Two reasons: (1) identifying cross-volume ("cross-device" equivalent) links
is harder, or at least more expensive, and (2) directory ACLs complicate
things a bit more than Unix directory permissions do. ((2) isn't considered
much of a problem any more, given that it's now available (and hence a
potential problem) in various Unixes (i.e. Solaris [gs]etfacl) and it
doesn't cause problems in practice.)
Add that a VFS check for "ownership" is fairly useless on Coda and AFS,
because the "owner" is a chimera provided to make Unix happy and may not
have any relationship to the file's real owner --- and indeed, the
AFS/DFS/Coda user ID may have no relationship to the Unix/Linux user ID when
the file is created or manipulated, so with your proposed change it's
trivial for me to get into a situation where I am forbidden to access my own
files. (VFS checks for "group" are even more worthless.) So you are not
only breaking Unix semantics, you're introducing the potential to
incorrectly deny me access to my files.
--
brandon s. allbery os/2,linux,solaris,perl allbery@kf8nh.apk.net
system administrator kthkrb,heimdal,gnome,rt allbery@ece.cmu.edu
carnegie mellon / electrical and computer engineering kf8nh
We are Linux. Resistance is an indication that you missed the point.
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