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

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  1 /*
  2  * linux/fs/jbd2/journal.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  * Generic filesystem journal-writing code; part of the ext2fs
 13  * journaling system.
 14  *
 15  * This file manages journals: areas of disk reserved for logging
 16  * transactional updates.  This includes the kernel journaling thread
 17  * which is responsible for scheduling updates to the log.
 18  *
 19  * We do not actually manage the physical storage of the journal in this
 20  * file: that is left to a per-journal policy function, which allows us
 21  * to store the journal within a filesystem-specified area for ext2
 22  * journaling (ext2 can use a reserved inode for storing the log).
 23  */
 24 
 25 #include <linux/module.h>
 26 #include <linux/time.h>
 27 #include <linux/fs.h>
 28 #include <linux/jbd2.h>
 29 #include <linux/errno.h>
 30 #include <linux/slab.h>
 31 #include <linux/init.h>
 32 #include <linux/mm.h>
 33 #include <linux/freezer.h>
 34 #include <linux/pagemap.h>
 35 #include <linux/kthread.h>
 36 #include <linux/poison.h>
 37 #include <linux/proc_fs.h>
 38 #include <linux/debugfs.h>
 39 #include <linux/seq_file.h>
 40 #include <linux/math64.h>
 41 #include <linux/hash.h>
 42 #include <linux/log2.h>
 43 #include <linux/vmalloc.h>
 44 #include <linux/backing-dev.h>
 45 #include <linux/bitops.h>
 46 #include <linux/ratelimit.h>
 47 
 48 #define CREATE_TRACE_POINTS
 49 #include <trace/events/jbd2.h>
 50 
 51 #include <asm/uaccess.h>
 52 #include <asm/page.h>
 53 
 54 EXPORT_SYMBOL(jbd2_journal_extend);
 55 EXPORT_SYMBOL(jbd2_journal_stop);
 56 EXPORT_SYMBOL(jbd2_journal_lock_updates);
 57 EXPORT_SYMBOL(jbd2_journal_unlock_updates);
 58 EXPORT_SYMBOL(jbd2_journal_get_write_access);
 59 EXPORT_SYMBOL(jbd2_journal_get_create_access);
 60 EXPORT_SYMBOL(jbd2_journal_get_undo_access);
 61 EXPORT_SYMBOL(jbd2_journal_set_triggers);
 62 EXPORT_SYMBOL(jbd2_journal_dirty_metadata);
 63 EXPORT_SYMBOL(jbd2_journal_release_buffer);
 64 EXPORT_SYMBOL(jbd2_journal_forget);
 65 #if 0
 66 EXPORT_SYMBOL(journal_sync_buffer);
 67 #endif
 68 EXPORT_SYMBOL(jbd2_journal_flush);
 69 EXPORT_SYMBOL(jbd2_journal_revoke);
 70 
 71 EXPORT_SYMBOL(jbd2_journal_init_dev);
 72 EXPORT_SYMBOL(jbd2_journal_init_inode);
 73 EXPORT_SYMBOL(jbd2_journal_check_used_features);
 74 EXPORT_SYMBOL(jbd2_journal_check_available_features);
 75 EXPORT_SYMBOL(jbd2_journal_set_features);
 76 EXPORT_SYMBOL(jbd2_journal_load);
 77 EXPORT_SYMBOL(jbd2_journal_destroy);
 78 EXPORT_SYMBOL(jbd2_journal_abort);
 79 EXPORT_SYMBOL(jbd2_journal_errno);
 80 EXPORT_SYMBOL(jbd2_journal_ack_err);
 81 EXPORT_SYMBOL(jbd2_journal_clear_err);
 82 EXPORT_SYMBOL(jbd2_log_wait_commit);
 83 EXPORT_SYMBOL(jbd2_log_start_commit);
 84 EXPORT_SYMBOL(jbd2_journal_start_commit);
 85 EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
 86 EXPORT_SYMBOL(jbd2_journal_wipe);
 87 EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
 88 EXPORT_SYMBOL(jbd2_journal_invalidatepage);
 89 EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
 90 EXPORT_SYMBOL(jbd2_journal_force_commit);
 91 EXPORT_SYMBOL(jbd2_journal_file_inode);
 92 EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
 93 EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
 94 EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
 95 EXPORT_SYMBOL(jbd2_inode_cache);
 96 
 97 static void __journal_abort_soft (journal_t *journal, int errno);
 98 static int jbd2_journal_create_slab(size_t slab_size);
 99 
100 /* Checksumming functions */
101 int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
102 {
103         if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
104                 return 1;
105 
106         return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
107 }
108 
109 static __u32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb)
110 {
111         __u32 csum, old_csum;
112 
113         old_csum = sb->s_checksum;
114         sb->s_checksum = 0;
115         csum = jbd2_chksum(j, ~0, (char *)sb, sizeof(journal_superblock_t));
116         sb->s_checksum = old_csum;
117 
118         return cpu_to_be32(csum);
119 }
120 
121 int jbd2_superblock_csum_verify(journal_t *j, journal_superblock_t *sb)
122 {
123         if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
124                 return 1;
125 
126         return sb->s_checksum == jbd2_superblock_csum(j, sb);
127 }
128 
129 void jbd2_superblock_csum_set(journal_t *j, journal_superblock_t *sb)
130 {
131         if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
132                 return;
133 
134         sb->s_checksum = jbd2_superblock_csum(j, sb);
135 }
136 
137 /*
138  * Helper function used to manage commit timeouts
139  */
140 
141 static void commit_timeout(unsigned long __data)
142 {
143         struct task_struct * p = (struct task_struct *) __data;
144 
145         wake_up_process(p);
146 }
147 
148 /*
149  * kjournald2: The main thread function used to manage a logging device
150  * journal.
151  *
152  * This kernel thread is responsible for two things:
153  *
154  * 1) COMMIT:  Every so often we need to commit the current state of the
155  *    filesystem to disk.  The journal thread is responsible for writing
156  *    all of the metadata buffers to disk.
157  *
158  * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
159  *    of the data in that part of the log has been rewritten elsewhere on
160  *    the disk.  Flushing these old buffers to reclaim space in the log is
161  *    known as checkpointing, and this thread is responsible for that job.
162  */
163 
164 static int kjournald2(void *arg)
165 {
166         journal_t *journal = arg;
167         transaction_t *transaction;
168 
169         /*
170          * Set up an interval timer which can be used to trigger a commit wakeup
171          * after the commit interval expires
172          */
173         setup_timer(&journal->j_commit_timer, commit_timeout,
174                         (unsigned long)current);
175 
176         set_freezable();
177 
178         /* Record that the journal thread is running */
179         journal->j_task = current;
180         wake_up(&journal->j_wait_done_commit);
181 
182         /*
183          * And now, wait forever for commit wakeup events.
184          */
185         write_lock(&journal->j_state_lock);
186 
187 loop:
188         if (journal->j_flags & JBD2_UNMOUNT)
189                 goto end_loop;
190 
191         jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
192                 journal->j_commit_sequence, journal->j_commit_request);
193 
194         if (journal->j_commit_sequence != journal->j_commit_request) {
195                 jbd_debug(1, "OK, requests differ\n");
196                 write_unlock(&journal->j_state_lock);
197                 del_timer_sync(&journal->j_commit_timer);
198                 jbd2_journal_commit_transaction(journal);
199                 write_lock(&journal->j_state_lock);
200                 goto loop;
201         }
202 
203         wake_up(&journal->j_wait_done_commit);
204         if (freezing(current)) {
205                 /*
206                  * The simpler the better. Flushing journal isn't a
207                  * good idea, because that depends on threads that may
208                  * be already stopped.
209                  */
210                 jbd_debug(1, "Now suspending kjournald2\n");
211                 write_unlock(&journal->j_state_lock);
212                 try_to_freeze();
213                 write_lock(&journal->j_state_lock);
214         } else {
215                 /*
216                  * We assume on resume that commits are already there,
217                  * so we don't sleep
218                  */
219                 DEFINE_WAIT(wait);
220                 int should_sleep = 1;
221 
222                 prepare_to_wait(&journal->j_wait_commit, &wait,
223                                 TASK_INTERRUPTIBLE);
224                 if (journal->j_commit_sequence != journal->j_commit_request)
225                         should_sleep = 0;
226                 transaction = journal->j_running_transaction;
227                 if (transaction && time_after_eq(jiffies,
228                                                 transaction->t_expires))
229                         should_sleep = 0;
230                 if (journal->j_flags & JBD2_UNMOUNT)
231                         should_sleep = 0;
232                 if (should_sleep) {
233                         write_unlock(&journal->j_state_lock);
234                         schedule();
235                         write_lock(&journal->j_state_lock);
236                 }
237                 finish_wait(&journal->j_wait_commit, &wait);
238         }
239 
240         jbd_debug(1, "kjournald2 wakes\n");
241 
242         /*
243          * Were we woken up by a commit wakeup event?
244          */
245         transaction = journal->j_running_transaction;
246         if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
247                 journal->j_commit_request = transaction->t_tid;
248                 jbd_debug(1, "woke because of timeout\n");
249         }
250         goto loop;
251 
252 end_loop:
253         write_unlock(&journal->j_state_lock);
254         del_timer_sync(&journal->j_commit_timer);
255         journal->j_task = NULL;
256         wake_up(&journal->j_wait_done_commit);
257         jbd_debug(1, "Journal thread exiting.\n");
258         return 0;
259 }
260 
261 static int jbd2_journal_start_thread(journal_t *journal)
262 {
263         struct task_struct *t;
264 
265         t = kthread_run(kjournald2, journal, "jbd2/%s",
266                         journal->j_devname);
267         if (IS_ERR(t))
268                 return PTR_ERR(t);
269 
270         wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
271         return 0;
272 }
273 
274 static void journal_kill_thread(journal_t *journal)
275 {
276         write_lock(&journal->j_state_lock);
277         journal->j_flags |= JBD2_UNMOUNT;
278 
279         while (journal->j_task) {
280                 wake_up(&journal->j_wait_commit);
281                 write_unlock(&journal->j_state_lock);
282                 wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
283                 write_lock(&journal->j_state_lock);
284         }
285         write_unlock(&journal->j_state_lock);
286 }
287 
288 /*
289  * jbd2_journal_write_metadata_buffer: write a metadata buffer to the journal.
290  *
291  * Writes a metadata buffer to a given disk block.  The actual IO is not
292  * performed but a new buffer_head is constructed which labels the data
293  * to be written with the correct destination disk block.
294  *
295  * Any magic-number escaping which needs to be done will cause a
296  * copy-out here.  If the buffer happens to start with the
297  * JBD2_MAGIC_NUMBER, then we can't write it to the log directly: the
298  * magic number is only written to the log for descripter blocks.  In
299  * this case, we copy the data and replace the first word with 0, and we
300  * return a result code which indicates that this buffer needs to be
301  * marked as an escaped buffer in the corresponding log descriptor
302  * block.  The missing word can then be restored when the block is read
303  * during recovery.
304  *
305  * If the source buffer has already been modified by a new transaction
306  * since we took the last commit snapshot, we use the frozen copy of
307  * that data for IO.  If we end up using the existing buffer_head's data
308  * for the write, then we *have* to lock the buffer to prevent anyone
309  * else from using and possibly modifying it while the IO is in
310  * progress.
311  *
312  * The function returns a pointer to the buffer_heads to be used for IO.
313  *
314  * We assume that the journal has already been locked in this function.
315  *
316  * Return value:
317  *  <0: Error
318  * >=0: Finished OK
319  *
320  * On success:
321  * Bit 0 set == escape performed on the data
322  * Bit 1 set == buffer copy-out performed (kfree the data after IO)
323  */
324 
325 int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
326                                   struct journal_head  *jh_in,
327                                   struct journal_head **jh_out,
328                                   unsigned long long blocknr)
329 {
330         int need_copy_out = 0;
331         int done_copy_out = 0;
332         int do_escape = 0;
333         char *mapped_data;
334         struct buffer_head *new_bh;
335         struct journal_head *new_jh;
336         struct page *new_page;
337         unsigned int new_offset;
338         struct buffer_head *bh_in = jh2bh(jh_in);
339         journal_t *journal = transaction->t_journal;
340 
341         /*
342          * The buffer really shouldn't be locked: only the current committing
343          * transaction is allowed to write it, so nobody else is allowed
344          * to do any IO.
345          *
346          * akpm: except if we're journalling data, and write() output is
347          * also part of a shared mapping, and another thread has
348          * decided to launch a writepage() against this buffer.
349          */
350         J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
351 
352 retry_alloc:
353         new_bh = alloc_buffer_head(GFP_NOFS);
354         if (!new_bh) {
355                 /*
356                  * Failure is not an option, but __GFP_NOFAIL is going
357                  * away; so we retry ourselves here.
358                  */
359                 congestion_wait(BLK_RW_ASYNC, HZ/50);
360                 goto retry_alloc;
361         }
362 
363         /* keep subsequent assertions sane */
364         new_bh->b_state = 0;
365         init_buffer(new_bh, NULL, NULL);
366         atomic_set(&new_bh->b_count, 1);
367         new_jh = jbd2_journal_add_journal_head(new_bh); /* This sleeps */
368 
369         /*
370          * If a new transaction has already done a buffer copy-out, then
371          * we use that version of the data for the commit.
372          */
373         jbd_lock_bh_state(bh_in);
374 repeat:
375         if (jh_in->b_frozen_data) {
376                 done_copy_out = 1;
377                 new_page = virt_to_page(jh_in->b_frozen_data);
378                 new_offset = offset_in_page(jh_in->b_frozen_data);
379         } else {
380                 new_page = jh2bh(jh_in)->b_page;
381                 new_offset = offset_in_page(jh2bh(jh_in)->b_data);
382         }
383 
384         mapped_data = kmap_atomic(new_page);
385         /*
386          * Fire data frozen trigger if data already wasn't frozen.  Do this
387          * before checking for escaping, as the trigger may modify the magic
388          * offset.  If a copy-out happens afterwards, it will have the correct
389          * data in the buffer.
390          */
391         if (!done_copy_out)
392                 jbd2_buffer_frozen_trigger(jh_in, mapped_data + new_offset,
393                                            jh_in->b_triggers);
394 
395         /*
396          * Check for escaping
397          */
398         if (*((__be32 *)(mapped_data + new_offset)) ==
399                                 cpu_to_be32(JBD2_MAGIC_NUMBER)) {
400                 need_copy_out = 1;
401                 do_escape = 1;
402         }
403         kunmap_atomic(mapped_data);
404 
405         /*
406          * Do we need to do a data copy?
407          */
408         if (need_copy_out && !done_copy_out) {
409                 char *tmp;
410 
411                 jbd_unlock_bh_state(bh_in);
412                 tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS);
413                 if (!tmp) {
414                         jbd2_journal_put_journal_head(new_jh);
415                         return -ENOMEM;
416                 }
417                 jbd_lock_bh_state(bh_in);
418                 if (jh_in->b_frozen_data) {
419                         jbd2_free(tmp, bh_in->b_size);
420                         goto repeat;
421                 }
422 
423                 jh_in->b_frozen_data = tmp;
424                 mapped_data = kmap_atomic(new_page);
425                 memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
426                 kunmap_atomic(mapped_data);
427 
428                 new_page = virt_to_page(tmp);
429                 new_offset = offset_in_page(tmp);
430                 done_copy_out = 1;
431 
432                 /*
433                  * This isn't strictly necessary, as we're using frozen
434                  * data for the escaping, but it keeps consistency with
435                  * b_frozen_data usage.
436                  */
437                 jh_in->b_frozen_triggers = jh_in->b_triggers;
438         }
439 
440         /*
441          * Did we need to do an escaping?  Now we've done all the
442          * copying, we can finally do so.
443          */
444         if (do_escape) {
445                 mapped_data = kmap_atomic(new_page);
446                 *((unsigned int *)(mapped_data + new_offset)) = 0;
447                 kunmap_atomic(mapped_data);
448         }
449 
450         set_bh_page(new_bh, new_page, new_offset);
451         new_jh->b_transaction = NULL;
452         new_bh->b_size = jh2bh(jh_in)->b_size;
453         new_bh->b_bdev = transaction->t_journal->j_dev;
454         new_bh->b_blocknr = blocknr;
455         set_buffer_mapped(new_bh);
456         set_buffer_dirty(new_bh);
457 
458         *jh_out = new_jh;
459 
460         /*
461          * The to-be-written buffer needs to get moved to the io queue,
462          * and the original buffer whose contents we are shadowing or
463          * copying is moved to the transaction's shadow queue.
464          */
465         JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
466         spin_lock(&journal->j_list_lock);
467         __jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
468         spin_unlock(&journal->j_list_lock);
469         jbd_unlock_bh_state(bh_in);
470 
471         JBUFFER_TRACE(new_jh, "file as BJ_IO");
472         jbd2_journal_file_buffer(new_jh, transaction, BJ_IO);
473 
474         return do_escape | (done_copy_out << 1);
475 }
476 
477 /*
478  * Allocation code for the journal file.  Manage the space left in the
479  * journal, so that we can begin checkpointing when appropriate.
480  */
481 
482 /*
483  * __jbd2_log_space_left: Return the number of free blocks left in the journal.
484  *
485  * Called with the journal already locked.
486  *
487  * Called under j_state_lock
488  */
489 
490 int __jbd2_log_space_left(journal_t *journal)
491 {
492         int left = journal->j_free;
493 
494         /* assert_spin_locked(&journal->j_state_lock); */
495 
496         /*
497          * Be pessimistic here about the number of those free blocks which
498          * might be required for log descriptor control blocks.
499          */
500 
501 #define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
502 
503         left -= MIN_LOG_RESERVED_BLOCKS;
504 
505         if (left <= 0)
506                 return 0;
507         left -= (left >> 3);
508         return left;
509 }
510 
511 /*
512  * Called with j_state_lock locked for writing.
513  * Returns true if a transaction commit was started.
514  */
515 int __jbd2_log_start_commit(journal_t *journal, tid_t target)
516 {
517         /*
518          * The only transaction we can possibly wait upon is the
519          * currently running transaction (if it exists).  Otherwise,
520          * the target tid must be an old one.
521          */
522         if (journal->j_running_transaction &&
523             journal->j_running_transaction->t_tid == target) {
524                 /*
525                  * We want a new commit: OK, mark the request and wakeup the
526                  * commit thread.  We do _not_ do the commit ourselves.
527                  */
528 
529                 journal->j_commit_request = target;
530                 jbd_debug(1, "JBD2: requesting commit %d/%d\n",
531                           journal->j_commit_request,
532                           journal->j_commit_sequence);
533                 wake_up(&journal->j_wait_commit);
534                 return 1;
535         } else if (!tid_geq(journal->j_commit_request, target))
536                 /* This should never happen, but if it does, preserve
537                    the evidence before kjournald goes into a loop and
538                    increments j_commit_sequence beyond all recognition. */
539                 WARN_ONCE(1, "JBD2: bad log_start_commit: %u %u %u %u\n",
540                           journal->j_commit_request,
541                           journal->j_commit_sequence,
542                           target, journal->j_running_transaction ? 
543                           journal->j_running_transaction->t_tid : 0);
544         return 0;
545 }
546 
547 int jbd2_log_start_commit(journal_t *journal, tid_t tid)
548 {
549         int ret;
550 
551         write_lock(&journal->j_state_lock);
552         ret = __jbd2_log_start_commit(journal, tid);
553         write_unlock(&journal->j_state_lock);
554         return ret;
555 }
556 
557 /*
558  * Force and wait upon a commit if the calling process is not within
559  * transaction.  This is used for forcing out undo-protected data which contains
560  * bitmaps, when the fs is running out of space.
561  *
562  * We can only force the running transaction if we don't have an active handle;
563  * otherwise, we will deadlock.
564  *
565  * Returns true if a transaction was started.
566  */
567 int jbd2_journal_force_commit_nested(journal_t *journal)
568 {
569         transaction_t *transaction = NULL;
570         tid_t tid;
571         int need_to_start = 0;
572 
573         read_lock(&journal->j_state_lock);
574         if (journal->j_running_transaction && !current->journal_info) {
575                 transaction = journal->j_running_transaction;
576                 if (!tid_geq(journal->j_commit_request, transaction->t_tid))
577                         need_to_start = 1;
578         } else if (journal->j_committing_transaction)
579                 transaction = journal->j_committing_transaction;
580 
581         if (!transaction) {
582                 read_unlock(&journal->j_state_lock);
583                 return 0;       /* Nothing to retry */
584         }
585 
586         tid = transaction->t_tid;
587         read_unlock(&journal->j_state_lock);
588         if (need_to_start)
589                 jbd2_log_start_commit(journal, tid);
590         jbd2_log_wait_commit(journal, tid);
591         return 1;
592 }
593 
594 /*
595  * Start a commit of the current running transaction (if any).  Returns true
596  * if a transaction is going to be committed (or is currently already
597  * committing), and fills its tid in at *ptid
598  */
599 int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
600 {
601         int ret = 0;
602 
603         write_lock(&journal->j_state_lock);
604         if (journal->j_running_transaction) {
605                 tid_t tid = journal->j_running_transaction->t_tid;
606 
607                 __jbd2_log_start_commit(journal, tid);
608                 /* There's a running transaction and we've just made sure
609                  * it's commit has been scheduled. */
610                 if (ptid)
611                         *ptid = tid;
612                 ret = 1;
613         } else if (journal->j_committing_transaction) {
614                 /*
615                  * If commit has been started, then we have to wait for
616                  * completion of that transaction.
617                  */
618                 if (ptid)
619                         *ptid = journal->j_committing_transaction->t_tid;
620                 ret = 1;
621         }
622         write_unlock(&journal->j_state_lock);
623         return ret;
624 }
625 
626 /*
627  * Return 1 if a given transaction has not yet sent barrier request
628  * connected with a transaction commit. If 0 is returned, transaction
629  * may or may not have sent the barrier. Used to avoid sending barrier
630  * twice in common cases.
631  */
632 int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid)
633 {
634         int ret = 0;
635         transaction_t *commit_trans;
636 
637         if (!(journal->j_flags & JBD2_BARRIER))
638                 return 0;
639         read_lock(&journal->j_state_lock);
640         /* Transaction already committed? */
641         if (tid_geq(journal->j_commit_sequence, tid))
642                 goto out;
643         commit_trans = journal->j_committing_transaction;
644         if (!commit_trans || commit_trans->t_tid != tid) {
645                 ret = 1;
646                 goto out;
647         }
648         /*
649          * Transaction is being committed and we already proceeded to
650          * submitting a flush to fs partition?
651          */
652         if (journal->j_fs_dev != journal->j_dev) {
653                 if (!commit_trans->t_need_data_flush ||
654                     commit_trans->t_state >= T_COMMIT_DFLUSH)
655                         goto out;
656         } else {
657                 if (commit_trans->t_state >= T_COMMIT_JFLUSH)
658                         goto out;
659         }
660         ret = 1;
661 out:
662         read_unlock(&journal->j_state_lock);
663         return ret;
664 }
665 EXPORT_SYMBOL(jbd2_trans_will_send_data_barrier);
666 
667 /*
668  * Wait for a specified commit to complete.
669  * The caller may not hold the journal lock.
670  */
671 int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
672 {
673         int err = 0;
674 
675         read_lock(&journal->j_state_lock);
676 #ifdef CONFIG_JBD2_DEBUG
677         if (!tid_geq(journal->j_commit_request, tid)) {
678                 printk(KERN_EMERG
679                        "%s: error: j_commit_request=%d, tid=%d\n",
680                        __func__, journal->j_commit_request, tid);
681         }
682 #endif
683         while (tid_gt(tid, journal->j_commit_sequence)) {
684                 jbd_debug(1, "JBD2: want %d, j_commit_sequence=%d\n",
685                                   tid, journal->j_commit_sequence);
686                 wake_up(&journal->j_wait_commit);
687                 read_unlock(&journal->j_state_lock);
688                 wait_event(journal->j_wait_done_commit,
689                                 !tid_gt(tid, journal->j_commit_sequence));
690                 read_lock(&journal->j_state_lock);
691         }
692         read_unlock(&journal->j_state_lock);
693 
694         if (unlikely(is_journal_aborted(journal))) {
695                 printk(KERN_EMERG "journal commit I/O error\n");
696                 err = -EIO;
697         }
698         return err;
699 }
700 
701 /*
702  * Log buffer allocation routines:
703  */
704 
705 int jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
706 {
707         unsigned long blocknr;
708 
709         write_lock(&journal->j_state_lock);
710         J_ASSERT(journal->j_free > 1);
711 
712         blocknr = journal->j_head;
713         journal->j_head++;
714         journal->j_free--;
715         if (journal->j_head == journal->j_last)
716                 journal->j_head = journal->j_first;
717         write_unlock(&journal->j_state_lock);
718         return jbd2_journal_bmap(journal, blocknr, retp);
719 }
720 
721 /*
722  * Conversion of logical to physical block numbers for the journal
723  *
724  * On external journals the journal blocks are identity-mapped, so
725  * this is a no-op.  If needed, we can use j_blk_offset - everything is
726  * ready.
727  */
728 int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
729                  unsigned long long *retp)
730 {
731         int err = 0;
732         unsigned long long ret;
733 
734         if (journal->j_inode) {
735                 ret = bmap(journal->j_inode, blocknr);
736                 if (ret)
737                         *retp = ret;
738                 else {
739                         printk(KERN_ALERT "%s: journal block not found "
740                                         "at offset %lu on %s\n",
741                                __func__, blocknr, journal->j_devname);
742                         err = -EIO;
743                         __journal_abort_soft(journal, err);
744                 }
745         } else {
746                 *retp = blocknr; /* +journal->j_blk_offset */
747         }
748         return err;
749 }
750 
751 /*
752  * We play buffer_head aliasing tricks to write data/metadata blocks to
753  * the journal without copying their contents, but for journal
754  * descriptor blocks we do need to generate bona fide buffers.
755  *
756  * After the caller of jbd2_journal_get_descriptor_buffer() has finished modifying
757  * the buffer's contents they really should run flush_dcache_page(bh->b_page).
758  * But we don't bother doing that, so there will be coherency problems with
759  * mmaps of blockdevs which hold live JBD-controlled filesystems.
760  */
761 struct journal_head *jbd2_journal_get_descriptor_buffer(journal_t *journal)
762 {
763         struct buffer_head *bh;
764         unsigned long long blocknr;
765         int err;
766 
767         err = jbd2_journal_next_log_block(journal, &blocknr);
768 
769         if (err)
770                 return NULL;
771 
772         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
773         if (!bh)
774                 return NULL;
775         lock_buffer(bh);
776         memset(bh->b_data, 0, journal->j_blocksize);
777         set_buffer_uptodate(bh);
778         unlock_buffer(bh);
779         BUFFER_TRACE(bh, "return this buffer");
780         return jbd2_journal_add_journal_head(bh);
781 }
782 
783 /*
784  * Return tid of the oldest transaction in the journal and block in the journal
785  * where the transaction starts.
786  *
787  * If the journal is now empty, return which will be the next transaction ID
788  * we will write and where will that transaction start.
789  *
790  * The return value is 0 if journal tail cannot be pushed any further, 1 if
791  * it can.
792  */
793 int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
794                               unsigned long *block)
795 {
796         transaction_t *transaction;
797         int ret;
798 
799         read_lock(&journal->j_state_lock);
800         spin_lock(&journal->j_list_lock);
801         transaction = journal->j_checkpoint_transactions;
802         if (transaction) {
803                 *tid = transaction->t_tid;
804                 *block = transaction->t_log_start;
805         } else if ((transaction = journal->j_committing_transaction) != NULL) {
806                 *tid = transaction->t_tid;
807                 *block = transaction->t_log_start;
808         } else if ((transaction = journal->j_running_transaction) != NULL) {
809                 *tid = transaction->t_tid;
810                 *block = journal->j_head;
811         } else {
812                 *tid = journal->j_transaction_sequence;
813                 *block = journal->j_head;
814         }
815         ret = tid_gt(*tid, journal->j_tail_sequence);
816         spin_unlock(&journal->j_list_lock);
817         read_unlock(&journal->j_state_lock);
818 
819         return ret;
820 }
821 
822 /*
823  * Update information in journal structure and in on disk journal superblock
824  * about log tail. This function does not check whether information passed in
825  * really pushes log tail further. It's responsibility of the caller to make
826  * sure provided log tail information is valid (e.g. by holding
827  * j_checkpoint_mutex all the time between computing log tail and calling this
828  * function as is the case with jbd2_cleanup_journal_tail()).
829  *
830  * Requires j_checkpoint_mutex
831  */
832 void __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
833 {
834         unsigned long freed;
835 
836         BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
837 
838         /*
839          * We cannot afford for write to remain in drive's caches since as
840          * soon as we update j_tail, next transaction can start reusing journal
841          * space and if we lose sb update during power failure we'd replay
842          * old transaction with possibly newly overwritten data.
843          */
844         jbd2_journal_update_sb_log_tail(journal, tid, block, WRITE_FUA);
845         write_lock(&journal->j_state_lock);
846         freed = block - journal->j_tail;
847         if (block < journal->j_tail)
848                 freed += journal->j_last - journal->j_first;
849 
850         trace_jbd2_update_log_tail(journal, tid, block, freed);
851         jbd_debug(1,
852                   "Cleaning journal tail from %d to %d (offset %lu), "
853                   "freeing %lu\n",
854                   journal->j_tail_sequence, tid, block, freed);
855 
856         journal->j_free += freed;
857         journal->j_tail_sequence = tid;
858         journal->j_tail = block;
859         write_unlock(&journal->j_state_lock);
860 }
861 
862 /*
863  * This is a variaon of __jbd2_update_log_tail which checks for validity of
864  * provided log tail and locks j_checkpoint_mutex. So it is safe against races
865  * with other threads updating log tail.
866  */
867 void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
868 {
869         mutex_lock(&journal->j_checkpoint_mutex);
870         if (tid_gt(tid, journal->j_tail_sequence))
871                 __jbd2_update_log_tail(journal, tid, block);
872         mutex_unlock(&journal->j_checkpoint_mutex);
873 }
874 
875 struct jbd2_stats_proc_session {
876         journal_t *journal;
877         struct transaction_stats_s *stats;
878         int start;
879         int max;
880 };
881 
882 static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos)
883 {
884         return *pos ? NULL : SEQ_START_TOKEN;
885 }
886 
887 static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
888 {
889         return NULL;
890 }
891 
892 static int jbd2_seq_info_show(struct seq_file *seq, void *v)
893 {
894         struct jbd2_stats_proc_session *s = seq->private;
895 
896         if (v != SEQ_START_TOKEN)
897                 return 0;
898         seq_printf(seq, "%lu transaction, each up to %u blocks\n",
899                         s->stats->ts_tid,
900                         s->journal->j_max_transaction_buffers);
901         if (s->stats->ts_tid == 0)
902                 return 0;
903         seq_printf(seq, "average: \n  %ums waiting for transaction\n",
904             jiffies_to_msecs(s->stats->run.rs_wait / s->stats->ts_tid));
905         seq_printf(seq, "  %ums running transaction\n",
906             jiffies_to_msecs(s->stats->run.rs_running / s->stats->ts_tid));
907         seq_printf(seq, "  %ums transaction was being locked\n",
908             jiffies_to_msecs(s->stats->run.rs_locked / s->stats->ts_tid));
909         seq_printf(seq, "  %ums flushing data (in ordered mode)\n",
910             jiffies_to_msecs(s->stats->run.rs_flushing / s->stats->ts_tid));
911         seq_printf(seq, "  %ums logging transaction\n",
912             jiffies_to_msecs(s->stats->run.rs_logging / s->stats->ts_tid));
913         seq_printf(seq, "  %lluus average transaction commit time\n",
914                    div_u64(s->journal->j_average_commit_time, 1000));
915         seq_printf(seq, "  %lu handles per transaction\n",
916             s->stats->run.rs_handle_count / s->stats->ts_tid);
917         seq_printf(seq, "  %lu blocks per transaction\n",
918             s->stats->run.rs_blocks / s->stats->ts_tid);
919         seq_printf(seq, "  %lu logged blocks per transaction\n",
920             s->stats->run.rs_blocks_logged / s->stats->ts_tid);
921         return 0;
922 }
923 
924 static void jbd2_seq_info_stop(struct seq_file *seq, void *v)
925 {
926 }
927 
928 static const struct seq_operations jbd2_seq_info_ops = {
929         .start  = jbd2_seq_info_start,
930         .next   = jbd2_seq_info_next,
931         .stop   = jbd2_seq_info_stop,
932         .show   = jbd2_seq_info_show,
933 };
934 
935 static int jbd2_seq_info_open(struct inode *inode, struct file *file)
936 {
937         journal_t *journal = PDE(inode)->data;
938         struct jbd2_stats_proc_session *s;
939         int rc, size;
940 
941         s = kmalloc(sizeof(*s), GFP_KERNEL);
942         if (s == NULL)
943                 return -ENOMEM;
944         size = sizeof(struct transaction_stats_s);
945         s->stats = kmalloc(size, GFP_KERNEL);
946         if (s->stats == NULL) {
947                 kfree(s);
948                 return -ENOMEM;
949         }
950         spin_lock(&journal->j_history_lock);
951         memcpy(s->stats, &journal->j_stats, size);
952         s->journal = journal;
953         spin_unlock(&journal->j_history_lock);
954 
955         rc = seq_open(file, &jbd2_seq_info_ops);
956         if (rc == 0) {
957                 struct seq_file *m = file->private_data;
958                 m->private = s;
959         } else {
960                 kfree(s->stats);
961                 kfree(s);
962         }
963         return rc;
964 
965 }
966 
967 static int jbd2_seq_info_release(struct inode *inode, struct file *file)
968 {
969         struct seq_file *seq = file->private_data;
970         struct jbd2_stats_proc_session *s = seq->private;
971         kfree(s->stats);
972         kfree(s);
973         return seq_release(inode, file);
974 }
975 
976 static const struct file_operations jbd2_seq_info_fops = {
977         .owner          = THIS_MODULE,
978         .open           = jbd2_seq_info_open,
979         .read           = seq_read,
980         .llseek         = seq_lseek,
981         .release        = jbd2_seq_info_release,
982 };
983 
984 static struct proc_dir_entry *proc_jbd2_stats;
985 
986 static void jbd2_stats_proc_init(journal_t *journal)
987 {
988         journal->j_proc_entry = proc_mkdir(journal->j_devname, proc_jbd2_stats);
989         if (journal->j_proc_entry) {
990                 proc_create_data("info", S_IRUGO, journal->j_proc_entry,
991                                  &jbd2_seq_info_fops, journal);
992         }
993 }
994 
995 static void jbd2_stats_proc_exit(journal_t *journal)
996 {
997         remove_proc_entry("info", journal->j_proc_entry);
998         remove_proc_entry(journal->j_devname, proc_jbd2_stats);
999 }
1000 
1001 /*
1002  * Management for journal control blocks: functions to create and
1003  * destroy journal_t structures, and to initialise and read existing
1004  * journal blocks from disk.  */
1005 
1006 /* First: create and setup a journal_t object in memory.  We initialise
1007  * very few fields yet: that has to wait until we have created the
1008  * journal structures from from scratch, or loaded them from disk. */
1009 
1010 static journal_t * journal_init_common (void)
1011 {
1012         journal_t *journal;
1013         int err;
1014 
1015         journal = kzalloc(sizeof(*journal), GFP_KERNEL);
1016         if (!journal)
1017                 return NULL;
1018 
1019         init_waitqueue_head(&journal->j_wait_transaction_locked);
1020         init_waitqueue_head(&journal->j_wait_logspace);
1021         init_waitqueue_head(&journal->j_wait_done_commit);
1022         init_waitqueue_head(&journal->j_wait_checkpoint);
1023         init_waitqueue_head(&journal->j_wait_commit);
1024         init_waitqueue_head(&journal->j_wait_updates);
1025         mutex_init(&journal->j_barrier);
1026         mutex_init(&journal->j_checkpoint_mutex);
1027         spin_lock_init(&journal->j_revoke_lock);
1028         spin_lock_init(&journal->j_list_lock);
1029         rwlock_init(&journal->j_state_lock);
1030 
1031         journal->j_commit_interval = (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE);
1032         journal->j_min_batch_time = 0;
1033         journal->j_max_batch_time = 15000; /* 15ms */
1034 
1035         /* The journal is marked for error until we succeed with recovery! */
1036         journal->j_flags = JBD2_ABORT;
1037 
1038         /* Set up a default-sized revoke table for the new mount. */
1039         err = jbd2_journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
1040         if (err) {
1041                 kfree(journal);
1042                 return NULL;
1043         }
1044 
1045         spin_lock_init(&journal->j_history_lock);
1046 
1047         return journal;
1048 }
1049 
1050 /* jbd2_journal_init_dev and jbd2_journal_init_inode:
1051  *
1052  * Create a journal structure assigned some fixed set of disk blocks to
1053  * the journal.  We don't actually touch those disk blocks yet, but we
1054  * need to set up all of the mapping information to tell the journaling
1055  * system where the journal blocks are.
1056  *
1057  */
1058 
1059 /**
1060  *  journal_t * jbd2_journal_init_dev() - creates and initialises a journal structure
1061  *  @bdev: Block device on which to create the journal
1062  *  @fs_dev: Device which hold journalled filesystem for this journal.
1063  *  @start: Block nr Start of journal.
1064  *  @len:  Length of the journal in blocks.
1065  *  @blocksize: blocksize of journalling device
1066  *
1067  *  Returns: a newly created journal_t *
1068  *
1069  *  jbd2_journal_init_dev creates a journal which maps a fixed contiguous
1070  *  range of blocks on an arbitrary block device.
1071  *
1072  */
1073 journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1074                         struct block_device *fs_dev,
1075                         unsigned long long start, int len, int blocksize)
1076 {
1077         journal_t *journal = journal_init_common();
1078         struct buffer_head *bh;
1079         char *p;
1080         int n;
1081 
1082         if (!journal)
1083                 return NULL;
1084 
1085         /* journal descriptor can store up to n blocks -bzzz */
1086         journal->j_blocksize = blocksize;
1087         journal->j_dev = bdev;
1088         journal->j_fs_dev = fs_dev;
1089         journal->j_blk_offset = start;
1090         journal->j_maxlen = len;
1091         bdevname(journal->j_dev, journal->j_devname);
1092         p = journal->j_devname;
1093         while ((p = strchr(p, '/')))
1094                 *p = '!';
1095         jbd2_stats_proc_init(journal);
1096         n = journal->j_blocksize / sizeof(journal_block_tag_t);
1097         journal->j_wbufsize = n;
1098         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
1099         if (!journal->j_wbuf) {
1100                 printk(KERN_ERR "%s: Can't allocate bhs for commit thread\n",
1101                         __func__);
1102                 goto out_err;
1103         }
1104 
1105         bh = __getblk(journal->j_dev, start, journal->j_blocksize);
1106         if (!bh) {
1107                 printk(KERN_ERR
1108                        "%s: Cannot get buffer for journal superblock\n",
1109                        __func__);
1110                 goto out_err;
1111         }
1112         journal->j_sb_buffer = bh;
1113         journal->j_superblock = (journal_superblock_t *)bh->b_data;
1114 
1115         return journal;
1116 out_err:
1117         kfree(journal->j_wbuf);
1118         jbd2_stats_proc_exit(journal);
1119         kfree(journal);
1120         return NULL;
1121 }
1122 
1123 /**
1124  *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
1125  *  @inode: An inode to create the journal in
1126  *
1127  * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
1128  * the journal.  The inode must exist already, must support bmap() and
1129  * must have all data blocks preallocated.
1130  */
1131 journal_t * jbd2_journal_init_inode (struct inode *inode)
1132 {
1133         struct buffer_head *bh;
1134         journal_t *journal = journal_init_common();
1135         char *p;
1136         int err;
1137         int n;
1138         unsigned long long blocknr;
1139 
1140         if (!journal)
1141                 return NULL;
1142 
1143         journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
1144         journal->j_inode = inode;
1145         bdevname(journal->j_dev, journal->j_devname);
1146         p = journal->j_devname;
1147         while ((p = strchr(p, '/')))
1148                 *p = '!';
1149         p = journal->j_devname + strlen(journal->j_devname);
1150         sprintf(p, "-%lu", journal->j_inode->i_ino);
1151         jbd_debug(1,
1152                   "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
1153                   journal, inode->i_sb->s_id, inode->i_ino,
1154                   (long long) inode->i_size,
1155                   inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
1156 
1157         journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
1158         journal->j_blocksize = inode->i_sb->s_blocksize;
1159         jbd2_stats_proc_init(journal);
1160 
1161         /* journal descriptor can store up to n blocks -bzzz */
1162         n = journal->j_blocksize / sizeof(journal_block_tag_t);
1163         journal->j_wbufsize = n;
1164         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
1165         if (!journal->j_wbuf) {
1166                 printk(KERN_ERR "%s: Can't allocate bhs for commit thread\n",
1167                         __func__);
1168                 goto out_err;
1169         }
1170 
1171         err = jbd2_journal_bmap(journal, 0, &blocknr);
1172         /* If that failed, give up */
1173         if (err) {
1174                 printk(KERN_ERR "%s: Cannot locate journal superblock\n",
1175                        __func__);
1176                 goto out_err;
1177         }
1178 
1179         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
1180         if (!bh) {
1181                 printk(KERN_ERR
1182                        "%s: Cannot get buffer for journal superblock\n",
1183                        __func__);
1184                 goto out_err;
1185         }
1186         journal->j_sb_buffer = bh;
1187         journal->j_superblock = (journal_superblock_t *)bh->b_data;
1188 
1189         return journal;
1190 out_err:
1191         kfree(journal->j_wbuf);
1192         jbd2_stats_proc_exit(journal);
1193         kfree(journal);
1194         return NULL;
1195 }
1196 
1197 /*
1198  * If the journal init or create aborts, we need to mark the journal
1199  * superblock as being NULL to prevent the journal destroy from writing
1200  * back a bogus superblock.
1201  */
1202 static void journal_fail_superblock (journal_t *journal)
1203 {
1204         struct buffer_head *bh = journal->j_sb_buffer;
1205         brelse(bh);
1206         journal->j_sb_buffer = NULL;
1207 }
1208 
1209 /*
1210  * Given a journal_t structure, initialise the various fields for
1211  * startup of a new journaling session.  We use this both when creating
1212  * a journal, and after recovering an old journal to reset it for
1213  * subsequent use.
1214  */
1215 
1216 static int journal_reset(journal_t *journal)
1217 {
1218         journal_superblock_t *sb = journal->j_superblock;
1219         unsigned long long first, last;
1220 
1221         first = be32_to_cpu(sb->s_first);
1222         last = be32_to_cpu(sb->s_maxlen);
1223         if (first + JBD2_MIN_JOURNAL_BLOCKS > last + 1) {
1224                 printk(KERN_ERR "JBD2: Journal too short (blocks %llu-%llu).\n",
1225                        first, last);
1226                 journal_fail_superblock(journal);
1227                 return -EINVAL;
1228         }
1229 
1230         journal->j_first = first;
1231         journal->j_last = last;
1232 
1233         journal->j_head = first;
1234         journal->j_tail = first;
1235         journal->j_free = last - first;
1236 
1237         journal->j_tail_sequence = journal->j_transaction_sequence;
1238         journal->j_commit_sequence = journal->j_transaction_sequence - 1;
1239         journal->j_commit_request = journal->j_commit_sequence;
1240 
1241         journal->j_max_transaction_buffers = journal->j_maxlen / 4;
1242 
1243         /*
1244          * As a special case, if the on-disk copy is already marked as needing
1245          * no recovery (s_start == 0), then we can safely defer the superblock
1246          * update until the next commit by setting JBD2_FLUSHED.  This avoids
1247          * attempting a write to a potential-readonly device.
1248          */
1249         if (sb->s_start == 0) {
1250                 jbd_debug(1, "JBD2: Skipping superblock update on recovered sb "
1251                         "(start %ld, seq %d, errno %d)\n",
1252                         journal->j_tail, journal->j_tail_sequence,
1253                         journal->j_errno);
1254                 journal->j_flags |= JBD2_FLUSHED;
1255         } else {
1256                 /* Lock here to make assertions happy... */
1257                 mutex_lock(&journal->j_checkpoint_mutex);
1258                 /*
1259                  * Update log tail information. We use WRITE_FUA since new
1260                  * transaction will start reusing journal space and so we
1261                  * must make sure information about current log tail is on
1262                  * disk before that.
1263                  */
1264                 jbd2_journal_update_sb_log_tail(journal,
1265                                                 journal->j_tail_sequence,
1266                                                 journal->j_tail,
1267                                                 WRITE_FUA);
1268                 mutex_unlock(&journal->j_checkpoint_mutex);
1269         }
1270         return jbd2_journal_start_thread(journal);
1271 }
1272 
1273 static void jbd2_write_superblock(journal_t *journal, int write_op)
1274 {
1275         struct buffer_head *bh = journal->j_sb_buffer;
1276         int ret;
1277 
1278         trace_jbd2_write_superblock(journal, write_op);
1279         if (!(journal->j_flags & JBD2_BARRIER))
1280                 write_op &= ~(REQ_FUA | REQ_FLUSH);
1281         lock_buffer(bh);
1282         if (buffer_write_io_error(bh)) {
1283                 /*
1284                  * Oh, dear.  A previous attempt to write the journal
1285                  * superblock failed.  This could happen because the
1286                  * USB device was yanked out.  Or it could happen to
1287                  * be a transient write error and maybe the block will
1288                  * be remapped.  Nothing we can do but to retry the
1289                  * write and hope for the best.
1290                  */
1291                 printk(KERN_ERR "JBD2: previous I/O error detected "
1292                        "for journal superblock update for %s.\n",
1293                        journal->j_devname);
1294                 clear_buffer_write_io_error(bh);
1295                 set_buffer_uptodate(bh);
1296         }
1297         get_bh(bh);
1298         bh->b_end_io = end_buffer_write_sync;
1299         ret = submit_bh(write_op, bh);
1300         wait_on_buffer(bh);
1301         if (buffer_write_io_error(bh)) {
1302                 clear_buffer_write_io_error(bh);
1303                 set_buffer_uptodate(bh);
1304                 ret = -EIO;
1305         }
1306         if (ret) {
1307                 printk(KERN_ERR "JBD2: Error %d detected when updating "
1308                        "journal superblock for %s.\n", ret,
1309                        journal->j_devname);
1310         }
1311 }
1312 
1313 /**
1314  * jbd2_journal_update_sb_log_tail() - Update log tail in journal sb on disk.
1315  * @journal: The journal to update.
1316  * @tail_tid: TID of the new transaction at the tail of the log
1317  * @tail_block: The first block of the transaction at the tail of the log
1318  * @write_op: With which operation should we write the journal sb
1319  *
1320  * Update a journal's superblock information about log tail and write it to
1321  * disk, waiting for the IO to complete.
1322  */
1323 void jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
1324                                      unsigned long tail_block, int write_op)
1325 {
1326         journal_superblock_t *sb = journal->j_superblock;
1327 
1328         BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1329         jbd_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n",
1330                   tail_block, tail_tid);
1331 
1332         sb->s_sequence = cpu_to_be32(tail_tid);
1333         sb->s_start    = cpu_to_be32(tail_block);
1334 
1335         jbd2_write_superblock(journal, write_op);
1336 
1337         /* Log is no longer empty */
1338         write_lock(&journal->j_state_lock);
1339         WARN_ON(!sb->s_sequence);
1340         journal->j_flags &= ~JBD2_FLUSHED;
1341         write_unlock(&journal->j_state_lock);
1342 }
1343 
1344 /**
1345  * jbd2_mark_journal_empty() - Mark on disk journal as empty.
1346  * @journal: The journal to update.
1347  *
1348  * Update a journal's dynamic superblock fields to show that journal is empty.
1349  * Write updated superblock to disk waiting for IO to complete.
1350  */
1351 static void jbd2_mark_journal_empty(journal_t *journal)
1352 {
1353         journal_superblock_t *sb = journal->j_superblock;
1354 
1355         BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1356         read_lock(&journal->j_state_lock);
1357         /* Is it already empty? */
1358         if (sb->s_start == 0) {
1359                 read_unlock(&journal->j_state_lock);
1360                 return;
1361         }
1362         jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n",
1363                   journal->j_tail_sequence);
1364 
1365         sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
1366         sb->s_start    = cpu_to_be32(0);
1367         read_unlock(&journal->j_state_lock);
1368 
1369         jbd2_write_superblock(journal, WRITE_FUA);
1370 
1371         /* Log is no longer empty */
1372         write_lock(&journal->j_state_lock);
1373         journal->j_flags |= JBD2_FLUSHED;
1374         write_unlock(&journal->j_state_lock);
1375 }
1376 
1377 
1378 /**
1379  * jbd2_journal_update_sb_errno() - Update error in the journal.
1380  * @journal: The journal to update.
1381  *
1382  * Update a journal's errno.  Write updated superblock to disk waiting for IO
1383  * to complete.
1384  */
1385 void jbd2_journal_update_sb_errno(journal_t *journal)
1386 {
1387         journal_superblock_t *sb = journal->j_superblock;
1388 
1389         read_lock(&journal->j_state_lock);
1390         jbd_debug(1, "JBD2: updating superblock error (errno %d)\n",
1391                   journal->j_errno);
1392         sb->s_errno    = cpu_to_be32(journal->j_errno);
1393         jbd2_superblock_csum_set(journal, sb);
1394         read_unlock(&journal->j_state_lock);
1395 
1396         jbd2_write_superblock(journal, WRITE_SYNC);
1397 }
1398 EXPORT_SYMBOL(jbd2_journal_update_sb_errno);
1399 
1400 /*
1401  * Read the superblock for a given journal, performing initial
1402  * validation of the format.
1403  */
1404 static int journal_get_superblock(journal_t *journal)
1405 {
1406         struct buffer_head *bh;
1407         journal_superblock_t *sb;
1408         int err = -EIO;
1409 
1410         bh = journal->j_sb_buffer;
1411 
1412         J_ASSERT(bh != NULL);
1413         if (!buffer_uptodate(bh)) {
1414                 ll_rw_block(READ, 1, &bh);
1415                 wait_on_buffer(bh);
1416                 if (!buffer_uptodate(bh)) {
1417                         printk(KERN_ERR
1418                                 "JBD2: IO error reading journal superblock\n");
1419                         goto out;
1420                 }
1421         }
1422 
1423         if (buffer_verified(bh))
1424                 return 0;
1425 
1426         sb = journal->j_superblock;
1427 
1428         err = -EINVAL;
1429 
1430         if (sb->s_header.h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER) ||
1431             sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1432                 printk(KERN_WARNING "JBD2: no valid journal superblock found\n");
1433                 goto out;
1434         }
1435 
1436         switch(be32_to_cpu(sb->s_header.h_blocktype)) {
1437         case JBD2_SUPERBLOCK_V1:
1438                 journal->j_format_version = 1;
1439                 break;
1440         case JBD2_SUPERBLOCK_V2:
1441                 journal->j_format_version = 2;
1442                 break;
1443         default:
1444                 printk(KERN_WARNING "JBD2: unrecognised superblock format ID\n");
1445                 goto out;
1446         }
1447 
1448         if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
1449                 journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
1450         else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
1451                 printk(KERN_WARNING "JBD2: journal file too short\n");
1452                 goto out;
1453         }
1454 
1455         if (be32_to_cpu(sb->s_first) == 0 ||
1456             be32_to_cpu(sb->s_first) >= journal->j_maxlen) {
1457                 printk(KERN_WARNING
1458                         "JBD2: Invalid start block of journal: %u\n",
1459                         be32_to_cpu(sb->s_first));
1460                 goto out;
1461         }
1462 
1463         if (JBD2_HAS_COMPAT_FEATURE(journal, JBD2_FEATURE_COMPAT_CHECKSUM) &&
1464             JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
1465                 /* Can't have checksum v1 and v2 on at the same time! */
1466                 printk(KERN_ERR "JBD: Can't enable checksumming v1 and v2 "
1467                        "at the same time!\n");
1468                 goto out;
1469         }
1470 
1471         if (!jbd2_verify_csum_type(journal, sb)) {
1472                 printk(KERN_ERR "JBD: Unknown checksum type\n");
1473                 goto out;
1474         }
1475 
1476         /* Load the checksum driver */
1477         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
1478                 journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
1479                 if (IS_ERR(journal->j_chksum_driver)) {
1480                         printk(KERN_ERR "JBD: Cannot load crc32c driver.\n");
1481                         err = PTR_ERR(journal->j_chksum_driver);
1482                         journal->j_chksum_driver = NULL;
1483                         goto out;
1484                 }
1485         }
1486 
1487         /* Check superblock checksum */
1488         if (!jbd2_superblock_csum_verify(journal, sb)) {
1489                 printk(KERN_ERR "JBD: journal checksum error\n");
1490                 goto out;
1491         }
1492 
1493         /* Precompute checksum seed for all metadata */
1494         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
1495                 journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid,
1496                                                    sizeof(sb->s_uuid));
1497 
1498         set_buffer_verified(bh);
1499 
1500         return 0;
1501 
1502 out:
1503         journal_fail_superblock(journal);
1504         return err;
1505 }
1506 
1507 /*
1508  * Load the on-disk journal superblock and read the key fields into the
1509  * journal_t.
1510  */
1511 
1512 static int load_superblock(journal_t *journal)
1513 {
1514         int err;
1515         journal_superblock_t *sb;
1516 
1517         err = journal_get_superblock(journal);
1518         if (err)
1519                 return err;
1520 
1521         sb = journal->j_superblock;
1522 
1523         journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1524         journal->j_tail = be32_to_cpu(sb->s_start);
1525         journal->j_first = be32_to_cpu(sb->s_first);
1526         journal->j_last = be32_to_cpu(sb->s_maxlen);
1527         journal->j_errno = be32_to_cpu(sb->s_errno);
1528 
1529         return 0;
1530 }
1531 
1532 
1533 /**
1534  * int jbd2_journal_load() - Read journal from disk.
1535  * @journal: Journal to act on.
1536  *
1537  * Given a journal_t structure which tells us which disk blocks contain
1538  * a journal, read the journal from disk to initialise the in-memory
1539  * structures.
1540  */
1541 int jbd2_journal_load(journal_t *journal)
1542 {
1543         int err;
1544         journal_superblock_t *sb;
1545 
1546         err = load_superblock(journal);
1547         if (err)
1548                 return err;
1549 
1550         sb = journal->j_superblock;
1551         /* If this is a V2 superblock, then we have to check the
1552          * features flags on it. */
1553 
1554         if (journal->j_format_version >= 2) {
1555                 if ((sb->s_feature_ro_compat &
1556                      ~cpu_to_be32(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
1557                     (sb->s_feature_incompat &
1558                      ~cpu_to_be32(JBD2_KNOWN_INCOMPAT_FEATURES))) {
1559                         printk(KERN_WARNING
1560                                 "JBD2: Unrecognised features on journal\n");
1561                         return -EINVAL;
1562                 }
1563         }
1564 
1565         /*
1566          * Create a slab for this blocksize
1567          */
1568         err = jbd2_journal_create_slab(be32_to_cpu(sb->s_blocksize));
1569         if (err)
1570                 return err;
1571 
1572         /* Let the recovery code check whether it needs to recover any
1573          * data from the journal. */
1574         if (jbd2_journal_recover(journal))
1575                 goto recovery_error;
1576 
1577         if (journal->j_failed_commit) {
1578                 printk(KERN_ERR "JBD2: journal transaction %u on %s "
1579                        "is corrupt.\n", journal->j_failed_commit,
1580                        journal->j_devname);
1581                 return -EIO;
1582         }
1583 
1584         /* OK, we've finished with the dynamic journal bits:
1585          * reinitialise the dynamic contents of the superblock in memory
1586          * and reset them on disk. */
1587         if (journal_reset(journal))
1588                 goto recovery_error;
1589 
1590         journal->j_flags &= ~JBD2_ABORT;
1591         journal->j_flags |= JBD2_LOADED;
1592         return 0;
1593 
1594 recovery_error:
1595         printk(KERN_WARNING "JBD2: recovery failed\n");
1596         return -EIO;
1597 }
1598 
1599 /**
1600  * void jbd2_journal_destroy() - Release a journal_t structure.
1601  * @journal: Journal to act on.
1602  *
1603  * Release a journal_t structure once it is no longer in use by the
1604  * journaled object.
1605  * Return <0 if we couldn't clean up the journal.
1606  */
1607 int jbd2_journal_destroy(journal_t *journal)
1608 {
1609         int err = 0;
1610 
1611         /* Wait for the commit thread to wake up and die. */
1612         journal_kill_thread(journal);
1613 
1614         /* Force a final log commit */
1615         if (journal->j_running_transaction)
1616                 jbd2_journal_commit_transaction(journal);
1617 
1618         /* Force any old transactions to disk */
1619 
1620         /* Totally anal locking here... */
1621         spin_lock(&journal->j_list_lock);
1622         while (journal->j_checkpoint_transactions != NULL) {
1623                 spin_unlock(&journal->j_list_lock);
1624                 mutex_lock(&journal->j_checkpoint_mutex);
1625                 jbd2_log_do_checkpoint(journal);
1626                 mutex_unlock(&journal->j_checkpoint_mutex);
1627                 spin_lock(&journal->j_list_lock);
1628         }
1629 
1630         J_ASSERT(journal->j_running_transaction == NULL);
1631         J_ASSERT(journal->j_committing_transaction == NULL);
1632         J_ASSERT(journal->j_checkpoint_transactions == NULL);
1633         spin_unlock(&journal->j_list_lock);
1634 
1635         if (journal->j_sb_buffer) {
1636                 if (!is_journal_aborted(journal)) {
1637                         mutex_lock(&journal->j_checkpoint_mutex);
1638                         jbd2_mark_journal_empty(journal);
1639                         mutex_unlock(&journal->j_checkpoint_mutex);
1640                 } else
1641                         err = -EIO;
1642                 brelse(journal->j_sb_buffer);
1643         }
1644 
1645         if (journal->j_proc_entry)
1646                 jbd2_stats_proc_exit(journal);
1647         if (journal->j_inode)
1648                 iput(journal->j_inode);
1649         if (journal->j_revoke)
1650                 jbd2_journal_destroy_revoke(journal);
1651         if (journal->j_chksum_driver)
1652                 crypto_free_shash(journal->j_chksum_driver);
1653         kfree(journal->j_wbuf);
1654         kfree(journal);
1655 
1656         return err;
1657 }
1658 
1659 
1660 /**
1661  *int jbd2_journal_check_used_features () - Check if features specified are used.
1662  * @journal: Journal to check.
1663  * @compat: bitmask of compatible features
1664  * @ro: bitmask of features that force read-only mount
1665  * @incompat: bitmask of incompatible features
1666  *
1667  * Check whether the journal uses all of a given set of
1668  * features.  Return true (non-zero) if it does.
1669  **/
1670 
1671 int jbd2_journal_check_used_features (journal_t *journal, unsigned long compat,
1672                                  unsigned long ro, unsigned long incompat)
1673 {
1674         journal_superblock_t *sb;
1675 
1676         if (!compat && !ro && !incompat)
1677                 return 1;
1678         /* Load journal superblock if it is not loaded yet. */
1679         if (journal->j_format_version == 0 &&
1680             journal_get_superblock(journal) != 0)
1681                 return 0;
1682         if (journal->j_format_version == 1)
1683                 return 0;
1684 
1685         sb = journal->j_superblock;
1686 
1687         if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1688             ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1689             ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1690                 return 1;
1691 
1692         return 0;
1693 }
1694 
1695 /**
1696  * int jbd2_journal_check_available_features() - Check feature set in journalling layer
1697  * @journal: Journal to check.
1698  * @compat: bitmask of compatible features
1699  * @ro: bitmask of features that force read-only mount
1700  * @incompat: bitmask of incompatible features
1701  *
1702  * Check whether the journaling code supports the use of
1703  * all of a given set of features on this journal.  Return true
1704  * (non-zero) if it can. */
1705 
1706 int jbd2_journal_check_available_features (journal_t *journal, unsigned long compat,
1707                                       unsigned long ro, unsigned long incompat)
1708 {
1709         if (!compat && !ro && !incompat)
1710                 return 1;
1711 
1712         /* We can support any known requested features iff the
1713          * superblock is in version 2.  Otherwise we fail to support any
1714          * extended sb features. */
1715 
1716         if (journal->j_format_version != 2)
1717                 return 0;
1718 
1719         if ((compat   & JBD2_KNOWN_COMPAT_FEATURES) == compat &&
1720             (ro       & JBD2_KNOWN_ROCOMPAT_FEATURES) == ro &&
1721             (incompat & JBD2_KNOWN_INCOMPAT_FEATURES) == incompat)
1722                 return 1;
1723 
1724         return 0;
1725 }
1726 
1727 /**
1728  * int jbd2_journal_set_features () - Mark a given journal feature in the superblock
1729  * @journal: Journal to act on.
1730  * @compat: bitmask of compatible features
1731  * @ro: bitmask of features that force read-only mount
1732  * @incompat: bitmask of incompatible features
1733  *
1734  * Mark a given journal feature as present on the
1735  * superblock.  Returns true if the requested features could be set.
1736  *
1737  */
1738 
1739 int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
1740                           unsigned long ro, unsigned long incompat)
1741 {
1742 #define INCOMPAT_FEATURE_ON(f) \
1743                 ((incompat & (f)) && !(sb->s_feature_incompat & cpu_to_be32(f)))
1744 #define COMPAT_FEATURE_ON(f) \
1745                 ((compat & (f)) && !(sb->s_feature_compat & cpu_to_be32(f)))
1746         journal_superblock_t *sb;
1747 
1748         if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
1749                 return 1;
1750 
1751         if (!jbd2_journal_check_available_features(journal, compat, ro, incompat))
1752                 return 0;
1753 
1754         /* Asking for checksumming v2 and v1?  Only give them v2. */
1755         if (incompat & JBD2_FEATURE_INCOMPAT_CSUM_V2 &&
1756             compat & JBD2_FEATURE_COMPAT_CHECKSUM)
1757                 compat &= ~JBD2_FEATURE_COMPAT_CHECKSUM;
1758 
1759         jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1760                   compat, ro, incompat);
1761 
1762         sb = journal->j_superblock;
1763 
1764         /* If enabling v2 checksums, update superblock */
1765         if (INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
1766                 sb->s_checksum_type = JBD2_CRC32C_CHKSUM;
1767                 sb->s_feature_compat &=
1768                         ~cpu_to_be32(JBD2_FEATURE_COMPAT_CHECKSUM);
1769 
1770                 /* Load the checksum driver */
1771                 if (journal->j_chksum_driver == NULL) {
1772                         journal->j_chksum_driver = crypto_alloc_shash("crc32c",
1773                                                                       0, 0);
1774                         if (IS_ERR(journal->j_chksum_driver)) {
1775                                 printk(KERN_ERR "JBD: Cannot load crc32c "
1776                                        "driver.\n");
1777                                 journal->j_chksum_driver = NULL;
1778                                 return 0;
1779                         }
1780                 }
1781 
1782                 /* Precompute checksum seed for all metadata */
1783                 if (JBD2_HAS_INCOMPAT_FEATURE(journal,
1784                                               JBD2_FEATURE_INCOMPAT_CSUM_V2))
1785                         journal->j_csum_seed = jbd2_chksum(journal, ~0,
1786                                                            sb->s_uuid,
1787                                                            sizeof(sb->s_uuid));
1788         }
1789 
1790         /* If enabling v1 checksums, downgrade superblock */
1791         if (COMPAT_FEATURE_ON(JBD2_FEATURE_COMPAT_CHECKSUM))
1792                 sb->s_feature_incompat &=
1793                         ~cpu_to_be32(JBD2_FEATURE_INCOMPAT_CSUM_V2);
1794 
1795         sb->s_feature_compat    |= cpu_to_be32(compat);
1796         sb->s_feature_ro_compat |= cpu_to_be32(ro);
1797         sb->s_feature_incompat  |= cpu_to_be32(incompat);
1798 
1799         return 1;
1800 #undef COMPAT_FEATURE_ON
1801 #undef INCOMPAT_FEATURE_ON
1802 }
1803 
1804 /*
1805  * jbd2_journal_clear_features () - Clear a given journal feature in the
1806  *                                  superblock
1807  * @journal: Journal to act on.
1808  * @compat: bitmask of compatible features
1809  * @ro: bitmask of features that force read-only mount
1810  * @incompat: bitmask of incompatible features
1811  *
1812  * Clear a given journal feature as present on the
1813  * superblock.
1814  */
1815 void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
1816                                 unsigned long ro, unsigned long incompat)
1817 {
1818         journal_superblock_t *sb;
1819 
1820         jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
1821                   compat, ro, incompat);
1822 
1823         sb = journal->j_superblock;
1824 
1825         sb->s_feature_compat    &= ~cpu_to_be32(compat);
1826         sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
1827         sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
1828 }
1829 EXPORT_SYMBOL(jbd2_journal_clear_features);
1830 
1831 /**
1832  * int jbd2_journal_flush () - Flush journal
1833  * @journal: Journal to act on.
1834  *
1835  * Flush all data for a given journal to disk and empty the journal.
1836  * Filesystems can use this when remounting readonly to ensure that
1837  * recovery does not need to happen on remount.
1838  */
1839 
1840 int jbd2_journal_flush(journal_t *journal)
1841 {
1842         int err = 0;
1843         transaction_t *transaction = NULL;
1844 
1845         write_lock(&journal->j_state_lock);
1846 
1847         /* Force everything buffered to the log... */
1848         if (journal->j_running_transaction) {
1849                 transaction = journal->j_running_transaction;
1850                 __jbd2_log_start_commit(journal, transaction->t_tid);
1851         } else if (journal->j_committing_transaction)
1852                 transaction = journal->j_committing_transaction;
1853 
1854         /* Wait for the log commit to complete... */
1855         if (transaction) {
1856                 tid_t tid = transaction->t_tid;
1857 
1858                 write_unlock(&journal->j_state_lock);
1859                 jbd2_log_wait_commit(journal, tid);
1860         } else {
1861                 write_unlock(&journal->j_state_lock);
1862         }
1863 
1864         /* ...and flush everything in the log out to disk. */
1865         spin_lock(&journal->j_list_lock);
1866         while (!err && journal->j_checkpoint_transactions != NULL) {
1867                 spin_unlock(&journal->j_list_lock);
1868                 mutex_lock(&journal->j_checkpoint_mutex);
1869                 err = jbd2_log_do_checkpoint(journal);
1870                 mutex_unlock(&journal->j_checkpoint_mutex);
1871                 spin_lock(&journal->j_list_lock);
1872         }
1873         spin_unlock(&journal->j_list_lock);
1874 
1875         if (is_journal_aborted(journal))
1876                 return -EIO;
1877 
1878         mutex_lock(&journal->j_checkpoint_mutex);
1879         jbd2_cleanup_journal_tail(journal);
1880 
1881         /* Finally, mark the journal as really needing no recovery.
1882          * This sets s_start==0 in the underlying superblock, which is
1883          * the magic code for a fully-recovered superblock.  Any future
1884          * commits of data to the journal will restore the current
1885          * s_start value. */
1886         jbd2_mark_journal_empty(journal);
1887         mutex_unlock(&journal->j_checkpoint_mutex);
1888         write_lock(&journal->j_state_lock);
1889         J_ASSERT(!journal->j_running_transaction);
1890         J_ASSERT(!journal->j_committing_transaction);
1891         J_ASSERT(!journal->j_checkpoint_transactions);
1892         J_ASSERT(journal->j_head == journal->j_tail);
1893         J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1894         write_unlock(&journal->j_state_lock);
1895         return 0;
1896 }
1897 
1898 /**
1899  * int jbd2_journal_wipe() - Wipe journal contents
1900  * @journal: Journal to act on.
1901  * @write: flag (see below)
1902  *
1903  * Wipe out all of the contents of a journal, safely.  This will produce
1904  * a warning if the journal contains any valid recovery information.
1905  * Must be called between journal_init_*() and jbd2_journal_load().
1906  *
1907  * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
1908  * we merely suppress recovery.
1909  */
1910 
1911 int jbd2_journal_wipe(journal_t *journal, int write)
1912 {
1913         int err = 0;
1914 
1915         J_ASSERT (!(journal->j_flags & JBD2_LOADED));
1916 
1917         err = load_superblock(journal);
1918         if (err)
1919                 return err;
1920 
1921         if (!journal->j_tail)
1922                 goto no_recovery;
1923 
1924         printk(KERN_WARNING "JBD2: %s recovery information on journal\n",
1925                 write ? "Clearing" : "Ignoring");
1926 
1927         err = jbd2_journal_skip_recovery(journal);
1928         if (write) {
1929                 /* Lock to make assertions happy... */
1930                 mutex_lock(&journal->j_checkpoint_mutex);
1931                 jbd2_mark_journal_empty(journal);
1932                 mutex_unlock(&journal->j_checkpoint_mutex);
1933         }
1934 
1935  no_recovery:
1936         return err;
1937 }
1938 
1939 /*
1940  * Journal abort has very specific semantics, which we describe
1941  * for journal abort.
1942  *
1943  * Two internal functions, which provide abort to the jbd layer
1944  * itself are here.
1945  */
1946 
1947 /*
1948  * Quick version for internal journal use (doesn't lock the journal).
1949  * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
1950  * and don't attempt to make any other journal updates.
1951  */
1952 void __jbd2_journal_abort_hard(journal_t *journal)
1953 {
1954         transaction_t *transaction;
1955 
1956         if (journal->j_flags & JBD2_ABORT)
1957                 return;
1958 
1959         printk(KERN_ERR "Aborting journal on device %s.\n",
1960                journal->j_devname);
1961 
1962         write_lock(&journal->j_state_lock);
1963         journal->j_flags |= JBD2_ABORT;
1964         transaction = journal->j_running_transaction;
1965         if (transaction)
1966                 __jbd2_log_start_commit(journal, transaction->t_tid);
1967         write_unlock(&journal->j_state_lock);
1968 }
1969 
1970 /* Soft abort: record the abort error status in the journal superblock,
1971  * but don't do any other IO. */
1972 static void __journal_abort_soft (journal_t *journal, int errno)
1973 {
1974         if (journal->j_flags & JBD2_ABORT)
1975                 return;
1976 
1977         if (!journal->j_errno)
1978                 journal->j_errno = errno;
1979 
1980         __jbd2_journal_abort_hard(journal);
1981 
1982         if (errno)
1983                 jbd2_journal_update_sb_errno(journal);
1984 }
1985 
1986 /**
1987  * void jbd2_journal_abort () - Shutdown the journal immediately.
1988  * @journal: the journal to shutdown.
1989  * @errno:   an error number to record in the journal indicating
1990  *           the reason for the shutdown.
1991  *
1992  * Perform a complete, immediate shutdown of the ENTIRE
1993  * journal (not of a single transaction).  This operation cannot be
1994  * undone without closing and reopening the journal.
1995  *
1996  * The jbd2_journal_abort function is intended to support higher level error
1997  * recovery mechanisms such as the ext2/ext3 remount-readonly error
1998  * mode.
1999  *
2000  * Journal abort has very specific semantics.  Any existing dirty,
2001  * unjournaled buffers in the main filesystem will still be written to
2002  * disk by bdflush, but the journaling mechanism will be suspended
2003  * immediately and no further transaction commits will be honoured.
2004  *
2005  * Any dirty, journaled buffers will be written back to disk without
2006  * hitting the journal.  Atomicity cannot be guaranteed on an aborted
2007  * filesystem, but we _do_ attempt to leave as much data as possible
2008  * behind for fsck to use for cleanup.
2009  *
2010  * Any attempt to get a new transaction handle on a journal which is in
2011  * ABORT state will just result in an -EROFS error return.  A
2012  * jbd2_journal_stop on an existing handle will return -EIO if we have
2013  * entered abort state during the update.
2014  *
2015  * Recursive transactions are not disturbed by journal abort until the
2016  * final jbd2_journal_stop, which will receive the -EIO error.
2017  *
2018  * Finally, the jbd2_journal_abort call allows the caller to supply an errno
2019  * which will be recorded (if possible) in the journal superblock.  This
2020  * allows a client to record failure conditions in the middle of a
2021  * transaction without having to complete the transaction to record the
2022  * failure to disk.  ext3_error, for example, now uses this
2023  * functionality.
2024  *
2025  * Errors which originate from within the journaling layer will NOT
2026  * supply an errno; a null errno implies that absolutely no further
2027  * writes are done to the journal (unless there are any already in
2028  * progress).
2029  *
2030  */
2031 
2032 void jbd2_journal_abort(journal_t *journal, int errno)
2033 {
2034         __journal_abort_soft(journal, errno);
2035 }
2036 
2037 /**
2038  * int jbd2_journal_errno () - returns the journal's error state.
2039  * @journal: journal to examine.
2040  *
2041  * This is the errno number set with jbd2_journal_abort(), the last
2042  * time the journal was mounted - if the journal was stopped
2043  * without calling abort this will be 0.
2044  *
2045  * If the journal has been aborted on this mount time -EROFS will
2046  * be returned.
2047  */
2048 int jbd2_journal_errno(journal_t *journal)
2049 {
2050         int err;
2051 
2052         read_lock(&journal->j_state_lock);
2053         if (journal->j_flags & JBD2_ABORT)
2054                 err = -EROFS;
2055         else
2056                 err = journal->j_errno;
2057         read_unlock(&journal->j_state_lock);
2058         return err;
2059 }
2060 
2061 /**
2062  * int jbd2_journal_clear_err () - clears the journal's error state
2063  * @journal: journal to act on.
2064  *
2065  * An error must be cleared or acked to take a FS out of readonly
2066  * mode.
2067  */
2068 int jbd2_journal_clear_err(journal_t *journal)
2069 {
2070         int err = 0;
2071 
2072         write_lock(&journal->j_state_lock);
2073         if (journal->j_flags & JBD2_ABORT)
2074                 err = -EROFS;
2075         else
2076                 journal->j_errno = 0;
2077         write_unlock(&journal->j_state_lock);
2078         return err;
2079 }
2080 
2081 /**
2082  * void jbd2_journal_ack_err() - Ack journal err.
2083  * @journal: journal to act on.
2084  *
2085  * An error must be cleared or acked to take a FS out of readonly
2086  * mode.
2087  */
2088 void jbd2_journal_ack_err(journal_t *journal)
2089 {
2090         write_lock(&journal->j_state_lock);
2091         if (journal->j_errno)
2092                 journal->j_flags |= JBD2_ACK_ERR;
2093         write_unlock(&journal->j_state_lock);
2094 }
2095 
2096 int jbd2_journal_blocks_per_page(struct inode *inode)
2097 {
2098         return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
2099 }
2100 
2101 /*
2102  * helper functions to deal with 32 or 64bit block numbers.
2103  */
2104 size_t journal_tag_bytes(journal_t *journal)
2105 {
2106         journal_block_tag_t tag;
2107         size_t x = 0;
2108 
2109         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
2110                 x += sizeof(tag.t_checksum);
2111 
2112         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
2113                 return x + JBD2_TAG_SIZE64;
2114         else
2115                 return x + JBD2_TAG_SIZE32;
2116 }
2117 
2118 /*
2119  * JBD memory management
2120  *
2121  * These functions are used to allocate block-sized chunks of memory
2122  * used for making copies of buffer_head data.  Very often it will be
2123  * page-sized chunks of data, but sometimes it will be in
2124  * sub-page-size chunks.  (For example, 16k pages on Power systems
2125  * with a 4k block file system.)  For blocks smaller than a page, we
2126  * use a SLAB allocator.  There are slab caches for each block size,
2127  * which are allocated at mount time, if necessary, and we only free
2128  * (all of) the slab caches when/if the jbd2 module is unloaded.  For
2129  * this reason we don't need to a mutex to protect access to
2130  * jbd2_slab[] allocating or releasing memory; only in
2131  * jbd2_journal_create_slab().
2132  */
2133 #define JBD2_MAX_SLABS 8
2134 static struct kmem_cache *jbd2_slab[JBD2_MAX_SLABS];
2135 
2136 static const char *jbd2_slab_names[JBD2_MAX_SLABS] = {
2137         "jbd2_1k", "jbd2_2k", "jbd2_4k", "jbd2_8k",
2138         "jbd2_16k", "jbd2_32k", "jbd2_64k", "jbd2_128k"
2139 };
2140 
2141 
2142 static void jbd2_journal_destroy_slabs(void)
2143 {
2144         int i;
2145 
2146         for (i = 0; i < JBD2_MAX_SLABS; i++) {
2147                 if (jbd2_slab[i])
2148                         kmem_cache_destroy(jbd2_slab[i]);
2149                 jbd2_slab[i] = NULL;
2150         }
2151 }
2152 
2153 static int jbd2_journal_create_slab(size_t size)
2154 {
2155         static DEFINE_MUTEX(jbd2_slab_create_mutex);
2156         int i = order_base_2(size) - 10;
2157         size_t slab_size;
2158 
2159         if (size == PAGE_SIZE)
2160                 return 0;
2161 
2162         if (i >= JBD2_MAX_SLABS)
2163                 return -EINVAL;
2164 
2165         if (unlikely(i < 0))
2166                 i = 0;
2167         mutex_lock(&jbd2_slab_create_mutex);
2168         if (jbd2_slab[i]) {
2169                 mutex_unlock(&jbd2_slab_create_mutex);
2170                 return 0;       /* Already created */
2171         }
2172 
2173         slab_size = 1 << (i+10);
2174         jbd2_slab[i] = kmem_cache_create(jbd2_slab_names[i], slab_size,
2175                                          slab_size, 0, NULL);
2176         mutex_unlock(&jbd2_slab_create_mutex);
2177         if (!jbd2_slab[i]) {
2178                 printk(KERN_EMERG "JBD2: no memory for jbd2_slab cache\n");
2179                 return -ENOMEM;
2180         }
2181         return 0;
2182 }
2183 
2184 static struct kmem_cache *get_slab(size_t size)
2185 {
2186         int i = order_base_2(size) - 10;
2187 
2188         BUG_ON(i >= JBD2_MAX_SLABS);
2189         if (unlikely(i < 0))
2190                 i = 0;
2191         BUG_ON(jbd2_slab[i] == NULL);
2192         return jbd2_slab[i];
2193 }
2194 
2195 void *jbd2_alloc(size_t size, gfp_t flags)
2196 {
2197         void *ptr;
2198 
2199         BUG_ON(size & (size-1)); /* Must be a power of 2 */
2200 
2201         flags |= __GFP_REPEAT;
2202         if (size == PAGE_SIZE)
2203                 ptr = (void *)__get_free_pages(flags, 0);
2204         else if (size > PAGE_SIZE) {
2205                 int order = get_order(size);
2206 
2207                 if (order < 3)
2208                         ptr = (void *)__get_free_pages(flags, order);
2209                 else
2210                         ptr = vmalloc(size);
2211         } else
2212                 ptr = kmem_cache_alloc(get_slab(size), flags);
2213 
2214         /* Check alignment; SLUB has gotten this wrong in the past,
2215          * and this can lead to user data corruption! */
2216         BUG_ON(((unsigned long) ptr) & (size-1));
2217 
2218         return ptr;
2219 }
2220 
2221 void jbd2_free(void *ptr, size_t size)
2222 {
2223         if (size == PAGE_SIZE) {
2224                 free_pages((unsigned long)ptr, 0);
2225                 return;
2226         }
2227         if (size > PAGE_SIZE) {
2228                 int order = get_order(size);
2229 
2230                 if (order < 3)
2231                         free_pages((unsigned long)ptr, order);
2232                 else
2233                         vfree(ptr);
2234                 return;
2235         }
2236         kmem_cache_free(get_slab(size), ptr);
2237 };
2238 
2239 /*
2240  * Journal_head storage management
2241  */
2242 static struct kmem_cache *jbd2_journal_head_cache;
2243 #ifdef CONFIG_JBD2_DEBUG
2244 static atomic_t nr_journal_heads = ATOMIC_INIT(0);
2245 #endif
2246 
2247 static int jbd2_journal_init_journal_head_cache(void)
2248 {
2249         int retval;
2250 
2251         J_ASSERT(jbd2_journal_head_cache == NULL);
2252         jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
2253                                 sizeof(struct journal_head),
2254                                 0,              /* offset */
2255                                 SLAB_TEMPORARY, /* flags */
2256                                 NULL);          /* ctor */
2257         retval = 0;
2258         if (!jbd2_journal_head_cache) {
2259                 retval = -ENOMEM;
2260                 printk(KERN_EMERG "JBD2: no memory for journal_head cache\n");
2261         }
2262         return retval;
2263 }
2264 
2265 static void jbd2_journal_destroy_journal_head_cache(void)
2266 {
2267         if (jbd2_journal_head_cache) {
2268                 kmem_cache_destroy(jbd2_journal_head_cache);
2269                 jbd2_journal_head_cache = NULL;
2270         }
2271 }
2272 
2273 /*
2274  * journal_head splicing and dicing
2275  */
2276 static struct journal_head *journal_alloc_journal_head(void)
2277 {
2278         struct journal_head *ret;
2279 
2280 #ifdef CONFIG_JBD2_DEBUG
2281         atomic_inc(&nr_journal_heads);
2282 #endif
2283         ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
2284         if (!ret) {
2285                 jbd_debug(1, "out of memory for journal_head\n");
2286                 pr_notice_ratelimited("ENOMEM in %s, retrying.\n", __func__);
2287                 while (!ret) {
2288                         yield();
2289                         ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
2290                 }
2291         }
2292         return ret;
2293 }
2294 
2295 static void journal_free_journal_head(struct journal_head *jh)
2296 {
2297 #ifdef CONFIG_JBD2_DEBUG
2298         atomic_dec(&nr_journal_heads);
2299         memset(jh, JBD2_POISON_FREE, sizeof(*jh));
2300 #endif
2301         kmem_cache_free(jbd2_journal_head_cache, jh);
2302 }
2303 
2304 /*
2305  * A journal_head is attached to a buffer_head whenever JBD has an
2306  * interest in the buffer.
2307  *
2308  * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
2309  * is set.  This bit is tested in core kernel code where we need to take
2310  * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
2311  * there.
2312  *
2313  * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
2314  *
2315  * When a buffer has its BH_JBD bit set it is immune from being released by
2316  * core kernel code, mainly via ->b_count.
2317  *
2318  * A journal_head is detached from its buffer_head when the journal_head's
2319  * b_jcount reaches zero. Running transaction (b_transaction) and checkpoint
2320  * transaction (b_cp_transaction) hold their references to b_jcount.
2321  *
2322  * Various places in the kernel want to attach a journal_head to a buffer_head
2323  * _before_ attaching the journal_head to a transaction.  To protect the
2324  * journal_head in this situation, jbd2_journal_add_journal_head elevates the
2325  * journal_head's b_jcount refcount by one.  The caller must call
2326  * jbd2_journal_put_journal_head() to undo this.
2327  *
2328  * So the typical usage would be:
2329  *
2330  *      (Attach a journal_head if needed.  Increments b_jcount)
2331  *      struct journal_head *jh = jbd2_journal_add_journal_head(bh);
2332  *      ...
2333  *      (Get another reference for transaction)
2334  *      jbd2_journal_grab_journal_head(bh);
2335  *      jh->b_transaction = xxx;
2336  *      (Put original reference)
2337  *      jbd2_journal_put_journal_head(jh);
2338  */
2339 
2340 /*
2341  * Give a buffer_head a journal_head.
2342  *
2343  * May sleep.
2344  */
2345 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh)
2346 {
2347         struct journal_head *jh;
2348         struct journal_head *new_jh = NULL;
2349 
2350 repeat:
2351         if (!buffer_jbd(bh)) {
2352                 new_jh = journal_alloc_journal_head();
2353                 memset(new_jh, 0, sizeof(*new_jh));
2354         }
2355 
2356         jbd_lock_bh_journal_head(bh);
2357         if (buffer_jbd(bh)) {
2358                 jh = bh2jh(bh);
2359         } else {
2360                 J_ASSERT_BH(bh,
2361                         (atomic_read(&bh->b_count) > 0) ||
2362                         (bh->b_page && bh->b_page->mapping));
2363 
2364                 if (!new_jh) {
2365                         jbd_unlock_bh_journal_head(bh);
2366                         goto repeat;
2367                 }
2368 
2369                 jh = new_jh;
2370                 new_jh = NULL;          /* We consumed it */
2371                 set_buffer_jbd(bh);
2372                 bh->b_private = jh;
2373                 jh->b_bh = bh;
2374                 get_bh(bh);
2375                 BUFFER_TRACE(bh, "added journal_head");
2376         }
2377         jh->b_jcount++;
2378         jbd_unlock_bh_journal_head(bh);
2379         if (new_jh)
2380                 journal_free_journal_head(new_jh);
2381         return bh->b_private;
2382 }
2383 
2384 /*
2385  * Grab a ref against this buffer_head's journal_head.  If it ended up not
2386  * having a journal_head, return NULL
2387  */
2388 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh)
2389 {
2390         struct journal_head *jh = NULL;
2391 
2392         jbd_lock_bh_journal_head(bh);
2393         if (buffer_jbd(bh)) {
2394                 jh = bh2jh(bh);
2395                 jh->b_jcount++;
2396         }
2397         jbd_unlock_bh_journal_head(bh);
2398         return jh;
2399 }
2400 
2401 static void __journal_remove_journal_head(struct buffer_head *bh)
2402 {
2403         struct journal_head *jh = bh2jh(bh);
2404 
2405         J_ASSERT_JH(jh, jh->b_jcount >= 0);
2406         J_ASSERT_JH(jh, jh->b_transaction == NULL);
2407         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
2408         J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
2409         J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
2410         J_ASSERT_BH(bh, buffer_jbd(bh));
2411         J_ASSERT_BH(bh, jh2bh(jh) == bh);
2412         BUFFER_TRACE(bh, "remove journal_head");
2413         if (jh->b_frozen_data) {
2414                 printk(KERN_WARNING "%s: freeing b_frozen_data\n", __func__);
2415                 jbd2_free(jh->b_frozen_data, bh->b_size);
2416         }
2417         if (jh->b_committed_data) {
2418                 printk(KERN_WARNING "%s: freeing b_committed_data\n", __func__);
2419                 jbd2_free(jh->b_committed_data, bh->b_size);
2420         }
2421         bh->b_private = NULL;
2422         jh->b_bh = NULL;        /* debug, really */
2423         clear_buffer_jbd(bh);
2424         journal_free_journal_head(jh);
2425 }
2426 
2427 /*
2428  * Drop a reference on the passed journal_head.  If it fell to zero then
2429  * release the journal_head from the buffer_head.
2430  */
2431 void jbd2_journal_put_journal_head(struct journal_head *jh)
2432 {
2433         struct buffer_head *bh = jh2bh(jh);
2434 
2435         jbd_lock_bh_journal_head(bh);
2436         J_ASSERT_JH(jh, jh->b_jcount > 0);
2437         --jh->b_jcount;
2438         if (!jh->b_jcount) {
2439                 __journal_remove_journal_head(bh);
2440                 jbd_unlock_bh_journal_head(bh);
2441                 __brelse(bh);
2442         } else
2443                 jbd_unlock_bh_journal_head(bh);
2444 }
2445 
2446 /*
2447  * Initialize jbd inode head
2448  */
2449 void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode)
2450 {
2451         jinode->i_transaction = NULL;
2452         jinode->i_next_transaction = NULL;
2453         jinode->i_vfs_inode = inode;
2454         jinode->i_flags = 0;
2455         INIT_LIST_HEAD(&jinode->i_list);
2456 }
2457 
2458 /*
2459  * Function to be called before we start removing inode from memory (i.e.,
2460  * clear_inode() is a fine place to be called from). It removes inode from
2461  * transaction's lists.
2462  */
2463 void jbd2_journal_release_jbd_inode(journal_t *journal,
2464                                     struct jbd2_inode *jinode)
2465 {
2466         if (!journal)
2467                 return;
2468 restart:
2469         spin_lock(&journal->j_list_lock);
2470         /* Is commit writing out inode - we have to wait */
2471         if (test_bit(__JI_COMMIT_RUNNING, &jinode->i_flags)) {
2472                 wait_queue_head_t *wq;
2473                 DEFINE_WAIT_BIT(wait, &jinode->i_flags, __JI_COMMIT_RUNNING);
2474                 wq = bit_waitqueue(&jinode->i_flags, __JI_COMMIT_RUNNING);
2475                 prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
2476                 spin_unlock(&journal->j_list_lock);
2477                 schedule();
2478                 finish_wait(wq, &wait.wait);
2479                 goto restart;
2480         }
2481 
2482         if (jinode->i_transaction) {
2483                 list_del(&jinode->i_list);
2484                 jinode->i_transaction = NULL;
2485         }
2486         spin_unlock(&journal->j_list_lock);
2487 }
2488 
2489 /*
2490  * debugfs tunables
2491  */
2492 #ifdef CONFIG_JBD2_DEBUG
2493 u8 jbd2_journal_enable_debug __read_mostly;
2494 EXPORT_SYMBOL(jbd2_journal_enable_debug);
2495 
2496 #define JBD2_DEBUG_NAME "jbd2-debug"
2497 
2498 static struct dentry *jbd2_debugfs_dir;
2499 static struct dentry *jbd2_debug;
2500 
2501 static void __init jbd2_create_debugfs_entry(void)
2502 {
2503         jbd2_debugfs_dir = debugfs_create_dir("jbd2", NULL);
2504         if (jbd2_debugfs_dir)
2505                 jbd2_debug = debugfs_create_u8(JBD2_DEBUG_NAME,
2506                                                S_IRUGO | S_IWUSR,
2507                                                jbd2_debugfs_dir,
2508                                                &jbd2_journal_enable_debug);
2509 }
2510 
2511 static void __exit jbd2_remove_debugfs_entry(void)
2512 {
2513         debugfs_remove(jbd2_debug);
2514         debugfs_remove(jbd2_debugfs_dir);
2515 }
2516 
2517 #else
2518 
2519 static void __init jbd2_create_debugfs_entry(void)
2520 {
2521 }
2522 
2523 static void __exit jbd2_remove_debugfs_entry(void)
2524 {
2525 }
2526 
2527 #endif
2528 
2529 #ifdef CONFIG_PROC_FS
2530 
2531 #define JBD2_STATS_PROC_NAME "fs/jbd2"
2532 
2533 static void __init jbd2_create_jbd_stats_proc_entry(void)
2534 {
2535         proc_jbd2_stats = proc_mkdir(JBD2_STATS_PROC_NAME, NULL);
2536 }
2537 
2538 static void __exit jbd2_remove_jbd_stats_proc_entry(void)
2539 {
2540         if (proc_jbd2_stats)
2541                 remove_proc_entry(JBD2_STATS_PROC_NAME, NULL);
2542 }
2543 
2544 #else
2545 
2546 #define jbd2_create_jbd_stats_proc_entry() do {} while (0)
2547 #define jbd2_remove_jbd_stats_proc_entry() do {} while (0)
2548 
2549 #endif
2550 
2551 struct kmem_cache *jbd2_handle_cache, *jbd2_inode_cache;
2552 
2553 static int __init jbd2_journal_init_handle_cache(void)
2554 {
2555         jbd2_handle_cache = KMEM_CACHE(jbd2_journal_handle, SLAB_TEMPORARY);
2556         if (jbd2_handle_cache == NULL) {
2557                 printk(KERN_EMERG "JBD2: failed to create handle cache\n");
2558                 return -ENOMEM;
2559         }
2560         jbd2_inode_cache = KMEM_CACHE(jbd2_inode, 0);
2561         if (jbd2_inode_cache == NULL) {
2562                 printk(KERN_EMERG "JBD2: failed to create inode cache\n");
2563                 kmem_cache_destroy(jbd2_handle_cache);
2564                 return -ENOMEM;
2565         }
2566         return 0;
2567 }
2568 
2569 static void jbd2_journal_destroy_handle_cache(void)
2570 {
2571         if (jbd2_handle_cache)
2572                 kmem_cache_destroy(jbd2_handle_cache);
2573         if (jbd2_inode_cache)
2574                 kmem_cache_destroy(jbd2_inode_cache);
2575 
2576 }
2577 
2578 /*
2579  * Module startup and shutdown
2580  */
2581 
2582 static int __init journal_init_caches(void)
2583 {
2584         int ret;
2585 
2586         ret = jbd2_journal_init_revoke_caches();
2587         if (ret == 0)
2588                 ret = jbd2_journal_init_journal_head_cache();
2589         if (ret == 0)
2590                 ret = jbd2_journal_init_handle_cache();
2591         if (ret == 0)
2592                 ret = jbd2_journal_init_transaction_cache();
2593         return ret;
2594 }
2595 
2596 static void jbd2_journal_destroy_caches(void)
2597 {
2598         jbd2_journal_destroy_revoke_caches();
2599         jbd2_journal_destroy_journal_head_cache();
2600         jbd2_journal_destroy_handle_cache();
2601         jbd2_journal_destroy_transaction_cache();
2602         jbd2_journal_destroy_slabs();
2603 }
2604 
2605 static int __init journal_init(void)
2606 {
2607         int ret;
2608 
2609         BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
2610 
2611         ret = journal_init_caches();
2612         if (ret == 0) {
2613                 jbd2_create_debugfs_entry();
2614                 jbd2_create_jbd_stats_proc_entry();
2615         } else {
2616                 jbd2_journal_destroy_caches();
2617         }
2618         return ret;
2619 }
2620 
2621 static void __exit journal_exit(void)
2622 {
2623 #ifdef CONFIG_JBD2_DEBUG
2624         int n = atomic_read(&nr_journal_heads);
2625         if (n)
2626                 printk(KERN_EMERG "JBD2: leaked %d journal_heads!\n", n);
2627 #endif
2628         jbd2_remove_debugfs_entry();
2629         jbd2_remove_jbd_stats_proc_entry();
2630         jbd2_journal_destroy_caches();
2631 }
2632 
2633 MODULE_LICENSE("GPL");
2634 module_init(journal_init);
2635 module_exit(journal_exit);
2636 
2637 

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