On Tue, 2009-03-03 at 15:41 +0100, Nick Piggin wrote: > On Tue, Mar 03, 2009 at 09:26:03AM -0500, Chris Mason wrote: > > On Tue, 2009-03-03 at 11:41 +0100, Nick Piggin wrote: > > > page_mkwrite is called with neither the page lock nor the ptl held. This > > > means a page can be concurrently truncated or invalidated out from underneath > > > it. Callers are supposed to prevent truncate races themselves, however > > > previously the only thing they can do in case they hit one is to raise a > > > SIGBUS. A sigbus is wrong for the case that the page has been invalidated > > > or truncated within i_size (eg. hole punched). Callers may also have to > > > perform memory allocations in this path, where again, SIGBUS would be wrong. > > > > > > The previous patch made it possible to properly specify errors. Convert > > > the generic buffer.c code and btrfs to return sane error values > > > (in the case of page removed from pagecache, VM_FAULT_NOPAGE will cause the > > > fault handler to exit without doing anything, and the fault will be retried > > > properly). > > > > > > > Thanks Nick. I think the btrfs patch needs an extra } to compile, but > > it looks fine. > > OK... btrfs is obviously untested :) I just got to btrfs and realised > that probably most of the non-trivial ones will want fs maintainers to > take a look. I *think* the following errors should mostly be right: > > !page->mapping ==> VM_FAULT_NOPAGE (just cause the VM to retry the fault) > -ENOMEM ==> VM_FAULT_OOM > any other error ==> VM_FAULT_SIGBUS > It's no problem, the patch made things more clear than it was before. You can add an sob for me once it compiles ;) -chris -- 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
