We no longer revert the iovec on -EIOCBQUEUED, see commit ab2125df921d, and this started causing issues for IOPOLL on devies that run out of request slots. Turns out what outside of needing a revert for those, we also had a bug where we didn't properly setup retry inside the submission path. That could cause re-import of the iovec, if any, and that could lead to spurious results if the application had those allocated on the stack.
Catch -EAGAIN retry and make the iovec stable for IOPOLL, just like we do for !IOPOLL retries.
Cc: stable@vger.kernel.org # 5.9+ Reported-by: Abaci Robot abaci@linux.alibaba.com Reported-by: Xiaoguang Wang xiaoguang.wang@linux.alibaba.com Signed-off-by: Jens Axboe axboe@kernel.dk --- fs/io_uring.c | 36 +++++++++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 28a360aac4a3..c765b7fba8a1 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2423,23 +2423,32 @@ static bool io_resubmit_prep(struct io_kiocb *req) return false; return !io_setup_async_rw(req, iovec, inline_vecs, &iter, false); } -#endif
-static bool io_rw_reissue(struct io_kiocb *req) +static bool io_rw_should_reissue(struct io_kiocb *req) { -#ifdef CONFIG_BLOCK umode_t mode = file_inode(req->file)->i_mode; + struct io_ring_ctx *ctx = req->ctx;
if (!S_ISBLK(mode) && !S_ISREG(mode)) return false; - if ((req->flags & REQ_F_NOWAIT) || io_wq_current_is_worker()) + if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() && + !(ctx->flags & IORING_SETUP_IOPOLL))) return false; /* * If ref is dying, we might be running poll reap from the exit work. * Don't attempt to reissue from that path, just let it fail with * -EAGAIN. */ - if (percpu_ref_is_dying(&req->ctx->refs)) + if (percpu_ref_is_dying(&ctx->refs)) + return false; + return true; +} +#endif + +static bool io_rw_reissue(struct io_kiocb *req) +{ +#ifdef CONFIG_BLOCK + if (!io_rw_should_reissue(req)) return false;
lockdep_assert_held(&req->ctx->uring_lock); @@ -2482,6 +2491,19 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2) { struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
+#ifdef CONFIG_BLOCK + /* Rewind iter, if we have one. iopoll path resubmits as usual */ + if (res == -EAGAIN && io_rw_should_reissue(req)) { + struct io_async_rw *rw = req->async_data; + + if (rw) + iov_iter_revert(&rw->iter, + req->result - iov_iter_count(&rw->iter)); + else if (!io_resubmit_prep(req)) + res = -EIO; + } +#endif + if (kiocb->ki_flags & IOCB_WRITE) kiocb_end_write(req);
@@ -3230,6 +3252,8 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags) ret = io_iter_do_read(req, iter);
if (ret == -EIOCBQUEUED) { + if (req->async_data) + iov_iter_revert(iter, io_size - iov_iter_count(iter)); goto out_free; } else if (ret == -EAGAIN) { /* IOPOLL retry should happen for io-wq threads */ @@ -3361,6 +3385,8 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags) /* no retry on NONBLOCK nor RWF_NOWAIT */ if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT)) goto done; + if (ret2 == -EIOCBQUEUED && req->async_data) + iov_iter_revert(iter, io_size - iov_iter_count(iter)); if (!force_nonblock || ret2 != -EAGAIN) { /* IOPOLL retry should happen for io-wq threads */ if ((req->ctx->flags & IORING_SETUP_IOPOLL) && ret2 == -EAGAIN)