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