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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * linux/fs/jbd2/transaction.c
4 *
5 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
6 *
7 * Copyright 1998 Red Hat corp --- All Rights Reserved
8 *
9 * Generic filesystem transaction handling code; part of the ext2fs
10 * journaling system.
11 *
12 * This file manages transactions (compound commits managed by the
13 * journaling code) and handles (individual atomic operations by the
14 * filesystem).
15 */
16
17#include <linux/time.h>
18#include <linux/fs.h>
19#include <linux/jbd2.h>
20#include <linux/errno.h>
21#include <linux/slab.h>
22#include <linux/timer.h>
23#include <linux/mm.h>
24#include <linux/highmem.h>
25#include <linux/hrtimer.h>
26#include <linux/backing-dev.h>
27#include <linux/bug.h>
28#include <linux/module.h>
29#include <linux/sched/mm.h>
30
31#include <trace/events/jbd2.h>
32
33static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
34static void __jbd2_journal_unfile_buffer(struct journal_head *jh);
35
36static struct kmem_cache *transaction_cache;
37int __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
50void jbd2_journal_destroy_transaction_cache(void)
51{
52 if (transaction_cache) {
53 kmem_cache_destroy(transaction_cache);
54 transaction_cache = NULL;
55 }
56}
57
58void 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
80static transaction_t *
81jbd2_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,
91 atomic_read(&journal->j_reserved_credits));
92 atomic_set(&transaction->t_handle_count, 0);
93 INIT_LIST_HEAD(&transaction->t_inode_list);
94 INIT_LIST_HEAD(&transaction->t_private_list);
95
96 /* Set up the commit timer for the new transaction. */
97 journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires);
98 add_timer(&journal->j_commit_timer);
99
100 J_ASSERT(journal->j_running_transaction == NULL);
101 journal->j_running_transaction = transaction;
102 transaction->t_max_wait = 0;
103 transaction->t_start = jiffies;
104 transaction->t_requested = 0;
105
106 return transaction;
107}
108
109/*
110 * Handle management.
111 *
112 * A handle_t is an object which represents a single atomic update to a
113 * filesystem, and which tracks all of the modifications which form part
114 * of that one update.
115 */
116
117/*
118 * Update transaction's maximum wait time, if debugging is enabled.
119 *
120 * In order for t_max_wait to be reliable, it must be protected by a
121 * lock. But doing so will mean that start_this_handle() can not be
122 * run in parallel on SMP systems, which limits our scalability. So
123 * unless debugging is enabled, we no longer update t_max_wait, which
124 * means that maximum wait time reported by the jbd2_run_stats
125 * tracepoint will always be zero.
126 */
127static inline void update_t_max_wait(transaction_t *transaction,
128 unsigned long ts)
129{
130#ifdef CONFIG_JBD2_DEBUG
131 if (jbd2_journal_enable_debug &&
132 time_after(transaction->t_start, ts)) {
133 ts = jbd2_time_diff(ts, transaction->t_start);
134 spin_lock(&transaction->t_handle_lock);
135 if (ts > transaction->t_max_wait)
136 transaction->t_max_wait = ts;
137 spin_unlock(&transaction->t_handle_lock);
138 }
139#endif
140}
141
142/*
143 * Wait until running transaction passes T_LOCKED state. Also starts the commit
144 * if needed. The function expects running transaction to exist and releases
145 * j_state_lock.
146 */
147static void wait_transaction_locked(journal_t *journal)
148 __releases(journal->j_state_lock)
149{
150 DEFINE_WAIT(wait);
151 int need_to_start;
152 tid_t tid = journal->j_running_transaction->t_tid;
153
154 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
155 TASK_UNINTERRUPTIBLE);
156 need_to_start = !tid_geq(journal->j_commit_request, tid);
157 read_unlock(&journal->j_state_lock);
158 if (need_to_start)
159 jbd2_log_start_commit(journal, tid);
160 jbd2_might_wait_for_commit(journal);
161 schedule();
162 finish_wait(&journal->j_wait_transaction_locked, &wait);
163}
164
165static void sub_reserved_credits(journal_t *journal, int blocks)
166{
167 atomic_sub(blocks, &journal->j_reserved_credits);
168 wake_up(&journal->j_wait_reserved);
169}
170
171/*
172 * Wait until we can add credits for handle to the running transaction. Called
173 * with j_state_lock held for reading. Returns 0 if handle joined the running
174 * transaction. Returns 1 if we had to wait, j_state_lock is dropped, and
175 * caller must retry.
176 */
177static int add_transaction_credits(journal_t *journal, int blocks,
178 int rsv_blocks)
179{
180 transaction_t *t = journal->j_running_transaction;
181 int needed;
182 int total = blocks + rsv_blocks;
183
184 /*
185 * If the current transaction is locked down for commit, wait
186 * for the lock to be released.
187 */
188 if (t->t_state == T_LOCKED) {
189 wait_transaction_locked(journal);
190 return 1;
191 }
192
193 /*
194 * If there is not enough space left in the log to write all
195 * potential buffers requested by this operation, we need to
196 * stall pending a log checkpoint to free some more log space.
197 */
198 needed = atomic_add_return(total, &t->t_outstanding_credits);
199 if (needed > journal->j_max_transaction_buffers) {
200 /*
201 * If the current transaction is already too large,
202 * then start to commit it: we can then go back and
203 * attach this handle to a new transaction.
204 */
205 atomic_sub(total, &t->t_outstanding_credits);
206
207 /*
208 * Is the number of reserved credits in the current transaction too
209 * big to fit this handle? Wait until reserved credits are freed.
210 */
211 if (atomic_read(&journal->j_reserved_credits) + total >
212 journal->j_max_transaction_buffers) {
213 read_unlock(&journal->j_state_lock);
214 jbd2_might_wait_for_commit(journal);
215 wait_event(journal->j_wait_reserved,
216 atomic_read(&journal->j_reserved_credits) + total <=
217 journal->j_max_transaction_buffers);
218 return 1;
219 }
220
221 wait_transaction_locked(journal);
222 return 1;
223 }
224
225 /*
226 * The commit code assumes that it can get enough log space
227 * without forcing a checkpoint. This is *critical* for
228 * correctness: a checkpoint of a buffer which is also
229 * associated with a committing transaction creates a deadlock,
230 * so commit simply cannot force through checkpoints.
231 *
232 * We must therefore ensure the necessary space in the journal
233 * *before* starting to dirty potentially checkpointed buffers
234 * in the new transaction.
235 */
236 if (jbd2_log_space_left(journal) < jbd2_space_needed(journal)) {
237 atomic_sub(total, &t->t_outstanding_credits);
238 read_unlock(&journal->j_state_lock);
239 jbd2_might_wait_for_commit(journal);
240 write_lock(&journal->j_state_lock);
241 if (jbd2_log_space_left(journal) < jbd2_space_needed(journal))
242 __jbd2_log_wait_for_space(journal);
243 write_unlock(&journal->j_state_lock);
244 return 1;
245 }
246
247 /* No reservation? We are done... */
248 if (!rsv_blocks)
249 return 0;
250
251 needed = atomic_add_return(rsv_blocks, &journal->j_reserved_credits);
252 /* We allow at most half of a transaction to be reserved */
253 if (needed > journal->j_max_transaction_buffers / 2) {
254 sub_reserved_credits(journal, rsv_blocks);
255 atomic_sub(total, &t->t_outstanding_credits);
256 read_unlock(&journal->j_state_lock);
257 jbd2_might_wait_for_commit(journal);
258 wait_event(journal->j_wait_reserved,
259 atomic_read(&journal->j_reserved_credits) + rsv_blocks
260 <= journal->j_max_transaction_buffers / 2);
261 return 1;
262 }
263 return 0;
264}
265
266/*
267 * start_this_handle: Given a handle, deal with any locking or stalling
268 * needed to make sure that there is enough journal space for the handle
269 * to begin. Attach the handle to a transaction and set up the
270 * transaction's buffer credits.
271 */
272
273static int start_this_handle(journal_t *journal, handle_t *handle,
274 gfp_t gfp_mask)
275{
276 transaction_t *transaction, *new_transaction = NULL;
277 int blocks = handle->h_buffer_credits;
278 int rsv_blocks = 0;
279 unsigned long ts = jiffies;
280
281 if (handle->h_rsv_handle)
282 rsv_blocks = handle->h_rsv_handle->h_buffer_credits;
283
284 /*
285 * Limit the number of reserved credits to 1/2 of maximum transaction
286 * size and limit the number of total credits to not exceed maximum
287 * transaction size per operation.
288 */
289 if ((rsv_blocks > journal->j_max_transaction_buffers / 2) ||
290 (rsv_blocks + blocks > journal->j_max_transaction_buffers)) {
291 printk(KERN_ERR "JBD2: %s wants too many credits "
292 "credits:%d rsv_credits:%d max:%d\n",
293 current->comm, blocks, rsv_blocks,
294 journal->j_max_transaction_buffers);
295 WARN_ON(1);
296 return -ENOSPC;
297 }
298
299alloc_transaction:
300 if (!journal->j_running_transaction) {
301 /*
302 * If __GFP_FS is not present, then we may be being called from
303 * inside the fs writeback layer, so we MUST NOT fail.
304 */
305 if ((gfp_mask & __GFP_FS) == 0)
306 gfp_mask |= __GFP_NOFAIL;
307 new_transaction = kmem_cache_zalloc(transaction_cache,
308 gfp_mask);
309 if (!new_transaction)
310 return -ENOMEM;
311 }
312
313 jbd_debug(3, "New handle %p going live.\n", handle);
314
315 /*
316 * We need to hold j_state_lock until t_updates has been incremented,
317 * for proper journal barrier handling
318 */
319repeat:
320 read_lock(&journal->j_state_lock);
321 BUG_ON(journal->j_flags & JBD2_UNMOUNT);
322 if (is_journal_aborted(journal) ||
323 (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
324 read_unlock(&journal->j_state_lock);
325 jbd2_journal_free_transaction(new_transaction);
326 return -EROFS;
327 }
328
329 /*
330 * Wait on the journal's transaction barrier if necessary. Specifically
331 * we allow reserved handles to proceed because otherwise commit could
332 * deadlock on page writeback not being able to complete.
333 */
334 if (!handle->h_reserved && journal->j_barrier_count) {
335 read_unlock(&journal->j_state_lock);
336 wait_event(journal->j_wait_transaction_locked,
337 journal->j_barrier_count == 0);
338 goto repeat;
339 }
340
341 if (!journal->j_running_transaction) {
342 read_unlock(&journal->j_state_lock);
343 if (!new_transaction)
344 goto alloc_transaction;
345 write_lock(&journal->j_state_lock);
346 if (!journal->j_running_transaction &&
347 (handle->h_reserved || !journal->j_barrier_count)) {
348 jbd2_get_transaction(journal, new_transaction);
349 new_transaction = NULL;
350 }
351 write_unlock(&journal->j_state_lock);
352 goto repeat;
353 }
354
355 transaction = journal->j_running_transaction;
356
357 if (!handle->h_reserved) {
358 /* We may have dropped j_state_lock - restart in that case */
359 if (add_transaction_credits(journal, blocks, rsv_blocks))
360 goto repeat;
361 } else {
362 /*
363 * We have handle reserved so we are allowed to join T_LOCKED
364 * transaction and we don't have to check for transaction size
365 * and journal space.
366 */
367 sub_reserved_credits(journal, blocks);
368 handle->h_reserved = 0;
369 }
370
371 /* OK, account for the buffers that this operation expects to
372 * use and add the handle to the running transaction.
373 */
374 update_t_max_wait(transaction, ts);
375 handle->h_transaction = transaction;
376 handle->h_requested_credits = blocks;
377 handle->h_start_jiffies = jiffies;
378 atomic_inc(&transaction->t_updates);
379 atomic_inc(&transaction->t_handle_count);
380 jbd_debug(4, "Handle %p given %d credits (total %d, free %lu)\n",
381 handle, blocks,
382 atomic_read(&transaction->t_outstanding_credits),
383 jbd2_log_space_left(journal));
384 read_unlock(&journal->j_state_lock);
385 current->journal_info = handle;
386
387 rwsem_acquire_read(&journal->j_trans_commit_map, 0, 0, _THIS_IP_);
388 jbd2_journal_free_transaction(new_transaction);
389 /*
390 * Ensure that no allocations done while the transaction is open are
391 * going to recurse back to the fs layer.
392 */
393 handle->saved_alloc_context = memalloc_nofs_save();
394 return 0;
395}
396
397/* Allocate a new handle. This should probably be in a slab... */
398static handle_t *new_handle(int nblocks)
399{
400 handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
401 if (!handle)
402 return NULL;
403 handle->h_buffer_credits = nblocks;
404 handle->h_ref = 1;
405
406 return handle;
407}
408
409handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
410 gfp_t gfp_mask, unsigned int type,
411 unsigned int line_no)
412{
413 handle_t *handle = journal_current_handle();
414 int err;
415
416 if (!journal)
417 return ERR_PTR(-EROFS);
418
419 if (handle) {
420 J_ASSERT(handle->h_transaction->t_journal == journal);
421 handle->h_ref++;
422 return handle;
423 }
424
425 handle = new_handle(nblocks);
426 if (!handle)
427 return ERR_PTR(-ENOMEM);
428 if (rsv_blocks) {
429 handle_t *rsv_handle;
430
431 rsv_handle = new_handle(rsv_blocks);
432 if (!rsv_handle) {
433 jbd2_free_handle(handle);
434 return ERR_PTR(-ENOMEM);
435 }
436 rsv_handle->h_reserved = 1;
437 rsv_handle->h_journal = journal;
438 handle->h_rsv_handle = rsv_handle;
439 }
440
441 err = start_this_handle(journal, handle, gfp_mask);
442 if (err < 0) {
443 if (handle->h_rsv_handle)
444 jbd2_free_handle(handle->h_rsv_handle);
445 jbd2_free_handle(handle);
446 return ERR_PTR(err);
447 }
448 handle->h_type = type;
449 handle->h_line_no = line_no;
450 trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
451 handle->h_transaction->t_tid, type,
452 line_no, nblocks);
453
454 return handle;
455}
456EXPORT_SYMBOL(jbd2__journal_start);
457
458
459/**
460 * handle_t *jbd2_journal_start() - Obtain a new handle.
461 * @journal: Journal to start transaction on.
462 * @nblocks: number of block buffer we might modify
463 *
464 * We make sure that the transaction can guarantee at least nblocks of
465 * modified buffers in the log. We block until the log can guarantee
466 * that much space. Additionally, if rsv_blocks > 0, we also create another
467 * handle with rsv_blocks reserved blocks in the journal. This handle is
468 * is stored in h_rsv_handle. It is not attached to any particular transaction
469 * and thus doesn't block transaction commit. If the caller uses this reserved
470 * handle, it has to set h_rsv_handle to NULL as otherwise jbd2_journal_stop()
471 * on the parent handle will dispose the reserved one. Reserved handle has to
472 * be converted to a normal handle using jbd2_journal_start_reserved() before
473 * it can be used.
474 *
475 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
476 * on failure.
477 */
478handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
479{
480 return jbd2__journal_start(journal, nblocks, 0, GFP_NOFS, 0, 0);
481}
482EXPORT_SYMBOL(jbd2_journal_start);
483
484void jbd2_journal_free_reserved(handle_t *handle)
485{
486 journal_t *journal = handle->h_journal;
487
488 WARN_ON(!handle->h_reserved);
489 sub_reserved_credits(journal, handle->h_buffer_credits);
490 jbd2_free_handle(handle);
491}
492EXPORT_SYMBOL(jbd2_journal_free_reserved);
493
494/**
495 * int jbd2_journal_start_reserved() - start reserved handle
496 * @handle: handle to start
497 * @type: for handle statistics
498 * @line_no: for handle statistics
499 *
500 * Start handle that has been previously reserved with jbd2_journal_reserve().
501 * This attaches @handle to the running transaction (or creates one if there's
502 * not transaction running). Unlike jbd2_journal_start() this function cannot
503 * block on journal commit, checkpointing, or similar stuff. It can block on
504 * memory allocation or frozen journal though.
505 *
506 * Return 0 on success, non-zero on error - handle is freed in that case.
507 */
508int jbd2_journal_start_reserved(handle_t *handle, unsigned int type,
509 unsigned int line_no)
510{
511 journal_t *journal = handle->h_journal;
512 int ret = -EIO;
513
514 if (WARN_ON(!handle->h_reserved)) {
515 /* Someone passed in normal handle? Just stop it. */
516 jbd2_journal_stop(handle);
517 return ret;
518 }
519 /*
520 * Usefulness of mixing of reserved and unreserved handles is
521 * questionable. So far nobody seems to need it so just error out.
522 */
523 if (WARN_ON(current->journal_info)) {
524 jbd2_journal_free_reserved(handle);
525 return ret;
526 }
527
528 handle->h_journal = NULL;
529 /*
530 * GFP_NOFS is here because callers are likely from writeback or
531 * similarly constrained call sites
532 */
533 ret = start_this_handle(journal, handle, GFP_NOFS);
534 if (ret < 0) {
535 handle->h_journal = journal;
536 jbd2_journal_free_reserved(handle);
537 return ret;
538 }
539 handle->h_type = type;
540 handle->h_line_no = line_no;
541 return 0;
542}
543EXPORT_SYMBOL(jbd2_journal_start_reserved);
544
545/**
546 * int jbd2_journal_extend() - extend buffer credits.
547 * @handle: handle to 'extend'
548 * @nblocks: nr blocks to try to extend by.
549 *
550 * Some transactions, such as large extends and truncates, can be done
551 * atomically all at once or in several stages. The operation requests
552 * a credit for a number of buffer modifications in advance, but can
553 * extend its credit if it needs more.
554 *
555 * jbd2_journal_extend tries to give the running handle more buffer credits.
556 * It does not guarantee that allocation - this is a best-effort only.
557 * The calling process MUST be able to deal cleanly with a failure to
558 * extend here.
559 *
560 * Return 0 on success, non-zero on failure.
561 *
562 * return code < 0 implies an error
563 * return code > 0 implies normal transaction-full status.
564 */
565int jbd2_journal_extend(handle_t *handle, int nblocks)
566{
567 transaction_t *transaction = handle->h_transaction;
568 journal_t *journal;
569 int result;
570 int wanted;
571
572 if (is_handle_aborted(handle))
573 return -EROFS;
574 journal = transaction->t_journal;
575
576 result = 1;
577
578 read_lock(&journal->j_state_lock);
579
580 /* Don't extend a locked-down transaction! */
581 if (transaction->t_state != T_RUNNING) {
582 jbd_debug(3, "denied handle %p %d blocks: "
583 "transaction not running\n", handle, nblocks);
584 goto error_out;
585 }
586
587 spin_lock(&transaction->t_handle_lock);
588 wanted = atomic_add_return(nblocks,
589 &transaction->t_outstanding_credits);
590
591 if (wanted > journal->j_max_transaction_buffers) {
592 jbd_debug(3, "denied handle %p %d blocks: "
593 "transaction too large\n", handle, nblocks);
594 atomic_sub(nblocks, &transaction->t_outstanding_credits);
595 goto unlock;
596 }
597
598 if (wanted + (wanted >> JBD2_CONTROL_BLOCKS_SHIFT) >
599 jbd2_log_space_left(journal)) {
600 jbd_debug(3, "denied handle %p %d blocks: "
601 "insufficient log space\n", handle, nblocks);
602 atomic_sub(nblocks, &transaction->t_outstanding_credits);
603 goto unlock;
604 }
605
606 trace_jbd2_handle_extend(journal->j_fs_dev->bd_dev,
607 transaction->t_tid,
608 handle->h_type, handle->h_line_no,
609 handle->h_buffer_credits,
610 nblocks);
611
612 handle->h_buffer_credits += nblocks;
613 handle->h_requested_credits += nblocks;
614 result = 0;
615
616 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
617unlock:
618 spin_unlock(&transaction->t_handle_lock);
619error_out:
620 read_unlock(&journal->j_state_lock);
621 return result;
622}
623
624
625/**
626 * int jbd2_journal_restart() - restart a handle .
627 * @handle: handle to restart
628 * @nblocks: nr credits requested
629 * @gfp_mask: memory allocation flags (for start_this_handle)
630 *
631 * Restart a handle for a multi-transaction filesystem
632 * operation.
633 *
634 * If the jbd2_journal_extend() call above fails to grant new buffer credits
635 * to a running handle, a call to jbd2_journal_restart will commit the
636 * handle's transaction so far and reattach the handle to a new
637 * transaction capable of guaranteeing the requested number of
638 * credits. We preserve reserved handle if there's any attached to the
639 * passed in handle.
640 */
641int jbd2__journal_restart(handle_t *handle, int nblocks, gfp_t gfp_mask)
642{
643 transaction_t *transaction = handle->h_transaction;
644 journal_t *journal;
645 tid_t tid;
646 int need_to_start, ret;
647
648 /* If we've had an abort of any type, don't even think about
649 * actually doing the restart! */
650 if (is_handle_aborted(handle))
651 return 0;
652 journal = transaction->t_journal;
653
654 /*
655 * First unlink the handle from its current transaction, and start the
656 * commit on that.
657 */
658 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
659 J_ASSERT(journal_current_handle() == handle);
660
661 read_lock(&journal->j_state_lock);
662 spin_lock(&transaction->t_handle_lock);
663 atomic_sub(handle->h_buffer_credits,
664 &transaction->t_outstanding_credits);
665 if (handle->h_rsv_handle) {
666 sub_reserved_credits(journal,
667 handle->h_rsv_handle->h_buffer_credits);
668 }
669 if (atomic_dec_and_test(&transaction->t_updates))
670 wake_up(&journal->j_wait_updates);
671 tid = transaction->t_tid;
672 spin_unlock(&transaction->t_handle_lock);
673 handle->h_transaction = NULL;
674 current->journal_info = NULL;
675
676 jbd_debug(2, "restarting handle %p\n", handle);
677 need_to_start = !tid_geq(journal->j_commit_request, tid);
678 read_unlock(&journal->j_state_lock);
679 if (need_to_start)
680 jbd2_log_start_commit(journal, tid);
681
682 rwsem_release(&journal->j_trans_commit_map, 1, _THIS_IP_);
683 handle->h_buffer_credits = nblocks;
684 /*
685 * Restore the original nofs context because the journal restart
686 * is basically the same thing as journal stop and start.
687 * start_this_handle will start a new nofs context.
688 */
689 memalloc_nofs_restore(handle->saved_alloc_context);
690 ret = start_this_handle(journal, handle, gfp_mask);
691 return ret;
692}
693EXPORT_SYMBOL(jbd2__journal_restart);
694
695
696int jbd2_journal_restart(handle_t *handle, int nblocks)
697{
698 return jbd2__journal_restart(handle, nblocks, GFP_NOFS);
699}
700EXPORT_SYMBOL(jbd2_journal_restart);
701
702/**
703 * void jbd2_journal_lock_updates () - establish a transaction barrier.
704 * @journal: Journal to establish a barrier on.
705 *
706 * This locks out any further updates from being started, and blocks
707 * until all existing updates have completed, returning only once the
708 * journal is in a quiescent state with no updates running.
709 *
710 * The journal lock should not be held on entry.
711 */
712void jbd2_journal_lock_updates(journal_t *journal)
713{
714 DEFINE_WAIT(wait);
715
716 jbd2_might_wait_for_commit(journal);
717
718 write_lock(&journal->j_state_lock);
719 ++journal->j_barrier_count;
720
721 /* Wait until there are no reserved handles */
722 if (atomic_read(&journal->j_reserved_credits)) {
723 write_unlock(&journal->j_state_lock);
724 wait_event(journal->j_wait_reserved,
725 atomic_read(&journal->j_reserved_credits) == 0);
726 write_lock(&journal->j_state_lock);
727 }
728
729 /* Wait until there are no running updates */
730 while (1) {
731 transaction_t *transaction = journal->j_running_transaction;
732
733 if (!transaction)
734 break;
735
736 spin_lock(&transaction->t_handle_lock);
737 prepare_to_wait(&journal->j_wait_updates, &wait,
738 TASK_UNINTERRUPTIBLE);
739 if (!atomic_read(&transaction->t_updates)) {
740 spin_unlock(&transaction->t_handle_lock);
741 finish_wait(&journal->j_wait_updates, &wait);
742 break;
743 }
744 spin_unlock(&transaction->t_handle_lock);
745 write_unlock(&journal->j_state_lock);
746 schedule();
747 finish_wait(&journal->j_wait_updates, &wait);
748 write_lock(&journal->j_state_lock);
749 }
750 write_unlock(&journal->j_state_lock);
751
752 /*
753 * We have now established a barrier against other normal updates, but
754 * we also need to barrier against other jbd2_journal_lock_updates() calls
755 * to make sure that we serialise special journal-locked operations
756 * too.
757 */
758 mutex_lock(&journal->j_barrier);
759}
760
761/**
762 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
763 * @journal: Journal to release the barrier on.
764 *
765 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
766 *
767 * Should be called without the journal lock held.
768 */
769void jbd2_journal_unlock_updates (journal_t *journal)
770{
771 J_ASSERT(journal->j_barrier_count != 0);
772
773 mutex_unlock(&journal->j_barrier);
774 write_lock(&journal->j_state_lock);
775 --journal->j_barrier_count;
776 write_unlock(&journal->j_state_lock);
777 wake_up(&journal->j_wait_transaction_locked);
778}
779
780static void warn_dirty_buffer(struct buffer_head *bh)
781{
782 printk(KERN_WARNING
783 "JBD2: Spotted dirty metadata buffer (dev = %pg, blocknr = %llu). "
784 "There's a risk of filesystem corruption in case of system "
785 "crash.\n",
786 bh->b_bdev, (unsigned long long)bh->b_blocknr);
787}
788
789/* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */
790static void jbd2_freeze_jh_data(struct journal_head *jh)
791{
792 struct page *page;
793 int offset;
794 char *source;
795 struct buffer_head *bh = jh2bh(jh);
796
797 J_EXPECT_JH(jh, buffer_uptodate(bh), "Possible IO failure.\n");
798 page = bh->b_page;
799 offset = offset_in_page(bh->b_data);
800 source = kmap_atomic(page);
801 /* Fire data frozen trigger just before we copy the data */
802 jbd2_buffer_frozen_trigger(jh, source + offset, jh->b_triggers);
803 memcpy(jh->b_frozen_data, source + offset, bh->b_size);
804 kunmap_atomic(source);
805
806 /*
807 * Now that the frozen data is saved off, we need to store any matching
808 * triggers.
809 */
810 jh->b_frozen_triggers = jh->b_triggers;
811}
812
813/*
814 * If the buffer is already part of the current transaction, then there
815 * is nothing we need to do. If it is already part of a prior
816 * transaction which we are still committing to disk, then we need to
817 * make sure that we do not overwrite the old copy: we do copy-out to
818 * preserve the copy going to disk. We also account the buffer against
819 * the handle's metadata buffer credits (unless the buffer is already
820 * part of the transaction, that is).
821 *
822 */
823static int
824do_get_write_access(handle_t *handle, struct journal_head *jh,
825 int force_copy)
826{
827 struct buffer_head *bh;
828 transaction_t *transaction = handle->h_transaction;
829 journal_t *journal;
830 int error;
831 char *frozen_buffer = NULL;
832 unsigned long start_lock, time_lock;
833
834 if (is_handle_aborted(handle))
835 return -EROFS;
836 journal = transaction->t_journal;
837
838 jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
839
840 JBUFFER_TRACE(jh, "entry");
841repeat:
842 bh = jh2bh(jh);
843
844 /* @@@ Need to check for errors here at some point. */
845
846 start_lock = jiffies;
847 lock_buffer(bh);
848 jbd_lock_bh_state(bh);
849
850 /* If it takes too long to lock the buffer, trace it */
851 time_lock = jbd2_time_diff(start_lock, jiffies);
852 if (time_lock > HZ/10)
853 trace_jbd2_lock_buffer_stall(bh->b_bdev->bd_dev,
854 jiffies_to_msecs(time_lock));
855
856 /* We now hold the buffer lock so it is safe to query the buffer
857 * state. Is the buffer dirty?
858 *
859 * If so, there are two possibilities. The buffer may be
860 * non-journaled, and undergoing a quite legitimate writeback.
861 * Otherwise, it is journaled, and we don't expect dirty buffers
862 * in that state (the buffers should be marked JBD_Dirty
863 * instead.) So either the IO is being done under our own
864 * control and this is a bug, or it's a third party IO such as
865 * dump(8) (which may leave the buffer scheduled for read ---
866 * ie. locked but not dirty) or tune2fs (which may actually have
867 * the buffer dirtied, ugh.) */
868
869 if (buffer_dirty(bh)) {
870 /*
871 * First question: is this buffer already part of the current
872 * transaction or the existing committing transaction?
873 */
874 if (jh->b_transaction) {
875 J_ASSERT_JH(jh,
876 jh->b_transaction == transaction ||
877 jh->b_transaction ==
878 journal->j_committing_transaction);
879 if (jh->b_next_transaction)
880 J_ASSERT_JH(jh, jh->b_next_transaction ==
881 transaction);
882 warn_dirty_buffer(bh);
883 }
884 /*
885 * In any case we need to clean the dirty flag and we must
886 * do it under the buffer lock to be sure we don't race
887 * with running write-out.
888 */
889 JBUFFER_TRACE(jh, "Journalling dirty buffer");
890 clear_buffer_dirty(bh);
891 set_buffer_jbddirty(bh);
892 }
893
894 unlock_buffer(bh);
895
896 error = -EROFS;
897 if (is_handle_aborted(handle)) {
898 jbd_unlock_bh_state(bh);
899 goto out;
900 }
901 error = 0;
902
903 /*
904 * The buffer is already part of this transaction if b_transaction or
905 * b_next_transaction points to it
906 */
907 if (jh->b_transaction == transaction ||
908 jh->b_next_transaction == transaction)
909 goto done;
910
911 /*
912 * this is the first time this transaction is touching this buffer,
913 * reset the modified flag
914 */
915 jh->b_modified = 0;
916
917 /*
918 * If the buffer is not journaled right now, we need to make sure it
919 * doesn't get written to disk before the caller actually commits the
920 * new data
921 */
922 if (!jh->b_transaction) {
923 JBUFFER_TRACE(jh, "no transaction");
924 J_ASSERT_JH(jh, !jh->b_next_transaction);
925 JBUFFER_TRACE(jh, "file as BJ_Reserved");
926 /*
927 * Make sure all stores to jh (b_modified, b_frozen_data) are
928 * visible before attaching it to the running transaction.
929 * Paired with barrier in jbd2_write_access_granted()
930 */
931 smp_wmb();
932 spin_lock(&journal->j_list_lock);
933 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
934 spin_unlock(&journal->j_list_lock);
935 goto done;
936 }
937 /*
938 * If there is already a copy-out version of this buffer, then we don't
939 * need to make another one
940 */
941 if (jh->b_frozen_data) {
942 JBUFFER_TRACE(jh, "has frozen data");
943 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
944 goto attach_next;
945 }
946
947 JBUFFER_TRACE(jh, "owned by older transaction");
948 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
949 J_ASSERT_JH(jh, jh->b_transaction == journal->j_committing_transaction);
950
951 /*
952 * There is one case we have to be very careful about. If the
953 * committing transaction is currently writing this buffer out to disk
954 * and has NOT made a copy-out, then we cannot modify the buffer
955 * contents at all right now. The essence of copy-out is that it is
956 * the extra copy, not the primary copy, which gets journaled. If the
957 * primary copy is already going to disk then we cannot do copy-out
958 * here.
959 */
960 if (buffer_shadow(bh)) {
961 JBUFFER_TRACE(jh, "on shadow: sleep");
962 jbd_unlock_bh_state(bh);
963 wait_on_bit_io(&bh->b_state, BH_Shadow, TASK_UNINTERRUPTIBLE);
964 goto repeat;
965 }
966
967 /*
968 * Only do the copy if the currently-owning transaction still needs it.
969 * If buffer isn't on BJ_Metadata list, the committing transaction is
970 * past that stage (here we use the fact that BH_Shadow is set under
971 * bh_state lock together with refiling to BJ_Shadow list and at this
972 * point we know the buffer doesn't have BH_Shadow set).
973 *
974 * Subtle point, though: if this is a get_undo_access, then we will be
975 * relying on the frozen_data to contain the new value of the
976 * committed_data record after the transaction, so we HAVE to force the
977 * frozen_data copy in that case.
978 */
979 if (jh->b_jlist == BJ_Metadata || force_copy) {
980 JBUFFER_TRACE(jh, "generate frozen data");
981 if (!frozen_buffer) {
982 JBUFFER_TRACE(jh, "allocate memory for buffer");
983 jbd_unlock_bh_state(bh);
984 frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
985 GFP_NOFS | __GFP_NOFAIL);
986 goto repeat;
987 }
988 jh->b_frozen_data = frozen_buffer;
989 frozen_buffer = NULL;
990 jbd2_freeze_jh_data(jh);
991 }
992attach_next:
993 /*
994 * Make sure all stores to jh (b_modified, b_frozen_data) are visible
995 * before attaching it to the running transaction. Paired with barrier
996 * in jbd2_write_access_granted()
997 */
998 smp_wmb();
999 jh->b_next_transaction = transaction;
1000
1001done:
1002 jbd_unlock_bh_state(bh);
1003
1004 /*
1005 * If we are about to journal a buffer, then any revoke pending on it is
1006 * no longer valid
1007 */
1008 jbd2_journal_cancel_revoke(handle, jh);
1009
1010out:
1011 if (unlikely(frozen_buffer)) /* It's usually NULL */
1012 jbd2_free(frozen_buffer, bh->b_size);
1013
1014 JBUFFER_TRACE(jh, "exit");
1015 return error;
1016}
1017
1018/* Fast check whether buffer is already attached to the required transaction */
1019static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh,
1020 bool undo)
1021{
1022 struct journal_head *jh;
1023 bool ret = false;
1024
1025 /* Dirty buffers require special handling... */
1026 if (buffer_dirty(bh))
1027 return false;
1028
1029 /*
1030 * RCU protects us from dereferencing freed pages. So the checks we do
1031 * are guaranteed not to oops. However the jh slab object can get freed
1032 * & reallocated while we work with it. So we have to be careful. When
1033 * we see jh attached to the running transaction, we know it must stay
1034 * so until the transaction is committed. Thus jh won't be freed and
1035 * will be attached to the same bh while we run. However it can
1036 * happen jh gets freed, reallocated, and attached to the transaction
1037 * just after we get pointer to it from bh. So we have to be careful
1038 * and recheck jh still belongs to our bh before we return success.
1039 */
1040 rcu_read_lock();
1041 if (!buffer_jbd(bh))
1042 goto out;
1043 /* This should be bh2jh() but that doesn't work with inline functions */
1044 jh = READ_ONCE(bh->b_private);
1045 if (!jh)
1046 goto out;
1047 /* For undo access buffer must have data copied */
1048 if (undo && !jh->b_committed_data)
1049 goto out;
1050 if (jh->b_transaction != handle->h_transaction &&
1051 jh->b_next_transaction != handle->h_transaction)
1052 goto out;
1053 /*
1054 * There are two reasons for the barrier here:
1055 * 1) Make sure to fetch b_bh after we did previous checks so that we
1056 * detect when jh went through free, realloc, attach to transaction
1057 * while we were checking. Paired with implicit barrier in that path.
1058 * 2) So that access to bh done after jbd2_write_access_granted()
1059 * doesn't get reordered and see inconsistent state of concurrent
1060 * do_get_write_access().
1061 */
1062 smp_mb();
1063 if (unlikely(jh->b_bh != bh))
1064 goto out;
1065 ret = true;
1066out:
1067 rcu_read_unlock();
1068 return ret;
1069}
1070
1071/**
1072 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
1073 * @handle: transaction to add buffer modifications to
1074 * @bh: bh to be used for metadata writes
1075 *
1076 * Returns: error code or 0 on success.
1077 *
1078 * In full data journalling mode the buffer may be of type BJ_AsyncData,
1079 * because we're ``write()ing`` a buffer which is also part of a shared mapping.
1080 */
1081
1082int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
1083{
1084 struct journal_head *jh;
1085 int rc;
1086
1087 if (jbd2_write_access_granted(handle, bh, false))
1088 return 0;
1089
1090 jh = jbd2_journal_add_journal_head(bh);
1091 /* We do not want to get caught playing with fields which the
1092 * log thread also manipulates. Make sure that the buffer
1093 * completes any outstanding IO before proceeding. */
1094 rc = do_get_write_access(handle, jh, 0);
1095 jbd2_journal_put_journal_head(jh);
1096 return rc;
1097}
1098
1099
1100/*
1101 * When the user wants to journal a newly created buffer_head
1102 * (ie. getblk() returned a new buffer and we are going to populate it
1103 * manually rather than reading off disk), then we need to keep the
1104 * buffer_head locked until it has been completely filled with new
1105 * data. In this case, we should be able to make the assertion that
1106 * the bh is not already part of an existing transaction.
1107 *
1108 * The buffer should already be locked by the caller by this point.
1109 * There is no lock ranking violation: it was a newly created,
1110 * unlocked buffer beforehand. */
1111
1112/**
1113 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
1114 * @handle: transaction to new buffer to
1115 * @bh: new buffer.
1116 *
1117 * Call this if you create a new bh.
1118 */
1119int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
1120{
1121 transaction_t *transaction = handle->h_transaction;
1122 journal_t *journal;
1123 struct journal_head *jh = jbd2_journal_add_journal_head(bh);
1124 int err;
1125
1126 jbd_debug(5, "journal_head %p\n", jh);
1127 err = -EROFS;
1128 if (is_handle_aborted(handle))
1129 goto out;
1130 journal = transaction->t_journal;
1131 err = 0;
1132
1133 JBUFFER_TRACE(jh, "entry");
1134 /*
1135 * The buffer may already belong to this transaction due to pre-zeroing
1136 * in the filesystem's new_block code. It may also be on the previous,
1137 * committing transaction's lists, but it HAS to be in Forget state in
1138 * that case: the transaction must have deleted the buffer for it to be
1139 * reused here.
1140 */
1141 jbd_lock_bh_state(bh);
1142 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
1143 jh->b_transaction == NULL ||
1144 (jh->b_transaction == journal->j_committing_transaction &&
1145 jh->b_jlist == BJ_Forget)));
1146
1147 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1148 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
1149
1150 if (jh->b_transaction == NULL) {
1151 /*
1152 * Previous jbd2_journal_forget() could have left the buffer
1153 * with jbddirty bit set because it was being committed. When
1154 * the commit finished, we've filed the buffer for
1155 * checkpointing and marked it dirty. Now we are reallocating
1156 * the buffer so the transaction freeing it must have
1157 * committed and so it's safe to clear the dirty bit.
1158 */
1159 clear_buffer_dirty(jh2bh(jh));
1160 /* first access by this transaction */
1161 jh->b_modified = 0;
1162
1163 JBUFFER_TRACE(jh, "file as BJ_Reserved");
1164 spin_lock(&journal->j_list_lock);
1165 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
1166 spin_unlock(&journal->j_list_lock);
1167 } else if (jh->b_transaction == journal->j_committing_transaction) {
1168 /* first access by this transaction */
1169 jh->b_modified = 0;
1170
1171 JBUFFER_TRACE(jh, "set next transaction");
1172 spin_lock(&journal->j_list_lock);
1173 jh->b_next_transaction = transaction;
1174 spin_unlock(&journal->j_list_lock);
1175 }
1176 jbd_unlock_bh_state(bh);
1177
1178 /*
1179 * akpm: I added this. ext3_alloc_branch can pick up new indirect
1180 * blocks which contain freed but then revoked metadata. We need
1181 * to cancel the revoke in case we end up freeing it yet again
1182 * and the reallocating as data - this would cause a second revoke,
1183 * which hits an assertion error.
1184 */
1185 JBUFFER_TRACE(jh, "cancelling revoke");
1186 jbd2_journal_cancel_revoke(handle, jh);
1187out:
1188 jbd2_journal_put_journal_head(jh);
1189 return err;
1190}
1191
1192/**
1193 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with
1194 * non-rewindable consequences
1195 * @handle: transaction
1196 * @bh: buffer to undo
1197 *
1198 * Sometimes there is a need to distinguish between metadata which has
1199 * been committed to disk and that which has not. The ext3fs code uses
1200 * this for freeing and allocating space, we have to make sure that we
1201 * do not reuse freed space until the deallocation has been committed,
1202 * since if we overwrote that space we would make the delete
1203 * un-rewindable in case of a crash.
1204 *
1205 * To deal with that, jbd2_journal_get_undo_access requests write access to a
1206 * buffer for parts of non-rewindable operations such as delete
1207 * operations on the bitmaps. The journaling code must keep a copy of
1208 * the buffer's contents prior to the undo_access call until such time
1209 * as we know that the buffer has definitely been committed to disk.
1210 *
1211 * We never need to know which transaction the committed data is part
1212 * of, buffers touched here are guaranteed to be dirtied later and so
1213 * will be committed to a new transaction in due course, at which point
1214 * we can discard the old committed data pointer.
1215 *
1216 * Returns error number or 0 on success.
1217 */
1218int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
1219{
1220 int err;
1221 struct journal_head *jh;
1222 char *committed_data = NULL;
1223
1224 JBUFFER_TRACE(jh, "entry");
1225 if (jbd2_write_access_granted(handle, bh, true))
1226 return 0;
1227
1228 jh = jbd2_journal_add_journal_head(bh);
1229 /*
1230 * Do this first --- it can drop the journal lock, so we want to
1231 * make sure that obtaining the committed_data is done
1232 * atomically wrt. completion of any outstanding commits.
1233 */
1234 err = do_get_write_access(handle, jh, 1);
1235 if (err)
1236 goto out;
1237
1238repeat:
1239 if (!jh->b_committed_data)
1240 committed_data = jbd2_alloc(jh2bh(jh)->b_size,
1241 GFP_NOFS|__GFP_NOFAIL);
1242
1243 jbd_lock_bh_state(bh);
1244 if (!jh->b_committed_data) {
1245 /* Copy out the current buffer contents into the
1246 * preserved, committed copy. */
1247 JBUFFER_TRACE(jh, "generate b_committed data");
1248 if (!committed_data) {
1249 jbd_unlock_bh_state(bh);
1250 goto repeat;
1251 }
1252
1253 jh->b_committed_data = committed_data;
1254 committed_data = NULL;
1255 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
1256 }
1257 jbd_unlock_bh_state(bh);
1258out:
1259 jbd2_journal_put_journal_head(jh);
1260 if (unlikely(committed_data))
1261 jbd2_free(committed_data, bh->b_size);
1262 return err;
1263}
1264
1265/**
1266 * void jbd2_journal_set_triggers() - Add triggers for commit writeout
1267 * @bh: buffer to trigger on
1268 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1269 *
1270 * Set any triggers on this journal_head. This is always safe, because
1271 * triggers for a committing buffer will be saved off, and triggers for
1272 * a running transaction will match the buffer in that transaction.
1273 *
1274 * Call with NULL to clear the triggers.
1275 */
1276void jbd2_journal_set_triggers(struct buffer_head *bh,
1277 struct jbd2_buffer_trigger_type *type)
1278{
1279 struct journal_head *jh = jbd2_journal_grab_journal_head(bh);
1280
1281 if (WARN_ON(!jh))
1282 return;
1283 jh->b_triggers = type;
1284 jbd2_journal_put_journal_head(jh);
1285}
1286
1287void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
1288 struct jbd2_buffer_trigger_type *triggers)
1289{
1290 struct buffer_head *bh = jh2bh(jh);
1291
1292 if (!triggers || !triggers->t_frozen)
1293 return;
1294
1295 triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
1296}
1297
1298void jbd2_buffer_abort_trigger(struct journal_head *jh,
1299 struct jbd2_buffer_trigger_type *triggers)
1300{
1301 if (!triggers || !triggers->t_abort)
1302 return;
1303
1304 triggers->t_abort(triggers, jh2bh(jh));
1305}
1306
1307/**
1308 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata
1309 * @handle: transaction to add buffer to.
1310 * @bh: buffer to mark
1311 *
1312 * mark dirty metadata which needs to be journaled as part of the current
1313 * transaction.
1314 *
1315 * The buffer must have previously had jbd2_journal_get_write_access()
1316 * called so that it has a valid journal_head attached to the buffer
1317 * head.
1318 *
1319 * The buffer is placed on the transaction's metadata list and is marked
1320 * as belonging to the transaction.
1321 *
1322 * Returns error number or 0 on success.
1323 *
1324 * Special care needs to be taken if the buffer already belongs to the
1325 * current committing transaction (in which case we should have frozen
1326 * data present for that commit). In that case, we don't relink the
1327 * buffer: that only gets done when the old transaction finally
1328 * completes its commit.
1329 */
1330int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1331{
1332 transaction_t *transaction = handle->h_transaction;
1333 journal_t *journal;
1334 struct journal_head *jh;
1335 int ret = 0;
1336
1337 if (is_handle_aborted(handle))
1338 return -EROFS;
1339 if (!buffer_jbd(bh)) {
1340 ret = -EUCLEAN;
1341 goto out;
1342 }
1343 /*
1344 * We don't grab jh reference here since the buffer must be part
1345 * of the running transaction.
1346 */
1347 jh = bh2jh(bh);
1348 /*
1349 * This and the following assertions are unreliable since we may see jh
1350 * in inconsistent state unless we grab bh_state lock. But this is
1351 * crucial to catch bugs so let's do a reliable check until the
1352 * lockless handling is fully proven.
1353 */
1354 if (jh->b_transaction != transaction &&
1355 jh->b_next_transaction != transaction) {
1356 jbd_lock_bh_state(bh);
1357 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1358 jh->b_next_transaction == transaction);
1359 jbd_unlock_bh_state(bh);
1360 }
1361 if (jh->b_modified == 1) {
1362 /* If it's in our transaction it must be in BJ_Metadata list. */
1363 if (jh->b_transaction == transaction &&
1364 jh->b_jlist != BJ_Metadata) {
1365 jbd_lock_bh_state(bh);
1366 J_ASSERT_JH(jh, jh->b_transaction != transaction ||
1367 jh->b_jlist == BJ_Metadata);
1368 jbd_unlock_bh_state(bh);
1369 }
1370 goto out;
1371 }
1372
1373 journal = transaction->t_journal;
1374 jbd_debug(5, "journal_head %p\n", jh);
1375 JBUFFER_TRACE(jh, "entry");
1376
1377 jbd_lock_bh_state(bh);
1378
1379 if (jh->b_modified == 0) {
1380 /*
1381 * This buffer's got modified and becoming part
1382 * of the transaction. This needs to be done
1383 * once a transaction -bzzz
1384 */
1385 jh->b_modified = 1;
1386 if (handle->h_buffer_credits <= 0) {
1387 ret = -ENOSPC;
1388 goto out_unlock_bh;
1389 }
1390 handle->h_buffer_credits--;
1391 }
1392
1393 /*
1394 * fastpath, to avoid expensive locking. If this buffer is already
1395 * on the running transaction's metadata list there is nothing to do.
1396 * Nobody can take it off again because there is a handle open.
1397 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1398 * result in this test being false, so we go in and take the locks.
1399 */
1400 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1401 JBUFFER_TRACE(jh, "fastpath");
1402 if (unlikely(jh->b_transaction !=
1403 journal->j_running_transaction)) {
1404 printk(KERN_ERR "JBD2: %s: "
1405 "jh->b_transaction (%llu, %p, %u) != "
1406 "journal->j_running_transaction (%p, %u)\n",
1407 journal->j_devname,
1408 (unsigned long long) bh->b_blocknr,
1409 jh->b_transaction,
1410 jh->b_transaction ? jh->b_transaction->t_tid : 0,
1411 journal->j_running_transaction,
1412 journal->j_running_transaction ?
1413 journal->j_running_transaction->t_tid : 0);
1414 ret = -EINVAL;
1415 }
1416 goto out_unlock_bh;
1417 }
1418
1419 set_buffer_jbddirty(bh);
1420
1421 /*
1422 * Metadata already on the current transaction list doesn't
1423 * need to be filed. Metadata on another transaction's list must
1424 * be committing, and will be refiled once the commit completes:
1425 * leave it alone for now.
1426 */
1427 if (jh->b_transaction != transaction) {
1428 JBUFFER_TRACE(jh, "already on other transaction");
1429 if (unlikely(((jh->b_transaction !=
1430 journal->j_committing_transaction)) ||
1431 (jh->b_next_transaction != transaction))) {
1432 printk(KERN_ERR "jbd2_journal_dirty_metadata: %s: "
1433 "bad jh for block %llu: "
1434 "transaction (%p, %u), "
1435 "jh->b_transaction (%p, %u), "
1436 "jh->b_next_transaction (%p, %u), jlist %u\n",
1437 journal->j_devname,
1438 (unsigned long long) bh->b_blocknr,
1439 transaction, transaction->t_tid,
1440 jh->b_transaction,
1441 jh->b_transaction ?
1442 jh->b_transaction->t_tid : 0,
1443 jh->b_next_transaction,
1444 jh->b_next_transaction ?
1445 jh->b_next_transaction->t_tid : 0,
1446 jh->b_jlist);
1447 WARN_ON(1);
1448 ret = -EINVAL;
1449 }
1450 /* And this case is illegal: we can't reuse another
1451 * transaction's data buffer, ever. */
1452 goto out_unlock_bh;
1453 }
1454
1455 /* That test should have eliminated the following case: */
1456 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1457
1458 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1459 spin_lock(&journal->j_list_lock);
1460 __jbd2_journal_file_buffer(jh, transaction, BJ_Metadata);
1461 spin_unlock(&journal->j_list_lock);
1462out_unlock_bh:
1463 jbd_unlock_bh_state(bh);
1464out:
1465 JBUFFER_TRACE(jh, "exit");
1466 return ret;
1467}
1468
1469/**
1470 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1471 * @handle: transaction handle
1472 * @bh: bh to 'forget'
1473 *
1474 * We can only do the bforget if there are no commits pending against the
1475 * buffer. If the buffer is dirty in the current running transaction we
1476 * can safely unlink it.
1477 *
1478 * bh may not be a journalled buffer at all - it may be a non-JBD
1479 * buffer which came off the hashtable. Check for this.
1480 *
1481 * Decrements bh->b_count by one.
1482 *
1483 * Allow this call even if the handle has aborted --- it may be part of
1484 * the caller's cleanup after an abort.
1485 */
1486int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1487{
1488 transaction_t *transaction = handle->h_transaction;
1489 journal_t *journal;
1490 struct journal_head *jh;
1491 int drop_reserve = 0;
1492 int err = 0;
1493 int was_modified = 0;
1494
1495 if (is_handle_aborted(handle))
1496 return -EROFS;
1497 journal = transaction->t_journal;
1498
1499 BUFFER_TRACE(bh, "entry");
1500
1501 jbd_lock_bh_state(bh);
1502
1503 if (!buffer_jbd(bh))
1504 goto not_jbd;
1505 jh = bh2jh(bh);
1506
1507 /* Critical error: attempting to delete a bitmap buffer, maybe?
1508 * Don't do any jbd operations, and return an error. */
1509 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1510 "inconsistent data on disk")) {
1511 err = -EIO;
1512 goto not_jbd;
1513 }
1514
1515 /* keep track of whether or not this transaction modified us */
1516 was_modified = jh->b_modified;
1517
1518 /*
1519 * The buffer's going from the transaction, we must drop
1520 * all references -bzzz
1521 */
1522 jh->b_modified = 0;
1523
1524 if (jh->b_transaction == transaction) {
1525 J_ASSERT_JH(jh, !jh->b_frozen_data);
1526
1527 /* If we are forgetting a buffer which is already part
1528 * of this transaction, then we can just drop it from
1529 * the transaction immediately. */
1530 clear_buffer_dirty(bh);
1531 clear_buffer_jbddirty(bh);
1532
1533 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1534
1535 /*
1536 * we only want to drop a reference if this transaction
1537 * modified the buffer
1538 */
1539 if (was_modified)
1540 drop_reserve = 1;
1541
1542 /*
1543 * We are no longer going to journal this buffer.
1544 * However, the commit of this transaction is still
1545 * important to the buffer: the delete that we are now
1546 * processing might obsolete an old log entry, so by
1547 * committing, we can satisfy the buffer's checkpoint.
1548 *
1549 * So, if we have a checkpoint on the buffer, we should
1550 * now refile the buffer on our BJ_Forget list so that
1551 * we know to remove the checkpoint after we commit.
1552 */
1553
1554 spin_lock(&journal->j_list_lock);
1555 if (jh->b_cp_transaction) {
1556 __jbd2_journal_temp_unlink_buffer(jh);
1557 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1558 } else {
1559 __jbd2_journal_unfile_buffer(jh);
1560 if (!buffer_jbd(bh)) {
1561 spin_unlock(&journal->j_list_lock);
1562 jbd_unlock_bh_state(bh);
1563 __bforget(bh);
1564 goto drop;
1565 }
1566 }
1567 spin_unlock(&journal->j_list_lock);
1568 } else if (jh->b_transaction) {
1569 J_ASSERT_JH(jh, (jh->b_transaction ==
1570 journal->j_committing_transaction));
1571 /* However, if the buffer is still owned by a prior
1572 * (committing) transaction, we can't drop it yet... */
1573 JBUFFER_TRACE(jh, "belongs to older transaction");
1574 /* ... but we CAN drop it from the new transaction if we
1575 * have also modified it since the original commit. */
1576
1577 if (jh->b_next_transaction) {
1578 J_ASSERT(jh->b_next_transaction == transaction);
1579 spin_lock(&journal->j_list_lock);
1580 jh->b_next_transaction = NULL;
1581 spin_unlock(&journal->j_list_lock);
1582
1583 /*
1584 * only drop a reference if this transaction modified
1585 * the buffer
1586 */
1587 if (was_modified)
1588 drop_reserve = 1;
1589 }
1590 }
1591
1592not_jbd:
1593 jbd_unlock_bh_state(bh);
1594 __brelse(bh);
1595drop:
1596 if (drop_reserve) {
1597 /* no need to reserve log space for this block -bzzz */
1598 handle->h_buffer_credits++;
1599 }
1600 return err;
1601}
1602
1603/**
1604 * int jbd2_journal_stop() - complete a transaction
1605 * @handle: transaction to complete.
1606 *
1607 * All done for a particular handle.
1608 *
1609 * There is not much action needed here. We just return any remaining
1610 * buffer credits to the transaction and remove the handle. The only
1611 * complication is that we need to start a commit operation if the
1612 * filesystem is marked for synchronous update.
1613 *
1614 * jbd2_journal_stop itself will not usually return an error, but it may
1615 * do so in unusual circumstances. In particular, expect it to
1616 * return -EIO if a jbd2_journal_abort has been executed since the
1617 * transaction began.
1618 */
1619int jbd2_journal_stop(handle_t *handle)
1620{
1621 transaction_t *transaction = handle->h_transaction;
1622 journal_t *journal;
1623 int err = 0, wait_for_commit = 0;
1624 tid_t tid;
1625 pid_t pid;
1626
1627 if (!transaction) {
1628 /*
1629 * Handle is already detached from the transaction so
1630 * there is nothing to do other than decrease a refcount,
1631 * or free the handle if refcount drops to zero
1632 */
1633 if (--handle->h_ref > 0) {
1634 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1635 handle->h_ref);
1636 return err;
1637 } else {
1638 if (handle->h_rsv_handle)
1639 jbd2_free_handle(handle->h_rsv_handle);
1640 goto free_and_exit;
1641 }
1642 }
1643 journal = transaction->t_journal;
1644
1645 J_ASSERT(journal_current_handle() == handle);
1646
1647 if (is_handle_aborted(handle))
1648 err = -EIO;
1649 else
1650 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
1651
1652 if (--handle->h_ref > 0) {
1653 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1654 handle->h_ref);
1655 return err;
1656 }
1657
1658 jbd_debug(4, "Handle %p going down\n", handle);
1659 trace_jbd2_handle_stats(journal->j_fs_dev->bd_dev,
1660 transaction->t_tid,
1661 handle->h_type, handle->h_line_no,
1662 jiffies - handle->h_start_jiffies,
1663 handle->h_sync, handle->h_requested_credits,
1664 (handle->h_requested_credits -
1665 handle->h_buffer_credits));
1666
1667 /*
1668 * Implement synchronous transaction batching. If the handle
1669 * was synchronous, don't force a commit immediately. Let's
1670 * yield and let another thread piggyback onto this
1671 * transaction. Keep doing that while new threads continue to
1672 * arrive. It doesn't cost much - we're about to run a commit
1673 * and sleep on IO anyway. Speeds up many-threaded, many-dir
1674 * operations by 30x or more...
1675 *
1676 * We try and optimize the sleep time against what the
1677 * underlying disk can do, instead of having a static sleep
1678 * time. This is useful for the case where our storage is so
1679 * fast that it is more optimal to go ahead and force a flush
1680 * and wait for the transaction to be committed than it is to
1681 * wait for an arbitrary amount of time for new writers to
1682 * join the transaction. We achieve this by measuring how
1683 * long it takes to commit a transaction, and compare it with
1684 * how long this transaction has been running, and if run time
1685 * < commit time then we sleep for the delta and commit. This
1686 * greatly helps super fast disks that would see slowdowns as
1687 * more threads started doing fsyncs.
1688 *
1689 * But don't do this if this process was the most recent one
1690 * to perform a synchronous write. We do this to detect the
1691 * case where a single process is doing a stream of sync
1692 * writes. No point in waiting for joiners in that case.
1693 *
1694 * Setting max_batch_time to 0 disables this completely.
1695 */
1696 pid = current->pid;
1697 if (handle->h_sync && journal->j_last_sync_writer != pid &&
1698 journal->j_max_batch_time) {
1699 u64 commit_time, trans_time;
1700
1701 journal->j_last_sync_writer = pid;
1702
1703 read_lock(&journal->j_state_lock);
1704 commit_time = journal->j_average_commit_time;
1705 read_unlock(&journal->j_state_lock);
1706
1707 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1708 transaction->t_start_time));
1709
1710 commit_time = max_t(u64, commit_time,
1711 1000*journal->j_min_batch_time);
1712 commit_time = min_t(u64, commit_time,
1713 1000*journal->j_max_batch_time);
1714
1715 if (trans_time < commit_time) {
1716 ktime_t expires = ktime_add_ns(ktime_get(),
1717 commit_time);
1718 set_current_state(TASK_UNINTERRUPTIBLE);
1719 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1720 }
1721 }
1722
1723 if (handle->h_sync)
1724 transaction->t_synchronous_commit = 1;
1725 current->journal_info = NULL;
1726 atomic_sub(handle->h_buffer_credits,
1727 &transaction->t_outstanding_credits);
1728
1729 /*
1730 * If the handle is marked SYNC, we need to set another commit
1731 * going! We also want to force a commit if the current
1732 * transaction is occupying too much of the log, or if the
1733 * transaction is too old now.
1734 */
1735 if (handle->h_sync ||
1736 (atomic_read(&transaction->t_outstanding_credits) >
1737 journal->j_max_transaction_buffers) ||
1738 time_after_eq(jiffies, transaction->t_expires)) {
1739 /* Do this even for aborted journals: an abort still
1740 * completes the commit thread, it just doesn't write
1741 * anything to disk. */
1742
1743 jbd_debug(2, "transaction too old, requesting commit for "
1744 "handle %p\n", handle);
1745 /* This is non-blocking */
1746 jbd2_log_start_commit(journal, transaction->t_tid);
1747
1748 /*
1749 * Special case: JBD2_SYNC synchronous updates require us
1750 * to wait for the commit to complete.
1751 */
1752 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1753 wait_for_commit = 1;
1754 }
1755
1756 /*
1757 * Once we drop t_updates, if it goes to zero the transaction
1758 * could start committing on us and eventually disappear. So
1759 * once we do this, we must not dereference transaction
1760 * pointer again.
1761 */
1762 tid = transaction->t_tid;
1763 if (atomic_dec_and_test(&transaction->t_updates)) {
1764 wake_up(&journal->j_wait_updates);
1765 if (journal->j_barrier_count)
1766 wake_up(&journal->j_wait_transaction_locked);
1767 }
1768
1769 rwsem_release(&journal->j_trans_commit_map, 1, _THIS_IP_);
1770
1771 if (wait_for_commit)
1772 err = jbd2_log_wait_commit(journal, tid);
1773
1774 if (handle->h_rsv_handle)
1775 jbd2_journal_free_reserved(handle->h_rsv_handle);
1776free_and_exit:
1777 /*
1778 * Scope of the GFP_NOFS context is over here and so we can restore the
1779 * original alloc context.
1780 */
1781 memalloc_nofs_restore(handle->saved_alloc_context);
1782 jbd2_free_handle(handle);
1783 return err;
1784}
1785
1786/*
1787 *
1788 * List management code snippets: various functions for manipulating the
1789 * transaction buffer lists.
1790 *
1791 */
1792
1793/*
1794 * Append a buffer to a transaction list, given the transaction's list head
1795 * pointer.
1796 *
1797 * j_list_lock is held.
1798 *
1799 * jbd_lock_bh_state(jh2bh(jh)) is held.
1800 */
1801
1802static inline void
1803__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1804{
1805 if (!*list) {
1806 jh->b_tnext = jh->b_tprev = jh;
1807 *list = jh;
1808 } else {
1809 /* Insert at the tail of the list to preserve order */
1810 struct journal_head *first = *list, *last = first->b_tprev;
1811 jh->b_tprev = last;
1812 jh->b_tnext = first;
1813 last->b_tnext = first->b_tprev = jh;
1814 }
1815}
1816
1817/*
1818 * Remove a buffer from a transaction list, given the transaction's list
1819 * head pointer.
1820 *
1821 * Called with j_list_lock held, and the journal may not be locked.
1822 *
1823 * jbd_lock_bh_state(jh2bh(jh)) is held.
1824 */
1825
1826static inline void
1827__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1828{
1829 if (*list == jh) {
1830 *list = jh->b_tnext;
1831 if (*list == jh)
1832 *list = NULL;
1833 }
1834 jh->b_tprev->b_tnext = jh->b_tnext;
1835 jh->b_tnext->b_tprev = jh->b_tprev;
1836}
1837
1838/*
1839 * Remove a buffer from the appropriate transaction list.
1840 *
1841 * Note that this function can *change* the value of
1842 * bh->b_transaction->t_buffers, t_forget, t_shadow_list, t_log_list or
1843 * t_reserved_list. If the caller is holding onto a copy of one of these
1844 * pointers, it could go bad. Generally the caller needs to re-read the
1845 * pointer from the transaction_t.
1846 *
1847 * Called under j_list_lock.
1848 */
1849static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1850{
1851 struct journal_head **list = NULL;
1852 transaction_t *transaction;
1853 struct buffer_head *bh = jh2bh(jh);
1854
1855 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1856 transaction = jh->b_transaction;
1857 if (transaction)
1858 assert_spin_locked(&transaction->t_journal->j_list_lock);
1859
1860 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1861 if (jh->b_jlist != BJ_None)
1862 J_ASSERT_JH(jh, transaction != NULL);
1863
1864 switch (jh->b_jlist) {
1865 case BJ_None:
1866 return;
1867 case BJ_Metadata:
1868 transaction->t_nr_buffers--;
1869 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1870 list = &transaction->t_buffers;
1871 break;
1872 case BJ_Forget:
1873 list = &transaction->t_forget;
1874 break;
1875 case BJ_Shadow:
1876 list = &transaction->t_shadow_list;
1877 break;
1878 case BJ_Reserved:
1879 list = &transaction->t_reserved_list;
1880 break;
1881 }
1882
1883 __blist_del_buffer(list, jh);
1884 jh->b_jlist = BJ_None;
1885 if (transaction && is_journal_aborted(transaction->t_journal))
1886 clear_buffer_jbddirty(bh);
1887 else if (test_clear_buffer_jbddirty(bh))
1888 mark_buffer_dirty(bh); /* Expose it to the VM */
1889}
1890
1891/*
1892 * Remove buffer from all transactions.
1893 *
1894 * Called with bh_state lock and j_list_lock
1895 *
1896 * jh and bh may be already freed when this function returns.
1897 */
1898static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1899{
1900 __jbd2_journal_temp_unlink_buffer(jh);
1901 jh->b_transaction = NULL;
1902 jbd2_journal_put_journal_head(jh);
1903}
1904
1905void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1906{
1907 struct buffer_head *bh = jh2bh(jh);
1908
1909 /* Get reference so that buffer cannot be freed before we unlock it */
1910 get_bh(bh);
1911 jbd_lock_bh_state(bh);
1912 spin_lock(&journal->j_list_lock);
1913 __jbd2_journal_unfile_buffer(jh);
1914 spin_unlock(&journal->j_list_lock);
1915 jbd_unlock_bh_state(bh);
1916 __brelse(bh);
1917}
1918
1919/*
1920 * Called from jbd2_journal_try_to_free_buffers().
1921 *
1922 * Called under jbd_lock_bh_state(bh)
1923 */
1924static void
1925__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1926{
1927 struct journal_head *jh;
1928
1929 jh = bh2jh(bh);
1930
1931 if (buffer_locked(bh) || buffer_dirty(bh))
1932 goto out;
1933
1934 if (jh->b_next_transaction != NULL || jh->b_transaction != NULL)
1935 goto out;
1936
1937 spin_lock(&journal->j_list_lock);
1938 if (jh->b_cp_transaction != NULL) {
1939 /* written-back checkpointed metadata buffer */
1940 JBUFFER_TRACE(jh, "remove from checkpoint list");
1941 __jbd2_journal_remove_checkpoint(jh);
1942 }
1943 spin_unlock(&journal->j_list_lock);
1944out:
1945 return;
1946}
1947
1948/**
1949 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1950 * @journal: journal for operation
1951 * @page: to try and free
1952 * @gfp_mask: we use the mask to detect how hard should we try to release
1953 * buffers. If __GFP_DIRECT_RECLAIM and __GFP_FS is set, we wait for commit
1954 * code to release the buffers.
1955 *
1956 *
1957 * For all the buffers on this page,
1958 * if they are fully written out ordered data, move them onto BUF_CLEAN
1959 * so try_to_free_buffers() can reap them.
1960 *
1961 * This function returns non-zero if we wish try_to_free_buffers()
1962 * to be called. We do this if the page is releasable by try_to_free_buffers().
1963 * We also do it if the page has locked or dirty buffers and the caller wants
1964 * us to perform sync or async writeout.
1965 *
1966 * This complicates JBD locking somewhat. We aren't protected by the
1967 * BKL here. We wish to remove the buffer from its committing or
1968 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1969 *
1970 * This may *change* the value of transaction_t->t_datalist, so anyone
1971 * who looks at t_datalist needs to lock against this function.
1972 *
1973 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
1974 * buffer. So we need to lock against that. jbd2_journal_dirty_data()
1975 * will come out of the lock with the buffer dirty, which makes it
1976 * ineligible for release here.
1977 *
1978 * Who else is affected by this? hmm... Really the only contender
1979 * is do_get_write_access() - it could be looking at the buffer while
1980 * journal_try_to_free_buffer() is changing its state. But that
1981 * cannot happen because we never reallocate freed data as metadata
1982 * while the data is part of a transaction. Yes?
1983 *
1984 * Return 0 on failure, 1 on success
1985 */
1986int jbd2_journal_try_to_free_buffers(journal_t *journal,
1987 struct page *page, gfp_t gfp_mask)
1988{
1989 struct buffer_head *head;
1990 struct buffer_head *bh;
1991 int ret = 0;
1992
1993 J_ASSERT(PageLocked(page));
1994
1995 head = page_buffers(page);
1996 bh = head;
1997 do {
1998 struct journal_head *jh;
1999
2000 /*
2001 * We take our own ref against the journal_head here to avoid
2002 * having to add tons of locking around each instance of
2003 * jbd2_journal_put_journal_head().
2004 */
2005 jh = jbd2_journal_grab_journal_head(bh);
2006 if (!jh)
2007 continue;
2008
2009 jbd_lock_bh_state(bh);
2010 __journal_try_to_free_buffer(journal, bh);
2011 jbd2_journal_put_journal_head(jh);
2012 jbd_unlock_bh_state(bh);
2013 if (buffer_jbd(bh))
2014 goto busy;
2015 } while ((bh = bh->b_this_page) != head);
2016
2017 ret = try_to_free_buffers(page);
2018
2019busy:
2020 return ret;
2021}
2022
2023/*
2024 * This buffer is no longer needed. If it is on an older transaction's
2025 * checkpoint list we need to record it on this transaction's forget list
2026 * to pin this buffer (and hence its checkpointing transaction) down until
2027 * this transaction commits. If the buffer isn't on a checkpoint list, we
2028 * release it.
2029 * Returns non-zero if JBD no longer has an interest in the buffer.
2030 *
2031 * Called under j_list_lock.
2032 *
2033 * Called under jbd_lock_bh_state(bh).
2034 */
2035static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
2036{
2037 int may_free = 1;
2038 struct buffer_head *bh = jh2bh(jh);
2039
2040 if (jh->b_cp_transaction) {
2041 JBUFFER_TRACE(jh, "on running+cp transaction");
2042 __jbd2_journal_temp_unlink_buffer(jh);
2043 /*
2044 * We don't want to write the buffer anymore, clear the
2045 * bit so that we don't confuse checks in
2046 * __journal_file_buffer
2047 */
2048 clear_buffer_dirty(bh);
2049 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
2050 may_free = 0;
2051 } else {
2052 JBUFFER_TRACE(jh, "on running transaction");
2053 __jbd2_journal_unfile_buffer(jh);
2054 }
2055 return may_free;
2056}
2057
2058/*
2059 * jbd2_journal_invalidatepage
2060 *
2061 * This code is tricky. It has a number of cases to deal with.
2062 *
2063 * There are two invariants which this code relies on:
2064 *
2065 * i_size must be updated on disk before we start calling invalidatepage on the
2066 * data.
2067 *
2068 * This is done in ext3 by defining an ext3_setattr method which
2069 * updates i_size before truncate gets going. By maintaining this
2070 * invariant, we can be sure that it is safe to throw away any buffers
2071 * attached to the current transaction: once the transaction commits,
2072 * we know that the data will not be needed.
2073 *
2074 * Note however that we can *not* throw away data belonging to the
2075 * previous, committing transaction!
2076 *
2077 * Any disk blocks which *are* part of the previous, committing
2078 * transaction (and which therefore cannot be discarded immediately) are
2079 * not going to be reused in the new running transaction
2080 *
2081 * The bitmap committed_data images guarantee this: any block which is
2082 * allocated in one transaction and removed in the next will be marked
2083 * as in-use in the committed_data bitmap, so cannot be reused until
2084 * the next transaction to delete the block commits. This means that
2085 * leaving committing buffers dirty is quite safe: the disk blocks
2086 * cannot be reallocated to a different file and so buffer aliasing is
2087 * not possible.
2088 *
2089 *
2090 * The above applies mainly to ordered data mode. In writeback mode we
2091 * don't make guarantees about the order in which data hits disk --- in
2092 * particular we don't guarantee that new dirty data is flushed before
2093 * transaction commit --- so it is always safe just to discard data
2094 * immediately in that mode. --sct
2095 */
2096
2097/*
2098 * The journal_unmap_buffer helper function returns zero if the buffer
2099 * concerned remains pinned as an anonymous buffer belonging to an older
2100 * transaction.
2101 *
2102 * We're outside-transaction here. Either or both of j_running_transaction
2103 * and j_committing_transaction may be NULL.
2104 */
2105static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
2106 int partial_page)
2107{
2108 transaction_t *transaction;
2109 struct journal_head *jh;
2110 int may_free = 1;
2111
2112 BUFFER_TRACE(bh, "entry");
2113
2114 /*
2115 * It is safe to proceed here without the j_list_lock because the
2116 * buffers cannot be stolen by try_to_free_buffers as long as we are
2117 * holding the page lock. --sct
2118 */
2119
2120 if (!buffer_jbd(bh))
2121 goto zap_buffer_unlocked;
2122
2123 /* OK, we have data buffer in journaled mode */
2124 write_lock(&journal->j_state_lock);
2125 jbd_lock_bh_state(bh);
2126 spin_lock(&journal->j_list_lock);
2127
2128 jh = jbd2_journal_grab_journal_head(bh);
2129 if (!jh)
2130 goto zap_buffer_no_jh;
2131
2132 /*
2133 * We cannot remove the buffer from checkpoint lists until the
2134 * transaction adding inode to orphan list (let's call it T)
2135 * is committed. Otherwise if the transaction changing the
2136 * buffer would be cleaned from the journal before T is
2137 * committed, a crash will cause that the correct contents of
2138 * the buffer will be lost. On the other hand we have to
2139 * clear the buffer dirty bit at latest at the moment when the
2140 * transaction marking the buffer as freed in the filesystem
2141 * structures is committed because from that moment on the
2142 * block can be reallocated and used by a different page.
2143 * Since the block hasn't been freed yet but the inode has
2144 * already been added to orphan list, it is safe for us to add
2145 * the buffer to BJ_Forget list of the newest transaction.
2146 *
2147 * Also we have to clear buffer_mapped flag of a truncated buffer
2148 * because the buffer_head may be attached to the page straddling
2149 * i_size (can happen only when blocksize < pagesize) and thus the
2150 * buffer_head can be reused when the file is extended again. So we end
2151 * up keeping around invalidated buffers attached to transactions'
2152 * BJ_Forget list just to stop checkpointing code from cleaning up
2153 * the transaction this buffer was modified in.
2154 */
2155 transaction = jh->b_transaction;
2156 if (transaction == NULL) {
2157 /* First case: not on any transaction. If it
2158 * has no checkpoint link, then we can zap it:
2159 * it's a writeback-mode buffer so we don't care
2160 * if it hits disk safely. */
2161 if (!jh->b_cp_transaction) {
2162 JBUFFER_TRACE(jh, "not on any transaction: zap");
2163 goto zap_buffer;
2164 }
2165
2166 if (!buffer_dirty(bh)) {
2167 /* bdflush has written it. We can drop it now */
2168 __jbd2_journal_remove_checkpoint(jh);
2169 goto zap_buffer;
2170 }
2171
2172 /* OK, it must be in the journal but still not
2173 * written fully to disk: it's metadata or
2174 * journaled data... */
2175
2176 if (journal->j_running_transaction) {
2177 /* ... and once the current transaction has
2178 * committed, the buffer won't be needed any
2179 * longer. */
2180 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
2181 may_free = __dispose_buffer(jh,
2182 journal->j_running_transaction);
2183 goto zap_buffer;
2184 } else {
2185 /* There is no currently-running transaction. So the
2186 * orphan record which we wrote for this file must have
2187 * passed into commit. We must attach this buffer to
2188 * the committing transaction, if it exists. */
2189 if (journal->j_committing_transaction) {
2190 JBUFFER_TRACE(jh, "give to committing trans");
2191 may_free = __dispose_buffer(jh,
2192 journal->j_committing_transaction);
2193 goto zap_buffer;
2194 } else {
2195 /* The orphan record's transaction has
2196 * committed. We can cleanse this buffer */
2197 clear_buffer_jbddirty(bh);
2198 __jbd2_journal_remove_checkpoint(jh);
2199 goto zap_buffer;
2200 }
2201 }
2202 } else if (transaction == journal->j_committing_transaction) {
2203 JBUFFER_TRACE(jh, "on committing transaction");
2204 /*
2205 * The buffer is committing, we simply cannot touch
2206 * it. If the page is straddling i_size we have to wait
2207 * for commit and try again.
2208 */
2209 if (partial_page) {
2210 jbd2_journal_put_journal_head(jh);
2211 spin_unlock(&journal->j_list_lock);
2212 jbd_unlock_bh_state(bh);
2213 write_unlock(&journal->j_state_lock);
2214 return -EBUSY;
2215 }
2216 /*
2217 * OK, buffer won't be reachable after truncate. We just set
2218 * j_next_transaction to the running transaction (if there is
2219 * one) and mark buffer as freed so that commit code knows it
2220 * should clear dirty bits when it is done with the buffer.
2221 */
2222 set_buffer_freed(bh);
2223 if (journal->j_running_transaction && buffer_jbddirty(bh))
2224 jh->b_next_transaction = journal->j_running_transaction;
2225 jbd2_journal_put_journal_head(jh);
2226 spin_unlock(&journal->j_list_lock);
2227 jbd_unlock_bh_state(bh);
2228 write_unlock(&journal->j_state_lock);
2229 return 0;
2230 } else {
2231 /* Good, the buffer belongs to the running transaction.
2232 * We are writing our own transaction's data, not any
2233 * previous one's, so it is safe to throw it away
2234 * (remember that we expect the filesystem to have set
2235 * i_size already for this truncate so recovery will not
2236 * expose the disk blocks we are discarding here.) */
2237 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
2238 JBUFFER_TRACE(jh, "on running transaction");
2239 may_free = __dispose_buffer(jh, transaction);
2240 }
2241
2242zap_buffer:
2243 /*
2244 * This is tricky. Although the buffer is truncated, it may be reused
2245 * if blocksize < pagesize and it is attached to the page straddling
2246 * EOF. Since the buffer might have been added to BJ_Forget list of the
2247 * running transaction, journal_get_write_access() won't clear
2248 * b_modified and credit accounting gets confused. So clear b_modified
2249 * here.
2250 */
2251 jh->b_modified = 0;
2252 jbd2_journal_put_journal_head(jh);
2253zap_buffer_no_jh:
2254 spin_unlock(&journal->j_list_lock);
2255 jbd_unlock_bh_state(bh);
2256 write_unlock(&journal->j_state_lock);
2257zap_buffer_unlocked:
2258 clear_buffer_dirty(bh);
2259 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
2260 clear_buffer_mapped(bh);
2261 clear_buffer_req(bh);
2262 clear_buffer_new(bh);
2263 clear_buffer_delay(bh);
2264 clear_buffer_unwritten(bh);
2265 bh->b_bdev = NULL;
2266 return may_free;
2267}
2268
2269/**
2270 * void jbd2_journal_invalidatepage()
2271 * @journal: journal to use for flush...
2272 * @page: page to flush
2273 * @offset: start of the range to invalidate
2274 * @length: length of the range to invalidate
2275 *
2276 * Reap page buffers containing data after in the specified range in page.
2277 * Can return -EBUSY if buffers are part of the committing transaction and
2278 * the page is straddling i_size. Caller then has to wait for current commit
2279 * and try again.
2280 */
2281int jbd2_journal_invalidatepage(journal_t *journal,
2282 struct page *page,
2283 unsigned int offset,
2284 unsigned int length)
2285{
2286 struct buffer_head *head, *bh, *next;
2287 unsigned int stop = offset + length;
2288 unsigned int curr_off = 0;
2289 int partial_page = (offset || length < PAGE_SIZE);
2290 int may_free = 1;
2291 int ret = 0;
2292
2293 if (!PageLocked(page))
2294 BUG();
2295 if (!page_has_buffers(page))
2296 return 0;
2297
2298 BUG_ON(stop > PAGE_SIZE || stop < length);
2299
2300 /* We will potentially be playing with lists other than just the
2301 * data lists (especially for journaled data mode), so be
2302 * cautious in our locking. */
2303
2304 head = bh = page_buffers(page);
2305 do {
2306 unsigned int next_off = curr_off + bh->b_size;
2307 next = bh->b_this_page;
2308
2309 if (next_off > stop)
2310 return 0;
2311
2312 if (offset <= curr_off) {
2313 /* This block is wholly outside the truncation point */
2314 lock_buffer(bh);
2315 ret = journal_unmap_buffer(journal, bh, partial_page);
2316 unlock_buffer(bh);
2317 if (ret < 0)
2318 return ret;
2319 may_free &= ret;
2320 }
2321 curr_off = next_off;
2322 bh = next;
2323
2324 } while (bh != head);
2325
2326 if (!partial_page) {
2327 if (may_free && try_to_free_buffers(page))
2328 J_ASSERT(!page_has_buffers(page));
2329 }
2330 return 0;
2331}
2332
2333/*
2334 * File a buffer on the given transaction list.
2335 */
2336void __jbd2_journal_file_buffer(struct journal_head *jh,
2337 transaction_t *transaction, int jlist)
2338{
2339 struct journal_head **list = NULL;
2340 int was_dirty = 0;
2341 struct buffer_head *bh = jh2bh(jh);
2342
2343 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2344 assert_spin_locked(&transaction->t_journal->j_list_lock);
2345
2346 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2347 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2348 jh->b_transaction == NULL);
2349
2350 if (jh->b_transaction && jh->b_jlist == jlist)
2351 return;
2352
2353 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
2354 jlist == BJ_Shadow || jlist == BJ_Forget) {
2355 /*
2356 * For metadata buffers, we track dirty bit in buffer_jbddirty
2357 * instead of buffer_dirty. We should not see a dirty bit set
2358 * here because we clear it in do_get_write_access but e.g.
2359 * tune2fs can modify the sb and set the dirty bit at any time
2360 * so we try to gracefully handle that.
2361 */
2362 if (buffer_dirty(bh))
2363 warn_dirty_buffer(bh);
2364 if (test_clear_buffer_dirty(bh) ||
2365 test_clear_buffer_jbddirty(bh))
2366 was_dirty = 1;
2367 }
2368
2369 if (jh->b_transaction)
2370 __jbd2_journal_temp_unlink_buffer(jh);
2371 else
2372 jbd2_journal_grab_journal_head(bh);
2373 jh->b_transaction = transaction;
2374
2375 switch (jlist) {
2376 case BJ_None:
2377 J_ASSERT_JH(jh, !jh->b_committed_data);
2378 J_ASSERT_JH(jh, !jh->b_frozen_data);
2379 return;
2380 case BJ_Metadata:
2381 transaction->t_nr_buffers++;
2382 list = &transaction->t_buffers;
2383 break;
2384 case BJ_Forget:
2385 list = &transaction->t_forget;
2386 break;
2387 case BJ_Shadow:
2388 list = &transaction->t_shadow_list;
2389 break;
2390 case BJ_Reserved:
2391 list = &transaction->t_reserved_list;
2392 break;
2393 }
2394
2395 __blist_add_buffer(list, jh);
2396 jh->b_jlist = jlist;
2397
2398 if (was_dirty)
2399 set_buffer_jbddirty(bh);
2400}
2401
2402void jbd2_journal_file_buffer(struct journal_head *jh,
2403 transaction_t *transaction, int jlist)
2404{
2405 jbd_lock_bh_state(jh2bh(jh));
2406 spin_lock(&transaction->t_journal->j_list_lock);
2407 __jbd2_journal_file_buffer(jh, transaction, jlist);
2408 spin_unlock(&transaction->t_journal->j_list_lock);
2409 jbd_unlock_bh_state(jh2bh(jh));
2410}
2411
2412/*
2413 * Remove a buffer from its current buffer list in preparation for
2414 * dropping it from its current transaction entirely. If the buffer has
2415 * already started to be used by a subsequent transaction, refile the
2416 * buffer on that transaction's metadata list.
2417 *
2418 * Called under j_list_lock
2419 * Called under jbd_lock_bh_state(jh2bh(jh))
2420 *
2421 * jh and bh may be already free when this function returns
2422 */
2423void __jbd2_journal_refile_buffer(struct journal_head *jh)
2424{
2425 int was_dirty, jlist;
2426 struct buffer_head *bh = jh2bh(jh);
2427
2428 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2429 if (jh->b_transaction)
2430 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2431
2432 /* If the buffer is now unused, just drop it. */
2433 if (jh->b_next_transaction == NULL) {
2434 __jbd2_journal_unfile_buffer(jh);
2435 return;
2436 }
2437
2438 /*
2439 * It has been modified by a later transaction: add it to the new
2440 * transaction's metadata list.
2441 */
2442
2443 was_dirty = test_clear_buffer_jbddirty(bh);
2444 __jbd2_journal_temp_unlink_buffer(jh);
2445 /*
2446 * We set b_transaction here because b_next_transaction will inherit
2447 * our jh reference and thus __jbd2_journal_file_buffer() must not
2448 * take a new one.
2449 */
2450 jh->b_transaction = jh->b_next_transaction;
2451 jh->b_next_transaction = NULL;
2452 if (buffer_freed(bh))
2453 jlist = BJ_Forget;
2454 else if (jh->b_modified)
2455 jlist = BJ_Metadata;
2456 else
2457 jlist = BJ_Reserved;
2458 __jbd2_journal_file_buffer(jh, jh->b_transaction, jlist);
2459 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2460
2461 if (was_dirty)
2462 set_buffer_jbddirty(bh);
2463}
2464
2465/*
2466 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
2467 * bh reference so that we can safely unlock bh.
2468 *
2469 * The jh and bh may be freed by this call.
2470 */
2471void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2472{
2473 struct buffer_head *bh = jh2bh(jh);
2474
2475 /* Get reference so that buffer cannot be freed before we unlock it */
2476 get_bh(bh);
2477 jbd_lock_bh_state(bh);
2478 spin_lock(&journal->j_list_lock);
2479 __jbd2_journal_refile_buffer(jh);
2480 jbd_unlock_bh_state(bh);
2481 spin_unlock(&journal->j_list_lock);
2482 __brelse(bh);
2483}
2484
2485/*
2486 * File inode in the inode list of the handle's transaction
2487 */
2488static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
2489 unsigned long flags)
2490{
2491 transaction_t *transaction = handle->h_transaction;
2492 journal_t *journal;
2493
2494 if (is_handle_aborted(handle))
2495 return -EROFS;
2496 journal = transaction->t_journal;
2497
2498 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
2499 transaction->t_tid);
2500
2501 /*
2502 * First check whether inode isn't already on the transaction's
2503 * lists without taking the lock. Note that this check is safe
2504 * without the lock as we cannot race with somebody removing inode
2505 * from the transaction. The reason is that we remove inode from the
2506 * transaction only in journal_release_jbd_inode() and when we commit
2507 * the transaction. We are guarded from the first case by holding
2508 * a reference to the inode. We are safe against the second case
2509 * because if jinode->i_transaction == transaction, commit code
2510 * cannot touch the transaction because we hold reference to it,
2511 * and if jinode->i_next_transaction == transaction, commit code
2512 * will only file the inode where we want it.
2513 */
2514 if ((jinode->i_transaction == transaction ||
2515 jinode->i_next_transaction == transaction) &&
2516 (jinode->i_flags & flags) == flags)
2517 return 0;
2518
2519 spin_lock(&journal->j_list_lock);
2520 jinode->i_flags |= flags;
2521 /* Is inode already attached where we need it? */
2522 if (jinode->i_transaction == transaction ||
2523 jinode->i_next_transaction == transaction)
2524 goto done;
2525
2526 /*
2527 * We only ever set this variable to 1 so the test is safe. Since
2528 * t_need_data_flush is likely to be set, we do the test to save some
2529 * cacheline bouncing
2530 */
2531 if (!transaction->t_need_data_flush)
2532 transaction->t_need_data_flush = 1;
2533 /* On some different transaction's list - should be
2534 * the committing one */
2535 if (jinode->i_transaction) {
2536 J_ASSERT(jinode->i_next_transaction == NULL);
2537 J_ASSERT(jinode->i_transaction ==
2538 journal->j_committing_transaction);
2539 jinode->i_next_transaction = transaction;
2540 goto done;
2541 }
2542 /* Not on any transaction list... */
2543 J_ASSERT(!jinode->i_next_transaction);
2544 jinode->i_transaction = transaction;
2545 list_add(&jinode->i_list, &transaction->t_inode_list);
2546done:
2547 spin_unlock(&journal->j_list_lock);
2548
2549 return 0;
2550}
2551
2552int jbd2_journal_inode_add_write(handle_t *handle, struct jbd2_inode *jinode)
2553{
2554 return jbd2_journal_file_inode(handle, jinode,
2555 JI_WRITE_DATA | JI_WAIT_DATA);
2556}
2557
2558int jbd2_journal_inode_add_wait(handle_t *handle, struct jbd2_inode *jinode)
2559{
2560 return jbd2_journal_file_inode(handle, jinode, JI_WAIT_DATA);
2561}
2562
2563/*
2564 * File truncate and transaction commit interact with each other in a
2565 * non-trivial way. If a transaction writing data block A is
2566 * committing, we cannot discard the data by truncate until we have
2567 * written them. Otherwise if we crashed after the transaction with
2568 * write has committed but before the transaction with truncate has
2569 * committed, we could see stale data in block A. This function is a
2570 * helper to solve this problem. It starts writeout of the truncated
2571 * part in case it is in the committing transaction.
2572 *
2573 * Filesystem code must call this function when inode is journaled in
2574 * ordered mode before truncation happens and after the inode has been
2575 * placed on orphan list with the new inode size. The second condition
2576 * avoids the race that someone writes new data and we start
2577 * committing the transaction after this function has been called but
2578 * before a transaction for truncate is started (and furthermore it
2579 * allows us to optimize the case where the addition to orphan list
2580 * happens in the same transaction as write --- we don't have to write
2581 * any data in such case).
2582 */
2583int jbd2_journal_begin_ordered_truncate(journal_t *journal,
2584 struct jbd2_inode *jinode,
2585 loff_t new_size)
2586{
2587 transaction_t *inode_trans, *commit_trans;
2588 int ret = 0;
2589
2590 /* This is a quick check to avoid locking if not necessary */
2591 if (!jinode->i_transaction)
2592 goto out;
2593 /* Locks are here just to force reading of recent values, it is
2594 * enough that the transaction was not committing before we started
2595 * a transaction adding the inode to orphan list */
2596 read_lock(&journal->j_state_lock);
2597 commit_trans = journal->j_committing_transaction;
2598 read_unlock(&journal->j_state_lock);
2599 spin_lock(&journal->j_list_lock);
2600 inode_trans = jinode->i_transaction;
2601 spin_unlock(&journal->j_list_lock);
2602 if (inode_trans == commit_trans) {
2603 ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping,
2604 new_size, LLONG_MAX);
2605 if (ret)
2606 jbd2_journal_abort(journal, ret);
2607 }
2608out:
2609 return ret;
2610}
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * linux/fs/jbd2/transaction.c
4 *
5 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
6 *
7 * Copyright 1998 Red Hat corp --- All Rights Reserved
8 *
9 * Generic filesystem transaction handling code; part of the ext2fs
10 * journaling system.
11 *
12 * This file manages transactions (compound commits managed by the
13 * journaling code) and handles (individual atomic operations by the
14 * filesystem).
15 */
16
17#include <linux/time.h>
18#include <linux/fs.h>
19#include <linux/jbd2.h>
20#include <linux/errno.h>
21#include <linux/slab.h>
22#include <linux/timer.h>
23#include <linux/mm.h>
24#include <linux/highmem.h>
25#include <linux/hrtimer.h>
26#include <linux/backing-dev.h>
27#include <linux/bug.h>
28#include <linux/module.h>
29#include <linux/sched/mm.h>
30
31#include <trace/events/jbd2.h>
32
33static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
34static void __jbd2_journal_unfile_buffer(struct journal_head *jh);
35
36static struct kmem_cache *transaction_cache;
37int __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 pr_emerg("JBD2: failed to create transaction cache\n");
47 return -ENOMEM;
48 }
49 return 0;
50}
51
52void jbd2_journal_destroy_transaction_cache(void)
53{
54 kmem_cache_destroy(transaction_cache);
55 transaction_cache = NULL;
56}
57
58void 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 * Base amount of descriptor blocks we reserve for each transaction.
67 */
68static int jbd2_descriptor_blocks_per_trans(journal_t *journal)
69{
70 int tag_space = journal->j_blocksize - sizeof(journal_header_t);
71 int tags_per_block;
72
73 /* Subtract UUID */
74 tag_space -= 16;
75 if (jbd2_journal_has_csum_v2or3(journal))
76 tag_space -= sizeof(struct jbd2_journal_block_tail);
77 /* Commit code leaves a slack space of 16 bytes at the end of block */
78 tags_per_block = (tag_space - 16) / journal_tag_bytes(journal);
79 /*
80 * Revoke descriptors are accounted separately so we need to reserve
81 * space for commit block and normal transaction descriptor blocks.
82 */
83 return 1 + DIV_ROUND_UP(journal->j_max_transaction_buffers,
84 tags_per_block);
85}
86
87/*
88 * jbd2_get_transaction: obtain a new transaction_t object.
89 *
90 * Simply initialise a new transaction. Initialize it in
91 * RUNNING state and add it to the current journal (which should not
92 * have an existing running transaction: we only make a new transaction
93 * once we have started to commit the old one).
94 *
95 * Preconditions:
96 * The journal MUST be locked. We don't perform atomic mallocs on the
97 * new transaction and we can't block without protecting against other
98 * processes trying to touch the journal while it is in transition.
99 *
100 */
101
102static void jbd2_get_transaction(journal_t *journal,
103 transaction_t *transaction)
104{
105 transaction->t_journal = journal;
106 transaction->t_state = T_RUNNING;
107 transaction->t_start_time = ktime_get();
108 transaction->t_tid = journal->j_transaction_sequence++;
109 transaction->t_expires = jiffies + journal->j_commit_interval;
110 atomic_set(&transaction->t_updates, 0);
111 atomic_set(&transaction->t_outstanding_credits,
112 jbd2_descriptor_blocks_per_trans(journal) +
113 atomic_read(&journal->j_reserved_credits));
114 atomic_set(&transaction->t_outstanding_revokes, 0);
115 atomic_set(&transaction->t_handle_count, 0);
116 INIT_LIST_HEAD(&transaction->t_inode_list);
117 INIT_LIST_HEAD(&transaction->t_private_list);
118
119 /* Set up the commit timer for the new transaction. */
120 journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires);
121 add_timer(&journal->j_commit_timer);
122
123 J_ASSERT(journal->j_running_transaction == NULL);
124 journal->j_running_transaction = transaction;
125 transaction->t_max_wait = 0;
126 transaction->t_start = jiffies;
127 transaction->t_requested = 0;
128}
129
130/*
131 * Handle management.
132 *
133 * A handle_t is an object which represents a single atomic update to a
134 * filesystem, and which tracks all of the modifications which form part
135 * of that one update.
136 */
137
138/*
139 * Update transaction's maximum wait time, if debugging is enabled.
140 *
141 * t_max_wait is carefully updated here with use of atomic compare exchange.
142 * Note that there could be multiplre threads trying to do this simultaneously
143 * hence using cmpxchg to avoid any use of locks in this case.
144 * With this t_max_wait can be updated w/o enabling jbd2_journal_enable_debug.
145 */
146static inline void update_t_max_wait(transaction_t *transaction,
147 unsigned long ts)
148{
149 unsigned long oldts, newts;
150
151 if (time_after(transaction->t_start, ts)) {
152 newts = jbd2_time_diff(ts, transaction->t_start);
153 oldts = READ_ONCE(transaction->t_max_wait);
154 while (oldts < newts)
155 oldts = cmpxchg(&transaction->t_max_wait, oldts, newts);
156 }
157}
158
159/*
160 * Wait until running transaction passes to T_FLUSH state and new transaction
161 * can thus be started. Also starts the commit if needed. The function expects
162 * running transaction to exist and releases j_state_lock.
163 */
164static void wait_transaction_locked(journal_t *journal)
165 __releases(journal->j_state_lock)
166{
167 DEFINE_WAIT(wait);
168 int need_to_start;
169 tid_t tid = journal->j_running_transaction->t_tid;
170
171 prepare_to_wait_exclusive(&journal->j_wait_transaction_locked, &wait,
172 TASK_UNINTERRUPTIBLE);
173 need_to_start = !tid_geq(journal->j_commit_request, tid);
174 read_unlock(&journal->j_state_lock);
175 if (need_to_start)
176 jbd2_log_start_commit(journal, tid);
177 jbd2_might_wait_for_commit(journal);
178 schedule();
179 finish_wait(&journal->j_wait_transaction_locked, &wait);
180}
181
182/*
183 * Wait until running transaction transitions from T_SWITCH to T_FLUSH
184 * state and new transaction can thus be started. The function releases
185 * j_state_lock.
186 */
187static void wait_transaction_switching(journal_t *journal)
188 __releases(journal->j_state_lock)
189{
190 DEFINE_WAIT(wait);
191
192 if (WARN_ON(!journal->j_running_transaction ||
193 journal->j_running_transaction->t_state != T_SWITCH)) {
194 read_unlock(&journal->j_state_lock);
195 return;
196 }
197 prepare_to_wait_exclusive(&journal->j_wait_transaction_locked, &wait,
198 TASK_UNINTERRUPTIBLE);
199 read_unlock(&journal->j_state_lock);
200 /*
201 * We don't call jbd2_might_wait_for_commit() here as there's no
202 * waiting for outstanding handles happening anymore in T_SWITCH state
203 * and handling of reserved handles actually relies on that for
204 * correctness.
205 */
206 schedule();
207 finish_wait(&journal->j_wait_transaction_locked, &wait);
208}
209
210static void sub_reserved_credits(journal_t *journal, int blocks)
211{
212 atomic_sub(blocks, &journal->j_reserved_credits);
213 wake_up(&journal->j_wait_reserved);
214}
215
216/*
217 * Wait until we can add credits for handle to the running transaction. Called
218 * with j_state_lock held for reading. Returns 0 if handle joined the running
219 * transaction. Returns 1 if we had to wait, j_state_lock is dropped, and
220 * caller must retry.
221 *
222 * Note: because j_state_lock may be dropped depending on the return
223 * value, we need to fake out sparse so ti doesn't complain about a
224 * locking imbalance. Callers of add_transaction_credits will need to
225 * make a similar accomodation.
226 */
227static int add_transaction_credits(journal_t *journal, int blocks,
228 int rsv_blocks)
229__must_hold(&journal->j_state_lock)
230{
231 transaction_t *t = journal->j_running_transaction;
232 int needed;
233 int total = blocks + rsv_blocks;
234
235 /*
236 * If the current transaction is locked down for commit, wait
237 * for the lock to be released.
238 */
239 if (t->t_state != T_RUNNING) {
240 WARN_ON_ONCE(t->t_state >= T_FLUSH);
241 wait_transaction_locked(journal);
242 __acquire(&journal->j_state_lock); /* fake out sparse */
243 return 1;
244 }
245
246 /*
247 * If there is not enough space left in the log to write all
248 * potential buffers requested by this operation, we need to
249 * stall pending a log checkpoint to free some more log space.
250 */
251 needed = atomic_add_return(total, &t->t_outstanding_credits);
252 if (needed > journal->j_max_transaction_buffers) {
253 /*
254 * If the current transaction is already too large,
255 * then start to commit it: we can then go back and
256 * attach this handle to a new transaction.
257 */
258 atomic_sub(total, &t->t_outstanding_credits);
259
260 /*
261 * Is the number of reserved credits in the current transaction too
262 * big to fit this handle? Wait until reserved credits are freed.
263 */
264 if (atomic_read(&journal->j_reserved_credits) + total >
265 journal->j_max_transaction_buffers) {
266 read_unlock(&journal->j_state_lock);
267 jbd2_might_wait_for_commit(journal);
268 wait_event(journal->j_wait_reserved,
269 atomic_read(&journal->j_reserved_credits) + total <=
270 journal->j_max_transaction_buffers);
271 __acquire(&journal->j_state_lock); /* fake out sparse */
272 return 1;
273 }
274
275 wait_transaction_locked(journal);
276 __acquire(&journal->j_state_lock); /* fake out sparse */
277 return 1;
278 }
279
280 /*
281 * The commit code assumes that it can get enough log space
282 * without forcing a checkpoint. This is *critical* for
283 * correctness: a checkpoint of a buffer which is also
284 * associated with a committing transaction creates a deadlock,
285 * so commit simply cannot force through checkpoints.
286 *
287 * We must therefore ensure the necessary space in the journal
288 * *before* starting to dirty potentially checkpointed buffers
289 * in the new transaction.
290 */
291 if (jbd2_log_space_left(journal) < journal->j_max_transaction_buffers) {
292 atomic_sub(total, &t->t_outstanding_credits);
293 read_unlock(&journal->j_state_lock);
294 jbd2_might_wait_for_commit(journal);
295 write_lock(&journal->j_state_lock);
296 if (jbd2_log_space_left(journal) <
297 journal->j_max_transaction_buffers)
298 __jbd2_log_wait_for_space(journal);
299 write_unlock(&journal->j_state_lock);
300 __acquire(&journal->j_state_lock); /* fake out sparse */
301 return 1;
302 }
303
304 /* No reservation? We are done... */
305 if (!rsv_blocks)
306 return 0;
307
308 needed = atomic_add_return(rsv_blocks, &journal->j_reserved_credits);
309 /* We allow at most half of a transaction to be reserved */
310 if (needed > journal->j_max_transaction_buffers / 2) {
311 sub_reserved_credits(journal, rsv_blocks);
312 atomic_sub(total, &t->t_outstanding_credits);
313 read_unlock(&journal->j_state_lock);
314 jbd2_might_wait_for_commit(journal);
315 wait_event(journal->j_wait_reserved,
316 atomic_read(&journal->j_reserved_credits) + rsv_blocks
317 <= journal->j_max_transaction_buffers / 2);
318 __acquire(&journal->j_state_lock); /* fake out sparse */
319 return 1;
320 }
321 return 0;
322}
323
324/*
325 * start_this_handle: Given a handle, deal with any locking or stalling
326 * needed to make sure that there is enough journal space for the handle
327 * to begin. Attach the handle to a transaction and set up the
328 * transaction's buffer credits.
329 */
330
331static int start_this_handle(journal_t *journal, handle_t *handle,
332 gfp_t gfp_mask)
333{
334 transaction_t *transaction, *new_transaction = NULL;
335 int blocks = handle->h_total_credits;
336 int rsv_blocks = 0;
337 unsigned long ts = jiffies;
338
339 if (handle->h_rsv_handle)
340 rsv_blocks = handle->h_rsv_handle->h_total_credits;
341
342 /*
343 * Limit the number of reserved credits to 1/2 of maximum transaction
344 * size and limit the number of total credits to not exceed maximum
345 * transaction size per operation.
346 */
347 if ((rsv_blocks > journal->j_max_transaction_buffers / 2) ||
348 (rsv_blocks + blocks > journal->j_max_transaction_buffers)) {
349 printk(KERN_ERR "JBD2: %s wants too many credits "
350 "credits:%d rsv_credits:%d max:%d\n",
351 current->comm, blocks, rsv_blocks,
352 journal->j_max_transaction_buffers);
353 WARN_ON(1);
354 return -ENOSPC;
355 }
356
357alloc_transaction:
358 /*
359 * This check is racy but it is just an optimization of allocating new
360 * transaction early if there are high chances we'll need it. If we
361 * guess wrong, we'll retry or free unused transaction.
362 */
363 if (!data_race(journal->j_running_transaction)) {
364 /*
365 * If __GFP_FS is not present, then we may be being called from
366 * inside the fs writeback layer, so we MUST NOT fail.
367 */
368 if ((gfp_mask & __GFP_FS) == 0)
369 gfp_mask |= __GFP_NOFAIL;
370 new_transaction = kmem_cache_zalloc(transaction_cache,
371 gfp_mask);
372 if (!new_transaction)
373 return -ENOMEM;
374 }
375
376 jbd2_debug(3, "New handle %p going live.\n", handle);
377
378 /*
379 * We need to hold j_state_lock until t_updates has been incremented,
380 * for proper journal barrier handling
381 */
382repeat:
383 read_lock(&journal->j_state_lock);
384 BUG_ON(journal->j_flags & JBD2_UNMOUNT);
385 if (is_journal_aborted(journal) ||
386 (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
387 read_unlock(&journal->j_state_lock);
388 jbd2_journal_free_transaction(new_transaction);
389 return -EROFS;
390 }
391
392 /*
393 * Wait on the journal's transaction barrier if necessary. Specifically
394 * we allow reserved handles to proceed because otherwise commit could
395 * deadlock on page writeback not being able to complete.
396 */
397 if (!handle->h_reserved && journal->j_barrier_count) {
398 read_unlock(&journal->j_state_lock);
399 wait_event(journal->j_wait_transaction_locked,
400 journal->j_barrier_count == 0);
401 goto repeat;
402 }
403
404 if (!journal->j_running_transaction) {
405 read_unlock(&journal->j_state_lock);
406 if (!new_transaction)
407 goto alloc_transaction;
408 write_lock(&journal->j_state_lock);
409 if (!journal->j_running_transaction &&
410 (handle->h_reserved || !journal->j_barrier_count)) {
411 jbd2_get_transaction(journal, new_transaction);
412 new_transaction = NULL;
413 }
414 write_unlock(&journal->j_state_lock);
415 goto repeat;
416 }
417
418 transaction = journal->j_running_transaction;
419
420 if (!handle->h_reserved) {
421 /* We may have dropped j_state_lock - restart in that case */
422 if (add_transaction_credits(journal, blocks, rsv_blocks)) {
423 /*
424 * add_transaction_credits releases
425 * j_state_lock on a non-zero return
426 */
427 __release(&journal->j_state_lock);
428 goto repeat;
429 }
430 } else {
431 /*
432 * We have handle reserved so we are allowed to join T_LOCKED
433 * transaction and we don't have to check for transaction size
434 * and journal space. But we still have to wait while running
435 * transaction is being switched to a committing one as it
436 * won't wait for any handles anymore.
437 */
438 if (transaction->t_state == T_SWITCH) {
439 wait_transaction_switching(journal);
440 goto repeat;
441 }
442 sub_reserved_credits(journal, blocks);
443 handle->h_reserved = 0;
444 }
445
446 /* OK, account for the buffers that this operation expects to
447 * use and add the handle to the running transaction.
448 */
449 update_t_max_wait(transaction, ts);
450 handle->h_transaction = transaction;
451 handle->h_requested_credits = blocks;
452 handle->h_revoke_credits_requested = handle->h_revoke_credits;
453 handle->h_start_jiffies = jiffies;
454 atomic_inc(&transaction->t_updates);
455 atomic_inc(&transaction->t_handle_count);
456 jbd2_debug(4, "Handle %p given %d credits (total %d, free %lu)\n",
457 handle, blocks,
458 atomic_read(&transaction->t_outstanding_credits),
459 jbd2_log_space_left(journal));
460 read_unlock(&journal->j_state_lock);
461 current->journal_info = handle;
462
463 rwsem_acquire_read(&journal->j_trans_commit_map, 0, 0, _THIS_IP_);
464 jbd2_journal_free_transaction(new_transaction);
465 /*
466 * Ensure that no allocations done while the transaction is open are
467 * going to recurse back to the fs layer.
468 */
469 handle->saved_alloc_context = memalloc_nofs_save();
470 return 0;
471}
472
473/* Allocate a new handle. This should probably be in a slab... */
474static handle_t *new_handle(int nblocks)
475{
476 handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
477 if (!handle)
478 return NULL;
479 handle->h_total_credits = nblocks;
480 handle->h_ref = 1;
481
482 return handle;
483}
484
485handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
486 int revoke_records, gfp_t gfp_mask,
487 unsigned int type, unsigned int line_no)
488{
489 handle_t *handle = journal_current_handle();
490 int err;
491
492 if (!journal)
493 return ERR_PTR(-EROFS);
494
495 if (handle) {
496 J_ASSERT(handle->h_transaction->t_journal == journal);
497 handle->h_ref++;
498 return handle;
499 }
500
501 nblocks += DIV_ROUND_UP(revoke_records,
502 journal->j_revoke_records_per_block);
503 handle = new_handle(nblocks);
504 if (!handle)
505 return ERR_PTR(-ENOMEM);
506 if (rsv_blocks) {
507 handle_t *rsv_handle;
508
509 rsv_handle = new_handle(rsv_blocks);
510 if (!rsv_handle) {
511 jbd2_free_handle(handle);
512 return ERR_PTR(-ENOMEM);
513 }
514 rsv_handle->h_reserved = 1;
515 rsv_handle->h_journal = journal;
516 handle->h_rsv_handle = rsv_handle;
517 }
518 handle->h_revoke_credits = revoke_records;
519
520 err = start_this_handle(journal, handle, gfp_mask);
521 if (err < 0) {
522 if (handle->h_rsv_handle)
523 jbd2_free_handle(handle->h_rsv_handle);
524 jbd2_free_handle(handle);
525 return ERR_PTR(err);
526 }
527 handle->h_type = type;
528 handle->h_line_no = line_no;
529 trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
530 handle->h_transaction->t_tid, type,
531 line_no, nblocks);
532
533 return handle;
534}
535EXPORT_SYMBOL(jbd2__journal_start);
536
537
538/**
539 * jbd2_journal_start() - Obtain a new handle.
540 * @journal: Journal to start transaction on.
541 * @nblocks: number of block buffer we might modify
542 *
543 * We make sure that the transaction can guarantee at least nblocks of
544 * modified buffers in the log. We block until the log can guarantee
545 * that much space. Additionally, if rsv_blocks > 0, we also create another
546 * handle with rsv_blocks reserved blocks in the journal. This handle is
547 * stored in h_rsv_handle. It is not attached to any particular transaction
548 * and thus doesn't block transaction commit. If the caller uses this reserved
549 * handle, it has to set h_rsv_handle to NULL as otherwise jbd2_journal_stop()
550 * on the parent handle will dispose the reserved one. Reserved handle has to
551 * be converted to a normal handle using jbd2_journal_start_reserved() before
552 * it can be used.
553 *
554 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
555 * on failure.
556 */
557handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
558{
559 return jbd2__journal_start(journal, nblocks, 0, 0, GFP_NOFS, 0, 0);
560}
561EXPORT_SYMBOL(jbd2_journal_start);
562
563static void __jbd2_journal_unreserve_handle(handle_t *handle, transaction_t *t)
564{
565 journal_t *journal = handle->h_journal;
566
567 WARN_ON(!handle->h_reserved);
568 sub_reserved_credits(journal, handle->h_total_credits);
569 if (t)
570 atomic_sub(handle->h_total_credits, &t->t_outstanding_credits);
571}
572
573void jbd2_journal_free_reserved(handle_t *handle)
574{
575 journal_t *journal = handle->h_journal;
576
577 /* Get j_state_lock to pin running transaction if it exists */
578 read_lock(&journal->j_state_lock);
579 __jbd2_journal_unreserve_handle(handle, journal->j_running_transaction);
580 read_unlock(&journal->j_state_lock);
581 jbd2_free_handle(handle);
582}
583EXPORT_SYMBOL(jbd2_journal_free_reserved);
584
585/**
586 * jbd2_journal_start_reserved() - start reserved handle
587 * @handle: handle to start
588 * @type: for handle statistics
589 * @line_no: for handle statistics
590 *
591 * Start handle that has been previously reserved with jbd2_journal_reserve().
592 * This attaches @handle to the running transaction (or creates one if there's
593 * not transaction running). Unlike jbd2_journal_start() this function cannot
594 * block on journal commit, checkpointing, or similar stuff. It can block on
595 * memory allocation or frozen journal though.
596 *
597 * Return 0 on success, non-zero on error - handle is freed in that case.
598 */
599int jbd2_journal_start_reserved(handle_t *handle, unsigned int type,
600 unsigned int line_no)
601{
602 journal_t *journal = handle->h_journal;
603 int ret = -EIO;
604
605 if (WARN_ON(!handle->h_reserved)) {
606 /* Someone passed in normal handle? Just stop it. */
607 jbd2_journal_stop(handle);
608 return ret;
609 }
610 /*
611 * Usefulness of mixing of reserved and unreserved handles is
612 * questionable. So far nobody seems to need it so just error out.
613 */
614 if (WARN_ON(current->journal_info)) {
615 jbd2_journal_free_reserved(handle);
616 return ret;
617 }
618
619 handle->h_journal = NULL;
620 /*
621 * GFP_NOFS is here because callers are likely from writeback or
622 * similarly constrained call sites
623 */
624 ret = start_this_handle(journal, handle, GFP_NOFS);
625 if (ret < 0) {
626 handle->h_journal = journal;
627 jbd2_journal_free_reserved(handle);
628 return ret;
629 }
630 handle->h_type = type;
631 handle->h_line_no = line_no;
632 trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
633 handle->h_transaction->t_tid, type,
634 line_no, handle->h_total_credits);
635 return 0;
636}
637EXPORT_SYMBOL(jbd2_journal_start_reserved);
638
639/**
640 * jbd2_journal_extend() - extend buffer credits.
641 * @handle: handle to 'extend'
642 * @nblocks: nr blocks to try to extend by.
643 * @revoke_records: number of revoke records to try to extend by.
644 *
645 * Some transactions, such as large extends and truncates, can be done
646 * atomically all at once or in several stages. The operation requests
647 * a credit for a number of buffer modifications in advance, but can
648 * extend its credit if it needs more.
649 *
650 * jbd2_journal_extend tries to give the running handle more buffer credits.
651 * It does not guarantee that allocation - this is a best-effort only.
652 * The calling process MUST be able to deal cleanly with a failure to
653 * extend here.
654 *
655 * Return 0 on success, non-zero on failure.
656 *
657 * return code < 0 implies an error
658 * return code > 0 implies normal transaction-full status.
659 */
660int jbd2_journal_extend(handle_t *handle, int nblocks, int revoke_records)
661{
662 transaction_t *transaction = handle->h_transaction;
663 journal_t *journal;
664 int result;
665 int wanted;
666
667 if (is_handle_aborted(handle))
668 return -EROFS;
669 journal = transaction->t_journal;
670
671 result = 1;
672
673 read_lock(&journal->j_state_lock);
674
675 /* Don't extend a locked-down transaction! */
676 if (transaction->t_state != T_RUNNING) {
677 jbd2_debug(3, "denied handle %p %d blocks: "
678 "transaction not running\n", handle, nblocks);
679 goto error_out;
680 }
681
682 nblocks += DIV_ROUND_UP(
683 handle->h_revoke_credits_requested + revoke_records,
684 journal->j_revoke_records_per_block) -
685 DIV_ROUND_UP(
686 handle->h_revoke_credits_requested,
687 journal->j_revoke_records_per_block);
688 wanted = atomic_add_return(nblocks,
689 &transaction->t_outstanding_credits);
690
691 if (wanted > journal->j_max_transaction_buffers) {
692 jbd2_debug(3, "denied handle %p %d blocks: "
693 "transaction too large\n", handle, nblocks);
694 atomic_sub(nblocks, &transaction->t_outstanding_credits);
695 goto error_out;
696 }
697
698 trace_jbd2_handle_extend(journal->j_fs_dev->bd_dev,
699 transaction->t_tid,
700 handle->h_type, handle->h_line_no,
701 handle->h_total_credits,
702 nblocks);
703
704 handle->h_total_credits += nblocks;
705 handle->h_requested_credits += nblocks;
706 handle->h_revoke_credits += revoke_records;
707 handle->h_revoke_credits_requested += revoke_records;
708 result = 0;
709
710 jbd2_debug(3, "extended handle %p by %d\n", handle, nblocks);
711error_out:
712 read_unlock(&journal->j_state_lock);
713 return result;
714}
715
716static void stop_this_handle(handle_t *handle)
717{
718 transaction_t *transaction = handle->h_transaction;
719 journal_t *journal = transaction->t_journal;
720 int revokes;
721
722 J_ASSERT(journal_current_handle() == handle);
723 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
724 current->journal_info = NULL;
725 /*
726 * Subtract necessary revoke descriptor blocks from handle credits. We
727 * take care to account only for revoke descriptor blocks the
728 * transaction will really need as large sequences of transactions with
729 * small numbers of revokes are relatively common.
730 */
731 revokes = handle->h_revoke_credits_requested - handle->h_revoke_credits;
732 if (revokes) {
733 int t_revokes, revoke_descriptors;
734 int rr_per_blk = journal->j_revoke_records_per_block;
735
736 WARN_ON_ONCE(DIV_ROUND_UP(revokes, rr_per_blk)
737 > handle->h_total_credits);
738 t_revokes = atomic_add_return(revokes,
739 &transaction->t_outstanding_revokes);
740 revoke_descriptors =
741 DIV_ROUND_UP(t_revokes, rr_per_blk) -
742 DIV_ROUND_UP(t_revokes - revokes, rr_per_blk);
743 handle->h_total_credits -= revoke_descriptors;
744 }
745 atomic_sub(handle->h_total_credits,
746 &transaction->t_outstanding_credits);
747 if (handle->h_rsv_handle)
748 __jbd2_journal_unreserve_handle(handle->h_rsv_handle,
749 transaction);
750 if (atomic_dec_and_test(&transaction->t_updates))
751 wake_up(&journal->j_wait_updates);
752
753 rwsem_release(&journal->j_trans_commit_map, _THIS_IP_);
754 /*
755 * Scope of the GFP_NOFS context is over here and so we can restore the
756 * original alloc context.
757 */
758 memalloc_nofs_restore(handle->saved_alloc_context);
759}
760
761/**
762 * jbd2__journal_restart() - restart a handle .
763 * @handle: handle to restart
764 * @nblocks: nr credits requested
765 * @revoke_records: number of revoke record credits requested
766 * @gfp_mask: memory allocation flags (for start_this_handle)
767 *
768 * Restart a handle for a multi-transaction filesystem
769 * operation.
770 *
771 * If the jbd2_journal_extend() call above fails to grant new buffer credits
772 * to a running handle, a call to jbd2_journal_restart will commit the
773 * handle's transaction so far and reattach the handle to a new
774 * transaction capable of guaranteeing the requested number of
775 * credits. We preserve reserved handle if there's any attached to the
776 * passed in handle.
777 */
778int jbd2__journal_restart(handle_t *handle, int nblocks, int revoke_records,
779 gfp_t gfp_mask)
780{
781 transaction_t *transaction = handle->h_transaction;
782 journal_t *journal;
783 tid_t tid;
784 int need_to_start;
785 int ret;
786
787 /* If we've had an abort of any type, don't even think about
788 * actually doing the restart! */
789 if (is_handle_aborted(handle))
790 return 0;
791 journal = transaction->t_journal;
792 tid = transaction->t_tid;
793
794 /*
795 * First unlink the handle from its current transaction, and start the
796 * commit on that.
797 */
798 jbd2_debug(2, "restarting handle %p\n", handle);
799 stop_this_handle(handle);
800 handle->h_transaction = NULL;
801
802 /*
803 * TODO: If we use READ_ONCE / WRITE_ONCE for j_commit_request we can
804 * get rid of pointless j_state_lock traffic like this.
805 */
806 read_lock(&journal->j_state_lock);
807 need_to_start = !tid_geq(journal->j_commit_request, tid);
808 read_unlock(&journal->j_state_lock);
809 if (need_to_start)
810 jbd2_log_start_commit(journal, tid);
811 handle->h_total_credits = nblocks +
812 DIV_ROUND_UP(revoke_records,
813 journal->j_revoke_records_per_block);
814 handle->h_revoke_credits = revoke_records;
815 ret = start_this_handle(journal, handle, gfp_mask);
816 trace_jbd2_handle_restart(journal->j_fs_dev->bd_dev,
817 ret ? 0 : handle->h_transaction->t_tid,
818 handle->h_type, handle->h_line_no,
819 handle->h_total_credits);
820 return ret;
821}
822EXPORT_SYMBOL(jbd2__journal_restart);
823
824
825int jbd2_journal_restart(handle_t *handle, int nblocks)
826{
827 return jbd2__journal_restart(handle, nblocks, 0, GFP_NOFS);
828}
829EXPORT_SYMBOL(jbd2_journal_restart);
830
831/*
832 * Waits for any outstanding t_updates to finish.
833 * This is called with write j_state_lock held.
834 */
835void jbd2_journal_wait_updates(journal_t *journal)
836{
837 DEFINE_WAIT(wait);
838
839 while (1) {
840 /*
841 * Note that the running transaction can get freed under us if
842 * this transaction is getting committed in
843 * jbd2_journal_commit_transaction() ->
844 * jbd2_journal_free_transaction(). This can only happen when we
845 * release j_state_lock -> schedule() -> acquire j_state_lock.
846 * Hence we should everytime retrieve new j_running_transaction
847 * value (after j_state_lock release acquire cycle), else it may
848 * lead to use-after-free of old freed transaction.
849 */
850 transaction_t *transaction = journal->j_running_transaction;
851
852 if (!transaction)
853 break;
854
855 prepare_to_wait(&journal->j_wait_updates, &wait,
856 TASK_UNINTERRUPTIBLE);
857 if (!atomic_read(&transaction->t_updates)) {
858 finish_wait(&journal->j_wait_updates, &wait);
859 break;
860 }
861 write_unlock(&journal->j_state_lock);
862 schedule();
863 finish_wait(&journal->j_wait_updates, &wait);
864 write_lock(&journal->j_state_lock);
865 }
866}
867
868/**
869 * jbd2_journal_lock_updates () - establish a transaction barrier.
870 * @journal: Journal to establish a barrier on.
871 *
872 * This locks out any further updates from being started, and blocks
873 * until all existing updates have completed, returning only once the
874 * journal is in a quiescent state with no updates running.
875 *
876 * The journal lock should not be held on entry.
877 */
878void jbd2_journal_lock_updates(journal_t *journal)
879{
880 jbd2_might_wait_for_commit(journal);
881
882 write_lock(&journal->j_state_lock);
883 ++journal->j_barrier_count;
884
885 /* Wait until there are no reserved handles */
886 if (atomic_read(&journal->j_reserved_credits)) {
887 write_unlock(&journal->j_state_lock);
888 wait_event(journal->j_wait_reserved,
889 atomic_read(&journal->j_reserved_credits) == 0);
890 write_lock(&journal->j_state_lock);
891 }
892
893 /* Wait until there are no running t_updates */
894 jbd2_journal_wait_updates(journal);
895
896 write_unlock(&journal->j_state_lock);
897
898 /*
899 * We have now established a barrier against other normal updates, but
900 * we also need to barrier against other jbd2_journal_lock_updates() calls
901 * to make sure that we serialise special journal-locked operations
902 * too.
903 */
904 mutex_lock(&journal->j_barrier);
905}
906
907/**
908 * jbd2_journal_unlock_updates () - release barrier
909 * @journal: Journal to release the barrier on.
910 *
911 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
912 *
913 * Should be called without the journal lock held.
914 */
915void jbd2_journal_unlock_updates (journal_t *journal)
916{
917 J_ASSERT(journal->j_barrier_count != 0);
918
919 mutex_unlock(&journal->j_barrier);
920 write_lock(&journal->j_state_lock);
921 --journal->j_barrier_count;
922 write_unlock(&journal->j_state_lock);
923 wake_up_all(&journal->j_wait_transaction_locked);
924}
925
926static void warn_dirty_buffer(struct buffer_head *bh)
927{
928 printk(KERN_WARNING
929 "JBD2: Spotted dirty metadata buffer (dev = %pg, blocknr = %llu). "
930 "There's a risk of filesystem corruption in case of system "
931 "crash.\n",
932 bh->b_bdev, (unsigned long long)bh->b_blocknr);
933}
934
935/* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */
936static void jbd2_freeze_jh_data(struct journal_head *jh)
937{
938 struct page *page;
939 int offset;
940 char *source;
941 struct buffer_head *bh = jh2bh(jh);
942
943 J_EXPECT_JH(jh, buffer_uptodate(bh), "Possible IO failure.\n");
944 page = bh->b_page;
945 offset = offset_in_page(bh->b_data);
946 source = kmap_atomic(page);
947 /* Fire data frozen trigger just before we copy the data */
948 jbd2_buffer_frozen_trigger(jh, source + offset, jh->b_triggers);
949 memcpy(jh->b_frozen_data, source + offset, bh->b_size);
950 kunmap_atomic(source);
951
952 /*
953 * Now that the frozen data is saved off, we need to store any matching
954 * triggers.
955 */
956 jh->b_frozen_triggers = jh->b_triggers;
957}
958
959/*
960 * If the buffer is already part of the current transaction, then there
961 * is nothing we need to do. If it is already part of a prior
962 * transaction which we are still committing to disk, then we need to
963 * make sure that we do not overwrite the old copy: we do copy-out to
964 * preserve the copy going to disk. We also account the buffer against
965 * the handle's metadata buffer credits (unless the buffer is already
966 * part of the transaction, that is).
967 *
968 */
969static int
970do_get_write_access(handle_t *handle, struct journal_head *jh,
971 int force_copy)
972{
973 struct buffer_head *bh;
974 transaction_t *transaction = handle->h_transaction;
975 journal_t *journal;
976 int error;
977 char *frozen_buffer = NULL;
978 unsigned long start_lock, time_lock;
979
980 journal = transaction->t_journal;
981
982 jbd2_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
983
984 JBUFFER_TRACE(jh, "entry");
985repeat:
986 bh = jh2bh(jh);
987
988 /* @@@ Need to check for errors here at some point. */
989
990 start_lock = jiffies;
991 lock_buffer(bh);
992 spin_lock(&jh->b_state_lock);
993
994 /* If it takes too long to lock the buffer, trace it */
995 time_lock = jbd2_time_diff(start_lock, jiffies);
996 if (time_lock > HZ/10)
997 trace_jbd2_lock_buffer_stall(bh->b_bdev->bd_dev,
998 jiffies_to_msecs(time_lock));
999
1000 /* We now hold the buffer lock so it is safe to query the buffer
1001 * state. Is the buffer dirty?
1002 *
1003 * If so, there are two possibilities. The buffer may be
1004 * non-journaled, and undergoing a quite legitimate writeback.
1005 * Otherwise, it is journaled, and we don't expect dirty buffers
1006 * in that state (the buffers should be marked JBD_Dirty
1007 * instead.) So either the IO is being done under our own
1008 * control and this is a bug, or it's a third party IO such as
1009 * dump(8) (which may leave the buffer scheduled for read ---
1010 * ie. locked but not dirty) or tune2fs (which may actually have
1011 * the buffer dirtied, ugh.) */
1012
1013 if (buffer_dirty(bh)) {
1014 /*
1015 * First question: is this buffer already part of the current
1016 * transaction or the existing committing transaction?
1017 */
1018 if (jh->b_transaction) {
1019 J_ASSERT_JH(jh,
1020 jh->b_transaction == transaction ||
1021 jh->b_transaction ==
1022 journal->j_committing_transaction);
1023 if (jh->b_next_transaction)
1024 J_ASSERT_JH(jh, jh->b_next_transaction ==
1025 transaction);
1026 warn_dirty_buffer(bh);
1027 }
1028 /*
1029 * In any case we need to clean the dirty flag and we must
1030 * do it under the buffer lock to be sure we don't race
1031 * with running write-out.
1032 */
1033 JBUFFER_TRACE(jh, "Journalling dirty buffer");
1034 clear_buffer_dirty(bh);
1035 set_buffer_jbddirty(bh);
1036 }
1037
1038 unlock_buffer(bh);
1039
1040 error = -EROFS;
1041 if (is_handle_aborted(handle)) {
1042 spin_unlock(&jh->b_state_lock);
1043 goto out;
1044 }
1045 error = 0;
1046
1047 /*
1048 * The buffer is already part of this transaction if b_transaction or
1049 * b_next_transaction points to it
1050 */
1051 if (jh->b_transaction == transaction ||
1052 jh->b_next_transaction == transaction)
1053 goto done;
1054
1055 /*
1056 * this is the first time this transaction is touching this buffer,
1057 * reset the modified flag
1058 */
1059 jh->b_modified = 0;
1060
1061 /*
1062 * If the buffer is not journaled right now, we need to make sure it
1063 * doesn't get written to disk before the caller actually commits the
1064 * new data
1065 */
1066 if (!jh->b_transaction) {
1067 JBUFFER_TRACE(jh, "no transaction");
1068 J_ASSERT_JH(jh, !jh->b_next_transaction);
1069 JBUFFER_TRACE(jh, "file as BJ_Reserved");
1070 /*
1071 * Make sure all stores to jh (b_modified, b_frozen_data) are
1072 * visible before attaching it to the running transaction.
1073 * Paired with barrier in jbd2_write_access_granted()
1074 */
1075 smp_wmb();
1076 spin_lock(&journal->j_list_lock);
1077 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
1078 spin_unlock(&journal->j_list_lock);
1079 goto done;
1080 }
1081 /*
1082 * If there is already a copy-out version of this buffer, then we don't
1083 * need to make another one
1084 */
1085 if (jh->b_frozen_data) {
1086 JBUFFER_TRACE(jh, "has frozen data");
1087 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1088 goto attach_next;
1089 }
1090
1091 JBUFFER_TRACE(jh, "owned by older transaction");
1092 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1093 J_ASSERT_JH(jh, jh->b_transaction == journal->j_committing_transaction);
1094
1095 /*
1096 * There is one case we have to be very careful about. If the
1097 * committing transaction is currently writing this buffer out to disk
1098 * and has NOT made a copy-out, then we cannot modify the buffer
1099 * contents at all right now. The essence of copy-out is that it is
1100 * the extra copy, not the primary copy, which gets journaled. If the
1101 * primary copy is already going to disk then we cannot do copy-out
1102 * here.
1103 */
1104 if (buffer_shadow(bh)) {
1105 JBUFFER_TRACE(jh, "on shadow: sleep");
1106 spin_unlock(&jh->b_state_lock);
1107 wait_on_bit_io(&bh->b_state, BH_Shadow, TASK_UNINTERRUPTIBLE);
1108 goto repeat;
1109 }
1110
1111 /*
1112 * Only do the copy if the currently-owning transaction still needs it.
1113 * If buffer isn't on BJ_Metadata list, the committing transaction is
1114 * past that stage (here we use the fact that BH_Shadow is set under
1115 * bh_state lock together with refiling to BJ_Shadow list and at this
1116 * point we know the buffer doesn't have BH_Shadow set).
1117 *
1118 * Subtle point, though: if this is a get_undo_access, then we will be
1119 * relying on the frozen_data to contain the new value of the
1120 * committed_data record after the transaction, so we HAVE to force the
1121 * frozen_data copy in that case.
1122 */
1123 if (jh->b_jlist == BJ_Metadata || force_copy) {
1124 JBUFFER_TRACE(jh, "generate frozen data");
1125 if (!frozen_buffer) {
1126 JBUFFER_TRACE(jh, "allocate memory for buffer");
1127 spin_unlock(&jh->b_state_lock);
1128 frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
1129 GFP_NOFS | __GFP_NOFAIL);
1130 goto repeat;
1131 }
1132 jh->b_frozen_data = frozen_buffer;
1133 frozen_buffer = NULL;
1134 jbd2_freeze_jh_data(jh);
1135 }
1136attach_next:
1137 /*
1138 * Make sure all stores to jh (b_modified, b_frozen_data) are visible
1139 * before attaching it to the running transaction. Paired with barrier
1140 * in jbd2_write_access_granted()
1141 */
1142 smp_wmb();
1143 jh->b_next_transaction = transaction;
1144
1145done:
1146 spin_unlock(&jh->b_state_lock);
1147
1148 /*
1149 * If we are about to journal a buffer, then any revoke pending on it is
1150 * no longer valid
1151 */
1152 jbd2_journal_cancel_revoke(handle, jh);
1153
1154out:
1155 if (unlikely(frozen_buffer)) /* It's usually NULL */
1156 jbd2_free(frozen_buffer, bh->b_size);
1157
1158 JBUFFER_TRACE(jh, "exit");
1159 return error;
1160}
1161
1162/* Fast check whether buffer is already attached to the required transaction */
1163static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh,
1164 bool undo)
1165{
1166 struct journal_head *jh;
1167 bool ret = false;
1168
1169 /* Dirty buffers require special handling... */
1170 if (buffer_dirty(bh))
1171 return false;
1172
1173 /*
1174 * RCU protects us from dereferencing freed pages. So the checks we do
1175 * are guaranteed not to oops. However the jh slab object can get freed
1176 * & reallocated while we work with it. So we have to be careful. When
1177 * we see jh attached to the running transaction, we know it must stay
1178 * so until the transaction is committed. Thus jh won't be freed and
1179 * will be attached to the same bh while we run. However it can
1180 * happen jh gets freed, reallocated, and attached to the transaction
1181 * just after we get pointer to it from bh. So we have to be careful
1182 * and recheck jh still belongs to our bh before we return success.
1183 */
1184 rcu_read_lock();
1185 if (!buffer_jbd(bh))
1186 goto out;
1187 /* This should be bh2jh() but that doesn't work with inline functions */
1188 jh = READ_ONCE(bh->b_private);
1189 if (!jh)
1190 goto out;
1191 /* For undo access buffer must have data copied */
1192 if (undo && !jh->b_committed_data)
1193 goto out;
1194 if (READ_ONCE(jh->b_transaction) != handle->h_transaction &&
1195 READ_ONCE(jh->b_next_transaction) != handle->h_transaction)
1196 goto out;
1197 /*
1198 * There are two reasons for the barrier here:
1199 * 1) Make sure to fetch b_bh after we did previous checks so that we
1200 * detect when jh went through free, realloc, attach to transaction
1201 * while we were checking. Paired with implicit barrier in that path.
1202 * 2) So that access to bh done after jbd2_write_access_granted()
1203 * doesn't get reordered and see inconsistent state of concurrent
1204 * do_get_write_access().
1205 */
1206 smp_mb();
1207 if (unlikely(jh->b_bh != bh))
1208 goto out;
1209 ret = true;
1210out:
1211 rcu_read_unlock();
1212 return ret;
1213}
1214
1215/**
1216 * jbd2_journal_get_write_access() - notify intent to modify a buffer
1217 * for metadata (not data) update.
1218 * @handle: transaction to add buffer modifications to
1219 * @bh: bh to be used for metadata writes
1220 *
1221 * Returns: error code or 0 on success.
1222 *
1223 * In full data journalling mode the buffer may be of type BJ_AsyncData,
1224 * because we're ``write()ing`` a buffer which is also part of a shared mapping.
1225 */
1226
1227int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
1228{
1229 struct journal_head *jh;
1230 int rc;
1231
1232 if (is_handle_aborted(handle))
1233 return -EROFS;
1234
1235 if (jbd2_write_access_granted(handle, bh, false))
1236 return 0;
1237
1238 jh = jbd2_journal_add_journal_head(bh);
1239 /* We do not want to get caught playing with fields which the
1240 * log thread also manipulates. Make sure that the buffer
1241 * completes any outstanding IO before proceeding. */
1242 rc = do_get_write_access(handle, jh, 0);
1243 jbd2_journal_put_journal_head(jh);
1244 return rc;
1245}
1246
1247
1248/*
1249 * When the user wants to journal a newly created buffer_head
1250 * (ie. getblk() returned a new buffer and we are going to populate it
1251 * manually rather than reading off disk), then we need to keep the
1252 * buffer_head locked until it has been completely filled with new
1253 * data. In this case, we should be able to make the assertion that
1254 * the bh is not already part of an existing transaction.
1255 *
1256 * The buffer should already be locked by the caller by this point.
1257 * There is no lock ranking violation: it was a newly created,
1258 * unlocked buffer beforehand. */
1259
1260/**
1261 * jbd2_journal_get_create_access () - notify intent to use newly created bh
1262 * @handle: transaction to new buffer to
1263 * @bh: new buffer.
1264 *
1265 * Call this if you create a new bh.
1266 */
1267int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
1268{
1269 transaction_t *transaction = handle->h_transaction;
1270 journal_t *journal;
1271 struct journal_head *jh = jbd2_journal_add_journal_head(bh);
1272 int err;
1273
1274 jbd2_debug(5, "journal_head %p\n", jh);
1275 err = -EROFS;
1276 if (is_handle_aborted(handle))
1277 goto out;
1278 journal = transaction->t_journal;
1279 err = 0;
1280
1281 JBUFFER_TRACE(jh, "entry");
1282 /*
1283 * The buffer may already belong to this transaction due to pre-zeroing
1284 * in the filesystem's new_block code. It may also be on the previous,
1285 * committing transaction's lists, but it HAS to be in Forget state in
1286 * that case: the transaction must have deleted the buffer for it to be
1287 * reused here.
1288 */
1289 spin_lock(&jh->b_state_lock);
1290 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
1291 jh->b_transaction == NULL ||
1292 (jh->b_transaction == journal->j_committing_transaction &&
1293 jh->b_jlist == BJ_Forget)));
1294
1295 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1296 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
1297
1298 if (jh->b_transaction == NULL) {
1299 /*
1300 * Previous jbd2_journal_forget() could have left the buffer
1301 * with jbddirty bit set because it was being committed. When
1302 * the commit finished, we've filed the buffer for
1303 * checkpointing and marked it dirty. Now we are reallocating
1304 * the buffer so the transaction freeing it must have
1305 * committed and so it's safe to clear the dirty bit.
1306 */
1307 clear_buffer_dirty(jh2bh(jh));
1308 /* first access by this transaction */
1309 jh->b_modified = 0;
1310
1311 JBUFFER_TRACE(jh, "file as BJ_Reserved");
1312 spin_lock(&journal->j_list_lock);
1313 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
1314 spin_unlock(&journal->j_list_lock);
1315 } else if (jh->b_transaction == journal->j_committing_transaction) {
1316 /* first access by this transaction */
1317 jh->b_modified = 0;
1318
1319 JBUFFER_TRACE(jh, "set next transaction");
1320 spin_lock(&journal->j_list_lock);
1321 jh->b_next_transaction = transaction;
1322 spin_unlock(&journal->j_list_lock);
1323 }
1324 spin_unlock(&jh->b_state_lock);
1325
1326 /*
1327 * akpm: I added this. ext3_alloc_branch can pick up new indirect
1328 * blocks which contain freed but then revoked metadata. We need
1329 * to cancel the revoke in case we end up freeing it yet again
1330 * and the reallocating as data - this would cause a second revoke,
1331 * which hits an assertion error.
1332 */
1333 JBUFFER_TRACE(jh, "cancelling revoke");
1334 jbd2_journal_cancel_revoke(handle, jh);
1335out:
1336 jbd2_journal_put_journal_head(jh);
1337 return err;
1338}
1339
1340/**
1341 * jbd2_journal_get_undo_access() - Notify intent to modify metadata with
1342 * non-rewindable consequences
1343 * @handle: transaction
1344 * @bh: buffer to undo
1345 *
1346 * Sometimes there is a need to distinguish between metadata which has
1347 * been committed to disk and that which has not. The ext3fs code uses
1348 * this for freeing and allocating space, we have to make sure that we
1349 * do not reuse freed space until the deallocation has been committed,
1350 * since if we overwrote that space we would make the delete
1351 * un-rewindable in case of a crash.
1352 *
1353 * To deal with that, jbd2_journal_get_undo_access requests write access to a
1354 * buffer for parts of non-rewindable operations such as delete
1355 * operations on the bitmaps. The journaling code must keep a copy of
1356 * the buffer's contents prior to the undo_access call until such time
1357 * as we know that the buffer has definitely been committed to disk.
1358 *
1359 * We never need to know which transaction the committed data is part
1360 * of, buffers touched here are guaranteed to be dirtied later and so
1361 * will be committed to a new transaction in due course, at which point
1362 * we can discard the old committed data pointer.
1363 *
1364 * Returns error number or 0 on success.
1365 */
1366int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
1367{
1368 int err;
1369 struct journal_head *jh;
1370 char *committed_data = NULL;
1371
1372 if (is_handle_aborted(handle))
1373 return -EROFS;
1374
1375 if (jbd2_write_access_granted(handle, bh, true))
1376 return 0;
1377
1378 jh = jbd2_journal_add_journal_head(bh);
1379 JBUFFER_TRACE(jh, "entry");
1380
1381 /*
1382 * Do this first --- it can drop the journal lock, so we want to
1383 * make sure that obtaining the committed_data is done
1384 * atomically wrt. completion of any outstanding commits.
1385 */
1386 err = do_get_write_access(handle, jh, 1);
1387 if (err)
1388 goto out;
1389
1390repeat:
1391 if (!jh->b_committed_data)
1392 committed_data = jbd2_alloc(jh2bh(jh)->b_size,
1393 GFP_NOFS|__GFP_NOFAIL);
1394
1395 spin_lock(&jh->b_state_lock);
1396 if (!jh->b_committed_data) {
1397 /* Copy out the current buffer contents into the
1398 * preserved, committed copy. */
1399 JBUFFER_TRACE(jh, "generate b_committed data");
1400 if (!committed_data) {
1401 spin_unlock(&jh->b_state_lock);
1402 goto repeat;
1403 }
1404
1405 jh->b_committed_data = committed_data;
1406 committed_data = NULL;
1407 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
1408 }
1409 spin_unlock(&jh->b_state_lock);
1410out:
1411 jbd2_journal_put_journal_head(jh);
1412 if (unlikely(committed_data))
1413 jbd2_free(committed_data, bh->b_size);
1414 return err;
1415}
1416
1417/**
1418 * jbd2_journal_set_triggers() - Add triggers for commit writeout
1419 * @bh: buffer to trigger on
1420 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1421 *
1422 * Set any triggers on this journal_head. This is always safe, because
1423 * triggers for a committing buffer will be saved off, and triggers for
1424 * a running transaction will match the buffer in that transaction.
1425 *
1426 * Call with NULL to clear the triggers.
1427 */
1428void jbd2_journal_set_triggers(struct buffer_head *bh,
1429 struct jbd2_buffer_trigger_type *type)
1430{
1431 struct journal_head *jh = jbd2_journal_grab_journal_head(bh);
1432
1433 if (WARN_ON_ONCE(!jh))
1434 return;
1435 jh->b_triggers = type;
1436 jbd2_journal_put_journal_head(jh);
1437}
1438
1439void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
1440 struct jbd2_buffer_trigger_type *triggers)
1441{
1442 struct buffer_head *bh = jh2bh(jh);
1443
1444 if (!triggers || !triggers->t_frozen)
1445 return;
1446
1447 triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
1448}
1449
1450void jbd2_buffer_abort_trigger(struct journal_head *jh,
1451 struct jbd2_buffer_trigger_type *triggers)
1452{
1453 if (!triggers || !triggers->t_abort)
1454 return;
1455
1456 triggers->t_abort(triggers, jh2bh(jh));
1457}
1458
1459/**
1460 * jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata
1461 * @handle: transaction to add buffer to.
1462 * @bh: buffer to mark
1463 *
1464 * mark dirty metadata which needs to be journaled as part of the current
1465 * transaction.
1466 *
1467 * The buffer must have previously had jbd2_journal_get_write_access()
1468 * called so that it has a valid journal_head attached to the buffer
1469 * head.
1470 *
1471 * The buffer is placed on the transaction's metadata list and is marked
1472 * as belonging to the transaction.
1473 *
1474 * Returns error number or 0 on success.
1475 *
1476 * Special care needs to be taken if the buffer already belongs to the
1477 * current committing transaction (in which case we should have frozen
1478 * data present for that commit). In that case, we don't relink the
1479 * buffer: that only gets done when the old transaction finally
1480 * completes its commit.
1481 */
1482int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1483{
1484 transaction_t *transaction = handle->h_transaction;
1485 journal_t *journal;
1486 struct journal_head *jh;
1487 int ret = 0;
1488
1489 if (!buffer_jbd(bh))
1490 return -EUCLEAN;
1491
1492 /*
1493 * We don't grab jh reference here since the buffer must be part
1494 * of the running transaction.
1495 */
1496 jh = bh2jh(bh);
1497 jbd2_debug(5, "journal_head %p\n", jh);
1498 JBUFFER_TRACE(jh, "entry");
1499
1500 /*
1501 * This and the following assertions are unreliable since we may see jh
1502 * in inconsistent state unless we grab bh_state lock. But this is
1503 * crucial to catch bugs so let's do a reliable check until the
1504 * lockless handling is fully proven.
1505 */
1506 if (data_race(jh->b_transaction != transaction &&
1507 jh->b_next_transaction != transaction)) {
1508 spin_lock(&jh->b_state_lock);
1509 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1510 jh->b_next_transaction == transaction);
1511 spin_unlock(&jh->b_state_lock);
1512 }
1513 if (jh->b_modified == 1) {
1514 /* If it's in our transaction it must be in BJ_Metadata list. */
1515 if (data_race(jh->b_transaction == transaction &&
1516 jh->b_jlist != BJ_Metadata)) {
1517 spin_lock(&jh->b_state_lock);
1518 if (jh->b_transaction == transaction &&
1519 jh->b_jlist != BJ_Metadata)
1520 pr_err("JBD2: assertion failure: h_type=%u "
1521 "h_line_no=%u block_no=%llu jlist=%u\n",
1522 handle->h_type, handle->h_line_no,
1523 (unsigned long long) bh->b_blocknr,
1524 jh->b_jlist);
1525 J_ASSERT_JH(jh, jh->b_transaction != transaction ||
1526 jh->b_jlist == BJ_Metadata);
1527 spin_unlock(&jh->b_state_lock);
1528 }
1529 goto out;
1530 }
1531
1532 journal = transaction->t_journal;
1533 spin_lock(&jh->b_state_lock);
1534
1535 if (is_handle_aborted(handle)) {
1536 /*
1537 * Check journal aborting with @jh->b_state_lock locked,
1538 * since 'jh->b_transaction' could be replaced with
1539 * 'jh->b_next_transaction' during old transaction
1540 * committing if journal aborted, which may fail
1541 * assertion on 'jh->b_frozen_data == NULL'.
1542 */
1543 ret = -EROFS;
1544 goto out_unlock_bh;
1545 }
1546
1547 if (jh->b_modified == 0) {
1548 /*
1549 * This buffer's got modified and becoming part
1550 * of the transaction. This needs to be done
1551 * once a transaction -bzzz
1552 */
1553 if (WARN_ON_ONCE(jbd2_handle_buffer_credits(handle) <= 0)) {
1554 ret = -ENOSPC;
1555 goto out_unlock_bh;
1556 }
1557 jh->b_modified = 1;
1558 handle->h_total_credits--;
1559 }
1560
1561 /*
1562 * fastpath, to avoid expensive locking. If this buffer is already
1563 * on the running transaction's metadata list there is nothing to do.
1564 * Nobody can take it off again because there is a handle open.
1565 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1566 * result in this test being false, so we go in and take the locks.
1567 */
1568 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1569 JBUFFER_TRACE(jh, "fastpath");
1570 if (unlikely(jh->b_transaction !=
1571 journal->j_running_transaction)) {
1572 printk(KERN_ERR "JBD2: %s: "
1573 "jh->b_transaction (%llu, %p, %u) != "
1574 "journal->j_running_transaction (%p, %u)\n",
1575 journal->j_devname,
1576 (unsigned long long) bh->b_blocknr,
1577 jh->b_transaction,
1578 jh->b_transaction ? jh->b_transaction->t_tid : 0,
1579 journal->j_running_transaction,
1580 journal->j_running_transaction ?
1581 journal->j_running_transaction->t_tid : 0);
1582 ret = -EINVAL;
1583 }
1584 goto out_unlock_bh;
1585 }
1586
1587 set_buffer_jbddirty(bh);
1588
1589 /*
1590 * Metadata already on the current transaction list doesn't
1591 * need to be filed. Metadata on another transaction's list must
1592 * be committing, and will be refiled once the commit completes:
1593 * leave it alone for now.
1594 */
1595 if (jh->b_transaction != transaction) {
1596 JBUFFER_TRACE(jh, "already on other transaction");
1597 if (unlikely(((jh->b_transaction !=
1598 journal->j_committing_transaction)) ||
1599 (jh->b_next_transaction != transaction))) {
1600 printk(KERN_ERR "jbd2_journal_dirty_metadata: %s: "
1601 "bad jh for block %llu: "
1602 "transaction (%p, %u), "
1603 "jh->b_transaction (%p, %u), "
1604 "jh->b_next_transaction (%p, %u), jlist %u\n",
1605 journal->j_devname,
1606 (unsigned long long) bh->b_blocknr,
1607 transaction, transaction->t_tid,
1608 jh->b_transaction,
1609 jh->b_transaction ?
1610 jh->b_transaction->t_tid : 0,
1611 jh->b_next_transaction,
1612 jh->b_next_transaction ?
1613 jh->b_next_transaction->t_tid : 0,
1614 jh->b_jlist);
1615 WARN_ON(1);
1616 ret = -EINVAL;
1617 }
1618 /* And this case is illegal: we can't reuse another
1619 * transaction's data buffer, ever. */
1620 goto out_unlock_bh;
1621 }
1622
1623 /* That test should have eliminated the following case: */
1624 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1625
1626 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1627 spin_lock(&journal->j_list_lock);
1628 __jbd2_journal_file_buffer(jh, transaction, BJ_Metadata);
1629 spin_unlock(&journal->j_list_lock);
1630out_unlock_bh:
1631 spin_unlock(&jh->b_state_lock);
1632out:
1633 JBUFFER_TRACE(jh, "exit");
1634 return ret;
1635}
1636
1637/**
1638 * jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1639 * @handle: transaction handle
1640 * @bh: bh to 'forget'
1641 *
1642 * We can only do the bforget if there are no commits pending against the
1643 * buffer. If the buffer is dirty in the current running transaction we
1644 * can safely unlink it.
1645 *
1646 * bh may not be a journalled buffer at all - it may be a non-JBD
1647 * buffer which came off the hashtable. Check for this.
1648 *
1649 * Decrements bh->b_count by one.
1650 *
1651 * Allow this call even if the handle has aborted --- it may be part of
1652 * the caller's cleanup after an abort.
1653 */
1654int jbd2_journal_forget(handle_t *handle, struct buffer_head *bh)
1655{
1656 transaction_t *transaction = handle->h_transaction;
1657 journal_t *journal;
1658 struct journal_head *jh;
1659 int drop_reserve = 0;
1660 int err = 0;
1661 int was_modified = 0;
1662
1663 if (is_handle_aborted(handle))
1664 return -EROFS;
1665 journal = transaction->t_journal;
1666
1667 BUFFER_TRACE(bh, "entry");
1668
1669 jh = jbd2_journal_grab_journal_head(bh);
1670 if (!jh) {
1671 __bforget(bh);
1672 return 0;
1673 }
1674
1675 spin_lock(&jh->b_state_lock);
1676
1677 /* Critical error: attempting to delete a bitmap buffer, maybe?
1678 * Don't do any jbd operations, and return an error. */
1679 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1680 "inconsistent data on disk")) {
1681 err = -EIO;
1682 goto drop;
1683 }
1684
1685 /* keep track of whether or not this transaction modified us */
1686 was_modified = jh->b_modified;
1687
1688 /*
1689 * The buffer's going from the transaction, we must drop
1690 * all references -bzzz
1691 */
1692 jh->b_modified = 0;
1693
1694 if (jh->b_transaction == transaction) {
1695 J_ASSERT_JH(jh, !jh->b_frozen_data);
1696
1697 /* If we are forgetting a buffer which is already part
1698 * of this transaction, then we can just drop it from
1699 * the transaction immediately. */
1700 clear_buffer_dirty(bh);
1701 clear_buffer_jbddirty(bh);
1702
1703 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1704
1705 /*
1706 * we only want to drop a reference if this transaction
1707 * modified the buffer
1708 */
1709 if (was_modified)
1710 drop_reserve = 1;
1711
1712 /*
1713 * We are no longer going to journal this buffer.
1714 * However, the commit of this transaction is still
1715 * important to the buffer: the delete that we are now
1716 * processing might obsolete an old log entry, so by
1717 * committing, we can satisfy the buffer's checkpoint.
1718 *
1719 * So, if we have a checkpoint on the buffer, we should
1720 * now refile the buffer on our BJ_Forget list so that
1721 * we know to remove the checkpoint after we commit.
1722 */
1723
1724 spin_lock(&journal->j_list_lock);
1725 if (jh->b_cp_transaction) {
1726 __jbd2_journal_temp_unlink_buffer(jh);
1727 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1728 } else {
1729 __jbd2_journal_unfile_buffer(jh);
1730 jbd2_journal_put_journal_head(jh);
1731 }
1732 spin_unlock(&journal->j_list_lock);
1733 } else if (jh->b_transaction) {
1734 J_ASSERT_JH(jh, (jh->b_transaction ==
1735 journal->j_committing_transaction));
1736 /* However, if the buffer is still owned by a prior
1737 * (committing) transaction, we can't drop it yet... */
1738 JBUFFER_TRACE(jh, "belongs to older transaction");
1739 /* ... but we CAN drop it from the new transaction through
1740 * marking the buffer as freed and set j_next_transaction to
1741 * the new transaction, so that not only the commit code
1742 * knows it should clear dirty bits when it is done with the
1743 * buffer, but also the buffer can be checkpointed only
1744 * after the new transaction commits. */
1745
1746 set_buffer_freed(bh);
1747
1748 if (!jh->b_next_transaction) {
1749 spin_lock(&journal->j_list_lock);
1750 jh->b_next_transaction = transaction;
1751 spin_unlock(&journal->j_list_lock);
1752 } else {
1753 J_ASSERT(jh->b_next_transaction == transaction);
1754
1755 /*
1756 * only drop a reference if this transaction modified
1757 * the buffer
1758 */
1759 if (was_modified)
1760 drop_reserve = 1;
1761 }
1762 } else {
1763 /*
1764 * Finally, if the buffer is not belongs to any
1765 * transaction, we can just drop it now if it has no
1766 * checkpoint.
1767 */
1768 spin_lock(&journal->j_list_lock);
1769 if (!jh->b_cp_transaction) {
1770 JBUFFER_TRACE(jh, "belongs to none transaction");
1771 spin_unlock(&journal->j_list_lock);
1772 goto drop;
1773 }
1774
1775 /*
1776 * Otherwise, if the buffer has been written to disk,
1777 * it is safe to remove the checkpoint and drop it.
1778 */
1779 if (!buffer_dirty(bh)) {
1780 __jbd2_journal_remove_checkpoint(jh);
1781 spin_unlock(&journal->j_list_lock);
1782 goto drop;
1783 }
1784
1785 /*
1786 * The buffer is still not written to disk, we should
1787 * attach this buffer to current transaction so that the
1788 * buffer can be checkpointed only after the current
1789 * transaction commits.
1790 */
1791 clear_buffer_dirty(bh);
1792 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1793 spin_unlock(&journal->j_list_lock);
1794 }
1795drop:
1796 __brelse(bh);
1797 spin_unlock(&jh->b_state_lock);
1798 jbd2_journal_put_journal_head(jh);
1799 if (drop_reserve) {
1800 /* no need to reserve log space for this block -bzzz */
1801 handle->h_total_credits++;
1802 }
1803 return err;
1804}
1805
1806/**
1807 * jbd2_journal_stop() - complete a transaction
1808 * @handle: transaction to complete.
1809 *
1810 * All done for a particular handle.
1811 *
1812 * There is not much action needed here. We just return any remaining
1813 * buffer credits to the transaction and remove the handle. The only
1814 * complication is that we need to start a commit operation if the
1815 * filesystem is marked for synchronous update.
1816 *
1817 * jbd2_journal_stop itself will not usually return an error, but it may
1818 * do so in unusual circumstances. In particular, expect it to
1819 * return -EIO if a jbd2_journal_abort has been executed since the
1820 * transaction began.
1821 */
1822int jbd2_journal_stop(handle_t *handle)
1823{
1824 transaction_t *transaction = handle->h_transaction;
1825 journal_t *journal;
1826 int err = 0, wait_for_commit = 0;
1827 tid_t tid;
1828 pid_t pid;
1829
1830 if (--handle->h_ref > 0) {
1831 jbd2_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1832 handle->h_ref);
1833 if (is_handle_aborted(handle))
1834 return -EIO;
1835 return 0;
1836 }
1837 if (!transaction) {
1838 /*
1839 * Handle is already detached from the transaction so there is
1840 * nothing to do other than free the handle.
1841 */
1842 memalloc_nofs_restore(handle->saved_alloc_context);
1843 goto free_and_exit;
1844 }
1845 journal = transaction->t_journal;
1846 tid = transaction->t_tid;
1847
1848 if (is_handle_aborted(handle))
1849 err = -EIO;
1850
1851 jbd2_debug(4, "Handle %p going down\n", handle);
1852 trace_jbd2_handle_stats(journal->j_fs_dev->bd_dev,
1853 tid, handle->h_type, handle->h_line_no,
1854 jiffies - handle->h_start_jiffies,
1855 handle->h_sync, handle->h_requested_credits,
1856 (handle->h_requested_credits -
1857 handle->h_total_credits));
1858
1859 /*
1860 * Implement synchronous transaction batching. If the handle
1861 * was synchronous, don't force a commit immediately. Let's
1862 * yield and let another thread piggyback onto this
1863 * transaction. Keep doing that while new threads continue to
1864 * arrive. It doesn't cost much - we're about to run a commit
1865 * and sleep on IO anyway. Speeds up many-threaded, many-dir
1866 * operations by 30x or more...
1867 *
1868 * We try and optimize the sleep time against what the
1869 * underlying disk can do, instead of having a static sleep
1870 * time. This is useful for the case where our storage is so
1871 * fast that it is more optimal to go ahead and force a flush
1872 * and wait for the transaction to be committed than it is to
1873 * wait for an arbitrary amount of time for new writers to
1874 * join the transaction. We achieve this by measuring how
1875 * long it takes to commit a transaction, and compare it with
1876 * how long this transaction has been running, and if run time
1877 * < commit time then we sleep for the delta and commit. This
1878 * greatly helps super fast disks that would see slowdowns as
1879 * more threads started doing fsyncs.
1880 *
1881 * But don't do this if this process was the most recent one
1882 * to perform a synchronous write. We do this to detect the
1883 * case where a single process is doing a stream of sync
1884 * writes. No point in waiting for joiners in that case.
1885 *
1886 * Setting max_batch_time to 0 disables this completely.
1887 */
1888 pid = current->pid;
1889 if (handle->h_sync && journal->j_last_sync_writer != pid &&
1890 journal->j_max_batch_time) {
1891 u64 commit_time, trans_time;
1892
1893 journal->j_last_sync_writer = pid;
1894
1895 read_lock(&journal->j_state_lock);
1896 commit_time = journal->j_average_commit_time;
1897 read_unlock(&journal->j_state_lock);
1898
1899 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1900 transaction->t_start_time));
1901
1902 commit_time = max_t(u64, commit_time,
1903 1000*journal->j_min_batch_time);
1904 commit_time = min_t(u64, commit_time,
1905 1000*journal->j_max_batch_time);
1906
1907 if (trans_time < commit_time) {
1908 ktime_t expires = ktime_add_ns(ktime_get(),
1909 commit_time);
1910 set_current_state(TASK_UNINTERRUPTIBLE);
1911 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1912 }
1913 }
1914
1915 if (handle->h_sync)
1916 transaction->t_synchronous_commit = 1;
1917
1918 /*
1919 * If the handle is marked SYNC, we need to set another commit
1920 * going! We also want to force a commit if the transaction is too
1921 * old now.
1922 */
1923 if (handle->h_sync ||
1924 time_after_eq(jiffies, transaction->t_expires)) {
1925 /* Do this even for aborted journals: an abort still
1926 * completes the commit thread, it just doesn't write
1927 * anything to disk. */
1928
1929 jbd2_debug(2, "transaction too old, requesting commit for "
1930 "handle %p\n", handle);
1931 /* This is non-blocking */
1932 jbd2_log_start_commit(journal, tid);
1933
1934 /*
1935 * Special case: JBD2_SYNC synchronous updates require us
1936 * to wait for the commit to complete.
1937 */
1938 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1939 wait_for_commit = 1;
1940 }
1941
1942 /*
1943 * Once stop_this_handle() drops t_updates, the transaction could start
1944 * committing on us and eventually disappear. So we must not
1945 * dereference transaction pointer again after calling
1946 * stop_this_handle().
1947 */
1948 stop_this_handle(handle);
1949
1950 if (wait_for_commit)
1951 err = jbd2_log_wait_commit(journal, tid);
1952
1953free_and_exit:
1954 if (handle->h_rsv_handle)
1955 jbd2_free_handle(handle->h_rsv_handle);
1956 jbd2_free_handle(handle);
1957 return err;
1958}
1959
1960/*
1961 *
1962 * List management code snippets: various functions for manipulating the
1963 * transaction buffer lists.
1964 *
1965 */
1966
1967/*
1968 * Append a buffer to a transaction list, given the transaction's list head
1969 * pointer.
1970 *
1971 * j_list_lock is held.
1972 *
1973 * jh->b_state_lock is held.
1974 */
1975
1976static inline void
1977__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1978{
1979 if (!*list) {
1980 jh->b_tnext = jh->b_tprev = jh;
1981 *list = jh;
1982 } else {
1983 /* Insert at the tail of the list to preserve order */
1984 struct journal_head *first = *list, *last = first->b_tprev;
1985 jh->b_tprev = last;
1986 jh->b_tnext = first;
1987 last->b_tnext = first->b_tprev = jh;
1988 }
1989}
1990
1991/*
1992 * Remove a buffer from a transaction list, given the transaction's list
1993 * head pointer.
1994 *
1995 * Called with j_list_lock held, and the journal may not be locked.
1996 *
1997 * jh->b_state_lock is held.
1998 */
1999
2000static inline void
2001__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
2002{
2003 if (*list == jh) {
2004 *list = jh->b_tnext;
2005 if (*list == jh)
2006 *list = NULL;
2007 }
2008 jh->b_tprev->b_tnext = jh->b_tnext;
2009 jh->b_tnext->b_tprev = jh->b_tprev;
2010}
2011
2012/*
2013 * Remove a buffer from the appropriate transaction list.
2014 *
2015 * Note that this function can *change* the value of
2016 * bh->b_transaction->t_buffers, t_forget, t_shadow_list, t_log_list or
2017 * t_reserved_list. If the caller is holding onto a copy of one of these
2018 * pointers, it could go bad. Generally the caller needs to re-read the
2019 * pointer from the transaction_t.
2020 *
2021 * Called under j_list_lock.
2022 */
2023static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
2024{
2025 struct journal_head **list = NULL;
2026 transaction_t *transaction;
2027 struct buffer_head *bh = jh2bh(jh);
2028
2029 lockdep_assert_held(&jh->b_state_lock);
2030 transaction = jh->b_transaction;
2031 if (transaction)
2032 assert_spin_locked(&transaction->t_journal->j_list_lock);
2033
2034 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2035 if (jh->b_jlist != BJ_None)
2036 J_ASSERT_JH(jh, transaction != NULL);
2037
2038 switch (jh->b_jlist) {
2039 case BJ_None:
2040 return;
2041 case BJ_Metadata:
2042 transaction->t_nr_buffers--;
2043 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
2044 list = &transaction->t_buffers;
2045 break;
2046 case BJ_Forget:
2047 list = &transaction->t_forget;
2048 break;
2049 case BJ_Shadow:
2050 list = &transaction->t_shadow_list;
2051 break;
2052 case BJ_Reserved:
2053 list = &transaction->t_reserved_list;
2054 break;
2055 }
2056
2057 __blist_del_buffer(list, jh);
2058 jh->b_jlist = BJ_None;
2059 if (transaction && is_journal_aborted(transaction->t_journal))
2060 clear_buffer_jbddirty(bh);
2061 else if (test_clear_buffer_jbddirty(bh))
2062 mark_buffer_dirty(bh); /* Expose it to the VM */
2063}
2064
2065/*
2066 * Remove buffer from all transactions. The caller is responsible for dropping
2067 * the jh reference that belonged to the transaction.
2068 *
2069 * Called with bh_state lock and j_list_lock
2070 */
2071static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
2072{
2073 J_ASSERT_JH(jh, jh->b_transaction != NULL);
2074 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
2075
2076 __jbd2_journal_temp_unlink_buffer(jh);
2077 jh->b_transaction = NULL;
2078}
2079
2080void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
2081{
2082 struct buffer_head *bh = jh2bh(jh);
2083
2084 /* Get reference so that buffer cannot be freed before we unlock it */
2085 get_bh(bh);
2086 spin_lock(&jh->b_state_lock);
2087 spin_lock(&journal->j_list_lock);
2088 __jbd2_journal_unfile_buffer(jh);
2089 spin_unlock(&journal->j_list_lock);
2090 spin_unlock(&jh->b_state_lock);
2091 jbd2_journal_put_journal_head(jh);
2092 __brelse(bh);
2093}
2094
2095/*
2096 * Called from jbd2_journal_try_to_free_buffers().
2097 *
2098 * Called under jh->b_state_lock
2099 */
2100static void
2101__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
2102{
2103 struct journal_head *jh;
2104
2105 jh = bh2jh(bh);
2106
2107 if (buffer_locked(bh) || buffer_dirty(bh))
2108 goto out;
2109
2110 if (jh->b_next_transaction != NULL || jh->b_transaction != NULL)
2111 goto out;
2112
2113 spin_lock(&journal->j_list_lock);
2114 if (jh->b_cp_transaction != NULL) {
2115 /* written-back checkpointed metadata buffer */
2116 JBUFFER_TRACE(jh, "remove from checkpoint list");
2117 __jbd2_journal_remove_checkpoint(jh);
2118 }
2119 spin_unlock(&journal->j_list_lock);
2120out:
2121 return;
2122}
2123
2124/**
2125 * jbd2_journal_try_to_free_buffers() - try to free page buffers.
2126 * @journal: journal for operation
2127 * @folio: Folio to detach data from.
2128 *
2129 * For all the buffers on this page,
2130 * if they are fully written out ordered data, move them onto BUF_CLEAN
2131 * so try_to_free_buffers() can reap them.
2132 *
2133 * This function returns non-zero if we wish try_to_free_buffers()
2134 * to be called. We do this if the page is releasable by try_to_free_buffers().
2135 * We also do it if the page has locked or dirty buffers and the caller wants
2136 * us to perform sync or async writeout.
2137 *
2138 * This complicates JBD locking somewhat. We aren't protected by the
2139 * BKL here. We wish to remove the buffer from its committing or
2140 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
2141 *
2142 * This may *change* the value of transaction_t->t_datalist, so anyone
2143 * who looks at t_datalist needs to lock against this function.
2144 *
2145 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
2146 * buffer. So we need to lock against that. jbd2_journal_dirty_data()
2147 * will come out of the lock with the buffer dirty, which makes it
2148 * ineligible for release here.
2149 *
2150 * Who else is affected by this? hmm... Really the only contender
2151 * is do_get_write_access() - it could be looking at the buffer while
2152 * journal_try_to_free_buffer() is changing its state. But that
2153 * cannot happen because we never reallocate freed data as metadata
2154 * while the data is part of a transaction. Yes?
2155 *
2156 * Return false on failure, true on success
2157 */
2158bool jbd2_journal_try_to_free_buffers(journal_t *journal, struct folio *folio)
2159{
2160 struct buffer_head *head;
2161 struct buffer_head *bh;
2162 bool ret = false;
2163
2164 J_ASSERT(folio_test_locked(folio));
2165
2166 head = folio_buffers(folio);
2167 bh = head;
2168 do {
2169 struct journal_head *jh;
2170
2171 /*
2172 * We take our own ref against the journal_head here to avoid
2173 * having to add tons of locking around each instance of
2174 * jbd2_journal_put_journal_head().
2175 */
2176 jh = jbd2_journal_grab_journal_head(bh);
2177 if (!jh)
2178 continue;
2179
2180 spin_lock(&jh->b_state_lock);
2181 __journal_try_to_free_buffer(journal, bh);
2182 spin_unlock(&jh->b_state_lock);
2183 jbd2_journal_put_journal_head(jh);
2184 if (buffer_jbd(bh))
2185 goto busy;
2186 } while ((bh = bh->b_this_page) != head);
2187
2188 ret = try_to_free_buffers(folio);
2189busy:
2190 return ret;
2191}
2192
2193/*
2194 * This buffer is no longer needed. If it is on an older transaction's
2195 * checkpoint list we need to record it on this transaction's forget list
2196 * to pin this buffer (and hence its checkpointing transaction) down until
2197 * this transaction commits. If the buffer isn't on a checkpoint list, we
2198 * release it.
2199 * Returns non-zero if JBD no longer has an interest in the buffer.
2200 *
2201 * Called under j_list_lock.
2202 *
2203 * Called under jh->b_state_lock.
2204 */
2205static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
2206{
2207 int may_free = 1;
2208 struct buffer_head *bh = jh2bh(jh);
2209
2210 if (jh->b_cp_transaction) {
2211 JBUFFER_TRACE(jh, "on running+cp transaction");
2212 __jbd2_journal_temp_unlink_buffer(jh);
2213 /*
2214 * We don't want to write the buffer anymore, clear the
2215 * bit so that we don't confuse checks in
2216 * __journal_file_buffer
2217 */
2218 clear_buffer_dirty(bh);
2219 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
2220 may_free = 0;
2221 } else {
2222 JBUFFER_TRACE(jh, "on running transaction");
2223 __jbd2_journal_unfile_buffer(jh);
2224 jbd2_journal_put_journal_head(jh);
2225 }
2226 return may_free;
2227}
2228
2229/*
2230 * jbd2_journal_invalidate_folio
2231 *
2232 * This code is tricky. It has a number of cases to deal with.
2233 *
2234 * There are two invariants which this code relies on:
2235 *
2236 * i_size must be updated on disk before we start calling invalidate_folio
2237 * on the data.
2238 *
2239 * This is done in ext3 by defining an ext3_setattr method which
2240 * updates i_size before truncate gets going. By maintaining this
2241 * invariant, we can be sure that it is safe to throw away any buffers
2242 * attached to the current transaction: once the transaction commits,
2243 * we know that the data will not be needed.
2244 *
2245 * Note however that we can *not* throw away data belonging to the
2246 * previous, committing transaction!
2247 *
2248 * Any disk blocks which *are* part of the previous, committing
2249 * transaction (and which therefore cannot be discarded immediately) are
2250 * not going to be reused in the new running transaction
2251 *
2252 * The bitmap committed_data images guarantee this: any block which is
2253 * allocated in one transaction and removed in the next will be marked
2254 * as in-use in the committed_data bitmap, so cannot be reused until
2255 * the next transaction to delete the block commits. This means that
2256 * leaving committing buffers dirty is quite safe: the disk blocks
2257 * cannot be reallocated to a different file and so buffer aliasing is
2258 * not possible.
2259 *
2260 *
2261 * The above applies mainly to ordered data mode. In writeback mode we
2262 * don't make guarantees about the order in which data hits disk --- in
2263 * particular we don't guarantee that new dirty data is flushed before
2264 * transaction commit --- so it is always safe just to discard data
2265 * immediately in that mode. --sct
2266 */
2267
2268/*
2269 * The journal_unmap_buffer helper function returns zero if the buffer
2270 * concerned remains pinned as an anonymous buffer belonging to an older
2271 * transaction.
2272 *
2273 * We're outside-transaction here. Either or both of j_running_transaction
2274 * and j_committing_transaction may be NULL.
2275 */
2276static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
2277 int partial_page)
2278{
2279 transaction_t *transaction;
2280 struct journal_head *jh;
2281 int may_free = 1;
2282
2283 BUFFER_TRACE(bh, "entry");
2284
2285 /*
2286 * It is safe to proceed here without the j_list_lock because the
2287 * buffers cannot be stolen by try_to_free_buffers as long as we are
2288 * holding the page lock. --sct
2289 */
2290
2291 jh = jbd2_journal_grab_journal_head(bh);
2292 if (!jh)
2293 goto zap_buffer_unlocked;
2294
2295 /* OK, we have data buffer in journaled mode */
2296 write_lock(&journal->j_state_lock);
2297 spin_lock(&jh->b_state_lock);
2298 spin_lock(&journal->j_list_lock);
2299
2300 /*
2301 * We cannot remove the buffer from checkpoint lists until the
2302 * transaction adding inode to orphan list (let's call it T)
2303 * is committed. Otherwise if the transaction changing the
2304 * buffer would be cleaned from the journal before T is
2305 * committed, a crash will cause that the correct contents of
2306 * the buffer will be lost. On the other hand we have to
2307 * clear the buffer dirty bit at latest at the moment when the
2308 * transaction marking the buffer as freed in the filesystem
2309 * structures is committed because from that moment on the
2310 * block can be reallocated and used by a different page.
2311 * Since the block hasn't been freed yet but the inode has
2312 * already been added to orphan list, it is safe for us to add
2313 * the buffer to BJ_Forget list of the newest transaction.
2314 *
2315 * Also we have to clear buffer_mapped flag of a truncated buffer
2316 * because the buffer_head may be attached to the page straddling
2317 * i_size (can happen only when blocksize < pagesize) and thus the
2318 * buffer_head can be reused when the file is extended again. So we end
2319 * up keeping around invalidated buffers attached to transactions'
2320 * BJ_Forget list just to stop checkpointing code from cleaning up
2321 * the transaction this buffer was modified in.
2322 */
2323 transaction = jh->b_transaction;
2324 if (transaction == NULL) {
2325 /* First case: not on any transaction. If it
2326 * has no checkpoint link, then we can zap it:
2327 * it's a writeback-mode buffer so we don't care
2328 * if it hits disk safely. */
2329 if (!jh->b_cp_transaction) {
2330 JBUFFER_TRACE(jh, "not on any transaction: zap");
2331 goto zap_buffer;
2332 }
2333
2334 if (!buffer_dirty(bh)) {
2335 /* bdflush has written it. We can drop it now */
2336 __jbd2_journal_remove_checkpoint(jh);
2337 goto zap_buffer;
2338 }
2339
2340 /* OK, it must be in the journal but still not
2341 * written fully to disk: it's metadata or
2342 * journaled data... */
2343
2344 if (journal->j_running_transaction) {
2345 /* ... and once the current transaction has
2346 * committed, the buffer won't be needed any
2347 * longer. */
2348 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
2349 may_free = __dispose_buffer(jh,
2350 journal->j_running_transaction);
2351 goto zap_buffer;
2352 } else {
2353 /* There is no currently-running transaction. So the
2354 * orphan record which we wrote for this file must have
2355 * passed into commit. We must attach this buffer to
2356 * the committing transaction, if it exists. */
2357 if (journal->j_committing_transaction) {
2358 JBUFFER_TRACE(jh, "give to committing trans");
2359 may_free = __dispose_buffer(jh,
2360 journal->j_committing_transaction);
2361 goto zap_buffer;
2362 } else {
2363 /* The orphan record's transaction has
2364 * committed. We can cleanse this buffer */
2365 clear_buffer_jbddirty(bh);
2366 __jbd2_journal_remove_checkpoint(jh);
2367 goto zap_buffer;
2368 }
2369 }
2370 } else if (transaction == journal->j_committing_transaction) {
2371 JBUFFER_TRACE(jh, "on committing transaction");
2372 /*
2373 * The buffer is committing, we simply cannot touch
2374 * it. If the page is straddling i_size we have to wait
2375 * for commit and try again.
2376 */
2377 if (partial_page) {
2378 spin_unlock(&journal->j_list_lock);
2379 spin_unlock(&jh->b_state_lock);
2380 write_unlock(&journal->j_state_lock);
2381 jbd2_journal_put_journal_head(jh);
2382 return -EBUSY;
2383 }
2384 /*
2385 * OK, buffer won't be reachable after truncate. We just clear
2386 * b_modified to not confuse transaction credit accounting, and
2387 * set j_next_transaction to the running transaction (if there
2388 * is one) and mark buffer as freed so that commit code knows
2389 * it should clear dirty bits when it is done with the buffer.
2390 */
2391 set_buffer_freed(bh);
2392 if (journal->j_running_transaction && buffer_jbddirty(bh))
2393 jh->b_next_transaction = journal->j_running_transaction;
2394 jh->b_modified = 0;
2395 spin_unlock(&journal->j_list_lock);
2396 spin_unlock(&jh->b_state_lock);
2397 write_unlock(&journal->j_state_lock);
2398 jbd2_journal_put_journal_head(jh);
2399 return 0;
2400 } else {
2401 /* Good, the buffer belongs to the running transaction.
2402 * We are writing our own transaction's data, not any
2403 * previous one's, so it is safe to throw it away
2404 * (remember that we expect the filesystem to have set
2405 * i_size already for this truncate so recovery will not
2406 * expose the disk blocks we are discarding here.) */
2407 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
2408 JBUFFER_TRACE(jh, "on running transaction");
2409 may_free = __dispose_buffer(jh, transaction);
2410 }
2411
2412zap_buffer:
2413 /*
2414 * This is tricky. Although the buffer is truncated, it may be reused
2415 * if blocksize < pagesize and it is attached to the page straddling
2416 * EOF. Since the buffer might have been added to BJ_Forget list of the
2417 * running transaction, journal_get_write_access() won't clear
2418 * b_modified and credit accounting gets confused. So clear b_modified
2419 * here.
2420 */
2421 jh->b_modified = 0;
2422 spin_unlock(&journal->j_list_lock);
2423 spin_unlock(&jh->b_state_lock);
2424 write_unlock(&journal->j_state_lock);
2425 jbd2_journal_put_journal_head(jh);
2426zap_buffer_unlocked:
2427 clear_buffer_dirty(bh);
2428 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
2429 clear_buffer_mapped(bh);
2430 clear_buffer_req(bh);
2431 clear_buffer_new(bh);
2432 clear_buffer_delay(bh);
2433 clear_buffer_unwritten(bh);
2434 bh->b_bdev = NULL;
2435 return may_free;
2436}
2437
2438/**
2439 * jbd2_journal_invalidate_folio()
2440 * @journal: journal to use for flush...
2441 * @folio: folio to flush
2442 * @offset: start of the range to invalidate
2443 * @length: length of the range to invalidate
2444 *
2445 * Reap page buffers containing data after in the specified range in page.
2446 * Can return -EBUSY if buffers are part of the committing transaction and
2447 * the page is straddling i_size. Caller then has to wait for current commit
2448 * and try again.
2449 */
2450int jbd2_journal_invalidate_folio(journal_t *journal, struct folio *folio,
2451 size_t offset, size_t length)
2452{
2453 struct buffer_head *head, *bh, *next;
2454 unsigned int stop = offset + length;
2455 unsigned int curr_off = 0;
2456 int partial_page = (offset || length < folio_size(folio));
2457 int may_free = 1;
2458 int ret = 0;
2459
2460 if (!folio_test_locked(folio))
2461 BUG();
2462 head = folio_buffers(folio);
2463 if (!head)
2464 return 0;
2465
2466 BUG_ON(stop > folio_size(folio) || stop < length);
2467
2468 /* We will potentially be playing with lists other than just the
2469 * data lists (especially for journaled data mode), so be
2470 * cautious in our locking. */
2471
2472 bh = head;
2473 do {
2474 unsigned int next_off = curr_off + bh->b_size;
2475 next = bh->b_this_page;
2476
2477 if (next_off > stop)
2478 return 0;
2479
2480 if (offset <= curr_off) {
2481 /* This block is wholly outside the truncation point */
2482 lock_buffer(bh);
2483 ret = journal_unmap_buffer(journal, bh, partial_page);
2484 unlock_buffer(bh);
2485 if (ret < 0)
2486 return ret;
2487 may_free &= ret;
2488 }
2489 curr_off = next_off;
2490 bh = next;
2491
2492 } while (bh != head);
2493
2494 if (!partial_page) {
2495 if (may_free && try_to_free_buffers(folio))
2496 J_ASSERT(!folio_buffers(folio));
2497 }
2498 return 0;
2499}
2500
2501/*
2502 * File a buffer on the given transaction list.
2503 */
2504void __jbd2_journal_file_buffer(struct journal_head *jh,
2505 transaction_t *transaction, int jlist)
2506{
2507 struct journal_head **list = NULL;
2508 int was_dirty = 0;
2509 struct buffer_head *bh = jh2bh(jh);
2510
2511 lockdep_assert_held(&jh->b_state_lock);
2512 assert_spin_locked(&transaction->t_journal->j_list_lock);
2513
2514 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2515 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2516 jh->b_transaction == NULL);
2517
2518 if (jh->b_transaction && jh->b_jlist == jlist)
2519 return;
2520
2521 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
2522 jlist == BJ_Shadow || jlist == BJ_Forget) {
2523 /*
2524 * For metadata buffers, we track dirty bit in buffer_jbddirty
2525 * instead of buffer_dirty. We should not see a dirty bit set
2526 * here because we clear it in do_get_write_access but e.g.
2527 * tune2fs can modify the sb and set the dirty bit at any time
2528 * so we try to gracefully handle that.
2529 */
2530 if (buffer_dirty(bh))
2531 warn_dirty_buffer(bh);
2532 if (test_clear_buffer_dirty(bh) ||
2533 test_clear_buffer_jbddirty(bh))
2534 was_dirty = 1;
2535 }
2536
2537 if (jh->b_transaction)
2538 __jbd2_journal_temp_unlink_buffer(jh);
2539 else
2540 jbd2_journal_grab_journal_head(bh);
2541 jh->b_transaction = transaction;
2542
2543 switch (jlist) {
2544 case BJ_None:
2545 J_ASSERT_JH(jh, !jh->b_committed_data);
2546 J_ASSERT_JH(jh, !jh->b_frozen_data);
2547 return;
2548 case BJ_Metadata:
2549 transaction->t_nr_buffers++;
2550 list = &transaction->t_buffers;
2551 break;
2552 case BJ_Forget:
2553 list = &transaction->t_forget;
2554 break;
2555 case BJ_Shadow:
2556 list = &transaction->t_shadow_list;
2557 break;
2558 case BJ_Reserved:
2559 list = &transaction->t_reserved_list;
2560 break;
2561 }
2562
2563 __blist_add_buffer(list, jh);
2564 jh->b_jlist = jlist;
2565
2566 if (was_dirty)
2567 set_buffer_jbddirty(bh);
2568}
2569
2570void jbd2_journal_file_buffer(struct journal_head *jh,
2571 transaction_t *transaction, int jlist)
2572{
2573 spin_lock(&jh->b_state_lock);
2574 spin_lock(&transaction->t_journal->j_list_lock);
2575 __jbd2_journal_file_buffer(jh, transaction, jlist);
2576 spin_unlock(&transaction->t_journal->j_list_lock);
2577 spin_unlock(&jh->b_state_lock);
2578}
2579
2580/*
2581 * Remove a buffer from its current buffer list in preparation for
2582 * dropping it from its current transaction entirely. If the buffer has
2583 * already started to be used by a subsequent transaction, refile the
2584 * buffer on that transaction's metadata list.
2585 *
2586 * Called under j_list_lock
2587 * Called under jh->b_state_lock
2588 *
2589 * When this function returns true, there's no next transaction to refile to
2590 * and the caller has to drop jh reference through
2591 * jbd2_journal_put_journal_head().
2592 */
2593bool __jbd2_journal_refile_buffer(struct journal_head *jh)
2594{
2595 int was_dirty, jlist;
2596 struct buffer_head *bh = jh2bh(jh);
2597
2598 lockdep_assert_held(&jh->b_state_lock);
2599 if (jh->b_transaction)
2600 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2601
2602 /* If the buffer is now unused, just drop it. */
2603 if (jh->b_next_transaction == NULL) {
2604 __jbd2_journal_unfile_buffer(jh);
2605 return true;
2606 }
2607
2608 /*
2609 * It has been modified by a later transaction: add it to the new
2610 * transaction's metadata list.
2611 */
2612
2613 was_dirty = test_clear_buffer_jbddirty(bh);
2614 __jbd2_journal_temp_unlink_buffer(jh);
2615
2616 /*
2617 * b_transaction must be set, otherwise the new b_transaction won't
2618 * be holding jh reference
2619 */
2620 J_ASSERT_JH(jh, jh->b_transaction != NULL);
2621
2622 /*
2623 * We set b_transaction here because b_next_transaction will inherit
2624 * our jh reference and thus __jbd2_journal_file_buffer() must not
2625 * take a new one.
2626 */
2627 WRITE_ONCE(jh->b_transaction, jh->b_next_transaction);
2628 WRITE_ONCE(jh->b_next_transaction, NULL);
2629 if (buffer_freed(bh))
2630 jlist = BJ_Forget;
2631 else if (jh->b_modified)
2632 jlist = BJ_Metadata;
2633 else
2634 jlist = BJ_Reserved;
2635 __jbd2_journal_file_buffer(jh, jh->b_transaction, jlist);
2636 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2637
2638 if (was_dirty)
2639 set_buffer_jbddirty(bh);
2640 return false;
2641}
2642
2643/*
2644 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
2645 * bh reference so that we can safely unlock bh.
2646 *
2647 * The jh and bh may be freed by this call.
2648 */
2649void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2650{
2651 bool drop;
2652
2653 spin_lock(&jh->b_state_lock);
2654 spin_lock(&journal->j_list_lock);
2655 drop = __jbd2_journal_refile_buffer(jh);
2656 spin_unlock(&jh->b_state_lock);
2657 spin_unlock(&journal->j_list_lock);
2658 if (drop)
2659 jbd2_journal_put_journal_head(jh);
2660}
2661
2662/*
2663 * File inode in the inode list of the handle's transaction
2664 */
2665static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
2666 unsigned long flags, loff_t start_byte, loff_t end_byte)
2667{
2668 transaction_t *transaction = handle->h_transaction;
2669 journal_t *journal;
2670
2671 if (is_handle_aborted(handle))
2672 return -EROFS;
2673 journal = transaction->t_journal;
2674
2675 jbd2_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
2676 transaction->t_tid);
2677
2678 spin_lock(&journal->j_list_lock);
2679 jinode->i_flags |= flags;
2680
2681 if (jinode->i_dirty_end) {
2682 jinode->i_dirty_start = min(jinode->i_dirty_start, start_byte);
2683 jinode->i_dirty_end = max(jinode->i_dirty_end, end_byte);
2684 } else {
2685 jinode->i_dirty_start = start_byte;
2686 jinode->i_dirty_end = end_byte;
2687 }
2688
2689 /* Is inode already attached where we need it? */
2690 if (jinode->i_transaction == transaction ||
2691 jinode->i_next_transaction == transaction)
2692 goto done;
2693
2694 /*
2695 * We only ever set this variable to 1 so the test is safe. Since
2696 * t_need_data_flush is likely to be set, we do the test to save some
2697 * cacheline bouncing
2698 */
2699 if (!transaction->t_need_data_flush)
2700 transaction->t_need_data_flush = 1;
2701 /* On some different transaction's list - should be
2702 * the committing one */
2703 if (jinode->i_transaction) {
2704 J_ASSERT(jinode->i_next_transaction == NULL);
2705 J_ASSERT(jinode->i_transaction ==
2706 journal->j_committing_transaction);
2707 jinode->i_next_transaction = transaction;
2708 goto done;
2709 }
2710 /* Not on any transaction list... */
2711 J_ASSERT(!jinode->i_next_transaction);
2712 jinode->i_transaction = transaction;
2713 list_add(&jinode->i_list, &transaction->t_inode_list);
2714done:
2715 spin_unlock(&journal->j_list_lock);
2716
2717 return 0;
2718}
2719
2720int jbd2_journal_inode_ranged_write(handle_t *handle,
2721 struct jbd2_inode *jinode, loff_t start_byte, loff_t length)
2722{
2723 return jbd2_journal_file_inode(handle, jinode,
2724 JI_WRITE_DATA | JI_WAIT_DATA, start_byte,
2725 start_byte + length - 1);
2726}
2727
2728int jbd2_journal_inode_ranged_wait(handle_t *handle, struct jbd2_inode *jinode,
2729 loff_t start_byte, loff_t length)
2730{
2731 return jbd2_journal_file_inode(handle, jinode, JI_WAIT_DATA,
2732 start_byte, start_byte + length - 1);
2733}
2734
2735/*
2736 * File truncate and transaction commit interact with each other in a
2737 * non-trivial way. If a transaction writing data block A is
2738 * committing, we cannot discard the data by truncate until we have
2739 * written them. Otherwise if we crashed after the transaction with
2740 * write has committed but before the transaction with truncate has
2741 * committed, we could see stale data in block A. This function is a
2742 * helper to solve this problem. It starts writeout of the truncated
2743 * part in case it is in the committing transaction.
2744 *
2745 * Filesystem code must call this function when inode is journaled in
2746 * ordered mode before truncation happens and after the inode has been
2747 * placed on orphan list with the new inode size. The second condition
2748 * avoids the race that someone writes new data and we start
2749 * committing the transaction after this function has been called but
2750 * before a transaction for truncate is started (and furthermore it
2751 * allows us to optimize the case where the addition to orphan list
2752 * happens in the same transaction as write --- we don't have to write
2753 * any data in such case).
2754 */
2755int jbd2_journal_begin_ordered_truncate(journal_t *journal,
2756 struct jbd2_inode *jinode,
2757 loff_t new_size)
2758{
2759 transaction_t *inode_trans, *commit_trans;
2760 int ret = 0;
2761
2762 /* This is a quick check to avoid locking if not necessary */
2763 if (!jinode->i_transaction)
2764 goto out;
2765 /* Locks are here just to force reading of recent values, it is
2766 * enough that the transaction was not committing before we started
2767 * a transaction adding the inode to orphan list */
2768 read_lock(&journal->j_state_lock);
2769 commit_trans = journal->j_committing_transaction;
2770 read_unlock(&journal->j_state_lock);
2771 spin_lock(&journal->j_list_lock);
2772 inode_trans = jinode->i_transaction;
2773 spin_unlock(&journal->j_list_lock);
2774 if (inode_trans == commit_trans) {
2775 ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping,
2776 new_size, LLONG_MAX);
2777 if (ret)
2778 jbd2_journal_abort(journal, ret);
2779 }
2780out:
2781 return ret;
2782}