[PATCH v4 1/9] io_uring: introduce struct iou_vec

[Pavel Begunkov <asml.silence@gmail.com>]

I need a convenient way to pass around and work with iovec+size pair,
put them into a structure and makes use of it in rw.c

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 include/linux/io_uring_types.h |  5 +++++
 io_uring/rsrc.c                |  9 +++++++++
 io_uring/rsrc.h                | 16 ++++++++++++++++
 io_uring/rw.c                  | 17 +++++++----------
 io_uring/rw.h                  |  4 ++--
 5 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 35fc241c4672..9101f12d21ef 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -110,6 +110,11 @@ struct io_uring_task {
 	} ____cacheline_aligned_in_smp;
 };
 
+struct iou_vec {
+	struct iovec		*iovec;
+	unsigned		nr;
+};
+
 struct io_uring {
 	u32 head;
 	u32 tail;
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 28783f1dde00..bac509f85c80 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1260,3 +1260,12 @@ int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg)
 	fput(file);
 	return ret;
 }
+
+void io_vec_free(struct iou_vec *iv)
+{
+	if (!iv->iovec)
+		return;
+	kfree(iv->iovec);
+	iv->iovec = NULL;
+	iv->nr = 0;
+}
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 284e300e63fb..f35e1a07619a 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -145,4 +145,20 @@ static inline void __io_unaccount_mem(struct user_struct *user,
 	atomic_long_sub(nr_pages, &user->locked_vm);
 }
 
+void io_vec_free(struct iou_vec *iv);
+
+static inline void io_vec_reset_iovec(struct iou_vec *iv,
+				      struct iovec *iovec, unsigned nr)
+{
+	io_vec_free(iv);
+	iv->iovec = iovec;
+	iv->nr = nr;
+}
+
+static inline void io_alloc_cache_vec_kasan(struct iou_vec *iv)
+{
+	if (IS_ENABLED(CONFIG_KASAN))
+		io_vec_free(iv);
+}
+
 #endif
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 5ee9f8949e8b..ad7f647d48e9 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -87,9 +87,9 @@ static int io_import_vec(int ddir, struct io_kiocb *req,
 	int ret, nr_segs;
 	struct iovec *iov;
 
-	if (io->free_iovec) {
-		nr_segs = io->free_iov_nr;
-		iov = io->free_iovec;
+	if (io->vec.iovec) {
+		nr_segs = io->vec.nr;
+		iov = io->vec.iovec;
 	} else {
 		nr_segs = 1;
 		iov = &io->fast_iov;
@@ -101,9 +101,7 @@ static int io_import_vec(int ddir, struct io_kiocb *req,
 		return ret;
 	if (iov) {
 		req->flags |= REQ_F_NEED_CLEANUP;
-		io->free_iov_nr = io->iter.nr_segs;
-		kfree(io->free_iovec);
-		io->free_iovec = iov;
+		io_vec_reset_iovec(&io->vec, iov, io->iter.nr_segs);
 	}
 	return 0;
 }
@@ -151,7 +149,7 @@ static void io_rw_recycle(struct io_kiocb *req, unsigned int issue_flags)
 	if (unlikely(issue_flags & IO_URING_F_UNLOCKED))
 		return;
 
-	io_alloc_cache_kasan(&rw->free_iovec, &rw->free_iov_nr);
+	io_alloc_cache_vec_kasan(&rw->vec);
 	if (io_alloc_cache_put(&req->ctx->rw_cache, rw)) {
 		req->async_data = NULL;
 		req->flags &= ~REQ_F_ASYNC_DATA;
@@ -201,7 +199,7 @@ static int io_rw_alloc_async(struct io_kiocb *req)
 	rw = io_uring_alloc_async_data(&ctx->rw_cache, req);
 	if (!rw)
 		return -ENOMEM;
-	if (rw->free_iovec)
+	if (rw->vec.iovec)
 		req->flags |= REQ_F_NEED_CLEANUP;
 	rw->bytes_done = 0;
 	return 0;
@@ -1327,7 +1325,6 @@ void io_rw_cache_free(const void *entry)
 {
 	struct io_async_rw *rw = (struct io_async_rw *) entry;
 
-	if (rw->free_iovec)
-		kfree(rw->free_iovec);
+	io_vec_free(&rw->vec);
 	kfree(rw);
 }
diff --git a/io_uring/rw.h b/io_uring/rw.h
index bf121b81ebe8..529fd2f96a7f 100644
--- a/io_uring/rw.h
+++ b/io_uring/rw.h
@@ -9,13 +9,13 @@ struct io_meta_state {
 };
 
 struct io_async_rw {
+	struct iou_vec			vec;
 	size_t				bytes_done;
-	struct iovec			*free_iovec;
+
 	struct_group(clear,
 		struct iov_iter			iter;
 		struct iov_iter_state		iter_state;
 		struct iovec			fast_iov;
-		int				free_iov_nr;
 		/*
 		 * wpq is for buffered io, while meta fields are used with
 		 * direct io
-- 
2.48.1