mars/kernel/lib_mapfree.h

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/*
* MARS Long Distance Replication Software
*
* This file is part of MARS project: http://schoebel.github.io/mars/
*
* Copyright (C) 2010-2014 Thomas Schoebel-Theuer
* Copyright (C) 2011-2014 1&1 Internet AG
*
* 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_MAPFREE_H
#define MARS_LIB_MAPFREE_H
/* Mapfree infrastructure.
*
* Purposes:
*
* 1) Open files only once when possible, do ref-counting on struct mapfree_info
*
* 2) Automatically call invalidate_mapping_pages() in the background on
* "unused" areas to free resources.
* Used areas can be indicated by calling mapfree_set() frequently.
* Usage model: tailored to sequential logfiles.
*
* 3) Do it all in a completely decoupled manner, in order to prevent resource deadlocks.
*
* 4) Also to prevent deadlocks: always set mapping_set_gfp_mask() accordingly.
*/
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#include <linux/rwsem.h>
#include "mars.h"
extern int mapfree_period_sec;
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extern int mapfree_grace_keep_mb;
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enum dirty_stage {
DIRTY_SUBMITTED,
DIRTY_COMPLETED,
DIRTY_FINISHED,
/* Keep this the last element */
DIRTY_MAX
};
struct dirty_length {
rwlock_t dl_lock;
loff_t dl_length;
};
struct mapfree_info {
struct list_head mf_head;
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struct list_head mf_dirty_anchor;
char *mf_name;
struct file *mf_filp;
int mf_flags;
int mf_mode;
atomic_t mf_count;
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struct rw_semaphore mf_mutex;
loff_t mf_min[2];
loff_t mf_last;
loff_t mf_max;
long long mf_jiffies;
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struct dirty_length mf_length[DIRTY_MAX];
};
struct mapfree_info *mapfree_get(const char *filename, int flags);
void mapfree_put(struct mapfree_info *mf);
void mapfree_set(struct mapfree_info *mf, loff_t min, loff_t max);
void mapfree_pages(struct mapfree_info *mf, int grace_keep);
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////////////////// dirty IOs in append mode //////////////////
void mf_dirty_append(struct mapfree_info *mf, enum dirty_stage stage, loff_t newlen);
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void mf_dirty_reduce(struct mapfree_info *mf, enum dirty_stage stage, loff_t newlen);
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loff_t mf_dirty_length(struct mapfree_info *mf, enum dirty_stage stage);
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////////////////// dirty IOs on the fly //////////////////
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loff_t mf_get_any_dirty(const char *filename, int stage);
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////////////////// module init stuff /////////////////////////
int __init init_mars_mapfree(void);
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void exit_mars_mapfree(void);
#endif