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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/*
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 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
92 */
93static int __try_to_free_cp_buf(struct journal_head *jh)
94{
95 int ret = 0;
96 struct buffer_head *bh = jh2bh(jh);
97
98 if (jh->b_jlist == BJ_None && !buffer_locked(bh) &&
99 !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
100 /*
101 * Get our reference so that bh cannot be freed before
102 * we unlock it
103 */
104 get_bh(bh);
105 JBUFFER_TRACE(jh, "remove from checkpoint list");
106 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
107 jbd_unlock_bh_state(bh);
108 BUFFER_TRACE(bh, "release");
109 __brelse(bh);
110 } else {
111 jbd_unlock_bh_state(bh);
112 }
113 return ret;
114}
115
116/*
117 * __jbd2_log_wait_for_space: wait until there is space in the journal.
118 *
119 * Called under j-state_lock *only*. It will be unlocked if we have to wait
120 * for a checkpoint to free up some space in the log.
121 */
122void __jbd2_log_wait_for_space(journal_t *journal)
123{
124 int nblocks, space_left;
125 /* assert_spin_locked(&journal->j_state_lock); */
126
127 nblocks = jbd_space_needed(journal);
128 while (__jbd2_log_space_left(journal) < nblocks) {
129 if (journal->j_flags & JBD2_ABORT)
130 return;
131 write_unlock(&journal->j_state_lock);
132 mutex_lock(&journal->j_checkpoint_mutex);
133
134 /*
135 * Test again, another process may have checkpointed while we
136 * were waiting for the checkpoint lock. If there are no
137 * transactions ready to be checkpointed, try to recover
138 * journal space by calling cleanup_journal_tail(), and if
139 * that doesn't work, by waiting for the currently committing
140 * transaction to complete. If there is absolutely no way
141 * to make progress, this is either a BUG or corrupted
142 * filesystem, so abort the journal and leave a stack
143 * trace for forensic evidence.
144 */
145 write_lock(&journal->j_state_lock);
146 spin_lock(&journal->j_list_lock);
147 nblocks = jbd_space_needed(journal);
148 space_left = __jbd2_log_space_left(journal);
149 if (space_left < nblocks) {
150 int chkpt = journal->j_checkpoint_transactions != NULL;
151 tid_t tid = 0;
152
153 if (journal->j_committing_transaction)
154 tid = journal->j_committing_transaction->t_tid;
155 spin_unlock(&journal->j_list_lock);
156 write_unlock(&journal->j_state_lock);
157 if (chkpt) {
158 jbd2_log_do_checkpoint(journal);
159 } else if (jbd2_cleanup_journal_tail(journal) == 0) {
160 /* We were able to recover space; yay! */
161 ;
162 } else if (tid) {
163 jbd2_log_wait_commit(journal, tid);
164 } else {
165 printk(KERN_ERR "%s: needed %d blocks and "
166 "only had %d space available\n",
167 __func__, nblocks, space_left);
168 printk(KERN_ERR "%s: no way to get more "
169 "journal space in %s\n", __func__,
170 journal->j_devname);
171 WARN_ON(1);
172 jbd2_journal_abort(journal, 0);
173 }
174 write_lock(&journal->j_state_lock);
175 } else {
176 spin_unlock(&journal->j_list_lock);
177 }
178 mutex_unlock(&journal->j_checkpoint_mutex);
179 }
180}
181
182/*
183 * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
184 * The caller must restart a list walk. Wait for someone else to run
185 * jbd_unlock_bh_state().
186 */
187static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
188 __releases(journal->j_list_lock)
189{
190 get_bh(bh);
191 spin_unlock(&journal->j_list_lock);
192 jbd_lock_bh_state(bh);
193 jbd_unlock_bh_state(bh);
194 put_bh(bh);
195}
196
197/*
198 * Clean up transaction's list of buffers submitted for io.
199 * We wait for any pending IO to complete and remove any clean
200 * buffers. Note that we take the buffers in the opposite ordering
201 * from the one in which they were submitted for IO.
202 *
203 * Return 0 on success, and return <0 if some buffers have failed
204 * to be written out.
205 *
206 * Called with j_list_lock held.
207 */
208static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
209{
210 struct journal_head *jh;
211 struct buffer_head *bh;
212 tid_t this_tid;
213 int released = 0;
214 int ret = 0;
215
216 this_tid = transaction->t_tid;
217restart:
218 /* Did somebody clean up the transaction in the meanwhile? */
219 if (journal->j_checkpoint_transactions != transaction ||
220 transaction->t_tid != this_tid)
221 return ret;
222 while (!released && transaction->t_checkpoint_io_list) {
223 jh = transaction->t_checkpoint_io_list;
224 bh = jh2bh(jh);
225 if (!jbd_trylock_bh_state(bh)) {
226 jbd_sync_bh(journal, bh);
227 spin_lock(&journal->j_list_lock);
228 goto restart;
229 }
230 get_bh(bh);
231 if (buffer_locked(bh)) {
232 spin_unlock(&journal->j_list_lock);
233 jbd_unlock_bh_state(bh);
234 wait_on_buffer(bh);
235 /* the journal_head may have gone by now */
236 BUFFER_TRACE(bh, "brelse");
237 __brelse(bh);
238 spin_lock(&journal->j_list_lock);
239 goto restart;
240 }
241 if (unlikely(buffer_write_io_error(bh)))
242 ret = -EIO;
243
244 /*
245 * Now in whatever state the buffer currently is, we know that
246 * it has been written out and so we can drop it from the list
247 */
248 released = __jbd2_journal_remove_checkpoint(jh);
249 jbd_unlock_bh_state(bh);
250 __brelse(bh);
251 }
252
253 return ret;
254}
255
256static void
257__flush_batch(journal_t *journal, int *batch_count)
258{
259 int i;
260 struct blk_plug plug;
261
262 blk_start_plug(&plug);
263 for (i = 0; i < *batch_count; i++)
264 write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE_SYNC);
265 blk_finish_plug(&plug);
266
267 for (i = 0; i < *batch_count; i++) {
268 struct buffer_head *bh = journal->j_chkpt_bhs[i];
269 clear_buffer_jwrite(bh);
270 BUFFER_TRACE(bh, "brelse");
271 __brelse(bh);
272 }
273 *batch_count = 0;
274}
275
276/*
277 * Try to flush one buffer from the checkpoint list to disk.
278 *
279 * Return 1 if something happened which requires us to abort the current
280 * scan of the checkpoint list. Return <0 if the buffer has failed to
281 * be written out.
282 *
283 * Called with j_list_lock held and drops it if 1 is returned
284 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
285 */
286static int __process_buffer(journal_t *journal, struct journal_head *jh,
287 int *batch_count, transaction_t *transaction)
288{
289 struct buffer_head *bh = jh2bh(jh);
290 int ret = 0;
291
292 if (buffer_locked(bh)) {
293 get_bh(bh);
294 spin_unlock(&journal->j_list_lock);
295 jbd_unlock_bh_state(bh);
296 wait_on_buffer(bh);
297 /* the journal_head may have gone by now */
298 BUFFER_TRACE(bh, "brelse");
299 __brelse(bh);
300 ret = 1;
301 } else if (jh->b_transaction != NULL) {
302 transaction_t *t = jh->b_transaction;
303 tid_t tid = t->t_tid;
304
305 transaction->t_chp_stats.cs_forced_to_close++;
306 spin_unlock(&journal->j_list_lock);
307 jbd_unlock_bh_state(bh);
308 if (unlikely(journal->j_flags & JBD2_UNMOUNT))
309 /*
310 * The journal thread is dead; so starting and
311 * waiting for a commit to finish will cause
312 * us to wait for a _very_ long time.
313 */
314 printk(KERN_ERR "JBD2: %s: "
315 "Waiting for Godot: block %llu\n",
316 journal->j_devname,
317 (unsigned long long) bh->b_blocknr);
318 jbd2_log_start_commit(journal, tid);
319 jbd2_log_wait_commit(journal, tid);
320 ret = 1;
321 } else if (!buffer_dirty(bh)) {
322 ret = 1;
323 if (unlikely(buffer_write_io_error(bh)))
324 ret = -EIO;
325 get_bh(bh);
326 J_ASSERT_JH(jh, !buffer_jbddirty(bh));
327 BUFFER_TRACE(bh, "remove from checkpoint");
328 __jbd2_journal_remove_checkpoint(jh);
329 spin_unlock(&journal->j_list_lock);
330 jbd_unlock_bh_state(bh);
331 __brelse(bh);
332 } else {
333 /*
334 * Important: we are about to write the buffer, and
335 * possibly block, while still holding the journal lock.
336 * We cannot afford to let the transaction logic start
337 * messing around with this buffer before we write it to
338 * disk, as that would break recoverability.
339 */
340 BUFFER_TRACE(bh, "queue");
341 get_bh(bh);
342 J_ASSERT_BH(bh, !buffer_jwrite(bh));
343 set_buffer_jwrite(bh);
344 journal->j_chkpt_bhs[*batch_count] = bh;
345 __buffer_relink_io(jh);
346 jbd_unlock_bh_state(bh);
347 transaction->t_chp_stats.cs_written++;
348 (*batch_count)++;
349 if (*batch_count == JBD2_NR_BATCH) {
350 spin_unlock(&journal->j_list_lock);
351 __flush_batch(journal, batch_count);
352 ret = 1;
353 }
354 }
355 return ret;
356}
357
358/*
359 * Perform an actual checkpoint. We take the first transaction on the
360 * list of transactions to be checkpointed and send all its buffers
361 * to disk. We submit larger chunks of data at once.
362 *
363 * The journal should be locked before calling this function.
364 * Called with j_checkpoint_mutex held.
365 */
366int jbd2_log_do_checkpoint(journal_t *journal)
367{
368 transaction_t *transaction;
369 tid_t this_tid;
370 int result;
371
372 jbd_debug(1, "Start checkpoint\n");
373
374 /*
375 * First thing: if there are any transactions in the log which
376 * don't need checkpointing, just eliminate them from the
377 * journal straight away.
378 */
379 result = jbd2_cleanup_journal_tail(journal);
380 trace_jbd2_checkpoint(journal, result);
381 jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
382 if (result <= 0)
383 return result;
384
385 /*
386 * OK, we need to start writing disk blocks. Take one transaction
387 * and write it.
388 */
389 result = 0;
390 spin_lock(&journal->j_list_lock);
391 if (!journal->j_checkpoint_transactions)
392 goto out;
393 transaction = journal->j_checkpoint_transactions;
394 if (transaction->t_chp_stats.cs_chp_time == 0)
395 transaction->t_chp_stats.cs_chp_time = jiffies;
396 this_tid = transaction->t_tid;
397restart:
398 /*
399 * If someone cleaned up this transaction while we slept, we're
400 * done (maybe it's a new transaction, but it fell at the same
401 * address).
402 */
403 if (journal->j_checkpoint_transactions == transaction &&
404 transaction->t_tid == this_tid) {
405 int batch_count = 0;
406 struct journal_head *jh;
407 int retry = 0, err;
408
409 while (!retry && transaction->t_checkpoint_list) {
410 struct buffer_head *bh;
411
412 jh = transaction->t_checkpoint_list;
413 bh = jh2bh(jh);
414 if (!jbd_trylock_bh_state(bh)) {
415 jbd_sync_bh(journal, bh);
416 retry = 1;
417 break;
418 }
419 retry = __process_buffer(journal, jh, &batch_count,
420 transaction);
421 if (retry < 0 && !result)
422 result = retry;
423 if (!retry && (need_resched() ||
424 spin_needbreak(&journal->j_list_lock))) {
425 spin_unlock(&journal->j_list_lock);
426 retry = 1;
427 break;
428 }
429 }
430
431 if (batch_count) {
432 if (!retry) {
433 spin_unlock(&journal->j_list_lock);
434 retry = 1;
435 }
436 __flush_batch(journal, &batch_count);
437 }
438
439 if (retry) {
440 spin_lock(&journal->j_list_lock);
441 goto restart;
442 }
443 /*
444 * Now we have cleaned up the first transaction's checkpoint
445 * list. Let's clean up the second one
446 */
447 err = __wait_cp_io(journal, transaction);
448 if (!result)
449 result = err;
450 }
451out:
452 spin_unlock(&journal->j_list_lock);
453 if (result < 0)
454 jbd2_journal_abort(journal, result);
455 else
456 result = jbd2_cleanup_journal_tail(journal);
457
458 return (result < 0) ? result : 0;
459}
460
461/*
462 * Check the list of checkpoint transactions for the journal to see if
463 * we have already got rid of any since the last update of the log tail
464 * in the journal superblock. If so, we can instantly roll the
465 * superblock forward to remove those transactions from the log.
466 *
467 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
468 *
469 * Called with the journal lock held.
470 *
471 * This is the only part of the journaling code which really needs to be
472 * aware of transaction aborts. Checkpointing involves writing to the
473 * main filesystem area rather than to the journal, so it can proceed
474 * even in abort state, but we must not update the super block if
475 * checkpointing may have failed. Otherwise, we would lose some metadata
476 * buffers which should be written-back to the filesystem.
477 */
478
479int jbd2_cleanup_journal_tail(journal_t *journal)
480{
481 transaction_t * transaction;
482 tid_t first_tid;
483 unsigned long blocknr, freed;
484
485 if (is_journal_aborted(journal))
486 return 1;
487
488 /* OK, work out the oldest transaction remaining in the log, and
489 * the log block it starts at.
490 *
491 * If the log is now empty, we need to work out which is the
492 * next transaction ID we will write, and where it will
493 * start. */
494
495 write_lock(&journal->j_state_lock);
496 spin_lock(&journal->j_list_lock);
497 transaction = journal->j_checkpoint_transactions;
498 if (transaction) {
499 first_tid = transaction->t_tid;
500 blocknr = transaction->t_log_start;
501 } else if ((transaction = journal->j_committing_transaction) != NULL) {
502 first_tid = transaction->t_tid;
503 blocknr = transaction->t_log_start;
504 } else if ((transaction = journal->j_running_transaction) != NULL) {
505 first_tid = transaction->t_tid;
506 blocknr = journal->j_head;
507 } else {
508 first_tid = journal->j_transaction_sequence;
509 blocknr = journal->j_head;
510 }
511 spin_unlock(&journal->j_list_lock);
512 J_ASSERT(blocknr != 0);
513
514 /* If the oldest pinned transaction is at the tail of the log
515 already then there's not much we can do right now. */
516 if (journal->j_tail_sequence == first_tid) {
517 write_unlock(&journal->j_state_lock);
518 return 1;
519 }
520
521 /* OK, update the superblock to recover the freed space.
522 * Physical blocks come first: have we wrapped beyond the end of
523 * the log? */
524 freed = blocknr - journal->j_tail;
525 if (blocknr < journal->j_tail)
526 freed = freed + journal->j_last - journal->j_first;
527
528 trace_jbd2_cleanup_journal_tail(journal, first_tid, blocknr, freed);
529 jbd_debug(1,
530 "Cleaning journal tail from %d to %d (offset %lu), "
531 "freeing %lu\n",
532 journal->j_tail_sequence, first_tid, blocknr, freed);
533
534 journal->j_free += freed;
535 journal->j_tail_sequence = first_tid;
536 journal->j_tail = blocknr;
537 write_unlock(&journal->j_state_lock);
538
539 /*
540 * If there is an external journal, we need to make sure that
541 * any data blocks that were recently written out --- perhaps
542 * by jbd2_log_do_checkpoint() --- are flushed out before we
543 * drop the transactions from the external journal. It's
544 * unlikely this will be necessary, especially with a
545 * appropriately sized journal, but we need this to guarantee
546 * correctness. Fortunately jbd2_cleanup_journal_tail()
547 * doesn't get called all that often.
548 */
549 if ((journal->j_fs_dev != journal->j_dev) &&
550 (journal->j_flags & JBD2_BARRIER))
551 blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
552 if (!(journal->j_flags & JBD2_ABORT))
553 jbd2_journal_update_superblock(journal, 1);
554 return 0;
555}
556
557
558/* Checkpoint list management */
559
560/*
561 * journal_clean_one_cp_list
562 *
563 * Find all the written-back checkpoint buffers in the given list and
564 * release them.
565 *
566 * Called with the journal locked.
567 * Called with j_list_lock held.
568 * Returns number of bufers reaped (for debug)
569 */
570
571static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
572{
573 struct journal_head *last_jh;
574 struct journal_head *next_jh = jh;
575 int ret, freed = 0;
576
577 *released = 0;
578 if (!jh)
579 return 0;
580
581 last_jh = jh->b_cpprev;
582 do {
583 jh = next_jh;
584 next_jh = jh->b_cpnext;
585 /* Use trylock because of the ranking */
586 if (jbd_trylock_bh_state(jh2bh(jh))) {
587 ret = __try_to_free_cp_buf(jh);
588 if (ret) {
589 freed++;
590 if (ret == 2) {
591 *released = 1;
592 return freed;
593 }
594 }
595 }
596 /*
597 * This function only frees up some memory
598 * if possible so we dont have an obligation
599 * to finish processing. Bail out if preemption
600 * requested:
601 */
602 if (need_resched())
603 return freed;
604 } while (jh != last_jh);
605
606 return freed;
607}
608
609/*
610 * journal_clean_checkpoint_list
611 *
612 * Find all the written-back checkpoint buffers in the journal and release them.
613 *
614 * Called with the journal locked.
615 * Called with j_list_lock held.
616 * Returns number of buffers reaped (for debug)
617 */
618
619int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
620{
621 transaction_t *transaction, *last_transaction, *next_transaction;
622 int ret = 0;
623 int released;
624
625 transaction = journal->j_checkpoint_transactions;
626 if (!transaction)
627 goto out;
628
629 last_transaction = transaction->t_cpprev;
630 next_transaction = transaction;
631 do {
632 transaction = next_transaction;
633 next_transaction = transaction->t_cpnext;
634 ret += journal_clean_one_cp_list(transaction->
635 t_checkpoint_list, &released);
636 /*
637 * This function only frees up some memory if possible so we
638 * dont have an obligation to finish processing. Bail out if
639 * preemption requested:
640 */
641 if (need_resched())
642 goto out;
643 if (released)
644 continue;
645 /*
646 * It is essential that we are as careful as in the case of
647 * t_checkpoint_list with removing the buffer from the list as
648 * we can possibly see not yet submitted buffers on io_list
649 */
650 ret += journal_clean_one_cp_list(transaction->
651 t_checkpoint_io_list, &released);
652 if (need_resched())
653 goto out;
654 } while (transaction != last_transaction);
655out:
656 return ret;
657}
658
659/*
660 * journal_remove_checkpoint: called after a buffer has been committed
661 * to disk (either by being write-back flushed to disk, or being
662 * committed to the log).
663 *
664 * We cannot safely clean a transaction out of the log until all of the
665 * buffer updates committed in that transaction have safely been stored
666 * elsewhere on disk. To achieve this, all of the buffers in a
667 * transaction need to be maintained on the transaction's checkpoint
668 * lists until they have been rewritten, at which point this function is
669 * called to remove the buffer from the existing transaction's
670 * checkpoint lists.
671 *
672 * The function returns 1 if it frees the transaction, 0 otherwise.
673 * The function can free jh and bh.
674 *
675 * This function is called with j_list_lock held.
676 * This function is called with jbd_lock_bh_state(jh2bh(jh))
677 */
678
679int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
680{
681 struct transaction_chp_stats_s *stats;
682 transaction_t *transaction;
683 journal_t *journal;
684 int ret = 0;
685
686 JBUFFER_TRACE(jh, "entry");
687
688 if ((transaction = jh->b_cp_transaction) == NULL) {
689 JBUFFER_TRACE(jh, "not on transaction");
690 goto out;
691 }
692 journal = transaction->t_journal;
693
694 JBUFFER_TRACE(jh, "removing from transaction");
695 __buffer_unlink(jh);
696 jh->b_cp_transaction = NULL;
697 jbd2_journal_put_journal_head(jh);
698
699 if (transaction->t_checkpoint_list != NULL ||
700 transaction->t_checkpoint_io_list != NULL)
701 goto out;
702
703 /*
704 * There is one special case to worry about: if we have just pulled the
705 * buffer off a running or committing transaction's checkpoing list,
706 * then even if the checkpoint list is empty, the transaction obviously
707 * cannot be dropped!
708 *
709 * The locking here around t_state is a bit sleazy.
710 * See the comment at the end of jbd2_journal_commit_transaction().
711 */
712 if (transaction->t_state != T_FINISHED)
713 goto out;
714
715 /* OK, that was the last buffer for the transaction: we can now
716 safely remove this transaction from the log */
717 stats = &transaction->t_chp_stats;
718 if (stats->cs_chp_time)
719 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
720 jiffies);
721 trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
722 transaction->t_tid, stats);
723
724 __jbd2_journal_drop_transaction(journal, transaction);
725 kfree(transaction);
726
727 /* Just in case anybody was waiting for more transactions to be
728 checkpointed... */
729 wake_up(&journal->j_wait_logspace);
730 ret = 1;
731out:
732 return ret;
733}
734
735/*
736 * journal_insert_checkpoint: put a committed buffer onto a checkpoint
737 * list so that we know when it is safe to clean the transaction out of
738 * the log.
739 *
740 * Called with the journal locked.
741 * Called with j_list_lock held.
742 */
743void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
744 transaction_t *transaction)
745{
746 JBUFFER_TRACE(jh, "entry");
747 J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
748 J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
749
750 /* Get reference for checkpointing transaction */
751 jbd2_journal_grab_journal_head(jh2bh(jh));
752 jh->b_cp_transaction = transaction;
753
754 if (!transaction->t_checkpoint_list) {
755 jh->b_cpnext = jh->b_cpprev = jh;
756 } else {
757 jh->b_cpnext = transaction->t_checkpoint_list;
758 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
759 jh->b_cpprev->b_cpnext = jh;
760 jh->b_cpnext->b_cpprev = jh;
761 }
762 transaction->t_checkpoint_list = jh;
763}
764
765/*
766 * We've finished with this transaction structure: adios...
767 *
768 * The transaction must have no links except for the checkpoint by this
769 * point.
770 *
771 * Called with the journal locked.
772 * Called with j_list_lock held.
773 */
774
775void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
776{
777 assert_spin_locked(&journal->j_list_lock);
778 if (transaction->t_cpnext) {
779 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
780 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
781 if (journal->j_checkpoint_transactions == transaction)
782 journal->j_checkpoint_transactions =
783 transaction->t_cpnext;
784 if (journal->j_checkpoint_transactions == transaction)
785 journal->j_checkpoint_transactions = NULL;
786 }
787
788 J_ASSERT(transaction->t_state == T_FINISHED);
789 J_ASSERT(transaction->t_buffers == NULL);
790 J_ASSERT(transaction->t_forget == NULL);
791 J_ASSERT(transaction->t_iobuf_list == NULL);
792 J_ASSERT(transaction->t_shadow_list == NULL);
793 J_ASSERT(transaction->t_log_list == NULL);
794 J_ASSERT(transaction->t_checkpoint_list == NULL);
795 J_ASSERT(transaction->t_checkpoint_io_list == NULL);
796 J_ASSERT(atomic_read(&transaction->t_updates) == 0);
797 J_ASSERT(journal->j_committing_transaction != transaction);
798 J_ASSERT(journal->j_running_transaction != transaction);
799
800 jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
801}