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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#endif
95#include <linux/log2.h>
96
97static struct kmem_cache *jbd2_revoke_record_cache;
98static struct kmem_cache *jbd2_revoke_table_cache;
99
100/* Each revoke record represents one single revoked block. During
101 journal replay, this involves recording the transaction ID of the
102 last transaction to revoke this block. */
103
104struct jbd2_revoke_record_s
105{
106 struct list_head hash;
107 tid_t sequence; /* Used for recovery only */
108 unsigned long long blocknr;
109};
110
111
112/* The revoke table is just a simple hash table of revoke records. */
113struct jbd2_revoke_table_s
114{
115 /* It is conceivable that we might want a larger hash table
116 * for recovery. Must be a power of two. */
117 int hash_size;
118 int hash_shift;
119 struct list_head *hash_table;
120};
121
122
123#ifdef __KERNEL__
124static void write_one_revoke_record(journal_t *, transaction_t *,
125 struct journal_head **, int *,
126 struct jbd2_revoke_record_s *, int);
127static void flush_descriptor(journal_t *, struct journal_head *, int, int);
128#endif
129
130/* Utility functions to maintain the revoke table */
131
132/* Borrowed from buffer.c: this is a tried and tested block hash function */
133static inline int hash(journal_t *journal, unsigned long long block)
134{
135 struct jbd2_revoke_table_s *table = journal->j_revoke;
136 int hash_shift = table->hash_shift;
137 int hash = (int)block ^ (int)((block >> 31) >> 1);
138
139 return ((hash << (hash_shift - 6)) ^
140 (hash >> 13) ^
141 (hash << (hash_shift - 12))) & (table->hash_size - 1);
142}
143
144static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
145 tid_t seq)
146{
147 struct list_head *hash_list;
148 struct jbd2_revoke_record_s *record;
149
150repeat:
151 record = kmem_cache_alloc(jbd2_revoke_record_cache, GFP_NOFS);
152 if (!record)
153 goto oom;
154
155 record->sequence = seq;
156 record->blocknr = blocknr;
157 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
158 spin_lock(&journal->j_revoke_lock);
159 list_add(&record->hash, hash_list);
160 spin_unlock(&journal->j_revoke_lock);
161 return 0;
162
163oom:
164 if (!journal_oom_retry)
165 return -ENOMEM;
166 jbd_debug(1, "ENOMEM in %s, retrying\n", __func__);
167 yield();
168 goto repeat;
169}
170
171/* Find a revoke record in the journal's hash table. */
172
173static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
174 unsigned long long blocknr)
175{
176 struct list_head *hash_list;
177 struct jbd2_revoke_record_s *record;
178
179 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
180
181 spin_lock(&journal->j_revoke_lock);
182 record = (struct jbd2_revoke_record_s *) hash_list->next;
183 while (&(record->hash) != hash_list) {
184 if (record->blocknr == blocknr) {
185 spin_unlock(&journal->j_revoke_lock);
186 return record;
187 }
188 record = (struct jbd2_revoke_record_s *) record->hash.next;
189 }
190 spin_unlock(&journal->j_revoke_lock);
191 return NULL;
192}
193
194void jbd2_journal_destroy_revoke_caches(void)
195{
196 if (jbd2_revoke_record_cache) {
197 kmem_cache_destroy(jbd2_revoke_record_cache);
198 jbd2_revoke_record_cache = NULL;
199 }
200 if (jbd2_revoke_table_cache) {
201 kmem_cache_destroy(jbd2_revoke_table_cache);
202 jbd2_revoke_table_cache = NULL;
203 }
204}
205
206int __init jbd2_journal_init_revoke_caches(void)
207{
208 J_ASSERT(!jbd2_revoke_record_cache);
209 J_ASSERT(!jbd2_revoke_table_cache);
210
211 jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s,
212 SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY);
213 if (!jbd2_revoke_record_cache)
214 goto record_cache_failure;
215
216 jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s,
217 SLAB_TEMPORARY);
218 if (!jbd2_revoke_table_cache)
219 goto table_cache_failure;
220 return 0;
221table_cache_failure:
222 jbd2_journal_destroy_revoke_caches();
223record_cache_failure:
224 return -ENOMEM;
225}
226
227static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size)
228{
229 int shift = 0;
230 int tmp = hash_size;
231 struct jbd2_revoke_table_s *table;
232
233 table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
234 if (!table)
235 goto out;
236
237 while((tmp >>= 1UL) != 0UL)
238 shift++;
239
240 table->hash_size = hash_size;
241 table->hash_shift = shift;
242 table->hash_table =
243 kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
244 if (!table->hash_table) {
245 kmem_cache_free(jbd2_revoke_table_cache, table);
246 table = NULL;
247 goto out;
248 }
249
250 for (tmp = 0; tmp < hash_size; tmp++)
251 INIT_LIST_HEAD(&table->hash_table[tmp]);
252
253out:
254 return table;
255}
256
257static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table)
258{
259 int i;
260 struct list_head *hash_list;
261
262 for (i = 0; i < table->hash_size; i++) {
263 hash_list = &table->hash_table[i];
264 J_ASSERT(list_empty(hash_list));
265 }
266
267 kfree(table->hash_table);
268 kmem_cache_free(jbd2_revoke_table_cache, table);
269}
270
271/* Initialise the revoke table for a given journal to a given size. */
272int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
273{
274 J_ASSERT(journal->j_revoke_table[0] == NULL);
275 J_ASSERT(is_power_of_2(hash_size));
276
277 journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size);
278 if (!journal->j_revoke_table[0])
279 goto fail0;
280
281 journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size);
282 if (!journal->j_revoke_table[1])
283 goto fail1;
284
285 journal->j_revoke = journal->j_revoke_table[1];
286
287 spin_lock_init(&journal->j_revoke_lock);
288
289 return 0;
290
291fail1:
292 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
293fail0:
294 return -ENOMEM;
295}
296
297/* Destroy a journal's revoke table. The table must already be empty! */
298void jbd2_journal_destroy_revoke(journal_t *journal)
299{
300 journal->j_revoke = NULL;
301 if (journal->j_revoke_table[0])
302 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
303 if (journal->j_revoke_table[1])
304 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]);
305}
306
307
308#ifdef __KERNEL__
309
310/*
311 * jbd2_journal_revoke: revoke a given buffer_head from the journal. This
312 * prevents the block from being replayed during recovery if we take a
313 * crash after this current transaction commits. Any subsequent
314 * metadata writes of the buffer in this transaction cancel the
315 * revoke.
316 *
317 * Note that this call may block --- it is up to the caller to make
318 * sure that there are no further calls to journal_write_metadata
319 * before the revoke is complete. In ext3, this implies calling the
320 * revoke before clearing the block bitmap when we are deleting
321 * metadata.
322 *
323 * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
324 * parameter, but does _not_ forget the buffer_head if the bh was only
325 * found implicitly.
326 *
327 * bh_in may not be a journalled buffer - it may have come off
328 * the hash tables without an attached journal_head.
329 *
330 * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
331 * by one.
332 */
333
334int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
335 struct buffer_head *bh_in)
336{
337 struct buffer_head *bh = NULL;
338 journal_t *journal;
339 struct block_device *bdev;
340 int err;
341
342 might_sleep();
343 if (bh_in)
344 BUFFER_TRACE(bh_in, "enter");
345
346 journal = handle->h_transaction->t_journal;
347 if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
348 J_ASSERT (!"Cannot set revoke feature!");
349 return -EINVAL;
350 }
351
352 bdev = journal->j_fs_dev;
353 bh = bh_in;
354
355 if (!bh) {
356 bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
357 if (bh)
358 BUFFER_TRACE(bh, "found on hash");
359 }
360#ifdef JBD2_EXPENSIVE_CHECKING
361 else {
362 struct buffer_head *bh2;
363
364 /* If there is a different buffer_head lying around in
365 * memory anywhere... */
366 bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
367 if (bh2) {
368 /* ... and it has RevokeValid status... */
369 if (bh2 != bh && buffer_revokevalid(bh2))
370 /* ...then it better be revoked too,
371 * since it's illegal to create a revoke
372 * record against a buffer_head which is
373 * not marked revoked --- that would
374 * risk missing a subsequent revoke
375 * cancel. */
376 J_ASSERT_BH(bh2, buffer_revoked(bh2));
377 put_bh(bh2);
378 }
379 }
380#endif
381
382 /* We really ought not ever to revoke twice in a row without
383 first having the revoke cancelled: it's illegal to free a
384 block twice without allocating it in between! */
385 if (bh) {
386 if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
387 "inconsistent data on disk")) {
388 if (!bh_in)
389 brelse(bh);
390 return -EIO;
391 }
392 set_buffer_revoked(bh);
393 set_buffer_revokevalid(bh);
394 if (bh_in) {
395 BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
396 jbd2_journal_forget(handle, bh_in);
397 } else {
398 BUFFER_TRACE(bh, "call brelse");
399 __brelse(bh);
400 }
401 }
402
403 jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
404 err = insert_revoke_hash(journal, blocknr,
405 handle->h_transaction->t_tid);
406 BUFFER_TRACE(bh_in, "exit");
407 return err;
408}
409
410/*
411 * Cancel an outstanding revoke. For use only internally by the
412 * journaling code (called from jbd2_journal_get_write_access).
413 *
414 * We trust buffer_revoked() on the buffer if the buffer is already
415 * being journaled: if there is no revoke pending on the buffer, then we
416 * don't do anything here.
417 *
418 * This would break if it were possible for a buffer to be revoked and
419 * discarded, and then reallocated within the same transaction. In such
420 * a case we would have lost the revoked bit, but when we arrived here
421 * the second time we would still have a pending revoke to cancel. So,
422 * do not trust the Revoked bit on buffers unless RevokeValid is also
423 * set.
424 */
425int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
426{
427 struct jbd2_revoke_record_s *record;
428 journal_t *journal = handle->h_transaction->t_journal;
429 int need_cancel;
430 int did_revoke = 0; /* akpm: debug */
431 struct buffer_head *bh = jh2bh(jh);
432
433 jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
434
435 /* Is the existing Revoke bit valid? If so, we trust it, and
436 * only perform the full cancel if the revoke bit is set. If
437 * not, we can't trust the revoke bit, and we need to do the
438 * full search for a revoke record. */
439 if (test_set_buffer_revokevalid(bh)) {
440 need_cancel = test_clear_buffer_revoked(bh);
441 } else {
442 need_cancel = 1;
443 clear_buffer_revoked(bh);
444 }
445
446 if (need_cancel) {
447 record = find_revoke_record(journal, bh->b_blocknr);
448 if (record) {
449 jbd_debug(4, "cancelled existing revoke on "
450 "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
451 spin_lock(&journal->j_revoke_lock);
452 list_del(&record->hash);
453 spin_unlock(&journal->j_revoke_lock);
454 kmem_cache_free(jbd2_revoke_record_cache, record);
455 did_revoke = 1;
456 }
457 }
458
459#ifdef JBD2_EXPENSIVE_CHECKING
460 /* There better not be one left behind by now! */
461 record = find_revoke_record(journal, bh->b_blocknr);
462 J_ASSERT_JH(jh, record == NULL);
463#endif
464
465 /* Finally, have we just cleared revoke on an unhashed
466 * buffer_head? If so, we'd better make sure we clear the
467 * revoked status on any hashed alias too, otherwise the revoke
468 * state machine will get very upset later on. */
469 if (need_cancel) {
470 struct buffer_head *bh2;
471 bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
472 if (bh2) {
473 if (bh2 != bh)
474 clear_buffer_revoked(bh2);
475 __brelse(bh2);
476 }
477 }
478 return did_revoke;
479}
480
481/*
482 * journal_clear_revoked_flag clears revoked flag of buffers in
483 * revoke table to reflect there is no revoked buffers in the next
484 * transaction which is going to be started.
485 */
486void jbd2_clear_buffer_revoked_flags(journal_t *journal)
487{
488 struct jbd2_revoke_table_s *revoke = journal->j_revoke;
489 int i = 0;
490
491 for (i = 0; i < revoke->hash_size; i++) {
492 struct list_head *hash_list;
493 struct list_head *list_entry;
494 hash_list = &revoke->hash_table[i];
495
496 list_for_each(list_entry, hash_list) {
497 struct jbd2_revoke_record_s *record;
498 struct buffer_head *bh;
499 record = (struct jbd2_revoke_record_s *)list_entry;
500 bh = __find_get_block(journal->j_fs_dev,
501 record->blocknr,
502 journal->j_blocksize);
503 if (bh) {
504 clear_buffer_revoked(bh);
505 __brelse(bh);
506 }
507 }
508 }
509}
510
511/* journal_switch_revoke table select j_revoke for next transaction
512 * we do not want to suspend any processing until all revokes are
513 * written -bzzz
514 */
515void jbd2_journal_switch_revoke_table(journal_t *journal)
516{
517 int i;
518
519 if (journal->j_revoke == journal->j_revoke_table[0])
520 journal->j_revoke = journal->j_revoke_table[1];
521 else
522 journal->j_revoke = journal->j_revoke_table[0];
523
524 for (i = 0; i < journal->j_revoke->hash_size; i++)
525 INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
526}
527
528/*
529 * Write revoke records to the journal for all entries in the current
530 * revoke hash, deleting the entries as we go.
531 */
532void jbd2_journal_write_revoke_records(journal_t *journal,
533 transaction_t *transaction,
534 int write_op)
535{
536 struct journal_head *descriptor;
537 struct jbd2_revoke_record_s *record;
538 struct jbd2_revoke_table_s *revoke;
539 struct list_head *hash_list;
540 int i, offset, count;
541
542 descriptor = NULL;
543 offset = 0;
544 count = 0;
545
546 /* select revoke table for committing transaction */
547 revoke = journal->j_revoke == journal->j_revoke_table[0] ?
548 journal->j_revoke_table[1] : journal->j_revoke_table[0];
549
550 for (i = 0; i < revoke->hash_size; i++) {
551 hash_list = &revoke->hash_table[i];
552
553 while (!list_empty(hash_list)) {
554 record = (struct jbd2_revoke_record_s *)
555 hash_list->next;
556 write_one_revoke_record(journal, transaction,
557 &descriptor, &offset,
558 record, write_op);
559 count++;
560 list_del(&record->hash);
561 kmem_cache_free(jbd2_revoke_record_cache, record);
562 }
563 }
564 if (descriptor)
565 flush_descriptor(journal, descriptor, offset, write_op);
566 jbd_debug(1, "Wrote %d revoke records\n", count);
567}
568
569/*
570 * Write out one revoke record. We need to create a new descriptor
571 * block if the old one is full or if we have not already created one.
572 */
573
574static void write_one_revoke_record(journal_t *journal,
575 transaction_t *transaction,
576 struct journal_head **descriptorp,
577 int *offsetp,
578 struct jbd2_revoke_record_s *record,
579 int write_op)
580{
581 int csum_size = 0;
582 struct journal_head *descriptor;
583 int offset;
584 journal_header_t *header;
585
586 /* If we are already aborting, this all becomes a noop. We
587 still need to go round the loop in
588 jbd2_journal_write_revoke_records in order to free all of the
589 revoke records: only the IO to the journal is omitted. */
590 if (is_journal_aborted(journal))
591 return;
592
593 descriptor = *descriptorp;
594 offset = *offsetp;
595
596 /* Do we need to leave space at the end for a checksum? */
597 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
598 csum_size = sizeof(struct jbd2_journal_revoke_tail);
599
600 /* Make sure we have a descriptor with space left for the record */
601 if (descriptor) {
602 if (offset >= journal->j_blocksize - csum_size) {
603 flush_descriptor(journal, descriptor, offset, write_op);
604 descriptor = NULL;
605 }
606 }
607
608 if (!descriptor) {
609 descriptor = jbd2_journal_get_descriptor_buffer(journal);
610 if (!descriptor)
611 return;
612 header = (journal_header_t *) &jh2bh(descriptor)->b_data[0];
613 header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
614 header->h_blocktype = cpu_to_be32(JBD2_REVOKE_BLOCK);
615 header->h_sequence = cpu_to_be32(transaction->t_tid);
616
617 /* Record it so that we can wait for IO completion later */
618 JBUFFER_TRACE(descriptor, "file as BJ_LogCtl");
619 jbd2_journal_file_buffer(descriptor, transaction, BJ_LogCtl);
620
621 offset = sizeof(jbd2_journal_revoke_header_t);
622 *descriptorp = descriptor;
623 }
624
625 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) {
626 * ((__be64 *)(&jh2bh(descriptor)->b_data[offset])) =
627 cpu_to_be64(record->blocknr);
628 offset += 8;
629
630 } else {
631 * ((__be32 *)(&jh2bh(descriptor)->b_data[offset])) =
632 cpu_to_be32(record->blocknr);
633 offset += 4;
634 }
635
636 *offsetp = offset;
637}
638
639static void jbd2_revoke_csum_set(journal_t *j,
640 struct journal_head *descriptor)
641{
642 struct jbd2_journal_revoke_tail *tail;
643 __u32 csum;
644
645 if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
646 return;
647
648 tail = (struct jbd2_journal_revoke_tail *)
649 (jh2bh(descriptor)->b_data + j->j_blocksize -
650 sizeof(struct jbd2_journal_revoke_tail));
651 tail->r_checksum = 0;
652 csum = jbd2_chksum(j, j->j_csum_seed, jh2bh(descriptor)->b_data,
653 j->j_blocksize);
654 tail->r_checksum = cpu_to_be32(csum);
655}
656
657/*
658 * Flush a revoke descriptor out to the journal. If we are aborting,
659 * this is a noop; otherwise we are generating a buffer which needs to
660 * be waited for during commit, so it has to go onto the appropriate
661 * journal buffer list.
662 */
663
664static void flush_descriptor(journal_t *journal,
665 struct journal_head *descriptor,
666 int offset, int write_op)
667{
668 jbd2_journal_revoke_header_t *header;
669 struct buffer_head *bh = jh2bh(descriptor);
670
671 if (is_journal_aborted(journal)) {
672 put_bh(bh);
673 return;
674 }
675
676 header = (jbd2_journal_revoke_header_t *) jh2bh(descriptor)->b_data;
677 header->r_count = cpu_to_be32(offset);
678 jbd2_revoke_csum_set(journal, descriptor);
679
680 set_buffer_jwrite(bh);
681 BUFFER_TRACE(bh, "write");
682 set_buffer_dirty(bh);
683 write_dirty_buffer(bh, write_op);
684}
685#endif
686
687/*
688 * Revoke support for recovery.
689 *
690 * Recovery needs to be able to:
691 *
692 * record all revoke records, including the tid of the latest instance
693 * of each revoke in the journal
694 *
695 * check whether a given block in a given transaction should be replayed
696 * (ie. has not been revoked by a revoke record in that or a subsequent
697 * transaction)
698 *
699 * empty the revoke table after recovery.
700 */
701
702/*
703 * First, setting revoke records. We create a new revoke record for
704 * every block ever revoked in the log as we scan it for recovery, and
705 * we update the existing records if we find multiple revokes for a
706 * single block.
707 */
708
709int jbd2_journal_set_revoke(journal_t *journal,
710 unsigned long long blocknr,
711 tid_t sequence)
712{
713 struct jbd2_revoke_record_s *record;
714
715 record = find_revoke_record(journal, blocknr);
716 if (record) {
717 /* If we have multiple occurrences, only record the
718 * latest sequence number in the hashed record */
719 if (tid_gt(sequence, record->sequence))
720 record->sequence = sequence;
721 return 0;
722 }
723 return insert_revoke_hash(journal, blocknr, sequence);
724}
725
726/*
727 * Test revoke records. For a given block referenced in the log, has
728 * that block been revoked? A revoke record with a given transaction
729 * sequence number revokes all blocks in that transaction and earlier
730 * ones, but later transactions still need replayed.
731 */
732
733int jbd2_journal_test_revoke(journal_t *journal,
734 unsigned long long blocknr,
735 tid_t sequence)
736{
737 struct jbd2_revoke_record_s *record;
738
739 record = find_revoke_record(journal, blocknr);
740 if (!record)
741 return 0;
742 if (tid_gt(sequence, record->sequence))
743 return 0;
744 return 1;
745}
746
747/*
748 * Finally, once recovery is over, we need to clear the revoke table so
749 * that it can be reused by the running filesystem.
750 */
751
752void jbd2_journal_clear_revoke(journal_t *journal)
753{
754 int i;
755 struct list_head *hash_list;
756 struct jbd2_revoke_record_s *record;
757 struct jbd2_revoke_table_s *revoke;
758
759 revoke = journal->j_revoke;
760
761 for (i = 0; i < revoke->hash_size; i++) {
762 hash_list = &revoke->hash_table[i];
763 while (!list_empty(hash_list)) {
764 record = (struct jbd2_revoke_record_s*) hash_list->next;
765 list_del(&record->hash);
766 kmem_cache_free(jbd2_revoke_record_cache, record);
767 }
768 }
769}
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#endif
95#include <linux/log2.h>
96
97static struct kmem_cache *jbd2_revoke_record_cache;
98static struct kmem_cache *jbd2_revoke_table_cache;
99
100/* Each revoke record represents one single revoked block. During
101 journal replay, this involves recording the transaction ID of the
102 last transaction to revoke this block. */
103
104struct jbd2_revoke_record_s
105{
106 struct list_head hash;
107 tid_t sequence; /* Used for recovery only */
108 unsigned long long blocknr;
109};
110
111
112/* The revoke table is just a simple hash table of revoke records. */
113struct jbd2_revoke_table_s
114{
115 /* It is conceivable that we might want a larger hash table
116 * for recovery. Must be a power of two. */
117 int hash_size;
118 int hash_shift;
119 struct list_head *hash_table;
120};
121
122
123#ifdef __KERNEL__
124static void write_one_revoke_record(journal_t *, transaction_t *,
125 struct list_head *,
126 struct buffer_head **, int *,
127 struct jbd2_revoke_record_s *, int);
128static void flush_descriptor(journal_t *, struct buffer_head *, int, int);
129#endif
130
131/* Utility functions to maintain the revoke table */
132
133/* Borrowed from buffer.c: this is a tried and tested block hash function */
134static inline int hash(journal_t *journal, unsigned long long block)
135{
136 struct jbd2_revoke_table_s *table = journal->j_revoke;
137 int hash_shift = table->hash_shift;
138 int hash = (int)block ^ (int)((block >> 31) >> 1);
139
140 return ((hash << (hash_shift - 6)) ^
141 (hash >> 13) ^
142 (hash << (hash_shift - 12))) & (table->hash_size - 1);
143}
144
145static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
146 tid_t seq)
147{
148 struct list_head *hash_list;
149 struct jbd2_revoke_record_s *record;
150
151repeat:
152 record = kmem_cache_alloc(jbd2_revoke_record_cache, GFP_NOFS);
153 if (!record)
154 goto oom;
155
156 record->sequence = seq;
157 record->blocknr = blocknr;
158 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
159 spin_lock(&journal->j_revoke_lock);
160 list_add(&record->hash, hash_list);
161 spin_unlock(&journal->j_revoke_lock);
162 return 0;
163
164oom:
165 if (!journal_oom_retry)
166 return -ENOMEM;
167 jbd_debug(1, "ENOMEM in %s, retrying\n", __func__);
168 yield();
169 goto repeat;
170}
171
172/* Find a revoke record in the journal's hash table. */
173
174static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
175 unsigned long long blocknr)
176{
177 struct list_head *hash_list;
178 struct jbd2_revoke_record_s *record;
179
180 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
181
182 spin_lock(&journal->j_revoke_lock);
183 record = (struct jbd2_revoke_record_s *) hash_list->next;
184 while (&(record->hash) != hash_list) {
185 if (record->blocknr == blocknr) {
186 spin_unlock(&journal->j_revoke_lock);
187 return record;
188 }
189 record = (struct jbd2_revoke_record_s *) record->hash.next;
190 }
191 spin_unlock(&journal->j_revoke_lock);
192 return NULL;
193}
194
195void jbd2_journal_destroy_revoke_caches(void)
196{
197 if (jbd2_revoke_record_cache) {
198 kmem_cache_destroy(jbd2_revoke_record_cache);
199 jbd2_revoke_record_cache = NULL;
200 }
201 if (jbd2_revoke_table_cache) {
202 kmem_cache_destroy(jbd2_revoke_table_cache);
203 jbd2_revoke_table_cache = NULL;
204 }
205}
206
207int __init jbd2_journal_init_revoke_caches(void)
208{
209 J_ASSERT(!jbd2_revoke_record_cache);
210 J_ASSERT(!jbd2_revoke_table_cache);
211
212 jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s,
213 SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY);
214 if (!jbd2_revoke_record_cache)
215 goto record_cache_failure;
216
217 jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s,
218 SLAB_TEMPORARY);
219 if (!jbd2_revoke_table_cache)
220 goto table_cache_failure;
221 return 0;
222table_cache_failure:
223 jbd2_journal_destroy_revoke_caches();
224record_cache_failure:
225 return -ENOMEM;
226}
227
228static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size)
229{
230 int shift = 0;
231 int tmp = hash_size;
232 struct jbd2_revoke_table_s *table;
233
234 table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
235 if (!table)
236 goto out;
237
238 while((tmp >>= 1UL) != 0UL)
239 shift++;
240
241 table->hash_size = hash_size;
242 table->hash_shift = shift;
243 table->hash_table =
244 kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
245 if (!table->hash_table) {
246 kmem_cache_free(jbd2_revoke_table_cache, table);
247 table = NULL;
248 goto out;
249 }
250
251 for (tmp = 0; tmp < hash_size; tmp++)
252 INIT_LIST_HEAD(&table->hash_table[tmp]);
253
254out:
255 return table;
256}
257
258static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table)
259{
260 int i;
261 struct list_head *hash_list;
262
263 for (i = 0; i < table->hash_size; i++) {
264 hash_list = &table->hash_table[i];
265 J_ASSERT(list_empty(hash_list));
266 }
267
268 kfree(table->hash_table);
269 kmem_cache_free(jbd2_revoke_table_cache, table);
270}
271
272/* Initialise the revoke table for a given journal to a given size. */
273int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
274{
275 J_ASSERT(journal->j_revoke_table[0] == NULL);
276 J_ASSERT(is_power_of_2(hash_size));
277
278 journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size);
279 if (!journal->j_revoke_table[0])
280 goto fail0;
281
282 journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size);
283 if (!journal->j_revoke_table[1])
284 goto fail1;
285
286 journal->j_revoke = journal->j_revoke_table[1];
287
288 spin_lock_init(&journal->j_revoke_lock);
289
290 return 0;
291
292fail1:
293 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
294fail0:
295 return -ENOMEM;
296}
297
298/* Destroy a journal's revoke table. The table must already be empty! */
299void jbd2_journal_destroy_revoke(journal_t *journal)
300{
301 journal->j_revoke = NULL;
302 if (journal->j_revoke_table[0])
303 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
304 if (journal->j_revoke_table[1])
305 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]);
306}
307
308
309#ifdef __KERNEL__
310
311/*
312 * jbd2_journal_revoke: revoke a given buffer_head from the journal. This
313 * prevents the block from being replayed during recovery if we take a
314 * crash after this current transaction commits. Any subsequent
315 * metadata writes of the buffer in this transaction cancel the
316 * revoke.
317 *
318 * Note that this call may block --- it is up to the caller to make
319 * sure that there are no further calls to journal_write_metadata
320 * before the revoke is complete. In ext3, this implies calling the
321 * revoke before clearing the block bitmap when we are deleting
322 * metadata.
323 *
324 * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
325 * parameter, but does _not_ forget the buffer_head if the bh was only
326 * found implicitly.
327 *
328 * bh_in may not be a journalled buffer - it may have come off
329 * the hash tables without an attached journal_head.
330 *
331 * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
332 * by one.
333 */
334
335int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
336 struct buffer_head *bh_in)
337{
338 struct buffer_head *bh = NULL;
339 journal_t *journal;
340 struct block_device *bdev;
341 int err;
342
343 might_sleep();
344 if (bh_in)
345 BUFFER_TRACE(bh_in, "enter");
346
347 journal = handle->h_transaction->t_journal;
348 if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
349 J_ASSERT (!"Cannot set revoke feature!");
350 return -EINVAL;
351 }
352
353 bdev = journal->j_fs_dev;
354 bh = bh_in;
355
356 if (!bh) {
357 bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
358 if (bh)
359 BUFFER_TRACE(bh, "found on hash");
360 }
361#ifdef JBD2_EXPENSIVE_CHECKING
362 else {
363 struct buffer_head *bh2;
364
365 /* If there is a different buffer_head lying around in
366 * memory anywhere... */
367 bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
368 if (bh2) {
369 /* ... and it has RevokeValid status... */
370 if (bh2 != bh && buffer_revokevalid(bh2))
371 /* ...then it better be revoked too,
372 * since it's illegal to create a revoke
373 * record against a buffer_head which is
374 * not marked revoked --- that would
375 * risk missing a subsequent revoke
376 * cancel. */
377 J_ASSERT_BH(bh2, buffer_revoked(bh2));
378 put_bh(bh2);
379 }
380 }
381#endif
382
383 /* We really ought not ever to revoke twice in a row without
384 first having the revoke cancelled: it's illegal to free a
385 block twice without allocating it in between! */
386 if (bh) {
387 if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
388 "inconsistent data on disk")) {
389 if (!bh_in)
390 brelse(bh);
391 return -EIO;
392 }
393 set_buffer_revoked(bh);
394 set_buffer_revokevalid(bh);
395 if (bh_in) {
396 BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
397 jbd2_journal_forget(handle, bh_in);
398 } else {
399 BUFFER_TRACE(bh, "call brelse");
400 __brelse(bh);
401 }
402 }
403
404 jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
405 err = insert_revoke_hash(journal, blocknr,
406 handle->h_transaction->t_tid);
407 BUFFER_TRACE(bh_in, "exit");
408 return err;
409}
410
411/*
412 * Cancel an outstanding revoke. For use only internally by the
413 * journaling code (called from jbd2_journal_get_write_access).
414 *
415 * We trust buffer_revoked() on the buffer if the buffer is already
416 * being journaled: if there is no revoke pending on the buffer, then we
417 * don't do anything here.
418 *
419 * This would break if it were possible for a buffer to be revoked and
420 * discarded, and then reallocated within the same transaction. In such
421 * a case we would have lost the revoked bit, but when we arrived here
422 * the second time we would still have a pending revoke to cancel. So,
423 * do not trust the Revoked bit on buffers unless RevokeValid is also
424 * set.
425 */
426int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
427{
428 struct jbd2_revoke_record_s *record;
429 journal_t *journal = handle->h_transaction->t_journal;
430 int need_cancel;
431 int did_revoke = 0; /* akpm: debug */
432 struct buffer_head *bh = jh2bh(jh);
433
434 jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
435
436 /* Is the existing Revoke bit valid? If so, we trust it, and
437 * only perform the full cancel if the revoke bit is set. If
438 * not, we can't trust the revoke bit, and we need to do the
439 * full search for a revoke record. */
440 if (test_set_buffer_revokevalid(bh)) {
441 need_cancel = test_clear_buffer_revoked(bh);
442 } else {
443 need_cancel = 1;
444 clear_buffer_revoked(bh);
445 }
446
447 if (need_cancel) {
448 record = find_revoke_record(journal, bh->b_blocknr);
449 if (record) {
450 jbd_debug(4, "cancelled existing revoke on "
451 "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
452 spin_lock(&journal->j_revoke_lock);
453 list_del(&record->hash);
454 spin_unlock(&journal->j_revoke_lock);
455 kmem_cache_free(jbd2_revoke_record_cache, record);
456 did_revoke = 1;
457 }
458 }
459
460#ifdef JBD2_EXPENSIVE_CHECKING
461 /* There better not be one left behind by now! */
462 record = find_revoke_record(journal, bh->b_blocknr);
463 J_ASSERT_JH(jh, record == NULL);
464#endif
465
466 /* Finally, have we just cleared revoke on an unhashed
467 * buffer_head? If so, we'd better make sure we clear the
468 * revoked status on any hashed alias too, otherwise the revoke
469 * state machine will get very upset later on. */
470 if (need_cancel) {
471 struct buffer_head *bh2;
472 bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
473 if (bh2) {
474 if (bh2 != bh)
475 clear_buffer_revoked(bh2);
476 __brelse(bh2);
477 }
478 }
479 return did_revoke;
480}
481
482/*
483 * journal_clear_revoked_flag clears revoked flag of buffers in
484 * revoke table to reflect there is no revoked buffers in the next
485 * transaction which is going to be started.
486 */
487void jbd2_clear_buffer_revoked_flags(journal_t *journal)
488{
489 struct jbd2_revoke_table_s *revoke = journal->j_revoke;
490 int i = 0;
491
492 for (i = 0; i < revoke->hash_size; i++) {
493 struct list_head *hash_list;
494 struct list_head *list_entry;
495 hash_list = &revoke->hash_table[i];
496
497 list_for_each(list_entry, hash_list) {
498 struct jbd2_revoke_record_s *record;
499 struct buffer_head *bh;
500 record = (struct jbd2_revoke_record_s *)list_entry;
501 bh = __find_get_block(journal->j_fs_dev,
502 record->blocknr,
503 journal->j_blocksize);
504 if (bh) {
505 clear_buffer_revoked(bh);
506 __brelse(bh);
507 }
508 }
509 }
510}
511
512/* journal_switch_revoke table select j_revoke for next transaction
513 * we do not want to suspend any processing until all revokes are
514 * written -bzzz
515 */
516void jbd2_journal_switch_revoke_table(journal_t *journal)
517{
518 int i;
519
520 if (journal->j_revoke == journal->j_revoke_table[0])
521 journal->j_revoke = journal->j_revoke_table[1];
522 else
523 journal->j_revoke = journal->j_revoke_table[0];
524
525 for (i = 0; i < journal->j_revoke->hash_size; i++)
526 INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
527}
528
529/*
530 * Write revoke records to the journal for all entries in the current
531 * revoke hash, deleting the entries as we go.
532 */
533void jbd2_journal_write_revoke_records(journal_t *journal,
534 transaction_t *transaction,
535 struct list_head *log_bufs,
536 int write_op)
537{
538 struct buffer_head *descriptor;
539 struct jbd2_revoke_record_s *record;
540 struct jbd2_revoke_table_s *revoke;
541 struct list_head *hash_list;
542 int i, offset, count;
543
544 descriptor = NULL;
545 offset = 0;
546 count = 0;
547
548 /* select revoke table for committing transaction */
549 revoke = journal->j_revoke == journal->j_revoke_table[0] ?
550 journal->j_revoke_table[1] : journal->j_revoke_table[0];
551
552 for (i = 0; i < revoke->hash_size; i++) {
553 hash_list = &revoke->hash_table[i];
554
555 while (!list_empty(hash_list)) {
556 record = (struct jbd2_revoke_record_s *)
557 hash_list->next;
558 write_one_revoke_record(journal, transaction, log_bufs,
559 &descriptor, &offset,
560 record, write_op);
561 count++;
562 list_del(&record->hash);
563 kmem_cache_free(jbd2_revoke_record_cache, record);
564 }
565 }
566 if (descriptor)
567 flush_descriptor(journal, descriptor, offset, write_op);
568 jbd_debug(1, "Wrote %d revoke records\n", count);
569}
570
571/*
572 * Write out one revoke record. We need to create a new descriptor
573 * block if the old one is full or if we have not already created one.
574 */
575
576static void write_one_revoke_record(journal_t *journal,
577 transaction_t *transaction,
578 struct list_head *log_bufs,
579 struct buffer_head **descriptorp,
580 int *offsetp,
581 struct jbd2_revoke_record_s *record,
582 int write_op)
583{
584 int csum_size = 0;
585 struct buffer_head *descriptor;
586 int offset;
587 journal_header_t *header;
588
589 /* If we are already aborting, this all becomes a noop. We
590 still need to go round the loop in
591 jbd2_journal_write_revoke_records in order to free all of the
592 revoke records: only the IO to the journal is omitted. */
593 if (is_journal_aborted(journal))
594 return;
595
596 descriptor = *descriptorp;
597 offset = *offsetp;
598
599 /* Do we need to leave space at the end for a checksum? */
600 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
601 csum_size = sizeof(struct jbd2_journal_revoke_tail);
602
603 /* Make sure we have a descriptor with space left for the record */
604 if (descriptor) {
605 if (offset >= journal->j_blocksize - csum_size) {
606 flush_descriptor(journal, descriptor, offset, write_op);
607 descriptor = NULL;
608 }
609 }
610
611 if (!descriptor) {
612 descriptor = jbd2_journal_get_descriptor_buffer(journal);
613 if (!descriptor)
614 return;
615 header = (journal_header_t *)descriptor->b_data;
616 header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
617 header->h_blocktype = cpu_to_be32(JBD2_REVOKE_BLOCK);
618 header->h_sequence = cpu_to_be32(transaction->t_tid);
619
620 /* Record it so that we can wait for IO completion later */
621 BUFFER_TRACE(descriptor, "file in log_bufs");
622 jbd2_file_log_bh(log_bufs, descriptor);
623
624 offset = sizeof(jbd2_journal_revoke_header_t);
625 *descriptorp = descriptor;
626 }
627
628 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) {
629 * ((__be64 *)(&descriptor->b_data[offset])) =
630 cpu_to_be64(record->blocknr);
631 offset += 8;
632
633 } else {
634 * ((__be32 *)(&descriptor->b_data[offset])) =
635 cpu_to_be32(record->blocknr);
636 offset += 4;
637 }
638
639 *offsetp = offset;
640}
641
642static void jbd2_revoke_csum_set(journal_t *j, struct buffer_head *bh)
643{
644 struct jbd2_journal_revoke_tail *tail;
645 __u32 csum;
646
647 if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
648 return;
649
650 tail = (struct jbd2_journal_revoke_tail *)(bh->b_data + j->j_blocksize -
651 sizeof(struct jbd2_journal_revoke_tail));
652 tail->r_checksum = 0;
653 csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
654 tail->r_checksum = cpu_to_be32(csum);
655}
656
657/*
658 * Flush a revoke descriptor out to the journal. If we are aborting,
659 * this is a noop; otherwise we are generating a buffer which needs to
660 * be waited for during commit, so it has to go onto the appropriate
661 * journal buffer list.
662 */
663
664static void flush_descriptor(journal_t *journal,
665 struct buffer_head *descriptor,
666 int offset, int write_op)
667{
668 jbd2_journal_revoke_header_t *header;
669
670 if (is_journal_aborted(journal)) {
671 put_bh(descriptor);
672 return;
673 }
674
675 header = (jbd2_journal_revoke_header_t *)descriptor->b_data;
676 header->r_count = cpu_to_be32(offset);
677 jbd2_revoke_csum_set(journal, descriptor);
678
679 set_buffer_jwrite(descriptor);
680 BUFFER_TRACE(descriptor, "write");
681 set_buffer_dirty(descriptor);
682 write_dirty_buffer(descriptor, write_op);
683}
684#endif
685
686/*
687 * Revoke support for recovery.
688 *
689 * Recovery needs to be able to:
690 *
691 * record all revoke records, including the tid of the latest instance
692 * of each revoke in the journal
693 *
694 * check whether a given block in a given transaction should be replayed
695 * (ie. has not been revoked by a revoke record in that or a subsequent
696 * transaction)
697 *
698 * empty the revoke table after recovery.
699 */
700
701/*
702 * First, setting revoke records. We create a new revoke record for
703 * every block ever revoked in the log as we scan it for recovery, and
704 * we update the existing records if we find multiple revokes for a
705 * single block.
706 */
707
708int jbd2_journal_set_revoke(journal_t *journal,
709 unsigned long long blocknr,
710 tid_t sequence)
711{
712 struct jbd2_revoke_record_s *record;
713
714 record = find_revoke_record(journal, blocknr);
715 if (record) {
716 /* If we have multiple occurrences, only record the
717 * latest sequence number in the hashed record */
718 if (tid_gt(sequence, record->sequence))
719 record->sequence = sequence;
720 return 0;
721 }
722 return insert_revoke_hash(journal, blocknr, sequence);
723}
724
725/*
726 * Test revoke records. For a given block referenced in the log, has
727 * that block been revoked? A revoke record with a given transaction
728 * sequence number revokes all blocks in that transaction and earlier
729 * ones, but later transactions still need replayed.
730 */
731
732int jbd2_journal_test_revoke(journal_t *journal,
733 unsigned long long blocknr,
734 tid_t sequence)
735{
736 struct jbd2_revoke_record_s *record;
737
738 record = find_revoke_record(journal, blocknr);
739 if (!record)
740 return 0;
741 if (tid_gt(sequence, record->sequence))
742 return 0;
743 return 1;
744}
745
746/*
747 * Finally, once recovery is over, we need to clear the revoke table so
748 * that it can be reused by the running filesystem.
749 */
750
751void jbd2_journal_clear_revoke(journal_t *journal)
752{
753 int i;
754 struct list_head *hash_list;
755 struct jbd2_revoke_record_s *record;
756 struct jbd2_revoke_table_s *revoke;
757
758 revoke = journal->j_revoke;
759
760 for (i = 0; i < revoke->hash_size; i++) {
761 hash_list = &revoke->hash_table[i];
762 while (!list_empty(hash_list)) {
763 record = (struct jbd2_revoke_record_s*) hash_list->next;
764 list_del(&record->hash);
765 kmem_cache_free(jbd2_revoke_record_cache, record);
766 }
767 }
768}