On Thu 24-01-13 14:13:52, Kent Overstreet wrote: > On Thu, Jan 24, 2013 at 01:27:59PM -0800, Andrew Morton wrote: > > Please also take a look at Jan's recent > > http://www.spinics.net/lists/linux-fsdevel/msg61738.html and have a > > think about how this plays with your patchset. > > I can't think of any possible interactions - none of my aio stuff messes > with the way the fput() happens; the aio code does call fput() when the > kiocb is freed and my patches do touch _that_ code but none of the > behaviour there changes. > > Might be worth documenting this though, I can't think of any reason it'd > be obvious looking at the aio code that the fput() has to happen after > aio_complete(). As with the bugs I just sent you patches for it's not > terribly clear who owns what in the kiocb when. > > Reading those patches though - the main change is to call > inode_dio_done() before calling aio_complete(). All inode_dio_done() > does though is issue a wakeup - to whatever called inode_dio_wait(). inode_dio_done() does a decrement and wakeup. > That means whatever called inode_dio_wait() needs its own ref on the > inode, and from a cursory glance at the code it is _not_ at all clear to > me that's the case - if inode_dio_wait() is merely finishing things for > that specific IO that need to be done in process context, I can easily > imagine it not being the case. > > Assuming whatever does call inode_dio_wait() does have its own ref, > there was only a real use after free when nothing was waiting on the > inode. Well, but there doesn't have to be any waiter... If there is, it had better have it's own ref, that's for sure. > Similarly for the ext4 code to write unwritten extents - and having seen > and helped chase a bug in that code before, that code _definitely_ needs > auditing. Agreed. That code is a mess. I'm cleaning up some of it but it's not easy. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- 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
