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 struct xfs_log_callback;
14
15 /*
16 * Flags for log structure
17 */
18 #define XLOG_ACTIVE_RECOVERY 0x2 /* in the middle of recovery */
19 #define XLOG_RECOVERY_NEEDED 0x4 /* log was recovered */
20 #define XLOG_IO_ERROR 0x8 /* log hit an I/O error, and being
21 shutdown */
22 #define XLOG_TAIL_WARN 0x10 /* log tail verify warning issued */
23
24 /*
25 * get client id from packed copy.
26 *
27 * this hack is here because the xlog_pack code copies four bytes
28 * of xlog_op_header containing the fields oh_clientid, oh_flags
29 * and oh_res2 into the packed copy.
30 *
31 * later on this four byte chunk is treated as an int and the
32 * client id is pulled out.
33 *
34 * this has endian issues, of course.
35 */
xlog_get_client_id(__be32 i)36 static inline uint xlog_get_client_id(__be32 i)
37 {
38 return be32_to_cpu(i) >> 24;
39 }
40
41 /*
42 * In core log state
43 */
44 #define XLOG_STATE_ACTIVE 0x0001 /* Current IC log being written to */
45 #define XLOG_STATE_WANT_SYNC 0x0002 /* Want to sync this iclog; no more writes */
46 #define XLOG_STATE_SYNCING 0x0004 /* This IC log is syncing */
47 #define XLOG_STATE_DONE_SYNC 0x0008 /* Done syncing to disk */
48 #define XLOG_STATE_DO_CALLBACK \
49 0x0010 /* Process callback functions */
50 #define XLOG_STATE_CALLBACK 0x0020 /* Callback functions now */
51 #define XLOG_STATE_DIRTY 0x0040 /* Dirty IC log, not ready for ACTIVE status*/
52 #define XLOG_STATE_IOERROR 0x0080 /* IO error happened in sync'ing log */
53 #define XLOG_STATE_IOABORT 0x0100 /* force abort on I/O completion (debug) */
54 #define XLOG_STATE_ALL 0x7FFF /* All possible valid flags */
55 #define XLOG_STATE_NOTUSED 0x8000 /* This IC log not being used */
56
57 /*
58 * Flags to log ticket
59 */
60 #define XLOG_TIC_INITED 0x1 /* has been initialized */
61 #define XLOG_TIC_PERM_RESERV 0x2 /* permanent reservation */
62
63 #define XLOG_TIC_FLAGS \
64 { XLOG_TIC_INITED, "XLOG_TIC_INITED" }, \
65 { XLOG_TIC_PERM_RESERV, "XLOG_TIC_PERM_RESERV" }
66
67 /*
68 * Below are states for covering allocation transactions.
69 * By covering, we mean changing the h_tail_lsn in the last on-disk
70 * log write such that no allocation transactions will be re-done during
71 * recovery after a system crash. Recovery starts at the last on-disk
72 * log write.
73 *
74 * These states are used to insert dummy log entries to cover
75 * space allocation transactions which can undo non-transactional changes
76 * after a crash. Writes to a file with space
77 * already allocated do not result in any transactions. Allocations
78 * might include space beyond the EOF. So if we just push the EOF a
79 * little, the last transaction for the file could contain the wrong
80 * size. If there is no file system activity, after an allocation
81 * transaction, and the system crashes, the allocation transaction
82 * will get replayed and the file will be truncated. This could
83 * be hours/days/... after the allocation occurred.
84 *
85 * The fix for this is to do two dummy transactions when the
86 * system is idle. We need two dummy transaction because the h_tail_lsn
87 * in the log record header needs to point beyond the last possible
88 * non-dummy transaction. The first dummy changes the h_tail_lsn to
89 * the first transaction before the dummy. The second dummy causes
90 * h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn.
91 *
92 * These dummy transactions get committed when everything
93 * is idle (after there has been some activity).
94 *
95 * There are 5 states used to control this.
96 *
97 * IDLE -- no logging has been done on the file system or
98 * we are done covering previous transactions.
99 * NEED -- logging has occurred and we need a dummy transaction
100 * when the log becomes idle.
101 * DONE -- we were in the NEED state and have committed a dummy
102 * transaction.
103 * NEED2 -- we detected that a dummy transaction has gone to the
104 * on disk log with no other transactions.
105 * DONE2 -- we committed a dummy transaction when in the NEED2 state.
106 *
107 * There are two places where we switch states:
108 *
109 * 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2.
110 * We commit the dummy transaction and switch to DONE or DONE2,
111 * respectively. In all other states, we don't do anything.
112 *
113 * 2.) When we finish writing the on-disk log (xlog_state_clean_log).
114 *
115 * No matter what state we are in, if this isn't the dummy
116 * transaction going out, the next state is NEED.
117 * So, if we aren't in the DONE or DONE2 states, the next state
118 * is NEED. We can't be finishing a write of the dummy record
119 * unless it was committed and the state switched to DONE or DONE2.
120 *
121 * If we are in the DONE state and this was a write of the
122 * dummy transaction, we move to NEED2.
123 *
124 * If we are in the DONE2 state and this was a write of the
125 * dummy transaction, we move to IDLE.
126 *
127 *
128 * Writing only one dummy transaction can get appended to
129 * one file space allocation. When this happens, the log recovery
130 * code replays the space allocation and a file could be truncated.
131 * This is why we have the NEED2 and DONE2 states before going idle.
132 */
133
134 #define XLOG_STATE_COVER_IDLE 0
135 #define XLOG_STATE_COVER_NEED 1
136 #define XLOG_STATE_COVER_DONE 2
137 #define XLOG_STATE_COVER_NEED2 3
138 #define XLOG_STATE_COVER_DONE2 4
139
140 #define XLOG_COVER_OPS 5
141
142 /* Ticket reservation region accounting */
143 #define XLOG_TIC_LEN_MAX 15
144
145 /*
146 * Reservation region
147 * As would be stored in xfs_log_iovec but without the i_addr which
148 * we don't care about.
149 */
150 typedef struct xlog_res {
151 uint r_len; /* region length :4 */
152 uint r_type; /* region's transaction type :4 */
153 } xlog_res_t;
154
155 typedef struct xlog_ticket {
156 struct list_head t_queue; /* reserve/write queue */
157 struct task_struct *t_task; /* task that owns this ticket */
158 xlog_tid_t t_tid; /* transaction identifier : 4 */
159 atomic_t t_ref; /* ticket reference count : 4 */
160 int t_curr_res; /* current reservation in bytes : 4 */
161 int t_unit_res; /* unit reservation in bytes : 4 */
162 char t_ocnt; /* original count : 1 */
163 char t_cnt; /* current count : 1 */
164 char t_clientid; /* who does this belong to; : 1 */
165 char t_flags; /* properties of reservation : 1 */
166
167 /* reservation array fields */
168 uint t_res_num; /* num in array : 4 */
169 uint t_res_num_ophdrs; /* num op hdrs : 4 */
170 uint t_res_arr_sum; /* array sum : 4 */
171 uint t_res_o_flow; /* sum overflow : 4 */
172 xlog_res_t t_res_arr[XLOG_TIC_LEN_MAX]; /* array of res : 8 * 15 */
173 } xlog_ticket_t;
174
175 /*
176 * - A log record header is 512 bytes. There is plenty of room to grow the
177 * xlog_rec_header_t into the reserved space.
178 * - ic_data follows, so a write to disk can start at the beginning of
179 * the iclog.
180 * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
181 * - ic_next is the pointer to the next iclog in the ring.
182 * - ic_bp is a pointer to the buffer used to write this incore log to disk.
183 * - ic_log is a pointer back to the global log structure.
184 * - ic_callback is a linked list of callback function/argument pairs to be
185 * called after an iclog finishes writing.
186 * - ic_size is the full size of the header plus data.
187 * - ic_offset is the current number of bytes written to in this iclog.
188 * - ic_refcnt is bumped when someone is writing to the log.
189 * - ic_state is the state of the iclog.
190 *
191 * Because of cacheline contention on large machines, we need to separate
192 * various resources onto different cachelines. To start with, make the
193 * structure cacheline aligned. The following fields can be contended on
194 * by independent processes:
195 *
196 * - ic_callback_*
197 * - ic_refcnt
198 * - fields protected by the global l_icloglock
199 *
200 * so we need to ensure that these fields are located in separate cachelines.
201 * We'll put all the read-only and l_icloglock fields in the first cacheline,
202 * and move everything else out to subsequent cachelines.
203 */
204 typedef struct xlog_in_core {
205 wait_queue_head_t ic_force_wait;
206 wait_queue_head_t ic_write_wait;
207 struct xlog_in_core *ic_next;
208 struct xlog_in_core *ic_prev;
209 struct xfs_buf *ic_bp;
210 struct xlog *ic_log;
211 int ic_size;
212 int ic_offset;
213 int ic_bwritecnt;
214 unsigned short ic_state;
215 char *ic_datap; /* pointer to iclog data */
216
217 /* Callback structures need their own cacheline */
218 spinlock_t ic_callback_lock ____cacheline_aligned_in_smp;
219 struct xfs_log_callback *ic_callback;
220 struct xfs_log_callback **ic_callback_tail;
221
222 /* reference counts need their own cacheline */
223 atomic_t ic_refcnt ____cacheline_aligned_in_smp;
224 xlog_in_core_2_t *ic_data;
225 #define ic_header ic_data->hic_header
226 } xlog_in_core_t;
227
228 /*
229 * The CIL context is used to aggregate per-transaction details as well be
230 * passed to the iclog for checkpoint post-commit processing. After being
231 * passed to the iclog, another context needs to be allocated for tracking the
232 * next set of transactions to be aggregated into a checkpoint.
233 */
234 struct xfs_cil;
235
236 struct xfs_cil_ctx {
237 struct xfs_cil *cil;
238 xfs_lsn_t sequence; /* chkpt sequence # */
239 xfs_lsn_t start_lsn; /* first LSN of chkpt commit */
240 xfs_lsn_t commit_lsn; /* chkpt commit record lsn */
241 struct xlog_ticket *ticket; /* chkpt ticket */
242 int nvecs; /* number of regions */
243 int space_used; /* aggregate size of regions */
244 struct list_head busy_extents; /* busy extents in chkpt */
245 struct xfs_log_vec *lv_chain; /* logvecs being pushed */
246 struct xfs_log_callback log_cb; /* completion callback hook. */
247 struct list_head committing; /* ctx committing list */
248 struct work_struct discard_endio_work;
249 };
250
251 /*
252 * Committed Item List structure
253 *
254 * This structure is used to track log items that have been committed but not
255 * yet written into the log. It is used only when the delayed logging mount
256 * option is enabled.
257 *
258 * This structure tracks the list of committing checkpoint contexts so
259 * we can avoid the problem of having to hold out new transactions during a
260 * flush until we have a the commit record LSN of the checkpoint. We can
261 * traverse the list of committing contexts in xlog_cil_push_lsn() to find a
262 * sequence match and extract the commit LSN directly from there. If the
263 * checkpoint is still in the process of committing, we can block waiting for
264 * the commit LSN to be determined as well. This should make synchronous
265 * operations almost as efficient as the old logging methods.
266 */
267 struct xfs_cil {
268 struct xlog *xc_log;
269 struct list_head xc_cil;
270 spinlock_t xc_cil_lock;
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_lsn_t xc_push_seq;
277 struct list_head xc_committing;
278 wait_queue_head_t xc_commit_wait;
279 xfs_lsn_t xc_current_sequence;
280 struct work_struct xc_push_work;
281 } ____cacheline_aligned_in_smp;
282
283 /*
284 * The amount of log space we allow the CIL to aggregate is difficult to size.
285 * Whatever we choose, we have to make sure we can get a reservation for the
286 * log space effectively, that it is large enough to capture sufficient
287 * relogging to reduce log buffer IO significantly, but it is not too large for
288 * the log or induces too much latency when writing out through the iclogs. We
289 * track both space consumed and the number of vectors in the checkpoint
290 * context, so we need to decide which to use for limiting.
291 *
292 * Every log buffer we write out during a push needs a header reserved, which
293 * is at least one sector and more for v2 logs. Hence we need a reservation of
294 * at least 512 bytes per 32k of log space just for the LR headers. That means
295 * 16KB of reservation per megabyte of delayed logging space we will consume,
296 * plus various headers. The number of headers will vary based on the num of
297 * io vectors, so limiting on a specific number of vectors is going to result
298 * in transactions of varying size. IOWs, it is more consistent to track and
299 * limit space consumed in the log rather than by the number of objects being
300 * logged in order to prevent checkpoint ticket overruns.
301 *
302 * Further, use of static reservations through the log grant mechanism is
303 * problematic. It introduces a lot of complexity (e.g. reserve grant vs write
304 * grant) and a significant deadlock potential because regranting write space
305 * can block on log pushes. Hence if we have to regrant log space during a log
306 * push, we can deadlock.
307 *
308 * However, we can avoid this by use of a dynamic "reservation stealing"
309 * technique during transaction commit whereby unused reservation space in the
310 * transaction ticket is transferred to the CIL ctx commit ticket to cover the
311 * space needed by the checkpoint transaction. This means that we never need to
312 * specifically reserve space for the CIL checkpoint transaction, nor do we
313 * need to regrant space once the checkpoint completes. This also means the
314 * checkpoint transaction ticket is specific to the checkpoint context, rather
315 * than the CIL itself.
316 *
317 * With dynamic reservations, we can effectively make up arbitrary limits for
318 * the checkpoint size so long as they don't violate any other size rules.
319 * Recovery imposes a rule that no transaction exceed half the log, so we are
320 * limited by that. Furthermore, the log transaction reservation subsystem
321 * tries to keep 25% of the log free, so we need to keep below that limit or we
322 * risk running out of free log space to start any new transactions.
323 *
324 * In order to keep background CIL push efficient, we will set a lower
325 * threshold at which background pushing is attempted without blocking current
326 * transaction commits. A separate, higher bound defines when CIL pushes are
327 * enforced to ensure we stay within our maximum checkpoint size bounds.
328 * threshold, yet give us plenty of space for aggregation on large logs.
329 */
330 #define XLOG_CIL_SPACE_LIMIT(log) (log->l_logsize >> 3)
331
332 /*
333 * ticket grant locks, queues and accounting have their own cachlines
334 * as these are quite hot and can be operated on concurrently.
335 */
336 struct xlog_grant_head {
337 spinlock_t lock ____cacheline_aligned_in_smp;
338 struct list_head waiters;
339 atomic64_t grant;
340 };
341
342 /*
343 * The reservation head lsn is not made up of a cycle number and block number.
344 * Instead, it uses a cycle number and byte number. Logs don't expect to
345 * overflow 31 bits worth of byte offset, so using a byte number will mean
346 * that round off problems won't occur when releasing partial reservations.
347 */
348 struct xlog {
349 /* The following fields don't need locking */
350 struct xfs_mount *l_mp; /* mount point */
351 struct xfs_ail *l_ailp; /* AIL log is working with */
352 struct xfs_cil *l_cilp; /* CIL log is working with */
353 struct xfs_buf *l_xbuf; /* extra buffer for log
354 * wrapping */
355 struct xfs_buftarg *l_targ; /* buftarg of log */
356 struct delayed_work l_work; /* background flush work */
357 uint l_flags;
358 uint l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
359 struct list_head *l_buf_cancel_table;
360 int l_iclog_hsize; /* size of iclog header */
361 int l_iclog_heads; /* # of iclog header sectors */
362 uint l_sectBBsize; /* sector size in BBs (2^n) */
363 int l_iclog_size; /* size of log in bytes */
364 int l_iclog_size_log; /* log power size of log */
365 int l_iclog_bufs; /* number of iclog buffers */
366 xfs_daddr_t l_logBBstart; /* start block of log */
367 int l_logsize; /* size of log in bytes */
368 int l_logBBsize; /* size of log in BB chunks */
369
370 /* The following block of fields are changed while holding icloglock */
371 wait_queue_head_t l_flush_wait ____cacheline_aligned_in_smp;
372 /* waiting for iclog flush */
373 int l_covered_state;/* state of "covering disk
374 * log entries" */
375 xlog_in_core_t *l_iclog; /* head log queue */
376 spinlock_t l_icloglock; /* grab to change iclog state */
377 int l_curr_cycle; /* Cycle number of log writes */
378 int l_prev_cycle; /* Cycle number before last
379 * block increment */
380 int l_curr_block; /* current logical log block */
381 int l_prev_block; /* previous logical log block */
382
383 /*
384 * l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
385 * read without needing to hold specific locks. To avoid operations
386 * contending with other hot objects, place each of them on a separate
387 * cacheline.
388 */
389 /* lsn of last LR on disk */
390 atomic64_t l_last_sync_lsn ____cacheline_aligned_in_smp;
391 /* lsn of 1st LR with unflushed * buffers */
392 atomic64_t l_tail_lsn ____cacheline_aligned_in_smp;
393
394 struct xlog_grant_head l_reserve_head;
395 struct xlog_grant_head l_write_head;
396
397 struct xfs_kobj l_kobj;
398
399 /* The following field are used for debugging; need to hold icloglock */
400 #ifdef DEBUG
401 void *l_iclog_bak[XLOG_MAX_ICLOGS];
402 /* log record crc error injection factor */
403 uint32_t l_badcrc_factor;
404 #endif
405 /* log recovery lsn tracking (for buffer submission */
406 xfs_lsn_t l_recovery_lsn;
407 };
408
409 #define XLOG_BUF_CANCEL_BUCKET(log, blkno) \
410 ((log)->l_buf_cancel_table + ((uint64_t)blkno % XLOG_BC_TABLE_SIZE))
411
412 #define XLOG_FORCED_SHUTDOWN(log) ((log)->l_flags & XLOG_IO_ERROR)
413
414 /* common routines */
415 extern int
416 xlog_recover(
417 struct xlog *log);
418 extern int
419 xlog_recover_finish(
420 struct xlog *log);
421 extern int
422 xlog_recover_cancel(struct xlog *);
423
424 extern __le32 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
425 char *dp, int size);
426
427 extern kmem_zone_t *xfs_log_ticket_zone;
428 struct xlog_ticket *
429 xlog_ticket_alloc(
430 struct xlog *log,
431 int unit_bytes,
432 int count,
433 char client,
434 bool permanent,
435 xfs_km_flags_t alloc_flags);
436
437
438 static inline void
xlog_write_adv_cnt(void ** ptr,int * len,int * off,size_t bytes)439 xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes)
440 {
441 *ptr += bytes;
442 *len -= bytes;
443 *off += bytes;
444 }
445
446 void xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
447 void xlog_print_trans(struct xfs_trans *);
448 int
449 xlog_write(
450 struct xlog *log,
451 struct xfs_log_vec *log_vector,
452 struct xlog_ticket *tic,
453 xfs_lsn_t *start_lsn,
454 struct xlog_in_core **commit_iclog,
455 uint flags);
456
457 /*
458 * When we crack an atomic LSN, we sample it first so that the value will not
459 * change while we are cracking it into the component values. This means we
460 * will always get consistent component values to work from. This should always
461 * be used to sample and crack LSNs that are stored and updated in atomic
462 * variables.
463 */
464 static inline void
xlog_crack_atomic_lsn(atomic64_t * lsn,uint * cycle,uint * block)465 xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
466 {
467 xfs_lsn_t val = atomic64_read(lsn);
468
469 *cycle = CYCLE_LSN(val);
470 *block = BLOCK_LSN(val);
471 }
472
473 /*
474 * Calculate and assign a value to an atomic LSN variable from component pieces.
475 */
476 static inline void
xlog_assign_atomic_lsn(atomic64_t * lsn,uint cycle,uint block)477 xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
478 {
479 atomic64_set(lsn, xlog_assign_lsn(cycle, block));
480 }
481
482 /*
483 * When we crack the grant head, we sample it first so that the value will not
484 * change while we are cracking it into the component values. This means we
485 * will always get consistent component values to work from.
486 */
487 static inline void
xlog_crack_grant_head_val(int64_t val,int * cycle,int * space)488 xlog_crack_grant_head_val(int64_t val, int *cycle, int *space)
489 {
490 *cycle = val >> 32;
491 *space = val & 0xffffffff;
492 }
493
494 static inline void
xlog_crack_grant_head(atomic64_t * head,int * cycle,int * space)495 xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space)
496 {
497 xlog_crack_grant_head_val(atomic64_read(head), cycle, space);
498 }
499
500 static inline int64_t
xlog_assign_grant_head_val(int cycle,int space)501 xlog_assign_grant_head_val(int cycle, int space)
502 {
503 return ((int64_t)cycle << 32) | space;
504 }
505
506 static inline void
xlog_assign_grant_head(atomic64_t * head,int cycle,int space)507 xlog_assign_grant_head(atomic64_t *head, int cycle, int space)
508 {
509 atomic64_set(head, xlog_assign_grant_head_val(cycle, space));
510 }
511
512 /*
513 * Committed Item List interfaces
514 */
515 int xlog_cil_init(struct xlog *log);
516 void xlog_cil_init_post_recovery(struct xlog *log);
517 void xlog_cil_destroy(struct xlog *log);
518 bool xlog_cil_empty(struct xlog *log);
519
520 /*
521 * CIL force routines
522 */
523 xfs_lsn_t
524 xlog_cil_force_lsn(
525 struct xlog *log,
526 xfs_lsn_t sequence);
527
528 static inline void
xlog_cil_force(struct xlog * log)529 xlog_cil_force(struct xlog *log)
530 {
531 xlog_cil_force_lsn(log, log->l_cilp->xc_current_sequence);
532 }
533
534 /*
535 * Unmount record type is used as a pseudo transaction type for the ticket.
536 * It's value must be outside the range of XFS_TRANS_* values.
537 */
538 #define XLOG_UNMOUNT_REC_TYPE (-1U)
539
540 /*
541 * Wrapper function for waiting on a wait queue serialised against wakeups
542 * by a spinlock. This matches the semantics of all the wait queues used in the
543 * log code.
544 */
xlog_wait(wait_queue_head_t * wq,spinlock_t * lock)545 static inline void xlog_wait(wait_queue_head_t *wq, spinlock_t *lock)
546 {
547 DECLARE_WAITQUEUE(wait, current);
548
549 add_wait_queue_exclusive(wq, &wait);
550 __set_current_state(TASK_UNINTERRUPTIBLE);
551 spin_unlock(lock);
552 schedule();
553 remove_wait_queue(wq, &wait);
554 }
555
556 /*
557 * The LSN is valid so long as it is behind the current LSN. If it isn't, this
558 * means that the next log record that includes this metadata could have a
559 * smaller LSN. In turn, this means that the modification in the log would not
560 * replay.
561 */
562 static inline bool
xlog_valid_lsn(struct xlog * log,xfs_lsn_t lsn)563 xlog_valid_lsn(
564 struct xlog *log,
565 xfs_lsn_t lsn)
566 {
567 int cur_cycle;
568 int cur_block;
569 bool valid = true;
570
571 /*
572 * First, sample the current lsn without locking to avoid added
573 * contention from metadata I/O. The current cycle and block are updated
574 * (in xlog_state_switch_iclogs()) and read here in a particular order
575 * to avoid false negatives (e.g., thinking the metadata LSN is valid
576 * when it is not).
577 *
578 * The current block is always rewound before the cycle is bumped in
579 * xlog_state_switch_iclogs() to ensure the current LSN is never seen in
580 * a transiently forward state. Instead, we can see the LSN in a
581 * transiently behind state if we happen to race with a cycle wrap.
582 */
583 cur_cycle = READ_ONCE(log->l_curr_cycle);
584 smp_rmb();
585 cur_block = READ_ONCE(log->l_curr_block);
586
587 if ((CYCLE_LSN(lsn) > cur_cycle) ||
588 (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block)) {
589 /*
590 * If the metadata LSN appears invalid, it's possible the check
591 * above raced with a wrap to the next log cycle. Grab the lock
592 * to check for sure.
593 */
594 spin_lock(&log->l_icloglock);
595 cur_cycle = log->l_curr_cycle;
596 cur_block = log->l_curr_block;
597 spin_unlock(&log->l_icloglock);
598
599 if ((CYCLE_LSN(lsn) > cur_cycle) ||
600 (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block))
601 valid = false;
602 }
603
604 return valid;
605 }
606
607 #endif /* __XFS_LOG_PRIV_H__ */
608