xref: /openbmc/linux/fs/jbd2/commit.c (revision 17bfcd6a)
1  // SPDX-License-Identifier: GPL-2.0+
2  /*
3   * linux/fs/jbd2/commit.c
4   *
5   * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
6   *
7   * Copyright 1998 Red Hat corp --- All Rights Reserved
8   *
9   * Journal commit routines for the generic filesystem journaling code;
10   * part of the ext2fs journaling system.
11   */
12  
13  #include <linux/time.h>
14  #include <linux/fs.h>
15  #include <linux/jbd2.h>
16  #include <linux/errno.h>
17  #include <linux/slab.h>
18  #include <linux/mm.h>
19  #include <linux/pagemap.h>
20  #include <linux/jiffies.h>
21  #include <linux/crc32.h>
22  #include <linux/writeback.h>
23  #include <linux/backing-dev.h>
24  #include <linux/bio.h>
25  #include <linux/blkdev.h>
26  #include <linux/bitops.h>
27  #include <trace/events/jbd2.h>
28  
29  /*
30   * IO end handler for temporary buffer_heads handling writes to the journal.
31   */
32  static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
33  {
34  	struct buffer_head *orig_bh = bh->b_private;
35  
36  	BUFFER_TRACE(bh, "");
37  	if (uptodate)
38  		set_buffer_uptodate(bh);
39  	else
40  		clear_buffer_uptodate(bh);
41  	if (orig_bh) {
42  		clear_bit_unlock(BH_Shadow, &orig_bh->b_state);
43  		smp_mb__after_atomic();
44  		wake_up_bit(&orig_bh->b_state, BH_Shadow);
45  	}
46  	unlock_buffer(bh);
47  }
48  
49  /*
50   * When an ext4 file is truncated, it is possible that some pages are not
51   * successfully freed, because they are attached to a committing transaction.
52   * After the transaction commits, these pages are left on the LRU, with no
53   * ->mapping, and with attached buffers.  These pages are trivially reclaimable
54   * by the VM, but their apparent absence upsets the VM accounting, and it makes
55   * the numbers in /proc/meminfo look odd.
56   *
57   * So here, we have a buffer which has just come off the forget list.  Look to
58   * see if we can strip all buffers from the backing page.
59   *
60   * Called under lock_journal(), and possibly under journal_datalist_lock.  The
61   * caller provided us with a ref against the buffer, and we drop that here.
62   */
63  static void release_buffer_page(struct buffer_head *bh)
64  {
65  	struct folio *folio;
66  
67  	if (buffer_dirty(bh))
68  		goto nope;
69  	if (atomic_read(&bh->b_count) != 1)
70  		goto nope;
71  	folio = bh->b_folio;
72  	if (folio->mapping)
73  		goto nope;
74  
75  	/* OK, it's a truncated page */
76  	if (!folio_trylock(folio))
77  		goto nope;
78  
79  	folio_get(folio);
80  	__brelse(bh);
81  	try_to_free_buffers(folio);
82  	folio_unlock(folio);
83  	folio_put(folio);
84  	return;
85  
86  nope:
87  	__brelse(bh);
88  }
89  
90  static void jbd2_commit_block_csum_set(journal_t *j, struct buffer_head *bh)
91  {
92  	struct commit_header *h;
93  	__u32 csum;
94  
95  	if (!jbd2_journal_has_csum_v2or3(j))
96  		return;
97  
98  	h = (struct commit_header *)(bh->b_data);
99  	h->h_chksum_type = 0;
100  	h->h_chksum_size = 0;
101  	h->h_chksum[0] = 0;
102  	csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
103  	h->h_chksum[0] = cpu_to_be32(csum);
104  }
105  
106  /*
107   * Done it all: now submit the commit record.  We should have
108   * cleaned up our previous buffers by now, so if we are in abort
109   * mode we can now just skip the rest of the journal write
110   * entirely.
111   *
112   * Returns 1 if the journal needs to be aborted or 0 on success
113   */
114  static int journal_submit_commit_record(journal_t *journal,
115  					transaction_t *commit_transaction,
116  					struct buffer_head **cbh,
117  					__u32 crc32_sum)
118  {
119  	struct commit_header *tmp;
120  	struct buffer_head *bh;
121  	struct timespec64 now;
122  	blk_opf_t write_flags = REQ_OP_WRITE | REQ_SYNC;
123  
124  	*cbh = NULL;
125  
126  	if (is_journal_aborted(journal))
127  		return 0;
128  
129  	bh = jbd2_journal_get_descriptor_buffer(commit_transaction,
130  						JBD2_COMMIT_BLOCK);
131  	if (!bh)
132  		return 1;
133  
134  	tmp = (struct commit_header *)bh->b_data;
135  	ktime_get_coarse_real_ts64(&now);
136  	tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
137  	tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);
138  
139  	if (jbd2_has_feature_checksum(journal)) {
140  		tmp->h_chksum_type 	= JBD2_CRC32_CHKSUM;
141  		tmp->h_chksum_size 	= JBD2_CRC32_CHKSUM_SIZE;
142  		tmp->h_chksum[0] 	= cpu_to_be32(crc32_sum);
143  	}
144  	jbd2_commit_block_csum_set(journal, bh);
145  
146  	BUFFER_TRACE(bh, "submit commit block");
147  	lock_buffer(bh);
148  	clear_buffer_dirty(bh);
149  	set_buffer_uptodate(bh);
150  	bh->b_end_io = journal_end_buffer_io_sync;
151  
152  	if (journal->j_flags & JBD2_BARRIER &&
153  	    !jbd2_has_feature_async_commit(journal))
154  		write_flags |= REQ_PREFLUSH | REQ_FUA;
155  
156  	submit_bh(write_flags, bh);
157  	*cbh = bh;
158  	return 0;
159  }
160  
161  /*
162   * This function along with journal_submit_commit_record
163   * allows to write the commit record asynchronously.
164   */
165  static int journal_wait_on_commit_record(journal_t *journal,
166  					 struct buffer_head *bh)
167  {
168  	int ret = 0;
169  
170  	clear_buffer_dirty(bh);
171  	wait_on_buffer(bh);
172  
173  	if (unlikely(!buffer_uptodate(bh)))
174  		ret = -EIO;
175  	put_bh(bh);            /* One for getblk() */
176  
177  	return ret;
178  }
179  
180  /* Send all the data buffers related to an inode */
181  int jbd2_submit_inode_data(journal_t *journal, struct jbd2_inode *jinode)
182  {
183  	if (!jinode || !(jinode->i_flags & JI_WRITE_DATA))
184  		return 0;
185  
186  	trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
187  	return journal->j_submit_inode_data_buffers(jinode);
188  
189  }
190  EXPORT_SYMBOL(jbd2_submit_inode_data);
191  
192  int jbd2_wait_inode_data(journal_t *journal, struct jbd2_inode *jinode)
193  {
194  	if (!jinode || !(jinode->i_flags & JI_WAIT_DATA) ||
195  		!jinode->i_vfs_inode || !jinode->i_vfs_inode->i_mapping)
196  		return 0;
197  	return filemap_fdatawait_range_keep_errors(
198  		jinode->i_vfs_inode->i_mapping, jinode->i_dirty_start,
199  		jinode->i_dirty_end);
200  }
201  EXPORT_SYMBOL(jbd2_wait_inode_data);
202  
203  /*
204   * Submit all the data buffers of inode associated with the transaction to
205   * disk.
206   *
207   * We are in a committing transaction. Therefore no new inode can be added to
208   * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently
209   * operate on from being released while we write out pages.
210   */
211  static int journal_submit_data_buffers(journal_t *journal,
212  		transaction_t *commit_transaction)
213  {
214  	struct jbd2_inode *jinode;
215  	int err, ret = 0;
216  
217  	spin_lock(&journal->j_list_lock);
218  	list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
219  		if (!(jinode->i_flags & JI_WRITE_DATA))
220  			continue;
221  		jinode->i_flags |= JI_COMMIT_RUNNING;
222  		spin_unlock(&journal->j_list_lock);
223  		/* submit the inode data buffers. */
224  		trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
225  		if (journal->j_submit_inode_data_buffers) {
226  			err = journal->j_submit_inode_data_buffers(jinode);
227  			if (!ret)
228  				ret = err;
229  		}
230  		spin_lock(&journal->j_list_lock);
231  		J_ASSERT(jinode->i_transaction == commit_transaction);
232  		jinode->i_flags &= ~JI_COMMIT_RUNNING;
233  		smp_mb();
234  		wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
235  	}
236  	spin_unlock(&journal->j_list_lock);
237  	return ret;
238  }
239  
240  int jbd2_journal_finish_inode_data_buffers(struct jbd2_inode *jinode)
241  {
242  	struct address_space *mapping = jinode->i_vfs_inode->i_mapping;
243  
244  	return filemap_fdatawait_range_keep_errors(mapping,
245  						   jinode->i_dirty_start,
246  						   jinode->i_dirty_end);
247  }
248  
249  /*
250   * Wait for data submitted for writeout, refile inodes to proper
251   * transaction if needed.
252   *
253   */
254  static int journal_finish_inode_data_buffers(journal_t *journal,
255  		transaction_t *commit_transaction)
256  {
257  	struct jbd2_inode *jinode, *next_i;
258  	int err, ret = 0;
259  
260  	/* For locking, see the comment in journal_submit_data_buffers() */
261  	spin_lock(&journal->j_list_lock);
262  	list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
263  		if (!(jinode->i_flags & JI_WAIT_DATA))
264  			continue;
265  		jinode->i_flags |= JI_COMMIT_RUNNING;
266  		spin_unlock(&journal->j_list_lock);
267  		/* wait for the inode data buffers writeout. */
268  		if (journal->j_finish_inode_data_buffers) {
269  			err = journal->j_finish_inode_data_buffers(jinode);
270  			if (!ret)
271  				ret = err;
272  		}
273  		spin_lock(&journal->j_list_lock);
274  		jinode->i_flags &= ~JI_COMMIT_RUNNING;
275  		smp_mb();
276  		wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
277  	}
278  
279  	/* Now refile inode to proper lists */
280  	list_for_each_entry_safe(jinode, next_i,
281  				 &commit_transaction->t_inode_list, i_list) {
282  		list_del(&jinode->i_list);
283  		if (jinode->i_next_transaction) {
284  			jinode->i_transaction = jinode->i_next_transaction;
285  			jinode->i_next_transaction = NULL;
286  			list_add(&jinode->i_list,
287  				&jinode->i_transaction->t_inode_list);
288  		} else {
289  			jinode->i_transaction = NULL;
290  			jinode->i_dirty_start = 0;
291  			jinode->i_dirty_end = 0;
292  		}
293  	}
294  	spin_unlock(&journal->j_list_lock);
295  
296  	return ret;
297  }
298  
299  static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
300  {
301  	char *addr;
302  	__u32 checksum;
303  
304  	addr = kmap_local_folio(bh->b_folio, bh_offset(bh));
305  	checksum = crc32_be(crc32_sum, addr, bh->b_size);
306  	kunmap_local(addr);
307  
308  	return checksum;
309  }
310  
311  static void write_tag_block(journal_t *j, journal_block_tag_t *tag,
312  				   unsigned long long block)
313  {
314  	tag->t_blocknr = cpu_to_be32(block & (u32)~0);
315  	if (jbd2_has_feature_64bit(j))
316  		tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
317  }
318  
319  static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
320  				    struct buffer_head *bh, __u32 sequence)
321  {
322  	journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
323  	__u8 *addr;
324  	__u32 csum32;
325  	__be32 seq;
326  
327  	if (!jbd2_journal_has_csum_v2or3(j))
328  		return;
329  
330  	seq = cpu_to_be32(sequence);
331  	addr = kmap_local_folio(bh->b_folio, bh_offset(bh));
332  	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
333  	csum32 = jbd2_chksum(j, csum32, addr, bh->b_size);
334  	kunmap_local(addr);
335  
336  	if (jbd2_has_feature_csum3(j))
337  		tag3->t_checksum = cpu_to_be32(csum32);
338  	else
339  		tag->t_checksum = cpu_to_be16(csum32);
340  }
341  /*
342   * jbd2_journal_commit_transaction
343   *
344   * The primary function for committing a transaction to the log.  This
345   * function is called by the journal thread to begin a complete commit.
346   */
347  void jbd2_journal_commit_transaction(journal_t *journal)
348  {
349  	struct transaction_stats_s stats;
350  	transaction_t *commit_transaction;
351  	struct journal_head *jh;
352  	struct buffer_head *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_block_tag_t *tag = NULL;
362  	int space_left = 0;
363  	int first_tag = 0;
364  	int tag_flag;
365  	int i;
366  	int tag_bytes = journal_tag_bytes(journal);
367  	struct buffer_head *cbh = NULL; /* For transactional checksums */
368  	__u32 crc32_sum = ~0;
369  	struct blk_plug plug;
370  	/* Tail of the journal */
371  	unsigned long first_block;
372  	tid_t first_tid;
373  	int update_tail;
374  	int csum_size = 0;
375  	LIST_HEAD(io_bufs);
376  	LIST_HEAD(log_bufs);
377  
378  	if (jbd2_journal_has_csum_v2or3(journal))
379  		csum_size = sizeof(struct jbd2_journal_block_tail);
380  
381  	/*
382  	 * First job: lock down the current transaction and wait for
383  	 * all outstanding updates to complete.
384  	 */
385  
386  	/* Do we need to erase the effects of a prior jbd2_journal_flush? */
387  	if (journal->j_flags & JBD2_FLUSHED) {
388  		jbd2_debug(3, "super block updated\n");
389  		mutex_lock_io(&journal->j_checkpoint_mutex);
390  		/*
391  		 * We hold j_checkpoint_mutex so tail cannot change under us.
392  		 * We don't need any special data guarantees for writing sb
393  		 * since journal is empty and it is ok for write to be
394  		 * flushed only with transaction commit.
395  		 */
396  		jbd2_journal_update_sb_log_tail(journal,
397  						journal->j_tail_sequence,
398  						journal->j_tail,
399  						REQ_SYNC);
400  		mutex_unlock(&journal->j_checkpoint_mutex);
401  	} else {
402  		jbd2_debug(3, "superblock not updated\n");
403  	}
404  
405  	J_ASSERT(journal->j_running_transaction != NULL);
406  	J_ASSERT(journal->j_committing_transaction == NULL);
407  
408  	write_lock(&journal->j_state_lock);
409  	journal->j_flags |= JBD2_FULL_COMMIT_ONGOING;
410  	while (journal->j_flags & JBD2_FAST_COMMIT_ONGOING) {
411  		DEFINE_WAIT(wait);
412  
413  		prepare_to_wait(&journal->j_fc_wait, &wait,
414  				TASK_UNINTERRUPTIBLE);
415  		write_unlock(&journal->j_state_lock);
416  		schedule();
417  		write_lock(&journal->j_state_lock);
418  		finish_wait(&journal->j_fc_wait, &wait);
419  		/*
420  		 * TODO: by blocking fast commits here, we are increasing
421  		 * fsync() latency slightly. Strictly speaking, we don't need
422  		 * to block fast commits until the transaction enters T_FLUSH
423  		 * state. So an optimization is possible where we block new fast
424  		 * commits here and wait for existing ones to complete
425  		 * just before we enter T_FLUSH. That way, the existing fast
426  		 * commits and this full commit can proceed parallely.
427  		 */
428  	}
429  	write_unlock(&journal->j_state_lock);
430  
431  	commit_transaction = journal->j_running_transaction;
432  
433  	trace_jbd2_start_commit(journal, commit_transaction);
434  	jbd2_debug(1, "JBD2: starting commit of transaction %d\n",
435  			commit_transaction->t_tid);
436  
437  	write_lock(&journal->j_state_lock);
438  	journal->j_fc_off = 0;
439  	J_ASSERT(commit_transaction->t_state == T_RUNNING);
440  	commit_transaction->t_state = T_LOCKED;
441  
442  	trace_jbd2_commit_locking(journal, commit_transaction);
443  	stats.run.rs_wait = commit_transaction->t_max_wait;
444  	stats.run.rs_request_delay = 0;
445  	stats.run.rs_locked = jiffies;
446  	if (commit_transaction->t_requested)
447  		stats.run.rs_request_delay =
448  			jbd2_time_diff(commit_transaction->t_requested,
449  				       stats.run.rs_locked);
450  	stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
451  					      stats.run.rs_locked);
452  
453  	// waits for any t_updates to finish
454  	jbd2_journal_wait_updates(journal);
455  
456  	commit_transaction->t_state = T_SWITCH;
457  
458  	J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
459  			journal->j_max_transaction_buffers);
460  
461  	/*
462  	 * First thing we are allowed to do is to discard any remaining
463  	 * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
464  	 * that there are no such buffers: if a large filesystem
465  	 * operation like a truncate needs to split itself over multiple
466  	 * transactions, then it may try to do a jbd2_journal_restart() while
467  	 * there are still BJ_Reserved buffers outstanding.  These must
468  	 * be released cleanly from the current transaction.
469  	 *
470  	 * In this case, the filesystem must still reserve write access
471  	 * again before modifying the buffer in the new transaction, but
472  	 * we do not require it to remember exactly which old buffers it
473  	 * has reserved.  This is consistent with the existing behaviour
474  	 * that multiple jbd2_journal_get_write_access() calls to the same
475  	 * buffer are perfectly permissible.
476  	 * We use journal->j_state_lock here to serialize processing of
477  	 * t_reserved_list with eviction of buffers from journal_unmap_buffer().
478  	 */
479  	while (commit_transaction->t_reserved_list) {
480  		jh = commit_transaction->t_reserved_list;
481  		JBUFFER_TRACE(jh, "reserved, unused: refile");
482  		/*
483  		 * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
484  		 * leave undo-committed data.
485  		 */
486  		if (jh->b_committed_data) {
487  			struct buffer_head *bh = jh2bh(jh);
488  
489  			spin_lock(&jh->b_state_lock);
490  			jbd2_free(jh->b_committed_data, bh->b_size);
491  			jh->b_committed_data = NULL;
492  			spin_unlock(&jh->b_state_lock);
493  		}
494  		jbd2_journal_refile_buffer(journal, jh);
495  	}
496  
497  	write_unlock(&journal->j_state_lock);
498  	/*
499  	 * Now try to drop any written-back buffers from the journal's
500  	 * checkpoint lists.  We do this *before* commit because it potentially
501  	 * frees some memory
502  	 */
503  	spin_lock(&journal->j_list_lock);
504  	__jbd2_journal_clean_checkpoint_list(journal, false);
505  	spin_unlock(&journal->j_list_lock);
506  
507  	jbd2_debug(3, "JBD2: commit phase 1\n");
508  
509  	/*
510  	 * Clear revoked flag to reflect there is no revoked buffers
511  	 * in the next transaction which is going to be started.
512  	 */
513  	jbd2_clear_buffer_revoked_flags(journal);
514  
515  	/*
516  	 * Switch to a new revoke table.
517  	 */
518  	jbd2_journal_switch_revoke_table(journal);
519  
520  	write_lock(&journal->j_state_lock);
521  	/*
522  	 * Reserved credits cannot be claimed anymore, free them
523  	 */
524  	atomic_sub(atomic_read(&journal->j_reserved_credits),
525  		   &commit_transaction->t_outstanding_credits);
526  
527  	trace_jbd2_commit_flushing(journal, commit_transaction);
528  	stats.run.rs_flushing = jiffies;
529  	stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
530  					     stats.run.rs_flushing);
531  
532  	commit_transaction->t_state = T_FLUSH;
533  	journal->j_committing_transaction = commit_transaction;
534  	journal->j_running_transaction = NULL;
535  	start_time = ktime_get();
536  	commit_transaction->t_log_start = journal->j_head;
537  	wake_up_all(&journal->j_wait_transaction_locked);
538  	write_unlock(&journal->j_state_lock);
539  
540  	jbd2_debug(3, "JBD2: commit phase 2a\n");
541  
542  	/*
543  	 * Now start flushing things to disk, in the order they appear
544  	 * on the transaction lists.  Data blocks go first.
545  	 */
546  	err = journal_submit_data_buffers(journal, commit_transaction);
547  	if (err)
548  		jbd2_journal_abort(journal, err);
549  
550  	blk_start_plug(&plug);
551  	jbd2_journal_write_revoke_records(commit_transaction, &log_bufs);
552  
553  	jbd2_debug(3, "JBD2: commit phase 2b\n");
554  
555  	/*
556  	 * Way to go: we have now written out all of the data for a
557  	 * transaction!  Now comes the tricky part: we need to write out
558  	 * metadata.  Loop over the transaction's entire buffer list:
559  	 */
560  	write_lock(&journal->j_state_lock);
561  	commit_transaction->t_state = T_COMMIT;
562  	write_unlock(&journal->j_state_lock);
563  
564  	trace_jbd2_commit_logging(journal, commit_transaction);
565  	stats.run.rs_logging = jiffies;
566  	stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
567  					       stats.run.rs_logging);
568  	stats.run.rs_blocks = commit_transaction->t_nr_buffers;
569  	stats.run.rs_blocks_logged = 0;
570  
571  	J_ASSERT(commit_transaction->t_nr_buffers <=
572  		 atomic_read(&commit_transaction->t_outstanding_credits));
573  
574  	err = 0;
575  	bufs = 0;
576  	descriptor = NULL;
577  	while (commit_transaction->t_buffers) {
578  
579  		/* Find the next buffer to be journaled... */
580  
581  		jh = commit_transaction->t_buffers;
582  
583  		/* If we're in abort mode, we just un-journal the buffer and
584  		   release it. */
585  
586  		if (is_journal_aborted(journal)) {
587  			clear_buffer_jbddirty(jh2bh(jh));
588  			JBUFFER_TRACE(jh, "journal is aborting: refile");
589  			jbd2_buffer_abort_trigger(jh,
590  						  jh->b_frozen_data ?
591  						  jh->b_frozen_triggers :
592  						  jh->b_triggers);
593  			jbd2_journal_refile_buffer(journal, jh);
594  			/* If that was the last one, we need to clean up
595  			 * any descriptor buffers which may have been
596  			 * already allocated, even if we are now
597  			 * aborting. */
598  			if (!commit_transaction->t_buffers)
599  				goto start_journal_io;
600  			continue;
601  		}
602  
603  		/* Make sure we have a descriptor block in which to
604  		   record the metadata buffer. */
605  
606  		if (!descriptor) {
607  			J_ASSERT (bufs == 0);
608  
609  			jbd2_debug(4, "JBD2: get descriptor\n");
610  
611  			descriptor = jbd2_journal_get_descriptor_buffer(
612  							commit_transaction,
613  							JBD2_DESCRIPTOR_BLOCK);
614  			if (!descriptor) {
615  				jbd2_journal_abort(journal, -EIO);
616  				continue;
617  			}
618  
619  			jbd2_debug(4, "JBD2: got buffer %llu (%p)\n",
620  				(unsigned long long)descriptor->b_blocknr,
621  				descriptor->b_data);
622  			tagp = &descriptor->b_data[sizeof(journal_header_t)];
623  			space_left = descriptor->b_size -
624  						sizeof(journal_header_t);
625  			first_tag = 1;
626  			set_buffer_jwrite(descriptor);
627  			set_buffer_dirty(descriptor);
628  			wbuf[bufs++] = descriptor;
629  
630  			/* Record it so that we can wait for IO
631                             completion later */
632  			BUFFER_TRACE(descriptor, "ph3: file as descriptor");
633  			jbd2_file_log_bh(&log_bufs, descriptor);
634  		}
635  
636  		/* Where is the buffer to be written? */
637  
638  		err = jbd2_journal_next_log_block(journal, &blocknr);
639  		/* If the block mapping failed, just abandon the buffer
640  		   and repeat this loop: we'll fall into the
641  		   refile-on-abort condition above. */
642  		if (err) {
643  			jbd2_journal_abort(journal, err);
644  			continue;
645  		}
646  
647  		/*
648  		 * start_this_handle() uses t_outstanding_credits to determine
649  		 * the free space in the log.
650  		 */
651  		atomic_dec(&commit_transaction->t_outstanding_credits);
652  
653  		/* Bump b_count to prevent truncate from stumbling over
654                     the shadowed buffer!  @@@ This can go if we ever get
655                     rid of the shadow pairing of buffers. */
656  		atomic_inc(&jh2bh(jh)->b_count);
657  
658  		/*
659  		 * Make a temporary IO buffer with which to write it out
660  		 * (this will requeue the metadata buffer to BJ_Shadow).
661  		 */
662  		set_bit(BH_JWrite, &jh2bh(jh)->b_state);
663  		JBUFFER_TRACE(jh, "ph3: write metadata");
664  		flags = jbd2_journal_write_metadata_buffer(commit_transaction,
665  						jh, &wbuf[bufs], blocknr);
666  		if (flags < 0) {
667  			jbd2_journal_abort(journal, flags);
668  			continue;
669  		}
670  		jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
671  
672  		/* Record the new block's tag in the current descriptor
673                     buffer */
674  
675  		tag_flag = 0;
676  		if (flags & 1)
677  			tag_flag |= JBD2_FLAG_ESCAPE;
678  		if (!first_tag)
679  			tag_flag |= JBD2_FLAG_SAME_UUID;
680  
681  		tag = (journal_block_tag_t *) tagp;
682  		write_tag_block(journal, tag, jh2bh(jh)->b_blocknr);
683  		tag->t_flags = cpu_to_be16(tag_flag);
684  		jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
685  					commit_transaction->t_tid);
686  		tagp += tag_bytes;
687  		space_left -= tag_bytes;
688  		bufs++;
689  
690  		if (first_tag) {
691  			memcpy (tagp, journal->j_uuid, 16);
692  			tagp += 16;
693  			space_left -= 16;
694  			first_tag = 0;
695  		}
696  
697  		/* If there's no more to do, or if the descriptor is full,
698  		   let the IO rip! */
699  
700  		if (bufs == journal->j_wbufsize ||
701  		    commit_transaction->t_buffers == NULL ||
702  		    space_left < tag_bytes + 16 + csum_size) {
703  
704  			jbd2_debug(4, "JBD2: Submit %d IOs\n", bufs);
705  
706  			/* Write an end-of-descriptor marker before
707                             submitting the IOs.  "tag" still points to
708                             the last tag we set up. */
709  
710  			tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
711  start_journal_io:
712  			if (descriptor)
713  				jbd2_descriptor_block_csum_set(journal,
714  							descriptor);
715  
716  			for (i = 0; i < bufs; i++) {
717  				struct buffer_head *bh = wbuf[i];
718  				/*
719  				 * Compute checksum.
720  				 */
721  				if (jbd2_has_feature_checksum(journal)) {
722  					crc32_sum =
723  					    jbd2_checksum_data(crc32_sum, bh);
724  				}
725  
726  				lock_buffer(bh);
727  				clear_buffer_dirty(bh);
728  				set_buffer_uptodate(bh);
729  				bh->b_end_io = journal_end_buffer_io_sync;
730  				submit_bh(REQ_OP_WRITE | REQ_SYNC, bh);
731  			}
732  			cond_resched();
733  
734  			/* Force a new descriptor to be generated next
735                             time round the loop. */
736  			descriptor = NULL;
737  			bufs = 0;
738  		}
739  	}
740  
741  	err = journal_finish_inode_data_buffers(journal, commit_transaction);
742  	if (err) {
743  		printk(KERN_WARNING
744  			"JBD2: Detected IO errors while flushing file data "
745  		       "on %s\n", journal->j_devname);
746  		if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
747  			jbd2_journal_abort(journal, err);
748  		err = 0;
749  	}
750  
751  	/*
752  	 * Get current oldest transaction in the log before we issue flush
753  	 * to the filesystem device. After the flush we can be sure that
754  	 * blocks of all older transactions are checkpointed to persistent
755  	 * storage and we will be safe to update journal start in the
756  	 * superblock with the numbers we get here.
757  	 */
758  	update_tail =
759  		jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
760  
761  	write_lock(&journal->j_state_lock);
762  	if (update_tail) {
763  		long freed = first_block - journal->j_tail;
764  
765  		if (first_block < journal->j_tail)
766  			freed += journal->j_last - journal->j_first;
767  		/* Update tail only if we free significant amount of space */
768  		if (freed < jbd2_journal_get_max_txn_bufs(journal))
769  			update_tail = 0;
770  	}
771  	J_ASSERT(commit_transaction->t_state == T_COMMIT);
772  	commit_transaction->t_state = T_COMMIT_DFLUSH;
773  	write_unlock(&journal->j_state_lock);
774  
775  	/*
776  	 * If the journal is not located on the file system device,
777  	 * then we must flush the file system device before we issue
778  	 * the commit record
779  	 */
780  	if (commit_transaction->t_need_data_flush &&
781  	    (journal->j_fs_dev != journal->j_dev) &&
782  	    (journal->j_flags & JBD2_BARRIER))
783  		blkdev_issue_flush(journal->j_fs_dev);
784  
785  	/* Done it all: now write the commit record asynchronously. */
786  	if (jbd2_has_feature_async_commit(journal)) {
787  		err = journal_submit_commit_record(journal, commit_transaction,
788  						 &cbh, crc32_sum);
789  		if (err)
790  			jbd2_journal_abort(journal, err);
791  	}
792  
793  	blk_finish_plug(&plug);
794  
795  	/* Lo and behold: we have just managed to send a transaction to
796             the log.  Before we can commit it, wait for the IO so far to
797             complete.  Control buffers being written are on the
798             transaction's t_log_list queue, and metadata buffers are on
799             the io_bufs list.
800  
801  	   Wait for the buffers in reverse order.  That way we are
802  	   less likely to be woken up until all IOs have completed, and
803  	   so we incur less scheduling load.
804  	*/
805  
806  	jbd2_debug(3, "JBD2: commit phase 3\n");
807  
808  	while (!list_empty(&io_bufs)) {
809  		struct buffer_head *bh = list_entry(io_bufs.prev,
810  						    struct buffer_head,
811  						    b_assoc_buffers);
812  
813  		wait_on_buffer(bh);
814  		cond_resched();
815  
816  		if (unlikely(!buffer_uptodate(bh)))
817  			err = -EIO;
818  		jbd2_unfile_log_bh(bh);
819  		stats.run.rs_blocks_logged++;
820  
821  		/*
822  		 * The list contains temporary buffer heads created by
823  		 * jbd2_journal_write_metadata_buffer().
824  		 */
825  		BUFFER_TRACE(bh, "dumping temporary bh");
826  		__brelse(bh);
827  		J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
828  		free_buffer_head(bh);
829  
830  		/* We also have to refile the corresponding shadowed buffer */
831  		jh = commit_transaction->t_shadow_list->b_tprev;
832  		bh = jh2bh(jh);
833  		clear_buffer_jwrite(bh);
834  		J_ASSERT_BH(bh, buffer_jbddirty(bh));
835  		J_ASSERT_BH(bh, !buffer_shadow(bh));
836  
837  		/* The metadata is now released for reuse, but we need
838                     to remember it against this transaction so that when
839                     we finally commit, we can do any checkpointing
840                     required. */
841  		JBUFFER_TRACE(jh, "file as BJ_Forget");
842  		jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
843  		JBUFFER_TRACE(jh, "brelse shadowed buffer");
844  		__brelse(bh);
845  	}
846  
847  	J_ASSERT (commit_transaction->t_shadow_list == NULL);
848  
849  	jbd2_debug(3, "JBD2: commit phase 4\n");
850  
851  	/* Here we wait for the revoke record and descriptor record buffers */
852  	while (!list_empty(&log_bufs)) {
853  		struct buffer_head *bh;
854  
855  		bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
856  		wait_on_buffer(bh);
857  		cond_resched();
858  
859  		if (unlikely(!buffer_uptodate(bh)))
860  			err = -EIO;
861  
862  		BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
863  		clear_buffer_jwrite(bh);
864  		jbd2_unfile_log_bh(bh);
865  		stats.run.rs_blocks_logged++;
866  		__brelse(bh);		/* One for getblk */
867  		/* AKPM: bforget here */
868  	}
869  
870  	if (err)
871  		jbd2_journal_abort(journal, err);
872  
873  	jbd2_debug(3, "JBD2: commit phase 5\n");
874  	write_lock(&journal->j_state_lock);
875  	J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
876  	commit_transaction->t_state = T_COMMIT_JFLUSH;
877  	write_unlock(&journal->j_state_lock);
878  
879  	if (!jbd2_has_feature_async_commit(journal)) {
880  		err = journal_submit_commit_record(journal, commit_transaction,
881  						&cbh, crc32_sum);
882  		if (err)
883  			jbd2_journal_abort(journal, err);
884  	}
885  	if (cbh)
886  		err = journal_wait_on_commit_record(journal, cbh);
887  	stats.run.rs_blocks_logged++;
888  	if (jbd2_has_feature_async_commit(journal) &&
889  	    journal->j_flags & JBD2_BARRIER) {
890  		blkdev_issue_flush(journal->j_dev);
891  	}
892  
893  	if (err)
894  		jbd2_journal_abort(journal, err);
895  
896  	WARN_ON_ONCE(
897  		atomic_read(&commit_transaction->t_outstanding_credits) < 0);
898  
899  	/*
900  	 * Now disk caches for filesystem device are flushed so we are safe to
901  	 * erase checkpointed transactions from the log by updating journal
902  	 * superblock.
903  	 */
904  	if (update_tail)
905  		jbd2_update_log_tail(journal, first_tid, first_block);
906  
907  	/* End of a transaction!  Finally, we can do checkpoint
908             processing: any buffers committed as a result of this
909             transaction can be removed from any checkpoint list it was on
910             before. */
911  
912  	jbd2_debug(3, "JBD2: commit phase 6\n");
913  
914  	J_ASSERT(list_empty(&commit_transaction->t_inode_list));
915  	J_ASSERT(commit_transaction->t_buffers == NULL);
916  	J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
917  	J_ASSERT(commit_transaction->t_shadow_list == NULL);
918  
919  restart_loop:
920  	/*
921  	 * As there are other places (journal_unmap_buffer()) adding buffers
922  	 * to this list we have to be careful and hold the j_list_lock.
923  	 */
924  	spin_lock(&journal->j_list_lock);
925  	while (commit_transaction->t_forget) {
926  		transaction_t *cp_transaction;
927  		struct buffer_head *bh;
928  		int try_to_free = 0;
929  		bool drop_ref;
930  
931  		jh = commit_transaction->t_forget;
932  		spin_unlock(&journal->j_list_lock);
933  		bh = jh2bh(jh);
934  		/*
935  		 * Get a reference so that bh cannot be freed before we are
936  		 * done with it.
937  		 */
938  		get_bh(bh);
939  		spin_lock(&jh->b_state_lock);
940  		J_ASSERT_JH(jh,	jh->b_transaction == commit_transaction);
941  
942  		/*
943  		 * If there is undo-protected committed data against
944  		 * this buffer, then we can remove it now.  If it is a
945  		 * buffer needing such protection, the old frozen_data
946  		 * field now points to a committed version of the
947  		 * buffer, so rotate that field to the new committed
948  		 * data.
949  		 *
950  		 * Otherwise, we can just throw away the frozen data now.
951  		 *
952  		 * We also know that the frozen data has already fired
953  		 * its triggers if they exist, so we can clear that too.
954  		 */
955  		if (jh->b_committed_data) {
956  			jbd2_free(jh->b_committed_data, bh->b_size);
957  			jh->b_committed_data = NULL;
958  			if (jh->b_frozen_data) {
959  				jh->b_committed_data = jh->b_frozen_data;
960  				jh->b_frozen_data = NULL;
961  				jh->b_frozen_triggers = NULL;
962  			}
963  		} else if (jh->b_frozen_data) {
964  			jbd2_free(jh->b_frozen_data, bh->b_size);
965  			jh->b_frozen_data = NULL;
966  			jh->b_frozen_triggers = NULL;
967  		}
968  
969  		spin_lock(&journal->j_list_lock);
970  		cp_transaction = jh->b_cp_transaction;
971  		if (cp_transaction) {
972  			JBUFFER_TRACE(jh, "remove from old cp transaction");
973  			cp_transaction->t_chp_stats.cs_dropped++;
974  			__jbd2_journal_remove_checkpoint(jh);
975  		}
976  
977  		/* Only re-checkpoint the buffer_head if it is marked
978  		 * dirty.  If the buffer was added to the BJ_Forget list
979  		 * by jbd2_journal_forget, it may no longer be dirty and
980  		 * there's no point in keeping a checkpoint record for
981  		 * it. */
982  
983  		/*
984  		 * A buffer which has been freed while still being journaled
985  		 * by a previous transaction, refile the buffer to BJ_Forget of
986  		 * the running transaction. If the just committed transaction
987  		 * contains "add to orphan" operation, we can completely
988  		 * invalidate the buffer now. We are rather through in that
989  		 * since the buffer may be still accessible when blocksize <
990  		 * pagesize and it is attached to the last partial page.
991  		 */
992  		if (buffer_freed(bh) && !jh->b_next_transaction) {
993  			struct address_space *mapping;
994  
995  			clear_buffer_freed(bh);
996  			clear_buffer_jbddirty(bh);
997  
998  			/*
999  			 * Block device buffers need to stay mapped all the
1000  			 * time, so it is enough to clear buffer_jbddirty and
1001  			 * buffer_freed bits. For the file mapping buffers (i.e.
1002  			 * journalled data) we need to unmap buffer and clear
1003  			 * more bits. We also need to be careful about the check
1004  			 * because the data page mapping can get cleared under
1005  			 * our hands. Note that if mapping == NULL, we don't
1006  			 * need to make buffer unmapped because the page is
1007  			 * already detached from the mapping and buffers cannot
1008  			 * get reused.
1009  			 */
1010  			mapping = READ_ONCE(bh->b_folio->mapping);
1011  			if (mapping && !sb_is_blkdev_sb(mapping->host->i_sb)) {
1012  				clear_buffer_mapped(bh);
1013  				clear_buffer_new(bh);
1014  				clear_buffer_req(bh);
1015  				bh->b_bdev = NULL;
1016  			}
1017  		}
1018  
1019  		if (buffer_jbddirty(bh)) {
1020  			JBUFFER_TRACE(jh, "add to new checkpointing trans");
1021  			__jbd2_journal_insert_checkpoint(jh, commit_transaction);
1022  			if (is_journal_aborted(journal))
1023  				clear_buffer_jbddirty(bh);
1024  		} else {
1025  			J_ASSERT_BH(bh, !buffer_dirty(bh));
1026  			/*
1027  			 * The buffer on BJ_Forget list and not jbddirty means
1028  			 * it has been freed by this transaction and hence it
1029  			 * could not have been reallocated until this
1030  			 * transaction has committed. *BUT* it could be
1031  			 * reallocated once we have written all the data to
1032  			 * disk and before we process the buffer on BJ_Forget
1033  			 * list.
1034  			 */
1035  			if (!jh->b_next_transaction)
1036  				try_to_free = 1;
1037  		}
1038  		JBUFFER_TRACE(jh, "refile or unfile buffer");
1039  		drop_ref = __jbd2_journal_refile_buffer(jh);
1040  		spin_unlock(&jh->b_state_lock);
1041  		if (drop_ref)
1042  			jbd2_journal_put_journal_head(jh);
1043  		if (try_to_free)
1044  			release_buffer_page(bh);	/* Drops bh reference */
1045  		else
1046  			__brelse(bh);
1047  		cond_resched_lock(&journal->j_list_lock);
1048  	}
1049  	spin_unlock(&journal->j_list_lock);
1050  	/*
1051  	 * This is a bit sleazy.  We use j_list_lock to protect transition
1052  	 * of a transaction into T_FINISHED state and calling
1053  	 * __jbd2_journal_drop_transaction(). Otherwise we could race with
1054  	 * other checkpointing code processing the transaction...
1055  	 */
1056  	write_lock(&journal->j_state_lock);
1057  	spin_lock(&journal->j_list_lock);
1058  	/*
1059  	 * Now recheck if some buffers did not get attached to the transaction
1060  	 * while the lock was dropped...
1061  	 */
1062  	if (commit_transaction->t_forget) {
1063  		spin_unlock(&journal->j_list_lock);
1064  		write_unlock(&journal->j_state_lock);
1065  		goto restart_loop;
1066  	}
1067  
1068  	/* Add the transaction to the checkpoint list
1069  	 * __journal_remove_checkpoint() can not destroy transaction
1070  	 * under us because it is not marked as T_FINISHED yet */
1071  	if (journal->j_checkpoint_transactions == NULL) {
1072  		journal->j_checkpoint_transactions = commit_transaction;
1073  		commit_transaction->t_cpnext = commit_transaction;
1074  		commit_transaction->t_cpprev = commit_transaction;
1075  	} else {
1076  		commit_transaction->t_cpnext =
1077  			journal->j_checkpoint_transactions;
1078  		commit_transaction->t_cpprev =
1079  			commit_transaction->t_cpnext->t_cpprev;
1080  		commit_transaction->t_cpnext->t_cpprev =
1081  			commit_transaction;
1082  		commit_transaction->t_cpprev->t_cpnext =
1083  				commit_transaction;
1084  	}
1085  	spin_unlock(&journal->j_list_lock);
1086  
1087  	/* Done with this transaction! */
1088  
1089  	jbd2_debug(3, "JBD2: commit phase 7\n");
1090  
1091  	J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1092  
1093  	commit_transaction->t_start = jiffies;
1094  	stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1095  					      commit_transaction->t_start);
1096  
1097  	/*
1098  	 * File the transaction statistics
1099  	 */
1100  	stats.ts_tid = commit_transaction->t_tid;
1101  	stats.run.rs_handle_count =
1102  		atomic_read(&commit_transaction->t_handle_count);
1103  	trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1104  			     commit_transaction->t_tid, &stats.run);
1105  	stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0;
1106  
1107  	commit_transaction->t_state = T_COMMIT_CALLBACK;
1108  	J_ASSERT(commit_transaction == journal->j_committing_transaction);
1109  	journal->j_commit_sequence = commit_transaction->t_tid;
1110  	journal->j_committing_transaction = NULL;
1111  	commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1112  
1113  	/*
1114  	 * weight the commit time higher than the average time so we don't
1115  	 * react too strongly to vast changes in the commit time
1116  	 */
1117  	if (likely(journal->j_average_commit_time))
1118  		journal->j_average_commit_time = (commit_time +
1119  				journal->j_average_commit_time*3) / 4;
1120  	else
1121  		journal->j_average_commit_time = commit_time;
1122  
1123  	write_unlock(&journal->j_state_lock);
1124  
1125  	if (journal->j_commit_callback)
1126  		journal->j_commit_callback(journal, commit_transaction);
1127  	if (journal->j_fc_cleanup_callback)
1128  		journal->j_fc_cleanup_callback(journal, 1, commit_transaction->t_tid);
1129  
1130  	trace_jbd2_end_commit(journal, commit_transaction);
1131  	jbd2_debug(1, "JBD2: commit %d complete, head %d\n",
1132  		  journal->j_commit_sequence, journal->j_tail_sequence);
1133  
1134  	write_lock(&journal->j_state_lock);
1135  	journal->j_flags &= ~JBD2_FULL_COMMIT_ONGOING;
1136  	journal->j_flags &= ~JBD2_FAST_COMMIT_ONGOING;
1137  	spin_lock(&journal->j_list_lock);
1138  	commit_transaction->t_state = T_FINISHED;
1139  	/* Check if the transaction can be dropped now that we are finished */
1140  	if (commit_transaction->t_checkpoint_list == NULL) {
1141  		__jbd2_journal_drop_transaction(journal, commit_transaction);
1142  		jbd2_journal_free_transaction(commit_transaction);
1143  	}
1144  	spin_unlock(&journal->j_list_lock);
1145  	write_unlock(&journal->j_state_lock);
1146  	wake_up(&journal->j_wait_done_commit);
1147  	wake_up(&journal->j_fc_wait);
1148  
1149  	/*
1150  	 * Calculate overall stats
1151  	 */
1152  	spin_lock(&journal->j_history_lock);
1153  	journal->j_stats.ts_tid++;
1154  	journal->j_stats.ts_requested += stats.ts_requested;
1155  	journal->j_stats.run.rs_wait += stats.run.rs_wait;
1156  	journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1157  	journal->j_stats.run.rs_running += stats.run.rs_running;
1158  	journal->j_stats.run.rs_locked += stats.run.rs_locked;
1159  	journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1160  	journal->j_stats.run.rs_logging += stats.run.rs_logging;
1161  	journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1162  	journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1163  	journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1164  	spin_unlock(&journal->j_history_lock);
1165  }
1166