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#pragma once
#include <kernel/types.h>
#include <shared/ring.h>
#include <stdbool.h>
#include <stddef.h>
struct ReqQueue {
VfsReq *head;
};
struct VfsBackend {
/* amount of using references
* VfsMount
* VfsReq
* Handle
* once it reaches 0, it'll never increase */
size_t usehcnt; /* VfsMount */
bool is_user;
union {
struct {
Proc *handler;
ReqQueue queue; /* kernel backends keep their own queues */
/* amount of processes that control this backend
* won't ever increase if it becomes 0 */
size_t provhcnt;
} user;
struct {
void (*accept)(VfsReq *);
void (*cleanup)(VfsBackend *);
void *data;
} kern;
};
};
/* describes an in-progress vfs call */
struct VfsReq {
enum vfs_op type;
struct {
bool kern; // if false: use .buf ; if true: use .buf_kern
union {
char __user *buf;
char *buf_kern;
};
size_t len;
} input;
struct {
char __user *buf;
size_t len;
} output;
// TODO why doesn't this just have a reference to the handle?
void __user *id; // handle.file.id
long offset;
int flags;
Proc *caller;
VfsBackend *backend;
VfsReq *reqqueue_next;
};
/** Assigns the vfs_request to the caller, and dispatches the call */
void vfsreq_dispatchcopy(VfsReq);
void vfsreq_finish(VfsReq*, char __user *stored, long ret, int flags, Proc *handler);
static inline void vfsreq_finish_short(VfsReq *req, long ret) {
vfsreq_finish(req, (void __user *)ret, ret, 0, NULL);
}
/** Try to accept an enqueued request */
void vfsback_useraccept(VfsReq *);
/** Decrements the "user" reference count. */
void vfsback_userdown(VfsBackend *);
/** Decrements the "provider" reference count. */
void vfsback_provdown(VfsBackend *);
void reqqueue_init(ReqQueue *q);
void reqqueue_join(ReqQueue *q, VfsReq *req);
VfsReq *reqqueue_pop(ReqQueue *q);
/** If there are any pending read requests, and the ring buffer isn't empty,
* fulfill them all with a single read. */
void reqqueue_ringreadall(ReqQueue *q, ring_t *r);
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