[PATCH v2 2/3] io_uring/cmd: add per-op data to struct io_uring_cmd_data

Mark Harmstone
2024-12-13T18:45:07Z

From: Jens Axboe <axboe@kernel.dk>

In case an op handler for ->uring_cmd() needs stable storage for user
data, it can allocate io_uring_cmd_data->op_data and use it for the
duration of the request. When the request gets cleaned up, uring_cmd
will free it automatically.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
include/linux/io_uring/cmd.h | 1 +
io_uring/uring_cmd.c | 13 +++++++++++--
2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index 61f97a398e9d..a65c7043078f 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -20,6 +20,7 @@ struct io_uring_cmd {

struct io_uring_cmd_data {
struct io_uring_sqe sqes[2];
+ void *op_data;
};

static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 629cb4266da6..ce7726a04883 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -23,12 +23,16 @@ static struct io_uring_cmd_data *io_uring_async_get(struct io_kiocb *req)

cache = io_alloc_cache_get(&ctx->uring_cache);
if (cache) {
+ cache->op_data = NULL;
req->flags |= REQ_F_ASYNC_DATA;
req->async_data = cache;
return cache;
}
- if (!io_alloc_async_data(req))
- return req->async_data;
+ if (!io_alloc_async_data(req)) {
+ cache = req->async_data;
+ cache->op_data = NULL;
+ return cache;
+ }
return NULL;
}

@@ -37,6 +41,11 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
struct io_uring_cmd_data *cache = req->async_data;

+ if (cache->op_data) {
+ kfree(cache->op_data);
+ cache->op_data = NULL;
+ }
+
if (issue_flags & IO_URING_F_UNLOCKED)
return;
if (io_alloc_cache_put(&req->ctx->uring_cache, cache)) {
--
2.45.2