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Dave Kleikamp470decc2006-10-11 01:20:57 -07001/*
Uwe Kleine-König58862692007-05-09 07:51:49 +02002 * linux/fs/jbd2/checkpoint.c
Dave Kleikamp470decc2006-10-11 01:20:57 -07003 *
4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
5 *
6 * Copyright 1999 Red Hat Software --- All Rights Reserved
7 *
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
11 *
12 * Checkpoint routines for the generic filesystem journaling code.
13 * Part of the ext2fs journaling system.
14 *
15 * Checkpointing is the process of ensuring that a section of the log is
16 * committed fully to disk, so that that portion of the log can be
17 * reused.
18 */
19
20#include <linux/time.h>
21#include <linux/fs.h>
Mingming Caof7f4bcc2006-10-11 01:20:59 -070022#include <linux/jbd2.h>
Dave Kleikamp470decc2006-10-11 01:20:57 -070023#include <linux/errno.h>
24#include <linux/slab.h>
Theodore Ts'occ3e1be2009-12-23 06:52:08 -050025#include <linux/blkdev.h>
Theodore Ts'o879c5e62009-06-17 11:47:48 -040026#include <trace/events/jbd2.h>
Dave Kleikamp470decc2006-10-11 01:20:57 -070027
28/*
29 * Unlink a buffer from a transaction checkpoint list.
30 *
31 * Called with j_list_lock held.
32 */
33static inline void __buffer_unlink_first(struct journal_head *jh)
34{
35 transaction_t *transaction = jh->b_cp_transaction;
36
37 jh->b_cpnext->b_cpprev = jh->b_cpprev;
38 jh->b_cpprev->b_cpnext = jh->b_cpnext;
39 if (transaction->t_checkpoint_list == jh) {
40 transaction->t_checkpoint_list = jh->b_cpnext;
41 if (transaction->t_checkpoint_list == jh)
42 transaction->t_checkpoint_list = NULL;
43 }
44}
45
46/*
47 * Unlink a buffer from a transaction checkpoint(io) list.
48 *
49 * Called with j_list_lock held.
50 */
51static inline void __buffer_unlink(struct journal_head *jh)
52{
53 transaction_t *transaction = jh->b_cp_transaction;
54
55 __buffer_unlink_first(jh);
56 if (transaction->t_checkpoint_io_list == jh) {
57 transaction->t_checkpoint_io_list = jh->b_cpnext;
58 if (transaction->t_checkpoint_io_list == jh)
59 transaction->t_checkpoint_io_list = NULL;
60 }
61}
62
63/*
64 * Move a buffer from the checkpoint list to the checkpoint io list
65 *
66 * Called with j_list_lock held
67 */
68static inline void __buffer_relink_io(struct journal_head *jh)
69{
70 transaction_t *transaction = jh->b_cp_transaction;
71
72 __buffer_unlink_first(jh);
73
74 if (!transaction->t_checkpoint_io_list) {
75 jh->b_cpnext = jh->b_cpprev = jh;
76 } else {
77 jh->b_cpnext = transaction->t_checkpoint_io_list;
78 jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
79 jh->b_cpprev->b_cpnext = jh;
80 jh->b_cpnext->b_cpprev = jh;
81 }
82 transaction->t_checkpoint_io_list = jh;
83}
84
85/*
86 * Try to release a checkpointed buffer from its transaction.
87 * Returns 1 if we released it and 2 if we also released the
88 * whole transaction.
89 *
90 * Requires j_list_lock
91 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
92 */
93static int __try_to_free_cp_buf(struct journal_head *jh)
94{
95 int ret = 0;
96 struct buffer_head *bh = jh2bh(jh);
97
Hidehiro Kawai44519fa2008-10-10 20:29:13 -040098 if (jh->b_jlist == BJ_None && !buffer_locked(bh) &&
99 !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
Jan Karade1b7942011-06-13 15:38:22 -0400100 /*
101 * Get our reference so that bh cannot be freed before
102 * we unlock it
103 */
104 get_bh(bh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700105 JBUFFER_TRACE(jh, "remove from checkpoint list");
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700106 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700107 jbd_unlock_bh_state(bh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700108 BUFFER_TRACE(bh, "release");
109 __brelse(bh);
110 } else {
111 jbd_unlock_bh_state(bh);
112 }
113 return ret;
114}
115
116/*
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700117 * __jbd2_log_wait_for_space: wait until there is space in the journal.
Dave Kleikamp470decc2006-10-11 01:20:57 -0700118 *
119 * Called under j-state_lock *only*. It will be unlocked if we have to wait
120 * for a checkpoint to free up some space in the log.
121 */
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700122void __jbd2_log_wait_for_space(journal_t *journal)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700123{
Theodore Ts'o8c3f25d2008-11-06 22:38:07 -0500124 int nblocks, space_left;
Theodore Ts'oa931da62010-08-03 21:35:12 -0400125 /* assert_spin_locked(&journal->j_state_lock); */
Dave Kleikamp470decc2006-10-11 01:20:57 -0700126
127 nblocks = jbd_space_needed(journal);
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700128 while (__jbd2_log_space_left(journal) < nblocks) {
129 if (journal->j_flags & JBD2_ABORT)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700130 return;
Theodore Ts'oa931da62010-08-03 21:35:12 -0400131 write_unlock(&journal->j_state_lock);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700132 mutex_lock(&journal->j_checkpoint_mutex);
133
134 /*
135 * Test again, another process may have checkpointed while we
Duane Griffin23f8b792008-10-08 23:28:31 -0400136 * were waiting for the checkpoint lock. If there are no
Theodore Ts'o8c3f25d2008-11-06 22:38:07 -0500137 * transactions ready to be checkpointed, try to recover
138 * journal space by calling cleanup_journal_tail(), and if
139 * that doesn't work, by waiting for the currently committing
140 * transaction to complete. If there is absolutely no way
141 * to make progress, this is either a BUG or corrupted
142 * filesystem, so abort the journal and leave a stack
143 * trace for forensic evidence.
Dave Kleikamp470decc2006-10-11 01:20:57 -0700144 */
Theodore Ts'oa931da62010-08-03 21:35:12 -0400145 write_lock(&journal->j_state_lock);
Duane Griffin23f8b792008-10-08 23:28:31 -0400146 spin_lock(&journal->j_list_lock);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700147 nblocks = jbd_space_needed(journal);
Theodore Ts'o8c3f25d2008-11-06 22:38:07 -0500148 space_left = __jbd2_log_space_left(journal);
149 if (space_left < nblocks) {
Duane Griffin23f8b792008-10-08 23:28:31 -0400150 int chkpt = journal->j_checkpoint_transactions != NULL;
Theodore Ts'o8c3f25d2008-11-06 22:38:07 -0500151 tid_t tid = 0;
Duane Griffin23f8b792008-10-08 23:28:31 -0400152
Theodore Ts'o8c3f25d2008-11-06 22:38:07 -0500153 if (journal->j_committing_transaction)
154 tid = journal->j_committing_transaction->t_tid;
Duane Griffin23f8b792008-10-08 23:28:31 -0400155 spin_unlock(&journal->j_list_lock);
Theodore Ts'oa931da62010-08-03 21:35:12 -0400156 write_unlock(&journal->j_state_lock);
Duane Griffin23f8b792008-10-08 23:28:31 -0400157 if (chkpt) {
158 jbd2_log_do_checkpoint(journal);
Theodore Ts'o8c3f25d2008-11-06 22:38:07 -0500159 } else if (jbd2_cleanup_journal_tail(journal) == 0) {
160 /* We were able to recover space; yay! */
161 ;
162 } else if (tid) {
163 jbd2_log_wait_commit(journal, tid);
Duane Griffin23f8b792008-10-08 23:28:31 -0400164 } else {
Theodore Ts'o8c3f25d2008-11-06 22:38:07 -0500165 printk(KERN_ERR "%s: needed %d blocks and "
166 "only had %d space available\n",
167 __func__, nblocks, space_left);
168 printk(KERN_ERR "%s: no way to get more "
169 "journal space in %s\n", __func__,
170 journal->j_devname);
171 WARN_ON(1);
Duane Griffin23f8b792008-10-08 23:28:31 -0400172 jbd2_journal_abort(journal, 0);
173 }
Theodore Ts'oa931da62010-08-03 21:35:12 -0400174 write_lock(&journal->j_state_lock);
Duane Griffin23f8b792008-10-08 23:28:31 -0400175 } else {
176 spin_unlock(&journal->j_list_lock);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700177 }
178 mutex_unlock(&journal->j_checkpoint_mutex);
179 }
180}
181
182/*
183 * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
184 * The caller must restart a list walk. Wait for someone else to run
185 * jbd_unlock_bh_state().
186 */
187static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
188 __releases(journal->j_list_lock)
189{
190 get_bh(bh);
191 spin_unlock(&journal->j_list_lock);
192 jbd_lock_bh_state(bh);
193 jbd_unlock_bh_state(bh);
194 put_bh(bh);
195}
196
197/*
198 * Clean up transaction's list of buffers submitted for io.
199 * We wait for any pending IO to complete and remove any clean
200 * buffers. Note that we take the buffers in the opposite ordering
201 * from the one in which they were submitted for IO.
202 *
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400203 * Return 0 on success, and return <0 if some buffers have failed
204 * to be written out.
205 *
Dave Kleikamp470decc2006-10-11 01:20:57 -0700206 * Called with j_list_lock held.
207 */
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400208static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700209{
210 struct journal_head *jh;
211 struct buffer_head *bh;
212 tid_t this_tid;
213 int released = 0;
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400214 int ret = 0;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700215
216 this_tid = transaction->t_tid;
217restart:
218 /* Did somebody clean up the transaction in the meanwhile? */
219 if (journal->j_checkpoint_transactions != transaction ||
220 transaction->t_tid != this_tid)
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400221 return ret;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700222 while (!released && transaction->t_checkpoint_io_list) {
223 jh = transaction->t_checkpoint_io_list;
224 bh = jh2bh(jh);
225 if (!jbd_trylock_bh_state(bh)) {
226 jbd_sync_bh(journal, bh);
227 spin_lock(&journal->j_list_lock);
228 goto restart;
229 }
Jan Karade1b7942011-06-13 15:38:22 -0400230 get_bh(bh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700231 if (buffer_locked(bh)) {
Dave Kleikamp470decc2006-10-11 01:20:57 -0700232 spin_unlock(&journal->j_list_lock);
233 jbd_unlock_bh_state(bh);
234 wait_on_buffer(bh);
235 /* the journal_head may have gone by now */
236 BUFFER_TRACE(bh, "brelse");
237 __brelse(bh);
238 spin_lock(&journal->j_list_lock);
239 goto restart;
240 }
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400241 if (unlikely(buffer_write_io_error(bh)))
242 ret = -EIO;
243
Dave Kleikamp470decc2006-10-11 01:20:57 -0700244 /*
245 * Now in whatever state the buffer currently is, we know that
246 * it has been written out and so we can drop it from the list
247 */
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700248 released = __jbd2_journal_remove_checkpoint(jh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700249 jbd_unlock_bh_state(bh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700250 __brelse(bh);
251 }
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400252
253 return ret;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700254}
255
Dave Kleikamp470decc2006-10-11 01:20:57 -0700256static void
Theodore Ts'o1a0d3782008-11-05 00:09:22 -0500257__flush_batch(journal_t *journal, int *batch_count)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700258{
259 int i;
Tao Mad3ad8432011-06-27 12:36:29 -0400260 struct blk_plug plug;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700261
Tao Mad3ad8432011-06-27 12:36:29 -0400262 blk_start_plug(&plug);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200263 for (i = 0; i < *batch_count; i++)
Tao Mad3ad8432011-06-27 12:36:29 -0400264 write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE_SYNC);
265 blk_finish_plug(&plug);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200266
Dave Kleikamp470decc2006-10-11 01:20:57 -0700267 for (i = 0; i < *batch_count; i++) {
Theodore Ts'o1a0d3782008-11-05 00:09:22 -0500268 struct buffer_head *bh = journal->j_chkpt_bhs[i];
Dave Kleikamp470decc2006-10-11 01:20:57 -0700269 clear_buffer_jwrite(bh);
270 BUFFER_TRACE(bh, "brelse");
271 __brelse(bh);
272 }
273 *batch_count = 0;
274}
275
276/*
277 * Try to flush one buffer from the checkpoint list to disk.
278 *
279 * Return 1 if something happened which requires us to abort the current
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400280 * scan of the checkpoint list. Return <0 if the buffer has failed to
281 * be written out.
Dave Kleikamp470decc2006-10-11 01:20:57 -0700282 *
283 * Called with j_list_lock held and drops it if 1 is returned
284 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
285 */
286static int __process_buffer(journal_t *journal, struct journal_head *jh,
Theodore Ts'o1a0d3782008-11-05 00:09:22 -0500287 int *batch_count, transaction_t *transaction)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700288{
289 struct buffer_head *bh = jh2bh(jh);
290 int ret = 0;
291
292 if (buffer_locked(bh)) {
Jan Karade1b7942011-06-13 15:38:22 -0400293 get_bh(bh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700294 spin_unlock(&journal->j_list_lock);
295 jbd_unlock_bh_state(bh);
296 wait_on_buffer(bh);
297 /* the journal_head may have gone by now */
298 BUFFER_TRACE(bh, "brelse");
299 __brelse(bh);
300 ret = 1;
301 } else if (jh->b_transaction != NULL) {
302 transaction_t *t = jh->b_transaction;
303 tid_t tid = t->t_tid;
304
Johann Lombardi8e85fb32008-01-28 23:58:27 -0500305 transaction->t_chp_stats.cs_forced_to_close++;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700306 spin_unlock(&journal->j_list_lock);
307 jbd_unlock_bh_state(bh);
Theodore Ts'o5c2178e2010-10-27 21:30:04 -0400308 if (unlikely(journal->j_flags & JBD2_UNMOUNT))
309 /*
310 * The journal thread is dead; so starting and
311 * waiting for a commit to finish will cause
312 * us to wait for a _very_ long time.
313 */
314 printk(KERN_ERR "JBD2: %s: "
315 "Waiting for Godot: block %llu\n",
316 journal->j_devname,
317 (unsigned long long) bh->b_blocknr);
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700318 jbd2_log_start_commit(journal, tid);
319 jbd2_log_wait_commit(journal, tid);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700320 ret = 1;
321 } else if (!buffer_dirty(bh)) {
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400322 ret = 1;
323 if (unlikely(buffer_write_io_error(bh)))
324 ret = -EIO;
Jan Karade1b7942011-06-13 15:38:22 -0400325 get_bh(bh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700326 J_ASSERT_JH(jh, !buffer_jbddirty(bh));
327 BUFFER_TRACE(bh, "remove from checkpoint");
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700328 __jbd2_journal_remove_checkpoint(jh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700329 spin_unlock(&journal->j_list_lock);
330 jbd_unlock_bh_state(bh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700331 __brelse(bh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700332 } else {
333 /*
334 * Important: we are about to write the buffer, and
335 * possibly block, while still holding the journal lock.
336 * We cannot afford to let the transaction logic start
337 * messing around with this buffer before we write it to
338 * disk, as that would break recoverability.
339 */
340 BUFFER_TRACE(bh, "queue");
341 get_bh(bh);
342 J_ASSERT_BH(bh, !buffer_jwrite(bh));
343 set_buffer_jwrite(bh);
Theodore Ts'o1a0d3782008-11-05 00:09:22 -0500344 journal->j_chkpt_bhs[*batch_count] = bh;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700345 __buffer_relink_io(jh);
346 jbd_unlock_bh_state(bh);
Johann Lombardi8e85fb32008-01-28 23:58:27 -0500347 transaction->t_chp_stats.cs_written++;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700348 (*batch_count)++;
Theodore Ts'o1a0d3782008-11-05 00:09:22 -0500349 if (*batch_count == JBD2_NR_BATCH) {
Dave Kleikamp470decc2006-10-11 01:20:57 -0700350 spin_unlock(&journal->j_list_lock);
Theodore Ts'o1a0d3782008-11-05 00:09:22 -0500351 __flush_batch(journal, batch_count);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700352 ret = 1;
353 }
354 }
355 return ret;
356}
357
358/*
359 * Perform an actual checkpoint. We take the first transaction on the
360 * list of transactions to be checkpointed and send all its buffers
361 * to disk. We submit larger chunks of data at once.
362 *
363 * The journal should be locked before calling this function.
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400364 * Called with j_checkpoint_mutex held.
Dave Kleikamp470decc2006-10-11 01:20:57 -0700365 */
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700366int jbd2_log_do_checkpoint(journal_t *journal)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700367{
368 transaction_t *transaction;
369 tid_t this_tid;
370 int result;
371
372 jbd_debug(1, "Start checkpoint\n");
373
374 /*
375 * First thing: if there are any transactions in the log which
376 * don't need checkpointing, just eliminate them from the
377 * journal straight away.
378 */
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700379 result = jbd2_cleanup_journal_tail(journal);
Theodore Ts'o879c5e62009-06-17 11:47:48 -0400380 trace_jbd2_checkpoint(journal, result);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700381 jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
382 if (result <= 0)
383 return result;
384
385 /*
386 * OK, we need to start writing disk blocks. Take one transaction
387 * and write it.
388 */
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400389 result = 0;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700390 spin_lock(&journal->j_list_lock);
391 if (!journal->j_checkpoint_transactions)
392 goto out;
393 transaction = journal->j_checkpoint_transactions;
Johann Lombardi8e85fb32008-01-28 23:58:27 -0500394 if (transaction->t_chp_stats.cs_chp_time == 0)
395 transaction->t_chp_stats.cs_chp_time = jiffies;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700396 this_tid = transaction->t_tid;
397restart:
398 /*
399 * If someone cleaned up this transaction while we slept, we're
400 * done (maybe it's a new transaction, but it fell at the same
401 * address).
402 */
403 if (journal->j_checkpoint_transactions == transaction &&
404 transaction->t_tid == this_tid) {
405 int batch_count = 0;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700406 struct journal_head *jh;
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400407 int retry = 0, err;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700408
409 while (!retry && transaction->t_checkpoint_list) {
410 struct buffer_head *bh;
411
412 jh = transaction->t_checkpoint_list;
413 bh = jh2bh(jh);
414 if (!jbd_trylock_bh_state(bh)) {
415 jbd_sync_bh(journal, bh);
416 retry = 1;
417 break;
418 }
Theodore Ts'o1a0d3782008-11-05 00:09:22 -0500419 retry = __process_buffer(journal, jh, &batch_count,
Johann Lombardi8e85fb32008-01-28 23:58:27 -0500420 transaction);
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400421 if (retry < 0 && !result)
422 result = retry;
Nick Piggin95c354f2008-01-30 13:31:20 +0100423 if (!retry && (need_resched() ||
424 spin_needbreak(&journal->j_list_lock))) {
Dave Kleikamp470decc2006-10-11 01:20:57 -0700425 spin_unlock(&journal->j_list_lock);
426 retry = 1;
427 break;
428 }
429 }
430
431 if (batch_count) {
432 if (!retry) {
433 spin_unlock(&journal->j_list_lock);
434 retry = 1;
435 }
Theodore Ts'o1a0d3782008-11-05 00:09:22 -0500436 __flush_batch(journal, &batch_count);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700437 }
438
439 if (retry) {
440 spin_lock(&journal->j_list_lock);
441 goto restart;
442 }
443 /*
444 * Now we have cleaned up the first transaction's checkpoint
445 * list. Let's clean up the second one
446 */
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400447 err = __wait_cp_io(journal, transaction);
448 if (!result)
449 result = err;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700450 }
451out:
452 spin_unlock(&journal->j_list_lock);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700453 if (result < 0)
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400454 jbd2_journal_abort(journal, result);
455 else
456 result = jbd2_cleanup_journal_tail(journal);
457
458 return (result < 0) ? result : 0;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700459}
460
461/*
462 * Check the list of checkpoint transactions for the journal to see if
463 * we have already got rid of any since the last update of the log tail
464 * in the journal superblock. If so, we can instantly roll the
465 * superblock forward to remove those transactions from the log.
466 *
467 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
468 *
469 * Called with the journal lock held.
470 *
471 * This is the only part of the journaling code which really needs to be
472 * aware of transaction aborts. Checkpointing involves writing to the
473 * main filesystem area rather than to the journal, so it can proceed
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400474 * even in abort state, but we must not update the super block if
475 * checkpointing may have failed. Otherwise, we would lose some metadata
476 * buffers which should be written-back to the filesystem.
Dave Kleikamp470decc2006-10-11 01:20:57 -0700477 */
478
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700479int jbd2_cleanup_journal_tail(journal_t *journal)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700480{
481 transaction_t * transaction;
482 tid_t first_tid;
483 unsigned long blocknr, freed;
484
Hidehiro Kawai44519fa2008-10-10 20:29:13 -0400485 if (is_journal_aborted(journal))
486 return 1;
487
Dave Kleikamp470decc2006-10-11 01:20:57 -0700488 /* OK, work out the oldest transaction remaining in the log, and
489 * the log block it starts at.
490 *
491 * If the log is now empty, we need to work out which is the
492 * next transaction ID we will write, and where it will
493 * start. */
494
Theodore Ts'oa931da62010-08-03 21:35:12 -0400495 write_lock(&journal->j_state_lock);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700496 spin_lock(&journal->j_list_lock);
497 transaction = journal->j_checkpoint_transactions;
498 if (transaction) {
499 first_tid = transaction->t_tid;
500 blocknr = transaction->t_log_start;
501 } else if ((transaction = journal->j_committing_transaction) != NULL) {
502 first_tid = transaction->t_tid;
503 blocknr = transaction->t_log_start;
504 } else if ((transaction = journal->j_running_transaction) != NULL) {
505 first_tid = transaction->t_tid;
506 blocknr = journal->j_head;
507 } else {
508 first_tid = journal->j_transaction_sequence;
509 blocknr = journal->j_head;
510 }
511 spin_unlock(&journal->j_list_lock);
512 J_ASSERT(blocknr != 0);
513
514 /* If the oldest pinned transaction is at the tail of the log
515 already then there's not much we can do right now. */
516 if (journal->j_tail_sequence == first_tid) {
Theodore Ts'oa931da62010-08-03 21:35:12 -0400517 write_unlock(&journal->j_state_lock);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700518 return 1;
519 }
520
521 /* OK, update the superblock to recover the freed space.
522 * Physical blocks come first: have we wrapped beyond the end of
523 * the log? */
524 freed = blocknr - journal->j_tail;
525 if (blocknr < journal->j_tail)
526 freed = freed + journal->j_last - journal->j_first;
527
Theodore Ts'o71f2be22009-12-23 07:45:44 -0500528 trace_jbd2_cleanup_journal_tail(journal, first_tid, blocknr, freed);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700529 jbd_debug(1,
530 "Cleaning journal tail from %d to %d (offset %lu), "
531 "freeing %lu\n",
532 journal->j_tail_sequence, first_tid, blocknr, freed);
533
534 journal->j_free += freed;
535 journal->j_tail_sequence = first_tid;
536 journal->j_tail = blocknr;
Theodore Ts'oa931da62010-08-03 21:35:12 -0400537 write_unlock(&journal->j_state_lock);
Theodore Ts'occ3e1be2009-12-23 06:52:08 -0500538
539 /*
540 * If there is an external journal, we need to make sure that
541 * any data blocks that were recently written out --- perhaps
542 * by jbd2_log_do_checkpoint() --- are flushed out before we
543 * drop the transactions from the external journal. It's
544 * unlikely this will be necessary, especially with a
545 * appropriately sized journal, but we need this to guarantee
546 * correctness. Fortunately jbd2_cleanup_journal_tail()
547 * doesn't get called all that often.
548 */
549 if ((journal->j_fs_dev != journal->j_dev) &&
550 (journal->j_flags & JBD2_BARRIER))
Christoph Hellwigdd3932e2010-09-16 20:51:46 +0200551 blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700552 if (!(journal->j_flags & JBD2_ABORT))
553 jbd2_journal_update_superblock(journal, 1);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700554 return 0;
555}
556
557
558/* Checkpoint list management */
559
560/*
561 * journal_clean_one_cp_list
562 *
Jan Karade1b7942011-06-13 15:38:22 -0400563 * Find all the written-back checkpoint buffers in the given list and
564 * release them.
Dave Kleikamp470decc2006-10-11 01:20:57 -0700565 *
566 * Called with the journal locked.
567 * Called with j_list_lock held.
Paul Bolle90802ed2011-12-05 13:00:34 +0100568 * Returns number of buffers reaped (for debug)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700569 */
570
571static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
572{
573 struct journal_head *last_jh;
574 struct journal_head *next_jh = jh;
575 int ret, freed = 0;
576
577 *released = 0;
578 if (!jh)
579 return 0;
580
581 last_jh = jh->b_cpprev;
582 do {
583 jh = next_jh;
584 next_jh = jh->b_cpnext;
585 /* Use trylock because of the ranking */
586 if (jbd_trylock_bh_state(jh2bh(jh))) {
587 ret = __try_to_free_cp_buf(jh);
588 if (ret) {
589 freed++;
590 if (ret == 2) {
591 *released = 1;
592 return freed;
593 }
594 }
595 }
596 /*
597 * This function only frees up some memory
598 * if possible so we dont have an obligation
599 * to finish processing. Bail out if preemption
600 * requested:
601 */
602 if (need_resched())
603 return freed;
604 } while (jh != last_jh);
605
606 return freed;
607}
608
609/*
610 * journal_clean_checkpoint_list
611 *
612 * Find all the written-back checkpoint buffers in the journal and release them.
613 *
614 * Called with the journal locked.
615 * Called with j_list_lock held.
616 * Returns number of buffers reaped (for debug)
617 */
618
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700619int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700620{
621 transaction_t *transaction, *last_transaction, *next_transaction;
622 int ret = 0;
623 int released;
624
625 transaction = journal->j_checkpoint_transactions;
626 if (!transaction)
627 goto out;
628
629 last_transaction = transaction->t_cpprev;
630 next_transaction = transaction;
631 do {
632 transaction = next_transaction;
633 next_transaction = transaction->t_cpnext;
634 ret += journal_clean_one_cp_list(transaction->
635 t_checkpoint_list, &released);
636 /*
637 * This function only frees up some memory if possible so we
638 * dont have an obligation to finish processing. Bail out if
639 * preemption requested:
640 */
641 if (need_resched())
642 goto out;
643 if (released)
644 continue;
645 /*
646 * It is essential that we are as careful as in the case of
647 * t_checkpoint_list with removing the buffer from the list as
648 * we can possibly see not yet submitted buffers on io_list
649 */
650 ret += journal_clean_one_cp_list(transaction->
651 t_checkpoint_io_list, &released);
652 if (need_resched())
653 goto out;
654 } while (transaction != last_transaction);
655out:
656 return ret;
657}
658
659/*
660 * journal_remove_checkpoint: called after a buffer has been committed
661 * to disk (either by being write-back flushed to disk, or being
662 * committed to the log).
663 *
664 * We cannot safely clean a transaction out of the log until all of the
665 * buffer updates committed in that transaction have safely been stored
666 * elsewhere on disk. To achieve this, all of the buffers in a
667 * transaction need to be maintained on the transaction's checkpoint
668 * lists until they have been rewritten, at which point this function is
669 * called to remove the buffer from the existing transaction's
670 * checkpoint lists.
671 *
672 * The function returns 1 if it frees the transaction, 0 otherwise.
Jan Karade1b7942011-06-13 15:38:22 -0400673 * The function can free jh and bh.
Dave Kleikamp470decc2006-10-11 01:20:57 -0700674 *
Dave Kleikamp470decc2006-10-11 01:20:57 -0700675 * This function is called with j_list_lock held.
676 * This function is called with jbd_lock_bh_state(jh2bh(jh))
677 */
678
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700679int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700680{
Theodore Ts'obf699322009-09-30 00:32:06 -0400681 struct transaction_chp_stats_s *stats;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700682 transaction_t *transaction;
683 journal_t *journal;
684 int ret = 0;
685
686 JBUFFER_TRACE(jh, "entry");
687
688 if ((transaction = jh->b_cp_transaction) == NULL) {
689 JBUFFER_TRACE(jh, "not on transaction");
690 goto out;
691 }
692 journal = transaction->t_journal;
693
Jan Karade1b7942011-06-13 15:38:22 -0400694 JBUFFER_TRACE(jh, "removing from transaction");
Dave Kleikamp470decc2006-10-11 01:20:57 -0700695 __buffer_unlink(jh);
696 jh->b_cp_transaction = NULL;
Jan Karade1b7942011-06-13 15:38:22 -0400697 jbd2_journal_put_journal_head(jh);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700698
699 if (transaction->t_checkpoint_list != NULL ||
700 transaction->t_checkpoint_io_list != NULL)
701 goto out;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700702
703 /*
704 * There is one special case to worry about: if we have just pulled the
Jan Karaf5a7a6b2008-01-28 23:58:27 -0500705 * buffer off a running or committing transaction's checkpoing list,
706 * then even if the checkpoint list is empty, the transaction obviously
707 * cannot be dropped!
Dave Kleikamp470decc2006-10-11 01:20:57 -0700708 *
Jan Karaf5a7a6b2008-01-28 23:58:27 -0500709 * The locking here around t_state is a bit sleazy.
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700710 * See the comment at the end of jbd2_journal_commit_transaction().
Dave Kleikamp470decc2006-10-11 01:20:57 -0700711 */
Jan Karade1b7942011-06-13 15:38:22 -0400712 if (transaction->t_state != T_FINISHED)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700713 goto out;
Dave Kleikamp470decc2006-10-11 01:20:57 -0700714
715 /* OK, that was the last buffer for the transaction: we can now
716 safely remove this transaction from the log */
Theodore Ts'obf699322009-09-30 00:32:06 -0400717 stats = &transaction->t_chp_stats;
718 if (stats->cs_chp_time)
719 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
720 jiffies);
721 trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
722 transaction->t_tid, stats);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700723
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700724 __jbd2_journal_drop_transaction(journal, transaction);
Aneesh Kumar K.Vfb684072008-11-06 17:50:21 -0500725 kfree(transaction);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700726
727 /* Just in case anybody was waiting for more transactions to be
728 checkpointed... */
729 wake_up(&journal->j_wait_logspace);
730 ret = 1;
731out:
Dave Kleikamp470decc2006-10-11 01:20:57 -0700732 return ret;
733}
734
735/*
736 * journal_insert_checkpoint: put a committed buffer onto a checkpoint
737 * list so that we know when it is safe to clean the transaction out of
738 * the log.
739 *
740 * Called with the journal locked.
741 * Called with j_list_lock held.
742 */
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700743void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
Dave Kleikamp470decc2006-10-11 01:20:57 -0700744 transaction_t *transaction)
745{
746 JBUFFER_TRACE(jh, "entry");
747 J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
748 J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
749
Jan Karade1b7942011-06-13 15:38:22 -0400750 /* Get reference for checkpointing transaction */
751 jbd2_journal_grab_journal_head(jh2bh(jh));
Dave Kleikamp470decc2006-10-11 01:20:57 -0700752 jh->b_cp_transaction = transaction;
753
754 if (!transaction->t_checkpoint_list) {
755 jh->b_cpnext = jh->b_cpprev = jh;
756 } else {
757 jh->b_cpnext = transaction->t_checkpoint_list;
758 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
759 jh->b_cpprev->b_cpnext = jh;
760 jh->b_cpnext->b_cpprev = jh;
761 }
762 transaction->t_checkpoint_list = jh;
763}
764
765/*
766 * We've finished with this transaction structure: adios...
767 *
768 * The transaction must have no links except for the checkpoint by this
769 * point.
770 *
771 * Called with the journal locked.
772 * Called with j_list_lock held.
773 */
774
Mingming Caof7f4bcc2006-10-11 01:20:59 -0700775void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
Dave Kleikamp470decc2006-10-11 01:20:57 -0700776{
777 assert_spin_locked(&journal->j_list_lock);
778 if (transaction->t_cpnext) {
779 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
780 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
781 if (journal->j_checkpoint_transactions == transaction)
782 journal->j_checkpoint_transactions =
783 transaction->t_cpnext;
784 if (journal->j_checkpoint_transactions == transaction)
785 journal->j_checkpoint_transactions = NULL;
786 }
787
788 J_ASSERT(transaction->t_state == T_FINISHED);
789 J_ASSERT(transaction->t_buffers == NULL);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700790 J_ASSERT(transaction->t_forget == NULL);
791 J_ASSERT(transaction->t_iobuf_list == NULL);
792 J_ASSERT(transaction->t_shadow_list == NULL);
793 J_ASSERT(transaction->t_log_list == NULL);
794 J_ASSERT(transaction->t_checkpoint_list == NULL);
795 J_ASSERT(transaction->t_checkpoint_io_list == NULL);
Theodore Ts'oa51dca92010-08-02 08:43:25 -0400796 J_ASSERT(atomic_read(&transaction->t_updates) == 0);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700797 J_ASSERT(journal->j_committing_transaction != transaction);
798 J_ASSERT(journal->j_running_transaction != transaction);
799
800 jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
Dave Kleikamp470decc2006-10-11 01:20:57 -0700801}