io_uring/rw: don't lose partial IO result on fail

A partially done read/write may end up in io_req_complete_failed() and
loose the result, make sure we return the number of bytes processed.

Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/05e0879c226bcd53b441bf92868eadd4bf04e2fc.1663668091.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/opdef.c

@@ -69,6 +69,7 @@ const struct io_op_def io_op_defs[] = {
 		.issue			= io_read,
 		.prep_async		= io_readv_prep_async,
 		.cleanup		= io_readv_writev_cleanup,
+		.fail			= io_rw_fail,
 	},
 	[IORING_OP_WRITEV] = {
 		.needs_file		= 1,
@@ -85,6 +86,7 @@ const struct io_op_def io_op_defs[] = {
 		.issue			= io_write,
 		.prep_async		= io_writev_prep_async,
 		.cleanup		= io_readv_writev_cleanup,
+		.fail			= io_rw_fail,
 	},
 	[IORING_OP_FSYNC] = {
 		.needs_file		= 1,
@@ -105,6 +107,7 @@ const struct io_op_def io_op_defs[] = {
 		.name			= "READ_FIXED",
 		.prep			= io_prep_rw,
 		.issue			= io_read,
+		.fail			= io_rw_fail,
 	},
 	[IORING_OP_WRITE_FIXED] = {
 		.needs_file		= 1,
@@ -119,6 +122,7 @@ const struct io_op_def io_op_defs[] = {
 		.name			= "WRITE_FIXED",
 		.prep			= io_prep_rw,
 		.issue			= io_write,
+		.fail			= io_rw_fail,
 	},
 	[IORING_OP_POLL_ADD] = {
 		.needs_file		= 1,
@@ -275,6 +279,7 @@ const struct io_op_def io_op_defs[] = {
 		.name			= "READ",
 		.prep			= io_prep_rw,
 		.issue			= io_read,
+		.fail			= io_rw_fail,
 	},
 	[IORING_OP_WRITE] = {
 		.needs_file		= 1,
@@ -289,6 +294,7 @@ const struct io_op_def io_op_defs[] = {
 		.name			= "WRITE",
 		.prep			= io_prep_rw,
 		.issue			= io_write,
+		.fail			= io_rw_fail,
 	},
 	[IORING_OP_FADVISE] = {
 		.needs_file		= 1,

io_uring/rw.c

@@ -954,6 +954,14 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
 		io_cqring_wake(ctx);
 }
 
+void io_rw_fail(struct io_kiocb *req)
+{
+	int res;
+
+	res = io_fixup_rw_res(req, req->cqe.res);
+	io_req_set_res(req, res, req->cqe.flags);
+}
+
 int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
 {
 	struct io_wq_work_node *pos, *start, *prev;

io_uring/rw.h

@@ -21,3 +21,4 @@ int io_readv_prep_async(struct io_kiocb *req);
 int io_write(struct io_kiocb *req, unsigned int issue_flags);
 int io_writev_prep_async(struct io_kiocb *req);
 void io_readv_writev_cleanup(struct io_kiocb *req);
+void io_rw_fail(struct io_kiocb *req);