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io_uring: fix using under-expanded iters

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[ 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>
This commit is contained in:
Pavel Begunkov 2022-06-03 13:17:05 +01:00 committed by Greg Kroah-Hartman
parent 57d01bcae7
commit 8adb751d29
1 changed files with 6 additions and 2 deletions
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8
fs/io_uring.c
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@ -3389,6 +3389,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
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, bool force_nonblock,
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, bool force_nonblock,
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, bool force_nonblock,
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, bool force_nonblock,
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 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
} 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;