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lvm2/lib/locking/locking.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_LOCKING_H
#define _LVM_LOCKING_H
#include "uuid.h"
#include "config.h"
int init_locking(int type, struct cmd_context *cmd, int suppress_messages);
void fin_locking(void);
void reset_locking(void);
int vg_write_lock_held(void);
int locking_is_clustered(void);
int remote_lock_held(const char *vol, int *exclusive);
/*
* LCK_VG:
* Lock/unlock on-disk volume group data.
* Use VG_ORPHANS to lock all orphan PVs.
* Use VG_GLOBAL as a global lock and to wipe the internal cache.
* char *vol holds volume group name.
* Set LCK_CACHE flag when manipulating 'vol' metadata in the internal cache.
* (Like commit, revert or invalidate metadata.)
* If more than one lock needs to be held simultaneously, they must be
* acquired in alphabetical order of 'vol' (to avoid deadlocks), with
* VG_ORPHANS last.
*
* LCK_LV:
* Lock/unlock an individual logical volume
* char *vol holds lvid
*/
int lock_vol(struct cmd_context *cmd, const char *vol, uint32_t flags);
/*
* Internal locking representation.
* LCK_VG: Uses prefix V_ unless the vol begins with # (i.e. #global or #orphans)
* or the LCK_CACHE flag is set when it uses the prefix P_.
* If LCK_CACHE is set, we do not take out a real lock.
* NB In clustered situations, LCK_CACHE is not propagated directly to remote nodes.
* (It can be deduced from lock name.)
*/
/*
* Does the LVM1 driver have this VG active?
*/
int check_lvm1_vg_inactive(struct cmd_context *cmd, const char *vgname);
/*
* Lock type - these numbers are the same as VMS and the IBM DLM
*/
#define LCK_TYPE_MASK 0x00000007U
#define LCK_NULL 0x00000000U /* LCK$_NLMODE */
#define LCK_READ 0x00000001U /* LCK$_CRMODE */
/* LCK$_CWMODE */
#define LCK_PREAD 0x00000003U /* LCK$_PRMODE */
#define LCK_WRITE 0x00000004U /* LCK$_PWMODE */
#define LCK_EXCL 0x00000005U /* LCK$_EXMODE */
#define LCK_UNLOCK 0x00000006U /* This is ours */
/*
* Lock flags - these numbers are the same as DLM
*/
#define LCKF_NOQUEUE 0x00000001U /* LKF$_NOQUEUE */
#define LCKF_CONVERT 0x00000004U /* LKF$_CONVERT */
/*
* Lock scope
*/
#define LCK_SCOPE_MASK 0x00000008U
#define LCK_VG 0x00000000U
#define LCK_LV 0x00000008U
/*
* Lock bits
*/
#define LCK_NONBLOCK 0x00000010U /* Don't block waiting for lock? */
#define LCK_HOLD 0x00000020U /* Hold lock when lock_vol returns? */
#define LCK_LOCAL 0x00000040U /* Don't propagate to other nodes */
#define LCK_CLUSTER_VG 0x00000080U /* VG is clustered */
#define LCK_CACHE 0x00000100U /* Operation on cache only using P_ lock */
#define LCK_ORIGIN_ONLY 0x00000200U /* Operation should bypass any snapshots */
/*
* Additional lock bits for cluster communication via args[1]
*/
#define LCK_PARTIAL_MODE 0x01 /* Partial activation? */
#define LCK_MIRROR_NOSYNC_MODE 0x02 /* Mirrors don't require sync */
#define LCK_DMEVENTD_MONITOR_MODE 0x04 /* Register with dmeventd */
#define LCK_CONVERT 0x08 /* Convert existing lock */
#define LCK_ORIGIN_ONLY_MODE 0x20 /* Same as above */
/*
* Special cases of VG locks.
*/
#define VG_ORPHANS "#orphans"
#define VG_GLOBAL "#global"
#define VG_SYNC_NAMES "#sync_names"
/*
* Common combinations
*/
#define LCK_NONE (LCK_VG | LCK_NULL)
#define LCK_VG_READ (LCK_VG | LCK_READ | LCK_HOLD)
#define LCK_VG_WRITE (LCK_VG | LCK_WRITE | LCK_HOLD)
#define LCK_VG_UNLOCK (LCK_VG | LCK_UNLOCK)
#define LCK_VG_DROP_CACHE (LCK_VG | LCK_WRITE | LCK_CACHE)
/* FIXME: LCK_HOLD abused here */
#define LCK_VG_COMMIT (LCK_VG | LCK_WRITE | LCK_CACHE | LCK_HOLD)
#define LCK_VG_REVERT (LCK_VG | LCK_READ | LCK_CACHE | LCK_HOLD)
#define LCK_VG_BACKUP (LCK_VG | LCK_CACHE)
#define LCK_LV_EXCLUSIVE (LCK_LV | LCK_EXCL)
#define LCK_LV_SUSPEND (LCK_LV | LCK_WRITE)
#define LCK_LV_RESUME (LCK_LV | LCK_UNLOCK)
#define LCK_LV_ACTIVATE (LCK_LV | LCK_READ)
#define LCK_LV_DEACTIVATE (LCK_LV | LCK_NULL)
#define LCK_MASK (LCK_TYPE_MASK | LCK_SCOPE_MASK)
#define LCK_LV_CLUSTERED(lv) \
(vg_is_clustered((lv)->vg) ? LCK_CLUSTER_VG : 0)
#define lock_lv_vol(cmd, lv, flags) \
(find_replicator_vgs((lv)) ? \
lock_vol(cmd, (lv)->lvid.s, flags | LCK_LV_CLUSTERED(lv)) : \
0)
#define unlock_vg(cmd, vol) \
do { \
if (is_real_vg(vol)) \
sync_dev_names(cmd); \
lock_vol(cmd, vol, LCK_VG_UNLOCK); \
} while (0)
#define unlock_and_free_vg(cmd, vg, vol) \
do { \
unlock_vg(cmd, vol); \
free_vg(vg); \
} while (0)
#define resume_lv(cmd, lv) lock_lv_vol(cmd, lv, LCK_LV_RESUME)
#define resume_lv_origin(cmd, lv) lock_lv_vol(cmd, lv, LCK_LV_RESUME | LCK_ORIGIN_ONLY)
#define suspend_lv(cmd, lv) lock_lv_vol(cmd, lv, LCK_LV_SUSPEND | LCK_HOLD)
#define suspend_lv_origin(cmd, lv) lock_lv_vol(cmd, lv, LCK_LV_SUSPEND | LCK_HOLD | LCK_ORIGIN_ONLY)
#define deactivate_lv(cmd, lv) lock_lv_vol(cmd, lv, LCK_LV_DEACTIVATE)
#define activate_lv(cmd, lv) lock_lv_vol(cmd, lv, LCK_LV_ACTIVATE | LCK_HOLD)
#define activate_lv_excl(cmd, lv) \
lock_lv_vol(cmd, lv, LCK_LV_EXCLUSIVE | LCK_HOLD)
#define activate_lv_local(cmd, lv) \
lock_lv_vol(cmd, lv, LCK_LV_ACTIVATE | LCK_HOLD | LCK_LOCAL)
#define deactivate_lv_local(cmd, lv) \
lock_lv_vol(cmd, lv, LCK_LV_DEACTIVATE | LCK_LOCAL)
#define drop_cached_metadata(vg) \
lock_vol((vg)->cmd, (vg)->name, LCK_VG_DROP_CACHE)
#define remote_commit_cached_metadata(vg) \
lock_vol((vg)->cmd, (vg)->name, LCK_VG_COMMIT)
#define remote_revert_cached_metadata(vg) \
lock_vol((vg)->cmd, (vg)->name, LCK_VG_REVERT)
#define remote_backup_metadata(vg) \
lock_vol((vg)->cmd, (vg)->name, LCK_VG_BACKUP)
/* cleanup later
#define sync_local_dev_names(cmd) \
lock_vol(cmd, VG_SYNC_NAMES, LCK_NONE | LCK_CACHE | LCK_LOCAL)
#define sync_dev_names(cmd) \
lock_vol(cmd, VG_SYNC_NAMES, LCK_NONE | LCK_CACHE)
*/
int sync_local_dev_names(struct cmd_context* cmd);
int sync_dev_names(struct cmd_context* cmd);
/* Process list of LVs */
int suspend_lvs(struct cmd_context *cmd, struct dm_list *lvs);
int resume_lvs(struct cmd_context *cmd, struct dm_list *lvs);
int activate_lvs(struct cmd_context *cmd, struct dm_list *lvs, unsigned exclusive);
/* Interrupt handling */
void sigint_clear(void);
void sigint_allow(void);
void sigint_restore(void);
int sigint_caught(void);
#endif
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