On 2/18/07, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
On Sat, Feb 17, 2007 at 12:32:42AM -0500, Wendy Cheng wrote:
> Robert Rappaport wrote:
>
> >[snip]
> >.... This is because the vfs running on the same node where the
> >samba server is running is not necessarily aware of all accesses to
> >the file on which it is granting a lease. Since vfs does not
> >currently inform file systems about the granting and rescinding of
> >leases, a clustered file system cannot allow a samba server to support
> >OpLocks on its files and this has a negative impact on performance.
> >
> >What I think is needed is to add a file systems defined
> >file_operations function, that would be invoked when vfs is
> >considering the granting of a lease on a file associated with an
> >inode. Such an enhancement would allow a file system to be come aware
> >of vfs lease activity and allow it to support this activity.
> >
> NFS has similar issues because Linux NLM-VFS does not invoke server side
> filesystem specific lock method. This implies NFS client applications is
> not able to use posix locks to coordinate file access across different
> nodes with a cluster filesystem, even the cluster filesystem itself
> does support posix locking.
We also have the same problem with leases, since we're using leases to
implement NFSv4 delegations. There's a simple-minded patch here:
http://linux-nfs.org/cgi-bin/gitweb.cgi?p=bfields-2.6.git;a=commitdiff;h=4e8aff5dabe07b2e4e95ef0c741a34f65409087f
I'm not really sure if it's right.
--b.
Thank you both for your helpful replies. In particular, the addition
of the calls to file system specific functions in routines,
fcntl_setlease() and break_lease(), as well as the modifications to
the file_operations and inode_operations structures, pointed to by
Bruce's reply, look exactly like the hooks that I would need to
proceed to resolve my problems. Is there any timetable established
for these modifications to make it into a future release? These hooks
would clearly benefit any cluster file system that has to deal with
leases.
- Robert Rappaport
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