xref: /linux/fs/jbd2/journal.c (revision 8b8eed05a1c650c27e78bc47d07f7d6c9ba779e8)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * linux/fs/jbd2/journal.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 journal-writing code; part of the ext2fs
10  * journaling system.
11  *
12  * This file manages journals: areas of disk reserved for logging
13  * transactional updates.  This includes the kernel journaling thread
14  * which is responsible for scheduling updates to the log.
15  *
16  * We do not actually manage the physical storage of the journal in this
17  * file: that is left to a per-journal policy function, which allows us
18  * to store the journal within a filesystem-specified area for ext2
19  * journaling (ext2 can use a reserved inode for storing the log).
20  */
21 
22 #include <linux/module.h>
23 #include <linux/time.h>
24 #include <linux/fs.h>
25 #include <linux/jbd2.h>
26 #include <linux/errno.h>
27 #include <linux/slab.h>
28 #include <linux/init.h>
29 #include <linux/mm.h>
30 #include <linux/freezer.h>
31 #include <linux/pagemap.h>
32 #include <linux/kthread.h>
33 #include <linux/poison.h>
34 #include <linux/proc_fs.h>
35 #include <linux/seq_file.h>
36 #include <linux/math64.h>
37 #include <linux/hash.h>
38 #include <linux/log2.h>
39 #include <linux/vmalloc.h>
40 #include <linux/backing-dev.h>
41 #include <linux/bitops.h>
42 #include <linux/ratelimit.h>
43 #include <linux/sched/mm.h>
44 
45 #define CREATE_TRACE_POINTS
46 #include <trace/events/jbd2.h>
47 
48 #include <linux/uaccess.h>
49 #include <asm/page.h>
50 
51 #ifdef CONFIG_JBD2_DEBUG
52 static ushort jbd2_journal_enable_debug __read_mostly;
53 
54 module_param_named(jbd2_debug, jbd2_journal_enable_debug, ushort, 0644);
55 MODULE_PARM_DESC(jbd2_debug, "Debugging level for jbd2");
56 #endif
57 
58 EXPORT_SYMBOL(jbd2_journal_extend);
59 EXPORT_SYMBOL(jbd2_journal_stop);
60 EXPORT_SYMBOL(jbd2_journal_lock_updates);
61 EXPORT_SYMBOL(jbd2_journal_unlock_updates);
62 EXPORT_SYMBOL(jbd2_journal_get_write_access);
63 EXPORT_SYMBOL(jbd2_journal_get_create_access);
64 EXPORT_SYMBOL(jbd2_journal_get_undo_access);
65 EXPORT_SYMBOL(jbd2_journal_set_triggers);
66 EXPORT_SYMBOL(jbd2_journal_dirty_metadata);
67 EXPORT_SYMBOL(jbd2_journal_forget);
68 EXPORT_SYMBOL(jbd2_journal_flush);
69 EXPORT_SYMBOL(jbd2_journal_revoke);
70 
71 EXPORT_SYMBOL(jbd2_journal_init_dev);
72 EXPORT_SYMBOL(jbd2_journal_init_inode);
73 EXPORT_SYMBOL(jbd2_journal_check_used_features);
74 EXPORT_SYMBOL(jbd2_journal_check_available_features);
75 EXPORT_SYMBOL(jbd2_journal_set_features);
76 EXPORT_SYMBOL(jbd2_journal_load);
77 EXPORT_SYMBOL(jbd2_journal_destroy);
78 EXPORT_SYMBOL(jbd2_journal_abort);
79 EXPORT_SYMBOL(jbd2_journal_errno);
80 EXPORT_SYMBOL(jbd2_journal_ack_err);
81 EXPORT_SYMBOL(jbd2_journal_clear_err);
82 EXPORT_SYMBOL(jbd2_log_wait_commit);
83 EXPORT_SYMBOL(jbd2_journal_start_commit);
84 EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
85 EXPORT_SYMBOL(jbd2_journal_wipe);
86 EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
87 EXPORT_SYMBOL(jbd2_journal_invalidate_folio);
88 EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
89 EXPORT_SYMBOL(jbd2_journal_force_commit);
90 EXPORT_SYMBOL(jbd2_journal_inode_ranged_write);
91 EXPORT_SYMBOL(jbd2_journal_inode_ranged_wait);
92 EXPORT_SYMBOL(jbd2_journal_finish_inode_data_buffers);
93 EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
94 EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
95 EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
96 EXPORT_SYMBOL(jbd2_inode_cache);
97 
98 static int jbd2_journal_create_slab(size_t slab_size);
99 
100 #ifdef CONFIG_JBD2_DEBUG
101 void __jbd2_debug(int level, const char *file, const char *func,
102 		  unsigned int line, const char *fmt, ...)
103 {
104 	struct va_format vaf;
105 	va_list args;
106 
107 	if (level > jbd2_journal_enable_debug)
108 		return;
109 	va_start(args, fmt);
110 	vaf.fmt = fmt;
111 	vaf.va = &args;
112 	printk(KERN_DEBUG "%s: (%s, %u): %pV", file, func, line, &vaf);
113 	va_end(args);
114 }
115 #endif
116 
117 /* Checksumming functions */
118 static __be32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb)
119 {
120 	__u32 csum;
121 	__be32 old_csum;
122 
123 	old_csum = sb->s_checksum;
124 	sb->s_checksum = 0;
125 	csum = jbd2_chksum(j, ~0, (char *)sb, sizeof(journal_superblock_t));
126 	sb->s_checksum = old_csum;
127 
128 	return cpu_to_be32(csum);
129 }
130 
131 /*
132  * Helper function used to manage commit timeouts
133  */
134 
135 static void commit_timeout(struct timer_list *t)
136 {
137 	journal_t *journal = from_timer(journal, t, j_commit_timer);
138 
139 	wake_up_process(journal->j_task);
140 }
141 
142 /*
143  * kjournald2: The main thread function used to manage a logging device
144  * journal.
145  *
146  * This kernel thread is responsible for two things:
147  *
148  * 1) COMMIT:  Every so often we need to commit the current state of the
149  *    filesystem to disk.  The journal thread is responsible for writing
150  *    all of the metadata buffers to disk. If a fast commit is ongoing
151  *    journal thread waits until it's done and then continues from
152  *    there on.
153  *
154  * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
155  *    of the data in that part of the log has been rewritten elsewhere on
156  *    the disk.  Flushing these old buffers to reclaim space in the log is
157  *    known as checkpointing, and this thread is responsible for that job.
158  */
159 
160 static int kjournald2(void *arg)
161 {
162 	journal_t *journal = arg;
163 	transaction_t *transaction;
164 
165 	/*
166 	 * Set up an interval timer which can be used to trigger a commit wakeup
167 	 * after the commit interval expires
168 	 */
169 	timer_setup(&journal->j_commit_timer, commit_timeout, 0);
170 
171 	set_freezable();
172 
173 	/* Record that the journal thread is running */
174 	journal->j_task = current;
175 	wake_up(&journal->j_wait_done_commit);
176 
177 	/*
178 	 * Make sure that no allocations from this kernel thread will ever
179 	 * recurse to the fs layer because we are responsible for the
180 	 * transaction commit and any fs involvement might get stuck waiting for
181 	 * the trasn. commit.
182 	 */
183 	memalloc_nofs_save();
184 
185 	/*
186 	 * And now, wait forever for commit wakeup events.
187 	 */
188 	write_lock(&journal->j_state_lock);
189 
190 loop:
191 	if (journal->j_flags & JBD2_UNMOUNT)
192 		goto end_loop;
193 
194 	jbd2_debug(1, "commit_sequence=%u, commit_request=%u\n",
195 		journal->j_commit_sequence, journal->j_commit_request);
196 
197 	if (journal->j_commit_sequence != journal->j_commit_request) {
198 		jbd2_debug(1, "OK, requests differ\n");
199 		write_unlock(&journal->j_state_lock);
200 		del_timer_sync(&journal->j_commit_timer);
201 		jbd2_journal_commit_transaction(journal);
202 		write_lock(&journal->j_state_lock);
203 		goto loop;
204 	}
205 
206 	wake_up(&journal->j_wait_done_commit);
207 	if (freezing(current)) {
208 		/*
209 		 * The simpler the better. Flushing journal isn't a
210 		 * good idea, because that depends on threads that may
211 		 * be already stopped.
212 		 */
213 		jbd2_debug(1, "Now suspending kjournald2\n");
214 		write_unlock(&journal->j_state_lock);
215 		try_to_freeze();
216 		write_lock(&journal->j_state_lock);
217 	} else {
218 		/*
219 		 * We assume on resume that commits are already there,
220 		 * so we don't sleep
221 		 */
222 		DEFINE_WAIT(wait);
223 		int should_sleep = 1;
224 
225 		prepare_to_wait(&journal->j_wait_commit, &wait,
226 				TASK_INTERRUPTIBLE);
227 		if (journal->j_commit_sequence != journal->j_commit_request)
228 			should_sleep = 0;
229 		transaction = journal->j_running_transaction;
230 		if (transaction && time_after_eq(jiffies,
231 						transaction->t_expires))
232 			should_sleep = 0;
233 		if (journal->j_flags & JBD2_UNMOUNT)
234 			should_sleep = 0;
235 		if (should_sleep) {
236 			write_unlock(&journal->j_state_lock);
237 			schedule();
238 			write_lock(&journal->j_state_lock);
239 		}
240 		finish_wait(&journal->j_wait_commit, &wait);
241 	}
242 
243 	jbd2_debug(1, "kjournald2 wakes\n");
244 
245 	/*
246 	 * Were we woken up by a commit wakeup event?
247 	 */
248 	transaction = journal->j_running_transaction;
249 	if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
250 		journal->j_commit_request = transaction->t_tid;
251 		jbd2_debug(1, "woke because of timeout\n");
252 	}
253 	goto loop;
254 
255 end_loop:
256 	del_timer_sync(&journal->j_commit_timer);
257 	journal->j_task = NULL;
258 	wake_up(&journal->j_wait_done_commit);
259 	jbd2_debug(1, "Journal thread exiting.\n");
260 	write_unlock(&journal->j_state_lock);
261 	return 0;
262 }
263 
264 static int jbd2_journal_start_thread(journal_t *journal)
265 {
266 	struct task_struct *t;
267 
268 	t = kthread_run(kjournald2, journal, "jbd2/%s",
269 			journal->j_devname);
270 	if (IS_ERR(t))
271 		return PTR_ERR(t);
272 
273 	wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
274 	return 0;
275 }
276 
277 static void journal_kill_thread(journal_t *journal)
278 {
279 	write_lock(&journal->j_state_lock);
280 	journal->j_flags |= JBD2_UNMOUNT;
281 
282 	while (journal->j_task) {
283 		write_unlock(&journal->j_state_lock);
284 		wake_up(&journal->j_wait_commit);
285 		wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
286 		write_lock(&journal->j_state_lock);
287 	}
288 	write_unlock(&journal->j_state_lock);
289 }
290 
291 /*
292  * jbd2_journal_write_metadata_buffer: write a metadata buffer to the journal.
293  *
294  * Writes a metadata buffer to a given disk block.  The actual IO is not
295  * performed but a new buffer_head is constructed which labels the data
296  * to be written with the correct destination disk block.
297  *
298  * Any magic-number escaping which needs to be done will cause a
299  * copy-out here.  If the buffer happens to start with the
300  * JBD2_MAGIC_NUMBER, then we can't write it to the log directly: the
301  * magic number is only written to the log for descripter blocks.  In
302  * this case, we copy the data and replace the first word with 0, and we
303  * return a result code which indicates that this buffer needs to be
304  * marked as an escaped buffer in the corresponding log descriptor
305  * block.  The missing word can then be restored when the block is read
306  * during recovery.
307  *
308  * If the source buffer has already been modified by a new transaction
309  * since we took the last commit snapshot, we use the frozen copy of
310  * that data for IO. If we end up using the existing buffer_head's data
311  * for the write, then we have to make sure nobody modifies it while the
312  * IO is in progress. do_get_write_access() handles this.
313  *
314  * The function returns a pointer to the buffer_head to be used for IO.
315  *
316  *
317  * Return value:
318  *  <0: Error
319  * >=0: Finished OK
320  *
321  * On success:
322  * Bit 0 set == escape performed on the data
323  * Bit 1 set == buffer copy-out performed (kfree the data after IO)
324  */
325 
326 int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
327 				  struct journal_head  *jh_in,
328 				  struct buffer_head **bh_out,
329 				  sector_t blocknr)
330 {
331 	int need_copy_out = 0;
332 	int done_copy_out = 0;
333 	int do_escape = 0;
334 	char *mapped_data;
335 	struct buffer_head *new_bh;
336 	struct folio *new_folio;
337 	unsigned int new_offset;
338 	struct buffer_head *bh_in = jh2bh(jh_in);
339 	journal_t *journal = transaction->t_journal;
340 
341 	/*
342 	 * The buffer really shouldn't be locked: only the current committing
343 	 * transaction is allowed to write it, so nobody else is allowed
344 	 * to do any IO.
345 	 *
346 	 * akpm: except if we're journalling data, and write() output is
347 	 * also part of a shared mapping, and another thread has
348 	 * decided to launch a writepage() against this buffer.
349 	 */
350 	J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
351 
352 	new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
353 
354 	/* keep subsequent assertions sane */
355 	atomic_set(&new_bh->b_count, 1);
356 
357 	spin_lock(&jh_in->b_state_lock);
358 repeat:
359 	/*
360 	 * If a new transaction has already done a buffer copy-out, then
361 	 * we use that version of the data for the commit.
362 	 */
363 	if (jh_in->b_frozen_data) {
364 		done_copy_out = 1;
365 		new_folio = virt_to_folio(jh_in->b_frozen_data);
366 		new_offset = offset_in_folio(new_folio, jh_in->b_frozen_data);
367 	} else {
368 		new_folio = jh2bh(jh_in)->b_folio;
369 		new_offset = offset_in_folio(new_folio, jh2bh(jh_in)->b_data);
370 	}
371 
372 	mapped_data = kmap_local_folio(new_folio, new_offset);
373 	/*
374 	 * Fire data frozen trigger if data already wasn't frozen.  Do this
375 	 * before checking for escaping, as the trigger may modify the magic
376 	 * offset.  If a copy-out happens afterwards, it will have the correct
377 	 * data in the buffer.
378 	 */
379 	if (!done_copy_out)
380 		jbd2_buffer_frozen_trigger(jh_in, mapped_data,
381 					   jh_in->b_triggers);
382 
383 	/*
384 	 * Check for escaping
385 	 */
386 	if (*((__be32 *)mapped_data) == cpu_to_be32(JBD2_MAGIC_NUMBER)) {
387 		need_copy_out = 1;
388 		do_escape = 1;
389 	}
390 	kunmap_local(mapped_data);
391 
392 	/*
393 	 * Do we need to do a data copy?
394 	 */
395 	if (need_copy_out && !done_copy_out) {
396 		char *tmp;
397 
398 		spin_unlock(&jh_in->b_state_lock);
399 		tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS);
400 		if (!tmp) {
401 			brelse(new_bh);
402 			return -ENOMEM;
403 		}
404 		spin_lock(&jh_in->b_state_lock);
405 		if (jh_in->b_frozen_data) {
406 			jbd2_free(tmp, bh_in->b_size);
407 			goto repeat;
408 		}
409 
410 		jh_in->b_frozen_data = tmp;
411 		memcpy_from_folio(tmp, new_folio, new_offset, bh_in->b_size);
412 
413 		new_folio = virt_to_folio(tmp);
414 		new_offset = offset_in_folio(new_folio, tmp);
415 		done_copy_out = 1;
416 
417 		/*
418 		 * This isn't strictly necessary, as we're using frozen
419 		 * data for the escaping, but it keeps consistency with
420 		 * b_frozen_data usage.
421 		 */
422 		jh_in->b_frozen_triggers = jh_in->b_triggers;
423 	}
424 
425 	/*
426 	 * Did we need to do an escaping?  Now we've done all the
427 	 * copying, we can finally do so.
428 	 */
429 	if (do_escape) {
430 		mapped_data = kmap_local_folio(new_folio, new_offset);
431 		*((unsigned int *)mapped_data) = 0;
432 		kunmap_local(mapped_data);
433 	}
434 
435 	folio_set_bh(new_bh, new_folio, new_offset);
436 	new_bh->b_size = bh_in->b_size;
437 	new_bh->b_bdev = journal->j_dev;
438 	new_bh->b_blocknr = blocknr;
439 	new_bh->b_private = bh_in;
440 	set_buffer_mapped(new_bh);
441 	set_buffer_dirty(new_bh);
442 
443 	*bh_out = new_bh;
444 
445 	/*
446 	 * The to-be-written buffer needs to get moved to the io queue,
447 	 * and the original buffer whose contents we are shadowing or
448 	 * copying is moved to the transaction's shadow queue.
449 	 */
450 	JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
451 	spin_lock(&journal->j_list_lock);
452 	__jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
453 	spin_unlock(&journal->j_list_lock);
454 	set_buffer_shadow(bh_in);
455 	spin_unlock(&jh_in->b_state_lock);
456 
457 	return do_escape | (done_copy_out << 1);
458 }
459 
460 /*
461  * Allocation code for the journal file.  Manage the space left in the
462  * journal, so that we can begin checkpointing when appropriate.
463  */
464 
465 /*
466  * Called with j_state_lock locked for writing.
467  * Returns true if a transaction commit was started.
468  */
469 static int __jbd2_log_start_commit(journal_t *journal, tid_t target)
470 {
471 	/* Return if the txn has already requested to be committed */
472 	if (journal->j_commit_request == target)
473 		return 0;
474 
475 	/*
476 	 * The only transaction we can possibly wait upon is the
477 	 * currently running transaction (if it exists).  Otherwise,
478 	 * the target tid must be an old one.
479 	 */
480 	if (journal->j_running_transaction &&
481 	    journal->j_running_transaction->t_tid == target) {
482 		/*
483 		 * We want a new commit: OK, mark the request and wakeup the
484 		 * commit thread.  We do _not_ do the commit ourselves.
485 		 */
486 
487 		journal->j_commit_request = target;
488 		jbd2_debug(1, "JBD2: requesting commit %u/%u\n",
489 			  journal->j_commit_request,
490 			  journal->j_commit_sequence);
491 		journal->j_running_transaction->t_requested = jiffies;
492 		wake_up(&journal->j_wait_commit);
493 		return 1;
494 	} else if (!tid_geq(journal->j_commit_request, target))
495 		/* This should never happen, but if it does, preserve
496 		   the evidence before kjournald goes into a loop and
497 		   increments j_commit_sequence beyond all recognition. */
498 		WARN_ONCE(1, "JBD2: bad log_start_commit: %u %u %u %u\n",
499 			  journal->j_commit_request,
500 			  journal->j_commit_sequence,
501 			  target, journal->j_running_transaction ?
502 			  journal->j_running_transaction->t_tid : 0);
503 	return 0;
504 }
505 
506 int jbd2_log_start_commit(journal_t *journal, tid_t tid)
507 {
508 	int ret;
509 
510 	write_lock(&journal->j_state_lock);
511 	ret = __jbd2_log_start_commit(journal, tid);
512 	write_unlock(&journal->j_state_lock);
513 	return ret;
514 }
515 
516 /*
517  * Force and wait any uncommitted transactions.  We can only force the running
518  * transaction if we don't have an active handle, otherwise, we will deadlock.
519  * Returns: <0 in case of error,
520  *           0 if nothing to commit,
521  *           1 if transaction was successfully committed.
522  */
523 static int __jbd2_journal_force_commit(journal_t *journal)
524 {
525 	transaction_t *transaction = NULL;
526 	tid_t tid;
527 	int need_to_start = 0, ret = 0;
528 
529 	read_lock(&journal->j_state_lock);
530 	if (journal->j_running_transaction && !current->journal_info) {
531 		transaction = journal->j_running_transaction;
532 		if (!tid_geq(journal->j_commit_request, transaction->t_tid))
533 			need_to_start = 1;
534 	} else if (journal->j_committing_transaction)
535 		transaction = journal->j_committing_transaction;
536 
537 	if (!transaction) {
538 		/* Nothing to commit */
539 		read_unlock(&journal->j_state_lock);
540 		return 0;
541 	}
542 	tid = transaction->t_tid;
543 	read_unlock(&journal->j_state_lock);
544 	if (need_to_start)
545 		jbd2_log_start_commit(journal, tid);
546 	ret = jbd2_log_wait_commit(journal, tid);
547 	if (!ret)
548 		ret = 1;
549 
550 	return ret;
551 }
552 
553 /**
554  * jbd2_journal_force_commit_nested - Force and wait upon a commit if the
555  * calling process is not within transaction.
556  *
557  * @journal: journal to force
558  * Returns true if progress was made.
559  *
560  * This is used for forcing out undo-protected data which contains
561  * bitmaps, when the fs is running out of space.
562  */
563 int jbd2_journal_force_commit_nested(journal_t *journal)
564 {
565 	int ret;
566 
567 	ret = __jbd2_journal_force_commit(journal);
568 	return ret > 0;
569 }
570 
571 /**
572  * jbd2_journal_force_commit() - force any uncommitted transactions
573  * @journal: journal to force
574  *
575  * Caller want unconditional commit. We can only force the running transaction
576  * if we don't have an active handle, otherwise, we will deadlock.
577  */
578 int jbd2_journal_force_commit(journal_t *journal)
579 {
580 	int ret;
581 
582 	J_ASSERT(!current->journal_info);
583 	ret = __jbd2_journal_force_commit(journal);
584 	if (ret > 0)
585 		ret = 0;
586 	return ret;
587 }
588 
589 /*
590  * Start a commit of the current running transaction (if any).  Returns true
591  * if a transaction is going to be committed (or is currently already
592  * committing), and fills its tid in at *ptid
593  */
594 int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
595 {
596 	int ret = 0;
597 
598 	write_lock(&journal->j_state_lock);
599 	if (journal->j_running_transaction) {
600 		tid_t tid = journal->j_running_transaction->t_tid;
601 
602 		__jbd2_log_start_commit(journal, tid);
603 		/* There's a running transaction and we've just made sure
604 		 * it's commit has been scheduled. */
605 		if (ptid)
606 			*ptid = tid;
607 		ret = 1;
608 	} else if (journal->j_committing_transaction) {
609 		/*
610 		 * If commit has been started, then we have to wait for
611 		 * completion of that transaction.
612 		 */
613 		if (ptid)
614 			*ptid = journal->j_committing_transaction->t_tid;
615 		ret = 1;
616 	}
617 	write_unlock(&journal->j_state_lock);
618 	return ret;
619 }
620 
621 /*
622  * Return 1 if a given transaction has not yet sent barrier request
623  * connected with a transaction commit. If 0 is returned, transaction
624  * may or may not have sent the barrier. Used to avoid sending barrier
625  * twice in common cases.
626  */
627 int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid)
628 {
629 	int ret = 0;
630 	transaction_t *commit_trans;
631 
632 	if (!(journal->j_flags & JBD2_BARRIER))
633 		return 0;
634 	read_lock(&journal->j_state_lock);
635 	/* Transaction already committed? */
636 	if (tid_geq(journal->j_commit_sequence, tid))
637 		goto out;
638 	commit_trans = journal->j_committing_transaction;
639 	if (!commit_trans || commit_trans->t_tid != tid) {
640 		ret = 1;
641 		goto out;
642 	}
643 	/*
644 	 * Transaction is being committed and we already proceeded to
645 	 * submitting a flush to fs partition?
646 	 */
647 	if (journal->j_fs_dev != journal->j_dev) {
648 		if (!commit_trans->t_need_data_flush ||
649 		    commit_trans->t_state >= T_COMMIT_DFLUSH)
650 			goto out;
651 	} else {
652 		if (commit_trans->t_state >= T_COMMIT_JFLUSH)
653 			goto out;
654 	}
655 	ret = 1;
656 out:
657 	read_unlock(&journal->j_state_lock);
658 	return ret;
659 }
660 EXPORT_SYMBOL(jbd2_trans_will_send_data_barrier);
661 
662 /*
663  * Wait for a specified commit to complete.
664  * The caller may not hold the journal lock.
665  */
666 int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
667 {
668 	int err = 0;
669 
670 	read_lock(&journal->j_state_lock);
671 #ifdef CONFIG_PROVE_LOCKING
672 	/*
673 	 * Some callers make sure transaction is already committing and in that
674 	 * case we cannot block on open handles anymore. So don't warn in that
675 	 * case.
676 	 */
677 	if (tid_gt(tid, journal->j_commit_sequence) &&
678 	    (!journal->j_committing_transaction ||
679 	     journal->j_committing_transaction->t_tid != tid)) {
680 		read_unlock(&journal->j_state_lock);
681 		jbd2_might_wait_for_commit(journal);
682 		read_lock(&journal->j_state_lock);
683 	}
684 #endif
685 #ifdef CONFIG_JBD2_DEBUG
686 	if (!tid_geq(journal->j_commit_request, tid)) {
687 		printk(KERN_ERR
688 		       "%s: error: j_commit_request=%u, tid=%u\n",
689 		       __func__, journal->j_commit_request, tid);
690 	}
691 #endif
692 	while (tid_gt(tid, journal->j_commit_sequence)) {
693 		jbd2_debug(1, "JBD2: want %u, j_commit_sequence=%u\n",
694 				  tid, journal->j_commit_sequence);
695 		read_unlock(&journal->j_state_lock);
696 		wake_up(&journal->j_wait_commit);
697 		wait_event(journal->j_wait_done_commit,
698 				!tid_gt(tid, journal->j_commit_sequence));
699 		read_lock(&journal->j_state_lock);
700 	}
701 	read_unlock(&journal->j_state_lock);
702 
703 	if (unlikely(is_journal_aborted(journal)))
704 		err = -EIO;
705 	return err;
706 }
707 
708 /*
709  * Start a fast commit. If there's an ongoing fast or full commit wait for
710  * it to complete. Returns 0 if a new fast commit was started. Returns -EALREADY
711  * if a fast commit is not needed, either because there's an already a commit
712  * going on or this tid has already been committed. Returns -EINVAL if no jbd2
713  * commit has yet been performed.
714  */
715 int jbd2_fc_begin_commit(journal_t *journal, tid_t tid)
716 {
717 	if (unlikely(is_journal_aborted(journal)))
718 		return -EIO;
719 	/*
720 	 * Fast commits only allowed if at least one full commit has
721 	 * been processed.
722 	 */
723 	if (!journal->j_stats.ts_tid)
724 		return -EINVAL;
725 
726 	write_lock(&journal->j_state_lock);
727 	if (tid <= journal->j_commit_sequence) {
728 		write_unlock(&journal->j_state_lock);
729 		return -EALREADY;
730 	}
731 
732 	if (journal->j_flags & JBD2_FULL_COMMIT_ONGOING ||
733 	    (journal->j_flags & JBD2_FAST_COMMIT_ONGOING)) {
734 		DEFINE_WAIT(wait);
735 
736 		prepare_to_wait(&journal->j_fc_wait, &wait,
737 				TASK_UNINTERRUPTIBLE);
738 		write_unlock(&journal->j_state_lock);
739 		schedule();
740 		finish_wait(&journal->j_fc_wait, &wait);
741 		return -EALREADY;
742 	}
743 	journal->j_flags |= JBD2_FAST_COMMIT_ONGOING;
744 	write_unlock(&journal->j_state_lock);
745 	jbd2_journal_lock_updates(journal);
746 
747 	return 0;
748 }
749 EXPORT_SYMBOL(jbd2_fc_begin_commit);
750 
751 /*
752  * Stop a fast commit. If fallback is set, this function starts commit of
753  * TID tid before any other fast commit can start.
754  */
755 static int __jbd2_fc_end_commit(journal_t *journal, tid_t tid, bool fallback)
756 {
757 	jbd2_journal_unlock_updates(journal);
758 	if (journal->j_fc_cleanup_callback)
759 		journal->j_fc_cleanup_callback(journal, 0, tid);
760 	write_lock(&journal->j_state_lock);
761 	journal->j_flags &= ~JBD2_FAST_COMMIT_ONGOING;
762 	if (fallback)
763 		journal->j_flags |= JBD2_FULL_COMMIT_ONGOING;
764 	write_unlock(&journal->j_state_lock);
765 	wake_up(&journal->j_fc_wait);
766 	if (fallback)
767 		return jbd2_complete_transaction(journal, tid);
768 	return 0;
769 }
770 
771 int jbd2_fc_end_commit(journal_t *journal)
772 {
773 	return __jbd2_fc_end_commit(journal, 0, false);
774 }
775 EXPORT_SYMBOL(jbd2_fc_end_commit);
776 
777 int jbd2_fc_end_commit_fallback(journal_t *journal)
778 {
779 	tid_t tid;
780 
781 	read_lock(&journal->j_state_lock);
782 	tid = journal->j_running_transaction ?
783 		journal->j_running_transaction->t_tid : 0;
784 	read_unlock(&journal->j_state_lock);
785 	return __jbd2_fc_end_commit(journal, tid, true);
786 }
787 EXPORT_SYMBOL(jbd2_fc_end_commit_fallback);
788 
789 /* Return 1 when transaction with given tid has already committed. */
790 int jbd2_transaction_committed(journal_t *journal, tid_t tid)
791 {
792 	int ret = 1;
793 
794 	read_lock(&journal->j_state_lock);
795 	if (journal->j_running_transaction &&
796 	    journal->j_running_transaction->t_tid == tid)
797 		ret = 0;
798 	if (journal->j_committing_transaction &&
799 	    journal->j_committing_transaction->t_tid == tid)
800 		ret = 0;
801 	read_unlock(&journal->j_state_lock);
802 	return ret;
803 }
804 EXPORT_SYMBOL(jbd2_transaction_committed);
805 
806 /*
807  * When this function returns the transaction corresponding to tid
808  * will be completed.  If the transaction has currently running, start
809  * committing that transaction before waiting for it to complete.  If
810  * the transaction id is stale, it is by definition already completed,
811  * so just return SUCCESS.
812  */
813 int jbd2_complete_transaction(journal_t *journal, tid_t tid)
814 {
815 	int	need_to_wait = 1;
816 
817 	read_lock(&journal->j_state_lock);
818 	if (journal->j_running_transaction &&
819 	    journal->j_running_transaction->t_tid == tid) {
820 		if (journal->j_commit_request != tid) {
821 			/* transaction not yet started, so request it */
822 			read_unlock(&journal->j_state_lock);
823 			jbd2_log_start_commit(journal, tid);
824 			goto wait_commit;
825 		}
826 	} else if (!(journal->j_committing_transaction &&
827 		     journal->j_committing_transaction->t_tid == tid))
828 		need_to_wait = 0;
829 	read_unlock(&journal->j_state_lock);
830 	if (!need_to_wait)
831 		return 0;
832 wait_commit:
833 	return jbd2_log_wait_commit(journal, tid);
834 }
835 EXPORT_SYMBOL(jbd2_complete_transaction);
836 
837 /*
838  * Log buffer allocation routines:
839  */
840 
841 int jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
842 {
843 	unsigned long blocknr;
844 
845 	write_lock(&journal->j_state_lock);
846 	J_ASSERT(journal->j_free > 1);
847 
848 	blocknr = journal->j_head;
849 	journal->j_head++;
850 	journal->j_free--;
851 	if (journal->j_head == journal->j_last)
852 		journal->j_head = journal->j_first;
853 	write_unlock(&journal->j_state_lock);
854 	return jbd2_journal_bmap(journal, blocknr, retp);
855 }
856 
857 /* Map one fast commit buffer for use by the file system */
858 int jbd2_fc_get_buf(journal_t *journal, struct buffer_head **bh_out)
859 {
860 	unsigned long long pblock;
861 	unsigned long blocknr;
862 	int ret = 0;
863 	struct buffer_head *bh;
864 	int fc_off;
865 
866 	*bh_out = NULL;
867 
868 	if (journal->j_fc_off + journal->j_fc_first < journal->j_fc_last) {
869 		fc_off = journal->j_fc_off;
870 		blocknr = journal->j_fc_first + fc_off;
871 		journal->j_fc_off++;
872 	} else {
873 		ret = -EINVAL;
874 	}
875 
876 	if (ret)
877 		return ret;
878 
879 	ret = jbd2_journal_bmap(journal, blocknr, &pblock);
880 	if (ret)
881 		return ret;
882 
883 	bh = __getblk(journal->j_dev, pblock, journal->j_blocksize);
884 	if (!bh)
885 		return -ENOMEM;
886 
887 
888 	journal->j_fc_wbuf[fc_off] = bh;
889 
890 	*bh_out = bh;
891 
892 	return 0;
893 }
894 EXPORT_SYMBOL(jbd2_fc_get_buf);
895 
896 /*
897  * Wait on fast commit buffers that were allocated by jbd2_fc_get_buf
898  * for completion.
899  */
900 int jbd2_fc_wait_bufs(journal_t *journal, int num_blks)
901 {
902 	struct buffer_head *bh;
903 	int i, j_fc_off;
904 
905 	j_fc_off = journal->j_fc_off;
906 
907 	/*
908 	 * Wait in reverse order to minimize chances of us being woken up before
909 	 * all IOs have completed
910 	 */
911 	for (i = j_fc_off - 1; i >= j_fc_off - num_blks; i--) {
912 		bh = journal->j_fc_wbuf[i];
913 		wait_on_buffer(bh);
914 		/*
915 		 * Update j_fc_off so jbd2_fc_release_bufs can release remain
916 		 * buffer head.
917 		 */
918 		if (unlikely(!buffer_uptodate(bh))) {
919 			journal->j_fc_off = i + 1;
920 			return -EIO;
921 		}
922 		put_bh(bh);
923 		journal->j_fc_wbuf[i] = NULL;
924 	}
925 
926 	return 0;
927 }
928 EXPORT_SYMBOL(jbd2_fc_wait_bufs);
929 
930 int jbd2_fc_release_bufs(journal_t *journal)
931 {
932 	struct buffer_head *bh;
933 	int i, j_fc_off;
934 
935 	j_fc_off = journal->j_fc_off;
936 
937 	for (i = j_fc_off - 1; i >= 0; i--) {
938 		bh = journal->j_fc_wbuf[i];
939 		if (!bh)
940 			break;
941 		put_bh(bh);
942 		journal->j_fc_wbuf[i] = NULL;
943 	}
944 
945 	return 0;
946 }
947 EXPORT_SYMBOL(jbd2_fc_release_bufs);
948 
949 /*
950  * Conversion of logical to physical block numbers for the journal
951  *
952  * On external journals the journal blocks are identity-mapped, so
953  * this is a no-op.  If needed, we can use j_blk_offset - everything is
954  * ready.
955  */
956 int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
957 		 unsigned long long *retp)
958 {
959 	int err = 0;
960 	unsigned long long ret;
961 	sector_t block = blocknr;
962 
963 	if (journal->j_bmap) {
964 		err = journal->j_bmap(journal, &block);
965 		if (err == 0)
966 			*retp = block;
967 	} else if (journal->j_inode) {
968 		ret = bmap(journal->j_inode, &block);
969 
970 		if (ret || !block) {
971 			printk(KERN_ALERT "%s: journal block not found "
972 					"at offset %lu on %s\n",
973 			       __func__, blocknr, journal->j_devname);
974 			err = -EIO;
975 			jbd2_journal_abort(journal, err);
976 		} else {
977 			*retp = block;
978 		}
979 
980 	} else {
981 		*retp = blocknr; /* +journal->j_blk_offset */
982 	}
983 	return err;
984 }
985 
986 /*
987  * We play buffer_head aliasing tricks to write data/metadata blocks to
988  * the journal without copying their contents, but for journal
989  * descriptor blocks we do need to generate bona fide buffers.
990  *
991  * After the caller of jbd2_journal_get_descriptor_buffer() has finished modifying
992  * the buffer's contents they really should run flush_dcache_page(bh->b_page).
993  * But we don't bother doing that, so there will be coherency problems with
994  * mmaps of blockdevs which hold live JBD-controlled filesystems.
995  */
996 struct buffer_head *
997 jbd2_journal_get_descriptor_buffer(transaction_t *transaction, int type)
998 {
999 	journal_t *journal = transaction->t_journal;
1000 	struct buffer_head *bh;
1001 	unsigned long long blocknr;
1002 	journal_header_t *header;
1003 	int err;
1004 
1005 	err = jbd2_journal_next_log_block(journal, &blocknr);
1006 
1007 	if (err)
1008 		return NULL;
1009 
1010 	bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
1011 	if (!bh)
1012 		return NULL;
1013 	atomic_dec(&transaction->t_outstanding_credits);
1014 	lock_buffer(bh);
1015 	memset(bh->b_data, 0, journal->j_blocksize);
1016 	header = (journal_header_t *)bh->b_data;
1017 	header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
1018 	header->h_blocktype = cpu_to_be32(type);
1019 	header->h_sequence = cpu_to_be32(transaction->t_tid);
1020 	set_buffer_uptodate(bh);
1021 	unlock_buffer(bh);
1022 	BUFFER_TRACE(bh, "return this buffer");
1023 	return bh;
1024 }
1025 
1026 void jbd2_descriptor_block_csum_set(journal_t *j, struct buffer_head *bh)
1027 {
1028 	struct jbd2_journal_block_tail *tail;
1029 	__u32 csum;
1030 
1031 	if (!jbd2_journal_has_csum_v2or3(j))
1032 		return;
1033 
1034 	tail = (struct jbd2_journal_block_tail *)(bh->b_data + j->j_blocksize -
1035 			sizeof(struct jbd2_journal_block_tail));
1036 	tail->t_checksum = 0;
1037 	csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
1038 	tail->t_checksum = cpu_to_be32(csum);
1039 }
1040 
1041 /*
1042  * Return tid of the oldest transaction in the journal and block in the journal
1043  * where the transaction starts.
1044  *
1045  * If the journal is now empty, return which will be the next transaction ID
1046  * we will write and where will that transaction start.
1047  *
1048  * The return value is 0 if journal tail cannot be pushed any further, 1 if
1049  * it can.
1050  */
1051 int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
1052 			      unsigned long *block)
1053 {
1054 	transaction_t *transaction;
1055 	int ret;
1056 
1057 	read_lock(&journal->j_state_lock);
1058 	spin_lock(&journal->j_list_lock);
1059 	transaction = journal->j_checkpoint_transactions;
1060 	if (transaction) {
1061 		*tid = transaction->t_tid;
1062 		*block = transaction->t_log_start;
1063 	} else if ((transaction = journal->j_committing_transaction) != NULL) {
1064 		*tid = transaction->t_tid;
1065 		*block = transaction->t_log_start;
1066 	} else if ((transaction = journal->j_running_transaction) != NULL) {
1067 		*tid = transaction->t_tid;
1068 		*block = journal->j_head;
1069 	} else {
1070 		*tid = journal->j_transaction_sequence;
1071 		*block = journal->j_head;
1072 	}
1073 	ret = tid_gt(*tid, journal->j_tail_sequence);
1074 	spin_unlock(&journal->j_list_lock);
1075 	read_unlock(&journal->j_state_lock);
1076 
1077 	return ret;
1078 }
1079 
1080 /*
1081  * Update information in journal structure and in on disk journal superblock
1082  * about log tail. This function does not check whether information passed in
1083  * really pushes log tail further. It's responsibility of the caller to make
1084  * sure provided log tail information is valid (e.g. by holding
1085  * j_checkpoint_mutex all the time between computing log tail and calling this
1086  * function as is the case with jbd2_cleanup_journal_tail()).
1087  *
1088  * Requires j_checkpoint_mutex
1089  */
1090 int __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
1091 {
1092 	unsigned long freed;
1093 	int ret;
1094 
1095 	BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1096 
1097 	/*
1098 	 * We cannot afford for write to remain in drive's caches since as
1099 	 * soon as we update j_tail, next transaction can start reusing journal
1100 	 * space and if we lose sb update during power failure we'd replay
1101 	 * old transaction with possibly newly overwritten data.
1102 	 */
1103 	ret = jbd2_journal_update_sb_log_tail(journal, tid, block,
1104 					      REQ_SYNC | REQ_FUA);
1105 	if (ret)
1106 		goto out;
1107 
1108 	write_lock(&journal->j_state_lock);
1109 	freed = block - journal->j_tail;
1110 	if (block < journal->j_tail)
1111 		freed += journal->j_last - journal->j_first;
1112 
1113 	trace_jbd2_update_log_tail(journal, tid, block, freed);
1114 	jbd2_debug(1,
1115 		  "Cleaning journal tail from %u to %u (offset %lu), "
1116 		  "freeing %lu\n",
1117 		  journal->j_tail_sequence, tid, block, freed);
1118 
1119 	journal->j_free += freed;
1120 	journal->j_tail_sequence = tid;
1121 	journal->j_tail = block;
1122 	write_unlock(&journal->j_state_lock);
1123 
1124 out:
1125 	return ret;
1126 }
1127 
1128 /*
1129  * This is a variation of __jbd2_update_log_tail which checks for validity of
1130  * provided log tail and locks j_checkpoint_mutex. So it is safe against races
1131  * with other threads updating log tail.
1132  */
1133 void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
1134 {
1135 	mutex_lock_io(&journal->j_checkpoint_mutex);
1136 	if (tid_gt(tid, journal->j_tail_sequence))
1137 		__jbd2_update_log_tail(journal, tid, block);
1138 	mutex_unlock(&journal->j_checkpoint_mutex);
1139 }
1140 
1141 struct jbd2_stats_proc_session {
1142 	journal_t *journal;
1143 	struct transaction_stats_s *stats;
1144 	int start;
1145 	int max;
1146 };
1147 
1148 static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos)
1149 {
1150 	return *pos ? NULL : SEQ_START_TOKEN;
1151 }
1152 
1153 static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
1154 {
1155 	(*pos)++;
1156 	return NULL;
1157 }
1158 
1159 static int jbd2_seq_info_show(struct seq_file *seq, void *v)
1160 {
1161 	struct jbd2_stats_proc_session *s = seq->private;
1162 
1163 	if (v != SEQ_START_TOKEN)
1164 		return 0;
1165 	seq_printf(seq, "%lu transactions (%lu requested), "
1166 		   "each up to %u blocks\n",
1167 		   s->stats->ts_tid, s->stats->ts_requested,
1168 		   s->journal->j_max_transaction_buffers);
1169 	if (s->stats->ts_tid == 0)
1170 		return 0;
1171 	seq_printf(seq, "average: \n  %ums waiting for transaction\n",
1172 	    jiffies_to_msecs(s->stats->run.rs_wait / s->stats->ts_tid));
1173 	seq_printf(seq, "  %ums request delay\n",
1174 	    (s->stats->ts_requested == 0) ? 0 :
1175 	    jiffies_to_msecs(s->stats->run.rs_request_delay /
1176 			     s->stats->ts_requested));
1177 	seq_printf(seq, "  %ums running transaction\n",
1178 	    jiffies_to_msecs(s->stats->run.rs_running / s->stats->ts_tid));
1179 	seq_printf(seq, "  %ums transaction was being locked\n",
1180 	    jiffies_to_msecs(s->stats->run.rs_locked / s->stats->ts_tid));
1181 	seq_printf(seq, "  %ums flushing data (in ordered mode)\n",
1182 	    jiffies_to_msecs(s->stats->run.rs_flushing / s->stats->ts_tid));
1183 	seq_printf(seq, "  %ums logging transaction\n",
1184 	    jiffies_to_msecs(s->stats->run.rs_logging / s->stats->ts_tid));
1185 	seq_printf(seq, "  %lluus average transaction commit time\n",
1186 		   div_u64(s->journal->j_average_commit_time, 1000));
1187 	seq_printf(seq, "  %lu handles per transaction\n",
1188 	    s->stats->run.rs_handle_count / s->stats->ts_tid);
1189 	seq_printf(seq, "  %lu blocks per transaction\n",
1190 	    s->stats->run.rs_blocks / s->stats->ts_tid);
1191 	seq_printf(seq, "  %lu logged blocks per transaction\n",
1192 	    s->stats->run.rs_blocks_logged / s->stats->ts_tid);
1193 	return 0;
1194 }
1195 
1196 static void jbd2_seq_info_stop(struct seq_file *seq, void *v)
1197 {
1198 }
1199 
1200 static const struct seq_operations jbd2_seq_info_ops = {
1201 	.start  = jbd2_seq_info_start,
1202 	.next   = jbd2_seq_info_next,
1203 	.stop   = jbd2_seq_info_stop,
1204 	.show   = jbd2_seq_info_show,
1205 };
1206 
1207 static int jbd2_seq_info_open(struct inode *inode, struct file *file)
1208 {
1209 	journal_t *journal = pde_data(inode);
1210 	struct jbd2_stats_proc_session *s;
1211 	int rc, size;
1212 
1213 	s = kmalloc(sizeof(*s), GFP_KERNEL);
1214 	if (s == NULL)
1215 		return -ENOMEM;
1216 	size = sizeof(struct transaction_stats_s);
1217 	s->stats = kmalloc(size, GFP_KERNEL);
1218 	if (s->stats == NULL) {
1219 		kfree(s);
1220 		return -ENOMEM;
1221 	}
1222 	spin_lock(&journal->j_history_lock);
1223 	memcpy(s->stats, &journal->j_stats, size);
1224 	s->journal = journal;
1225 	spin_unlock(&journal->j_history_lock);
1226 
1227 	rc = seq_open(file, &jbd2_seq_info_ops);
1228 	if (rc == 0) {
1229 		struct seq_file *m = file->private_data;
1230 		m->private = s;
1231 	} else {
1232 		kfree(s->stats);
1233 		kfree(s);
1234 	}
1235 	return rc;
1236 
1237 }
1238 
1239 static int jbd2_seq_info_release(struct inode *inode, struct file *file)
1240 {
1241 	struct seq_file *seq = file->private_data;
1242 	struct jbd2_stats_proc_session *s = seq->private;
1243 	kfree(s->stats);
1244 	kfree(s);
1245 	return seq_release(inode, file);
1246 }
1247 
1248 static const struct proc_ops jbd2_info_proc_ops = {
1249 	.proc_open	= jbd2_seq_info_open,
1250 	.proc_read	= seq_read,
1251 	.proc_lseek	= seq_lseek,
1252 	.proc_release	= jbd2_seq_info_release,
1253 };
1254 
1255 static struct proc_dir_entry *proc_jbd2_stats;
1256 
1257 static void jbd2_stats_proc_init(journal_t *journal)
1258 {
1259 	journal->j_proc_entry = proc_mkdir(journal->j_devname, proc_jbd2_stats);
1260 	if (journal->j_proc_entry) {
1261 		proc_create_data("info", S_IRUGO, journal->j_proc_entry,
1262 				 &jbd2_info_proc_ops, journal);
1263 	}
1264 }
1265 
1266 static void jbd2_stats_proc_exit(journal_t *journal)
1267 {
1268 	remove_proc_entry("info", journal->j_proc_entry);
1269 	remove_proc_entry(journal->j_devname, proc_jbd2_stats);
1270 }
1271 
1272 /* Minimum size of descriptor tag */
1273 static int jbd2_min_tag_size(void)
1274 {
1275 	/*
1276 	 * Tag with 32-bit block numbers does not use last four bytes of the
1277 	 * structure
1278 	 */
1279 	return sizeof(journal_block_tag_t) - 4;
1280 }
1281 
1282 /**
1283  * jbd2_journal_shrink_scan()
1284  * @shrink: shrinker to work on
1285  * @sc: reclaim request to process
1286  *
1287  * Scan the checkpointed buffer on the checkpoint list and release the
1288  * journal_head.
1289  */
1290 static unsigned long jbd2_journal_shrink_scan(struct shrinker *shrink,
1291 					      struct shrink_control *sc)
1292 {
1293 	journal_t *journal = shrink->private_data;
1294 	unsigned long nr_to_scan = sc->nr_to_scan;
1295 	unsigned long nr_shrunk;
1296 	unsigned long count;
1297 
1298 	count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
1299 	trace_jbd2_shrink_scan_enter(journal, sc->nr_to_scan, count);
1300 
1301 	nr_shrunk = jbd2_journal_shrink_checkpoint_list(journal, &nr_to_scan);
1302 
1303 	count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
1304 	trace_jbd2_shrink_scan_exit(journal, nr_to_scan, nr_shrunk, count);
1305 
1306 	return nr_shrunk;
1307 }
1308 
1309 /**
1310  * jbd2_journal_shrink_count()
1311  * @shrink: shrinker to work on
1312  * @sc: reclaim request to process
1313  *
1314  * Count the number of checkpoint buffers on the checkpoint list.
1315  */
1316 static unsigned long jbd2_journal_shrink_count(struct shrinker *shrink,
1317 					       struct shrink_control *sc)
1318 {
1319 	journal_t *journal = shrink->private_data;
1320 	unsigned long count;
1321 
1322 	count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
1323 	trace_jbd2_shrink_count(journal, sc->nr_to_scan, count);
1324 
1325 	return count;
1326 }
1327 
1328 /*
1329  * If the journal init or create aborts, we need to mark the journal
1330  * superblock as being NULL to prevent the journal destroy from writing
1331  * back a bogus superblock.
1332  */
1333 static void journal_fail_superblock(journal_t *journal)
1334 {
1335 	struct buffer_head *bh = journal->j_sb_buffer;
1336 	brelse(bh);
1337 	journal->j_sb_buffer = NULL;
1338 }
1339 
1340 /*
1341  * Check the superblock for a given journal, performing initial
1342  * validation of the format.
1343  */
1344 static int journal_check_superblock(journal_t *journal)
1345 {
1346 	journal_superblock_t *sb = journal->j_superblock;
1347 	int num_fc_blks;
1348 	int err = -EINVAL;
1349 
1350 	if (sb->s_header.h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER) ||
1351 	    sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1352 		printk(KERN_WARNING "JBD2: no valid journal superblock found\n");
1353 		return err;
1354 	}
1355 
1356 	if (be32_to_cpu(sb->s_header.h_blocktype) != JBD2_SUPERBLOCK_V1 &&
1357 	    be32_to_cpu(sb->s_header.h_blocktype) != JBD2_SUPERBLOCK_V2) {
1358 		printk(KERN_WARNING "JBD2: unrecognised superblock format ID\n");
1359 		return err;
1360 	}
1361 
1362 	if (be32_to_cpu(sb->s_maxlen) > journal->j_total_len) {
1363 		printk(KERN_WARNING "JBD2: journal file too short\n");
1364 		return err;
1365 	}
1366 
1367 	if (be32_to_cpu(sb->s_first) == 0 ||
1368 	    be32_to_cpu(sb->s_first) >= journal->j_total_len) {
1369 		printk(KERN_WARNING
1370 			"JBD2: Invalid start block of journal: %u\n",
1371 			be32_to_cpu(sb->s_first));
1372 		return err;
1373 	}
1374 
1375 	/*
1376 	 * If this is a V2 superblock, then we have to check the
1377 	 * features flags on it.
1378 	 */
1379 	if (!jbd2_format_support_feature(journal))
1380 		return 0;
1381 
1382 	if ((sb->s_feature_ro_compat &
1383 			~cpu_to_be32(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
1384 	    (sb->s_feature_incompat &
1385 			~cpu_to_be32(JBD2_KNOWN_INCOMPAT_FEATURES))) {
1386 		printk(KERN_WARNING "JBD2: Unrecognised features on journal\n");
1387 		return err;
1388 	}
1389 
1390 	num_fc_blks = jbd2_has_feature_fast_commit(journal) ?
1391 				jbd2_journal_get_num_fc_blks(sb) : 0;
1392 	if (be32_to_cpu(sb->s_maxlen) < JBD2_MIN_JOURNAL_BLOCKS ||
1393 	    be32_to_cpu(sb->s_maxlen) - JBD2_MIN_JOURNAL_BLOCKS < num_fc_blks) {
1394 		printk(KERN_ERR "JBD2: journal file too short %u,%d\n",
1395 		       be32_to_cpu(sb->s_maxlen), num_fc_blks);
1396 		return err;
1397 	}
1398 
1399 	if (jbd2_has_feature_csum2(journal) &&
1400 	    jbd2_has_feature_csum3(journal)) {
1401 		/* Can't have checksum v2 and v3 at the same time! */
1402 		printk(KERN_ERR "JBD2: Can't enable checksumming v2 and v3 "
1403 		       "at the same time!\n");
1404 		return err;
1405 	}
1406 
1407 	if (jbd2_journal_has_csum_v2or3_feature(journal) &&
1408 	    jbd2_has_feature_checksum(journal)) {
1409 		/* Can't have checksum v1 and v2 on at the same time! */
1410 		printk(KERN_ERR "JBD2: Can't enable checksumming v1 and v2/3 "
1411 		       "at the same time!\n");
1412 		return err;
1413 	}
1414 
1415 	/* Load the checksum driver */
1416 	if (jbd2_journal_has_csum_v2or3_feature(journal)) {
1417 		if (sb->s_checksum_type != JBD2_CRC32C_CHKSUM) {
1418 			printk(KERN_ERR "JBD2: Unknown checksum type\n");
1419 			return err;
1420 		}
1421 
1422 		journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
1423 		if (IS_ERR(journal->j_chksum_driver)) {
1424 			printk(KERN_ERR "JBD2: Cannot load crc32c driver.\n");
1425 			err = PTR_ERR(journal->j_chksum_driver);
1426 			journal->j_chksum_driver = NULL;
1427 			return err;
1428 		}
1429 		/* Check superblock checksum */
1430 		if (sb->s_checksum != jbd2_superblock_csum(journal, sb)) {
1431 			printk(KERN_ERR "JBD2: journal checksum error\n");
1432 			err = -EFSBADCRC;
1433 			return err;
1434 		}
1435 	}
1436 
1437 	return 0;
1438 }
1439 
1440 static int journal_revoke_records_per_block(journal_t *journal)
1441 {
1442 	int record_size;
1443 	int space = journal->j_blocksize - sizeof(jbd2_journal_revoke_header_t);
1444 
1445 	if (jbd2_has_feature_64bit(journal))
1446 		record_size = 8;
1447 	else
1448 		record_size = 4;
1449 
1450 	if (jbd2_journal_has_csum_v2or3(journal))
1451 		space -= sizeof(struct jbd2_journal_block_tail);
1452 	return space / record_size;
1453 }
1454 
1455 /*
1456  * Load the on-disk journal superblock and read the key fields into the
1457  * journal_t.
1458  */
1459 static int journal_load_superblock(journal_t *journal)
1460 {
1461 	int err;
1462 	struct buffer_head *bh;
1463 	journal_superblock_t *sb;
1464 
1465 	bh = getblk_unmovable(journal->j_dev, journal->j_blk_offset,
1466 			      journal->j_blocksize);
1467 	if (bh)
1468 		err = bh_read(bh, 0);
1469 	if (!bh || err < 0) {
1470 		pr_err("%s: Cannot read journal superblock\n", __func__);
1471 		brelse(bh);
1472 		return -EIO;
1473 	}
1474 
1475 	journal->j_sb_buffer = bh;
1476 	sb = (journal_superblock_t *)bh->b_data;
1477 	journal->j_superblock = sb;
1478 	err = journal_check_superblock(journal);
1479 	if (err) {
1480 		journal_fail_superblock(journal);
1481 		return err;
1482 	}
1483 
1484 	journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1485 	journal->j_tail = be32_to_cpu(sb->s_start);
1486 	journal->j_first = be32_to_cpu(sb->s_first);
1487 	journal->j_errno = be32_to_cpu(sb->s_errno);
1488 	journal->j_last = be32_to_cpu(sb->s_maxlen);
1489 
1490 	if (be32_to_cpu(sb->s_maxlen) < journal->j_total_len)
1491 		journal->j_total_len = be32_to_cpu(sb->s_maxlen);
1492 	/* Precompute checksum seed for all metadata */
1493 	if (jbd2_journal_has_csum_v2or3(journal))
1494 		journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid,
1495 						   sizeof(sb->s_uuid));
1496 	journal->j_revoke_records_per_block =
1497 				journal_revoke_records_per_block(journal);
1498 
1499 	if (jbd2_has_feature_fast_commit(journal)) {
1500 		journal->j_fc_last = be32_to_cpu(sb->s_maxlen);
1501 		journal->j_last = journal->j_fc_last -
1502 				  jbd2_journal_get_num_fc_blks(sb);
1503 		journal->j_fc_first = journal->j_last + 1;
1504 		journal->j_fc_off = 0;
1505 	}
1506 
1507 	return 0;
1508 }
1509 
1510 
1511 /*
1512  * Management for journal control blocks: functions to create and
1513  * destroy journal_t structures, and to initialise and read existing
1514  * journal blocks from disk.  */
1515 
1516 /* First: create and setup a journal_t object in memory.  We initialise
1517  * very few fields yet: that has to wait until we have created the
1518  * journal structures from from scratch, or loaded them from disk. */
1519 
1520 static journal_t *journal_init_common(struct block_device *bdev,
1521 			struct block_device *fs_dev,
1522 			unsigned long long start, int len, int blocksize)
1523 {
1524 	static struct lock_class_key jbd2_trans_commit_key;
1525 	journal_t *journal;
1526 	int err;
1527 	int n;
1528 
1529 	journal = kzalloc(sizeof(*journal), GFP_KERNEL);
1530 	if (!journal)
1531 		return ERR_PTR(-ENOMEM);
1532 
1533 	journal->j_blocksize = blocksize;
1534 	journal->j_dev = bdev;
1535 	journal->j_fs_dev = fs_dev;
1536 	journal->j_blk_offset = start;
1537 	journal->j_total_len = len;
1538 
1539 	err = journal_load_superblock(journal);
1540 	if (err)
1541 		goto err_cleanup;
1542 
1543 	init_waitqueue_head(&journal->j_wait_transaction_locked);
1544 	init_waitqueue_head(&journal->j_wait_done_commit);
1545 	init_waitqueue_head(&journal->j_wait_commit);
1546 	init_waitqueue_head(&journal->j_wait_updates);
1547 	init_waitqueue_head(&journal->j_wait_reserved);
1548 	init_waitqueue_head(&journal->j_fc_wait);
1549 	mutex_init(&journal->j_abort_mutex);
1550 	mutex_init(&journal->j_barrier);
1551 	mutex_init(&journal->j_checkpoint_mutex);
1552 	spin_lock_init(&journal->j_revoke_lock);
1553 	spin_lock_init(&journal->j_list_lock);
1554 	spin_lock_init(&journal->j_history_lock);
1555 	rwlock_init(&journal->j_state_lock);
1556 
1557 	journal->j_commit_interval = (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE);
1558 	journal->j_min_batch_time = 0;
1559 	journal->j_max_batch_time = 15000; /* 15ms */
1560 	atomic_set(&journal->j_reserved_credits, 0);
1561 	lockdep_init_map(&journal->j_trans_commit_map, "jbd2_handle",
1562 			 &jbd2_trans_commit_key, 0);
1563 
1564 	/* The journal is marked for error until we succeed with recovery! */
1565 	journal->j_flags = JBD2_ABORT;
1566 
1567 	/* Set up a default-sized revoke table for the new mount. */
1568 	err = jbd2_journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
1569 	if (err)
1570 		goto err_cleanup;
1571 
1572 	/*
1573 	 * journal descriptor can store up to n blocks, we need enough
1574 	 * buffers to write out full descriptor block.
1575 	 */
1576 	err = -ENOMEM;
1577 	n = journal->j_blocksize / jbd2_min_tag_size();
1578 	journal->j_wbufsize = n;
1579 	journal->j_fc_wbuf = NULL;
1580 	journal->j_wbuf = kmalloc_array(n, sizeof(struct buffer_head *),
1581 					GFP_KERNEL);
1582 	if (!journal->j_wbuf)
1583 		goto err_cleanup;
1584 
1585 	err = percpu_counter_init(&journal->j_checkpoint_jh_count, 0,
1586 				  GFP_KERNEL);
1587 	if (err)
1588 		goto err_cleanup;
1589 
1590 	journal->j_shrink_transaction = NULL;
1591 
1592 	journal->j_shrinker = shrinker_alloc(0, "jbd2-journal:(%u:%u)",
1593 					     MAJOR(bdev->bd_dev),
1594 					     MINOR(bdev->bd_dev));
1595 	if (!journal->j_shrinker) {
1596 		err = -ENOMEM;
1597 		goto err_cleanup;
1598 	}
1599 
1600 	journal->j_shrinker->scan_objects = jbd2_journal_shrink_scan;
1601 	journal->j_shrinker->count_objects = jbd2_journal_shrink_count;
1602 	journal->j_shrinker->batch = journal->j_max_transaction_buffers;
1603 	journal->j_shrinker->private_data = journal;
1604 
1605 	shrinker_register(journal->j_shrinker);
1606 
1607 	return journal;
1608 
1609 err_cleanup:
1610 	percpu_counter_destroy(&journal->j_checkpoint_jh_count);
1611 	if (journal->j_chksum_driver)
1612 		crypto_free_shash(journal->j_chksum_driver);
1613 	kfree(journal->j_wbuf);
1614 	jbd2_journal_destroy_revoke(journal);
1615 	journal_fail_superblock(journal);
1616 	kfree(journal);
1617 	return ERR_PTR(err);
1618 }
1619 
1620 /* jbd2_journal_init_dev and jbd2_journal_init_inode:
1621  *
1622  * Create a journal structure assigned some fixed set of disk blocks to
1623  * the journal.  We don't actually touch those disk blocks yet, but we
1624  * need to set up all of the mapping information to tell the journaling
1625  * system where the journal blocks are.
1626  *
1627  */
1628 
1629 /**
1630  *  journal_t * jbd2_journal_init_dev() - creates and initialises a journal structure
1631  *  @bdev: Block device on which to create the journal
1632  *  @fs_dev: Device which hold journalled filesystem for this journal.
1633  *  @start: Block nr Start of journal.
1634  *  @len:  Length of the journal in blocks.
1635  *  @blocksize: blocksize of journalling device
1636  *
1637  *  Returns: a newly created journal_t *
1638  *
1639  *  jbd2_journal_init_dev creates a journal which maps a fixed contiguous
1640  *  range of blocks on an arbitrary block device.
1641  *
1642  */
1643 journal_t *jbd2_journal_init_dev(struct block_device *bdev,
1644 			struct block_device *fs_dev,
1645 			unsigned long long start, int len, int blocksize)
1646 {
1647 	journal_t *journal;
1648 
1649 	journal = journal_init_common(bdev, fs_dev, start, len, blocksize);
1650 	if (IS_ERR(journal))
1651 		return ERR_CAST(journal);
1652 
1653 	snprintf(journal->j_devname, sizeof(journal->j_devname),
1654 		 "%pg", journal->j_dev);
1655 	strreplace(journal->j_devname, '/', '!');
1656 	jbd2_stats_proc_init(journal);
1657 
1658 	return journal;
1659 }
1660 
1661 /**
1662  *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
1663  *  @inode: An inode to create the journal in
1664  *
1665  * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
1666  * the journal.  The inode must exist already, must support bmap() and
1667  * must have all data blocks preallocated.
1668  */
1669 journal_t *jbd2_journal_init_inode(struct inode *inode)
1670 {
1671 	journal_t *journal;
1672 	sector_t blocknr;
1673 	int err = 0;
1674 
1675 	blocknr = 0;
1676 	err = bmap(inode, &blocknr);
1677 	if (err || !blocknr) {
1678 		pr_err("%s: Cannot locate journal superblock\n", __func__);
1679 		return err ? ERR_PTR(err) : ERR_PTR(-EINVAL);
1680 	}
1681 
1682 	jbd2_debug(1, "JBD2: inode %s/%ld, size %lld, bits %d, blksize %ld\n",
1683 		  inode->i_sb->s_id, inode->i_ino, (long long) inode->i_size,
1684 		  inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
1685 
1686 	journal = journal_init_common(inode->i_sb->s_bdev, inode->i_sb->s_bdev,
1687 			blocknr, inode->i_size >> inode->i_sb->s_blocksize_bits,
1688 			inode->i_sb->s_blocksize);
1689 	if (IS_ERR(journal))
1690 		return ERR_CAST(journal);
1691 
1692 	journal->j_inode = inode;
1693 	snprintf(journal->j_devname, sizeof(journal->j_devname),
1694 		 "%pg-%lu", journal->j_dev, journal->j_inode->i_ino);
1695 	strreplace(journal->j_devname, '/', '!');
1696 	jbd2_stats_proc_init(journal);
1697 
1698 	return journal;
1699 }
1700 
1701 /*
1702  * Given a journal_t structure, initialise the various fields for
1703  * startup of a new journaling session.  We use this both when creating
1704  * a journal, and after recovering an old journal to reset it for
1705  * subsequent use.
1706  */
1707 
1708 static int journal_reset(journal_t *journal)
1709 {
1710 	journal_superblock_t *sb = journal->j_superblock;
1711 	unsigned long long first, last;
1712 
1713 	first = be32_to_cpu(sb->s_first);
1714 	last = be32_to_cpu(sb->s_maxlen);
1715 	if (first + JBD2_MIN_JOURNAL_BLOCKS > last + 1) {
1716 		printk(KERN_ERR "JBD2: Journal too short (blocks %llu-%llu).\n",
1717 		       first, last);
1718 		journal_fail_superblock(journal);
1719 		return -EINVAL;
1720 	}
1721 
1722 	journal->j_first = first;
1723 	journal->j_last = last;
1724 
1725 	if (journal->j_head != 0 && journal->j_flags & JBD2_CYCLE_RECORD) {
1726 		/*
1727 		 * Disable the cycled recording mode if the journal head block
1728 		 * number is not correct.
1729 		 */
1730 		if (journal->j_head < first || journal->j_head >= last) {
1731 			printk(KERN_WARNING "JBD2: Incorrect Journal head block %lu, "
1732 			       "disable journal_cycle_record\n",
1733 			       journal->j_head);
1734 			journal->j_head = journal->j_first;
1735 		}
1736 	} else {
1737 		journal->j_head = journal->j_first;
1738 	}
1739 	journal->j_tail = journal->j_head;
1740 	journal->j_free = journal->j_last - journal->j_first;
1741 
1742 	journal->j_tail_sequence = journal->j_transaction_sequence;
1743 	journal->j_commit_sequence = journal->j_transaction_sequence - 1;
1744 	journal->j_commit_request = journal->j_commit_sequence;
1745 
1746 	journal->j_max_transaction_buffers = jbd2_journal_get_max_txn_bufs(journal);
1747 
1748 	/*
1749 	 * Now that journal recovery is done, turn fast commits off here. This
1750 	 * way, if fast commit was enabled before the crash but if now FS has
1751 	 * disabled it, we don't enable fast commits.
1752 	 */
1753 	jbd2_clear_feature_fast_commit(journal);
1754 
1755 	/*
1756 	 * As a special case, if the on-disk copy is already marked as needing
1757 	 * no recovery (s_start == 0), then we can safely defer the superblock
1758 	 * update until the next commit by setting JBD2_FLUSHED.  This avoids
1759 	 * attempting a write to a potential-readonly device.
1760 	 */
1761 	if (sb->s_start == 0) {
1762 		jbd2_debug(1, "JBD2: Skipping superblock update on recovered sb "
1763 			"(start %ld, seq %u, errno %d)\n",
1764 			journal->j_tail, journal->j_tail_sequence,
1765 			journal->j_errno);
1766 		journal->j_flags |= JBD2_FLUSHED;
1767 	} else {
1768 		/* Lock here to make assertions happy... */
1769 		mutex_lock_io(&journal->j_checkpoint_mutex);
1770 		/*
1771 		 * Update log tail information. We use REQ_FUA since new
1772 		 * transaction will start reusing journal space and so we
1773 		 * must make sure information about current log tail is on
1774 		 * disk before that.
1775 		 */
1776 		jbd2_journal_update_sb_log_tail(journal,
1777 						journal->j_tail_sequence,
1778 						journal->j_tail,
1779 						REQ_SYNC | REQ_FUA);
1780 		mutex_unlock(&journal->j_checkpoint_mutex);
1781 	}
1782 	return jbd2_journal_start_thread(journal);
1783 }
1784 
1785 /*
1786  * This function expects that the caller will have locked the journal
1787  * buffer head, and will return with it unlocked
1788  */
1789 static int jbd2_write_superblock(journal_t *journal, blk_opf_t write_flags)
1790 {
1791 	struct buffer_head *bh = journal->j_sb_buffer;
1792 	journal_superblock_t *sb = journal->j_superblock;
1793 	int ret = 0;
1794 
1795 	/* Buffer got discarded which means block device got invalidated */
1796 	if (!buffer_mapped(bh)) {
1797 		unlock_buffer(bh);
1798 		return -EIO;
1799 	}
1800 
1801 	trace_jbd2_write_superblock(journal, write_flags);
1802 	if (!(journal->j_flags & JBD2_BARRIER))
1803 		write_flags &= ~(REQ_FUA | REQ_PREFLUSH);
1804 	if (buffer_write_io_error(bh)) {
1805 		/*
1806 		 * Oh, dear.  A previous attempt to write the journal
1807 		 * superblock failed.  This could happen because the
1808 		 * USB device was yanked out.  Or it could happen to
1809 		 * be a transient write error and maybe the block will
1810 		 * be remapped.  Nothing we can do but to retry the
1811 		 * write and hope for the best.
1812 		 */
1813 		printk(KERN_ERR "JBD2: previous I/O error detected "
1814 		       "for journal superblock update for %s.\n",
1815 		       journal->j_devname);
1816 		clear_buffer_write_io_error(bh);
1817 		set_buffer_uptodate(bh);
1818 	}
1819 	if (jbd2_journal_has_csum_v2or3(journal))
1820 		sb->s_checksum = jbd2_superblock_csum(journal, sb);
1821 	get_bh(bh);
1822 	bh->b_end_io = end_buffer_write_sync;
1823 	submit_bh(REQ_OP_WRITE | write_flags, bh);
1824 	wait_on_buffer(bh);
1825 	if (buffer_write_io_error(bh)) {
1826 		clear_buffer_write_io_error(bh);
1827 		set_buffer_uptodate(bh);
1828 		ret = -EIO;
1829 	}
1830 	if (ret) {
1831 		printk(KERN_ERR "JBD2: I/O error when updating journal superblock for %s.\n",
1832 				journal->j_devname);
1833 		if (!is_journal_aborted(journal))
1834 			jbd2_journal_abort(journal, ret);
1835 	}
1836 
1837 	return ret;
1838 }
1839 
1840 /**
1841  * jbd2_journal_update_sb_log_tail() - Update log tail in journal sb on disk.
1842  * @journal: The journal to update.
1843  * @tail_tid: TID of the new transaction at the tail of the log
1844  * @tail_block: The first block of the transaction at the tail of the log
1845  * @write_flags: Flags for the journal sb write operation
1846  *
1847  * Update a journal's superblock information about log tail and write it to
1848  * disk, waiting for the IO to complete.
1849  */
1850 int jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
1851 				    unsigned long tail_block,
1852 				    blk_opf_t write_flags)
1853 {
1854 	journal_superblock_t *sb = journal->j_superblock;
1855 	int ret;
1856 
1857 	if (is_journal_aborted(journal))
1858 		return -EIO;
1859 	if (test_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags)) {
1860 		jbd2_journal_abort(journal, -EIO);
1861 		return -EIO;
1862 	}
1863 
1864 	BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1865 	jbd2_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n",
1866 		  tail_block, tail_tid);
1867 
1868 	lock_buffer(journal->j_sb_buffer);
1869 	sb->s_sequence = cpu_to_be32(tail_tid);
1870 	sb->s_start    = cpu_to_be32(tail_block);
1871 
1872 	ret = jbd2_write_superblock(journal, write_flags);
1873 	if (ret)
1874 		goto out;
1875 
1876 	/* Log is no longer empty */
1877 	write_lock(&journal->j_state_lock);
1878 	WARN_ON(!sb->s_sequence);
1879 	journal->j_flags &= ~JBD2_FLUSHED;
1880 	write_unlock(&journal->j_state_lock);
1881 
1882 out:
1883 	return ret;
1884 }
1885 
1886 /**
1887  * jbd2_mark_journal_empty() - Mark on disk journal as empty.
1888  * @journal: The journal to update.
1889  * @write_flags: Flags for the journal sb write operation
1890  *
1891  * Update a journal's dynamic superblock fields to show that journal is empty.
1892  * Write updated superblock to disk waiting for IO to complete.
1893  */
1894 static void jbd2_mark_journal_empty(journal_t *journal, blk_opf_t write_flags)
1895 {
1896 	journal_superblock_t *sb = journal->j_superblock;
1897 	bool had_fast_commit = false;
1898 
1899 	BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1900 	lock_buffer(journal->j_sb_buffer);
1901 	if (sb->s_start == 0) {		/* Is it already empty? */
1902 		unlock_buffer(journal->j_sb_buffer);
1903 		return;
1904 	}
1905 
1906 	jbd2_debug(1, "JBD2: Marking journal as empty (seq %u)\n",
1907 		  journal->j_tail_sequence);
1908 
1909 	sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
1910 	sb->s_start    = cpu_to_be32(0);
1911 	sb->s_head     = cpu_to_be32(journal->j_head);
1912 	if (jbd2_has_feature_fast_commit(journal)) {
1913 		/*
1914 		 * When journal is clean, no need to commit fast commit flag and
1915 		 * make file system incompatible with older kernels.
1916 		 */
1917 		jbd2_clear_feature_fast_commit(journal);
1918 		had_fast_commit = true;
1919 	}
1920 
1921 	jbd2_write_superblock(journal, write_flags);
1922 
1923 	if (had_fast_commit)
1924 		jbd2_set_feature_fast_commit(journal);
1925 
1926 	/* Log is no longer empty */
1927 	write_lock(&journal->j_state_lock);
1928 	journal->j_flags |= JBD2_FLUSHED;
1929 	write_unlock(&journal->j_state_lock);
1930 }
1931 
1932 /**
1933  * __jbd2_journal_erase() - Discard or zeroout journal blocks (excluding superblock)
1934  * @journal: The journal to erase.
1935  * @flags: A discard/zeroout request is sent for each physically contigous
1936  *	region of the journal. Either JBD2_JOURNAL_FLUSH_DISCARD or
1937  *	JBD2_JOURNAL_FLUSH_ZEROOUT must be set to determine which operation
1938  *	to perform.
1939  *
1940  * Note: JBD2_JOURNAL_FLUSH_ZEROOUT attempts to use hardware offload. Zeroes
1941  * will be explicitly written if no hardware offload is available, see
1942  * blkdev_issue_zeroout for more details.
1943  */
1944 static int __jbd2_journal_erase(journal_t *journal, unsigned int flags)
1945 {
1946 	int err = 0;
1947 	unsigned long block, log_offset; /* logical */
1948 	unsigned long long phys_block, block_start, block_stop; /* physical */
1949 	loff_t byte_start, byte_stop, byte_count;
1950 
1951 	/* flags must be set to either discard or zeroout */
1952 	if ((flags & ~JBD2_JOURNAL_FLUSH_VALID) || !flags ||
1953 			((flags & JBD2_JOURNAL_FLUSH_DISCARD) &&
1954 			(flags & JBD2_JOURNAL_FLUSH_ZEROOUT)))
1955 		return -EINVAL;
1956 
1957 	if ((flags & JBD2_JOURNAL_FLUSH_DISCARD) &&
1958 	    !bdev_max_discard_sectors(journal->j_dev))
1959 		return -EOPNOTSUPP;
1960 
1961 	/*
1962 	 * lookup block mapping and issue discard/zeroout for each
1963 	 * contiguous region
1964 	 */
1965 	log_offset = be32_to_cpu(journal->j_superblock->s_first);
1966 	block_start =  ~0ULL;
1967 	for (block = log_offset; block < journal->j_total_len; block++) {
1968 		err = jbd2_journal_bmap(journal, block, &phys_block);
1969 		if (err) {
1970 			pr_err("JBD2: bad block at offset %lu", block);
1971 			return err;
1972 		}
1973 
1974 		if (block_start == ~0ULL) {
1975 			block_start = phys_block;
1976 			block_stop = block_start - 1;
1977 		}
1978 
1979 		/*
1980 		 * last block not contiguous with current block,
1981 		 * process last contiguous region and return to this block on
1982 		 * next loop
1983 		 */
1984 		if (phys_block != block_stop + 1) {
1985 			block--;
1986 		} else {
1987 			block_stop++;
1988 			/*
1989 			 * if this isn't the last block of journal,
1990 			 * no need to process now because next block may also
1991 			 * be part of this contiguous region
1992 			 */
1993 			if (block != journal->j_total_len - 1)
1994 				continue;
1995 		}
1996 
1997 		/*
1998 		 * end of contiguous region or this is last block of journal,
1999 		 * take care of the region
2000 		 */
2001 		byte_start = block_start * journal->j_blocksize;
2002 		byte_stop = block_stop * journal->j_blocksize;
2003 		byte_count = (block_stop - block_start + 1) *
2004 				journal->j_blocksize;
2005 
2006 		truncate_inode_pages_range(journal->j_dev->bd_inode->i_mapping,
2007 				byte_start, byte_stop);
2008 
2009 		if (flags & JBD2_JOURNAL_FLUSH_DISCARD) {
2010 			err = blkdev_issue_discard(journal->j_dev,
2011 					byte_start >> SECTOR_SHIFT,
2012 					byte_count >> SECTOR_SHIFT,
2013 					GFP_NOFS);
2014 		} else if (flags & JBD2_JOURNAL_FLUSH_ZEROOUT) {
2015 			err = blkdev_issue_zeroout(journal->j_dev,
2016 					byte_start >> SECTOR_SHIFT,
2017 					byte_count >> SECTOR_SHIFT,
2018 					GFP_NOFS, 0);
2019 		}
2020 
2021 		if (unlikely(err != 0)) {
2022 			pr_err("JBD2: (error %d) unable to wipe journal at physical blocks %llu - %llu",
2023 					err, block_start, block_stop);
2024 			return err;
2025 		}
2026 
2027 		/* reset start and stop after processing a region */
2028 		block_start = ~0ULL;
2029 	}
2030 
2031 	return blkdev_issue_flush(journal->j_dev);
2032 }
2033 
2034 /**
2035  * jbd2_journal_update_sb_errno() - Update error in the journal.
2036  * @journal: The journal to update.
2037  *
2038  * Update a journal's errno.  Write updated superblock to disk waiting for IO
2039  * to complete.
2040  */
2041 void jbd2_journal_update_sb_errno(journal_t *journal)
2042 {
2043 	journal_superblock_t *sb = journal->j_superblock;
2044 	int errcode;
2045 
2046 	lock_buffer(journal->j_sb_buffer);
2047 	errcode = journal->j_errno;
2048 	if (errcode == -ESHUTDOWN)
2049 		errcode = 0;
2050 	jbd2_debug(1, "JBD2: updating superblock error (errno %d)\n", errcode);
2051 	sb->s_errno    = cpu_to_be32(errcode);
2052 
2053 	jbd2_write_superblock(journal, REQ_SYNC | REQ_FUA);
2054 }
2055 EXPORT_SYMBOL(jbd2_journal_update_sb_errno);
2056 
2057 /**
2058  * jbd2_journal_load() - Read journal from disk.
2059  * @journal: Journal to act on.
2060  *
2061  * Given a journal_t structure which tells us which disk blocks contain
2062  * a journal, read the journal from disk to initialise the in-memory
2063  * structures.
2064  */
2065 int jbd2_journal_load(journal_t *journal)
2066 {
2067 	int err;
2068 	journal_superblock_t *sb = journal->j_superblock;
2069 
2070 	/*
2071 	 * Create a slab for this blocksize
2072 	 */
2073 	err = jbd2_journal_create_slab(be32_to_cpu(sb->s_blocksize));
2074 	if (err)
2075 		return err;
2076 
2077 	/* Let the recovery code check whether it needs to recover any
2078 	 * data from the journal. */
2079 	err = jbd2_journal_recover(journal);
2080 	if (err) {
2081 		pr_warn("JBD2: journal recovery failed\n");
2082 		return err;
2083 	}
2084 
2085 	if (journal->j_failed_commit) {
2086 		printk(KERN_ERR "JBD2: journal transaction %u on %s "
2087 		       "is corrupt.\n", journal->j_failed_commit,
2088 		       journal->j_devname);
2089 		return -EFSCORRUPTED;
2090 	}
2091 	/*
2092 	 * clear JBD2_ABORT flag initialized in journal_init_common
2093 	 * here to update log tail information with the newest seq.
2094 	 */
2095 	journal->j_flags &= ~JBD2_ABORT;
2096 
2097 	/* OK, we've finished with the dynamic journal bits:
2098 	 * reinitialise the dynamic contents of the superblock in memory
2099 	 * and reset them on disk. */
2100 	err = journal_reset(journal);
2101 	if (err) {
2102 		pr_warn("JBD2: journal reset failed\n");
2103 		return err;
2104 	}
2105 
2106 	journal->j_flags |= JBD2_LOADED;
2107 	return 0;
2108 }
2109 
2110 /**
2111  * jbd2_journal_destroy() - Release a journal_t structure.
2112  * @journal: Journal to act on.
2113  *
2114  * Release a journal_t structure once it is no longer in use by the
2115  * journaled object.
2116  * Return <0 if we couldn't clean up the journal.
2117  */
2118 int jbd2_journal_destroy(journal_t *journal)
2119 {
2120 	int err = 0;
2121 
2122 	/* Wait for the commit thread to wake up and die. */
2123 	journal_kill_thread(journal);
2124 
2125 	/* Force a final log commit */
2126 	if (journal->j_running_transaction)
2127 		jbd2_journal_commit_transaction(journal);
2128 
2129 	/* Force any old transactions to disk */
2130 
2131 	/* Totally anal locking here... */
2132 	spin_lock(&journal->j_list_lock);
2133 	while (journal->j_checkpoint_transactions != NULL) {
2134 		spin_unlock(&journal->j_list_lock);
2135 		mutex_lock_io(&journal->j_checkpoint_mutex);
2136 		err = jbd2_log_do_checkpoint(journal);
2137 		mutex_unlock(&journal->j_checkpoint_mutex);
2138 		/*
2139 		 * If checkpointing failed, just free the buffers to avoid
2140 		 * looping forever
2141 		 */
2142 		if (err) {
2143 			jbd2_journal_destroy_checkpoint(journal);
2144 			spin_lock(&journal->j_list_lock);
2145 			break;
2146 		}
2147 		spin_lock(&journal->j_list_lock);
2148 	}
2149 
2150 	J_ASSERT(journal->j_running_transaction == NULL);
2151 	J_ASSERT(journal->j_committing_transaction == NULL);
2152 	J_ASSERT(journal->j_checkpoint_transactions == NULL);
2153 	spin_unlock(&journal->j_list_lock);
2154 
2155 	/*
2156 	 * OK, all checkpoint transactions have been checked, now check the
2157 	 * write out io error flag and abort the journal if some buffer failed
2158 	 * to write back to the original location, otherwise the filesystem
2159 	 * may become inconsistent.
2160 	 */
2161 	if (!is_journal_aborted(journal) &&
2162 	    test_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags))
2163 		jbd2_journal_abort(journal, -EIO);
2164 
2165 	if (journal->j_sb_buffer) {
2166 		if (!is_journal_aborted(journal)) {
2167 			mutex_lock_io(&journal->j_checkpoint_mutex);
2168 
2169 			write_lock(&journal->j_state_lock);
2170 			journal->j_tail_sequence =
2171 				++journal->j_transaction_sequence;
2172 			write_unlock(&journal->j_state_lock);
2173 
2174 			jbd2_mark_journal_empty(journal,
2175 					REQ_SYNC | REQ_PREFLUSH | REQ_FUA);
2176 			mutex_unlock(&journal->j_checkpoint_mutex);
2177 		} else
2178 			err = -EIO;
2179 		brelse(journal->j_sb_buffer);
2180 	}
2181 
2182 	if (journal->j_shrinker) {
2183 		percpu_counter_destroy(&journal->j_checkpoint_jh_count);
2184 		shrinker_free(journal->j_shrinker);
2185 	}
2186 	if (journal->j_proc_entry)
2187 		jbd2_stats_proc_exit(journal);
2188 	iput(journal->j_inode);
2189 	if (journal->j_revoke)
2190 		jbd2_journal_destroy_revoke(journal);
2191 	if (journal->j_chksum_driver)
2192 		crypto_free_shash(journal->j_chksum_driver);
2193 	kfree(journal->j_fc_wbuf);
2194 	kfree(journal->j_wbuf);
2195 	kfree(journal);
2196 
2197 	return err;
2198 }
2199 
2200 
2201 /**
2202  * jbd2_journal_check_used_features() - Check if features specified are used.
2203  * @journal: Journal to check.
2204  * @compat: bitmask of compatible features
2205  * @ro: bitmask of features that force read-only mount
2206  * @incompat: bitmask of incompatible features
2207  *
2208  * Check whether the journal uses all of a given set of
2209  * features.  Return true (non-zero) if it does.
2210  **/
2211 
2212 int jbd2_journal_check_used_features(journal_t *journal, unsigned long compat,
2213 				 unsigned long ro, unsigned long incompat)
2214 {
2215 	journal_superblock_t *sb;
2216 
2217 	if (!compat && !ro && !incompat)
2218 		return 1;
2219 	if (!jbd2_format_support_feature(journal))
2220 		return 0;
2221 
2222 	sb = journal->j_superblock;
2223 
2224 	if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
2225 	    ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
2226 	    ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
2227 		return 1;
2228 
2229 	return 0;
2230 }
2231 
2232 /**
2233  * jbd2_journal_check_available_features() - Check feature set in journalling layer
2234  * @journal: Journal to check.
2235  * @compat: bitmask of compatible features
2236  * @ro: bitmask of features that force read-only mount
2237  * @incompat: bitmask of incompatible features
2238  *
2239  * Check whether the journaling code supports the use of
2240  * all of a given set of features on this journal.  Return true
2241  * (non-zero) if it can. */
2242 
2243 int jbd2_journal_check_available_features(journal_t *journal, unsigned long compat,
2244 				      unsigned long ro, unsigned long incompat)
2245 {
2246 	if (!compat && !ro && !incompat)
2247 		return 1;
2248 
2249 	if (!jbd2_format_support_feature(journal))
2250 		return 0;
2251 
2252 	if ((compat   & JBD2_KNOWN_COMPAT_FEATURES) == compat &&
2253 	    (ro       & JBD2_KNOWN_ROCOMPAT_FEATURES) == ro &&
2254 	    (incompat & JBD2_KNOWN_INCOMPAT_FEATURES) == incompat)
2255 		return 1;
2256 
2257 	return 0;
2258 }
2259 
2260 static int
2261 jbd2_journal_initialize_fast_commit(journal_t *journal)
2262 {
2263 	journal_superblock_t *sb = journal->j_superblock;
2264 	unsigned long long num_fc_blks;
2265 
2266 	num_fc_blks = jbd2_journal_get_num_fc_blks(sb);
2267 	if (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS)
2268 		return -ENOSPC;
2269 
2270 	/* Are we called twice? */
2271 	WARN_ON(journal->j_fc_wbuf != NULL);
2272 	journal->j_fc_wbuf = kmalloc_array(num_fc_blks,
2273 				sizeof(struct buffer_head *), GFP_KERNEL);
2274 	if (!journal->j_fc_wbuf)
2275 		return -ENOMEM;
2276 
2277 	journal->j_fc_wbufsize = num_fc_blks;
2278 	journal->j_fc_last = journal->j_last;
2279 	journal->j_last = journal->j_fc_last - num_fc_blks;
2280 	journal->j_fc_first = journal->j_last + 1;
2281 	journal->j_fc_off = 0;
2282 	journal->j_free = journal->j_last - journal->j_first;
2283 	journal->j_max_transaction_buffers =
2284 		jbd2_journal_get_max_txn_bufs(journal);
2285 
2286 	return 0;
2287 }
2288 
2289 /**
2290  * jbd2_journal_set_features() - Mark a given journal feature in the superblock
2291  * @journal: Journal to act on.
2292  * @compat: bitmask of compatible features
2293  * @ro: bitmask of features that force read-only mount
2294  * @incompat: bitmask of incompatible features
2295  *
2296  * Mark a given journal feature as present on the
2297  * superblock.  Returns true if the requested features could be set.
2298  *
2299  */
2300 
2301 int jbd2_journal_set_features(journal_t *journal, unsigned long compat,
2302 			  unsigned long ro, unsigned long incompat)
2303 {
2304 #define INCOMPAT_FEATURE_ON(f) \
2305 		((incompat & (f)) && !(sb->s_feature_incompat & cpu_to_be32(f)))
2306 #define COMPAT_FEATURE_ON(f) \
2307 		((compat & (f)) && !(sb->s_feature_compat & cpu_to_be32(f)))
2308 	journal_superblock_t *sb;
2309 
2310 	if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
2311 		return 1;
2312 
2313 	if (!jbd2_journal_check_available_features(journal, compat, ro, incompat))
2314 		return 0;
2315 
2316 	/* If enabling v2 checksums, turn on v3 instead */
2317 	if (incompat & JBD2_FEATURE_INCOMPAT_CSUM_V2) {
2318 		incompat &= ~JBD2_FEATURE_INCOMPAT_CSUM_V2;
2319 		incompat |= JBD2_FEATURE_INCOMPAT_CSUM_V3;
2320 	}
2321 
2322 	/* Asking for checksumming v3 and v1?  Only give them v3. */
2323 	if (incompat & JBD2_FEATURE_INCOMPAT_CSUM_V3 &&
2324 	    compat & JBD2_FEATURE_COMPAT_CHECKSUM)
2325 		compat &= ~JBD2_FEATURE_COMPAT_CHECKSUM;
2326 
2327 	jbd2_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
2328 		  compat, ro, incompat);
2329 
2330 	sb = journal->j_superblock;
2331 
2332 	if (incompat & JBD2_FEATURE_INCOMPAT_FAST_COMMIT) {
2333 		if (jbd2_journal_initialize_fast_commit(journal)) {
2334 			pr_err("JBD2: Cannot enable fast commits.\n");
2335 			return 0;
2336 		}
2337 	}
2338 
2339 	/* Load the checksum driver if necessary */
2340 	if ((journal->j_chksum_driver == NULL) &&
2341 	    INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V3)) {
2342 		journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
2343 		if (IS_ERR(journal->j_chksum_driver)) {
2344 			printk(KERN_ERR "JBD2: Cannot load crc32c driver.\n");
2345 			journal->j_chksum_driver = NULL;
2346 			return 0;
2347 		}
2348 		/* Precompute checksum seed for all metadata */
2349 		journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid,
2350 						   sizeof(sb->s_uuid));
2351 	}
2352 
2353 	lock_buffer(journal->j_sb_buffer);
2354 
2355 	/* If enabling v3 checksums, update superblock */
2356 	if (INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V3)) {
2357 		sb->s_checksum_type = JBD2_CRC32C_CHKSUM;
2358 		sb->s_feature_compat &=
2359 			~cpu_to_be32(JBD2_FEATURE_COMPAT_CHECKSUM);
2360 	}
2361 
2362 	/* If enabling v1 checksums, downgrade superblock */
2363 	if (COMPAT_FEATURE_ON(JBD2_FEATURE_COMPAT_CHECKSUM))
2364 		sb->s_feature_incompat &=
2365 			~cpu_to_be32(JBD2_FEATURE_INCOMPAT_CSUM_V2 |
2366 				     JBD2_FEATURE_INCOMPAT_CSUM_V3);
2367 
2368 	sb->s_feature_compat    |= cpu_to_be32(compat);
2369 	sb->s_feature_ro_compat |= cpu_to_be32(ro);
2370 	sb->s_feature_incompat  |= cpu_to_be32(incompat);
2371 	unlock_buffer(journal->j_sb_buffer);
2372 	journal->j_revoke_records_per_block =
2373 				journal_revoke_records_per_block(journal);
2374 
2375 	return 1;
2376 #undef COMPAT_FEATURE_ON
2377 #undef INCOMPAT_FEATURE_ON
2378 }
2379 
2380 /*
2381  * jbd2_journal_clear_features() - Clear a given journal feature in the
2382  * 				    superblock
2383  * @journal: Journal to act on.
2384  * @compat: bitmask of compatible features
2385  * @ro: bitmask of features that force read-only mount
2386  * @incompat: bitmask of incompatible features
2387  *
2388  * Clear a given journal feature as present on the
2389  * superblock.
2390  */
2391 void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
2392 				unsigned long ro, unsigned long incompat)
2393 {
2394 	journal_superblock_t *sb;
2395 
2396 	jbd2_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
2397 		  compat, ro, incompat);
2398 
2399 	sb = journal->j_superblock;
2400 
2401 	sb->s_feature_compat    &= ~cpu_to_be32(compat);
2402 	sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
2403 	sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
2404 	journal->j_revoke_records_per_block =
2405 				journal_revoke_records_per_block(journal);
2406 }
2407 EXPORT_SYMBOL(jbd2_journal_clear_features);
2408 
2409 /**
2410  * jbd2_journal_flush() - Flush journal
2411  * @journal: Journal to act on.
2412  * @flags: optional operation on the journal blocks after the flush (see below)
2413  *
2414  * Flush all data for a given journal to disk and empty the journal.
2415  * Filesystems can use this when remounting readonly to ensure that
2416  * recovery does not need to happen on remount. Optionally, a discard or zeroout
2417  * can be issued on the journal blocks after flushing.
2418  *
2419  * flags:
2420  *	JBD2_JOURNAL_FLUSH_DISCARD: issues discards for the journal blocks
2421  *	JBD2_JOURNAL_FLUSH_ZEROOUT: issues zeroouts for the journal blocks
2422  */
2423 int jbd2_journal_flush(journal_t *journal, unsigned int flags)
2424 {
2425 	int err = 0;
2426 	transaction_t *transaction = NULL;
2427 
2428 	write_lock(&journal->j_state_lock);
2429 
2430 	/* Force everything buffered to the log... */
2431 	if (journal->j_running_transaction) {
2432 		transaction = journal->j_running_transaction;
2433 		__jbd2_log_start_commit(journal, transaction->t_tid);
2434 	} else if (journal->j_committing_transaction)
2435 		transaction = journal->j_committing_transaction;
2436 
2437 	/* Wait for the log commit to complete... */
2438 	if (transaction) {
2439 		tid_t tid = transaction->t_tid;
2440 
2441 		write_unlock(&journal->j_state_lock);
2442 		jbd2_log_wait_commit(journal, tid);
2443 	} else {
2444 		write_unlock(&journal->j_state_lock);
2445 	}
2446 
2447 	/* ...and flush everything in the log out to disk. */
2448 	spin_lock(&journal->j_list_lock);
2449 	while (!err && journal->j_checkpoint_transactions != NULL) {
2450 		spin_unlock(&journal->j_list_lock);
2451 		mutex_lock_io(&journal->j_checkpoint_mutex);
2452 		err = jbd2_log_do_checkpoint(journal);
2453 		mutex_unlock(&journal->j_checkpoint_mutex);
2454 		spin_lock(&journal->j_list_lock);
2455 	}
2456 	spin_unlock(&journal->j_list_lock);
2457 
2458 	if (is_journal_aborted(journal))
2459 		return -EIO;
2460 
2461 	mutex_lock_io(&journal->j_checkpoint_mutex);
2462 	if (!err) {
2463 		err = jbd2_cleanup_journal_tail(journal);
2464 		if (err < 0) {
2465 			mutex_unlock(&journal->j_checkpoint_mutex);
2466 			goto out;
2467 		}
2468 		err = 0;
2469 	}
2470 
2471 	/* Finally, mark the journal as really needing no recovery.
2472 	 * This sets s_start==0 in the underlying superblock, which is
2473 	 * the magic code for a fully-recovered superblock.  Any future
2474 	 * commits of data to the journal will restore the current
2475 	 * s_start value. */
2476 	jbd2_mark_journal_empty(journal, REQ_SYNC | REQ_FUA);
2477 
2478 	if (flags)
2479 		err = __jbd2_journal_erase(journal, flags);
2480 
2481 	mutex_unlock(&journal->j_checkpoint_mutex);
2482 	write_lock(&journal->j_state_lock);
2483 	J_ASSERT(!journal->j_running_transaction);
2484 	J_ASSERT(!journal->j_committing_transaction);
2485 	J_ASSERT(!journal->j_checkpoint_transactions);
2486 	J_ASSERT(journal->j_head == journal->j_tail);
2487 	J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
2488 	write_unlock(&journal->j_state_lock);
2489 out:
2490 	return err;
2491 }
2492 
2493 /**
2494  * jbd2_journal_wipe() - Wipe journal contents
2495  * @journal: Journal to act on.
2496  * @write: flag (see below)
2497  *
2498  * Wipe out all of the contents of a journal, safely.  This will produce
2499  * a warning if the journal contains any valid recovery information.
2500  * Must be called between journal_init_*() and jbd2_journal_load().
2501  *
2502  * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
2503  * we merely suppress recovery.
2504  */
2505 
2506 int jbd2_journal_wipe(journal_t *journal, int write)
2507 {
2508 	int err;
2509 
2510 	J_ASSERT (!(journal->j_flags & JBD2_LOADED));
2511 
2512 	if (!journal->j_tail)
2513 		return 0;
2514 
2515 	printk(KERN_WARNING "JBD2: %s recovery information on journal\n",
2516 		write ? "Clearing" : "Ignoring");
2517 
2518 	err = jbd2_journal_skip_recovery(journal);
2519 	if (write) {
2520 		/* Lock to make assertions happy... */
2521 		mutex_lock_io(&journal->j_checkpoint_mutex);
2522 		jbd2_mark_journal_empty(journal, REQ_SYNC | REQ_FUA);
2523 		mutex_unlock(&journal->j_checkpoint_mutex);
2524 	}
2525 
2526 	return err;
2527 }
2528 
2529 /**
2530  * jbd2_journal_abort () - Shutdown the journal immediately.
2531  * @journal: the journal to shutdown.
2532  * @errno:   an error number to record in the journal indicating
2533  *           the reason for the shutdown.
2534  *
2535  * Perform a complete, immediate shutdown of the ENTIRE
2536  * journal (not of a single transaction).  This operation cannot be
2537  * undone without closing and reopening the journal.
2538  *
2539  * The jbd2_journal_abort function is intended to support higher level error
2540  * recovery mechanisms such as the ext2/ext3 remount-readonly error
2541  * mode.
2542  *
2543  * Journal abort has very specific semantics.  Any existing dirty,
2544  * unjournaled buffers in the main filesystem will still be written to
2545  * disk by bdflush, but the journaling mechanism will be suspended
2546  * immediately and no further transaction commits will be honoured.
2547  *
2548  * Any dirty, journaled buffers will be written back to disk without
2549  * hitting the journal.  Atomicity cannot be guaranteed on an aborted
2550  * filesystem, but we _do_ attempt to leave as much data as possible
2551  * behind for fsck to use for cleanup.
2552  *
2553  * Any attempt to get a new transaction handle on a journal which is in
2554  * ABORT state will just result in an -EROFS error return.  A
2555  * jbd2_journal_stop on an existing handle will return -EIO if we have
2556  * entered abort state during the update.
2557  *
2558  * Recursive transactions are not disturbed by journal abort until the
2559  * final jbd2_journal_stop, which will receive the -EIO error.
2560  *
2561  * Finally, the jbd2_journal_abort call allows the caller to supply an errno
2562  * which will be recorded (if possible) in the journal superblock.  This
2563  * allows a client to record failure conditions in the middle of a
2564  * transaction without having to complete the transaction to record the
2565  * failure to disk.  ext3_error, for example, now uses this
2566  * functionality.
2567  *
2568  */
2569 
2570 void jbd2_journal_abort(journal_t *journal, int errno)
2571 {
2572 	transaction_t *transaction;
2573 
2574 	/*
2575 	 * Lock the aborting procedure until everything is done, this avoid
2576 	 * races between filesystem's error handling flow (e.g. ext4_abort()),
2577 	 * ensure panic after the error info is written into journal's
2578 	 * superblock.
2579 	 */
2580 	mutex_lock(&journal->j_abort_mutex);
2581 	/*
2582 	 * ESHUTDOWN always takes precedence because a file system check
2583 	 * caused by any other journal abort error is not required after
2584 	 * a shutdown triggered.
2585 	 */
2586 	write_lock(&journal->j_state_lock);
2587 	if (journal->j_flags & JBD2_ABORT) {
2588 		int old_errno = journal->j_errno;
2589 
2590 		write_unlock(&journal->j_state_lock);
2591 		if (old_errno != -ESHUTDOWN && errno == -ESHUTDOWN) {
2592 			journal->j_errno = errno;
2593 			jbd2_journal_update_sb_errno(journal);
2594 		}
2595 		mutex_unlock(&journal->j_abort_mutex);
2596 		return;
2597 	}
2598 
2599 	/*
2600 	 * Mark the abort as occurred and start current running transaction
2601 	 * to release all journaled buffer.
2602 	 */
2603 	pr_err("Aborting journal on device %s.\n", journal->j_devname);
2604 
2605 	journal->j_flags |= JBD2_ABORT;
2606 	journal->j_errno = errno;
2607 	transaction = journal->j_running_transaction;
2608 	if (transaction)
2609 		__jbd2_log_start_commit(journal, transaction->t_tid);
2610 	write_unlock(&journal->j_state_lock);
2611 
2612 	/*
2613 	 * Record errno to the journal super block, so that fsck and jbd2
2614 	 * layer could realise that a filesystem check is needed.
2615 	 */
2616 	jbd2_journal_update_sb_errno(journal);
2617 	mutex_unlock(&journal->j_abort_mutex);
2618 }
2619 
2620 /**
2621  * jbd2_journal_errno() - returns the journal's error state.
2622  * @journal: journal to examine.
2623  *
2624  * This is the errno number set with jbd2_journal_abort(), the last
2625  * time the journal was mounted - if the journal was stopped
2626  * without calling abort this will be 0.
2627  *
2628  * If the journal has been aborted on this mount time -EROFS will
2629  * be returned.
2630  */
2631 int jbd2_journal_errno(journal_t *journal)
2632 {
2633 	int err;
2634 
2635 	read_lock(&journal->j_state_lock);
2636 	if (journal->j_flags & JBD2_ABORT)
2637 		err = -EROFS;
2638 	else
2639 		err = journal->j_errno;
2640 	read_unlock(&journal->j_state_lock);
2641 	return err;
2642 }
2643 
2644 /**
2645  * jbd2_journal_clear_err() - clears the journal's error state
2646  * @journal: journal to act on.
2647  *
2648  * An error must be cleared or acked to take a FS out of readonly
2649  * mode.
2650  */
2651 int jbd2_journal_clear_err(journal_t *journal)
2652 {
2653 	int err = 0;
2654 
2655 	write_lock(&journal->j_state_lock);
2656 	if (journal->j_flags & JBD2_ABORT)
2657 		err = -EROFS;
2658 	else
2659 		journal->j_errno = 0;
2660 	write_unlock(&journal->j_state_lock);
2661 	return err;
2662 }
2663 
2664 /**
2665  * jbd2_journal_ack_err() - Ack journal err.
2666  * @journal: journal to act on.
2667  *
2668  * An error must be cleared or acked to take a FS out of readonly
2669  * mode.
2670  */
2671 void jbd2_journal_ack_err(journal_t *journal)
2672 {
2673 	write_lock(&journal->j_state_lock);
2674 	if (journal->j_errno)
2675 		journal->j_flags |= JBD2_ACK_ERR;
2676 	write_unlock(&journal->j_state_lock);
2677 }
2678 
2679 int jbd2_journal_blocks_per_page(struct inode *inode)
2680 {
2681 	return 1 << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
2682 }
2683 
2684 /*
2685  * helper functions to deal with 32 or 64bit block numbers.
2686  */
2687 size_t journal_tag_bytes(journal_t *journal)
2688 {
2689 	size_t sz;
2690 
2691 	if (jbd2_has_feature_csum3(journal))
2692 		return sizeof(journal_block_tag3_t);
2693 
2694 	sz = sizeof(journal_block_tag_t);
2695 
2696 	if (jbd2_has_feature_csum2(journal))
2697 		sz += sizeof(__u16);
2698 
2699 	if (jbd2_has_feature_64bit(journal))
2700 		return sz;
2701 	else
2702 		return sz - sizeof(__u32);
2703 }
2704 
2705 /*
2706  * JBD memory management
2707  *
2708  * These functions are used to allocate block-sized chunks of memory
2709  * used for making copies of buffer_head data.  Very often it will be
2710  * page-sized chunks of data, but sometimes it will be in
2711  * sub-page-size chunks.  (For example, 16k pages on Power systems
2712  * with a 4k block file system.)  For blocks smaller than a page, we
2713  * use a SLAB allocator.  There are slab caches for each block size,
2714  * which are allocated at mount time, if necessary, and we only free
2715  * (all of) the slab caches when/if the jbd2 module is unloaded.  For
2716  * this reason we don't need to a mutex to protect access to
2717  * jbd2_slab[] allocating or releasing memory; only in
2718  * jbd2_journal_create_slab().
2719  */
2720 #define JBD2_MAX_SLABS 8
2721 static struct kmem_cache *jbd2_slab[JBD2_MAX_SLABS];
2722 
2723 static const char *jbd2_slab_names[JBD2_MAX_SLABS] = {
2724 	"jbd2_1k", "jbd2_2k", "jbd2_4k", "jbd2_8k",
2725 	"jbd2_16k", "jbd2_32k", "jbd2_64k", "jbd2_128k"
2726 };
2727 
2728 
2729 static void jbd2_journal_destroy_slabs(void)
2730 {
2731 	int i;
2732 
2733 	for (i = 0; i < JBD2_MAX_SLABS; i++) {
2734 		kmem_cache_destroy(jbd2_slab[i]);
2735 		jbd2_slab[i] = NULL;
2736 	}
2737 }
2738 
2739 static int jbd2_journal_create_slab(size_t size)
2740 {
2741 	static DEFINE_MUTEX(jbd2_slab_create_mutex);
2742 	int i = order_base_2(size) - 10;
2743 	size_t slab_size;
2744 
2745 	if (size == PAGE_SIZE)
2746 		return 0;
2747 
2748 	if (i >= JBD2_MAX_SLABS)
2749 		return -EINVAL;
2750 
2751 	if (unlikely(i < 0))
2752 		i = 0;
2753 	mutex_lock(&jbd2_slab_create_mutex);
2754 	if (jbd2_slab[i]) {
2755 		mutex_unlock(&jbd2_slab_create_mutex);
2756 		return 0;	/* Already created */
2757 	}
2758 
2759 	slab_size = 1 << (i+10);
2760 	jbd2_slab[i] = kmem_cache_create(jbd2_slab_names[i], slab_size,
2761 					 slab_size, 0, NULL);
2762 	mutex_unlock(&jbd2_slab_create_mutex);
2763 	if (!jbd2_slab[i]) {
2764 		printk(KERN_EMERG "JBD2: no memory for jbd2_slab cache\n");
2765 		return -ENOMEM;
2766 	}
2767 	return 0;
2768 }
2769 
2770 static struct kmem_cache *get_slab(size_t size)
2771 {
2772 	int i = order_base_2(size) - 10;
2773 
2774 	BUG_ON(i >= JBD2_MAX_SLABS);
2775 	if (unlikely(i < 0))
2776 		i = 0;
2777 	BUG_ON(jbd2_slab[i] == NULL);
2778 	return jbd2_slab[i];
2779 }
2780 
2781 void *jbd2_alloc(size_t size, gfp_t flags)
2782 {
2783 	void *ptr;
2784 
2785 	BUG_ON(size & (size-1)); /* Must be a power of 2 */
2786 
2787 	if (size < PAGE_SIZE)
2788 		ptr = kmem_cache_alloc(get_slab(size), flags);
2789 	else
2790 		ptr = (void *)__get_free_pages(flags, get_order(size));
2791 
2792 	/* Check alignment; SLUB has gotten this wrong in the past,
2793 	 * and this can lead to user data corruption! */
2794 	BUG_ON(((unsigned long) ptr) & (size-1));
2795 
2796 	return ptr;
2797 }
2798 
2799 void jbd2_free(void *ptr, size_t size)
2800 {
2801 	if (size < PAGE_SIZE)
2802 		kmem_cache_free(get_slab(size), ptr);
2803 	else
2804 		free_pages((unsigned long)ptr, get_order(size));
2805 };
2806 
2807 /*
2808  * Journal_head storage management
2809  */
2810 static struct kmem_cache *jbd2_journal_head_cache;
2811 #ifdef CONFIG_JBD2_DEBUG
2812 static atomic_t nr_journal_heads = ATOMIC_INIT(0);
2813 #endif
2814 
2815 static int __init jbd2_journal_init_journal_head_cache(void)
2816 {
2817 	J_ASSERT(!jbd2_journal_head_cache);
2818 	jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
2819 				sizeof(struct journal_head),
2820 				0,		/* offset */
2821 				SLAB_TEMPORARY | SLAB_TYPESAFE_BY_RCU,
2822 				NULL);		/* ctor */
2823 	if (!jbd2_journal_head_cache) {
2824 		printk(KERN_EMERG "JBD2: no memory for journal_head cache\n");
2825 		return -ENOMEM;
2826 	}
2827 	return 0;
2828 }
2829 
2830 static void jbd2_journal_destroy_journal_head_cache(void)
2831 {
2832 	kmem_cache_destroy(jbd2_journal_head_cache);
2833 	jbd2_journal_head_cache = NULL;
2834 }
2835 
2836 /*
2837  * journal_head splicing and dicing
2838  */
2839 static struct journal_head *journal_alloc_journal_head(void)
2840 {
2841 	struct journal_head *ret;
2842 
2843 #ifdef CONFIG_JBD2_DEBUG
2844 	atomic_inc(&nr_journal_heads);
2845 #endif
2846 	ret = kmem_cache_zalloc(jbd2_journal_head_cache, GFP_NOFS);
2847 	if (!ret) {
2848 		jbd2_debug(1, "out of memory for journal_head\n");
2849 		pr_notice_ratelimited("ENOMEM in %s, retrying.\n", __func__);
2850 		ret = kmem_cache_zalloc(jbd2_journal_head_cache,
2851 				GFP_NOFS | __GFP_NOFAIL);
2852 	}
2853 	if (ret)
2854 		spin_lock_init(&ret->b_state_lock);
2855 	return ret;
2856 }
2857 
2858 static void journal_free_journal_head(struct journal_head *jh)
2859 {
2860 #ifdef CONFIG_JBD2_DEBUG
2861 	atomic_dec(&nr_journal_heads);
2862 	memset(jh, JBD2_POISON_FREE, sizeof(*jh));
2863 #endif
2864 	kmem_cache_free(jbd2_journal_head_cache, jh);
2865 }
2866 
2867 /*
2868  * A journal_head is attached to a buffer_head whenever JBD has an
2869  * interest in the buffer.
2870  *
2871  * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
2872  * is set.  This bit is tested in core kernel code where we need to take
2873  * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
2874  * there.
2875  *
2876  * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
2877  *
2878  * When a buffer has its BH_JBD bit set it is immune from being released by
2879  * core kernel code, mainly via ->b_count.
2880  *
2881  * A journal_head is detached from its buffer_head when the journal_head's
2882  * b_jcount reaches zero. Running transaction (b_transaction) and checkpoint
2883  * transaction (b_cp_transaction) hold their references to b_jcount.
2884  *
2885  * Various places in the kernel want to attach a journal_head to a buffer_head
2886  * _before_ attaching the journal_head to a transaction.  To protect the
2887  * journal_head in this situation, jbd2_journal_add_journal_head elevates the
2888  * journal_head's b_jcount refcount by one.  The caller must call
2889  * jbd2_journal_put_journal_head() to undo this.
2890  *
2891  * So the typical usage would be:
2892  *
2893  *	(Attach a journal_head if needed.  Increments b_jcount)
2894  *	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
2895  *	...
2896  *      (Get another reference for transaction)
2897  *	jbd2_journal_grab_journal_head(bh);
2898  *	jh->b_transaction = xxx;
2899  *	(Put original reference)
2900  *	jbd2_journal_put_journal_head(jh);
2901  */
2902 
2903 /*
2904  * Give a buffer_head a journal_head.
2905  *
2906  * May sleep.
2907  */
2908 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh)
2909 {
2910 	struct journal_head *jh;
2911 	struct journal_head *new_jh = NULL;
2912 
2913 repeat:
2914 	if (!buffer_jbd(bh))
2915 		new_jh = journal_alloc_journal_head();
2916 
2917 	jbd_lock_bh_journal_head(bh);
2918 	if (buffer_jbd(bh)) {
2919 		jh = bh2jh(bh);
2920 	} else {
2921 		J_ASSERT_BH(bh,
2922 			(atomic_read(&bh->b_count) > 0) ||
2923 			(bh->b_folio && bh->b_folio->mapping));
2924 
2925 		if (!new_jh) {
2926 			jbd_unlock_bh_journal_head(bh);
2927 			goto repeat;
2928 		}
2929 
2930 		jh = new_jh;
2931 		new_jh = NULL;		/* We consumed it */
2932 		set_buffer_jbd(bh);
2933 		bh->b_private = jh;
2934 		jh->b_bh = bh;
2935 		get_bh(bh);
2936 		BUFFER_TRACE(bh, "added journal_head");
2937 	}
2938 	jh->b_jcount++;
2939 	jbd_unlock_bh_journal_head(bh);
2940 	if (new_jh)
2941 		journal_free_journal_head(new_jh);
2942 	return bh->b_private;
2943 }
2944 
2945 /*
2946  * Grab a ref against this buffer_head's journal_head.  If it ended up not
2947  * having a journal_head, return NULL
2948  */
2949 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh)
2950 {
2951 	struct journal_head *jh = NULL;
2952 
2953 	jbd_lock_bh_journal_head(bh);
2954 	if (buffer_jbd(bh)) {
2955 		jh = bh2jh(bh);
2956 		jh->b_jcount++;
2957 	}
2958 	jbd_unlock_bh_journal_head(bh);
2959 	return jh;
2960 }
2961 EXPORT_SYMBOL(jbd2_journal_grab_journal_head);
2962 
2963 static void __journal_remove_journal_head(struct buffer_head *bh)
2964 {
2965 	struct journal_head *jh = bh2jh(bh);
2966 
2967 	J_ASSERT_JH(jh, jh->b_transaction == NULL);
2968 	J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
2969 	J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
2970 	J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
2971 	J_ASSERT_BH(bh, buffer_jbd(bh));
2972 	J_ASSERT_BH(bh, jh2bh(jh) == bh);
2973 	BUFFER_TRACE(bh, "remove journal_head");
2974 
2975 	/* Unlink before dropping the lock */
2976 	bh->b_private = NULL;
2977 	jh->b_bh = NULL;	/* debug, really */
2978 	clear_buffer_jbd(bh);
2979 }
2980 
2981 static void journal_release_journal_head(struct journal_head *jh, size_t b_size)
2982 {
2983 	if (jh->b_frozen_data) {
2984 		printk(KERN_WARNING "%s: freeing b_frozen_data\n", __func__);
2985 		jbd2_free(jh->b_frozen_data, b_size);
2986 	}
2987 	if (jh->b_committed_data) {
2988 		printk(KERN_WARNING "%s: freeing b_committed_data\n", __func__);
2989 		jbd2_free(jh->b_committed_data, b_size);
2990 	}
2991 	journal_free_journal_head(jh);
2992 }
2993 
2994 /*
2995  * Drop a reference on the passed journal_head.  If it fell to zero then
2996  * release the journal_head from the buffer_head.
2997  */
2998 void jbd2_journal_put_journal_head(struct journal_head *jh)
2999 {
3000 	struct buffer_head *bh = jh2bh(jh);
3001 
3002 	jbd_lock_bh_journal_head(bh);
3003 	J_ASSERT_JH(jh, jh->b_jcount > 0);
3004 	--jh->b_jcount;
3005 	if (!jh->b_jcount) {
3006 		__journal_remove_journal_head(bh);
3007 		jbd_unlock_bh_journal_head(bh);
3008 		journal_release_journal_head(jh, bh->b_size);
3009 		__brelse(bh);
3010 	} else {
3011 		jbd_unlock_bh_journal_head(bh);
3012 	}
3013 }
3014 EXPORT_SYMBOL(jbd2_journal_put_journal_head);
3015 
3016 /*
3017  * Initialize jbd inode head
3018  */
3019 void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode)
3020 {
3021 	jinode->i_transaction = NULL;
3022 	jinode->i_next_transaction = NULL;
3023 	jinode->i_vfs_inode = inode;
3024 	jinode->i_flags = 0;
3025 	jinode->i_dirty_start = 0;
3026 	jinode->i_dirty_end = 0;
3027 	INIT_LIST_HEAD(&jinode->i_list);
3028 }
3029 
3030 /*
3031  * Function to be called before we start removing inode from memory (i.e.,
3032  * clear_inode() is a fine place to be called from). It removes inode from
3033  * transaction's lists.
3034  */
3035 void jbd2_journal_release_jbd_inode(journal_t *journal,
3036 				    struct jbd2_inode *jinode)
3037 {
3038 	if (!journal)
3039 		return;
3040 restart:
3041 	spin_lock(&journal->j_list_lock);
3042 	/* Is commit writing out inode - we have to wait */
3043 	if (jinode->i_flags & JI_COMMIT_RUNNING) {
3044 		wait_queue_head_t *wq;
3045 		DEFINE_WAIT_BIT(wait, &jinode->i_flags, __JI_COMMIT_RUNNING);
3046 		wq = bit_waitqueue(&jinode->i_flags, __JI_COMMIT_RUNNING);
3047 		prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
3048 		spin_unlock(&journal->j_list_lock);
3049 		schedule();
3050 		finish_wait(wq, &wait.wq_entry);
3051 		goto restart;
3052 	}
3053 
3054 	if (jinode->i_transaction) {
3055 		list_del(&jinode->i_list);
3056 		jinode->i_transaction = NULL;
3057 	}
3058 	spin_unlock(&journal->j_list_lock);
3059 }
3060 
3061 
3062 #ifdef CONFIG_PROC_FS
3063 
3064 #define JBD2_STATS_PROC_NAME "fs/jbd2"
3065 
3066 static void __init jbd2_create_jbd_stats_proc_entry(void)
3067 {
3068 	proc_jbd2_stats = proc_mkdir(JBD2_STATS_PROC_NAME, NULL);
3069 }
3070 
3071 static void __exit jbd2_remove_jbd_stats_proc_entry(void)
3072 {
3073 	if (proc_jbd2_stats)
3074 		remove_proc_entry(JBD2_STATS_PROC_NAME, NULL);
3075 }
3076 
3077 #else
3078 
3079 #define jbd2_create_jbd_stats_proc_entry() do {} while (0)
3080 #define jbd2_remove_jbd_stats_proc_entry() do {} while (0)
3081 
3082 #endif
3083 
3084 struct kmem_cache *jbd2_handle_cache, *jbd2_inode_cache;
3085 
3086 static int __init jbd2_journal_init_inode_cache(void)
3087 {
3088 	J_ASSERT(!jbd2_inode_cache);
3089 	jbd2_inode_cache = KMEM_CACHE(jbd2_inode, 0);
3090 	if (!jbd2_inode_cache) {
3091 		pr_emerg("JBD2: failed to create inode cache\n");
3092 		return -ENOMEM;
3093 	}
3094 	return 0;
3095 }
3096 
3097 static int __init jbd2_journal_init_handle_cache(void)
3098 {
3099 	J_ASSERT(!jbd2_handle_cache);
3100 	jbd2_handle_cache = KMEM_CACHE(jbd2_journal_handle, SLAB_TEMPORARY);
3101 	if (!jbd2_handle_cache) {
3102 		printk(KERN_EMERG "JBD2: failed to create handle cache\n");
3103 		return -ENOMEM;
3104 	}
3105 	return 0;
3106 }
3107 
3108 static void jbd2_journal_destroy_inode_cache(void)
3109 {
3110 	kmem_cache_destroy(jbd2_inode_cache);
3111 	jbd2_inode_cache = NULL;
3112 }
3113 
3114 static void jbd2_journal_destroy_handle_cache(void)
3115 {
3116 	kmem_cache_destroy(jbd2_handle_cache);
3117 	jbd2_handle_cache = NULL;
3118 }
3119 
3120 /*
3121  * Module startup and shutdown
3122  */
3123 
3124 static int __init journal_init_caches(void)
3125 {
3126 	int ret;
3127 
3128 	ret = jbd2_journal_init_revoke_record_cache();
3129 	if (ret == 0)
3130 		ret = jbd2_journal_init_revoke_table_cache();
3131 	if (ret == 0)
3132 		ret = jbd2_journal_init_journal_head_cache();
3133 	if (ret == 0)
3134 		ret = jbd2_journal_init_handle_cache();
3135 	if (ret == 0)
3136 		ret = jbd2_journal_init_inode_cache();
3137 	if (ret == 0)
3138 		ret = jbd2_journal_init_transaction_cache();
3139 	return ret;
3140 }
3141 
3142 static void jbd2_journal_destroy_caches(void)
3143 {
3144 	jbd2_journal_destroy_revoke_record_cache();
3145 	jbd2_journal_destroy_revoke_table_cache();
3146 	jbd2_journal_destroy_journal_head_cache();
3147 	jbd2_journal_destroy_handle_cache();
3148 	jbd2_journal_destroy_inode_cache();
3149 	jbd2_journal_destroy_transaction_cache();
3150 	jbd2_journal_destroy_slabs();
3151 }
3152 
3153 static int __init journal_init(void)
3154 {
3155 	int ret;
3156 
3157 	BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
3158 
3159 	ret = journal_init_caches();
3160 	if (ret == 0) {
3161 		jbd2_create_jbd_stats_proc_entry();
3162 	} else {
3163 		jbd2_journal_destroy_caches();
3164 	}
3165 	return ret;
3166 }
3167 
3168 static void __exit journal_exit(void)
3169 {
3170 #ifdef CONFIG_JBD2_DEBUG
3171 	int n = atomic_read(&nr_journal_heads);
3172 	if (n)
3173 		printk(KERN_ERR "JBD2: leaked %d journal_heads!\n", n);
3174 #endif
3175 	jbd2_remove_jbd_stats_proc_entry();
3176 	jbd2_journal_destroy_caches();
3177 }
3178 
3179 MODULE_LICENSE("GPL");
3180 module_init(journal_init);
3181 module_exit(journal_exit);
3182 
3183