On Tue, 31 Mar 2009 17:20:31 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 31 Mar 2009 20:03:59 -0400 > Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > > + * It's not sufficient to just do a time_after() check on > > + * dirtied_when. That assumes that dirtied_when will always > > + * change within a period of jiffies that encompasses half the > > + * machine word size (2^31 jiffies on 32-bit arch). That's not > > + * necessarily the case if an inode is being constantly > > + * redirtied. Since dirtied_when can never be in the future, > > + * we can assume that if it appears to be so then it is > > + * actually in the distant past. > > so this really is a 32-bit-only thing. > > I guess that isn't worth optimising for though. > Yeah, it's pretty much impossible to hit this on a 64-bit machine. > otoh, given that all three comparisons are the same: > > + time_after(inode->dirtied_when, *older_than_this) && > + time_before_eq(inode->dirtied_when, jiffies)) > > (although one is inverted (i think?)), it might end up nicer if this was all done > in a little helper function? > > That way we only need to comment what's going on at a single site, and > we could omit the additional test if !CONFIG_64BIT. Ok, that seems reasonable. At one point I had a macro similar to time_in_range(), but dropped it primarily because time_after_but_before_eq() wasn't easy on the eyes. Thoughts on better names? -- Jeff Layton <jlayton@xxxxxxxxxx> -- 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
