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
