Messages in this thread | | | From | jlnance@unity ... | Date | Sun, 18 May 2003 20:53:16 -0400 | Subject | Re: NFS problems with Linux-2.4 |
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On Sun, May 18, 2003 at 05:00:24PM +0200, Trond Myklebust wrote: > > Sorry. stat doesn't obey close-to-open. It relies on standard > attribute caching. close-to-open means "open()" (and only "open()") > checks data cache consistency...
Trond, Thanks for the info. Here is a section of the man page for open. Is the information it gives correct wrt using link & stat?
O_EXCL When used with O_CREAT, if the file already exists it is an error and the open will fail. In this con text, a symbolic link exists, regardless of where its points to. O_EXCL is broken on NFS file sys tems, programs which rely on it for performing locking tasks will contain a race condition. The solution for performing atomic file locking using a lockfile is to create a unique file on the same fs (e.g., incorporating hostname and pid), use link(2) to make a link to the lockfile. If link() returns 0, the lock is successful. Otherwise, use stat(2) on the unique file to check if its link count has increased to 2, in which case the lock is also suc cessful.
Thanks,
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