On Fri, Nov 09, 2018 at 11:32:16AM +1100, NeilBrown wrote: > On Thu, Nov 08 2018, J. Bruce Fields wrote: > > > On Mon, Nov 05, 2018 at 12:30:47PM +1100, NeilBrown wrote: > >> struct file lock contains an 'fl_next' pointer which > >> is used to point to the lock that this request is blocked > >> waiting for. So rename it to fl_blocker. > >> > >> The fl_blocked list_head in an active lock is the head of a list of > >> blocked requests. In a request it is a node in that list. > >> These are two distinct uses, so replace with two list_heads > >> with different names. > >> fl_blocked is the head of a list of blocked requests > >> fl_block is a node on that list. > > > > Reading these, I have a lot of trouble keeping fl_blocked, fl_block, and > > fl_blocker straight. Is it just me? > > "Naming is hard" - but that is no excuse. > I suspect it isn't just you. > > I particularly like "fl_blocker". > > error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker); > > reads well to me - wait until this lock has a no blocker - i.e. until > nothing blocks it. > > fl_blocked could be fl_blockees (the things that I block), but I doubt > that is an improvement. Maybe. The plural might help me remember that it's the head of a list? > > I guess they form a tree, so fl_children, fl_siblings, and fl_parent > > might be easier for me to keep straight. > > This requires one to know a priori that the tree records which locks > block which requests, which is obvious to us now, but might not be so > obvious in 5 years time when we look at this code again. > > An I have never really liked the "siblings" naming. 'struct dentry' uses > "d_child", which is possibly ever more confusing. > I would like it to be obvious that this is a list-member, not a > list-head. Rusty once posted patches to allow the list head to be a > different type to the members, but that fell on deaf ears. > So > fl_blocked_member > might be an improvement - this is a member of the fl_blocked list. > It would be easier to search for than fl_block - which needs > fl_block[^a-z] to avoid false positives. Yeah, maybe, if it's not too long. > I'd be quite happy to change fl_block is any two people can agree on a > better name. I'm less inclined to change the others without a really > good proposal. > > Hmmm. what is the inverse of "Block"? If I block you then you .... I > know, you are a usurper. > So > fl_blocker points to the "parent" > fl_usurpers is a list of "children" > fl_usurpers_member is my linkage in that list. > or not. "Usurper" isn't doing it for me. Yeah, I've got no clever scheme. --b.
