io_uring: fix rw req completion

WARNING: at fs/io_uring.c:8578 io_ring_exit_work.cold+0x0/0x18

As reissuing is now passed back by REQ_F_REISSUE and kiocb_done()
internally uses __io_complete_rw(), it may stop after setting the flag
so leaving a dangling request.

There are tricky edge cases, e.g. reading beyound file, boundary, so
the easiest way is to hand code reissue in kiocb_done() as
__io_complete_rw() was doing for us before.

Fixes: 230d50d448ac ("io_uring: move reissue into regular IO path")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f602250d292f8a84cca9a01d747744d1e797be26.1617842918.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f1881ac..bd14327 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2762,6 +2762,7 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
 {
        struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
        struct io_async_rw *io = req->async_data;
+       bool check_reissue = kiocb->ki_complete == io_complete_rw;
 
        /* add previously done IO, if any */
        if (io && io->bytes_done > 0) {
@@ -2777,6 +2778,18 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
                __io_complete_rw(req, ret, 0, issue_flags);
        else
                io_rw_done(kiocb, ret);
+
+       if (check_reissue && req->flags & REQ_F_REISSUE) {
+               req->flags &= ~REQ_F_REISSUE;
+               if (!io_rw_reissue(req)) {
+                       int cflags = 0;
+
+                       req_set_fail_links(req);
+                       if (req->flags & REQ_F_BUFFER_SELECTED)
+                               cflags = io_put_rw_kbuf(req);
+                       __io_req_complete(req, issue_flags, ret, cflags);
+               }
+       }
 }
 
 static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter)