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1/*
2 * linux/fs/jbd2/checkpoint.c
3 *
4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
5 *
6 * Copyright 1999 Red Hat Software --- All Rights Reserved
7 *
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
11 *
12 * Checkpoint routines for the generic filesystem journaling code.
13 * Part of the ext2fs journaling system.
14 *
15 * Checkpointing is the process of ensuring that a section of the log is
16 * committed fully to disk, so that that portion of the log can be
17 * reused.
18 */
19
20#include <linux/time.h>
21#include <linux/fs.h>
22#include <linux/jbd2.h>
23#include <linux/errno.h>
24#include <linux/slab.h>
25#include <linux/blkdev.h>
26#include <trace/events/jbd2.h>
27
28/*
29 * Unlink a buffer from a transaction checkpoint list.
30 *
31 * Called with j_list_lock held.
32 */
33static inline void __buffer_unlink_first(struct journal_head *jh)
34{
35 transaction_t *transaction = jh->b_cp_transaction;
36
37 jh->b_cpnext->b_cpprev = jh->b_cpprev;
38 jh->b_cpprev->b_cpnext = jh->b_cpnext;
39 if (transaction->t_checkpoint_list == jh) {
40 transaction->t_checkpoint_list = jh->b_cpnext;
41 if (transaction->t_checkpoint_list == jh)
42 transaction->t_checkpoint_list = NULL;
43 }
44}
45
46/*
47 * Unlink a buffer from a transaction checkpoint(io) list.
48 *
49 * Called with j_list_lock held.
50 */
51static inline void __buffer_unlink(struct journal_head *jh)
52{
53 transaction_t *transaction = jh->b_cp_transaction;
54
55 __buffer_unlink_first(jh);
56 if (transaction->t_checkpoint_io_list == jh) {
57 transaction->t_checkpoint_io_list = jh->b_cpnext;
58 if (transaction->t_checkpoint_io_list == jh)
59 transaction->t_checkpoint_io_list = NULL;
60 }
61}
62
63/*
64 * Move a buffer from the checkpoint list to the checkpoint io list
65 *
66 * Called with j_list_lock held
67 */
68static inline void __buffer_relink_io(struct journal_head *jh)
69{
70 transaction_t *transaction = jh->b_cp_transaction;
71
72 __buffer_unlink_first(jh);
73
74 if (!transaction->t_checkpoint_io_list) {
75 jh->b_cpnext = jh->b_cpprev = jh;
76 } else {
77 jh->b_cpnext = transaction->t_checkpoint_io_list;
78 jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
79 jh->b_cpprev->b_cpnext = jh;
80 jh->b_cpnext->b_cpprev = jh;
81 }
82 transaction->t_checkpoint_io_list = jh;
83}
84
85/*
86 * Try to release a checkpointed buffer from its transaction.
87 * Returns 1 if we released it and 2 if we also released the
88 * whole transaction.
89 *
90 * Requires j_list_lock
91 */
92static int __try_to_free_cp_buf(struct journal_head *jh)
93{
94 int ret = 0;
95 struct buffer_head *bh = jh2bh(jh);
96
97 if (jh->b_transaction == NULL && !buffer_locked(bh) &&
98 !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
99 /*
100 * Get our reference so that bh cannot be freed before
101 * we unlock it
102 */
103 get_bh(bh);
104 JBUFFER_TRACE(jh, "remove from checkpoint list");
105 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
106 BUFFER_TRACE(bh, "release");
107 __brelse(bh);
108 }
109 return ret;
110}
111
112/*
113 * __jbd2_log_wait_for_space: wait until there is space in the journal.
114 *
115 * Called under j-state_lock *only*. It will be unlocked if we have to wait
116 * for a checkpoint to free up some space in the log.
117 */
118void __jbd2_log_wait_for_space(journal_t *journal)
119{
120 int nblocks, space_left;
121 /* assert_spin_locked(&journal->j_state_lock); */
122
123 nblocks = jbd_space_needed(journal);
124 while (__jbd2_log_space_left(journal) < nblocks) {
125 if (journal->j_flags & JBD2_ABORT)
126 return;
127 write_unlock(&journal->j_state_lock);
128 mutex_lock(&journal->j_checkpoint_mutex);
129
130 /*
131 * Test again, another process may have checkpointed while we
132 * were waiting for the checkpoint lock. If there are no
133 * transactions ready to be checkpointed, try to recover
134 * journal space by calling cleanup_journal_tail(), and if
135 * that doesn't work, by waiting for the currently committing
136 * transaction to complete. If there is absolutely no way
137 * to make progress, this is either a BUG or corrupted
138 * filesystem, so abort the journal and leave a stack
139 * trace for forensic evidence.
140 */
141 write_lock(&journal->j_state_lock);
142 spin_lock(&journal->j_list_lock);
143 nblocks = jbd_space_needed(journal);
144 space_left = __jbd2_log_space_left(journal);
145 if (space_left < nblocks) {
146 int chkpt = journal->j_checkpoint_transactions != NULL;
147 tid_t tid = 0;
148
149 if (journal->j_committing_transaction)
150 tid = journal->j_committing_transaction->t_tid;
151 spin_unlock(&journal->j_list_lock);
152 write_unlock(&journal->j_state_lock);
153 if (chkpt) {
154 jbd2_log_do_checkpoint(journal);
155 } else if (jbd2_cleanup_journal_tail(journal) == 0) {
156 /* We were able to recover space; yay! */
157 ;
158 } else if (tid) {
159 jbd2_log_wait_commit(journal, tid);
160 } else {
161 printk(KERN_ERR "%s: needed %d blocks and "
162 "only had %d space available\n",
163 __func__, nblocks, space_left);
164 printk(KERN_ERR "%s: no way to get more "
165 "journal space in %s\n", __func__,
166 journal->j_devname);
167 WARN_ON(1);
168 jbd2_journal_abort(journal, 0);
169 }
170 write_lock(&journal->j_state_lock);
171 } else {
172 spin_unlock(&journal->j_list_lock);
173 }
174 mutex_unlock(&journal->j_checkpoint_mutex);
175 }
176}
177
178/*
179 * Clean up transaction's list of buffers submitted for io.
180 * We wait for any pending IO to complete and remove any clean
181 * buffers. Note that we take the buffers in the opposite ordering
182 * from the one in which they were submitted for IO.
183 *
184 * Return 0 on success, and return <0 if some buffers have failed
185 * to be written out.
186 *
187 * Called with j_list_lock held.
188 */
189static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
190{
191 struct journal_head *jh;
192 struct buffer_head *bh;
193 tid_t this_tid;
194 int released = 0;
195 int ret = 0;
196
197 this_tid = transaction->t_tid;
198restart:
199 /* Did somebody clean up the transaction in the meanwhile? */
200 if (journal->j_checkpoint_transactions != transaction ||
201 transaction->t_tid != this_tid)
202 return ret;
203 while (!released && transaction->t_checkpoint_io_list) {
204 jh = transaction->t_checkpoint_io_list;
205 bh = jh2bh(jh);
206 get_bh(bh);
207 if (buffer_locked(bh)) {
208 spin_unlock(&journal->j_list_lock);
209 wait_on_buffer(bh);
210 /* the journal_head may have gone by now */
211 BUFFER_TRACE(bh, "brelse");
212 __brelse(bh);
213 spin_lock(&journal->j_list_lock);
214 goto restart;
215 }
216 if (unlikely(buffer_write_io_error(bh)))
217 ret = -EIO;
218
219 /*
220 * Now in whatever state the buffer currently is, we know that
221 * it has been written out and so we can drop it from the list
222 */
223 released = __jbd2_journal_remove_checkpoint(jh);
224 __brelse(bh);
225 }
226
227 return ret;
228}
229
230static void
231__flush_batch(journal_t *journal, int *batch_count)
232{
233 int i;
234 struct blk_plug plug;
235
236 blk_start_plug(&plug);
237 for (i = 0; i < *batch_count; i++)
238 write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE_SYNC);
239 blk_finish_plug(&plug);
240
241 for (i = 0; i < *batch_count; i++) {
242 struct buffer_head *bh = journal->j_chkpt_bhs[i];
243 BUFFER_TRACE(bh, "brelse");
244 __brelse(bh);
245 }
246 *batch_count = 0;
247}
248
249/*
250 * Try to flush one buffer from the checkpoint list to disk.
251 *
252 * Return 1 if something happened which requires us to abort the current
253 * scan of the checkpoint list. Return <0 if the buffer has failed to
254 * be written out.
255 *
256 * Called with j_list_lock held and drops it if 1 is returned
257 */
258static int __process_buffer(journal_t *journal, struct journal_head *jh,
259 int *batch_count, transaction_t *transaction)
260{
261 struct buffer_head *bh = jh2bh(jh);
262 int ret = 0;
263
264 if (buffer_locked(bh)) {
265 get_bh(bh);
266 spin_unlock(&journal->j_list_lock);
267 wait_on_buffer(bh);
268 /* the journal_head may have gone by now */
269 BUFFER_TRACE(bh, "brelse");
270 __brelse(bh);
271 ret = 1;
272 } else if (jh->b_transaction != NULL) {
273 transaction_t *t = jh->b_transaction;
274 tid_t tid = t->t_tid;
275
276 transaction->t_chp_stats.cs_forced_to_close++;
277 spin_unlock(&journal->j_list_lock);
278 if (unlikely(journal->j_flags & JBD2_UNMOUNT))
279 /*
280 * The journal thread is dead; so starting and
281 * waiting for a commit to finish will cause
282 * us to wait for a _very_ long time.
283 */
284 printk(KERN_ERR "JBD2: %s: "
285 "Waiting for Godot: block %llu\n",
286 journal->j_devname,
287 (unsigned long long) bh->b_blocknr);
288 jbd2_log_start_commit(journal, tid);
289 jbd2_log_wait_commit(journal, tid);
290 ret = 1;
291 } else if (!buffer_dirty(bh)) {
292 ret = 1;
293 if (unlikely(buffer_write_io_error(bh)))
294 ret = -EIO;
295 get_bh(bh);
296 BUFFER_TRACE(bh, "remove from checkpoint");
297 __jbd2_journal_remove_checkpoint(jh);
298 spin_unlock(&journal->j_list_lock);
299 __brelse(bh);
300 } else {
301 /*
302 * Important: we are about to write the buffer, and
303 * possibly block, while still holding the journal lock.
304 * We cannot afford to let the transaction logic start
305 * messing around with this buffer before we write it to
306 * disk, as that would break recoverability.
307 */
308 BUFFER_TRACE(bh, "queue");
309 get_bh(bh);
310 J_ASSERT_BH(bh, !buffer_jwrite(bh));
311 journal->j_chkpt_bhs[*batch_count] = bh;
312 __buffer_relink_io(jh);
313 transaction->t_chp_stats.cs_written++;
314 (*batch_count)++;
315 if (*batch_count == JBD2_NR_BATCH) {
316 spin_unlock(&journal->j_list_lock);
317 __flush_batch(journal, batch_count);
318 ret = 1;
319 }
320 }
321 return ret;
322}
323
324/*
325 * Perform an actual checkpoint. We take the first transaction on the
326 * list of transactions to be checkpointed and send all its buffers
327 * to disk. We submit larger chunks of data at once.
328 *
329 * The journal should be locked before calling this function.
330 * Called with j_checkpoint_mutex held.
331 */
332int jbd2_log_do_checkpoint(journal_t *journal)
333{
334 transaction_t *transaction;
335 tid_t this_tid;
336 int result;
337
338 jbd_debug(1, "Start checkpoint\n");
339
340 /*
341 * First thing: if there are any transactions in the log which
342 * don't need checkpointing, just eliminate them from the
343 * journal straight away.
344 */
345 result = jbd2_cleanup_journal_tail(journal);
346 trace_jbd2_checkpoint(journal, result);
347 jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
348 if (result <= 0)
349 return result;
350
351 /*
352 * OK, we need to start writing disk blocks. Take one transaction
353 * and write it.
354 */
355 result = 0;
356 spin_lock(&journal->j_list_lock);
357 if (!journal->j_checkpoint_transactions)
358 goto out;
359 transaction = journal->j_checkpoint_transactions;
360 if (transaction->t_chp_stats.cs_chp_time == 0)
361 transaction->t_chp_stats.cs_chp_time = jiffies;
362 this_tid = transaction->t_tid;
363restart:
364 /*
365 * If someone cleaned up this transaction while we slept, we're
366 * done (maybe it's a new transaction, but it fell at the same
367 * address).
368 */
369 if (journal->j_checkpoint_transactions == transaction &&
370 transaction->t_tid == this_tid) {
371 int batch_count = 0;
372 struct journal_head *jh;
373 int retry = 0, err;
374
375 while (!retry && transaction->t_checkpoint_list) {
376 jh = transaction->t_checkpoint_list;
377 retry = __process_buffer(journal, jh, &batch_count,
378 transaction);
379 if (retry < 0 && !result)
380 result = retry;
381 if (!retry && (need_resched() ||
382 spin_needbreak(&journal->j_list_lock))) {
383 spin_unlock(&journal->j_list_lock);
384 retry = 1;
385 break;
386 }
387 }
388
389 if (batch_count) {
390 if (!retry) {
391 spin_unlock(&journal->j_list_lock);
392 retry = 1;
393 }
394 __flush_batch(journal, &batch_count);
395 }
396
397 if (retry) {
398 spin_lock(&journal->j_list_lock);
399 goto restart;
400 }
401 /*
402 * Now we have cleaned up the first transaction's checkpoint
403 * list. Let's clean up the second one
404 */
405 err = __wait_cp_io(journal, transaction);
406 if (!result)
407 result = err;
408 }
409out:
410 spin_unlock(&journal->j_list_lock);
411 if (result < 0)
412 jbd2_journal_abort(journal, result);
413 else
414 result = jbd2_cleanup_journal_tail(journal);
415
416 return (result < 0) ? result : 0;
417}
418
419/*
420 * Check the list of checkpoint transactions for the journal to see if
421 * we have already got rid of any since the last update of the log tail
422 * in the journal superblock. If so, we can instantly roll the
423 * superblock forward to remove those transactions from the log.
424 *
425 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
426 *
427 * Called with the journal lock held.
428 *
429 * This is the only part of the journaling code which really needs to be
430 * aware of transaction aborts. Checkpointing involves writing to the
431 * main filesystem area rather than to the journal, so it can proceed
432 * even in abort state, but we must not update the super block if
433 * checkpointing may have failed. Otherwise, we would lose some metadata
434 * buffers which should be written-back to the filesystem.
435 */
436
437int jbd2_cleanup_journal_tail(journal_t *journal)
438{
439 tid_t first_tid;
440 unsigned long blocknr;
441
442 if (is_journal_aborted(journal))
443 return 1;
444
445 if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
446 return 1;
447 J_ASSERT(blocknr != 0);
448
449 /*
450 * We need to make sure that any blocks that were recently written out
451 * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
452 * we drop the transactions from the journal. It's unlikely this will
453 * be necessary, especially with an appropriately sized journal, but we
454 * need this to guarantee correctness. Fortunately
455 * jbd2_cleanup_journal_tail() doesn't get called all that often.
456 */
457 if (journal->j_flags & JBD2_BARRIER)
458 blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
459
460 __jbd2_update_log_tail(journal, first_tid, blocknr);
461 return 0;
462}
463
464
465/* Checkpoint list management */
466
467/*
468 * journal_clean_one_cp_list
469 *
470 * Find all the written-back checkpoint buffers in the given list and
471 * release them.
472 *
473 * Called with the journal locked.
474 * Called with j_list_lock held.
475 * Returns number of buffers reaped (for debug)
476 */
477
478static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
479{
480 struct journal_head *last_jh;
481 struct journal_head *next_jh = jh;
482 int ret, freed = 0;
483
484 *released = 0;
485 if (!jh)
486 return 0;
487
488 last_jh = jh->b_cpprev;
489 do {
490 jh = next_jh;
491 next_jh = jh->b_cpnext;
492 ret = __try_to_free_cp_buf(jh);
493 if (ret) {
494 freed++;
495 if (ret == 2) {
496 *released = 1;
497 return freed;
498 }
499 }
500 /*
501 * This function only frees up some memory
502 * if possible so we dont have an obligation
503 * to finish processing. Bail out if preemption
504 * requested:
505 */
506 if (need_resched())
507 return freed;
508 } while (jh != last_jh);
509
510 return freed;
511}
512
513/*
514 * journal_clean_checkpoint_list
515 *
516 * Find all the written-back checkpoint buffers in the journal and release them.
517 *
518 * Called with the journal locked.
519 * Called with j_list_lock held.
520 * Returns number of buffers reaped (for debug)
521 */
522
523int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
524{
525 transaction_t *transaction, *last_transaction, *next_transaction;
526 int ret = 0;
527 int released;
528
529 transaction = journal->j_checkpoint_transactions;
530 if (!transaction)
531 goto out;
532
533 last_transaction = transaction->t_cpprev;
534 next_transaction = transaction;
535 do {
536 transaction = next_transaction;
537 next_transaction = transaction->t_cpnext;
538 ret += journal_clean_one_cp_list(transaction->
539 t_checkpoint_list, &released);
540 /*
541 * This function only frees up some memory if possible so we
542 * dont have an obligation to finish processing. Bail out if
543 * preemption requested:
544 */
545 if (need_resched())
546 goto out;
547 if (released)
548 continue;
549 /*
550 * It is essential that we are as careful as in the case of
551 * t_checkpoint_list with removing the buffer from the list as
552 * we can possibly see not yet submitted buffers on io_list
553 */
554 ret += journal_clean_one_cp_list(transaction->
555 t_checkpoint_io_list, &released);
556 if (need_resched())
557 goto out;
558 } while (transaction != last_transaction);
559out:
560 return ret;
561}
562
563/*
564 * journal_remove_checkpoint: called after a buffer has been committed
565 * to disk (either by being write-back flushed to disk, or being
566 * committed to the log).
567 *
568 * We cannot safely clean a transaction out of the log until all of the
569 * buffer updates committed in that transaction have safely been stored
570 * elsewhere on disk. To achieve this, all of the buffers in a
571 * transaction need to be maintained on the transaction's checkpoint
572 * lists until they have been rewritten, at which point this function is
573 * called to remove the buffer from the existing transaction's
574 * checkpoint lists.
575 *
576 * The function returns 1 if it frees the transaction, 0 otherwise.
577 * The function can free jh and bh.
578 *
579 * This function is called with j_list_lock held.
580 */
581int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
582{
583 struct transaction_chp_stats_s *stats;
584 transaction_t *transaction;
585 journal_t *journal;
586 int ret = 0;
587
588 JBUFFER_TRACE(jh, "entry");
589
590 if ((transaction = jh->b_cp_transaction) == NULL) {
591 JBUFFER_TRACE(jh, "not on transaction");
592 goto out;
593 }
594 journal = transaction->t_journal;
595
596 JBUFFER_TRACE(jh, "removing from transaction");
597 __buffer_unlink(jh);
598 jh->b_cp_transaction = NULL;
599 jbd2_journal_put_journal_head(jh);
600
601 if (transaction->t_checkpoint_list != NULL ||
602 transaction->t_checkpoint_io_list != NULL)
603 goto out;
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 goto out;
616
617 /* OK, that was the last buffer for the transaction: we can now
618 safely remove this transaction from the log */
619 stats = &transaction->t_chp_stats;
620 if (stats->cs_chp_time)
621 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
622 jiffies);
623 trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
624 transaction->t_tid, stats);
625
626 __jbd2_journal_drop_transaction(journal, transaction);
627 jbd2_journal_free_transaction(transaction);
628
629 /* Just in case anybody was waiting for more transactions to be
630 checkpointed... */
631 wake_up(&journal->j_wait_logspace);
632 ret = 1;
633out:
634 return ret;
635}
636
637/*
638 * journal_insert_checkpoint: put a committed buffer onto a checkpoint
639 * list so that we know when it is safe to clean the transaction out of
640 * the log.
641 *
642 * Called with the journal locked.
643 * Called with j_list_lock held.
644 */
645void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
646 transaction_t *transaction)
647{
648 JBUFFER_TRACE(jh, "entry");
649 J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
650 J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
651
652 /* Get reference for checkpointing transaction */
653 jbd2_journal_grab_journal_head(jh2bh(jh));
654 jh->b_cp_transaction = transaction;
655
656 if (!transaction->t_checkpoint_list) {
657 jh->b_cpnext = jh->b_cpprev = jh;
658 } else {
659 jh->b_cpnext = transaction->t_checkpoint_list;
660 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
661 jh->b_cpprev->b_cpnext = jh;
662 jh->b_cpnext->b_cpprev = jh;
663 }
664 transaction->t_checkpoint_list = jh;
665}
666
667/*
668 * We've finished with this transaction structure: adios...
669 *
670 * The transaction must have no links except for the checkpoint by this
671 * point.
672 *
673 * Called with the journal locked.
674 * Called with j_list_lock held.
675 */
676
677void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
678{
679 assert_spin_locked(&journal->j_list_lock);
680 if (transaction->t_cpnext) {
681 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
682 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
683 if (journal->j_checkpoint_transactions == transaction)
684 journal->j_checkpoint_transactions =
685 transaction->t_cpnext;
686 if (journal->j_checkpoint_transactions == transaction)
687 journal->j_checkpoint_transactions = NULL;
688 }
689
690 J_ASSERT(transaction->t_state == T_FINISHED);
691 J_ASSERT(transaction->t_buffers == NULL);
692 J_ASSERT(transaction->t_forget == NULL);
693 J_ASSERT(transaction->t_iobuf_list == NULL);
694 J_ASSERT(transaction->t_shadow_list == NULL);
695 J_ASSERT(transaction->t_log_list == NULL);
696 J_ASSERT(transaction->t_checkpoint_list == NULL);
697 J_ASSERT(transaction->t_checkpoint_io_list == NULL);
698 J_ASSERT(atomic_read(&transaction->t_updates) == 0);
699 J_ASSERT(journal->j_committing_transaction != transaction);
700 J_ASSERT(journal->j_running_transaction != transaction);
701
702 trace_jbd2_drop_transaction(journal, transaction);
703
704 jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
705}
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_first(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 * Unlink a buffer from a transaction checkpoint(io) list.
45 *
46 * Called with j_list_lock held.
47 */
48static inline void __buffer_unlink(struct journal_head *jh)
49{
50 transaction_t *transaction = jh->b_cp_transaction;
51
52 __buffer_unlink_first(jh);
53 if (transaction->t_checkpoint_io_list == jh) {
54 transaction->t_checkpoint_io_list = jh->b_cpnext;
55 if (transaction->t_checkpoint_io_list == jh)
56 transaction->t_checkpoint_io_list = NULL;
57 }
58}
59
60/*
61 * Move a buffer from the checkpoint list to the checkpoint io list
62 *
63 * Called with j_list_lock held
64 */
65static inline void __buffer_relink_io(struct journal_head *jh)
66{
67 transaction_t *transaction = jh->b_cp_transaction;
68
69 __buffer_unlink_first(jh);
70
71 if (!transaction->t_checkpoint_io_list) {
72 jh->b_cpnext = jh->b_cpprev = jh;
73 } else {
74 jh->b_cpnext = transaction->t_checkpoint_io_list;
75 jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
76 jh->b_cpprev->b_cpnext = jh;
77 jh->b_cpnext->b_cpprev = jh;
78 }
79 transaction->t_checkpoint_io_list = jh;
80}
81
82/*
83 * Check a checkpoint buffer could be release or not.
84 *
85 * Requires j_list_lock
86 */
87static inline bool __cp_buffer_busy(struct journal_head *jh)
88{
89 struct buffer_head *bh = jh2bh(jh);
90
91 return (jh->b_transaction || buffer_locked(bh) || buffer_dirty(bh));
92}
93
94/*
95 * __jbd2_log_wait_for_space: wait until there is space in the journal.
96 *
97 * Called under j-state_lock *only*. It will be unlocked if we have to wait
98 * for a checkpoint to free up some space in the log.
99 */
100void __jbd2_log_wait_for_space(journal_t *journal)
101__acquires(&journal->j_state_lock)
102__releases(&journal->j_state_lock)
103{
104 int nblocks, space_left;
105 /* assert_spin_locked(&journal->j_state_lock); */
106
107 nblocks = journal->j_max_transaction_buffers;
108 while (jbd2_log_space_left(journal) < nblocks) {
109 write_unlock(&journal->j_state_lock);
110 mutex_lock_io(&journal->j_checkpoint_mutex);
111
112 /*
113 * Test again, another process may have checkpointed while we
114 * were waiting for the checkpoint lock. If there are no
115 * transactions ready to be checkpointed, try to recover
116 * journal space by calling cleanup_journal_tail(), and if
117 * that doesn't work, by waiting for the currently committing
118 * transaction to complete. If there is absolutely no way
119 * to make progress, this is either a BUG or corrupted
120 * filesystem, so abort the journal and leave a stack
121 * trace for forensic evidence.
122 */
123 write_lock(&journal->j_state_lock);
124 if (journal->j_flags & JBD2_ABORT) {
125 mutex_unlock(&journal->j_checkpoint_mutex);
126 return;
127 }
128 spin_lock(&journal->j_list_lock);
129 space_left = jbd2_log_space_left(journal);
130 if (space_left < nblocks) {
131 int chkpt = journal->j_checkpoint_transactions != NULL;
132 tid_t tid = 0;
133
134 if (journal->j_committing_transaction)
135 tid = journal->j_committing_transaction->t_tid;
136 spin_unlock(&journal->j_list_lock);
137 write_unlock(&journal->j_state_lock);
138 if (chkpt) {
139 jbd2_log_do_checkpoint(journal);
140 } else if (jbd2_cleanup_journal_tail(journal) == 0) {
141 /* We were able to recover space; yay! */
142 ;
143 } else if (tid) {
144 /*
145 * jbd2_journal_commit_transaction() may want
146 * to take the checkpoint_mutex if JBD2_FLUSHED
147 * is set. So we need to temporarily drop it.
148 */
149 mutex_unlock(&journal->j_checkpoint_mutex);
150 jbd2_log_wait_commit(journal, tid);
151 write_lock(&journal->j_state_lock);
152 continue;
153 } else {
154 printk(KERN_ERR "%s: needed %d blocks and "
155 "only had %d space available\n",
156 __func__, nblocks, space_left);
157 printk(KERN_ERR "%s: no way to get more "
158 "journal space in %s\n", __func__,
159 journal->j_devname);
160 WARN_ON(1);
161 jbd2_journal_abort(journal, -EIO);
162 }
163 write_lock(&journal->j_state_lock);
164 } else {
165 spin_unlock(&journal->j_list_lock);
166 }
167 mutex_unlock(&journal->j_checkpoint_mutex);
168 }
169}
170
171static void
172__flush_batch(journal_t *journal, int *batch_count)
173{
174 int i;
175 struct blk_plug plug;
176
177 blk_start_plug(&plug);
178 for (i = 0; i < *batch_count; i++)
179 write_dirty_buffer(journal->j_chkpt_bhs[i], REQ_SYNC);
180 blk_finish_plug(&plug);
181
182 for (i = 0; i < *batch_count; i++) {
183 struct buffer_head *bh = journal->j_chkpt_bhs[i];
184 BUFFER_TRACE(bh, "brelse");
185 __brelse(bh);
186 }
187 *batch_count = 0;
188}
189
190/*
191 * Perform an actual checkpoint. We take the first transaction on the
192 * list of transactions to be checkpointed and send all its buffers
193 * to disk. We submit larger chunks of data at once.
194 *
195 * The journal should be locked before calling this function.
196 * Called with j_checkpoint_mutex held.
197 */
198int jbd2_log_do_checkpoint(journal_t *journal)
199{
200 struct journal_head *jh;
201 struct buffer_head *bh;
202 transaction_t *transaction;
203 tid_t this_tid;
204 int result, batch_count = 0;
205
206 jbd2_debug(1, "Start checkpoint\n");
207
208 /*
209 * First thing: if there are any transactions in the log which
210 * don't need checkpointing, just eliminate them from the
211 * journal straight away.
212 */
213 result = jbd2_cleanup_journal_tail(journal);
214 trace_jbd2_checkpoint(journal, result);
215 jbd2_debug(1, "cleanup_journal_tail returned %d\n", result);
216 if (result <= 0)
217 return result;
218
219 /*
220 * OK, we need to start writing disk blocks. Take one transaction
221 * and write it.
222 */
223 spin_lock(&journal->j_list_lock);
224 if (!journal->j_checkpoint_transactions)
225 goto out;
226 transaction = journal->j_checkpoint_transactions;
227 if (transaction->t_chp_stats.cs_chp_time == 0)
228 transaction->t_chp_stats.cs_chp_time = jiffies;
229 this_tid = transaction->t_tid;
230restart:
231 /*
232 * If someone cleaned up this transaction while we slept, we're
233 * done (maybe it's a new transaction, but it fell at the same
234 * address).
235 */
236 if (journal->j_checkpoint_transactions != transaction ||
237 transaction->t_tid != this_tid)
238 goto out;
239
240 /* checkpoint all of the transaction's buffers */
241 while (transaction->t_checkpoint_list) {
242 jh = transaction->t_checkpoint_list;
243 bh = jh2bh(jh);
244
245 if (buffer_locked(bh)) {
246 get_bh(bh);
247 spin_unlock(&journal->j_list_lock);
248 wait_on_buffer(bh);
249 /* the journal_head may have gone by now */
250 BUFFER_TRACE(bh, "brelse");
251 __brelse(bh);
252 goto retry;
253 }
254 if (jh->b_transaction != NULL) {
255 transaction_t *t = jh->b_transaction;
256 tid_t tid = t->t_tid;
257
258 transaction->t_chp_stats.cs_forced_to_close++;
259 spin_unlock(&journal->j_list_lock);
260 if (unlikely(journal->j_flags & JBD2_UNMOUNT))
261 /*
262 * The journal thread is dead; so
263 * starting and waiting for a commit
264 * to finish will cause us to wait for
265 * a _very_ long time.
266 */
267 printk(KERN_ERR
268 "JBD2: %s: Waiting for Godot: block %llu\n",
269 journal->j_devname, (unsigned long long) bh->b_blocknr);
270
271 if (batch_count)
272 __flush_batch(journal, &batch_count);
273 jbd2_log_start_commit(journal, tid);
274 /*
275 * jbd2_journal_commit_transaction() may want
276 * to take the checkpoint_mutex if JBD2_FLUSHED
277 * is set, jbd2_update_log_tail() called by
278 * jbd2_journal_commit_transaction() may also take
279 * checkpoint_mutex. So we need to temporarily
280 * drop it.
281 */
282 mutex_unlock(&journal->j_checkpoint_mutex);
283 jbd2_log_wait_commit(journal, tid);
284 mutex_lock_io(&journal->j_checkpoint_mutex);
285 spin_lock(&journal->j_list_lock);
286 goto restart;
287 }
288 if (!buffer_dirty(bh)) {
289 BUFFER_TRACE(bh, "remove from checkpoint");
290 if (__jbd2_journal_remove_checkpoint(jh))
291 /* The transaction was released; we're done */
292 goto out;
293 continue;
294 }
295 /*
296 * Important: we are about to write the buffer, and
297 * possibly block, while still holding the journal
298 * lock. We cannot afford to let the transaction
299 * logic start messing around with this buffer before
300 * we write it to disk, as that would break
301 * recoverability.
302 */
303 BUFFER_TRACE(bh, "queue");
304 get_bh(bh);
305 J_ASSERT_BH(bh, !buffer_jwrite(bh));
306 journal->j_chkpt_bhs[batch_count++] = bh;
307 __buffer_relink_io(jh);
308 transaction->t_chp_stats.cs_written++;
309 if ((batch_count == JBD2_NR_BATCH) ||
310 need_resched() ||
311 spin_needbreak(&journal->j_list_lock))
312 goto unlock_and_flush;
313 }
314
315 if (batch_count) {
316 unlock_and_flush:
317 spin_unlock(&journal->j_list_lock);
318 retry:
319 if (batch_count)
320 __flush_batch(journal, &batch_count);
321 spin_lock(&journal->j_list_lock);
322 goto restart;
323 }
324
325 /*
326 * Now we issued all of the transaction's buffers, let's deal
327 * with the buffers that are out for I/O.
328 */
329restart2:
330 /* Did somebody clean up the transaction in the meanwhile? */
331 if (journal->j_checkpoint_transactions != transaction ||
332 transaction->t_tid != this_tid)
333 goto out;
334
335 while (transaction->t_checkpoint_io_list) {
336 jh = transaction->t_checkpoint_io_list;
337 bh = jh2bh(jh);
338 if (buffer_locked(bh)) {
339 get_bh(bh);
340 spin_unlock(&journal->j_list_lock);
341 wait_on_buffer(bh);
342 /* the journal_head may have gone by now */
343 BUFFER_TRACE(bh, "brelse");
344 __brelse(bh);
345 spin_lock(&journal->j_list_lock);
346 goto restart2;
347 }
348
349 /*
350 * Now in whatever state the buffer currently is, we
351 * know that it has been written out and so we can
352 * drop it from the list
353 */
354 if (__jbd2_journal_remove_checkpoint(jh))
355 break;
356 }
357out:
358 spin_unlock(&journal->j_list_lock);
359 result = jbd2_cleanup_journal_tail(journal);
360
361 return (result < 0) ? result : 0;
362}
363
364/*
365 * Check the list of checkpoint transactions for the journal to see if
366 * we have already got rid of any since the last update of the log tail
367 * in the journal superblock. If so, we can instantly roll the
368 * superblock forward to remove those transactions from the log.
369 *
370 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
371 *
372 * Called with the journal lock held.
373 *
374 * This is the only part of the journaling code which really needs to be
375 * aware of transaction aborts. Checkpointing involves writing to the
376 * main filesystem area rather than to the journal, so it can proceed
377 * even in abort state, but we must not update the super block if
378 * checkpointing may have failed. Otherwise, we would lose some metadata
379 * buffers which should be written-back to the filesystem.
380 */
381
382int jbd2_cleanup_journal_tail(journal_t *journal)
383{
384 tid_t first_tid;
385 unsigned long blocknr;
386
387 if (is_journal_aborted(journal))
388 return -EIO;
389
390 if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
391 return 1;
392 J_ASSERT(blocknr != 0);
393
394 /*
395 * We need to make sure that any blocks that were recently written out
396 * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
397 * we drop the transactions from the journal. It's unlikely this will
398 * be necessary, especially with an appropriately sized journal, but we
399 * need this to guarantee correctness. Fortunately
400 * jbd2_cleanup_journal_tail() doesn't get called all that often.
401 */
402 if (journal->j_flags & JBD2_BARRIER)
403 blkdev_issue_flush(journal->j_fs_dev);
404
405 return __jbd2_update_log_tail(journal, first_tid, blocknr);
406}
407
408
409/* Checkpoint list management */
410
411/*
412 * journal_clean_one_cp_list
413 *
414 * Find all the written-back checkpoint buffers in the given list and
415 * release them. If 'destroy' is set, clean all buffers unconditionally.
416 *
417 * Called with j_list_lock held.
418 * Returns 1 if we freed the transaction, 0 otherwise.
419 */
420static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy)
421{
422 struct journal_head *last_jh;
423 struct journal_head *next_jh = jh;
424
425 if (!jh)
426 return 0;
427
428 last_jh = jh->b_cpprev;
429 do {
430 jh = next_jh;
431 next_jh = jh->b_cpnext;
432
433 if (!destroy && __cp_buffer_busy(jh))
434 return 0;
435
436 if (__jbd2_journal_remove_checkpoint(jh))
437 return 1;
438 /*
439 * This function only frees up some memory
440 * if possible so we dont have an obligation
441 * to finish processing. Bail out if preemption
442 * requested:
443 */
444 if (need_resched())
445 return 0;
446 } while (jh != last_jh);
447
448 return 0;
449}
450
451/*
452 * journal_shrink_one_cp_list
453 *
454 * Find 'nr_to_scan' written-back checkpoint buffers in the given list
455 * and try to release them. If the whole transaction is released, set
456 * the 'released' parameter. Return the number of released checkpointed
457 * buffers.
458 *
459 * Called with j_list_lock held.
460 */
461static unsigned long journal_shrink_one_cp_list(struct journal_head *jh,
462 unsigned long *nr_to_scan,
463 bool *released)
464{
465 struct journal_head *last_jh;
466 struct journal_head *next_jh = jh;
467 unsigned long nr_freed = 0;
468 int ret;
469
470 if (!jh || *nr_to_scan == 0)
471 return 0;
472
473 last_jh = jh->b_cpprev;
474 do {
475 jh = next_jh;
476 next_jh = jh->b_cpnext;
477
478 (*nr_to_scan)--;
479 if (__cp_buffer_busy(jh))
480 continue;
481
482 nr_freed++;
483 ret = __jbd2_journal_remove_checkpoint(jh);
484 if (ret) {
485 *released = true;
486 break;
487 }
488
489 if (need_resched())
490 break;
491 } while (jh != last_jh && *nr_to_scan);
492
493 return nr_freed;
494}
495
496/*
497 * jbd2_journal_shrink_checkpoint_list
498 *
499 * Find 'nr_to_scan' written-back checkpoint buffers in the journal
500 * and try to release them. Return the number of released checkpointed
501 * buffers.
502 *
503 * Called with j_list_lock held.
504 */
505unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
506 unsigned long *nr_to_scan)
507{
508 transaction_t *transaction, *last_transaction, *next_transaction;
509 bool released;
510 tid_t first_tid = 0, last_tid = 0, next_tid = 0;
511 tid_t tid = 0;
512 unsigned long nr_freed = 0;
513 unsigned long nr_scanned = *nr_to_scan;
514
515again:
516 spin_lock(&journal->j_list_lock);
517 if (!journal->j_checkpoint_transactions) {
518 spin_unlock(&journal->j_list_lock);
519 goto out;
520 }
521
522 /*
523 * Get next shrink transaction, resume previous scan or start
524 * over again. If some others do checkpoint and drop transaction
525 * from the checkpoint list, we ignore saved j_shrink_transaction
526 * and start over unconditionally.
527 */
528 if (journal->j_shrink_transaction)
529 transaction = journal->j_shrink_transaction;
530 else
531 transaction = journal->j_checkpoint_transactions;
532
533 if (!first_tid)
534 first_tid = transaction->t_tid;
535 last_transaction = journal->j_checkpoint_transactions->t_cpprev;
536 next_transaction = transaction;
537 last_tid = last_transaction->t_tid;
538 do {
539 transaction = next_transaction;
540 next_transaction = transaction->t_cpnext;
541 tid = transaction->t_tid;
542 released = false;
543
544 nr_freed += journal_shrink_one_cp_list(transaction->t_checkpoint_list,
545 nr_to_scan, &released);
546 if (*nr_to_scan == 0)
547 break;
548 if (need_resched() || spin_needbreak(&journal->j_list_lock))
549 break;
550 if (released)
551 continue;
552
553 nr_freed += journal_shrink_one_cp_list(transaction->t_checkpoint_io_list,
554 nr_to_scan, &released);
555 if (*nr_to_scan == 0)
556 break;
557 if (need_resched() || spin_needbreak(&journal->j_list_lock))
558 break;
559 } while (transaction != last_transaction);
560
561 if (transaction != last_transaction) {
562 journal->j_shrink_transaction = next_transaction;
563 next_tid = next_transaction->t_tid;
564 } else {
565 journal->j_shrink_transaction = NULL;
566 next_tid = 0;
567 }
568
569 spin_unlock(&journal->j_list_lock);
570 cond_resched();
571
572 if (*nr_to_scan && next_tid)
573 goto again;
574out:
575 nr_scanned -= *nr_to_scan;
576 trace_jbd2_shrink_checkpoint_list(journal, first_tid, tid, last_tid,
577 nr_freed, nr_scanned, next_tid);
578
579 return nr_freed;
580}
581
582/*
583 * journal_clean_checkpoint_list
584 *
585 * Find all the written-back checkpoint buffers in the journal and release them.
586 * If 'destroy' is set, release all buffers unconditionally.
587 *
588 * Called with j_list_lock held.
589 */
590void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
591{
592 transaction_t *transaction, *last_transaction, *next_transaction;
593 int ret;
594
595 transaction = journal->j_checkpoint_transactions;
596 if (!transaction)
597 return;
598
599 last_transaction = transaction->t_cpprev;
600 next_transaction = transaction;
601 do {
602 transaction = next_transaction;
603 next_transaction = transaction->t_cpnext;
604 ret = journal_clean_one_cp_list(transaction->t_checkpoint_list,
605 destroy);
606 /*
607 * This function only frees up some memory if possible so we
608 * dont have an obligation to finish processing. Bail out if
609 * preemption requested:
610 */
611 if (need_resched())
612 return;
613 if (ret)
614 continue;
615 /*
616 * It is essential that we are as careful as in the case of
617 * t_checkpoint_list with removing the buffer from the list as
618 * we can possibly see not yet submitted buffers on io_list
619 */
620 ret = journal_clean_one_cp_list(transaction->
621 t_checkpoint_io_list, destroy);
622 if (need_resched())
623 return;
624 /*
625 * Stop scanning if we couldn't free the transaction. This
626 * avoids pointless scanning of transactions which still
627 * weren't checkpointed.
628 */
629 if (!ret)
630 return;
631 } while (transaction != last_transaction);
632}
633
634/*
635 * Remove buffers from all checkpoint lists as journal is aborted and we just
636 * need to free memory
637 */
638void jbd2_journal_destroy_checkpoint(journal_t *journal)
639{
640 /*
641 * We loop because __jbd2_journal_clean_checkpoint_list() may abort
642 * early due to a need of rescheduling.
643 */
644 while (1) {
645 spin_lock(&journal->j_list_lock);
646 if (!journal->j_checkpoint_transactions) {
647 spin_unlock(&journal->j_list_lock);
648 break;
649 }
650 __jbd2_journal_clean_checkpoint_list(journal, true);
651 spin_unlock(&journal->j_list_lock);
652 cond_resched();
653 }
654}
655
656/*
657 * journal_remove_checkpoint: called after a buffer has been committed
658 * to disk (either by being write-back flushed to disk, or being
659 * committed to the log).
660 *
661 * We cannot safely clean a transaction out of the log until all of the
662 * buffer updates committed in that transaction have safely been stored
663 * elsewhere on disk. To achieve this, all of the buffers in a
664 * transaction need to be maintained on the transaction's checkpoint
665 * lists until they have been rewritten, at which point this function is
666 * called to remove the buffer from the existing transaction's
667 * checkpoint lists.
668 *
669 * The function returns 1 if it frees the transaction, 0 otherwise.
670 * The function can free jh and bh.
671 *
672 * This function is called with j_list_lock held.
673 */
674int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
675{
676 struct transaction_chp_stats_s *stats;
677 transaction_t *transaction;
678 journal_t *journal;
679 struct buffer_head *bh = jh2bh(jh);
680
681 JBUFFER_TRACE(jh, "entry");
682
683 transaction = jh->b_cp_transaction;
684 if (!transaction) {
685 JBUFFER_TRACE(jh, "not on transaction");
686 return 0;
687 }
688 journal = transaction->t_journal;
689
690 JBUFFER_TRACE(jh, "removing from transaction");
691
692 /*
693 * If we have failed to write the buffer out to disk, the filesystem
694 * may become inconsistent. We cannot abort the journal here since
695 * we hold j_list_lock and we have to be careful about races with
696 * jbd2_journal_destroy(). So mark the writeback IO error in the
697 * journal here and we abort the journal later from a better context.
698 */
699 if (buffer_write_io_error(bh))
700 set_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags);
701
702 __buffer_unlink(jh);
703 jh->b_cp_transaction = NULL;
704 percpu_counter_dec(&journal->j_checkpoint_jh_count);
705 jbd2_journal_put_journal_head(jh);
706
707 /* Is this transaction empty? */
708 if (transaction->t_checkpoint_list || transaction->t_checkpoint_io_list)
709 return 0;
710
711 /*
712 * There is one special case to worry about: if we have just pulled the
713 * buffer off a running or committing transaction's checkpoing list,
714 * then even if the checkpoint list is empty, the transaction obviously
715 * cannot be dropped!
716 *
717 * The locking here around t_state is a bit sleazy.
718 * See the comment at the end of jbd2_journal_commit_transaction().
719 */
720 if (transaction->t_state != T_FINISHED)
721 return 0;
722
723 /*
724 * OK, that was the last buffer for the transaction, we can now
725 * safely remove this transaction from the log.
726 */
727 stats = &transaction->t_chp_stats;
728 if (stats->cs_chp_time)
729 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
730 jiffies);
731 trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
732 transaction->t_tid, stats);
733
734 __jbd2_journal_drop_transaction(journal, transaction);
735 jbd2_journal_free_transaction(transaction);
736 return 1;
737}
738
739/*
740 * journal_insert_checkpoint: put a committed buffer onto a checkpoint
741 * list so that we know when it is safe to clean the transaction out of
742 * the log.
743 *
744 * Called with the journal locked.
745 * Called with j_list_lock held.
746 */
747void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
748 transaction_t *transaction)
749{
750 JBUFFER_TRACE(jh, "entry");
751 J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
752 J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
753
754 /* Get reference for checkpointing transaction */
755 jbd2_journal_grab_journal_head(jh2bh(jh));
756 jh->b_cp_transaction = transaction;
757
758 if (!transaction->t_checkpoint_list) {
759 jh->b_cpnext = jh->b_cpprev = jh;
760 } else {
761 jh->b_cpnext = transaction->t_checkpoint_list;
762 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
763 jh->b_cpprev->b_cpnext = jh;
764 jh->b_cpnext->b_cpprev = jh;
765 }
766 transaction->t_checkpoint_list = jh;
767 percpu_counter_inc(&transaction->t_journal->j_checkpoint_jh_count);
768}
769
770/*
771 * We've finished with this transaction structure: adios...
772 *
773 * The transaction must have no links except for the checkpoint by this
774 * point.
775 *
776 * Called with the journal locked.
777 * Called with j_list_lock held.
778 */
779
780void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
781{
782 assert_spin_locked(&journal->j_list_lock);
783
784 journal->j_shrink_transaction = NULL;
785 if (transaction->t_cpnext) {
786 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
787 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
788 if (journal->j_checkpoint_transactions == transaction)
789 journal->j_checkpoint_transactions =
790 transaction->t_cpnext;
791 if (journal->j_checkpoint_transactions == transaction)
792 journal->j_checkpoint_transactions = NULL;
793 }
794
795 J_ASSERT(transaction->t_state == T_FINISHED);
796 J_ASSERT(transaction->t_buffers == NULL);
797 J_ASSERT(transaction->t_forget == NULL);
798 J_ASSERT(transaction->t_shadow_list == NULL);
799 J_ASSERT(transaction->t_checkpoint_list == NULL);
800 J_ASSERT(transaction->t_checkpoint_io_list == NULL);
801 J_ASSERT(atomic_read(&transaction->t_updates) == 0);
802 J_ASSERT(journal->j_committing_transaction != transaction);
803 J_ASSERT(journal->j_running_transaction != transaction);
804
805 trace_jbd2_drop_transaction(journal, transaction);
806
807 jbd2_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
808}