~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/jbd2/revoke.c

Version: ~ [ linux-5.9.1 ] ~ [ linux-5.8.16 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.72 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.152 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.202 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.240 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.240 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 
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 
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 
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 
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 
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 
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 
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 
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 
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. */
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! */
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 
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         jbd_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  */
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         jbd_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                         jbd_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  */
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  */
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  */
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         jbd_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 
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 
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 
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 
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 
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 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp