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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/seq_file.h>
 39 #include <linux/math64.h>
 40 #include <linux/hash.h>
 41 #include <linux/log2.h>
 42 #include <linux/vmalloc.h>
 43 #include <linux/backing-dev.h>
 44 #include <linux/bitops.h>
 45 #include <linux/ratelimit.h>
 46 
 47 #define CREATE_TRACE_POINTS
 48 #include <trace/events/jbd2.h>
 49 
 50 #include <linux/uaccess.h>
 51 #include <asm/page.h>
 52 
 53 #ifdef CONFIG_JBD2_DEBUG
 54 ushort jbd2_journal_enable_debug __read_mostly;
 55 EXPORT_SYMBOL(jbd2_journal_enable_debug);
 56 
 57 module_param_named(jbd2_debug, jbd2_journal_enable_debug, ushort, 0644);
 58 MODULE_PARM_DESC(jbd2_debug, "Debugging level for jbd2");
 59 #endif
 60 
 61 EXPORT_SYMBOL(jbd2_journal_extend);
 62 EXPORT_SYMBOL(jbd2_journal_stop);
 63 EXPORT_SYMBOL(jbd2_journal_lock_updates);
 64 EXPORT_SYMBOL(jbd2_journal_unlock_updates);
 65 EXPORT_SYMBOL(jbd2_journal_get_write_access);
 66 EXPORT_SYMBOL(jbd2_journal_get_create_access);
 67 EXPORT_SYMBOL(jbd2_journal_get_undo_access);
 68 EXPORT_SYMBOL(jbd2_journal_set_triggers);
 69 EXPORT_SYMBOL(jbd2_journal_dirty_metadata);
 70 EXPORT_SYMBOL(jbd2_journal_forget);
 71 #if 0
 72 EXPORT_SYMBOL(journal_sync_buffer);
 73 #endif
 74 EXPORT_SYMBOL(jbd2_journal_flush);
 75 EXPORT_SYMBOL(jbd2_journal_revoke);
 76 
 77 EXPORT_SYMBOL(jbd2_journal_init_dev);
 78 EXPORT_SYMBOL(jbd2_journal_init_inode);
 79 EXPORT_SYMBOL(jbd2_journal_check_used_features);
 80 EXPORT_SYMBOL(jbd2_journal_check_available_features);
 81 EXPORT_SYMBOL(jbd2_journal_set_features);
 82 EXPORT_SYMBOL(jbd2_journal_load);
 83 EXPORT_SYMBOL(jbd2_journal_destroy);
 84 EXPORT_SYMBOL(jbd2_journal_abort);
 85 EXPORT_SYMBOL(jbd2_journal_errno);
 86 EXPORT_SYMBOL(jbd2_journal_ack_err);
 87 EXPORT_SYMBOL(jbd2_journal_clear_err);
 88 EXPORT_SYMBOL(jbd2_log_wait_commit);
 89 EXPORT_SYMBOL(jbd2_log_start_commit);
 90 EXPORT_SYMBOL(jbd2_journal_start_commit);
 91 EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
 92 EXPORT_SYMBOL(jbd2_journal_wipe);
 93 EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
 94 EXPORT_SYMBOL(jbd2_journal_invalidatepage);
 95 EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
 96 EXPORT_SYMBOL(jbd2_journal_force_commit);
 97 EXPORT_SYMBOL(jbd2_journal_inode_add_write);
 98 EXPORT_SYMBOL(jbd2_journal_inode_add_wait);
 99 EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
100 EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
101 EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
102 EXPORT_SYMBOL(jbd2_inode_cache);
103 
104 static void __journal_abort_soft (journal_t *journal, int errno);
105 static int jbd2_journal_create_slab(size_t slab_size);
106 
107 #ifdef CONFIG_JBD2_DEBUG
108 void __jbd2_debug(int level, const char *file, const char *func,
109                   unsigned int line, const char *fmt, ...)
110 {
111         struct va_format vaf;
112         va_list args;
113 
114         if (level > jbd2_journal_enable_debug)
115                 return;
116         va_start(args, fmt);
117         vaf.fmt = fmt;
118         vaf.va = &args;
119         printk(KERN_DEBUG "%s: (%s, %u): %pV\n", file, func, line, &vaf);
120         va_end(args);
121 }
122 EXPORT_SYMBOL(__jbd2_debug);
123 #endif
124 
125 /* Checksumming functions */
126 static int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
127 {
128         if (!jbd2_journal_has_csum_v2or3_feature(j))
129                 return 1;
130 
131         return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
132 }
133 
134 static __be32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb)
135 {
136         __u32 csum;
137         __be32 old_csum;
138 
139         old_csum = sb->s_checksum;
140         sb->s_checksum = 0;
141         csum = jbd2_chksum(j, ~0, (char *)sb, sizeof(journal_superblock_t));
142         sb->s_checksum = old_csum;
143 
144         return cpu_to_be32(csum);
145 }
146 
147 static int jbd2_superblock_csum_verify(journal_t *j, journal_superblock_t *sb)
148 {
149         if (!jbd2_journal_has_csum_v2or3(j))
150                 return 1;
151 
152         return sb->s_checksum == jbd2_superblock_csum(j, sb);
153 }
154 
155 static void jbd2_superblock_csum_set(journal_t *j, journal_superblock_t *sb)
156 {
157         if (!jbd2_journal_has_csum_v2or3(j))
158                 return;
159 
160         sb->s_checksum = jbd2_superblock_csum(j, sb);
161 }
162 
163 /*
164  * Helper function used to manage commit timeouts
165  */
166 
167 static void commit_timeout(unsigned long __data)
168 {
169         struct task_struct * p = (struct task_struct *) __data;
170 
171         wake_up_process(p);
172 }
173 
174 /*
175  * kjournald2: The main thread function used to manage a logging device
176  * journal.
177  *
178  * This kernel thread is responsible for two things:
179  *
180  * 1) COMMIT:  Every so often we need to commit the current state of the
181  *    filesystem to disk.  The journal thread is responsible for writing
182  *    all of the metadata buffers to disk.
183  *
184  * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
185  *    of the data in that part of the log has been rewritten elsewhere on
186  *    the disk.  Flushing these old buffers to reclaim space in the log is
187  *    known as checkpointing, and this thread is responsible for that job.
188  */
189 
190 static int kjournald2(void *arg)
191 {
192         journal_t *journal = arg;
193         transaction_t *transaction;
194 
195         /*
196          * Set up an interval timer which can be used to trigger a commit wakeup
197          * after the commit interval expires
198          */
199         setup_timer(&journal->j_commit_timer, commit_timeout,
200                         (unsigned long)current);
201 
202         set_freezable();
203 
204         /* Record that the journal thread is running */
205         journal->j_task = current;
206         wake_up(&journal->j_wait_done_commit);
207 
208         /*
209          * And now, wait forever for commit wakeup events.
210          */
211         write_lock(&journal->j_state_lock);
212 
213 loop:
214         if (journal->j_flags & JBD2_UNMOUNT)
215                 goto end_loop;
216 
217         jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
218                 journal->j_commit_sequence, journal->j_commit_request);
219 
220         if (journal->j_commit_sequence != journal->j_commit_request) {
221                 jbd_debug(1, "OK, requests differ\n");
222                 write_unlock(&journal->j_state_lock);
223                 del_timer_sync(&journal->j_commit_timer);
224                 jbd2_journal_commit_transaction(journal);
225                 write_lock(&journal->j_state_lock);
226                 goto loop;
227         }
228 
229         wake_up(&journal->j_wait_done_commit);
230         if (freezing(current)) {
231                 /*
232                  * The simpler the better. Flushing journal isn't a
233                  * good idea, because that depends on threads that may
234                  * be already stopped.
235                  */
236                 jbd_debug(1, "Now suspending kjournald2\n");
237                 write_unlock(&journal->j_state_lock);
238                 try_to_freeze();
239                 write_lock(&journal->j_state_lock);
240         } else {
241                 /*
242                  * We assume on resume that commits are already there,
243                  * so we don't sleep
244                  */
245                 DEFINE_WAIT(wait);
246                 int should_sleep = 1;
247 
248                 prepare_to_wait(&journal->j_wait_commit, &wait,
249                                 TASK_INTERRUPTIBLE);
250                 if (journal->j_commit_sequence != journal->j_commit_request)
251                         should_sleep = 0;
252                 transaction = journal->j_running_transaction;
253                 if (transaction && time_after_eq(jiffies,
254                                                 transaction->t_expires))
255                         should_sleep = 0;
256                 if (journal->j_flags & JBD2_UNMOUNT)
257                         should_sleep = 0;
258                 if (should_sleep) {
259                         write_unlock(&journal->j_state_lock);
260                         schedule();
261                         write_lock(&journal->j_state_lock);
262                 }
263                 finish_wait(&journal->j_wait_commit, &wait);
264         }
265 
266         jbd_debug(1, "kjournald2 wakes\n");
267 
268         /*
269          * Were we woken up by a commit wakeup event?
270          */
271         transaction = journal->j_running_transaction;
272         if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
273                 journal->j_commit_request = transaction->t_tid;
274                 jbd_debug(1, "woke because of timeout\n");
275         }
276         goto loop;
277 
278 end_loop:
279         write_unlock(&journal->j_state_lock);
280         del_timer_sync(&journal->j_commit_timer);
281         journal->j_task = NULL;
282         wake_up(&journal->j_wait_done_commit);
283         jbd_debug(1, "Journal thread exiting.\n");
284         return 0;
285 }
286 
287 static int jbd2_journal_start_thread(journal_t *journal)
288 {
289         struct task_struct *t;
290 
291         t = kthread_run(kjournald2, journal, "jbd2/%s",
292                         journal->j_devname);
293         if (IS_ERR(t))
294                 return PTR_ERR(t);
295 
296         wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
297         return 0;
298 }
299 
300 static void journal_kill_thread(journal_t *journal)
301 {
302         write_lock(&journal->j_state_lock);
303         journal->j_flags |= JBD2_UNMOUNT;
304 
305         while (journal->j_task) {
306                 write_unlock(&journal->j_state_lock);
307                 wake_up(&journal->j_wait_commit);
308                 wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
309                 write_lock(&journal->j_state_lock);
310         }
311         write_unlock(&journal->j_state_lock);
312 }
313 
314 /*
315  * jbd2_journal_write_metadata_buffer: write a metadata buffer to the journal.
316  *
317  * Writes a metadata buffer to a given disk block.  The actual IO is not
318  * performed but a new buffer_head is constructed which labels the data
319  * to be written with the correct destination disk block.
320  *
321  * Any magic-number escaping which needs to be done will cause a
322  * copy-out here.  If the buffer happens to start with the
323  * JBD2_MAGIC_NUMBER, then we can't write it to the log directly: the
324  * magic number is only written to the log for descripter blocks.  In
325  * this case, we copy the data and replace the first word with 0, and we
326  * return a result code which indicates that this buffer needs to be
327  * marked as an escaped buffer in the corresponding log descriptor
328  * block.  The missing word can then be restored when the block is read
329  * during recovery.
330  *
331  * If the source buffer has already been modified by a new transaction
332  * since we took the last commit snapshot, we use the frozen copy of
333  * that data for IO. If we end up using the existing buffer_head's data
334  * for the write, then we have to make sure nobody modifies it while the
335  * IO is in progress. do_get_write_access() handles this.
336  *
337  * The function returns a pointer to the buffer_head to be used for IO.
338  * 
339  *
340  * Return value:
341  *  <0: Error
342  * >=0: Finished OK
343  *
344  * On success:
345  * Bit 0 set == escape performed on the data
346  * Bit 1 set == buffer copy-out performed (kfree the data after IO)
347  */
348 
349 int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
350                                   struct journal_head  *jh_in,
351                                   struct buffer_head **bh_out,
352                                   sector_t blocknr)
353 {
354         int need_copy_out = 0;
355         int done_copy_out = 0;
356         int do_escape = 0;
357         char *mapped_data;
358         struct buffer_head *new_bh;
359         struct page *new_page;
360         unsigned int new_offset;
361         struct buffer_head *bh_in = jh2bh(jh_in);
362         journal_t *journal = transaction->t_journal;
363 
364         /*
365          * The buffer really shouldn't be locked: only the current committing
366          * transaction is allowed to write it, so nobody else is allowed
367          * to do any IO.
368          *
369          * akpm: except if we're journalling data, and write() output is
370          * also part of a shared mapping, and another thread has
371          * decided to launch a writepage() against this buffer.
372          */
373         J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
374 
375         new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
376 
377         /* keep subsequent assertions sane */
378         atomic_set(&new_bh->b_count, 1);
379 
380         jbd_lock_bh_state(bh_in);
381 repeat:
382         /*
383          * If a new transaction has already done a buffer copy-out, then
384          * we use that version of the data for the commit.
385          */
386         if (jh_in->b_frozen_data) {
387                 done_copy_out = 1;
388                 new_page = virt_to_page(jh_in->b_frozen_data);
389                 new_offset = offset_in_page(jh_in->b_frozen_data);
390         } else {
391                 new_page = jh2bh(jh_in)->b_page;
392                 new_offset = offset_in_page(jh2bh(jh_in)->b_data);
393         }
394 
395         mapped_data = kmap_atomic(new_page);
396         /*
397          * Fire data frozen trigger if data already wasn't frozen.  Do this
398          * before checking for escaping, as the trigger may modify the magic
399          * offset.  If a copy-out happens afterwards, it will have the correct
400          * data in the buffer.
401          */
402         if (!done_copy_out)
403                 jbd2_buffer_frozen_trigger(jh_in, mapped_data + new_offset,
404                                            jh_in->b_triggers);
405 
406         /*
407          * Check for escaping
408          */
409         if (*((__be32 *)(mapped_data + new_offset)) ==
410                                 cpu_to_be32(JBD2_MAGIC_NUMBER)) {
411                 need_copy_out = 1;
412                 do_escape = 1;
413         }
414         kunmap_atomic(mapped_data);
415 
416         /*
417          * Do we need to do a data copy?
418          */
419         if (need_copy_out && !done_copy_out) {
420                 char *tmp;
421 
422                 jbd_unlock_bh_state(bh_in);
423                 tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS);
424                 if (!tmp) {
425                         brelse(new_bh);
426                         return -ENOMEM;
427                 }
428                 jbd_lock_bh_state(bh_in);
429                 if (jh_in->b_frozen_data) {
430                         jbd2_free(tmp, bh_in->b_size);
431                         goto repeat;
432                 }
433 
434                 jh_in->b_frozen_data = tmp;
435                 mapped_data = kmap_atomic(new_page);
436                 memcpy(tmp, mapped_data + new_offset, bh_in->b_size);
437                 kunmap_atomic(mapped_data);
438 
439                 new_page = virt_to_page(tmp);
440                 new_offset = offset_in_page(tmp);
441                 done_copy_out = 1;
442 
443                 /*
444                  * This isn't strictly necessary, as we're using frozen
445                  * data for the escaping, but it keeps consistency with
446                  * b_frozen_data usage.
447                  */
448                 jh_in->b_frozen_triggers = jh_in->b_triggers;
449         }
450 
451         /*
452          * Did we need to do an escaping?  Now we've done all the
453          * copying, we can finally do so.
454          */
455         if (do_escape) {
456                 mapped_data = kmap_atomic(new_page);
457                 *((unsigned int *)(mapped_data + new_offset)) = 0;
458                 kunmap_atomic(mapped_data);
459         }
460 
461         set_bh_page(new_bh, new_page, new_offset);
462         new_bh->b_size = bh_in->b_size;
463         new_bh->b_bdev = journal->j_dev;
464         new_bh->b_blocknr = blocknr;
465         new_bh->b_private = bh_in;
466         set_buffer_mapped(new_bh);
467         set_buffer_dirty(new_bh);
468 
469         *bh_out = new_bh;
470 
471         /*
472          * The to-be-written buffer needs to get moved to the io queue,
473          * and the original buffer whose contents we are shadowing or
474          * copying is moved to the transaction's shadow queue.
475          */
476         JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
477         spin_lock(&journal->j_list_lock);
478         __jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
479         spin_unlock(&journal->j_list_lock);
480         set_buffer_shadow(bh_in);
481         jbd_unlock_bh_state(bh_in);
482 
483         return do_escape | (done_copy_out << 1);
484 }
485 
486 /*
487  * Allocation code for the journal file.  Manage the space left in the
488  * journal, so that we can begin checkpointing when appropriate.
489  */
490 
491 /*
492  * Called with j_state_lock locked for writing.
493  * Returns true if a transaction commit was started.
494  */
495 int __jbd2_log_start_commit(journal_t *journal, tid_t target)
496 {
497         /* Return if the txn has already requested to be committed */
498         if (journal->j_commit_request == target)
499                 return 0;
500 
501         /*
502          * The only transaction we can possibly wait upon is the
503          * currently running transaction (if it exists).  Otherwise,
504          * the target tid must be an old one.
505          */
506         if (journal->j_running_transaction &&
507             journal->j_running_transaction->t_tid == target) {
508                 /*
509                  * We want a new commit: OK, mark the request and wakeup the
510                  * commit thread.  We do _not_ do the commit ourselves.
511                  */
512 
513                 journal->j_commit_request = target;
514                 jbd_debug(1, "JBD2: requesting commit %d/%d\n",
515                           journal->j_commit_request,
516                           journal->j_commit_sequence);
517                 journal->j_running_transaction->t_requested = jiffies;
518                 wake_up(&journal->j_wait_commit);
519                 return 1;
520         } else if (!tid_geq(journal->j_commit_request, target))
521                 /* This should never happen, but if it does, preserve
522                    the evidence before kjournald goes into a loop and
523                    increments j_commit_sequence beyond all recognition. */
524                 WARN_ONCE(1, "JBD2: bad log_start_commit: %u %u %u %u\n",
525                           journal->j_commit_request,
526                           journal->j_commit_sequence,
527                           target, journal->j_running_transaction ? 
528                           journal->j_running_transaction->t_tid : 0);
529         return 0;
530 }
531 
532 int jbd2_log_start_commit(journal_t *journal, tid_t tid)
533 {
534         int ret;
535 
536         write_lock(&journal->j_state_lock);
537         ret = __jbd2_log_start_commit(journal, tid);
538         write_unlock(&journal->j_state_lock);
539         return ret;
540 }
541 
542 /*
543  * Force and wait any uncommitted transactions.  We can only force the running
544  * transaction if we don't have an active handle, otherwise, we will deadlock.
545  * Returns: <0 in case of error,
546  *           0 if nothing to commit,
547  *           1 if transaction was successfully committed.
548  */
549 static int __jbd2_journal_force_commit(journal_t *journal)
550 {
551         transaction_t *transaction = NULL;
552         tid_t tid;
553         int need_to_start = 0, ret = 0;
554 
555         read_lock(&journal->j_state_lock);
556         if (journal->j_running_transaction && !current->journal_info) {
557                 transaction = journal->j_running_transaction;
558                 if (!tid_geq(journal->j_commit_request, transaction->t_tid))
559                         need_to_start = 1;
560         } else if (journal->j_committing_transaction)
561                 transaction = journal->j_committing_transaction;
562 
563         if (!transaction) {
564                 /* Nothing to commit */
565                 read_unlock(&journal->j_state_lock);
566                 return 0;
567         }
568         tid = transaction->t_tid;
569         read_unlock(&journal->j_state_lock);
570         if (need_to_start)
571                 jbd2_log_start_commit(journal, tid);
572         ret = jbd2_log_wait_commit(journal, tid);
573         if (!ret)
574                 ret = 1;
575 
576         return ret;
577 }
578 
579 /**
580  * Force and wait upon a commit if the calling process is not within
581  * transaction.  This is used for forcing out undo-protected data which contains
582  * bitmaps, when the fs is running out of space.
583  *
584  * @journal: journal to force
585  * Returns true if progress was made.
586  */
587 int jbd2_journal_force_commit_nested(journal_t *journal)
588 {
589         int ret;
590 
591         ret = __jbd2_journal_force_commit(journal);
592         return ret > 0;
593 }
594 
595 /**
596  * int journal_force_commit() - force any uncommitted transactions
597  * @journal: journal to force
598  *
599  * Caller want unconditional commit. We can only force the running transaction
600  * if we don't have an active handle, otherwise, we will deadlock.
601  */
602 int jbd2_journal_force_commit(journal_t *journal)
603 {
604         int ret;
605 
606         J_ASSERT(!current->journal_info);
607         ret = __jbd2_journal_force_commit(journal);
608         if (ret > 0)
609                 ret = 0;
610         return ret;
611 }
612 
613 /*
614  * Start a commit of the current running transaction (if any).  Returns true
615  * if a transaction is going to be committed (or is currently already
616  * committing), and fills its tid in at *ptid
617  */
618 int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
619 {
620         int ret = 0;
621 
622         write_lock(&journal->j_state_lock);
623         if (journal->j_running_transaction) {
624                 tid_t tid = journal->j_running_transaction->t_tid;
625 
626                 __jbd2_log_start_commit(journal, tid);
627                 /* There's a running transaction and we've just made sure
628                  * it's commit has been scheduled. */
629                 if (ptid)
630                         *ptid = tid;
631                 ret = 1;
632         } else if (journal->j_committing_transaction) {
633                 /*
634                  * If commit has been started, then we have to wait for
635                  * completion of that transaction.
636                  */
637                 if (ptid)
638                         *ptid = journal->j_committing_transaction->t_tid;
639                 ret = 1;
640         }
641         write_unlock(&journal->j_state_lock);
642         return ret;
643 }
644 
645 /*
646  * Return 1 if a given transaction has not yet sent barrier request
647  * connected with a transaction commit. If 0 is returned, transaction
648  * may or may not have sent the barrier. Used to avoid sending barrier
649  * twice in common cases.
650  */
651 int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid)
652 {
653         int ret = 0;
654         transaction_t *commit_trans;
655 
656         if (!(journal->j_flags & JBD2_BARRIER))
657                 return 0;
658         read_lock(&journal->j_state_lock);
659         /* Transaction already committed? */
660         if (tid_geq(journal->j_commit_sequence, tid))
661                 goto out;
662         commit_trans = journal->j_committing_transaction;
663         if (!commit_trans || commit_trans->t_tid != tid) {
664                 ret = 1;
665                 goto out;
666         }
667         /*
668          * Transaction is being committed and we already proceeded to
669          * submitting a flush to fs partition?
670          */
671         if (journal->j_fs_dev != journal->j_dev) {
672                 if (!commit_trans->t_need_data_flush ||
673                     commit_trans->t_state >= T_COMMIT_DFLUSH)
674                         goto out;
675         } else {
676                 if (commit_trans->t_state >= T_COMMIT_JFLUSH)
677                         goto out;
678         }
679         ret = 1;
680 out:
681         read_unlock(&journal->j_state_lock);
682         return ret;
683 }
684 EXPORT_SYMBOL(jbd2_trans_will_send_data_barrier);
685 
686 /*
687  * Wait for a specified commit to complete.
688  * The caller may not hold the journal lock.
689  */
690 int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
691 {
692         int err = 0;
693 
694         jbd2_might_wait_for_commit(journal);
695         read_lock(&journal->j_state_lock);
696 #ifdef CONFIG_JBD2_DEBUG
697         if (!tid_geq(journal->j_commit_request, tid)) {
698                 printk(KERN_ERR
699                        "%s: error: j_commit_request=%d, tid=%d\n",
700                        __func__, journal->j_commit_request, tid);
701         }
702 #endif
703         while (tid_gt(tid, journal->j_commit_sequence)) {
704                 jbd_debug(1, "JBD2: want %d, j_commit_sequence=%d\n",
705                                   tid, journal->j_commit_sequence);
706                 read_unlock(&journal->j_state_lock);
707                 wake_up(&journal->j_wait_commit);
708                 wait_event(journal->j_wait_done_commit,
709                                 !tid_gt(tid, journal->j_commit_sequence));
710                 read_lock(&journal->j_state_lock);
711         }
712         read_unlock(&journal->j_state_lock);
713 
714         if (unlikely(is_journal_aborted(journal)))
715                 err = -EIO;
716         return err;
717 }
718 
719 /*
720  * When this function returns the transaction corresponding to tid
721  * will be completed.  If the transaction has currently running, start
722  * committing that transaction before waiting for it to complete.  If
723  * the transaction id is stale, it is by definition already completed,
724  * so just return SUCCESS.
725  */
726 int jbd2_complete_transaction(journal_t *journal, tid_t tid)
727 {
728         int     need_to_wait = 1;
729 
730         read_lock(&journal->j_state_lock);
731         if (journal->j_running_transaction &&
732             journal->j_running_transaction->t_tid == tid) {
733                 if (journal->j_commit_request != tid) {
734                         /* transaction not yet started, so request it */
735                         read_unlock(&journal->j_state_lock);
736                         jbd2_log_start_commit(journal, tid);
737                         goto wait_commit;
738                 }
739         } else if (!(journal->j_committing_transaction &&
740                      journal->j_committing_transaction->t_tid == tid))
741                 need_to_wait = 0;
742         read_unlock(&journal->j_state_lock);
743         if (!need_to_wait)
744                 return 0;
745 wait_commit:
746         return jbd2_log_wait_commit(journal, tid);
747 }
748 EXPORT_SYMBOL(jbd2_complete_transaction);
749 
750 /*
751  * Log buffer allocation routines:
752  */
753 
754 int jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
755 {
756         unsigned long blocknr;
757 
758         write_lock(&journal->j_state_lock);
759         J_ASSERT(journal->j_free > 1);
760 
761         blocknr = journal->j_head;
762         journal->j_head++;
763         journal->j_free--;
764         if (journal->j_head == journal->j_last)
765                 journal->j_head = journal->j_first;
766         write_unlock(&journal->j_state_lock);
767         return jbd2_journal_bmap(journal, blocknr, retp);
768 }
769 
770 /*
771  * Conversion of logical to physical block numbers for the journal
772  *
773  * On external journals the journal blocks are identity-mapped, so
774  * this is a no-op.  If needed, we can use j_blk_offset - everything is
775  * ready.
776  */
777 int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
778                  unsigned long long *retp)
779 {
780         int err = 0;
781         unsigned long long ret;
782 
783         if (journal->j_inode) {
784                 ret = bmap(journal->j_inode, blocknr);
785                 if (ret)
786                         *retp = ret;
787                 else {
788                         printk(KERN_ALERT "%s: journal block not found "
789                                         "at offset %lu on %s\n",
790                                __func__, blocknr, journal->j_devname);
791                         err = -EIO;
792                         __journal_abort_soft(journal, err);
793                 }
794         } else {
795                 *retp = blocknr; /* +journal->j_blk_offset */
796         }
797         return err;
798 }
799 
800 /*
801  * We play buffer_head aliasing tricks to write data/metadata blocks to
802  * the journal without copying their contents, but for journal
803  * descriptor blocks we do need to generate bona fide buffers.
804  *
805  * After the caller of jbd2_journal_get_descriptor_buffer() has finished modifying
806  * the buffer's contents they really should run flush_dcache_page(bh->b_page).
807  * But we don't bother doing that, so there will be coherency problems with
808  * mmaps of blockdevs which hold live JBD-controlled filesystems.
809  */
810 struct buffer_head *
811 jbd2_journal_get_descriptor_buffer(transaction_t *transaction, int type)
812 {
813         journal_t *journal = transaction->t_journal;
814         struct buffer_head *bh;
815         unsigned long long blocknr;
816         journal_header_t *header;
817         int err;
818 
819         err = jbd2_journal_next_log_block(journal, &blocknr);
820 
821         if (err)
822                 return NULL;
823 
824         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
825         if (!bh)
826                 return NULL;
827         lock_buffer(bh);
828         memset(bh->b_data, 0, journal->j_blocksize);
829         header = (journal_header_t *)bh->b_data;
830         header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
831         header->h_blocktype = cpu_to_be32(type);
832         header->h_sequence = cpu_to_be32(transaction->t_tid);
833         set_buffer_uptodate(bh);
834         unlock_buffer(bh);
835         BUFFER_TRACE(bh, "return this buffer");
836         return bh;
837 }
838 
839 void jbd2_descriptor_block_csum_set(journal_t *j, struct buffer_head *bh)
840 {
841         struct jbd2_journal_block_tail *tail;
842         __u32 csum;
843 
844         if (!jbd2_journal_has_csum_v2or3(j))
845                 return;
846 
847         tail = (struct jbd2_journal_block_tail *)(bh->b_data + j->j_blocksize -
848                         sizeof(struct jbd2_journal_block_tail));
849         tail->t_checksum = 0;
850         csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
851         tail->t_checksum = cpu_to_be32(csum);
852 }
853 
854 /*
855  * Return tid of the oldest transaction in the journal and block in the journal
856  * where the transaction starts.
857  *
858  * If the journal is now empty, return which will be the next transaction ID
859  * we will write and where will that transaction start.
860  *
861  * The return value is 0 if journal tail cannot be pushed any further, 1 if
862  * it can.
863  */
864 int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
865                               unsigned long *block)
866 {
867         transaction_t *transaction;
868         int ret;
869 
870         read_lock(&journal->j_state_lock);
871         spin_lock(&journal->j_list_lock);
872         transaction = journal->j_checkpoint_transactions;
873         if (transaction) {
874                 *tid = transaction->t_tid;
875                 *block = transaction->t_log_start;
876         } else if ((transaction = journal->j_committing_transaction) != NULL) {
877                 *tid = transaction->t_tid;
878                 *block = transaction->t_log_start;
879         } else if ((transaction = journal->j_running_transaction) != NULL) {
880                 *tid = transaction->t_tid;
881                 *block = journal->j_head;
882         } else {
883                 *tid = journal->j_transaction_sequence;
884                 *block = journal->j_head;
885         }
886         ret = tid_gt(*tid, journal->j_tail_sequence);
887         spin_unlock(&journal->j_list_lock);
888         read_unlock(&journal->j_state_lock);
889 
890         return ret;
891 }
892 
893 /*
894  * Update information in journal structure and in on disk journal superblock
895  * about log tail. This function does not check whether information passed in
896  * really pushes log tail further. It's responsibility of the caller to make
897  * sure provided log tail information is valid (e.g. by holding
898  * j_checkpoint_mutex all the time between computing log tail and calling this
899  * function as is the case with jbd2_cleanup_journal_tail()).
900  *
901  * Requires j_checkpoint_mutex
902  */
903 int __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
904 {
905         unsigned long freed;
906         int ret;
907 
908         BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
909 
910         /*
911          * We cannot afford for write to remain in drive's caches since as
912          * soon as we update j_tail, next transaction can start reusing journal
913          * space and if we lose sb update during power failure we'd replay
914          * old transaction with possibly newly overwritten data.
915          */
916         ret = jbd2_journal_update_sb_log_tail(journal, tid, block, REQ_FUA);
917         if (ret)
918                 goto out;
919 
920         write_lock(&journal->j_state_lock);
921         freed = block - journal->j_tail;
922         if (block < journal->j_tail)
923                 freed += journal->j_last - journal->j_first;
924 
925         trace_jbd2_update_log_tail(journal, tid, block, freed);
926         jbd_debug(1,
927                   "Cleaning journal tail from %d to %d (offset %lu), "
928                   "freeing %lu\n",
929                   journal->j_tail_sequence, tid, block, freed);
930 
931         journal->j_free += freed;
932         journal->j_tail_sequence = tid;
933         journal->j_tail = block;
934         write_unlock(&journal->j_state_lock);
935 
936 out:
937         return ret;
938 }
939 
940 /*
941  * This is a variaon of __jbd2_update_log_tail which checks for validity of
942  * provided log tail and locks j_checkpoint_mutex. So it is safe against races
943  * with other threads updating log tail.
944  */
945 void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
946 {
947         mutex_lock(&journal->j_checkpoint_mutex);
948         if (tid_gt(tid, journal->j_tail_sequence))
949                 __jbd2_update_log_tail(journal, tid, block);
950         mutex_unlock(&journal->j_checkpoint_mutex);
951 }
952 
953 struct jbd2_stats_proc_session {
954         journal_t *journal;
955         struct transaction_stats_s *stats;
956         int start;
957         int max;
958 };
959 
960 static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos)
961 {
962         return *pos ? NULL : SEQ_START_TOKEN;
963 }
964 
965 static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
966 {
967         return NULL;
968 }
969 
970 static int jbd2_seq_info_show(struct seq_file *seq, void *v)
971 {
972         struct jbd2_stats_proc_session *s = seq->private;
973 
974         if (v != SEQ_START_TOKEN)
975                 return 0;
976         seq_printf(seq, "%lu transactions (%lu requested), "
977                    "each up to %u blocks\n",
978                    s->stats->ts_tid, s->stats->ts_requested,
979                    s->journal->j_max_transaction_buffers);
980         if (s->stats->ts_tid == 0)
981                 return 0;
982         seq_printf(seq, "average: \n  %ums waiting for transaction\n",
983             jiffies_to_msecs(s->stats->run.rs_wait / s->stats->ts_tid));
984         seq_printf(seq, "  %ums request delay\n",
985             (s->stats->ts_requested == 0) ? 0 :
986             jiffies_to_msecs(s->stats->run.rs_request_delay /
987                              s->stats->ts_requested));
988         seq_printf(seq, "  %ums running transaction\n",
989             jiffies_to_msecs(s->stats->run.rs_running / s->stats->ts_tid));
990         seq_printf(seq, "  %ums transaction was being locked\n",
991             jiffies_to_msecs(s->stats->run.rs_locked / s->stats->ts_tid));
992         seq_printf(seq, "  %ums flushing data (in ordered mode)\n",
993             jiffies_to_msecs(s->stats->run.rs_flushing / s->stats->ts_tid));
994         seq_printf(seq, "  %ums logging transaction\n",
995             jiffies_to_msecs(s->stats->run.rs_logging / s->stats->ts_tid));
996         seq_printf(seq, "  %lluus average transaction commit time\n",
997                    div_u64(s->journal->j_average_commit_time, 1000));
998         seq_printf(seq, "  %lu handles per transaction\n",
999             s->stats->run.rs_handle_count / s->stats->ts_tid);
1000         seq_printf(seq, "  %lu blocks per transaction\n",
1001             s->stats->run.rs_blocks / s->stats->ts_tid);
1002         seq_printf(seq, "  %lu logged blocks per transaction\n",
1003             s->stats->run.rs_blocks_logged / s->stats->ts_tid);
1004         return 0;
1005 }
1006 
1007 static void jbd2_seq_info_stop(struct seq_file *seq, void *v)
1008 {
1009 }
1010 
1011 static const struct seq_operations jbd2_seq_info_ops = {
1012         .start  = jbd2_seq_info_start,
1013         .next   = jbd2_seq_info_next,
1014         .stop   = jbd2_seq_info_stop,
1015         .show   = jbd2_seq_info_show,
1016 };
1017 
1018 static int jbd2_seq_info_open(struct inode *inode, struct file *file)
1019 {
1020         journal_t *journal = PDE_DATA(inode);
1021         struct jbd2_stats_proc_session *s;
1022         int rc, size;
1023 
1024         s = kmalloc(sizeof(*s), GFP_KERNEL);
1025         if (s == NULL)
1026                 return -ENOMEM;
1027         size = sizeof(struct transaction_stats_s);
1028         s->stats = kmalloc(size, GFP_KERNEL);
1029         if (s->stats == NULL) {
1030                 kfree(s);
1031                 return -ENOMEM;
1032         }
1033         spin_lock(&journal->j_history_lock);
1034         memcpy(s->stats, &journal->j_stats, size);
1035         s->journal = journal;
1036         spin_unlock(&journal->j_history_lock);
1037 
1038         rc = seq_open(file, &jbd2_seq_info_ops);
1039         if (rc == 0) {
1040                 struct seq_file *m = file->private_data;
1041                 m->private = s;
1042         } else {
1043                 kfree(s->stats);
1044                 kfree(s);
1045         }
1046         return rc;
1047 
1048 }
1049 
1050 static int jbd2_seq_info_release(struct inode *inode, struct file *file)
1051 {
1052         struct seq_file *seq = file->private_data;
1053         struct jbd2_stats_proc_session *s = seq->private;
1054         kfree(s->stats);
1055         kfree(s);
1056         return seq_release(inode, file);
1057 }
1058 
1059 static const struct file_operations jbd2_seq_info_fops = {
1060         .owner          = THIS_MODULE,
1061         .open           = jbd2_seq_info_open,
1062         .read           = seq_read,
1063         .llseek         = seq_lseek,
1064         .release        = jbd2_seq_info_release,
1065 };
1066 
1067 static struct proc_dir_entry *proc_jbd2_stats;
1068 
1069 static void jbd2_stats_proc_init(journal_t *journal)
1070 {
1071         journal->j_proc_entry = proc_mkdir(journal->j_devname, proc_jbd2_stats);
1072         if (journal->j_proc_entry) {
1073                 proc_create_data("info", S_IRUGO, journal->j_proc_entry,
1074                                  &jbd2_seq_info_fops, journal);
1075         }
1076 }
1077 
1078 static void jbd2_stats_proc_exit(journal_t *journal)
1079 {
1080         remove_proc_entry("info", journal->j_proc_entry);
1081         remove_proc_entry(journal->j_devname, proc_jbd2_stats);
1082 }
1083 
1084 /*
1085  * Management for journal control blocks: functions to create and
1086  * destroy journal_t structures, and to initialise and read existing
1087  * journal blocks from disk.  */
1088 
1089 /* First: create and setup a journal_t object in memory.  We initialise
1090  * very few fields yet: that has to wait until we have created the
1091  * journal structures from from scratch, or loaded them from disk. */
1092 
1093 static journal_t *journal_init_common(struct block_device *bdev,
1094                         struct block_device *fs_dev,
1095                         unsigned long long start, int len, int blocksize)
1096 {
1097         static struct lock_class_key jbd2_trans_commit_key;
1098         journal_t *journal;
1099         int err;
1100         struct buffer_head *bh;
1101         int n;
1102 
1103         journal = kzalloc(sizeof(*journal), GFP_KERNEL);
1104         if (!journal)
1105                 return NULL;
1106 
1107         init_waitqueue_head(&journal->j_wait_transaction_locked);
1108         init_waitqueue_head(&journal->j_wait_done_commit);
1109         init_waitqueue_head(&journal->j_wait_commit);
1110         init_waitqueue_head(&journal->j_wait_updates);
1111         init_waitqueue_head(&journal->j_wait_reserved);
1112         mutex_init(&journal->j_barrier);
1113         mutex_init(&journal->j_checkpoint_mutex);
1114         spin_lock_init(&journal->j_revoke_lock);
1115         spin_lock_init(&journal->j_list_lock);
1116         rwlock_init(&journal->j_state_lock);
1117 
1118         journal->j_commit_interval = (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE);
1119         journal->j_min_batch_time = 0;
1120         journal->j_max_batch_time = 15000; /* 15ms */
1121         atomic_set(&journal->j_reserved_credits, 0);
1122 
1123         /* The journal is marked for error until we succeed with recovery! */
1124         journal->j_flags = JBD2_ABORT;
1125 
1126         /* Set up a default-sized revoke table for the new mount. */
1127         err = jbd2_journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
1128         if (err)
1129                 goto err_cleanup;
1130 
1131         spin_lock_init(&journal->j_history_lock);
1132 
1133         lockdep_init_map(&journal->j_trans_commit_map, "jbd2_handle",
1134                          &jbd2_trans_commit_key, 0);
1135 
1136         /* journal descriptor can store up to n blocks -bzzz */
1137         journal->j_blocksize = blocksize;
1138         journal->j_dev = bdev;
1139         journal->j_fs_dev = fs_dev;
1140         journal->j_blk_offset = start;
1141         journal->j_maxlen = len;
1142         n = journal->j_blocksize / sizeof(journal_block_tag_t);
1143         journal->j_wbufsize = n;
1144         journal->j_wbuf = kmalloc_array(n, sizeof(struct buffer_head *),
1145                                         GFP_KERNEL);
1146         if (!journal->j_wbuf)
1147                 goto err_cleanup;
1148 
1149         bh = getblk_unmovable(journal->j_dev, start, journal->j_blocksize);
1150         if (!bh) {
1151                 pr_err("%s: Cannot get buffer for journal superblock\n",
1152                         __func__);
1153                 goto err_cleanup;
1154         }
1155         journal->j_sb_buffer = bh;
1156         journal->j_superblock = (journal_superblock_t *)bh->b_data;
1157 
1158         return journal;
1159 
1160 err_cleanup:
1161         kfree(journal->j_wbuf);
1162         jbd2_journal_destroy_revoke(journal);
1163         kfree(journal);
1164         return NULL;
1165 }
1166 
1167 /* jbd2_journal_init_dev and jbd2_journal_init_inode:
1168  *
1169  * Create a journal structure assigned some fixed set of disk blocks to
1170  * the journal.  We don't actually touch those disk blocks yet, but we
1171  * need to set up all of the mapping information to tell the journaling
1172  * system where the journal blocks are.
1173  *
1174  */
1175 
1176 /**
1177  *  journal_t * jbd2_journal_init_dev() - creates and initialises a journal structure
1178  *  @bdev: Block device on which to create the journal
1179  *  @fs_dev: Device which hold journalled filesystem for this journal.
1180  *  @start: Block nr Start of journal.
1181  *  @len:  Length of the journal in blocks.
1182  *  @blocksize: blocksize of journalling device
1183  *
1184  *  Returns: a newly created journal_t *
1185  *
1186  *  jbd2_journal_init_dev creates a journal which maps a fixed contiguous
1187  *  range of blocks on an arbitrary block device.
1188  *
1189  */
1190 journal_t *jbd2_journal_init_dev(struct block_device *bdev,
1191                         struct block_device *fs_dev,
1192                         unsigned long long start, int len, int blocksize)
1193 {
1194         journal_t *journal;
1195 
1196         journal = journal_init_common(bdev, fs_dev, start, len, blocksize);
1197         if (!journal)
1198                 return NULL;
1199 
1200         bdevname(journal->j_dev, journal->j_devname);
1201         strreplace(journal->j_devname, '/', '!');
1202         jbd2_stats_proc_init(journal);
1203 
1204         return journal;
1205 }
1206 
1207 /**
1208  *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
1209  *  @inode: An inode to create the journal in
1210  *
1211  * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
1212  * the journal.  The inode must exist already, must support bmap() and
1213  * must have all data blocks preallocated.
1214  */
1215 journal_t *jbd2_journal_init_inode(struct inode *inode)
1216 {
1217         journal_t *journal;
1218         char *p;
1219         unsigned long long blocknr;
1220 
1221         blocknr = bmap(inode, 0);
1222         if (!blocknr) {
1223                 pr_err("%s: Cannot locate journal superblock\n",
1224                         __func__);
1225                 return NULL;
1226         }
1227 
1228         jbd_debug(1, "JBD2: inode %s/%ld, size %lld, bits %d, blksize %ld\n",
1229                   inode->i_sb->s_id, inode->i_ino, (long long) inode->i_size,
1230                   inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
1231 
1232         journal = journal_init_common(inode->i_sb->s_bdev, inode->i_sb->s_bdev,
1233                         blocknr, inode->i_size >> inode->i_sb->s_blocksize_bits,
1234                         inode->i_sb->s_blocksize);
1235         if (!journal)
1236                 return NULL;
1237 
1238         journal->j_inode = inode;
1239         bdevname(journal->j_dev, journal->j_devname);
1240         p = strreplace(journal->j_devname, '/', '!');
1241         sprintf(p, "-%lu", journal->j_inode->i_ino);
1242         jbd2_stats_proc_init(journal);
1243 
1244         return journal;
1245 }
1246 
1247 /*
1248  * If the journal init or create aborts, we need to mark the journal
1249  * superblock as being NULL to prevent the journal destroy from writing
1250  * back a bogus superblock.
1251  */
1252 static void journal_fail_superblock (journal_t *journal)
1253 {
1254         struct buffer_head *bh = journal->j_sb_buffer;
1255         brelse(bh);
1256         journal->j_sb_buffer = NULL;
1257 }
1258 
1259 /*
1260  * Given a journal_t structure, initialise the various fields for
1261  * startup of a new journaling session.  We use this both when creating
1262  * a journal, and after recovering an old journal to reset it for
1263  * subsequent use.
1264  */
1265 
1266 static int journal_reset(journal_t *journal)
1267 {
1268         journal_superblock_t *sb = journal->j_superblock;
1269         unsigned long long first, last;
1270 
1271         first = be32_to_cpu(sb->s_first);
1272         last = be32_to_cpu(sb->s_maxlen);
1273         if (first + JBD2_MIN_JOURNAL_BLOCKS > last + 1) {
1274                 printk(KERN_ERR "JBD2: Journal too short (blocks %llu-%llu).\n",
1275                        first, last);
1276                 journal_fail_superblock(journal);
1277                 return -EINVAL;
1278         }
1279 
1280         journal->j_first = first;
1281         journal->j_last = last;
1282 
1283         journal->j_head = first;
1284         journal->j_tail = first;
1285         journal->j_free = last - first;
1286 
1287         journal->j_tail_sequence = journal->j_transaction_sequence;
1288         journal->j_commit_sequence = journal->j_transaction_sequence - 1;
1289         journal->j_commit_request = journal->j_commit_sequence;
1290 
1291         journal->j_max_transaction_buffers = journal->j_maxlen / 4;
1292 
1293         /*
1294          * As a special case, if the on-disk copy is already marked as needing
1295          * no recovery (s_start == 0), then we can safely defer the superblock
1296          * update until the next commit by setting JBD2_FLUSHED.  This avoids
1297          * attempting a write to a potential-readonly device.
1298          */
1299         if (sb->s_start == 0) {
1300                 jbd_debug(1, "JBD2: Skipping superblock update on recovered sb "
1301                         "(start %ld, seq %d, errno %d)\n",
1302                         journal->j_tail, journal->j_tail_sequence,
1303                         journal->j_errno);
1304                 journal->j_flags |= JBD2_FLUSHED;
1305         } else {
1306                 /* Lock here to make assertions happy... */
1307                 mutex_lock(&journal->j_checkpoint_mutex);
1308                 /*
1309                  * Update log tail information. We use REQ_FUA since new
1310                  * transaction will start reusing journal space and so we
1311                  * must make sure information about current log tail is on
1312                  * disk before that.
1313                  */
1314                 jbd2_journal_update_sb_log_tail(journal,
1315                                                 journal->j_tail_sequence,
1316                                                 journal->j_tail,
1317                                                 REQ_FUA);
1318                 mutex_unlock(&journal->j_checkpoint_mutex);
1319         }
1320         return jbd2_journal_start_thread(journal);
1321 }
1322 
1323 static int jbd2_write_superblock(journal_t *journal, int write_flags)
1324 {
1325         struct buffer_head *bh = journal->j_sb_buffer;
1326         journal_superblock_t *sb = journal->j_superblock;
1327         int ret;
1328 
1329         trace_jbd2_write_superblock(journal, write_flags);
1330         if (!(journal->j_flags & JBD2_BARRIER))
1331                 write_flags &= ~(REQ_FUA | REQ_PREFLUSH);
1332         lock_buffer(bh);
1333         if (buffer_write_io_error(bh)) {
1334                 /*
1335                  * Oh, dear.  A previous attempt to write the journal
1336                  * superblock failed.  This could happen because the
1337                  * USB device was yanked out.  Or it could happen to
1338                  * be a transient write error and maybe the block will
1339                  * be remapped.  Nothing we can do but to retry the
1340                  * write and hope for the best.
1341                  */
1342                 printk(KERN_ERR "JBD2: previous I/O error detected "
1343                        "for journal superblock update for %s.\n",
1344                        journal->j_devname);
1345                 clear_buffer_write_io_error(bh);
1346                 set_buffer_uptodate(bh);
1347         }
1348         jbd2_superblock_csum_set(journal, sb);
1349         get_bh(bh);
1350         bh->b_end_io = end_buffer_write_sync;
1351         ret = submit_bh(REQ_OP_WRITE, write_flags | REQ_SYNC, bh);
1352         wait_on_buffer(bh);
1353         if (buffer_write_io_error(bh)) {
1354                 clear_buffer_write_io_error(bh);
1355                 set_buffer_uptodate(bh);
1356                 ret = -EIO;
1357         }
1358         if (ret) {
1359                 printk(KERN_ERR "JBD2: Error %d detected when updating "
1360                        "journal superblock for %s.\n", ret,
1361                        journal->j_devname);
1362                 jbd2_journal_abort(journal, ret);
1363         }
1364 
1365         return ret;
1366 }
1367 
1368 /**
1369  * jbd2_journal_update_sb_log_tail() - Update log tail in journal sb on disk.
1370  * @journal: The journal to update.
1371  * @tail_tid: TID of the new transaction at the tail of the log
1372  * @tail_block: The first block of the transaction at the tail of the log
1373  * @write_op: With which operation should we write the journal sb
1374  *
1375  * Update a journal's superblock information about log tail and write it to
1376  * disk, waiting for the IO to complete.
1377  */
1378 int jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
1379                                      unsigned long tail_block, int write_op)
1380 {
1381         journal_superblock_t *sb = journal->j_superblock;
1382         int ret;
1383 
1384         BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1385         jbd_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n",
1386                   tail_block, tail_tid);
1387 
1388         sb->s_sequence = cpu_to_be32(tail_tid);
1389         sb->s_start    = cpu_to_be32(tail_block);
1390 
1391         ret = jbd2_write_superblock(journal, write_op);
1392         if (ret)
1393                 goto out;
1394 
1395         /* Log is no longer empty */
1396         write_lock(&journal->j_state_lock);
1397         WARN_ON(!sb->s_sequence);
1398         journal->j_flags &= ~JBD2_FLUSHED;
1399         write_unlock(&journal->j_state_lock);
1400 
1401 out:
1402         return ret;
1403 }
1404 
1405 /**
1406  * jbd2_mark_journal_empty() - Mark on disk journal as empty.
1407  * @journal: The journal to update.
1408  * @write_op: With which operation should we write the journal sb
1409  *
1410  * Update a journal's dynamic superblock fields to show that journal is empty.
1411  * Write updated superblock to disk waiting for IO to complete.
1412  */
1413 static void jbd2_mark_journal_empty(journal_t *journal, int write_op)
1414 {
1415         journal_superblock_t *sb = journal->j_superblock;
1416 
1417         BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1418         read_lock(&journal->j_state_lock);
1419         /* Is it already empty? */
1420         if (sb->s_start == 0) {
1421                 read_unlock(&journal->j_state_lock);
1422                 return;
1423         }
1424         jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n",
1425                   journal->j_tail_sequence);
1426 
1427         sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
1428         sb->s_start    = cpu_to_be32(0);
1429         read_unlock(&journal->j_state_lock);
1430 
1431         jbd2_write_superblock(journal, write_op);
1432 
1433         /* Log is no longer empty */
1434         write_lock(&journal->j_state_lock);
1435         journal->j_flags |= JBD2_FLUSHED;
1436         write_unlock(&journal->j_state_lock);
1437 }
1438 
1439 
1440 /**
1441  * jbd2_journal_update_sb_errno() - Update error in the journal.
1442  * @journal: The journal to update.
1443  *
1444  * Update a journal's errno.  Write updated superblock to disk waiting for IO
1445  * to complete.
1446  */
1447 void jbd2_journal_update_sb_errno(journal_t *journal)
1448 {
1449         journal_superblock_t *sb = journal->j_superblock;
1450 
1451         read_lock(&journal->j_state_lock);
1452         jbd_debug(1, "JBD2: updating superblock error (errno %d)\n",
1453                   journal->j_errno);
1454         sb->s_errno    = cpu_to_be32(journal->j_errno);
1455         read_unlock(&journal->j_state_lock);
1456 
1457         jbd2_write_superblock(journal, REQ_FUA);
1458 }
1459 EXPORT_SYMBOL(jbd2_journal_update_sb_errno);
1460 
1461 /*
1462  * Read the superblock for a given journal, performing initial
1463  * validation of the format.
1464  */
1465 static int journal_get_superblock(journal_t *journal)
1466 {
1467         struct buffer_head *bh;
1468         journal_superblock_t *sb;
1469         int err = -EIO;
1470 
1471         bh = journal->j_sb_buffer;
1472 
1473         J_ASSERT(bh != NULL);
1474         if (!buffer_uptodate(bh)) {
1475                 ll_rw_block(REQ_OP_READ, 0, 1, &bh);
1476                 wait_on_buffer(bh);
1477                 if (!buffer_uptodate(bh)) {
1478                         printk(KERN_ERR
1479                                 "JBD2: IO error reading journal superblock\n");
1480                         goto out;
1481                 }
1482         }
1483 
1484         if (buffer_verified(bh))
1485                 return 0;
1486 
1487         sb = journal->j_superblock;
1488 
1489         err = -EINVAL;
1490 
1491         if (sb->s_header.h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER) ||
1492             sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1493                 printk(KERN_WARNING "JBD2: no valid journal superblock found\n");
1494                 goto out;
1495         }
1496 
1497         switch(be32_to_cpu(sb->s_header.h_blocktype)) {
1498         case JBD2_SUPERBLOCK_V1:
1499                 journal->j_format_version = 1;
1500                 break;
1501         case JBD2_SUPERBLOCK_V2:
1502                 journal->j_format_version = 2;
1503                 break;
1504         default:
1505                 printk(KERN_WARNING "JBD2: unrecognised superblock format ID\n");
1506                 goto out;
1507         }
1508 
1509         if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
1510                 journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
1511         else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
1512                 printk(KERN_WARNING "JBD2: journal file too short\n");
1513                 goto out;
1514         }
1515 
1516         if (be32_to_cpu(sb->s_first) == 0 ||
1517             be32_to_cpu(sb->s_first) >= journal->j_maxlen) {
1518                 printk(KERN_WARNING
1519                         "JBD2: Invalid start block of journal: %u\n",
1520                         be32_to_cpu(sb->s_first));
1521                 goto out;
1522         }
1523 
1524         if (jbd2_has_feature_csum2(journal) &&
1525             jbd2_has_feature_csum3(journal)) {
1526                 /* Can't have checksum v2 and v3 at the same time! */
1527                 printk(KERN_ERR "JBD2: Can't enable checksumming v2 and v3 "
1528                        "at the same time!\n");
1529                 goto out;
1530         }
1531 
1532         if (jbd2_journal_has_csum_v2or3_feature(journal) &&
1533             jbd2_has_feature_checksum(journal)) {
1534                 /* Can't have checksum v1 and v2 on at the same time! */
1535                 printk(KERN_ERR "JBD2: Can't enable checksumming v1 and v2/3 "
1536                        "at the same time!\n");
1537                 goto out;
1538         }
1539 
1540         if (!jbd2_verify_csum_type(journal, sb)) {
1541                 printk(KERN_ERR "JBD2: Unknown checksum type\n");
1542                 goto out;
1543         }
1544 
1545         /* Load the checksum driver */
1546         if (jbd2_journal_has_csum_v2or3_feature(journal)) {
1547                 journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
1548                 if (IS_ERR(journal->j_chksum_driver)) {
1549                         printk(KERN_ERR "JBD2: Cannot load crc32c driver.\n");
1550                         err = PTR_ERR(journal->j_chksum_driver);
1551                         journal->j_chksum_driver = NULL;
1552                         goto out;
1553                 }
1554         }
1555 
1556         /* Check superblock checksum */
1557         if (!jbd2_superblock_csum_verify(journal, sb)) {
1558                 printk(KERN_ERR "JBD2: journal checksum error\n");
1559                 err = -EFSBADCRC;
1560                 goto out;
1561         }
1562 
1563         /* Precompute checksum seed for all metadata */
1564         if (jbd2_journal_has_csum_v2or3(journal))
1565                 journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid,
1566                                                    sizeof(sb->s_uuid));
1567 
1568         set_buffer_verified(bh);
1569 
1570         return 0;
1571 
1572 out:
1573         journal_fail_superblock(journal);
1574         return err;
1575 }
1576 
1577 /*
1578  * Load the on-disk journal superblock and read the key fields into the
1579  * journal_t.
1580  */
1581 
1582 static int load_superblock(journal_t *journal)
1583 {
1584         int err;
1585         journal_superblock_t *sb;
1586 
1587         err = journal_get_superblock(journal);
1588         if (err)
1589                 return err;
1590 
1591         sb = journal->j_superblock;
1592 
1593         journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1594         journal->j_tail = be32_to_cpu(sb->s_start);
1595         journal->j_first = be32_to_cpu(sb->s_first);
1596         journal->j_last = be32_to_cpu(sb->s_maxlen);
1597         journal->j_errno = be32_to_cpu(sb->s_errno);
1598 
1599         return 0;
1600 }
1601 
1602 
1603 /**
1604  * int jbd2_journal_load() - Read journal from disk.
1605  * @journal: Journal to act on.
1606  *
1607  * Given a journal_t structure which tells us which disk blocks contain
1608  * a journal, read the journal from disk to initialise the in-memory
1609  * structures.
1610  */
1611 int jbd2_journal_load(journal_t *journal)
1612 {
1613         int err;
1614         journal_superblock_t *sb;
1615 
1616         err = load_superblock(journal);
1617         if (err)
1618                 return err;
1619 
1620         sb = journal->j_superblock;
1621         /* If this is a V2 superblock, then we have to check the
1622          * features flags on it. */
1623 
1624         if (journal->j_format_version >= 2) {
1625                 if ((sb->s_feature_ro_compat &
1626                      ~cpu_to_be32(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
1627                     (sb->s_feature_incompat &
1628                      ~cpu_to_be32(JBD2_KNOWN_INCOMPAT_FEATURES))) {
1629                         printk(KERN_WARNING
1630                                 "JBD2: Unrecognised features on journal\n");
1631                         return -EINVAL;
1632                 }
1633         }
1634 
1635         /*
1636          * Create a slab for this blocksize
1637          */
1638         err = jbd2_journal_create_slab(be32_to_cpu(sb->s_blocksize));
1639         if (err)
1640                 return err;
1641 
1642         /* Let the recovery code check whether it needs to recover any
1643          * data from the journal. */
1644         if (jbd2_journal_recover(journal))
1645                 goto recovery_error;
1646 
1647         if (journal->j_failed_commit) {
1648                 printk(KERN_ERR "JBD2: journal transaction %u on %s "
1649                        "is corrupt.\n", journal->j_failed_commit,
1650                        journal->j_devname);
1651                 return -EFSCORRUPTED;
1652         }
1653 
1654         /* OK, we've finished with the dynamic journal bits:
1655          * reinitialise the dynamic contents of the superblock in memory
1656          * and reset them on disk. */
1657         if (journal_reset(journal))
1658                 goto recovery_error;
1659 
1660         journal->j_flags &= ~JBD2_ABORT;
1661         journal->j_flags |= JBD2_LOADED;
1662         return 0;
1663 
1664 recovery_error:
1665         printk(KERN_WARNING "JBD2: recovery failed\n");
1666         return -EIO;
1667 }
1668 
1669 /**
1670  * void jbd2_journal_destroy() - Release a journal_t structure.
1671  * @journal: Journal to act on.
1672  *
1673  * Release a journal_t structure once it is no longer in use by the
1674  * journaled object.
1675  * Return <0 if we couldn't clean up the journal.
1676  */
1677 int jbd2_journal_destroy(journal_t *journal)
1678 {
1679         int err = 0;
1680 
1681         /* Wait for the commit thread to wake up and die. */
1682         journal_kill_thread(journal);
1683 
1684         /* Force a final log commit */
1685         if (journal->j_running_transaction)
1686                 jbd2_journal_commit_transaction(journal);
1687 
1688         /* Force any old transactions to disk */
1689 
1690         /* Totally anal locking here... */
1691         spin_lock(&journal->j_list_lock);
1692         while (journal->j_checkpoint_transactions != NULL) {
1693                 spin_unlock(&journal->j_list_lock);
1694                 mutex_lock(&journal->j_checkpoint_mutex);
1695                 err = jbd2_log_do_checkpoint(journal);
1696                 mutex_unlock(&journal->j_checkpoint_mutex);
1697                 /*
1698                  * If checkpointing failed, just free the buffers to avoid
1699                  * looping forever
1700                  */
1701                 if (err) {
1702                         jbd2_journal_destroy_checkpoint(journal);
1703                         spin_lock(&journal->j_list_lock);
1704                         break;
1705                 }
1706                 spin_lock(&journal->j_list_lock);
1707         }
1708 
1709         J_ASSERT(journal->j_running_transaction == NULL);
1710         J_ASSERT(journal->j_committing_transaction == NULL);
1711         J_ASSERT(journal->j_checkpoint_transactions == NULL);
1712         spin_unlock(&journal->j_list_lock);
1713 
1714         if (journal->j_sb_buffer) {
1715                 if (!is_journal_aborted(journal)) {
1716                         mutex_lock(&journal->j_checkpoint_mutex);
1717 
1718                         write_lock(&journal->j_state_lock);
1719                         journal->j_tail_sequence =
1720                                 ++journal->j_transaction_sequence;
1721                         write_unlock(&journal->j_state_lock);
1722 
1723                         jbd2_mark_journal_empty(journal,
1724                                         REQ_PREFLUSH | REQ_FUA);
1725                         mutex_unlock(&journal->j_checkpoint_mutex);
1726                 } else
1727                         err = -EIO;
1728                 brelse(journal->j_sb_buffer);
1729         }
1730 
1731         if (journal->j_proc_entry)
1732                 jbd2_stats_proc_exit(journal);
1733         iput(journal->j_inode);
1734         if (journal->j_revoke)
1735                 jbd2_journal_destroy_revoke(journal);
1736         if (journal->j_chksum_driver)
1737                 crypto_free_shash(journal->j_chksum_driver);
1738         kfree(journal->j_wbuf);
1739         kfree(journal);
1740 
1741         return err;
1742 }
1743 
1744 
1745 /**
1746  *int jbd2_journal_check_used_features () - Check if features specified are used.
1747  * @journal: Journal to check.
1748  * @compat: bitmask of compatible features
1749  * @ro: bitmask of features that force read-only mount
1750  * @incompat: bitmask of incompatible features
1751  *
1752  * Check whether the journal uses all of a given set of
1753  * features.  Return true (non-zero) if it does.
1754  **/
1755 
1756 int jbd2_journal_check_used_features (journal_t *journal, unsigned long compat,
1757                                  unsigned long ro, unsigned long incompat)
1758 {
1759         journal_superblock_t *sb;
1760 
1761         if (!compat && !ro && !incompat)
1762                 return 1;
1763         /* Load journal superblock if it is not loaded yet. */
1764         if (journal->j_format_version == 0 &&
1765             journal_get_superblock(journal) != 0)
1766                 return 0;
1767         if (journal->j_format_version == 1)
1768                 return 0;
1769 
1770         sb = journal->j_superblock;
1771 
1772         if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1773             ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1774             ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1775                 return 1;
1776 
1777         return 0;
1778 }
1779 
1780 /**
1781  * int jbd2_journal_check_available_features() - Check feature set in journalling layer
1782  * @journal: Journal to check.
1783  * @compat: bitmask of compatible features
1784  * @ro: bitmask of features that force read-only mount
1785  * @incompat: bitmask of incompatible features
1786  *
1787  * Check whether the journaling code supports the use of
1788  * all of a given set of features on this journal.  Return true
1789  * (non-zero) if it can. */
1790 
1791 int jbd2_journal_check_available_features (journal_t *journal, unsigned long compat,
1792                                       unsigned long ro, unsigned long incompat)
1793 {
1794         if (!compat && !ro && !incompat)
1795                 return 1;
1796 
1797         /* We can support any known requested features iff the
1798          * superblock is in version 2.  Otherwise we fail to support any
1799          * extended sb features. */
1800 
1801         if (journal->j_format_version != 2)
1802                 return 0;
1803 
1804         if ((compat   & JBD2_KNOWN_COMPAT_FEATURES) == compat &&
1805             (ro       & JBD2_KNOWN_ROCOMPAT_FEATURES) == ro &&
1806             (incompat & JBD2_KNOWN_INCOMPAT_FEATURES) == incompat)
1807                 return 1;
1808 
1809         return 0;
1810 }
1811 
1812 /**
1813  * int jbd2_journal_set_features () - Mark a given journal feature in the superblock
1814  * @journal: Journal to act on.
1815  * @compat: bitmask of compatible features
1816  * @ro: bitmask of features that force read-only mount
1817  * @incompat: bitmask of incompatible features
1818  *
1819  * Mark a given journal feature as present on the
1820  * superblock.  Returns true if the requested features could be set.
1821  *
1822  */
1823 
1824 int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
1825                           unsigned long ro, unsigned long incompat)
1826 {
1827 #define INCOMPAT_FEATURE_ON(f) \
1828                 ((incompat & (f)) && !(sb->s_feature_incompat & cpu_to_be32(f)))
1829 #define COMPAT_FEATURE_ON(f) \
1830                 ((compat & (f)) && !(sb->s_feature_compat & cpu_to_be32(f)))
1831         journal_superblock_t *sb;
1832 
1833         if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
1834                 return 1;
1835 
1836         if (!jbd2_journal_check_available_features(journal, compat, ro, incompat))
1837                 return 0;
1838 
1839         /* If enabling v2 checksums, turn on v3 instead */
1840         if (incompat & JBD2_FEATURE_INCOMPAT_CSUM_V2) {
1841                 incompat &= ~JBD2_FEATURE_INCOMPAT_CSUM_V2;
1842                 incompat |= JBD2_FEATURE_INCOMPAT_CSUM_V3;
1843         }
1844 
1845         /* Asking for checksumming v3 and v1?  Only give them v3. */
1846         if (incompat & JBD2_FEATURE_INCOMPAT_CSUM_V3 &&
1847             compat & JBD2_FEATURE_COMPAT_CHECKSUM)
1848                 compat &= ~JBD2_FEATURE_COMPAT_CHECKSUM;
1849 
1850         jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1851                   compat, ro, incompat);
1852 
1853         sb = journal->j_superblock;
1854 
1855         /* If enabling v3 checksums, update superblock */
1856         if (INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V3)) {
1857                 sb->s_checksum_type = JBD2_CRC32C_CHKSUM;
1858                 sb->s_feature_compat &=
1859                         ~cpu_to_be32(JBD2_FEATURE_COMPAT_CHECKSUM);
1860 
1861                 /* Load the checksum driver */
1862                 if (journal->j_chksum_driver == NULL) {
1863                         journal->j_chksum_driver = crypto_alloc_shash("crc32c",
1864                                                                       0, 0);
1865                         if (IS_ERR(journal->j_chksum_driver)) {
1866                                 printk(KERN_ERR "JBD2: Cannot load crc32c "
1867                                        "driver.\n");
1868                                 journal->j_chksum_driver = NULL;
1869                                 return 0;
1870                         }
1871 
1872                         /* Precompute checksum seed for all metadata */
1873                         journal->j_csum_seed = jbd2_chksum(journal, ~0,
1874                                                            sb->s_uuid,
1875                                                            sizeof(sb->s_uuid));
1876                 }
1877         }
1878 
1879         /* If enabling v1 checksums, downgrade superblock */
1880         if (COMPAT_FEATURE_ON(JBD2_FEATURE_COMPAT_CHECKSUM))
1881                 sb->s_feature_incompat &=
1882                         ~cpu_to_be32(JBD2_FEATURE_INCOMPAT_CSUM_V2 |
1883                                      JBD2_FEATURE_INCOMPAT_CSUM_V3);
1884 
1885         sb->s_feature_compat    |= cpu_to_be32(compat);
1886         sb->s_feature_ro_compat |= cpu_to_be32(ro);
1887         sb->s_feature_incompat  |= cpu_to_be32(incompat);
1888 
1889         return 1;
1890 #undef COMPAT_FEATURE_ON
1891 #undef INCOMPAT_FEATURE_ON
1892 }
1893 
1894 /*
1895  * jbd2_journal_clear_features () - Clear a given journal feature in the
1896  *                                  superblock
1897  * @journal: Journal to act on.
1898  * @compat: bitmask of compatible features
1899  * @ro: bitmask of features that force read-only mount
1900  * @incompat: bitmask of incompatible features
1901  *
1902  * Clear a given journal feature as present on the
1903  * superblock.
1904  */
1905 void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
1906                                 unsigned long ro, unsigned long incompat)
1907 {
1908         journal_superblock_t *sb;
1909 
1910         jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
1911                   compat, ro, incompat);
1912 
1913         sb = journal->j_superblock;
1914 
1915         sb->s_feature_compat    &= ~cpu_to_be32(compat);
1916         sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
1917         sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
1918 }
1919 EXPORT_SYMBOL(jbd2_journal_clear_features);
1920 
1921 /**
1922  * int jbd2_journal_flush () - Flush journal
1923  * @journal: Journal to act on.
1924  *
1925  * Flush all data for a given journal to disk and empty the journal.
1926  * Filesystems can use this when remounting readonly to ensure that
1927  * recovery does not need to happen on remount.
1928  */
1929 
1930 int jbd2_journal_flush(journal_t *journal)
1931 {
1932         int err = 0;
1933         transaction_t *transaction = NULL;
1934 
1935         write_lock(&journal->j_state_lock);
1936 
1937         /* Force everything buffered to the log... */
1938         if (journal->j_running_transaction) {
1939                 transaction = journal->j_running_transaction;
1940                 __jbd2_log_start_commit(journal, transaction->t_tid);
1941         } else if (journal->j_committing_transaction)
1942                 transaction = journal->j_committing_transaction;
1943 
1944         /* Wait for the log commit to complete... */
1945         if (transaction) {
1946                 tid_t tid = transaction->t_tid;
1947 
1948                 write_unlock(&journal->j_state_lock);
1949                 jbd2_log_wait_commit(journal, tid);
1950         } else {
1951                 write_unlock(&journal->j_state_lock);
1952         }
1953 
1954         /* ...and flush everything in the log out to disk. */
1955         spin_lock(&journal->j_list_lock);
1956         while (!err && journal->j_checkpoint_transactions != NULL) {
1957                 spin_unlock(&journal->j_list_lock);
1958                 mutex_lock(&journal->j_checkpoint_mutex);
1959                 err = jbd2_log_do_checkpoint(journal);
1960                 mutex_unlock(&journal->j_checkpoint_mutex);
1961                 spin_lock(&journal->j_list_lock);
1962         }
1963         spin_unlock(&journal->j_list_lock);
1964 
1965         if (is_journal_aborted(journal))
1966                 return -EIO;
1967 
1968         mutex_lock(&journal->j_checkpoint_mutex);
1969         if (!err) {
1970                 err = jbd2_cleanup_journal_tail(journal);
1971                 if (err < 0) {
1972                         mutex_unlock(&journal->j_checkpoint_mutex);
1973                         goto out;
1974                 }
1975                 err = 0;
1976         }
1977 
1978         /* Finally, mark the journal as really needing no recovery.
1979          * This sets s_start==0 in the underlying superblock, which is
1980          * the magic code for a fully-recovered superblock.  Any future
1981          * commits of data to the journal will restore the current
1982          * s_start value. */
1983         jbd2_mark_journal_empty(journal, REQ_FUA);
1984         mutex_unlock(&journal->j_checkpoint_mutex);
1985         write_lock(&journal->j_state_lock);
1986         J_ASSERT(!journal->j_running_transaction);
1987         J_ASSERT(!journal->j_committing_transaction);
1988         J_ASSERT(!journal->j_checkpoint_transactions);
1989         J_ASSERT(journal->j_head == journal->j_tail);
1990         J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1991         write_unlock(&journal->j_state_lock);
1992 out:
1993         return err;
1994 }
1995 
1996 /**
1997  * int jbd2_journal_wipe() - Wipe journal contents
1998  * @journal: Journal to act on.
1999  * @write: flag (see below)
2000  *
2001  * Wipe out all of the contents of a journal, safely.  This will produce
2002  * a warning if the journal contains any valid recovery information.
2003  * Must be called between journal_init_*() and jbd2_journal_load().
2004  *
2005  * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
2006  * we merely suppress recovery.
2007  */
2008 
2009 int jbd2_journal_wipe(journal_t *journal, int write)
2010 {
2011         int err = 0;
2012 
2013         J_ASSERT (!(journal->j_flags & JBD2_LOADED));
2014 
2015         err = load_superblock(journal);
2016         if (err)
2017                 return err;
2018 
2019         if (!journal->j_tail)
2020                 goto no_recovery;
2021 
2022         printk(KERN_WARNING "JBD2: %s recovery information on journal\n",
2023                 write ? "Clearing" : "Ignoring");
2024 
2025         err = jbd2_journal_skip_recovery(journal);
2026         if (write) {
2027                 /* Lock to make assertions happy... */
2028                 mutex_lock(&journal->j_checkpoint_mutex);
2029                 jbd2_mark_journal_empty(journal, REQ_FUA);
2030                 mutex_unlock(&journal->j_checkpoint_mutex);
2031         }
2032 
2033  no_recovery:
2034         return err;
2035 }
2036 
2037 /*
2038  * Journal abort has very specific semantics, which we describe
2039  * for journal abort.
2040  *
2041  * Two internal functions, which provide abort to the jbd layer
2042  * itself are here.
2043  */
2044 
2045 /*
2046  * Quick version for internal journal use (doesn't lock the journal).
2047  * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
2048  * and don't attempt to make any other journal updates.
2049  */
2050 void __jbd2_journal_abort_hard(journal_t *journal)
2051 {
2052         transaction_t *transaction;
2053 
2054         if (journal->j_flags & JBD2_ABORT)
2055                 return;
2056 
2057         printk(KERN_ERR "Aborting journal on device %s.\n",
2058                journal->j_devname);
2059 
2060         write_lock(&journal->j_state_lock);
2061         journal->j_flags |= JBD2_ABORT;
2062         transaction = journal->j_running_transaction;
2063         if (transaction)
2064                 __jbd2_log_start_commit(journal, transaction->t_tid);
2065         write_unlock(&journal->j_state_lock);
2066 }
2067 
2068 /* Soft abort: record the abort error status in the journal superblock,
2069  * but don't do any other IO. */
2070 static void __journal_abort_soft (journal_t *journal, int errno)
2071 {
2072         if (journal->j_flags & JBD2_ABORT)
2073                 return;
2074 
2075         if (!journal->j_errno)
2076                 journal->j_errno = errno;
2077 
2078         __jbd2_journal_abort_hard(journal);
2079 
2080         if (errno) {
2081                 jbd2_journal_update_sb_errno(journal);
2082                 write_lock(&journal->j_state_lock);
2083                 journal->j_flags |= JBD2_REC_ERR;
2084                 write_unlock(&journal->j_state_lock);
2085         }
2086 }
2087 
2088 /**
2089  * void jbd2_journal_abort () - Shutdown the journal immediately.
2090  * @journal: the journal to shutdown.
2091  * @errno:   an error number to record in the journal indicating
2092  *           the reason for the shutdown.
2093  *
2094  * Perform a complete, immediate shutdown of the ENTIRE
2095  * journal (not of a single transaction).  This operation cannot be
2096  * undone without closing and reopening the journal.
2097  *
2098  * The jbd2_journal_abort function is intended to support higher level error
2099  * recovery mechanisms such as the ext2/ext3 remount-readonly error
2100  * mode.
2101  *
2102  * Journal abort has very specific semantics.  Any existing dirty,
2103  * unjournaled buffers in the main filesystem will still be written to
2104  * disk by bdflush, but the journaling mechanism will be suspended
2105  * immediately and no further transaction commits will be honoured.
2106  *
2107  * Any dirty, journaled buffers will be written back to disk without
2108  * hitting the journal.  Atomicity cannot be guaranteed on an aborted
2109  * filesystem, but we _do_ attempt to leave as much data as possible
2110  * behind for fsck to use for cleanup.
2111  *
2112  * Any attempt to get a new transaction handle on a journal which is in
2113  * ABORT state will just result in an -EROFS error return.  A
2114  * jbd2_journal_stop on an existing handle will return -EIO if we have
2115  * entered abort state during the update.
2116  *
2117  * Recursive transactions are not disturbed by journal abort until the
2118  * final jbd2_journal_stop, which will receive the -EIO error.
2119  *
2120  * Finally, the jbd2_journal_abort call allows the caller to supply an errno
2121  * which will be recorded (if possible) in the journal superblock.  This
2122  * allows a client to record failure conditions in the middle of a
2123  * transaction without having to complete the transaction to record the
2124  * failure to disk.  ext3_error, for example, now uses this
2125  * functionality.
2126  *
2127  * Errors which originate from within the journaling layer will NOT
2128  * supply an errno; a null errno implies that absolutely no further
2129  * writes are done to the journal (unless there are any already in
2130  * progress).
2131  *
2132  */
2133 
2134 void jbd2_journal_abort(journal_t *journal, int errno)
2135 {
2136         __journal_abort_soft(journal, errno);
2137 }
2138 
2139 /**
2140  * int jbd2_journal_errno () - returns the journal's error state.
2141  * @journal: journal to examine.
2142  *
2143  * This is the errno number set with jbd2_journal_abort(), the last
2144  * time the journal was mounted - if the journal was stopped
2145  * without calling abort this will be 0.
2146  *
2147  * If the journal has been aborted on this mount time -EROFS will
2148  * be returned.
2149  */
2150 int jbd2_journal_errno(journal_t *journal)
2151 {
2152         int err;
2153 
2154         read_lock(&journal->j_state_lock);
2155         if (journal->j_flags & JBD2_ABORT)
2156                 err = -EROFS;
2157         else
2158                 err = journal->j_errno;
2159         read_unlock(&journal->j_state_lock);
2160         return err;
2161 }
2162 
2163 /**
2164  * int jbd2_journal_clear_err () - clears the journal's error state
2165  * @journal: journal to act on.
2166  *
2167  * An error must be cleared or acked to take a FS out of readonly
2168  * mode.
2169  */
2170 int jbd2_journal_clear_err(journal_t *journal)
2171 {
2172         int err = 0;
2173 
2174         write_lock(&journal->j_state_lock);
2175         if (journal->j_flags & JBD2_ABORT)
2176                 err = -EROFS;
2177         else
2178                 journal->j_errno = 0;
2179         write_unlock(&journal->j_state_lock);
2180         return err;
2181 }
2182 
2183 /**
2184  * void jbd2_journal_ack_err() - Ack journal err.
2185  * @journal: journal to act on.
2186  *
2187  * An error must be cleared or acked to take a FS out of readonly
2188  * mode.
2189  */
2190 void jbd2_journal_ack_err(journal_t *journal)
2191 {
2192         write_lock(&journal->j_state_lock);
2193         if (journal->j_errno)
2194                 journal->j_flags |= JBD2_ACK_ERR;
2195         write_unlock(&journal->j_state_lock);
2196 }
2197 
2198 int jbd2_journal_blocks_per_page(struct inode *inode)
2199 {
2200         return 1 << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
2201 }
2202 
2203 /*
2204  * helper functions to deal with 32 or 64bit block numbers.
2205  */
2206 size_t journal_tag_bytes(journal_t *journal)
2207 {
2208         size_t sz;
2209 
2210         if (jbd2_has_feature_csum3(journal))
2211                 return sizeof(journal_block_tag3_t);
2212 
2213         sz = sizeof(journal_block_tag_t);
2214 
2215         if (jbd2_has_feature_csum2(journal))
2216                 sz += sizeof(__u16);
2217 
2218         if (jbd2_has_feature_64bit(journal))
2219                 return sz;
2220         else
2221                 return sz - sizeof(__u32);
2222 }
2223 
2224 /*
2225  * JBD memory management
2226  *
2227  * These functions are used to allocate block-sized chunks of memory
2228  * used for making copies of buffer_head data.  Very often it will be
2229  * page-sized chunks of data, but sometimes it will be in
2230  * sub-page-size chunks.  (For example, 16k pages on Power systems
2231  * with a 4k block file system.)  For blocks smaller than a page, we
2232  * use a SLAB allocator.  There are slab caches for each block size,
2233  * which are allocated at mount time, if necessary, and we only free
2234  * (all of) the slab caches when/if the jbd2 module is unloaded.  For
2235  * this reason we don't need to a mutex to protect access to
2236  * jbd2_slab[] allocating or releasing memory; only in
2237  * jbd2_journal_create_slab().
2238  */
2239 #define JBD2_MAX_SLABS 8
2240 static struct kmem_cache *jbd2_slab[JBD2_MAX_SLABS];
2241 
2242 static const char *jbd2_slab_names[JBD2_MAX_SLABS] = {
2243         "jbd2_1k", "jbd2_2k", "jbd2_4k", "jbd2_8k",
2244         "jbd2_16k", "jbd2_32k", "jbd2_64k", "jbd2_128k"
2245 };
2246 
2247 
2248 static void jbd2_journal_destroy_slabs(void)
2249 {
2250         int i;
2251 
2252         for (i = 0; i < JBD2_MAX_SLABS; i++) {
2253                 if (jbd2_slab[i])
2254                         kmem_cache_destroy(jbd2_slab[i]);
2255                 jbd2_slab[i] = NULL;
2256         }
2257 }
2258 
2259 static int jbd2_journal_create_slab(size_t size)
2260 {
2261         static DEFINE_MUTEX(jbd2_slab_create_mutex);
2262         int i = order_base_2(size) - 10;
2263         size_t slab_size;
2264 
2265         if (size == PAGE_SIZE)
2266                 return 0;
2267 
2268         if (i >= JBD2_MAX_SLABS)
2269                 return -EINVAL;
2270 
2271         if (unlikely(i < 0))
2272                 i = 0;
2273         mutex_lock(&jbd2_slab_create_mutex);
2274         if (jbd2_slab[i]) {
2275                 mutex_unlock(&jbd2_slab_create_mutex);
2276                 return 0;       /* Already created */
2277         }
2278 
2279         slab_size = 1 << (i+10);
2280         jbd2_slab[i] = kmem_cache_create(jbd2_slab_names[i], slab_size,
2281                                          slab_size, 0, NULL);
2282         mutex_unlock(&jbd2_slab_create_mutex);
2283         if (!jbd2_slab[i]) {
2284                 printk(KERN_EMERG "JBD2: no memory for jbd2_slab cache\n");
2285                 return -ENOMEM;
2286         }
2287         return 0;
2288 }
2289 
2290 static struct kmem_cache *get_slab(size_t size)
2291 {
2292         int i = order_base_2(size) - 10;
2293 
2294         BUG_ON(i >= JBD2_MAX_SLABS);
2295         if (unlikely(i < 0))
2296                 i = 0;
2297         BUG_ON(jbd2_slab[i] == NULL);
2298         return jbd2_slab[i];
2299 }
2300 
2301 void *jbd2_alloc(size_t size, gfp_t flags)
2302 {
2303         void *ptr;
2304 
2305         BUG_ON(size & (size-1)); /* Must be a power of 2 */
2306 
2307         if (size < PAGE_SIZE)
2308                 ptr = kmem_cache_alloc(get_slab(size), flags);
2309         else
2310                 ptr = (void *)__get_free_pages(flags, get_order(size));
2311 
2312         /* Check alignment; SLUB has gotten this wrong in the past,
2313          * and this can lead to user data corruption! */
2314         BUG_ON(((unsigned long) ptr) & (size-1));
2315 
2316         return ptr;
2317 }
2318 
2319 void jbd2_free(void *ptr, size_t size)
2320 {
2321         if (size < PAGE_SIZE)
2322                 kmem_cache_free(get_slab(size), ptr);
2323         else
2324                 free_pages((unsigned long)ptr, get_order(size));
2325 };
2326 
2327 /*
2328  * Journal_head storage management
2329  */
2330 static struct kmem_cache *jbd2_journal_head_cache;
2331 #ifdef CONFIG_JBD2_DEBUG
2332 static atomic_t nr_journal_heads = ATOMIC_INIT(0);
2333 #endif
2334 
2335 static int jbd2_journal_init_journal_head_cache(void)
2336 {
2337         int retval;
2338 
2339         J_ASSERT(jbd2_journal_head_cache == NULL);
2340         jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
2341                                 sizeof(struct journal_head),
2342                                 0,              /* offset */
2343                                 SLAB_TEMPORARY | SLAB_DESTROY_BY_RCU,
2344                                 NULL);          /* ctor */
2345         retval = 0;
2346         if (!jbd2_journal_head_cache) {
2347                 retval = -ENOMEM;
2348                 printk(KERN_EMERG "JBD2: no memory for journal_head cache\n");
2349         }
2350         return retval;
2351 }
2352 
2353 static void jbd2_journal_destroy_journal_head_cache(void)
2354 {
2355         if (jbd2_journal_head_cache) {
2356                 kmem_cache_destroy(jbd2_journal_head_cache);
2357                 jbd2_journal_head_cache = NULL;
2358         }
2359 }
2360 
2361 /*
2362  * journal_head splicing and dicing
2363  */
2364 static struct journal_head *journal_alloc_journal_head(void)
2365 {
2366         struct journal_head *ret;
2367 
2368 #ifdef CONFIG_JBD2_DEBUG
2369         atomic_inc(&nr_journal_heads);
2370 #endif
2371         ret = kmem_cache_zalloc(jbd2_journal_head_cache, GFP_NOFS);
2372         if (!ret) {
2373                 jbd_debug(1, "out of memory for journal_head\n");
2374                 pr_notice_ratelimited("ENOMEM in %s, retrying.\n", __func__);
2375                 ret = kmem_cache_zalloc(jbd2_journal_head_cache,
2376                                 GFP_NOFS | __GFP_NOFAIL);
2377         }
2378         return ret;
2379 }
2380 
2381 static void journal_free_journal_head(struct journal_head *jh)
2382 {
2383 #ifdef CONFIG_JBD2_DEBUG
2384         atomic_dec(&nr_journal_heads);
2385         memset(jh, JBD2_POISON_FREE, sizeof(*jh));
2386 #endif
2387         kmem_cache_free(jbd2_journal_head_cache, jh);
2388 }
2389 
2390 /*
2391  * A journal_head is attached to a buffer_head whenever JBD has an
2392  * interest in the buffer.
2393  *
2394  * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
2395  * is set.  This bit is tested in core kernel code where we need to take
2396  * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
2397  * there.
2398  *
2399  * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
2400  *
2401  * When a buffer has its BH_JBD bit set it is immune from being released by
2402  * core kernel code, mainly via ->b_count.
2403  *
2404  * A journal_head is detached from its buffer_head when the journal_head's
2405  * b_jcount reaches zero. Running transaction (b_transaction) and checkpoint
2406  * transaction (b_cp_transaction) hold their references to b_jcount.
2407  *
2408  * Various places in the kernel want to attach a journal_head to a buffer_head
2409  * _before_ attaching the journal_head to a transaction.  To protect the
2410  * journal_head in this situation, jbd2_journal_add_journal_head elevates the
2411  * journal_head's b_jcount refcount by one.  The caller must call
2412  * jbd2_journal_put_journal_head() to undo this.
2413  *
2414  * So the typical usage would be:
2415  *
2416  *      (Attach a journal_head if needed.  Increments b_jcount)
2417  *      struct journal_head *jh = jbd2_journal_add_journal_head(bh);
2418  *      ...
2419  *      (Get another reference for transaction)
2420  *      jbd2_journal_grab_journal_head(bh);
2421  *      jh->b_transaction = xxx;
2422  *      (Put original reference)
2423  *      jbd2_journal_put_journal_head(jh);
2424  */
2425 
2426 /*
2427  * Give a buffer_head a journal_head.
2428  *
2429  * May sleep.
2430  */
2431 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh)
2432 {
2433         struct journal_head *jh;
2434         struct journal_head *new_jh = NULL;
2435 
2436 repeat:
2437         if (!buffer_jbd(bh))
2438                 new_jh = journal_alloc_journal_head();
2439 
2440         jbd_lock_bh_journal_head(bh);
2441         if (buffer_jbd(bh)) {
2442                 jh = bh2jh(bh);
2443         } else {
2444                 J_ASSERT_BH(bh,
2445                         (atomic_read(&bh->b_count) > 0) ||
2446                         (bh->b_page && bh->b_page->mapping));
2447 
2448                 if (!new_jh) {
2449                         jbd_unlock_bh_journal_head(bh);
2450                         goto repeat;
2451                 }
2452 
2453                 jh = new_jh;
2454                 new_jh = NULL;          /* We consumed it */
2455                 set_buffer_jbd(bh);
2456                 bh->b_private = jh;
2457                 jh->b_bh = bh;
2458                 get_bh(bh);
2459                 BUFFER_TRACE(bh, "added journal_head");
2460         }
2461         jh->b_jcount++;
2462         jbd_unlock_bh_journal_head(bh);
2463         if (new_jh)
2464                 journal_free_journal_head(new_jh);
2465         return bh->b_private;
2466 }
2467 
2468 /*
2469  * Grab a ref against this buffer_head's journal_head.  If it ended up not
2470  * having a journal_head, return NULL
2471  */
2472 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh)
2473 {
2474         struct journal_head *jh = NULL;
2475 
2476         jbd_lock_bh_journal_head(bh);
2477         if (buffer_jbd(bh)) {
2478                 jh = bh2jh(bh);
2479                 jh->b_jcount++;
2480         }
2481         jbd_unlock_bh_journal_head(bh);
2482         return jh;
2483 }
2484 
2485 static void __journal_remove_journal_head(struct buffer_head *bh)
2486 {
2487         struct journal_head *jh = bh2jh(bh);
2488 
2489         J_ASSERT_JH(jh, jh->b_jcount >= 0);
2490         J_ASSERT_JH(jh, jh->b_transaction == NULL);
2491         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
2492         J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
2493         J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
2494         J_ASSERT_BH(bh, buffer_jbd(bh));
2495         J_ASSERT_BH(bh, jh2bh(jh) == bh);
2496         BUFFER_TRACE(bh, "remove journal_head");
2497         if (jh->b_frozen_data) {
2498                 printk(KERN_WARNING "%s: freeing b_frozen_data\n", __func__);
2499                 jbd2_free(jh->b_frozen_data, bh->b_size);
2500         }
2501         if (jh->b_committed_data) {
2502                 printk(KERN_WARNING "%s: freeing b_committed_data\n", __func__);
2503                 jbd2_free(jh->b_committed_data, bh->b_size);
2504         }
2505         bh->b_private = NULL;
2506         jh->b_bh = NULL;        /* debug, really */
2507         clear_buffer_jbd(bh);
2508         journal_free_journal_head(jh);
2509 }
2510 
2511 /*
2512  * Drop a reference on the passed journal_head.  If it fell to zero then
2513  * release the journal_head from the buffer_head.
2514  */
2515 void jbd2_journal_put_journal_head(struct journal_head *jh)
2516 {
2517         struct buffer_head *bh = jh2bh(jh);
2518 
2519         jbd_lock_bh_journal_head(bh);
2520         J_ASSERT_JH(jh, jh->b_jcount > 0);
2521         --jh->b_jcount;
2522         if (!jh->b_jcount) {
2523                 __journal_remove_journal_head(bh);
2524                 jbd_unlock_bh_journal_head(bh);
2525                 __brelse(bh);
2526         } else
2527                 jbd_unlock_bh_journal_head(bh);
2528 }
2529 
2530 /*
2531  * Initialize jbd inode head
2532  */
2533 void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode)
2534 {
2535         jinode->i_transaction = NULL;
2536         jinode->i_next_transaction = NULL;
2537         jinode->i_vfs_inode = inode;
2538         jinode->i_flags = 0;
2539         INIT_LIST_HEAD(&jinode->i_list);
2540 }
2541 
2542 /*
2543  * Function to be called before we start removing inode from memory (i.e.,
2544  * clear_inode() is a fine place to be called from). It removes inode from
2545  * transaction's lists.
2546  */
2547 void jbd2_journal_release_jbd_inode(journal_t *journal,
2548                                     struct jbd2_inode *jinode)
2549 {
2550         if (!journal)
2551                 return;
2552 restart:
2553         spin_lock(&journal->j_list_lock);
2554         /* Is commit writing out inode - we have to wait */
2555         if (jinode->i_flags & JI_COMMIT_RUNNING) {
2556                 wait_queue_head_t *wq;
2557                 DEFINE_WAIT_BIT(wait, &jinode->i_flags, __JI_COMMIT_RUNNING);
2558                 wq = bit_waitqueue(&jinode->i_flags, __JI_COMMIT_RUNNING);
2559                 prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
2560                 spin_unlock(&journal->j_list_lock);
2561                 schedule();
2562                 finish_wait(wq, &wait.wait);
2563                 goto restart;
2564         }
2565 
2566         if (jinode->i_transaction) {
2567                 list_del(&jinode->i_list);
2568                 jinode->i_transaction = NULL;
2569         }
2570         spin_unlock(&journal->j_list_lock);
2571 }
2572 
2573 
2574 #ifdef CONFIG_PROC_FS
2575 
2576 #define JBD2_STATS_PROC_NAME "fs/jbd2"
2577 
2578 static void __init jbd2_create_jbd_stats_proc_entry(void)
2579 {
2580         proc_jbd2_stats = proc_mkdir(JBD2_STATS_PROC_NAME, NULL);
2581 }
2582 
2583 static void __exit jbd2_remove_jbd_stats_proc_entry(void)
2584 {
2585         if (proc_jbd2_stats)
2586                 remove_proc_entry(JBD2_STATS_PROC_NAME, NULL);
2587 }
2588 
2589 #else
2590 
2591 #define jbd2_create_jbd_stats_proc_entry() do {} while (0)
2592 #define jbd2_remove_jbd_stats_proc_entry() do {} while (0)
2593 
2594 #endif
2595 
2596 struct kmem_cache *jbd2_handle_cache, *jbd2_inode_cache;
2597 
2598 static int __init jbd2_journal_init_handle_cache(void)
2599 {
2600         jbd2_handle_cache = KMEM_CACHE(jbd2_journal_handle, SLAB_TEMPORARY);
2601         if (jbd2_handle_cache == NULL) {
2602                 printk(KERN_EMERG "JBD2: failed to create handle cache\n");
2603                 return -ENOMEM;
2604         }
2605         jbd2_inode_cache = KMEM_CACHE(jbd2_inode, 0);
2606         if (jbd2_inode_cache == NULL) {
2607                 printk(KERN_EMERG "JBD2: failed to create inode cache\n");
2608                 kmem_cache_destroy(jbd2_handle_cache);
2609                 return -ENOMEM;
2610         }
2611         return 0;
2612 }
2613 
2614 static void jbd2_journal_destroy_handle_cache(void)
2615 {
2616         if (jbd2_handle_cache)
2617                 kmem_cache_destroy(jbd2_handle_cache);
2618         if (jbd2_inode_cache)
2619                 kmem_cache_destroy(jbd2_inode_cache);
2620 
2621 }
2622 
2623 /*
2624  * Module startup and shutdown
2625  */
2626 
2627 static int __init journal_init_caches(void)
2628 {
2629         int ret;
2630 
2631         ret = jbd2_journal_init_revoke_caches();
2632         if (ret == 0)
2633                 ret = jbd2_journal_init_journal_head_cache();
2634         if (ret == 0)
2635                 ret = jbd2_journal_init_handle_cache();
2636         if (ret == 0)
2637                 ret = jbd2_journal_init_transaction_cache();
2638         return ret;
2639 }
2640 
2641 static void jbd2_journal_destroy_caches(void)
2642 {
2643         jbd2_journal_destroy_revoke_caches();
2644         jbd2_journal_destroy_journal_head_cache();
2645         jbd2_journal_destroy_handle_cache();
2646         jbd2_journal_destroy_transaction_cache();
2647         jbd2_journal_destroy_slabs();
2648 }
2649 
2650 static int __init journal_init(void)
2651 {
2652         int ret;
2653 
2654         BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
2655 
2656         ret = journal_init_caches();
2657         if (ret == 0) {
2658                 jbd2_create_jbd_stats_proc_entry();
2659         } else {
2660                 jbd2_journal_destroy_caches();
2661         }
2662         return ret;
2663 }
2664 
2665 static void __exit journal_exit(void)
2666 {
2667 #ifdef CONFIG_JBD2_DEBUG
2668         int n = atomic_read(&nr_journal_heads);
2669         if (n)
2670                 printk(KERN_ERR "JBD2: leaked %d journal_heads!\n", n);
2671 #endif
2672         jbd2_remove_jbd_stats_proc_entry();
2673         jbd2_journal_destroy_caches();
2674 }
2675 
2676 MODULE_LICENSE("GPL");
2677 module_init(journal_init);
2678 module_exit(journal_exit);
2679 
2680 

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