~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/jbd2/checkpoint.c

Version: ~ [ linux-5.6 ] ~ [ linux-5.5.13 ] ~ [ linux-5.4.28 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.113 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.174 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.217 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.217 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.82 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /*
  2  * linux/fs/jbd2/checkpoint.c
  3  *
  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>
 22 #include <linux/jbd2.h>
 23 #include <linux/errno.h>
 24 #include <linux/slab.h>
 25 #include <linux/blkdev.h>
 26 #include <trace/events/jbd2.h>
 27 
 28 /*
 29  * Unlink a buffer from a transaction checkpoint list.
 30  *
 31  * Called with j_list_lock held.
 32  */
 33 static 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  */
 51 static 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  */
 68 static 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  */
 92 static int __try_to_free_cp_buf(struct journal_head *jh)
 93 {
 94         int ret = 0;
 95         struct buffer_head *bh = jh2bh(jh);
 96 
 97         if (jh->b_transaction == NULL && !buffer_locked(bh) &&
 98             !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
 99                 /*
100                  * Get our reference so that bh cannot be freed before
101                  * we unlock it
102                  */
103                 get_bh(bh);
104                 JBUFFER_TRACE(jh, "remove from checkpoint list");
105                 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
106                 BUFFER_TRACE(bh, "release");
107                 __brelse(bh);
108         }
109         return ret;
110 }
111 
112 /*
113  * __jbd2_log_wait_for_space: wait until there is space in the journal.
114  *
115  * Called under j-state_lock *only*.  It will be unlocked if we have to wait
116  * for a checkpoint to free up some space in the log.
117  */
118 void __jbd2_log_wait_for_space(journal_t *journal)
119 {
120         int nblocks, space_left;
121         /* assert_spin_locked(&journal->j_state_lock); */
122 
123         nblocks = jbd2_space_needed(journal);
124         while (jbd2_log_space_left(journal) < nblocks) {
125                 if (journal->j_flags & JBD2_ABORT)
126                         return;
127                 write_unlock(&journal->j_state_lock);
128                 mutex_lock(&journal->j_checkpoint_mutex);
129 
130                 /*
131                  * Test again, another process may have checkpointed while we
132                  * were waiting for the checkpoint lock. If there are no
133                  * transactions ready to be checkpointed, try to recover
134                  * journal space by calling cleanup_journal_tail(), and if
135                  * that doesn't work, by waiting for the currently committing
136                  * transaction to complete.  If there is absolutely no way
137                  * to make progress, this is either a BUG or corrupted
138                  * filesystem, so abort the journal and leave a stack
139                  * trace for forensic evidence.
140                  */
141                 write_lock(&journal->j_state_lock);
142                 spin_lock(&journal->j_list_lock);
143                 nblocks = jbd2_space_needed(journal);
144                 space_left = jbd2_log_space_left(journal);
145                 if (space_left < nblocks) {
146                         int chkpt = journal->j_checkpoint_transactions != NULL;
147                         tid_t tid = 0;
148 
149                         if (journal->j_committing_transaction)
150                                 tid = journal->j_committing_transaction->t_tid;
151                         spin_unlock(&journal->j_list_lock);
152                         write_unlock(&journal->j_state_lock);
153                         if (chkpt) {
154                                 jbd2_log_do_checkpoint(journal);
155                         } else if (jbd2_cleanup_journal_tail(journal) == 0) {
156                                 /* We were able to recover space; yay! */
157                                 ;
158                         } else if (tid) {
159                                 /*
160                                  * jbd2_journal_commit_transaction() may want
161                                  * to take the checkpoint_mutex if JBD2_FLUSHED
162                                  * is set.  So we need to temporarily drop it.
163                                  */
164                                 mutex_unlock(&journal->j_checkpoint_mutex);
165                                 jbd2_log_wait_commit(journal, tid);
166                                 write_lock(&journal->j_state_lock);
167                                 continue;
168                         } else {
169                                 printk(KERN_ERR "%s: needed %d blocks and "
170                                        "only had %d space available\n",
171                                        __func__, nblocks, space_left);
172                                 printk(KERN_ERR "%s: no way to get more "
173                                        "journal space in %s\n", __func__,
174                                        journal->j_devname);
175                                 WARN_ON(1);
176                                 jbd2_journal_abort(journal, 0);
177                         }
178                         write_lock(&journal->j_state_lock);
179                 } else {
180                         spin_unlock(&journal->j_list_lock);
181                 }
182                 mutex_unlock(&journal->j_checkpoint_mutex);
183         }
184 }
185 
186 /*
187  * Clean up transaction's list of buffers submitted for io.
188  * We wait for any pending IO to complete and remove any clean
189  * buffers. Note that we take the buffers in the opposite ordering
190  * from the one in which they were submitted for IO.
191  *
192  * Return 0 on success, and return <0 if some buffers have failed
193  * to be written out.
194  *
195  * Called with j_list_lock held.
196  */
197 static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
198 {
199         struct journal_head *jh;
200         struct buffer_head *bh;
201         tid_t this_tid;
202         int released = 0;
203         int ret = 0;
204 
205         this_tid = transaction->t_tid;
206 restart:
207         /* Did somebody clean up the transaction in the meanwhile? */
208         if (journal->j_checkpoint_transactions != transaction ||
209                         transaction->t_tid != this_tid)
210                 return ret;
211         while (!released && transaction->t_checkpoint_io_list) {
212                 jh = transaction->t_checkpoint_io_list;
213                 bh = jh2bh(jh);
214                 get_bh(bh);
215                 if (buffer_locked(bh)) {
216                         spin_unlock(&journal->j_list_lock);
217                         wait_on_buffer(bh);
218                         /* the journal_head may have gone by now */
219                         BUFFER_TRACE(bh, "brelse");
220                         __brelse(bh);
221                         spin_lock(&journal->j_list_lock);
222                         goto restart;
223                 }
224                 if (unlikely(buffer_write_io_error(bh)))
225                         ret = -EIO;
226 
227                 /*
228                  * Now in whatever state the buffer currently is, we know that
229                  * it has been written out and so we can drop it from the list
230                  */
231                 released = __jbd2_journal_remove_checkpoint(jh);
232                 __brelse(bh);
233         }
234 
235         return ret;
236 }
237 
238 static void
239 __flush_batch(journal_t *journal, int *batch_count)
240 {
241         int i;
242         struct blk_plug plug;
243 
244         blk_start_plug(&plug);
245         for (i = 0; i < *batch_count; i++)
246                 write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE_SYNC);
247         blk_finish_plug(&plug);
248 
249         for (i = 0; i < *batch_count; i++) {
250                 struct buffer_head *bh = journal->j_chkpt_bhs[i];
251                 BUFFER_TRACE(bh, "brelse");
252                 __brelse(bh);
253         }
254         *batch_count = 0;
255 }
256 
257 /*
258  * Try to flush one buffer from the checkpoint list to disk.
259  *
260  * Return 1 if something happened which requires us to abort the current
261  * scan of the checkpoint list.  Return <0 if the buffer has failed to
262  * be written out.
263  *
264  * Called with j_list_lock held and drops it if 1 is returned
265  */
266 static int __process_buffer(journal_t *journal, struct journal_head *jh,
267                             int *batch_count, transaction_t *transaction)
268 {
269         struct buffer_head *bh = jh2bh(jh);
270         int ret = 0;
271 
272         if (buffer_locked(bh)) {
273                 get_bh(bh);
274                 spin_unlock(&journal->j_list_lock);
275                 wait_on_buffer(bh);
276                 /* the journal_head may have gone by now */
277                 BUFFER_TRACE(bh, "brelse");
278                 __brelse(bh);
279                 ret = 1;
280         } else if (jh->b_transaction != NULL) {
281                 transaction_t *t = jh->b_transaction;
282                 tid_t tid = t->t_tid;
283 
284                 transaction->t_chp_stats.cs_forced_to_close++;
285                 spin_unlock(&journal->j_list_lock);
286                 if (unlikely(journal->j_flags & JBD2_UNMOUNT))
287                         /*
288                          * The journal thread is dead; so starting and
289                          * waiting for a commit to finish will cause
290                          * us to wait for a _very_ long time.
291                          */
292                         printk(KERN_ERR "JBD2: %s: "
293                                "Waiting for Godot: block %llu\n",
294                                journal->j_devname,
295                                (unsigned long long) bh->b_blocknr);
296                 jbd2_log_start_commit(journal, tid);
297                 jbd2_log_wait_commit(journal, tid);
298                 ret = 1;
299         } else if (!buffer_dirty(bh)) {
300                 ret = 1;
301                 if (unlikely(buffer_write_io_error(bh)))
302                         ret = -EIO;
303                 get_bh(bh);
304                 BUFFER_TRACE(bh, "remove from checkpoint");
305                 __jbd2_journal_remove_checkpoint(jh);
306                 spin_unlock(&journal->j_list_lock);
307                 __brelse(bh);
308         } else {
309                 /*
310                  * Important: we are about to write the buffer, and
311                  * possibly block, while still holding the journal lock.
312                  * We cannot afford to let the transaction logic start
313                  * messing around with this buffer before we write it to
314                  * disk, as that would break recoverability.
315                  */
316                 BUFFER_TRACE(bh, "queue");
317                 get_bh(bh);
318                 J_ASSERT_BH(bh, !buffer_jwrite(bh));
319                 journal->j_chkpt_bhs[*batch_count] = bh;
320                 __buffer_relink_io(jh);
321                 transaction->t_chp_stats.cs_written++;
322                 (*batch_count)++;
323                 if (*batch_count == JBD2_NR_BATCH) {
324                         spin_unlock(&journal->j_list_lock);
325                         __flush_batch(journal, batch_count);
326                         ret = 1;
327                 }
328         }
329         return ret;
330 }
331 
332 /*
333  * Perform an actual checkpoint. We take the first transaction on the
334  * list of transactions to be checkpointed and send all its buffers
335  * to disk. We submit larger chunks of data at once.
336  *
337  * The journal should be locked before calling this function.
338  * Called with j_checkpoint_mutex held.
339  */
340 int jbd2_log_do_checkpoint(journal_t *journal)
341 {
342         transaction_t *transaction;
343         tid_t this_tid;
344         int result;
345 
346         jbd_debug(1, "Start checkpoint\n");
347 
348         /*
349          * First thing: if there are any transactions in the log which
350          * don't need checkpointing, just eliminate them from the
351          * journal straight away.
352          */
353         result = jbd2_cleanup_journal_tail(journal);
354         trace_jbd2_checkpoint(journal, result);
355         jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
356         if (result <= 0)
357                 return result;
358 
359         /*
360          * OK, we need to start writing disk blocks.  Take one transaction
361          * and write it.
362          */
363         result = 0;
364         spin_lock(&journal->j_list_lock);
365         if (!journal->j_checkpoint_transactions)
366                 goto out;
367         transaction = journal->j_checkpoint_transactions;
368         if (transaction->t_chp_stats.cs_chp_time == 0)
369                 transaction->t_chp_stats.cs_chp_time = jiffies;
370         this_tid = transaction->t_tid;
371 restart:
372         /*
373          * If someone cleaned up this transaction while we slept, we're
374          * done (maybe it's a new transaction, but it fell at the same
375          * address).
376          */
377         if (journal->j_checkpoint_transactions == transaction &&
378                         transaction->t_tid == this_tid) {
379                 int batch_count = 0;
380                 struct journal_head *jh;
381                 int retry = 0, err;
382 
383                 while (!retry && transaction->t_checkpoint_list) {
384                         jh = transaction->t_checkpoint_list;
385                         retry = __process_buffer(journal, jh, &batch_count,
386                                                  transaction);
387                         if (retry < 0 && !result)
388                                 result = retry;
389                         if (!retry && (need_resched() ||
390                                 spin_needbreak(&journal->j_list_lock))) {
391                                 spin_unlock(&journal->j_list_lock);
392                                 retry = 1;
393                                 break;
394                         }
395                 }
396 
397                 if (batch_count) {
398                         if (!retry) {
399                                 spin_unlock(&journal->j_list_lock);
400                                 retry = 1;
401                         }
402                         __flush_batch(journal, &batch_count);
403                 }
404 
405                 if (retry) {
406                         spin_lock(&journal->j_list_lock);
407                         goto restart;
408                 }
409                 /*
410                  * Now we have cleaned up the first transaction's checkpoint
411                  * list. Let's clean up the second one
412                  */
413                 err = __wait_cp_io(journal, transaction);
414                 if (!result)
415                         result = err;
416         }
417 out:
418         spin_unlock(&journal->j_list_lock);
419         if (result < 0)
420                 jbd2_journal_abort(journal, result);
421         else
422                 result = jbd2_cleanup_journal_tail(journal);
423 
424         return (result < 0) ? result : 0;
425 }
426 
427 /*
428  * Check the list of checkpoint transactions for the journal to see if
429  * we have already got rid of any since the last update of the log tail
430  * in the journal superblock.  If so, we can instantly roll the
431  * superblock forward to remove those transactions from the log.
432  *
433  * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
434  *
435  * Called with the journal lock held.
436  *
437  * This is the only part of the journaling code which really needs to be
438  * aware of transaction aborts.  Checkpointing involves writing to the
439  * main filesystem area rather than to the journal, so it can proceed
440  * even in abort state, but we must not update the super block if
441  * checkpointing may have failed.  Otherwise, we would lose some metadata
442  * buffers which should be written-back to the filesystem.
443  */
444 
445 int jbd2_cleanup_journal_tail(journal_t *journal)
446 {
447         tid_t           first_tid;
448         unsigned long   blocknr;
449 
450         if (is_journal_aborted(journal))
451                 return -EIO;
452 
453         if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
454                 return 1;
455         J_ASSERT(blocknr != 0);
456 
457         /*
458          * We need to make sure that any blocks that were recently written out
459          * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
460          * we drop the transactions from the journal. It's unlikely this will
461          * be necessary, especially with an appropriately sized journal, but we
462          * need this to guarantee correctness.  Fortunately
463          * jbd2_cleanup_journal_tail() doesn't get called all that often.
464          */
465         if (journal->j_flags & JBD2_BARRIER)
466                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
467 
468         return __jbd2_update_log_tail(journal, first_tid, blocknr);
469 }
470 
471 
472 /* Checkpoint list management */
473 
474 /*
475  * journal_clean_one_cp_list
476  *
477  * Find all the written-back checkpoint buffers in the given list and
478  * release them. If 'destroy' is set, clean all buffers unconditionally.
479  *
480  * Called with the journal locked.
481  * Called with j_list_lock held.
482  * Returns number of buffers reaped (for debug)
483  */
484 
485 static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy,
486                                      int *released)
487 {
488         struct journal_head *last_jh;
489         struct journal_head *next_jh = jh;
490         int ret, freed = 0;
491 
492         *released = 0;
493         if (!jh)
494                 return 0;
495 
496         last_jh = jh->b_cpprev;
497         do {
498                 jh = next_jh;
499                 next_jh = jh->b_cpnext;
500                 if (!destroy)
501                         ret = __try_to_free_cp_buf(jh);
502                 else
503                         ret = __jbd2_journal_remove_checkpoint(jh) + 1;
504                 if (ret) {
505                         freed++;
506                         if (ret == 2) {
507                                 *released = 1;
508                                 return freed;
509                         }
510                 }
511                 /*
512                  * This function only frees up some memory
513                  * if possible so we dont have an obligation
514                  * to finish processing. Bail out if preemption
515                  * requested:
516                  */
517                 if (need_resched())
518                         return freed;
519         } while (jh != last_jh);
520 
521         return freed;
522 }
523 
524 /*
525  * journal_clean_checkpoint_list
526  *
527  * Find all the written-back checkpoint buffers in the journal and release them.
528  * If 'destroy' is set, release all buffers unconditionally.
529  *
530  * Called with the journal locked.
531  * Called with j_list_lock held.
532  * Returns number of buffers reaped (for debug)
533  */
534 
535 int __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
536 {
537         transaction_t *transaction, *last_transaction, *next_transaction;
538         int ret = 0;
539         int released;
540 
541         transaction = journal->j_checkpoint_transactions;
542         if (!transaction)
543                 goto out;
544 
545         last_transaction = transaction->t_cpprev;
546         next_transaction = transaction;
547         do {
548                 transaction = next_transaction;
549                 next_transaction = transaction->t_cpnext;
550                 ret += journal_clean_one_cp_list(transaction->
551                                 t_checkpoint_list, destroy, &released);
552                 /*
553                  * This function only frees up some memory if possible so we
554                  * dont have an obligation to finish processing. Bail out if
555                  * preemption requested:
556                  */
557                 if (need_resched())
558                         goto out;
559                 if (released)
560                         continue;
561                 /*
562                  * It is essential that we are as careful as in the case of
563                  * t_checkpoint_list with removing the buffer from the list as
564                  * we can possibly see not yet submitted buffers on io_list
565                  */
566                 ret += journal_clean_one_cp_list(transaction->
567                                 t_checkpoint_io_list, destroy, &released);
568                 if (need_resched())
569                         goto out;
570         } while (transaction != last_transaction);
571 out:
572         return ret;
573 }
574 
575 /*
576  * Remove buffers from all checkpoint lists as journal is aborted and we just
577  * need to free memory
578  */
579 void jbd2_journal_destroy_checkpoint(journal_t *journal)
580 {
581         /*
582          * We loop because __jbd2_journal_clean_checkpoint_list() may abort
583          * early due to a need of rescheduling.
584          */
585         while (1) {
586                 spin_lock(&journal->j_list_lock);
587                 if (!journal->j_checkpoint_transactions) {
588                         spin_unlock(&journal->j_list_lock);
589                         break;
590                 }
591                 __jbd2_journal_clean_checkpoint_list(journal, true);
592                 spin_unlock(&journal->j_list_lock);
593                 cond_resched();
594         }
595 }
596 
597 /*
598  * journal_remove_checkpoint: called after a buffer has been committed
599  * to disk (either by being write-back flushed to disk, or being
600  * committed to the log).
601  *
602  * We cannot safely clean a transaction out of the log until all of the
603  * buffer updates committed in that transaction have safely been stored
604  * elsewhere on disk.  To achieve this, all of the buffers in a
605  * transaction need to be maintained on the transaction's checkpoint
606  * lists until they have been rewritten, at which point this function is
607  * called to remove the buffer from the existing transaction's
608  * checkpoint lists.
609  *
610  * The function returns 1 if it frees the transaction, 0 otherwise.
611  * The function can free jh and bh.
612  *
613  * This function is called with j_list_lock held.
614  */
615 int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
616 {
617         struct transaction_chp_stats_s *stats;
618         transaction_t *transaction;
619         journal_t *journal;
620         int ret = 0;
621 
622         JBUFFER_TRACE(jh, "entry");
623 
624         if ((transaction = jh->b_cp_transaction) == NULL) {
625                 JBUFFER_TRACE(jh, "not on transaction");
626                 goto out;
627         }
628         journal = transaction->t_journal;
629 
630         JBUFFER_TRACE(jh, "removing from transaction");
631         __buffer_unlink(jh);
632         jh->b_cp_transaction = NULL;
633         jbd2_journal_put_journal_head(jh);
634 
635         if (transaction->t_checkpoint_list != NULL ||
636             transaction->t_checkpoint_io_list != NULL)
637                 goto out;
638 
639         /*
640          * There is one special case to worry about: if we have just pulled the
641          * buffer off a running or committing transaction's checkpoing list,
642          * then even if the checkpoint list is empty, the transaction obviously
643          * cannot be dropped!
644          *
645          * The locking here around t_state is a bit sleazy.
646          * See the comment at the end of jbd2_journal_commit_transaction().
647          */
648         if (transaction->t_state != T_FINISHED)
649                 goto out;
650 
651         /* OK, that was the last buffer for the transaction: we can now
652            safely remove this transaction from the log */
653         stats = &transaction->t_chp_stats;
654         if (stats->cs_chp_time)
655                 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
656                                                     jiffies);
657         trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
658                                     transaction->t_tid, stats);
659 
660         __jbd2_journal_drop_transaction(journal, transaction);
661         jbd2_journal_free_transaction(transaction);
662         ret = 1;
663 out:
664         return ret;
665 }
666 
667 /*
668  * journal_insert_checkpoint: put a committed buffer onto a checkpoint
669  * list so that we know when it is safe to clean the transaction out of
670  * the log.
671  *
672  * Called with the journal locked.
673  * Called with j_list_lock held.
674  */
675 void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
676                                transaction_t *transaction)
677 {
678         JBUFFER_TRACE(jh, "entry");
679         J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
680         J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
681 
682         /* Get reference for checkpointing transaction */
683         jbd2_journal_grab_journal_head(jh2bh(jh));
684         jh->b_cp_transaction = transaction;
685 
686         if (!transaction->t_checkpoint_list) {
687                 jh->b_cpnext = jh->b_cpprev = jh;
688         } else {
689                 jh->b_cpnext = transaction->t_checkpoint_list;
690                 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
691                 jh->b_cpprev->b_cpnext = jh;
692                 jh->b_cpnext->b_cpprev = jh;
693         }
694         transaction->t_checkpoint_list = jh;
695 }
696 
697 /*
698  * We've finished with this transaction structure: adios...
699  *
700  * The transaction must have no links except for the checkpoint by this
701  * point.
702  *
703  * Called with the journal locked.
704  * Called with j_list_lock held.
705  */
706 
707 void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
708 {
709         assert_spin_locked(&journal->j_list_lock);
710         if (transaction->t_cpnext) {
711                 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
712                 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
713                 if (journal->j_checkpoint_transactions == transaction)
714                         journal->j_checkpoint_transactions =
715                                 transaction->t_cpnext;
716                 if (journal->j_checkpoint_transactions == transaction)
717                         journal->j_checkpoint_transactions = NULL;
718         }
719 
720         J_ASSERT(transaction->t_state == T_FINISHED);
721         J_ASSERT(transaction->t_buffers == NULL);
722         J_ASSERT(transaction->t_forget == NULL);
723         J_ASSERT(transaction->t_shadow_list == NULL);
724         J_ASSERT(transaction->t_checkpoint_list == NULL);
725         J_ASSERT(transaction->t_checkpoint_io_list == NULL);
726         J_ASSERT(atomic_read(&transaction->t_updates) == 0);
727         J_ASSERT(journal->j_committing_transaction != transaction);
728         J_ASSERT(journal->j_running_transaction != transaction);
729 
730         trace_jbd2_drop_transaction(journal, transaction);
731 
732         jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
733 }
734 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp