Hi, the open(2) man page says:
O_EXCL When used with O_CREAT, if the file already exists
it is an error and the open will fail. O_EXCL is
broken on NFS file systems, 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. Oth
erwise, use stat(2) on the unique file to check if
its link count has increased to 2, in which case
the lock is also successful.
I coded this up and tried it here on a cluster of different operating
systems (Linux 2.4.5 server, linux, freebsd, solaris, aix, hpux, irix
clients) and it doesn't work.
2 questions:
a) is it the belief of folks here that this should work?
b) if performance isn't a big issue, is there any portable way to do
locking over NFS with just files?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Mon Oct 15 2001 - 21:00:55 EST