xfs_log_priv.h

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
  4 * All Rights Reserved.
  5 */
  6#ifndef	__XFS_LOG_PRIV_H__
  7#define __XFS_LOG_PRIV_H__
  8
  9#include "xfs_extent_busy.h"	/* for struct xfs_busy_extents */
 10
 11struct xfs_buf;
 12struct xlog;
 13struct xlog_ticket;
 14struct xfs_mount;
 15
 16/*
 17 * get client id from packed copy.
 18 *
 19 * this hack is here because the xlog_pack code copies four bytes
 20 * of xlog_op_header containing the fields oh_clientid, oh_flags
 21 * and oh_res2 into the packed copy.
 22 *
 23 * later on this four byte chunk is treated as an int and the
 24 * client id is pulled out.
 25 *
 26 * this has endian issues, of course.
 27 */
 28static inline uint xlog_get_client_id(__be32 i)
 29{
 30	return be32_to_cpu(i) >> 24;
 31}
 32
 33/*
 34 * In core log state
 35 */
 36enum xlog_iclog_state {
 37	XLOG_STATE_ACTIVE,	/* Current IC log being written to */
 38	XLOG_STATE_WANT_SYNC,	/* Want to sync this iclog; no more writes */
 39	XLOG_STATE_SYNCING,	/* This IC log is syncing */
 40	XLOG_STATE_DONE_SYNC,	/* Done syncing to disk */
 41	XLOG_STATE_CALLBACK,	/* Callback functions now */
 42	XLOG_STATE_DIRTY,	/* Dirty IC log, not ready for ACTIVE status */
 43};
 44
 45#define XLOG_STATE_STRINGS \
 46	{ XLOG_STATE_ACTIVE,	"XLOG_STATE_ACTIVE" }, \
 47	{ XLOG_STATE_WANT_SYNC,	"XLOG_STATE_WANT_SYNC" }, \
 48	{ XLOG_STATE_SYNCING,	"XLOG_STATE_SYNCING" }, \
 49	{ XLOG_STATE_DONE_SYNC,	"XLOG_STATE_DONE_SYNC" }, \
 50	{ XLOG_STATE_CALLBACK,	"XLOG_STATE_CALLBACK" }, \
 51	{ XLOG_STATE_DIRTY,	"XLOG_STATE_DIRTY" }
 52
 53/*
 54 * In core log flags
 55 */
 56#define XLOG_ICL_NEED_FLUSH	(1u << 0)	/* iclog needs REQ_PREFLUSH */
 57#define XLOG_ICL_NEED_FUA	(1u << 1)	/* iclog needs REQ_FUA */
 58
 59#define XLOG_ICL_STRINGS \
 60	{ XLOG_ICL_NEED_FLUSH,	"XLOG_ICL_NEED_FLUSH" }, \
 61	{ XLOG_ICL_NEED_FUA,	"XLOG_ICL_NEED_FUA" }
 62
 63
 64/*
 65 * Log ticket flags
 66 */
 67#define XLOG_TIC_PERM_RESERV	(1u << 0)	/* permanent reservation */
 68
 69#define XLOG_TIC_FLAGS \
 70	{ XLOG_TIC_PERM_RESERV,	"XLOG_TIC_PERM_RESERV" }
 71
 72/*
 73 * Below are states for covering allocation transactions.
 74 * By covering, we mean changing the h_tail_lsn in the last on-disk
 75 * log write such that no allocation transactions will be re-done during
 76 * recovery after a system crash. Recovery starts at the last on-disk
 77 * log write.
 78 *
 79 * These states are used to insert dummy log entries to cover
 80 * space allocation transactions which can undo non-transactional changes
 81 * after a crash. Writes to a file with space
 82 * already allocated do not result in any transactions. Allocations
 83 * might include space beyond the EOF. So if we just push the EOF a
 84 * little, the last transaction for the file could contain the wrong
 85 * size. If there is no file system activity, after an allocation
 86 * transaction, and the system crashes, the allocation transaction
 87 * will get replayed and the file will be truncated. This could
 88 * be hours/days/... after the allocation occurred.
 89 *
 90 * The fix for this is to do two dummy transactions when the
 91 * system is idle. We need two dummy transaction because the h_tail_lsn
 92 * in the log record header needs to point beyond the last possible
 93 * non-dummy transaction. The first dummy changes the h_tail_lsn to
 94 * the first transaction before the dummy. The second dummy causes
 95 * h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn.
 96 *
 97 * These dummy transactions get committed when everything
 98 * is idle (after there has been some activity).
 99 *
100 * There are 5 states used to control this.
101 *
102 *  IDLE -- no logging has been done on the file system or
103 *		we are done covering previous transactions.
104 *  NEED -- logging has occurred and we need a dummy transaction
105 *		when the log becomes idle.
106 *  DONE -- we were in the NEED state and have committed a dummy
107 *		transaction.
108 *  NEED2 -- we detected that a dummy transaction has gone to the
109 *		on disk log with no other transactions.
110 *  DONE2 -- we committed a dummy transaction when in the NEED2 state.
111 *
112 * There are two places where we switch states:
113 *
114 * 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2.
115 *	We commit the dummy transaction and switch to DONE or DONE2,
116 *	respectively. In all other states, we don't do anything.
117 *
118 * 2.) When we finish writing the on-disk log (xlog_state_clean_log).
119 *
120 *	No matter what state we are in, if this isn't the dummy
121 *	transaction going out, the next state is NEED.
122 *	So, if we aren't in the DONE or DONE2 states, the next state
123 *	is NEED. We can't be finishing a write of the dummy record
124 *	unless it was committed and the state switched to DONE or DONE2.
125 *
126 *	If we are in the DONE state and this was a write of the
127 *		dummy transaction, we move to NEED2.
128 *
129 *	If we are in the DONE2 state and this was a write of the
130 *		dummy transaction, we move to IDLE.
131 *
132 *
133 * Writing only one dummy transaction can get appended to
134 * one file space allocation. When this happens, the log recovery
135 * code replays the space allocation and a file could be truncated.
136 * This is why we have the NEED2 and DONE2 states before going idle.
137 */
138
139#define XLOG_STATE_COVER_IDLE	0
140#define XLOG_STATE_COVER_NEED	1
141#define XLOG_STATE_COVER_DONE	2
142#define XLOG_STATE_COVER_NEED2	3
143#define XLOG_STATE_COVER_DONE2	4
144
145#define XLOG_COVER_OPS		5
146
147struct xlog_ticket {
148	struct list_head	t_queue;	/* reserve/write queue */
149	struct task_struct	*t_task;	/* task that owns this ticket */
150	xlog_tid_t		t_tid;		/* transaction identifier */
151	atomic_t		t_ref;		/* ticket reference count */
152	int			t_curr_res;	/* current reservation */
153	int			t_unit_res;	/* unit reservation */
154	char			t_ocnt;		/* original unit count */
155	char			t_cnt;		/* current unit count */
156	uint8_t			t_flags;	/* properties of reservation */
157	int			t_iclog_hdrs;	/* iclog hdrs in t_curr_res */
158};
159
160/*
161 * In-core log structure.
162 *
163 * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
164 * - ic_next is the pointer to the next iclog in the ring.
165 * - ic_log is a pointer back to the global log structure.
166 * - ic_size is the full size of the log buffer, minus the cycle headers.
167 * - ic_offset is the current number of bytes written to in this iclog.
168 * - ic_refcnt is bumped when someone is writing to the log.
169 * - ic_state is the state of the iclog.
170 *
171 * Because of cacheline contention on large machines, we need to separate
172 * various resources onto different cachelines. To start with, make the
173 * structure cacheline aligned. The following fields can be contended on
174 * by independent processes:
175 *
176 *	- ic_callbacks
177 *	- ic_refcnt
178 *	- fields protected by the global l_icloglock
179 *
180 * so we need to ensure that these fields are located in separate cachelines.
181 * We'll put all the read-only and l_icloglock fields in the first cacheline,
182 * and move everything else out to subsequent cachelines.
183 */
184struct xlog_in_core {
185	wait_queue_head_t	ic_force_wait;
186	wait_queue_head_t	ic_write_wait;
187	struct xlog_in_core	*ic_next;
188	struct xlog_in_core	*ic_prev;
189	struct xlog		*ic_log;
190	u32			ic_size;
191	u32			ic_offset;
192	enum xlog_iclog_state	ic_state;
193	unsigned int		ic_flags;
194	void			*ic_datap;	/* pointer to iclog data */
195	struct list_head	ic_callbacks;
196
197	/* reference counts need their own cacheline */
198	atomic_t		ic_refcnt ____cacheline_aligned_in_smp;
199	struct xlog_rec_header	*ic_header;
200#ifdef DEBUG
201	bool			ic_fail_crc : 1;
202#endif
203	struct semaphore	ic_sema;
204	struct work_struct	ic_end_io_work;
205	struct bio		ic_bio;
206	struct bio_vec		ic_bvec[];
207};
208
209/*
210 * The CIL context is used to aggregate per-transaction details as well be
211 * passed to the iclog for checkpoint post-commit processing.  After being
212 * passed to the iclog, another context needs to be allocated for tracking the
213 * next set of transactions to be aggregated into a checkpoint.
214 */
215struct xfs_cil;
216
217struct xfs_cil_ctx {
218	struct xfs_cil		*cil;
219	xfs_csn_t		sequence;	/* chkpt sequence # */
220	xfs_lsn_t		start_lsn;	/* first LSN of chkpt commit */
221	xfs_lsn_t		commit_lsn;	/* chkpt commit record lsn */
222	struct xlog_in_core	*commit_iclog;
223	struct xlog_ticket	*ticket;	/* chkpt ticket */
224	atomic_t		space_used;	/* aggregate size of regions */
225	struct xfs_busy_extents	busy_extents;
226	struct list_head	log_items;	/* log items in chkpt */
227	struct list_head	lv_chain;	/* logvecs being pushed */
228	struct list_head	iclog_entry;
229	struct list_head	committing;	/* ctx committing list */
230	struct work_struct	push_work;
231	atomic_t		order_id;
232
233	/*
234	 * CPUs that could have added items to the percpu CIL data.  Access is
235	 * coordinated with xc_ctx_lock.
236	 */
237	struct cpumask		cil_pcpmask;
238};
239
240/*
241 * Per-cpu CIL tracking items
242 */
243struct xlog_cil_pcp {
244	int32_t			space_used;
245	uint32_t		space_reserved;
246	struct list_head	busy_extents;
247	struct list_head	log_items;
248};
249
250/*
251 * Committed Item List structure
252 *
253 * This structure is used to track log items that have been committed but not
254 * yet written into the log. It is used only when the delayed logging mount
255 * option is enabled.
256 *
257 * This structure tracks the list of committing checkpoint contexts so
258 * we can avoid the problem of having to hold out new transactions during a
259 * flush until we have a the commit record LSN of the checkpoint. We can
260 * traverse the list of committing contexts in xlog_cil_push_lsn() to find a
261 * sequence match and extract the commit LSN directly from there. If the
262 * checkpoint is still in the process of committing, we can block waiting for
263 * the commit LSN to be determined as well. This should make synchronous
264 * operations almost as efficient as the old logging methods.
265 */
266struct xfs_cil {
267	struct xlog		*xc_log;
268	unsigned long		xc_flags;
269	atomic_t		xc_iclog_hdrs;
270	struct workqueue_struct	*xc_push_wq;
271
272	struct rw_semaphore	xc_ctx_lock ____cacheline_aligned_in_smp;
273	struct xfs_cil_ctx	*xc_ctx;
274
275	spinlock_t		xc_push_lock ____cacheline_aligned_in_smp;
276	xfs_csn_t		xc_push_seq;
277	bool			xc_push_commit_stable;
278	struct list_head	xc_committing;
279	wait_queue_head_t	xc_commit_wait;
280	wait_queue_head_t	xc_start_wait;
281	xfs_csn_t		xc_current_sequence;
282	wait_queue_head_t	xc_push_wait;	/* background push throttle */
283
284	void __percpu		*xc_pcp;	/* percpu CIL structures */
285} ____cacheline_aligned_in_smp;
286
287/* xc_flags bit values */
288#define	XLOG_CIL_EMPTY		1
289#define XLOG_CIL_PCP_SPACE	2
290
291/*
292 * The amount of log space we allow the CIL to aggregate is difficult to size.
293 * Whatever we choose, we have to make sure we can get a reservation for the
294 * log space effectively, that it is large enough to capture sufficient
295 * relogging to reduce log buffer IO significantly, but it is not too large for
296 * the log or induces too much latency when writing out through the iclogs. We
297 * track both space consumed and the number of vectors in the checkpoint
298 * context, so we need to decide which to use for limiting.
299 *
300 * Every log buffer we write out during a push needs a header reserved, which
301 * is at least one sector and more for v2 logs. Hence we need a reservation of
302 * at least 512 bytes per 32k of log space just for the LR headers. That means
303 * 16KB of reservation per megabyte of delayed logging space we will consume,
304 * plus various headers.  The number of headers will vary based on the num of
305 * io vectors, so limiting on a specific number of vectors is going to result
306 * in transactions of varying size. IOWs, it is more consistent to track and
307 * limit space consumed in the log rather than by the number of objects being
308 * logged in order to prevent checkpoint ticket overruns.
309 *
310 * Further, use of static reservations through the log grant mechanism is
311 * problematic. It introduces a lot of complexity (e.g. reserve grant vs write
312 * grant) and a significant deadlock potential because regranting write space
313 * can block on log pushes. Hence if we have to regrant log space during a log
314 * push, we can deadlock.
315 *
316 * However, we can avoid this by use of a dynamic "reservation stealing"
317 * technique during transaction commit whereby unused reservation space in the
318 * transaction ticket is transferred to the CIL ctx commit ticket to cover the
319 * space needed by the checkpoint transaction. This means that we never need to
320 * specifically reserve space for the CIL checkpoint transaction, nor do we
321 * need to regrant space once the checkpoint completes. This also means the
322 * checkpoint transaction ticket is specific to the checkpoint context, rather
323 * than the CIL itself.
324 *
325 * With dynamic reservations, we can effectively make up arbitrary limits for
326 * the checkpoint size so long as they don't violate any other size rules.
327 * Recovery imposes a rule that no transaction exceed half the log, so we are
328 * limited by that.  Furthermore, the log transaction reservation subsystem
329 * tries to keep 25% of the log free, so we need to keep below that limit or we
330 * risk running out of free log space to start any new transactions.
331 *
332 * In order to keep background CIL push efficient, we only need to ensure the
333 * CIL is large enough to maintain sufficient in-memory relogging to avoid
334 * repeated physical writes of frequently modified metadata. If we allow the CIL
335 * to grow to a substantial fraction of the log, then we may be pinning hundreds
336 * of megabytes of metadata in memory until the CIL flushes. This can cause
337 * issues when we are running low on memory - pinned memory cannot be reclaimed,
338 * and the CIL consumes a lot of memory. Hence we need to set an upper physical
339 * size limit for the CIL that limits the maximum amount of memory pinned by the
340 * CIL but does not limit performance by reducing relogging efficiency
341 * significantly.
342 *
343 * As such, the CIL push threshold ends up being the smaller of two thresholds:
344 * - a threshold large enough that it allows CIL to be pushed and progress to be
345 *   made without excessive blocking of incoming transaction commits. This is
346 *   defined to be 12.5% of the log space - half the 25% push threshold of the
347 *   AIL.
348 * - small enough that it doesn't pin excessive amounts of memory but maintains
349 *   close to peak relogging efficiency. This is defined to be 16x the iclog
350 *   buffer window (32MB) as measurements have shown this to be roughly the
351 *   point of diminishing performance increases under highly concurrent
352 *   modification workloads.
353 *
354 * To prevent the CIL from overflowing upper commit size bounds, we introduce a
355 * new threshold at which we block committing transactions until the background
356 * CIL commit commences and switches to a new context. While this is not a hard
357 * limit, it forces the process committing a transaction to the CIL to block and
358 * yeild the CPU, giving the CIL push work a chance to be scheduled and start
359 * work. This prevents a process running lots of transactions from overfilling
360 * the CIL because it is not yielding the CPU. We set the blocking limit at
361 * twice the background push space threshold so we keep in line with the AIL
362 * push thresholds.
363 *
364 * Note: this is not a -hard- limit as blocking is applied after the transaction
365 * is inserted into the CIL and the push has been triggered. It is largely a
366 * throttling mechanism that allows the CIL push to be scheduled and run. A hard
367 * limit will be difficult to implement without introducing global serialisation
368 * in the CIL commit fast path, and it's not at all clear that we actually need
369 * such hard limits given the ~7 years we've run without a hard limit before
370 * finding the first situation where a checkpoint size overflow actually
371 * occurred. Hence the simple throttle, and an ASSERT check to tell us that
372 * we've overrun the max size.
373 */
374#define XLOG_CIL_SPACE_LIMIT(log)	\
375	min_t(int, (log)->l_logsize >> 3, BBTOB(XLOG_TOTAL_REC_SHIFT(log)) << 4)
376
377#define XLOG_CIL_BLOCKING_SPACE_LIMIT(log)	\
378	(XLOG_CIL_SPACE_LIMIT(log) * 2)
379
380/*
381 * ticket grant locks, queues and accounting have their own cachlines
382 * as these are quite hot and can be operated on concurrently.
383 */
384struct xlog_grant_head {
385	spinlock_t		lock ____cacheline_aligned_in_smp;
386	struct list_head	waiters;
387	atomic64_t		grant;
388};
389
390/*
391 * The reservation head lsn is not made up of a cycle number and block number.
392 * Instead, it uses a cycle number and byte number.  Logs don't expect to
393 * overflow 31 bits worth of byte offset, so using a byte number will mean
394 * that round off problems won't occur when releasing partial reservations.
395 */
396struct xlog {
397	/* The following fields don't need locking */
398	struct xfs_mount	*l_mp;	        /* mount point */
399	struct xfs_ail		*l_ailp;	/* AIL log is working with */
400	struct xfs_cil		*l_cilp;	/* CIL log is working with */
401	struct xfs_buftarg	*l_targ;        /* buftarg of log */
402	struct workqueue_struct	*l_ioend_workqueue; /* for I/O completions */
403	struct delayed_work	l_work;		/* background flush work */
404	long			l_opstate;	/* operational state */
405	uint			l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
406	struct list_head	*l_buf_cancel_table;
407	struct list_head	r_dfops;	/* recovered log intent items */
408	int			l_iclog_hsize;  /* size of iclog header */
409	uint			l_sectBBsize;   /* sector size in BBs (2^n) */
410	int			l_iclog_size;	/* size of log in bytes */
411	int			l_iclog_bufs;	/* number of iclog buffers */
412	xfs_daddr_t		l_logBBstart;   /* start block of log */
413	int			l_logsize;      /* size of log in bytes */
414	int			l_logBBsize;    /* size of log in BB chunks */
415
416	/* The following block of fields are changed while holding icloglock */
417	wait_queue_head_t	l_flush_wait ____cacheline_aligned_in_smp;
418						/* waiting for iclog flush */
419	int			l_covered_state;/* state of "covering disk
420						 * log entries" */
421	struct xlog_in_core	*l_iclog;       /* head log queue	*/
422	spinlock_t		l_icloglock;    /* grab to change iclog state */
423	int			l_curr_cycle;   /* Cycle number of log writes */
424	int			l_prev_cycle;   /* Cycle number before last
425						 * block increment */
426	int			l_curr_block;   /* current logical log block */
427	int			l_prev_block;   /* previous logical log block */
428
429	/*
430	 * l_tail_lsn is atomic so it can be set and read without needing to
431	 * hold specific locks. To avoid operations contending with other hot
432	 * objects, it on a separate cacheline.
433	 */
434	/* lsn of 1st LR with unflushed * buffers */
435	atomic64_t		l_tail_lsn ____cacheline_aligned_in_smp;
436
437	struct xlog_grant_head	l_reserve_head;
438	struct xlog_grant_head	l_write_head;
439	uint64_t		l_tail_space;
440
441	struct xfs_kobj		l_kobj;
442
443	/* log recovery lsn tracking (for buffer submission */
444	xfs_lsn_t		l_recovery_lsn;
445
446	uint32_t		l_iclog_roundoff;/* padding roundoff */
447};
448
449/*
450 * Bits for operational state
451 */
452#define XLOG_ACTIVE_RECOVERY	0	/* in the middle of recovery */
453#define XLOG_RECOVERY_NEEDED	1	/* log was recovered */
454#define XLOG_IO_ERROR		2	/* log hit an I/O error, and being
455				   shutdown */
456#define XLOG_TAIL_WARN		3	/* log tail verify warning issued */
457#define XLOG_SHUTDOWN_STARTED	4	/* xlog_force_shutdown() exclusion */
458
459static inline bool
460xlog_recovery_needed(struct xlog *log)
461{
462	return test_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
463}
464
465static inline bool
466xlog_in_recovery(struct xlog *log)
467{
468	return test_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
469}
470
471static inline bool
472xlog_is_shutdown(struct xlog *log)
473{
474	return test_bit(XLOG_IO_ERROR, &log->l_opstate);
475}
476
477/*
478 * Wait until the xlog_force_shutdown() has marked the log as shut down
479 * so xlog_is_shutdown() will always return true.
480 */
481static inline void
482xlog_shutdown_wait(
483	struct xlog	*log)
484{
485	wait_var_event(&log->l_opstate, xlog_is_shutdown(log));
486}
487
488/* common routines */
489extern int
490xlog_recover(
491	struct xlog		*log);
492extern int
493xlog_recover_finish(
494	struct xlog		*log);
495extern void
496xlog_recover_cancel(struct xlog *);
497
498__le32	 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
499		char *dp, unsigned int hdrsize, unsigned int size);
500
501extern struct kmem_cache *xfs_log_ticket_cache;
502struct xlog_ticket *xlog_ticket_alloc(struct xlog *log, int unit_bytes,
503		int count, bool permanent);
504
505void	xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
506void	xlog_print_trans(struct xfs_trans *);
507int	xlog_write(struct xlog *log, struct xfs_cil_ctx *ctx,
508		struct list_head *lv_chain, struct xlog_ticket *tic,
509		uint32_t len);
510void	xfs_log_ticket_ungrant(struct xlog *log, struct xlog_ticket *ticket);
511void	xfs_log_ticket_regrant(struct xlog *log, struct xlog_ticket *ticket);
512
513void xlog_state_switch_iclogs(struct xlog *log, struct xlog_in_core *iclog,
514		int eventual_size);
515int xlog_state_release_iclog(struct xlog *log, struct xlog_in_core *iclog,
516		struct xlog_ticket *ticket);
517
518/*
519 * When we crack an atomic LSN, we sample it first so that the value will not
520 * change while we are cracking it into the component values. This means we
521 * will always get consistent component values to work from. This should always
522 * be used to sample and crack LSNs that are stored and updated in atomic
523 * variables.
524 */
525static inline void
526xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
527{
528	xfs_lsn_t val = atomic64_read(lsn);
529
530	*cycle = CYCLE_LSN(val);
531	*block = BLOCK_LSN(val);
532}
533
534/*
535 * Calculate and assign a value to an atomic LSN variable from component pieces.
536 */
537static inline void
538xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
539{
540	atomic64_set(lsn, xlog_assign_lsn(cycle, block));
541}
542
543/*
544 * Committed Item List interfaces
545 */
546int	xlog_cil_init(struct xlog *log);
547void	xlog_cil_init_post_recovery(struct xlog *log);
548void	xlog_cil_destroy(struct xlog *log);
549bool	xlog_cil_empty(struct xlog *log);
550void	xlog_cil_commit(struct xlog *log, struct xfs_trans *tp,
551			xfs_csn_t *commit_seq, bool regrant);
552void	xlog_cil_set_ctx_write_state(struct xfs_cil_ctx *ctx,
553			struct xlog_in_core *iclog);
554
555
556/*
557 * CIL force routines
558 */
559void xlog_cil_flush(struct xlog *log);
560xfs_lsn_t xlog_cil_force_seq(struct xlog *log, xfs_csn_t sequence);
561
562static inline void
563xlog_cil_force(struct xlog *log)
564{
565	xlog_cil_force_seq(log, log->l_cilp->xc_current_sequence);
566}
567
568/*
569 * Wrapper function for waiting on a wait queue serialised against wakeups
570 * by a spinlock. This matches the semantics of all the wait queues used in the
571 * log code.
572 */
573static inline void
574xlog_wait(
575	struct wait_queue_head	*wq,
576	struct spinlock		*lock)
577		__releases(lock)
578{
579	DECLARE_WAITQUEUE(wait, current);
580
581	add_wait_queue_exclusive(wq, &wait);
582	__set_current_state(TASK_UNINTERRUPTIBLE);
583	spin_unlock(lock);
584	schedule();
585	remove_wait_queue(wq, &wait);
586}
587
588int xlog_wait_on_iclog(struct xlog_in_core *iclog)
589		__releases(iclog->ic_log->l_icloglock);
590
591/* Calculate the distance between two LSNs in bytes */
592static inline uint64_t
593xlog_lsn_sub(
594	struct xlog	*log,
595	xfs_lsn_t	high,
596	xfs_lsn_t	low)
597{
598	uint32_t	hi_cycle = CYCLE_LSN(high);
599	uint32_t	hi_block = BLOCK_LSN(high);
600	uint32_t	lo_cycle = CYCLE_LSN(low);
601	uint32_t	lo_block = BLOCK_LSN(low);
602
603	if (hi_cycle == lo_cycle)
604		return BBTOB(hi_block - lo_block);
605	ASSERT((hi_cycle == lo_cycle + 1) || xlog_is_shutdown(log));
606	return (uint64_t)log->l_logsize - BBTOB(lo_block - hi_block);
607}
608
609void xlog_grant_return_space(struct xlog *log, xfs_lsn_t old_head,
610		xfs_lsn_t new_head);
611
612/*
613 * The LSN is valid so long as it is behind the current LSN. If it isn't, this
614 * means that the next log record that includes this metadata could have a
615 * smaller LSN. In turn, this means that the modification in the log would not
616 * replay.
617 */
618static inline bool
619xlog_valid_lsn(
620	struct xlog	*log,
621	xfs_lsn_t	lsn)
622{
623	int		cur_cycle;
624	int		cur_block;
625	bool		valid = true;
626
627	/*
628	 * First, sample the current lsn without locking to avoid added
629	 * contention from metadata I/O. The current cycle and block are updated
630	 * (in xlog_state_switch_iclogs()) and read here in a particular order
631	 * to avoid false negatives (e.g., thinking the metadata LSN is valid
632	 * when it is not).
633	 *
634	 * The current block is always rewound before the cycle is bumped in
635	 * xlog_state_switch_iclogs() to ensure the current LSN is never seen in
636	 * a transiently forward state. Instead, we can see the LSN in a
637	 * transiently behind state if we happen to race with a cycle wrap.
638	 */
639	cur_cycle = READ_ONCE(log->l_curr_cycle);
640	smp_rmb();
641	cur_block = READ_ONCE(log->l_curr_block);
642
643	if ((CYCLE_LSN(lsn) > cur_cycle) ||
644	    (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block)) {
645		/*
646		 * If the metadata LSN appears invalid, it's possible the check
647		 * above raced with a wrap to the next log cycle. Grab the lock
648		 * to check for sure.
649		 */
650		spin_lock(&log->l_icloglock);
651		cur_cycle = log->l_curr_cycle;
652		cur_block = log->l_curr_block;
653		spin_unlock(&log->l_icloglock);
654
655		if ((CYCLE_LSN(lsn) > cur_cycle) ||
656		    (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block))
657			valid = false;
658	}
659
660	return valid;
661}
662
663/*
664 * Log vector and shadow buffers can be large, so we need to use kvmalloc() here
665 * to ensure success. Unfortunately, kvmalloc() only allows GFP_KERNEL contexts
666 * to fall back to vmalloc, so we can't actually do anything useful with gfp
667 * flags to control the kmalloc() behaviour within kvmalloc(). Hence kmalloc()
668 * will do direct reclaim and compaction in the slow path, both of which are
669 * horrendously expensive. We just want kmalloc to fail fast and fall back to
670 * vmalloc if it can't get something straight away from the free lists or
671 * buddy allocator. Hence we have to open code kvmalloc outselves here.
672 *
673 * This assumes that the caller uses memalloc_nofs_save task context here, so
674 * despite the use of GFP_KERNEL here, we are going to be doing GFP_NOFS
675 * allocations. This is actually the only way to make vmalloc() do GFP_NOFS
676 * allocations, so lets just all pretend this is a GFP_KERNEL context
677 * operation....
678 */
679static inline void *
680xlog_kvmalloc(
681	size_t		buf_size)
682{
683	gfp_t		flags = GFP_KERNEL;
684	void		*p;
685
686	flags &= ~__GFP_DIRECT_RECLAIM;
687	flags |= __GFP_NOWARN | __GFP_NORETRY;
688	do {
689		p = kmalloc(buf_size, flags);
690		if (!p)
691			p = vmalloc(buf_size);
692	} while (!p);
693
694	return p;
695}
696
697/*
698 * Given a count of iovecs and space for a log item, compute the space we need
699 * in the log to store that data plus the log headers.
700 */
701static inline unsigned int
702xlog_item_space(
703	unsigned int	niovecs,
704	unsigned int	nbytes)
705{
706	nbytes += niovecs * (sizeof(uint64_t) + sizeof(struct xlog_op_header));
707	return round_up(nbytes, sizeof(uint64_t));
708}
709
710/*
711 * Cycles over XLOG_CYCLE_DATA_SIZE overflow into the extended header that was
712 * added for v2 logs.  Addressing for the cycles array there is off by one,
713 * because the first batch of cycles is in the original header.
714 */
715static inline __be32 *xlog_cycle_data(struct xlog_rec_header *rhead, unsigned i)
716{
717	if (i >= XLOG_CYCLE_DATA_SIZE) {
718		unsigned	j = i / XLOG_CYCLE_DATA_SIZE;
719		unsigned	k = i % XLOG_CYCLE_DATA_SIZE;
720
721		return &rhead->h_ext[j - 1].xh_cycle_data[k];
722	}
723
724	return &rhead->h_cycle_data[i];
725}
726
727#endif	/* __XFS_LOG_PRIV_H__ */