Loading...
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 JBUFFER_TRACE(jh, "remove from checkpoint list");
100 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
101 }
102 return ret;
103}
104
105/*
106 * __jbd2_log_wait_for_space: wait until there is space in the journal.
107 *
108 * Called under j-state_lock *only*. It will be unlocked if we have to wait
109 * for a checkpoint to free up some space in the log.
110 */
111void __jbd2_log_wait_for_space(journal_t *journal)
112{
113 int nblocks, space_left;
114 /* assert_spin_locked(&journal->j_state_lock); */
115
116 nblocks = jbd2_space_needed(journal);
117 while (jbd2_log_space_left(journal) < nblocks) {
118 write_unlock(&journal->j_state_lock);
119 mutex_lock(&journal->j_checkpoint_mutex);
120
121 /*
122 * Test again, another process may have checkpointed while we
123 * were waiting for the checkpoint lock. If there are no
124 * transactions ready to be checkpointed, try to recover
125 * journal space by calling cleanup_journal_tail(), and if
126 * that doesn't work, by waiting for the currently committing
127 * transaction to complete. If there is absolutely no way
128 * to make progress, this is either a BUG or corrupted
129 * filesystem, so abort the journal and leave a stack
130 * trace for forensic evidence.
131 */
132 write_lock(&journal->j_state_lock);
133 if (journal->j_flags & JBD2_ABORT) {
134 mutex_unlock(&journal->j_checkpoint_mutex);
135 return;
136 }
137 spin_lock(&journal->j_list_lock);
138 nblocks = jbd2_space_needed(journal);
139 space_left = jbd2_log_space_left(journal);
140 if (space_left < nblocks) {
141 int chkpt = journal->j_checkpoint_transactions != NULL;
142 tid_t tid = 0;
143
144 if (journal->j_committing_transaction)
145 tid = journal->j_committing_transaction->t_tid;
146 spin_unlock(&journal->j_list_lock);
147 write_unlock(&journal->j_state_lock);
148 if (chkpt) {
149 jbd2_log_do_checkpoint(journal);
150 } else if (jbd2_cleanup_journal_tail(journal) == 0) {
151 /* We were able to recover space; yay! */
152 ;
153 } else if (tid) {
154 /*
155 * jbd2_journal_commit_transaction() may want
156 * to take the checkpoint_mutex if JBD2_FLUSHED
157 * is set. So we need to temporarily drop it.
158 */
159 mutex_unlock(&journal->j_checkpoint_mutex);
160 jbd2_log_wait_commit(journal, tid);
161 write_lock(&journal->j_state_lock);
162 continue;
163 } else {
164 printk(KERN_ERR "%s: needed %d blocks and "
165 "only had %d space available\n",
166 __func__, nblocks, space_left);
167 printk(KERN_ERR "%s: no way to get more "
168 "journal space in %s\n", __func__,
169 journal->j_devname);
170 WARN_ON(1);
171 jbd2_journal_abort(journal, 0);
172 }
173 write_lock(&journal->j_state_lock);
174 } else {
175 spin_unlock(&journal->j_list_lock);
176 }
177 mutex_unlock(&journal->j_checkpoint_mutex);
178 }
179}
180
181static void
182__flush_batch(journal_t *journal, int *batch_count)
183{
184 int i;
185 struct blk_plug plug;
186
187 blk_start_plug(&plug);
188 for (i = 0; i < *batch_count; i++)
189 write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE_SYNC);
190 blk_finish_plug(&plug);
191
192 for (i = 0; i < *batch_count; i++) {
193 struct buffer_head *bh = journal->j_chkpt_bhs[i];
194 BUFFER_TRACE(bh, "brelse");
195 __brelse(bh);
196 }
197 *batch_count = 0;
198}
199
200/*
201 * Perform an actual checkpoint. We take the first transaction on the
202 * list of transactions to be checkpointed and send all its buffers
203 * to disk. We submit larger chunks of data at once.
204 *
205 * The journal should be locked before calling this function.
206 * Called with j_checkpoint_mutex held.
207 */
208int jbd2_log_do_checkpoint(journal_t *journal)
209{
210 struct journal_head *jh;
211 struct buffer_head *bh;
212 transaction_t *transaction;
213 tid_t this_tid;
214 int result, batch_count = 0;
215
216 jbd_debug(1, "Start checkpoint\n");
217
218 /*
219 * First thing: if there are any transactions in the log which
220 * don't need checkpointing, just eliminate them from the
221 * journal straight away.
222 */
223 result = jbd2_cleanup_journal_tail(journal);
224 trace_jbd2_checkpoint(journal, result);
225 jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
226 if (result <= 0)
227 return result;
228
229 /*
230 * OK, we need to start writing disk blocks. Take one transaction
231 * and write it.
232 */
233 result = 0;
234 spin_lock(&journal->j_list_lock);
235 if (!journal->j_checkpoint_transactions)
236 goto out;
237 transaction = journal->j_checkpoint_transactions;
238 if (transaction->t_chp_stats.cs_chp_time == 0)
239 transaction->t_chp_stats.cs_chp_time = jiffies;
240 this_tid = transaction->t_tid;
241restart:
242 /*
243 * If someone cleaned up this transaction while we slept, we're
244 * done (maybe it's a new transaction, but it fell at the same
245 * address).
246 */
247 if (journal->j_checkpoint_transactions != transaction ||
248 transaction->t_tid != this_tid)
249 goto out;
250
251 /* checkpoint all of the transaction's buffers */
252 while (transaction->t_checkpoint_list) {
253 jh = transaction->t_checkpoint_list;
254 bh = jh2bh(jh);
255
256 if (buffer_locked(bh)) {
257 spin_unlock(&journal->j_list_lock);
258 get_bh(bh);
259 wait_on_buffer(bh);
260 /* the journal_head may have gone by now */
261 BUFFER_TRACE(bh, "brelse");
262 __brelse(bh);
263 goto retry;
264 }
265 if (jh->b_transaction != NULL) {
266 transaction_t *t = jh->b_transaction;
267 tid_t tid = t->t_tid;
268
269 transaction->t_chp_stats.cs_forced_to_close++;
270 spin_unlock(&journal->j_list_lock);
271 if (unlikely(journal->j_flags & JBD2_UNMOUNT))
272 /*
273 * The journal thread is dead; so
274 * starting and waiting for a commit
275 * to finish will cause us to wait for
276 * a _very_ long time.
277 */
278 printk(KERN_ERR
279 "JBD2: %s: Waiting for Godot: block %llu\n",
280 journal->j_devname, (unsigned long long) bh->b_blocknr);
281
282 jbd2_log_start_commit(journal, tid);
283 jbd2_log_wait_commit(journal, tid);
284 goto retry;
285 }
286 if (!buffer_dirty(bh)) {
287 if (unlikely(buffer_write_io_error(bh)) && !result)
288 result = -EIO;
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 spin_unlock(&journal->j_list_lock);
340 get_bh(bh);
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 if (unlikely(buffer_write_io_error(bh)) && !result)
349 result = -EIO;
350
351 /*
352 * Now in whatever state the buffer currently is, we
353 * know that it has been written out and so we can
354 * drop it from the list
355 */
356 if (__jbd2_journal_remove_checkpoint(jh))
357 break;
358 }
359out:
360 spin_unlock(&journal->j_list_lock);
361 if (result < 0)
362 jbd2_journal_abort(journal, result);
363 else
364 result = jbd2_cleanup_journal_tail(journal);
365
366 return (result < 0) ? result : 0;
367}
368
369/*
370 * Check the list of checkpoint transactions for the journal to see if
371 * we have already got rid of any since the last update of the log tail
372 * in the journal superblock. If so, we can instantly roll the
373 * superblock forward to remove those transactions from the log.
374 *
375 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
376 *
377 * Called with the journal lock held.
378 *
379 * This is the only part of the journaling code which really needs to be
380 * aware of transaction aborts. Checkpointing involves writing to the
381 * main filesystem area rather than to the journal, so it can proceed
382 * even in abort state, but we must not update the super block if
383 * checkpointing may have failed. Otherwise, we would lose some metadata
384 * buffers which should be written-back to the filesystem.
385 */
386
387int jbd2_cleanup_journal_tail(journal_t *journal)
388{
389 tid_t first_tid;
390 unsigned long blocknr;
391
392 if (is_journal_aborted(journal))
393 return -EIO;
394
395 if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
396 return 1;
397 J_ASSERT(blocknr != 0);
398
399 /*
400 * We need to make sure that any blocks that were recently written out
401 * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
402 * we drop the transactions from the journal. It's unlikely this will
403 * be necessary, especially with an appropriately sized journal, but we
404 * need this to guarantee correctness. Fortunately
405 * jbd2_cleanup_journal_tail() doesn't get called all that often.
406 */
407 if (journal->j_flags & JBD2_BARRIER)
408 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
409
410 return __jbd2_update_log_tail(journal, first_tid, blocknr);
411}
412
413
414/* Checkpoint list management */
415
416/*
417 * journal_clean_one_cp_list
418 *
419 * Find all the written-back checkpoint buffers in the given list and
420 * release them. If 'destroy' is set, clean all buffers unconditionally.
421 *
422 * Called with j_list_lock held.
423 * Returns 1 if we freed the transaction, 0 otherwise.
424 */
425static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy)
426{
427 struct journal_head *last_jh;
428 struct journal_head *next_jh = jh;
429 int ret;
430
431 if (!jh)
432 return 0;
433
434 last_jh = jh->b_cpprev;
435 do {
436 jh = next_jh;
437 next_jh = jh->b_cpnext;
438 if (!destroy)
439 ret = __try_to_free_cp_buf(jh);
440 else
441 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
442 if (!ret)
443 return 0;
444 if (ret == 2)
445 return 1;
446 /*
447 * This function only frees up some memory
448 * if possible so we dont have an obligation
449 * to finish processing. Bail out if preemption
450 * requested:
451 */
452 if (need_resched())
453 return 0;
454 } while (jh != last_jh);
455
456 return 0;
457}
458
459/*
460 * journal_clean_checkpoint_list
461 *
462 * Find all the written-back checkpoint buffers in the journal and release them.
463 * If 'destroy' is set, release all buffers unconditionally.
464 *
465 * Called with j_list_lock held.
466 */
467void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
468{
469 transaction_t *transaction, *last_transaction, *next_transaction;
470 int ret;
471
472 transaction = journal->j_checkpoint_transactions;
473 if (!transaction)
474 return;
475
476 last_transaction = transaction->t_cpprev;
477 next_transaction = transaction;
478 do {
479 transaction = next_transaction;
480 next_transaction = transaction->t_cpnext;
481 ret = journal_clean_one_cp_list(transaction->t_checkpoint_list,
482 destroy);
483 /*
484 * This function only frees up some memory if possible so we
485 * dont have an obligation to finish processing. Bail out if
486 * preemption requested:
487 */
488 if (need_resched())
489 return;
490 if (ret)
491 continue;
492 /*
493 * It is essential that we are as careful as in the case of
494 * t_checkpoint_list with removing the buffer from the list as
495 * we can possibly see not yet submitted buffers on io_list
496 */
497 ret = journal_clean_one_cp_list(transaction->
498 t_checkpoint_io_list, destroy);
499 if (need_resched())
500 return;
501 /*
502 * Stop scanning if we couldn't free the transaction. This
503 * avoids pointless scanning of transactions which still
504 * weren't checkpointed.
505 */
506 if (!ret)
507 return;
508 } while (transaction != last_transaction);
509}
510
511/*
512 * Remove buffers from all checkpoint lists as journal is aborted and we just
513 * need to free memory
514 */
515void jbd2_journal_destroy_checkpoint(journal_t *journal)
516{
517 /*
518 * We loop because __jbd2_journal_clean_checkpoint_list() may abort
519 * early due to a need of rescheduling.
520 */
521 while (1) {
522 spin_lock(&journal->j_list_lock);
523 if (!journal->j_checkpoint_transactions) {
524 spin_unlock(&journal->j_list_lock);
525 break;
526 }
527 __jbd2_journal_clean_checkpoint_list(journal, true);
528 spin_unlock(&journal->j_list_lock);
529 cond_resched();
530 }
531}
532
533/*
534 * journal_remove_checkpoint: called after a buffer has been committed
535 * to disk (either by being write-back flushed to disk, or being
536 * committed to the log).
537 *
538 * We cannot safely clean a transaction out of the log until all of the
539 * buffer updates committed in that transaction have safely been stored
540 * elsewhere on disk. To achieve this, all of the buffers in a
541 * transaction need to be maintained on the transaction's checkpoint
542 * lists until they have been rewritten, at which point this function is
543 * called to remove the buffer from the existing transaction's
544 * checkpoint lists.
545 *
546 * The function returns 1 if it frees the transaction, 0 otherwise.
547 * The function can free jh and bh.
548 *
549 * This function is called with j_list_lock held.
550 */
551int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
552{
553 struct transaction_chp_stats_s *stats;
554 transaction_t *transaction;
555 journal_t *journal;
556 int ret = 0;
557
558 JBUFFER_TRACE(jh, "entry");
559
560 if ((transaction = jh->b_cp_transaction) == NULL) {
561 JBUFFER_TRACE(jh, "not on transaction");
562 goto out;
563 }
564 journal = transaction->t_journal;
565
566 JBUFFER_TRACE(jh, "removing from transaction");
567 __buffer_unlink(jh);
568 jh->b_cp_transaction = NULL;
569 jbd2_journal_put_journal_head(jh);
570
571 if (transaction->t_checkpoint_list != NULL ||
572 transaction->t_checkpoint_io_list != NULL)
573 goto out;
574
575 /*
576 * There is one special case to worry about: if we have just pulled the
577 * buffer off a running or committing transaction's checkpoing list,
578 * then even if the checkpoint list is empty, the transaction obviously
579 * cannot be dropped!
580 *
581 * The locking here around t_state is a bit sleazy.
582 * See the comment at the end of jbd2_journal_commit_transaction().
583 */
584 if (transaction->t_state != T_FINISHED)
585 goto out;
586
587 /* OK, that was the last buffer for the transaction: we can now
588 safely remove this transaction from the log */
589 stats = &transaction->t_chp_stats;
590 if (stats->cs_chp_time)
591 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
592 jiffies);
593 trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
594 transaction->t_tid, stats);
595
596 __jbd2_journal_drop_transaction(journal, transaction);
597 jbd2_journal_free_transaction(transaction);
598 ret = 1;
599out:
600 return ret;
601}
602
603/*
604 * journal_insert_checkpoint: put a committed buffer onto a checkpoint
605 * list so that we know when it is safe to clean the transaction out of
606 * the log.
607 *
608 * Called with the journal locked.
609 * Called with j_list_lock held.
610 */
611void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
612 transaction_t *transaction)
613{
614 JBUFFER_TRACE(jh, "entry");
615 J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
616 J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
617
618 /* Get reference for checkpointing transaction */
619 jbd2_journal_grab_journal_head(jh2bh(jh));
620 jh->b_cp_transaction = transaction;
621
622 if (!transaction->t_checkpoint_list) {
623 jh->b_cpnext = jh->b_cpprev = jh;
624 } else {
625 jh->b_cpnext = transaction->t_checkpoint_list;
626 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
627 jh->b_cpprev->b_cpnext = jh;
628 jh->b_cpnext->b_cpprev = jh;
629 }
630 transaction->t_checkpoint_list = jh;
631}
632
633/*
634 * We've finished with this transaction structure: adios...
635 *
636 * The transaction must have no links except for the checkpoint by this
637 * point.
638 *
639 * Called with the journal locked.
640 * Called with j_list_lock held.
641 */
642
643void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
644{
645 assert_spin_locked(&journal->j_list_lock);
646 if (transaction->t_cpnext) {
647 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
648 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
649 if (journal->j_checkpoint_transactions == transaction)
650 journal->j_checkpoint_transactions =
651 transaction->t_cpnext;
652 if (journal->j_checkpoint_transactions == transaction)
653 journal->j_checkpoint_transactions = NULL;
654 }
655
656 J_ASSERT(transaction->t_state == T_FINISHED);
657 J_ASSERT(transaction->t_buffers == NULL);
658 J_ASSERT(transaction->t_forget == NULL);
659 J_ASSERT(transaction->t_shadow_list == NULL);
660 J_ASSERT(transaction->t_checkpoint_list == NULL);
661 J_ASSERT(transaction->t_checkpoint_io_list == NULL);
662 J_ASSERT(atomic_read(&transaction->t_updates) == 0);
663 J_ASSERT(journal->j_committing_transaction != transaction);
664 J_ASSERT(journal->j_running_transaction != transaction);
665
666 trace_jbd2_drop_transaction(journal, transaction);
667
668 jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
669}
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}