vfs request refactor pt1

1 files changed, 67 insertions, 0 deletions

diff --git a/src/kernel/vfs/request.c b/src/kernel/vfs/request.c
new file mode 100644
index 0000000..1212aa4
--- /dev/null
+++ b/src/kernel/vfs/request.c
@@ -0,0 +1,67 @@
+#include <kernel/mem/alloc.h>
+#include <kernel/panic.h>
+#include <kernel/proc.h>
+#include <kernel/vfs/request.h>
+#include <kernel/vfs/root.h>
+
+// dispatches a VFS operation to the correct process
+_Noreturn void vfs_request_create(struct vfs_request req) {
+	int ret;
+	switch (req.backend->type) {
+		case VFS_BACK_ROOT:
+			ret = vfs_root_handler(&req);
+			vfs_request_finish(&req, ret);
+		case VFS_BACK_USER:
+			process_current->state = PS_WAITS4FS;
+			if (req.backend->handler == NULL) { 
+				// backend isn't ready yet, join the queue
+				assert(req.backend->queue == NULL); // TODO implement a proper queue
+
+				req.backend->queue = process_current;
+				process_current->pending_req = req;
+				process_switch_any();
+			} else {
+				vfs_request_pass2handler(&req);
+			}
+		default:
+			panic();
+	}
+}
+
+_Noreturn void vfs_request_pass2handler(struct vfs_request *req) {
+	assert(req->backend->handler);
+	assert(req->backend->handler->state == PS_WAITS4REQUEST);
+
+	req->backend->handler->state = PS_RUNNING;
+	// TODO pass the request to the process
+	process_switch(req->backend->handler);
+}
+
+// returns from a VFS operation to the calling process
+_Noreturn void vfs_request_finish(struct vfs_request *req, int ret) {
+	struct process *caller = req->caller;
+
+	if (req->type == VFSOP_OPEN && ret >= 0) {
+		// open() calls need special handling
+		// we need to wrap the id returned by the VFS in a handle passed to
+		// the client
+		handle_t handle = process_find_handle(req->caller);
+		if (handle < 0) panic();
+		req->caller->handles[handle] = (struct handle){
+			.type = HANDLE_FILE,
+			.file = {
+				.backend = req->backend,
+				.id = ret,
+			},
+		};
+		ret = handle;
+	}
+
+	if (req->type == VFSOP_OPEN)
+		kfree(req->open.path);
+
+	req->caller->state = PS_RUNNING;
+	regs_savereturn(&req->caller->regs, ret);
+	kfree(req);
+	process_switch(caller);
+}