1 files changed, 712 insertions, 0 deletions

diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c
new file mode 100644
index 000000000000..380d19917f37
--- /dev/null
+++ b/fs/jbd2/revoke.c
@@ -0,0 +1,712 @@
+/*
+ * linux/fs/revoke.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 2000
+ *
+ * Copyright 2000 Red Hat corp --- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Journal revoke routines for the generic filesystem journaling code;
+ * part of the ext2fs journaling system.
+ *
+ * Revoke is the mechanism used to prevent old log records for deleted
+ * metadata from being replayed on top of newer data using the same
+ * blocks.  The revoke mechanism is used in two separate places:
+ *
+ * + Commit: during commit we write the entire list of the current
+ *   transaction's revoked blocks to the journal
+ *
+ * + Recovery: during recovery we record the transaction ID of all
+ *   revoked blocks.  If there are multiple revoke records in the log
+ *   for a single block, only the last one counts, and if there is a log
+ *   entry for a block beyond the last revoke, then that log entry still
+ *   gets replayed.
+ *
+ * We can get interactions between revokes and new log data within a
+ * single transaction:
+ *
+ * Block is revoked and then journaled:
+ *   The desired end result is the journaling of the new block, so we
+ *   cancel the revoke before the transaction commits.
+ *
+ * Block is journaled and then revoked:
+ *   The revoke must take precedence over the write of the block, so we
+ *   need either to cancel the journal entry or to write the revoke
+ *   later in the log than the log block.  In this case, we choose the
+ *   latter: journaling a block cancels any revoke record for that block
+ *   in the current transaction, so any revoke for that block in the
+ *   transaction must have happened after the block was journaled and so
+ *   the revoke must take precedence.
+ *
+ * Block is revoked and then written as data:
+ *   The data write is allowed to succeed, but the revoke is _not_
+ *   cancelled.  We still need to prevent old log records from
+ *   overwriting the new data.  We don't even need to clear the revoke
+ *   bit here.
+ *
+ * Revoke information on buffers is a tri-state value:
+ *
+ * RevokeValid clear:   no cached revoke status, need to look it up
+ * RevokeValid set, Revoked clear:
+ *                      buffer has not been revoked, and cancel_revoke
+ *                      need do nothing.
+ * RevokeValid set, Revoked set:
+ *                      buffer has been revoked.
+ */
+
+#ifndef __KERNEL__
+#include "jfs_user.h"
+#else
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd2.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+#endif
+
+static kmem_cache_t *jbd2_revoke_record_cache;
+static kmem_cache_t *jbd2_revoke_table_cache;
+
+/* Each revoke record represents one single revoked block.  During
+   journal replay, this involves recording the transaction ID of the
+   last transaction to revoke this block. */
+
+struct jbd2_revoke_record_s
+{
+        struct list_head  hash;
+        tid_t             sequence;     /* Used for recovery only */
+        unsigned long long        blocknr;
+};
+
+
+/* The revoke table is just a simple hash table of revoke records. */
+struct jbd2_revoke_table_s
+{
+        /* It is conceivable that we might want a larger hash table
+         * for recovery.  Must be a power of two. */
+        int               hash_size;
+        int               hash_shift;
+        struct list_head *hash_table;
+};
+
+
+#ifdef __KERNEL__
+static void write_one_revoke_record(journal_t *, transaction_t *,
+                                    struct journal_head **, int *,
+                                    struct jbd2_revoke_record_s *);
+static void flush_descriptor(journal_t *, struct journal_head *, int);
+#endif
+
+/* Utility functions to maintain the revoke table */
+
+/* Borrowed from buffer.c: this is a tried and tested block hash function */
+static inline int hash(journal_t *journal, unsigned long long block)
+{
+        struct jbd2_revoke_table_s *table = journal->j_revoke;
+        int hash_shift = table->hash_shift;
+        int hash = (int)block ^ (int)((block >> 31) >> 1);
+
+        return ((hash << (hash_shift - 6)) ^
+                (hash >> 13) ^
+                (hash << (hash_shift - 12))) & (table->hash_size - 1);
+}
+
+static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
+                              tid_t seq)
+{
+        struct list_head *hash_list;
+        struct jbd2_revoke_record_s *record;
+
+repeat:
+        record = kmem_cache_alloc(jbd2_revoke_record_cache, GFP_NOFS);
+        if (!record)
+                goto oom;
+
+        record->sequence = seq;
+        record->blocknr = blocknr;
+        hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
+        spin_lock(&journal->j_revoke_lock);
+        list_add(&record->hash, hash_list);
+        spin_unlock(&journal->j_revoke_lock);
+        return 0;
+
+oom:
+        if (!journal_oom_retry)
+                return -ENOMEM;
+        jbd_debug(1, "ENOMEM in %s, retrying\n", __FUNCTION__);
+        yield();
+        goto repeat;
+}
+
+/* Find a revoke record in the journal's hash table. */
+
+static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
+                                                      unsigned long long blocknr)
+{
+        struct list_head *hash_list;
+        struct jbd2_revoke_record_s *record;
+
+        hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
+
+        spin_lock(&journal->j_revoke_lock);
+        record = (struct jbd2_revoke_record_s *) hash_list->next;
+        while (&(record->hash) != hash_list) {
+                if (record->blocknr == blocknr) {
+                        spin_unlock(&journal->j_revoke_lock);
+                        return record;
+                }
+                record = (struct jbd2_revoke_record_s *) record->hash.next;
+        }
+        spin_unlock(&journal->j_revoke_lock);
+        return NULL;
+}
+
+int __init jbd2_journal_init_revoke_caches(void)
+{
+        jbd2_revoke_record_cache = kmem_cache_create("jbd2_revoke_record",
+                                           sizeof(struct jbd2_revoke_record_s),
+                                           0, SLAB_HWCACHE_ALIGN, NULL, NULL);
+        if (jbd2_revoke_record_cache == 0)
+                return -ENOMEM;
+
+        jbd2_revoke_table_cache = kmem_cache_create("jbd2_revoke_table",
+                                           sizeof(struct jbd2_revoke_table_s),
+                                           0, 0, NULL, NULL);
+        if (jbd2_revoke_table_cache == 0) {
+                kmem_cache_destroy(jbd2_revoke_record_cache);
+                jbd2_revoke_record_cache = NULL;
+                return -ENOMEM;
+        }
+        return 0;
+}
+
+void jbd2_journal_destroy_revoke_caches(void)
+{
+        kmem_cache_destroy(jbd2_revoke_record_cache);
+        jbd2_revoke_record_cache = NULL;
+        kmem_cache_destroy(jbd2_revoke_table_cache);
+        jbd2_revoke_table_cache = NULL;
+}
+
+/* Initialise the revoke table for a given journal to a given size. */
+
+int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
+{
+        int shift, tmp;
+
+        J_ASSERT (journal->j_revoke_table[0] == NULL);
+
+        shift = 0;
+        tmp = hash_size;
+        while((tmp >>= 1UL) != 0UL)
+                shift++;
+
+        journal->j_revoke_table[0] = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
+        if (!journal->j_revoke_table[0])
+                return -ENOMEM;
+        journal->j_revoke = journal->j_revoke_table[0];
+
+        /* Check that the hash_size is a power of two */
+        J_ASSERT ((hash_size & (hash_size-1)) == 0);
+
+        journal->j_revoke->hash_size = hash_size;
+
+        journal->j_revoke->hash_shift = shift;
+
+        journal->j_revoke->hash_table =
+                kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
+        if (!journal->j_revoke->hash_table) {
+                kmem_cache_free(jbd2_revoke_table_cache, journal->j_revoke_table[0]);
+                journal->j_revoke = NULL;
+                return -ENOMEM;
+        }
+
+        for (tmp = 0; tmp < hash_size; tmp++)
+                INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]);
+
+        journal->j_revoke_table[1] = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
+        if (!journal->j_revoke_table[1]) {
+                kfree(journal->j_revoke_table[0]->hash_table);
+                kmem_cache_free(jbd2_revoke_table_cache, journal->j_revoke_table[0]);
+                return -ENOMEM;
+        }
+
+        journal->j_revoke = journal->j_revoke_table[1];
+
+        /* Check that the hash_size is a power of two */
+        J_ASSERT ((hash_size & (hash_size-1)) == 0);
+
+        journal->j_revoke->hash_size = hash_size;
+
+        journal->j_revoke->hash_shift = shift;
+
+        journal->j_revoke->hash_table =
+                kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
+        if (!journal->j_revoke->hash_table) {
+                kfree(journal->j_revoke_table[0]->hash_table);
+                kmem_cache_free(jbd2_revoke_table_cache, journal->j_revoke_table[0]);
+                kmem_cache_free(jbd2_revoke_table_cache, journal->j_revoke_table[1]);
+                journal->j_revoke = NULL;
+                return -ENOMEM;
+        }
+
+        for (tmp = 0; tmp < hash_size; tmp++)
+                INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]);
+
+        spin_lock_init(&journal->j_revoke_lock);
+
+        return 0;
+}
+
+/* Destoy a journal's revoke table.  The table must already be empty! */
+
+void jbd2_journal_destroy_revoke(journal_t *journal)
+{
+        struct jbd2_revoke_table_s *table;
+        struct list_head *hash_list;
+        int i;
+
+        table = journal->j_revoke_table[0];
+        if (!table)
+                return;
+
+        for (i=0; i<table->hash_size; i++) {
+                hash_list = &table->hash_table[i];
+                J_ASSERT (list_empty(hash_list));
+        }
+
+        kfree(table->hash_table);
+        kmem_cache_free(jbd2_revoke_table_cache, table);
+        journal->j_revoke = NULL;
+
+        table = journal->j_revoke_table[1];
+        if (!table)
+                return;
+
+        for (i=0; i<table->hash_size; i++) {
+                hash_list = &table->hash_table[i];
+                J_ASSERT (list_empty(hash_list));
+        }
+
+        kfree(table->hash_table);
+        kmem_cache_free(jbd2_revoke_table_cache, table);
+        journal->j_revoke = NULL;
+}
+
+
+#ifdef __KERNEL__
+
+/*
+ * jbd2_journal_revoke: revoke a given buffer_head from the journal.  This
+ * prevents the block from being replayed during recovery if we take a
+ * crash after this current transaction commits.  Any subsequent
+ * metadata writes of the buffer in this transaction cancel the
+ * revoke.
+ *
+ * Note that this call may block --- it is up to the caller to make
+ * sure that there are no further calls to journal_write_metadata
+ * before the revoke is complete.  In ext3, this implies calling the
+ * revoke before clearing the block bitmap when we are deleting
+ * metadata.
+ *
+ * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
+ * parameter, but does _not_ forget the buffer_head if the bh was only
+ * found implicitly.
+ *
+ * bh_in may not be a journalled buffer - it may have come off
+ * the hash tables without an attached journal_head.
+ *
+ * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
+ * by one.
+ */
+
+int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
+                   struct buffer_head *bh_in)
+{
+        struct buffer_head *bh = NULL;
+        journal_t *journal;
+        struct block_device *bdev;
+        int err;
+
+        might_sleep();
+        if (bh_in)
+                BUFFER_TRACE(bh_in, "enter");
+
+        journal = handle->h_transaction->t_journal;
+        if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
+                J_ASSERT (!"Cannot set revoke feature!");
+                return -EINVAL;
+        }
+
+        bdev = journal->j_fs_dev;
+        bh = bh_in;
+
+        if (!bh) {
+                bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
+                if (bh)
+                        BUFFER_TRACE(bh, "found on hash");
+        }
+#ifdef JBD_EXPENSIVE_CHECKING
+        else {
+                struct buffer_head *bh2;
+
+                /* If there is a different buffer_head lying around in
+                 * memory anywhere... */
+                bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
+                if (bh2) {
+                        /* ... and it has RevokeValid status... */
+                        if (bh2 != bh && buffer_revokevalid(bh2))
+                                /* ...then it better be revoked too,
+                                 * since it's illegal to create a revoke
+                                 * record against a buffer_head which is
+                                 * not marked revoked --- that would
+                                 * risk missing a subsequent revoke
+                                 * cancel. */
+                                J_ASSERT_BH(bh2, buffer_revoked(bh2));
+                        put_bh(bh2);
+                }
+        }
+#endif
+
+        /* We really ought not ever to revoke twice in a row without
+           first having the revoke cancelled: it's illegal to free a
+           block twice without allocating it in between! */
+        if (bh) {
+                if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
+                                 "inconsistent data on disk")) {
+                        if (!bh_in)
+                                brelse(bh);
+                        return -EIO;
+                }
+                set_buffer_revoked(bh);
+                set_buffer_revokevalid(bh);
+                if (bh_in) {
+                        BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
+                        jbd2_journal_forget(handle, bh_in);
+                } else {
+                        BUFFER_TRACE(bh, "call brelse");
+                        __brelse(bh);
+                }
+        }
+
+        jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
+        err = insert_revoke_hash(journal, blocknr,
+                                handle->h_transaction->t_tid);
+        BUFFER_TRACE(bh_in, "exit");
+        return err;
+}
+
+/*
+ * Cancel an outstanding revoke.  For use only internally by the
+ * journaling code (called from jbd2_journal_get_write_access).
+ *
+ * We trust buffer_revoked() on the buffer if the buffer is already
+ * being journaled: if there is no revoke pending on the buffer, then we
+ * don't do anything here.
+ *
+ * This would break if it were possible for a buffer to be revoked and
+ * discarded, and then reallocated within the same transaction.  In such
+ * a case we would have lost the revoked bit, but when we arrived here
+ * the second time we would still have a pending revoke to cancel.  So,
+ * do not trust the Revoked bit on buffers unless RevokeValid is also
+ * set.
+ *
+ * The caller must have the journal locked.
+ */
+int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
+{
+        struct jbd2_revoke_record_s *record;
+        journal_t *journal = handle->h_transaction->t_journal;
+        int need_cancel;
+        int did_revoke = 0;     /* akpm: debug */
+        struct buffer_head *bh = jh2bh(jh);
+
+        jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
+
+        /* Is the existing Revoke bit valid?  If so, we trust it, and
+         * only perform the full cancel if the revoke bit is set.  If
+         * not, we can't trust the revoke bit, and we need to do the
+         * full search for a revoke record. */
+        if (test_set_buffer_revokevalid(bh)) {
+                need_cancel = test_clear_buffer_revoked(bh);
+        } else {
+                need_cancel = 1;
+                clear_buffer_revoked(bh);
+        }
+
+        if (need_cancel) {
+                record = find_revoke_record(journal, bh->b_blocknr);
+                if (record) {
+                        jbd_debug(4, "cancelled existing revoke on "
+                                  "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
+                        spin_lock(&journal->j_revoke_lock);
+                        list_del(&record->hash);
+                        spin_unlock(&journal->j_revoke_lock);
+                        kmem_cache_free(jbd2_revoke_record_cache, record);
+                        did_revoke = 1;
+                }
+        }
+
+#ifdef JBD_EXPENSIVE_CHECKING
+        /* There better not be one left behind by now! */
+        record = find_revoke_record(journal, bh->b_blocknr);
+        J_ASSERT_JH(jh, record == NULL);
+#endif
+
+        /* Finally, have we just cleared revoke on an unhashed
+         * buffer_head?  If so, we'd better make sure we clear the
+         * revoked status on any hashed alias too, otherwise the revoke
+         * state machine will get very upset later on. */
+        if (need_cancel) {
+                struct buffer_head *bh2;
+                bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
+                if (bh2) {
+                        if (bh2 != bh)
+                                clear_buffer_revoked(bh2);
+                        __brelse(bh2);
+                }
+        }
+        return did_revoke;
+}
+
+/* journal_switch_revoke table select j_revoke for next transaction
+ * we do not want to suspend any processing until all revokes are
+ * written -bzzz
+ */
+void jbd2_journal_switch_revoke_table(journal_t *journal)
+{
+        int i;
+
+        if (journal->j_revoke == journal->j_revoke_table[0])
+                journal->j_revoke = journal->j_revoke_table[1];
+        else
+                journal->j_revoke = journal->j_revoke_table[0];
+
+        for (i = 0; i < journal->j_revoke->hash_size; i++)
+                INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
+}
+
+/*
+ * Write revoke records to the journal for all entries in the current
+ * revoke hash, deleting the entries as we go.
+ *
+ * Called with the journal lock held.
+ */
+
+void jbd2_journal_write_revoke_records(journal_t *journal,
+                                  transaction_t *transaction)
+{
+        struct journal_head *descriptor;
+        struct jbd2_revoke_record_s *record;
+        struct jbd2_revoke_table_s *revoke;
+        struct list_head *hash_list;
+        int i, offset, count;
+
+        descriptor = NULL;
+        offset = 0;
+        count = 0;
+
+        /* select revoke table for committing transaction */
+        revoke = journal->j_revoke == journal->j_revoke_table[0] ?
+                journal->j_revoke_table[1] : journal->j_revoke_table[0];
+
+        for (i = 0; i < revoke->hash_size; i++) {
+                hash_list = &revoke->hash_table[i];
+
+                while (!list_empty(hash_list)) {
+                        record = (struct jbd2_revoke_record_s *)
+                                hash_list->next;
+                        write_one_revoke_record(journal, transaction,
+                                                &descriptor, &offset,
+                                                record);
+                        count++;
+                        list_del(&record->hash);
+                        kmem_cache_free(jbd2_revoke_record_cache, record);
+                }
+        }
+        if (descriptor)
+                flush_descriptor(journal, descriptor, offset);
+        jbd_debug(1, "Wrote %d revoke records\n", count);
+}
+
+/*
+ * Write out one revoke record.  We need to create a new descriptor
+ * block if the old one is full or if we have not already created one.
+ */
+
+static void write_one_revoke_record(journal_t *journal,
+                                    transaction_t *transaction,
+                                    struct journal_head **descriptorp,
+                                    int *offsetp,
+                                    struct jbd2_revoke_record_s *record)
+{
+        struct journal_head *descriptor;
+        int offset;
+        journal_header_t *header;
+
+        /* If we are already aborting, this all becomes a noop.  We
+           still need to go round the loop in
+           jbd2_journal_write_revoke_records in order to free all of the
+           revoke records: only the IO to the journal is omitted. */
+        if (is_journal_aborted(journal))
+                return;
+
+        descriptor = *descriptorp;
+        offset = *offsetp;
+
+        /* Make sure we have a descriptor with space left for the record */
+        if (descriptor) {
+                if (offset == journal->j_blocksize) {
+                        flush_descriptor(journal, descriptor, offset);
+                        descriptor = NULL;
+                }
+        }
+
+        if (!descriptor) {
+                descriptor = jbd2_journal_get_descriptor_buffer(journal);
+                if (!descriptor)
+                        return;
+                header = (journal_header_t *) &jh2bh(descriptor)->b_data[0];
+                header->h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
+                header->h_blocktype = cpu_to_be32(JBD2_REVOKE_BLOCK);
+                header->h_sequence  = cpu_to_be32(transaction->t_tid);
+
+                /* Record it so that we can wait for IO completion later */
+                JBUFFER_TRACE(descriptor, "file as BJ_LogCtl");
+                jbd2_journal_file_buffer(descriptor, transaction, BJ_LogCtl);
+
+                offset = sizeof(jbd2_journal_revoke_header_t);
+                *descriptorp = descriptor;
+        }
+
+        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) {
+                * ((__be64 *)(&jh2bh(descriptor)->b_data[offset])) =
+                        cpu_to_be64(record->blocknr);
+                offset += 8;
+
+        } else {
+                * ((__be32 *)(&jh2bh(descriptor)->b_data[offset])) =
+                        cpu_to_be32(record->blocknr);
+                offset += 4;
+        }
+
+        *offsetp = offset;
+}
+
+/*
+ * Flush a revoke descriptor out to the journal.  If we are aborting,
+ * this is a noop; otherwise we are generating a buffer which needs to
+ * be waited for during commit, so it has to go onto the appropriate
+ * journal buffer list.
+ */
+
+static void flush_descriptor(journal_t *journal,
+                             struct journal_head *descriptor,
+                             int offset)
+{
+        jbd2_journal_revoke_header_t *header;
+        struct buffer_head *bh = jh2bh(descriptor);
+
+        if (is_journal_aborted(journal)) {
+                put_bh(bh);
+                return;
+        }
+
+        header = (jbd2_journal_revoke_header_t *) jh2bh(descriptor)->b_data;
+        header->r_count = cpu_to_be32(offset);
+        set_buffer_jwrite(bh);
+        BUFFER_TRACE(bh, "write");
+        set_buffer_dirty(bh);
+        ll_rw_block(SWRITE, 1, &bh);
+}
+#endif
+
+/*
+ * Revoke support for recovery.
+ *
+ * Recovery needs to be able to:
+ *
+ *  record all revoke records, including the tid of the latest instance
+ *  of each revoke in the journal
+ *
+ *  check whether a given block in a given transaction should be replayed
+ *  (ie. has not been revoked by a revoke record in that or a subsequent
+ *  transaction)
+ *
+ *  empty the revoke table after recovery.
+ */
+
+/*
+ * First, setting revoke records.  We create a new revoke record for
+ * every block ever revoked in the log as we scan it for recovery, and
+ * we update the existing records if we find multiple revokes for a
+ * single block.
+ */
+
+int jbd2_journal_set_revoke(journal_t *journal,
+                       unsigned long long blocknr,
+                       tid_t sequence)
+{
+        struct jbd2_revoke_record_s *record;
+
+        record = find_revoke_record(journal, blocknr);
+        if (record) {
+                /* If we have multiple occurrences, only record the
+                 * latest sequence number in the hashed record */
+                if (tid_gt(sequence, record->sequence))
+                        record->sequence = sequence;
+                return 0;
+        }
+        return insert_revoke_hash(journal, blocknr, sequence);
+}
+
+/*
+ * Test revoke records.  For a given block referenced in the log, has
+ * that block been revoked?  A revoke record with a given transaction
+ * sequence number revokes all blocks in that transaction and earlier
+ * ones, but later transactions still need replayed.
+ */
+
+int jbd2_journal_test_revoke(journal_t *journal,
+                        unsigned long long blocknr,
+                        tid_t sequence)
+{
+        struct jbd2_revoke_record_s *record;
+
+        record = find_revoke_record(journal, blocknr);
+        if (!record)
+                return 0;
+        if (tid_gt(sequence, record->sequence))
+                return 0;
+        return 1;
+}
+
+/*
+ * Finally, once recovery is over, we need to clear the revoke table so
+ * that it can be reused by the running filesystem.
+ */
+
+void jbd2_journal_clear_revoke(journal_t *journal)
+{
+        int i;
+        struct list_head *hash_list;
+        struct jbd2_revoke_record_s *record;
+        struct jbd2_revoke_table_s *revoke;
+
+        revoke = journal->j_revoke;
+
+        for (i = 0; i < revoke->hash_size; i++) {
+                hash_list = &revoke->hash_table[i];
+                while (!list_empty(hash_list)) {
+                        record = (struct jbd2_revoke_record_s*) hash_list->next;
+                        list_del(&record->hash);
+                        kmem_cache_free(jbd2_revoke_record_cache, record);
+                }
+        }
+}