1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
6 #ifndef __XFS_LOG_PRIV_H__
7 #define __XFS_LOG_PRIV_H__
15 * Flags for log structure
17 #define XLOG_ACTIVE_RECOVERY 0x2 /* in the middle of recovery */
18 #define XLOG_RECOVERY_NEEDED 0x4 /* log was recovered */
19 #define XLOG_IO_ERROR 0x8 /* log hit an I/O error, and being
21 #define XLOG_TAIL_WARN 0x10 /* log tail verify warning issued */
24 * get client id from packed copy.
26 * this hack is here because the xlog_pack code copies four bytes
27 * of xlog_op_header containing the fields oh_clientid, oh_flags
28 * and oh_res2 into the packed copy.
30 * later on this four byte chunk is treated as an int and the
31 * client id is pulled out.
33 * this has endian issues, of course.
35 static inline uint xlog_get_client_id(__be32 i)
37 return be32_to_cpu(i) >> 24;
43 enum xlog_iclog_state {
44 XLOG_STATE_ACTIVE, /* Current IC log being written to */
45 XLOG_STATE_WANT_SYNC, /* Want to sync this iclog; no more writes */
46 XLOG_STATE_SYNCING, /* This IC log is syncing */
47 XLOG_STATE_DONE_SYNC, /* Done syncing to disk */
48 XLOG_STATE_CALLBACK, /* Callback functions now */
49 XLOG_STATE_DIRTY, /* Dirty IC log, not ready for ACTIVE status */
50 XLOG_STATE_IOERROR, /* IO error happened in sync'ing log */
56 #define XLOG_TIC_PERM_RESERV 0x1 /* permanent reservation */
58 #define XLOG_TIC_FLAGS \
59 { XLOG_TIC_PERM_RESERV, "XLOG_TIC_PERM_RESERV" }
62 * Below are states for covering allocation transactions.
63 * By covering, we mean changing the h_tail_lsn in the last on-disk
64 * log write such that no allocation transactions will be re-done during
65 * recovery after a system crash. Recovery starts at the last on-disk
68 * These states are used to insert dummy log entries to cover
69 * space allocation transactions which can undo non-transactional changes
70 * after a crash. Writes to a file with space
71 * already allocated do not result in any transactions. Allocations
72 * might include space beyond the EOF. So if we just push the EOF a
73 * little, the last transaction for the file could contain the wrong
74 * size. If there is no file system activity, after an allocation
75 * transaction, and the system crashes, the allocation transaction
76 * will get replayed and the file will be truncated. This could
77 * be hours/days/... after the allocation occurred.
79 * The fix for this is to do two dummy transactions when the
80 * system is idle. We need two dummy transaction because the h_tail_lsn
81 * in the log record header needs to point beyond the last possible
82 * non-dummy transaction. The first dummy changes the h_tail_lsn to
83 * the first transaction before the dummy. The second dummy causes
84 * h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn.
86 * These dummy transactions get committed when everything
87 * is idle (after there has been some activity).
89 * There are 5 states used to control this.
91 * IDLE -- no logging has been done on the file system or
92 * we are done covering previous transactions.
93 * NEED -- logging has occurred and we need a dummy transaction
94 * when the log becomes idle.
95 * DONE -- we were in the NEED state and have committed a dummy
97 * NEED2 -- we detected that a dummy transaction has gone to the
98 * on disk log with no other transactions.
99 * DONE2 -- we committed a dummy transaction when in the NEED2 state.
101 * There are two places where we switch states:
103 * 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2.
104 * We commit the dummy transaction and switch to DONE or DONE2,
105 * respectively. In all other states, we don't do anything.
107 * 2.) When we finish writing the on-disk log (xlog_state_clean_log).
109 * No matter what state we are in, if this isn't the dummy
110 * transaction going out, the next state is NEED.
111 * So, if we aren't in the DONE or DONE2 states, the next state
112 * is NEED. We can't be finishing a write of the dummy record
113 * unless it was committed and the state switched to DONE or DONE2.
115 * If we are in the DONE state and this was a write of the
116 * dummy transaction, we move to NEED2.
118 * If we are in the DONE2 state and this was a write of the
119 * dummy transaction, we move to IDLE.
122 * Writing only one dummy transaction can get appended to
123 * one file space allocation. When this happens, the log recovery
124 * code replays the space allocation and a file could be truncated.
125 * This is why we have the NEED2 and DONE2 states before going idle.
128 #define XLOG_STATE_COVER_IDLE 0
129 #define XLOG_STATE_COVER_NEED 1
130 #define XLOG_STATE_COVER_DONE 2
131 #define XLOG_STATE_COVER_NEED2 3
132 #define XLOG_STATE_COVER_DONE2 4
134 #define XLOG_COVER_OPS 5
136 /* Ticket reservation region accounting */
137 #define XLOG_TIC_LEN_MAX 15
141 * As would be stored in xfs_log_iovec but without the i_addr which
142 * we don't care about.
144 typedef struct xlog_res {
145 uint r_len; /* region length :4 */
146 uint r_type; /* region's transaction type :4 */
149 typedef struct xlog_ticket {
150 struct list_head t_queue; /* reserve/write queue */
151 struct task_struct *t_task; /* task that owns this ticket */
152 xlog_tid_t t_tid; /* transaction identifier : 4 */
153 atomic_t t_ref; /* ticket reference count : 4 */
154 int t_curr_res; /* current reservation in bytes : 4 */
155 int t_unit_res; /* unit reservation in bytes : 4 */
156 char t_ocnt; /* original count : 1 */
157 char t_cnt; /* current count : 1 */
158 char t_clientid; /* who does this belong to; : 1 */
159 char t_flags; /* properties of reservation : 1 */
161 /* reservation array fields */
162 uint t_res_num; /* num in array : 4 */
163 uint t_res_num_ophdrs; /* num op hdrs : 4 */
164 uint t_res_arr_sum; /* array sum : 4 */
165 uint t_res_o_flow; /* sum overflow : 4 */
166 xlog_res_t t_res_arr[XLOG_TIC_LEN_MAX]; /* array of res : 8 * 15 */
170 * - A log record header is 512 bytes. There is plenty of room to grow the
171 * xlog_rec_header_t into the reserved space.
172 * - ic_data follows, so a write to disk can start at the beginning of
174 * - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
175 * - ic_next is the pointer to the next iclog in the ring.
176 * - ic_log is a pointer back to the global log structure.
177 * - ic_size is the full size of the log buffer, minus the cycle headers.
178 * - ic_offset is the current number of bytes written to in this iclog.
179 * - ic_refcnt is bumped when someone is writing to the log.
180 * - ic_state is the state of the iclog.
182 * Because of cacheline contention on large machines, we need to separate
183 * various resources onto different cachelines. To start with, make the
184 * structure cacheline aligned. The following fields can be contended on
185 * by independent processes:
189 * - fields protected by the global l_icloglock
191 * so we need to ensure that these fields are located in separate cachelines.
192 * We'll put all the read-only and l_icloglock fields in the first cacheline,
193 * and move everything else out to subsequent cachelines.
195 typedef struct xlog_in_core {
196 wait_queue_head_t ic_force_wait;
197 wait_queue_head_t ic_write_wait;
198 struct xlog_in_core *ic_next;
199 struct xlog_in_core *ic_prev;
203 enum xlog_iclog_state ic_state;
204 char *ic_datap; /* pointer to iclog data */
206 /* Callback structures need their own cacheline */
207 spinlock_t ic_callback_lock ____cacheline_aligned_in_smp;
208 struct list_head ic_callbacks;
210 /* reference counts need their own cacheline */
211 atomic_t ic_refcnt ____cacheline_aligned_in_smp;
212 xlog_in_core_2_t *ic_data;
213 #define ic_header ic_data->hic_header
215 bool ic_fail_crc : 1;
217 struct semaphore ic_sema;
218 struct work_struct ic_end_io_work;
220 struct bio_vec ic_bvec[];
224 * The CIL context is used to aggregate per-transaction details as well be
225 * passed to the iclog for checkpoint post-commit processing. After being
226 * passed to the iclog, another context needs to be allocated for tracking the
227 * next set of transactions to be aggregated into a checkpoint.
233 xfs_lsn_t sequence; /* chkpt sequence # */
234 xfs_lsn_t start_lsn; /* first LSN of chkpt commit */
235 xfs_lsn_t commit_lsn; /* chkpt commit record lsn */
236 struct xlog_ticket *ticket; /* chkpt ticket */
237 int nvecs; /* number of regions */
238 int space_used; /* aggregate size of regions */
239 struct list_head busy_extents; /* busy extents in chkpt */
240 struct xfs_log_vec *lv_chain; /* logvecs being pushed */
241 struct list_head iclog_entry;
242 struct list_head committing; /* ctx committing list */
243 struct work_struct discard_endio_work;
247 * Committed Item List structure
249 * This structure is used to track log items that have been committed but not
250 * yet written into the log. It is used only when the delayed logging mount
253 * This structure tracks the list of committing checkpoint contexts so
254 * we can avoid the problem of having to hold out new transactions during a
255 * flush until we have a the commit record LSN of the checkpoint. We can
256 * traverse the list of committing contexts in xlog_cil_push_lsn() to find a
257 * sequence match and extract the commit LSN directly from there. If the
258 * checkpoint is still in the process of committing, we can block waiting for
259 * the commit LSN to be determined as well. This should make synchronous
260 * operations almost as efficient as the old logging methods.
264 struct list_head xc_cil;
265 spinlock_t xc_cil_lock;
267 struct rw_semaphore xc_ctx_lock ____cacheline_aligned_in_smp;
268 struct xfs_cil_ctx *xc_ctx;
270 spinlock_t xc_push_lock ____cacheline_aligned_in_smp;
271 xfs_lsn_t xc_push_seq;
272 struct list_head xc_committing;
273 wait_queue_head_t xc_commit_wait;
274 xfs_lsn_t xc_current_sequence;
275 struct work_struct xc_push_work;
276 } ____cacheline_aligned_in_smp;
279 * The amount of log space we allow the CIL to aggregate is difficult to size.
280 * Whatever we choose, we have to make sure we can get a reservation for the
281 * log space effectively, that it is large enough to capture sufficient
282 * relogging to reduce log buffer IO significantly, but it is not too large for
283 * the log or induces too much latency when writing out through the iclogs. We
284 * track both space consumed and the number of vectors in the checkpoint
285 * context, so we need to decide which to use for limiting.
287 * Every log buffer we write out during a push needs a header reserved, which
288 * is at least one sector and more for v2 logs. Hence we need a reservation of
289 * at least 512 bytes per 32k of log space just for the LR headers. That means
290 * 16KB of reservation per megabyte of delayed logging space we will consume,
291 * plus various headers. The number of headers will vary based on the num of
292 * io vectors, so limiting on a specific number of vectors is going to result
293 * in transactions of varying size. IOWs, it is more consistent to track and
294 * limit space consumed in the log rather than by the number of objects being
295 * logged in order to prevent checkpoint ticket overruns.
297 * Further, use of static reservations through the log grant mechanism is
298 * problematic. It introduces a lot of complexity (e.g. reserve grant vs write
299 * grant) and a significant deadlock potential because regranting write space
300 * can block on log pushes. Hence if we have to regrant log space during a log
301 * push, we can deadlock.
303 * However, we can avoid this by use of a dynamic "reservation stealing"
304 * technique during transaction commit whereby unused reservation space in the
305 * transaction ticket is transferred to the CIL ctx commit ticket to cover the
306 * space needed by the checkpoint transaction. This means that we never need to
307 * specifically reserve space for the CIL checkpoint transaction, nor do we
308 * need to regrant space once the checkpoint completes. This also means the
309 * checkpoint transaction ticket is specific to the checkpoint context, rather
310 * than the CIL itself.
312 * With dynamic reservations, we can effectively make up arbitrary limits for
313 * the checkpoint size so long as they don't violate any other size rules.
314 * Recovery imposes a rule that no transaction exceed half the log, so we are
315 * limited by that. Furthermore, the log transaction reservation subsystem
316 * tries to keep 25% of the log free, so we need to keep below that limit or we
317 * risk running out of free log space to start any new transactions.
319 * In order to keep background CIL push efficient, we will set a lower
320 * threshold at which background pushing is attempted without blocking current
321 * transaction commits. A separate, higher bound defines when CIL pushes are
322 * enforced to ensure we stay within our maximum checkpoint size bounds.
323 * threshold, yet give us plenty of space for aggregation on large logs.
325 #define XLOG_CIL_SPACE_LIMIT(log) (log->l_logsize >> 3)
328 * ticket grant locks, queues and accounting have their own cachlines
329 * as these are quite hot and can be operated on concurrently.
331 struct xlog_grant_head {
332 spinlock_t lock ____cacheline_aligned_in_smp;
333 struct list_head waiters;
338 * The reservation head lsn is not made up of a cycle number and block number.
339 * Instead, it uses a cycle number and byte number. Logs don't expect to
340 * overflow 31 bits worth of byte offset, so using a byte number will mean
341 * that round off problems won't occur when releasing partial reservations.
344 /* The following fields don't need locking */
345 struct xfs_mount *l_mp; /* mount point */
346 struct xfs_ail *l_ailp; /* AIL log is working with */
347 struct xfs_cil *l_cilp; /* CIL log is working with */
348 struct xfs_buftarg *l_targ; /* buftarg of log */
349 struct workqueue_struct *l_ioend_workqueue; /* for I/O completions */
350 struct delayed_work l_work; /* background flush work */
352 uint l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
353 struct list_head *l_buf_cancel_table;
354 int l_iclog_hsize; /* size of iclog header */
355 int l_iclog_heads; /* # of iclog header sectors */
356 uint l_sectBBsize; /* sector size in BBs (2^n) */
357 int l_iclog_size; /* size of log in bytes */
358 int l_iclog_bufs; /* number of iclog buffers */
359 xfs_daddr_t l_logBBstart; /* start block of log */
360 int l_logsize; /* size of log in bytes */
361 int l_logBBsize; /* size of log in BB chunks */
363 /* The following block of fields are changed while holding icloglock */
364 wait_queue_head_t l_flush_wait ____cacheline_aligned_in_smp;
365 /* waiting for iclog flush */
366 int l_covered_state;/* state of "covering disk
368 xlog_in_core_t *l_iclog; /* head log queue */
369 spinlock_t l_icloglock; /* grab to change iclog state */
370 int l_curr_cycle; /* Cycle number of log writes */
371 int l_prev_cycle; /* Cycle number before last
373 int l_curr_block; /* current logical log block */
374 int l_prev_block; /* previous logical log block */
377 * l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
378 * read without needing to hold specific locks. To avoid operations
379 * contending with other hot objects, place each of them on a separate
382 /* lsn of last LR on disk */
383 atomic64_t l_last_sync_lsn ____cacheline_aligned_in_smp;
384 /* lsn of 1st LR with unflushed * buffers */
385 atomic64_t l_tail_lsn ____cacheline_aligned_in_smp;
387 struct xlog_grant_head l_reserve_head;
388 struct xlog_grant_head l_write_head;
390 struct xfs_kobj l_kobj;
392 /* The following field are used for debugging; need to hold icloglock */
394 void *l_iclog_bak[XLOG_MAX_ICLOGS];
396 /* log recovery lsn tracking (for buffer submission */
397 xfs_lsn_t l_recovery_lsn;
400 #define XLOG_BUF_CANCEL_BUCKET(log, blkno) \
401 ((log)->l_buf_cancel_table + ((uint64_t)blkno % XLOG_BC_TABLE_SIZE))
403 #define XLOG_FORCED_SHUTDOWN(log) \
404 (unlikely((log)->l_flags & XLOG_IO_ERROR))
406 /* common routines */
414 xlog_recover_cancel(struct xlog *);
416 extern __le32 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
419 extern kmem_zone_t *xfs_log_ticket_zone;
427 xfs_km_flags_t alloc_flags);
431 xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes)
438 void xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
439 void xlog_print_trans(struct xfs_trans *);
440 int xlog_write(struct xlog *log, struct xfs_log_vec *log_vector,
441 struct xlog_ticket *tic, xfs_lsn_t *start_lsn,
442 struct xlog_in_core **commit_iclog, uint flags,
443 bool need_start_rec);
444 int xlog_commit_record(struct xlog *log, struct xlog_ticket *ticket,
445 struct xlog_in_core **iclog, xfs_lsn_t *lsn);
446 void xfs_log_ticket_ungrant(struct xlog *log, struct xlog_ticket *ticket);
447 void xfs_log_ticket_regrant(struct xlog *log, struct xlog_ticket *ticket);
450 * When we crack an atomic LSN, we sample it first so that the value will not
451 * change while we are cracking it into the component values. This means we
452 * will always get consistent component values to work from. This should always
453 * be used to sample and crack LSNs that are stored and updated in atomic
457 xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
459 xfs_lsn_t val = atomic64_read(lsn);
461 *cycle = CYCLE_LSN(val);
462 *block = BLOCK_LSN(val);
466 * Calculate and assign a value to an atomic LSN variable from component pieces.
469 xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
471 atomic64_set(lsn, xlog_assign_lsn(cycle, block));
475 * When we crack the grant head, we sample it first so that the value will not
476 * change while we are cracking it into the component values. This means we
477 * will always get consistent component values to work from.
480 xlog_crack_grant_head_val(int64_t val, int *cycle, int *space)
483 *space = val & 0xffffffff;
487 xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space)
489 xlog_crack_grant_head_val(atomic64_read(head), cycle, space);
492 static inline int64_t
493 xlog_assign_grant_head_val(int cycle, int space)
495 return ((int64_t)cycle << 32) | space;
499 xlog_assign_grant_head(atomic64_t *head, int cycle, int space)
501 atomic64_set(head, xlog_assign_grant_head_val(cycle, space));
505 * Committed Item List interfaces
507 int xlog_cil_init(struct xlog *log);
508 void xlog_cil_init_post_recovery(struct xlog *log);
509 void xlog_cil_destroy(struct xlog *log);
510 bool xlog_cil_empty(struct xlog *log);
521 xlog_cil_force(struct xlog *log)
523 xlog_cil_force_lsn(log, log->l_cilp->xc_current_sequence);
527 * Wrapper function for waiting on a wait queue serialised against wakeups
528 * by a spinlock. This matches the semantics of all the wait queues used in the
533 struct wait_queue_head *wq,
534 struct spinlock *lock)
537 DECLARE_WAITQUEUE(wait, current);
539 add_wait_queue_exclusive(wq, &wait);
540 __set_current_state(TASK_UNINTERRUPTIBLE);
543 remove_wait_queue(wq, &wait);
547 * The LSN is valid so long as it is behind the current LSN. If it isn't, this
548 * means that the next log record that includes this metadata could have a
549 * smaller LSN. In turn, this means that the modification in the log would not
562 * First, sample the current lsn without locking to avoid added
563 * contention from metadata I/O. The current cycle and block are updated
564 * (in xlog_state_switch_iclogs()) and read here in a particular order
565 * to avoid false negatives (e.g., thinking the metadata LSN is valid
568 * The current block is always rewound before the cycle is bumped in
569 * xlog_state_switch_iclogs() to ensure the current LSN is never seen in
570 * a transiently forward state. Instead, we can see the LSN in a
571 * transiently behind state if we happen to race with a cycle wrap.
573 cur_cycle = READ_ONCE(log->l_curr_cycle);
575 cur_block = READ_ONCE(log->l_curr_block);
577 if ((CYCLE_LSN(lsn) > cur_cycle) ||
578 (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block)) {
580 * If the metadata LSN appears invalid, it's possible the check
581 * above raced with a wrap to the next log cycle. Grab the lock
584 spin_lock(&log->l_icloglock);
585 cur_cycle = log->l_curr_cycle;
586 cur_block = log->l_curr_block;
587 spin_unlock(&log->l_icloglock);
589 if ((CYCLE_LSN(lsn) > cur_cycle) ||
590 (CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block))
597 #endif /* __XFS_LOG_PRIV_H__ */