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1/*
2 * linux/fs/jbd/commit.c
3 *
4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
5 *
6 * Copyright 1998 Red Hat corp --- 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 * Journal commit routines for the generic filesystem journaling code;
13 * part of the ext2fs journaling system.
14 */
15
16#include <linux/time.h>
17#include <linux/fs.h>
18#include <linux/jbd.h>
19#include <linux/errno.h>
20#include <linux/mm.h>
21#include <linux/pagemap.h>
22#include <linux/bio.h>
23#include <linux/blkdev.h>
24#include <trace/events/jbd.h>
25
26/*
27 * Default IO end handler for temporary BJ_IO buffer_heads.
28 */
29static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
30{
31 BUFFER_TRACE(bh, "");
32 if (uptodate)
33 set_buffer_uptodate(bh);
34 else
35 clear_buffer_uptodate(bh);
36 unlock_buffer(bh);
37}
38
39/*
40 * When an ext3-ordered file is truncated, it is possible that many pages are
41 * not successfully freed, because they are attached to a committing transaction.
42 * After the transaction commits, these pages are left on the LRU, with no
43 * ->mapping, and with attached buffers. These pages are trivially reclaimable
44 * by the VM, but their apparent absence upsets the VM accounting, and it makes
45 * the numbers in /proc/meminfo look odd.
46 *
47 * So here, we have a buffer which has just come off the forget list. Look to
48 * see if we can strip all buffers from the backing page.
49 *
50 * Called under journal->j_list_lock. The caller provided us with a ref
51 * against the buffer, and we drop that here.
52 */
53static void release_buffer_page(struct buffer_head *bh)
54{
55 struct page *page;
56
57 if (buffer_dirty(bh))
58 goto nope;
59 if (atomic_read(&bh->b_count) != 1)
60 goto nope;
61 page = bh->b_page;
62 if (!page)
63 goto nope;
64 if (page->mapping)
65 goto nope;
66
67 /* OK, it's a truncated page */
68 if (!trylock_page(page))
69 goto nope;
70
71 page_cache_get(page);
72 __brelse(bh);
73 try_to_free_buffers(page);
74 unlock_page(page);
75 page_cache_release(page);
76 return;
77
78nope:
79 __brelse(bh);
80}
81
82/*
83 * Decrement reference counter for data buffer. If it has been marked
84 * 'BH_Freed', release it and the page to which it belongs if possible.
85 */
86static void release_data_buffer(struct buffer_head *bh)
87{
88 if (buffer_freed(bh)) {
89 clear_buffer_freed(bh);
90 release_buffer_page(bh);
91 } else
92 put_bh(bh);
93}
94
95/*
96 * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is
97 * held. For ranking reasons we must trylock. If we lose, schedule away and
98 * return 0. j_list_lock is dropped in this case.
99 */
100static int inverted_lock(journal_t *journal, struct buffer_head *bh)
101{
102 if (!jbd_trylock_bh_state(bh)) {
103 spin_unlock(&journal->j_list_lock);
104 schedule();
105 return 0;
106 }
107 return 1;
108}
109
110/* Done it all: now write the commit record. We should have
111 * cleaned up our previous buffers by now, so if we are in abort
112 * mode we can now just skip the rest of the journal write
113 * entirely.
114 *
115 * Returns 1 if the journal needs to be aborted or 0 on success
116 */
117static int journal_write_commit_record(journal_t *journal,
118 transaction_t *commit_transaction)
119{
120 struct journal_head *descriptor;
121 struct buffer_head *bh;
122 journal_header_t *header;
123 int ret;
124
125 if (is_journal_aborted(journal))
126 return 0;
127
128 descriptor = journal_get_descriptor_buffer(journal);
129 if (!descriptor)
130 return 1;
131
132 bh = jh2bh(descriptor);
133
134 header = (journal_header_t *)(bh->b_data);
135 header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
136 header->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK);
137 header->h_sequence = cpu_to_be32(commit_transaction->t_tid);
138
139 JBUFFER_TRACE(descriptor, "write commit block");
140 set_buffer_dirty(bh);
141
142 if (journal->j_flags & JFS_BARRIER)
143 ret = __sync_dirty_buffer(bh, WRITE_SYNC | WRITE_FLUSH_FUA);
144 else
145 ret = sync_dirty_buffer(bh);
146
147 put_bh(bh); /* One for getblk() */
148 journal_put_journal_head(descriptor);
149
150 return (ret == -EIO);
151}
152
153static void journal_do_submit_data(struct buffer_head **wbuf, int bufs,
154 int write_op)
155{
156 int i;
157
158 for (i = 0; i < bufs; i++) {
159 wbuf[i]->b_end_io = end_buffer_write_sync;
160 /* We use-up our safety reference in submit_bh() */
161 submit_bh(write_op, wbuf[i]);
162 }
163}
164
165/*
166 * Submit all the data buffers to disk
167 */
168static int journal_submit_data_buffers(journal_t *journal,
169 transaction_t *commit_transaction,
170 int write_op)
171{
172 struct journal_head *jh;
173 struct buffer_head *bh;
174 int locked;
175 int bufs = 0;
176 struct buffer_head **wbuf = journal->j_wbuf;
177 int err = 0;
178
179 /*
180 * Whenever we unlock the journal and sleep, things can get added
181 * onto ->t_sync_datalist, so we have to keep looping back to
182 * write_out_data until we *know* that the list is empty.
183 *
184 * Cleanup any flushed data buffers from the data list. Even in
185 * abort mode, we want to flush this out as soon as possible.
186 */
187write_out_data:
188 cond_resched();
189 spin_lock(&journal->j_list_lock);
190
191 while (commit_transaction->t_sync_datalist) {
192 jh = commit_transaction->t_sync_datalist;
193 bh = jh2bh(jh);
194 locked = 0;
195
196 /* Get reference just to make sure buffer does not disappear
197 * when we are forced to drop various locks */
198 get_bh(bh);
199 /* If the buffer is dirty, we need to submit IO and hence
200 * we need the buffer lock. We try to lock the buffer without
201 * blocking. If we fail, we need to drop j_list_lock and do
202 * blocking lock_buffer().
203 */
204 if (buffer_dirty(bh)) {
205 if (!trylock_buffer(bh)) {
206 BUFFER_TRACE(bh, "needs blocking lock");
207 spin_unlock(&journal->j_list_lock);
208 trace_jbd_do_submit_data(journal,
209 commit_transaction);
210 /* Write out all data to prevent deadlocks */
211 journal_do_submit_data(wbuf, bufs, write_op);
212 bufs = 0;
213 lock_buffer(bh);
214 spin_lock(&journal->j_list_lock);
215 }
216 locked = 1;
217 }
218 /* We have to get bh_state lock. Again out of order, sigh. */
219 if (!inverted_lock(journal, bh)) {
220 jbd_lock_bh_state(bh);
221 spin_lock(&journal->j_list_lock);
222 }
223 /* Someone already cleaned up the buffer? */
224 if (!buffer_jbd(bh) || bh2jh(bh) != jh
225 || jh->b_transaction != commit_transaction
226 || jh->b_jlist != BJ_SyncData) {
227 jbd_unlock_bh_state(bh);
228 if (locked)
229 unlock_buffer(bh);
230 BUFFER_TRACE(bh, "already cleaned up");
231 release_data_buffer(bh);
232 continue;
233 }
234 if (locked && test_clear_buffer_dirty(bh)) {
235 BUFFER_TRACE(bh, "needs writeout, adding to array");
236 wbuf[bufs++] = bh;
237 __journal_file_buffer(jh, commit_transaction,
238 BJ_Locked);
239 jbd_unlock_bh_state(bh);
240 if (bufs == journal->j_wbufsize) {
241 spin_unlock(&journal->j_list_lock);
242 trace_jbd_do_submit_data(journal,
243 commit_transaction);
244 journal_do_submit_data(wbuf, bufs, write_op);
245 bufs = 0;
246 goto write_out_data;
247 }
248 } else if (!locked && buffer_locked(bh)) {
249 __journal_file_buffer(jh, commit_transaction,
250 BJ_Locked);
251 jbd_unlock_bh_state(bh);
252 put_bh(bh);
253 } else {
254 BUFFER_TRACE(bh, "writeout complete: unfile");
255 if (unlikely(!buffer_uptodate(bh)))
256 err = -EIO;
257 __journal_unfile_buffer(jh);
258 jbd_unlock_bh_state(bh);
259 if (locked)
260 unlock_buffer(bh);
261 release_data_buffer(bh);
262 }
263
264 if (need_resched() || spin_needbreak(&journal->j_list_lock)) {
265 spin_unlock(&journal->j_list_lock);
266 goto write_out_data;
267 }
268 }
269 spin_unlock(&journal->j_list_lock);
270 trace_jbd_do_submit_data(journal, commit_transaction);
271 journal_do_submit_data(wbuf, bufs, write_op);
272
273 return err;
274}
275
276/*
277 * journal_commit_transaction
278 *
279 * The primary function for committing a transaction to the log. This
280 * function is called by the journal thread to begin a complete commit.
281 */
282void journal_commit_transaction(journal_t *journal)
283{
284 transaction_t *commit_transaction;
285 struct journal_head *jh, *new_jh, *descriptor;
286 struct buffer_head **wbuf = journal->j_wbuf;
287 int bufs;
288 int flags;
289 int err;
290 unsigned int blocknr;
291 ktime_t start_time;
292 u64 commit_time;
293 char *tagp = NULL;
294 journal_header_t *header;
295 journal_block_tag_t *tag = NULL;
296 int space_left = 0;
297 int first_tag = 0;
298 int tag_flag;
299 int i;
300 struct blk_plug plug;
301
302 /*
303 * First job: lock down the current transaction and wait for
304 * all outstanding updates to complete.
305 */
306
307 /* Do we need to erase the effects of a prior journal_flush? */
308 if (journal->j_flags & JFS_FLUSHED) {
309 jbd_debug(3, "super block updated\n");
310 journal_update_superblock(journal, 1);
311 } else {
312 jbd_debug(3, "superblock not updated\n");
313 }
314
315 J_ASSERT(journal->j_running_transaction != NULL);
316 J_ASSERT(journal->j_committing_transaction == NULL);
317
318 commit_transaction = journal->j_running_transaction;
319 J_ASSERT(commit_transaction->t_state == T_RUNNING);
320
321 trace_jbd_start_commit(journal, commit_transaction);
322 jbd_debug(1, "JBD: starting commit of transaction %d\n",
323 commit_transaction->t_tid);
324
325 spin_lock(&journal->j_state_lock);
326 commit_transaction->t_state = T_LOCKED;
327
328 trace_jbd_commit_locking(journal, commit_transaction);
329 spin_lock(&commit_transaction->t_handle_lock);
330 while (commit_transaction->t_updates) {
331 DEFINE_WAIT(wait);
332
333 prepare_to_wait(&journal->j_wait_updates, &wait,
334 TASK_UNINTERRUPTIBLE);
335 if (commit_transaction->t_updates) {
336 spin_unlock(&commit_transaction->t_handle_lock);
337 spin_unlock(&journal->j_state_lock);
338 schedule();
339 spin_lock(&journal->j_state_lock);
340 spin_lock(&commit_transaction->t_handle_lock);
341 }
342 finish_wait(&journal->j_wait_updates, &wait);
343 }
344 spin_unlock(&commit_transaction->t_handle_lock);
345
346 J_ASSERT (commit_transaction->t_outstanding_credits <=
347 journal->j_max_transaction_buffers);
348
349 /*
350 * First thing we are allowed to do is to discard any remaining
351 * BJ_Reserved buffers. Note, it is _not_ permissible to assume
352 * that there are no such buffers: if a large filesystem
353 * operation like a truncate needs to split itself over multiple
354 * transactions, then it may try to do a journal_restart() while
355 * there are still BJ_Reserved buffers outstanding. These must
356 * be released cleanly from the current transaction.
357 *
358 * In this case, the filesystem must still reserve write access
359 * again before modifying the buffer in the new transaction, but
360 * we do not require it to remember exactly which old buffers it
361 * has reserved. This is consistent with the existing behaviour
362 * that multiple journal_get_write_access() calls to the same
363 * buffer are perfectly permissible.
364 */
365 while (commit_transaction->t_reserved_list) {
366 jh = commit_transaction->t_reserved_list;
367 JBUFFER_TRACE(jh, "reserved, unused: refile");
368 /*
369 * A journal_get_undo_access()+journal_release_buffer() may
370 * leave undo-committed data.
371 */
372 if (jh->b_committed_data) {
373 struct buffer_head *bh = jh2bh(jh);
374
375 jbd_lock_bh_state(bh);
376 jbd_free(jh->b_committed_data, bh->b_size);
377 jh->b_committed_data = NULL;
378 jbd_unlock_bh_state(bh);
379 }
380 journal_refile_buffer(journal, jh);
381 }
382
383 /*
384 * Now try to drop any written-back buffers from the journal's
385 * checkpoint lists. We do this *before* commit because it potentially
386 * frees some memory
387 */
388 spin_lock(&journal->j_list_lock);
389 __journal_clean_checkpoint_list(journal);
390 spin_unlock(&journal->j_list_lock);
391
392 jbd_debug (3, "JBD: commit phase 1\n");
393
394 /*
395 * Switch to a new revoke table.
396 */
397 journal_switch_revoke_table(journal);
398
399 trace_jbd_commit_flushing(journal, commit_transaction);
400 commit_transaction->t_state = T_FLUSH;
401 journal->j_committing_transaction = commit_transaction;
402 journal->j_running_transaction = NULL;
403 start_time = ktime_get();
404 commit_transaction->t_log_start = journal->j_head;
405 wake_up(&journal->j_wait_transaction_locked);
406 spin_unlock(&journal->j_state_lock);
407
408 jbd_debug (3, "JBD: commit phase 2\n");
409
410 /*
411 * Now start flushing things to disk, in the order they appear
412 * on the transaction lists. Data blocks go first.
413 */
414 blk_start_plug(&plug);
415 err = journal_submit_data_buffers(journal, commit_transaction,
416 WRITE_SYNC);
417 blk_finish_plug(&plug);
418
419 /*
420 * Wait for all previously submitted IO to complete.
421 */
422 spin_lock(&journal->j_list_lock);
423 while (commit_transaction->t_locked_list) {
424 struct buffer_head *bh;
425
426 jh = commit_transaction->t_locked_list->b_tprev;
427 bh = jh2bh(jh);
428 get_bh(bh);
429 if (buffer_locked(bh)) {
430 spin_unlock(&journal->j_list_lock);
431 wait_on_buffer(bh);
432 spin_lock(&journal->j_list_lock);
433 }
434 if (unlikely(!buffer_uptodate(bh))) {
435 if (!trylock_page(bh->b_page)) {
436 spin_unlock(&journal->j_list_lock);
437 lock_page(bh->b_page);
438 spin_lock(&journal->j_list_lock);
439 }
440 if (bh->b_page->mapping)
441 set_bit(AS_EIO, &bh->b_page->mapping->flags);
442
443 unlock_page(bh->b_page);
444 SetPageError(bh->b_page);
445 err = -EIO;
446 }
447 if (!inverted_lock(journal, bh)) {
448 put_bh(bh);
449 spin_lock(&journal->j_list_lock);
450 continue;
451 }
452 if (buffer_jbd(bh) && bh2jh(bh) == jh &&
453 jh->b_transaction == commit_transaction &&
454 jh->b_jlist == BJ_Locked)
455 __journal_unfile_buffer(jh);
456 jbd_unlock_bh_state(bh);
457 release_data_buffer(bh);
458 cond_resched_lock(&journal->j_list_lock);
459 }
460 spin_unlock(&journal->j_list_lock);
461
462 if (err) {
463 char b[BDEVNAME_SIZE];
464
465 printk(KERN_WARNING
466 "JBD: Detected IO errors while flushing file data "
467 "on %s\n", bdevname(journal->j_fs_dev, b));
468 if (journal->j_flags & JFS_ABORT_ON_SYNCDATA_ERR)
469 journal_abort(journal, err);
470 err = 0;
471 }
472
473 blk_start_plug(&plug);
474
475 journal_write_revoke_records(journal, commit_transaction, WRITE_SYNC);
476
477 /*
478 * If we found any dirty or locked buffers, then we should have
479 * looped back up to the write_out_data label. If there weren't
480 * any then journal_clean_data_list should have wiped the list
481 * clean by now, so check that it is in fact empty.
482 */
483 J_ASSERT (commit_transaction->t_sync_datalist == NULL);
484
485 jbd_debug (3, "JBD: commit phase 3\n");
486
487 /*
488 * Way to go: we have now written out all of the data for a
489 * transaction! Now comes the tricky part: we need to write out
490 * metadata. Loop over the transaction's entire buffer list:
491 */
492 spin_lock(&journal->j_state_lock);
493 commit_transaction->t_state = T_COMMIT;
494 spin_unlock(&journal->j_state_lock);
495
496 trace_jbd_commit_logging(journal, commit_transaction);
497 J_ASSERT(commit_transaction->t_nr_buffers <=
498 commit_transaction->t_outstanding_credits);
499
500 descriptor = NULL;
501 bufs = 0;
502 while (commit_transaction->t_buffers) {
503
504 /* Find the next buffer to be journaled... */
505
506 jh = commit_transaction->t_buffers;
507
508 /* If we're in abort mode, we just un-journal the buffer and
509 release it. */
510
511 if (is_journal_aborted(journal)) {
512 clear_buffer_jbddirty(jh2bh(jh));
513 JBUFFER_TRACE(jh, "journal is aborting: refile");
514 journal_refile_buffer(journal, jh);
515 /* If that was the last one, we need to clean up
516 * any descriptor buffers which may have been
517 * already allocated, even if we are now
518 * aborting. */
519 if (!commit_transaction->t_buffers)
520 goto start_journal_io;
521 continue;
522 }
523
524 /* Make sure we have a descriptor block in which to
525 record the metadata buffer. */
526
527 if (!descriptor) {
528 struct buffer_head *bh;
529
530 J_ASSERT (bufs == 0);
531
532 jbd_debug(4, "JBD: get descriptor\n");
533
534 descriptor = journal_get_descriptor_buffer(journal);
535 if (!descriptor) {
536 journal_abort(journal, -EIO);
537 continue;
538 }
539
540 bh = jh2bh(descriptor);
541 jbd_debug(4, "JBD: got buffer %llu (%p)\n",
542 (unsigned long long)bh->b_blocknr, bh->b_data);
543 header = (journal_header_t *)&bh->b_data[0];
544 header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
545 header->h_blocktype = cpu_to_be32(JFS_DESCRIPTOR_BLOCK);
546 header->h_sequence = cpu_to_be32(commit_transaction->t_tid);
547
548 tagp = &bh->b_data[sizeof(journal_header_t)];
549 space_left = bh->b_size - sizeof(journal_header_t);
550 first_tag = 1;
551 set_buffer_jwrite(bh);
552 set_buffer_dirty(bh);
553 wbuf[bufs++] = bh;
554
555 /* Record it so that we can wait for IO
556 completion later */
557 BUFFER_TRACE(bh, "ph3: file as descriptor");
558 journal_file_buffer(descriptor, commit_transaction,
559 BJ_LogCtl);
560 }
561
562 /* Where is the buffer to be written? */
563
564 err = journal_next_log_block(journal, &blocknr);
565 /* If the block mapping failed, just abandon the buffer
566 and repeat this loop: we'll fall into the
567 refile-on-abort condition above. */
568 if (err) {
569 journal_abort(journal, err);
570 continue;
571 }
572
573 /*
574 * start_this_handle() uses t_outstanding_credits to determine
575 * the free space in the log, but this counter is changed
576 * by journal_next_log_block() also.
577 */
578 commit_transaction->t_outstanding_credits--;
579
580 /* Bump b_count to prevent truncate from stumbling over
581 the shadowed buffer! @@@ This can go if we ever get
582 rid of the BJ_IO/BJ_Shadow pairing of buffers. */
583 get_bh(jh2bh(jh));
584
585 /* Make a temporary IO buffer with which to write it out
586 (this will requeue both the metadata buffer and the
587 temporary IO buffer). new_bh goes on BJ_IO*/
588
589 set_buffer_jwrite(jh2bh(jh));
590 /*
591 * akpm: journal_write_metadata_buffer() sets
592 * new_bh->b_transaction to commit_transaction.
593 * We need to clean this up before we release new_bh
594 * (which is of type BJ_IO)
595 */
596 JBUFFER_TRACE(jh, "ph3: write metadata");
597 flags = journal_write_metadata_buffer(commit_transaction,
598 jh, &new_jh, blocknr);
599 set_buffer_jwrite(jh2bh(new_jh));
600 wbuf[bufs++] = jh2bh(new_jh);
601
602 /* Record the new block's tag in the current descriptor
603 buffer */
604
605 tag_flag = 0;
606 if (flags & 1)
607 tag_flag |= JFS_FLAG_ESCAPE;
608 if (!first_tag)
609 tag_flag |= JFS_FLAG_SAME_UUID;
610
611 tag = (journal_block_tag_t *) tagp;
612 tag->t_blocknr = cpu_to_be32(jh2bh(jh)->b_blocknr);
613 tag->t_flags = cpu_to_be32(tag_flag);
614 tagp += sizeof(journal_block_tag_t);
615 space_left -= sizeof(journal_block_tag_t);
616
617 if (first_tag) {
618 memcpy (tagp, journal->j_uuid, 16);
619 tagp += 16;
620 space_left -= 16;
621 first_tag = 0;
622 }
623
624 /* If there's no more to do, or if the descriptor is full,
625 let the IO rip! */
626
627 if (bufs == journal->j_wbufsize ||
628 commit_transaction->t_buffers == NULL ||
629 space_left < sizeof(journal_block_tag_t) + 16) {
630
631 jbd_debug(4, "JBD: Submit %d IOs\n", bufs);
632
633 /* Write an end-of-descriptor marker before
634 submitting the IOs. "tag" still points to
635 the last tag we set up. */
636
637 tag->t_flags |= cpu_to_be32(JFS_FLAG_LAST_TAG);
638
639start_journal_io:
640 for (i = 0; i < bufs; i++) {
641 struct buffer_head *bh = wbuf[i];
642 lock_buffer(bh);
643 clear_buffer_dirty(bh);
644 set_buffer_uptodate(bh);
645 bh->b_end_io = journal_end_buffer_io_sync;
646 submit_bh(WRITE_SYNC, bh);
647 }
648 cond_resched();
649
650 /* Force a new descriptor to be generated next
651 time round the loop. */
652 descriptor = NULL;
653 bufs = 0;
654 }
655 }
656
657 blk_finish_plug(&plug);
658
659 /* Lo and behold: we have just managed to send a transaction to
660 the log. Before we can commit it, wait for the IO so far to
661 complete. Control buffers being written are on the
662 transaction's t_log_list queue, and metadata buffers are on
663 the t_iobuf_list queue.
664
665 Wait for the buffers in reverse order. That way we are
666 less likely to be woken up until all IOs have completed, and
667 so we incur less scheduling load.
668 */
669
670 jbd_debug(3, "JBD: commit phase 4\n");
671
672 /*
673 * akpm: these are BJ_IO, and j_list_lock is not needed.
674 * See __journal_try_to_free_buffer.
675 */
676wait_for_iobuf:
677 while (commit_transaction->t_iobuf_list != NULL) {
678 struct buffer_head *bh;
679
680 jh = commit_transaction->t_iobuf_list->b_tprev;
681 bh = jh2bh(jh);
682 if (buffer_locked(bh)) {
683 wait_on_buffer(bh);
684 goto wait_for_iobuf;
685 }
686 if (cond_resched())
687 goto wait_for_iobuf;
688
689 if (unlikely(!buffer_uptodate(bh)))
690 err = -EIO;
691
692 clear_buffer_jwrite(bh);
693
694 JBUFFER_TRACE(jh, "ph4: unfile after journal write");
695 journal_unfile_buffer(journal, jh);
696
697 /*
698 * ->t_iobuf_list should contain only dummy buffer_heads
699 * which were created by journal_write_metadata_buffer().
700 */
701 BUFFER_TRACE(bh, "dumping temporary bh");
702 journal_put_journal_head(jh);
703 __brelse(bh);
704 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
705 free_buffer_head(bh);
706
707 /* We also have to unlock and free the corresponding
708 shadowed buffer */
709 jh = commit_transaction->t_shadow_list->b_tprev;
710 bh = jh2bh(jh);
711 clear_buffer_jwrite(bh);
712 J_ASSERT_BH(bh, buffer_jbddirty(bh));
713
714 /* The metadata is now released for reuse, but we need
715 to remember it against this transaction so that when
716 we finally commit, we can do any checkpointing
717 required. */
718 JBUFFER_TRACE(jh, "file as BJ_Forget");
719 journal_file_buffer(jh, commit_transaction, BJ_Forget);
720 /*
721 * Wake up any transactions which were waiting for this
722 * IO to complete. The barrier must be here so that changes
723 * by journal_file_buffer() take effect before wake_up_bit()
724 * does the waitqueue check.
725 */
726 smp_mb();
727 wake_up_bit(&bh->b_state, BH_Unshadow);
728 JBUFFER_TRACE(jh, "brelse shadowed buffer");
729 __brelse(bh);
730 }
731
732 J_ASSERT (commit_transaction->t_shadow_list == NULL);
733
734 jbd_debug(3, "JBD: commit phase 5\n");
735
736 /* Here we wait for the revoke record and descriptor record buffers */
737 wait_for_ctlbuf:
738 while (commit_transaction->t_log_list != NULL) {
739 struct buffer_head *bh;
740
741 jh = commit_transaction->t_log_list->b_tprev;
742 bh = jh2bh(jh);
743 if (buffer_locked(bh)) {
744 wait_on_buffer(bh);
745 goto wait_for_ctlbuf;
746 }
747 if (cond_resched())
748 goto wait_for_ctlbuf;
749
750 if (unlikely(!buffer_uptodate(bh)))
751 err = -EIO;
752
753 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
754 clear_buffer_jwrite(bh);
755 journal_unfile_buffer(journal, jh);
756 journal_put_journal_head(jh);
757 __brelse(bh); /* One for getblk */
758 /* AKPM: bforget here */
759 }
760
761 if (err)
762 journal_abort(journal, err);
763
764 jbd_debug(3, "JBD: commit phase 6\n");
765
766 /* All metadata is written, now write commit record and do cleanup */
767 spin_lock(&journal->j_state_lock);
768 J_ASSERT(commit_transaction->t_state == T_COMMIT);
769 commit_transaction->t_state = T_COMMIT_RECORD;
770 spin_unlock(&journal->j_state_lock);
771
772 if (journal_write_commit_record(journal, commit_transaction))
773 err = -EIO;
774
775 if (err)
776 journal_abort(journal, err);
777
778 /* End of a transaction! Finally, we can do checkpoint
779 processing: any buffers committed as a result of this
780 transaction can be removed from any checkpoint list it was on
781 before. */
782
783 jbd_debug(3, "JBD: commit phase 7\n");
784
785 J_ASSERT(commit_transaction->t_sync_datalist == NULL);
786 J_ASSERT(commit_transaction->t_buffers == NULL);
787 J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
788 J_ASSERT(commit_transaction->t_iobuf_list == NULL);
789 J_ASSERT(commit_transaction->t_shadow_list == NULL);
790 J_ASSERT(commit_transaction->t_log_list == NULL);
791
792restart_loop:
793 /*
794 * As there are other places (journal_unmap_buffer()) adding buffers
795 * to this list we have to be careful and hold the j_list_lock.
796 */
797 spin_lock(&journal->j_list_lock);
798 while (commit_transaction->t_forget) {
799 transaction_t *cp_transaction;
800 struct buffer_head *bh;
801 int try_to_free = 0;
802
803 jh = commit_transaction->t_forget;
804 spin_unlock(&journal->j_list_lock);
805 bh = jh2bh(jh);
806 /*
807 * Get a reference so that bh cannot be freed before we are
808 * done with it.
809 */
810 get_bh(bh);
811 jbd_lock_bh_state(bh);
812 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction ||
813 jh->b_transaction == journal->j_running_transaction);
814
815 /*
816 * If there is undo-protected committed data against
817 * this buffer, then we can remove it now. If it is a
818 * buffer needing such protection, the old frozen_data
819 * field now points to a committed version of the
820 * buffer, so rotate that field to the new committed
821 * data.
822 *
823 * Otherwise, we can just throw away the frozen data now.
824 */
825 if (jh->b_committed_data) {
826 jbd_free(jh->b_committed_data, bh->b_size);
827 jh->b_committed_data = NULL;
828 if (jh->b_frozen_data) {
829 jh->b_committed_data = jh->b_frozen_data;
830 jh->b_frozen_data = NULL;
831 }
832 } else if (jh->b_frozen_data) {
833 jbd_free(jh->b_frozen_data, bh->b_size);
834 jh->b_frozen_data = NULL;
835 }
836
837 spin_lock(&journal->j_list_lock);
838 cp_transaction = jh->b_cp_transaction;
839 if (cp_transaction) {
840 JBUFFER_TRACE(jh, "remove from old cp transaction");
841 __journal_remove_checkpoint(jh);
842 }
843
844 /* Only re-checkpoint the buffer_head if it is marked
845 * dirty. If the buffer was added to the BJ_Forget list
846 * by journal_forget, it may no longer be dirty and
847 * there's no point in keeping a checkpoint record for
848 * it. */
849
850 /* A buffer which has been freed while still being
851 * journaled by a previous transaction may end up still
852 * being dirty here, but we want to avoid writing back
853 * that buffer in the future after the "add to orphan"
854 * operation been committed, That's not only a performance
855 * gain, it also stops aliasing problems if the buffer is
856 * left behind for writeback and gets reallocated for another
857 * use in a different page. */
858 if (buffer_freed(bh) && !jh->b_next_transaction) {
859 clear_buffer_freed(bh);
860 clear_buffer_jbddirty(bh);
861 }
862
863 if (buffer_jbddirty(bh)) {
864 JBUFFER_TRACE(jh, "add to new checkpointing trans");
865 __journal_insert_checkpoint(jh, commit_transaction);
866 if (is_journal_aborted(journal))
867 clear_buffer_jbddirty(bh);
868 } else {
869 J_ASSERT_BH(bh, !buffer_dirty(bh));
870 /*
871 * The buffer on BJ_Forget list and not jbddirty means
872 * it has been freed by this transaction and hence it
873 * could not have been reallocated until this
874 * transaction has committed. *BUT* it could be
875 * reallocated once we have written all the data to
876 * disk and before we process the buffer on BJ_Forget
877 * list.
878 */
879 if (!jh->b_next_transaction)
880 try_to_free = 1;
881 }
882 JBUFFER_TRACE(jh, "refile or unfile freed buffer");
883 __journal_refile_buffer(jh);
884 jbd_unlock_bh_state(bh);
885 if (try_to_free)
886 release_buffer_page(bh);
887 else
888 __brelse(bh);
889 cond_resched_lock(&journal->j_list_lock);
890 }
891 spin_unlock(&journal->j_list_lock);
892 /*
893 * This is a bit sleazy. We use j_list_lock to protect transition
894 * of a transaction into T_FINISHED state and calling
895 * __journal_drop_transaction(). Otherwise we could race with
896 * other checkpointing code processing the transaction...
897 */
898 spin_lock(&journal->j_state_lock);
899 spin_lock(&journal->j_list_lock);
900 /*
901 * Now recheck if some buffers did not get attached to the transaction
902 * while the lock was dropped...
903 */
904 if (commit_transaction->t_forget) {
905 spin_unlock(&journal->j_list_lock);
906 spin_unlock(&journal->j_state_lock);
907 goto restart_loop;
908 }
909
910 /* Done with this transaction! */
911
912 jbd_debug(3, "JBD: commit phase 8\n");
913
914 J_ASSERT(commit_transaction->t_state == T_COMMIT_RECORD);
915
916 commit_transaction->t_state = T_FINISHED;
917 J_ASSERT(commit_transaction == journal->j_committing_transaction);
918 journal->j_commit_sequence = commit_transaction->t_tid;
919 journal->j_committing_transaction = NULL;
920 commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
921
922 /*
923 * weight the commit time higher than the average time so we don't
924 * react too strongly to vast changes in commit time
925 */
926 if (likely(journal->j_average_commit_time))
927 journal->j_average_commit_time = (commit_time*3 +
928 journal->j_average_commit_time) / 4;
929 else
930 journal->j_average_commit_time = commit_time;
931
932 spin_unlock(&journal->j_state_lock);
933
934 if (commit_transaction->t_checkpoint_list == NULL &&
935 commit_transaction->t_checkpoint_io_list == NULL) {
936 __journal_drop_transaction(journal, commit_transaction);
937 } else {
938 if (journal->j_checkpoint_transactions == NULL) {
939 journal->j_checkpoint_transactions = commit_transaction;
940 commit_transaction->t_cpnext = commit_transaction;
941 commit_transaction->t_cpprev = commit_transaction;
942 } else {
943 commit_transaction->t_cpnext =
944 journal->j_checkpoint_transactions;
945 commit_transaction->t_cpprev =
946 commit_transaction->t_cpnext->t_cpprev;
947 commit_transaction->t_cpnext->t_cpprev =
948 commit_transaction;
949 commit_transaction->t_cpprev->t_cpnext =
950 commit_transaction;
951 }
952 }
953 spin_unlock(&journal->j_list_lock);
954
955 trace_jbd_end_commit(journal, commit_transaction);
956 jbd_debug(1, "JBD: commit %d complete, head %d\n",
957 journal->j_commit_sequence, journal->j_tail_sequence);
958
959 wake_up(&journal->j_wait_done_commit);
960}