Date: Mon, 26 Feb 2001 15:18:29 -0700 From: Lyndon Nerenberg <lyndon@orthanc.ab.ca> To: seebs@plethora.net (Peter Seebach) Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Is mkdir guaranteed to be 'atomic' ?? Message-ID: <200102262218.f1QMITq95167@orthanc.ab.ca> In-Reply-To: Your message of "Mon, 26 Feb 2001 16:01:28 CST." <200102262201.f1QM1S620699@guild.plethora.net>
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>>>>> "Peter" == Peter Seebach <seebs@plethora.net> writes:
Peter> Well, imagine a hypothetical broken system in which two
Peter> simultaneous calls to mkdir, on some hypothetical broken
Peter> filesystem, can each think that it "succeeded". After all,
Peter> at the end of the operation, the directory has been
Peter> created, so who's to say they're wrong? ;)
"They" are :-) What if the two processes issuing mkdir() have a
different effective [ug]id or umask? I.e. if I get success back I'm
going to assume I own the directory, which has a 1/n chance of being
wrong for for n processes with unique uids racing a non-atomic mkdir()
call over (say) NFS.
--lyndon
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