On Fri, 2010-11-05 at 12:28 -0400, J. Bruce Fields wrote: > On Fri, Nov 05, 2010 at 07:08:06AM -0400, Mimi Zohar wrote: > > Right, like the ima_file_check(), which is after the __dentry_open(). > > Al, is it possible to move the break_lease() in may_open() to later? > > That would still leave a race like: > > check count > bump count > break lease > set lease > > But we could extend the i_lock to prevent the lease being bumped between > the two steps on the right-hand side. The latest i_readcount patchset, i_readcount is atomic and doesn't require i_lock, at least for IMA. Have to think about this more .... > At that point I think we'd be done? We're assured the count is still > zero while the lease is added to the inode, so anyone in the process of > doing an open has yet to reach the break_lease, which will see the newly > added lease. > > That leaves the problem that leases really should be broken on anything > that changes the attributes or the dentries pointing to the inode: > setattr, link, unlink, rename, at least. For this reason, IMA is now taking i_mutex, preventing file metadata from changing. > One approach: add another counter to the inode named disable_leases, and > have any of those operations do something like: > > disable_lease++ > break_lease > ... do operation ... > disable_lease-- > > ? > > --b. lol, getting i_readcount was was hard enough. Mimi -- 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
