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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * linux/fs/jbd2/checkpoint.c
4 *
5 * Written by Stephen C. Tweedie <[email protected]>, 1999
6 *
7 * Copyright 1999 Red Hat Software --- All Rights Reserved
8 *
9 * Checkpoint routines for the generic filesystem journaling code.
10 * Part of the ext2fs journaling system.
11 *
12 * Checkpointing is the process of ensuring that a section of the log is
13 * committed fully to disk, so that that portion of the log can be
14 * reused.
15 */
16
17#include <linux/time.h>
18#include <linux/fs.h>
19#include <linux/jbd2.h>
20#include <linux/errno.h>
21#include <linux/slab.h>
22#include <linux/blkdev.h>
23#include <trace/events/jbd2.h>
24
25/*
26 * Unlink a buffer from a transaction checkpoint list.
27 *
28 * Called with j_list_lock held.
29 */
30static inline void __buffer_unlink(struct journal_head *jh)
31{
32 transaction_t *transaction = jh->b_cp_transaction;
33
34 jh->b_cpnext->b_cpprev = jh->b_cpprev;
35 jh->b_cpprev->b_cpnext = jh->b_cpnext;
36 if (transaction->t_checkpoint_list == jh) {
37 transaction->t_checkpoint_list = jh->b_cpnext;
38 if (transaction->t_checkpoint_list == jh)
39 transaction->t_checkpoint_list = NULL;
40 }
41}
42
43/*
44 * __jbd2_log_wait_for_space: wait until there is space in the journal.
45 *
46 * Called under j-state_lock *only*. It will be unlocked if we have to wait
47 * for a checkpoint to free up some space in the log.
48 */
49void __jbd2_log_wait_for_space(journal_t *journal)
50__acquires(&journal->j_state_lock)
51__releases(&journal->j_state_lock)
52{
53 int nblocks, space_left;
54 /* assert_spin_locked(&journal->j_state_lock); */
55
56 nblocks = journal->j_max_transaction_buffers;
57 while (jbd2_log_space_left(journal) < nblocks) {
58 write_unlock(&journal->j_state_lock);
59 mutex_lock_io(&journal->j_checkpoint_mutex);
60
61 /*
62 * Test again, another process may have checkpointed while we
63 * were waiting for the checkpoint lock. If there are no
64 * transactions ready to be checkpointed, try to recover
65 * journal space by calling cleanup_journal_tail(), and if
66 * that doesn't work, by waiting for the currently committing
67 * transaction to complete. If there is absolutely no way
68 * to make progress, this is either a BUG or corrupted
69 * filesystem, so abort the journal and leave a stack
70 * trace for forensic evidence.
71 */
72 write_lock(&journal->j_state_lock);
73 if (journal->j_flags & JBD2_ABORT) {
74 mutex_unlock(&journal->j_checkpoint_mutex);
75 return;
76 }
77 spin_lock(&journal->j_list_lock);
78 space_left = jbd2_log_space_left(journal);
79 if (space_left < nblocks) {
80 int chkpt = journal->j_checkpoint_transactions != NULL;
81 tid_t tid = 0;
82 bool has_transaction = false;
83
84 if (journal->j_committing_transaction) {
85 tid = journal->j_committing_transaction->t_tid;
86 has_transaction = true;
87 }
88 spin_unlock(&journal->j_list_lock);
89 write_unlock(&journal->j_state_lock);
90 if (chkpt) {
91 jbd2_log_do_checkpoint(journal);
92 } else if (jbd2_cleanup_journal_tail(journal) <= 0) {
93 /*
94 * We were able to recover space or the
95 * journal was aborted due to an error.
96 */
97 ;
98 } else if (has_transaction) {
99 /*
100 * jbd2_journal_commit_transaction() may want
101 * to take the checkpoint_mutex if JBD2_FLUSHED
102 * is set. So we need to temporarily drop it.
103 */
104 mutex_unlock(&journal->j_checkpoint_mutex);
105 jbd2_log_wait_commit(journal, tid);
106 write_lock(&journal->j_state_lock);
107 continue;
108 } else {
109 printk(KERN_ERR "%s: needed %d blocks and "
110 "only had %d space available\n",
111 __func__, nblocks, space_left);
112 printk(KERN_ERR "%s: no way to get more "
113 "journal space in %s\n", __func__,
114 journal->j_devname);
115 WARN_ON(1);
116 jbd2_journal_abort(journal, -ENOSPC);
117 }
118 write_lock(&journal->j_state_lock);
119 } else {
120 spin_unlock(&journal->j_list_lock);
121 }
122 mutex_unlock(&journal->j_checkpoint_mutex);
123 }
124}
125
126static void
127__flush_batch(journal_t *journal, int *batch_count)
128{
129 int i;
130 struct blk_plug plug;
131
132 blk_start_plug(&plug);
133 for (i = 0; i < *batch_count; i++)
134 write_dirty_buffer(journal->j_chkpt_bhs[i], JBD2_JOURNAL_REQ_FLAGS);
135 blk_finish_plug(&plug);
136
137 for (i = 0; i < *batch_count; i++) {
138 struct buffer_head *bh = journal->j_chkpt_bhs[i];
139 BUFFER_TRACE(bh, "brelse");
140 __brelse(bh);
141 journal->j_chkpt_bhs[i] = NULL;
142 }
143 *batch_count = 0;
144}
145
146/*
147 * Perform an actual checkpoint. We take the first transaction on the
148 * list of transactions to be checkpointed and send all its buffers
149 * to disk. We submit larger chunks of data at once.
150 *
151 * The journal should be locked before calling this function.
152 * Called with j_checkpoint_mutex held.
153 */
154int jbd2_log_do_checkpoint(journal_t *journal)
155{
156 struct journal_head *jh;
157 struct buffer_head *bh;
158 transaction_t *transaction;
159 tid_t this_tid;
160 int result, batch_count = 0;
161
162 jbd2_debug(1, "Start checkpoint\n");
163
164 /*
165 * First thing: if there are any transactions in the log which
166 * don't need checkpointing, just eliminate them from the
167 * journal straight away.
168 */
169 result = jbd2_cleanup_journal_tail(journal);
170 trace_jbd2_checkpoint(journal, result);
171 jbd2_debug(1, "cleanup_journal_tail returned %d\n", result);
172 if (result <= 0)
173 return result;
174
175 /*
176 * OK, we need to start writing disk blocks. Take one transaction
177 * and write it.
178 */
179 spin_lock(&journal->j_list_lock);
180 if (!journal->j_checkpoint_transactions)
181 goto out;
182 transaction = journal->j_checkpoint_transactions;
183 if (transaction->t_chp_stats.cs_chp_time == 0)
184 transaction->t_chp_stats.cs_chp_time = jiffies;
185 this_tid = transaction->t_tid;
186restart:
187 /*
188 * If someone cleaned up this transaction while we slept, we're
189 * done (maybe it's a new transaction, but it fell at the same
190 * address).
191 */
192 if (journal->j_checkpoint_transactions != transaction ||
193 transaction->t_tid != this_tid)
194 goto out;
195
196 /* checkpoint all of the transaction's buffers */
197 while (transaction->t_checkpoint_list) {
198 jh = transaction->t_checkpoint_list;
199 bh = jh2bh(jh);
200
201 if (jh->b_transaction != NULL) {
202 transaction_t *t = jh->b_transaction;
203 tid_t tid = t->t_tid;
204
205 transaction->t_chp_stats.cs_forced_to_close++;
206 spin_unlock(&journal->j_list_lock);
207 if (unlikely(journal->j_flags & JBD2_UNMOUNT))
208 /*
209 * The journal thread is dead; so
210 * starting and waiting for a commit
211 * to finish will cause us to wait for
212 * a _very_ long time.
213 */
214 printk(KERN_ERR
215 "JBD2: %s: Waiting for Godot: block %llu\n",
216 journal->j_devname, (unsigned long long) bh->b_blocknr);
217
218 if (batch_count)
219 __flush_batch(journal, &batch_count);
220 jbd2_log_start_commit(journal, tid);
221 /*
222 * jbd2_journal_commit_transaction() may want
223 * to take the checkpoint_mutex if JBD2_FLUSHED
224 * is set, jbd2_update_log_tail() called by
225 * jbd2_journal_commit_transaction() may also take
226 * checkpoint_mutex. So we need to temporarily
227 * drop it.
228 */
229 mutex_unlock(&journal->j_checkpoint_mutex);
230 jbd2_log_wait_commit(journal, tid);
231 mutex_lock_io(&journal->j_checkpoint_mutex);
232 spin_lock(&journal->j_list_lock);
233 goto restart;
234 }
235 if (!trylock_buffer(bh)) {
236 /*
237 * The buffer is locked, it may be writing back, or
238 * flushing out in the last couple of cycles, or
239 * re-adding into a new transaction, need to check
240 * it again until it's unlocked.
241 */
242 get_bh(bh);
243 spin_unlock(&journal->j_list_lock);
244 wait_on_buffer(bh);
245 /* the journal_head may have gone by now */
246 BUFFER_TRACE(bh, "brelse");
247 __brelse(bh);
248 goto retry;
249 } else if (!buffer_dirty(bh)) {
250 unlock_buffer(bh);
251 BUFFER_TRACE(bh, "remove from checkpoint");
252 /*
253 * If the transaction was released or the checkpoint
254 * list was empty, we're done.
255 */
256 if (__jbd2_journal_remove_checkpoint(jh) ||
257 !transaction->t_checkpoint_list)
258 goto out;
259 } else {
260 unlock_buffer(bh);
261 /*
262 * We are about to write the buffer, it could be
263 * raced by some other transaction shrink or buffer
264 * re-log logic once we release the j_list_lock,
265 * leave it on the checkpoint list and check status
266 * again to make sure it's clean.
267 */
268 BUFFER_TRACE(bh, "queue");
269 get_bh(bh);
270 if (WARN_ON_ONCE(buffer_jwrite(bh))) {
271 put_bh(bh); /* drop the ref we just took */
272 spin_unlock(&journal->j_list_lock);
273 /* Clean up any previously batched buffers */
274 if (batch_count)
275 __flush_batch(journal, &batch_count);
276 jbd2_journal_abort(journal, -EFSCORRUPTED);
277 return -EFSCORRUPTED;
278 }
279 journal->j_chkpt_bhs[batch_count++] = bh;
280 transaction->t_chp_stats.cs_written++;
281 transaction->t_checkpoint_list = jh->b_cpnext;
282 }
283
284 if ((batch_count == JBD2_NR_BATCH) ||
285 need_resched() || spin_needbreak(&journal->j_list_lock) ||
286 jh2bh(transaction->t_checkpoint_list) == journal->j_chkpt_bhs[0])
287 goto unlock_and_flush;
288 }
289
290 if (batch_count) {
291 unlock_and_flush:
292 spin_unlock(&journal->j_list_lock);
293 retry:
294 if (batch_count)
295 __flush_batch(journal, &batch_count);
296 cond_resched();
297 spin_lock(&journal->j_list_lock);
298 goto restart;
299 }
300
301out:
302 spin_unlock(&journal->j_list_lock);
303 result = jbd2_cleanup_journal_tail(journal);
304
305 return (result < 0) ? result : 0;
306}
307
308/*
309 * Check the list of checkpoint transactions for the journal to see if
310 * we have already got rid of any since the last update of the log tail
311 * in the journal superblock. If so, we can instantly roll the
312 * superblock forward to remove those transactions from the log.
313 *
314 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
315 *
316 * Called with the journal lock held.
317 *
318 * This is the only part of the journaling code which really needs to be
319 * aware of transaction aborts. Checkpointing involves writing to the
320 * main filesystem area rather than to the journal, so it can proceed
321 * even in abort state, but we must not update the super block if
322 * checkpointing may have failed. Otherwise, we would lose some metadata
323 * buffers which should be written-back to the filesystem.
324 */
325
326int jbd2_cleanup_journal_tail(journal_t *journal)
327{
328 tid_t first_tid;
329 unsigned long blocknr;
330
331 if (is_journal_aborted(journal))
332 return -EIO;
333
334 if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
335 return 1;
336 if (WARN_ON_ONCE(blocknr == 0)) {
337 jbd2_journal_abort(journal, -EFSCORRUPTED);
338 return -EFSCORRUPTED;
339 }
340
341 /*
342 * We need to make sure that any blocks that were recently written out
343 * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
344 * we drop the transactions from the journal. It's unlikely this will
345 * be necessary, especially with an appropriately sized journal, but we
346 * need this to guarantee correctness. Fortunately
347 * jbd2_cleanup_journal_tail() doesn't get called all that often.
348 */
349 if (journal->j_flags & JBD2_BARRIER)
350 blkdev_issue_flush(journal->j_fs_dev);
351
352 return __jbd2_update_log_tail(journal, first_tid, blocknr);
353}
354
355
356/* Checkpoint list management */
357
358/*
359 * journal_shrink_one_cp_list
360 *
361 * Find written-back checkpoint buffers in the given list and try to release
362 * them. If 'nr_to_scan' is set, scan at most that many buffers. If the whole
363 * transaction is released, set the 'released' parameter. Return the number of
364 * released checkpointed buffers.
365 *
366 * Called with j_list_lock held.
367 */
368static unsigned long journal_shrink_one_cp_list(struct journal_head *jh,
369 enum jbd2_shrink_type type,
370 unsigned long *nr_to_scan,
371 bool *released)
372{
373 struct journal_head *last_jh;
374 struct journal_head *next_jh = jh;
375 unsigned long nr_freed = 0;
376 int ret;
377
378 *released = false;
379 if (!jh || (nr_to_scan && !*nr_to_scan))
380 return 0;
381
382 last_jh = jh->b_cpprev;
383 do {
384 jh = next_jh;
385 next_jh = jh->b_cpnext;
386 if (nr_to_scan)
387 (*nr_to_scan)--;
388
389 if (type == JBD2_SHRINK_DESTROY) {
390 ret = __jbd2_journal_remove_checkpoint(jh);
391 } else {
392 ret = jbd2_journal_try_remove_checkpoint(jh);
393 if (ret < 0) {
394 if (type == JBD2_SHRINK_BUSY_SKIP)
395 goto next;
396 break;
397 }
398 }
399
400 nr_freed++;
401 if (ret) {
402 *released = true;
403 break;
404 }
405
406next:
407 if (need_resched())
408 break;
409 } while (jh != last_jh && (!nr_to_scan || *nr_to_scan));
410
411 return nr_freed;
412}
413
414/*
415 * jbd2_journal_shrink_checkpoint_list
416 *
417 * Find 'nr_to_scan' written-back checkpoint buffers in the journal
418 * and try to release them. Return the number of released checkpointed
419 * buffers.
420 *
421 * Called with j_list_lock held.
422 */
423unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
424 unsigned long *nr_to_scan)
425{
426 transaction_t *transaction, *last_transaction, *next_transaction;
427 bool __maybe_unused released;
428 tid_t first_tid = 0, last_tid = 0, next_tid = 0;
429 tid_t tid = 0;
430 unsigned long nr_freed = 0;
431 bool first_set = false;
432
433again:
434 spin_lock(&journal->j_list_lock);
435 if (!journal->j_checkpoint_transactions) {
436 spin_unlock(&journal->j_list_lock);
437 goto out;
438 }
439
440 /*
441 * Get next shrink transaction, resume previous scan or start
442 * over again. If some others do checkpoint and drop transaction
443 * from the checkpoint list, we ignore saved j_shrink_transaction
444 * and start over unconditionally.
445 */
446 if (journal->j_shrink_transaction)
447 transaction = journal->j_shrink_transaction;
448 else
449 transaction = journal->j_checkpoint_transactions;
450
451 if (!first_set) {
452 first_tid = transaction->t_tid;
453 first_set = true;
454 }
455 last_transaction = journal->j_checkpoint_transactions->t_cpprev;
456 next_transaction = transaction;
457 last_tid = last_transaction->t_tid;
458 do {
459 transaction = next_transaction;
460 next_transaction = transaction->t_cpnext;
461 tid = transaction->t_tid;
462
463 nr_freed += journal_shrink_one_cp_list(transaction->t_checkpoint_list,
464 JBD2_SHRINK_BUSY_SKIP,
465 nr_to_scan, &released);
466 if (*nr_to_scan == 0)
467 break;
468 if (need_resched() || spin_needbreak(&journal->j_list_lock))
469 break;
470 } while (transaction != last_transaction);
471
472 if (transaction != last_transaction) {
473 journal->j_shrink_transaction = next_transaction;
474 next_tid = next_transaction->t_tid;
475 } else {
476 journal->j_shrink_transaction = NULL;
477 next_tid = 0;
478 }
479
480 spin_unlock(&journal->j_list_lock);
481 cond_resched();
482
483 if (*nr_to_scan && journal->j_shrink_transaction)
484 goto again;
485out:
486 trace_jbd2_shrink_checkpoint_list(journal, first_tid, tid, last_tid,
487 nr_freed, next_tid);
488
489 return nr_freed;
490}
491
492/*
493 * journal_clean_checkpoint_list
494 *
495 * Find all the written-back checkpoint buffers in the journal and release them.
496 * If 'type' is JBD2_SHRINK_DESTROY, release all buffers unconditionally. If
497 * 'type' is JBD2_SHRINK_BUSY_STOP, will stop release buffers if encounters a
498 * busy buffer. To avoid wasting CPU cycles scanning the buffer list in some
499 * cases, don't pass JBD2_SHRINK_BUSY_SKIP 'type' for this function.
500 *
501 * Called with j_list_lock held.
502 */
503void __jbd2_journal_clean_checkpoint_list(journal_t *journal,
504 enum jbd2_shrink_type type)
505{
506 transaction_t *transaction, *last_transaction, *next_transaction;
507 bool released;
508
509 WARN_ON_ONCE(type == JBD2_SHRINK_BUSY_SKIP);
510
511 transaction = journal->j_checkpoint_transactions;
512 if (!transaction)
513 return;
514
515 last_transaction = transaction->t_cpprev;
516 next_transaction = transaction;
517 do {
518 transaction = next_transaction;
519 next_transaction = transaction->t_cpnext;
520 journal_shrink_one_cp_list(transaction->t_checkpoint_list,
521 type, NULL, &released);
522 /*
523 * This function only frees up some memory if possible so we
524 * dont have an obligation to finish processing. Bail out if
525 * preemption requested:
526 */
527 if (need_resched())
528 return;
529 /*
530 * Stop scanning if we couldn't free the transaction. This
531 * avoids pointless scanning of transactions which still
532 * weren't checkpointed.
533 */
534 if (!released)
535 return;
536 } while (transaction != last_transaction);
537}
538
539/*
540 * Remove buffers from all checkpoint lists as journal is aborted and we just
541 * need to free memory
542 */
543void jbd2_journal_destroy_checkpoint(journal_t *journal)
544{
545 /*
546 * We loop because __jbd2_journal_clean_checkpoint_list() may abort
547 * early due to a need of rescheduling.
548 */
549 while (1) {
550 spin_lock(&journal->j_list_lock);
551 if (!journal->j_checkpoint_transactions) {
552 spin_unlock(&journal->j_list_lock);
553 break;
554 }
555 __jbd2_journal_clean_checkpoint_list(journal, JBD2_SHRINK_DESTROY);
556 spin_unlock(&journal->j_list_lock);
557 cond_resched();
558 }
559}
560
561/*
562 * journal_remove_checkpoint: called after a buffer has been committed
563 * to disk (either by being write-back flushed to disk, or being
564 * committed to the log).
565 *
566 * We cannot safely clean a transaction out of the log until all of the
567 * buffer updates committed in that transaction have safely been stored
568 * elsewhere on disk. To achieve this, all of the buffers in a
569 * transaction need to be maintained on the transaction's checkpoint
570 * lists until they have been rewritten, at which point this function is
571 * called to remove the buffer from the existing transaction's
572 * checkpoint lists.
573 *
574 * The function returns 1 if it frees the transaction, 0 otherwise.
575 * The function can free jh and bh.
576 *
577 * This function is called with j_list_lock held.
578 */
579int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
580{
581 struct transaction_chp_stats_s *stats;
582 transaction_t *transaction;
583 journal_t *journal;
584
585 JBUFFER_TRACE(jh, "entry");
586
587 transaction = jh->b_cp_transaction;
588 if (!transaction) {
589 JBUFFER_TRACE(jh, "not on transaction");
590 return 0;
591 }
592 journal = transaction->t_journal;
593
594 JBUFFER_TRACE(jh, "removing from transaction");
595
596 __buffer_unlink(jh);
597 jh->b_cp_transaction = NULL;
598 percpu_counter_dec(&journal->j_checkpoint_jh_count);
599 jbd2_journal_put_journal_head(jh);
600
601 /* Is this transaction empty? */
602 if (transaction->t_checkpoint_list)
603 return 0;
604
605 /*
606 * There is one special case to worry about: if we have just pulled the
607 * buffer off a running or committing transaction's checkpoing list,
608 * then even if the checkpoint list is empty, the transaction obviously
609 * cannot be dropped!
610 *
611 * The locking here around t_state is a bit sleazy.
612 * See the comment at the end of jbd2_journal_commit_transaction().
613 */
614 if (transaction->t_state != T_FINISHED)
615 return 0;
616
617 /*
618 * OK, that was the last buffer for the transaction, we can now
619 * safely remove this transaction from the log.
620 */
621 stats = &transaction->t_chp_stats;
622 if (stats->cs_chp_time)
623 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
624 jiffies);
625 trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
626 transaction->t_tid, stats);
627
628 __jbd2_journal_drop_transaction(journal, transaction);
629 jbd2_journal_free_transaction(transaction);
630 return 1;
631}
632
633/*
634 * Check the checkpoint buffer and try to remove it from the checkpoint
635 * list if it's clean. Returns -EBUSY if it is not clean, returns 1 if
636 * it frees the transaction, 0 otherwise.
637 *
638 * This function is called with j_list_lock held.
639 */
640int jbd2_journal_try_remove_checkpoint(struct journal_head *jh)
641{
642 struct buffer_head *bh = jh2bh(jh);
643
644 if (jh->b_transaction)
645 return -EBUSY;
646 if (!trylock_buffer(bh))
647 return -EBUSY;
648 if (buffer_dirty(bh)) {
649 unlock_buffer(bh);
650 return -EBUSY;
651 }
652 unlock_buffer(bh);
653
654 /*
655 * Buffer is clean and the IO has finished (we held the buffer
656 * lock) so the checkpoint is done. We can safely remove the
657 * buffer from this transaction.
658 */
659 JBUFFER_TRACE(jh, "remove from checkpoint list");
660 return __jbd2_journal_remove_checkpoint(jh);
661}
662
663/*
664 * journal_insert_checkpoint: put a committed buffer onto a checkpoint
665 * list so that we know when it is safe to clean the transaction out of
666 * the log.
667 *
668 * Called with the journal locked.
669 * Called with j_list_lock held.
670 */
671void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
672 transaction_t *transaction)
673{
674 JBUFFER_TRACE(jh, "entry");
675 J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
676 J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
677
678 /* Get reference for checkpointing transaction */
679 jbd2_journal_grab_journal_head(jh2bh(jh));
680 jh->b_cp_transaction = transaction;
681
682 if (!transaction->t_checkpoint_list) {
683 jh->b_cpnext = jh->b_cpprev = jh;
684 } else {
685 jh->b_cpnext = transaction->t_checkpoint_list;
686 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
687 jh->b_cpprev->b_cpnext = jh;
688 jh->b_cpnext->b_cpprev = jh;
689 }
690 transaction->t_checkpoint_list = jh;
691 percpu_counter_inc(&transaction->t_journal->j_checkpoint_jh_count);
692}
693
694/*
695 * We've finished with this transaction structure: adios...
696 *
697 * The transaction must have no links except for the checkpoint by this
698 * point.
699 *
700 * Called with the journal locked.
701 * Called with j_list_lock held.
702 */
703
704void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
705{
706 assert_spin_locked(&journal->j_list_lock);
707
708 journal->j_shrink_transaction = NULL;
709 if (transaction->t_cpnext) {
710 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
711 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
712 if (journal->j_checkpoint_transactions == transaction)
713 journal->j_checkpoint_transactions =
714 transaction->t_cpnext;
715 if (journal->j_checkpoint_transactions == transaction)
716 journal->j_checkpoint_transactions = NULL;
717 }
718
719 J_ASSERT(transaction->t_state == T_FINISHED);
720 J_ASSERT(transaction->t_buffers == NULL);
721 J_ASSERT(transaction->t_forget == NULL);
722 J_ASSERT(transaction->t_shadow_list == NULL);
723 J_ASSERT(transaction->t_checkpoint_list == NULL);
724 J_ASSERT(atomic_read(&transaction->t_updates) == 0);
725 J_ASSERT(journal->j_committing_transaction != transaction);
726 J_ASSERT(journal->j_running_transaction != transaction);
727
728 trace_jbd2_drop_transaction(journal, transaction);
729
730 jbd2_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
731}