xref: /linux/fs/xfs/xfs_log_priv.h (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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 
11 struct xfs_buf;
12 struct xlog;
13 struct xlog_ticket;
14 struct 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  */
xlog_get_client_id(__be32 i)28 static 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  */
36 enum 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 
147 typedef struct 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 } xlog_ticket_t;
159 
160 /*
161  * - A log record header is 512 bytes.  There is plenty of room to grow the
162  *	xlog_rec_header_t into the reserved space.
163  * - ic_data follows, so a write to disk can start at the beginning of
164  *	the iclog.
165  * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
166  * - ic_next is the pointer to the next iclog in the ring.
167  * - ic_log is a pointer back to the global log structure.
168  * - ic_size is the full size of the log buffer, minus the cycle headers.
169  * - ic_offset is the current number of bytes written to in this iclog.
170  * - ic_refcnt is bumped when someone is writing to the log.
171  * - ic_state is the state of the iclog.
172  *
173  * Because of cacheline contention on large machines, we need to separate
174  * various resources onto different cachelines. To start with, make the
175  * structure cacheline aligned. The following fields can be contended on
176  * by independent processes:
177  *
178  *	- ic_callbacks
179  *	- ic_refcnt
180  *	- fields protected by the global l_icloglock
181  *
182  * so we need to ensure that these fields are located in separate cachelines.
183  * We'll put all the read-only and l_icloglock fields in the first cacheline,
184  * and move everything else out to subsequent cachelines.
185  */
186 typedef struct xlog_in_core {
187 	wait_queue_head_t	ic_force_wait;
188 	wait_queue_head_t	ic_write_wait;
189 	struct xlog_in_core	*ic_next;
190 	struct xlog_in_core	*ic_prev;
191 	struct xlog		*ic_log;
192 	u32			ic_size;
193 	u32			ic_offset;
194 	enum xlog_iclog_state	ic_state;
195 	unsigned int		ic_flags;
196 	void			*ic_datap;	/* pointer to iclog data */
197 	struct list_head	ic_callbacks;
198 
199 	/* reference counts need their own cacheline */
200 	atomic_t		ic_refcnt ____cacheline_aligned_in_smp;
201 	xlog_in_core_2_t	*ic_data;
202 #define ic_header	ic_data->hic_header
203 #ifdef DEBUG
204 	bool			ic_fail_crc : 1;
205 #endif
206 	struct semaphore	ic_sema;
207 	struct work_struct	ic_end_io_work;
208 	struct bio		ic_bio;
209 	struct bio_vec		ic_bvec[];
210 } xlog_in_core_t;
211 
212 /*
213  * The CIL context is used to aggregate per-transaction details as well be
214  * passed to the iclog for checkpoint post-commit processing.  After being
215  * passed to the iclog, another context needs to be allocated for tracking the
216  * next set of transactions to be aggregated into a checkpoint.
217  */
218 struct xfs_cil;
219 
220 struct xfs_cil_ctx {
221 	struct xfs_cil		*cil;
222 	xfs_csn_t		sequence;	/* chkpt sequence # */
223 	xfs_lsn_t		start_lsn;	/* first LSN of chkpt commit */
224 	xfs_lsn_t		commit_lsn;	/* chkpt commit record lsn */
225 	struct xlog_in_core	*commit_iclog;
226 	struct xlog_ticket	*ticket;	/* chkpt ticket */
227 	atomic_t		space_used;	/* aggregate size of regions */
228 	struct xfs_busy_extents	busy_extents;
229 	struct list_head	log_items;	/* log items in chkpt */
230 	struct list_head	lv_chain;	/* logvecs being pushed */
231 	struct list_head	iclog_entry;
232 	struct list_head	committing;	/* ctx committing list */
233 	struct work_struct	push_work;
234 	atomic_t		order_id;
235 
236 	/*
237 	 * CPUs that could have added items to the percpu CIL data.  Access is
238 	 * coordinated with xc_ctx_lock.
239 	 */
240 	struct cpumask		cil_pcpmask;
241 };
242 
243 /*
244  * Per-cpu CIL tracking items
245  */
246 struct xlog_cil_pcp {
247 	int32_t			space_used;
248 	uint32_t		space_reserved;
249 	struct list_head	busy_extents;
250 	struct list_head	log_items;
251 };
252 
253 /*
254  * Committed Item List structure
255  *
256  * This structure is used to track log items that have been committed but not
257  * yet written into the log. It is used only when the delayed logging mount
258  * option is enabled.
259  *
260  * This structure tracks the list of committing checkpoint contexts so
261  * we can avoid the problem of having to hold out new transactions during a
262  * flush until we have a the commit record LSN of the checkpoint. We can
263  * traverse the list of committing contexts in xlog_cil_push_lsn() to find a
264  * sequence match and extract the commit LSN directly from there. If the
265  * checkpoint is still in the process of committing, we can block waiting for
266  * the commit LSN to be determined as well. This should make synchronous
267  * operations almost as efficient as the old logging methods.
268  */
269 struct xfs_cil {
270 	struct xlog		*xc_log;
271 	unsigned long		xc_flags;
272 	atomic_t		xc_iclog_hdrs;
273 	struct workqueue_struct	*xc_push_wq;
274 
275 	struct rw_semaphore	xc_ctx_lock ____cacheline_aligned_in_smp;
276 	struct xfs_cil_ctx	*xc_ctx;
277 
278 	spinlock_t		xc_push_lock ____cacheline_aligned_in_smp;
279 	xfs_csn_t		xc_push_seq;
280 	bool			xc_push_commit_stable;
281 	struct list_head	xc_committing;
282 	wait_queue_head_t	xc_commit_wait;
283 	wait_queue_head_t	xc_start_wait;
284 	xfs_csn_t		xc_current_sequence;
285 	wait_queue_head_t	xc_push_wait;	/* background push throttle */
286 
287 	void __percpu		*xc_pcp;	/* percpu CIL structures */
288 } ____cacheline_aligned_in_smp;
289 
290 /* xc_flags bit values */
291 #define	XLOG_CIL_EMPTY		1
292 #define XLOG_CIL_PCP_SPACE	2
293 
294 /*
295  * The amount of log space we allow the CIL to aggregate is difficult to size.
296  * Whatever we choose, we have to make sure we can get a reservation for the
297  * log space effectively, that it is large enough to capture sufficient
298  * relogging to reduce log buffer IO significantly, but it is not too large for
299  * the log or induces too much latency when writing out through the iclogs. We
300  * track both space consumed and the number of vectors in the checkpoint
301  * context, so we need to decide which to use for limiting.
302  *
303  * Every log buffer we write out during a push needs a header reserved, which
304  * is at least one sector and more for v2 logs. Hence we need a reservation of
305  * at least 512 bytes per 32k of log space just for the LR headers. That means
306  * 16KB of reservation per megabyte of delayed logging space we will consume,
307  * plus various headers.  The number of headers will vary based on the num of
308  * io vectors, so limiting on a specific number of vectors is going to result
309  * in transactions of varying size. IOWs, it is more consistent to track and
310  * limit space consumed in the log rather than by the number of objects being
311  * logged in order to prevent checkpoint ticket overruns.
312  *
313  * Further, use of static reservations through the log grant mechanism is
314  * problematic. It introduces a lot of complexity (e.g. reserve grant vs write
315  * grant) and a significant deadlock potential because regranting write space
316  * can block on log pushes. Hence if we have to regrant log space during a log
317  * push, we can deadlock.
318  *
319  * However, we can avoid this by use of a dynamic "reservation stealing"
320  * technique during transaction commit whereby unused reservation space in the
321  * transaction ticket is transferred to the CIL ctx commit ticket to cover the
322  * space needed by the checkpoint transaction. This means that we never need to
323  * specifically reserve space for the CIL checkpoint transaction, nor do we
324  * need to regrant space once the checkpoint completes. This also means the
325  * checkpoint transaction ticket is specific to the checkpoint context, rather
326  * than the CIL itself.
327  *
328  * With dynamic reservations, we can effectively make up arbitrary limits for
329  * the checkpoint size so long as they don't violate any other size rules.
330  * Recovery imposes a rule that no transaction exceed half the log, so we are
331  * limited by that.  Furthermore, the log transaction reservation subsystem
332  * tries to keep 25% of the log free, so we need to keep below that limit or we
333  * risk running out of free log space to start any new transactions.
334  *
335  * In order to keep background CIL push efficient, we only need to ensure the
336  * CIL is large enough to maintain sufficient in-memory relogging to avoid
337  * repeated physical writes of frequently modified metadata. If we allow the CIL
338  * to grow to a substantial fraction of the log, then we may be pinning hundreds
339  * of megabytes of metadata in memory until the CIL flushes. This can cause
340  * issues when we are running low on memory - pinned memory cannot be reclaimed,
341  * and the CIL consumes a lot of memory. Hence we need to set an upper physical
342  * size limit for the CIL that limits the maximum amount of memory pinned by the
343  * CIL but does not limit performance by reducing relogging efficiency
344  * significantly.
345  *
346  * As such, the CIL push threshold ends up being the smaller of two thresholds:
347  * - a threshold large enough that it allows CIL to be pushed and progress to be
348  *   made without excessive blocking of incoming transaction commits. This is
349  *   defined to be 12.5% of the log space - half the 25% push threshold of the
350  *   AIL.
351  * - small enough that it doesn't pin excessive amounts of memory but maintains
352  *   close to peak relogging efficiency. This is defined to be 16x the iclog
353  *   buffer window (32MB) as measurements have shown this to be roughly the
354  *   point of diminishing performance increases under highly concurrent
355  *   modification workloads.
356  *
357  * To prevent the CIL from overflowing upper commit size bounds, we introduce a
358  * new threshold at which we block committing transactions until the background
359  * CIL commit commences and switches to a new context. While this is not a hard
360  * limit, it forces the process committing a transaction to the CIL to block and
361  * yeild the CPU, giving the CIL push work a chance to be scheduled and start
362  * work. This prevents a process running lots of transactions from overfilling
363  * the CIL because it is not yielding the CPU. We set the blocking limit at
364  * twice the background push space threshold so we keep in line with the AIL
365  * push thresholds.
366  *
367  * Note: this is not a -hard- limit as blocking is applied after the transaction
368  * is inserted into the CIL and the push has been triggered. It is largely a
369  * throttling mechanism that allows the CIL push to be scheduled and run. A hard
370  * limit will be difficult to implement without introducing global serialisation
371  * in the CIL commit fast path, and it's not at all clear that we actually need
372  * such hard limits given the ~7 years we've run without a hard limit before
373  * finding the first situation where a checkpoint size overflow actually
374  * occurred. Hence the simple throttle, and an ASSERT check to tell us that
375  * we've overrun the max size.
376  */
377 #define XLOG_CIL_SPACE_LIMIT(log)	\
378 	min_t(int, (log)->l_logsize >> 3, BBTOB(XLOG_TOTAL_REC_SHIFT(log)) << 4)
379 
380 #define XLOG_CIL_BLOCKING_SPACE_LIMIT(log)	\
381 	(XLOG_CIL_SPACE_LIMIT(log) * 2)
382 
383 /*
384  * ticket grant locks, queues and accounting have their own cachlines
385  * as these are quite hot and can be operated on concurrently.
386  */
387 struct xlog_grant_head {
388 	spinlock_t		lock ____cacheline_aligned_in_smp;
389 	struct list_head	waiters;
390 	atomic64_t		grant;
391 };
392 
393 /*
394  * The reservation head lsn is not made up of a cycle number and block number.
395  * Instead, it uses a cycle number and byte number.  Logs don't expect to
396  * overflow 31 bits worth of byte offset, so using a byte number will mean
397  * that round off problems won't occur when releasing partial reservations.
398  */
399 struct xlog {
400 	/* The following fields don't need locking */
401 	struct xfs_mount	*l_mp;	        /* mount point */
402 	struct xfs_ail		*l_ailp;	/* AIL log is working with */
403 	struct xfs_cil		*l_cilp;	/* CIL log is working with */
404 	struct xfs_buftarg	*l_targ;        /* buftarg of log */
405 	struct workqueue_struct	*l_ioend_workqueue; /* for I/O completions */
406 	struct delayed_work	l_work;		/* background flush work */
407 	long			l_opstate;	/* operational state */
408 	uint			l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
409 	struct list_head	*l_buf_cancel_table;
410 	struct list_head	r_dfops;	/* recovered log intent items */
411 	int			l_iclog_hsize;  /* size of iclog header */
412 	int			l_iclog_heads;  /* # of iclog header sectors */
413 	uint			l_sectBBsize;   /* sector size in BBs (2^n) */
414 	int			l_iclog_size;	/* size of log in bytes */
415 	int			l_iclog_bufs;	/* number of iclog buffers */
416 	xfs_daddr_t		l_logBBstart;   /* start block of log */
417 	int			l_logsize;      /* size of log in bytes */
418 	int			l_logBBsize;    /* size of log in BB chunks */
419 
420 	/* The following block of fields are changed while holding icloglock */
421 	wait_queue_head_t	l_flush_wait ____cacheline_aligned_in_smp;
422 						/* waiting for iclog flush */
423 	int			l_covered_state;/* state of "covering disk
424 						 * log entries" */
425 	xlog_in_core_t		*l_iclog;       /* head log queue	*/
426 	spinlock_t		l_icloglock;    /* grab to change iclog state */
427 	int			l_curr_cycle;   /* Cycle number of log writes */
428 	int			l_prev_cycle;   /* Cycle number before last
429 						 * block increment */
430 	int			l_curr_block;   /* current logical log block */
431 	int			l_prev_block;   /* previous logical log block */
432 
433 	/*
434 	 * l_tail_lsn is atomic so it can be set and read without needing to
435 	 * hold specific locks. To avoid operations contending with other hot
436 	 * objects, it on a separate cacheline.
437 	 */
438 	/* lsn of 1st LR with unflushed * buffers */
439 	atomic64_t		l_tail_lsn ____cacheline_aligned_in_smp;
440 
441 	struct xlog_grant_head	l_reserve_head;
442 	struct xlog_grant_head	l_write_head;
443 	uint64_t		l_tail_space;
444 
445 	struct xfs_kobj		l_kobj;
446 
447 	/* log recovery lsn tracking (for buffer submission */
448 	xfs_lsn_t		l_recovery_lsn;
449 
450 	uint32_t		l_iclog_roundoff;/* padding roundoff */
451 };
452 
453 /*
454  * Bits for operational state
455  */
456 #define XLOG_ACTIVE_RECOVERY	0	/* in the middle of recovery */
457 #define XLOG_RECOVERY_NEEDED	1	/* log was recovered */
458 #define XLOG_IO_ERROR		2	/* log hit an I/O error, and being
459 				   shutdown */
460 #define XLOG_TAIL_WARN		3	/* log tail verify warning issued */
461 
462 static inline bool
xlog_recovery_needed(struct xlog * log)463 xlog_recovery_needed(struct xlog *log)
464 {
465 	return test_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
466 }
467 
468 static inline bool
xlog_in_recovery(struct xlog * log)469 xlog_in_recovery(struct xlog *log)
470 {
471 	return test_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
472 }
473 
474 static inline bool
xlog_is_shutdown(struct xlog * log)475 xlog_is_shutdown(struct xlog *log)
476 {
477 	return test_bit(XLOG_IO_ERROR, &log->l_opstate);
478 }
479 
480 /*
481  * Wait until the xlog_force_shutdown() has marked the log as shut down
482  * so xlog_is_shutdown() will always return true.
483  */
484 static inline void
xlog_shutdown_wait(struct xlog * log)485 xlog_shutdown_wait(
486 	struct xlog	*log)
487 {
488 	wait_var_event(&log->l_opstate, xlog_is_shutdown(log));
489 }
490 
491 /* common routines */
492 extern int
493 xlog_recover(
494 	struct xlog		*log);
495 extern int
496 xlog_recover_finish(
497 	struct xlog		*log);
498 extern void
499 xlog_recover_cancel(struct xlog *);
500 
501 extern __le32	 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
502 			    char *dp, int size);
503 
504 extern struct kmem_cache *xfs_log_ticket_cache;
505 struct xlog_ticket *xlog_ticket_alloc(struct xlog *log, int unit_bytes,
506 		int count, bool permanent);
507 
508 void	xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
509 void	xlog_print_trans(struct xfs_trans *);
510 int	xlog_write(struct xlog *log, struct xfs_cil_ctx *ctx,
511 		struct list_head *lv_chain, struct xlog_ticket *tic,
512 		uint32_t len);
513 void	xfs_log_ticket_ungrant(struct xlog *log, struct xlog_ticket *ticket);
514 void	xfs_log_ticket_regrant(struct xlog *log, struct xlog_ticket *ticket);
515 
516 void xlog_state_switch_iclogs(struct xlog *log, struct xlog_in_core *iclog,
517 		int eventual_size);
518 int xlog_state_release_iclog(struct xlog *log, struct xlog_in_core *iclog,
519 		struct xlog_ticket *ticket);
520 
521 /*
522  * When we crack an atomic LSN, we sample it first so that the value will not
523  * change while we are cracking it into the component values. This means we
524  * will always get consistent component values to work from. This should always
525  * be used to sample and crack LSNs that are stored and updated in atomic
526  * variables.
527  */
528 static inline void
xlog_crack_atomic_lsn(atomic64_t * lsn,uint * cycle,uint * block)529 xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
530 {
531 	xfs_lsn_t val = atomic64_read(lsn);
532 
533 	*cycle = CYCLE_LSN(val);
534 	*block = BLOCK_LSN(val);
535 }
536 
537 /*
538  * Calculate and assign a value to an atomic LSN variable from component pieces.
539  */
540 static inline void
xlog_assign_atomic_lsn(atomic64_t * lsn,uint cycle,uint block)541 xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
542 {
543 	atomic64_set(lsn, xlog_assign_lsn(cycle, block));
544 }
545 
546 /*
547  * Committed Item List interfaces
548  */
549 int	xlog_cil_init(struct xlog *log);
550 void	xlog_cil_init_post_recovery(struct xlog *log);
551 void	xlog_cil_destroy(struct xlog *log);
552 bool	xlog_cil_empty(struct xlog *log);
553 void	xlog_cil_commit(struct xlog *log, struct xfs_trans *tp,
554 			xfs_csn_t *commit_seq, bool regrant);
555 void	xlog_cil_set_ctx_write_state(struct xfs_cil_ctx *ctx,
556 			struct xlog_in_core *iclog);
557 
558 
559 /*
560  * CIL force routines
561  */
562 void xlog_cil_flush(struct xlog *log);
563 xfs_lsn_t xlog_cil_force_seq(struct xlog *log, xfs_csn_t sequence);
564 
565 static inline void
xlog_cil_force(struct xlog * log)566 xlog_cil_force(struct xlog *log)
567 {
568 	xlog_cil_force_seq(log, log->l_cilp->xc_current_sequence);
569 }
570 
571 /*
572  * Wrapper function for waiting on a wait queue serialised against wakeups
573  * by a spinlock. This matches the semantics of all the wait queues used in the
574  * log code.
575  */
576 static inline void
xlog_wait(struct wait_queue_head * wq,struct spinlock * lock)577 xlog_wait(
578 	struct wait_queue_head	*wq,
579 	struct spinlock		*lock)
580 		__releases(lock)
581 {
582 	DECLARE_WAITQUEUE(wait, current);
583 
584 	add_wait_queue_exclusive(wq, &wait);
585 	__set_current_state(TASK_UNINTERRUPTIBLE);
586 	spin_unlock(lock);
587 	schedule();
588 	remove_wait_queue(wq, &wait);
589 }
590 
591 int xlog_wait_on_iclog(struct xlog_in_core *iclog)
592 		__releases(iclog->ic_log->l_icloglock);
593 
594 /* Calculate the distance between two LSNs in bytes */
595 static inline uint64_t
xlog_lsn_sub(struct xlog * log,xfs_lsn_t high,xfs_lsn_t low)596 xlog_lsn_sub(
597 	struct xlog	*log,
598 	xfs_lsn_t	high,
599 	xfs_lsn_t	low)
600 {
601 	uint32_t	hi_cycle = CYCLE_LSN(high);
602 	uint32_t	hi_block = BLOCK_LSN(high);
603 	uint32_t	lo_cycle = CYCLE_LSN(low);
604 	uint32_t	lo_block = BLOCK_LSN(low);
605 
606 	if (hi_cycle == lo_cycle)
607 		return BBTOB(hi_block - lo_block);
608 	ASSERT((hi_cycle == lo_cycle + 1) || xlog_is_shutdown(log));
609 	return (uint64_t)log->l_logsize - BBTOB(lo_block - hi_block);
610 }
611 
612 void xlog_grant_return_space(struct xlog *log, xfs_lsn_t old_head,
613 		xfs_lsn_t new_head);
614 
615 /*
616  * The LSN is valid so long as it is behind the current LSN. If it isn't, this
617  * means that the next log record that includes this metadata could have a
618  * smaller LSN. In turn, this means that the modification in the log would not
619  * replay.
620  */
621 static inline bool
xlog_valid_lsn(struct xlog * log,xfs_lsn_t lsn)622 xlog_valid_lsn(
623 	struct xlog	*log,
624 	xfs_lsn_t	lsn)
625 {
626 	int		cur_cycle;
627 	int		cur_block;
628 	bool		valid = true;
629 
630 	/*
631 	 * First, sample the current lsn without locking to avoid added
632 	 * contention from metadata I/O. The current cycle and block are updated
633 	 * (in xlog_state_switch_iclogs()) and read here in a particular order
634 	 * to avoid false negatives (e.g., thinking the metadata LSN is valid
635 	 * when it is not).
636 	 *
637 	 * The current block is always rewound before the cycle is bumped in
638 	 * xlog_state_switch_iclogs() to ensure the current LSN is never seen in
639 	 * a transiently forward state. Instead, we can see the LSN in a
640 	 * transiently behind state if we happen to race with a cycle wrap.
641 	 */
642 	cur_cycle = READ_ONCE(log->l_curr_cycle);
643 	smp_rmb();
644 	cur_block = READ_ONCE(log->l_curr_block);
645 
646 	if ((CYCLE_LSN(lsn) > cur_cycle) ||
647 	    (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block)) {
648 		/*
649 		 * If the metadata LSN appears invalid, it's possible the check
650 		 * above raced with a wrap to the next log cycle. Grab the lock
651 		 * to check for sure.
652 		 */
653 		spin_lock(&log->l_icloglock);
654 		cur_cycle = log->l_curr_cycle;
655 		cur_block = log->l_curr_block;
656 		spin_unlock(&log->l_icloglock);
657 
658 		if ((CYCLE_LSN(lsn) > cur_cycle) ||
659 		    (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block))
660 			valid = false;
661 	}
662 
663 	return valid;
664 }
665 
666 /*
667  * Log vector and shadow buffers can be large, so we need to use kvmalloc() here
668  * to ensure success. Unfortunately, kvmalloc() only allows GFP_KERNEL contexts
669  * to fall back to vmalloc, so we can't actually do anything useful with gfp
670  * flags to control the kmalloc() behaviour within kvmalloc(). Hence kmalloc()
671  * will do direct reclaim and compaction in the slow path, both of which are
672  * horrendously expensive. We just want kmalloc to fail fast and fall back to
673  * vmalloc if it can't get something straight away from the free lists or
674  * buddy allocator. Hence we have to open code kvmalloc outselves here.
675  *
676  * This assumes that the caller uses memalloc_nofs_save task context here, so
677  * despite the use of GFP_KERNEL here, we are going to be doing GFP_NOFS
678  * allocations. This is actually the only way to make vmalloc() do GFP_NOFS
679  * allocations, so lets just all pretend this is a GFP_KERNEL context
680  * operation....
681  */
682 static inline void *
xlog_kvmalloc(size_t buf_size)683 xlog_kvmalloc(
684 	size_t		buf_size)
685 {
686 	gfp_t		flags = GFP_KERNEL;
687 	void		*p;
688 
689 	flags &= ~__GFP_DIRECT_RECLAIM;
690 	flags |= __GFP_NOWARN | __GFP_NORETRY;
691 	do {
692 		p = kmalloc(buf_size, flags);
693 		if (!p)
694 			p = vmalloc(buf_size);
695 	} while (!p);
696 
697 	return p;
698 }
699 
700 #endif	/* __XFS_LOG_PRIV_H__ */
701