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#include <kernel/mem/alloc.h>
#include <kernel/panic.h>
#include <kernel/proc.h>
#include <kernel/vfs/backend.h>
#include <kernel/vfs/root.h>
// dispatches a VFS operation to the correct process
_Noreturn void vfs_backend_dispatch(struct vfs_backend *backend, struct vfs_op op) {
struct vfs_op_request *req = kmalloc(sizeof *req); // freed in vfs_backend_finish
int ret;
*req = (struct vfs_op_request) {
.op = op,
.caller = process_current,
.backend = backend,
};
switch (backend->type) {
case VFS_BACK_ROOT:
ret = vfs_root_handler(req);
vfs_backend_finish(req, ret);
case VFS_BACK_USER:
process_current->state = PS_WAITS4FS;
if (backend->handler == NULL) {
// backend isn't ready yet, join the queue
assert(backend->queue == NULL); // TODO implement a proper queue
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_op_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_backend_finish(struct vfs_op_request *req, int ret) {
struct process *caller = req->caller;
if (req->op.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->op.type == VFSOP_OPEN)
kfree(req->op.open.path);
req->caller->state = PS_RUNNING;
regs_savereturn(&req->caller->regs, ret);
kfree(req);
process_switch(caller);
}
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