1 /*
2 * linux/fs/jbd2/transaction.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 * Generic filesystem transaction handling code; part of the ext2fs
13 * journaling system.
14 *
15 * This file manages transactions (compound commits managed by the
16 * journaling code) and handles (individual atomic operations by the
17 * filesystem).
18 */
19
20 #include <linux/time.h>
21 #include <linux/fs.h>
22 #include <linux/jbd2.h>
23 #include <linux/errno.h>
24 #include <linux/slab.h>
25 #include <linux/timer.h>
26 #include <linux/mm.h>
27 #include <linux/highmem.h>
28 #include <linux/hrtimer.h>
29 #include <linux/backing-dev.h>
30 #include <linux/bug.h>
31 #include <linux/module.h>
32
33 static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
34 static void __jbd2_journal_unfile_buffer(struct journal_head *jh);
35
36 static struct kmem_cache *transaction_cache;
jbd2_journal_init_transaction_cache(void)37 int __init jbd2_journal_init_transaction_cache(void)
38 {
39 J_ASSERT(!transaction_cache);
40 transaction_cache = kmem_cache_create("jbd2_transaction_s",
41 sizeof(transaction_t),
42 0,
43 SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY,
44 NULL);
45 if (transaction_cache)
46 return 0;
47 return -ENOMEM;
48 }
49
jbd2_journal_destroy_transaction_cache(void)50 void jbd2_journal_destroy_transaction_cache(void)
51 {
52 if (transaction_cache) {
53 kmem_cache_destroy(transaction_cache);
54 transaction_cache = NULL;
55 }
56 }
57
jbd2_journal_free_transaction(transaction_t * transaction)58 void jbd2_journal_free_transaction(transaction_t *transaction)
59 {
60 if (unlikely(ZERO_OR_NULL_PTR(transaction)))
61 return;
62 kmem_cache_free(transaction_cache, transaction);
63 }
64
65 /*
66 * jbd2_get_transaction: obtain a new transaction_t object.
67 *
68 * Simply allocate and initialise a new transaction. Create it in
69 * RUNNING state and add it to the current journal (which should not
70 * have an existing running transaction: we only make a new transaction
71 * once we have started to commit the old one).
72 *
73 * Preconditions:
74 * The journal MUST be locked. We don't perform atomic mallocs on the
75 * new transaction and we can't block without protecting against other
76 * processes trying to touch the journal while it is in transition.
77 *
78 */
79
80 static transaction_t *
jbd2_get_transaction(journal_t * journal,transaction_t * transaction)81 jbd2_get_transaction(journal_t *journal, transaction_t *transaction)
82 {
83 transaction->t_journal = journal;
84 transaction->t_state = T_RUNNING;
85 transaction->t_start_time = ktime_get();
86 transaction->t_tid = journal->j_transaction_sequence++;
87 transaction->t_expires = jiffies + journal->j_commit_interval;
88 spin_lock_init(&transaction->t_handle_lock);
89 atomic_set(&transaction->t_updates, 0);
90 atomic_set(&transaction->t_outstanding_credits, 0);
91 atomic_set(&transaction->t_handle_count, 0);
92 INIT_LIST_HEAD(&transaction->t_inode_list);
93 INIT_LIST_HEAD(&transaction->t_private_list);
94
95 /* Set up the commit timer for the new transaction. */
96 journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires);
97 add_timer(&journal->j_commit_timer);
98
99 J_ASSERT(journal->j_running_transaction == NULL);
100 journal->j_running_transaction = transaction;
101 transaction->t_max_wait = 0;
102 transaction->t_start = jiffies;
103
104 return transaction;
105 }
106
107 /*
108 * Handle management.
109 *
110 * A handle_t is an object which represents a single atomic update to a
111 * filesystem, and which tracks all of the modifications which form part
112 * of that one update.
113 */
114
115 /*
116 * Update transaction's maximum wait time, if debugging is enabled.
117 *
118 * In order for t_max_wait to be reliable, it must be protected by a
119 * lock. But doing so will mean that start_this_handle() can not be
120 * run in parallel on SMP systems, which limits our scalability. So
121 * unless debugging is enabled, we no longer update t_max_wait, which
122 * means that maximum wait time reported by the jbd2_run_stats
123 * tracepoint will always be zero.
124 */
update_t_max_wait(transaction_t * transaction,unsigned long ts)125 static inline void update_t_max_wait(transaction_t *transaction,
126 unsigned long ts)
127 {
128 #ifdef CONFIG_JBD2_DEBUG
129 if (jbd2_journal_enable_debug &&
130 time_after(transaction->t_start, ts)) {
131 ts = jbd2_time_diff(ts, transaction->t_start);
132 spin_lock(&transaction->t_handle_lock);
133 if (ts > transaction->t_max_wait)
134 transaction->t_max_wait = ts;
135 spin_unlock(&transaction->t_handle_lock);
136 }
137 #endif
138 }
139
140 /*
141 * start_this_handle: Given a handle, deal with any locking or stalling
142 * needed to make sure that there is enough journal space for the handle
143 * to begin. Attach the handle to a transaction and set up the
144 * transaction's buffer credits.
145 */
146
start_this_handle(journal_t * journal,handle_t * handle,gfp_t gfp_mask)147 static int start_this_handle(journal_t *journal, handle_t *handle,
148 gfp_t gfp_mask)
149 {
150 transaction_t *transaction, *new_transaction = NULL;
151 tid_t tid;
152 int needed, need_to_start;
153 int nblocks = handle->h_buffer_credits;
154 unsigned long ts = jiffies;
155
156 if (nblocks > journal->j_max_transaction_buffers) {
157 printk(KERN_ERR "JBD2: %s wants too many credits (%d > %d)\n",
158 current->comm, nblocks,
159 journal->j_max_transaction_buffers);
160 return -ENOSPC;
161 }
162
163 alloc_transaction:
164 if (!journal->j_running_transaction) {
165 new_transaction = kmem_cache_alloc(transaction_cache,
166 gfp_mask | __GFP_ZERO);
167 if (!new_transaction) {
168 /*
169 * If __GFP_FS is not present, then we may be
170 * being called from inside the fs writeback
171 * layer, so we MUST NOT fail. Since
172 * __GFP_NOFAIL is going away, we will arrange
173 * to retry the allocation ourselves.
174 */
175 if ((gfp_mask & __GFP_FS) == 0) {
176 congestion_wait(BLK_RW_ASYNC, HZ/50);
177 goto alloc_transaction;
178 }
179 return -ENOMEM;
180 }
181 }
182
183 jbd_debug(3, "New handle %p going live.\n", handle);
184
185 /*
186 * We need to hold j_state_lock until t_updates has been incremented,
187 * for proper journal barrier handling
188 */
189 repeat:
190 read_lock(&journal->j_state_lock);
191 BUG_ON(journal->j_flags & JBD2_UNMOUNT);
192 if (is_journal_aborted(journal) ||
193 (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
194 read_unlock(&journal->j_state_lock);
195 jbd2_journal_free_transaction(new_transaction);
196 return -EROFS;
197 }
198
199 /* Wait on the journal's transaction barrier if necessary */
200 if (journal->j_barrier_count) {
201 read_unlock(&journal->j_state_lock);
202 wait_event(journal->j_wait_transaction_locked,
203 journal->j_barrier_count == 0);
204 goto repeat;
205 }
206
207 if (!journal->j_running_transaction) {
208 read_unlock(&journal->j_state_lock);
209 if (!new_transaction)
210 goto alloc_transaction;
211 write_lock(&journal->j_state_lock);
212 if (!journal->j_running_transaction &&
213 !journal->j_barrier_count) {
214 jbd2_get_transaction(journal, new_transaction);
215 new_transaction = NULL;
216 }
217 write_unlock(&journal->j_state_lock);
218 goto repeat;
219 }
220
221 transaction = journal->j_running_transaction;
222
223 /*
224 * If the current transaction is locked down for commit, wait for the
225 * lock to be released.
226 */
227 if (transaction->t_state == T_LOCKED) {
228 DEFINE_WAIT(wait);
229
230 prepare_to_wait(&journal->j_wait_transaction_locked,
231 &wait, TASK_UNINTERRUPTIBLE);
232 read_unlock(&journal->j_state_lock);
233 schedule();
234 finish_wait(&journal->j_wait_transaction_locked, &wait);
235 goto repeat;
236 }
237
238 /*
239 * If there is not enough space left in the log to write all potential
240 * buffers requested by this operation, we need to stall pending a log
241 * checkpoint to free some more log space.
242 */
243 needed = atomic_add_return(nblocks,
244 &transaction->t_outstanding_credits);
245
246 if (needed > journal->j_max_transaction_buffers) {
247 /*
248 * If the current transaction is already too large, then start
249 * to commit it: we can then go back and attach this handle to
250 * a new transaction.
251 */
252 DEFINE_WAIT(wait);
253
254 jbd_debug(2, "Handle %p starting new commit...\n", handle);
255 atomic_sub(nblocks, &transaction->t_outstanding_credits);
256 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
257 TASK_UNINTERRUPTIBLE);
258 tid = transaction->t_tid;
259 need_to_start = !tid_geq(journal->j_commit_request, tid);
260 read_unlock(&journal->j_state_lock);
261 if (need_to_start)
262 jbd2_log_start_commit(journal, tid);
263 schedule();
264 finish_wait(&journal->j_wait_transaction_locked, &wait);
265 goto repeat;
266 }
267
268 /*
269 * The commit code assumes that it can get enough log space
270 * without forcing a checkpoint. This is *critical* for
271 * correctness: a checkpoint of a buffer which is also
272 * associated with a committing transaction creates a deadlock,
273 * so commit simply cannot force through checkpoints.
274 *
275 * We must therefore ensure the necessary space in the journal
276 * *before* starting to dirty potentially checkpointed buffers
277 * in the new transaction.
278 *
279 * The worst part is, any transaction currently committing can
280 * reduce the free space arbitrarily. Be careful to account for
281 * those buffers when checkpointing.
282 */
283
284 /*
285 * @@@ AKPM: This seems rather over-defensive. We're giving commit
286 * a _lot_ of headroom: 1/4 of the journal plus the size of
287 * the committing transaction. Really, we only need to give it
288 * committing_transaction->t_outstanding_credits plus "enough" for
289 * the log control blocks.
290 * Also, this test is inconsistent with the matching one in
291 * jbd2_journal_extend().
292 */
293 if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) {
294 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
295 atomic_sub(nblocks, &transaction->t_outstanding_credits);
296 read_unlock(&journal->j_state_lock);
297 write_lock(&journal->j_state_lock);
298 if (__jbd2_log_space_left(journal) < jbd_space_needed(journal))
299 __jbd2_log_wait_for_space(journal);
300 write_unlock(&journal->j_state_lock);
301 goto repeat;
302 }
303
304 /* OK, account for the buffers that this operation expects to
305 * use and add the handle to the running transaction.
306 */
307 update_t_max_wait(transaction, ts);
308 handle->h_transaction = transaction;
309 atomic_inc(&transaction->t_updates);
310 atomic_inc(&transaction->t_handle_count);
311 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
312 handle, nblocks,
313 atomic_read(&transaction->t_outstanding_credits),
314 __jbd2_log_space_left(journal));
315 read_unlock(&journal->j_state_lock);
316
317 lock_map_acquire(&handle->h_lockdep_map);
318 jbd2_journal_free_transaction(new_transaction);
319 return 0;
320 }
321
322 static struct lock_class_key jbd2_handle_key;
323
324 /* Allocate a new handle. This should probably be in a slab... */
new_handle(int nblocks)325 static handle_t *new_handle(int nblocks)
326 {
327 handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
328 if (!handle)
329 return NULL;
330 memset(handle, 0, sizeof(*handle));
331 handle->h_buffer_credits = nblocks;
332 handle->h_ref = 1;
333
334 lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle",
335 &jbd2_handle_key, 0);
336
337 return handle;
338 }
339
340 /**
341 * handle_t *jbd2_journal_start() - Obtain a new handle.
342 * @journal: Journal to start transaction on.
343 * @nblocks: number of block buffer we might modify
344 *
345 * We make sure that the transaction can guarantee at least nblocks of
346 * modified buffers in the log. We block until the log can guarantee
347 * that much space.
348 *
349 * This function is visible to journal users (like ext3fs), so is not
350 * called with the journal already locked.
351 *
352 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
353 * on failure.
354 */
jbd2__journal_start(journal_t * journal,int nblocks,gfp_t gfp_mask)355 handle_t *jbd2__journal_start(journal_t *journal, int nblocks, gfp_t gfp_mask)
356 {
357 handle_t *handle = journal_current_handle();
358 int err;
359
360 if (!journal)
361 return ERR_PTR(-EROFS);
362
363 if (handle) {
364 J_ASSERT(handle->h_transaction->t_journal == journal);
365 handle->h_ref++;
366 return handle;
367 }
368
369 handle = new_handle(nblocks);
370 if (!handle)
371 return ERR_PTR(-ENOMEM);
372
373 current->journal_info = handle;
374
375 err = start_this_handle(journal, handle, gfp_mask);
376 if (err < 0) {
377 jbd2_free_handle(handle);
378 current->journal_info = NULL;
379 handle = ERR_PTR(err);
380 }
381 return handle;
382 }
383 EXPORT_SYMBOL(jbd2__journal_start);
384
385
jbd2_journal_start(journal_t * journal,int nblocks)386 handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
387 {
388 return jbd2__journal_start(journal, nblocks, GFP_NOFS);
389 }
390 EXPORT_SYMBOL(jbd2_journal_start);
391
392
393 /**
394 * int jbd2_journal_extend() - extend buffer credits.
395 * @handle: handle to 'extend'
396 * @nblocks: nr blocks to try to extend by.
397 *
398 * Some transactions, such as large extends and truncates, can be done
399 * atomically all at once or in several stages. The operation requests
400 * a credit for a number of buffer modications in advance, but can
401 * extend its credit if it needs more.
402 *
403 * jbd2_journal_extend tries to give the running handle more buffer credits.
404 * It does not guarantee that allocation - this is a best-effort only.
405 * The calling process MUST be able to deal cleanly with a failure to
406 * extend here.
407 *
408 * Return 0 on success, non-zero on failure.
409 *
410 * return code < 0 implies an error
411 * return code > 0 implies normal transaction-full status.
412 */
jbd2_journal_extend(handle_t * handle,int nblocks)413 int jbd2_journal_extend(handle_t *handle, int nblocks)
414 {
415 transaction_t *transaction = handle->h_transaction;
416 journal_t *journal = transaction->t_journal;
417 int result;
418 int wanted;
419
420 result = -EIO;
421 if (is_handle_aborted(handle))
422 goto out;
423
424 result = 1;
425
426 read_lock(&journal->j_state_lock);
427
428 /* Don't extend a locked-down transaction! */
429 if (handle->h_transaction->t_state != T_RUNNING) {
430 jbd_debug(3, "denied handle %p %d blocks: "
431 "transaction not running\n", handle, nblocks);
432 goto error_out;
433 }
434
435 spin_lock(&transaction->t_handle_lock);
436 wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks;
437
438 if (wanted > journal->j_max_transaction_buffers) {
439 jbd_debug(3, "denied handle %p %d blocks: "
440 "transaction too large\n", handle, nblocks);
441 goto unlock;
442 }
443
444 if (wanted > __jbd2_log_space_left(journal)) {
445 jbd_debug(3, "denied handle %p %d blocks: "
446 "insufficient log space\n", handle, nblocks);
447 goto unlock;
448 }
449
450 handle->h_buffer_credits += nblocks;
451 atomic_add(nblocks, &transaction->t_outstanding_credits);
452 result = 0;
453
454 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
455 unlock:
456 spin_unlock(&transaction->t_handle_lock);
457 error_out:
458 read_unlock(&journal->j_state_lock);
459 out:
460 return result;
461 }
462
463
464 /**
465 * int jbd2_journal_restart() - restart a handle .
466 * @handle: handle to restart
467 * @nblocks: nr credits requested
468 *
469 * Restart a handle for a multi-transaction filesystem
470 * operation.
471 *
472 * If the jbd2_journal_extend() call above fails to grant new buffer credits
473 * to a running handle, a call to jbd2_journal_restart will commit the
474 * handle's transaction so far and reattach the handle to a new
475 * transaction capabable of guaranteeing the requested number of
476 * credits.
477 */
jbd2__journal_restart(handle_t * handle,int nblocks,gfp_t gfp_mask)478 int jbd2__journal_restart(handle_t *handle, int nblocks, gfp_t gfp_mask)
479 {
480 transaction_t *transaction = handle->h_transaction;
481 journal_t *journal = transaction->t_journal;
482 tid_t tid;
483 int need_to_start, ret;
484
485 /* If we've had an abort of any type, don't even think about
486 * actually doing the restart! */
487 if (is_handle_aborted(handle))
488 return 0;
489
490 /*
491 * First unlink the handle from its current transaction, and start the
492 * commit on that.
493 */
494 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
495 J_ASSERT(journal_current_handle() == handle);
496
497 read_lock(&journal->j_state_lock);
498 spin_lock(&transaction->t_handle_lock);
499 atomic_sub(handle->h_buffer_credits,
500 &transaction->t_outstanding_credits);
501 if (atomic_dec_and_test(&transaction->t_updates))
502 wake_up(&journal->j_wait_updates);
503 tid = transaction->t_tid;
504 spin_unlock(&transaction->t_handle_lock);
505
506 jbd_debug(2, "restarting handle %p\n", handle);
507 need_to_start = !tid_geq(journal->j_commit_request, tid);
508 read_unlock(&journal->j_state_lock);
509 if (need_to_start)
510 jbd2_log_start_commit(journal, tid);
511
512 lock_map_release(&handle->h_lockdep_map);
513 handle->h_buffer_credits = nblocks;
514 ret = start_this_handle(journal, handle, gfp_mask);
515 return ret;
516 }
517 EXPORT_SYMBOL(jbd2__journal_restart);
518
519
jbd2_journal_restart(handle_t * handle,int nblocks)520 int jbd2_journal_restart(handle_t *handle, int nblocks)
521 {
522 return jbd2__journal_restart(handle, nblocks, GFP_NOFS);
523 }
524 EXPORT_SYMBOL(jbd2_journal_restart);
525
526 /**
527 * void jbd2_journal_lock_updates () - establish a transaction barrier.
528 * @journal: Journal to establish a barrier on.
529 *
530 * This locks out any further updates from being started, and blocks
531 * until all existing updates have completed, returning only once the
532 * journal is in a quiescent state with no updates running.
533 *
534 * The journal lock should not be held on entry.
535 */
jbd2_journal_lock_updates(journal_t * journal)536 void jbd2_journal_lock_updates(journal_t *journal)
537 {
538 DEFINE_WAIT(wait);
539
540 write_lock(&journal->j_state_lock);
541 ++journal->j_barrier_count;
542
543 /* Wait until there are no running updates */
544 while (1) {
545 transaction_t *transaction = journal->j_running_transaction;
546
547 if (!transaction)
548 break;
549
550 spin_lock(&transaction->t_handle_lock);
551 prepare_to_wait(&journal->j_wait_updates, &wait,
552 TASK_UNINTERRUPTIBLE);
553 if (!atomic_read(&transaction->t_updates)) {
554 spin_unlock(&transaction->t_handle_lock);
555 finish_wait(&journal->j_wait_updates, &wait);
556 break;
557 }
558 spin_unlock(&transaction->t_handle_lock);
559 write_unlock(&journal->j_state_lock);
560 schedule();
561 finish_wait(&journal->j_wait_updates, &wait);
562 write_lock(&journal->j_state_lock);
563 }
564 write_unlock(&journal->j_state_lock);
565
566 /*
567 * We have now established a barrier against other normal updates, but
568 * we also need to barrier against other jbd2_journal_lock_updates() calls
569 * to make sure that we serialise special journal-locked operations
570 * too.
571 */
572 mutex_lock(&journal->j_barrier);
573 }
574
575 /**
576 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
577 * @journal: Journal to release the barrier on.
578 *
579 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
580 *
581 * Should be called without the journal lock held.
582 */
jbd2_journal_unlock_updates(journal_t * journal)583 void jbd2_journal_unlock_updates (journal_t *journal)
584 {
585 J_ASSERT(journal->j_barrier_count != 0);
586
587 mutex_unlock(&journal->j_barrier);
588 write_lock(&journal->j_state_lock);
589 --journal->j_barrier_count;
590 write_unlock(&journal->j_state_lock);
591 wake_up(&journal->j_wait_transaction_locked);
592 }
593
warn_dirty_buffer(struct buffer_head * bh)594 static void warn_dirty_buffer(struct buffer_head *bh)
595 {
596 char b[BDEVNAME_SIZE];
597
598 printk(KERN_WARNING
599 "JBD2: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
600 "There's a risk of filesystem corruption in case of system "
601 "crash.\n",
602 bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
603 }
604
605 /*
606 * If the buffer is already part of the current transaction, then there
607 * is nothing we need to do. If it is already part of a prior
608 * transaction which we are still committing to disk, then we need to
609 * make sure that we do not overwrite the old copy: we do copy-out to
610 * preserve the copy going to disk. We also account the buffer against
611 * the handle's metadata buffer credits (unless the buffer is already
612 * part of the transaction, that is).
613 *
614 */
615 static int
do_get_write_access(handle_t * handle,struct journal_head * jh,int force_copy)616 do_get_write_access(handle_t *handle, struct journal_head *jh,
617 int force_copy)
618 {
619 struct buffer_head *bh;
620 transaction_t *transaction;
621 journal_t *journal;
622 int error;
623 char *frozen_buffer = NULL;
624 int need_copy = 0;
625
626 if (is_handle_aborted(handle))
627 return -EROFS;
628
629 transaction = handle->h_transaction;
630 journal = transaction->t_journal;
631
632 jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
633
634 JBUFFER_TRACE(jh, "entry");
635 repeat:
636 bh = jh2bh(jh);
637
638 /* @@@ Need to check for errors here at some point. */
639
640 lock_buffer(bh);
641 jbd_lock_bh_state(bh);
642
643 /* We now hold the buffer lock so it is safe to query the buffer
644 * state. Is the buffer dirty?
645 *
646 * If so, there are two possibilities. The buffer may be
647 * non-journaled, and undergoing a quite legitimate writeback.
648 * Otherwise, it is journaled, and we don't expect dirty buffers
649 * in that state (the buffers should be marked JBD_Dirty
650 * instead.) So either the IO is being done under our own
651 * control and this is a bug, or it's a third party IO such as
652 * dump(8) (which may leave the buffer scheduled for read ---
653 * ie. locked but not dirty) or tune2fs (which may actually have
654 * the buffer dirtied, ugh.) */
655
656 if (buffer_dirty(bh)) {
657 /*
658 * First question: is this buffer already part of the current
659 * transaction or the existing committing transaction?
660 */
661 if (jh->b_transaction) {
662 J_ASSERT_JH(jh,
663 jh->b_transaction == transaction ||
664 jh->b_transaction ==
665 journal->j_committing_transaction);
666 if (jh->b_next_transaction)
667 J_ASSERT_JH(jh, jh->b_next_transaction ==
668 transaction);
669 warn_dirty_buffer(bh);
670 }
671 /*
672 * In any case we need to clean the dirty flag and we must
673 * do it under the buffer lock to be sure we don't race
674 * with running write-out.
675 */
676 JBUFFER_TRACE(jh, "Journalling dirty buffer");
677 clear_buffer_dirty(bh);
678 set_buffer_jbddirty(bh);
679 }
680
681 unlock_buffer(bh);
682
683 error = -EROFS;
684 if (is_handle_aborted(handle)) {
685 jbd_unlock_bh_state(bh);
686 goto out;
687 }
688 error = 0;
689
690 /*
691 * The buffer is already part of this transaction if b_transaction or
692 * b_next_transaction points to it
693 */
694 if (jh->b_transaction == transaction ||
695 jh->b_next_transaction == transaction)
696 goto done;
697
698 /*
699 * this is the first time this transaction is touching this buffer,
700 * reset the modified flag
701 */
702 jh->b_modified = 0;
703
704 /*
705 * If there is already a copy-out version of this buffer, then we don't
706 * need to make another one
707 */
708 if (jh->b_frozen_data) {
709 JBUFFER_TRACE(jh, "has frozen data");
710 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
711 jh->b_next_transaction = transaction;
712 goto done;
713 }
714
715 /* Is there data here we need to preserve? */
716
717 if (jh->b_transaction && jh->b_transaction != transaction) {
718 JBUFFER_TRACE(jh, "owned by older transaction");
719 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
720 J_ASSERT_JH(jh, jh->b_transaction ==
721 journal->j_committing_transaction);
722
723 /* There is one case we have to be very careful about.
724 * If the committing transaction is currently writing
725 * this buffer out to disk and has NOT made a copy-out,
726 * then we cannot modify the buffer contents at all
727 * right now. The essence of copy-out is that it is the
728 * extra copy, not the primary copy, which gets
729 * journaled. If the primary copy is already going to
730 * disk then we cannot do copy-out here. */
731
732 if (jh->b_jlist == BJ_Shadow) {
733 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
734 wait_queue_head_t *wqh;
735
736 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
737
738 JBUFFER_TRACE(jh, "on shadow: sleep");
739 jbd_unlock_bh_state(bh);
740 /* commit wakes up all shadow buffers after IO */
741 for ( ; ; ) {
742 prepare_to_wait(wqh, &wait.wait,
743 TASK_UNINTERRUPTIBLE);
744 if (jh->b_jlist != BJ_Shadow)
745 break;
746 schedule();
747 }
748 finish_wait(wqh, &wait.wait);
749 goto repeat;
750 }
751
752 /* Only do the copy if the currently-owning transaction
753 * still needs it. If it is on the Forget list, the
754 * committing transaction is past that stage. The
755 * buffer had better remain locked during the kmalloc,
756 * but that should be true --- we hold the journal lock
757 * still and the buffer is already on the BUF_JOURNAL
758 * list so won't be flushed.
759 *
760 * Subtle point, though: if this is a get_undo_access,
761 * then we will be relying on the frozen_data to contain
762 * the new value of the committed_data record after the
763 * transaction, so we HAVE to force the frozen_data copy
764 * in that case. */
765
766 if (jh->b_jlist != BJ_Forget || force_copy) {
767 JBUFFER_TRACE(jh, "generate frozen data");
768 if (!frozen_buffer) {
769 JBUFFER_TRACE(jh, "allocate memory for buffer");
770 jbd_unlock_bh_state(bh);
771 frozen_buffer =
772 jbd2_alloc(jh2bh(jh)->b_size,
773 GFP_NOFS);
774 if (!frozen_buffer) {
775 printk(KERN_EMERG
776 "%s: OOM for frozen_buffer\n",
777 __func__);
778 JBUFFER_TRACE(jh, "oom!");
779 error = -ENOMEM;
780 jbd_lock_bh_state(bh);
781 goto done;
782 }
783 goto repeat;
784 }
785 jh->b_frozen_data = frozen_buffer;
786 frozen_buffer = NULL;
787 need_copy = 1;
788 }
789 jh->b_next_transaction = transaction;
790 }
791
792
793 /*
794 * Finally, if the buffer is not journaled right now, we need to make
795 * sure it doesn't get written to disk before the caller actually
796 * commits the new data
797 */
798 if (!jh->b_transaction) {
799 JBUFFER_TRACE(jh, "no transaction");
800 J_ASSERT_JH(jh, !jh->b_next_transaction);
801 JBUFFER_TRACE(jh, "file as BJ_Reserved");
802 spin_lock(&journal->j_list_lock);
803 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
804 spin_unlock(&journal->j_list_lock);
805 }
806
807 done:
808 if (need_copy) {
809 struct page *page;
810 int offset;
811 char *source;
812
813 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
814 "Possible IO failure.\n");
815 page = jh2bh(jh)->b_page;
816 offset = offset_in_page(jh2bh(jh)->b_data);
817 source = kmap_atomic(page);
818 /* Fire data frozen trigger just before we copy the data */
819 jbd2_buffer_frozen_trigger(jh, source + offset,
820 jh->b_triggers);
821 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
822 kunmap_atomic(source);
823
824 /*
825 * Now that the frozen data is saved off, we need to store
826 * any matching triggers.
827 */
828 jh->b_frozen_triggers = jh->b_triggers;
829 }
830 jbd_unlock_bh_state(bh);
831
832 /*
833 * If we are about to journal a buffer, then any revoke pending on it is
834 * no longer valid
835 */
836 jbd2_journal_cancel_revoke(handle, jh);
837
838 out:
839 if (unlikely(frozen_buffer)) /* It's usually NULL */
840 jbd2_free(frozen_buffer, bh->b_size);
841
842 JBUFFER_TRACE(jh, "exit");
843 return error;
844 }
845
846 /**
847 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
848 * @handle: transaction to add buffer modifications to
849 * @bh: bh to be used for metadata writes
850 *
851 * Returns an error code or 0 on success.
852 *
853 * In full data journalling mode the buffer may be of type BJ_AsyncData,
854 * because we're write()ing a buffer which is also part of a shared mapping.
855 */
856
jbd2_journal_get_write_access(handle_t * handle,struct buffer_head * bh)857 int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
858 {
859 struct journal_head *jh = jbd2_journal_add_journal_head(bh);
860 int rc;
861
862 /* We do not want to get caught playing with fields which the
863 * log thread also manipulates. Make sure that the buffer
864 * completes any outstanding IO before proceeding. */
865 rc = do_get_write_access(handle, jh, 0);
866 jbd2_journal_put_journal_head(jh);
867 return rc;
868 }
869
870
871 /*
872 * When the user wants to journal a newly created buffer_head
873 * (ie. getblk() returned a new buffer and we are going to populate it
874 * manually rather than reading off disk), then we need to keep the
875 * buffer_head locked until it has been completely filled with new
876 * data. In this case, we should be able to make the assertion that
877 * the bh is not already part of an existing transaction.
878 *
879 * The buffer should already be locked by the caller by this point.
880 * There is no lock ranking violation: it was a newly created,
881 * unlocked buffer beforehand. */
882
883 /**
884 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
885 * @handle: transaction to new buffer to
886 * @bh: new buffer.
887 *
888 * Call this if you create a new bh.
889 */
jbd2_journal_get_create_access(handle_t * handle,struct buffer_head * bh)890 int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
891 {
892 transaction_t *transaction = handle->h_transaction;
893 journal_t *journal = transaction->t_journal;
894 struct journal_head *jh = jbd2_journal_add_journal_head(bh);
895 int err;
896
897 jbd_debug(5, "journal_head %p\n", jh);
898 err = -EROFS;
899 if (is_handle_aborted(handle))
900 goto out;
901 err = 0;
902
903 JBUFFER_TRACE(jh, "entry");
904 /*
905 * The buffer may already belong to this transaction due to pre-zeroing
906 * in the filesystem's new_block code. It may also be on the previous,
907 * committing transaction's lists, but it HAS to be in Forget state in
908 * that case: the transaction must have deleted the buffer for it to be
909 * reused here.
910 */
911 jbd_lock_bh_state(bh);
912 spin_lock(&journal->j_list_lock);
913 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
914 jh->b_transaction == NULL ||
915 (jh->b_transaction == journal->j_committing_transaction &&
916 jh->b_jlist == BJ_Forget)));
917
918 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
919 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
920
921 if (jh->b_transaction == NULL) {
922 /*
923 * Previous jbd2_journal_forget() could have left the buffer
924 * with jbddirty bit set because it was being committed. When
925 * the commit finished, we've filed the buffer for
926 * checkpointing and marked it dirty. Now we are reallocating
927 * the buffer so the transaction freeing it must have
928 * committed and so it's safe to clear the dirty bit.
929 */
930 clear_buffer_dirty(jh2bh(jh));
931 /* first access by this transaction */
932 jh->b_modified = 0;
933
934 JBUFFER_TRACE(jh, "file as BJ_Reserved");
935 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
936 } else if (jh->b_transaction == journal->j_committing_transaction) {
937 /* first access by this transaction */
938 jh->b_modified = 0;
939
940 JBUFFER_TRACE(jh, "set next transaction");
941 jh->b_next_transaction = transaction;
942 }
943 spin_unlock(&journal->j_list_lock);
944 jbd_unlock_bh_state(bh);
945
946 /*
947 * akpm: I added this. ext3_alloc_branch can pick up new indirect
948 * blocks which contain freed but then revoked metadata. We need
949 * to cancel the revoke in case we end up freeing it yet again
950 * and the reallocating as data - this would cause a second revoke,
951 * which hits an assertion error.
952 */
953 JBUFFER_TRACE(jh, "cancelling revoke");
954 jbd2_journal_cancel_revoke(handle, jh);
955 out:
956 jbd2_journal_put_journal_head(jh);
957 return err;
958 }
959
960 /**
961 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with
962 * non-rewindable consequences
963 * @handle: transaction
964 * @bh: buffer to undo
965 *
966 * Sometimes there is a need to distinguish between metadata which has
967 * been committed to disk and that which has not. The ext3fs code uses
968 * this for freeing and allocating space, we have to make sure that we
969 * do not reuse freed space until the deallocation has been committed,
970 * since if we overwrote that space we would make the delete
971 * un-rewindable in case of a crash.
972 *
973 * To deal with that, jbd2_journal_get_undo_access requests write access to a
974 * buffer for parts of non-rewindable operations such as delete
975 * operations on the bitmaps. The journaling code must keep a copy of
976 * the buffer's contents prior to the undo_access call until such time
977 * as we know that the buffer has definitely been committed to disk.
978 *
979 * We never need to know which transaction the committed data is part
980 * of, buffers touched here are guaranteed to be dirtied later and so
981 * will be committed to a new transaction in due course, at which point
982 * we can discard the old committed data pointer.
983 *
984 * Returns error number or 0 on success.
985 */
jbd2_journal_get_undo_access(handle_t * handle,struct buffer_head * bh)986 int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
987 {
988 int err;
989 struct journal_head *jh = jbd2_journal_add_journal_head(bh);
990 char *committed_data = NULL;
991
992 JBUFFER_TRACE(jh, "entry");
993
994 /*
995 * Do this first --- it can drop the journal lock, so we want to
996 * make sure that obtaining the committed_data is done
997 * atomically wrt. completion of any outstanding commits.
998 */
999 err = do_get_write_access(handle, jh, 1);
1000 if (err)
1001 goto out;
1002
1003 repeat:
1004 if (!jh->b_committed_data) {
1005 committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
1006 if (!committed_data) {
1007 printk(KERN_EMERG "%s: No memory for committed data\n",
1008 __func__);
1009 err = -ENOMEM;
1010 goto out;
1011 }
1012 }
1013
1014 jbd_lock_bh_state(bh);
1015 if (!jh->b_committed_data) {
1016 /* Copy out the current buffer contents into the
1017 * preserved, committed copy. */
1018 JBUFFER_TRACE(jh, "generate b_committed data");
1019 if (!committed_data) {
1020 jbd_unlock_bh_state(bh);
1021 goto repeat;
1022 }
1023
1024 jh->b_committed_data = committed_data;
1025 committed_data = NULL;
1026 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
1027 }
1028 jbd_unlock_bh_state(bh);
1029 out:
1030 jbd2_journal_put_journal_head(jh);
1031 if (unlikely(committed_data))
1032 jbd2_free(committed_data, bh->b_size);
1033 return err;
1034 }
1035
1036 /**
1037 * void jbd2_journal_set_triggers() - Add triggers for commit writeout
1038 * @bh: buffer to trigger on
1039 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1040 *
1041 * Set any triggers on this journal_head. This is always safe, because
1042 * triggers for a committing buffer will be saved off, and triggers for
1043 * a running transaction will match the buffer in that transaction.
1044 *
1045 * Call with NULL to clear the triggers.
1046 */
jbd2_journal_set_triggers(struct buffer_head * bh,struct jbd2_buffer_trigger_type * type)1047 void jbd2_journal_set_triggers(struct buffer_head *bh,
1048 struct jbd2_buffer_trigger_type *type)
1049 {
1050 struct journal_head *jh = jbd2_journal_grab_journal_head(bh);
1051
1052 if (WARN_ON(!jh))
1053 return;
1054 jh->b_triggers = type;
1055 jbd2_journal_put_journal_head(jh);
1056 }
1057
jbd2_buffer_frozen_trigger(struct journal_head * jh,void * mapped_data,struct jbd2_buffer_trigger_type * triggers)1058 void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
1059 struct jbd2_buffer_trigger_type *triggers)
1060 {
1061 struct buffer_head *bh = jh2bh(jh);
1062
1063 if (!triggers || !triggers->t_frozen)
1064 return;
1065
1066 triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
1067 }
1068
jbd2_buffer_abort_trigger(struct journal_head * jh,struct jbd2_buffer_trigger_type * triggers)1069 void jbd2_buffer_abort_trigger(struct journal_head *jh,
1070 struct jbd2_buffer_trigger_type *triggers)
1071 {
1072 if (!triggers || !triggers->t_abort)
1073 return;
1074
1075 triggers->t_abort(triggers, jh2bh(jh));
1076 }
1077
1078
1079
1080 /**
1081 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata
1082 * @handle: transaction to add buffer to.
1083 * @bh: buffer to mark
1084 *
1085 * mark dirty metadata which needs to be journaled as part of the current
1086 * transaction.
1087 *
1088 * The buffer must have previously had jbd2_journal_get_write_access()
1089 * called so that it has a valid journal_head attached to the buffer
1090 * head.
1091 *
1092 * The buffer is placed on the transaction's metadata list and is marked
1093 * as belonging to the transaction.
1094 *
1095 * Returns error number or 0 on success.
1096 *
1097 * Special care needs to be taken if the buffer already belongs to the
1098 * current committing transaction (in which case we should have frozen
1099 * data present for that commit). In that case, we don't relink the
1100 * buffer: that only gets done when the old transaction finally
1101 * completes its commit.
1102 */
jbd2_journal_dirty_metadata(handle_t * handle,struct buffer_head * bh)1103 int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1104 {
1105 transaction_t *transaction = handle->h_transaction;
1106 journal_t *journal = transaction->t_journal;
1107 struct journal_head *jh;
1108 int ret = 0;
1109
1110 if (is_handle_aborted(handle))
1111 goto out;
1112 jh = jbd2_journal_grab_journal_head(bh);
1113 if (!jh) {
1114 ret = -EUCLEAN;
1115 goto out;
1116 }
1117 jbd_debug(5, "journal_head %p\n", jh);
1118 JBUFFER_TRACE(jh, "entry");
1119
1120 jbd_lock_bh_state(bh);
1121
1122 if (jh->b_modified == 0) {
1123 /*
1124 * This buffer's got modified and becoming part
1125 * of the transaction. This needs to be done
1126 * once a transaction -bzzz
1127 */
1128 jh->b_modified = 1;
1129 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1130 handle->h_buffer_credits--;
1131 }
1132
1133 /*
1134 * fastpath, to avoid expensive locking. If this buffer is already
1135 * on the running transaction's metadata list there is nothing to do.
1136 * Nobody can take it off again because there is a handle open.
1137 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1138 * result in this test being false, so we go in and take the locks.
1139 */
1140 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1141 JBUFFER_TRACE(jh, "fastpath");
1142 if (unlikely(jh->b_transaction !=
1143 journal->j_running_transaction)) {
1144 printk(KERN_EMERG "JBD: %s: "
1145 "jh->b_transaction (%llu, %p, %u) != "
1146 "journal->j_running_transaction (%p, %u)",
1147 journal->j_devname,
1148 (unsigned long long) bh->b_blocknr,
1149 jh->b_transaction,
1150 jh->b_transaction ? jh->b_transaction->t_tid : 0,
1151 journal->j_running_transaction,
1152 journal->j_running_transaction ?
1153 journal->j_running_transaction->t_tid : 0);
1154 ret = -EINVAL;
1155 }
1156 goto out_unlock_bh;
1157 }
1158
1159 set_buffer_jbddirty(bh);
1160
1161 /*
1162 * Metadata already on the current transaction list doesn't
1163 * need to be filed. Metadata on another transaction's list must
1164 * be committing, and will be refiled once the commit completes:
1165 * leave it alone for now.
1166 */
1167 if (jh->b_transaction != transaction) {
1168 JBUFFER_TRACE(jh, "already on other transaction");
1169 if (unlikely(jh->b_transaction !=
1170 journal->j_committing_transaction)) {
1171 printk(KERN_EMERG "JBD: %s: "
1172 "jh->b_transaction (%llu, %p, %u) != "
1173 "journal->j_committing_transaction (%p, %u)",
1174 journal->j_devname,
1175 (unsigned long long) bh->b_blocknr,
1176 jh->b_transaction,
1177 jh->b_transaction ? jh->b_transaction->t_tid : 0,
1178 journal->j_committing_transaction,
1179 journal->j_committing_transaction ?
1180 journal->j_committing_transaction->t_tid : 0);
1181 ret = -EINVAL;
1182 }
1183 if (unlikely(jh->b_next_transaction != transaction)) {
1184 printk(KERN_EMERG "JBD: %s: "
1185 "jh->b_next_transaction (%llu, %p, %u) != "
1186 "transaction (%p, %u)",
1187 journal->j_devname,
1188 (unsigned long long) bh->b_blocknr,
1189 jh->b_next_transaction,
1190 jh->b_next_transaction ?
1191 jh->b_next_transaction->t_tid : 0,
1192 transaction, transaction->t_tid);
1193 ret = -EINVAL;
1194 }
1195 /* And this case is illegal: we can't reuse another
1196 * transaction's data buffer, ever. */
1197 goto out_unlock_bh;
1198 }
1199
1200 /* That test should have eliminated the following case: */
1201 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1202
1203 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1204 spin_lock(&journal->j_list_lock);
1205 __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1206 spin_unlock(&journal->j_list_lock);
1207 out_unlock_bh:
1208 jbd_unlock_bh_state(bh);
1209 jbd2_journal_put_journal_head(jh);
1210 out:
1211 JBUFFER_TRACE(jh, "exit");
1212 WARN_ON(ret); /* All errors are bugs, so dump the stack */
1213 return ret;
1214 }
1215
1216 /*
1217 * jbd2_journal_release_buffer: undo a get_write_access without any buffer
1218 * updates, if the update decided in the end that it didn't need access.
1219 *
1220 */
1221 void
jbd2_journal_release_buffer(handle_t * handle,struct buffer_head * bh)1222 jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1223 {
1224 BUFFER_TRACE(bh, "entry");
1225 }
1226
1227 /**
1228 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1229 * @handle: transaction handle
1230 * @bh: bh to 'forget'
1231 *
1232 * We can only do the bforget if there are no commits pending against the
1233 * buffer. If the buffer is dirty in the current running transaction we
1234 * can safely unlink it.
1235 *
1236 * bh may not be a journalled buffer at all - it may be a non-JBD
1237 * buffer which came off the hashtable. Check for this.
1238 *
1239 * Decrements bh->b_count by one.
1240 *
1241 * Allow this call even if the handle has aborted --- it may be part of
1242 * the caller's cleanup after an abort.
1243 */
jbd2_journal_forget(handle_t * handle,struct buffer_head * bh)1244 int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1245 {
1246 transaction_t *transaction = handle->h_transaction;
1247 journal_t *journal = transaction->t_journal;
1248 struct journal_head *jh;
1249 int drop_reserve = 0;
1250 int err = 0;
1251 int was_modified = 0;
1252
1253 BUFFER_TRACE(bh, "entry");
1254
1255 jbd_lock_bh_state(bh);
1256 spin_lock(&journal->j_list_lock);
1257
1258 if (!buffer_jbd(bh))
1259 goto not_jbd;
1260 jh = bh2jh(bh);
1261
1262 /* Critical error: attempting to delete a bitmap buffer, maybe?
1263 * Don't do any jbd operations, and return an error. */
1264 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1265 "inconsistent data on disk")) {
1266 err = -EIO;
1267 goto not_jbd;
1268 }
1269
1270 /* keep track of wether or not this transaction modified us */
1271 was_modified = jh->b_modified;
1272
1273 /*
1274 * The buffer's going from the transaction, we must drop
1275 * all references -bzzz
1276 */
1277 jh->b_modified = 0;
1278
1279 if (jh->b_transaction == handle->h_transaction) {
1280 J_ASSERT_JH(jh, !jh->b_frozen_data);
1281
1282 /* If we are forgetting a buffer which is already part
1283 * of this transaction, then we can just drop it from
1284 * the transaction immediately. */
1285 clear_buffer_dirty(bh);
1286 clear_buffer_jbddirty(bh);
1287
1288 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1289
1290 /*
1291 * we only want to drop a reference if this transaction
1292 * modified the buffer
1293 */
1294 if (was_modified)
1295 drop_reserve = 1;
1296
1297 /*
1298 * We are no longer going to journal this buffer.
1299 * However, the commit of this transaction is still
1300 * important to the buffer: the delete that we are now
1301 * processing might obsolete an old log entry, so by
1302 * committing, we can satisfy the buffer's checkpoint.
1303 *
1304 * So, if we have a checkpoint on the buffer, we should
1305 * now refile the buffer on our BJ_Forget list so that
1306 * we know to remove the checkpoint after we commit.
1307 */
1308
1309 if (jh->b_cp_transaction) {
1310 __jbd2_journal_temp_unlink_buffer(jh);
1311 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1312 } else {
1313 __jbd2_journal_unfile_buffer(jh);
1314 if (!buffer_jbd(bh)) {
1315 spin_unlock(&journal->j_list_lock);
1316 jbd_unlock_bh_state(bh);
1317 __bforget(bh);
1318 goto drop;
1319 }
1320 }
1321 } else if (jh->b_transaction) {
1322 J_ASSERT_JH(jh, (jh->b_transaction ==
1323 journal->j_committing_transaction));
1324 /* However, if the buffer is still owned by a prior
1325 * (committing) transaction, we can't drop it yet... */
1326 JBUFFER_TRACE(jh, "belongs to older transaction");
1327 /* ... but we CAN drop it from the new transaction if we
1328 * have also modified it since the original commit. */
1329
1330 if (jh->b_next_transaction) {
1331 J_ASSERT(jh->b_next_transaction == transaction);
1332 jh->b_next_transaction = NULL;
1333
1334 /*
1335 * only drop a reference if this transaction modified
1336 * the buffer
1337 */
1338 if (was_modified)
1339 drop_reserve = 1;
1340 }
1341 }
1342
1343 not_jbd:
1344 spin_unlock(&journal->j_list_lock);
1345 jbd_unlock_bh_state(bh);
1346 __brelse(bh);
1347 drop:
1348 if (drop_reserve) {
1349 /* no need to reserve log space for this block -bzzz */
1350 handle->h_buffer_credits++;
1351 }
1352 return err;
1353 }
1354
1355 /**
1356 * int jbd2_journal_stop() - complete a transaction
1357 * @handle: tranaction to complete.
1358 *
1359 * All done for a particular handle.
1360 *
1361 * There is not much action needed here. We just return any remaining
1362 * buffer credits to the transaction and remove the handle. The only
1363 * complication is that we need to start a commit operation if the
1364 * filesystem is marked for synchronous update.
1365 *
1366 * jbd2_journal_stop itself will not usually return an error, but it may
1367 * do so in unusual circumstances. In particular, expect it to
1368 * return -EIO if a jbd2_journal_abort has been executed since the
1369 * transaction began.
1370 */
jbd2_journal_stop(handle_t * handle)1371 int jbd2_journal_stop(handle_t *handle)
1372 {
1373 transaction_t *transaction = handle->h_transaction;
1374 journal_t *journal = transaction->t_journal;
1375 int err, wait_for_commit = 0;
1376 tid_t tid;
1377 pid_t pid;
1378
1379 J_ASSERT(journal_current_handle() == handle);
1380
1381 if (is_handle_aborted(handle))
1382 err = -EIO;
1383 else {
1384 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
1385 err = 0;
1386 }
1387
1388 if (--handle->h_ref > 0) {
1389 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1390 handle->h_ref);
1391 return err;
1392 }
1393
1394 jbd_debug(4, "Handle %p going down\n", handle);
1395
1396 /*
1397 * Implement synchronous transaction batching. If the handle
1398 * was synchronous, don't force a commit immediately. Let's
1399 * yield and let another thread piggyback onto this
1400 * transaction. Keep doing that while new threads continue to
1401 * arrive. It doesn't cost much - we're about to run a commit
1402 * and sleep on IO anyway. Speeds up many-threaded, many-dir
1403 * operations by 30x or more...
1404 *
1405 * We try and optimize the sleep time against what the
1406 * underlying disk can do, instead of having a static sleep
1407 * time. This is useful for the case where our storage is so
1408 * fast that it is more optimal to go ahead and force a flush
1409 * and wait for the transaction to be committed than it is to
1410 * wait for an arbitrary amount of time for new writers to
1411 * join the transaction. We achieve this by measuring how
1412 * long it takes to commit a transaction, and compare it with
1413 * how long this transaction has been running, and if run time
1414 * < commit time then we sleep for the delta and commit. This
1415 * greatly helps super fast disks that would see slowdowns as
1416 * more threads started doing fsyncs.
1417 *
1418 * But don't do this if this process was the most recent one
1419 * to perform a synchronous write. We do this to detect the
1420 * case where a single process is doing a stream of sync
1421 * writes. No point in waiting for joiners in that case.
1422 */
1423 pid = current->pid;
1424 if (handle->h_sync && journal->j_last_sync_writer != pid) {
1425 u64 commit_time, trans_time;
1426
1427 journal->j_last_sync_writer = pid;
1428
1429 read_lock(&journal->j_state_lock);
1430 commit_time = journal->j_average_commit_time;
1431 read_unlock(&journal->j_state_lock);
1432
1433 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1434 transaction->t_start_time));
1435
1436 commit_time = max_t(u64, commit_time,
1437 1000*journal->j_min_batch_time);
1438 commit_time = min_t(u64, commit_time,
1439 1000*journal->j_max_batch_time);
1440
1441 if (trans_time < commit_time) {
1442 ktime_t expires = ktime_add_ns(ktime_get(),
1443 commit_time);
1444 set_current_state(TASK_UNINTERRUPTIBLE);
1445 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1446 }
1447 }
1448
1449 if (handle->h_sync)
1450 transaction->t_synchronous_commit = 1;
1451 current->journal_info = NULL;
1452 atomic_sub(handle->h_buffer_credits,
1453 &transaction->t_outstanding_credits);
1454
1455 /*
1456 * If the handle is marked SYNC, we need to set another commit
1457 * going! We also want to force a commit if the current
1458 * transaction is occupying too much of the log, or if the
1459 * transaction is too old now.
1460 */
1461 if (handle->h_sync ||
1462 (atomic_read(&transaction->t_outstanding_credits) >
1463 journal->j_max_transaction_buffers) ||
1464 time_after_eq(jiffies, transaction->t_expires)) {
1465 /* Do this even for aborted journals: an abort still
1466 * completes the commit thread, it just doesn't write
1467 * anything to disk. */
1468
1469 jbd_debug(2, "transaction too old, requesting commit for "
1470 "handle %p\n", handle);
1471 /* This is non-blocking */
1472 jbd2_log_start_commit(journal, transaction->t_tid);
1473
1474 /*
1475 * Special case: JBD2_SYNC synchronous updates require us
1476 * to wait for the commit to complete.
1477 */
1478 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1479 wait_for_commit = 1;
1480 }
1481
1482 /*
1483 * Once we drop t_updates, if it goes to zero the transaction
1484 * could start committing on us and eventually disappear. So
1485 * once we do this, we must not dereference transaction
1486 * pointer again.
1487 */
1488 tid = transaction->t_tid;
1489 if (atomic_dec_and_test(&transaction->t_updates)) {
1490 wake_up(&journal->j_wait_updates);
1491 if (journal->j_barrier_count)
1492 wake_up(&journal->j_wait_transaction_locked);
1493 }
1494
1495 if (wait_for_commit)
1496 err = jbd2_log_wait_commit(journal, tid);
1497
1498 lock_map_release(&handle->h_lockdep_map);
1499
1500 jbd2_free_handle(handle);
1501 return err;
1502 }
1503
1504 /**
1505 * int jbd2_journal_force_commit() - force any uncommitted transactions
1506 * @journal: journal to force
1507 *
1508 * For synchronous operations: force any uncommitted transactions
1509 * to disk. May seem kludgy, but it reuses all the handle batching
1510 * code in a very simple manner.
1511 */
jbd2_journal_force_commit(journal_t * journal)1512 int jbd2_journal_force_commit(journal_t *journal)
1513 {
1514 handle_t *handle;
1515 int ret;
1516
1517 handle = jbd2_journal_start(journal, 1);
1518 if (IS_ERR(handle)) {
1519 ret = PTR_ERR(handle);
1520 } else {
1521 handle->h_sync = 1;
1522 ret = jbd2_journal_stop(handle);
1523 }
1524 return ret;
1525 }
1526
1527 /*
1528 *
1529 * List management code snippets: various functions for manipulating the
1530 * transaction buffer lists.
1531 *
1532 */
1533
1534 /*
1535 * Append a buffer to a transaction list, given the transaction's list head
1536 * pointer.
1537 *
1538 * j_list_lock is held.
1539 *
1540 * jbd_lock_bh_state(jh2bh(jh)) is held.
1541 */
1542
1543 static inline void
__blist_add_buffer(struct journal_head ** list,struct journal_head * jh)1544 __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1545 {
1546 if (!*list) {
1547 jh->b_tnext = jh->b_tprev = jh;
1548 *list = jh;
1549 } else {
1550 /* Insert at the tail of the list to preserve order */
1551 struct journal_head *first = *list, *last = first->b_tprev;
1552 jh->b_tprev = last;
1553 jh->b_tnext = first;
1554 last->b_tnext = first->b_tprev = jh;
1555 }
1556 }
1557
1558 /*
1559 * Remove a buffer from a transaction list, given the transaction's list
1560 * head pointer.
1561 *
1562 * Called with j_list_lock held, and the journal may not be locked.
1563 *
1564 * jbd_lock_bh_state(jh2bh(jh)) is held.
1565 */
1566
1567 static inline void
__blist_del_buffer(struct journal_head ** list,struct journal_head * jh)1568 __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1569 {
1570 if (*list == jh) {
1571 *list = jh->b_tnext;
1572 if (*list == jh)
1573 *list = NULL;
1574 }
1575 jh->b_tprev->b_tnext = jh->b_tnext;
1576 jh->b_tnext->b_tprev = jh->b_tprev;
1577 }
1578
1579 /*
1580 * Remove a buffer from the appropriate transaction list.
1581 *
1582 * Note that this function can *change* the value of
1583 * bh->b_transaction->t_buffers, t_forget, t_iobuf_list, t_shadow_list,
1584 * t_log_list or t_reserved_list. If the caller is holding onto a copy of one
1585 * of these pointers, it could go bad. Generally the caller needs to re-read
1586 * the pointer from the transaction_t.
1587 *
1588 * Called under j_list_lock.
1589 */
__jbd2_journal_temp_unlink_buffer(struct journal_head * jh)1590 static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1591 {
1592 struct journal_head **list = NULL;
1593 transaction_t *transaction;
1594 struct buffer_head *bh = jh2bh(jh);
1595
1596 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1597 transaction = jh->b_transaction;
1598 if (transaction)
1599 assert_spin_locked(&transaction->t_journal->j_list_lock);
1600
1601 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1602 if (jh->b_jlist != BJ_None)
1603 J_ASSERT_JH(jh, transaction != NULL);
1604
1605 switch (jh->b_jlist) {
1606 case BJ_None:
1607 return;
1608 case BJ_Metadata:
1609 transaction->t_nr_buffers--;
1610 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1611 list = &transaction->t_buffers;
1612 break;
1613 case BJ_Forget:
1614 list = &transaction->t_forget;
1615 break;
1616 case BJ_IO:
1617 list = &transaction->t_iobuf_list;
1618 break;
1619 case BJ_Shadow:
1620 list = &transaction->t_shadow_list;
1621 break;
1622 case BJ_LogCtl:
1623 list = &transaction->t_log_list;
1624 break;
1625 case BJ_Reserved:
1626 list = &transaction->t_reserved_list;
1627 break;
1628 }
1629
1630 __blist_del_buffer(list, jh);
1631 jh->b_jlist = BJ_None;
1632 if (test_clear_buffer_jbddirty(bh))
1633 mark_buffer_dirty(bh); /* Expose it to the VM */
1634 }
1635
1636 /*
1637 * Remove buffer from all transactions.
1638 *
1639 * Called with bh_state lock and j_list_lock
1640 *
1641 * jh and bh may be already freed when this function returns.
1642 */
__jbd2_journal_unfile_buffer(struct journal_head * jh)1643 static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1644 {
1645 __jbd2_journal_temp_unlink_buffer(jh);
1646 jh->b_transaction = NULL;
1647 jbd2_journal_put_journal_head(jh);
1648 }
1649
jbd2_journal_unfile_buffer(journal_t * journal,struct journal_head * jh)1650 void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1651 {
1652 struct buffer_head *bh = jh2bh(jh);
1653
1654 /* Get reference so that buffer cannot be freed before we unlock it */
1655 get_bh(bh);
1656 jbd_lock_bh_state(bh);
1657 spin_lock(&journal->j_list_lock);
1658 __jbd2_journal_unfile_buffer(jh);
1659 spin_unlock(&journal->j_list_lock);
1660 jbd_unlock_bh_state(bh);
1661 __brelse(bh);
1662 }
1663
1664 /*
1665 * Called from jbd2_journal_try_to_free_buffers().
1666 *
1667 * Called under jbd_lock_bh_state(bh)
1668 */
1669 static void
__journal_try_to_free_buffer(journal_t * journal,struct buffer_head * bh)1670 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1671 {
1672 struct journal_head *jh;
1673
1674 jh = bh2jh(bh);
1675
1676 if (buffer_locked(bh) || buffer_dirty(bh))
1677 goto out;
1678
1679 if (jh->b_next_transaction != NULL)
1680 goto out;
1681
1682 spin_lock(&journal->j_list_lock);
1683 if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
1684 /* written-back checkpointed metadata buffer */
1685 JBUFFER_TRACE(jh, "remove from checkpoint list");
1686 __jbd2_journal_remove_checkpoint(jh);
1687 }
1688 spin_unlock(&journal->j_list_lock);
1689 out:
1690 return;
1691 }
1692
1693 /**
1694 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1695 * @journal: journal for operation
1696 * @page: to try and free
1697 * @gfp_mask: we use the mask to detect how hard should we try to release
1698 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1699 * release the buffers.
1700 *
1701 *
1702 * For all the buffers on this page,
1703 * if they are fully written out ordered data, move them onto BUF_CLEAN
1704 * so try_to_free_buffers() can reap them.
1705 *
1706 * This function returns non-zero if we wish try_to_free_buffers()
1707 * to be called. We do this if the page is releasable by try_to_free_buffers().
1708 * We also do it if the page has locked or dirty buffers and the caller wants
1709 * us to perform sync or async writeout.
1710 *
1711 * This complicates JBD locking somewhat. We aren't protected by the
1712 * BKL here. We wish to remove the buffer from its committing or
1713 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1714 *
1715 * This may *change* the value of transaction_t->t_datalist, so anyone
1716 * who looks at t_datalist needs to lock against this function.
1717 *
1718 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
1719 * buffer. So we need to lock against that. jbd2_journal_dirty_data()
1720 * will come out of the lock with the buffer dirty, which makes it
1721 * ineligible for release here.
1722 *
1723 * Who else is affected by this? hmm... Really the only contender
1724 * is do_get_write_access() - it could be looking at the buffer while
1725 * journal_try_to_free_buffer() is changing its state. But that
1726 * cannot happen because we never reallocate freed data as metadata
1727 * while the data is part of a transaction. Yes?
1728 *
1729 * Return 0 on failure, 1 on success
1730 */
jbd2_journal_try_to_free_buffers(journal_t * journal,struct page * page,gfp_t gfp_mask)1731 int jbd2_journal_try_to_free_buffers(journal_t *journal,
1732 struct page *page, gfp_t gfp_mask)
1733 {
1734 struct buffer_head *head;
1735 struct buffer_head *bh;
1736 int ret = 0;
1737
1738 J_ASSERT(PageLocked(page));
1739
1740 head = page_buffers(page);
1741 bh = head;
1742 do {
1743 struct journal_head *jh;
1744
1745 /*
1746 * We take our own ref against the journal_head here to avoid
1747 * having to add tons of locking around each instance of
1748 * jbd2_journal_put_journal_head().
1749 */
1750 jh = jbd2_journal_grab_journal_head(bh);
1751 if (!jh)
1752 continue;
1753
1754 jbd_lock_bh_state(bh);
1755 __journal_try_to_free_buffer(journal, bh);
1756 jbd2_journal_put_journal_head(jh);
1757 jbd_unlock_bh_state(bh);
1758 if (buffer_jbd(bh))
1759 goto busy;
1760 } while ((bh = bh->b_this_page) != head);
1761
1762 ret = try_to_free_buffers(page);
1763
1764 busy:
1765 return ret;
1766 }
1767
1768 /*
1769 * This buffer is no longer needed. If it is on an older transaction's
1770 * checkpoint list we need to record it on this transaction's forget list
1771 * to pin this buffer (and hence its checkpointing transaction) down until
1772 * this transaction commits. If the buffer isn't on a checkpoint list, we
1773 * release it.
1774 * Returns non-zero if JBD no longer has an interest in the buffer.
1775 *
1776 * Called under j_list_lock.
1777 *
1778 * Called under jbd_lock_bh_state(bh).
1779 */
__dispose_buffer(struct journal_head * jh,transaction_t * transaction)1780 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1781 {
1782 int may_free = 1;
1783 struct buffer_head *bh = jh2bh(jh);
1784
1785 if (jh->b_cp_transaction) {
1786 JBUFFER_TRACE(jh, "on running+cp transaction");
1787 __jbd2_journal_temp_unlink_buffer(jh);
1788 /*
1789 * We don't want to write the buffer anymore, clear the
1790 * bit so that we don't confuse checks in
1791 * __journal_file_buffer
1792 */
1793 clear_buffer_dirty(bh);
1794 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1795 may_free = 0;
1796 } else {
1797 JBUFFER_TRACE(jh, "on running transaction");
1798 __jbd2_journal_unfile_buffer(jh);
1799 }
1800 return may_free;
1801 }
1802
1803 /*
1804 * jbd2_journal_invalidatepage
1805 *
1806 * This code is tricky. It has a number of cases to deal with.
1807 *
1808 * There are two invariants which this code relies on:
1809 *
1810 * i_size must be updated on disk before we start calling invalidatepage on the
1811 * data.
1812 *
1813 * This is done in ext3 by defining an ext3_setattr method which
1814 * updates i_size before truncate gets going. By maintaining this
1815 * invariant, we can be sure that it is safe to throw away any buffers
1816 * attached to the current transaction: once the transaction commits,
1817 * we know that the data will not be needed.
1818 *
1819 * Note however that we can *not* throw away data belonging to the
1820 * previous, committing transaction!
1821 *
1822 * Any disk blocks which *are* part of the previous, committing
1823 * transaction (and which therefore cannot be discarded immediately) are
1824 * not going to be reused in the new running transaction
1825 *
1826 * The bitmap committed_data images guarantee this: any block which is
1827 * allocated in one transaction and removed in the next will be marked
1828 * as in-use in the committed_data bitmap, so cannot be reused until
1829 * the next transaction to delete the block commits. This means that
1830 * leaving committing buffers dirty is quite safe: the disk blocks
1831 * cannot be reallocated to a different file and so buffer aliasing is
1832 * not possible.
1833 *
1834 *
1835 * The above applies mainly to ordered data mode. In writeback mode we
1836 * don't make guarantees about the order in which data hits disk --- in
1837 * particular we don't guarantee that new dirty data is flushed before
1838 * transaction commit --- so it is always safe just to discard data
1839 * immediately in that mode. --sct
1840 */
1841
1842 /*
1843 * The journal_unmap_buffer helper function returns zero if the buffer
1844 * concerned remains pinned as an anonymous buffer belonging to an older
1845 * transaction.
1846 *
1847 * We're outside-transaction here. Either or both of j_running_transaction
1848 * and j_committing_transaction may be NULL.
1849 */
journal_unmap_buffer(journal_t * journal,struct buffer_head * bh)1850 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1851 {
1852 transaction_t *transaction;
1853 struct journal_head *jh;
1854 int may_free = 1;
1855 int ret;
1856
1857 BUFFER_TRACE(bh, "entry");
1858
1859 /*
1860 * It is safe to proceed here without the j_list_lock because the
1861 * buffers cannot be stolen by try_to_free_buffers as long as we are
1862 * holding the page lock. --sct
1863 */
1864
1865 if (!buffer_jbd(bh))
1866 goto zap_buffer_unlocked;
1867
1868 /* OK, we have data buffer in journaled mode */
1869 write_lock(&journal->j_state_lock);
1870 jbd_lock_bh_state(bh);
1871 spin_lock(&journal->j_list_lock);
1872
1873 jh = jbd2_journal_grab_journal_head(bh);
1874 if (!jh)
1875 goto zap_buffer_no_jh;
1876
1877 /*
1878 * We cannot remove the buffer from checkpoint lists until the
1879 * transaction adding inode to orphan list (let's call it T)
1880 * is committed. Otherwise if the transaction changing the
1881 * buffer would be cleaned from the journal before T is
1882 * committed, a crash will cause that the correct contents of
1883 * the buffer will be lost. On the other hand we have to
1884 * clear the buffer dirty bit at latest at the moment when the
1885 * transaction marking the buffer as freed in the filesystem
1886 * structures is committed because from that moment on the
1887 * buffer can be reallocated and used by a different page.
1888 * Since the block hasn't been freed yet but the inode has
1889 * already been added to orphan list, it is safe for us to add
1890 * the buffer to BJ_Forget list of the newest transaction.
1891 */
1892 transaction = jh->b_transaction;
1893 if (transaction == NULL) {
1894 /* First case: not on any transaction. If it
1895 * has no checkpoint link, then we can zap it:
1896 * it's a writeback-mode buffer so we don't care
1897 * if it hits disk safely. */
1898 if (!jh->b_cp_transaction) {
1899 JBUFFER_TRACE(jh, "not on any transaction: zap");
1900 goto zap_buffer;
1901 }
1902
1903 if (!buffer_dirty(bh)) {
1904 /* bdflush has written it. We can drop it now */
1905 goto zap_buffer;
1906 }
1907
1908 /* OK, it must be in the journal but still not
1909 * written fully to disk: it's metadata or
1910 * journaled data... */
1911
1912 if (journal->j_running_transaction) {
1913 /* ... and once the current transaction has
1914 * committed, the buffer won't be needed any
1915 * longer. */
1916 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1917 ret = __dispose_buffer(jh,
1918 journal->j_running_transaction);
1919 jbd2_journal_put_journal_head(jh);
1920 spin_unlock(&journal->j_list_lock);
1921 jbd_unlock_bh_state(bh);
1922 write_unlock(&journal->j_state_lock);
1923 return ret;
1924 } else {
1925 /* There is no currently-running transaction. So the
1926 * orphan record which we wrote for this file must have
1927 * passed into commit. We must attach this buffer to
1928 * the committing transaction, if it exists. */
1929 if (journal->j_committing_transaction) {
1930 JBUFFER_TRACE(jh, "give to committing trans");
1931 ret = __dispose_buffer(jh,
1932 journal->j_committing_transaction);
1933 jbd2_journal_put_journal_head(jh);
1934 spin_unlock(&journal->j_list_lock);
1935 jbd_unlock_bh_state(bh);
1936 write_unlock(&journal->j_state_lock);
1937 return ret;
1938 } else {
1939 /* The orphan record's transaction has
1940 * committed. We can cleanse this buffer */
1941 clear_buffer_jbddirty(bh);
1942 goto zap_buffer;
1943 }
1944 }
1945 } else if (transaction == journal->j_committing_transaction) {
1946 JBUFFER_TRACE(jh, "on committing transaction");
1947 /*
1948 * The buffer is committing, we simply cannot touch
1949 * it. So we just set j_next_transaction to the
1950 * running transaction (if there is one) and mark
1951 * buffer as freed so that commit code knows it should
1952 * clear dirty bits when it is done with the buffer.
1953 */
1954 set_buffer_freed(bh);
1955 if (journal->j_running_transaction && buffer_jbddirty(bh))
1956 jh->b_next_transaction = journal->j_running_transaction;
1957 jbd2_journal_put_journal_head(jh);
1958 spin_unlock(&journal->j_list_lock);
1959 jbd_unlock_bh_state(bh);
1960 write_unlock(&journal->j_state_lock);
1961 return 0;
1962 } else {
1963 /* Good, the buffer belongs to the running transaction.
1964 * We are writing our own transaction's data, not any
1965 * previous one's, so it is safe to throw it away
1966 * (remember that we expect the filesystem to have set
1967 * i_size already for this truncate so recovery will not
1968 * expose the disk blocks we are discarding here.) */
1969 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1970 JBUFFER_TRACE(jh, "on running transaction");
1971 may_free = __dispose_buffer(jh, transaction);
1972 }
1973
1974 zap_buffer:
1975 jbd2_journal_put_journal_head(jh);
1976 zap_buffer_no_jh:
1977 spin_unlock(&journal->j_list_lock);
1978 jbd_unlock_bh_state(bh);
1979 write_unlock(&journal->j_state_lock);
1980 zap_buffer_unlocked:
1981 clear_buffer_dirty(bh);
1982 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1983 clear_buffer_mapped(bh);
1984 clear_buffer_req(bh);
1985 clear_buffer_new(bh);
1986 clear_buffer_delay(bh);
1987 clear_buffer_unwritten(bh);
1988 bh->b_bdev = NULL;
1989 return may_free;
1990 }
1991
1992 /**
1993 * void jbd2_journal_invalidatepage()
1994 * @journal: journal to use for flush...
1995 * @page: page to flush
1996 * @offset: length of page to invalidate.
1997 *
1998 * Reap page buffers containing data after offset in page.
1999 *
2000 */
jbd2_journal_invalidatepage(journal_t * journal,struct page * page,unsigned long offset)2001 void jbd2_journal_invalidatepage(journal_t *journal,
2002 struct page *page,
2003 unsigned long offset)
2004 {
2005 struct buffer_head *head, *bh, *next;
2006 unsigned int curr_off = 0;
2007 int may_free = 1;
2008
2009 if (!PageLocked(page))
2010 BUG();
2011 if (!page_has_buffers(page))
2012 return;
2013
2014 /* We will potentially be playing with lists other than just the
2015 * data lists (especially for journaled data mode), so be
2016 * cautious in our locking. */
2017
2018 head = bh = page_buffers(page);
2019 do {
2020 unsigned int next_off = curr_off + bh->b_size;
2021 next = bh->b_this_page;
2022
2023 if (offset <= curr_off) {
2024 /* This block is wholly outside the truncation point */
2025 lock_buffer(bh);
2026 may_free &= journal_unmap_buffer(journal, bh);
2027 unlock_buffer(bh);
2028 }
2029 curr_off = next_off;
2030 bh = next;
2031
2032 } while (bh != head);
2033
2034 if (!offset) {
2035 if (may_free && try_to_free_buffers(page))
2036 J_ASSERT(!page_has_buffers(page));
2037 }
2038 }
2039
2040 /*
2041 * File a buffer on the given transaction list.
2042 */
__jbd2_journal_file_buffer(struct journal_head * jh,transaction_t * transaction,int jlist)2043 void __jbd2_journal_file_buffer(struct journal_head *jh,
2044 transaction_t *transaction, int jlist)
2045 {
2046 struct journal_head **list = NULL;
2047 int was_dirty = 0;
2048 struct buffer_head *bh = jh2bh(jh);
2049
2050 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2051 assert_spin_locked(&transaction->t_journal->j_list_lock);
2052
2053 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2054 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2055 jh->b_transaction == NULL);
2056
2057 if (jh->b_transaction && jh->b_jlist == jlist)
2058 return;
2059
2060 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
2061 jlist == BJ_Shadow || jlist == BJ_Forget) {
2062 /*
2063 * For metadata buffers, we track dirty bit in buffer_jbddirty
2064 * instead of buffer_dirty. We should not see a dirty bit set
2065 * here because we clear it in do_get_write_access but e.g.
2066 * tune2fs can modify the sb and set the dirty bit at any time
2067 * so we try to gracefully handle that.
2068 */
2069 if (buffer_dirty(bh))
2070 warn_dirty_buffer(bh);
2071 if (test_clear_buffer_dirty(bh) ||
2072 test_clear_buffer_jbddirty(bh))
2073 was_dirty = 1;
2074 }
2075
2076 if (jh->b_transaction)
2077 __jbd2_journal_temp_unlink_buffer(jh);
2078 else
2079 jbd2_journal_grab_journal_head(bh);
2080 jh->b_transaction = transaction;
2081
2082 switch (jlist) {
2083 case BJ_None:
2084 J_ASSERT_JH(jh, !jh->b_committed_data);
2085 J_ASSERT_JH(jh, !jh->b_frozen_data);
2086 return;
2087 case BJ_Metadata:
2088 transaction->t_nr_buffers++;
2089 list = &transaction->t_buffers;
2090 break;
2091 case BJ_Forget:
2092 list = &transaction->t_forget;
2093 break;
2094 case BJ_IO:
2095 list = &transaction->t_iobuf_list;
2096 break;
2097 case BJ_Shadow:
2098 list = &transaction->t_shadow_list;
2099 break;
2100 case BJ_LogCtl:
2101 list = &transaction->t_log_list;
2102 break;
2103 case BJ_Reserved:
2104 list = &transaction->t_reserved_list;
2105 break;
2106 }
2107
2108 __blist_add_buffer(list, jh);
2109 jh->b_jlist = jlist;
2110
2111 if (was_dirty)
2112 set_buffer_jbddirty(bh);
2113 }
2114
jbd2_journal_file_buffer(struct journal_head * jh,transaction_t * transaction,int jlist)2115 void jbd2_journal_file_buffer(struct journal_head *jh,
2116 transaction_t *transaction, int jlist)
2117 {
2118 jbd_lock_bh_state(jh2bh(jh));
2119 spin_lock(&transaction->t_journal->j_list_lock);
2120 __jbd2_journal_file_buffer(jh, transaction, jlist);
2121 spin_unlock(&transaction->t_journal->j_list_lock);
2122 jbd_unlock_bh_state(jh2bh(jh));
2123 }
2124
2125 /*
2126 * Remove a buffer from its current buffer list in preparation for
2127 * dropping it from its current transaction entirely. If the buffer has
2128 * already started to be used by a subsequent transaction, refile the
2129 * buffer on that transaction's metadata list.
2130 *
2131 * Called under j_list_lock
2132 * Called under jbd_lock_bh_state(jh2bh(jh))
2133 *
2134 * jh and bh may be already free when this function returns
2135 */
__jbd2_journal_refile_buffer(struct journal_head * jh)2136 void __jbd2_journal_refile_buffer(struct journal_head *jh)
2137 {
2138 int was_dirty, jlist;
2139 struct buffer_head *bh = jh2bh(jh);
2140
2141 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2142 if (jh->b_transaction)
2143 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2144
2145 /* If the buffer is now unused, just drop it. */
2146 if (jh->b_next_transaction == NULL) {
2147 __jbd2_journal_unfile_buffer(jh);
2148 return;
2149 }
2150
2151 /*
2152 * It has been modified by a later transaction: add it to the new
2153 * transaction's metadata list.
2154 */
2155
2156 was_dirty = test_clear_buffer_jbddirty(bh);
2157 __jbd2_journal_temp_unlink_buffer(jh);
2158 /*
2159 * We set b_transaction here because b_next_transaction will inherit
2160 * our jh reference and thus __jbd2_journal_file_buffer() must not
2161 * take a new one.
2162 */
2163 jh->b_transaction = jh->b_next_transaction;
2164 jh->b_next_transaction = NULL;
2165 if (buffer_freed(bh))
2166 jlist = BJ_Forget;
2167 else if (jh->b_modified)
2168 jlist = BJ_Metadata;
2169 else
2170 jlist = BJ_Reserved;
2171 __jbd2_journal_file_buffer(jh, jh->b_transaction, jlist);
2172 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2173
2174 if (was_dirty)
2175 set_buffer_jbddirty(bh);
2176 }
2177
2178 /*
2179 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
2180 * bh reference so that we can safely unlock bh.
2181 *
2182 * The jh and bh may be freed by this call.
2183 */
jbd2_journal_refile_buffer(journal_t * journal,struct journal_head * jh)2184 void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2185 {
2186 struct buffer_head *bh = jh2bh(jh);
2187
2188 /* Get reference so that buffer cannot be freed before we unlock it */
2189 get_bh(bh);
2190 jbd_lock_bh_state(bh);
2191 spin_lock(&journal->j_list_lock);
2192 __jbd2_journal_refile_buffer(jh);
2193 jbd_unlock_bh_state(bh);
2194 spin_unlock(&journal->j_list_lock);
2195 __brelse(bh);
2196 }
2197
2198 /*
2199 * File inode in the inode list of the handle's transaction
2200 */
jbd2_journal_file_inode(handle_t * handle,struct jbd2_inode * jinode)2201 int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode)
2202 {
2203 transaction_t *transaction = handle->h_transaction;
2204 journal_t *journal = transaction->t_journal;
2205
2206 if (is_handle_aborted(handle))
2207 return -EIO;
2208
2209 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
2210 transaction->t_tid);
2211
2212 /*
2213 * First check whether inode isn't already on the transaction's
2214 * lists without taking the lock. Note that this check is safe
2215 * without the lock as we cannot race with somebody removing inode
2216 * from the transaction. The reason is that we remove inode from the
2217 * transaction only in journal_release_jbd_inode() and when we commit
2218 * the transaction. We are guarded from the first case by holding
2219 * a reference to the inode. We are safe against the second case
2220 * because if jinode->i_transaction == transaction, commit code
2221 * cannot touch the transaction because we hold reference to it,
2222 * and if jinode->i_next_transaction == transaction, commit code
2223 * will only file the inode where we want it.
2224 */
2225 if (jinode->i_transaction == transaction ||
2226 jinode->i_next_transaction == transaction)
2227 return 0;
2228
2229 spin_lock(&journal->j_list_lock);
2230
2231 if (jinode->i_transaction == transaction ||
2232 jinode->i_next_transaction == transaction)
2233 goto done;
2234
2235 /*
2236 * We only ever set this variable to 1 so the test is safe. Since
2237 * t_need_data_flush is likely to be set, we do the test to save some
2238 * cacheline bouncing
2239 */
2240 if (!transaction->t_need_data_flush)
2241 transaction->t_need_data_flush = 1;
2242 /* On some different transaction's list - should be
2243 * the committing one */
2244 if (jinode->i_transaction) {
2245 J_ASSERT(jinode->i_next_transaction == NULL);
2246 J_ASSERT(jinode->i_transaction ==
2247 journal->j_committing_transaction);
2248 jinode->i_next_transaction = transaction;
2249 goto done;
2250 }
2251 /* Not on any transaction list... */
2252 J_ASSERT(!jinode->i_next_transaction);
2253 jinode->i_transaction = transaction;
2254 list_add(&jinode->i_list, &transaction->t_inode_list);
2255 done:
2256 spin_unlock(&journal->j_list_lock);
2257
2258 return 0;
2259 }
2260
2261 /*
2262 * File truncate and transaction commit interact with each other in a
2263 * non-trivial way. If a transaction writing data block A is
2264 * committing, we cannot discard the data by truncate until we have
2265 * written them. Otherwise if we crashed after the transaction with
2266 * write has committed but before the transaction with truncate has
2267 * committed, we could see stale data in block A. This function is a
2268 * helper to solve this problem. It starts writeout of the truncated
2269 * part in case it is in the committing transaction.
2270 *
2271 * Filesystem code must call this function when inode is journaled in
2272 * ordered mode before truncation happens and after the inode has been
2273 * placed on orphan list with the new inode size. The second condition
2274 * avoids the race that someone writes new data and we start
2275 * committing the transaction after this function has been called but
2276 * before a transaction for truncate is started (and furthermore it
2277 * allows us to optimize the case where the addition to orphan list
2278 * happens in the same transaction as write --- we don't have to write
2279 * any data in such case).
2280 */
jbd2_journal_begin_ordered_truncate(journal_t * journal,struct jbd2_inode * jinode,loff_t new_size)2281 int jbd2_journal_begin_ordered_truncate(journal_t *journal,
2282 struct jbd2_inode *jinode,
2283 loff_t new_size)
2284 {
2285 transaction_t *inode_trans, *commit_trans;
2286 int ret = 0;
2287
2288 /* This is a quick check to avoid locking if not necessary */
2289 if (!jinode->i_transaction)
2290 goto out;
2291 /* Locks are here just to force reading of recent values, it is
2292 * enough that the transaction was not committing before we started
2293 * a transaction adding the inode to orphan list */
2294 read_lock(&journal->j_state_lock);
2295 commit_trans = journal->j_committing_transaction;
2296 read_unlock(&journal->j_state_lock);
2297 spin_lock(&journal->j_list_lock);
2298 inode_trans = jinode->i_transaction;
2299 spin_unlock(&journal->j_list_lock);
2300 if (inode_trans == commit_trans) {
2301 ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping,
2302 new_size, LLONG_MAX);
2303 if (ret)
2304 jbd2_journal_abort(journal, ret);
2305 }
2306 out:
2307 return ret;
2308 }
2309