io_uring/bpf_filter: move filter size and populate helper into struct

Rather than open-code this logic in io_uring_populate_bpf_ctx() with
a switch, move it to the issue side definitions. Outside of making this
easier to extend in the future, it's also a prep patch for using the
pdu size for a given opcode filter elsewhere.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: axboe

io_uring/bpf_filter.c

@@ -26,6 +26,8 @@ static const struct io_bpf_filter dummy_filter;
 static void io_uring_populate_bpf_ctx(struct io_uring_bpf_ctx *bctx,
 				      struct io_kiocb *req)
 {
+	const struct io_issue_def *def = &io_issue_defs[req->opcode];
+
 	bctx->opcode = req->opcode;
 	bctx->sqe_flags = (__force int) req->flags & SQE_VALID_FLAGS;
 	bctx->user_data = req->cqe.user_data;
@@ -34,19 +36,12 @@ static void io_uring_populate_bpf_ctx(struct io_uring_bpf_ctx *bctx,
 		sizeof(*bctx) - offsetof(struct io_uring_bpf_ctx, pdu_size));
 
 	/*
-	 * Opcodes can provide a handler fo populating more data into bctx,
+	 * Opcodes can provide a handler for populating more data into bctx,
 	 * for filters to use.
 	 */
-	switch (req->opcode) {
-	case IORING_OP_SOCKET:
-		bctx->pdu_size = sizeof(bctx->socket);
-		io_socket_bpf_populate(bctx, req);
-		break;
-	case IORING_OP_OPENAT:
-	case IORING_OP_OPENAT2:
-		bctx->pdu_size = sizeof(bctx->open);
-		io_openat_bpf_populate(bctx, req);
-		break;
+	if (def->filter_pdu_size) {
+		bctx->pdu_size = def->filter_pdu_size;
+		def->filter_populate(bctx, req);
 	}
 }
 

io_uring/opdef.c

@@ -221,8 +221,10 @@ const struct io_issue_def io_issue_defs[] = {
 		.issue			= io_fallocate,
 	},
 	[IORING_OP_OPENAT] = {
+		.filter_pdu_size	= sizeof_field(struct io_uring_bpf_ctx, open),
 		.prep			= io_openat_prep,
 		.issue			= io_openat,
+		.filter_populate	= io_openat_bpf_populate,
 	},
 	[IORING_OP_CLOSE] = {
 		.prep			= io_close_prep,
@@ -309,8 +311,10 @@ const struct io_issue_def io_issue_defs[] = {
 #endif
 	},
 	[IORING_OP_OPENAT2] = {
+		.filter_pdu_size	= sizeof_field(struct io_uring_bpf_ctx, open),
 		.prep			= io_openat2_prep,
 		.issue			= io_openat2,
+		.filter_populate	= io_openat_bpf_populate,
 	},
 	[IORING_OP_EPOLL_CTL] = {
 		.unbound_nonreg_file	= 1,
@@ -406,8 +410,10 @@ const struct io_issue_def io_issue_defs[] = {
 	[IORING_OP_SOCKET] = {
 		.audit_skip		= 1,
 #if defined(CONFIG_NET)
+		.filter_pdu_size	= sizeof_field(struct io_uring_bpf_ctx, socket),
 		.prep			= io_socket_prep,
 		.issue			= io_socket,
+		.filter_populate	= io_socket_bpf_populate,
 #else
 		.prep			= io_eopnotsupp_prep,
 #endif

io_uring/opdef.h

@@ -2,6 +2,8 @@
 #ifndef IOU_OP_DEF_H
 #define IOU_OP_DEF_H
 
+struct io_uring_bpf_ctx;
+
 struct io_issue_def {
 	/* needs req->file assigned */
 	unsigned		needs_file : 1;
@@ -33,8 +35,12 @@ struct io_issue_def {
 	/* size of async data needed, if any */
 	unsigned short		async_size;
 
+	/* bpf filter pdu size, if any */
+	unsigned short		filter_pdu_size;
+
 	int (*issue)(struct io_kiocb *, unsigned int);
 	int (*prep)(struct io_kiocb *, const struct io_uring_sqe *);
+	void (*filter_populate)(struct io_uring_bpf_ctx *, struct io_kiocb *);
 };
 
 struct io_cold_def {