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Diffstat (limited to 'e2fsprogs/e2fsck/revoke.c')
| -rw-r--r-- | e2fsprogs/e2fsck/revoke.c | 640 |
1 files changed, 0 insertions, 640 deletions
diff --git a/e2fsprogs/e2fsck/revoke.c b/e2fsprogs/e2fsck/revoke.c deleted file mode 100644 index 388bf5b..0000000 --- a/e2fsprogs/e2fsck/revoke.c +++ /dev/null @@ -1,640 +0,0 @@ -/* - * 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); -} - -static 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_var; - - revoke_var = journal->j_revoke; - - for (i = 0; i < revoke_var->hash_size; i++) { - hash_list = &revoke_var->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); - } - } -} - |