On Wed, May 19, 2010 at 05:46:23PM +0800, Mi Jinlong wrote: > > > J. Bruce Fields : > > On Fri, May 14, 2010 at 02:31:12PM -0400, Trond Myklebust wrote: > >> On Fri, 2010-05-14 at 13:59 -0400, Trond Myklebust wrote: > >>> Note that the server should also recall the delegation if someone > >>> attempts to violate the guarantees that are listed in section 9.4: Open > >>> Delegation > >>> > >>> When a client has a read open delegation, it may not make any changes > >>> to the contents or attributes of the file but it is assured that no > >>> other client may do so. When a client has a write open delegation, > >>> it may modify the file data since no other client will be accessing > >>> the file's data. The client holding a write delegation may only > >>> affect file attributes which are intimately connected with the file > >>> data: size, time_modify, change. > >>> > >>> IOW: even if you hold a write delegation you are not allowed to change > >>> the file mode bits, owner, group or acls... > >> ...or the nlink value. So technically, we should also recall the > >> delegation when someone creates or deletes a hard link. I think I need > >> to remind Tom that he should add that to the RFC3530bis draft... > > > > Yep. And fixing all these cases is required before our the server's > > NFSv4 server is ready for much of anything. > > > > I'm not sure ading break_lease() to may_delete() is right, but maybe > > it's better than nothing. > > Agree with you. > > > > > One problem is that there's a race: nothing I can see stops anyone from > > getting another lease after may_delete() but before the delete happens. > > Yes. > The problem will exist, but there isn't some better methods to avoid it. > Is there a lease lock exist in kernel? > If that's true, the problem will be fixed simply. I don't know of any existing lock that does exactly what we want. Somebody at citi worked on a better lease implementation for a while, but I don't think we ever really got it right; the last version I can find is here: git://linux-nfs.org/~bfields/linux-topics.git leases --b. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
