Loading...
1/*
2 * linux/fs/jbd2/revoke.c
3 *
4 * Written by Stephen C. Tweedie <sct@redhat.com>, 2000
5 *
6 * Copyright 2000 Red Hat corp --- All Rights Reserved
7 *
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
11 *
12 * Journal revoke routines for the generic filesystem journaling code;
13 * part of the ext2fs journaling system.
14 *
15 * Revoke is the mechanism used to prevent old log records for deleted
16 * metadata from being replayed on top of newer data using the same
17 * blocks. The revoke mechanism is used in two separate places:
18 *
19 * + Commit: during commit we write the entire list of the current
20 * transaction's revoked blocks to the journal
21 *
22 * + Recovery: during recovery we record the transaction ID of all
23 * revoked blocks. If there are multiple revoke records in the log
24 * for a single block, only the last one counts, and if there is a log
25 * entry for a block beyond the last revoke, then that log entry still
26 * gets replayed.
27 *
28 * We can get interactions between revokes and new log data within a
29 * single transaction:
30 *
31 * Block is revoked and then journaled:
32 * The desired end result is the journaling of the new block, so we
33 * cancel the revoke before the transaction commits.
34 *
35 * Block is journaled and then revoked:
36 * The revoke must take precedence over the write of the block, so we
37 * need either to cancel the journal entry or to write the revoke
38 * later in the log than the log block. In this case, we choose the
39 * latter: journaling a block cancels any revoke record for that block
40 * in the current transaction, so any revoke for that block in the
41 * transaction must have happened after the block was journaled and so
42 * the revoke must take precedence.
43 *
44 * Block is revoked and then written as data:
45 * The data write is allowed to succeed, but the revoke is _not_
46 * cancelled. We still need to prevent old log records from
47 * overwriting the new data. We don't even need to clear the revoke
48 * bit here.
49 *
50 * We cache revoke status of a buffer in the current transaction in b_states
51 * bits. As the name says, revokevalid flag indicates that the cached revoke
52 * status of a buffer is valid and we can rely on the cached status.
53 *
54 * Revoke information on buffers is a tri-state value:
55 *
56 * RevokeValid clear: no cached revoke status, need to look it up
57 * RevokeValid set, Revoked clear:
58 * buffer has not been revoked, and cancel_revoke
59 * need do nothing.
60 * RevokeValid set, Revoked set:
61 * buffer has been revoked.
62 *
63 * Locking rules:
64 * We keep two hash tables of revoke records. One hashtable belongs to the
65 * running transaction (is pointed to by journal->j_revoke), the other one
66 * belongs to the committing transaction. Accesses to the second hash table
67 * happen only from the kjournald and no other thread touches this table. Also
68 * journal_switch_revoke_table() which switches which hashtable belongs to the
69 * running and which to the committing transaction is called only from
70 * kjournald. Therefore we need no locks when accessing the hashtable belonging
71 * to the committing transaction.
72 *
73 * All users operating on the hash table belonging to the running transaction
74 * have a handle to the transaction. Therefore they are safe from kjournald
75 * switching hash tables under them. For operations on the lists of entries in
76 * the hash table j_revoke_lock is used.
77 *
78 * Finally, also replay code uses the hash tables but at this moment no one else
79 * can touch them (filesystem isn't mounted yet) and hence no locking is
80 * needed.
81 */
82
83#ifndef __KERNEL__
84#include "jfs_user.h"
85#else
86#include <linux/time.h>
87#include <linux/fs.h>
88#include <linux/jbd2.h>
89#include <linux/errno.h>
90#include <linux/slab.h>
91#include <linux/list.h>
92#include <linux/init.h>
93#include <linux/bio.h>
94#include <linux/log2.h>
95#include <linux/hash.h>
96#endif
97
98static struct kmem_cache *jbd2_revoke_record_cache;
99static struct kmem_cache *jbd2_revoke_table_cache;
100
101/* Each revoke record represents one single revoked block. During
102 journal replay, this involves recording the transaction ID of the
103 last transaction to revoke this block. */
104
105struct jbd2_revoke_record_s
106{
107 struct list_head hash;
108 tid_t sequence; /* Used for recovery only */
109 unsigned long long blocknr;
110};
111
112
113/* The revoke table is just a simple hash table of revoke records. */
114struct jbd2_revoke_table_s
115{
116 /* It is conceivable that we might want a larger hash table
117 * for recovery. Must be a power of two. */
118 int hash_size;
119 int hash_shift;
120 struct list_head *hash_table;
121};
122
123
124#ifdef __KERNEL__
125static void write_one_revoke_record(transaction_t *,
126 struct list_head *,
127 struct buffer_head **, int *,
128 struct jbd2_revoke_record_s *);
129static void flush_descriptor(journal_t *, struct buffer_head *, int);
130#endif
131
132/* Utility functions to maintain the revoke table */
133
134static inline int hash(journal_t *journal, unsigned long long block)
135{
136 return hash_64(block, journal->j_revoke->hash_shift);
137}
138
139static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
140 tid_t seq)
141{
142 struct list_head *hash_list;
143 struct jbd2_revoke_record_s *record;
144 gfp_t gfp_mask = GFP_NOFS;
145
146 if (journal_oom_retry)
147 gfp_mask |= __GFP_NOFAIL;
148 record = kmem_cache_alloc(jbd2_revoke_record_cache, gfp_mask);
149 if (!record)
150 return -ENOMEM;
151
152 record->sequence = seq;
153 record->blocknr = blocknr;
154 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
155 spin_lock(&journal->j_revoke_lock);
156 list_add(&record->hash, hash_list);
157 spin_unlock(&journal->j_revoke_lock);
158 return 0;
159}
160
161/* Find a revoke record in the journal's hash table. */
162
163static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
164 unsigned long long blocknr)
165{
166 struct list_head *hash_list;
167 struct jbd2_revoke_record_s *record;
168
169 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
170
171 spin_lock(&journal->j_revoke_lock);
172 record = (struct jbd2_revoke_record_s *) hash_list->next;
173 while (&(record->hash) != hash_list) {
174 if (record->blocknr == blocknr) {
175 spin_unlock(&journal->j_revoke_lock);
176 return record;
177 }
178 record = (struct jbd2_revoke_record_s *) record->hash.next;
179 }
180 spin_unlock(&journal->j_revoke_lock);
181 return NULL;
182}
183
184void jbd2_journal_destroy_revoke_caches(void)
185{
186 if (jbd2_revoke_record_cache) {
187 kmem_cache_destroy(jbd2_revoke_record_cache);
188 jbd2_revoke_record_cache = NULL;
189 }
190 if (jbd2_revoke_table_cache) {
191 kmem_cache_destroy(jbd2_revoke_table_cache);
192 jbd2_revoke_table_cache = NULL;
193 }
194}
195
196int __init jbd2_journal_init_revoke_caches(void)
197{
198 J_ASSERT(!jbd2_revoke_record_cache);
199 J_ASSERT(!jbd2_revoke_table_cache);
200
201 jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s,
202 SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY);
203 if (!jbd2_revoke_record_cache)
204 goto record_cache_failure;
205
206 jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s,
207 SLAB_TEMPORARY);
208 if (!jbd2_revoke_table_cache)
209 goto table_cache_failure;
210 return 0;
211table_cache_failure:
212 jbd2_journal_destroy_revoke_caches();
213record_cache_failure:
214 return -ENOMEM;
215}
216
217static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size)
218{
219 int shift = 0;
220 int tmp = hash_size;
221 struct jbd2_revoke_table_s *table;
222
223 table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
224 if (!table)
225 goto out;
226
227 while((tmp >>= 1UL) != 0UL)
228 shift++;
229
230 table->hash_size = hash_size;
231 table->hash_shift = shift;
232 table->hash_table =
233 kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
234 if (!table->hash_table) {
235 kmem_cache_free(jbd2_revoke_table_cache, table);
236 table = NULL;
237 goto out;
238 }
239
240 for (tmp = 0; tmp < hash_size; tmp++)
241 INIT_LIST_HEAD(&table->hash_table[tmp]);
242
243out:
244 return table;
245}
246
247static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table)
248{
249 int i;
250 struct list_head *hash_list;
251
252 for (i = 0; i < table->hash_size; i++) {
253 hash_list = &table->hash_table[i];
254 J_ASSERT(list_empty(hash_list));
255 }
256
257 kfree(table->hash_table);
258 kmem_cache_free(jbd2_revoke_table_cache, table);
259}
260
261/* Initialise the revoke table for a given journal to a given size. */
262int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
263{
264 J_ASSERT(journal->j_revoke_table[0] == NULL);
265 J_ASSERT(is_power_of_2(hash_size));
266
267 journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size);
268 if (!journal->j_revoke_table[0])
269 goto fail0;
270
271 journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size);
272 if (!journal->j_revoke_table[1])
273 goto fail1;
274
275 journal->j_revoke = journal->j_revoke_table[1];
276
277 spin_lock_init(&journal->j_revoke_lock);
278
279 return 0;
280
281fail1:
282 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
283fail0:
284 return -ENOMEM;
285}
286
287/* Destroy a journal's revoke table. The table must already be empty! */
288void jbd2_journal_destroy_revoke(journal_t *journal)
289{
290 journal->j_revoke = NULL;
291 if (journal->j_revoke_table[0])
292 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
293 if (journal->j_revoke_table[1])
294 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]);
295}
296
297
298#ifdef __KERNEL__
299
300/*
301 * jbd2_journal_revoke: revoke a given buffer_head from the journal. This
302 * prevents the block from being replayed during recovery if we take a
303 * crash after this current transaction commits. Any subsequent
304 * metadata writes of the buffer in this transaction cancel the
305 * revoke.
306 *
307 * Note that this call may block --- it is up to the caller to make
308 * sure that there are no further calls to journal_write_metadata
309 * before the revoke is complete. In ext3, this implies calling the
310 * revoke before clearing the block bitmap when we are deleting
311 * metadata.
312 *
313 * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
314 * parameter, but does _not_ forget the buffer_head if the bh was only
315 * found implicitly.
316 *
317 * bh_in may not be a journalled buffer - it may have come off
318 * the hash tables without an attached journal_head.
319 *
320 * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
321 * by one.
322 */
323
324int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
325 struct buffer_head *bh_in)
326{
327 struct buffer_head *bh = NULL;
328 journal_t *journal;
329 struct block_device *bdev;
330 int err;
331
332 might_sleep();
333 if (bh_in)
334 BUFFER_TRACE(bh_in, "enter");
335
336 journal = handle->h_transaction->t_journal;
337 if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
338 J_ASSERT (!"Cannot set revoke feature!");
339 return -EINVAL;
340 }
341
342 bdev = journal->j_fs_dev;
343 bh = bh_in;
344
345 if (!bh) {
346 bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
347 if (bh)
348 BUFFER_TRACE(bh, "found on hash");
349 }
350#ifdef JBD2_EXPENSIVE_CHECKING
351 else {
352 struct buffer_head *bh2;
353
354 /* If there is a different buffer_head lying around in
355 * memory anywhere... */
356 bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
357 if (bh2) {
358 /* ... and it has RevokeValid status... */
359 if (bh2 != bh && buffer_revokevalid(bh2))
360 /* ...then it better be revoked too,
361 * since it's illegal to create a revoke
362 * record against a buffer_head which is
363 * not marked revoked --- that would
364 * risk missing a subsequent revoke
365 * cancel. */
366 J_ASSERT_BH(bh2, buffer_revoked(bh2));
367 put_bh(bh2);
368 }
369 }
370#endif
371
372 /* We really ought not ever to revoke twice in a row without
373 first having the revoke cancelled: it's illegal to free a
374 block twice without allocating it in between! */
375 if (bh) {
376 if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
377 "inconsistent data on disk")) {
378 if (!bh_in)
379 brelse(bh);
380 return -EIO;
381 }
382 set_buffer_revoked(bh);
383 set_buffer_revokevalid(bh);
384 if (bh_in) {
385 BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
386 jbd2_journal_forget(handle, bh_in);
387 } else {
388 BUFFER_TRACE(bh, "call brelse");
389 __brelse(bh);
390 }
391 }
392
393 jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
394 err = insert_revoke_hash(journal, blocknr,
395 handle->h_transaction->t_tid);
396 BUFFER_TRACE(bh_in, "exit");
397 return err;
398}
399
400/*
401 * Cancel an outstanding revoke. For use only internally by the
402 * journaling code (called from jbd2_journal_get_write_access).
403 *
404 * We trust buffer_revoked() on the buffer if the buffer is already
405 * being journaled: if there is no revoke pending on the buffer, then we
406 * don't do anything here.
407 *
408 * This would break if it were possible for a buffer to be revoked and
409 * discarded, and then reallocated within the same transaction. In such
410 * a case we would have lost the revoked bit, but when we arrived here
411 * the second time we would still have a pending revoke to cancel. So,
412 * do not trust the Revoked bit on buffers unless RevokeValid is also
413 * set.
414 */
415int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
416{
417 struct jbd2_revoke_record_s *record;
418 journal_t *journal = handle->h_transaction->t_journal;
419 int need_cancel;
420 int did_revoke = 0; /* akpm: debug */
421 struct buffer_head *bh = jh2bh(jh);
422
423 jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
424
425 /* Is the existing Revoke bit valid? If so, we trust it, and
426 * only perform the full cancel if the revoke bit is set. If
427 * not, we can't trust the revoke bit, and we need to do the
428 * full search for a revoke record. */
429 if (test_set_buffer_revokevalid(bh)) {
430 need_cancel = test_clear_buffer_revoked(bh);
431 } else {
432 need_cancel = 1;
433 clear_buffer_revoked(bh);
434 }
435
436 if (need_cancel) {
437 record = find_revoke_record(journal, bh->b_blocknr);
438 if (record) {
439 jbd_debug(4, "cancelled existing revoke on "
440 "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
441 spin_lock(&journal->j_revoke_lock);
442 list_del(&record->hash);
443 spin_unlock(&journal->j_revoke_lock);
444 kmem_cache_free(jbd2_revoke_record_cache, record);
445 did_revoke = 1;
446 }
447 }
448
449#ifdef JBD2_EXPENSIVE_CHECKING
450 /* There better not be one left behind by now! */
451 record = find_revoke_record(journal, bh->b_blocknr);
452 J_ASSERT_JH(jh, record == NULL);
453#endif
454
455 /* Finally, have we just cleared revoke on an unhashed
456 * buffer_head? If so, we'd better make sure we clear the
457 * revoked status on any hashed alias too, otherwise the revoke
458 * state machine will get very upset later on. */
459 if (need_cancel) {
460 struct buffer_head *bh2;
461 bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
462 if (bh2) {
463 if (bh2 != bh)
464 clear_buffer_revoked(bh2);
465 __brelse(bh2);
466 }
467 }
468 return did_revoke;
469}
470
471/*
472 * journal_clear_revoked_flag clears revoked flag of buffers in
473 * revoke table to reflect there is no revoked buffers in the next
474 * transaction which is going to be started.
475 */
476void jbd2_clear_buffer_revoked_flags(journal_t *journal)
477{
478 struct jbd2_revoke_table_s *revoke = journal->j_revoke;
479 int i = 0;
480
481 for (i = 0; i < revoke->hash_size; i++) {
482 struct list_head *hash_list;
483 struct list_head *list_entry;
484 hash_list = &revoke->hash_table[i];
485
486 list_for_each(list_entry, hash_list) {
487 struct jbd2_revoke_record_s *record;
488 struct buffer_head *bh;
489 record = (struct jbd2_revoke_record_s *)list_entry;
490 bh = __find_get_block(journal->j_fs_dev,
491 record->blocknr,
492 journal->j_blocksize);
493 if (bh) {
494 clear_buffer_revoked(bh);
495 __brelse(bh);
496 }
497 }
498 }
499}
500
501/* journal_switch_revoke table select j_revoke for next transaction
502 * we do not want to suspend any processing until all revokes are
503 * written -bzzz
504 */
505void jbd2_journal_switch_revoke_table(journal_t *journal)
506{
507 int i;
508
509 if (journal->j_revoke == journal->j_revoke_table[0])
510 journal->j_revoke = journal->j_revoke_table[1];
511 else
512 journal->j_revoke = journal->j_revoke_table[0];
513
514 for (i = 0; i < journal->j_revoke->hash_size; i++)
515 INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
516}
517
518/*
519 * Write revoke records to the journal for all entries in the current
520 * revoke hash, deleting the entries as we go.
521 */
522void jbd2_journal_write_revoke_records(transaction_t *transaction,
523 struct list_head *log_bufs)
524{
525 journal_t *journal = transaction->t_journal;
526 struct buffer_head *descriptor;
527 struct jbd2_revoke_record_s *record;
528 struct jbd2_revoke_table_s *revoke;
529 struct list_head *hash_list;
530 int i, offset, count;
531
532 descriptor = NULL;
533 offset = 0;
534 count = 0;
535
536 /* select revoke table for committing transaction */
537 revoke = journal->j_revoke == journal->j_revoke_table[0] ?
538 journal->j_revoke_table[1] : journal->j_revoke_table[0];
539
540 for (i = 0; i < revoke->hash_size; i++) {
541 hash_list = &revoke->hash_table[i];
542
543 while (!list_empty(hash_list)) {
544 record = (struct jbd2_revoke_record_s *)
545 hash_list->next;
546 write_one_revoke_record(transaction, log_bufs,
547 &descriptor, &offset, record);
548 count++;
549 list_del(&record->hash);
550 kmem_cache_free(jbd2_revoke_record_cache, record);
551 }
552 }
553 if (descriptor)
554 flush_descriptor(journal, descriptor, offset);
555 jbd_debug(1, "Wrote %d revoke records\n", count);
556}
557
558/*
559 * Write out one revoke record. We need to create a new descriptor
560 * block if the old one is full or if we have not already created one.
561 */
562
563static void write_one_revoke_record(transaction_t *transaction,
564 struct list_head *log_bufs,
565 struct buffer_head **descriptorp,
566 int *offsetp,
567 struct jbd2_revoke_record_s *record)
568{
569 journal_t *journal = transaction->t_journal;
570 int csum_size = 0;
571 struct buffer_head *descriptor;
572 int sz, offset;
573
574 /* If we are already aborting, this all becomes a noop. We
575 still need to go round the loop in
576 jbd2_journal_write_revoke_records in order to free all of the
577 revoke records: only the IO to the journal is omitted. */
578 if (is_journal_aborted(journal))
579 return;
580
581 descriptor = *descriptorp;
582 offset = *offsetp;
583
584 /* Do we need to leave space at the end for a checksum? */
585 if (jbd2_journal_has_csum_v2or3(journal))
586 csum_size = sizeof(struct jbd2_journal_block_tail);
587
588 if (jbd2_has_feature_64bit(journal))
589 sz = 8;
590 else
591 sz = 4;
592
593 /* Make sure we have a descriptor with space left for the record */
594 if (descriptor) {
595 if (offset + sz > journal->j_blocksize - csum_size) {
596 flush_descriptor(journal, descriptor, offset);
597 descriptor = NULL;
598 }
599 }
600
601 if (!descriptor) {
602 descriptor = jbd2_journal_get_descriptor_buffer(transaction,
603 JBD2_REVOKE_BLOCK);
604 if (!descriptor)
605 return;
606
607 /* Record it so that we can wait for IO completion later */
608 BUFFER_TRACE(descriptor, "file in log_bufs");
609 jbd2_file_log_bh(log_bufs, descriptor);
610
611 offset = sizeof(jbd2_journal_revoke_header_t);
612 *descriptorp = descriptor;
613 }
614
615 if (jbd2_has_feature_64bit(journal))
616 * ((__be64 *)(&descriptor->b_data[offset])) =
617 cpu_to_be64(record->blocknr);
618 else
619 * ((__be32 *)(&descriptor->b_data[offset])) =
620 cpu_to_be32(record->blocknr);
621 offset += sz;
622
623 *offsetp = offset;
624}
625
626/*
627 * Flush a revoke descriptor out to the journal. If we are aborting,
628 * this is a noop; otherwise we are generating a buffer which needs to
629 * be waited for during commit, so it has to go onto the appropriate
630 * journal buffer list.
631 */
632
633static void flush_descriptor(journal_t *journal,
634 struct buffer_head *descriptor,
635 int offset)
636{
637 jbd2_journal_revoke_header_t *header;
638
639 if (is_journal_aborted(journal)) {
640 put_bh(descriptor);
641 return;
642 }
643
644 header = (jbd2_journal_revoke_header_t *)descriptor->b_data;
645 header->r_count = cpu_to_be32(offset);
646 jbd2_descriptor_block_csum_set(journal, descriptor);
647
648 set_buffer_jwrite(descriptor);
649 BUFFER_TRACE(descriptor, "write");
650 set_buffer_dirty(descriptor);
651 write_dirty_buffer(descriptor, WRITE_SYNC);
652}
653#endif
654
655/*
656 * Revoke support for recovery.
657 *
658 * Recovery needs to be able to:
659 *
660 * record all revoke records, including the tid of the latest instance
661 * of each revoke in the journal
662 *
663 * check whether a given block in a given transaction should be replayed
664 * (ie. has not been revoked by a revoke record in that or a subsequent
665 * transaction)
666 *
667 * empty the revoke table after recovery.
668 */
669
670/*
671 * First, setting revoke records. We create a new revoke record for
672 * every block ever revoked in the log as we scan it for recovery, and
673 * we update the existing records if we find multiple revokes for a
674 * single block.
675 */
676
677int jbd2_journal_set_revoke(journal_t *journal,
678 unsigned long long blocknr,
679 tid_t sequence)
680{
681 struct jbd2_revoke_record_s *record;
682
683 record = find_revoke_record(journal, blocknr);
684 if (record) {
685 /* If we have multiple occurrences, only record the
686 * latest sequence number in the hashed record */
687 if (tid_gt(sequence, record->sequence))
688 record->sequence = sequence;
689 return 0;
690 }
691 return insert_revoke_hash(journal, blocknr, sequence);
692}
693
694/*
695 * Test revoke records. For a given block referenced in the log, has
696 * that block been revoked? A revoke record with a given transaction
697 * sequence number revokes all blocks in that transaction and earlier
698 * ones, but later transactions still need replayed.
699 */
700
701int jbd2_journal_test_revoke(journal_t *journal,
702 unsigned long long blocknr,
703 tid_t sequence)
704{
705 struct jbd2_revoke_record_s *record;
706
707 record = find_revoke_record(journal, blocknr);
708 if (!record)
709 return 0;
710 if (tid_gt(sequence, record->sequence))
711 return 0;
712 return 1;
713}
714
715/*
716 * Finally, once recovery is over, we need to clear the revoke table so
717 * that it can be reused by the running filesystem.
718 */
719
720void jbd2_journal_clear_revoke(journal_t *journal)
721{
722 int i;
723 struct list_head *hash_list;
724 struct jbd2_revoke_record_s *record;
725 struct jbd2_revoke_table_s *revoke;
726
727 revoke = journal->j_revoke;
728
729 for (i = 0; i < revoke->hash_size; i++) {
730 hash_list = &revoke->hash_table[i];
731 while (!list_empty(hash_list)) {
732 record = (struct jbd2_revoke_record_s*) hash_list->next;
733 list_del(&record->hash);
734 kmem_cache_free(jbd2_revoke_record_cache, record);
735 }
736 }
737}
1/*
2 * linux/fs/jbd2/revoke.c
3 *
4 * Written by Stephen C. Tweedie <sct@redhat.com>, 2000
5 *
6 * Copyright 2000 Red Hat corp --- All Rights Reserved
7 *
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
11 *
12 * Journal revoke routines for the generic filesystem journaling code;
13 * part of the ext2fs journaling system.
14 *
15 * Revoke is the mechanism used to prevent old log records for deleted
16 * metadata from being replayed on top of newer data using the same
17 * blocks. The revoke mechanism is used in two separate places:
18 *
19 * + Commit: during commit we write the entire list of the current
20 * transaction's revoked blocks to the journal
21 *
22 * + Recovery: during recovery we record the transaction ID of all
23 * revoked blocks. If there are multiple revoke records in the log
24 * for a single block, only the last one counts, and if there is a log
25 * entry for a block beyond the last revoke, then that log entry still
26 * gets replayed.
27 *
28 * We can get interactions between revokes and new log data within a
29 * single transaction:
30 *
31 * Block is revoked and then journaled:
32 * The desired end result is the journaling of the new block, so we
33 * cancel the revoke before the transaction commits.
34 *
35 * Block is journaled and then revoked:
36 * The revoke must take precedence over the write of the block, so we
37 * need either to cancel the journal entry or to write the revoke
38 * later in the log than the log block. In this case, we choose the
39 * latter: journaling a block cancels any revoke record for that block
40 * in the current transaction, so any revoke for that block in the
41 * transaction must have happened after the block was journaled and so
42 * the revoke must take precedence.
43 *
44 * Block is revoked and then written as data:
45 * The data write is allowed to succeed, but the revoke is _not_
46 * cancelled. We still need to prevent old log records from
47 * overwriting the new data. We don't even need to clear the revoke
48 * bit here.
49 *
50 * We cache revoke status of a buffer in the current transaction in b_states
51 * bits. As the name says, revokevalid flag indicates that the cached revoke
52 * status of a buffer is valid and we can rely on the cached status.
53 *
54 * Revoke information on buffers is a tri-state value:
55 *
56 * RevokeValid clear: no cached revoke status, need to look it up
57 * RevokeValid set, Revoked clear:
58 * buffer has not been revoked, and cancel_revoke
59 * need do nothing.
60 * RevokeValid set, Revoked set:
61 * buffer has been revoked.
62 *
63 * Locking rules:
64 * We keep two hash tables of revoke records. One hashtable belongs to the
65 * running transaction (is pointed to by journal->j_revoke), the other one
66 * belongs to the committing transaction. Accesses to the second hash table
67 * happen only from the kjournald and no other thread touches this table. Also
68 * journal_switch_revoke_table() which switches which hashtable belongs to the
69 * running and which to the committing transaction is called only from
70 * kjournald. Therefore we need no locks when accessing the hashtable belonging
71 * to the committing transaction.
72 *
73 * All users operating on the hash table belonging to the running transaction
74 * have a handle to the transaction. Therefore they are safe from kjournald
75 * switching hash tables under them. For operations on the lists of entries in
76 * the hash table j_revoke_lock is used.
77 *
78 * Finally, also replay code uses the hash tables but at this moment no one else
79 * can touch them (filesystem isn't mounted yet) and hence no locking is
80 * needed.
81 */
82
83#ifndef __KERNEL__
84#include "jfs_user.h"
85#else
86#include <linux/time.h>
87#include <linux/fs.h>
88#include <linux/jbd2.h>
89#include <linux/errno.h>
90#include <linux/slab.h>
91#include <linux/list.h>
92#include <linux/init.h>
93#include <linux/bio.h>
94#include <linux/log2.h>
95#include <linux/hash.h>
96#endif
97
98static struct kmem_cache *jbd2_revoke_record_cache;
99static struct kmem_cache *jbd2_revoke_table_cache;
100
101/* Each revoke record represents one single revoked block. During
102 journal replay, this involves recording the transaction ID of the
103 last transaction to revoke this block. */
104
105struct jbd2_revoke_record_s
106{
107 struct list_head hash;
108 tid_t sequence; /* Used for recovery only */
109 unsigned long long blocknr;
110};
111
112
113/* The revoke table is just a simple hash table of revoke records. */
114struct jbd2_revoke_table_s
115{
116 /* It is conceivable that we might want a larger hash table
117 * for recovery. Must be a power of two. */
118 int hash_size;
119 int hash_shift;
120 struct list_head *hash_table;
121};
122
123
124#ifdef __KERNEL__
125static void write_one_revoke_record(transaction_t *,
126 struct list_head *,
127 struct buffer_head **, int *,
128 struct jbd2_revoke_record_s *);
129static void flush_descriptor(journal_t *, struct buffer_head *, int);
130#endif
131
132/* Utility functions to maintain the revoke table */
133
134static inline int hash(journal_t *journal, unsigned long long block)
135{
136 return hash_64(block, journal->j_revoke->hash_shift);
137}
138
139static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
140 tid_t seq)
141{
142 struct list_head *hash_list;
143 struct jbd2_revoke_record_s *record;
144 gfp_t gfp_mask = GFP_NOFS;
145
146 if (journal_oom_retry)
147 gfp_mask |= __GFP_NOFAIL;
148 record = kmem_cache_alloc(jbd2_revoke_record_cache, gfp_mask);
149 if (!record)
150 return -ENOMEM;
151
152 record->sequence = seq;
153 record->blocknr = blocknr;
154 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
155 spin_lock(&journal->j_revoke_lock);
156 list_add(&record->hash, hash_list);
157 spin_unlock(&journal->j_revoke_lock);
158 return 0;
159}
160
161/* Find a revoke record in the journal's hash table. */
162
163static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
164 unsigned long long blocknr)
165{
166 struct list_head *hash_list;
167 struct jbd2_revoke_record_s *record;
168
169 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
170
171 spin_lock(&journal->j_revoke_lock);
172 record = (struct jbd2_revoke_record_s *) hash_list->next;
173 while (&(record->hash) != hash_list) {
174 if (record->blocknr == blocknr) {
175 spin_unlock(&journal->j_revoke_lock);
176 return record;
177 }
178 record = (struct jbd2_revoke_record_s *) record->hash.next;
179 }
180 spin_unlock(&journal->j_revoke_lock);
181 return NULL;
182}
183
184void jbd2_journal_destroy_revoke_caches(void)
185{
186 if (jbd2_revoke_record_cache) {
187 kmem_cache_destroy(jbd2_revoke_record_cache);
188 jbd2_revoke_record_cache = NULL;
189 }
190 if (jbd2_revoke_table_cache) {
191 kmem_cache_destroy(jbd2_revoke_table_cache);
192 jbd2_revoke_table_cache = NULL;
193 }
194}
195
196int __init jbd2_journal_init_revoke_caches(void)
197{
198 J_ASSERT(!jbd2_revoke_record_cache);
199 J_ASSERT(!jbd2_revoke_table_cache);
200
201 jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s,
202 SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY);
203 if (!jbd2_revoke_record_cache)
204 goto record_cache_failure;
205
206 jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s,
207 SLAB_TEMPORARY);
208 if (!jbd2_revoke_table_cache)
209 goto table_cache_failure;
210 return 0;
211table_cache_failure:
212 jbd2_journal_destroy_revoke_caches();
213record_cache_failure:
214 return -ENOMEM;
215}
216
217static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size)
218{
219 int shift = 0;
220 int tmp = hash_size;
221 struct jbd2_revoke_table_s *table;
222
223 table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
224 if (!table)
225 goto out;
226
227 while((tmp >>= 1UL) != 0UL)
228 shift++;
229
230 table->hash_size = hash_size;
231 table->hash_shift = shift;
232 table->hash_table =
233 kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
234 if (!table->hash_table) {
235 kmem_cache_free(jbd2_revoke_table_cache, table);
236 table = NULL;
237 goto out;
238 }
239
240 for (tmp = 0; tmp < hash_size; tmp++)
241 INIT_LIST_HEAD(&table->hash_table[tmp]);
242
243out:
244 return table;
245}
246
247static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table)
248{
249 int i;
250 struct list_head *hash_list;
251
252 for (i = 0; i < table->hash_size; i++) {
253 hash_list = &table->hash_table[i];
254 J_ASSERT(list_empty(hash_list));
255 }
256
257 kfree(table->hash_table);
258 kmem_cache_free(jbd2_revoke_table_cache, table);
259}
260
261/* Initialise the revoke table for a given journal to a given size. */
262int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
263{
264 J_ASSERT(journal->j_revoke_table[0] == NULL);
265 J_ASSERT(is_power_of_2(hash_size));
266
267 journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size);
268 if (!journal->j_revoke_table[0])
269 goto fail0;
270
271 journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size);
272 if (!journal->j_revoke_table[1])
273 goto fail1;
274
275 journal->j_revoke = journal->j_revoke_table[1];
276
277 spin_lock_init(&journal->j_revoke_lock);
278
279 return 0;
280
281fail1:
282 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
283 journal->j_revoke_table[0] = NULL;
284fail0:
285 return -ENOMEM;
286}
287
288/* Destroy a journal's revoke table. The table must already be empty! */
289void jbd2_journal_destroy_revoke(journal_t *journal)
290{
291 journal->j_revoke = NULL;
292 if (journal->j_revoke_table[0])
293 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
294 if (journal->j_revoke_table[1])
295 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]);
296}
297
298
299#ifdef __KERNEL__
300
301/*
302 * jbd2_journal_revoke: revoke a given buffer_head from the journal. This
303 * prevents the block from being replayed during recovery if we take a
304 * crash after this current transaction commits. Any subsequent
305 * metadata writes of the buffer in this transaction cancel the
306 * revoke.
307 *
308 * Note that this call may block --- it is up to the caller to make
309 * sure that there are no further calls to journal_write_metadata
310 * before the revoke is complete. In ext3, this implies calling the
311 * revoke before clearing the block bitmap when we are deleting
312 * metadata.
313 *
314 * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
315 * parameter, but does _not_ forget the buffer_head if the bh was only
316 * found implicitly.
317 *
318 * bh_in may not be a journalled buffer - it may have come off
319 * the hash tables without an attached journal_head.
320 *
321 * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
322 * by one.
323 */
324
325int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
326 struct buffer_head *bh_in)
327{
328 struct buffer_head *bh = NULL;
329 journal_t *journal;
330 struct block_device *bdev;
331 int err;
332
333 might_sleep();
334 if (bh_in)
335 BUFFER_TRACE(bh_in, "enter");
336
337 journal = handle->h_transaction->t_journal;
338 if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
339 J_ASSERT (!"Cannot set revoke feature!");
340 return -EINVAL;
341 }
342
343 bdev = journal->j_fs_dev;
344 bh = bh_in;
345
346 if (!bh) {
347 bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
348 if (bh)
349 BUFFER_TRACE(bh, "found on hash");
350 }
351#ifdef JBD2_EXPENSIVE_CHECKING
352 else {
353 struct buffer_head *bh2;
354
355 /* If there is a different buffer_head lying around in
356 * memory anywhere... */
357 bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
358 if (bh2) {
359 /* ... and it has RevokeValid status... */
360 if (bh2 != bh && buffer_revokevalid(bh2))
361 /* ...then it better be revoked too,
362 * since it's illegal to create a revoke
363 * record against a buffer_head which is
364 * not marked revoked --- that would
365 * risk missing a subsequent revoke
366 * cancel. */
367 J_ASSERT_BH(bh2, buffer_revoked(bh2));
368 put_bh(bh2);
369 }
370 }
371#endif
372
373 /* We really ought not ever to revoke twice in a row without
374 first having the revoke cancelled: it's illegal to free a
375 block twice without allocating it in between! */
376 if (bh) {
377 if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
378 "inconsistent data on disk")) {
379 if (!bh_in)
380 brelse(bh);
381 return -EIO;
382 }
383 set_buffer_revoked(bh);
384 set_buffer_revokevalid(bh);
385 if (bh_in) {
386 BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
387 jbd2_journal_forget(handle, bh_in);
388 } else {
389 BUFFER_TRACE(bh, "call brelse");
390 __brelse(bh);
391 }
392 }
393
394 jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
395 err = insert_revoke_hash(journal, blocknr,
396 handle->h_transaction->t_tid);
397 BUFFER_TRACE(bh_in, "exit");
398 return err;
399}
400
401/*
402 * Cancel an outstanding revoke. For use only internally by the
403 * journaling code (called from jbd2_journal_get_write_access).
404 *
405 * We trust buffer_revoked() on the buffer if the buffer is already
406 * being journaled: if there is no revoke pending on the buffer, then we
407 * don't do anything here.
408 *
409 * This would break if it were possible for a buffer to be revoked and
410 * discarded, and then reallocated within the same transaction. In such
411 * a case we would have lost the revoked bit, but when we arrived here
412 * the second time we would still have a pending revoke to cancel. So,
413 * do not trust the Revoked bit on buffers unless RevokeValid is also
414 * set.
415 */
416int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
417{
418 struct jbd2_revoke_record_s *record;
419 journal_t *journal = handle->h_transaction->t_journal;
420 int need_cancel;
421 int did_revoke = 0; /* akpm: debug */
422 struct buffer_head *bh = jh2bh(jh);
423
424 jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
425
426 /* Is the existing Revoke bit valid? If so, we trust it, and
427 * only perform the full cancel if the revoke bit is set. If
428 * not, we can't trust the revoke bit, and we need to do the
429 * full search for a revoke record. */
430 if (test_set_buffer_revokevalid(bh)) {
431 need_cancel = test_clear_buffer_revoked(bh);
432 } else {
433 need_cancel = 1;
434 clear_buffer_revoked(bh);
435 }
436
437 if (need_cancel) {
438 record = find_revoke_record(journal, bh->b_blocknr);
439 if (record) {
440 jbd_debug(4, "cancelled existing revoke on "
441 "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
442 spin_lock(&journal->j_revoke_lock);
443 list_del(&record->hash);
444 spin_unlock(&journal->j_revoke_lock);
445 kmem_cache_free(jbd2_revoke_record_cache, record);
446 did_revoke = 1;
447 }
448 }
449
450#ifdef JBD2_EXPENSIVE_CHECKING
451 /* There better not be one left behind by now! */
452 record = find_revoke_record(journal, bh->b_blocknr);
453 J_ASSERT_JH(jh, record == NULL);
454#endif
455
456 /* Finally, have we just cleared revoke on an unhashed
457 * buffer_head? If so, we'd better make sure we clear the
458 * revoked status on any hashed alias too, otherwise the revoke
459 * state machine will get very upset later on. */
460 if (need_cancel) {
461 struct buffer_head *bh2;
462 bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
463 if (bh2) {
464 if (bh2 != bh)
465 clear_buffer_revoked(bh2);
466 __brelse(bh2);
467 }
468 }
469 return did_revoke;
470}
471
472/*
473 * journal_clear_revoked_flag clears revoked flag of buffers in
474 * revoke table to reflect there is no revoked buffers in the next
475 * transaction which is going to be started.
476 */
477void jbd2_clear_buffer_revoked_flags(journal_t *journal)
478{
479 struct jbd2_revoke_table_s *revoke = journal->j_revoke;
480 int i = 0;
481
482 for (i = 0; i < revoke->hash_size; i++) {
483 struct list_head *hash_list;
484 struct list_head *list_entry;
485 hash_list = &revoke->hash_table[i];
486
487 list_for_each(list_entry, hash_list) {
488 struct jbd2_revoke_record_s *record;
489 struct buffer_head *bh;
490 record = (struct jbd2_revoke_record_s *)list_entry;
491 bh = __find_get_block(journal->j_fs_dev,
492 record->blocknr,
493 journal->j_blocksize);
494 if (bh) {
495 clear_buffer_revoked(bh);
496 __brelse(bh);
497 }
498 }
499 }
500}
501
502/* journal_switch_revoke table select j_revoke for next transaction
503 * we do not want to suspend any processing until all revokes are
504 * written -bzzz
505 */
506void jbd2_journal_switch_revoke_table(journal_t *journal)
507{
508 int i;
509
510 if (journal->j_revoke == journal->j_revoke_table[0])
511 journal->j_revoke = journal->j_revoke_table[1];
512 else
513 journal->j_revoke = journal->j_revoke_table[0];
514
515 for (i = 0; i < journal->j_revoke->hash_size; i++)
516 INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
517}
518
519/*
520 * Write revoke records to the journal for all entries in the current
521 * revoke hash, deleting the entries as we go.
522 */
523void jbd2_journal_write_revoke_records(transaction_t *transaction,
524 struct list_head *log_bufs)
525{
526 journal_t *journal = transaction->t_journal;
527 struct buffer_head *descriptor;
528 struct jbd2_revoke_record_s *record;
529 struct jbd2_revoke_table_s *revoke;
530 struct list_head *hash_list;
531 int i, offset, count;
532
533 descriptor = NULL;
534 offset = 0;
535 count = 0;
536
537 /* select revoke table for committing transaction */
538 revoke = journal->j_revoke == journal->j_revoke_table[0] ?
539 journal->j_revoke_table[1] : journal->j_revoke_table[0];
540
541 for (i = 0; i < revoke->hash_size; i++) {
542 hash_list = &revoke->hash_table[i];
543
544 while (!list_empty(hash_list)) {
545 record = (struct jbd2_revoke_record_s *)
546 hash_list->next;
547 write_one_revoke_record(transaction, log_bufs,
548 &descriptor, &offset, record);
549 count++;
550 list_del(&record->hash);
551 kmem_cache_free(jbd2_revoke_record_cache, record);
552 }
553 }
554 if (descriptor)
555 flush_descriptor(journal, descriptor, offset);
556 jbd_debug(1, "Wrote %d revoke records\n", count);
557}
558
559/*
560 * Write out one revoke record. We need to create a new descriptor
561 * block if the old one is full or if we have not already created one.
562 */
563
564static void write_one_revoke_record(transaction_t *transaction,
565 struct list_head *log_bufs,
566 struct buffer_head **descriptorp,
567 int *offsetp,
568 struct jbd2_revoke_record_s *record)
569{
570 journal_t *journal = transaction->t_journal;
571 int csum_size = 0;
572 struct buffer_head *descriptor;
573 int sz, offset;
574
575 /* If we are already aborting, this all becomes a noop. We
576 still need to go round the loop in
577 jbd2_journal_write_revoke_records in order to free all of the
578 revoke records: only the IO to the journal is omitted. */
579 if (is_journal_aborted(journal))
580 return;
581
582 descriptor = *descriptorp;
583 offset = *offsetp;
584
585 /* Do we need to leave space at the end for a checksum? */
586 if (jbd2_journal_has_csum_v2or3(journal))
587 csum_size = sizeof(struct jbd2_journal_block_tail);
588
589 if (jbd2_has_feature_64bit(journal))
590 sz = 8;
591 else
592 sz = 4;
593
594 /* Make sure we have a descriptor with space left for the record */
595 if (descriptor) {
596 if (offset + sz > journal->j_blocksize - csum_size) {
597 flush_descriptor(journal, descriptor, offset);
598 descriptor = NULL;
599 }
600 }
601
602 if (!descriptor) {
603 descriptor = jbd2_journal_get_descriptor_buffer(transaction,
604 JBD2_REVOKE_BLOCK);
605 if (!descriptor)
606 return;
607
608 /* Record it so that we can wait for IO completion later */
609 BUFFER_TRACE(descriptor, "file in log_bufs");
610 jbd2_file_log_bh(log_bufs, descriptor);
611
612 offset = sizeof(jbd2_journal_revoke_header_t);
613 *descriptorp = descriptor;
614 }
615
616 if (jbd2_has_feature_64bit(journal))
617 * ((__be64 *)(&descriptor->b_data[offset])) =
618 cpu_to_be64(record->blocknr);
619 else
620 * ((__be32 *)(&descriptor->b_data[offset])) =
621 cpu_to_be32(record->blocknr);
622 offset += sz;
623
624 *offsetp = offset;
625}
626
627/*
628 * Flush a revoke descriptor out to the journal. If we are aborting,
629 * this is a noop; otherwise we are generating a buffer which needs to
630 * be waited for during commit, so it has to go onto the appropriate
631 * journal buffer list.
632 */
633
634static void flush_descriptor(journal_t *journal,
635 struct buffer_head *descriptor,
636 int offset)
637{
638 jbd2_journal_revoke_header_t *header;
639
640 if (is_journal_aborted(journal)) {
641 put_bh(descriptor);
642 return;
643 }
644
645 header = (jbd2_journal_revoke_header_t *)descriptor->b_data;
646 header->r_count = cpu_to_be32(offset);
647 jbd2_descriptor_block_csum_set(journal, descriptor);
648
649 set_buffer_jwrite(descriptor);
650 BUFFER_TRACE(descriptor, "write");
651 set_buffer_dirty(descriptor);
652 write_dirty_buffer(descriptor, REQ_SYNC);
653}
654#endif
655
656/*
657 * Revoke support for recovery.
658 *
659 * Recovery needs to be able to:
660 *
661 * record all revoke records, including the tid of the latest instance
662 * of each revoke in the journal
663 *
664 * check whether a given block in a given transaction should be replayed
665 * (ie. has not been revoked by a revoke record in that or a subsequent
666 * transaction)
667 *
668 * empty the revoke table after recovery.
669 */
670
671/*
672 * First, setting revoke records. We create a new revoke record for
673 * every block ever revoked in the log as we scan it for recovery, and
674 * we update the existing records if we find multiple revokes for a
675 * single block.
676 */
677
678int jbd2_journal_set_revoke(journal_t *journal,
679 unsigned long long blocknr,
680 tid_t sequence)
681{
682 struct jbd2_revoke_record_s *record;
683
684 record = find_revoke_record(journal, blocknr);
685 if (record) {
686 /* If we have multiple occurrences, only record the
687 * latest sequence number in the hashed record */
688 if (tid_gt(sequence, record->sequence))
689 record->sequence = sequence;
690 return 0;
691 }
692 return insert_revoke_hash(journal, blocknr, sequence);
693}
694
695/*
696 * Test revoke records. For a given block referenced in the log, has
697 * that block been revoked? A revoke record with a given transaction
698 * sequence number revokes all blocks in that transaction and earlier
699 * ones, but later transactions still need replayed.
700 */
701
702int jbd2_journal_test_revoke(journal_t *journal,
703 unsigned long long blocknr,
704 tid_t sequence)
705{
706 struct jbd2_revoke_record_s *record;
707
708 record = find_revoke_record(journal, blocknr);
709 if (!record)
710 return 0;
711 if (tid_gt(sequence, record->sequence))
712 return 0;
713 return 1;
714}
715
716/*
717 * Finally, once recovery is over, we need to clear the revoke table so
718 * that it can be reused by the running filesystem.
719 */
720
721void jbd2_journal_clear_revoke(journal_t *journal)
722{
723 int i;
724 struct list_head *hash_list;
725 struct jbd2_revoke_record_s *record;
726 struct jbd2_revoke_table_s *revoke;
727
728 revoke = journal->j_revoke;
729
730 for (i = 0; i < revoke->hash_size; i++) {
731 hash_list = &revoke->hash_table[i];
732 while (!list_empty(hash_list)) {
733 record = (struct jbd2_revoke_record_s*) hash_list->next;
734 list_del(&record->hash);
735 kmem_cache_free(jbd2_revoke_record_cache, record);
736 }
737 }
738}