Line data Source code
1 : /*
2 : * linux/fs/jbd/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 : * Revoke information on buffers is a tri-state value:
51 : *
52 : * RevokeValid clear: no cached revoke status, need to look it up
53 : * RevokeValid set, Revoked clear:
54 : * buffer has not been revoked, and cancel_revoke
55 : * need do nothing.
56 : * RevokeValid set, Revoked set:
57 : * buffer has been revoked.
58 : *
59 : * Locking rules:
60 : * We keep two hash tables of revoke records. One hashtable belongs to the
61 : * running transaction (is pointed to by journal->j_revoke), the other one
62 : * belongs to the committing transaction. Accesses to the second hash table
63 : * happen only from the kjournald and no other thread touches this table. Also
64 : * journal_switch_revoke_table() which switches which hashtable belongs to the
65 : * running and which to the committing transaction is called only from
66 : * kjournald. Therefore we need no locks when accessing the hashtable belonging
67 : * to the committing transaction.
68 : *
69 : * All users operating on the hash table belonging to the running transaction
70 : * have a handle to the transaction. Therefore they are safe from kjournald
71 : * switching hash tables under them. For operations on the lists of entries in
72 : * the hash table j_revoke_lock is used.
73 : *
74 : * Finally, also replay code uses the hash tables but at this moment noone else
75 : * can touch them (filesystem isn't mounted yet) and hence no locking is
76 : * needed.
77 : */
78 :
79 : #ifndef __KERNEL__
80 : #include "jfs_user.h"
81 : #else
82 : #include <linux/time.h>
83 : #include <linux/fs.h>
84 : #include <linux/jbd.h>
85 : #include <linux/errno.h>
86 : #include <linux/slab.h>
87 : #include <linux/list.h>
88 : #include <linux/init.h>
89 : #include <linux/bio.h>
90 : #endif
91 : #include <linux/log2.h>
92 :
93 1 : static struct kmem_cache *revoke_record_cache;
94 1 : static struct kmem_cache *revoke_table_cache;
95 1 :
96 : /* Each revoke record represents one single revoked block. During
97 : journal replay, this involves recording the transaction ID of the
98 : last transaction to revoke this block. */
99 :
100 : struct jbd_revoke_record_s
101 : {
102 : struct list_head hash;
103 : tid_t sequence; /* Used for recovery only */
104 : unsigned int blocknr;
105 : };
106 1 :
107 :
108 : /* The revoke table is just a simple hash table of revoke records. */
109 : struct jbd_revoke_table_s
110 : {
111 : /* It is conceivable that we might want a larger hash table
112 : * for recovery. Must be a power of two. */
113 : int hash_size;
114 : int hash_shift;
115 : struct list_head *hash_table;
116 : };
117 :
118 :
119 : #ifdef __KERNEL__
120 : static void write_one_revoke_record(journal_t *, transaction_t *,
121 : struct journal_head **, int *,
122 : struct jbd_revoke_record_s *, int);
123 : static void flush_descriptor(journal_t *, struct journal_head *, int, int);
124 : #endif
125 :
126 : /* Utility functions to maintain the revoke table */
127 :
128 : /* Borrowed from buffer.c: this is a tried and tested block hash function */
129 : static inline int hash(journal_t *journal, unsigned int block)
130 : {
131 0 : struct jbd_revoke_table_s *table = journal->j_revoke;
132 0 : int hash_shift = table->hash_shift;
133 :
134 0 : return ((block << (hash_shift - 6)) ^
135 : (block >> 13) ^
136 : (block << (hash_shift - 12))) & (table->hash_size - 1);
137 : }
138 :
139 : static int insert_revoke_hash(journal_t *journal, unsigned int blocknr,
140 : tid_t seq)
141 0 : {
142 0 : struct list_head *hash_list;
143 0 : struct jbd_revoke_record_s *record;
144 0 :
145 : repeat:
146 0 : record = kmem_cache_alloc(revoke_record_cache, GFP_NOFS);
147 0 : if (!record)
148 0 : goto oom;
149 :
150 0 : record->sequence = seq;
151 0 : record->blocknr = blocknr;
152 0 : hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
153 0 : spin_lock(&journal->j_revoke_lock);
154 0 : list_add(&record->hash, hash_list);
155 0 : spin_unlock(&journal->j_revoke_lock);
156 0 : return 0;
157 0 :
158 : oom:
159 : if (!journal_oom_retry)
160 : return -ENOMEM;
161 : jbd_debug(1, "ENOMEM in %s, retrying\n", __func__);
162 0 : yield();
163 0 : goto repeat;
164 : }
165 :
166 : /* Find a revoke record in the journal's hash table. */
167 :
168 : static struct jbd_revoke_record_s *find_revoke_record(journal_t *journal,
169 : unsigned int blocknr)
170 0 : {
171 0 : struct list_head *hash_list;
172 0 : struct jbd_revoke_record_s *record;
173 :
174 0 : hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
175 :
176 0 : spin_lock(&journal->j_revoke_lock);
177 0 : record = (struct jbd_revoke_record_s *) hash_list->next;
178 0 : while (&(record->hash) != hash_list) {
179 0 : if (record->blocknr == blocknr) {
180 0 : spin_unlock(&journal->j_revoke_lock);
181 0 : return record;
182 : }
183 0 : record = (struct jbd_revoke_record_s *) record->hash.next;
184 0 : }
185 0 : spin_unlock(&journal->j_revoke_lock);
186 0 : return NULL;
187 : }
188 :
189 : void journal_destroy_revoke_caches(void)
190 : {
191 8 : if (revoke_record_cache) {
192 4 : kmem_cache_destroy(revoke_record_cache);
193 4 : revoke_record_cache = NULL;
194 : }
195 8 : if (revoke_table_cache) {
196 4 : kmem_cache_destroy(revoke_table_cache);
197 4 : revoke_table_cache = NULL;
198 : }
199 4 : }
200 :
201 : int __init journal_init_revoke_caches(void)
202 : {
203 7 : J_ASSERT(!revoke_record_cache);
204 7 : J_ASSERT(!revoke_table_cache);
205 :
206 1 : revoke_record_cache = kmem_cache_create("revoke_record",
207 : sizeof(struct jbd_revoke_record_s),
208 : 0,
209 : SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY,
210 : NULL);
211 2 : if (!revoke_record_cache)
212 1 : goto record_cache_failure;
213 :
214 1 : revoke_table_cache = kmem_cache_create("revoke_table",
215 : sizeof(struct jbd_revoke_table_s),
216 : 0, SLAB_TEMPORARY, NULL);
217 2 : if (!revoke_table_cache)
218 1 : goto table_cache_failure;
219 :
220 1 : return 0;
221 1 :
222 : table_cache_failure:
223 2 : journal_destroy_revoke_caches();
224 : record_cache_failure:
225 3 : return -ENOMEM;
226 : }
227 :
228 : static struct jbd_revoke_table_s *journal_init_revoke_table(int hash_size)
229 : {
230 0 : int shift = 0;
231 0 : int tmp = hash_size;
232 0 : struct jbd_revoke_table_s *table;
233 0 :
234 0 : table = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL);
235 0 : if (!table)
236 0 : goto out;
237 :
238 0 : while((tmp >>= 1UL) != 0UL)
239 0 : shift++;
240 0 :
241 0 : table->hash_size = hash_size;
242 0 : table->hash_shift = shift;
243 0 : table->hash_table =
244 : kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
245 0 : if (!table->hash_table) {
246 0 : kmem_cache_free(revoke_table_cache, table);
247 0 : table = NULL;
248 0 : goto out;
249 : }
250 :
251 0 : for (tmp = 0; tmp < hash_size; tmp++)
252 0 : INIT_LIST_HEAD(&table->hash_table[tmp]);
253 0 :
254 : out:
255 0 : return table;
256 : }
257 :
258 0 : static void journal_destroy_revoke_table(struct jbd_revoke_table_s *table)
259 : {
260 0 : int i;
261 0 : struct list_head *hash_list;
262 0 :
263 0 : for (i = 0; i < table->hash_size; i++) {
264 0 : hash_list = &table->hash_table[i];
265 0 : J_ASSERT(list_empty(hash_list));
266 : }
267 :
268 0 : kfree(table->hash_table);
269 0 : kmem_cache_free(revoke_table_cache, table);
270 0 : }
271 :
272 : /* Initialise the revoke table for a given journal to a given size. */
273 : int journal_init_revoke(journal_t *journal, int hash_size)
274 : {
275 0 : J_ASSERT(journal->j_revoke_table[0] == NULL);
276 0 : J_ASSERT(is_power_of_2(hash_size));
277 0 :
278 0 : journal->j_revoke_table[0] = journal_init_revoke_table(hash_size);
279 0 : if (!journal->j_revoke_table[0])
280 0 : goto fail0;
281 :
282 0 : journal->j_revoke_table[1] = journal_init_revoke_table(hash_size);
283 0 : if (!journal->j_revoke_table[1])
284 0 : goto fail1;
285 :
286 0 : journal->j_revoke = journal->j_revoke_table[1];
287 :
288 0 : spin_lock_init(&journal->j_revoke_lock);
289 :
290 0 : return 0;
291 0 :
292 : fail1:
293 0 : journal_destroy_revoke_table(journal->j_revoke_table[0]);
294 : fail0:
295 0 : return -ENOMEM;
296 : }
297 :
298 : /* Destroy a journal's revoke table. The table must already be empty! */
299 : void journal_destroy_revoke(journal_t *journal)
300 : {
301 0 : journal->j_revoke = NULL;
302 0 : if (journal->j_revoke_table[0])
303 0 : journal_destroy_revoke_table(journal->j_revoke_table[0]);
304 0 : if (journal->j_revoke_table[1])
305 0 : journal_destroy_revoke_table(journal->j_revoke_table[1]);
306 0 : }
307 :
308 :
309 : #ifdef __KERNEL__
310 :
311 : /*
312 : * 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 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, journal_revoke() will decrement its b_count
332 : * by one.
333 : */
334 :
335 : int journal_revoke(handle_t *handle, unsigned int blocknr,
336 : struct buffer_head *bh_in)
337 0 : {
338 0 : struct buffer_head *bh = NULL;
339 0 : journal_t *journal;
340 0 : struct block_device *bdev;
341 0 : int err;
342 0 :
343 0 : might_sleep();
344 : if (bh_in)
345 : BUFFER_TRACE(bh_in, "enter");
346 :
347 0 : journal = handle->h_transaction->t_journal;
348 0 : if (!journal_set_features(journal, 0, 0, JFS_FEATURE_INCOMPAT_REVOKE)){
349 0 : J_ASSERT (!"Cannot set revoke feature!");
350 0 : return -EINVAL;
351 : }
352 :
353 0 : bdev = journal->j_fs_dev;
354 0 : bh = bh_in;
355 :
356 0 : if (!bh) {
357 0 : bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
358 : if (bh)
359 : BUFFER_TRACE(bh, "found on hash");
360 : }
361 : #ifdef JBD_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 0 : if (bh) {
387 0 : if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
388 : "inconsistent data on disk")) {
389 0 : if (!bh_in)
390 0 : brelse(bh);
391 0 : return -EIO;
392 : }
393 0 : set_buffer_revoked(bh);
394 0 : set_buffer_revokevalid(bh);
395 0 : if (bh_in) {
396 : BUFFER_TRACE(bh_in, "call journal_forget");
397 0 : journal_forget(handle, bh_in);
398 : } else {
399 : BUFFER_TRACE(bh, "call brelse");
400 0 : __brelse(bh);
401 : }
402 : }
403 :
404 : jbd_debug(2, "insert revoke for block %u, bh_in=%p\n", blocknr, bh_in);
405 0 : err = insert_revoke_hash(journal, blocknr,
406 : handle->h_transaction->t_tid);
407 : BUFFER_TRACE(bh_in, "exit");
408 0 : return err;
409 : }
410 :
411 : /*
412 : * Cancel an outstanding revoke. For use only internally by the
413 : * journaling code (called from 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 : */
426 : int journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
427 : {
428 0 : struct jbd_revoke_record_s *record;
429 0 : journal_t *journal = handle->h_transaction->t_journal;
430 0 : int need_cancel;
431 0 : int did_revoke = 0; /* akpm: debug */
432 0 : struct buffer_head *bh = jh2bh(jh);
433 0 :
434 0 : jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
435 0 :
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 0 : if (test_set_buffer_revokevalid(bh)) {
441 0 : need_cancel = test_clear_buffer_revoked(bh);
442 : } else {
443 0 : need_cancel = 1;
444 0 : clear_buffer_revoked(bh);
445 : }
446 :
447 0 : if (need_cancel) {
448 0 : record = find_revoke_record(journal, bh->b_blocknr);
449 0 : if (record) {
450 : jbd_debug(4, "cancelled existing revoke on "
451 : "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
452 0 : spin_lock(&journal->j_revoke_lock);
453 0 : list_del(&record->hash);
454 0 : spin_unlock(&journal->j_revoke_lock);
455 0 : kmem_cache_free(revoke_record_cache, record);
456 0 : did_revoke = 1;
457 : }
458 : }
459 :
460 : #ifdef JBD_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 0 : if (need_cancel) {
471 : struct buffer_head *bh2;
472 0 : bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
473 0 : if (bh2) {
474 0 : if (bh2 != bh)
475 0 : clear_buffer_revoked(bh2);
476 0 : __brelse(bh2);
477 : }
478 : }
479 0 : return did_revoke;
480 : }
481 :
482 : /* journal_switch_revoke table select j_revoke for next transaction
483 : * we do not want to suspend any processing until all revokes are
484 : * written -bzzz
485 : */
486 : void journal_switch_revoke_table(journal_t *journal)
487 : {
488 0 : int i;
489 :
490 0 : if (journal->j_revoke == journal->j_revoke_table[0])
491 0 : journal->j_revoke = journal->j_revoke_table[1];
492 : else
493 0 : journal->j_revoke = journal->j_revoke_table[0];
494 :
495 0 : for (i = 0; i < journal->j_revoke->hash_size; i++)
496 0 : INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
497 0 : }
498 :
499 : /*
500 : * Write revoke records to the journal for all entries in the current
501 : * revoke hash, deleting the entries as we go.
502 0 : */
503 : void journal_write_revoke_records(journal_t *journal,
504 : transaction_t *transaction, int write_op)
505 : {
506 0 : struct journal_head *descriptor;
507 0 : struct jbd_revoke_record_s *record;
508 0 : struct jbd_revoke_table_s *revoke;
509 0 : struct list_head *hash_list;
510 0 : int i, offset, count;
511 0 :
512 0 : descriptor = NULL;
513 0 : offset = 0;
514 0 : count = 0;
515 :
516 : /* select revoke table for committing transaction */
517 0 : revoke = journal->j_revoke == journal->j_revoke_table[0] ?
518 : journal->j_revoke_table[1] : journal->j_revoke_table[0];
519 :
520 0 : for (i = 0; i < revoke->hash_size; i++) {
521 0 : hash_list = &revoke->hash_table[i];
522 0 :
523 0 : while (!list_empty(hash_list)) {
524 0 : record = (struct jbd_revoke_record_s *)
525 0 : hash_list->next;
526 0 : write_one_revoke_record(journal, transaction,
527 : &descriptor, &offset,
528 : record, write_op);
529 0 : count++;
530 0 : list_del(&record->hash);
531 0 : kmem_cache_free(revoke_record_cache, record);
532 : }
533 0 : }
534 0 : if (descriptor)
535 0 : flush_descriptor(journal, descriptor, offset, write_op);
536 0 : jbd_debug(1, "Wrote %d revoke records\n", count);
537 : }
538 :
539 : /*
540 : * Write out one revoke record. We need to create a new descriptor
541 : * block if the old one is full or if we have not already created one.
542 : */
543 :
544 : static void write_one_revoke_record(journal_t *journal,
545 : transaction_t *transaction,
546 : struct journal_head **descriptorp,
547 : int *offsetp,
548 0 : struct jbd_revoke_record_s *record,
549 0 : int write_op)
550 0 : {
551 0 : struct journal_head *descriptor;
552 0 : int offset;
553 0 : journal_header_t *header;
554 0 :
555 0 : /* If we are already aborting, this all becomes a noop. We
556 : still need to go round the loop in
557 : journal_write_revoke_records in order to free all of the
558 : revoke records: only the IO to the journal is omitted. */
559 0 : if (is_journal_aborted(journal))
560 0 : return;
561 :
562 0 : descriptor = *descriptorp;
563 0 : offset = *offsetp;
564 :
565 : /* Make sure we have a descriptor with space left for the record */
566 0 : if (descriptor) {
567 0 : if (offset == journal->j_blocksize) {
568 0 : flush_descriptor(journal, descriptor, offset, write_op);
569 0 : descriptor = NULL;
570 : }
571 : }
572 :
573 0 : if (!descriptor) {
574 0 : descriptor = journal_get_descriptor_buffer(journal);
575 0 : if (!descriptor)
576 0 : return;
577 0 : header = (journal_header_t *) &jh2bh(descriptor)->b_data[0];
578 0 : header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
579 0 : header->h_blocktype = cpu_to_be32(JFS_REVOKE_BLOCK);
580 0 : header->h_sequence = cpu_to_be32(transaction->t_tid);
581 :
582 : /* Record it so that we can wait for IO completion later */
583 : JBUFFER_TRACE(descriptor, "file as BJ_LogCtl");
584 0 : journal_file_buffer(descriptor, transaction, BJ_LogCtl);
585 :
586 0 : offset = sizeof(journal_revoke_header_t);
587 0 : *descriptorp = descriptor;
588 : }
589 :
590 0 : * ((__be32 *)(&jh2bh(descriptor)->b_data[offset])) =
591 : cpu_to_be32(record->blocknr);
592 0 : offset += 4;
593 0 : *offsetp = offset;
594 0 : }
595 :
596 : /*
597 : * Flush a revoke descriptor out to the journal. If we are aborting,
598 : * this is a noop; otherwise we are generating a buffer which needs to
599 : * be waited for during commit, so it has to go onto the appropriate
600 : * journal buffer list.
601 : */
602 :
603 : static void flush_descriptor(journal_t *journal,
604 : struct journal_head *descriptor,
605 : int offset, int write_op)
606 0 : {
607 0 : journal_revoke_header_t *header;
608 0 : struct buffer_head *bh = jh2bh(descriptor);
609 0 :
610 0 : if (is_journal_aborted(journal)) {
611 0 : put_bh(bh);
612 0 : return;
613 : }
614 :
615 0 : header = (journal_revoke_header_t *) jh2bh(descriptor)->b_data;
616 0 : header->r_count = cpu_to_be32(offset);
617 0 : set_buffer_jwrite(bh);
618 : BUFFER_TRACE(bh, "write");
619 0 : set_buffer_dirty(bh);
620 0 : ll_rw_block((write_op == WRITE) ? SWRITE : SWRITE_SYNC_PLUG, 1, &bh);
621 0 : }
622 : #endif
623 :
624 : /*
625 : * Revoke support for recovery.
626 : *
627 : * Recovery needs to be able to:
628 : *
629 : * record all revoke records, including the tid of the latest instance
630 : * of each revoke in the journal
631 : *
632 : * check whether a given block in a given transaction should be replayed
633 : * (ie. has not been revoked by a revoke record in that or a subsequent
634 : * transaction)
635 : *
636 : * empty the revoke table after recovery.
637 : */
638 :
639 : /*
640 : * First, setting revoke records. We create a new revoke record for
641 : * every block ever revoked in the log as we scan it for recovery, and
642 : * we update the existing records if we find multiple revokes for a
643 : * single block.
644 : */
645 :
646 : int journal_set_revoke(journal_t *journal,
647 : unsigned int blocknr,
648 0 : tid_t sequence)
649 0 : {
650 0 : struct jbd_revoke_record_s *record;
651 :
652 0 : record = find_revoke_record(journal, blocknr);
653 0 : if (record) {
654 : /* If we have multiple occurrences, only record the
655 : * latest sequence number in the hashed record */
656 0 : if (tid_gt(sequence, record->sequence))
657 0 : record->sequence = sequence;
658 0 : return 0;
659 : }
660 0 : return insert_revoke_hash(journal, blocknr, sequence);
661 : }
662 :
663 : /*
664 : * Test revoke records. For a given block referenced in the log, has
665 : * that block been revoked? A revoke record with a given transaction
666 : * sequence number revokes all blocks in that transaction and earlier
667 : * ones, but later transactions still need replayed.
668 : */
669 :
670 : int journal_test_revoke(journal_t *journal,
671 : unsigned int blocknr,
672 0 : tid_t sequence)
673 0 : {
674 : struct jbd_revoke_record_s *record;
675 :
676 0 : record = find_revoke_record(journal, blocknr);
677 0 : if (!record)
678 0 : return 0;
679 0 : if (tid_gt(sequence, record->sequence))
680 0 : return 0;
681 0 : return 1;
682 : }
683 :
684 : /*
685 : * Finally, once recovery is over, we need to clear the revoke table so
686 : * that it can be reused by the running filesystem.
687 : */
688 :
689 : void journal_clear_revoke(journal_t *journal)
690 : {
691 0 : int i;
692 0 : struct list_head *hash_list;
693 0 : struct jbd_revoke_record_s *record;
694 0 : struct jbd_revoke_table_s *revoke;
695 0 :
696 0 : revoke = journal->j_revoke;
697 :
698 0 : for (i = 0; i < revoke->hash_size; i++) {
699 0 : hash_list = &revoke->hash_table[i];
700 0 : while (!list_empty(hash_list)) {
701 0 : record = (struct jbd_revoke_record_s*) hash_list->next;
702 0 : list_del(&record->hash);
703 0 : kmem_cache_free(revoke_record_cache, record);
704 : }
705 0 : }
706 : }
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