[linux-2.6-block.git] / fs / gfs2 / glock.h

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * 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 General Public License version 2.
 */

#ifndef __GLOCK_DOT_H__
#define __GLOCK_DOT_H__

#include <linux/sched.h>
#include <linux/parser.h>
#include "incore.h"
#include "util.h"

/* Options for hostdata parser */

enum {
	Opt_jid,
	Opt_id,
	Opt_first,
	Opt_nodir,
	Opt_err,
};

/*
 * lm_lockname types
 */

#define LM_TYPE_RESERVED	0x00
#define LM_TYPE_NONDISK		0x01
#define LM_TYPE_INODE		0x02
#define LM_TYPE_RGRP		0x03
#define LM_TYPE_META		0x04
#define LM_TYPE_IOPEN		0x05
#define LM_TYPE_FLOCK		0x06
#define LM_TYPE_PLOCK		0x07
#define LM_TYPE_QUOTA		0x08
#define LM_TYPE_JOURNAL		0x09

/*
 * lm_lock() states
 *
 * SHARED is compatible with SHARED, not with DEFERRED or EX.
 * DEFERRED is compatible with DEFERRED, not with SHARED or EX.
 */

#define LM_ST_UNLOCKED		0
#define LM_ST_EXCLUSIVE		1
#define LM_ST_DEFERRED		2
#define LM_ST_SHARED		3

/*
 * lm_lock() flags
 *
 * LM_FLAG_TRY
 * Don't wait to acquire the lock if it can't be granted immediately.
 *
 * LM_FLAG_TRY_1CB
 * Send one blocking callback if TRY is set and the lock is not granted.
 *
 * LM_FLAG_NOEXP
 * GFS sets this flag on lock requests it makes while doing journal recovery.
 * These special requests should not be blocked due to the recovery like
 * ordinary locks would be.
 *
 * LM_FLAG_ANY
 * A SHARED request may also be granted in DEFERRED, or a DEFERRED request may
 * also be granted in SHARED.  The preferred state is whichever is compatible
 * with other granted locks, or the specified state if no other locks exist.
 *
 * LM_FLAG_PRIORITY
 * Override fairness considerations.  Suppose a lock is held in a shared state
 * and there is a pending request for the deferred state.  A shared lock
 * request with the priority flag would be allowed to bypass the deferred
 * request and directly join the other shared lock.  A shared lock request
 * without the priority flag might be forced to wait until the deferred
 * requested had acquired and released the lock.
 */

#define LM_FLAG_TRY		0x0001
#define LM_FLAG_TRY_1CB		0x0002
#define LM_FLAG_NOEXP		0x0004
#define LM_FLAG_ANY		0x0008
#define LM_FLAG_PRIORITY	0x0010
#define GL_ASYNC		0x0040
#define GL_EXACT		0x0080
#define GL_SKIP			0x0100
#define GL_NOCACHE		0x0400
  
/*
 * lm_async_cb return flags
 *
 * LM_OUT_ST_MASK
 * Masks the lower two bits of lock state in the returned value.
 *
 * LM_OUT_CANCELED
 * The lock request was canceled.
 *
 */

#define LM_OUT_ST_MASK		0x00000003
#define LM_OUT_CANCELED		0x00000008
#define LM_OUT_ERROR		0x00000004

/*
 * lm_recovery_done() messages
 */

#define LM_RD_GAVEUP		308
#define LM_RD_SUCCESS		309

#define GLR_TRYFAILED		13

#define GL_GLOCK_MAX_HOLD        (long)(HZ / 5)
#define GL_GLOCK_DFT_HOLD        (long)(HZ / 5)
#define GL_GLOCK_MIN_HOLD        (long)(10)
#define GL_GLOCK_HOLD_INCR       (long)(HZ / 20)
#define GL_GLOCK_HOLD_DECR       (long)(HZ / 40)

struct lm_lockops {
	const char *lm_proto_name;
	int (*lm_mount) (struct gfs2_sbd *sdp, const char *table);
	void (*lm_first_done) (struct gfs2_sbd *sdp);
	void (*lm_recovery_result) (struct gfs2_sbd *sdp, unsigned int jid,
				    unsigned int result);
	void (*lm_unmount) (struct gfs2_sbd *sdp);
	void (*lm_withdraw) (struct gfs2_sbd *sdp);
	void (*lm_put_lock) (struct gfs2_glock *gl);
	int (*lm_lock) (struct gfs2_glock *gl, unsigned int req_state,
			unsigned int flags);
	void (*lm_cancel) (struct gfs2_glock *gl);
	const match_table_t *lm_tokens;
};

extern struct workqueue_struct *gfs2_delete_workqueue;
static inline struct gfs2_holder *gfs2_glock_is_locked_by_me(struct gfs2_glock *gl)
{
	struct gfs2_holder *gh;
	struct pid *pid;

	/* Look in glock's list of holders for one with current task as owner */
	spin_lock(&gl->gl_lockref.lock);
	pid = task_pid(current);
	list_for_each_entry(gh, &gl->gl_holders, gh_list) {
		if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
			break;
		if (gh->gh_owner_pid == pid)
			goto out;
	}
	gh = NULL;
out:
	spin_unlock(&gl->gl_lockref.lock);

	return gh;
}

static inline int gfs2_glock_is_held_excl(struct gfs2_glock *gl)
{
	return gl->gl_state == LM_ST_EXCLUSIVE;
}

static inline int gfs2_glock_is_held_dfrd(struct gfs2_glock *gl)
{
	return gl->gl_state == LM_ST_DEFERRED;
}

static inline int gfs2_glock_is_held_shrd(struct gfs2_glock *gl)
{
	return gl->gl_state == LM_ST_SHARED;
}

static inline struct address_space *gfs2_glock2aspace(struct gfs2_glock *gl)
{
	if (gl->gl_ops->go_flags & GLOF_ASPACE)
		return (struct address_space *)(gl + 1);
	return NULL;
}

extern int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
			  const struct gfs2_glock_operations *glops,
			  int create, struct gfs2_glock **glp);
extern void gfs2_glock_hold(struct gfs2_glock *gl);
extern void gfs2_glock_put(struct gfs2_glock *gl);
extern void gfs2_glock_queue_put(struct gfs2_glock *gl);
extern void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state,
			     u16 flags, struct gfs2_holder *gh);
extern void gfs2_holder_reinit(unsigned int state, u16 flags,
			       struct gfs2_holder *gh);
extern void gfs2_holder_uninit(struct gfs2_holder *gh);
extern int gfs2_glock_nq(struct gfs2_holder *gh);
extern int gfs2_glock_poll(struct gfs2_holder *gh);
extern int gfs2_glock_wait(struct gfs2_holder *gh);
extern void gfs2_glock_dq(struct gfs2_holder *gh);
extern void gfs2_glock_dq_wait(struct gfs2_holder *gh);
extern void gfs2_glock_dq_uninit(struct gfs2_holder *gh);
extern int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
			     const struct gfs2_glock_operations *glops,
			     unsigned int state, u16 flags,
			     struct gfs2_holder *gh);
extern int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs);
extern void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs);
extern void gfs2_dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
#define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { gfs2_dump_glock(NULL, gl); BUG(); } } while(0)
extern __printf(2, 3)
void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...);

/**
 * gfs2_glock_nq_init - initialize a holder and enqueue it on a glock
 * @gl: the glock
 * @state: the state we're requesting
 * @flags: the modifier flags
 * @gh: the holder structure
 *
 * Returns: 0, GLR_*, or errno
 */

static inline int gfs2_glock_nq_init(struct gfs2_glock *gl,
				     unsigned int state, u16 flags,
				     struct gfs2_holder *gh)
{
	int error;

	gfs2_holder_init(gl, state, flags, gh);

	error = gfs2_glock_nq(gh);
	if (error)
		gfs2_holder_uninit(gh);

	return error;
}

extern void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state);
extern void gfs2_glock_complete(struct gfs2_glock *gl, int ret);
extern void gfs2_gl_hash_clear(struct gfs2_sbd *sdp);
extern void gfs2_glock_finish_truncate(struct gfs2_inode *ip);
extern void gfs2_glock_thaw(struct gfs2_sbd *sdp);
extern void gfs2_glock_add_to_lru(struct gfs2_glock *gl);
extern void gfs2_glock_free(struct gfs2_glock *gl);

extern int __init gfs2_glock_init(void);
extern void gfs2_glock_exit(void);

extern int gfs2_create_debugfs_file(struct gfs2_sbd *sdp);
extern void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp);
extern int gfs2_register_debugfs(void);
extern void gfs2_unregister_debugfs(void);

extern const struct lm_lockops gfs2_dlm_ops;

static inline void gfs2_holder_mark_uninitialized(struct gfs2_holder *gh)
{
	gh->gh_gl = NULL;
}

static inline bool gfs2_holder_initialized(struct gfs2_holder *gh)
{
	return gh->gh_gl;
}

/**
 * glock_set_object - set the gl_object field of a glock
 * @gl: the glock
 * @object: the object
 */
static inline void glock_set_object(struct gfs2_glock *gl, void *object)
{
	spin_lock(&gl->gl_lockref.lock);
	if (gfs2_assert_warn(gl->gl_name.ln_sbd, gl->gl_object == NULL))
		gfs2_dump_glock(NULL, gl);
	gl->gl_object = object;
	spin_unlock(&gl->gl_lockref.lock);
}

/**
 * glock_clear_object - clear the gl_object field of a glock
 * @gl: the glock
 * @object: the object
 *
 * I'd love to similarly add this:
 *	else if (gfs2_assert_warn(gl->gl_sbd, gl->gl_object == object))
 *		gfs2_dump_glock(NULL, gl);
 * Unfortunately, that's not possible because as soon as gfs2_delete_inode
 * frees the block in the rgrp, another process can reassign it for an I_NEW
 * inode in gfs2_create_inode because that calls new_inode, not gfs2_iget.
 * That means gfs2_delete_inode may subsequently try to call this function
 * for a glock that's already pointing to a brand new inode. If we clear the
 * new inode's gl_object, we'll introduce metadata corruption. Function
 * gfs2_delete_inode calls clear_inode which calls gfs2_clear_inode which also
 * tries to clear gl_object, so it's more than just gfs2_delete_inode.
 *
 */
static inline void glock_clear_object(struct gfs2_glock *gl, void *object)
{
	spin_lock(&gl->gl_lockref.lock);
	if (gl->gl_object == object)
		gl->gl_object = NULL;
	spin_unlock(&gl->gl_lockref.lock);
}

#endif /* __GLOCK_DOT_H__ */
Commit	Line	Data
b3b94faa DT	1	/*
b3b94faa DT	2	* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
3a8a9a10	3	* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
b3b94faa DT	4	*
	5	* This copyrighted material is made available to anyone wishing to use,
	6	* modify, copy, or redistribute it subject to the terms and conditions
e9fc2aa0	7	* of the GNU General Public License version 2.
b3b94faa DT	8	*/
	9
	10	#ifndef __GLOCK_DOT_H__
	11	#define __GLOCK_DOT_H__
	12
e8edc6e0	13	#include <linux/sched.h>
f057f6cd	14	#include <linux/parser.h>
f2f7ba52	15	#include "incore.h"
df3d87bd	16	#include "util.h"
f2f7ba52	17
f057f6cd SW	18	/* Options for hostdata parser */
	19
	20	enum {
	21	Opt_jid,
	22	Opt_id,
	23	Opt_first,
	24	Opt_nodir,
	25	Opt_err,
	26	};
	27
	28	/*
	29	* lm_lockname types
	30	*/
	31
	32	#define LM_TYPE_RESERVED 0x00
	33	#define LM_TYPE_NONDISK 0x01
	34	#define LM_TYPE_INODE 0x02
	35	#define LM_TYPE_RGRP 0x03
	36	#define LM_TYPE_META 0x04
	37	#define LM_TYPE_IOPEN 0x05
	38	#define LM_TYPE_FLOCK 0x06
	39	#define LM_TYPE_PLOCK 0x07
	40	#define LM_TYPE_QUOTA 0x08
	41	#define LM_TYPE_JOURNAL 0x09
	42
	43	/*
	44	* lm_lock() states
	45	*
	46	* SHARED is compatible with SHARED, not with DEFERRED or EX.
	47	* DEFERRED is compatible with DEFERRED, not with SHARED or EX.
	48	*/
	49
	50	#define LM_ST_UNLOCKED 0
	51	#define LM_ST_EXCLUSIVE 1
	52	#define LM_ST_DEFERRED 2
	53	#define LM_ST_SHARED 3
	54
	55	/*
	56	* lm_lock() flags
	57	*
	58	* LM_FLAG_TRY
	59	* Don't wait to acquire the lock if it can't be granted immediately.
	60	*
	61	* LM_FLAG_TRY_1CB
	62	* Send one blocking callback if TRY is set and the lock is not granted.
	63	*
	64	* LM_FLAG_NOEXP
	65	* GFS sets this flag on lock requests it makes while doing journal recovery.
	66	* These special requests should not be blocked due to the recovery like
	67	* ordinary locks would be.
	68	*
	69	* LM_FLAG_ANY
	70	* A SHARED request may also be granted in DEFERRED, or a DEFERRED request may
	71	* also be granted in SHARED. The preferred state is whichever is compatible
	72	* with other granted locks, or the specified state if no other locks exist.
	73	*
	74	* LM_FLAG_PRIORITY
	75	* Override fairness considerations. Suppose a lock is held in a shared state
	76	* and there is a pending request for the deferred state. A shared lock
	77	* request with the priority flag would be allowed to bypass the deferred
	78	* request and directly join the other shared lock. A shared lock request
	79	* without the priority flag might be forced to wait until the deferred
	80	* requested had acquired and released the lock.
	81	*/
82
b58bf407 BP	83	#define LM_FLAG_TRY 0x0001
	84	#define LM_FLAG_TRY_1CB 0x0002
	85	#define LM_FLAG_NOEXP 0x0004
	86	#define LM_FLAG_ANY 0x0008
	87	#define LM_FLAG_PRIORITY 0x0010
	88	#define GL_ASYNC 0x0040
	89	#define GL_EXACT 0x0080
	90	#define GL_SKIP 0x0100
	91	#define GL_NOCACHE 0x0400
f057f6cd SW	92
f057f6cd SW	93	/*
921169ca	94	* lm_async_cb return flags
f057f6cd SW	95	*
	96	* LM_OUT_ST_MASK
	97	* Masks the lower two bits of lock state in the returned value.
	98	*
	99	* LM_OUT_CANCELED
	100	* The lock request was canceled.
	101	*
f057f6cd SW	102	*/
	103
	104	#define LM_OUT_ST_MASK 0x00000003
	105	#define LM_OUT_CANCELED 0x00000008
921169ca	106	#define LM_OUT_ERROR 0x00000004
f057f6cd SW	107
	108	/*
	109	* lm_recovery_done() messages
	110	*/
	111
	112	#define LM_RD_GAVEUP 308
	113	#define LM_RD_SUCCESS 309
	114
	115	#define GLR_TRYFAILED 13
	116
7cf8dcd3 BP	117	#define GL_GLOCK_MAX_HOLD (long)(HZ / 5)
	118	#define GL_GLOCK_DFT_HOLD (long)(HZ / 5)
	119	#define GL_GLOCK_MIN_HOLD (long)(10)
	120	#define GL_GLOCK_HOLD_INCR (long)(HZ / 20)
	121	#define GL_GLOCK_HOLD_DECR (long)(HZ / 40)
	122
f057f6cd SW	123	struct lm_lockops {
f057f6cd SW	124	const char *lm_proto_name;
e0c2a9aa DT	125	int (lm_mount) (struct gfs2_sbd sdp, const char *table);
	126	void (lm_first_done) (struct gfs2_sbd sdp);
	127	void (lm_recovery_result) (struct gfs2_sbd sdp, unsigned int jid,
	128	unsigned int result);
	129	void (lm_unmount) (struct gfs2_sbd sdp);
f057f6cd	130	void (lm_withdraw) (struct gfs2_sbd sdp);
bc015cb8	131	void (lm_put_lock) (struct gfs2_glock gl);
921169ca SW	132	int (lm_lock) (struct gfs2_glock gl, unsigned int req_state,
921169ca SW	133	unsigned int flags);
f057f6cd SW	134	void (lm_cancel) (struct gfs2_glock gl);
	135	const match_table_t *lm_tokens;
	136	};
	137
b94a170e	138	extern struct workqueue_struct *gfs2_delete_workqueue;
7afd88d9	139	static inline struct gfs2_holder gfs2_glock_is_locked_by_me(struct gfs2_glock gl)
b3b94faa DT	140	{
b3b94faa DT	141	struct gfs2_holder *gh;
b1e058da	142	struct pid *pid;
b3b94faa DT	143
b3b94faa DT	144	/* Look in glock's list of holders for one with current task as owner */
f3dd1649	145	spin_lock(&gl->gl_lockref.lock);
b1e058da	146	pid = task_pid(current);
b3b94faa	147	list_for_each_entry(gh, &gl->gl_holders, gh_list) {
6802e340 SW	148	if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
6802e340 SW	149	break;
7afd88d9 SW	150	if (gh->gh_owner_pid == pid)
7afd88d9 SW	151	goto out;
b3b94faa	152	}
7afd88d9 SW	153	gh = NULL;
7afd88d9 SW	154	out:
f3dd1649	155	spin_unlock(&gl->gl_lockref.lock);
b3b94faa	156
7afd88d9	157	return gh;
b3b94faa DT	158	}
	159
	160	static inline int gfs2_glock_is_held_excl(struct gfs2_glock *gl)
	161	{
50299965	162	return gl->gl_state == LM_ST_EXCLUSIVE;
b3b94faa DT	163	}
	164
	165	static inline int gfs2_glock_is_held_dfrd(struct gfs2_glock *gl)
	166	{
50299965	167	return gl->gl_state == LM_ST_DEFERRED;
b3b94faa DT	168	}
	169
	170	static inline int gfs2_glock_is_held_shrd(struct gfs2_glock *gl)
	171	{
50299965	172	return gl->gl_state == LM_ST_SHARED;
b3b94faa DT	173	}
b3b94faa DT	174
009d8518 SW	175	static inline struct address_space gfs2_glock2aspace(struct gfs2_glock gl)
	176	{
	177	if (gl->gl_ops->go_flags & GLOF_ASPACE)
	178	return (struct address_space *)(gl + 1);
	179	return NULL;
	180	}
	181
8eae1ca0 SW	182	extern int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
	183	const struct gfs2_glock_operations *glops,
	184	int create, struct gfs2_glock **glp);
71c1b213	185	extern void gfs2_glock_hold(struct gfs2_glock *gl);
8eae1ca0	186	extern void gfs2_glock_put(struct gfs2_glock *gl);
71c1b213	187	extern void gfs2_glock_queue_put(struct gfs2_glock *gl);
8eae1ca0	188	extern void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state,
b58bf407 BP	189	u16 flags, struct gfs2_holder *gh);
b58bf407 BP	190	extern void gfs2_holder_reinit(unsigned int state, u16 flags,
8eae1ca0 SW	191	struct gfs2_holder *gh);
	192	extern void gfs2_holder_uninit(struct gfs2_holder *gh);
	193	extern int gfs2_glock_nq(struct gfs2_holder *gh);
	194	extern int gfs2_glock_poll(struct gfs2_holder *gh);
	195	extern int gfs2_glock_wait(struct gfs2_holder *gh);
	196	extern void gfs2_glock_dq(struct gfs2_holder *gh);
	197	extern void gfs2_glock_dq_wait(struct gfs2_holder *gh);
	198	extern void gfs2_glock_dq_uninit(struct gfs2_holder *gh);
	199	extern int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
	200	const struct gfs2_glock_operations *glops,
b58bf407	201	unsigned int state, u16 flags,
8eae1ca0 SW	202	struct gfs2_holder *gh);
	203	extern int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs);
	204	extern void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs);
ac3beb6a	205	extern void gfs2_dump_glock(struct seq_file seq, const struct gfs2_glock gl);
8eae1ca0 SW	206	#define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { gfs2_dump_glock(NULL, gl); BUG(); } } while(0)
8eae1ca0 SW	207	extern __printf(2, 3)
6802e340	208	void gfs2_print_dbg(struct seq_file seq, const char fmt, ...);
b3b94faa	209
d0dc80db	210	/**
33027af6	211	* gfs2_glock_nq_init - initialize a holder and enqueue it on a glock
d0dc80db SW	212	* @gl: the glock
	213	* @state: the state we're requesting
	214	* @flags: the modifier flags
	215	* @gh: the holder structure
	216	*
	217	* Returns: 0, GLR_*, or errno
	218	*/
	219
	220	static inline int gfs2_glock_nq_init(struct gfs2_glock *gl,
b58bf407	221	unsigned int state, u16 flags,
d0dc80db SW	222	struct gfs2_holder *gh)
	223	{
	224	int error;
	225
	226	gfs2_holder_init(gl, state, flags, gh);
	227
	228	error = gfs2_glock_nq(gh);
	229	if (error)
	230	gfs2_holder_uninit(gh);
	231
	232	return error;
	233	}
	234
bc015cb8 SW	235	extern void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state);
bc015cb8 SW	236	extern void gfs2_glock_complete(struct gfs2_glock *gl, int ret);
bc015cb8 SW	237	extern void gfs2_gl_hash_clear(struct gfs2_sbd *sdp);
	238	extern void gfs2_glock_finish_truncate(struct gfs2_inode *ip);
	239	extern void gfs2_glock_thaw(struct gfs2_sbd *sdp);
29687a2a	240	extern void gfs2_glock_add_to_lru(struct gfs2_glock *gl);
fc0e38da	241	extern void gfs2_glock_free(struct gfs2_glock *gl);
bc015cb8 SW	242
	243	extern int __init gfs2_glock_init(void);
	244	extern void gfs2_glock_exit(void);
	245
	246	extern int gfs2_create_debugfs_file(struct gfs2_sbd *sdp);
	247	extern void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp);
	248	extern int gfs2_register_debugfs(void);
	249	extern void gfs2_unregister_debugfs(void);
85d1da67	250
f057f6cd SW	251	extern const struct lm_lockops gfs2_dlm_ops;
f057f6cd SW	252
6df9f9a2 AG	253	static inline void gfs2_holder_mark_uninitialized(struct gfs2_holder *gh)
	254	{
	255	gh->gh_gl = NULL;
	256	}
	257
	258	static inline bool gfs2_holder_initialized(struct gfs2_holder *gh)
	259	{
	260	return gh->gh_gl;
	261	}
	262
df3d87bd BP	263	/**
	264	* glock_set_object - set the gl_object field of a glock
	265	* @gl: the glock
	266	* @object: the object
	267	*/
4fd1a579 AG	268	static inline void glock_set_object(struct gfs2_glock gl, void object)
	269	{
	270	spin_lock(&gl->gl_lockref.lock);
df3d87bd BP	271	if (gfs2_assert_warn(gl->gl_name.ln_sbd, gl->gl_object == NULL))
df3d87bd BP	272	gfs2_dump_glock(NULL, gl);
4fd1a579 AG	273	gl->gl_object = object;
	274	spin_unlock(&gl->gl_lockref.lock);
	275	}
	276
df3d87bd BP	277	/**
	278	* glock_clear_object - clear the gl_object field of a glock
	279	* @gl: the glock
	280	* @object: the object
	281	*
	282	* I'd love to similarly add this:
	283	* else if (gfs2_assert_warn(gl->gl_sbd, gl->gl_object == object))
	284	* gfs2_dump_glock(NULL, gl);
	285	* Unfortunately, that's not possible because as soon as gfs2_delete_inode
	286	* frees the block in the rgrp, another process can reassign it for an I_NEW
	287	* inode in gfs2_create_inode because that calls new_inode, not gfs2_iget.
	288	* That means gfs2_delete_inode may subsequently try to call this function
	289	* for a glock that's already pointing to a brand new inode. If we clear the
	290	* new inode's gl_object, we'll introduce metadata corruption. Function
	291	* gfs2_delete_inode calls clear_inode which calls gfs2_clear_inode which also
	292	* tries to clear gl_object, so it's more than just gfs2_delete_inode.
	293	*
	294	*/
	295	static inline void glock_clear_object(struct gfs2_glock gl, void object)
	296	{
	297	spin_lock(&gl->gl_lockref.lock);
	298	if (gl->gl_object == object)
	299	gl->gl_object = NULL;
	300	spin_unlock(&gl->gl_lockref.lock);
	301	}
	302
b3b94faa	303	#endif /* __GLOCK_DOT_H__ */