Free Electrons

Embedded Linux Experts

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
/*
 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * 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.
 *
 * This program is distributed in the hope that it would 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 the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef	__XFS_LOG_PRIV_H__
#define __XFS_LOG_PRIV_H__

struct xfs_buf;
struct xlog;
struct xlog_ticket;
struct xfs_mount;
struct xfs_log_callback;

/*
 * Flags for log structure
 */
#define XLOG_ACTIVE_RECOVERY	0x2	/* in the middle of recovery */
#define	XLOG_RECOVERY_NEEDED	0x4	/* log was recovered */
#define XLOG_IO_ERROR		0x8	/* log hit an I/O error, and being
					   shutdown */
#define XLOG_TAIL_WARN		0x10	/* log tail verify warning issued */

/*
 * get client id from packed copy.
 *
 * this hack is here because the xlog_pack code copies four bytes
 * of xlog_op_header containing the fields oh_clientid, oh_flags
 * and oh_res2 into the packed copy.
 *
 * later on this four byte chunk is treated as an int and the
 * client id is pulled out.
 *
 * this has endian issues, of course.
 */
static inline uint xlog_get_client_id(__be32 i)
{
	return be32_to_cpu(i) >> 24;
}

/*
 * In core log state
 */
#define XLOG_STATE_ACTIVE    0x0001 /* Current IC log being written to */
#define XLOG_STATE_WANT_SYNC 0x0002 /* Want to sync this iclog; no more writes */
#define XLOG_STATE_SYNCING   0x0004 /* This IC log is syncing */
#define XLOG_STATE_DONE_SYNC 0x0008 /* Done syncing to disk */
#define XLOG_STATE_DO_CALLBACK \
			     0x0010 /* Process callback functions */
#define XLOG_STATE_CALLBACK  0x0020 /* Callback functions now */
#define XLOG_STATE_DIRTY     0x0040 /* Dirty IC log, not ready for ACTIVE status*/
#define XLOG_STATE_IOERROR   0x0080 /* IO error happened in sync'ing log */
#define XLOG_STATE_ALL	     0x7FFF /* All possible valid flags */
#define XLOG_STATE_NOTUSED   0x8000 /* This IC log not being used */

/*
 * Flags to log ticket
 */
#define XLOG_TIC_INITED		0x1	/* has been initialized */
#define XLOG_TIC_PERM_RESERV	0x2	/* permanent reservation */

#define XLOG_TIC_FLAGS \
	{ XLOG_TIC_INITED,	"XLOG_TIC_INITED" }, \
	{ XLOG_TIC_PERM_RESERV,	"XLOG_TIC_PERM_RESERV" }

/*
 * Below are states for covering allocation transactions.
 * By covering, we mean changing the h_tail_lsn in the last on-disk
 * log write such that no allocation transactions will be re-done during
 * recovery after a system crash. Recovery starts at the last on-disk
 * log write.
 *
 * These states are used to insert dummy log entries to cover
 * space allocation transactions which can undo non-transactional changes
 * after a crash. Writes to a file with space
 * already allocated do not result in any transactions. Allocations
 * might include space beyond the EOF. So if we just push the EOF a
 * little, the last transaction for the file could contain the wrong
 * size. If there is no file system activity, after an allocation
 * transaction, and the system crashes, the allocation transaction
 * will get replayed and the file will be truncated. This could
 * be hours/days/... after the allocation occurred.
 *
 * The fix for this is to do two dummy transactions when the
 * system is idle. We need two dummy transaction because the h_tail_lsn
 * in the log record header needs to point beyond the last possible
 * non-dummy transaction. The first dummy changes the h_tail_lsn to
 * the first transaction before the dummy. The second dummy causes
 * h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn.
 *
 * These dummy transactions get committed when everything
 * is idle (after there has been some activity).
 *
 * There are 5 states used to control this.
 *
 *  IDLE -- no logging has been done on the file system or
 *		we are done covering previous transactions.
 *  NEED -- logging has occurred and we need a dummy transaction
 *		when the log becomes idle.
 *  DONE -- we were in the NEED state and have committed a dummy
 *		transaction.
 *  NEED2 -- we detected that a dummy transaction has gone to the
 *		on disk log with no other transactions.
 *  DONE2 -- we committed a dummy transaction when in the NEED2 state.
 *
 * There are two places where we switch states:
 *
 * 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2.
 *	We commit the dummy transaction and switch to DONE or DONE2,
 *	respectively. In all other states, we don't do anything.
 *
 * 2.) When we finish writing the on-disk log (xlog_state_clean_log).
 *
 *	No matter what state we are in, if this isn't the dummy
 *	transaction going out, the next state is NEED.
 *	So, if we aren't in the DONE or DONE2 states, the next state
 *	is NEED. We can't be finishing a write of the dummy record
 *	unless it was committed and the state switched to DONE or DONE2.
 *
 *	If we are in the DONE state and this was a write of the
 *		dummy transaction, we move to NEED2.
 *
 *	If we are in the DONE2 state and this was a write of the
 *		dummy transaction, we move to IDLE.
 *
 *
 * Writing only one dummy transaction can get appended to
 * one file space allocation. When this happens, the log recovery
 * code replays the space allocation and a file could be truncated.
 * This is why we have the NEED2 and DONE2 states before going idle.
 */

#define XLOG_STATE_COVER_IDLE	0
#define XLOG_STATE_COVER_NEED	1
#define XLOG_STATE_COVER_DONE	2
#define XLOG_STATE_COVER_NEED2	3
#define XLOG_STATE_COVER_DONE2	4

#define XLOG_COVER_OPS		5

/* Ticket reservation region accounting */ 
#define XLOG_TIC_LEN_MAX	15

/*
 * Reservation region
 * As would be stored in xfs_log_iovec but without the i_addr which
 * we don't care about.
 */
typedef struct xlog_res {
	uint	r_len;	/* region length		:4 */
	uint	r_type;	/* region's transaction type	:4 */
} xlog_res_t;

typedef struct xlog_ticket {
	struct list_head   t_queue;	 /* reserve/write queue */
	struct task_struct *t_task;	 /* task that owns this ticket */
	xlog_tid_t	   t_tid;	 /* transaction identifier	 : 4  */
	atomic_t	   t_ref;	 /* ticket reference count       : 4  */
	int		   t_curr_res;	 /* current reservation in bytes : 4  */
	int		   t_unit_res;	 /* unit reservation in bytes    : 4  */
	char		   t_ocnt;	 /* original count		 : 1  */
	char		   t_cnt;	 /* current count		 : 1  */
	char		   t_clientid;	 /* who does this belong to;	 : 1  */
	char		   t_flags;	 /* properties of reservation	 : 1  */
	uint		   t_trans_type; /* transaction type             : 4  */

        /* reservation array fields */
	uint		   t_res_num;                    /* num in array : 4 */
	uint		   t_res_num_ophdrs;		 /* num op hdrs  : 4 */
	uint		   t_res_arr_sum;		 /* array sum    : 4 */
	uint		   t_res_o_flow;		 /* sum overflow : 4 */
	xlog_res_t	   t_res_arr[XLOG_TIC_LEN_MAX];  /* array of res : 8 * 15 */ 
} xlog_ticket_t;

/*
 * - A log record header is 512 bytes.  There is plenty of room to grow the
 *	xlog_rec_header_t into the reserved space.
 * - ic_data follows, so a write to disk can start at the beginning of
 *	the iclog.
 * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
 * - ic_next is the pointer to the next iclog in the ring.
 * - ic_bp is a pointer to the buffer used to write this incore log to disk.
 * - ic_log is a pointer back to the global log structure.
 * - ic_callback is a linked list of callback function/argument pairs to be
 *	called after an iclog finishes writing.
 * - ic_size is the full size of the header plus data.
 * - ic_offset is the current number of bytes written to in this iclog.
 * - ic_refcnt is bumped when someone is writing to the log.
 * - ic_state is the state of the iclog.
 *
 * Because of cacheline contention on large machines, we need to separate
 * various resources onto different cachelines. To start with, make the
 * structure cacheline aligned. The following fields can be contended on
 * by independent processes:
 *
 *	- ic_callback_*
 *	- ic_refcnt
 *	- fields protected by the global l_icloglock
 *
 * so we need to ensure that these fields are located in separate cachelines.
 * We'll put all the read-only and l_icloglock fields in the first cacheline,
 * and move everything else out to subsequent cachelines.
 */
typedef struct xlog_in_core {
	wait_queue_head_t	ic_force_wait;
	wait_queue_head_t	ic_write_wait;
	struct xlog_in_core	*ic_next;
	struct xlog_in_core	*ic_prev;
	struct xfs_buf		*ic_bp;
	struct xlog		*ic_log;
	int			ic_size;
	int			ic_offset;
	int			ic_bwritecnt;
	unsigned short		ic_state;
	char			*ic_datap;	/* pointer to iclog data */

	/* Callback structures need their own cacheline */
	spinlock_t		ic_callback_lock ____cacheline_aligned_in_smp;
	struct xfs_log_callback	*ic_callback;
	struct xfs_log_callback	**ic_callback_tail;

	/* reference counts need their own cacheline */
	atomic_t		ic_refcnt ____cacheline_aligned_in_smp;
	xlog_in_core_2_t	*ic_data;
#define ic_header	ic_data->hic_header
} xlog_in_core_t;

/*
 * The CIL context is used to aggregate per-transaction details as well be
 * passed to the iclog for checkpoint post-commit processing.  After being
 * passed to the iclog, another context needs to be allocated for tracking the
 * next set of transactions to be aggregated into a checkpoint.
 */
struct xfs_cil;

struct xfs_cil_ctx {
	struct xfs_cil		*cil;
	xfs_lsn_t		sequence;	/* chkpt sequence # */
	xfs_lsn_t		start_lsn;	/* first LSN of chkpt commit */
	xfs_lsn_t		commit_lsn;	/* chkpt commit record lsn */
	struct xlog_ticket	*ticket;	/* chkpt ticket */
	int			nvecs;		/* number of regions */
	int			space_used;	/* aggregate size of regions */
	struct list_head	busy_extents;	/* busy extents in chkpt */
	struct xfs_log_vec	*lv_chain;	/* logvecs being pushed */
	struct xfs_log_callback	log_cb;		/* completion callback hook. */
	struct list_head	committing;	/* ctx committing list */
};

/*
 * Committed Item List structure
 *
 * This structure is used to track log items that have been committed but not
 * yet written into the log. It is used only when the delayed logging mount
 * option is enabled.
 *
 * This structure tracks the list of committing checkpoint contexts so
 * we can avoid the problem of having to hold out new transactions during a
 * flush until we have a the commit record LSN of the checkpoint. We can
 * traverse the list of committing contexts in xlog_cil_push_lsn() to find a
 * sequence match and extract the commit LSN directly from there. If the
 * checkpoint is still in the process of committing, we can block waiting for
 * the commit LSN to be determined as well. This should make synchronous
 * operations almost as efficient as the old logging methods.
 */
struct xfs_cil {
	struct xlog		*xc_log;
	struct list_head	xc_cil;
	spinlock_t		xc_cil_lock;

	struct rw_semaphore	xc_ctx_lock ____cacheline_aligned_in_smp;
	struct xfs_cil_ctx	*xc_ctx;

	spinlock_t		xc_push_lock ____cacheline_aligned_in_smp;
	xfs_lsn_t		xc_push_seq;
	struct list_head	xc_committing;
	wait_queue_head_t	xc_commit_wait;
	xfs_lsn_t		xc_current_sequence;
	struct work_struct	xc_push_work;
} ____cacheline_aligned_in_smp;

/*
 * The amount of log space we allow the CIL to aggregate is difficult to size.
 * Whatever we choose, we have to make sure we can get a reservation for the
 * log space effectively, that it is large enough to capture sufficient
 * relogging to reduce log buffer IO significantly, but it is not too large for
 * the log or induces too much latency when writing out through the iclogs. We
 * track both space consumed and the number of vectors in the checkpoint
 * context, so we need to decide which to use for limiting.
 *
 * Every log buffer we write out during a push needs a header reserved, which
 * is at least one sector and more for v2 logs. Hence we need a reservation of
 * at least 512 bytes per 32k of log space just for the LR headers. That means
 * 16KB of reservation per megabyte of delayed logging space we will consume,
 * plus various headers.  The number of headers will vary based on the num of
 * io vectors, so limiting on a specific number of vectors is going to result
 * in transactions of varying size. IOWs, it is more consistent to track and
 * limit space consumed in the log rather than by the number of objects being
 * logged in order to prevent checkpoint ticket overruns.
 *
 * Further, use of static reservations through the log grant mechanism is
 * problematic. It introduces a lot of complexity (e.g. reserve grant vs write
 * grant) and a significant deadlock potential because regranting write space
 * can block on log pushes. Hence if we have to regrant log space during a log
 * push, we can deadlock.
 *
 * However, we can avoid this by use of a dynamic "reservation stealing"
 * technique during transaction commit whereby unused reservation space in the
 * transaction ticket is transferred to the CIL ctx commit ticket to cover the
 * space needed by the checkpoint transaction. This means that we never need to
 * specifically reserve space for the CIL checkpoint transaction, nor do we
 * need to regrant space once the checkpoint completes. This also means the
 * checkpoint transaction ticket is specific to the checkpoint context, rather
 * than the CIL itself.
 *
 * With dynamic reservations, we can effectively make up arbitrary limits for
 * the checkpoint size so long as they don't violate any other size rules.
 * Recovery imposes a rule that no transaction exceed half the log, so we are
 * limited by that.  Furthermore, the log transaction reservation subsystem
 * tries to keep 25% of the log free, so we need to keep below that limit or we
 * risk running out of free log space to start any new transactions.
 *
 * In order to keep background CIL push efficient, we will set a lower
 * threshold at which background pushing is attempted without blocking current
 * transaction commits.  A separate, higher bound defines when CIL pushes are
 * enforced to ensure we stay within our maximum checkpoint size bounds.
 * threshold, yet give us plenty of space for aggregation on large logs.
 */
#define XLOG_CIL_SPACE_LIMIT(log)	(log->l_logsize >> 3)

/*
 * ticket grant locks, queues and accounting have their own cachlines
 * as these are quite hot and can be operated on concurrently.
 */
struct xlog_grant_head {
	spinlock_t		lock ____cacheline_aligned_in_smp;
	struct list_head	waiters;
	atomic64_t		grant;
};

/*
 * The reservation head lsn is not made up of a cycle number and block number.
 * Instead, it uses a cycle number and byte number.  Logs don't expect to
 * overflow 31 bits worth of byte offset, so using a byte number will mean
 * that round off problems won't occur when releasing partial reservations.
 */
struct xlog {
	/* The following fields don't need locking */
	struct xfs_mount	*l_mp;	        /* mount point */
	struct xfs_ail		*l_ailp;	/* AIL log is working with */
	struct xfs_cil		*l_cilp;	/* CIL log is working with */
	struct xfs_buf		*l_xbuf;        /* extra buffer for log
						 * wrapping */
	struct xfs_buftarg	*l_targ;        /* buftarg of log */
	struct delayed_work	l_work;		/* background flush work */
	uint			l_flags;
	uint			l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
	struct list_head	*l_buf_cancel_table;
	int			l_iclog_hsize;  /* size of iclog header */
	int			l_iclog_heads;  /* # of iclog header sectors */
	uint			l_sectBBsize;   /* sector size in BBs (2^n) */
	int			l_iclog_size;	/* size of log in bytes */
	int			l_iclog_size_log; /* log power size of log */
	int			l_iclog_bufs;	/* number of iclog buffers */
	xfs_daddr_t		l_logBBstart;   /* start block of log */
	int			l_logsize;      /* size of log in bytes */
	int			l_logBBsize;    /* size of log in BB chunks */

	/* The following block of fields are changed while holding icloglock */
	wait_queue_head_t	l_flush_wait ____cacheline_aligned_in_smp;
						/* waiting for iclog flush */
	int			l_covered_state;/* state of "covering disk
						 * log entries" */
	xlog_in_core_t		*l_iclog;       /* head log queue	*/
	spinlock_t		l_icloglock;    /* grab to change iclog state */
	int			l_curr_cycle;   /* Cycle number of log writes */
	int			l_prev_cycle;   /* Cycle number before last
						 * block increment */
	int			l_curr_block;   /* current logical log block */
	int			l_prev_block;   /* previous logical log block */

	/*
	 * l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
	 * read without needing to hold specific locks. To avoid operations
	 * contending with other hot objects, place each of them on a separate
	 * cacheline.
	 */
	/* lsn of last LR on disk */
	atomic64_t		l_last_sync_lsn ____cacheline_aligned_in_smp;
	/* lsn of 1st LR with unflushed * buffers */
	atomic64_t		l_tail_lsn ____cacheline_aligned_in_smp;

	struct xlog_grant_head	l_reserve_head;
	struct xlog_grant_head	l_write_head;

	struct xfs_kobj		l_kobj;

	/* The following field are used for debugging; need to hold icloglock */
#ifdef DEBUG
	char			*l_iclog_bak[XLOG_MAX_ICLOGS];
#endif

};

#define XLOG_BUF_CANCEL_BUCKET(log, blkno) \
	((log)->l_buf_cancel_table + ((__uint64_t)blkno % XLOG_BC_TABLE_SIZE))

#define XLOG_FORCED_SHUTDOWN(log)	((log)->l_flags & XLOG_IO_ERROR)

/* common routines */
extern int
xlog_recover(
	struct xlog		*log);
extern int
xlog_recover_finish(
	struct xlog		*log);

extern __le32	 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
			    char *dp, int size);

extern kmem_zone_t *xfs_log_ticket_zone;
struct xlog_ticket *
xlog_ticket_alloc(
	struct xlog	*log,
	int		unit_bytes,
	int		count,
	char		client,
	bool		permanent,
	xfs_km_flags_t	alloc_flags);


static inline void
xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes)
{
	*ptr += bytes;
	*len -= bytes;
	*off += bytes;
}

void	xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
int
xlog_write(
	struct xlog		*log,
	struct xfs_log_vec	*log_vector,
	struct xlog_ticket	*tic,
	xfs_lsn_t		*start_lsn,
	struct xlog_in_core	**commit_iclog,
	uint			flags);

/*
 * When we crack an atomic LSN, we sample it first so that the value will not
 * change while we are cracking it into the component values. This means we
 * will always get consistent component values to work from. This should always
 * be used to sample and crack LSNs that are stored and updated in atomic
 * variables.
 */
static inline void
xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
{
	xfs_lsn_t val = atomic64_read(lsn);

	*cycle = CYCLE_LSN(val);
	*block = BLOCK_LSN(val);
}

/*
 * Calculate and assign a value to an atomic LSN variable from component pieces.
 */
static inline void
xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
{
	atomic64_set(lsn, xlog_assign_lsn(cycle, block));
}

/*
 * When we crack the grant head, we sample it first so that the value will not
 * change while we are cracking it into the component values. This means we
 * will always get consistent component values to work from.
 */
static inline void
xlog_crack_grant_head_val(int64_t val, int *cycle, int *space)
{
	*cycle = val >> 32;
	*space = val & 0xffffffff;
}

static inline void
xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space)
{
	xlog_crack_grant_head_val(atomic64_read(head), cycle, space);
}

static inline int64_t
xlog_assign_grant_head_val(int cycle, int space)
{
	return ((int64_t)cycle << 32) | space;
}

static inline void
xlog_assign_grant_head(atomic64_t *head, int cycle, int space)
{
	atomic64_set(head, xlog_assign_grant_head_val(cycle, space));
}

/*
 * Committed Item List interfaces
 */
int	xlog_cil_init(struct xlog *log);
void	xlog_cil_init_post_recovery(struct xlog *log);
void	xlog_cil_destroy(struct xlog *log);
bool	xlog_cil_empty(struct xlog *log);

/*
 * CIL force routines
 */
xfs_lsn_t
xlog_cil_force_lsn(
	struct xlog *log,
	xfs_lsn_t sequence);

static inline void
xlog_cil_force(struct xlog *log)
{
	xlog_cil_force_lsn(log, log->l_cilp->xc_current_sequence);
}

/*
 * Unmount record type is used as a pseudo transaction type for the ticket.
 * It's value must be outside the range of XFS_TRANS_* values.
 */
#define XLOG_UNMOUNT_REC_TYPE	(-1U)

/*
 * Wrapper function for waiting on a wait queue serialised against wakeups
 * by a spinlock. This matches the semantics of all the wait queues used in the
 * log code.
 */
static inline void xlog_wait(wait_queue_head_t *wq, spinlock_t *lock)
{
	DECLARE_WAITQUEUE(wait, current);

	add_wait_queue_exclusive(wq, &wait);
	__set_current_state(TASK_UNINTERRUPTIBLE);
	spin_unlock(lock);
	schedule();
	remove_wait_queue(wq, &wait);
}

#endif	/* __XFS_LOG_PRIV_H__ */