unionfs & kqueue?

[Ivan Voras]

Karsten Behrmann wrote:
> Heya,
> 
>> Does unionfs work with kqueue? When I run `tail -f` on a file residing
>> on unionfs with cd9660 underneeth and md+ufs over it, it doesn't detect
>> changes. The changes are immediately visible, just not with tail -f.
> 
> Hmm. When you start the tail -f, does the file reside on the cd9660 or
> already on the md?

The file resides entirely in the upper layer, in the md.

> See if tail -F does a better job.

Will do.

> My guess would be that, since you cannot modify a file on any filesystem
> except the top one, unionfs must change semantics of open so that even
> opening for writing or appending silently creates a new copy of the file
> on the top filesystem (if the file didn't reside there already).

Yes, AFAIK it does that.

> As tail -f still has the lower-layer file open,
> it never notices that there's a new file by the name.

Not in my case - there's no such lower-layer file.


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