fs/sysv: dereferencing ERR_PTR()
[linux-2.6-block.git] / fs / jbd / checkpoint.c
CommitLineData
1da177e4 1/*
58862699 2 * linux/fs/jbd/checkpoint.c
ae6ddcc5 3 *
1da177e4
LT
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 *
ae6ddcc5
MC
12 * Checkpoint routines for the generic filesystem journaling code.
13 * Part of the ext2fs journaling system.
1da177e4
LT
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
26/*
78ce89c9 27 * Unlink a buffer from a transaction checkpoint list.
1da177e4
LT
28 *
29 * Called with j_list_lock held.
30 */
78ce89c9 31static inline void __buffer_unlink_first(struct journal_head *jh)
1da177e4 32{
78ce89c9 33 transaction_t *transaction = jh->b_cp_transaction;
1da177e4
LT
34
35 jh->b_cpnext->b_cpprev = jh->b_cpprev;
36 jh->b_cpprev->b_cpnext = jh->b_cpnext;
78ce89c9 37 if (transaction->t_checkpoint_list == jh) {
1da177e4 38 transaction->t_checkpoint_list = jh->b_cpnext;
78ce89c9
JK
39 if (transaction->t_checkpoint_list == jh)
40 transaction->t_checkpoint_list = NULL;
41 }
42}
43
44/*
45 * Unlink a buffer from a transaction checkpoint(io) list.
46 *
47 * Called with j_list_lock held.
48 */
49static inline void __buffer_unlink(struct journal_head *jh)
50{
51 transaction_t *transaction = jh->b_cp_transaction;
52
53 __buffer_unlink_first(jh);
54 if (transaction->t_checkpoint_io_list == jh) {
55 transaction->t_checkpoint_io_list = jh->b_cpnext;
56 if (transaction->t_checkpoint_io_list == jh)
57 transaction->t_checkpoint_io_list = NULL;
58 }
59}
60
61/*
62 * Move a buffer from the checkpoint list to the checkpoint io list
63 *
64 * Called with j_list_lock held
65 */
66static inline void __buffer_relink_io(struct journal_head *jh)
67{
68 transaction_t *transaction = jh->b_cp_transaction;
69
70 __buffer_unlink_first(jh);
71
72 if (!transaction->t_checkpoint_io_list) {
73 jh->b_cpnext = jh->b_cpprev = jh;
74 } else {
75 jh->b_cpnext = transaction->t_checkpoint_io_list;
76 jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
77 jh->b_cpprev->b_cpnext = jh;
78 jh->b_cpnext->b_cpprev = jh;
79 }
80 transaction->t_checkpoint_io_list = jh;
1da177e4
LT
81}
82
83/*
84 * Try to release a checkpointed buffer from its transaction.
78ce89c9
JK
85 * Returns 1 if we released it and 2 if we also released the
86 * whole transaction.
87 *
1da177e4
LT
88 * Requires j_list_lock
89 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
90 */
91static int __try_to_free_cp_buf(struct journal_head *jh)
92{
93 int ret = 0;
94 struct buffer_head *bh = jh2bh(jh);
95
4afe9785 96 if (jh->b_jlist == BJ_None && !buffer_locked(bh) &&
9f818b4a 97 !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
1da177e4 98 JBUFFER_TRACE(jh, "remove from checkpoint list");
78ce89c9 99 ret = __journal_remove_checkpoint(jh) + 1;
1da177e4
LT
100 jbd_unlock_bh_state(bh);
101 journal_remove_journal_head(bh);
102 BUFFER_TRACE(bh, "release");
103 __brelse(bh);
1da177e4
LT
104 } else {
105 jbd_unlock_bh_state(bh);
106 }
107 return ret;
108}
109
110/*
111 * __log_wait_for_space: wait until there is space in the journal.
112 *
113 * Called under j-state_lock *only*. It will be unlocked if we have to wait
114 * for a checkpoint to free up some space in the log.
115 */
116void __log_wait_for_space(journal_t *journal)
117{
e219cca0 118 int nblocks, space_left;
1da177e4
LT
119 assert_spin_locked(&journal->j_state_lock);
120
121 nblocks = jbd_space_needed(journal);
122 while (__log_space_left(journal) < nblocks) {
123 if (journal->j_flags & JFS_ABORT)
124 return;
125 spin_unlock(&journal->j_state_lock);
2c68ee75 126 mutex_lock(&journal->j_checkpoint_mutex);
1da177e4
LT
127
128 /*
129 * Test again, another process may have checkpointed while we
be07c4ed 130 * were waiting for the checkpoint lock. If there are no
e219cca0
TT
131 * transactions ready to be checkpointed, try to recover
132 * journal space by calling cleanup_journal_tail(), and if
133 * that doesn't work, by waiting for the currently committing
134 * transaction to complete. If there is absolutely no way
135 * to make progress, this is either a BUG or corrupted
136 * filesystem, so abort the journal and leave a stack
137 * trace for forensic evidence.
1da177e4
LT
138 */
139 spin_lock(&journal->j_state_lock);
be07c4ed 140 spin_lock(&journal->j_list_lock);
1da177e4 141 nblocks = jbd_space_needed(journal);
e219cca0
TT
142 space_left = __log_space_left(journal);
143 if (space_left < nblocks) {
be07c4ed 144 int chkpt = journal->j_checkpoint_transactions != NULL;
e219cca0 145 tid_t tid = 0;
be07c4ed 146
e219cca0
TT
147 if (journal->j_committing_transaction)
148 tid = journal->j_committing_transaction->t_tid;
be07c4ed 149 spin_unlock(&journal->j_list_lock);
1da177e4 150 spin_unlock(&journal->j_state_lock);
be07c4ed
DG
151 if (chkpt) {
152 log_do_checkpoint(journal);
e219cca0
TT
153 } else if (cleanup_journal_tail(journal) == 0) {
154 /* We were able to recover space; yay! */
155 ;
156 } else if (tid) {
157 log_wait_commit(journal, tid);
be07c4ed 158 } else {
e219cca0
TT
159 printk(KERN_ERR "%s: needed %d blocks and "
160 "only had %d space available\n",
161 __func__, nblocks, space_left);
162 printk(KERN_ERR "%s: no way to get more "
163 "journal space\n", __func__);
164 WARN_ON(1);
be07c4ed
DG
165 journal_abort(journal, 0);
166 }
1da177e4 167 spin_lock(&journal->j_state_lock);
be07c4ed
DG
168 } else {
169 spin_unlock(&journal->j_list_lock);
1da177e4 170 }
2c68ee75 171 mutex_unlock(&journal->j_checkpoint_mutex);
1da177e4
LT
172 }
173}
174
175/*
176 * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
177 * The caller must restart a list walk. Wait for someone else to run
178 * jbd_unlock_bh_state().
179 */
180static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
e7ab8d65 181 __releases(journal->j_list_lock)
1da177e4
LT
182{
183 get_bh(bh);
184 spin_unlock(&journal->j_list_lock);
185 jbd_lock_bh_state(bh);
186 jbd_unlock_bh_state(bh);
187 put_bh(bh);
188}
189
190/*
78ce89c9
JK
191 * Clean up transaction's list of buffers submitted for io.
192 * We wait for any pending IO to complete and remove any clean
193 * buffers. Note that we take the buffers in the opposite ordering
194 * from the one in which they were submitted for IO.
1da177e4 195 *
4afe9785
HK
196 * Return 0 on success, and return <0 if some buffers have failed
197 * to be written out.
198 *
1da177e4
LT
199 * Called with j_list_lock held.
200 */
4afe9785 201static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
1da177e4 202{
78ce89c9 203 struct journal_head *jh;
1da177e4 204 struct buffer_head *bh;
78ce89c9
JK
205 tid_t this_tid;
206 int released = 0;
4afe9785 207 int ret = 0;
78ce89c9
JK
208
209 this_tid = transaction->t_tid;
210restart:
211 /* Did somebody clean up the transaction in the meanwhile? */
212 if (journal->j_checkpoint_transactions != transaction ||
213 transaction->t_tid != this_tid)
4afe9785 214 return ret;
78ce89c9
JK
215 while (!released && transaction->t_checkpoint_io_list) {
216 jh = transaction->t_checkpoint_io_list;
1da177e4 217 bh = jh2bh(jh);
78ce89c9
JK
218 if (!jbd_trylock_bh_state(bh)) {
219 jbd_sync_bh(journal, bh);
220 spin_lock(&journal->j_list_lock);
221 goto restart;
222 }
1da177e4
LT
223 if (buffer_locked(bh)) {
224 atomic_inc(&bh->b_count);
225 spin_unlock(&journal->j_list_lock);
78ce89c9 226 jbd_unlock_bh_state(bh);
1da177e4
LT
227 wait_on_buffer(bh);
228 /* the journal_head may have gone by now */
229 BUFFER_TRACE(bh, "brelse");
230 __brelse(bh);
78ce89c9
JK
231 spin_lock(&journal->j_list_lock);
232 goto restart;
1da177e4 233 }
9f818b4a 234 if (unlikely(buffer_write_io_error(bh)))
4afe9785
HK
235 ret = -EIO;
236
1da177e4 237 /*
78ce89c9
JK
238 * Now in whatever state the buffer currently is, we know that
239 * it has been written out and so we can drop it from the list
1da177e4 240 */
78ce89c9
JK
241 released = __journal_remove_checkpoint(jh);
242 jbd_unlock_bh_state(bh);
243 journal_remove_journal_head(bh);
244 __brelse(bh);
245 }
4afe9785
HK
246
247 return ret;
1da177e4
LT
248}
249
250#define NR_BATCH 64
251
252static void
253__flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
254{
255 int i;
256
26707699 257 ll_rw_block(SWRITE, *batch_count, bhs);
1da177e4
LT
258 for (i = 0; i < *batch_count; i++) {
259 struct buffer_head *bh = bhs[i];
260 clear_buffer_jwrite(bh);
261 BUFFER_TRACE(bh, "brelse");
262 __brelse(bh);
263 }
264 *batch_count = 0;
265}
266
267/*
268 * Try to flush one buffer from the checkpoint list to disk.
269 *
270 * Return 1 if something happened which requires us to abort the current
4afe9785
HK
271 * scan of the checkpoint list. Return <0 if the buffer has failed to
272 * be written out.
1da177e4 273 *
78ce89c9 274 * Called with j_list_lock held and drops it if 1 is returned
1da177e4
LT
275 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
276 */
78ce89c9
JK
277static int __process_buffer(journal_t *journal, struct journal_head *jh,
278 struct buffer_head **bhs, int *batch_count)
1da177e4
LT
279{
280 struct buffer_head *bh = jh2bh(jh);
281 int ret = 0;
282
78ce89c9
JK
283 if (buffer_locked(bh)) {
284 atomic_inc(&bh->b_count);
285 spin_unlock(&journal->j_list_lock);
286 jbd_unlock_bh_state(bh);
287 wait_on_buffer(bh);
288 /* the journal_head may have gone by now */
289 BUFFER_TRACE(bh, "brelse");
290 __brelse(bh);
291 ret = 1;
292 } else if (jh->b_transaction != NULL) {
293 transaction_t *t = jh->b_transaction;
294 tid_t tid = t->t_tid;
1da177e4 295
78ce89c9
JK
296 spin_unlock(&journal->j_list_lock);
297 jbd_unlock_bh_state(bh);
298 log_start_commit(journal, tid);
299 log_wait_commit(journal, tid);
300 ret = 1;
301 } else if (!buffer_dirty(bh)) {
4afe9785 302 ret = 1;
9f818b4a 303 if (unlikely(buffer_write_io_error(bh)))
4afe9785 304 ret = -EIO;
78ce89c9
JK
305 J_ASSERT_JH(jh, !buffer_jbddirty(bh));
306 BUFFER_TRACE(bh, "remove from checkpoint");
307 __journal_remove_checkpoint(jh);
308 spin_unlock(&journal->j_list_lock);
309 jbd_unlock_bh_state(bh);
310 journal_remove_journal_head(bh);
311 __brelse(bh);
78ce89c9 312 } else {
1da177e4
LT
313 /*
314 * Important: we are about to write the buffer, and
315 * possibly block, while still holding the journal lock.
316 * We cannot afford to let the transaction logic start
317 * messing around with this buffer before we write it to
ae6ddcc5 318 * disk, as that would break recoverability.
1da177e4
LT
319 */
320 BUFFER_TRACE(bh, "queue");
321 get_bh(bh);
322 J_ASSERT_BH(bh, !buffer_jwrite(bh));
323 set_buffer_jwrite(bh);
324 bhs[*batch_count] = bh;
78ce89c9 325 __buffer_relink_io(jh);
1da177e4
LT
326 jbd_unlock_bh_state(bh);
327 (*batch_count)++;
328 if (*batch_count == NR_BATCH) {
78ce89c9 329 spin_unlock(&journal->j_list_lock);
1da177e4
LT
330 __flush_batch(journal, bhs, batch_count);
331 ret = 1;
332 }
1da177e4
LT
333 }
334 return ret;
335}
336
337/*
78ce89c9
JK
338 * Perform an actual checkpoint. We take the first transaction on the
339 * list of transactions to be checkpointed and send all its buffers
340 * to disk. We submit larger chunks of data at once.
ae6ddcc5 341 *
1da177e4 342 * The journal should be locked before calling this function.
4afe9785 343 * Called with j_checkpoint_mutex held.
1da177e4
LT
344 */
345int log_do_checkpoint(journal_t *journal)
346{
78ce89c9
JK
347 transaction_t *transaction;
348 tid_t this_tid;
1da177e4 349 int result;
1da177e4
LT
350
351 jbd_debug(1, "Start checkpoint\n");
352
ae6ddcc5 353 /*
1da177e4
LT
354 * First thing: if there are any transactions in the log which
355 * don't need checkpointing, just eliminate them from the
ae6ddcc5 356 * journal straight away.
1da177e4
LT
357 */
358 result = cleanup_journal_tail(journal);
359 jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
360 if (result <= 0)
361 return result;
362
363 /*
78ce89c9
JK
364 * OK, we need to start writing disk blocks. Take one transaction
365 * and write it.
1da177e4 366 */
4afe9785 367 result = 0;
78ce89c9
JK
368 spin_lock(&journal->j_list_lock);
369 if (!journal->j_checkpoint_transactions)
370 goto out;
371 transaction = journal->j_checkpoint_transactions;
372 this_tid = transaction->t_tid;
373restart:
1da177e4 374 /*
78ce89c9
JK
375 * If someone cleaned up this transaction while we slept, we're
376 * done (maybe it's a new transaction, but it fell at the same
377 * address).
1da177e4 378 */
78ce89c9
JK
379 if (journal->j_checkpoint_transactions == transaction &&
380 transaction->t_tid == this_tid) {
381 int batch_count = 0;
382 struct buffer_head *bhs[NR_BATCH];
383 struct journal_head *jh;
4afe9785 384 int retry = 0, err;
78ce89c9
JK
385
386 while (!retry && transaction->t_checkpoint_list) {
1da177e4
LT
387 struct buffer_head *bh;
388
78ce89c9 389 jh = transaction->t_checkpoint_list;
1da177e4
LT
390 bh = jh2bh(jh);
391 if (!jbd_trylock_bh_state(bh)) {
392 jbd_sync_bh(journal, bh);
1da177e4
LT
393 retry = 1;
394 break;
395 }
78ce89c9 396 retry = __process_buffer(journal, jh, bhs,&batch_count);
4afe9785
HK
397 if (retry < 0 && !result)
398 result = retry;
95c354fe
NP
399 if (!retry && (need_resched() ||
400 spin_needbreak(&journal->j_list_lock))) {
78ce89c9 401 spin_unlock(&journal->j_list_lock);
1da177e4
LT
402 retry = 1;
403 break;
404 }
78ce89c9 405 }
1da177e4 406
00ea8145 407 if (batch_count) {
78ce89c9
JK
408 if (!retry) {
409 spin_unlock(&journal->j_list_lock);
410 retry = 1;
411 }
1da177e4 412 __flush_batch(journal, bhs, &batch_count);
00ea8145 413 }
1da177e4 414
78ce89c9
JK
415 if (retry) {
416 spin_lock(&journal->j_list_lock);
417 goto restart;
418 }
1da177e4 419 /*
78ce89c9
JK
420 * Now we have cleaned up the first transaction's checkpoint
421 * list. Let's clean up the second one
7c8903f6 422 */
4afe9785
HK
423 err = __wait_cp_io(journal, transaction);
424 if (!result)
425 result = err;
1da177e4 426 }
78ce89c9 427out:
1da177e4 428 spin_unlock(&journal->j_list_lock);
1da177e4 429 if (result < 0)
4afe9785
HK
430 journal_abort(journal, result);
431 else
432 result = cleanup_journal_tail(journal);
433
434 return (result < 0) ? result : 0;
1da177e4
LT
435}
436
437/*
438 * Check the list of checkpoint transactions for the journal to see if
439 * we have already got rid of any since the last update of the log tail
440 * in the journal superblock. If so, we can instantly roll the
441 * superblock forward to remove those transactions from the log.
ae6ddcc5 442 *
1da177e4 443 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
ae6ddcc5 444 *
1da177e4
LT
445 * Called with the journal lock held.
446 *
447 * This is the only part of the journaling code which really needs to be
448 * aware of transaction aborts. Checkpointing involves writing to the
449 * main filesystem area rather than to the journal, so it can proceed
4afe9785
HK
450 * even in abort state, but we must not update the super block if
451 * checkpointing may have failed. Otherwise, we would lose some metadata
452 * buffers which should be written-back to the filesystem.
1da177e4
LT
453 */
454
455int cleanup_journal_tail(journal_t *journal)
456{
457 transaction_t * transaction;
458 tid_t first_tid;
9c28cbcc 459 unsigned int blocknr, freed;
1da177e4 460
4afe9785
HK
461 if (is_journal_aborted(journal))
462 return 1;
463
1da177e4 464 /* OK, work out the oldest transaction remaining in the log, and
ae6ddcc5
MC
465 * the log block it starts at.
466 *
1da177e4
LT
467 * If the log is now empty, we need to work out which is the
468 * next transaction ID we will write, and where it will
469 * start. */
470
471 spin_lock(&journal->j_state_lock);
472 spin_lock(&journal->j_list_lock);
473 transaction = journal->j_checkpoint_transactions;
474 if (transaction) {
475 first_tid = transaction->t_tid;
476 blocknr = transaction->t_log_start;
477 } else if ((transaction = journal->j_committing_transaction) != NULL) {
478 first_tid = transaction->t_tid;
479 blocknr = transaction->t_log_start;
480 } else if ((transaction = journal->j_running_transaction) != NULL) {
481 first_tid = transaction->t_tid;
482 blocknr = journal->j_head;
483 } else {
484 first_tid = journal->j_transaction_sequence;
485 blocknr = journal->j_head;
486 }
487 spin_unlock(&journal->j_list_lock);
488 J_ASSERT(blocknr != 0);
489
490 /* If the oldest pinned transaction is at the tail of the log
491 already then there's not much we can do right now. */
492 if (journal->j_tail_sequence == first_tid) {
493 spin_unlock(&journal->j_state_lock);
494 return 1;
495 }
496
497 /* OK, update the superblock to recover the freed space.
498 * Physical blocks come first: have we wrapped beyond the end of
499 * the log? */
500 freed = blocknr - journal->j_tail;
501 if (blocknr < journal->j_tail)
502 freed = freed + journal->j_last - journal->j_first;
503
504 jbd_debug(1,
9c28cbcc
JK
505 "Cleaning journal tail from %d to %d (offset %u), "
506 "freeing %u\n",
1da177e4
LT
507 journal->j_tail_sequence, first_tid, blocknr, freed);
508
509 journal->j_free += freed;
510 journal->j_tail_sequence = first_tid;
511 journal->j_tail = blocknr;
512 spin_unlock(&journal->j_state_lock);
513 if (!(journal->j_flags & JFS_ABORT))
514 journal_update_superblock(journal, 1);
515 return 0;
516}
517
518
519/* Checkpoint list management */
520
78ce89c9
JK
521/*
522 * journal_clean_one_cp_list
523 *
524 * Find all the written-back checkpoint buffers in the given list and release them.
525 *
526 * Called with the journal locked.
527 * Called with j_list_lock held.
528 * Returns number of bufers reaped (for debug)
529 */
530
531static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
532{
533 struct journal_head *last_jh;
534 struct journal_head *next_jh = jh;
535 int ret, freed = 0;
536
537 *released = 0;
538 if (!jh)
539 return 0;
540
e9ad5620 541 last_jh = jh->b_cpprev;
78ce89c9
JK
542 do {
543 jh = next_jh;
544 next_jh = jh->b_cpnext;
545 /* Use trylock because of the ranking */
546 if (jbd_trylock_bh_state(jh2bh(jh))) {
547 ret = __try_to_free_cp_buf(jh);
548 if (ret) {
549 freed++;
550 if (ret == 2) {
551 *released = 1;
552 return freed;
553 }
554 }
555 }
556 /*
557 * This function only frees up some memory
558 * if possible so we dont have an obligation
559 * to finish processing. Bail out if preemption
560 * requested:
561 */
562 if (need_resched())
563 return freed;
564 } while (jh != last_jh);
565
566 return freed;
567}
568
1da177e4
LT
569/*
570 * journal_clean_checkpoint_list
571 *
572 * Find all the written-back checkpoint buffers in the journal and release them.
573 *
574 * Called with the journal locked.
575 * Called with j_list_lock held.
78ce89c9 576 * Returns number of buffers reaped (for debug)
1da177e4
LT
577 */
578
579int __journal_clean_checkpoint_list(journal_t *journal)
580{
581 transaction_t *transaction, *last_transaction, *next_transaction;
7c8903f6 582 int ret = 0;
78ce89c9 583 int released;
1da177e4
LT
584
585 transaction = journal->j_checkpoint_transactions;
78ce89c9 586 if (!transaction)
1da177e4
LT
587 goto out;
588
589 last_transaction = transaction->t_cpprev;
590 next_transaction = transaction;
591 do {
1da177e4
LT
592 transaction = next_transaction;
593 next_transaction = transaction->t_cpnext;
78ce89c9
JK
594 ret += journal_clean_one_cp_list(transaction->
595 t_checkpoint_list, &released);
596 /*
597 * This function only frees up some memory if possible so we
598 * dont have an obligation to finish processing. Bail out if
599 * preemption requested:
600 */
601 if (need_resched())
602 goto out;
603 if (released)
604 continue;
605 /*
606 * It is essential that we are as careful as in the case of
607 * t_checkpoint_list with removing the buffer from the list as
608 * we can possibly see not yet submitted buffers on io_list
609 */
610 ret += journal_clean_one_cp_list(transaction->
611 t_checkpoint_io_list, &released);
612 if (need_resched())
613 goto out;
1da177e4
LT
614 } while (transaction != last_transaction);
615out:
616 return ret;
617}
618
ae6ddcc5 619/*
1da177e4
LT
620 * journal_remove_checkpoint: called after a buffer has been committed
621 * to disk (either by being write-back flushed to disk, or being
622 * committed to the log).
623 *
624 * We cannot safely clean a transaction out of the log until all of the
625 * buffer updates committed in that transaction have safely been stored
626 * elsewhere on disk. To achieve this, all of the buffers in a
627 * transaction need to be maintained on the transaction's checkpoint
78ce89c9 628 * lists until they have been rewritten, at which point this function is
1da177e4 629 * called to remove the buffer from the existing transaction's
78ce89c9
JK
630 * checkpoint lists.
631 *
632 * The function returns 1 if it frees the transaction, 0 otherwise.
1da177e4
LT
633 *
634 * This function is called with the journal locked.
635 * This function is called with j_list_lock held.
78ce89c9 636 * This function is called with jbd_lock_bh_state(jh2bh(jh))
1da177e4
LT
637 */
638
78ce89c9 639int __journal_remove_checkpoint(struct journal_head *jh)
1da177e4
LT
640{
641 transaction_t *transaction;
642 journal_t *journal;
78ce89c9 643 int ret = 0;
1da177e4
LT
644
645 JBUFFER_TRACE(jh, "entry");
646
647 if ((transaction = jh->b_cp_transaction) == NULL) {
648 JBUFFER_TRACE(jh, "not on transaction");
649 goto out;
650 }
651 journal = transaction->t_journal;
652
653 __buffer_unlink(jh);
78ce89c9 654 jh->b_cp_transaction = NULL;
1da177e4 655
78ce89c9
JK
656 if (transaction->t_checkpoint_list != NULL ||
657 transaction->t_checkpoint_io_list != NULL)
1da177e4
LT
658 goto out;
659 JBUFFER_TRACE(jh, "transaction has no more buffers");
660
661 /*
662 * There is one special case to worry about: if we have just pulled the
d4beaf4a
JK
663 * buffer off a running or committing transaction's checkpoing list,
664 * then even if the checkpoint list is empty, the transaction obviously
665 * cannot be dropped!
1da177e4 666 *
d4beaf4a 667 * The locking here around t_state is a bit sleazy.
1da177e4
LT
668 * See the comment at the end of journal_commit_transaction().
669 */
d4beaf4a
JK
670 if (transaction->t_state != T_FINISHED) {
671 JBUFFER_TRACE(jh, "belongs to running/committing transaction");
1da177e4
LT
672 goto out;
673 }
674
675 /* OK, that was the last buffer for the transaction: we can now
676 safely remove this transaction from the log */
677
678 __journal_drop_transaction(journal, transaction);
679
680 /* Just in case anybody was waiting for more transactions to be
681 checkpointed... */
682 wake_up(&journal->j_wait_logspace);
78ce89c9 683 ret = 1;
1da177e4
LT
684out:
685 JBUFFER_TRACE(jh, "exit");
78ce89c9 686 return ret;
1da177e4
LT
687}
688
689/*
690 * journal_insert_checkpoint: put a committed buffer onto a checkpoint
691 * list so that we know when it is safe to clean the transaction out of
692 * the log.
693 *
694 * Called with the journal locked.
695 * Called with j_list_lock held.
696 */
ae6ddcc5 697void __journal_insert_checkpoint(struct journal_head *jh,
1da177e4
LT
698 transaction_t *transaction)
699{
700 JBUFFER_TRACE(jh, "entry");
701 J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
702 J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
703
704 jh->b_cp_transaction = transaction;
705
706 if (!transaction->t_checkpoint_list) {
707 jh->b_cpnext = jh->b_cpprev = jh;
708 } else {
709 jh->b_cpnext = transaction->t_checkpoint_list;
710 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
711 jh->b_cpprev->b_cpnext = jh;
712 jh->b_cpnext->b_cpprev = jh;
713 }
714 transaction->t_checkpoint_list = jh;
715}
716
717/*
718 * We've finished with this transaction structure: adios...
ae6ddcc5 719 *
1da177e4
LT
720 * The transaction must have no links except for the checkpoint by this
721 * point.
722 *
723 * Called with the journal locked.
724 * Called with j_list_lock held.
725 */
726
727void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)
728{
729 assert_spin_locked(&journal->j_list_lock);
730 if (transaction->t_cpnext) {
731 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
732 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
733 if (journal->j_checkpoint_transactions == transaction)
734 journal->j_checkpoint_transactions =
735 transaction->t_cpnext;
736 if (journal->j_checkpoint_transactions == transaction)
737 journal->j_checkpoint_transactions = NULL;
738 }
739
740 J_ASSERT(transaction->t_state == T_FINISHED);
741 J_ASSERT(transaction->t_buffers == NULL);
742 J_ASSERT(transaction->t_sync_datalist == NULL);
743 J_ASSERT(transaction->t_forget == NULL);
744 J_ASSERT(transaction->t_iobuf_list == NULL);
745 J_ASSERT(transaction->t_shadow_list == NULL);
746 J_ASSERT(transaction->t_log_list == NULL);
747 J_ASSERT(transaction->t_checkpoint_list == NULL);
78ce89c9 748 J_ASSERT(transaction->t_checkpoint_io_list == NULL);
1da177e4
LT
749 J_ASSERT(transaction->t_updates == 0);
750 J_ASSERT(journal->j_committing_transaction != transaction);
751 J_ASSERT(journal->j_running_transaction != transaction);
752
753 jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
754 kfree(transaction);
755}