  | |  | flock() over NFS | flock() over NFS 2004-12-03 - By Brian Long
Back Has anyone else experienced difficulty with applications that expect flock() to work over NFS? We have various build environments built around NFS and ClearCase. Many makefiles use a flock program which calls flock() and works over NFS on all distributions except RHEL 3 (works on Debian Sarge, FC3, RHEL 4 beta, RH 7.1, 7.3, Suse 9.2).
The developers are not trying to lock a single file for multiple machines over NFS. They're just trying to lock the file knowing the file will only be accessed by the one machine, but it happens to be over NFS.
The flock() man pages says flock doesn't work over NFS (even RH 7.1 man page says this, but it returns success anyways). We understand it shouldn't work with multiple clients trying to lock or check status for the lock on a single file, but what about a single client running a make -j8 over NFS? Why is flock() only broken in RHEL 3?
When we opened a case with IBM GS which back-lined to Red Hat Level 3, they said it was working as documented and they wouldn't fix it. I'm trying to understand why it's only affecting us on the RHEL 3 platform.
FYI, if we mount the NFS filesystem with -nolock, this gets around the behaviour, but it also opens up the posibility of problems for programs using fcntl(). Any ideas on how to resolve this would be appreciated!
/Brian/ -- Brian Long | | | IT Data Center Systems | .|||. .|||. Cisco Linux Developer | ..:|||||||:...:|||||||:.. Phone: (919) 392-7363 | C i s c o S y s t e m s
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