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