Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> writes: > On Thu, Mar 3, 2011 at 12:46 PM, OGAWA Hirofumi > <hirofumi@xxxxxxxxxxxxxxxxxx> wrote: >> >> But, some commands see i_nlink (IIRC, it's checking i_nlink == 2, to >> know empty dir or not). > > Actually, that would be a serious bug in the application. > > The traditional rule of thumb is that a directory with i_nlink==1 has > a "I'm not counting at all". > > For example, I think that's the rule that 'find' uses to decide if a > directory can have subdirectories (and when it could try to stop > scanning early): i_nlink == 1 means that yes, it _can_ have > subdirectories, we just don't know how many. Yes. I think it is. > So checking i_nlink==2 is actually a user-level bug. We can call it's the user-level bug, but like you know, we will receive many complain if old behavior was broken. If you are saying i_nlink == 2 is meaning the undefine, it sounds strange. (I was thinking it's why isofs is using i_nlink == 1 always. I.e. i_nlink >= 2 is defined behavior. Actually the reason would be "find" was checking i_nlink == 2 though) >> So we have to simulate some levels. I guess you >> are not saying we don't need to care it at all though. > > I'm saying that it should just work to set i_nlink=1 and not do > anything at all. Ever. It's a valid model for directory counts. > > Seriously - that's what isofs does, for example. It does mean that > 'find' for certain cases gets bit more expensive, but on the other > hand, other operations are a lot _less_ expensive. > > We might well try that as a FAT mount option, to let people decide > whether they really do want the "scan directories all the time" or > only the "let 'find' scan directories when it needs to" behavior. Yes. i_nlink == 1 is ok, IIRC (I checked last time at least. And I used i_nlink == 1 for exFAT). And I agree with you almost all, but isofs is read-only, the read-only is why I was not really sure. And I can't only see is why you refuse to make consistent behavior (if you are saying it). It's why I said if it's _really easy_. Thanks -- OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> -- 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
