timerfd: support CLOCK_BOOTTIME clock
[linux-3.10.git] / fs / jbd / checkpoint.c
1 /*
2  * linux/fs/jbd/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/jbd.h>
23 #include <linux/errno.h>
24 #include <linux/slab.h>
25 #include <linux/blkdev.h>
26 #include <trace/events/jbd.h>
27
28 /*
29  * Unlink a buffer from a transaction checkpoint list.
30  *
31  * Called with j_list_lock held.
32  */
33 static 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  */
51 static 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  */
68 static 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  */
93 static 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 = __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  * __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  */
122 void __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 (__log_space_left(journal) < nblocks) {
129                 if (journal->j_flags & JFS_ABORT)
130                         return;
131                 spin_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                 spin_lock(&journal->j_state_lock);
146                 spin_lock(&journal->j_list_lock);
147                 nblocks = jbd_space_needed(journal);
148                 space_left = __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                         spin_unlock(&journal->j_state_lock);
157                         if (chkpt) {
158                                 log_do_checkpoint(journal);
159                         } else if (cleanup_journal_tail(journal) == 0) {
160                                 /* We were able to recover space; yay! */
161                                 ;
162                         } else if (tid) {
163                                 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\n", __func__);
170                                 WARN_ON(1);
171                                 journal_abort(journal, 0);
172                         }
173                         spin_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
181 /*
182  * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
183  * The caller must restart a list walk.  Wait for someone else to run
184  * jbd_unlock_bh_state().
185  */
186 static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
187         __releases(journal->j_list_lock)
188 {
189         get_bh(bh);
190         spin_unlock(&journal->j_list_lock);
191         jbd_lock_bh_state(bh);
192         jbd_unlock_bh_state(bh);
193         put_bh(bh);
194 }
195
196 /*
197  * Clean up transaction's list of buffers submitted for io.
198  * We wait for any pending IO to complete and remove any clean
199  * buffers. Note that we take the buffers in the opposite ordering
200  * from the one in which they were submitted for IO.
201  *
202  * Return 0 on success, and return <0 if some buffers have failed
203  * to be written out.
204  *
205  * Called with j_list_lock held.
206  */
207 static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
208 {
209         struct journal_head *jh;
210         struct buffer_head *bh;
211         tid_t this_tid;
212         int released = 0;
213         int ret = 0;
214
215         this_tid = transaction->t_tid;
216 restart:
217         /* Did somebody clean up the transaction in the meanwhile? */
218         if (journal->j_checkpoint_transactions != transaction ||
219                         transaction->t_tid != this_tid)
220                 return ret;
221         while (!released && transaction->t_checkpoint_io_list) {
222                 jh = transaction->t_checkpoint_io_list;
223                 bh = jh2bh(jh);
224                 if (!jbd_trylock_bh_state(bh)) {
225                         jbd_sync_bh(journal, bh);
226                         spin_lock(&journal->j_list_lock);
227                         goto restart;
228                 }
229                 get_bh(bh);
230                 if (buffer_locked(bh)) {
231                         spin_unlock(&journal->j_list_lock);
232                         jbd_unlock_bh_state(bh);
233                         wait_on_buffer(bh);
234                         /* the journal_head may have gone by now */
235                         BUFFER_TRACE(bh, "brelse");
236                         __brelse(bh);
237                         spin_lock(&journal->j_list_lock);
238                         goto restart;
239                 }
240                 if (unlikely(buffer_write_io_error(bh)))
241                         ret = -EIO;
242
243                 /*
244                  * Now in whatever state the buffer currently is, we know that
245                  * it has been written out and so we can drop it from the list
246                  */
247                 released = __journal_remove_checkpoint(jh);
248                 jbd_unlock_bh_state(bh);
249                 __brelse(bh);
250         }
251
252         return ret;
253 }
254
255 #define NR_BATCH        64
256
257 static void
258 __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
259 {
260         int i;
261         struct blk_plug plug;
262
263         blk_start_plug(&plug);
264         for (i = 0; i < *batch_count; i++)
265                 write_dirty_buffer(bhs[i], WRITE_SYNC);
266         blk_finish_plug(&plug);
267
268         for (i = 0; i < *batch_count; i++) {
269                 struct buffer_head *bh = bhs[i];
270                 clear_buffer_jwrite(bh);
271                 BUFFER_TRACE(bh, "brelse");
272                 __brelse(bh);
273         }
274         *batch_count = 0;
275 }
276
277 /*
278  * Try to flush one buffer from the checkpoint list to disk.
279  *
280  * Return 1 if something happened which requires us to abort the current
281  * scan of the checkpoint list.  Return <0 if the buffer has failed to
282  * be written out.
283  *
284  * Called with j_list_lock held and drops it if 1 is returned
285  * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
286  */
287 static int __process_buffer(journal_t *journal, struct journal_head *jh,
288                         struct buffer_head **bhs, int *batch_count)
289 {
290         struct buffer_head *bh = jh2bh(jh);
291         int ret = 0;
292
293         if (buffer_locked(bh)) {
294                 get_bh(bh);
295                 spin_unlock(&journal->j_list_lock);
296                 jbd_unlock_bh_state(bh);
297                 wait_on_buffer(bh);
298                 /* the journal_head may have gone by now */
299                 BUFFER_TRACE(bh, "brelse");
300                 __brelse(bh);
301                 ret = 1;
302         } else if (jh->b_transaction != NULL) {
303                 transaction_t *t = jh->b_transaction;
304                 tid_t tid = t->t_tid;
305
306                 spin_unlock(&journal->j_list_lock);
307                 jbd_unlock_bh_state(bh);
308                 log_start_commit(journal, tid);
309                 log_wait_commit(journal, tid);
310                 ret = 1;
311         } else if (!buffer_dirty(bh)) {
312                 ret = 1;
313                 if (unlikely(buffer_write_io_error(bh)))
314                         ret = -EIO;
315                 get_bh(bh);
316                 J_ASSERT_JH(jh, !buffer_jbddirty(bh));
317                 BUFFER_TRACE(bh, "remove from checkpoint");
318                 __journal_remove_checkpoint(jh);
319                 spin_unlock(&journal->j_list_lock);
320                 jbd_unlock_bh_state(bh);
321                 __brelse(bh);
322         } else {
323                 /*
324                  * Important: we are about to write the buffer, and
325                  * possibly block, while still holding the journal lock.
326                  * We cannot afford to let the transaction logic start
327                  * messing around with this buffer before we write it to
328                  * disk, as that would break recoverability.
329                  */
330                 BUFFER_TRACE(bh, "queue");
331                 get_bh(bh);
332                 J_ASSERT_BH(bh, !buffer_jwrite(bh));
333                 set_buffer_jwrite(bh);
334                 bhs[*batch_count] = bh;
335                 __buffer_relink_io(jh);
336                 jbd_unlock_bh_state(bh);
337                 (*batch_count)++;
338                 if (*batch_count == NR_BATCH) {
339                         spin_unlock(&journal->j_list_lock);
340                         __flush_batch(journal, bhs, batch_count);
341                         ret = 1;
342                 }
343         }
344         return ret;
345 }
346
347 /*
348  * Perform an actual checkpoint. We take the first transaction on the
349  * list of transactions to be checkpointed and send all its buffers
350  * to disk. We submit larger chunks of data at once.
351  *
352  * The journal should be locked before calling this function.
353  * Called with j_checkpoint_mutex held.
354  */
355 int log_do_checkpoint(journal_t *journal)
356 {
357         transaction_t *transaction;
358         tid_t this_tid;
359         int result;
360
361         jbd_debug(1, "Start checkpoint\n");
362
363         /*
364          * First thing: if there are any transactions in the log which
365          * don't need checkpointing, just eliminate them from the
366          * journal straight away.
367          */
368         result = cleanup_journal_tail(journal);
369         trace_jbd_checkpoint(journal, result);
370         jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
371         if (result <= 0)
372                 return result;
373
374         /*
375          * OK, we need to start writing disk blocks.  Take one transaction
376          * and write it.
377          */
378         result = 0;
379         spin_lock(&journal->j_list_lock);
380         if (!journal->j_checkpoint_transactions)
381                 goto out;
382         transaction = journal->j_checkpoint_transactions;
383         this_tid = transaction->t_tid;
384 restart:
385         /*
386          * If someone cleaned up this transaction while we slept, we're
387          * done (maybe it's a new transaction, but it fell at the same
388          * address).
389          */
390         if (journal->j_checkpoint_transactions == transaction &&
391                         transaction->t_tid == this_tid) {
392                 int batch_count = 0;
393                 struct buffer_head *bhs[NR_BATCH];
394                 struct journal_head *jh;
395                 int retry = 0, err;
396
397                 while (!retry && transaction->t_checkpoint_list) {
398                         struct buffer_head *bh;
399
400                         jh = transaction->t_checkpoint_list;
401                         bh = jh2bh(jh);
402                         if (!jbd_trylock_bh_state(bh)) {
403                                 jbd_sync_bh(journal, bh);
404                                 retry = 1;
405                                 break;
406                         }
407                         retry = __process_buffer(journal, jh, bhs,&batch_count);
408                         if (retry < 0 && !result)
409                                 result = retry;
410                         if (!retry && (need_resched() ||
411                                 spin_needbreak(&journal->j_list_lock))) {
412                                 spin_unlock(&journal->j_list_lock);
413                                 retry = 1;
414                                 break;
415                         }
416                 }
417
418                 if (batch_count) {
419                         if (!retry) {
420                                 spin_unlock(&journal->j_list_lock);
421                                 retry = 1;
422                         }
423                         __flush_batch(journal, bhs, &batch_count);
424                 }
425
426                 if (retry) {
427                         spin_lock(&journal->j_list_lock);
428                         goto restart;
429                 }
430                 /*
431                  * Now we have cleaned up the first transaction's checkpoint
432                  * list. Let's clean up the second one
433                  */
434                 err = __wait_cp_io(journal, transaction);
435                 if (!result)
436                         result = err;
437         }
438 out:
439         spin_unlock(&journal->j_list_lock);
440         if (result < 0)
441                 journal_abort(journal, result);
442         else
443                 result = cleanup_journal_tail(journal);
444
445         return (result < 0) ? result : 0;
446 }
447
448 /*
449  * Check the list of checkpoint transactions for the journal to see if
450  * we have already got rid of any since the last update of the log tail
451  * in the journal superblock.  If so, we can instantly roll the
452  * superblock forward to remove those transactions from the log.
453  *
454  * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
455  *
456  * This is the only part of the journaling code which really needs to be
457  * aware of transaction aborts.  Checkpointing involves writing to the
458  * main filesystem area rather than to the journal, so it can proceed
459  * even in abort state, but we must not update the super block if
460  * checkpointing may have failed.  Otherwise, we would lose some metadata
461  * buffers which should be written-back to the filesystem.
462  */
463
464 int cleanup_journal_tail(journal_t *journal)
465 {
466         transaction_t * transaction;
467         tid_t           first_tid;
468         unsigned int    blocknr, freed;
469
470         if (is_journal_aborted(journal))
471                 return 1;
472
473         /*
474          * OK, work out the oldest transaction remaining in the log, and
475          * the log block it starts at.
476          *
477          * If the log is now empty, we need to work out which is the
478          * next transaction ID we will write, and where it will
479          * start.
480          */
481         spin_lock(&journal->j_state_lock);
482         spin_lock(&journal->j_list_lock);
483         transaction = journal->j_checkpoint_transactions;
484         if (transaction) {
485                 first_tid = transaction->t_tid;
486                 blocknr = transaction->t_log_start;
487         } else if ((transaction = journal->j_committing_transaction) != NULL) {
488                 first_tid = transaction->t_tid;
489                 blocknr = transaction->t_log_start;
490         } else if ((transaction = journal->j_running_transaction) != NULL) {
491                 first_tid = transaction->t_tid;
492                 blocknr = journal->j_head;
493         } else {
494                 first_tid = journal->j_transaction_sequence;
495                 blocknr = journal->j_head;
496         }
497         spin_unlock(&journal->j_list_lock);
498         J_ASSERT(blocknr != 0);
499
500         /* If the oldest pinned transaction is at the tail of the log
501            already then there's not much we can do right now. */
502         if (journal->j_tail_sequence == first_tid) {
503                 spin_unlock(&journal->j_state_lock);
504                 return 1;
505         }
506         spin_unlock(&journal->j_state_lock);
507
508         /*
509          * We need to make sure that any blocks that were recently written out
510          * --- perhaps by log_do_checkpoint() --- are flushed out before we
511          * drop the transactions from the journal. Similarly we need to be sure
512          * superblock makes it to disk before next transaction starts reusing
513          * freed space (otherwise we could replay some blocks of the new
514          * transaction thinking they belong to the old one). So we use
515          * WRITE_FLUSH_FUA. It's unlikely this will be necessary, especially
516          * with an appropriately sized journal, but we need this to guarantee
517          * correctness.  Fortunately cleanup_journal_tail() doesn't get called
518          * all that often.
519          */
520         journal_update_sb_log_tail(journal, first_tid, blocknr,
521                                    WRITE_FLUSH_FUA);
522
523         spin_lock(&journal->j_state_lock);
524         /* OK, update the superblock to recover the freed space.
525          * Physical blocks come first: have we wrapped beyond the end of
526          * the log?  */
527         freed = blocknr - journal->j_tail;
528         if (blocknr < journal->j_tail)
529                 freed = freed + journal->j_last - journal->j_first;
530
531         trace_jbd_cleanup_journal_tail(journal, first_tid, blocknr, freed);
532         jbd_debug(1,
533                   "Cleaning journal tail from %d to %d (offset %u), "
534                   "freeing %u\n",
535                   journal->j_tail_sequence, first_tid, blocknr, freed);
536
537         journal->j_free += freed;
538         journal->j_tail_sequence = first_tid;
539         journal->j_tail = blocknr;
540         spin_unlock(&journal->j_state_lock);
541         return 0;
542 }
543
544
545 /* Checkpoint list management */
546
547 /*
548  * journal_clean_one_cp_list
549  *
550  * Find all the written-back checkpoint buffers in the given list and release
551  * them.
552  *
553  * Called with j_list_lock held.
554  * Returns number of buffers reaped (for debug)
555  */
556
557 static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
558 {
559         struct journal_head *last_jh;
560         struct journal_head *next_jh = jh;
561         int ret, freed = 0;
562
563         *released = 0;
564         if (!jh)
565                 return 0;
566
567         last_jh = jh->b_cpprev;
568         do {
569                 jh = next_jh;
570                 next_jh = jh->b_cpnext;
571                 /* Use trylock because of the ranking */
572                 if (jbd_trylock_bh_state(jh2bh(jh))) {
573                         ret = __try_to_free_cp_buf(jh);
574                         if (ret) {
575                                 freed++;
576                                 if (ret == 2) {
577                                         *released = 1;
578                                         return freed;
579                                 }
580                         }
581                 }
582                 /*
583                  * This function only frees up some memory
584                  * if possible so we dont have an obligation
585                  * to finish processing. Bail out if preemption
586                  * requested:
587                  */
588                 if (need_resched())
589                         return freed;
590         } while (jh != last_jh);
591
592         return freed;
593 }
594
595 /*
596  * journal_clean_checkpoint_list
597  *
598  * Find all the written-back checkpoint buffers in the journal and release them.
599  *
600  * Called with the journal locked.
601  * Called with j_list_lock held.
602  * Returns number of buffers reaped (for debug)
603  */
604
605 int __journal_clean_checkpoint_list(journal_t *journal)
606 {
607         transaction_t *transaction, *last_transaction, *next_transaction;
608         int ret = 0;
609         int released;
610
611         transaction = journal->j_checkpoint_transactions;
612         if (!transaction)
613                 goto out;
614
615         last_transaction = transaction->t_cpprev;
616         next_transaction = transaction;
617         do {
618                 transaction = next_transaction;
619                 next_transaction = transaction->t_cpnext;
620                 ret += journal_clean_one_cp_list(transaction->
621                                 t_checkpoint_list, &released);
622                 /*
623                  * This function only frees up some memory if possible so we
624                  * dont have an obligation to finish processing. Bail out if
625                  * preemption requested:
626                  */
627                 if (need_resched())
628                         goto out;
629                 if (released)
630                         continue;
631                 /*
632                  * It is essential that we are as careful as in the case of
633                  * t_checkpoint_list with removing the buffer from the list as
634                  * we can possibly see not yet submitted buffers on io_list
635                  */
636                 ret += journal_clean_one_cp_list(transaction->
637                                 t_checkpoint_io_list, &released);
638                 if (need_resched())
639                         goto out;
640         } while (transaction != last_transaction);
641 out:
642         return ret;
643 }
644
645 /*
646  * journal_remove_checkpoint: called after a buffer has been committed
647  * to disk (either by being write-back flushed to disk, or being
648  * committed to the log).
649  *
650  * We cannot safely clean a transaction out of the log until all of the
651  * buffer updates committed in that transaction have safely been stored
652  * elsewhere on disk.  To achieve this, all of the buffers in a
653  * transaction need to be maintained on the transaction's checkpoint
654  * lists until they have been rewritten, at which point this function is
655  * called to remove the buffer from the existing transaction's
656  * checkpoint lists.
657  *
658  * The function returns 1 if it frees the transaction, 0 otherwise.
659  * The function can free jh and bh.
660  *
661  * This function is called with j_list_lock held.
662  * This function is called with jbd_lock_bh_state(jh2bh(jh))
663  */
664
665 int __journal_remove_checkpoint(struct journal_head *jh)
666 {
667         transaction_t *transaction;
668         journal_t *journal;
669         int ret = 0;
670
671         JBUFFER_TRACE(jh, "entry");
672
673         if ((transaction = jh->b_cp_transaction) == NULL) {
674                 JBUFFER_TRACE(jh, "not on transaction");
675                 goto out;
676         }
677         journal = transaction->t_journal;
678
679         JBUFFER_TRACE(jh, "removing from transaction");
680         __buffer_unlink(jh);
681         jh->b_cp_transaction = NULL;
682         journal_put_journal_head(jh);
683
684         if (transaction->t_checkpoint_list != NULL ||
685             transaction->t_checkpoint_io_list != NULL)
686                 goto out;
687
688         /*
689          * There is one special case to worry about: if we have just pulled the
690          * buffer off a running or committing transaction's checkpoing list,
691          * then even if the checkpoint list is empty, the transaction obviously
692          * cannot be dropped!
693          *
694          * The locking here around t_state is a bit sleazy.
695          * See the comment at the end of journal_commit_transaction().
696          */
697         if (transaction->t_state != T_FINISHED)
698                 goto out;
699
700         /* OK, that was the last buffer for the transaction: we can now
701            safely remove this transaction from the log */
702
703         __journal_drop_transaction(journal, transaction);
704
705         /* Just in case anybody was waiting for more transactions to be
706            checkpointed... */
707         wake_up(&journal->j_wait_logspace);
708         ret = 1;
709 out:
710         return ret;
711 }
712
713 /*
714  * journal_insert_checkpoint: put a committed buffer onto a checkpoint
715  * list so that we know when it is safe to clean the transaction out of
716  * the log.
717  *
718  * Called with the journal locked.
719  * Called with j_list_lock held.
720  */
721 void __journal_insert_checkpoint(struct journal_head *jh,
722                                transaction_t *transaction)
723 {
724         JBUFFER_TRACE(jh, "entry");
725         J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
726         J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
727
728         /* Get reference for checkpointing transaction */
729         journal_grab_journal_head(jh2bh(jh));
730         jh->b_cp_transaction = transaction;
731
732         if (!transaction->t_checkpoint_list) {
733                 jh->b_cpnext = jh->b_cpprev = jh;
734         } else {
735                 jh->b_cpnext = transaction->t_checkpoint_list;
736                 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
737                 jh->b_cpprev->b_cpnext = jh;
738                 jh->b_cpnext->b_cpprev = jh;
739         }
740         transaction->t_checkpoint_list = jh;
741 }
742
743 /*
744  * We've finished with this transaction structure: adios...
745  *
746  * The transaction must have no links except for the checkpoint by this
747  * point.
748  *
749  * Called with the journal locked.
750  * Called with j_list_lock held.
751  */
752
753 void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)
754 {
755         assert_spin_locked(&journal->j_list_lock);
756         if (transaction->t_cpnext) {
757                 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
758                 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
759                 if (journal->j_checkpoint_transactions == transaction)
760                         journal->j_checkpoint_transactions =
761                                 transaction->t_cpnext;
762                 if (journal->j_checkpoint_transactions == transaction)
763                         journal->j_checkpoint_transactions = NULL;
764         }
765
766         J_ASSERT(transaction->t_state == T_FINISHED);
767         J_ASSERT(transaction->t_buffers == NULL);
768         J_ASSERT(transaction->t_sync_datalist == NULL);
769         J_ASSERT(transaction->t_forget == NULL);
770         J_ASSERT(transaction->t_iobuf_list == NULL);
771         J_ASSERT(transaction->t_shadow_list == NULL);
772         J_ASSERT(transaction->t_log_list == NULL);
773         J_ASSERT(transaction->t_checkpoint_list == NULL);
774         J_ASSERT(transaction->t_checkpoint_io_list == NULL);
775         J_ASSERT(transaction->t_updates == 0);
776         J_ASSERT(journal->j_committing_transaction != transaction);
777         J_ASSERT(journal->j_running_transaction != transaction);
778
779         trace_jbd_drop_transaction(journal, transaction);
780         jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
781         kfree(transaction);
782 }