1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * linux/fs/jbd2/revoke.c
4  *
5  * Written by Stephen C. Tweedie <sct@redhat.com>, 2000
6  *
7  * Copyright 2000 Red Hat corp --- All Rights Reserved
8  *
9  * Journal revoke routines for the generic filesystem journaling code;
10  * part of the ext2fs journaling system.
11  *
12  * Revoke is the mechanism used to prevent old log records for deleted
13  * metadata from being replayed on top of newer data using the same
14  * blocks.  The revoke mechanism is used in two separate places:
15  *
16  * + Commit: during commit we write the entire list of the current
17  *   transaction's revoked blocks to the journal
18  *
19  * + Recovery: during recovery we record the transaction ID of all
20  *   revoked blocks.  If there are multiple revoke records in the log
21  *   for a single block, only the last one counts, and if there is a log
22  *   entry for a block beyond the last revoke, then that log entry still
23  *   gets replayed.
24  *
25  * We can get interactions between revokes and new log data within a
26  * single transaction:
27  *
28  * Block is revoked and then journaled:
29  *   The desired end result is the journaling of the new block, so we
30  *   cancel the revoke before the transaction commits.
31  *
32  * Block is journaled and then revoked:
33  *   The revoke must take precedence over the write of the block, so we
34  *   need either to cancel the journal entry or to write the revoke
35  *   later in the log than the log block.  In this case, we choose the
36  *   latter: journaling a block cancels any revoke record for that block
37  *   in the current transaction, so any revoke for that block in the
38  *   transaction must have happened after the block was journaled and so
39  *   the revoke must take precedence.
40  *
41  * Block is revoked and then written as data:
42  *   The data write is allowed to succeed, but the revoke is _not_
43  *   cancelled.  We still need to prevent old log records from
44  *   overwriting the new data.  We don't even need to clear the revoke
45  *   bit here.
46  *
47  * We cache revoke status of a buffer in the current transaction in b_states
48  * bits.  As the name says, revokevalid flag indicates that the cached revoke
49  * status of a buffer is valid and we can rely on the cached status.
50  *
51  * Revoke information on buffers is a tri-state value:
52  *
53  * RevokeValid clear:	no cached revoke status, need to look it up
54  * RevokeValid set, Revoked clear:
55  *			buffer has not been revoked, and cancel_revoke
56  *			need do nothing.
57  * RevokeValid set, Revoked set:
58  *			buffer has been revoked.
59  *
60  * Locking rules:
61  * We keep two hash tables of revoke records. One hashtable belongs to the
62  * running transaction (is pointed to by journal->j_revoke), the other one
63  * belongs to the committing transaction. Accesses to the second hash table
64  * happen only from the kjournald and no other thread touches this table.  Also
65  * journal_switch_revoke_table() which switches which hashtable belongs to the
66  * running and which to the committing transaction is called only from
67  * kjournald. Therefore we need no locks when accessing the hashtable belonging
68  * to the committing transaction.
69  *
70  * All users operating on the hash table belonging to the running transaction
71  * have a handle to the transaction. Therefore they are safe from kjournald
72  * switching hash tables under them. For operations on the lists of entries in
73  * the hash table j_revoke_lock is used.
74  *
75  * Finally, also replay code uses the hash tables but at this moment no one else
76  * can touch them (filesystem isn't mounted yet) and hence no locking is
77  * needed.
78  */
79 
80 #ifndef __KERNEL__
81 #include "jfs_user.h"
82 #else
83 #include <linux/time.h>
84 #include <linux/fs.h>
85 #include <linux/jbd2.h>
86 #include <linux/errno.h>
87 #include <linux/slab.h>
88 #include <linux/list.h>
89 #include <linux/init.h>
90 #include <linux/bio.h>
91 #include <linux/log2.h>
92 #include <linux/hash.h>
93 #endif
94 
95 static struct kmem_cache *jbd2_revoke_record_cache;
96 static struct kmem_cache *jbd2_revoke_table_cache;
97 
98 /* Each revoke record represents one single revoked block.  During
99    journal replay, this involves recording the transaction ID of the
100    last transaction to revoke this block. */
101 
102 struct jbd2_revoke_record_s
103 {
104 	struct list_head  hash;
105 	tid_t		  sequence;	/* Used for recovery only */
106 	unsigned long long	  blocknr;
107 };
108 
109 
110 /* The revoke table is just a simple hash table of revoke records. */
111 struct jbd2_revoke_table_s
112 {
113 	/* It is conceivable that we might want a larger hash table
114 	 * for recovery.  Must be a power of two. */
115 	int		  hash_size;
116 	int		  hash_shift;
117 	struct list_head *hash_table;
118 };
119 
120 
121 #ifdef __KERNEL__
122 static void write_one_revoke_record(transaction_t *,
123 				    struct list_head *,
124 				    struct buffer_head **, int *,
125 				    struct jbd2_revoke_record_s *);
126 static void flush_descriptor(journal_t *, struct buffer_head *, int);
127 #endif
128 
129 /* Utility functions to maintain the revoke table */
130 
hash(journal_t * journal,unsigned long long block)131 static inline int hash(journal_t *journal, unsigned long long block)
132 {
133 	return hash_64(block, journal->j_revoke->hash_shift);
134 }
135 
insert_revoke_hash(journal_t * journal,unsigned long long blocknr,tid_t seq)136 static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
137 			      tid_t seq)
138 {
139 	struct list_head *hash_list;
140 	struct jbd2_revoke_record_s *record;
141 	gfp_t gfp_mask = GFP_NOFS;
142 
143 	if (journal_oom_retry)
144 		gfp_mask |= __GFP_NOFAIL;
145 	record = kmem_cache_alloc(jbd2_revoke_record_cache, gfp_mask);
146 	if (!record)
147 		return -ENOMEM;
148 
149 	record->sequence = seq;
150 	record->blocknr = blocknr;
151 	hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
152 	spin_lock(&journal->j_revoke_lock);
153 	list_add(&record->hash, hash_list);
154 	spin_unlock(&journal->j_revoke_lock);
155 	return 0;
156 }
157 
158 /* Find a revoke record in the journal's hash table. */
159 
find_revoke_record(journal_t * journal,unsigned long long blocknr)160 static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
161 						      unsigned long long blocknr)
162 {
163 	struct list_head *hash_list;
164 	struct jbd2_revoke_record_s *record;
165 
166 	hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
167 
168 	spin_lock(&journal->j_revoke_lock);
169 	record = (struct jbd2_revoke_record_s *) hash_list->next;
170 	while (&(record->hash) != hash_list) {
171 		if (record->blocknr == blocknr) {
172 			spin_unlock(&journal->j_revoke_lock);
173 			return record;
174 		}
175 		record = (struct jbd2_revoke_record_s *) record->hash.next;
176 	}
177 	spin_unlock(&journal->j_revoke_lock);
178 	return NULL;
179 }
180 
jbd2_journal_destroy_revoke_record_cache(void)181 void jbd2_journal_destroy_revoke_record_cache(void)
182 {
183 	kmem_cache_destroy(jbd2_revoke_record_cache);
184 	jbd2_revoke_record_cache = NULL;
185 }
186 
jbd2_journal_destroy_revoke_table_cache(void)187 void jbd2_journal_destroy_revoke_table_cache(void)
188 {
189 	kmem_cache_destroy(jbd2_revoke_table_cache);
190 	jbd2_revoke_table_cache = NULL;
191 }
192 
jbd2_journal_init_revoke_record_cache(void)193 int __init jbd2_journal_init_revoke_record_cache(void)
194 {
195 	J_ASSERT(!jbd2_revoke_record_cache);
196 	jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s,
197 					SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY);
198 
199 	if (!jbd2_revoke_record_cache) {
200 		pr_emerg("JBD2: failed to create revoke_record cache\n");
201 		return -ENOMEM;
202 	}
203 	return 0;
204 }
205 
jbd2_journal_init_revoke_table_cache(void)206 int __init jbd2_journal_init_revoke_table_cache(void)
207 {
208 	J_ASSERT(!jbd2_revoke_table_cache);
209 	jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s,
210 					     SLAB_TEMPORARY);
211 	if (!jbd2_revoke_table_cache) {
212 		pr_emerg("JBD2: failed to create revoke_table cache\n");
213 		return -ENOMEM;
214 	}
215 	return 0;
216 }
217 
jbd2_journal_init_revoke_table(int hash_size)218 static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size)
219 {
220 	int shift = 0;
221 	int tmp = hash_size;
222 	struct jbd2_revoke_table_s *table;
223 
224 	table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
225 	if (!table)
226 		goto out;
227 
228 	while((tmp >>= 1UL) != 0UL)
229 		shift++;
230 
231 	table->hash_size = hash_size;
232 	table->hash_shift = shift;
233 	table->hash_table =
234 		kmalloc_array(hash_size, sizeof(struct list_head), GFP_KERNEL);
235 	if (!table->hash_table) {
236 		kmem_cache_free(jbd2_revoke_table_cache, table);
237 		table = NULL;
238 		goto out;
239 	}
240 
241 	for (tmp = 0; tmp < hash_size; tmp++)
242 		INIT_LIST_HEAD(&table->hash_table[tmp]);
243 
244 out:
245 	return table;
246 }
247 
jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s * table)248 static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table)
249 {
250 	int i;
251 	struct list_head *hash_list;
252 
253 	for (i = 0; i < table->hash_size; i++) {
254 		hash_list = &table->hash_table[i];
255 		J_ASSERT(list_empty(hash_list));
256 	}
257 
258 	kfree(table->hash_table);
259 	kmem_cache_free(jbd2_revoke_table_cache, table);
260 }
261 
262 /* Initialise the revoke table for a given journal to a given size. */
jbd2_journal_init_revoke(journal_t * journal,int hash_size)263 int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
264 {
265 	J_ASSERT(journal->j_revoke_table[0] == NULL);
266 	J_ASSERT(is_power_of_2(hash_size));
267 
268 	journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size);
269 	if (!journal->j_revoke_table[0])
270 		goto fail0;
271 
272 	journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size);
273 	if (!journal->j_revoke_table[1])
274 		goto fail1;
275 
276 	journal->j_revoke = journal->j_revoke_table[1];
277 
278 	spin_lock_init(&journal->j_revoke_lock);
279 
280 	return 0;
281 
282 fail1:
283 	jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
284 	journal->j_revoke_table[0] = NULL;
285 fail0:
286 	return -ENOMEM;
287 }
288 
289 /* Destroy a journal's revoke table.  The table must already be empty! */
jbd2_journal_destroy_revoke(journal_t * journal)290 void jbd2_journal_destroy_revoke(journal_t *journal)
291 {
292 	journal->j_revoke = NULL;
293 	if (journal->j_revoke_table[0])
294 		jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
295 	if (journal->j_revoke_table[1])
296 		jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]);
297 }
298 
299 
300 #ifdef __KERNEL__
301 
302 /*
303  * jbd2_journal_revoke: revoke a given buffer_head from the journal.  This
304  * prevents the block from being replayed during recovery if we take a
305  * crash after this current transaction commits.  Any subsequent
306  * metadata writes of the buffer in this transaction cancel the
307  * revoke.
308  *
309  * Note that this call may block --- it is up to the caller to make
310  * sure that there are no further calls to journal_write_metadata
311  * before the revoke is complete.  In ext3, this implies calling the
312  * revoke before clearing the block bitmap when we are deleting
313  * metadata.
314  *
315  * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
316  * parameter, but does _not_ forget the buffer_head if the bh was only
317  * found implicitly.
318  *
319  * bh_in may not be a journalled buffer - it may have come off
320  * the hash tables without an attached journal_head.
321  *
322  * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
323  * by one.
324  */
325 
jbd2_journal_revoke(handle_t * handle,unsigned long long blocknr,struct buffer_head * bh_in)326 int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
327 		   struct buffer_head *bh_in)
328 {
329 	struct buffer_head *bh = NULL;
330 	journal_t *journal;
331 	struct block_device *bdev;
332 	int err;
333 
334 	might_sleep();
335 	if (bh_in)
336 		BUFFER_TRACE(bh_in, "enter");
337 
338 	journal = handle->h_transaction->t_journal;
339 	if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
340 		J_ASSERT (!"Cannot set revoke feature!");
341 		return -EINVAL;
342 	}
343 
344 	bdev = journal->j_fs_dev;
345 	bh = bh_in;
346 
347 	if (!bh) {
348 		bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
349 		if (bh)
350 			BUFFER_TRACE(bh, "found on hash");
351 	}
352 #ifdef JBD2_EXPENSIVE_CHECKING
353 	else {
354 		struct buffer_head *bh2;
355 
356 		/* If there is a different buffer_head lying around in
357 		 * memory anywhere... */
358 		bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
359 		if (bh2) {
360 			/* ... and it has RevokeValid status... */
361 			if (bh2 != bh && buffer_revokevalid(bh2))
362 				/* ...then it better be revoked too,
363 				 * since it's illegal to create a revoke
364 				 * record against a buffer_head which is
365 				 * not marked revoked --- that would
366 				 * risk missing a subsequent revoke
367 				 * cancel. */
368 				J_ASSERT_BH(bh2, buffer_revoked(bh2));
369 			put_bh(bh2);
370 		}
371 	}
372 #endif
373 
374 	if (WARN_ON_ONCE(handle->h_revoke_credits <= 0)) {
375 		if (!bh_in)
376 			brelse(bh);
377 		return -EIO;
378 	}
379 	/* We really ought not ever to revoke twice in a row without
380            first having the revoke cancelled: it's illegal to free a
381            block twice without allocating it in between! */
382 	if (bh) {
383 		if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
384 				 "inconsistent data on disk")) {
385 			if (!bh_in)
386 				brelse(bh);
387 			return -EIO;
388 		}
389 		set_buffer_revoked(bh);
390 		set_buffer_revokevalid(bh);
391 		if (bh_in) {
392 			BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
393 			jbd2_journal_forget(handle, bh_in);
394 		} else {
395 			BUFFER_TRACE(bh, "call brelse");
396 			__brelse(bh);
397 		}
398 	}
399 	handle->h_revoke_credits--;
400 
401 	jbd2_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
402 	err = insert_revoke_hash(journal, blocknr,
403 				handle->h_transaction->t_tid);
404 	BUFFER_TRACE(bh_in, "exit");
405 	return err;
406 }
407 
408 /*
409  * Cancel an outstanding revoke.  For use only internally by the
410  * journaling code (called from jbd2_journal_get_write_access).
411  *
412  * We trust buffer_revoked() on the buffer if the buffer is already
413  * being journaled: if there is no revoke pending on the buffer, then we
414  * don't do anything here.
415  *
416  * This would break if it were possible for a buffer to be revoked and
417  * discarded, and then reallocated within the same transaction.  In such
418  * a case we would have lost the revoked bit, but when we arrived here
419  * the second time we would still have a pending revoke to cancel.  So,
420  * do not trust the Revoked bit on buffers unless RevokeValid is also
421  * set.
422  */
jbd2_journal_cancel_revoke(handle_t * handle,struct journal_head * jh)423 int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
424 {
425 	struct jbd2_revoke_record_s *record;
426 	journal_t *journal = handle->h_transaction->t_journal;
427 	int need_cancel;
428 	int did_revoke = 0;	/* akpm: debug */
429 	struct buffer_head *bh = jh2bh(jh);
430 
431 	jbd2_debug(4, "journal_head %p, cancelling revoke\n", jh);
432 
433 	/* Is the existing Revoke bit valid?  If so, we trust it, and
434 	 * only perform the full cancel if the revoke bit is set.  If
435 	 * not, we can't trust the revoke bit, and we need to do the
436 	 * full search for a revoke record. */
437 	if (test_set_buffer_revokevalid(bh)) {
438 		need_cancel = test_clear_buffer_revoked(bh);
439 	} else {
440 		need_cancel = 1;
441 		clear_buffer_revoked(bh);
442 	}
443 
444 	if (need_cancel) {
445 		record = find_revoke_record(journal, bh->b_blocknr);
446 		if (record) {
447 			jbd2_debug(4, "cancelled existing revoke on "
448 				  "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
449 			spin_lock(&journal->j_revoke_lock);
450 			list_del(&record->hash);
451 			spin_unlock(&journal->j_revoke_lock);
452 			kmem_cache_free(jbd2_revoke_record_cache, record);
453 			did_revoke = 1;
454 		}
455 	}
456 
457 #ifdef JBD2_EXPENSIVE_CHECKING
458 	/* There better not be one left behind by now! */
459 	record = find_revoke_record(journal, bh->b_blocknr);
460 	J_ASSERT_JH(jh, record == NULL);
461 #endif
462 
463 	/* Finally, have we just cleared revoke on an unhashed
464 	 * buffer_head?  If so, we'd better make sure we clear the
465 	 * revoked status on any hashed alias too, otherwise the revoke
466 	 * state machine will get very upset later on. */
467 	if (need_cancel) {
468 		struct buffer_head *bh2;
469 		bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
470 		if (bh2) {
471 			if (bh2 != bh)
472 				clear_buffer_revoked(bh2);
473 			__brelse(bh2);
474 		}
475 	}
476 	return did_revoke;
477 }
478 
479 /*
480  * journal_clear_revoked_flag clears revoked flag of buffers in
481  * revoke table to reflect there is no revoked buffers in the next
482  * transaction which is going to be started.
483  */
jbd2_clear_buffer_revoked_flags(journal_t * journal)484 void jbd2_clear_buffer_revoked_flags(journal_t *journal)
485 {
486 	struct jbd2_revoke_table_s *revoke = journal->j_revoke;
487 	int i = 0;
488 
489 	for (i = 0; i < revoke->hash_size; i++) {
490 		struct list_head *hash_list;
491 		struct list_head *list_entry;
492 		hash_list = &revoke->hash_table[i];
493 
494 		list_for_each(list_entry, hash_list) {
495 			struct jbd2_revoke_record_s *record;
496 			struct buffer_head *bh;
497 			record = (struct jbd2_revoke_record_s *)list_entry;
498 			bh = __find_get_block(journal->j_fs_dev,
499 					      record->blocknr,
500 					      journal->j_blocksize);
501 			if (bh) {
502 				clear_buffer_revoked(bh);
503 				__brelse(bh);
504 			}
505 		}
506 	}
507 }
508 
509 /* journal_switch_revoke table select j_revoke for next transaction
510  * we do not want to suspend any processing until all revokes are
511  * written -bzzz
512  */
jbd2_journal_switch_revoke_table(journal_t * journal)513 void jbd2_journal_switch_revoke_table(journal_t *journal)
514 {
515 	int i;
516 
517 	if (journal->j_revoke == journal->j_revoke_table[0])
518 		journal->j_revoke = journal->j_revoke_table[1];
519 	else
520 		journal->j_revoke = journal->j_revoke_table[0];
521 
522 	for (i = 0; i < journal->j_revoke->hash_size; i++)
523 		INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
524 }
525 
526 /*
527  * Write revoke records to the journal for all entries in the current
528  * revoke hash, deleting the entries as we go.
529  */
jbd2_journal_write_revoke_records(transaction_t * transaction,struct list_head * log_bufs)530 void jbd2_journal_write_revoke_records(transaction_t *transaction,
531 				       struct list_head *log_bufs)
532 {
533 	journal_t *journal = transaction->t_journal;
534 	struct buffer_head *descriptor;
535 	struct jbd2_revoke_record_s *record;
536 	struct jbd2_revoke_table_s *revoke;
537 	struct list_head *hash_list;
538 	int i, offset, count;
539 
540 	descriptor = NULL;
541 	offset = 0;
542 	count = 0;
543 
544 	/* select revoke table for committing transaction */
545 	revoke = journal->j_revoke == journal->j_revoke_table[0] ?
546 		journal->j_revoke_table[1] : journal->j_revoke_table[0];
547 
548 	for (i = 0; i < revoke->hash_size; i++) {
549 		hash_list = &revoke->hash_table[i];
550 
551 		while (!list_empty(hash_list)) {
552 			record = (struct jbd2_revoke_record_s *)
553 				hash_list->next;
554 			write_one_revoke_record(transaction, log_bufs,
555 						&descriptor, &offset, record);
556 			count++;
557 			list_del(&record->hash);
558 			kmem_cache_free(jbd2_revoke_record_cache, record);
559 		}
560 	}
561 	if (descriptor)
562 		flush_descriptor(journal, descriptor, offset);
563 	jbd2_debug(1, "Wrote %d revoke records\n", count);
564 }
565 
566 /*
567  * Write out one revoke record.  We need to create a new descriptor
568  * block if the old one is full or if we have not already created one.
569  */
570 
write_one_revoke_record(transaction_t * transaction,struct list_head * log_bufs,struct buffer_head ** descriptorp,int * offsetp,struct jbd2_revoke_record_s * record)571 static void write_one_revoke_record(transaction_t *transaction,
572 				    struct list_head *log_bufs,
573 				    struct buffer_head **descriptorp,
574 				    int *offsetp,
575 				    struct jbd2_revoke_record_s *record)
576 {
577 	journal_t *journal = transaction->t_journal;
578 	int csum_size = 0;
579 	struct buffer_head *descriptor;
580 	int sz, offset;
581 
582 	/* If we are already aborting, this all becomes a noop.  We
583            still need to go round the loop in
584            jbd2_journal_write_revoke_records in order to free all of the
585            revoke records: only the IO to the journal is omitted. */
586 	if (is_journal_aborted(journal))
587 		return;
588 
589 	descriptor = *descriptorp;
590 	offset = *offsetp;
591 
592 	/* Do we need to leave space at the end for a checksum? */
593 	if (jbd2_journal_has_csum_v2or3(journal))
594 		csum_size = sizeof(struct jbd2_journal_block_tail);
595 
596 	if (jbd2_has_feature_64bit(journal))
597 		sz = 8;
598 	else
599 		sz = 4;
600 
601 	/* Make sure we have a descriptor with space left for the record */
602 	if (descriptor) {
603 		if (offset + sz > journal->j_blocksize - csum_size) {
604 			flush_descriptor(journal, descriptor, offset);
605 			descriptor = NULL;
606 		}
607 	}
608 
609 	if (!descriptor) {
610 		descriptor = jbd2_journal_get_descriptor_buffer(transaction,
611 							JBD2_REVOKE_BLOCK);
612 		if (!descriptor)
613 			return;
614 
615 		/* Record it so that we can wait for IO completion later */
616 		BUFFER_TRACE(descriptor, "file in log_bufs");
617 		jbd2_file_log_bh(log_bufs, descriptor);
618 
619 		offset = sizeof(jbd2_journal_revoke_header_t);
620 		*descriptorp = descriptor;
621 	}
622 
623 	if (jbd2_has_feature_64bit(journal))
624 		* ((__be64 *)(&descriptor->b_data[offset])) =
625 			cpu_to_be64(record->blocknr);
626 	else
627 		* ((__be32 *)(&descriptor->b_data[offset])) =
628 			cpu_to_be32(record->blocknr);
629 	offset += sz;
630 
631 	*offsetp = offset;
632 }
633 
634 /*
635  * Flush a revoke descriptor out to the journal.  If we are aborting,
636  * this is a noop; otherwise we are generating a buffer which needs to
637  * be waited for during commit, so it has to go onto the appropriate
638  * journal buffer list.
639  */
640 
flush_descriptor(journal_t * journal,struct buffer_head * descriptor,int offset)641 static void flush_descriptor(journal_t *journal,
642 			     struct buffer_head *descriptor,
643 			     int offset)
644 {
645 	jbd2_journal_revoke_header_t *header;
646 
647 	if (is_journal_aborted(journal))
648 		return;
649 
650 	header = (jbd2_journal_revoke_header_t *)descriptor->b_data;
651 	header->r_count = cpu_to_be32(offset);
652 	jbd2_descriptor_block_csum_set(journal, descriptor);
653 
654 	set_buffer_jwrite(descriptor);
655 	BUFFER_TRACE(descriptor, "write");
656 	set_buffer_dirty(descriptor);
657 	write_dirty_buffer(descriptor, REQ_SYNC);
658 }
659 #endif
660 
661 /*
662  * Revoke support for recovery.
663  *
664  * Recovery needs to be able to:
665  *
666  *  record all revoke records, including the tid of the latest instance
667  *  of each revoke in the journal
668  *
669  *  check whether a given block in a given transaction should be replayed
670  *  (ie. has not been revoked by a revoke record in that or a subsequent
671  *  transaction)
672  *
673  *  empty the revoke table after recovery.
674  */
675 
676 /*
677  * First, setting revoke records.  We create a new revoke record for
678  * every block ever revoked in the log as we scan it for recovery, and
679  * we update the existing records if we find multiple revokes for a
680  * single block.
681  */
682 
jbd2_journal_set_revoke(journal_t * journal,unsigned long long blocknr,tid_t sequence)683 int jbd2_journal_set_revoke(journal_t *journal,
684 		       unsigned long long blocknr,
685 		       tid_t sequence)
686 {
687 	struct jbd2_revoke_record_s *record;
688 
689 	record = find_revoke_record(journal, blocknr);
690 	if (record) {
691 		/* If we have multiple occurrences, only record the
692 		 * latest sequence number in the hashed record */
693 		if (tid_gt(sequence, record->sequence))
694 			record->sequence = sequence;
695 		return 0;
696 	}
697 	return insert_revoke_hash(journal, blocknr, sequence);
698 }
699 
700 /*
701  * Test revoke records.  For a given block referenced in the log, has
702  * that block been revoked?  A revoke record with a given transaction
703  * sequence number revokes all blocks in that transaction and earlier
704  * ones, but later transactions still need replayed.
705  */
706 
jbd2_journal_test_revoke(journal_t * journal,unsigned long long blocknr,tid_t sequence)707 int jbd2_journal_test_revoke(journal_t *journal,
708 			unsigned long long blocknr,
709 			tid_t sequence)
710 {
711 	struct jbd2_revoke_record_s *record;
712 
713 	record = find_revoke_record(journal, blocknr);
714 	if (!record)
715 		return 0;
716 	if (tid_gt(sequence, record->sequence))
717 		return 0;
718 	return 1;
719 }
720 
721 /*
722  * Finally, once recovery is over, we need to clear the revoke table so
723  * that it can be reused by the running filesystem.
724  */
725 
jbd2_journal_clear_revoke(journal_t * journal)726 void jbd2_journal_clear_revoke(journal_t *journal)
727 {
728 	int i;
729 	struct list_head *hash_list;
730 	struct jbd2_revoke_record_s *record;
731 	struct jbd2_revoke_table_s *revoke;
732 
733 	revoke = journal->j_revoke;
734 
735 	for (i = 0; i < revoke->hash_size; i++) {
736 		hash_list = &revoke->hash_table[i];
737 		while (!list_empty(hash_list)) {
738 			record = (struct jbd2_revoke_record_s*) hash_list->next;
739 			list_del(&record->hash);
740 			kmem_cache_free(jbd2_revoke_record_cache, record);
741 		}
742 	}
743 }
744