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lvm2/lib/mm/memlock.h
Zdenek Kabelac b1bcff7424 Critical section
New strategy for memory locking to decrease the number of call to
to un/lock memory when processing critical lvm functions.

Introducing functions for critical section.

Inside the critical section - memory is always locked.
When leaving the critical section, the memory stays locked
until memlock_unlock() is called - this happens with
sync_local_dev_names() and sync_dev_names() function call.

memlock_reset() is needed to reset locking numbers after fork
(polldaemon).

The patch itself is mostly rename:

memlock_inc  -> critical_section_inc
memlock_dec  -> critical_section_dec
memlock      -> critical_section

Daemons (clmvd, dmevent) are using memlock_daemon_inc&dec
(mlockall()) thus they will never release or relock memory they've
already locked memory.

Macros sync_local_dev_names() and sync_dev_names() are functions.
It's better for debugging - and also we do not need to add memlock.h
to locking.h header (for memlock_unlock() prototyp).
2011-02-18 14:16:11 +00:00

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/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2011 Red Hat, Inc. All rights reserved.
*
* This file is part of LVM2.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License v.2.1.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef LVM_MEMLOCK_H
#define LVM_MEMLOCK_H
struct cmd_context;
void critical_section_inc(struct cmd_context *cmd);
void critical_section_dec(struct cmd_context *cmd);
int critical_section(void);
void memlock_inc_daemon(struct cmd_context *cmd);
void memlock_dec_daemon(struct cmd_context *cmd);
void memlock_init(struct cmd_context *cmd);
void memlock_reset(void);
void memlock_unlock(struct cmd_context *cmd);
#endif