/* * MARS Long Distance Replication Software * * This file is part of MARS project: http://schoebel.github.io/mars/ * * Copyright (C) 2010-2022 Thomas Schoebel-Theuer * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #ifndef MARS_LIB_QIO_RW_H #define MARS_LIB_QIO_RW_H #include "brick.h" #include "lamport.h" #include #include #include /* Minor abstraction to/from the kernel IO interface. * (a) hopefully this interface will remain stable until MARS * can go upstream. Only the implementation in lib_qio_rw.c * should need to cope with kernel versions. * (b) keep the door open for alternative kernel adaptors, maybe even * more direct access to the page cache, or some future developments. * * Architectural differences to kernel_{read,write}(): * (1) The interface is as similar as possible, for long-term * code maintenance. * (2) Submission should work as non-blocking as possible ;) * (3) *_wait() operations are supposed to block any (separate) * kernel threads. * Any information transfer between submission and (internal) * completion path(s) goes via *private, which should always * start with prefix "struct qio_rw_...", but may append further * external items. */ enum qio_rw_phase { QIO_RW_NOTSTARTED, QIO_RW_RD_STARTED, QIO_RW_WR_STARTED, QIO_RW_WAITING, QIO_RW_COMPLETED, }; struct qio_rw { union { struct { /* from general kernel infrastructure */ struct kiocb kiocb; struct iov_iter from_to; /* from io_uring */ /* currently unused: struct io_async_rw rw; */ /* private */ ssize_t submission_ret; ssize_t completion_ret; enum qio_rw_phase qio_phase; }; }; }; struct qio_rw_operations { ssize_t (*qio_read_start)(struct file *file, void *buf, size_t count, loff_t *pos, void *private, bool nowait); ssize_t (*qio_write_start)(struct file *file, void *buf, size_t count, loff_t *pos, void *private, bool wait_for_sync); ssize_t (*qio_rw_wait)(struct file *file, bool is_write, bool needs_write_sync, void *private); }; extern const struct qio_rw_operations qio_rw_operations; extern void init_qio_rw(struct qio_rw *qio_rw); extern void exit_qio_rw(struct qio_rw *qio_rw); #endif