0b7d3b8226fdb01725b76b6ba18643a4fbd41381
[linux-2.6.git] / fs / jbd2 / commit.c
1 /*
2  * linux/fs/jbd2/commit.c
3  *
4  * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
5  *
6  * Copyright 1998 Red Hat corp --- All Rights Reserved
7  *
8  * This file is part of the Linux kernel and is made available under
9  * the terms of the GNU General Public License, version 2, or at your
10  * option, any later version, incorporated herein by reference.
11  *
12  * Journal commit routines for the generic filesystem journaling code;
13  * part of the ext2fs journaling system.
14  */
15
16 #include <linux/time.h>
17 #include <linux/fs.h>
18 #include <linux/jbd2.h>
19 #include <linux/marker.h>
20 #include <linux/errno.h>
21 #include <linux/slab.h>
22 #include <linux/mm.h>
23 #include <linux/pagemap.h>
24 #include <linux/jiffies.h>
25 #include <linux/crc32.h>
26 #include <linux/writeback.h>
27 #include <linux/backing-dev.h>
28 #include <linux/bio.h>
29
30 /*
31  * Default IO end handler for temporary BJ_IO buffer_heads.
32  */
33 static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
34 {
35         BUFFER_TRACE(bh, "");
36         if (uptodate)
37                 set_buffer_uptodate(bh);
38         else
39                 clear_buffer_uptodate(bh);
40         unlock_buffer(bh);
41 }
42
43 /*
44  * When an ext4 file is truncated, it is possible that some pages are not
45  * successfully freed, because they are attached to a committing transaction.
46  * After the transaction commits, these pages are left on the LRU, with no
47  * ->mapping, and with attached buffers.  These pages are trivially reclaimable
48  * by the VM, but their apparent absence upsets the VM accounting, and it makes
49  * the numbers in /proc/meminfo look odd.
50  *
51  * So here, we have a buffer which has just come off the forget list.  Look to
52  * see if we can strip all buffers from the backing page.
53  *
54  * Called under lock_journal(), and possibly under journal_datalist_lock.  The
55  * caller provided us with a ref against the buffer, and we drop that here.
56  */
57 static void release_buffer_page(struct buffer_head *bh)
58 {
59         struct page *page;
60
61         if (buffer_dirty(bh))
62                 goto nope;
63         if (atomic_read(&bh->b_count) != 1)
64                 goto nope;
65         page = bh->b_page;
66         if (!page)
67                 goto nope;
68         if (page->mapping)
69                 goto nope;
70
71         /* OK, it's a truncated page */
72         if (!trylock_page(page))
73                 goto nope;
74
75         page_cache_get(page);
76         __brelse(bh);
77         try_to_free_buffers(page);
78         unlock_page(page);
79         page_cache_release(page);
80         return;
81
82 nope:
83         __brelse(bh);
84 }
85
86 /*
87  * Done it all: now submit the commit record.  We should have
88  * cleaned up our previous buffers by now, so if we are in abort
89  * mode we can now just skip the rest of the journal write
90  * entirely.
91  *
92  * Returns 1 if the journal needs to be aborted or 0 on success
93  */
94 static int journal_submit_commit_record(journal_t *journal,
95                                         transaction_t *commit_transaction,
96                                         struct buffer_head **cbh,
97                                         __u32 crc32_sum)
98 {
99         struct journal_head *descriptor;
100         struct commit_header *tmp;
101         struct buffer_head *bh;
102         int ret;
103         int barrier_done = 0;
104         struct timespec now = current_kernel_time();
105
106         if (is_journal_aborted(journal))
107                 return 0;
108
109         descriptor = jbd2_journal_get_descriptor_buffer(journal);
110         if (!descriptor)
111                 return 1;
112
113         bh = jh2bh(descriptor);
114
115         tmp = (struct commit_header *)bh->b_data;
116         tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
117         tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK);
118         tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
119         tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
120         tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);
121
122         if (JBD2_HAS_COMPAT_FEATURE(journal,
123                                     JBD2_FEATURE_COMPAT_CHECKSUM)) {
124                 tmp->h_chksum_type      = JBD2_CRC32_CHKSUM;
125                 tmp->h_chksum_size      = JBD2_CRC32_CHKSUM_SIZE;
126                 tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
127         }
128
129         JBUFFER_TRACE(descriptor, "submit commit block");
130         lock_buffer(bh);
131         clear_buffer_dirty(bh);
132         set_buffer_uptodate(bh);
133         bh->b_end_io = journal_end_buffer_io_sync;
134
135         if (journal->j_flags & JBD2_BARRIER &&
136                 !JBD2_HAS_INCOMPAT_FEATURE(journal,
137                                          JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
138                 set_buffer_ordered(bh);
139                 barrier_done = 1;
140         }
141         ret = submit_bh(WRITE_SYNC_PLUG, bh);
142         if (barrier_done)
143                 clear_buffer_ordered(bh);
144
145         /* is it possible for another commit to fail at roughly
146          * the same time as this one?  If so, we don't want to
147          * trust the barrier flag in the super, but instead want
148          * to remember if we sent a barrier request
149          */
150         if (ret == -EOPNOTSUPP && barrier_done) {
151                 printk(KERN_WARNING
152                        "JBD: barrier-based sync failed on %s - "
153                        "disabling barriers\n", journal->j_devname);
154                 spin_lock(&journal->j_state_lock);
155                 journal->j_flags &= ~JBD2_BARRIER;
156                 spin_unlock(&journal->j_state_lock);
157
158                 /* And try again, without the barrier */
159                 lock_buffer(bh);
160                 set_buffer_uptodate(bh);
161                 clear_buffer_dirty(bh);
162                 ret = submit_bh(WRITE_SYNC_PLUG, bh);
163         }
164         *cbh = bh;
165         return ret;
166 }
167
168 /*
169  * This function along with journal_submit_commit_record
170  * allows to write the commit record asynchronously.
171  */
172 static int journal_wait_on_commit_record(journal_t *journal,
173                                          struct buffer_head *bh)
174 {
175         int ret = 0;
176
177 retry:
178         clear_buffer_dirty(bh);
179         wait_on_buffer(bh);
180         if (buffer_eopnotsupp(bh) && (journal->j_flags & JBD2_BARRIER)) {
181                 printk(KERN_WARNING
182                        "JBD2: wait_on_commit_record: sync failed on %s - "
183                        "disabling barriers\n", journal->j_devname);
184                 spin_lock(&journal->j_state_lock);
185                 journal->j_flags &= ~JBD2_BARRIER;
186                 spin_unlock(&journal->j_state_lock);
187
188                 lock_buffer(bh);
189                 clear_buffer_dirty(bh);
190                 set_buffer_uptodate(bh);
191                 bh->b_end_io = journal_end_buffer_io_sync;
192
193                 ret = submit_bh(WRITE_SYNC_PLUG, bh);
194                 if (ret) {
195                         unlock_buffer(bh);
196                         return ret;
197                 }
198                 goto retry;
199         }
200
201         if (unlikely(!buffer_uptodate(bh)))
202                 ret = -EIO;
203         put_bh(bh);            /* One for getblk() */
204         jbd2_journal_put_journal_head(bh2jh(bh));
205
206         return ret;
207 }
208
209 /*
210  * write the filemap data using writepage() address_space_operations.
211  * We don't do block allocation here even for delalloc. We don't
212  * use writepages() because with dealyed allocation we may be doing
213  * block allocation in writepages().
214  */
215 static int journal_submit_inode_data_buffers(struct address_space *mapping)
216 {
217         int ret;
218         struct writeback_control wbc = {
219                 .sync_mode =  WB_SYNC_ALL,
220                 .nr_to_write = mapping->nrpages * 2,
221                 .range_start = 0,
222                 .range_end = i_size_read(mapping->host),
223                 .for_writepages = 1,
224         };
225
226         ret = generic_writepages(mapping, &wbc);
227         return ret;
228 }
229
230 /*
231  * Submit all the data buffers of inode associated with the transaction to
232  * disk.
233  *
234  * We are in a committing transaction. Therefore no new inode can be added to
235  * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently
236  * operate on from being released while we write out pages.
237  */
238 static int journal_submit_data_buffers(journal_t *journal,
239                 transaction_t *commit_transaction)
240 {
241         struct jbd2_inode *jinode;
242         int err, ret = 0;
243         struct address_space *mapping;
244
245         spin_lock(&journal->j_list_lock);
246         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
247                 mapping = jinode->i_vfs_inode->i_mapping;
248                 jinode->i_flags |= JI_COMMIT_RUNNING;
249                 spin_unlock(&journal->j_list_lock);
250                 /*
251                  * submit the inode data buffers. We use writepage
252                  * instead of writepages. Because writepages can do
253                  * block allocation  with delalloc. We need to write
254                  * only allocated blocks here.
255                  */
256                 err = journal_submit_inode_data_buffers(mapping);
257                 if (!ret)
258                         ret = err;
259                 spin_lock(&journal->j_list_lock);
260                 J_ASSERT(jinode->i_transaction == commit_transaction);
261                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
262                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
263         }
264         spin_unlock(&journal->j_list_lock);
265         return ret;
266 }
267
268 /*
269  * Wait for data submitted for writeout, refile inodes to proper
270  * transaction if needed.
271  *
272  */
273 static int journal_finish_inode_data_buffers(journal_t *journal,
274                 transaction_t *commit_transaction)
275 {
276         struct jbd2_inode *jinode, *next_i;
277         int err, ret = 0;
278
279         /* For locking, see the comment in journal_submit_data_buffers() */
280         spin_lock(&journal->j_list_lock);
281         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
282                 jinode->i_flags |= JI_COMMIT_RUNNING;
283                 spin_unlock(&journal->j_list_lock);
284                 err = filemap_fdatawait(jinode->i_vfs_inode->i_mapping);
285                 if (err) {
286                         /*
287                          * Because AS_EIO is cleared by
288                          * wait_on_page_writeback_range(), set it again so
289                          * that user process can get -EIO from fsync().
290                          */
291                         set_bit(AS_EIO,
292                                 &jinode->i_vfs_inode->i_mapping->flags);
293
294                         if (!ret)
295                                 ret = err;
296                 }
297                 spin_lock(&journal->j_list_lock);
298                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
299                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
300         }
301
302         /* Now refile inode to proper lists */
303         list_for_each_entry_safe(jinode, next_i,
304                                  &commit_transaction->t_inode_list, i_list) {
305                 list_del(&jinode->i_list);
306                 if (jinode->i_next_transaction) {
307                         jinode->i_transaction = jinode->i_next_transaction;
308                         jinode->i_next_transaction = NULL;
309                         list_add(&jinode->i_list,
310                                 &jinode->i_transaction->t_inode_list);
311                 } else {
312                         jinode->i_transaction = NULL;
313                 }
314         }
315         spin_unlock(&journal->j_list_lock);
316
317         return ret;
318 }
319
320 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
321 {
322         struct page *page = bh->b_page;
323         char *addr;
324         __u32 checksum;
325
326         addr = kmap_atomic(page, KM_USER0);
327         checksum = crc32_be(crc32_sum,
328                 (void *)(addr + offset_in_page(bh->b_data)), bh->b_size);
329         kunmap_atomic(addr, KM_USER0);
330
331         return checksum;
332 }
333
334 static void write_tag_block(int tag_bytes, journal_block_tag_t *tag,
335                                    unsigned long long block)
336 {
337         tag->t_blocknr = cpu_to_be32(block & (u32)~0);
338         if (tag_bytes > JBD2_TAG_SIZE32)
339                 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
340 }
341
342 /*
343  * jbd2_journal_commit_transaction
344  *
345  * The primary function for committing a transaction to the log.  This
346  * function is called by the journal thread to begin a complete commit.
347  */
348 void jbd2_journal_commit_transaction(journal_t *journal)
349 {
350         struct transaction_stats_s stats;
351         transaction_t *commit_transaction;
352         struct journal_head *jh, *new_jh, *descriptor;
353         struct buffer_head **wbuf = journal->j_wbuf;
354         int bufs;
355         int flags;
356         int err;
357         unsigned long long blocknr;
358         ktime_t start_time;
359         u64 commit_time;
360         char *tagp = NULL;
361         journal_header_t *header;
362         journal_block_tag_t *tag = NULL;
363         int space_left = 0;
364         int first_tag = 0;
365         int tag_flag;
366         int i, to_free = 0;
367         int tag_bytes = journal_tag_bytes(journal);
368         struct buffer_head *cbh = NULL; /* For transactional checksums */
369         __u32 crc32_sum = ~0;
370         int write_op = WRITE;
371
372         /*
373          * First job: lock down the current transaction and wait for
374          * all outstanding updates to complete.
375          */
376
377 #ifdef COMMIT_STATS
378         spin_lock(&journal->j_list_lock);
379         summarise_journal_usage(journal);
380         spin_unlock(&journal->j_list_lock);
381 #endif
382
383         /* Do we need to erase the effects of a prior jbd2_journal_flush? */
384         if (journal->j_flags & JBD2_FLUSHED) {
385                 jbd_debug(3, "super block updated\n");
386                 jbd2_journal_update_superblock(journal, 1);
387         } else {
388                 jbd_debug(3, "superblock not updated\n");
389         }
390
391         J_ASSERT(journal->j_running_transaction != NULL);
392         J_ASSERT(journal->j_committing_transaction == NULL);
393
394         commit_transaction = journal->j_running_transaction;
395         J_ASSERT(commit_transaction->t_state == T_RUNNING);
396
397         trace_mark(jbd2_start_commit, "dev %s transaction %d",
398                    journal->j_devname, commit_transaction->t_tid);
399         jbd_debug(1, "JBD: starting commit of transaction %d\n",
400                         commit_transaction->t_tid);
401
402         spin_lock(&journal->j_state_lock);
403         commit_transaction->t_state = T_LOCKED;
404
405         /*
406          * Use plugged writes here, since we want to submit several before
407          * we unplug the device. We don't do explicit unplugging in here,
408          * instead we rely on sync_buffer() doing the unplug for us.
409          */
410         if (commit_transaction->t_synchronous_commit)
411                 write_op = WRITE_SYNC_PLUG;
412         stats.u.run.rs_wait = commit_transaction->t_max_wait;
413         stats.u.run.rs_locked = jiffies;
414         stats.u.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
415                                                 stats.u.run.rs_locked);
416
417         spin_lock(&commit_transaction->t_handle_lock);
418         while (commit_transaction->t_updates) {
419                 DEFINE_WAIT(wait);
420
421                 prepare_to_wait(&journal->j_wait_updates, &wait,
422                                         TASK_UNINTERRUPTIBLE);
423                 if (commit_transaction->t_updates) {
424                         spin_unlock(&commit_transaction->t_handle_lock);
425                         spin_unlock(&journal->j_state_lock);
426                         schedule();
427                         spin_lock(&journal->j_state_lock);
428                         spin_lock(&commit_transaction->t_handle_lock);
429                 }
430                 finish_wait(&journal->j_wait_updates, &wait);
431         }
432         spin_unlock(&commit_transaction->t_handle_lock);
433
434         J_ASSERT (commit_transaction->t_outstanding_credits <=
435                         journal->j_max_transaction_buffers);
436
437         /*
438          * First thing we are allowed to do is to discard any remaining
439          * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
440          * that there are no such buffers: if a large filesystem
441          * operation like a truncate needs to split itself over multiple
442          * transactions, then it may try to do a jbd2_journal_restart() while
443          * there are still BJ_Reserved buffers outstanding.  These must
444          * be released cleanly from the current transaction.
445          *
446          * In this case, the filesystem must still reserve write access
447          * again before modifying the buffer in the new transaction, but
448          * we do not require it to remember exactly which old buffers it
449          * has reserved.  This is consistent with the existing behaviour
450          * that multiple jbd2_journal_get_write_access() calls to the same
451          * buffer are perfectly permissable.
452          */
453         while (commit_transaction->t_reserved_list) {
454                 jh = commit_transaction->t_reserved_list;
455                 JBUFFER_TRACE(jh, "reserved, unused: refile");
456                 /*
457                  * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
458                  * leave undo-committed data.
459                  */
460                 if (jh->b_committed_data) {
461                         struct buffer_head *bh = jh2bh(jh);
462
463                         jbd_lock_bh_state(bh);
464                         jbd2_free(jh->b_committed_data, bh->b_size);
465                         jh->b_committed_data = NULL;
466                         jbd_unlock_bh_state(bh);
467                 }
468                 jbd2_journal_refile_buffer(journal, jh);
469         }
470
471         /*
472          * Now try to drop any written-back buffers from the journal's
473          * checkpoint lists.  We do this *before* commit because it potentially
474          * frees some memory
475          */
476         spin_lock(&journal->j_list_lock);
477         __jbd2_journal_clean_checkpoint_list(journal);
478         spin_unlock(&journal->j_list_lock);
479
480         jbd_debug (3, "JBD: commit phase 1\n");
481
482         /*
483          * Switch to a new revoke table.
484          */
485         jbd2_journal_switch_revoke_table(journal);
486
487         stats.u.run.rs_flushing = jiffies;
488         stats.u.run.rs_locked = jbd2_time_diff(stats.u.run.rs_locked,
489                                                stats.u.run.rs_flushing);
490
491         commit_transaction->t_state = T_FLUSH;
492         journal->j_committing_transaction = commit_transaction;
493         journal->j_running_transaction = NULL;
494         start_time = ktime_get();
495         commit_transaction->t_log_start = journal->j_head;
496         wake_up(&journal->j_wait_transaction_locked);
497         spin_unlock(&journal->j_state_lock);
498
499         jbd_debug (3, "JBD: commit phase 2\n");
500
501         /*
502          * Now start flushing things to disk, in the order they appear
503          * on the transaction lists.  Data blocks go first.
504          */
505         err = journal_submit_data_buffers(journal, commit_transaction);
506         if (err)
507                 jbd2_journal_abort(journal, err);
508
509         jbd2_journal_write_revoke_records(journal, commit_transaction,
510                                           write_op);
511
512         jbd_debug(3, "JBD: commit phase 2\n");
513
514         /*
515          * Way to go: we have now written out all of the data for a
516          * transaction!  Now comes the tricky part: we need to write out
517          * metadata.  Loop over the transaction's entire buffer list:
518          */
519         spin_lock(&journal->j_state_lock);
520         commit_transaction->t_state = T_COMMIT;
521         spin_unlock(&journal->j_state_lock);
522
523         stats.u.run.rs_logging = jiffies;
524         stats.u.run.rs_flushing = jbd2_time_diff(stats.u.run.rs_flushing,
525                                                  stats.u.run.rs_logging);
526         stats.u.run.rs_blocks = commit_transaction->t_outstanding_credits;
527         stats.u.run.rs_blocks_logged = 0;
528
529         J_ASSERT(commit_transaction->t_nr_buffers <=
530                  commit_transaction->t_outstanding_credits);
531
532         err = 0;
533         descriptor = NULL;
534         bufs = 0;
535         while (commit_transaction->t_buffers) {
536
537                 /* Find the next buffer to be journaled... */
538
539                 jh = commit_transaction->t_buffers;
540
541                 /* If we're in abort mode, we just un-journal the buffer and
542                    release it. */
543
544                 if (is_journal_aborted(journal)) {
545                         clear_buffer_jbddirty(jh2bh(jh));
546                         JBUFFER_TRACE(jh, "journal is aborting: refile");
547                         jbd2_buffer_abort_trigger(jh,
548                                                   jh->b_frozen_data ?
549                                                   jh->b_frozen_triggers :
550                                                   jh->b_triggers);
551                         jbd2_journal_refile_buffer(journal, jh);
552                         /* If that was the last one, we need to clean up
553                          * any descriptor buffers which may have been
554                          * already allocated, even if we are now
555                          * aborting. */
556                         if (!commit_transaction->t_buffers)
557                                 goto start_journal_io;
558                         continue;
559                 }
560
561                 /* Make sure we have a descriptor block in which to
562                    record the metadata buffer. */
563
564                 if (!descriptor) {
565                         struct buffer_head *bh;
566
567                         J_ASSERT (bufs == 0);
568
569                         jbd_debug(4, "JBD: get descriptor\n");
570
571                         descriptor = jbd2_journal_get_descriptor_buffer(journal);
572                         if (!descriptor) {
573                                 jbd2_journal_abort(journal, -EIO);
574                                 continue;
575                         }
576
577                         bh = jh2bh(descriptor);
578                         jbd_debug(4, "JBD: got buffer %llu (%p)\n",
579                                 (unsigned long long)bh->b_blocknr, bh->b_data);
580                         header = (journal_header_t *)&bh->b_data[0];
581                         header->h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
582                         header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK);
583                         header->h_sequence  = cpu_to_be32(commit_transaction->t_tid);
584
585                         tagp = &bh->b_data[sizeof(journal_header_t)];
586                         space_left = bh->b_size - sizeof(journal_header_t);
587                         first_tag = 1;
588                         set_buffer_jwrite(bh);
589                         set_buffer_dirty(bh);
590                         wbuf[bufs++] = bh;
591
592                         /* Record it so that we can wait for IO
593                            completion later */
594                         BUFFER_TRACE(bh, "ph3: file as descriptor");
595                         jbd2_journal_file_buffer(descriptor, commit_transaction,
596                                         BJ_LogCtl);
597                 }
598
599                 /* Where is the buffer to be written? */
600
601                 err = jbd2_journal_next_log_block(journal, &blocknr);
602                 /* If the block mapping failed, just abandon the buffer
603                    and repeat this loop: we'll fall into the
604                    refile-on-abort condition above. */
605                 if (err) {
606                         jbd2_journal_abort(journal, err);
607                         continue;
608                 }
609
610                 /*
611                  * start_this_handle() uses t_outstanding_credits to determine
612                  * the free space in the log, but this counter is changed
613                  * by jbd2_journal_next_log_block() also.
614                  */
615                 commit_transaction->t_outstanding_credits--;
616
617                 /* Bump b_count to prevent truncate from stumbling over
618                    the shadowed buffer!  @@@ This can go if we ever get
619                    rid of the BJ_IO/BJ_Shadow pairing of buffers. */
620                 atomic_inc(&jh2bh(jh)->b_count);
621
622                 /* Make a temporary IO buffer with which to write it out
623                    (this will requeue both the metadata buffer and the
624                    temporary IO buffer). new_bh goes on BJ_IO*/
625
626                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
627                 /*
628                  * akpm: jbd2_journal_write_metadata_buffer() sets
629                  * new_bh->b_transaction to commit_transaction.
630                  * We need to clean this up before we release new_bh
631                  * (which is of type BJ_IO)
632                  */
633                 JBUFFER_TRACE(jh, "ph3: write metadata");
634                 flags = jbd2_journal_write_metadata_buffer(commit_transaction,
635                                                       jh, &new_jh, blocknr);
636                 set_bit(BH_JWrite, &jh2bh(new_jh)->b_state);
637                 wbuf[bufs++] = jh2bh(new_jh);
638
639                 /* Record the new block's tag in the current descriptor
640                    buffer */
641
642                 tag_flag = 0;
643                 if (flags & 1)
644                         tag_flag |= JBD2_FLAG_ESCAPE;
645                 if (!first_tag)
646                         tag_flag |= JBD2_FLAG_SAME_UUID;
647
648                 tag = (journal_block_tag_t *) tagp;
649                 write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr);
650                 tag->t_flags = cpu_to_be32(tag_flag);
651                 tagp += tag_bytes;
652                 space_left -= tag_bytes;
653
654                 if (first_tag) {
655                         memcpy (tagp, journal->j_uuid, 16);
656                         tagp += 16;
657                         space_left -= 16;
658                         first_tag = 0;
659                 }
660
661                 /* If there's no more to do, or if the descriptor is full,
662                    let the IO rip! */
663
664                 if (bufs == journal->j_wbufsize ||
665                     commit_transaction->t_buffers == NULL ||
666                     space_left < tag_bytes + 16) {
667
668                         jbd_debug(4, "JBD: Submit %d IOs\n", bufs);
669
670                         /* Write an end-of-descriptor marker before
671                            submitting the IOs.  "tag" still points to
672                            the last tag we set up. */
673
674                         tag->t_flags |= cpu_to_be32(JBD2_FLAG_LAST_TAG);
675
676 start_journal_io:
677                         for (i = 0; i < bufs; i++) {
678                                 struct buffer_head *bh = wbuf[i];
679                                 /*
680                                  * Compute checksum.
681                                  */
682                                 if (JBD2_HAS_COMPAT_FEATURE(journal,
683                                         JBD2_FEATURE_COMPAT_CHECKSUM)) {
684                                         crc32_sum =
685                                             jbd2_checksum_data(crc32_sum, bh);
686                                 }
687
688                                 lock_buffer(bh);
689                                 clear_buffer_dirty(bh);
690                                 set_buffer_uptodate(bh);
691                                 bh->b_end_io = journal_end_buffer_io_sync;
692                                 submit_bh(write_op, bh);
693                         }
694                         cond_resched();
695                         stats.u.run.rs_blocks_logged += bufs;
696
697                         /* Force a new descriptor to be generated next
698                            time round the loop. */
699                         descriptor = NULL;
700                         bufs = 0;
701                 }
702         }
703
704         /* Done it all: now write the commit record asynchronously. */
705
706         if (JBD2_HAS_INCOMPAT_FEATURE(journal,
707                 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
708                 err = journal_submit_commit_record(journal, commit_transaction,
709                                                  &cbh, crc32_sum);
710                 if (err)
711                         __jbd2_journal_abort_hard(journal);
712         }
713
714         /*
715          * This is the right place to wait for data buffers both for ASYNC
716          * and !ASYNC commit. If commit is ASYNC, we need to wait only after
717          * the commit block went to disk (which happens above). If commit is
718          * SYNC, we need to wait for data buffers before we start writing
719          * commit block, which happens below in such setting.
720          */
721         err = journal_finish_inode_data_buffers(journal, commit_transaction);
722         if (err) {
723                 printk(KERN_WARNING
724                         "JBD2: Detected IO errors while flushing file data "
725                        "on %s\n", journal->j_devname);
726                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
727                         jbd2_journal_abort(journal, err);
728                 err = 0;
729         }
730
731         /* Lo and behold: we have just managed to send a transaction to
732            the log.  Before we can commit it, wait for the IO so far to
733            complete.  Control buffers being written are on the
734            transaction's t_log_list queue, and metadata buffers are on
735            the t_iobuf_list queue.
736
737            Wait for the buffers in reverse order.  That way we are
738            less likely to be woken up until all IOs have completed, and
739            so we incur less scheduling load.
740         */
741
742         jbd_debug(3, "JBD: commit phase 3\n");
743
744         /*
745          * akpm: these are BJ_IO, and j_list_lock is not needed.
746          * See __journal_try_to_free_buffer.
747          */
748 wait_for_iobuf:
749         while (commit_transaction->t_iobuf_list != NULL) {
750                 struct buffer_head *bh;
751
752                 jh = commit_transaction->t_iobuf_list->b_tprev;
753                 bh = jh2bh(jh);
754                 if (buffer_locked(bh)) {
755                         wait_on_buffer(bh);
756                         goto wait_for_iobuf;
757                 }
758                 if (cond_resched())
759                         goto wait_for_iobuf;
760
761                 if (unlikely(!buffer_uptodate(bh)))
762                         err = -EIO;
763
764                 clear_buffer_jwrite(bh);
765
766                 JBUFFER_TRACE(jh, "ph4: unfile after journal write");
767                 jbd2_journal_unfile_buffer(journal, jh);
768
769                 /*
770                  * ->t_iobuf_list should contain only dummy buffer_heads
771                  * which were created by jbd2_journal_write_metadata_buffer().
772                  */
773                 BUFFER_TRACE(bh, "dumping temporary bh");
774                 jbd2_journal_put_journal_head(jh);
775                 __brelse(bh);
776                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
777                 free_buffer_head(bh);
778
779                 /* We also have to unlock and free the corresponding
780                    shadowed buffer */
781                 jh = commit_transaction->t_shadow_list->b_tprev;
782                 bh = jh2bh(jh);
783                 clear_bit(BH_JWrite, &bh->b_state);
784                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
785
786                 /* The metadata is now released for reuse, but we need
787                    to remember it against this transaction so that when
788                    we finally commit, we can do any checkpointing
789                    required. */
790                 JBUFFER_TRACE(jh, "file as BJ_Forget");
791                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
792                 /* Wake up any transactions which were waiting for this
793                    IO to complete */
794                 wake_up_bit(&bh->b_state, BH_Unshadow);
795                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
796                 __brelse(bh);
797         }
798
799         J_ASSERT (commit_transaction->t_shadow_list == NULL);
800
801         jbd_debug(3, "JBD: commit phase 4\n");
802
803         /* Here we wait for the revoke record and descriptor record buffers */
804  wait_for_ctlbuf:
805         while (commit_transaction->t_log_list != NULL) {
806                 struct buffer_head *bh;
807
808                 jh = commit_transaction->t_log_list->b_tprev;
809                 bh = jh2bh(jh);
810                 if (buffer_locked(bh)) {
811                         wait_on_buffer(bh);
812                         goto wait_for_ctlbuf;
813                 }
814                 if (cond_resched())
815                         goto wait_for_ctlbuf;
816
817                 if (unlikely(!buffer_uptodate(bh)))
818                         err = -EIO;
819
820                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
821                 clear_buffer_jwrite(bh);
822                 jbd2_journal_unfile_buffer(journal, jh);
823                 jbd2_journal_put_journal_head(jh);
824                 __brelse(bh);           /* One for getblk */
825                 /* AKPM: bforget here */
826         }
827
828         if (err)
829                 jbd2_journal_abort(journal, err);
830
831         jbd_debug(3, "JBD: commit phase 5\n");
832
833         if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
834                 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
835                 err = journal_submit_commit_record(journal, commit_transaction,
836                                                 &cbh, crc32_sum);
837                 if (err)
838                         __jbd2_journal_abort_hard(journal);
839         }
840         if (!err && !is_journal_aborted(journal))
841                 err = journal_wait_on_commit_record(journal, cbh);
842
843         if (err)
844                 jbd2_journal_abort(journal, err);
845
846         /* End of a transaction!  Finally, we can do checkpoint
847            processing: any buffers committed as a result of this
848            transaction can be removed from any checkpoint list it was on
849            before. */
850
851         jbd_debug(3, "JBD: commit phase 6\n");
852
853         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
854         J_ASSERT(commit_transaction->t_buffers == NULL);
855         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
856         J_ASSERT(commit_transaction->t_iobuf_list == NULL);
857         J_ASSERT(commit_transaction->t_shadow_list == NULL);
858         J_ASSERT(commit_transaction->t_log_list == NULL);
859
860 restart_loop:
861         /*
862          * As there are other places (journal_unmap_buffer()) adding buffers
863          * to this list we have to be careful and hold the j_list_lock.
864          */
865         spin_lock(&journal->j_list_lock);
866         while (commit_transaction->t_forget) {
867                 transaction_t *cp_transaction;
868                 struct buffer_head *bh;
869
870                 jh = commit_transaction->t_forget;
871                 spin_unlock(&journal->j_list_lock);
872                 bh = jh2bh(jh);
873                 jbd_lock_bh_state(bh);
874                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction ||
875                         jh->b_transaction == journal->j_running_transaction);
876
877                 /*
878                  * If there is undo-protected committed data against
879                  * this buffer, then we can remove it now.  If it is a
880                  * buffer needing such protection, the old frozen_data
881                  * field now points to a committed version of the
882                  * buffer, so rotate that field to the new committed
883                  * data.
884                  *
885                  * Otherwise, we can just throw away the frozen data now.
886                  *
887                  * We also know that the frozen data has already fired
888                  * its triggers if they exist, so we can clear that too.
889                  */
890                 if (jh->b_committed_data) {
891                         jbd2_free(jh->b_committed_data, bh->b_size);
892                         jh->b_committed_data = NULL;
893                         if (jh->b_frozen_data) {
894                                 jh->b_committed_data = jh->b_frozen_data;
895                                 jh->b_frozen_data = NULL;
896                                 jh->b_frozen_triggers = NULL;
897                         }
898                 } else if (jh->b_frozen_data) {
899                         jbd2_free(jh->b_frozen_data, bh->b_size);
900                         jh->b_frozen_data = NULL;
901                         jh->b_frozen_triggers = NULL;
902                 }
903
904                 spin_lock(&journal->j_list_lock);
905                 cp_transaction = jh->b_cp_transaction;
906                 if (cp_transaction) {
907                         JBUFFER_TRACE(jh, "remove from old cp transaction");
908                         cp_transaction->t_chp_stats.cs_dropped++;
909                         __jbd2_journal_remove_checkpoint(jh);
910                 }
911
912                 /* Only re-checkpoint the buffer_head if it is marked
913                  * dirty.  If the buffer was added to the BJ_Forget list
914                  * by jbd2_journal_forget, it may no longer be dirty and
915                  * there's no point in keeping a checkpoint record for
916                  * it. */
917
918                 /* A buffer which has been freed while still being
919                  * journaled by a previous transaction may end up still
920                  * being dirty here, but we want to avoid writing back
921                  * that buffer in the future now that the last use has
922                  * been committed.  That's not only a performance gain,
923                  * it also stops aliasing problems if the buffer is left
924                  * behind for writeback and gets reallocated for another
925                  * use in a different page. */
926                 if (buffer_freed(bh)) {
927                         clear_buffer_freed(bh);
928                         clear_buffer_jbddirty(bh);
929                 }
930
931                 if (buffer_jbddirty(bh)) {
932                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
933                         __jbd2_journal_insert_checkpoint(jh, commit_transaction);
934                         if (is_journal_aborted(journal))
935                                 clear_buffer_jbddirty(bh);
936                         JBUFFER_TRACE(jh, "refile for checkpoint writeback");
937                         __jbd2_journal_refile_buffer(jh);
938                         jbd_unlock_bh_state(bh);
939                 } else {
940                         J_ASSERT_BH(bh, !buffer_dirty(bh));
941                         /* The buffer on BJ_Forget list and not jbddirty means
942                          * it has been freed by this transaction and hence it
943                          * could not have been reallocated until this
944                          * transaction has committed. *BUT* it could be
945                          * reallocated once we have written all the data to
946                          * disk and before we process the buffer on BJ_Forget
947                          * list. */
948                         JBUFFER_TRACE(jh, "refile or unfile freed buffer");
949                         __jbd2_journal_refile_buffer(jh);
950                         if (!jh->b_transaction) {
951                                 jbd_unlock_bh_state(bh);
952                                  /* needs a brelse */
953                                 jbd2_journal_remove_journal_head(bh);
954                                 release_buffer_page(bh);
955                         } else
956                                 jbd_unlock_bh_state(bh);
957                 }
958                 cond_resched_lock(&journal->j_list_lock);
959         }
960         spin_unlock(&journal->j_list_lock);
961         /*
962          * This is a bit sleazy.  We use j_list_lock to protect transition
963          * of a transaction into T_FINISHED state and calling
964          * __jbd2_journal_drop_transaction(). Otherwise we could race with
965          * other checkpointing code processing the transaction...
966          */
967         spin_lock(&journal->j_state_lock);
968         spin_lock(&journal->j_list_lock);
969         /*
970          * Now recheck if some buffers did not get attached to the transaction
971          * while the lock was dropped...
972          */
973         if (commit_transaction->t_forget) {
974                 spin_unlock(&journal->j_list_lock);
975                 spin_unlock(&journal->j_state_lock);
976                 goto restart_loop;
977         }
978
979         /* Done with this transaction! */
980
981         jbd_debug(3, "JBD: commit phase 7\n");
982
983         J_ASSERT(commit_transaction->t_state == T_COMMIT);
984
985         commit_transaction->t_start = jiffies;
986         stats.u.run.rs_logging = jbd2_time_diff(stats.u.run.rs_logging,
987                                                 commit_transaction->t_start);
988
989         /*
990          * File the transaction for history
991          */
992         stats.ts_type = JBD2_STATS_RUN;
993         stats.ts_tid = commit_transaction->t_tid;
994         stats.u.run.rs_handle_count = commit_transaction->t_handle_count;
995         spin_lock(&journal->j_history_lock);
996         memcpy(journal->j_history + journal->j_history_cur, &stats,
997                         sizeof(stats));
998         if (++journal->j_history_cur == journal->j_history_max)
999                 journal->j_history_cur = 0;
1000
1001         /*
1002          * Calculate overall stats
1003          */
1004         journal->j_stats.ts_tid++;
1005         journal->j_stats.u.run.rs_wait += stats.u.run.rs_wait;
1006         journal->j_stats.u.run.rs_running += stats.u.run.rs_running;
1007         journal->j_stats.u.run.rs_locked += stats.u.run.rs_locked;
1008         journal->j_stats.u.run.rs_flushing += stats.u.run.rs_flushing;
1009         journal->j_stats.u.run.rs_logging += stats.u.run.rs_logging;
1010         journal->j_stats.u.run.rs_handle_count += stats.u.run.rs_handle_count;
1011         journal->j_stats.u.run.rs_blocks += stats.u.run.rs_blocks;
1012         journal->j_stats.u.run.rs_blocks_logged += stats.u.run.rs_blocks_logged;
1013         spin_unlock(&journal->j_history_lock);
1014
1015         commit_transaction->t_state = T_FINISHED;
1016         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1017         journal->j_commit_sequence = commit_transaction->t_tid;
1018         journal->j_committing_transaction = NULL;
1019         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1020
1021         /*
1022          * weight the commit time higher than the average time so we don't
1023          * react too strongly to vast changes in the commit time
1024          */
1025         if (likely(journal->j_average_commit_time))
1026                 journal->j_average_commit_time = (commit_time +
1027                                 journal->j_average_commit_time*3) / 4;
1028         else
1029                 journal->j_average_commit_time = commit_time;
1030         spin_unlock(&journal->j_state_lock);
1031
1032         if (commit_transaction->t_checkpoint_list == NULL &&
1033             commit_transaction->t_checkpoint_io_list == NULL) {
1034                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1035                 to_free = 1;
1036         } else {
1037                 if (journal->j_checkpoint_transactions == NULL) {
1038                         journal->j_checkpoint_transactions = commit_transaction;
1039                         commit_transaction->t_cpnext = commit_transaction;
1040                         commit_transaction->t_cpprev = commit_transaction;
1041                 } else {
1042                         commit_transaction->t_cpnext =
1043                                 journal->j_checkpoint_transactions;
1044                         commit_transaction->t_cpprev =
1045                                 commit_transaction->t_cpnext->t_cpprev;
1046                         commit_transaction->t_cpnext->t_cpprev =
1047                                 commit_transaction;
1048                         commit_transaction->t_cpprev->t_cpnext =
1049                                 commit_transaction;
1050                 }
1051         }
1052         spin_unlock(&journal->j_list_lock);
1053
1054         if (journal->j_commit_callback)
1055                 journal->j_commit_callback(journal, commit_transaction);
1056
1057         trace_mark(jbd2_end_commit, "dev %s transaction %d head %d",
1058                    journal->j_devname, commit_transaction->t_tid,
1059                    journal->j_tail_sequence);
1060         jbd_debug(1, "JBD: commit %d complete, head %d\n",
1061                   journal->j_commit_sequence, journal->j_tail_sequence);
1062         if (to_free)
1063                 kfree(commit_transaction);
1064
1065         wake_up(&journal->j_wait_done_commit);
1066 }