Line data Source code
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 :
26 : /*
27 : * Unlink a buffer from a transaction checkpoint list.
28 : *
29 : * Called with j_list_lock held.
30 : */
31 : static inline void __buffer_unlink_first(struct journal_head *jh)
32 : {
33 0 : transaction_t *transaction = jh->b_cp_transaction;
34 :
35 0 : jh->b_cpnext->b_cpprev = jh->b_cpprev;
36 0 : jh->b_cpprev->b_cpnext = jh->b_cpnext;
37 0 : if (transaction->t_checkpoint_list == jh) {
38 0 : transaction->t_checkpoint_list = jh->b_cpnext;
39 0 : if (transaction->t_checkpoint_list == jh)
40 0 : transaction->t_checkpoint_list = NULL;
41 : }
42 0 : }
43 :
44 : /*
45 : * Unlink a buffer from a transaction checkpoint(io) list.
46 : *
47 : * Called with j_list_lock held.
48 : */
49 : static inline void __buffer_unlink(struct journal_head *jh)
50 : {
51 0 : transaction_t *transaction = jh->b_cp_transaction;
52 :
53 0 : __buffer_unlink_first(jh);
54 0 : if (transaction->t_checkpoint_io_list == jh) {
55 0 : transaction->t_checkpoint_io_list = jh->b_cpnext;
56 0 : if (transaction->t_checkpoint_io_list == jh)
57 0 : transaction->t_checkpoint_io_list = NULL;
58 : }
59 0 : }
60 :
61 : /*
62 : * Move a buffer from the checkpoint list to the checkpoint io list
63 : *
64 : * Called with j_list_lock held
65 : */
66 : static inline void __buffer_relink_io(struct journal_head *jh)
67 : {
68 0 : transaction_t *transaction = jh->b_cp_transaction;
69 0 :
70 0 : __buffer_unlink_first(jh);
71 :
72 0 : if (!transaction->t_checkpoint_io_list) {
73 0 : jh->b_cpnext = jh->b_cpprev = jh;
74 : } else {
75 0 : jh->b_cpnext = transaction->t_checkpoint_io_list;
76 0 : jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
77 0 : jh->b_cpprev->b_cpnext = jh;
78 0 : jh->b_cpnext->b_cpprev = jh;
79 : }
80 0 : transaction->t_checkpoint_io_list = jh;
81 0 : }
82 :
83 : /*
84 : * Try to release a checkpointed buffer from its transaction.
85 : * Returns 1 if we released it and 2 if we also released the
86 : * whole transaction.
87 : *
88 : * Requires j_list_lock
89 : * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
90 : */
91 : static int __try_to_free_cp_buf(struct journal_head *jh)
92 : {
93 0 : int ret = 0;
94 0 : struct buffer_head *bh = jh2bh(jh);
95 0 :
96 0 : if (jh->b_jlist == BJ_None && !buffer_locked(bh) &&
97 0 : !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
98 0 : JBUFFER_TRACE(jh, "remove from checkpoint list");
99 0 : ret = __journal_remove_checkpoint(jh) + 1;
100 0 : jbd_unlock_bh_state(bh);
101 0 : journal_remove_journal_head(bh);
102 : BUFFER_TRACE(bh, "release");
103 0 : __brelse(bh);
104 : } else {
105 0 : jbd_unlock_bh_state(bh);
106 : }
107 0 : 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 : */
116 : void __log_wait_for_space(journal_t *journal)
117 : {
118 0 : int nblocks, space_left;
119 0 : assert_spin_locked(&journal->j_state_lock);
120 0 :
121 0 : nblocks = jbd_space_needed(journal);
122 0 : while (__log_space_left(journal) < nblocks) {
123 0 : if (journal->j_flags & JFS_ABORT)
124 0 : return;
125 0 : spin_unlock(&journal->j_state_lock);
126 0 : mutex_lock(&journal->j_checkpoint_mutex);
127 :
128 : /*
129 0 : * Test again, another process may have checkpointed while we
130 : * were waiting for the checkpoint lock. If there are no
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.
138 : */
139 0 : spin_lock(&journal->j_state_lock);
140 0 : spin_lock(&journal->j_list_lock);
141 0 : nblocks = jbd_space_needed(journal);
142 0 : space_left = __log_space_left(journal);
143 0 : if (space_left < nblocks) {
144 0 : int chkpt = journal->j_checkpoint_transactions != NULL;
145 0 : tid_t tid = 0;
146 :
147 0 : if (journal->j_committing_transaction)
148 0 : tid = journal->j_committing_transaction->t_tid;
149 0 : spin_unlock(&journal->j_list_lock);
150 0 : spin_unlock(&journal->j_state_lock);
151 0 : if (chkpt) {
152 0 : log_do_checkpoint(journal);
153 0 : } else if (cleanup_journal_tail(journal) == 0) {
154 : /* We were able to recover space; yay! */
155 : ;
156 0 : } else if (tid) {
157 0 : log_wait_commit(journal, tid);
158 : } else {
159 0 : printk(KERN_ERR "%s: needed %d blocks and "
160 : "only had %d space available\n",
161 : __func__, nblocks, space_left);
162 0 : printk(KERN_ERR "%s: no way to get more "
163 : "journal space\n", __func__);
164 0 : WARN_ON(1);
165 0 : journal_abort(journal, 0);
166 : }
167 0 : spin_lock(&journal->j_state_lock);
168 : } else {
169 0 : spin_unlock(&journal->j_list_lock);
170 : }
171 0 : mutex_unlock(&journal->j_checkpoint_mutex);
172 : }
173 0 : }
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 : */
180 : static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
181 : __releases(journal->j_list_lock)
182 : {
183 0 : get_bh(bh);
184 0 : spin_unlock(&journal->j_list_lock);
185 0 : jbd_lock_bh_state(bh);
186 0 : jbd_unlock_bh_state(bh);
187 0 : put_bh(bh);
188 0 : }
189 :
190 : /*
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.
195 : *
196 : * Return 0 on success, and return <0 if some buffers have failed
197 : * to be written out.
198 : *
199 : * Called with j_list_lock held.
200 : */
201 : static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
202 : {
203 0 : struct journal_head *jh;
204 0 : struct buffer_head *bh;
205 0 : tid_t this_tid;
206 0 : int released = 0;
207 0 : int ret = 0;
208 0 :
209 0 : this_tid = transaction->t_tid;
210 0 : restart:
211 0 : /* Did somebody clean up the transaction in the meanwhile? */
212 0 : if (journal->j_checkpoint_transactions != transaction ||
213 : transaction->t_tid != this_tid)
214 0 : return ret;
215 0 : while (!released && transaction->t_checkpoint_io_list) {
216 0 : jh = transaction->t_checkpoint_io_list;
217 0 : bh = jh2bh(jh);
218 0 : if (!jbd_trylock_bh_state(bh)) {
219 0 : jbd_sync_bh(journal, bh);
220 0 : spin_lock(&journal->j_list_lock);
221 0 : goto restart;
222 : }
223 0 : if (buffer_locked(bh)) {
224 0 : atomic_inc(&bh->b_count);
225 0 : spin_unlock(&journal->j_list_lock);
226 0 : jbd_unlock_bh_state(bh);
227 0 : wait_on_buffer(bh);
228 : /* the journal_head may have gone by now */
229 : BUFFER_TRACE(bh, "brelse");
230 0 : __brelse(bh);
231 0 : spin_lock(&journal->j_list_lock);
232 0 : goto restart;
233 : }
234 0 : if (unlikely(buffer_write_io_error(bh)))
235 0 : ret = -EIO;
236 :
237 : /*
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
240 : */
241 0 : released = __journal_remove_checkpoint(jh);
242 0 : jbd_unlock_bh_state(bh);
243 0 : journal_remove_journal_head(bh);
244 0 : __brelse(bh);
245 : }
246 0 :
247 0 : return ret;
248 : }
249 :
250 : #define NR_BATCH 64
251 :
252 : static void
253 : __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
254 : {
255 0 : int i;
256 0 :
257 0 : ll_rw_block(SWRITE, *batch_count, bhs);
258 0 : for (i = 0; i < *batch_count; i++) {
259 0 : struct buffer_head *bh = bhs[i];
260 0 : clear_buffer_jwrite(bh);
261 : BUFFER_TRACE(bh, "brelse");
262 0 : __brelse(bh);
263 : }
264 0 : *batch_count = 0;
265 0 : }
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
271 : * scan of the checkpoint list. Return <0 if the buffer has failed to
272 : * be written out.
273 : *
274 : * Called with j_list_lock held and drops it if 1 is returned
275 : * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
276 : */
277 : static int __process_buffer(journal_t *journal, struct journal_head *jh,
278 : struct buffer_head **bhs, int *batch_count)
279 : {
280 0 : struct buffer_head *bh = jh2bh(jh);
281 0 : int ret = 0;
282 0 :
283 0 : if (buffer_locked(bh)) {
284 0 : atomic_inc(&bh->b_count);
285 0 : spin_unlock(&journal->j_list_lock);
286 0 : jbd_unlock_bh_state(bh);
287 0 : wait_on_buffer(bh);
288 0 : /* the journal_head may have gone by now */
289 0 : BUFFER_TRACE(bh, "brelse");
290 0 : __brelse(bh);
291 0 : ret = 1;
292 0 : } else if (jh->b_transaction != NULL) {
293 0 : transaction_t *t = jh->b_transaction;
294 0 : tid_t tid = t->t_tid;
295 :
296 0 : spin_unlock(&journal->j_list_lock);
297 0 : jbd_unlock_bh_state(bh);
298 0 : log_start_commit(journal, tid);
299 0 : log_wait_commit(journal, tid);
300 0 : ret = 1;
301 0 : } else if (!buffer_dirty(bh)) {
302 0 : ret = 1;
303 0 : if (unlikely(buffer_write_io_error(bh)))
304 0 : ret = -EIO;
305 0 : J_ASSERT_JH(jh, !buffer_jbddirty(bh));
306 : BUFFER_TRACE(bh, "remove from checkpoint");
307 0 : __journal_remove_checkpoint(jh);
308 0 : spin_unlock(&journal->j_list_lock);
309 0 : jbd_unlock_bh_state(bh);
310 0 : journal_remove_journal_head(bh);
311 0 : __brelse(bh);
312 : } else {
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
318 : * disk, as that would break recoverability.
319 : */
320 : BUFFER_TRACE(bh, "queue");
321 0 : get_bh(bh);
322 0 : J_ASSERT_BH(bh, !buffer_jwrite(bh));
323 0 : set_buffer_jwrite(bh);
324 0 : bhs[*batch_count] = bh;
325 0 : __buffer_relink_io(jh);
326 0 : jbd_unlock_bh_state(bh);
327 0 : (*batch_count)++;
328 0 : if (*batch_count == NR_BATCH) {
329 0 : spin_unlock(&journal->j_list_lock);
330 0 : __flush_batch(journal, bhs, batch_count);
331 0 : ret = 1;
332 : }
333 : }
334 0 : return ret;
335 : }
336 :
337 : /*
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.
341 : *
342 : * The journal should be locked before calling this function.
343 : * Called with j_checkpoint_mutex held.
344 : */
345 : int log_do_checkpoint(journal_t *journal)
346 : {
347 0 : transaction_t *transaction;
348 0 : tid_t this_tid;
349 0 : int result;
350 0 :
351 0 : jbd_debug(1, "Start checkpoint\n");
352 0 :
353 0 : /*
354 0 : * First thing: if there are any transactions in the log which
355 0 : * don't need checkpointing, just eliminate them from the
356 0 : * journal straight away.
357 0 : */
358 0 : result = cleanup_journal_tail(journal);
359 : jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
360 0 : if (result <= 0)
361 0 : return result;
362 :
363 : /*
364 : * OK, we need to start writing disk blocks. Take one transaction
365 : * and write it.
366 : */
367 0 : result = 0;
368 0 : spin_lock(&journal->j_list_lock);
369 0 : if (!journal->j_checkpoint_transactions)
370 0 : goto out;
371 0 : transaction = journal->j_checkpoint_transactions;
372 0 : this_tid = transaction->t_tid;
373 0 : restart:
374 : /*
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).
378 : */
379 0 : if (journal->j_checkpoint_transactions == transaction &&
380 : transaction->t_tid == this_tid) {
381 0 : int batch_count = 0;
382 : struct buffer_head *bhs[NR_BATCH];
383 : struct journal_head *jh;
384 0 : int retry = 0, err;
385 :
386 0 : while (!retry && transaction->t_checkpoint_list) {
387 0 : struct buffer_head *bh;
388 0 :
389 0 : jh = transaction->t_checkpoint_list;
390 0 : bh = jh2bh(jh);
391 0 : if (!jbd_trylock_bh_state(bh)) {
392 0 : jbd_sync_bh(journal, bh);
393 0 : retry = 1;
394 0 : break;
395 : }
396 0 : retry = __process_buffer(journal, jh, bhs,&batch_count);
397 0 : if (retry < 0 && !result)
398 0 : result = retry;
399 0 : if (!retry && (need_resched() ||
400 : spin_needbreak(&journal->j_list_lock))) {
401 0 : spin_unlock(&journal->j_list_lock);
402 0 : retry = 1;
403 0 : break;
404 : }
405 : }
406 :
407 0 : if (batch_count) {
408 0 : if (!retry) {
409 0 : spin_unlock(&journal->j_list_lock);
410 0 : retry = 1;
411 0 : }
412 0 : __flush_batch(journal, bhs, &batch_count);
413 : }
414 :
415 0 : if (retry) {
416 0 : spin_lock(&journal->j_list_lock);
417 0 : goto restart;
418 : }
419 : /*
420 : * Now we have cleaned up the first transaction's checkpoint
421 : * list. Let's clean up the second one
422 : */
423 0 : err = __wait_cp_io(journal, transaction);
424 0 : if (!result)
425 0 : result = err;
426 : }
427 : out:
428 0 : spin_unlock(&journal->j_list_lock);
429 0 : if (result < 0)
430 0 : journal_abort(journal, result);
431 : else
432 0 : result = cleanup_journal_tail(journal);
433 :
434 0 : return (result < 0) ? result : 0;
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.
442 : *
443 : * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
444 : *
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
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.
453 : */
454 :
455 : int cleanup_journal_tail(journal_t *journal)
456 : {
457 0 : transaction_t * transaction;
458 0 : tid_t first_tid;
459 0 : unsigned int blocknr, freed;
460 0 :
461 0 : if (is_journal_aborted(journal))
462 0 : return 1;
463 :
464 : /* OK, work out the oldest transaction remaining in the log, and
465 : * the log block it starts at.
466 : *
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 0 : spin_lock(&journal->j_state_lock);
472 0 : spin_lock(&journal->j_list_lock);
473 0 : transaction = journal->j_checkpoint_transactions;
474 0 : if (transaction) {
475 0 : first_tid = transaction->t_tid;
476 0 : blocknr = transaction->t_log_start;
477 0 : } else if ((transaction = journal->j_committing_transaction) != NULL) {
478 0 : first_tid = transaction->t_tid;
479 0 : blocknr = transaction->t_log_start;
480 0 : } else if ((transaction = journal->j_running_transaction) != NULL) {
481 0 : first_tid = transaction->t_tid;
482 0 : blocknr = journal->j_head;
483 : } else {
484 0 : first_tid = journal->j_transaction_sequence;
485 0 : blocknr = journal->j_head;
486 : }
487 0 : spin_unlock(&journal->j_list_lock);
488 0 : 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 0 : if (journal->j_tail_sequence == first_tid) {
493 0 : spin_unlock(&journal->j_state_lock);
494 0 : 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 0 : freed = blocknr - journal->j_tail;
501 0 : if (blocknr < journal->j_tail)
502 0 : freed = freed + journal->j_last - journal->j_first;
503 :
504 : jbd_debug(1,
505 : "Cleaning journal tail from %d to %d (offset %u), "
506 : "freeing %u\n",
507 : journal->j_tail_sequence, first_tid, blocknr, freed);
508 :
509 0 : journal->j_free += freed;
510 0 : journal->j_tail_sequence = first_tid;
511 0 : journal->j_tail = blocknr;
512 0 : spin_unlock(&journal->j_state_lock);
513 0 : if (!(journal->j_flags & JFS_ABORT))
514 0 : journal_update_superblock(journal, 1);
515 0 : return 0;
516 : }
517 :
518 :
519 : /* Checkpoint list management */
520 :
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 :
531 : static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
532 : {
533 0 : struct journal_head *last_jh;
534 0 : struct journal_head *next_jh = jh;
535 0 : int ret, freed = 0;
536 0 :
537 0 : *released = 0;
538 0 : if (!jh)
539 0 : return 0;
540 :
541 0 : last_jh = jh->b_cpprev;
542 0 : do {
543 0 : jh = next_jh;
544 0 : next_jh = jh->b_cpnext;
545 : /* Use trylock because of the ranking */
546 0 : if (jbd_trylock_bh_state(jh2bh(jh))) {
547 0 : ret = __try_to_free_cp_buf(jh);
548 0 : if (ret) {
549 0 : freed++;
550 0 : if (ret == 2) {
551 0 : *released = 1;
552 0 : 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 0 : if (need_resched())
563 0 : return freed;
564 0 : } while (jh != last_jh);
565 :
566 0 : return freed;
567 : }
568 :
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.
576 : * Returns number of buffers reaped (for debug)
577 : */
578 :
579 : int __journal_clean_checkpoint_list(journal_t *journal)
580 : {
581 0 : transaction_t *transaction, *last_transaction, *next_transaction;
582 0 : int ret = 0;
583 0 : int released;
584 0 :
585 0 : transaction = journal->j_checkpoint_transactions;
586 0 : if (!transaction)
587 0 : goto out;
588 0 :
589 0 : last_transaction = transaction->t_cpprev;
590 0 : next_transaction = transaction;
591 0 : do {
592 0 : transaction = next_transaction;
593 0 : next_transaction = transaction->t_cpnext;
594 0 : 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 0 : if (need_resched())
602 0 : goto out;
603 0 : if (released)
604 0 : 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 0 : ret += journal_clean_one_cp_list(transaction->
611 : t_checkpoint_io_list, &released);
612 0 : if (need_resched())
613 0 : goto out;
614 0 : } while (transaction != last_transaction);
615 : out:
616 0 : return ret;
617 0 : }
618 :
619 : /*
620 : * journal_remove_checkpoint: called after a buffer has been committed
621 0 : * 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
628 : * lists until they have been rewritten, at which point this function is
629 : * called to remove the buffer from the existing transaction's
630 : * checkpoint lists.
631 : *
632 : * The function returns 1 if it frees the transaction, 0 otherwise.
633 : *
634 : * This function is called with the journal locked.
635 : * This function is called with j_list_lock held.
636 : * This function is called with jbd_lock_bh_state(jh2bh(jh))
637 : */
638 :
639 : int __journal_remove_checkpoint(struct journal_head *jh)
640 : {
641 0 : transaction_t *transaction;
642 0 : journal_t *journal;
643 0 : int ret = 0;
644 :
645 : JBUFFER_TRACE(jh, "entry");
646 :
647 0 : if ((transaction = jh->b_cp_transaction) == NULL) {
648 : JBUFFER_TRACE(jh, "not on transaction");
649 0 : goto out;
650 : }
651 0 : journal = transaction->t_journal;
652 :
653 0 : __buffer_unlink(jh);
654 0 : jh->b_cp_transaction = NULL;
655 :
656 0 : if (transaction->t_checkpoint_list != NULL ||
657 : transaction->t_checkpoint_io_list != NULL)
658 0 : 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
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!
666 : *
667 : * The locking here around t_state is a bit sleazy.
668 : * See the comment at the end of journal_commit_transaction().
669 : */
670 0 : if (transaction->t_state != T_FINISHED) {
671 : JBUFFER_TRACE(jh, "belongs to running/committing transaction");
672 0 : 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 0 : __journal_drop_transaction(journal, transaction);
679 :
680 : /* Just in case anybody was waiting for more transactions to be
681 : checkpointed... */
682 0 : wake_up(&journal->j_wait_logspace);
683 0 : ret = 1;
684 : out:
685 0 : JBUFFER_TRACE(jh, "exit");
686 0 : return ret;
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 : */
697 : void __journal_insert_checkpoint(struct journal_head *jh,
698 : transaction_t *transaction)
699 0 : {
700 0 : JBUFFER_TRACE(jh, "entry");
701 0 : J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
702 0 : J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
703 0 :
704 0 : jh->b_cp_transaction = transaction;
705 0 :
706 0 : if (!transaction->t_checkpoint_list) {
707 0 : jh->b_cpnext = jh->b_cpprev = jh;
708 : } else {
709 0 : jh->b_cpnext = transaction->t_checkpoint_list;
710 0 : jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
711 0 : jh->b_cpprev->b_cpnext = jh;
712 0 : jh->b_cpnext->b_cpprev = jh;
713 : }
714 0 : transaction->t_checkpoint_list = jh;
715 0 : }
716 :
717 : /*
718 : * We've finished with this transaction structure: adios...
719 : *
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 :
727 : void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)
728 : {
729 0 : assert_spin_locked(&journal->j_list_lock);
730 0 : if (transaction->t_cpnext) {
731 0 : transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
732 0 : transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
733 0 : if (journal->j_checkpoint_transactions == transaction)
734 0 : journal->j_checkpoint_transactions =
735 0 : transaction->t_cpnext;
736 0 : if (journal->j_checkpoint_transactions == transaction)
737 0 : journal->j_checkpoint_transactions = NULL;
738 0 : }
739 0 :
740 0 : J_ASSERT(transaction->t_state == T_FINISHED);
741 0 : J_ASSERT(transaction->t_buffers == NULL);
742 0 : J_ASSERT(transaction->t_sync_datalist == NULL);
743 0 : J_ASSERT(transaction->t_forget == NULL);
744 0 : J_ASSERT(transaction->t_iobuf_list == NULL);
745 0 : J_ASSERT(transaction->t_shadow_list == NULL);
746 0 : J_ASSERT(transaction->t_log_list == NULL);
747 0 : J_ASSERT(transaction->t_checkpoint_list == NULL);
748 0 : J_ASSERT(transaction->t_checkpoint_io_list == NULL);
749 0 : J_ASSERT(transaction->t_updates == 0);
750 0 : J_ASSERT(journal->j_committing_transaction != transaction);
751 0 : J_ASSERT(journal->j_running_transaction != transaction);
752 :
753 : jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
754 0 : kfree(transaction);
755 0 : }
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