How 'honest' is fstat(1)?
Mikhail Teterin
mi+mx at aldan.algebra.com
Fri Mar 24 21:47:17 UTC 2006
Hello!
As a policy I try to keep my /, /usr, and other filesystems (except /var
and /home) mounted readonly. (Not so much for security as for safety.)
When I need to make a modification, I remount them:
mount -orw -u /
make the change, and remount back:
mount -oro -u /usr/local
This works for "small" changes, but sometimes, however, after a bigger on
(such as rebuilding of some ports), the last step fails with "busy".
At this time nothing should have a file open, and nothing does according to
fstat. The command:
fstat | awk '$5 == "/usr/local" && $NF != "r"'
does not list anything. Yet, the fs (in this case -- /usr/local) will not
remount readonly.
My only guess is, the earlier versions of the just reinstalled executables are
still running and that trigger's the rarely noticed bug.
Any other guesses? Thanks!
-mi
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