquist <bqt%softjar.se@localhost>]

On 2013-08-18 15:08, Manuel Wiesinger wrote:
> 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?

As Joerg said, the link count is the limitation here.

> If, yes why does dump iterate the indirect blocks, when looking for
> subdirectories?

Not sure I understand the question. Are you suggesting that you don't 
need to scan through all the contents of a directory to find the 
subdirectories?

        Johnny

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Johnny Billquist                  || "I'm on a bus
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