The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
Possible dependencies:
4d9cb92ca41d ("io_uring/rw: fix short rw error handling") f2ccb5aed7bc ("io_uring: make io_kiocb_to_cmd() typesafe") 14b146b688ad ("io_uring: notification completion optimisation") 6a9ce66f4d08 ("io_uring/net: make page accounting more consistent") 2e32ba5607ee ("io_uring/net: checks errors of zc mem accounting") 3ff1a0d395c0 ("io_uring: enable managed frags with register buffers") 492dddb4f6e3 ("io_uring: add zc notification flush requests") 4379d5f15b3f ("io_uring: rename IORING_OP_FILES_UPDATE") 63809137ebb5 ("io_uring: flush notifiers after sendzc") 10c7d33ecd51 ("io_uring: sendzc with fixed buffers") e29e3bd4b968 ("io_uring: account locked pages for non-fixed zc") 06a5464be84e ("io_uring: wire send zc request type") bc24d6bd32df ("io_uring: add notification slot registration") 68ef5578efc8 ("io_uring: add rsrc referencing for notifiers") e58d498e81ba ("io_uring: complete notifiers in tw") eb4a299b2f95 ("io_uring: cache struct io_notif") eb42cebb2cf2 ("io_uring: add zc notification infrastructure") e70cb60893ca ("io_uring: export io_put_task()") 72c531f8ef30 ("net: copy from user before calling __get_compat_msghdr") 7fa875b8e53c ("net: copy from user before calling __copy_msghdr")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 4d9cb92ca41dd8e905a4569ceba4716c2f39c75a Mon Sep 17 00:00:00 2001 From: Pavel Begunkov asml.silence@gmail.com Date: Fri, 9 Sep 2022 12:11:49 +0100 Subject: [PATCH] io_uring/rw: fix short rw error handling
We have a couple of problems, first reports of unexpected link breakage for reads when cqe->res indicates that the IO was done in full. The reason here is partial IO with retries.
TL;DR; we compare the result in __io_complete_rw_common() against req->cqe.res, but req->cqe.res doesn't store the full length but rather the length left to be done. So, when we pass the full corrected result via kiocb_done() -> __io_complete_rw_common(), it fails.
The second problem is that we don't try to correct res in io_complete_rw(), which, for instance, might be a problem for O_DIRECT but when a prefix of data was cached in the page cache. We also definitely don't want to pass a corrected result into io_rw_done().
The fix here is to leave __io_complete_rw_common() alone, always pass not corrected result into it and fix it up as the last step just before actually finishing the I/O.
Cc: stable@vger.kernel.org Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://github.com/axboe/liburing/issues/643 Reported-by: Beld Zhang beldzhang@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk
diff --git a/io_uring/rw.c b/io_uring/rw.c index 1babd77da79c..1e18a44adcf5 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -206,6 +206,20 @@ static bool __io_complete_rw_common(struct io_kiocb *req, long res) return false; }
+static inline unsigned io_fixup_rw_res(struct io_kiocb *req, unsigned res) +{ + struct io_async_rw *io = req->async_data; + + /* add previously done IO, if any */ + if (req_has_async_data(req) && io->bytes_done > 0) { + if (res < 0) + res = io->bytes_done; + else + res += io->bytes_done; + } + return res; +} + static void io_complete_rw(struct kiocb *kiocb, long res) { struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); @@ -213,7 +227,7 @@ static void io_complete_rw(struct kiocb *kiocb, long res)
if (__io_complete_rw_common(req, res)) return; - io_req_set_res(req, res, 0); + io_req_set_res(req, io_fixup_rw_res(req, res), 0); req->io_task_work.func = io_req_task_complete; io_req_task_work_add(req); } @@ -240,22 +254,14 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res) static int kiocb_done(struct io_kiocb *req, ssize_t ret, unsigned int issue_flags) { - struct io_async_rw *io = req->async_data; struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); - - /* add previously done IO, if any */ - if (req_has_async_data(req) && io->bytes_done > 0) { - if (ret < 0) - ret = io->bytes_done; - else - ret += io->bytes_done; - } + unsigned final_ret = io_fixup_rw_res(req, ret);
if (req->flags & REQ_F_CUR_POS) req->file->f_pos = rw->kiocb.ki_pos; if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) { if (!__io_complete_rw_common(req, ret)) { - io_req_set_res(req, req->cqe.res, + io_req_set_res(req, final_ret, io_put_kbuf(req, issue_flags)); return IOU_OK; } @@ -268,7 +274,7 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret, if (io_resubmit_prep(req)) io_req_task_queue_reissue(req); else - io_req_task_queue_fail(req, ret); + io_req_task_queue_fail(req, final_ret); } return IOU_ISSUE_SKIP_COMPLETE; }