I'll put it in aio_prep_rw like you suggest and run it through xfstests. I work through gmail, so I'll fiddle with my git-sendmail-foo and send the patch up after that. Thanks! -Mike On Sat, Feb 2, 2019 at 11:37 AM Jens Axboe <axboe@xxxxxxxxx> wrote: > > On 2/2/19 9:35 AM, Jens Axboe wrote: > > 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? > > BTW, I'd probably initialize it in aio_prep_rw(), that's the more > logical place for it. > > > diff --git a/fs/aio.c b/fs/aio.c > index b906ff70c90f..aaaaf4d12c73 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -1436,6 +1436,7 @@ static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb) > if (unlikely(!req->ki_filp)) > return -EBADF; > req->ki_complete = aio_complete_rw; > + req->private = NULL; > req->ki_pos = iocb->aio_offset; > req->ki_flags = iocb_flags(req->ki_filp); > if (iocb->aio_flags & IOCB_FLAG_RESFD) > > -- > Jens Axboe >
