On Mon, 2010-09-06 at 18:03 +0530, Suresh Jayaraman wrote: > NFS clients since 2.6.12 support flock()locks by emulating the > BSD-style locks in terms of POSIX byte range locks. So the NFS client > does not allow to lock the same file using both flock() and fcntl > byte-range locks. > > For some Windows applications which seem to use both share mode locks > (flock()) and fcntl byte range locks sequentially on the same file, > the locking is failing as the lock has already been acquired. i.e. the > flock mapped as posix locks collide with actual byte range locks from > the same process. The problem was observed on a setup with Windows > clients accessing Excel files on a Samba exported share which is > originally a NFS mount from a NetApp filer. Since kernels < 2.6.12 does > not support flock, what was working (as flock locks were local) in > older kernels is not working with newer kernels. > > This could be seen as a bug in the implementation of the windows > application or a NFS client regression, but that is debatable. > In the spirit of not breaking existing setups, this patch adds mount > options "flock=local" that enables older flock behavior and > "flock=fcntl" that allows the current flock behavior. So instead of having a special option for flock only, what say we rather introduce an option of the form -olocal_lock= which can take the values 'none', 'flock', 'fcntl' (or 'posix'?) and 'all'? Cheers Trond -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
