From: Pavel Begunkov asml.silence@gmail.com
[ upstream commit 89473c1a9205760c4fa6d158058da7b594a815f0 ]
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/io_uring.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2701,6 +2701,20 @@ static bool __io_complete_rw_common(stru 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 (io && io->bytes_done > 0) { + if (res < 0) + res = io->bytes_done; + else + res += io->bytes_done; + } + return res; +} + static void io_req_task_complete(struct io_kiocb *req, bool *locked) { unsigned int cflags = io_put_rw_kbuf(req); @@ -2724,7 +2738,7 @@ static void __io_complete_rw(struct io_k { if (__io_complete_rw_common(req, res)) return; - __io_req_complete(req, issue_flags, req->result, io_put_rw_kbuf(req)); + __io_req_complete(req, issue_flags, io_fixup_rw_res(req, res), io_put_rw_kbuf(req)); }
static void io_complete_rw(struct kiocb *kiocb, long res, long res2) @@ -2733,7 +2747,7 @@ static void io_complete_rw(struct kiocb
if (__io_complete_rw_common(req, res)) return; - req->result = res; + req->result = io_fixup_rw_res(req, res); req->io_task_work.func = io_req_task_complete; io_req_task_work_add(req); } @@ -2979,15 +2993,6 @@ static void kiocb_done(struct kiocb *kio unsigned int issue_flags) { struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb); - struct io_async_rw *io = req->async_data; - - /* add previously done IO, if any */ - if (io && io->bytes_done > 0) { - if (ret < 0) - ret = io->bytes_done; - else - ret += io->bytes_done; - }
if (req->flags & REQ_F_CUR_POS) req->file->f_pos = kiocb->ki_pos; @@ -3004,6 +3009,7 @@ static void kiocb_done(struct kiocb *kio unsigned int cflags = io_put_rw_kbuf(req); struct io_ring_ctx *ctx = req->ctx;
+ ret = io_fixup_rw_res(req, ret); req_set_fail(req); if (!(issue_flags & IO_URING_F_NONBLOCK)) { mutex_lock(&ctx->uring_lock);