On Fri 18-06-10 12:21:37, Peter Zijlstra wrote: > On Thu, 2010-06-17 at 20:04 +0200, Jan Kara wrote: > > + if (bdi_stat(bdi, BDI_WRITTEN) >= bdi->wb_written_head) > > + bdi_wakeup_writers(bdi); > > For the paranoid amongst us you could make wb_written_head s64 and write > the above as: > > if (bdi_stat(bdi, BDI_WRITTEN) - bdi->wb_written_head > 0) > > Which, if you assume both are monotonic and wb_written_head is always > within 2^63 of the actual bdi_stat() value, should give the same end > result and deal with wrap-around. > > For when we manage to create a device that can write 2^64 pages in our > uptime :-) OK, the fix is simple enough so I've changed it, although I'm not paranoic enough ;) (I actually did the math before writing that test). Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>