On Sat, Apr 07, 2018 at 09:50:05AM -0700, Linus Torvalds wrote: > On Thu, Apr 5, 2018 at 1:29 PM, David Howells <dhowells@xxxxxxxxxx> wrote: > >> > > Here are a set of AFS patches, a few fixes, but mostly development. The fixes > > are: > > So I pulled this after your updated fscache pull request, and I notice > that these three commits are duplicate (not shared): > > fscache: Attach the index key and aux data to the cookie > fscache: Pass object size in rather than calling back for it > fscache: Maintain a catalogue of allocated cookies > > and partly as a result I get some trivial conflicts. > > Now, the conflicts really do look entirely trivial, and that's not the > problem, but the fact that you *didn't* re-send the AFS pull request > makes me wonder if you perhaps didn't want me to pull it after all? > > So I decided to not do the resolution, and instead just verify with > you that you still want this pulled? > > No need to rebase, no need to do anything at all, really, except reply > with "yes I want you to pull this" or "no, the fscache pull updates > meant that I want you to do something else, hold off". > > Pls advice. > > (I may decide later to pull anyway, because I *think* you want me to > pull, but thought to ask in case you're online and answer quickly). FWIW, the main problem I see in there is the use of lookup_one_len() with parent locked only shared. As it is, that's simply broken - lookup of full name happening at the same time will bugger the things badly. I have a series that lowers requirements to "parent must be held at least shared" (see vfs.git#work.dcache) and it seems to be working. With that series the locking problem goes away; however, the use of dget_parent() around that lookup_one_len() call is pointless - ->lookup() is guaranteed that * dentry->d_parent is stable at least until dentry becomes positive. Dentry it originally pointed to remains pinned and positive through the entire call of ->lookup(); 'dir' argument of ->lookup() is the inode of that dentry. * dentry->d_name is stable at least until it becomes positive. * dir remains locked at least shared through the entire call of ->lookup(). All ->lookup() instances rely upon that and there's no need to play silly buggers with careful grabbing a reference to dentry->d_parent. That, of course, can be dealt with after merge, but since that commit has to be at least rebased to avoid bisection hazard... might as well get rid of dget_parent() there at the same time.
