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1/*
2 * Copyright (c) 2010 Red Hat, Inc. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it would be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write the Free Software Foundation,
15 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
16 */
17
18#include "xfs.h"
19#include "xfs_fs.h"
20#include "xfs_types.h"
21#include "xfs_bit.h"
22#include "xfs_log.h"
23#include "xfs_inum.h"
24#include "xfs_trans.h"
25#include "xfs_trans_priv.h"
26#include "xfs_log_priv.h"
27#include "xfs_sb.h"
28#include "xfs_ag.h"
29#include "xfs_mount.h"
30#include "xfs_error.h"
31#include "xfs_alloc.h"
32#include "xfs_discard.h"
33
34/*
35 * Perform initial CIL structure initialisation. If the CIL is not
36 * enabled in this filesystem, ensure the log->l_cilp is null so
37 * we can check this conditional to determine if we are doing delayed
38 * logging or not.
39 */
40int
41xlog_cil_init(
42 struct log *log)
43{
44 struct xfs_cil *cil;
45 struct xfs_cil_ctx *ctx;
46
47 log->l_cilp = NULL;
48 if (!(log->l_mp->m_flags & XFS_MOUNT_DELAYLOG))
49 return 0;
50
51 cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL);
52 if (!cil)
53 return ENOMEM;
54
55 ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL);
56 if (!ctx) {
57 kmem_free(cil);
58 return ENOMEM;
59 }
60
61 INIT_LIST_HEAD(&cil->xc_cil);
62 INIT_LIST_HEAD(&cil->xc_committing);
63 spin_lock_init(&cil->xc_cil_lock);
64 init_rwsem(&cil->xc_ctx_lock);
65 init_waitqueue_head(&cil->xc_commit_wait);
66
67 INIT_LIST_HEAD(&ctx->committing);
68 INIT_LIST_HEAD(&ctx->busy_extents);
69 ctx->sequence = 1;
70 ctx->cil = cil;
71 cil->xc_ctx = ctx;
72 cil->xc_current_sequence = ctx->sequence;
73
74 cil->xc_log = log;
75 log->l_cilp = cil;
76 return 0;
77}
78
79void
80xlog_cil_destroy(
81 struct log *log)
82{
83 if (!log->l_cilp)
84 return;
85
86 if (log->l_cilp->xc_ctx) {
87 if (log->l_cilp->xc_ctx->ticket)
88 xfs_log_ticket_put(log->l_cilp->xc_ctx->ticket);
89 kmem_free(log->l_cilp->xc_ctx);
90 }
91
92 ASSERT(list_empty(&log->l_cilp->xc_cil));
93 kmem_free(log->l_cilp);
94}
95
96/*
97 * Allocate a new ticket. Failing to get a new ticket makes it really hard to
98 * recover, so we don't allow failure here. Also, we allocate in a context that
99 * we don't want to be issuing transactions from, so we need to tell the
100 * allocation code this as well.
101 *
102 * We don't reserve any space for the ticket - we are going to steal whatever
103 * space we require from transactions as they commit. To ensure we reserve all
104 * the space required, we need to set the current reservation of the ticket to
105 * zero so that we know to steal the initial transaction overhead from the
106 * first transaction commit.
107 */
108static struct xlog_ticket *
109xlog_cil_ticket_alloc(
110 struct log *log)
111{
112 struct xlog_ticket *tic;
113
114 tic = xlog_ticket_alloc(log, 0, 1, XFS_TRANSACTION, 0,
115 KM_SLEEP|KM_NOFS);
116 tic->t_trans_type = XFS_TRANS_CHECKPOINT;
117
118 /*
119 * set the current reservation to zero so we know to steal the basic
120 * transaction overhead reservation from the first transaction commit.
121 */
122 tic->t_curr_res = 0;
123 return tic;
124}
125
126/*
127 * After the first stage of log recovery is done, we know where the head and
128 * tail of the log are. We need this log initialisation done before we can
129 * initialise the first CIL checkpoint context.
130 *
131 * Here we allocate a log ticket to track space usage during a CIL push. This
132 * ticket is passed to xlog_write() directly so that we don't slowly leak log
133 * space by failing to account for space used by log headers and additional
134 * region headers for split regions.
135 */
136void
137xlog_cil_init_post_recovery(
138 struct log *log)
139{
140 if (!log->l_cilp)
141 return;
142
143 log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log);
144 log->l_cilp->xc_ctx->sequence = 1;
145 log->l_cilp->xc_ctx->commit_lsn = xlog_assign_lsn(log->l_curr_cycle,
146 log->l_curr_block);
147}
148
149/*
150 * Format log item into a flat buffers
151 *
152 * For delayed logging, we need to hold a formatted buffer containing all the
153 * changes on the log item. This enables us to relog the item in memory and
154 * write it out asynchronously without needing to relock the object that was
155 * modified at the time it gets written into the iclog.
156 *
157 * This function builds a vector for the changes in each log item in the
158 * transaction. It then works out the length of the buffer needed for each log
159 * item, allocates them and formats the vector for the item into the buffer.
160 * The buffer is then attached to the log item are then inserted into the
161 * Committed Item List for tracking until the next checkpoint is written out.
162 *
163 * We don't set up region headers during this process; we simply copy the
164 * regions into the flat buffer. We can do this because we still have to do a
165 * formatting step to write the regions into the iclog buffer. Writing the
166 * ophdrs during the iclog write means that we can support splitting large
167 * regions across iclog boundares without needing a change in the format of the
168 * item/region encapsulation.
169 *
170 * Hence what we need to do now is change the rewrite the vector array to point
171 * to the copied region inside the buffer we just allocated. This allows us to
172 * format the regions into the iclog as though they are being formatted
173 * directly out of the objects themselves.
174 */
175static void
176xlog_cil_format_items(
177 struct log *log,
178 struct xfs_log_vec *log_vector)
179{
180 struct xfs_log_vec *lv;
181
182 ASSERT(log_vector);
183 for (lv = log_vector; lv; lv = lv->lv_next) {
184 void *ptr;
185 int index;
186 int len = 0;
187
188 /* build the vector array and calculate it's length */
189 IOP_FORMAT(lv->lv_item, lv->lv_iovecp);
190 for (index = 0; index < lv->lv_niovecs; index++)
191 len += lv->lv_iovecp[index].i_len;
192
193 lv->lv_buf_len = len;
194 lv->lv_buf = kmem_alloc(lv->lv_buf_len, KM_SLEEP|KM_NOFS);
195 ptr = lv->lv_buf;
196
197 for (index = 0; index < lv->lv_niovecs; index++) {
198 struct xfs_log_iovec *vec = &lv->lv_iovecp[index];
199
200 memcpy(ptr, vec->i_addr, vec->i_len);
201 vec->i_addr = ptr;
202 ptr += vec->i_len;
203 }
204 ASSERT(ptr == lv->lv_buf + lv->lv_buf_len);
205 }
206}
207
208/*
209 * Prepare the log item for insertion into the CIL. Calculate the difference in
210 * log space and vectors it will consume, and if it is a new item pin it as
211 * well.
212 */
213STATIC void
214xfs_cil_prepare_item(
215 struct log *log,
216 struct xfs_log_vec *lv,
217 int *len,
218 int *diff_iovecs)
219{
220 struct xfs_log_vec *old = lv->lv_item->li_lv;
221
222 if (old) {
223 /* existing lv on log item, space used is a delta */
224 ASSERT(!list_empty(&lv->lv_item->li_cil));
225 ASSERT(old->lv_buf && old->lv_buf_len && old->lv_niovecs);
226
227 *len += lv->lv_buf_len - old->lv_buf_len;
228 *diff_iovecs += lv->lv_niovecs - old->lv_niovecs;
229 kmem_free(old->lv_buf);
230 kmem_free(old);
231 } else {
232 /* new lv, must pin the log item */
233 ASSERT(!lv->lv_item->li_lv);
234 ASSERT(list_empty(&lv->lv_item->li_cil));
235
236 *len += lv->lv_buf_len;
237 *diff_iovecs += lv->lv_niovecs;
238 IOP_PIN(lv->lv_item);
239
240 }
241
242 /* attach new log vector to log item */
243 lv->lv_item->li_lv = lv;
244
245 /*
246 * If this is the first time the item is being committed to the
247 * CIL, store the sequence number on the log item so we can
248 * tell in future commits whether this is the first checkpoint
249 * the item is being committed into.
250 */
251 if (!lv->lv_item->li_seq)
252 lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence;
253}
254
255/*
256 * Insert the log items into the CIL and calculate the difference in space
257 * consumed by the item. Add the space to the checkpoint ticket and calculate
258 * if the change requires additional log metadata. If it does, take that space
259 * as well. Remove the amount of space we addded to the checkpoint ticket from
260 * the current transaction ticket so that the accounting works out correctly.
261 */
262static void
263xlog_cil_insert_items(
264 struct log *log,
265 struct xfs_log_vec *log_vector,
266 struct xlog_ticket *ticket)
267{
268 struct xfs_cil *cil = log->l_cilp;
269 struct xfs_cil_ctx *ctx = cil->xc_ctx;
270 struct xfs_log_vec *lv;
271 int len = 0;
272 int diff_iovecs = 0;
273 int iclog_space;
274
275 ASSERT(log_vector);
276
277 /*
278 * Do all the accounting aggregation and switching of log vectors
279 * around in a separate loop to the insertion of items into the CIL.
280 * Then we can do a separate loop to update the CIL within a single
281 * lock/unlock pair. This reduces the number of round trips on the CIL
282 * lock from O(nr_logvectors) to O(1) and greatly reduces the overall
283 * hold time for the transaction commit.
284 *
285 * If this is the first time the item is being placed into the CIL in
286 * this context, pin it so it can't be written to disk until the CIL is
287 * flushed to the iclog and the iclog written to disk.
288 *
289 * We can do this safely because the context can't checkpoint until we
290 * are done so it doesn't matter exactly how we update the CIL.
291 */
292 for (lv = log_vector; lv; lv = lv->lv_next)
293 xfs_cil_prepare_item(log, lv, &len, &diff_iovecs);
294
295 /* account for space used by new iovec headers */
296 len += diff_iovecs * sizeof(xlog_op_header_t);
297
298 spin_lock(&cil->xc_cil_lock);
299
300 /* move the items to the tail of the CIL */
301 for (lv = log_vector; lv; lv = lv->lv_next)
302 list_move_tail(&lv->lv_item->li_cil, &cil->xc_cil);
303
304 ctx->nvecs += diff_iovecs;
305
306 /*
307 * Now transfer enough transaction reservation to the context ticket
308 * for the checkpoint. The context ticket is special - the unit
309 * reservation has to grow as well as the current reservation as we
310 * steal from tickets so we can correctly determine the space used
311 * during the transaction commit.
312 */
313 if (ctx->ticket->t_curr_res == 0) {
314 /* first commit in checkpoint, steal the header reservation */
315 ASSERT(ticket->t_curr_res >= ctx->ticket->t_unit_res + len);
316 ctx->ticket->t_curr_res = ctx->ticket->t_unit_res;
317 ticket->t_curr_res -= ctx->ticket->t_unit_res;
318 }
319
320 /* do we need space for more log record headers? */
321 iclog_space = log->l_iclog_size - log->l_iclog_hsize;
322 if (len > 0 && (ctx->space_used / iclog_space !=
323 (ctx->space_used + len) / iclog_space)) {
324 int hdrs;
325
326 hdrs = (len + iclog_space - 1) / iclog_space;
327 /* need to take into account split region headers, too */
328 hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
329 ctx->ticket->t_unit_res += hdrs;
330 ctx->ticket->t_curr_res += hdrs;
331 ticket->t_curr_res -= hdrs;
332 ASSERT(ticket->t_curr_res >= len);
333 }
334 ticket->t_curr_res -= len;
335 ctx->space_used += len;
336
337 spin_unlock(&cil->xc_cil_lock);
338}
339
340static void
341xlog_cil_free_logvec(
342 struct xfs_log_vec *log_vector)
343{
344 struct xfs_log_vec *lv;
345
346 for (lv = log_vector; lv; ) {
347 struct xfs_log_vec *next = lv->lv_next;
348 kmem_free(lv->lv_buf);
349 kmem_free(lv);
350 lv = next;
351 }
352}
353
354/*
355 * Mark all items committed and clear busy extents. We free the log vector
356 * chains in a separate pass so that we unpin the log items as quickly as
357 * possible.
358 */
359static void
360xlog_cil_committed(
361 void *args,
362 int abort)
363{
364 struct xfs_cil_ctx *ctx = args;
365 struct xfs_mount *mp = ctx->cil->xc_log->l_mp;
366
367 xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain,
368 ctx->start_lsn, abort);
369
370 xfs_alloc_busy_sort(&ctx->busy_extents);
371 xfs_alloc_busy_clear(mp, &ctx->busy_extents,
372 (mp->m_flags & XFS_MOUNT_DISCARD) && !abort);
373
374 spin_lock(&ctx->cil->xc_cil_lock);
375 list_del(&ctx->committing);
376 spin_unlock(&ctx->cil->xc_cil_lock);
377
378 xlog_cil_free_logvec(ctx->lv_chain);
379
380 if (!list_empty(&ctx->busy_extents)) {
381 ASSERT(mp->m_flags & XFS_MOUNT_DISCARD);
382
383 xfs_discard_extents(mp, &ctx->busy_extents);
384 xfs_alloc_busy_clear(mp, &ctx->busy_extents, false);
385 }
386
387 kmem_free(ctx);
388}
389
390/*
391 * Push the Committed Item List to the log. If @push_seq flag is zero, then it
392 * is a background flush and so we can chose to ignore it. Otherwise, if the
393 * current sequence is the same as @push_seq we need to do a flush. If
394 * @push_seq is less than the current sequence, then it has already been
395 * flushed and we don't need to do anything - the caller will wait for it to
396 * complete if necessary.
397 *
398 * @push_seq is a value rather than a flag because that allows us to do an
399 * unlocked check of the sequence number for a match. Hence we can allows log
400 * forces to run racily and not issue pushes for the same sequence twice. If we
401 * get a race between multiple pushes for the same sequence they will block on
402 * the first one and then abort, hence avoiding needless pushes.
403 */
404STATIC int
405xlog_cil_push(
406 struct log *log,
407 xfs_lsn_t push_seq)
408{
409 struct xfs_cil *cil = log->l_cilp;
410 struct xfs_log_vec *lv;
411 struct xfs_cil_ctx *ctx;
412 struct xfs_cil_ctx *new_ctx;
413 struct xlog_in_core *commit_iclog;
414 struct xlog_ticket *tic;
415 int num_lv;
416 int num_iovecs;
417 int len;
418 int error = 0;
419 struct xfs_trans_header thdr;
420 struct xfs_log_iovec lhdr;
421 struct xfs_log_vec lvhdr = { NULL };
422 xfs_lsn_t commit_lsn;
423
424 if (!cil)
425 return 0;
426
427 ASSERT(!push_seq || push_seq <= cil->xc_ctx->sequence);
428
429 new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS);
430 new_ctx->ticket = xlog_cil_ticket_alloc(log);
431
432 /*
433 * Lock out transaction commit, but don't block for background pushes
434 * unless we are well over the CIL space limit. See the definition of
435 * XLOG_CIL_HARD_SPACE_LIMIT() for the full explanation of the logic
436 * used here.
437 */
438 if (!down_write_trylock(&cil->xc_ctx_lock)) {
439 if (!push_seq &&
440 cil->xc_ctx->space_used < XLOG_CIL_HARD_SPACE_LIMIT(log))
441 goto out_free_ticket;
442 down_write(&cil->xc_ctx_lock);
443 }
444 ctx = cil->xc_ctx;
445
446 /* check if we've anything to push */
447 if (list_empty(&cil->xc_cil))
448 goto out_skip;
449
450 /* check for spurious background flush */
451 if (!push_seq && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
452 goto out_skip;
453
454 /* check for a previously pushed seqeunce */
455 if (push_seq && push_seq < cil->xc_ctx->sequence)
456 goto out_skip;
457
458 /*
459 * pull all the log vectors off the items in the CIL, and
460 * remove the items from the CIL. We don't need the CIL lock
461 * here because it's only needed on the transaction commit
462 * side which is currently locked out by the flush lock.
463 */
464 lv = NULL;
465 num_lv = 0;
466 num_iovecs = 0;
467 len = 0;
468 while (!list_empty(&cil->xc_cil)) {
469 struct xfs_log_item *item;
470 int i;
471
472 item = list_first_entry(&cil->xc_cil,
473 struct xfs_log_item, li_cil);
474 list_del_init(&item->li_cil);
475 if (!ctx->lv_chain)
476 ctx->lv_chain = item->li_lv;
477 else
478 lv->lv_next = item->li_lv;
479 lv = item->li_lv;
480 item->li_lv = NULL;
481
482 num_lv++;
483 num_iovecs += lv->lv_niovecs;
484 for (i = 0; i < lv->lv_niovecs; i++)
485 len += lv->lv_iovecp[i].i_len;
486 }
487
488 /*
489 * initialise the new context and attach it to the CIL. Then attach
490 * the current context to the CIL committing lsit so it can be found
491 * during log forces to extract the commit lsn of the sequence that
492 * needs to be forced.
493 */
494 INIT_LIST_HEAD(&new_ctx->committing);
495 INIT_LIST_HEAD(&new_ctx->busy_extents);
496 new_ctx->sequence = ctx->sequence + 1;
497 new_ctx->cil = cil;
498 cil->xc_ctx = new_ctx;
499
500 /*
501 * mirror the new sequence into the cil structure so that we can do
502 * unlocked checks against the current sequence in log forces without
503 * risking deferencing a freed context pointer.
504 */
505 cil->xc_current_sequence = new_ctx->sequence;
506
507 /*
508 * The switch is now done, so we can drop the context lock and move out
509 * of a shared context. We can't just go straight to the commit record,
510 * though - we need to synchronise with previous and future commits so
511 * that the commit records are correctly ordered in the log to ensure
512 * that we process items during log IO completion in the correct order.
513 *
514 * For example, if we get an EFI in one checkpoint and the EFD in the
515 * next (e.g. due to log forces), we do not want the checkpoint with
516 * the EFD to be committed before the checkpoint with the EFI. Hence
517 * we must strictly order the commit records of the checkpoints so
518 * that: a) the checkpoint callbacks are attached to the iclogs in the
519 * correct order; and b) the checkpoints are replayed in correct order
520 * in log recovery.
521 *
522 * Hence we need to add this context to the committing context list so
523 * that higher sequences will wait for us to write out a commit record
524 * before they do.
525 */
526 spin_lock(&cil->xc_cil_lock);
527 list_add(&ctx->committing, &cil->xc_committing);
528 spin_unlock(&cil->xc_cil_lock);
529 up_write(&cil->xc_ctx_lock);
530
531 /*
532 * Build a checkpoint transaction header and write it to the log to
533 * begin the transaction. We need to account for the space used by the
534 * transaction header here as it is not accounted for in xlog_write().
535 *
536 * The LSN we need to pass to the log items on transaction commit is
537 * the LSN reported by the first log vector write. If we use the commit
538 * record lsn then we can move the tail beyond the grant write head.
539 */
540 tic = ctx->ticket;
541 thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
542 thdr.th_type = XFS_TRANS_CHECKPOINT;
543 thdr.th_tid = tic->t_tid;
544 thdr.th_num_items = num_iovecs;
545 lhdr.i_addr = &thdr;
546 lhdr.i_len = sizeof(xfs_trans_header_t);
547 lhdr.i_type = XLOG_REG_TYPE_TRANSHDR;
548 tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t);
549
550 lvhdr.lv_niovecs = 1;
551 lvhdr.lv_iovecp = &lhdr;
552 lvhdr.lv_next = ctx->lv_chain;
553
554 error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0);
555 if (error)
556 goto out_abort_free_ticket;
557
558 /*
559 * now that we've written the checkpoint into the log, strictly
560 * order the commit records so replay will get them in the right order.
561 */
562restart:
563 spin_lock(&cil->xc_cil_lock);
564 list_for_each_entry(new_ctx, &cil->xc_committing, committing) {
565 /*
566 * Higher sequences will wait for this one so skip them.
567 * Don't wait for own own sequence, either.
568 */
569 if (new_ctx->sequence >= ctx->sequence)
570 continue;
571 if (!new_ctx->commit_lsn) {
572 /*
573 * It is still being pushed! Wait for the push to
574 * complete, then start again from the beginning.
575 */
576 xlog_wait(&cil->xc_commit_wait, &cil->xc_cil_lock);
577 goto restart;
578 }
579 }
580 spin_unlock(&cil->xc_cil_lock);
581
582 /* xfs_log_done always frees the ticket on error. */
583 commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0);
584 if (commit_lsn == -1)
585 goto out_abort;
586
587 /* attach all the transactions w/ busy extents to iclog */
588 ctx->log_cb.cb_func = xlog_cil_committed;
589 ctx->log_cb.cb_arg = ctx;
590 error = xfs_log_notify(log->l_mp, commit_iclog, &ctx->log_cb);
591 if (error)
592 goto out_abort;
593
594 /*
595 * now the checkpoint commit is complete and we've attached the
596 * callbacks to the iclog we can assign the commit LSN to the context
597 * and wake up anyone who is waiting for the commit to complete.
598 */
599 spin_lock(&cil->xc_cil_lock);
600 ctx->commit_lsn = commit_lsn;
601 wake_up_all(&cil->xc_commit_wait);
602 spin_unlock(&cil->xc_cil_lock);
603
604 /* release the hounds! */
605 return xfs_log_release_iclog(log->l_mp, commit_iclog);
606
607out_skip:
608 up_write(&cil->xc_ctx_lock);
609out_free_ticket:
610 xfs_log_ticket_put(new_ctx->ticket);
611 kmem_free(new_ctx);
612 return 0;
613
614out_abort_free_ticket:
615 xfs_log_ticket_put(tic);
616out_abort:
617 xlog_cil_committed(ctx, XFS_LI_ABORTED);
618 return XFS_ERROR(EIO);
619}
620
621/*
622 * Commit a transaction with the given vector to the Committed Item List.
623 *
624 * To do this, we need to format the item, pin it in memory if required and
625 * account for the space used by the transaction. Once we have done that we
626 * need to release the unused reservation for the transaction, attach the
627 * transaction to the checkpoint context so we carry the busy extents through
628 * to checkpoint completion, and then unlock all the items in the transaction.
629 *
630 * For more specific information about the order of operations in
631 * xfs_log_commit_cil() please refer to the comments in
632 * xfs_trans_commit_iclog().
633 *
634 * Called with the context lock already held in read mode to lock out
635 * background commit, returns without it held once background commits are
636 * allowed again.
637 */
638void
639xfs_log_commit_cil(
640 struct xfs_mount *mp,
641 struct xfs_trans *tp,
642 struct xfs_log_vec *log_vector,
643 xfs_lsn_t *commit_lsn,
644 int flags)
645{
646 struct log *log = mp->m_log;
647 int log_flags = 0;
648 int push = 0;
649
650 if (flags & XFS_TRANS_RELEASE_LOG_RES)
651 log_flags = XFS_LOG_REL_PERM_RESERV;
652
653 /*
654 * do all the hard work of formatting items (including memory
655 * allocation) outside the CIL context lock. This prevents stalling CIL
656 * pushes when we are low on memory and a transaction commit spends a
657 * lot of time in memory reclaim.
658 */
659 xlog_cil_format_items(log, log_vector);
660
661 /* lock out background commit */
662 down_read(&log->l_cilp->xc_ctx_lock);
663 if (commit_lsn)
664 *commit_lsn = log->l_cilp->xc_ctx->sequence;
665
666 xlog_cil_insert_items(log, log_vector, tp->t_ticket);
667
668 /* check we didn't blow the reservation */
669 if (tp->t_ticket->t_curr_res < 0)
670 xlog_print_tic_res(log->l_mp, tp->t_ticket);
671
672 /* attach the transaction to the CIL if it has any busy extents */
673 if (!list_empty(&tp->t_busy)) {
674 spin_lock(&log->l_cilp->xc_cil_lock);
675 list_splice_init(&tp->t_busy,
676 &log->l_cilp->xc_ctx->busy_extents);
677 spin_unlock(&log->l_cilp->xc_cil_lock);
678 }
679
680 tp->t_commit_lsn = *commit_lsn;
681 xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
682 xfs_trans_unreserve_and_mod_sb(tp);
683
684 /*
685 * Once all the items of the transaction have been copied to the CIL,
686 * the items can be unlocked and freed.
687 *
688 * This needs to be done before we drop the CIL context lock because we
689 * have to update state in the log items and unlock them before they go
690 * to disk. If we don't, then the CIL checkpoint can race with us and
691 * we can run checkpoint completion before we've updated and unlocked
692 * the log items. This affects (at least) processing of stale buffers,
693 * inodes and EFIs.
694 */
695 xfs_trans_free_items(tp, *commit_lsn, 0);
696
697 /* check for background commit before unlock */
698 if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log))
699 push = 1;
700
701 up_read(&log->l_cilp->xc_ctx_lock);
702
703 /*
704 * We need to push CIL every so often so we don't cache more than we
705 * can fit in the log. The limit really is that a checkpoint can't be
706 * more than half the log (the current checkpoint is not allowed to
707 * overwrite the previous checkpoint), but commit latency and memory
708 * usage limit this to a smaller size in most cases.
709 */
710 if (push)
711 xlog_cil_push(log, 0);
712}
713
714/*
715 * Conditionally push the CIL based on the sequence passed in.
716 *
717 * We only need to push if we haven't already pushed the sequence
718 * number given. Hence the only time we will trigger a push here is
719 * if the push sequence is the same as the current context.
720 *
721 * We return the current commit lsn to allow the callers to determine if a
722 * iclog flush is necessary following this call.
723 *
724 * XXX: Initially, just push the CIL unconditionally and return whatever
725 * commit lsn is there. It'll be empty, so this is broken for now.
726 */
727xfs_lsn_t
728xlog_cil_force_lsn(
729 struct log *log,
730 xfs_lsn_t sequence)
731{
732 struct xfs_cil *cil = log->l_cilp;
733 struct xfs_cil_ctx *ctx;
734 xfs_lsn_t commit_lsn = NULLCOMMITLSN;
735
736 ASSERT(sequence <= cil->xc_current_sequence);
737
738 /*
739 * check to see if we need to force out the current context.
740 * xlog_cil_push() handles racing pushes for the same sequence,
741 * so no need to deal with it here.
742 */
743 if (sequence == cil->xc_current_sequence)
744 xlog_cil_push(log, sequence);
745
746 /*
747 * See if we can find a previous sequence still committing.
748 * We need to wait for all previous sequence commits to complete
749 * before allowing the force of push_seq to go ahead. Hence block
750 * on commits for those as well.
751 */
752restart:
753 spin_lock(&cil->xc_cil_lock);
754 list_for_each_entry(ctx, &cil->xc_committing, committing) {
755 if (ctx->sequence > sequence)
756 continue;
757 if (!ctx->commit_lsn) {
758 /*
759 * It is still being pushed! Wait for the push to
760 * complete, then start again from the beginning.
761 */
762 xlog_wait(&cil->xc_commit_wait, &cil->xc_cil_lock);
763 goto restart;
764 }
765 if (ctx->sequence != sequence)
766 continue;
767 /* found it! */
768 commit_lsn = ctx->commit_lsn;
769 }
770 spin_unlock(&cil->xc_cil_lock);
771 return commit_lsn;
772}
773
774/*
775 * Check if the current log item was first committed in this sequence.
776 * We can't rely on just the log item being in the CIL, we have to check
777 * the recorded commit sequence number.
778 *
779 * Note: for this to be used in a non-racy manner, it has to be called with
780 * CIL flushing locked out. As a result, it should only be used during the
781 * transaction commit process when deciding what to format into the item.
782 */
783bool
784xfs_log_item_in_current_chkpt(
785 struct xfs_log_item *lip)
786{
787 struct xfs_cil_ctx *ctx;
788
789 if (!(lip->li_mountp->m_flags & XFS_MOUNT_DELAYLOG))
790 return false;
791 if (list_empty(&lip->li_cil))
792 return false;
793
794 ctx = lip->li_mountp->m_log->l_cilp->xc_ctx;
795
796 /*
797 * li_seq is written on the first commit of a log item to record the
798 * first checkpoint it is written to. Hence if it is different to the
799 * current sequence, we're in a new checkpoint.
800 */
801 if (XFS_LSN_CMP(lip->li_seq, ctx->sequence) != 0)
802 return false;
803 return true;
804}
1/*
2 * Copyright (c) 2010 Red Hat, Inc. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it would be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write the Free Software Foundation,
15 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
16 */
17
18#include "xfs.h"
19#include "xfs_fs.h"
20#include "xfs_format.h"
21#include "xfs_log_format.h"
22#include "xfs_shared.h"
23#include "xfs_trans_resv.h"
24#include "xfs_mount.h"
25#include "xfs_error.h"
26#include "xfs_alloc.h"
27#include "xfs_extent_busy.h"
28#include "xfs_discard.h"
29#include "xfs_trans.h"
30#include "xfs_trans_priv.h"
31#include "xfs_log.h"
32#include "xfs_log_priv.h"
33#include "xfs_trace.h"
34
35struct workqueue_struct *xfs_discard_wq;
36
37/*
38 * Allocate a new ticket. Failing to get a new ticket makes it really hard to
39 * recover, so we don't allow failure here. Also, we allocate in a context that
40 * we don't want to be issuing transactions from, so we need to tell the
41 * allocation code this as well.
42 *
43 * We don't reserve any space for the ticket - we are going to steal whatever
44 * space we require from transactions as they commit. To ensure we reserve all
45 * the space required, we need to set the current reservation of the ticket to
46 * zero so that we know to steal the initial transaction overhead from the
47 * first transaction commit.
48 */
49static struct xlog_ticket *
50xlog_cil_ticket_alloc(
51 struct xlog *log)
52{
53 struct xlog_ticket *tic;
54
55 tic = xlog_ticket_alloc(log, 0, 1, XFS_TRANSACTION, 0,
56 KM_SLEEP|KM_NOFS);
57
58 /*
59 * set the current reservation to zero so we know to steal the basic
60 * transaction overhead reservation from the first transaction commit.
61 */
62 tic->t_curr_res = 0;
63 return tic;
64}
65
66/*
67 * After the first stage of log recovery is done, we know where the head and
68 * tail of the log are. We need this log initialisation done before we can
69 * initialise the first CIL checkpoint context.
70 *
71 * Here we allocate a log ticket to track space usage during a CIL push. This
72 * ticket is passed to xlog_write() directly so that we don't slowly leak log
73 * space by failing to account for space used by log headers and additional
74 * region headers for split regions.
75 */
76void
77xlog_cil_init_post_recovery(
78 struct xlog *log)
79{
80 log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log);
81 log->l_cilp->xc_ctx->sequence = 1;
82}
83
84static inline int
85xlog_cil_iovec_space(
86 uint niovecs)
87{
88 return round_up((sizeof(struct xfs_log_vec) +
89 niovecs * sizeof(struct xfs_log_iovec)),
90 sizeof(uint64_t));
91}
92
93/*
94 * Allocate or pin log vector buffers for CIL insertion.
95 *
96 * The CIL currently uses disposable buffers for copying a snapshot of the
97 * modified items into the log during a push. The biggest problem with this is
98 * the requirement to allocate the disposable buffer during the commit if:
99 * a) does not exist; or
100 * b) it is too small
101 *
102 * If we do this allocation within xlog_cil_insert_format_items(), it is done
103 * under the xc_ctx_lock, which means that a CIL push cannot occur during
104 * the memory allocation. This means that we have a potential deadlock situation
105 * under low memory conditions when we have lots of dirty metadata pinned in
106 * the CIL and we need a CIL commit to occur to free memory.
107 *
108 * To avoid this, we need to move the memory allocation outside the
109 * xc_ctx_lock, but because the log vector buffers are disposable, that opens
110 * up a TOCTOU race condition w.r.t. the CIL committing and removing the log
111 * vector buffers between the check and the formatting of the item into the
112 * log vector buffer within the xc_ctx_lock.
113 *
114 * Because the log vector buffer needs to be unchanged during the CIL push
115 * process, we cannot share the buffer between the transaction commit (which
116 * modifies the buffer) and the CIL push context that is writing the changes
117 * into the log. This means skipping preallocation of buffer space is
118 * unreliable, but we most definitely do not want to be allocating and freeing
119 * buffers unnecessarily during commits when overwrites can be done safely.
120 *
121 * The simplest solution to this problem is to allocate a shadow buffer when a
122 * log item is committed for the second time, and then to only use this buffer
123 * if necessary. The buffer can remain attached to the log item until such time
124 * it is needed, and this is the buffer that is reallocated to match the size of
125 * the incoming modification. Then during the formatting of the item we can swap
126 * the active buffer with the new one if we can't reuse the existing buffer. We
127 * don't free the old buffer as it may be reused on the next modification if
128 * it's size is right, otherwise we'll free and reallocate it at that point.
129 *
130 * This function builds a vector for the changes in each log item in the
131 * transaction. It then works out the length of the buffer needed for each log
132 * item, allocates them and attaches the vector to the log item in preparation
133 * for the formatting step which occurs under the xc_ctx_lock.
134 *
135 * While this means the memory footprint goes up, it avoids the repeated
136 * alloc/free pattern that repeated modifications of an item would otherwise
137 * cause, and hence minimises the CPU overhead of such behaviour.
138 */
139static void
140xlog_cil_alloc_shadow_bufs(
141 struct xlog *log,
142 struct xfs_trans *tp)
143{
144 struct xfs_log_item_desc *lidp;
145
146 list_for_each_entry(lidp, &tp->t_items, lid_trans) {
147 struct xfs_log_item *lip = lidp->lid_item;
148 struct xfs_log_vec *lv;
149 int niovecs = 0;
150 int nbytes = 0;
151 int buf_size;
152 bool ordered = false;
153
154 /* Skip items which aren't dirty in this transaction. */
155 if (!(lidp->lid_flags & XFS_LID_DIRTY))
156 continue;
157
158 /* get number of vecs and size of data to be stored */
159 lip->li_ops->iop_size(lip, &niovecs, &nbytes);
160
161 /*
162 * Ordered items need to be tracked but we do not wish to write
163 * them. We need a logvec to track the object, but we do not
164 * need an iovec or buffer to be allocated for copying data.
165 */
166 if (niovecs == XFS_LOG_VEC_ORDERED) {
167 ordered = true;
168 niovecs = 0;
169 nbytes = 0;
170 }
171
172 /*
173 * We 64-bit align the length of each iovec so that the start
174 * of the next one is naturally aligned. We'll need to
175 * account for that slack space here. Then round nbytes up
176 * to 64-bit alignment so that the initial buffer alignment is
177 * easy to calculate and verify.
178 */
179 nbytes += niovecs * sizeof(uint64_t);
180 nbytes = round_up(nbytes, sizeof(uint64_t));
181
182 /*
183 * The data buffer needs to start 64-bit aligned, so round up
184 * that space to ensure we can align it appropriately and not
185 * overrun the buffer.
186 */
187 buf_size = nbytes + xlog_cil_iovec_space(niovecs);
188
189 /*
190 * if we have no shadow buffer, or it is too small, we need to
191 * reallocate it.
192 */
193 if (!lip->li_lv_shadow ||
194 buf_size > lip->li_lv_shadow->lv_size) {
195
196 /*
197 * We free and allocate here as a realloc would copy
198 * unecessary data. We don't use kmem_zalloc() for the
199 * same reason - we don't need to zero the data area in
200 * the buffer, only the log vector header and the iovec
201 * storage.
202 */
203 kmem_free(lip->li_lv_shadow);
204
205 lv = kmem_alloc_large(buf_size, KM_SLEEP | KM_NOFS);
206 memset(lv, 0, xlog_cil_iovec_space(niovecs));
207
208 lv->lv_item = lip;
209 lv->lv_size = buf_size;
210 if (ordered)
211 lv->lv_buf_len = XFS_LOG_VEC_ORDERED;
212 else
213 lv->lv_iovecp = (struct xfs_log_iovec *)&lv[1];
214 lip->li_lv_shadow = lv;
215 } else {
216 /* same or smaller, optimise common overwrite case */
217 lv = lip->li_lv_shadow;
218 if (ordered)
219 lv->lv_buf_len = XFS_LOG_VEC_ORDERED;
220 else
221 lv->lv_buf_len = 0;
222 lv->lv_bytes = 0;
223 lv->lv_next = NULL;
224 }
225
226 /* Ensure the lv is set up according to ->iop_size */
227 lv->lv_niovecs = niovecs;
228
229 /* The allocated data region lies beyond the iovec region */
230 lv->lv_buf = (char *)lv + xlog_cil_iovec_space(niovecs);
231 }
232
233}
234
235/*
236 * Prepare the log item for insertion into the CIL. Calculate the difference in
237 * log space and vectors it will consume, and if it is a new item pin it as
238 * well.
239 */
240STATIC void
241xfs_cil_prepare_item(
242 struct xlog *log,
243 struct xfs_log_vec *lv,
244 struct xfs_log_vec *old_lv,
245 int *diff_len,
246 int *diff_iovecs)
247{
248 /* Account for the new LV being passed in */
249 if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED) {
250 *diff_len += lv->lv_bytes;
251 *diff_iovecs += lv->lv_niovecs;
252 }
253
254 /*
255 * If there is no old LV, this is the first time we've seen the item in
256 * this CIL context and so we need to pin it. If we are replacing the
257 * old_lv, then remove the space it accounts for and make it the shadow
258 * buffer for later freeing. In both cases we are now switching to the
259 * shadow buffer, so update the the pointer to it appropriately.
260 */
261 if (!old_lv) {
262 lv->lv_item->li_ops->iop_pin(lv->lv_item);
263 lv->lv_item->li_lv_shadow = NULL;
264 } else if (old_lv != lv) {
265 ASSERT(lv->lv_buf_len != XFS_LOG_VEC_ORDERED);
266
267 *diff_len -= old_lv->lv_bytes;
268 *diff_iovecs -= old_lv->lv_niovecs;
269 lv->lv_item->li_lv_shadow = old_lv;
270 }
271
272 /* attach new log vector to log item */
273 lv->lv_item->li_lv = lv;
274
275 /*
276 * If this is the first time the item is being committed to the
277 * CIL, store the sequence number on the log item so we can
278 * tell in future commits whether this is the first checkpoint
279 * the item is being committed into.
280 */
281 if (!lv->lv_item->li_seq)
282 lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence;
283}
284
285/*
286 * Format log item into a flat buffers
287 *
288 * For delayed logging, we need to hold a formatted buffer containing all the
289 * changes on the log item. This enables us to relog the item in memory and
290 * write it out asynchronously without needing to relock the object that was
291 * modified at the time it gets written into the iclog.
292 *
293 * This function takes the prepared log vectors attached to each log item, and
294 * formats the changes into the log vector buffer. The buffer it uses is
295 * dependent on the current state of the vector in the CIL - the shadow lv is
296 * guaranteed to be large enough for the current modification, but we will only
297 * use that if we can't reuse the existing lv. If we can't reuse the existing
298 * lv, then simple swap it out for the shadow lv. We don't free it - that is
299 * done lazily either by th enext modification or the freeing of the log item.
300 *
301 * We don't set up region headers during this process; we simply copy the
302 * regions into the flat buffer. We can do this because we still have to do a
303 * formatting step to write the regions into the iclog buffer. Writing the
304 * ophdrs during the iclog write means that we can support splitting large
305 * regions across iclog boundares without needing a change in the format of the
306 * item/region encapsulation.
307 *
308 * Hence what we need to do now is change the rewrite the vector array to point
309 * to the copied region inside the buffer we just allocated. This allows us to
310 * format the regions into the iclog as though they are being formatted
311 * directly out of the objects themselves.
312 */
313static void
314xlog_cil_insert_format_items(
315 struct xlog *log,
316 struct xfs_trans *tp,
317 int *diff_len,
318 int *diff_iovecs)
319{
320 struct xfs_log_item_desc *lidp;
321
322
323 /* Bail out if we didn't find a log item. */
324 if (list_empty(&tp->t_items)) {
325 ASSERT(0);
326 return;
327 }
328
329 list_for_each_entry(lidp, &tp->t_items, lid_trans) {
330 struct xfs_log_item *lip = lidp->lid_item;
331 struct xfs_log_vec *lv;
332 struct xfs_log_vec *old_lv = NULL;
333 struct xfs_log_vec *shadow;
334 bool ordered = false;
335
336 /* Skip items which aren't dirty in this transaction. */
337 if (!(lidp->lid_flags & XFS_LID_DIRTY))
338 continue;
339
340 /*
341 * The formatting size information is already attached to
342 * the shadow lv on the log item.
343 */
344 shadow = lip->li_lv_shadow;
345 if (shadow->lv_buf_len == XFS_LOG_VEC_ORDERED)
346 ordered = true;
347
348 /* Skip items that do not have any vectors for writing */
349 if (!shadow->lv_niovecs && !ordered)
350 continue;
351
352 /* compare to existing item size */
353 old_lv = lip->li_lv;
354 if (lip->li_lv && shadow->lv_size <= lip->li_lv->lv_size) {
355 /* same or smaller, optimise common overwrite case */
356 lv = lip->li_lv;
357 lv->lv_next = NULL;
358
359 if (ordered)
360 goto insert;
361
362 /*
363 * set the item up as though it is a new insertion so
364 * that the space reservation accounting is correct.
365 */
366 *diff_iovecs -= lv->lv_niovecs;
367 *diff_len -= lv->lv_bytes;
368
369 /* Ensure the lv is set up according to ->iop_size */
370 lv->lv_niovecs = shadow->lv_niovecs;
371
372 /* reset the lv buffer information for new formatting */
373 lv->lv_buf_len = 0;
374 lv->lv_bytes = 0;
375 lv->lv_buf = (char *)lv +
376 xlog_cil_iovec_space(lv->lv_niovecs);
377 } else {
378 /* switch to shadow buffer! */
379 lv = shadow;
380 lv->lv_item = lip;
381 if (ordered) {
382 /* track as an ordered logvec */
383 ASSERT(lip->li_lv == NULL);
384 goto insert;
385 }
386 }
387
388 ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t)));
389 lip->li_ops->iop_format(lip, lv);
390insert:
391 xfs_cil_prepare_item(log, lv, old_lv, diff_len, diff_iovecs);
392 }
393}
394
395/*
396 * Insert the log items into the CIL and calculate the difference in space
397 * consumed by the item. Add the space to the checkpoint ticket and calculate
398 * if the change requires additional log metadata. If it does, take that space
399 * as well. Remove the amount of space we added to the checkpoint ticket from
400 * the current transaction ticket so that the accounting works out correctly.
401 */
402static void
403xlog_cil_insert_items(
404 struct xlog *log,
405 struct xfs_trans *tp)
406{
407 struct xfs_cil *cil = log->l_cilp;
408 struct xfs_cil_ctx *ctx = cil->xc_ctx;
409 struct xfs_log_item_desc *lidp;
410 int len = 0;
411 int diff_iovecs = 0;
412 int iclog_space;
413 int iovhdr_res = 0, split_res = 0, ctx_res = 0;
414
415 ASSERT(tp);
416
417 /*
418 * We can do this safely because the context can't checkpoint until we
419 * are done so it doesn't matter exactly how we update the CIL.
420 */
421 xlog_cil_insert_format_items(log, tp, &len, &diff_iovecs);
422
423 spin_lock(&cil->xc_cil_lock);
424
425 /* account for space used by new iovec headers */
426 iovhdr_res = diff_iovecs * sizeof(xlog_op_header_t);
427 len += iovhdr_res;
428 ctx->nvecs += diff_iovecs;
429
430 /* attach the transaction to the CIL if it has any busy extents */
431 if (!list_empty(&tp->t_busy))
432 list_splice_init(&tp->t_busy, &ctx->busy_extents);
433
434 /*
435 * Now transfer enough transaction reservation to the context ticket
436 * for the checkpoint. The context ticket is special - the unit
437 * reservation has to grow as well as the current reservation as we
438 * steal from tickets so we can correctly determine the space used
439 * during the transaction commit.
440 */
441 if (ctx->ticket->t_curr_res == 0) {
442 ctx_res = ctx->ticket->t_unit_res;
443 ctx->ticket->t_curr_res = ctx_res;
444 tp->t_ticket->t_curr_res -= ctx_res;
445 }
446
447 /* do we need space for more log record headers? */
448 iclog_space = log->l_iclog_size - log->l_iclog_hsize;
449 if (len > 0 && (ctx->space_used / iclog_space !=
450 (ctx->space_used + len) / iclog_space)) {
451 split_res = (len + iclog_space - 1) / iclog_space;
452 /* need to take into account split region headers, too */
453 split_res *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
454 ctx->ticket->t_unit_res += split_res;
455 ctx->ticket->t_curr_res += split_res;
456 tp->t_ticket->t_curr_res -= split_res;
457 ASSERT(tp->t_ticket->t_curr_res >= len);
458 }
459 tp->t_ticket->t_curr_res -= len;
460 ctx->space_used += len;
461
462 /*
463 * If we've overrun the reservation, dump the tx details before we move
464 * the log items. Shutdown is imminent...
465 */
466 if (WARN_ON(tp->t_ticket->t_curr_res < 0)) {
467 xfs_warn(log->l_mp, "Transaction log reservation overrun:");
468 xfs_warn(log->l_mp,
469 " log items: %d bytes (iov hdrs: %d bytes)",
470 len, iovhdr_res);
471 xfs_warn(log->l_mp, " split region headers: %d bytes",
472 split_res);
473 xfs_warn(log->l_mp, " ctx ticket: %d bytes", ctx_res);
474 xlog_print_trans(tp);
475 }
476
477 /*
478 * Now (re-)position everything modified at the tail of the CIL.
479 * We do this here so we only need to take the CIL lock once during
480 * the transaction commit.
481 */
482 list_for_each_entry(lidp, &tp->t_items, lid_trans) {
483 struct xfs_log_item *lip = lidp->lid_item;
484
485 /* Skip items which aren't dirty in this transaction. */
486 if (!(lidp->lid_flags & XFS_LID_DIRTY))
487 continue;
488
489 /*
490 * Only move the item if it isn't already at the tail. This is
491 * to prevent a transient list_empty() state when reinserting
492 * an item that is already the only item in the CIL.
493 */
494 if (!list_is_last(&lip->li_cil, &cil->xc_cil))
495 list_move_tail(&lip->li_cil, &cil->xc_cil);
496 }
497
498 spin_unlock(&cil->xc_cil_lock);
499
500 if (tp->t_ticket->t_curr_res < 0)
501 xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
502}
503
504static void
505xlog_cil_free_logvec(
506 struct xfs_log_vec *log_vector)
507{
508 struct xfs_log_vec *lv;
509
510 for (lv = log_vector; lv; ) {
511 struct xfs_log_vec *next = lv->lv_next;
512 kmem_free(lv);
513 lv = next;
514 }
515}
516
517static void
518xlog_discard_endio_work(
519 struct work_struct *work)
520{
521 struct xfs_cil_ctx *ctx =
522 container_of(work, struct xfs_cil_ctx, discard_endio_work);
523 struct xfs_mount *mp = ctx->cil->xc_log->l_mp;
524
525 xfs_extent_busy_clear(mp, &ctx->busy_extents, false);
526 kmem_free(ctx);
527}
528
529/*
530 * Queue up the actual completion to a thread to avoid IRQ-safe locking for
531 * pagb_lock. Note that we need a unbounded workqueue, otherwise we might
532 * get the execution delayed up to 30 seconds for weird reasons.
533 */
534static void
535xlog_discard_endio(
536 struct bio *bio)
537{
538 struct xfs_cil_ctx *ctx = bio->bi_private;
539
540 INIT_WORK(&ctx->discard_endio_work, xlog_discard_endio_work);
541 queue_work(xfs_discard_wq, &ctx->discard_endio_work);
542 bio_put(bio);
543}
544
545static void
546xlog_discard_busy_extents(
547 struct xfs_mount *mp,
548 struct xfs_cil_ctx *ctx)
549{
550 struct list_head *list = &ctx->busy_extents;
551 struct xfs_extent_busy *busyp;
552 struct bio *bio = NULL;
553 struct blk_plug plug;
554 int error = 0;
555
556 ASSERT(mp->m_flags & XFS_MOUNT_DISCARD);
557
558 blk_start_plug(&plug);
559 list_for_each_entry(busyp, list, list) {
560 trace_xfs_discard_extent(mp, busyp->agno, busyp->bno,
561 busyp->length);
562
563 error = __blkdev_issue_discard(mp->m_ddev_targp->bt_bdev,
564 XFS_AGB_TO_DADDR(mp, busyp->agno, busyp->bno),
565 XFS_FSB_TO_BB(mp, busyp->length),
566 GFP_NOFS, 0, &bio);
567 if (error && error != -EOPNOTSUPP) {
568 xfs_info(mp,
569 "discard failed for extent [0x%llx,%u], error %d",
570 (unsigned long long)busyp->bno,
571 busyp->length,
572 error);
573 break;
574 }
575 }
576
577 if (bio) {
578 bio->bi_private = ctx;
579 bio->bi_end_io = xlog_discard_endio;
580 submit_bio(bio);
581 } else {
582 xlog_discard_endio_work(&ctx->discard_endio_work);
583 }
584 blk_finish_plug(&plug);
585}
586
587/*
588 * Mark all items committed and clear busy extents. We free the log vector
589 * chains in a separate pass so that we unpin the log items as quickly as
590 * possible.
591 */
592static void
593xlog_cil_committed(
594 void *args,
595 int abort)
596{
597 struct xfs_cil_ctx *ctx = args;
598 struct xfs_mount *mp = ctx->cil->xc_log->l_mp;
599
600 xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain,
601 ctx->start_lsn, abort);
602
603 xfs_extent_busy_sort(&ctx->busy_extents);
604 xfs_extent_busy_clear(mp, &ctx->busy_extents,
605 (mp->m_flags & XFS_MOUNT_DISCARD) && !abort);
606
607 /*
608 * If we are aborting the commit, wake up anyone waiting on the
609 * committing list. If we don't, then a shutdown we can leave processes
610 * waiting in xlog_cil_force_lsn() waiting on a sequence commit that
611 * will never happen because we aborted it.
612 */
613 spin_lock(&ctx->cil->xc_push_lock);
614 if (abort)
615 wake_up_all(&ctx->cil->xc_commit_wait);
616 list_del(&ctx->committing);
617 spin_unlock(&ctx->cil->xc_push_lock);
618
619 xlog_cil_free_logvec(ctx->lv_chain);
620
621 if (!list_empty(&ctx->busy_extents))
622 xlog_discard_busy_extents(mp, ctx);
623 else
624 kmem_free(ctx);
625}
626
627/*
628 * Push the Committed Item List to the log. If @push_seq flag is zero, then it
629 * is a background flush and so we can chose to ignore it. Otherwise, if the
630 * current sequence is the same as @push_seq we need to do a flush. If
631 * @push_seq is less than the current sequence, then it has already been
632 * flushed and we don't need to do anything - the caller will wait for it to
633 * complete if necessary.
634 *
635 * @push_seq is a value rather than a flag because that allows us to do an
636 * unlocked check of the sequence number for a match. Hence we can allows log
637 * forces to run racily and not issue pushes for the same sequence twice. If we
638 * get a race between multiple pushes for the same sequence they will block on
639 * the first one and then abort, hence avoiding needless pushes.
640 */
641STATIC int
642xlog_cil_push(
643 struct xlog *log)
644{
645 struct xfs_cil *cil = log->l_cilp;
646 struct xfs_log_vec *lv;
647 struct xfs_cil_ctx *ctx;
648 struct xfs_cil_ctx *new_ctx;
649 struct xlog_in_core *commit_iclog;
650 struct xlog_ticket *tic;
651 int num_iovecs;
652 int error = 0;
653 struct xfs_trans_header thdr;
654 struct xfs_log_iovec lhdr;
655 struct xfs_log_vec lvhdr = { NULL };
656 xfs_lsn_t commit_lsn;
657 xfs_lsn_t push_seq;
658
659 if (!cil)
660 return 0;
661
662 new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS);
663 new_ctx->ticket = xlog_cil_ticket_alloc(log);
664
665 down_write(&cil->xc_ctx_lock);
666 ctx = cil->xc_ctx;
667
668 spin_lock(&cil->xc_push_lock);
669 push_seq = cil->xc_push_seq;
670 ASSERT(push_seq <= ctx->sequence);
671
672 /*
673 * Check if we've anything to push. If there is nothing, then we don't
674 * move on to a new sequence number and so we have to be able to push
675 * this sequence again later.
676 */
677 if (list_empty(&cil->xc_cil)) {
678 cil->xc_push_seq = 0;
679 spin_unlock(&cil->xc_push_lock);
680 goto out_skip;
681 }
682
683
684 /* check for a previously pushed seqeunce */
685 if (push_seq < cil->xc_ctx->sequence) {
686 spin_unlock(&cil->xc_push_lock);
687 goto out_skip;
688 }
689
690 /*
691 * We are now going to push this context, so add it to the committing
692 * list before we do anything else. This ensures that anyone waiting on
693 * this push can easily detect the difference between a "push in
694 * progress" and "CIL is empty, nothing to do".
695 *
696 * IOWs, a wait loop can now check for:
697 * the current sequence not being found on the committing list;
698 * an empty CIL; and
699 * an unchanged sequence number
700 * to detect a push that had nothing to do and therefore does not need
701 * waiting on. If the CIL is not empty, we get put on the committing
702 * list before emptying the CIL and bumping the sequence number. Hence
703 * an empty CIL and an unchanged sequence number means we jumped out
704 * above after doing nothing.
705 *
706 * Hence the waiter will either find the commit sequence on the
707 * committing list or the sequence number will be unchanged and the CIL
708 * still dirty. In that latter case, the push has not yet started, and
709 * so the waiter will have to continue trying to check the CIL
710 * committing list until it is found. In extreme cases of delay, the
711 * sequence may fully commit between the attempts the wait makes to wait
712 * on the commit sequence.
713 */
714 list_add(&ctx->committing, &cil->xc_committing);
715 spin_unlock(&cil->xc_push_lock);
716
717 /*
718 * pull all the log vectors off the items in the CIL, and
719 * remove the items from the CIL. We don't need the CIL lock
720 * here because it's only needed on the transaction commit
721 * side which is currently locked out by the flush lock.
722 */
723 lv = NULL;
724 num_iovecs = 0;
725 while (!list_empty(&cil->xc_cil)) {
726 struct xfs_log_item *item;
727
728 item = list_first_entry(&cil->xc_cil,
729 struct xfs_log_item, li_cil);
730 list_del_init(&item->li_cil);
731 if (!ctx->lv_chain)
732 ctx->lv_chain = item->li_lv;
733 else
734 lv->lv_next = item->li_lv;
735 lv = item->li_lv;
736 item->li_lv = NULL;
737 num_iovecs += lv->lv_niovecs;
738 }
739
740 /*
741 * initialise the new context and attach it to the CIL. Then attach
742 * the current context to the CIL committing lsit so it can be found
743 * during log forces to extract the commit lsn of the sequence that
744 * needs to be forced.
745 */
746 INIT_LIST_HEAD(&new_ctx->committing);
747 INIT_LIST_HEAD(&new_ctx->busy_extents);
748 new_ctx->sequence = ctx->sequence + 1;
749 new_ctx->cil = cil;
750 cil->xc_ctx = new_ctx;
751
752 /*
753 * The switch is now done, so we can drop the context lock and move out
754 * of a shared context. We can't just go straight to the commit record,
755 * though - we need to synchronise with previous and future commits so
756 * that the commit records are correctly ordered in the log to ensure
757 * that we process items during log IO completion in the correct order.
758 *
759 * For example, if we get an EFI in one checkpoint and the EFD in the
760 * next (e.g. due to log forces), we do not want the checkpoint with
761 * the EFD to be committed before the checkpoint with the EFI. Hence
762 * we must strictly order the commit records of the checkpoints so
763 * that: a) the checkpoint callbacks are attached to the iclogs in the
764 * correct order; and b) the checkpoints are replayed in correct order
765 * in log recovery.
766 *
767 * Hence we need to add this context to the committing context list so
768 * that higher sequences will wait for us to write out a commit record
769 * before they do.
770 *
771 * xfs_log_force_lsn requires us to mirror the new sequence into the cil
772 * structure atomically with the addition of this sequence to the
773 * committing list. This also ensures that we can do unlocked checks
774 * against the current sequence in log forces without risking
775 * deferencing a freed context pointer.
776 */
777 spin_lock(&cil->xc_push_lock);
778 cil->xc_current_sequence = new_ctx->sequence;
779 spin_unlock(&cil->xc_push_lock);
780 up_write(&cil->xc_ctx_lock);
781
782 /*
783 * Build a checkpoint transaction header and write it to the log to
784 * begin the transaction. We need to account for the space used by the
785 * transaction header here as it is not accounted for in xlog_write().
786 *
787 * The LSN we need to pass to the log items on transaction commit is
788 * the LSN reported by the first log vector write. If we use the commit
789 * record lsn then we can move the tail beyond the grant write head.
790 */
791 tic = ctx->ticket;
792 thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
793 thdr.th_type = XFS_TRANS_CHECKPOINT;
794 thdr.th_tid = tic->t_tid;
795 thdr.th_num_items = num_iovecs;
796 lhdr.i_addr = &thdr;
797 lhdr.i_len = sizeof(xfs_trans_header_t);
798 lhdr.i_type = XLOG_REG_TYPE_TRANSHDR;
799 tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t);
800
801 lvhdr.lv_niovecs = 1;
802 lvhdr.lv_iovecp = &lhdr;
803 lvhdr.lv_next = ctx->lv_chain;
804
805 error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0);
806 if (error)
807 goto out_abort_free_ticket;
808
809 /*
810 * now that we've written the checkpoint into the log, strictly
811 * order the commit records so replay will get them in the right order.
812 */
813restart:
814 spin_lock(&cil->xc_push_lock);
815 list_for_each_entry(new_ctx, &cil->xc_committing, committing) {
816 /*
817 * Avoid getting stuck in this loop because we were woken by the
818 * shutdown, but then went back to sleep once already in the
819 * shutdown state.
820 */
821 if (XLOG_FORCED_SHUTDOWN(log)) {
822 spin_unlock(&cil->xc_push_lock);
823 goto out_abort_free_ticket;
824 }
825
826 /*
827 * Higher sequences will wait for this one so skip them.
828 * Don't wait for our own sequence, either.
829 */
830 if (new_ctx->sequence >= ctx->sequence)
831 continue;
832 if (!new_ctx->commit_lsn) {
833 /*
834 * It is still being pushed! Wait for the push to
835 * complete, then start again from the beginning.
836 */
837 xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
838 goto restart;
839 }
840 }
841 spin_unlock(&cil->xc_push_lock);
842
843 /* xfs_log_done always frees the ticket on error. */
844 commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, false);
845 if (commit_lsn == -1)
846 goto out_abort;
847
848 /* attach all the transactions w/ busy extents to iclog */
849 ctx->log_cb.cb_func = xlog_cil_committed;
850 ctx->log_cb.cb_arg = ctx;
851 error = xfs_log_notify(commit_iclog, &ctx->log_cb);
852 if (error)
853 goto out_abort;
854
855 /*
856 * now the checkpoint commit is complete and we've attached the
857 * callbacks to the iclog we can assign the commit LSN to the context
858 * and wake up anyone who is waiting for the commit to complete.
859 */
860 spin_lock(&cil->xc_push_lock);
861 ctx->commit_lsn = commit_lsn;
862 wake_up_all(&cil->xc_commit_wait);
863 spin_unlock(&cil->xc_push_lock);
864
865 /* release the hounds! */
866 return xfs_log_release_iclog(log->l_mp, commit_iclog);
867
868out_skip:
869 up_write(&cil->xc_ctx_lock);
870 xfs_log_ticket_put(new_ctx->ticket);
871 kmem_free(new_ctx);
872 return 0;
873
874out_abort_free_ticket:
875 xfs_log_ticket_put(tic);
876out_abort:
877 xlog_cil_committed(ctx, XFS_LI_ABORTED);
878 return -EIO;
879}
880
881static void
882xlog_cil_push_work(
883 struct work_struct *work)
884{
885 struct xfs_cil *cil = container_of(work, struct xfs_cil,
886 xc_push_work);
887 xlog_cil_push(cil->xc_log);
888}
889
890/*
891 * We need to push CIL every so often so we don't cache more than we can fit in
892 * the log. The limit really is that a checkpoint can't be more than half the
893 * log (the current checkpoint is not allowed to overwrite the previous
894 * checkpoint), but commit latency and memory usage limit this to a smaller
895 * size.
896 */
897static void
898xlog_cil_push_background(
899 struct xlog *log)
900{
901 struct xfs_cil *cil = log->l_cilp;
902
903 /*
904 * The cil won't be empty because we are called while holding the
905 * context lock so whatever we added to the CIL will still be there
906 */
907 ASSERT(!list_empty(&cil->xc_cil));
908
909 /*
910 * don't do a background push if we haven't used up all the
911 * space available yet.
912 */
913 if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
914 return;
915
916 spin_lock(&cil->xc_push_lock);
917 if (cil->xc_push_seq < cil->xc_current_sequence) {
918 cil->xc_push_seq = cil->xc_current_sequence;
919 queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
920 }
921 spin_unlock(&cil->xc_push_lock);
922
923}
924
925/*
926 * xlog_cil_push_now() is used to trigger an immediate CIL push to the sequence
927 * number that is passed. When it returns, the work will be queued for
928 * @push_seq, but it won't be completed. The caller is expected to do any
929 * waiting for push_seq to complete if it is required.
930 */
931static void
932xlog_cil_push_now(
933 struct xlog *log,
934 xfs_lsn_t push_seq)
935{
936 struct xfs_cil *cil = log->l_cilp;
937
938 if (!cil)
939 return;
940
941 ASSERT(push_seq && push_seq <= cil->xc_current_sequence);
942
943 /* start on any pending background push to minimise wait time on it */
944 flush_work(&cil->xc_push_work);
945
946 /*
947 * If the CIL is empty or we've already pushed the sequence then
948 * there's no work we need to do.
949 */
950 spin_lock(&cil->xc_push_lock);
951 if (list_empty(&cil->xc_cil) || push_seq <= cil->xc_push_seq) {
952 spin_unlock(&cil->xc_push_lock);
953 return;
954 }
955
956 cil->xc_push_seq = push_seq;
957 queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
958 spin_unlock(&cil->xc_push_lock);
959}
960
961bool
962xlog_cil_empty(
963 struct xlog *log)
964{
965 struct xfs_cil *cil = log->l_cilp;
966 bool empty = false;
967
968 spin_lock(&cil->xc_push_lock);
969 if (list_empty(&cil->xc_cil))
970 empty = true;
971 spin_unlock(&cil->xc_push_lock);
972 return empty;
973}
974
975/*
976 * Commit a transaction with the given vector to the Committed Item List.
977 *
978 * To do this, we need to format the item, pin it in memory if required and
979 * account for the space used by the transaction. Once we have done that we
980 * need to release the unused reservation for the transaction, attach the
981 * transaction to the checkpoint context so we carry the busy extents through
982 * to checkpoint completion, and then unlock all the items in the transaction.
983 *
984 * Called with the context lock already held in read mode to lock out
985 * background commit, returns without it held once background commits are
986 * allowed again.
987 */
988void
989xfs_log_commit_cil(
990 struct xfs_mount *mp,
991 struct xfs_trans *tp,
992 xfs_lsn_t *commit_lsn,
993 bool regrant)
994{
995 struct xlog *log = mp->m_log;
996 struct xfs_cil *cil = log->l_cilp;
997 xfs_lsn_t xc_commit_lsn;
998
999 /*
1000 * Do all necessary memory allocation before we lock the CIL.
1001 * This ensures the allocation does not deadlock with a CIL
1002 * push in memory reclaim (e.g. from kswapd).
1003 */
1004 xlog_cil_alloc_shadow_bufs(log, tp);
1005
1006 /* lock out background commit */
1007 down_read(&cil->xc_ctx_lock);
1008
1009 xlog_cil_insert_items(log, tp);
1010
1011 xc_commit_lsn = cil->xc_ctx->sequence;
1012 if (commit_lsn)
1013 *commit_lsn = xc_commit_lsn;
1014
1015 xfs_log_done(mp, tp->t_ticket, NULL, regrant);
1016 xfs_trans_unreserve_and_mod_sb(tp);
1017
1018 /*
1019 * Once all the items of the transaction have been copied to the CIL,
1020 * the items can be unlocked and freed.
1021 *
1022 * This needs to be done before we drop the CIL context lock because we
1023 * have to update state in the log items and unlock them before they go
1024 * to disk. If we don't, then the CIL checkpoint can race with us and
1025 * we can run checkpoint completion before we've updated and unlocked
1026 * the log items. This affects (at least) processing of stale buffers,
1027 * inodes and EFIs.
1028 */
1029 xfs_trans_free_items(tp, xc_commit_lsn, false);
1030
1031 xlog_cil_push_background(log);
1032
1033 up_read(&cil->xc_ctx_lock);
1034}
1035
1036/*
1037 * Conditionally push the CIL based on the sequence passed in.
1038 *
1039 * We only need to push if we haven't already pushed the sequence
1040 * number given. Hence the only time we will trigger a push here is
1041 * if the push sequence is the same as the current context.
1042 *
1043 * We return the current commit lsn to allow the callers to determine if a
1044 * iclog flush is necessary following this call.
1045 */
1046xfs_lsn_t
1047xlog_cil_force_lsn(
1048 struct xlog *log,
1049 xfs_lsn_t sequence)
1050{
1051 struct xfs_cil *cil = log->l_cilp;
1052 struct xfs_cil_ctx *ctx;
1053 xfs_lsn_t commit_lsn = NULLCOMMITLSN;
1054
1055 ASSERT(sequence <= cil->xc_current_sequence);
1056
1057 /*
1058 * check to see if we need to force out the current context.
1059 * xlog_cil_push() handles racing pushes for the same sequence,
1060 * so no need to deal with it here.
1061 */
1062restart:
1063 xlog_cil_push_now(log, sequence);
1064
1065 /*
1066 * See if we can find a previous sequence still committing.
1067 * We need to wait for all previous sequence commits to complete
1068 * before allowing the force of push_seq to go ahead. Hence block
1069 * on commits for those as well.
1070 */
1071 spin_lock(&cil->xc_push_lock);
1072 list_for_each_entry(ctx, &cil->xc_committing, committing) {
1073 /*
1074 * Avoid getting stuck in this loop because we were woken by the
1075 * shutdown, but then went back to sleep once already in the
1076 * shutdown state.
1077 */
1078 if (XLOG_FORCED_SHUTDOWN(log))
1079 goto out_shutdown;
1080 if (ctx->sequence > sequence)
1081 continue;
1082 if (!ctx->commit_lsn) {
1083 /*
1084 * It is still being pushed! Wait for the push to
1085 * complete, then start again from the beginning.
1086 */
1087 xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
1088 goto restart;
1089 }
1090 if (ctx->sequence != sequence)
1091 continue;
1092 /* found it! */
1093 commit_lsn = ctx->commit_lsn;
1094 }
1095
1096 /*
1097 * The call to xlog_cil_push_now() executes the push in the background.
1098 * Hence by the time we have got here it our sequence may not have been
1099 * pushed yet. This is true if the current sequence still matches the
1100 * push sequence after the above wait loop and the CIL still contains
1101 * dirty objects. This is guaranteed by the push code first adding the
1102 * context to the committing list before emptying the CIL.
1103 *
1104 * Hence if we don't find the context in the committing list and the
1105 * current sequence number is unchanged then the CIL contents are
1106 * significant. If the CIL is empty, if means there was nothing to push
1107 * and that means there is nothing to wait for. If the CIL is not empty,
1108 * it means we haven't yet started the push, because if it had started
1109 * we would have found the context on the committing list.
1110 */
1111 if (sequence == cil->xc_current_sequence &&
1112 !list_empty(&cil->xc_cil)) {
1113 spin_unlock(&cil->xc_push_lock);
1114 goto restart;
1115 }
1116
1117 spin_unlock(&cil->xc_push_lock);
1118 return commit_lsn;
1119
1120 /*
1121 * We detected a shutdown in progress. We need to trigger the log force
1122 * to pass through it's iclog state machine error handling, even though
1123 * we are already in a shutdown state. Hence we can't return
1124 * NULLCOMMITLSN here as that has special meaning to log forces (i.e.
1125 * LSN is already stable), so we return a zero LSN instead.
1126 */
1127out_shutdown:
1128 spin_unlock(&cil->xc_push_lock);
1129 return 0;
1130}
1131
1132/*
1133 * Check if the current log item was first committed in this sequence.
1134 * We can't rely on just the log item being in the CIL, we have to check
1135 * the recorded commit sequence number.
1136 *
1137 * Note: for this to be used in a non-racy manner, it has to be called with
1138 * CIL flushing locked out. As a result, it should only be used during the
1139 * transaction commit process when deciding what to format into the item.
1140 */
1141bool
1142xfs_log_item_in_current_chkpt(
1143 struct xfs_log_item *lip)
1144{
1145 struct xfs_cil_ctx *ctx;
1146
1147 if (list_empty(&lip->li_cil))
1148 return false;
1149
1150 ctx = lip->li_mountp->m_log->l_cilp->xc_ctx;
1151
1152 /*
1153 * li_seq is written on the first commit of a log item to record the
1154 * first checkpoint it is written to. Hence if it is different to the
1155 * current sequence, we're in a new checkpoint.
1156 */
1157 if (XFS_LSN_CMP(lip->li_seq, ctx->sequence) != 0)
1158 return false;
1159 return true;
1160}
1161
1162/*
1163 * Perform initial CIL structure initialisation.
1164 */
1165int
1166xlog_cil_init(
1167 struct xlog *log)
1168{
1169 struct xfs_cil *cil;
1170 struct xfs_cil_ctx *ctx;
1171
1172 cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL);
1173 if (!cil)
1174 return -ENOMEM;
1175
1176 ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL);
1177 if (!ctx) {
1178 kmem_free(cil);
1179 return -ENOMEM;
1180 }
1181
1182 INIT_WORK(&cil->xc_push_work, xlog_cil_push_work);
1183 INIT_LIST_HEAD(&cil->xc_cil);
1184 INIT_LIST_HEAD(&cil->xc_committing);
1185 spin_lock_init(&cil->xc_cil_lock);
1186 spin_lock_init(&cil->xc_push_lock);
1187 init_rwsem(&cil->xc_ctx_lock);
1188 init_waitqueue_head(&cil->xc_commit_wait);
1189
1190 INIT_LIST_HEAD(&ctx->committing);
1191 INIT_LIST_HEAD(&ctx->busy_extents);
1192 ctx->sequence = 1;
1193 ctx->cil = cil;
1194 cil->xc_ctx = ctx;
1195 cil->xc_current_sequence = ctx->sequence;
1196
1197 cil->xc_log = log;
1198 log->l_cilp = cil;
1199 return 0;
1200}
1201
1202void
1203xlog_cil_destroy(
1204 struct xlog *log)
1205{
1206 if (log->l_cilp->xc_ctx) {
1207 if (log->l_cilp->xc_ctx->ticket)
1208 xfs_log_ticket_put(log->l_cilp->xc_ctx->ticket);
1209 kmem_free(log->l_cilp->xc_ctx);
1210 }
1211
1212 ASSERT(list_empty(&log->l_cilp->xc_cil));
1213 kmem_free(log->l_cilp);
1214}
1215