[PATCH 3/3] io_uring: follow **iovec idiom in io_import_iovec

Pavel Begunkov
2020-07-13T20:01:27Z

As for import_iovec(), return !=NULL iovec from io_import_iovec() only
when it should be freed, that includes returning NULL when iovec is
already in req->io, because it shoulb be deallocated by other means,
e.g. inside op handler. After io_setup_async_rw() local iovec to ->io,
just mark it NULL, to follow the idea in io_{read,write} as well.

That's easier to follow, and especially useful if we want to reuse
per-op space for completion data.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 217dbb6563e7..0b9c0333d8c0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2739,10 +2739,8 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
if (req->io) {
struct io_async_rw *iorw = &req->io->rw;

- *iovec = iorw->iov;
- iov_iter_init(iter, rw, *iovec, iorw->nr_segs, iorw->size);
- if (iorw->iov == iorw->fast_iov)
- *iovec = NULL;
+ iov_iter_init(iter, rw, iorw->iov, iorw->nr_segs, iorw->size);
+ *iovec = NULL;
return iorw->size;
}

@@ -3025,6 +3023,8 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
inline_vecs, &iter);
if (ret)
goto out_free;
+ /* it's copied and will be cleaned with ->io */
+ iovec = NULL;
/* if we can retry, do so with the callbacks armed */
if (io_rw_should_retry(req)) {
ret2 = io_iter_do_read(req, &iter);
@@ -3040,8 +3040,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
}
}
out_free:
- if (!(req->flags & REQ_F_NEED_CLEANUP))
- kfree(iovec);
+ kfree(iovec);
return ret;
}

@@ -3142,12 +3141,13 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
inline_vecs, &iter);
if (ret)
goto out_free;
+ /* it's copied and will be cleaned with ->io */
+ iovec = NULL;
return -EAGAIN;
}
}
out_free:
- if (!(req->flags & REQ_F_NEED_CLEANUP))
- kfree(iovec);
+ kfree(iovec);
return ret;
}

--
2.24.0