| /* |
| * 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| * buffer has not been revoked, and cancel_revoke |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/sched.h> |
| #include <linux/fs.h> |
| #include <linux/jbd.h> |
| #include <linux/errno.h> |
| #include <linux/slab.h> |
| #include <linux/locks.h> |
| #include <linux/list.h> |
| #include <linux/smp_lock.h> |
| #include <linux/init.h> |
| #endif |
| |
| static kmem_cache_t *revoke_record_cache; |
| static kmem_cache_t *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 jbd_revoke_record_s |
| { |
| struct list_head hash; |
| tid_t sequence; /* Used for recovery only */ |
| unsigned long blocknr; |
| }; |
| |
| |
| /* The revoke table is just a simple hash table of revoke records. */ |
| struct jbd_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 jbd_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 block) |
| { |
| struct jbd_revoke_table_s *table = journal->j_revoke; |
| int hash_shift = table->hash_shift; |
| |
| return ((block << (hash_shift - 6)) ^ |
| (block >> 13) ^ |
| (block << (hash_shift - 12))) & (table->hash_size - 1); |
| } |
| |
| int insert_revoke_hash(journal_t *journal, unsigned long blocknr, tid_t seq) |
| { |
| struct list_head *hash_list; |
| struct jbd_revoke_record_s *record; |
| |
| #ifdef __KERNEL__ |
| repeat: |
| #endif |
| record = kmem_cache_alloc(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)]; |
| list_add(&record->hash, hash_list); |
| return 0; |
| |
| oom: |
| #ifdef __KERNEL__ |
| if (!journal_oom_retry) |
| return -ENOMEM; |
| jbd_debug(1, "ENOMEM in " __FUNCTION__ ", retrying.\n"); |
| current->policy |= SCHED_YIELD; |
| schedule(); |
| goto repeat; |
| #else |
| return -ENOMEM; |
| #endif |
| } |
| |
| /* Find a revoke record in the journal's hash table. */ |
| |
| static struct jbd_revoke_record_s *find_revoke_record(journal_t *journal, |
| unsigned long blocknr) |
| { |
| struct list_head *hash_list; |
| struct jbd_revoke_record_s *record; |
| |
| hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)]; |
| |
| record = (struct jbd_revoke_record_s *) hash_list->next; |
| while (&(record->hash) != hash_list) { |
| if (record->blocknr == blocknr) |
| return record; |
| record = (struct jbd_revoke_record_s *) record->hash.next; |
| } |
| return NULL; |
| } |
| |
| int __init journal_init_revoke_caches(void) |
| { |
| revoke_record_cache = kmem_cache_create("revoke_record", |
| sizeof(struct jbd_revoke_record_s), |
| 0, SLAB_HWCACHE_ALIGN, NULL, NULL); |
| if (revoke_record_cache == 0) |
| return -ENOMEM; |
| |
| revoke_table_cache = kmem_cache_create("revoke_table", |
| sizeof(struct jbd_revoke_table_s), |
| 0, 0, NULL, NULL); |
| if (revoke_table_cache == 0) { |
| kmem_cache_destroy(revoke_record_cache); |
| revoke_record_cache = NULL; |
| return -ENOMEM; |
| } |
| return 0; |
| } |
| |
| void journal_destroy_revoke_caches(void) |
| { |
| kmem_cache_destroy(revoke_record_cache); |
| revoke_record_cache = 0; |
| kmem_cache_destroy(revoke_table_cache); |
| revoke_table_cache = 0; |
| } |
| |
| /* Initialise the revoke table for a given journal to a given size. */ |
| |
| int journal_init_revoke(journal_t *journal, int hash_size) |
| { |
| int shift, tmp; |
| |
| J_ASSERT (journal->j_revoke == NULL); |
| |
| journal->j_revoke = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL); |
| if (!journal->j_revoke) |
| return -ENOMEM; |
| |
| /* 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; |
| |
| shift = 0; |
| tmp = hash_size; |
| while((tmp >>= 1UL) != 0UL) |
| shift++; |
| 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(revoke_table_cache, journal->j_revoke); |
| journal->j_revoke = NULL; |
| return -ENOMEM; |
| } |
| |
| for (tmp = 0; tmp < hash_size; tmp++) |
| INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]); |
| |
| return 0; |
| } |
| |
| /* Destoy a journal's revoke table. The table must already be empty! */ |
| |
| void journal_destroy_revoke(journal_t *journal) |
| { |
| struct jbd_revoke_table_s *table; |
| struct list_head *hash_list; |
| int i; |
| |
| table = journal->j_revoke; |
| 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(revoke_table_cache, table); |
| journal->j_revoke = NULL; |
| } |
| |
| |
| #ifdef __KERNEL__ |
| |
| /* |
| * 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 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, journal_revoke() will decrement its b_count |
| * by one. |
| */ |
| |
| int journal_revoke(handle_t *handle, unsigned long blocknr, |
| struct buffer_head *bh_in) |
| { |
| struct buffer_head *bh = NULL; |
| journal_t *journal; |
| kdev_t dev; |
| int err; |
| |
| if (bh_in) |
| BUFFER_TRACE(bh_in, "enter"); |
| |
| journal = handle->h_transaction->t_journal; |
| if (!journal_set_features(journal, 0, 0, JFS_FEATURE_INCOMPAT_REVOKE)){ |
| J_ASSERT (!"Cannot set revoke feature!"); |
| return -EINVAL; |
| } |
| |
| dev = journal->j_fs_dev; |
| bh = bh_in; |
| |
| if (!bh) { |
| bh = get_hash_table(dev, 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 = get_hash_table(dev, blocknr, journal->j_blocksize); |
| if (bh2) { |
| /* ... and it has RevokeValid status... */ |
| if ((bh2 != bh) && |
| test_bit(BH_RevokeValid, &bh2->b_state)) |
| /* ...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, test_bit(BH_Revoked, & |
| bh2->b_state)); |
| __brelse(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) { |
| J_ASSERT_BH(bh, !test_bit(BH_Revoked, &bh->b_state)); |
| set_bit(BH_Revoked, &bh->b_state); |
| set_bit(BH_RevokeValid, &bh->b_state); |
| if (bh_in) { |
| BUFFER_TRACE(bh_in, "call journal_forget"); |
| journal_forget(handle, bh_in); |
| } else { |
| BUFFER_TRACE(bh, "call brelse"); |
| __brelse(bh); |
| } |
| } |
| |
| lock_journal(journal); |
| jbd_debug(2, "insert revoke for block %lu, bh_in=%p\n", blocknr, bh_in); |
| err = insert_revoke_hash(journal, blocknr, |
| handle->h_transaction->t_tid); |
| unlock_journal(journal); |
| BUFFER_TRACE(bh_in, "exit"); |
| return err; |
| } |
| |
| /* |
| * Cancel an outstanding revoke. For use only internally by the |
| * journaling code (called from journal_get_write_access). |
| * |
| * We trust the BH_Revoked bit 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 journal_cancel_revoke(handle_t *handle, struct journal_head *jh) |
| { |
| struct jbd_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_and_set_bit(BH_RevokeValid, &bh->b_state)) |
| need_cancel = (test_and_clear_bit(BH_Revoked, &bh->b_state)); |
| else { |
| need_cancel = 1; |
| clear_bit(BH_Revoked, &bh->b_state); |
| } |
| |
| if (need_cancel) { |
| record = find_revoke_record(journal, bh->b_blocknr); |
| if (record) { |
| jbd_debug(4, "cancelled existing revoke on " |
| "blocknr %lu\n", bh->b_blocknr); |
| list_del(&record->hash); |
| kmem_cache_free(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 && !bh->b_pprev) { |
| struct buffer_head *bh2; |
| bh2 = get_hash_table(bh->b_dev, bh->b_blocknr, bh->b_size); |
| if (bh2) { |
| clear_bit(BH_Revoked, &bh2->b_state); |
| __brelse(bh2); |
| } |
| } |
| |
| return did_revoke; |
| } |
| |
| |
| /* |
| * 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 journal_write_revoke_records(journal_t *journal, |
| transaction_t *transaction) |
| { |
| struct journal_head *descriptor; |
| struct jbd_revoke_record_s *record; |
| struct jbd_revoke_table_s *revoke; |
| struct list_head *hash_list; |
| int i, offset, count; |
| |
| descriptor = NULL; |
| offset = 0; |
| count = 0; |
| 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 jbd_revoke_record_s *) |
| hash_list->next; |
| write_one_revoke_record(journal, transaction, |
| &descriptor, &offset, |
| record); |
| count++; |
| list_del(&record->hash); |
| kmem_cache_free(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 jbd_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 |
| 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 = journal_get_descriptor_buffer(journal); |
| if (!descriptor) |
| return; |
| header = (journal_header_t *) &jh2bh(descriptor)->b_data[0]; |
| header->h_magic = htonl(JFS_MAGIC_NUMBER); |
| header->h_blocktype = htonl(JFS_REVOKE_BLOCK); |
| header->h_sequence = htonl(transaction->t_tid); |
| |
| /* Record it so that we can wait for IO completion later */ |
| JBUFFER_TRACE(descriptor, "file as BJ_LogCtl"); |
| journal_file_buffer(descriptor, transaction, BJ_LogCtl); |
| |
| offset = sizeof(journal_revoke_header_t); |
| *descriptorp = descriptor; |
| } |
| |
| * ((unsigned int *)(&jh2bh(descriptor)->b_data[offset])) = |
| htonl(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) |
| { |
| journal_revoke_header_t *header; |
| |
| if (is_journal_aborted(journal)) { |
| JBUFFER_TRACE(descriptor, "brelse"); |
| __brelse(jh2bh(descriptor)); |
| return; |
| } |
| |
| header = (journal_revoke_header_t *) jh2bh(descriptor)->b_data; |
| header->r_count = htonl(offset); |
| set_bit(BH_JWrite, &jh2bh(descriptor)->b_state); |
| { |
| struct buffer_head *bh = jh2bh(descriptor); |
| BUFFER_TRACE(bh, "write"); |
| ll_rw_block (WRITE, 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 journal_set_revoke(journal_t *journal, |
| unsigned long blocknr, |
| tid_t sequence) |
| { |
| struct jbd_revoke_record_s *record; |
| |
| record = find_revoke_record(journal, blocknr); |
| if (record) { |
| /* If we have multiple occurences, 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 journal_test_revoke(journal_t *journal, |
| unsigned long blocknr, |
| tid_t sequence) |
| { |
| struct jbd_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 journal_clear_revoke(journal_t *journal) |
| { |
| int i; |
| struct list_head *hash_list; |
| struct jbd_revoke_record_s *record; |
| struct jbd_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 jbd_revoke_record_s*) hash_list->next; |
| list_del(&record->hash); |
| kmem_cache_free(revoke_record_cache, record); |
| } |
| } |
| } |
| |