On 2/1/19 7:29 PM, Mike Marshall wrote: > We've been working on our Orangefs page cache patch with blinders on, > and last week I took our patch set which was based on 4.19-rc7 > and applied it to 5.0-rc3. > > In the process I ran vanilla rc3, and rc3 plus an Orangefs related > patch set that Christoph Hellwig sent in, through the > suite of xfstests. > > It turns out that a patch from one of Jens Axboe's patch sets > that came, I think, in the 5.0 merge window triggered a BUG_ON in Orangefs' > file.c. The particular patch is "aio: don't zero entire aio_kiocb aio_get_req". > > This code is in Orangefs file.c in a couple of places: > > BUG_ON(iocb->private); > > Anywho... I can easily fix the Orangefs problem by removing the two > BUG_ON statements, I've researched how they got there and they > are vestigial, just the kind of thing that Linus hates :-). > > The bigger question is that maybe there is other code in other filesystems > that checks iocb->private without failing in a way that is as obvious > as BUG_ON. I don't see any upstream code with grep other than a few > lines in ext4/inode.c that might be affected. > > As a test, I "fixed" the Orangefs problem with this: > > [hubcap@vm1 linux]# git diff > diff --git a/fs/aio.c b/fs/aio.c > index b906ff70c90f..2605a4b1a3c9 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -1020,6 +1020,7 @@ static inline struct aio_kiocb > *aio_get_req(struct kioctx *ctx) > if (unlikely(!req)) > return NULL; > > + req->rw.private = NULL; > percpu_ref_get(&ctx->reqs); > req->ki_ctx = ctx; > INIT_LIST_HEAD(&req->ki_list); > > So, the real fix for Orangefs is getting rid of the two BUG_ON lines, > and I'll do that, I just wanted to bring this up in case it matters > to anyone else... Let's just bring it back, I think your patch is fine. I don't see any other issues with this in a git grep, but better safe than sorry. Care to send this as a properly formatted patch so it can get included? -- Jens Axboe
