From: Pavel Begunkov asml.silence@gmail.com
[ upstream commit cd65869512ab5668a5d16f789bc4da1319c435c4 ]
The issue was first described and addressed in 89c2b3b7491820 ("io_uring: reexpand under-reexpanded iters"), but shortly after reimplemented as. cd65869512ab56 ("io_uring: use iov_iter state save/restore helpers").
Here we follow the approach from the second patch but without in-callback resubmissions, fixups for not yet supported in 5.10 short read retries and replacing iov_iter_state with iter copies to not pull even more dependencies, and because it's just much simpler.
Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/io_uring.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3389,6 +3389,7 @@ static int io_read(struct io_kiocb *req, struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; struct kiocb *kiocb = &req->rw.kiocb; struct iov_iter __iter, *iter = &__iter; + struct iov_iter iter_cp; struct io_async_rw *rw = req->async_data; ssize_t io_size, ret, ret2; bool no_async; @@ -3399,6 +3400,7 @@ static int io_read(struct io_kiocb *req, ret = io_import_iovec(READ, req, &iovec, iter, !force_nonblock); if (ret < 0) return ret; + iter_cp = *iter; io_size = iov_iter_count(iter); req->result = io_size; ret = 0; @@ -3434,7 +3436,7 @@ static int io_read(struct io_kiocb *req, if (req->file->f_flags & O_NONBLOCK) goto done; /* some cases will consume bytes even on error returns */ - iov_iter_revert(iter, io_size - iov_iter_count(iter)); + *iter = iter_cp; ret = 0; goto copy_iov; } else if (ret < 0) { @@ -3517,6 +3519,7 @@ static int io_write(struct io_kiocb *req struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; struct kiocb *kiocb = &req->rw.kiocb; struct iov_iter __iter, *iter = &__iter; + struct iov_iter iter_cp; struct io_async_rw *rw = req->async_data; ssize_t ret, ret2, io_size;
@@ -3526,6 +3529,7 @@ static int io_write(struct io_kiocb *req ret = io_import_iovec(WRITE, req, &iovec, iter, !force_nonblock); if (ret < 0) return ret; + iter_cp = *iter; io_size = iov_iter_count(iter); req->result = io_size;
@@ -3587,7 +3591,7 @@ done: } else { copy_iov: /* some cases will consume bytes even on error returns */ - iov_iter_revert(iter, io_size - iov_iter_count(iter)); + *iter = iter_cp; ret = io_setup_async_rw(req, iovec, inline_vecs, iter, false); if (!ret) return -EAGAIN;