On Mon, Jun 25, 2007 at 04:58:48PM +1000, Nick Piggin wrote: > > >Using buffer heads instead allows the FS to send file data down inside > >the transaction code, without taking the page lock. So, locking wrt > >data=ordered is definitely going to be tricky. > > > >The best long term option may be making the locking order > >transaction -> page lock, and change writepage to punt to some other > >queue when it needs to start a transaction. > > Yeah, that's what I would like, and I think it would come naturally > if we move away from these "pass down a single, locked page APIs" > in the VM, and let the filesystem do the locking and potentially > batching of larger ranges. Definitely. > > write_begin/write_end is a step in that direction (and it helps > OCFS and GFS quite a bit). I think there is also not much reason > for writepage sites to require the page to lock the page and clear > the dirty bit themselves (which has seems ugly to me). If we keep the page mapping information with the page all the time (ie writepage doesn't have to call get_block ever), it may be possible to avoid sending down a locked page. But, I don't know the delayed allocation internals well enough to say for sure if that is true. Either way, writepage is the easiest of the bunch because it can be deferred. -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
