tmpfs: make: Cannot open `.' (Permission denied)

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

I'm running a pbulk build completely inside a tmpfs sandbox (i.e. set
up sandbox, copy/null-mount some files inside, start bulk build).

Since yesterday's update to 5.99.20/amd64, I saw the following
phenomenon twice already:
At some point in the bulk build, configure steps start failing all
over, i.e. all remaining packages don't succeed in their configure
step. The error I get is (in configure.log):
        make: Cannot open `.' (Permission denied)

The permissions of the object(scratch)space look fine when the bulk
build is finished, and when I empty the meta/error file and restart
the build, the first few hundred packages usually compile fine, even
if they failed before.

Any ideas?

My last state before that was from 20090922, and I saw only one
tmpfs-related commit in the meantime:

Modified Files:
        src/sys/fs/tmpfs: tmpfs_vnops.c

Log Message:
tmpfs_rename: handle hard-links correctly.  Fixes PR/41236.

To generate a diff of this commit:
cvs rdiff -u -r1.62 -r1.63 src/sys/fs/tmpfs/tmpfs_vnops.c

No idea if that's related.

ISTR that I had seen this one before, but I'm not sure; and definitely
not as reproducable as this time.
 Thomas