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lvm2/lib/locking/lvmlockd.h

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/*
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* Copyright (C) 2014-2015 Red Hat, Inc.
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*
* 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.
*/
#ifndef _LVMLOCKD_H
#define _LVMLOCKD_H
#include "libdaemon/client/config-util.h"
#include "libdaemon/client/daemon-client.h"
#include "lib/metadata/metadata-exported.h" /* is_lockd_type() */
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#define LOCKD_SANLOCK_LV_NAME "lvmlock"
/* lockd_lv flags */
#define LDLV_MODE_NO_SH 0x00000001
#define LDLV_PERSISTENT 0x00000002
#define LDLV_SH_EXISTS_OK 0x00000004
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/* lvmlockd result flags */
#define LD_RF_NO_LOCKSPACES 0x00000001
#define LD_RF_NO_GL_LS 0x00000002
#define LD_RF_WARN_GL_REMOVED 0x00000004
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#define LD_RF_DUP_GL_LS 0x00000008
#define LD_RF_NO_LM 0x00000010
#define LD_RF_SH_EXISTS 0x00000020
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/* lockd_state flags */
#define LDST_EX 0x00000001
#define LDST_SH 0x00000002
#define LDST_FAIL_REQUEST 0x00000004
#define LDST_FAIL_NOLS 0x00000008
#define LDST_FAIL_STARTING 0x00000010
#define LDST_FAIL_OTHER 0x00000020
#define LDST_FAIL (LDST_FAIL_REQUEST | LDST_FAIL_NOLS | LDST_FAIL_STARTING | LDST_FAIL_OTHER)
#ifdef LVMLOCKD_SUPPORT
locking: unify global lock for flock and lockd There have been two file locks used to protect lvm "global state": "ORPHANS" and "GLOBAL". Commands that used the ORPHAN flock in exclusive mode: pvcreate, pvremove, vgcreate, vgextend, vgremove, vgcfgrestore Commands that used the ORPHAN flock in shared mode: vgimportclone, pvs, pvscan, pvresize, pvmove, pvdisplay, pvchange, fullreport Commands that used the GLOBAL flock in exclusive mode: pvchange, pvscan, vgimportclone, vgscan Commands that used the GLOBAL flock in shared mode: pvscan --cache, pvs The ORPHAN lock covers the important cases of serializing the use of orphan PVs. It also partially covers the reporting of orphan PVs (although not correctly as explained below.) The GLOBAL lock doesn't seem to have a clear purpose (it may have eroded over time.) Neither lock correctly protects the VG namespace, or orphan PV properties. To simplify and correct these issues, the two separate flocks are combined into the one GLOBAL flock, and this flock is used from the locking sites that are in place for the lvmlockd global lock. The logic behind the lvmlockd (distributed) global lock is that any command that changes "global state" needs to take the global lock in ex mode. Global state in lvm is: the list of VG names, the set of orphan PVs, and any properties of orphan PVs. Reading this global state can use the global lock in sh mode to ensure it doesn't change while being reported. The locking of global state now looks like: lockd_global() previously named lockd_gl(), acquires the distributed global lock through lvmlockd. This is unchanged. It serializes distributed lvm commands that are changing global state. This is a no-op when lvmlockd is not in use. lockf_global() acquires an flock on a local file. It serializes local lvm commands that are changing global state. lock_global() first calls lockf_global() to acquire the local flock for global state, and if this succeeds, it calls lockd_global() to acquire the distributed lock for global state. Replace instances of lockd_gl() with lock_global(), so that the existing sites for lvmlockd global state locking are now also used for local file locking of global state. Remove the previous file locking calls lock_vol(GLOBAL) and lock_vol(ORPHAN). The following commands which change global state are now serialized with the exclusive global flock: pvchange (of orphan), pvresize (of orphan), pvcreate, pvremove, vgcreate, vgextend, vgremove, vgreduce, vgrename, vgcfgrestore, vgimportclone, vgmerge, vgsplit Commands that use a shared flock to read global state (and will be serialized against the prior list) are those that use process_each functions that are based on processing a list of all VG names, or all PVs. The list of all VGs or all PVs is global state and the shared lock prevents those lists from changing while the command is processing them. The ORPHAN lock previously attempted to produce an accurate listing of orphan PVs, but it was only acquired at the end of the command during the fake vg_read of the fake orphan vg. This is not when orphan PVs were determined; they were determined by elimination beforehand by processing all real VGs, and subtracting the PVs in the real VGs from the list of all PVs that had been identified during the initial scan. This is fixed by holding the single global lock in shared mode while processing all VGs to determine the list of orphan PVs.
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struct lvresize_params;
struct lvcreate_params;
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/* lvmlockd connection and communication */
void lvmlockd_set_socket(const char *sock);
void lvmlockd_set_use(int use);
int lvmlockd_use(void);
void lvmlockd_init(struct cmd_context *cmd);
void lvmlockd_connect(void);
void lvmlockd_disconnect(void);
/* vgcreate/vgremove use init/free */
int lockd_init_vg(struct cmd_context *cmd, struct volume_group *vg, const char *lock_type, int lv_lock_count);
int lockd_free_vg_before(struct cmd_context *cmd, struct volume_group *vg, int changing);
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void lockd_free_vg_final(struct cmd_context *cmd, struct volume_group *vg);
/* vgrename */
int lockd_rename_vg_before(struct cmd_context *cmd, struct volume_group *vg);
int lockd_rename_vg_final(struct cmd_context *cmd, struct volume_group *vg, int success);
/* start and stop the lockspace for a vg */
int lockd_start_vg(struct cmd_context *cmd, struct volume_group *vg, int start_init, int *exists);
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int lockd_stop_vg(struct cmd_context *cmd, struct volume_group *vg);
int lockd_start_wait(struct cmd_context *cmd);
/* locking */
locking: unify global lock for flock and lockd There have been two file locks used to protect lvm "global state": "ORPHANS" and "GLOBAL". Commands that used the ORPHAN flock in exclusive mode: pvcreate, pvremove, vgcreate, vgextend, vgremove, vgcfgrestore Commands that used the ORPHAN flock in shared mode: vgimportclone, pvs, pvscan, pvresize, pvmove, pvdisplay, pvchange, fullreport Commands that used the GLOBAL flock in exclusive mode: pvchange, pvscan, vgimportclone, vgscan Commands that used the GLOBAL flock in shared mode: pvscan --cache, pvs The ORPHAN lock covers the important cases of serializing the use of orphan PVs. It also partially covers the reporting of orphan PVs (although not correctly as explained below.) The GLOBAL lock doesn't seem to have a clear purpose (it may have eroded over time.) Neither lock correctly protects the VG namespace, or orphan PV properties. To simplify and correct these issues, the two separate flocks are combined into the one GLOBAL flock, and this flock is used from the locking sites that are in place for the lvmlockd global lock. The logic behind the lvmlockd (distributed) global lock is that any command that changes "global state" needs to take the global lock in ex mode. Global state in lvm is: the list of VG names, the set of orphan PVs, and any properties of orphan PVs. Reading this global state can use the global lock in sh mode to ensure it doesn't change while being reported. The locking of global state now looks like: lockd_global() previously named lockd_gl(), acquires the distributed global lock through lvmlockd. This is unchanged. It serializes distributed lvm commands that are changing global state. This is a no-op when lvmlockd is not in use. lockf_global() acquires an flock on a local file. It serializes local lvm commands that are changing global state. lock_global() first calls lockf_global() to acquire the local flock for global state, and if this succeeds, it calls lockd_global() to acquire the distributed lock for global state. Replace instances of lockd_gl() with lock_global(), so that the existing sites for lvmlockd global state locking are now also used for local file locking of global state. Remove the previous file locking calls lock_vol(GLOBAL) and lock_vol(ORPHAN). The following commands which change global state are now serialized with the exclusive global flock: pvchange (of orphan), pvresize (of orphan), pvcreate, pvremove, vgcreate, vgextend, vgremove, vgreduce, vgrename, vgcfgrestore, vgimportclone, vgmerge, vgsplit Commands that use a shared flock to read global state (and will be serialized against the prior list) are those that use process_each functions that are based on processing a list of all VG names, or all PVs. The list of all VGs or all PVs is global state and the shared lock prevents those lists from changing while the command is processing them. The ORPHAN lock previously attempted to produce an accurate listing of orphan PVs, but it was only acquired at the end of the command during the fake vg_read of the fake orphan vg. This is not when orphan PVs were determined; they were determined by elimination beforehand by processing all real VGs, and subtracting the PVs in the real VGs from the list of all PVs that had been identified during the initial scan. This is fixed by holding the single global lock in shared mode while processing all VGs to determine the list of orphan PVs.
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int lockd_global_create(struct cmd_context *cmd, const char *def_mode, const char *vg_lock_type);
int lockd_global(struct cmd_context *cmd, const char *def_mode);
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int lockd_vg(struct cmd_context *cmd, const char *vg_name, const char *def_mode,
uint32_t flags, uint32_t *lockd_state);
int lockd_vg_update(struct volume_group *vg);
int lockd_lv_name(struct cmd_context *cmd, struct volume_group *vg,
const char *lv_name, struct id *lv_id,
const char *lock_args, const char *def_mode, uint32_t flags);
int lockd_lv(struct cmd_context *cmd, struct logical_volume *lv,
const char *def_mode, uint32_t flags);
int lockd_lv_resize(struct cmd_context *cmd, struct logical_volume *lv,
const char *def_mode, uint32_t flags, struct lvresize_params *lp);
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/* lvcreate/lvremove use init/free */
int lockd_init_lv(struct cmd_context *cmd, struct volume_group *vg, struct logical_volume *lv,
struct lvcreate_params *lp);
int lockd_init_lv_args(struct cmd_context *cmd, struct volume_group *vg,
struct logical_volume *lv, const char *lock_type, const char **lock_args);
int lockd_free_lv(struct cmd_context *cmd, struct volume_group *vg,
const char *lv_name, struct id *lv_id, const char *lock_args);
const char *lockd_running_lock_type(struct cmd_context *cmd, int *found_multiple);
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int handle_sanlock_lv(struct cmd_context *cmd, struct volume_group *vg);
int lockd_lv_uses_lock(struct logical_volume *lv);
int lockd_lv_refresh(struct cmd_context *cmd, struct lvresize_params *lp);
int lockd_query_lv(struct cmd_context *cmd, struct logical_volume *lv, int *ex, int *sh);
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#else /* LVMLOCKD_SUPPORT */
static inline void lvmlockd_set_socket(const char *sock)
{
}
static inline void lvmlockd_set_use(int use)
{
}
static inline void lvmlockd_init(struct cmd_context *cmd)
{
}
static inline void lvmlockd_disconnect(void)
{
}
static inline void lvmlockd_connect(void)
{
}
static inline int lvmlockd_use(void)
{
return 0;
}
static inline int lockd_init_vg(struct cmd_context *cmd, struct volume_group *vg, const char *lock_type, int lv_lock_count)
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{
return 1;
}
static inline int lockd_free_vg_before(struct cmd_context *cmd, struct volume_group *vg, int changing)
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{
return 1;
}
static inline void lockd_free_vg_final(struct cmd_context *cmd, struct volume_group *vg)
{
return;
}
static inline int lockd_rename_vg_before(struct cmd_context *cmd, struct volume_group *vg)
{
return 1;
}
static inline int lockd_rename_vg_final(struct cmd_context *cmd, struct volume_group *vg, int success)
{
return 1;
}
static inline int lockd_start_vg(struct cmd_context *cmd, struct volume_group *vg, int start_init, int *exists)
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{
return 0;
}
static inline int lockd_stop_vg(struct cmd_context *cmd, struct volume_group *vg)
{
return 0;
}
static inline int lockd_start_wait(struct cmd_context *cmd)
{
return 0;
}
locking: unify global lock for flock and lockd There have been two file locks used to protect lvm "global state": "ORPHANS" and "GLOBAL". Commands that used the ORPHAN flock in exclusive mode: pvcreate, pvremove, vgcreate, vgextend, vgremove, vgcfgrestore Commands that used the ORPHAN flock in shared mode: vgimportclone, pvs, pvscan, pvresize, pvmove, pvdisplay, pvchange, fullreport Commands that used the GLOBAL flock in exclusive mode: pvchange, pvscan, vgimportclone, vgscan Commands that used the GLOBAL flock in shared mode: pvscan --cache, pvs The ORPHAN lock covers the important cases of serializing the use of orphan PVs. It also partially covers the reporting of orphan PVs (although not correctly as explained below.) The GLOBAL lock doesn't seem to have a clear purpose (it may have eroded over time.) Neither lock correctly protects the VG namespace, or orphan PV properties. To simplify and correct these issues, the two separate flocks are combined into the one GLOBAL flock, and this flock is used from the locking sites that are in place for the lvmlockd global lock. The logic behind the lvmlockd (distributed) global lock is that any command that changes "global state" needs to take the global lock in ex mode. Global state in lvm is: the list of VG names, the set of orphan PVs, and any properties of orphan PVs. Reading this global state can use the global lock in sh mode to ensure it doesn't change while being reported. The locking of global state now looks like: lockd_global() previously named lockd_gl(), acquires the distributed global lock through lvmlockd. This is unchanged. It serializes distributed lvm commands that are changing global state. This is a no-op when lvmlockd is not in use. lockf_global() acquires an flock on a local file. It serializes local lvm commands that are changing global state. lock_global() first calls lockf_global() to acquire the local flock for global state, and if this succeeds, it calls lockd_global() to acquire the distributed lock for global state. Replace instances of lockd_gl() with lock_global(), so that the existing sites for lvmlockd global state locking are now also used for local file locking of global state. Remove the previous file locking calls lock_vol(GLOBAL) and lock_vol(ORPHAN). The following commands which change global state are now serialized with the exclusive global flock: pvchange (of orphan), pvresize (of orphan), pvcreate, pvremove, vgcreate, vgextend, vgremove, vgreduce, vgrename, vgcfgrestore, vgimportclone, vgmerge, vgsplit Commands that use a shared flock to read global state (and will be serialized against the prior list) are those that use process_each functions that are based on processing a list of all VG names, or all PVs. The list of all VGs or all PVs is global state and the shared lock prevents those lists from changing while the command is processing them. The ORPHAN lock previously attempted to produce an accurate listing of orphan PVs, but it was only acquired at the end of the command during the fake vg_read of the fake orphan vg. This is not when orphan PVs were determined; they were determined by elimination beforehand by processing all real VGs, and subtracting the PVs in the real VGs from the list of all PVs that had been identified during the initial scan. This is fixed by holding the single global lock in shared mode while processing all VGs to determine the list of orphan PVs.
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static inline int lockd_global_create(struct cmd_context *cmd, const char *def_mode, const char *vg_lock_type)
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{
/*
* When lvm is built without lvmlockd support, creating a VG with
* a shared lock type should fail.
*/
if (is_lockd_type(vg_lock_type)) {
log_error("Using a shared lock type requires lvmlockd.");
return 0;
}
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return 1;
}
static inline int lockd_global(struct cmd_context *cmd, const char *def_mode)
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{
return 1;
}
static inline int lockd_vg(struct cmd_context *cmd, const char *vg_name, const char *def_mode,
uint32_t flags, uint32_t *lockd_state)
{
*lockd_state = 0;
return 1;
}
static inline int lockd_vg_update(struct volume_group *vg)
{
return 1;
}
static inline int lockd_lv_name(struct cmd_context *cmd, struct volume_group *vg,
const char *lv_name, struct id *lv_id,
const char *lock_args, const char *def_mode, uint32_t flags)
{
return 1;
}
static inline int lockd_lv(struct cmd_context *cmd, struct logical_volume *lv,
const char *def_mode, uint32_t flags)
{
return 1;
}
static inline int lockd_lv_resize(struct cmd_context *cmd, struct logical_volume *lv,
const char *def_mode, uint32_t flags, struct lvresize_params *lp)
{
return 1;
}
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static inline int lockd_init_lv(struct cmd_context *cmd, struct volume_group *vg,
struct logical_volume *lv, struct lvcreate_params *lp)
{
return 1;
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}
static inline int lockd_init_lv_args(struct cmd_context *cmd, struct volume_group *vg,
struct logical_volume *lv, const char *lock_type, const char **lock_args)
{
return 1;
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}
static inline int lockd_free_lv(struct cmd_context *cmd, struct volume_group *vg,
const char *lv_name, struct id *lv_id, const char *lock_args)
{
return 1;
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}
static inline const char *lockd_running_lock_type(struct cmd_context *cmd, int *found_multiple)
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{
log_error("Using a shared lock type requires lvmlockd.");
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return NULL;
}
static inline int handle_sanlock_lv(struct cmd_context *cmd, struct volume_group *vg)
{
return 0;
}
static inline int lockd_lv_uses_lock(struct logical_volume *lv)
{
return 0;
}
static inline int lockd_lv_refresh(struct cmd_context *cmd, struct lvresize_params *lp)
{
return 0;
}
static inline int lockd_query_lv(struct cmd_context *cmd, struct logical_volume *lv, int *ex, int *sh)
{
return 0;
}
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#endif /* LVMLOCKD_SUPPORT */
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#endif /* _LVMLOCKD_H */