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 	/* We really ought not ever to revoke twice in a row without
375            first having the revoke cancelled: it's illegal to free a
376            block twice without allocating it in between! */
377 	if (bh) {
378 		if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
379 				 "inconsistent data on disk")) {
380 			if (!bh_in)
381 				brelse(bh);
382 			return -EIO;
383 		}
384 		set_buffer_revoked(bh);
385 		set_buffer_revokevalid(bh);
386 		if (bh_in) {
387 			BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
388 			jbd2_journal_forget(handle, bh_in);
389 		} else {
390 			BUFFER_TRACE(bh, "call brelse");
391 			__brelse(bh);
392 		}
393 	}
394 
395 	jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
396 	err = insert_revoke_hash(journal, blocknr,
397 				handle->h_transaction->t_tid);
398 	BUFFER_TRACE(bh_in, "exit");
399 	return err;
400 }
401 
402 /*
403  * Cancel an outstanding revoke.  For use only internally by the
404  * journaling code (called from jbd2_journal_get_write_access).
405  *
406  * We trust buffer_revoked() on the buffer if the buffer is already
407  * being journaled: if there is no revoke pending on the buffer, then we
408  * don't do anything here.
409  *
410  * This would break if it were possible for a buffer to be revoked and
411  * discarded, and then reallocated within the same transaction.  In such
412  * a case we would have lost the revoked bit, but when we arrived here
413  * the second time we would still have a pending revoke to cancel.  So,
414  * do not trust the Revoked bit on buffers unless RevokeValid is also
415  * set.
416  */
jbd2_journal_cancel_revoke(handle_t * handle,struct journal_head * jh)417 int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
418 {
419 	struct jbd2_revoke_record_s *record;
420 	journal_t *journal = handle->h_transaction->t_journal;
421 	int need_cancel;
422 	int did_revoke = 0;	/* akpm: debug */
423 	struct buffer_head *bh = jh2bh(jh);
424 
425 	jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
426 
427 	/* Is the existing Revoke bit valid?  If so, we trust it, and
428 	 * only perform the full cancel if the revoke bit is set.  If
429 	 * not, we can't trust the revoke bit, and we need to do the
430 	 * full search for a revoke record. */
431 	if (test_set_buffer_revokevalid(bh)) {
432 		need_cancel = test_clear_buffer_revoked(bh);
433 	} else {
434 		need_cancel = 1;
435 		clear_buffer_revoked(bh);
436 	}
437 
438 	if (need_cancel) {
439 		record = find_revoke_record(journal, bh->b_blocknr);
440 		if (record) {
441 			jbd_debug(4, "cancelled existing revoke on "
442 				  "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
443 			spin_lock(&journal->j_revoke_lock);
444 			list_del(&record->hash);
445 			spin_unlock(&journal->j_revoke_lock);
446 			kmem_cache_free(jbd2_revoke_record_cache, record);
447 			did_revoke = 1;
448 		}
449 	}
450 
451 #ifdef JBD2_EXPENSIVE_CHECKING
452 	/* There better not be one left behind by now! */
453 	record = find_revoke_record(journal, bh->b_blocknr);
454 	J_ASSERT_JH(jh, record == NULL);
455 #endif
456 
457 	/* Finally, have we just cleared revoke on an unhashed
458 	 * buffer_head?  If so, we'd better make sure we clear the
459 	 * revoked status on any hashed alias too, otherwise the revoke
460 	 * state machine will get very upset later on. */
461 	if (need_cancel) {
462 		struct buffer_head *bh2;
463 		bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
464 		if (bh2) {
465 			if (bh2 != bh)
466 				clear_buffer_revoked(bh2);
467 			__brelse(bh2);
468 		}
469 	}
470 	return did_revoke;
471 }
472 
473 /*
474  * journal_clear_revoked_flag clears revoked flag of buffers in
475  * revoke table to reflect there is no revoked buffers in the next
476  * transaction which is going to be started.
477  */
jbd2_clear_buffer_revoked_flags(journal_t * journal)478 void jbd2_clear_buffer_revoked_flags(journal_t *journal)
479 {
480 	struct jbd2_revoke_table_s *revoke = journal->j_revoke;
481 	int i = 0;
482 
483 	for (i = 0; i < revoke->hash_size; i++) {
484 		struct list_head *hash_list;
485 		struct list_head *list_entry;
486 		hash_list = &revoke->hash_table[i];
487 
488 		list_for_each(list_entry, hash_list) {
489 			struct jbd2_revoke_record_s *record;
490 			struct buffer_head *bh;
491 			record = (struct jbd2_revoke_record_s *)list_entry;
492 			bh = __find_get_block(journal->j_fs_dev,
493 					      record->blocknr,
494 					      journal->j_blocksize);
495 			if (bh) {
496 				clear_buffer_revoked(bh);
497 				__brelse(bh);
498 			}
499 		}
500 	}
501 }
502 
503 /* journal_switch_revoke table select j_revoke for next transaction
504  * we do not want to suspend any processing until all revokes are
505  * written -bzzz
506  */
jbd2_journal_switch_revoke_table(journal_t * journal)507 void jbd2_journal_switch_revoke_table(journal_t *journal)
508 {
509 	int i;
510 
511 	if (journal->j_revoke == journal->j_revoke_table[0])
512 		journal->j_revoke = journal->j_revoke_table[1];
513 	else
514 		journal->j_revoke = journal->j_revoke_table[0];
515 
516 	for (i = 0; i < journal->j_revoke->hash_size; i++)
517 		INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
518 }
519 
520 /*
521  * Write revoke records to the journal for all entries in the current
522  * revoke hash, deleting the entries as we go.
523  */
jbd2_journal_write_revoke_records(transaction_t * transaction,struct list_head * log_bufs)524 void jbd2_journal_write_revoke_records(transaction_t *transaction,
525 				       struct list_head *log_bufs)
526 {
527 	journal_t *journal = transaction->t_journal;
528 	struct buffer_head *descriptor;
529 	struct jbd2_revoke_record_s *record;
530 	struct jbd2_revoke_table_s *revoke;
531 	struct list_head *hash_list;
532 	int i, offset, count;
533 
534 	descriptor = NULL;
535 	offset = 0;
536 	count = 0;
537 
538 	/* select revoke table for committing transaction */
539 	revoke = journal->j_revoke == journal->j_revoke_table[0] ?
540 		journal->j_revoke_table[1] : journal->j_revoke_table[0];
541 
542 	for (i = 0; i < revoke->hash_size; i++) {
543 		hash_list = &revoke->hash_table[i];
544 
545 		while (!list_empty(hash_list)) {
546 			record = (struct jbd2_revoke_record_s *)
547 				hash_list->next;
548 			write_one_revoke_record(transaction, log_bufs,
549 						&descriptor, &offset, record);
550 			count++;
551 			list_del(&record->hash);
552 			kmem_cache_free(jbd2_revoke_record_cache, record);
553 		}
554 	}
555 	if (descriptor)
556 		flush_descriptor(journal, descriptor, offset);
557 	jbd_debug(1, "Wrote %d revoke records\n", count);
558 }
559 
560 /*
561  * Write out one revoke record.  We need to create a new descriptor
562  * block if the old one is full or if we have not already created one.
563  */
564 
write_one_revoke_record(transaction_t * transaction,struct list_head * log_bufs,struct buffer_head ** descriptorp,int * offsetp,struct jbd2_revoke_record_s * record)565 static void write_one_revoke_record(transaction_t *transaction,
566 				    struct list_head *log_bufs,
567 				    struct buffer_head **descriptorp,
568 				    int *offsetp,
569 				    struct jbd2_revoke_record_s *record)
570 {
571 	journal_t *journal = transaction->t_journal;
572 	int csum_size = 0;
573 	struct buffer_head *descriptor;
574 	int sz, offset;
575 
576 	/* If we are already aborting, this all becomes a noop.  We
577            still need to go round the loop in
578            jbd2_journal_write_revoke_records in order to free all of the
579            revoke records: only the IO to the journal is omitted. */
580 	if (is_journal_aborted(journal))
581 		return;
582 
583 	descriptor = *descriptorp;
584 	offset = *offsetp;
585 
586 	/* Do we need to leave space at the end for a checksum? */
587 	if (jbd2_journal_has_csum_v2or3(journal))
588 		csum_size = sizeof(struct jbd2_journal_block_tail);
589 
590 	if (jbd2_has_feature_64bit(journal))
591 		sz = 8;
592 	else
593 		sz = 4;
594 
595 	/* Make sure we have a descriptor with space left for the record */
596 	if (descriptor) {
597 		if (offset + sz > journal->j_blocksize - csum_size) {
598 			flush_descriptor(journal, descriptor, offset);
599 			descriptor = NULL;
600 		}
601 	}
602 
603 	if (!descriptor) {
604 		descriptor = jbd2_journal_get_descriptor_buffer(transaction,
605 							JBD2_REVOKE_BLOCK);
606 		if (!descriptor)
607 			return;
608 
609 		/* Record it so that we can wait for IO completion later */
610 		BUFFER_TRACE(descriptor, "file in log_bufs");
611 		jbd2_file_log_bh(log_bufs, descriptor);
612 
613 		offset = sizeof(jbd2_journal_revoke_header_t);
614 		*descriptorp = descriptor;
615 	}
616 
617 	if (jbd2_has_feature_64bit(journal))
618 		* ((__be64 *)(&descriptor->b_data[offset])) =
619 			cpu_to_be64(record->blocknr);
620 	else
621 		* ((__be32 *)(&descriptor->b_data[offset])) =
622 			cpu_to_be32(record->blocknr);
623 	offset += sz;
624 
625 	*offsetp = offset;
626 }
627 
628 /*
629  * Flush a revoke descriptor out to the journal.  If we are aborting,
630  * this is a noop; otherwise we are generating a buffer which needs to
631  * be waited for during commit, so it has to go onto the appropriate
632  * journal buffer list.
633  */
634 
flush_descriptor(journal_t * journal,struct buffer_head * descriptor,int offset)635 static void flush_descriptor(journal_t *journal,
636 			     struct buffer_head *descriptor,
637 			     int offset)
638 {
639 	jbd2_journal_revoke_header_t *header;
640 
641 	if (is_journal_aborted(journal)) {
642 		put_bh(descriptor);
643 		return;
644 	}
645 
646 	header = (jbd2_journal_revoke_header_t *)descriptor->b_data;
647 	header->r_count = cpu_to_be32(offset);
648 	jbd2_descriptor_block_csum_set(journal, descriptor);
649 
650 	set_buffer_jwrite(descriptor);
651 	BUFFER_TRACE(descriptor, "write");
652 	set_buffer_dirty(descriptor);
653 	write_dirty_buffer(descriptor, REQ_SYNC);
654 }
655 #endif
656 
657 /*
658  * Revoke support for recovery.
659  *
660  * Recovery needs to be able to:
661  *
662  *  record all revoke records, including the tid of the latest instance
663  *  of each revoke in the journal
664  *
665  *  check whether a given block in a given transaction should be replayed
666  *  (ie. has not been revoked by a revoke record in that or a subsequent
667  *  transaction)
668  *
669  *  empty the revoke table after recovery.
670  */
671 
672 /*
673  * First, setting revoke records.  We create a new revoke record for
674  * every block ever revoked in the log as we scan it for recovery, and
675  * we update the existing records if we find multiple revokes for a
676  * single block.
677  */
678 
jbd2_journal_set_revoke(journal_t * journal,unsigned long long blocknr,tid_t sequence)679 int jbd2_journal_set_revoke(journal_t *journal,
680 		       unsigned long long blocknr,
681 		       tid_t sequence)
682 {
683 	struct jbd2_revoke_record_s *record;
684 
685 	record = find_revoke_record(journal, blocknr);
686 	if (record) {
687 		/* If we have multiple occurrences, only record the
688 		 * latest sequence number in the hashed record */
689 		if (tid_gt(sequence, record->sequence))
690 			record->sequence = sequence;
691 		return 0;
692 	}
693 	return insert_revoke_hash(journal, blocknr, sequence);
694 }
695 
696 /*
697  * Test revoke records.  For a given block referenced in the log, has
698  * that block been revoked?  A revoke record with a given transaction
699  * sequence number revokes all blocks in that transaction and earlier
700  * ones, but later transactions still need replayed.
701  */
702 
jbd2_journal_test_revoke(journal_t * journal,unsigned long long blocknr,tid_t sequence)703 int jbd2_journal_test_revoke(journal_t *journal,
704 			unsigned long long blocknr,
705 			tid_t sequence)
706 {
707 	struct jbd2_revoke_record_s *record;
708 
709 	record = find_revoke_record(journal, blocknr);
710 	if (!record)
711 		return 0;
712 	if (tid_gt(sequence, record->sequence))
713 		return 0;
714 	return 1;
715 }
716 
717 /*
718  * Finally, once recovery is over, we need to clear the revoke table so
719  * that it can be reused by the running filesystem.
720  */
721 
jbd2_journal_clear_revoke(journal_t * journal)722 void jbd2_journal_clear_revoke(journal_t *journal)
723 {
724 	int i;
725 	struct list_head *hash_list;
726 	struct jbd2_revoke_record_s *record;
727 	struct jbd2_revoke_table_s *revoke;
728 
729 	revoke = journal->j_revoke;
730 
731 	for (i = 0; i < revoke->hash_size; i++) {
732 		hash_list = &revoke->hash_table[i];
733 		while (!list_empty(hash_list)) {
734 			record = (struct jbd2_revoke_record_s*) hash_list->next;
735 			list_del(&record->hash);
736 			kmem_cache_free(jbd2_revoke_record_cache, record);
737 		}
738 	}
739 }
740