On Tue, 2009-02-17 at 12:55 +0100, Nick Piggin wrote: > On Tue, Feb 17, 2009 at 12:39:32PM +0100, Peter Zijlstra wrote: > > On Tue, 2009-02-17 at 12:25 +0100, Nick Piggin wrote: > > > > > Introduce put_user_pages function. > > > > > > In order to have more flexibility to deal with issues surrounding > > > get_user_pages difficulties[*], introduce put_user_pages function > > > intended to release pages acquired by get_user_pages. For now, just > > > do the regular put_page thing. If all callers are converted, it could > > > be used to help with such races. In the meantime, it will actually > > > serve as a small extra piece of documentation for the code. > > > > > > [*] eg. get_user_pages caller can bypass page_mkwrite calls into the > > > filesystem to notify of page dirty activity if the page gets cleaned > > > before the caller calls its final set_page_dirty). > > > > Hmm, if we want to distinguish between .write=1 and .write=0, we would > > have to pass .write to pup too, right? > > Doh, yeah. I hand edited the patch to put that parameter in, but quilt > refresh must have outsmarted me! > > If nobody thinks it is insane, I'll resend to Andrew in a new thread. Right, gup_fast() seems to also respect .write properly, so it would also be used to balance that. I guess gup_fast() would need to use trylock_page(), and fall back to the slow path when we start taking PG_locked on .write. I suppose we should start converting a few gup users over to pup before handing the thing to Andrew, to have at least a few examples in-kernel. -- To unsubscribe from this list: send the line "unsubscribe reiserfs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
