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SubjectRe: [RFC] st_nlink after rmdir() and rename()
On Thu, Mar 3, 2011 at 12:46 PM, OGAWA Hirofumi
<> wrote:
> But, some commands see i_nlink (IIRC, it's checking i_nlink == 2, to
> know empty dir or not).

Actually, that would be a serious bug in the application.

The traditional rule of thumb is that a directory with i_nlink==1 has
a "I'm not counting at all".

For example, I think that's the rule that 'find' uses to decide if a
directory can have subdirectories (and when it could try to stop
scanning early): i_nlink == 1 means that yes, it _can_ have
subdirectories, we just don't know how many.

So checking i_nlink==2 is actually a user-level bug.

> So we have to simulate some levels. I guess you
> are not saying we don't need to care it at all though.

I'm saying that it should just work to set i_nlink=1 and not do
anything at all. Ever. It's a valid model for directory counts.

Seriously - that's what isofs does, for example. It does mean that
'find' for certain cases gets bit more expensive, but on the other
hand, other operations are a lot _less_ expensive.

We might well try that as a FAT mount option, to let people decide
whether they really do want the "scan directories all the time" or
only the "let 'find' scan directories when it needs to" behavior.


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