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 struct xfs_buf;
10 struct xlog;
11 struct xlog_ticket;
12 struct xfs_mount;
13 
14 /*
15  * get client id from packed copy.
16  *
17  * this hack is here because the xlog_pack code copies four bytes
18  * of xlog_op_header containing the fields oh_clientid, oh_flags
19  * and oh_res2 into the packed copy.
20  *
21  * later on this four byte chunk is treated as an int and the
22  * client id is pulled out.
23  *
24  * this has endian issues, of course.
25  */
xlog_get_client_id(__be32 i)26 static inline uint xlog_get_client_id(__be32 i)
27 {
28 	return be32_to_cpu(i) >> 24;
29 }
30 
31 /*
32  * In core log state
33  */
34 enum xlog_iclog_state {
35 	XLOG_STATE_ACTIVE,	/* Current IC log being written to */
36 	XLOG_STATE_WANT_SYNC,	/* Want to sync this iclog; no more writes */
37 	XLOG_STATE_SYNCING,	/* This IC log is syncing */
38 	XLOG_STATE_DONE_SYNC,	/* Done syncing to disk */
39 	XLOG_STATE_CALLBACK,	/* Callback functions now */
40 	XLOG_STATE_DIRTY,	/* Dirty IC log, not ready for ACTIVE status */
41 };
42 
43 #define XLOG_STATE_STRINGS \
44 	{ XLOG_STATE_ACTIVE,	"XLOG_STATE_ACTIVE" }, \
45 	{ XLOG_STATE_WANT_SYNC,	"XLOG_STATE_WANT_SYNC" }, \
46 	{ XLOG_STATE_SYNCING,	"XLOG_STATE_SYNCING" }, \
47 	{ XLOG_STATE_DONE_SYNC,	"XLOG_STATE_DONE_SYNC" }, \
48 	{ XLOG_STATE_CALLBACK,	"XLOG_STATE_CALLBACK" }, \
49 	{ XLOG_STATE_DIRTY,	"XLOG_STATE_DIRTY" }
50 
51 /*
52  * In core log flags
53  */
54 #define XLOG_ICL_NEED_FLUSH	(1u << 0)	/* iclog needs REQ_PREFLUSH */
55 #define XLOG_ICL_NEED_FUA	(1u << 1)	/* iclog needs REQ_FUA */
56 
57 #define XLOG_ICL_STRINGS \
58 	{ XLOG_ICL_NEED_FLUSH,	"XLOG_ICL_NEED_FLUSH" }, \
59 	{ XLOG_ICL_NEED_FUA,	"XLOG_ICL_NEED_FUA" }
60 
61 
62 /*
63  * Log ticket flags
64  */
65 #define XLOG_TIC_PERM_RESERV	(1u << 0)	/* permanent reservation */
66 
67 #define XLOG_TIC_FLAGS \
68 	{ XLOG_TIC_PERM_RESERV,	"XLOG_TIC_PERM_RESERV" }
69 
70 /*
71  * Below are states for covering allocation transactions.
72  * By covering, we mean changing the h_tail_lsn in the last on-disk
73  * log write such that no allocation transactions will be re-done during
74  * recovery after a system crash. Recovery starts at the last on-disk
75  * log write.
76  *
77  * These states are used to insert dummy log entries to cover
78  * space allocation transactions which can undo non-transactional changes
79  * after a crash. Writes to a file with space
80  * already allocated do not result in any transactions. Allocations
81  * might include space beyond the EOF. So if we just push the EOF a
82  * little, the last transaction for the file could contain the wrong
83  * size. If there is no file system activity, after an allocation
84  * transaction, and the system crashes, the allocation transaction
85  * will get replayed and the file will be truncated. This could
86  * be hours/days/... after the allocation occurred.
87  *
88  * The fix for this is to do two dummy transactions when the
89  * system is idle. We need two dummy transaction because the h_tail_lsn
90  * in the log record header needs to point beyond the last possible
91  * non-dummy transaction. The first dummy changes the h_tail_lsn to
92  * the first transaction before the dummy. The second dummy causes
93  * h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn.
94  *
95  * These dummy transactions get committed when everything
96  * is idle (after there has been some activity).
97  *
98  * There are 5 states used to control this.
99  *
100  *  IDLE -- no logging has been done on the file system or
101  *		we are done covering previous transactions.
102  *  NEED -- logging has occurred and we need a dummy transaction
103  *		when the log becomes idle.
104  *  DONE -- we were in the NEED state and have committed a dummy
105  *		transaction.
106  *  NEED2 -- we detected that a dummy transaction has gone to the
107  *		on disk log with no other transactions.
108  *  DONE2 -- we committed a dummy transaction when in the NEED2 state.
109  *
110  * There are two places where we switch states:
111  *
112  * 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2.
113  *	We commit the dummy transaction and switch to DONE or DONE2,
114  *	respectively. In all other states, we don't do anything.
115  *
116  * 2.) When we finish writing the on-disk log (xlog_state_clean_log).
117  *
118  *	No matter what state we are in, if this isn't the dummy
119  *	transaction going out, the next state is NEED.
120  *	So, if we aren't in the DONE or DONE2 states, the next state
121  *	is NEED. We can't be finishing a write of the dummy record
122  *	unless it was committed and the state switched to DONE or DONE2.
123  *
124  *	If we are in the DONE state and this was a write of the
125  *		dummy transaction, we move to NEED2.
126  *
127  *	If we are in the DONE2 state and this was a write of the
128  *		dummy transaction, we move to IDLE.
129  *
130  *
131  * Writing only one dummy transaction can get appended to
132  * one file space allocation. When this happens, the log recovery
133  * code replays the space allocation and a file could be truncated.
134  * This is why we have the NEED2 and DONE2 states before going idle.
135  */
136 
137 #define XLOG_STATE_COVER_IDLE	0
138 #define XLOG_STATE_COVER_NEED	1
139 #define XLOG_STATE_COVER_DONE	2
140 #define XLOG_STATE_COVER_NEED2	3
141 #define XLOG_STATE_COVER_DONE2	4
142 
143 #define XLOG_COVER_OPS		5
144 
145 typedef struct xlog_ticket {
146 	struct list_head   t_queue;	 /* reserve/write queue */
147 	struct task_struct *t_task;	 /* task that owns this ticket */
148 	xlog_tid_t	   t_tid;	 /* transaction identifier	 : 4  */
149 	atomic_t	   t_ref;	 /* ticket reference count       : 4  */
150 	int		   t_curr_res;	 /* current reservation in bytes : 4  */
151 	int		   t_unit_res;	 /* unit reservation in bytes    : 4  */
152 	char		   t_ocnt;	 /* original count		 : 1  */
153 	char		   t_cnt;	 /* current count		 : 1  */
154 	uint8_t		   t_flags;	 /* properties of reservation	 : 1  */
155 } xlog_ticket_t;
156 
157 /*
158  * - A log record header is 512 bytes.  There is plenty of room to grow the
159  *	xlog_rec_header_t into the reserved space.
160  * - ic_data follows, so a write to disk can start at the beginning of
161  *	the iclog.
162  * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
163  * - ic_next is the pointer to the next iclog in the ring.
164  * - ic_log is a pointer back to the global log structure.
165  * - ic_size is the full size of the log buffer, minus the cycle headers.
166  * - ic_offset is the current number of bytes written to in this iclog.
167  * - ic_refcnt is bumped when someone is writing to the log.
168  * - ic_state is the state of the iclog.
169  *
170  * Because of cacheline contention on large machines, we need to separate
171  * various resources onto different cachelines. To start with, make the
172  * structure cacheline aligned. The following fields can be contended on
173  * by independent processes:
174  *
175  *	- ic_callbacks
176  *	- ic_refcnt
177  *	- fields protected by the global l_icloglock
178  *
179  * so we need to ensure that these fields are located in separate cachelines.
180  * We'll put all the read-only and l_icloglock fields in the first cacheline,
181  * and move everything else out to subsequent cachelines.
182  */
183 typedef struct xlog_in_core {
184 	wait_queue_head_t	ic_force_wait;
185 	wait_queue_head_t	ic_write_wait;
186 	struct xlog_in_core	*ic_next;
187 	struct xlog_in_core	*ic_prev;
188 	struct xlog		*ic_log;
189 	u32			ic_size;
190 	u32			ic_offset;
191 	enum xlog_iclog_state	ic_state;
192 	unsigned int		ic_flags;
193 	void			*ic_datap;	/* pointer to iclog data */
194 	struct list_head	ic_callbacks;
195 
196 	/* reference counts need their own cacheline */
197 	atomic_t		ic_refcnt ____cacheline_aligned_in_smp;
198 	xlog_in_core_2_t	*ic_data;
199 #define ic_header	ic_data->hic_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 } xlog_in_core_t;
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  */
215 struct xfs_cil;
216 
217 struct 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 	int			space_used;	/* aggregate size of regions */
225 	struct list_head	busy_extents;	/* busy extents in chkpt */
226 	struct xfs_log_vec	*lv_chain;	/* logvecs being pushed */
227 	struct list_head	iclog_entry;
228 	struct list_head	committing;	/* ctx committing list */
229 	struct work_struct	discard_endio_work;
230 	struct work_struct	push_work;
231 };
232 
233 /*
234  * Committed Item List structure
235  *
236  * This structure is used to track log items that have been committed but not
237  * yet written into the log. It is used only when the delayed logging mount
238  * option is enabled.
239  *
240  * This structure tracks the list of committing checkpoint contexts so
241  * we can avoid the problem of having to hold out new transactions during a
242  * flush until we have a the commit record LSN of the checkpoint. We can
243  * traverse the list of committing contexts in xlog_cil_push_lsn() to find a
244  * sequence match and extract the commit LSN directly from there. If the
245  * checkpoint is still in the process of committing, we can block waiting for
246  * the commit LSN to be determined as well. This should make synchronous
247  * operations almost as efficient as the old logging methods.
248  */
249 struct xfs_cil {
250 	struct xlog		*xc_log;
251 	struct list_head	xc_cil;
252 	spinlock_t		xc_cil_lock;
253 	struct workqueue_struct	*xc_push_wq;
254 
255 	struct rw_semaphore	xc_ctx_lock ____cacheline_aligned_in_smp;
256 	struct xfs_cil_ctx	*xc_ctx;
257 
258 	spinlock_t		xc_push_lock ____cacheline_aligned_in_smp;
259 	xfs_csn_t		xc_push_seq;
260 	bool			xc_push_commit_stable;
261 	struct list_head	xc_committing;
262 	wait_queue_head_t	xc_commit_wait;
263 	wait_queue_head_t	xc_start_wait;
264 	xfs_csn_t		xc_current_sequence;
265 	wait_queue_head_t	xc_push_wait;	/* background push throttle */
266 } ____cacheline_aligned_in_smp;
267 
268 /*
269  * The amount of log space we allow the CIL to aggregate is difficult to size.
270  * Whatever we choose, we have to make sure we can get a reservation for the
271  * log space effectively, that it is large enough to capture sufficient
272  * relogging to reduce log buffer IO significantly, but it is not too large for
273  * the log or induces too much latency when writing out through the iclogs. We
274  * track both space consumed and the number of vectors in the checkpoint
275  * context, so we need to decide which to use for limiting.
276  *
277  * Every log buffer we write out during a push needs a header reserved, which
278  * is at least one sector and more for v2 logs. Hence we need a reservation of
279  * at least 512 bytes per 32k of log space just for the LR headers. That means
280  * 16KB of reservation per megabyte of delayed logging space we will consume,
281  * plus various headers.  The number of headers will vary based on the num of
282  * io vectors, so limiting on a specific number of vectors is going to result
283  * in transactions of varying size. IOWs, it is more consistent to track and
284  * limit space consumed in the log rather than by the number of objects being
285  * logged in order to prevent checkpoint ticket overruns.
286  *
287  * Further, use of static reservations through the log grant mechanism is
288  * problematic. It introduces a lot of complexity (e.g. reserve grant vs write
289  * grant) and a significant deadlock potential because regranting write space
290  * can block on log pushes. Hence if we have to regrant log space during a log
291  * push, we can deadlock.
292  *
293  * However, we can avoid this by use of a dynamic "reservation stealing"
294  * technique during transaction commit whereby unused reservation space in the
295  * transaction ticket is transferred to the CIL ctx commit ticket to cover the
296  * space needed by the checkpoint transaction. This means that we never need to
297  * specifically reserve space for the CIL checkpoint transaction, nor do we
298  * need to regrant space once the checkpoint completes. This also means the
299  * checkpoint transaction ticket is specific to the checkpoint context, rather
300  * than the CIL itself.
301  *
302  * With dynamic reservations, we can effectively make up arbitrary limits for
303  * the checkpoint size so long as they don't violate any other size rules.
304  * Recovery imposes a rule that no transaction exceed half the log, so we are
305  * limited by that.  Furthermore, the log transaction reservation subsystem
306  * tries to keep 25% of the log free, so we need to keep below that limit or we
307  * risk running out of free log space to start any new transactions.
308  *
309  * In order to keep background CIL push efficient, we only need to ensure the
310  * CIL is large enough to maintain sufficient in-memory relogging to avoid
311  * repeated physical writes of frequently modified metadata. If we allow the CIL
312  * to grow to a substantial fraction of the log, then we may be pinning hundreds
313  * of megabytes of metadata in memory until the CIL flushes. This can cause
314  * issues when we are running low on memory - pinned memory cannot be reclaimed,
315  * and the CIL consumes a lot of memory. Hence we need to set an upper physical
316  * size limit for the CIL that limits the maximum amount of memory pinned by the
317  * CIL but does not limit performance by reducing relogging efficiency
318  * significantly.
319  *
320  * As such, the CIL push threshold ends up being the smaller of two thresholds:
321  * - a threshold large enough that it allows CIL to be pushed and progress to be
322  *   made without excessive blocking of incoming transaction commits. This is
323  *   defined to be 12.5% of the log space - half the 25% push threshold of the
324  *   AIL.
325  * - small enough that it doesn't pin excessive amounts of memory but maintains
326  *   close to peak relogging efficiency. This is defined to be 16x the iclog
327  *   buffer window (32MB) as measurements have shown this to be roughly the
328  *   point of diminishing performance increases under highly concurrent
329  *   modification workloads.
330  *
331  * To prevent the CIL from overflowing upper commit size bounds, we introduce a
332  * new threshold at which we block committing transactions until the background
333  * CIL commit commences and switches to a new context. While this is not a hard
334  * limit, it forces the process committing a transaction to the CIL to block and
335  * yeild the CPU, giving the CIL push work a chance to be scheduled and start
336  * work. This prevents a process running lots of transactions from overfilling
337  * the CIL because it is not yielding the CPU. We set the blocking limit at
338  * twice the background push space threshold so we keep in line with the AIL
339  * push thresholds.
340  *
341  * Note: this is not a -hard- limit as blocking is applied after the transaction
342  * is inserted into the CIL and the push has been triggered. It is largely a
343  * throttling mechanism that allows the CIL push to be scheduled and run. A hard
344  * limit will be difficult to implement without introducing global serialisation
345  * in the CIL commit fast path, and it's not at all clear that we actually need
346  * such hard limits given the ~7 years we've run without a hard limit before
347  * finding the first situation where a checkpoint size overflow actually
348  * occurred. Hence the simple throttle, and an ASSERT check to tell us that
349  * we've overrun the max size.
350  */
351 #define XLOG_CIL_SPACE_LIMIT(log)	\
352 	min_t(int, (log)->l_logsize >> 3, BBTOB(XLOG_TOTAL_REC_SHIFT(log)) << 4)
353 
354 #define XLOG_CIL_BLOCKING_SPACE_LIMIT(log)	\
355 	(XLOG_CIL_SPACE_LIMIT(log) * 2)
356 
357 /*
358  * ticket grant locks, queues and accounting have their own cachlines
359  * as these are quite hot and can be operated on concurrently.
360  */
361 struct xlog_grant_head {
362 	spinlock_t		lock ____cacheline_aligned_in_smp;
363 	struct list_head	waiters;
364 	atomic64_t		grant;
365 };
366 
367 /*
368  * The reservation head lsn is not made up of a cycle number and block number.
369  * Instead, it uses a cycle number and byte number.  Logs don't expect to
370  * overflow 31 bits worth of byte offset, so using a byte number will mean
371  * that round off problems won't occur when releasing partial reservations.
372  */
373 struct xlog {
374 	/* The following fields don't need locking */
375 	struct xfs_mount	*l_mp;	        /* mount point */
376 	struct xfs_ail		*l_ailp;	/* AIL log is working with */
377 	struct xfs_cil		*l_cilp;	/* CIL log is working with */
378 	struct xfs_buftarg	*l_targ;        /* buftarg of log */
379 	struct workqueue_struct	*l_ioend_workqueue; /* for I/O completions */
380 	struct delayed_work	l_work;		/* background flush work */
381 	long			l_opstate;	/* operational state */
382 	uint			l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
383 	struct list_head	*l_buf_cancel_table;
384 	int			l_iclog_hsize;  /* size of iclog header */
385 	int			l_iclog_heads;  /* # of iclog header sectors */
386 	uint			l_sectBBsize;   /* sector size in BBs (2^n) */
387 	int			l_iclog_size;	/* size of log in bytes */
388 	int			l_iclog_bufs;	/* number of iclog buffers */
389 	xfs_daddr_t		l_logBBstart;   /* start block of log */
390 	int			l_logsize;      /* size of log in bytes */
391 	int			l_logBBsize;    /* size of log in BB chunks */
392 
393 	/* The following block of fields are changed while holding icloglock */
394 	wait_queue_head_t	l_flush_wait ____cacheline_aligned_in_smp;
395 						/* waiting for iclog flush */
396 	int			l_covered_state;/* state of "covering disk
397 						 * log entries" */
398 	xlog_in_core_t		*l_iclog;       /* head log queue	*/
399 	spinlock_t		l_icloglock;    /* grab to change iclog state */
400 	int			l_curr_cycle;   /* Cycle number of log writes */
401 	int			l_prev_cycle;   /* Cycle number before last
402 						 * block increment */
403 	int			l_curr_block;   /* current logical log block */
404 	int			l_prev_block;   /* previous logical log block */
405 
406 	/*
407 	 * l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
408 	 * read without needing to hold specific locks. To avoid operations
409 	 * contending with other hot objects, place each of them on a separate
410 	 * cacheline.
411 	 */
412 	/* lsn of last LR on disk */
413 	atomic64_t		l_last_sync_lsn ____cacheline_aligned_in_smp;
414 	/* lsn of 1st LR with unflushed * buffers */
415 	atomic64_t		l_tail_lsn ____cacheline_aligned_in_smp;
416 
417 	struct xlog_grant_head	l_reserve_head;
418 	struct xlog_grant_head	l_write_head;
419 
420 	struct xfs_kobj		l_kobj;
421 
422 	/* log recovery lsn tracking (for buffer submission */
423 	xfs_lsn_t		l_recovery_lsn;
424 
425 	uint32_t		l_iclog_roundoff;/* padding roundoff */
426 
427 	/* Users of log incompat features should take a read lock. */
428 	struct rw_semaphore	l_incompat_users;
429 };
430 
431 /*
432  * Bits for operational state
433  */
434 #define XLOG_ACTIVE_RECOVERY	0	/* in the middle of recovery */
435 #define XLOG_RECOVERY_NEEDED	1	/* log was recovered */
436 #define XLOG_IO_ERROR		2	/* log hit an I/O error, and being
437 				   shutdown */
438 #define XLOG_TAIL_WARN		3	/* log tail verify warning issued */
439 
440 static inline bool
xlog_recovery_needed(struct xlog * log)441 xlog_recovery_needed(struct xlog *log)
442 {
443 	return test_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
444 }
445 
446 static inline bool
xlog_in_recovery(struct xlog * log)447 xlog_in_recovery(struct xlog *log)
448 {
449 	return test_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
450 }
451 
452 static inline bool
xlog_is_shutdown(struct xlog * log)453 xlog_is_shutdown(struct xlog *log)
454 {
455 	return test_bit(XLOG_IO_ERROR, &log->l_opstate);
456 }
457 
458 /*
459  * Wait until the xlog_force_shutdown() has marked the log as shut down
460  * so xlog_is_shutdown() will always return true.
461  */
462 static inline void
xlog_shutdown_wait(struct xlog * log)463 xlog_shutdown_wait(
464 	struct xlog	*log)
465 {
466 	wait_var_event(&log->l_opstate, xlog_is_shutdown(log));
467 }
468 
469 /* common routines */
470 extern int
471 xlog_recover(
472 	struct xlog		*log);
473 extern int
474 xlog_recover_finish(
475 	struct xlog		*log);
476 extern void
477 xlog_recover_cancel(struct xlog *);
478 
479 extern __le32	 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
480 			    char *dp, int size);
481 
482 extern struct kmem_cache *xfs_log_ticket_cache;
483 struct xlog_ticket *xlog_ticket_alloc(struct xlog *log, int unit_bytes,
484 		int count, bool permanent);
485 
486 void	xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
487 void	xlog_print_trans(struct xfs_trans *);
488 int	xlog_write(struct xlog *log, struct xfs_cil_ctx *ctx,
489 		struct xfs_log_vec *log_vector, struct xlog_ticket *tic,
490 		uint32_t len);
491 void	xfs_log_ticket_ungrant(struct xlog *log, struct xlog_ticket *ticket);
492 void	xfs_log_ticket_regrant(struct xlog *log, struct xlog_ticket *ticket);
493 
494 void xlog_state_switch_iclogs(struct xlog *log, struct xlog_in_core *iclog,
495 		int eventual_size);
496 int xlog_state_release_iclog(struct xlog *log, struct xlog_in_core *iclog);
497 
498 /*
499  * When we crack an atomic LSN, we sample it first so that the value will not
500  * change while we are cracking it into the component values. This means we
501  * will always get consistent component values to work from. This should always
502  * be used to sample and crack LSNs that are stored and updated in atomic
503  * variables.
504  */
505 static inline void
xlog_crack_atomic_lsn(atomic64_t * lsn,uint * cycle,uint * block)506 xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
507 {
508 	xfs_lsn_t val = atomic64_read(lsn);
509 
510 	*cycle = CYCLE_LSN(val);
511 	*block = BLOCK_LSN(val);
512 }
513 
514 /*
515  * Calculate and assign a value to an atomic LSN variable from component pieces.
516  */
517 static inline void
xlog_assign_atomic_lsn(atomic64_t * lsn,uint cycle,uint block)518 xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
519 {
520 	atomic64_set(lsn, xlog_assign_lsn(cycle, block));
521 }
522 
523 /*
524  * When we crack the grant head, we sample it first so that the value will not
525  * change while we are cracking it into the component values. This means we
526  * will always get consistent component values to work from.
527  */
528 static inline void
xlog_crack_grant_head_val(int64_t val,int * cycle,int * space)529 xlog_crack_grant_head_val(int64_t val, int *cycle, int *space)
530 {
531 	*cycle = val >> 32;
532 	*space = val & 0xffffffff;
533 }
534 
535 static inline void
xlog_crack_grant_head(atomic64_t * head,int * cycle,int * space)536 xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space)
537 {
538 	xlog_crack_grant_head_val(atomic64_read(head), cycle, space);
539 }
540 
541 static inline int64_t
xlog_assign_grant_head_val(int cycle,int space)542 xlog_assign_grant_head_val(int cycle, int space)
543 {
544 	return ((int64_t)cycle << 32) | space;
545 }
546 
547 static inline void
xlog_assign_grant_head(atomic64_t * head,int cycle,int space)548 xlog_assign_grant_head(atomic64_t *head, int cycle, int space)
549 {
550 	atomic64_set(head, xlog_assign_grant_head_val(cycle, space));
551 }
552 
553 /*
554  * Committed Item List interfaces
555  */
556 int	xlog_cil_init(struct xlog *log);
557 void	xlog_cil_init_post_recovery(struct xlog *log);
558 void	xlog_cil_destroy(struct xlog *log);
559 bool	xlog_cil_empty(struct xlog *log);
560 void	xlog_cil_commit(struct xlog *log, struct xfs_trans *tp,
561 			xfs_csn_t *commit_seq, bool regrant);
562 void	xlog_cil_set_ctx_write_state(struct xfs_cil_ctx *ctx,
563 			struct xlog_in_core *iclog);
564 
565 
566 /*
567  * CIL force routines
568  */
569 void xlog_cil_flush(struct xlog *log);
570 xfs_lsn_t xlog_cil_force_seq(struct xlog *log, xfs_csn_t sequence);
571 
572 static inline void
xlog_cil_force(struct xlog * log)573 xlog_cil_force(struct xlog *log)
574 {
575 	xlog_cil_force_seq(log, log->l_cilp->xc_current_sequence);
576 }
577 
578 /*
579  * Wrapper function for waiting on a wait queue serialised against wakeups
580  * by a spinlock. This matches the semantics of all the wait queues used in the
581  * log code.
582  */
583 static inline void
xlog_wait(struct wait_queue_head * wq,struct spinlock * lock)584 xlog_wait(
585 	struct wait_queue_head	*wq,
586 	struct spinlock		*lock)
587 		__releases(lock)
588 {
589 	DECLARE_WAITQUEUE(wait, current);
590 
591 	add_wait_queue_exclusive(wq, &wait);
592 	__set_current_state(TASK_UNINTERRUPTIBLE);
593 	spin_unlock(lock);
594 	schedule();
595 	remove_wait_queue(wq, &wait);
596 }
597 
598 int xlog_wait_on_iclog(struct xlog_in_core *iclog);
599 
600 /*
601  * The LSN is valid so long as it is behind the current LSN. If it isn't, this
602  * means that the next log record that includes this metadata could have a
603  * smaller LSN. In turn, this means that the modification in the log would not
604  * replay.
605  */
606 static inline bool
xlog_valid_lsn(struct xlog * log,xfs_lsn_t lsn)607 xlog_valid_lsn(
608 	struct xlog	*log,
609 	xfs_lsn_t	lsn)
610 {
611 	int		cur_cycle;
612 	int		cur_block;
613 	bool		valid = true;
614 
615 	/*
616 	 * First, sample the current lsn without locking to avoid added
617 	 * contention from metadata I/O. The current cycle and block are updated
618 	 * (in xlog_state_switch_iclogs()) and read here in a particular order
619 	 * to avoid false negatives (e.g., thinking the metadata LSN is valid
620 	 * when it is not).
621 	 *
622 	 * The current block is always rewound before the cycle is bumped in
623 	 * xlog_state_switch_iclogs() to ensure the current LSN is never seen in
624 	 * a transiently forward state. Instead, we can see the LSN in a
625 	 * transiently behind state if we happen to race with a cycle wrap.
626 	 */
627 	cur_cycle = READ_ONCE(log->l_curr_cycle);
628 	smp_rmb();
629 	cur_block = READ_ONCE(log->l_curr_block);
630 
631 	if ((CYCLE_LSN(lsn) > cur_cycle) ||
632 	    (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block)) {
633 		/*
634 		 * If the metadata LSN appears invalid, it's possible the check
635 		 * above raced with a wrap to the next log cycle. Grab the lock
636 		 * to check for sure.
637 		 */
638 		spin_lock(&log->l_icloglock);
639 		cur_cycle = log->l_curr_cycle;
640 		cur_block = log->l_curr_block;
641 		spin_unlock(&log->l_icloglock);
642 
643 		if ((CYCLE_LSN(lsn) > cur_cycle) ||
644 		    (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block))
645 			valid = false;
646 	}
647 
648 	return valid;
649 }
650 
651 /*
652  * Log vector and shadow buffers can be large, so we need to use kvmalloc() here
653  * to ensure success. Unfortunately, kvmalloc() only allows GFP_KERNEL contexts
654  * to fall back to vmalloc, so we can't actually do anything useful with gfp
655  * flags to control the kmalloc() behaviour within kvmalloc(). Hence kmalloc()
656  * will do direct reclaim and compaction in the slow path, both of which are
657  * horrendously expensive. We just want kmalloc to fail fast and fall back to
658  * vmalloc if it can't get somethign straight away from the free lists or
659  * buddy allocator. Hence we have to open code kvmalloc outselves here.
660  *
661  * This assumes that the caller uses memalloc_nofs_save task context here, so
662  * despite the use of GFP_KERNEL here, we are going to be doing GFP_NOFS
663  * allocations. This is actually the only way to make vmalloc() do GFP_NOFS
664  * allocations, so lets just all pretend this is a GFP_KERNEL context
665  * operation....
666  */
667 static inline void *
xlog_kvmalloc(size_t buf_size)668 xlog_kvmalloc(
669 	size_t		buf_size)
670 {
671 	gfp_t		flags = GFP_KERNEL;
672 	void		*p;
673 
674 	flags &= ~__GFP_DIRECT_RECLAIM;
675 	flags |= __GFP_NOWARN | __GFP_NORETRY;
676 	do {
677 		p = kmalloc(buf_size, flags);
678 		if (!p)
679 			p = vmalloc(buf_size);
680 	} while (!p);
681 
682 	return p;
683 }
684 
685 #endif	/* __XFS_LOG_PRIV_H__ */
686