io_uring/cmd: add iovec cache for commands

JIRA: https://issues.redhat.com/browse/RHEL-106845

commit 3a4689ac109f18f23ea0d0c1c79e055142796858
Author: Pavel Begunkov <asml.silence@gmail.com>
Date:   Fri Mar 21 18:04:33 2025 +0000

    io_uring/cmd: add iovec cache for commands

    Add iou_vec to commands and wire caching for it, but don't expose it to
    users just yet. We need the vec cleared on initial alloc, but since
    we can't place it at the beginning at the moment, zero the entire
    async_data. It's cached, and the performance effects only the initial
    allocation, and it might be not a bad idea since we're exposing those
    bits to outside drivers.

    Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
    Link: https://lore.kernel.org/r/c0f2145b75791bc6106eb4e72add2cf6a2c72a7a.1742579999.git.asml.silence@gmail.com
    Signed-off-by: Jens Axboe <axboe@kernel.dk>

Signed-off-by: Ming Lei <ming.lei@redhat.com>

io_uring/io_uring.c

@@ -289,7 +289,7 @@ static void io_free_alloc_caches(struct io_ring_ctx *ctx)
 	io_alloc_cache_free(&ctx->apoll_cache, kfree);
 	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
 	io_alloc_cache_free(&ctx->rw_cache, io_rw_cache_free);
-	io_alloc_cache_free(&ctx->cmd_cache, kfree);
+	io_alloc_cache_free(&ctx->cmd_cache, io_cmd_cache_free);
 	io_alloc_cache_free(&ctx->msg_cache, kfree);
 	io_futex_cache_free(ctx);
 	io_rsrc_cache_free(ctx);
@@ -335,7 +335,8 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 			    sizeof(struct io_async_rw),
 			    offsetof(struct io_async_rw, clear));
 	ret |= io_alloc_cache_init(&ctx->cmd_cache, IO_ALLOC_CACHE_MAX,
-			    sizeof(struct io_async_cmd), 0);
+			    sizeof(struct io_async_cmd),
+			    sizeof(struct io_async_cmd));
 	spin_lock_init(&ctx->msg_lock);
 	ret |= io_alloc_cache_init(&ctx->msg_cache, IO_ALLOC_CACHE_MAX,
 			    sizeof(struct io_kiocb), 0);

io_uring/opdef.c

@@ -737,6 +737,7 @@ const struct io_cold_def io_cold_defs[] = {
 	},
 	[IORING_OP_URING_CMD] = {
 		.name			= "URING_CMD",
+		.cleanup		= io_uring_cmd_cleanup,
 	},
 	[IORING_OP_SEND_ZC] = {
 		.name			= "SEND_ZC",

io_uring/uring_cmd.c

@@ -16,6 +16,14 @@
 #include "rsrc.h"
 #include "uring_cmd.h"
 
+void io_cmd_cache_free(const void *entry)
+{
+	struct io_async_cmd *ac = (struct io_async_cmd *)entry;
+
+	io_vec_free(&ac->vec);
+	kfree(ac);
+}
+
 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);
@@ -29,13 +37,23 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (issue_flags & IO_URING_F_UNLOCKED)
 		return;
+
+	io_alloc_cache_vec_kasan(&ac->vec);
+	if (ac->vec.nr > IO_VEC_CACHE_SOFT_CAP)
+		io_vec_free(&ac->vec);
+
 	if (io_alloc_cache_put(&req->ctx->cmd_cache, cache)) {
 		ioucmd->sqe = NULL;
 		req->async_data = NULL;
-		req->flags &= ~REQ_F_ASYNC_DATA;
+		req->flags &= ~(REQ_F_ASYNC_DATA|REQ_F_NEED_CLEANUP);
 	}
 }
 
+void io_uring_cmd_cleanup(struct io_kiocb *req)
+{
+	io_req_uring_cleanup(req, 0);
+}
+
 bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
 				   struct io_uring_task *tctx, bool cancel_all)
 {

io_uring/uring_cmd.h

@@ -1,13 +1,18 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include <linux/io_uring/cmd.h>
+#include <linux/io_uring_types.h>
 
 struct io_async_cmd {
 	struct io_uring_cmd_data	data;
+	struct iou_vec			vec;
 };
 
 int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags);
 int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+void io_uring_cmd_cleanup(struct io_kiocb *req);
 
 bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
 				   struct io_uring_task *tctx, bool cancel_all);
+
+void io_cmd_cache_free(const void *entry);