Messages in this thread Patch in this message | | | Subject | Re: [PATCH v1] fs/io_uring: Hoist ret2 == -EAGAIN check in tail of io_write | From | Hao Xu <> | Date | Mon, 18 Oct 2021 20:17:57 +0800 |
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在 2021/10/18 下午3:02, Noah Goldstein 写道: > This commit reorganizes the branches in the tail of io_write so that > the 'ret2 == -EAGAIN' check is not repeated and done first. > > The previous version was duplicating the 'ret2 == -EAGAIN'. As well > 'ret2 != -EAGAIN' gurantees the 'done:' path so it makes sense to > move that check to the front before the likely more expensive branches > which require memory derefences. > > Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com> > --- > Generally I would want to rewrite this as: > ``` > if (ret2 != -EAGAIN > || (req->flags & REQ_F_NOWAIT) > || (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))) > kiocb_done(kiocb, ret2, issue_flags); > else { > ... > ``` To me, this one is clear enough and short, but I think better to: if (ret2 != -EAGAIN || (req->flags & REQ_F_NOWAIT) || (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
if the first line doesn't exceed the line limit.
Reviewed-by: Hao Xu <haoxu@linux.alibaba.com> > > But the style of the file seems to be to use gotos. If the above is > prefereable, let me know and I'll post a new version. > fs/io_uring.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index d1e672e7a2d1..932fc84d70d3 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -3648,12 +3648,15 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags) > */ > if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT)) > ret2 = -EAGAIN; > + > + if (ret2 != -EAGAIN) > + goto done; > /* no retry on NONBLOCK nor RWF_NOWAIT */ > - if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT)) > + if (req->flags & REQ_F_NOWAIT) > goto done; > - if (!force_nonblock || ret2 != -EAGAIN) { > + if (!force_nonblock) { > /* IOPOLL retry should happen for io-wq threads */ > - if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL)) > + if (req->ctx->flags & IORING_SETUP_IOPOLL) > goto copy_iov; > done: > kiocb_done(kiocb, ret2, issue_flags); >
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