diff options
Diffstat (limited to 'fs/jbd/revoke.c')
| -rw-r--r-- | fs/jbd/revoke.c | 733 |
1 files changed, 0 insertions, 733 deletions
diff --git a/fs/jbd/revoke.c b/fs/jbd/revoke.c deleted file mode 100644 index dcead636c33b..000000000000 --- a/fs/jbd/revoke.c +++ /dev/null @@ -1,733 +0,0 @@ -/* - * linux/fs/jbd/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. - * - * We cache revoke status of a buffer in the current transaction in b_states - * bits. As the name says, revokevalid flag indicates that the cached revoke - * status of a buffer is valid and we can rely on the cached status. - * - * 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. - * - * Locking rules: - * We keep two hash tables of revoke records. One hashtable belongs to the - * running transaction (is pointed to by journal->j_revoke), the other one - * belongs to the committing transaction. Accesses to the second hash table - * happen only from the kjournald and no other thread touches this table. Also - * journal_switch_revoke_table() which switches which hashtable belongs to the - * running and which to the committing transaction is called only from - * kjournald. Therefore we need no locks when accessing the hashtable belonging - * to the committing transaction. - * - * All users operating on the hash table belonging to the running transaction - * have a handle to the transaction. Therefore they are safe from kjournald - * switching hash tables under them. For operations on the lists of entries in - * the hash table j_revoke_lock is used. - * - * Finally, also replay code uses the hash tables but at this moment no one else - * can touch them (filesystem isn't mounted yet) and hence no locking is - * needed. - */ - -#ifndef __KERNEL__ -#include "jfs_user.h" -#else -#include <linux/time.h> -#include <linux/fs.h> -#include <linux/jbd.h> -#include <linux/errno.h> -#include <linux/slab.h> -#include <linux/list.h> -#include <linux/init.h> -#include <linux/bio.h> -#endif -#include <linux/log2.h> -#include <linux/hash.h> - -static struct kmem_cache *revoke_record_cache; -static struct kmem_cache *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 int 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 *, int); -static void flush_descriptor(journal_t *, struct journal_head *, int, int); -#endif - -/* Utility functions to maintain the revoke table */ - -static inline int hash(journal_t *journal, unsigned int block) -{ - struct jbd_revoke_table_s *table = journal->j_revoke; - - return hash_32(block, table->hash_shift); -} - -static int insert_revoke_hash(journal_t *journal, unsigned int blocknr, - tid_t seq) -{ - struct list_head *hash_list; - struct jbd_revoke_record_s *record; - -repeat: - 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)]; - 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", __func__); - yield(); - goto repeat; -} - -/* Find a revoke record in the journal's hash table. */ - -static struct jbd_revoke_record_s *find_revoke_record(journal_t *journal, - unsigned int blocknr) -{ - struct list_head *hash_list; - struct jbd_revoke_record_s *record; - - hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)]; - - spin_lock(&journal->j_revoke_lock); - record = (struct jbd_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 jbd_revoke_record_s *) record->hash.next; - } - spin_unlock(&journal->j_revoke_lock); - return NULL; -} - -void journal_destroy_revoke_caches(void) -{ - if (revoke_record_cache) { - kmem_cache_destroy(revoke_record_cache); - revoke_record_cache = NULL; - } - if (revoke_table_cache) { - kmem_cache_destroy(revoke_table_cache); - revoke_table_cache = NULL; - } -} - -int __init journal_init_revoke_caches(void) -{ - J_ASSERT(!revoke_record_cache); - J_ASSERT(!revoke_table_cache); - - revoke_record_cache = kmem_cache_create("revoke_record", - sizeof(struct jbd_revoke_record_s), - 0, - SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY, - NULL); - if (!revoke_record_cache) - goto record_cache_failure; - - revoke_table_cache = kmem_cache_create("revoke_table", - sizeof(struct jbd_revoke_table_s), - 0, SLAB_TEMPORARY, NULL); - if (!revoke_table_cache) - goto table_cache_failure; - - return 0; - -table_cache_failure: - journal_destroy_revoke_caches(); -record_cache_failure: - return -ENOMEM; -} - -static struct jbd_revoke_table_s *journal_init_revoke_table(int hash_size) -{ - int i; - struct jbd_revoke_table_s *table; - - table = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL); - if (!table) - goto out; - - table->hash_size = hash_size; - table->hash_shift = ilog2(hash_size); - table->hash_table = - kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL); - if (!table->hash_table) { - kmem_cache_free(revoke_table_cache, table); - table = NULL; - goto out; - } - - for (i = 0; i < hash_size; i++) - INIT_LIST_HEAD(&table->hash_table[i]); - -out: - return table; -} - -static void journal_destroy_revoke_table(struct jbd_revoke_table_s *table) -{ - int i; - struct list_head *hash_list; - - 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); -} - -/* Initialise the revoke table for a given journal to a given size. */ -int journal_init_revoke(journal_t *journal, int hash_size) -{ - J_ASSERT(journal->j_revoke_table[0] == NULL); - J_ASSERT(is_power_of_2(hash_size)); - - journal->j_revoke_table[0] = journal_init_revoke_table(hash_size); - if (!journal->j_revoke_table[0]) - goto fail0; - - journal->j_revoke_table[1] = journal_init_revoke_table(hash_size); - if (!journal->j_revoke_table[1]) - goto fail1; - - journal->j_revoke = journal->j_revoke_table[1]; - - spin_lock_init(&journal->j_revoke_lock); - - return 0; - -fail1: - journal_destroy_revoke_table(journal->j_revoke_table[0]); -fail0: - return -ENOMEM; -} - -/* Destroy a journal's revoke table. The table must already be empty! */ -void journal_destroy_revoke(journal_t *journal) -{ - journal->j_revoke = NULL; - if (journal->j_revoke_table[0]) - journal_destroy_revoke_table(journal->j_revoke_table[0]); - if (journal->j_revoke_table[1]) - journal_destroy_revoke_table(journal->j_revoke_table[1]); -} - - -#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 int 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 (!journal_set_features(journal, 0, 0, JFS_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 journal_forget"); - journal_forget(handle, bh_in); - } else { - BUFFER_TRACE(bh, "call brelse"); - __brelse(bh); - } - } - - jbd_debug(2, "insert revoke for block %u, 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 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. - */ -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_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(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_clear_revoked_flags clears revoked flag of buffers in - * revoke table to reflect there is no revoked buffer in the next - * transaction which is going to be started. - */ -void journal_clear_buffer_revoked_flags(journal_t *journal) -{ - struct jbd_revoke_table_s *revoke = journal->j_revoke; - int i = 0; - - for (i = 0; i < revoke->hash_size; i++) { - struct list_head *hash_list; - struct list_head *list_entry; - hash_list = &revoke->hash_table[i]; - - list_for_each(list_entry, hash_list) { - struct jbd_revoke_record_s *record; - struct buffer_head *bh; - record = (struct jbd_revoke_record_s *)list_entry; - bh = __find_get_block(journal->j_fs_dev, - record->blocknr, - journal->j_blocksize); - if (bh) { - clear_buffer_revoked(bh); - __brelse(bh); - } - } - } -} - -/* 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 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. - */ -void journal_write_revoke_records(journal_t *journal, - transaction_t *transaction, int write_op) -{ - 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; - - /* 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 jbd_revoke_record_s *) - hash_list->next; - write_one_revoke_record(journal, transaction, - &descriptor, &offset, - record, write_op); - count++; - list_del(&record->hash); - kmem_cache_free(revoke_record_cache, record); - } - } - if (descriptor) - flush_descriptor(journal, descriptor, offset, write_op); - 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, - int write_op) -{ - 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, write_op); - 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 = cpu_to_be32(JFS_MAGIC_NUMBER); - header->h_blocktype = cpu_to_be32(JFS_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"); - journal_file_buffer(descriptor, transaction, BJ_LogCtl); - - offset = sizeof(journal_revoke_header_t); - *descriptorp = descriptor; - } - - * ((__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, int write_op) -{ - journal_revoke_header_t *header; - struct buffer_head *bh = jh2bh(descriptor); - - if (is_journal_aborted(journal)) { - put_bh(bh); - return; - } - - header = (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); - write_dirty_buffer(bh, write_op); -} -#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 int blocknr, - tid_t sequence) -{ - struct jbd_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 journal_test_revoke(journal_t *journal, - unsigned int 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); - } - } -} |