/* * linux/fs/jbd/journal.c * * Written by Stephen C. Tweedie , 1998 * * Copyright 1998 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. * * Generic filesystem journal-writing code; part of the ext2fs * journaling system. * * This file manages journals: areas of disk reserved for logging * transactional updates. This includes the kernel journaling thread * which is responsible for scheduling updates to the log. * * We do not actually manage the physical storage of the journal in this * file: that is left to a per-journal policy function, which allows us * to store the journal within a filesystem-specified area for ext2 * journaling (ext2 can use a reserved inode for storing the log). */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define CREATE_TRACE_POINTS #include #include #include EXPORT_SYMBOL(journal_start); EXPORT_SYMBOL(journal_restart); EXPORT_SYMBOL(journal_extend); EXPORT_SYMBOL(journal_stop); EXPORT_SYMBOL(journal_lock_updates); EXPORT_SYMBOL(journal_unlock_updates); EXPORT_SYMBOL(journal_get_write_access); EXPORT_SYMBOL(journal_get_create_access); EXPORT_SYMBOL(journal_get_undo_access); EXPORT_SYMBOL(journal_dirty_data); EXPORT_SYMBOL(journal_dirty_metadata); EXPORT_SYMBOL(journal_release_buffer); EXPORT_SYMBOL(journal_forget); #if 0 EXPORT_SYMBOL(journal_sync_buffer); #endif EXPORT_SYMBOL(journal_flush); EXPORT_SYMBOL(journal_revoke); EXPORT_SYMBOL(journal_init_dev); EXPORT_SYMBOL(journal_init_inode); EXPORT_SYMBOL(journal_update_format); EXPORT_SYMBOL(journal_check_used_features); EXPORT_SYMBOL(journal_check_available_features); EXPORT_SYMBOL(journal_set_features); EXPORT_SYMBOL(journal_create); EXPORT_SYMBOL(journal_load); EXPORT_SYMBOL(journal_destroy); EXPORT_SYMBOL(journal_abort); EXPORT_SYMBOL(journal_errno); EXPORT_SYMBOL(journal_ack_err); EXPORT_SYMBOL(journal_clear_err); EXPORT_SYMBOL(log_wait_commit); EXPORT_SYMBOL(log_start_commit); EXPORT_SYMBOL(journal_start_commit); EXPORT_SYMBOL(journal_force_commit_nested); EXPORT_SYMBOL(journal_wipe); EXPORT_SYMBOL(journal_blocks_per_page); EXPORT_SYMBOL(journal_invalidatepage); EXPORT_SYMBOL(journal_try_to_free_buffers); EXPORT_SYMBOL(journal_force_commit); static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *); static void __journal_abort_soft (journal_t *journal, int errno); static const char *journal_dev_name(journal_t *journal, char *buffer); /* * Helper function used to manage commit timeouts */ static void commit_timeout(unsigned long __data) { struct task_struct * p = (struct task_struct *) __data; wake_up_process(p); } /* * kjournald: The main thread function used to manage a logging device * journal. * * This kernel thread is responsible for two things: * * 1) COMMIT: Every so often we need to commit the current state of the * filesystem to disk. The journal thread is responsible for writing * all of the metadata buffers to disk. * * 2) CHECKPOINT: We cannot reuse a used section of the log file until all * of the data in that part of the log has been rewritten elsewhere on * the disk. Flushing these old buffers to reclaim space in the log is * known as checkpointing, and this thread is responsible for that job. */ static int kjournald(void *arg) { journal_t *journal = arg; transaction_t *transaction; /* * Set up an interval timer which can be used to trigger a commit wakeup * after the commit interval expires */ setup_timer(&journal->j_commit_timer, commit_timeout, (unsigned long)current); /* Record that the journal thread is running */ journal->j_task = current; wake_up(&journal->j_wait_done_commit); printk(KERN_INFO "kjournald starting. Commit interval %ld seconds\n", journal->j_commit_interval / HZ); /* * And now, wait forever for commit wakeup events. */ spin_lock(&journal->j_state_lock); loop: if (journal->j_flags & JFS_UNMOUNT) goto end_loop; jbd_debug(1, "commit_sequence=%d, commit_request=%d\n", journal->j_commit_sequence, journal->j_commit_request); if (journal->j_commit_sequence != journal->j_commit_request) { jbd_debug(1, "OK, requests differ\n"); spin_unlock(&journal->j_state_lock); del_timer_sync(&journal->j_commit_timer); journal_commit_transaction(journal); spin_lock(&journal->j_state_lock); goto loop; } wake_up(&journal->j_wait_done_commit); if (freezing(current)) { /* * The simpler the better. Flushing journal isn't a * good idea, because that depends on threads that may * be already stopped. */ jbd_debug(1, "Now suspending kjournald\n"); spin_unlock(&journal->j_state_lock); try_to_freeze(); spin_lock(&journal->j_state_lock); } else { /* * We assume on resume that commits are already there, * so we don't sleep */ DEFINE_WAIT(wait); int should_sleep = 1; prepare_to_wait(&journal->j_wait_commit, &wait, TASK_INTERRUPTIBLE); if (journal->j_commit_sequence != journal->j_commit_request) should_sleep = 0; transaction = journal->j_running_transaction; if (transaction && time_after_eq(jiffies, transaction->t_expires)) should_sleep = 0; if (journal->j_flags & JFS_UNMOUNT) should_sleep = 0; if (should_sleep) { spin_unlock(&journal->j_state_lock); schedule(); spin_lock(&journal->j_state_lock); } finish_wait(&journal->j_wait_commit, &wait); } jbd_debug(1, "kjournald wakes\n"); /* * Were we woken up by a commit wakeup event? */ transaction = journal->j_running_transaction; if (transaction && time_after_eq(jiffies, transaction->t_expires)) { journal->j_commit_request = transaction->t_tid; jbd_debug(1, "woke because of timeout\n"); } goto loop; end_loop: spin_unlock(&journal->j_state_lock); del_timer_sync(&journal->j_commit_timer); journal->j_task = NULL; wake_up(&journal->j_wait_done_commit); jbd_debug(1, "Journal thread exiting.\n"); return 0; } static int journal_start_thread(journal_t *journal) { struct task_struct *t; t = kthread_run(kjournald, journal, "kjournald"); if (IS_ERR(t)) return PTR_ERR(t); wait_event(journal->j_wait_done_commit, journal->j_task != NULL); return 0; } static void journal_kill_thread(journal_t *journal) { spin_lock(&journal->j_state_lock); journal->j_flags |= JFS_UNMOUNT; while (journal->j_task) { wake_up(&journal->j_wait_commit); spin_unlock(&journal->j_state_lock); wait_event(journal->j_wait_done_commit, journal->j_task == NULL); spin_lock(&journal->j_state_lock); } spin_unlock(&journal->j_state_lock); } /* * journal_write_metadata_buffer: write a metadata buffer to the journal. * * Writes a metadata buffer to a given disk block. The actual IO is not * performed but a new buffer_head is constructed which labels the data * to be written with the correct destination disk block. * * Any magic-number escaping which needs to be done will cause a * copy-out here. If the buffer happens to start with the * JFS_MAGIC_NUMBER, then we can't write it to the log directly: the * magic number is only written to the log for descripter blocks. In * this case, we copy the data and replace the first word with 0, and we * return a result code which indicates that this buffer needs to be * marked as an escaped buffer in the corresponding log descriptor * block. The missing word can then be restored when the block is read * during recovery. * * If the source buffer has already been modified by a new transaction * since we took the last commit snapshot, we use the frozen copy of * that data for IO. If we end up using the existing buffer_head's data * for the write, then we *have* to lock the buffer to prevent anyone * else from using and possibly modifying it while the IO is in * progress. * * The function returns a pointer to the buffer_heads to be used for IO. * * We assume that the journal has already been locked in this function. * * Return value: * <0: Error * >=0: Finished OK * * On success: * Bit 0 set == escape performed on the data * Bit 1 set == buffer copy-out performed (kfree the data after IO) */ int journal_write_metadata_buffer(transaction_t *transaction, struct journal_head *jh_in, struct journal_head **jh_out, unsigned int blocknr) { int need_copy_out = 0; int done_copy_out = 0; int do_escape = 0; char *mapped_data; struct buffer_head *new_bh; struct journal_head *new_jh; struct page *new_page; unsigned int new_offset; struct buffer_head *bh_in = jh2bh(jh_in); journal_t *journal = transaction->t_journal; /* * The buffer really shouldn't be locked: only the current committing * transaction is allowed to write it, so nobody else is allowed * to do any IO. * * akpm: except if we're journalling data, and write() output is * also part of a shared mapping, and another thread has * decided to launch a writepage() against this buffer. */ J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in)); new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL); /* keep subsequent assertions sane */ new_bh->b_state = 0; init_buffer(new_bh, NULL, NULL); atomic_set(&new_bh->b_count, 1); new_jh = journal_add_journal_head(new_bh); /* This sleeps */ /* * If a new transaction has already done a buffer copy-out, then * we use that version of the data for the commit. */ jbd_lock_bh_state(bh_in); repeat: if (jh_in->b_frozen_data) { done_copy_out = 1; new_page = virt_to_page(jh_in->b_frozen_data); new_offset = offset_in_page(jh_in->b_frozen_data); } else { new_page = jh2bh(jh_in)->b_page; new_offset = offset_in_page(jh2bh(jh_in)->b_data); } mapped_data = kmap_atomic(new_page, KM_USER0); /* * Check for escaping */ if (*((__be32 *)(mapped_data + new_offset)) == cpu_to_be32(JFS_MAGIC_NUMBER)) { need_copy_out = 1; do_escape = 1; } kunmap_atomic(mapped_data, KM_USER0); /* * Do we need to do a data copy? */ if (need_copy_out && !done_copy_out) { char *tmp; jbd_unlock_bh_state(bh_in); tmp = jbd_alloc(bh_in->b_size, GFP_NOFS); jbd_lock_bh_state(bh_in); if (jh_in->b_frozen_data) { jbd_free(tmp, bh_in->b_size); goto repeat; } jh_in->b_frozen_data = tmp; mapped_data = kmap_atomic(new_page, KM_USER0); memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size); kunmap_atomic(mapped_data, KM_USER0); new_page = virt_to_page(tmp); new_offset = offset_in_page(tmp); done_copy_out = 1; } /* * Did we need to do an escaping? Now we've done all the * copying, we can finally do so. */ if (do_escape) { mapped_data = kmap_atomic(new_page, KM_USER0); *((unsigned int *)(mapped_data + new_offset)) = 0; kunmap_atomic(mapped_data, KM_USER0); } set_bh_page(new_bh, new_page, new_offset); new_jh->b_transaction = NULL; new_bh->b_size = jh2bh(jh_in)->b_size; new_bh->b_bdev = transaction->t_journal->j_dev; new_bh->b_blocknr = blocknr; set_buffer_mapped(new_bh); set_buffer_dirty(new_bh); *jh_out = new_jh; /* * The to-be-written buffer needs to get moved to the io queue, * and the original buffer whose contents we are shadowing or * copying is moved to the transaction's shadow queue. */ JBUFFER_TRACE(jh_in, "file as BJ_Shadow"); spin_lock(&journal->j_list_lock); __journal_file_buffer(jh_in, transaction, BJ_Shadow); spin_unlock(&journal->j_list_lock); jbd_unlock_bh_state(bh_in); JBUFFER_TRACE(new_jh, "file as BJ_IO"); journal_file_buffer(new_jh, transaction, BJ_IO); return do_escape | (done_copy_out << 1); } /* * Allocation code for the journal file. Manage the space left in the * journal, so that we can begin checkpointing when appropriate. */ /* * __log_space_left: Return the number of free blocks left in the journal. * * Called with the journal already locked. * * Called under j_state_lock */ int __log_space_left(journal_t *journal) { int left = journal->j_free; assert_spin_locked(&journal->j_state_lock); /* * Be pessimistic here about the number of those free blocks which * might be required for log descriptor control blocks. */ #define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */ left -= MIN_LOG_RESERVED_BLOCKS; if (left <= 0) return 0; left -= (left >> 3); return left; } /* * Called under j_state_lock. Returns true if a transaction commit was started. */ int __log_start_commit(journal_t *journal, tid_t target) { /* * The only transaction we can possibly wait upon is the * currently running transaction (if it exists). Otherwise, * the target tid must be an old one. */ if (journal->j_running_transaction && journal->j_running_transaction->t_tid == target) { /* * We want a new commit: OK, mark the request and wakeup the * commit thread. We do _not_ do the commit ourselves. */ journal->j_commit_request = target; jbd_debug(1, "JBD: requesting commit %d/%d\n", journal->j_commit_request, journal->j_commit_sequence); wake_up(&journal->j_wait_commit); return 1; } else if (!tid_geq(journal->j_commit_request, target)) /* This should never happen, but if it does, preserve the evidence before kjournald goes into a loop and increments j_commit_sequence beyond all recognition. */ WARN_ONCE(1, "jbd: bad log_start_commit: %u %u %u %u\n", journal->j_commit_request, journal->j_commit_sequence, target, journal->j_running_transaction ? journal->j_running_transaction->t_tid : 0); return 0; } int log_start_commit(journal_t *journal, tid_t tid) { int ret; spin_lock(&journal->j_state_lock); ret = __log_start_commit(journal, tid); spin_unlock(&journal->j_state_lock); return ret; } /* * Force and wait upon a commit if the calling process is not within * transaction. This is used for forcing out undo-protected data which contains * bitmaps, when the fs is running out of space. * * We can only force the running transaction if we don't have an active handle; * otherwise, we will deadlock. * * Returns true if a transaction was started. */ int journal_force_commit_nested(journal_t *journal) { transaction_t *transaction = NULL; tid_t tid; spin_lock(&journal->j_state_lock); if (journal->j_running_transaction && !current->journal_info) { transaction = journal->j_running_transaction; __log_start_commit(journal, transaction->t_tid); } else if (journal->j_committing_transaction) transaction = journal->j_committing_transaction; if (!transaction) { spin_unlock(&journal->j_state_lock); return 0; /* Nothing to retry */ } tid = transaction->t_tid; spin_unlock(&journal->j_state_lock); log_wait_commit(journal, tid); return 1; } /* * Start a commit of the current running transaction (if any). Returns true * if a transaction is going to be committed (or is currently already * committing), and fills its tid in at *ptid */ int journal_start_commit(journal_t *journal, tid_t *ptid) { int ret = 0; spin_lock(&journal->j_state_lock); if (journal->j_running_transaction) { tid_t tid = journal->j_running_transaction->t_tid; __log_start_commit(journal, tid); /* There's a running transaction and we've just made sure * it's commit has been scheduled. */ if (ptid) *ptid = tid; ret = 1; } else if (journal->j_committing_transaction) { /* * If ext3_write_super() recently started a commit, then we * have to wait for completion of that transaction */ if (ptid) *ptid = journal->j_committing_transaction->t_tid; ret = 1; } spin_unlock(&journal->j_state_lock); return ret; } /* * Wait for a specified commit to complete. * The caller may not hold the journal lock. */ int log_wait_commit(journal_t *journal, tid_t tid) { int err = 0; #ifdef CONFIG_JBD_DEBUG spin_lock(&journal->j_state_lock); if (!tid_geq(journal->j_commit_request, tid)) { printk(KERN_EMERG "%s: error: j_commit_request=%d, tid=%d\n", __func__, journal->j_commit_request, tid); } spin_unlock(&journal->j_state_lock); #endif spin_lock(&journal->j_state_lock); while (tid_gt(tid, journal->j_commit_sequence)) { jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n", tid, journal->j_commit_sequence); wake_up(&journal->j_wait_commit); spin_unlock(&journal->j_state_lock); wait_event(journal->j_wait_done_commit, !tid_gt(tid, journal->j_commit_sequence)); spin_lock(&journal->j_state_lock); } spin_unlock(&journal->j_state_lock); if (unlikely(is_journal_aborted(journal))) { printk(KERN_EMERG "journal commit I/O error\n"); err = -EIO; } return err; } /* * Return 1 if a given transaction has not yet sent barrier request * connected with a transaction commit. If 0 is returned, transaction * may or may not have sent the barrier. Used to avoid sending barrier * twice in common cases. */ int journal_trans_will_send_data_barrier(journal_t *journal, tid_t tid) { int ret = 0; transaction_t *commit_trans; if (!(journal->j_flags & JFS_BARRIER)) return 0; spin_lock(&journal->j_state_lock); /* Transaction already committed? */ if (tid_geq(journal->j_commit_sequence, tid)) goto out; /* * Transaction is being committed and we already proceeded to * writing commit record? */ commit_trans = journal->j_committing_transaction; if (commit_trans && commit_trans->t_tid == tid && commit_trans->t_state >= T_COMMIT_RECORD) goto out; ret = 1; out: spin_unlock(&journal->j_state_lock); return ret; } EXPORT_SYMBOL(journal_trans_will_send_data_barrier); /* * Log buffer allocation routines: */ int journal_next_log_block(journal_t *journal, unsigned int *retp) { unsigned int blocknr; spin_lock(&journal->j_state_lock); J_ASSERT(journal->j_free > 1); blocknr = journal->j_head; journal->j_head++; journal->j_free--; if (journal->j_head == journal->j_last) journal->j_head = journal->j_first; spin_unlock(&journal->j_state_lock); return journal_bmap(journal, blocknr, retp); } /* * Conversion of logical to physical block numbers for the journal * * On external journals the journal blocks are identity-mapped, so * this is a no-op. If needed, we can use j_blk_offset - everything is * ready. */ int journal_bmap(journal_t *journal, unsigned int blocknr, unsigned int *retp) { int err = 0; unsigned int ret; if (journal->j_inode) { ret = bmap(journal->j_inode, blocknr); if (ret) *retp = ret; else { char b[BDEVNAME_SIZE]; printk(KERN_ALERT "%s: journal block not found " "at offset %u on %s\n", __func__, blocknr, bdevname(journal->j_dev, b)); err = -EIO; __journal_abort_soft(journal, err); } } else { *retp = blocknr; /* +journal->j_blk_offset */ } return err; } /* * We play buffer_head aliasing tricks to write data/metadata blocks to * the journal without copying their contents, but for journal * descriptor blocks we do need to generate bona fide buffers. * * After the caller of journal_get_descriptor_buffer() has finished modifying * the buffer's contents they really should run flush_dcache_page(bh->b_page). * But we don't bother doing that, so there will be coherency problems with * mmaps of blockdevs which hold live JBD-controlled filesystems. */ struct journal_head *journal_get_descriptor_buffer(journal_t *journal) { struct buffer_head *bh; unsigned int blocknr; int err; err = journal_next_log_block(journal, &blocknr); if (err) return NULL; bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); if (!bh) return NULL; lock_buffer(bh); memset(bh->b_data, 0, journal->j_blocksize); set_buffer_uptodate(bh); unlock_buffer(bh); BUFFER_TRACE(bh, "return this buffer"); return journal_add_journal_head(bh); } /* * Management for journal control blocks: functions to create and * destroy journal_t structures, and to initialise and read existing * journal blocks from disk. */ /* First: create and setup a journal_t object in memory. We initialise * very few fields yet: that has to wait until we have created the * journal structures from from scratch, or loaded them from disk. */ static journal_t * journal_init_common (void) { journal_t *journal; int err; journal = kzalloc(sizeof(*journal), GFP_KERNEL); if (!journal) goto fail; init_waitqueue_head(&journal->j_wait_transaction_locked); init_waitqueue_head(&journal->j_wait_logspace); init_waitqueue_head(&journal->j_wait_done_commit); init_waitqueue_head(&journal->j_wait_checkpoint); init_waitqueue_head(&journal->j_wait_commit); init_waitqueue_head(&journal->j_wait_updates); mutex_init(&journal->j_checkpoint_mutex); spin_lock_init(&journal->j_revoke_lock); spin_lock_init(&journal->j_list_lock); spin_lock_init(&journal->j_state_lock); journal->j_commit_interval = (HZ * JBD_DEFAULT_MAX_COMMIT_AGE); /* The journal is marked for error until we succeed with recovery! */ journal->j_flags = JFS_ABORT; /* Set up a default-sized revoke table for the new mount. */ err = journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH); if (err) { kfree(journal); goto fail; } return journal; fail: return NULL; } /* journal_init_dev and journal_init_inode: * * Create a journal structure assigned some fixed set of disk blocks to * the journal. We don't actually touch those disk blocks yet, but we * need to set up all of the mapping information to tell the journaling * system where the journal blocks are. * */ /** * journal_t * journal_init_dev() - creates and initialises a journal structure * @bdev: Block device on which to create the journal * @fs_dev: Device which hold journalled filesystem for this journal. * @start: Block nr Start of journal. * @len: Length of the journal in blocks. * @blocksize: blocksize of journalling device * * Returns: a newly created journal_t * * * journal_init_dev creates a journal which maps a fixed contiguous * range of blocks on an arbitrary block device. * */ journal_t * journal_init_dev(struct block_device *bdev, struct block_device *fs_dev, int start, int len, int blocksize) { journal_t *journal = journal_init_common(); struct buffer_head *bh; int n; if (!journal) return NULL; /* journal descriptor can store up to n blocks -bzzz */ journal->j_blocksize = blocksize; n = journal->j_blocksize / sizeof(journal_block_tag_t); journal->j_wbufsize = n; journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL); if (!journal->j_wbuf) { printk(KERN_ERR "%s: Can't allocate bhs for commit thread\n", __func__); goto out_err; } journal->j_dev = bdev; journal->j_fs_dev = fs_dev; journal->j_blk_offset = start; journal->j_maxlen = len; bh = __getblk(journal->j_dev, start, journal->j_blocksize); if (!bh) { printk(KERN_ERR "%s: Cannot get buffer for journal superblock\n", __func__); goto out_err; } journal->j_sb_buffer = bh; journal->j_superblock = (journal_superblock_t *)bh->b_data; return journal; out_err: kfree(journal->j_wbuf); kfree(journal); return NULL; } /** * journal_t * journal_init_inode () - creates a journal which maps to a inode. * @inode: An inode to create the journal in * * journal_init_inode creates a journal which maps an on-disk inode as * the journal. The inode must exist already, must support bmap() and * must have all data blocks preallocated. */ journal_t * journal_init_inode (struct inode *inode) { struct buffer_head *bh; journal_t *journal = journal_init_common(); int err; int n; unsigned int blocknr; if (!journal) return NULL; journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev; journal->j_inode = inode; jbd_debug(1, "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n", journal, inode->i_sb->s_id, inode->i_ino, (long long) inode->i_size, inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize); journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits; journal->j_blocksize = inode->i_sb->s_blocksize; /* journal descriptor can store up to n blocks -bzzz */ n = journal->j_blocksize / sizeof(journal_block_tag_t); journal->j_wbufsize = n; journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL); if (!journal->j_wbuf) { printk(KERN_ERR "%s: Can't allocate bhs for commit thread\n", __func__); goto out_err; } err = journal_bmap(journal, 0, &blocknr); /* If that failed, give up */ if (err) { printk(KERN_ERR "%s: Cannot locate journal superblock\n", __func__); goto out_err; } bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); if (!bh) { printk(KERN_ERR "%s: Cannot get buffer for journal superblock\n", __func__); goto out_err; } journal->j_sb_buffer = bh; journal->j_superblock = (journal_superblock_t *)bh->b_data; return journal; out_err: kfree(journal->j_wbuf); kfree(journal); return NULL; } /* * If the journal init or create aborts, we need to mark the journal * superblock as being NULL to prevent the journal destroy from writing * back a bogus superblock. */ static void journal_fail_superblock (journal_t *journal) { struct buffer_head *bh = journal->j_sb_buffer; brelse(bh); journal->j_sb_buffer = NULL; } /* * Given a journal_t structure, initialise the various fields for * startup of a new journaling session. We use this both when creating * a journal, and after recovering an old journal to reset it for * subsequent use. */ static int journal_reset(journal_t *journal) { journal_superblock_t *sb = journal->j_superblock; unsigned int first, last; first = be32_to_cpu(sb->s_first); last = be32_to_cpu(sb->s_maxlen); if (first + JFS_MIN_JOURNAL_BLOCKS > last + 1) { printk(KERN_ERR "JBD: Journal too short (blocks %u-%u).\n", first, last); journal_fail_superblock(journal); return -EINVAL; } journal->j_first = first; journal->j_last = last; journal->j_head = first; journal->j_tail = first; journal->j_free = last - first; journal->j_tail_sequence = journal->j_transaction_sequence; journal->j_commit_sequence = journal->j_transaction_sequence - 1; journal->j_commit_request = journal->j_commit_sequence; journal->j_max_transaction_buffers = journal->j_maxlen / 4; /* Add the dynamic fields and write it to disk. */ journal_update_superblock(journal, 1); return journal_start_thread(journal); } /** * int journal_create() - Initialise the new journal file * @journal: Journal to create. This structure must have been initialised * * Given a journal_t structure which tells us which disk blocks we can * use, create a new journal superblock and initialise all of the * journal fields from scratch. **/ int journal_create(journal_t *journal) { unsigned int blocknr; struct buffer_head *bh; journal_superblock_t *sb; int i, err; if (journal->j_maxlen < JFS_MIN_JOURNAL_BLOCKS) { printk (KERN_ERR "Journal length (%d blocks) too short.\n", journal->j_maxlen); journal_fail_superblock(journal); return -EINVAL; } if (journal->j_inode == NULL) { /* * We don't know what block to start at! */ printk(KERN_EMERG "%s: creation of journal on external device!\n", __func__); BUG(); } /* Zero out the entire journal on disk. We cannot afford to have any blocks on disk beginning with JFS_MAGIC_NUMBER. */ jbd_debug(1, "JBD: Zeroing out journal blocks...\n"); for (i = 0; i < journal->j_maxlen; i++) { err = journal_bmap(journal, i, &blocknr); if (err) return err; bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); if (unlikely(!bh)) return -ENOMEM; lock_buffer(bh); memset (bh->b_data, 0, journal->j_blocksize); BUFFER_TRACE(bh, "marking dirty"); mark_buffer_dirty(bh); BUFFER_TRACE(bh, "marking uptodate"); set_buffer_uptodate(bh); unlock_buffer(bh); __brelse(bh); } sync_blockdev(journal->j_dev); jbd_debug(1, "JBD: journal cleared.\n"); /* OK, fill in the initial static fields in the new superblock */ sb = journal->j_superblock; sb->s_header.h_magic = cpu_to_be32(JFS_MAGIC_NUMBER); sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2); sb->s_blocksize = cpu_to_be32(journal->j_blocksize); sb->s_maxlen = cpu_to_be32(journal->j_maxlen); sb->s_first = cpu_to_be32(1); journal->j_transaction_sequence = 1; journal->j_flags &= ~JFS_ABORT; journal->j_format_version = 2; return journal_reset(journal); } /** * void journal_update_superblock() - Update journal sb on disk. * @journal: The journal to update. * @wait: Set to '0' if you don't want to wait for IO completion. * * Update a journal's dynamic superblock fields and write it to disk, * optionally waiting for the IO to complete. */ void journal_update_superblock(journal_t *journal, int wait) { journal_superblock_t *sb = journal->j_superblock; struct buffer_head *bh = journal->j_sb_buffer; /* * As a special case, if the on-disk copy is already marked as needing * no recovery (s_start == 0) and there are no outstanding transactions * in the filesystem, then we can safely defer the superblock update * until the next commit by setting JFS_FLUSHED. This avoids * attempting a write to a potential-readonly device. */ if (sb->s_start == 0 && journal->j_tail_sequence == journal->j_transaction_sequence) { jbd_debug(1,"JBD: Skipping superblock update on recovered sb " "(start %u, seq %d, errno %d)\n", journal->j_tail, journal->j_tail_sequence, journal->j_errno); goto out; } if (buffer_write_io_error(bh)) { char b[BDEVNAME_SIZE]; /* * Oh, dear. A previous attempt to write the journal * superblock failed. This could happen because the * USB device was yanked out. Or it could happen to * be a transient write error and maybe the block will * be remapped. Nothing we can do but to retry the * write and hope for the best. */ printk(KERN_ERR "JBD: previous I/O error detected " "for journal superblock update for %s.\n", journal_dev_name(journal, b)); clear_buffer_write_io_error(bh); set_buffer_uptodate(bh); } spin_lock(&journal->j_state_lock); jbd_debug(1,"JBD: updating superblock (start %u, seq %d, errno %d)\n", journal->j_tail, journal->j_tail_sequence, journal->j_errno); sb->s_sequence = cpu_to_be32(journal->j_tail_sequence); sb->s_start = cpu_to_be32(journal->j_tail); sb->s_errno = cpu_to_be32(journal->j_errno); spin_unlock(&journal->j_state_lock); BUFFER_TRACE(bh, "marking dirty"); mark_buffer_dirty(bh); if (wait) { sync_dirty_buffer(bh); if (buffer_write_io_error(bh)) { char b[BDEVNAME_SIZE]; printk(KERN_ERR "JBD: I/O error detected " "when updating journal superblock for %s.\n", journal_dev_name(journal, b)); clear_buffer_write_io_error(bh); set_buffer_uptodate(bh); } } else write_dirty_buffer(bh, WRITE); trace_jbd_update_superblock_end(journal, wait); out: /* If we have just flushed the log (by marking s_start==0), then * any future commit will have to be careful to update the * superblock again to re-record the true start of the log. */ spin_lock(&journal->j_state_lock); if (sb->s_start) journal->j_flags &= ~JFS_FLUSHED; else journal->j_flags |= JFS_FLUSHED; spin_unlock(&journal->j_state_lock); } /* * Read the superblock for a given journal, performing initial * validation of the format. */ static int journal_get_superblock(journal_t *journal) { struct buffer_head *bh; journal_superblock_t *sb; int err = -EIO; bh = journal->j_sb_buffer; J_ASSERT(bh != NULL); if (!buffer_uptodate(bh)) { ll_rw_block(READ, 1, &bh); wait_on_buffer(bh); if (!buffer_uptodate(bh)) { printk (KERN_ERR "JBD: IO error reading journal superblock\n"); goto out; } } sb = journal->j_superblock; err = -EINVAL; if (sb->s_header.h_magic != cpu_to_be32(JFS_MAGIC_NUMBER) || sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) { printk(KERN_WARNING "JBD: no valid journal superblock found\n"); goto out; } switch(be32_to_cpu(sb->s_header.h_blocktype)) { case JFS_SUPERBLOCK_V1: journal->j_format_version = 1; break; case JFS_SUPERBLOCK_V2: journal->j_format_version = 2; break; default: printk(KERN_WARNING "JBD: unrecognised superblock format ID\n"); goto out; } if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen) journal->j_maxlen = be32_to_cpu(sb->s_maxlen); else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) { printk (KERN_WARNING "JBD: journal file too short\n"); goto out; } if (be32_to_cpu(sb->s_first) == 0 || be32_to_cpu(sb->s_first) >= journal->j_maxlen) { printk(KERN_WARNING "JBD: Invalid start block of journal: %u\n", be32_to_cpu(sb->s_first)); goto out; } return 0; out: journal_fail_superblock(journal); return err; } /* * Load the on-disk journal superblock and read the key fields into the * journal_t. */ static int load_superblock(journal_t *journal) { int err; journal_superblock_t *sb; err = journal_get_superblock(journal); if (err) return err; sb = journal->j_superblock; journal->j_tail_sequence = be32_to_cpu(sb->s_sequence); journal->j_tail = be32_to_cpu(sb->s_start); journal->j_first = be32_to_cpu(sb->s_first); journal->j_last = be32_to_cpu(sb->s_maxlen); journal->j_errno = be32_to_cpu(sb->s_errno); return 0; } /** * int journal_load() - Read journal from disk. * @journal: Journal to act on. * * Given a journal_t structure which tells us which disk blocks contain * a journal, read the journal from disk to initialise the in-memory * structures. */ int journal_load(journal_t *journal) { int err; journal_superblock_t *sb; err = load_superblock(journal); if (err) return err; sb = journal->j_superblock; /* If this is a V2 superblock, then we have to check the * features flags on it. */ if (journal->j_format_version >= 2) { if ((sb->s_feature_ro_compat & ~cpu_to_be32(JFS_KNOWN_ROCOMPAT_FEATURES)) || (sb->s_feature_incompat & ~cpu_to_be32(JFS_KNOWN_INCOMPAT_FEATURES))) { printk (KERN_WARNING "JBD: Unrecognised features on journal\n"); return -EINVAL; } } /* Let the recovery code check whether it needs to recover any * data from the journal. */ if (journal_recover(journal)) goto recovery_error; /* OK, we've finished with the dynamic journal bits: * reinitialise the dynamic contents of the superblock in memory * and reset them on disk. */ if (journal_reset(journal)) goto recovery_error; journal->j_flags &= ~JFS_ABORT; journal->j_flags |= JFS_LOADED; return 0; recovery_error: printk (KERN_WARNING "JBD: recovery failed\n"); return -EIO; } /** * void journal_destroy() - Release a journal_t structure. * @journal: Journal to act on. * * Release a journal_t structure once it is no longer in use by the * journaled object. * Return <0 if we couldn't clean up the journal. */ int journal_destroy(journal_t *journal) { int err = 0; /* Wait for the commit thread to wake up and die. */ journal_kill_thread(journal); /* Force a final log commit */ if (journal->j_running_transaction) journal_commit_transaction(journal); /* Force any old transactions to disk */ /* Totally anal locking here... */ spin_lock(&journal->j_list_lock); while (journal->j_checkpoint_transactions != NULL) { spin_unlock(&journal->j_list_lock); log_do_checkpoint(journal); spin_lock(&journal->j_list_lock); } J_ASSERT(journal->j_running_transaction == NULL); J_ASSERT(journal->j_committing_transaction == NULL); J_ASSERT(journal->j_checkpoint_transactions == NULL); spin_unlock(&journal->j_list_lock); if (journal->j_sb_buffer) { if (!is_journal_aborted(journal)) { /* We can now mark the journal as empty. */ journal->j_tail = 0; journal->j_tail_sequence = ++journal->j_transaction_sequence; journal_update_superblock(journal, 1); } else { err = -EIO; } brelse(journal->j_sb_buffer); } if (journal->j_inode) iput(journal->j_inode); if (journal->j_revoke) journal_destroy_revoke(journal); kfree(journal->j_wbuf); kfree(journal); return err; } /** *int journal_check_used_features () - Check if features specified are used. * @journal: Journal to check. * @compat: bitmask of compatible features * @ro: bitmask of features that force read-only mount * @incompat: bitmask of incompatible features * * Check whether the journal uses all of a given set of * features. Return true (non-zero) if it does. **/ int journal_check_used_features (journal_t *journal, unsigned long compat, unsigned long ro, unsigned long incompat) { journal_superblock_t *sb; if (!compat && !ro && !incompat) return 1; if (journal->j_format_version == 1) return 0; sb = journal->j_superblock; if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) && ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) && ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat)) return 1; return 0; } /** * int journal_check_available_features() - Check feature set in journalling layer * @journal: Journal to check. * @compat: bitmask of compatible features * @ro: bitmask of features that force read-only mount * @incompat: bitmask of incompatible features * * Check whether the journaling code supports the use of * all of a given set of features on this journal. Return true * (non-zero) if it can. */ int journal_check_available_features (journal_t *journal, unsigned long compat, unsigned long ro, unsigned long incompat) { if (!compat && !ro && !incompat) return 1; /* We can support any known requested features iff the * superblock is in version 2. Otherwise we fail to support any * extended sb features. */ if (journal->j_format_version != 2) return 0; if ((compat & JFS_KNOWN_COMPAT_FEATURES) == compat && (ro & JFS_KNOWN_ROCOMPAT_FEATURES) == ro && (incompat & JFS_KNOWN_INCOMPAT_FEATURES) == incompat) return 1; return 0; } /** * int journal_set_features () - Mark a given journal feature in the superblock * @journal: Journal to act on. * @compat: bitmask of compatible features * @ro: bitmask of features that force read-only mount * @incompat: bitmask of incompatible features * * Mark a given journal feature as present on the * superblock. Returns true if the requested features could be set. * */ int journal_set_features (journal_t *journal, unsigned long compat, unsigned long ro, unsigned long incompat) { journal_superblock_t *sb; if (journal_check_used_features(journal, compat, ro, incompat)) return 1; if (!journal_check_available_features(journal, compat, ro, incompat)) return 0; jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n", compat, ro, incompat); sb = journal->j_superblock; sb->s_feature_compat |= cpu_to_be32(compat); sb->s_feature_ro_compat |= cpu_to_be32(ro); sb->s_feature_incompat |= cpu_to_be32(incompat); return 1; } /** * int journal_update_format () - Update on-disk journal structure. * @journal: Journal to act on. * * Given an initialised but unloaded journal struct, poke about in the * on-disk structure to update it to the most recent supported version. */ int journal_update_format (journal_t *journal) { journal_superblock_t *sb; int err; err = journal_get_superblock(journal); if (err) return err; sb = journal->j_superblock; switch (be32_to_cpu(sb->s_header.h_blocktype)) { case JFS_SUPERBLOCK_V2: return 0; case JFS_SUPERBLOCK_V1: return journal_convert_superblock_v1(journal, sb); default: break; } return -EINVAL; } static int journal_convert_superblock_v1(journal_t *journal, journal_superblock_t *sb) { int offset, blocksize; struct buffer_head *bh; printk(KERN_WARNING "JBD: Converting superblock from version 1 to 2.\n"); /* Pre-initialise new fields to zero */ offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb); blocksize = be32_to_cpu(sb->s_blocksize); memset(&sb->s_feature_compat, 0, blocksize-offset); sb->s_nr_users = cpu_to_be32(1); sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2); journal->j_format_version = 2; bh = journal->j_sb_buffer; BUFFER_TRACE(bh, "marking dirty"); mark_buffer_dirty(bh); sync_dirty_buffer(bh); return 0; } /** * int journal_flush () - Flush journal * @journal: Journal to act on. * * Flush all data for a given journal to disk and empty the journal. * Filesystems can use this when remounting readonly to ensure that * recovery does not need to happen on remount. */ int journal_flush(journal_t *journal) { int err = 0; transaction_t *transaction = NULL; unsigned int old_tail; spin_lock(&journal->j_state_lock); /* Force everything buffered to the log... */ if (journal->j_running_transaction) { transaction = journal->j_running_transaction; __log_start_commit(journal, transaction->t_tid); } else if (journal->j_committing_transaction) transaction = journal->j_committing_transaction; /* Wait for the log commit to complete... */ if (transaction) { tid_t tid = transaction->t_tid; spin_unlock(&journal->j_state_lock); log_wait_commit(journal, tid); } else { spin_unlock(&journal->j_state_lock); } /* ...and flush everything in the log out to disk. */ spin_lock(&journal->j_list_lock); while (!err && journal->j_checkpoint_transactions != NULL) { spin_unlock(&journal->j_list_lock); mutex_lock(&journal->j_checkpoint_mutex); err = log_do_checkpoint(journal); mutex_unlock(&journal->j_checkpoint_mutex); spin_lock(&journal->j_list_lock); } spin_unlock(&journal->j_list_lock); if (is_journal_aborted(journal)) return -EIO; cleanup_journal_tail(journal); /* Finally, mark the journal as really needing no recovery. * This sets s_start==0 in the underlying superblock, which is * the magic code for a fully-recovered superblock. Any future * commits of data to the journal will restore the current * s_start value. */ spin_lock(&journal->j_state_lock); old_tail = journal->j_tail; journal->j_tail = 0; spin_unlock(&journal->j_state_lock); journal_update_superblock(journal, 1); spin_lock(&journal->j_state_lock); journal->j_tail = old_tail; J_ASSERT(!journal->j_running_transaction); J_ASSERT(!journal->j_committing_transaction); J_ASSERT(!journal->j_checkpoint_transactions); J_ASSERT(journal->j_head == journal->j_tail); J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence); spin_unlock(&journal->j_state_lock); return 0; } /** * int journal_wipe() - Wipe journal contents * @journal: Journal to act on. * @write: flag (see below) * * Wipe out all of the contents of a journal, safely. This will produce * a warning if the journal contains any valid recovery information. * Must be called between journal_init_*() and journal_load(). * * If 'write' is non-zero, then we wipe out the journal on disk; otherwise * we merely suppress recovery. */ int journal_wipe(journal_t *journal, int write) { int err = 0; J_ASSERT (!(journal->j_flags & JFS_LOADED)); err = load_superblock(journal); if (err) return err; if (!journal->j_tail) goto no_recovery; printk (KERN_WARNING "JBD: %s recovery information on journal\n", write ? "Clearing" : "Ignoring"); err = journal_skip_recovery(journal); if (write) journal_update_superblock(journal, 1); no_recovery: return err; } /* * journal_dev_name: format a character string to describe on what * device this journal is present. */ static const char *journal_dev_name(journal_t *journal, char *buffer) { struct block_device *bdev; if (journal->j_inode) bdev = journal->j_inode->i_sb->s_bdev; else bdev = journal->j_dev; return bdevname(bdev, buffer); } /* * Journal abort has very specific semantics, which we describe * for journal abort. * * Two internal function, which provide abort to te jbd layer * itself are here. */ /* * Quick version for internal journal use (doesn't lock the journal). * Aborts hard --- we mark the abort as occurred, but do _nothing_ else, * and don't attempt to make any other journal updates. */ static void __journal_abort_hard(journal_t *journal) { transaction_t *transaction; char b[BDEVNAME_SIZE]; if (journal->j_flags & JFS_ABORT) return; printk(KERN_ERR "Aborting journal on device %s.\n", journal_dev_name(journal, b)); spin_lock(&journal->j_state_lock); journal->j_flags |= JFS_ABORT; transaction = journal->j_running_transaction; if (transaction) __log_start_commit(journal, transaction->t_tid); spin_unlock(&journal->j_state_lock); } /* Soft abort: record the abort error status in the journal superblock, * but don't do any other IO. */ static void __journal_abort_soft (journal_t *journal, int errno) { if (journal->j_flags & JFS_ABORT) return; if (!journal->j_errno) journal->j_errno = errno; __journal_abort_hard(journal); if (errno) journal_update_superblock(journal, 1); } /** * void journal_abort () - Shutdown the journal immediately. * @journal: the journal to shutdown. * @errno: an error number to record in the journal indicating * the reason for the shutdown. * * Perform a complete, immediate shutdown of the ENTIRE * journal (not of a single transaction). This operation cannot be * undone without closing and reopening the journal. * * The journal_abort function is intended to support higher level error * recovery mechanisms such as the ext2/ext3 remount-readonly error * mode. * * Journal abort has very specific semantics. Any existing dirty, * unjournaled buffers in the main filesystem will still be written to * disk by bdflush, but the journaling mechanism will be suspended * immediately and no further transaction commits will be honoured. * * Any dirty, journaled buffers will be written back to disk without * hitting the journal. Atomicity cannot be guaranteed on an aborted * filesystem, but we _do_ attempt to leave as much data as possible * behind for fsck to use for cleanup. * * Any attempt to get a new transaction handle on a journal which is in * ABORT state will just result in an -EROFS error return. A * journal_stop on an existing handle will return -EIO if we have * entered abort state during the update. * * Recursive transactions are not disturbed by journal abort until the * final journal_stop, which will receive the -EIO error. * * Finally, the journal_abort call allows the caller to supply an errno * which will be recorded (if possible) in the journal superblock. This * allows a client to record failure conditions in the middle of a * transaction without having to complete the transaction to record the * failure to disk. ext3_error, for example, now uses this * functionality. * * Errors which originate from within the journaling layer will NOT * supply an errno; a null errno implies that absolutely no further * writes are done to the journal (unless there are any already in * progress). * */ void journal_abort(journal_t *journal, int errno) { __journal_abort_soft(journal, errno); } /** * int journal_errno () - returns the journal's error state. * @journal: journal to examine. * * This is the errno numbet set with journal_abort(), the last * time the journal was mounted - if the journal was stopped * without calling abort this will be 0. * * If the journal has been aborted on this mount time -EROFS will * be returned. */ int journal_errno(journal_t *journal) { int err; spin_lock(&journal->j_state_lock); if (journal->j_flags & JFS_ABORT) err = -EROFS; else err = journal->j_errno; spin_unlock(&journal->j_state_lock); return err; } /** * int journal_clear_err () - clears the journal's error state * @journal: journal to act on. * * An error must be cleared or Acked to take a FS out of readonly * mode. */ int journal_clear_err(journal_t *journal) { int err = 0; spin_lock(&journal->j_state_lock); if (journal->j_flags & JFS_ABORT) err = -EROFS; else journal->j_errno = 0; spin_unlock(&journal->j_state_lock); return err; } /** * void journal_ack_err() - Ack journal err. * @journal: journal to act on. * * An error must be cleared or Acked to take a FS out of readonly * mode. */ void journal_ack_err(journal_t *journal) { spin_lock(&journal->j_state_lock); if (journal->j_errno) journal->j_flags |= JFS_ACK_ERR; spin_unlock(&journal->j_state_lock); } int journal_blocks_per_page(struct inode *inode) { return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits); } /* * Journal_head storage management */ static struct kmem_cache *journal_head_cache; #ifdef CONFIG_JBD_DEBUG static atomic_t nr_journal_heads = ATOMIC_INIT(0); #endif static int journal_init_journal_head_cache(void) { int retval; J_ASSERT(journal_head_cache == NULL); journal_head_cache = kmem_cache_create("journal_head", sizeof(struct journal_head), 0, /* offset */ SLAB_TEMPORARY, /* flags */ NULL); /* ctor */ retval = 0; if (!journal_head_cache) { retval = -ENOMEM; printk(KERN_EMERG "JBD: no memory for journal_head cache\n"); } return retval; } static void journal_destroy_journal_head_cache(void) { if (journal_head_cache) { kmem_cache_destroy(journal_head_cache); journal_head_cache = NULL; } } /* * journal_head splicing and dicing */ static struct journal_head *journal_alloc_journal_head(void) { struct journal_head *ret; #ifdef CONFIG_JBD_DEBUG atomic_inc(&nr_journal_heads); #endif ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS); if (ret == NULL) { jbd_debug(1, "out of memory for journal_head\n"); printk_ratelimited(KERN_NOTICE "ENOMEM in %s, retrying.\n", __func__); while (ret == NULL) { yield(); ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS); } } return ret; } static void journal_free_journal_head(struct journal_head *jh) { #ifdef CONFIG_JBD_DEBUG atomic_dec(&nr_journal_heads); memset(jh, JBD_POISON_FREE, sizeof(*jh)); #endif kmem_cache_free(journal_head_cache, jh); } /* * A journal_head is attached to a buffer_head whenever JBD has an * interest in the buffer. * * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit * is set. This bit is tested in core kernel code where we need to take * JBD-specific actions. Testing the zeroness of ->b_private is not reliable * there. * * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one. * * When a buffer has its BH_JBD bit set it is immune from being released by * core kernel code, mainly via ->b_count. * * A journal_head is detached from its buffer_head when the journal_head's * b_jcount reaches zero. Running transaction (b_transaction) and checkpoint * transaction (b_cp_transaction) hold their references to b_jcount. * * Various places in the kernel want to attach a journal_head to a buffer_head * _before_ attaching the journal_head to a transaction. To protect the * journal_head in this situation, journal_add_journal_head elevates the * journal_head's b_jcount refcount by one. The caller must call * journal_put_journal_head() to undo this. * * So the typical usage would be: * * (Attach a journal_head if needed. Increments b_jcount) * struct journal_head *jh = journal_add_journal_head(bh); * ... * (Get another reference for transaction) * journal_grab_journal_head(bh); * jh->b_transaction = xxx; * (Put original reference) * journal_put_journal_head(jh); */ /* * Give a buffer_head a journal_head. * * May sleep. */ struct journal_head *journal_add_journal_head(struct buffer_head *bh) { struct journal_head *jh; struct journal_head *new_jh = NULL; repeat: if (!buffer_jbd(bh)) { new_jh = journal_alloc_journal_head(); memset(new_jh, 0, sizeof(*new_jh)); } jbd_lock_bh_journal_head(bh); if (buffer_jbd(bh)) { jh = bh2jh(bh); } else { J_ASSERT_BH(bh, (atomic_read(&bh->b_count) > 0) || (bh->b_page && bh->b_page->mapping)); if (!new_jh) { jbd_unlock_bh_journal_head(bh); goto repeat; } jh = new_jh; new_jh = NULL; /* We consumed it */ set_buffer_jbd(bh); bh->b_private = jh; jh->b_bh = bh; get_bh(bh); BUFFER_TRACE(bh, "added journal_head"); } jh->b_jcount++; jbd_unlock_bh_journal_head(bh); if (new_jh) journal_free_journal_head(new_jh); return bh->b_private; } /* * Grab a ref against this buffer_head's journal_head. If it ended up not * having a journal_head, return NULL */ struct journal_head *journal_grab_journal_head(struct buffer_head *bh) { struct journal_head *jh = NULL; jbd_lock_bh_journal_head(bh); if (buffer_jbd(bh)) { jh = bh2jh(bh); jh->b_jcount++; } jbd_unlock_bh_journal_head(bh); return jh; } static void __journal_remove_journal_head(struct buffer_head *bh) { struct journal_head *jh = bh2jh(bh); J_ASSERT_JH(jh, jh->b_jcount >= 0); J_ASSERT_JH(jh, jh->b_transaction == NULL); J_ASSERT_JH(jh, jh->b_next_transaction == NULL); J_ASSERT_JH(jh, jh->b_cp_transaction == NULL); J_ASSERT_JH(jh, jh->b_jlist == BJ_None); J_ASSERT_BH(bh, buffer_jbd(bh)); J_ASSERT_BH(bh, jh2bh(jh) == bh); BUFFER_TRACE(bh, "remove journal_head"); if (jh->b_frozen_data) { printk(KERN_WARNING "%s: freeing b_frozen_data\n", __func__); jbd_free(jh->b_frozen_data, bh->b_size); } if (jh->b_committed_data) { printk(KERN_WARNING "%s: freeing b_committed_data\n", __func__); jbd_free(jh->b_committed_data, bh->b_size); } bh->b_private = NULL; jh->b_bh = NULL; /* debug, really */ clear_buffer_jbd(bh); journal_free_journal_head(jh); } /* * Drop a reference on the passed journal_head. If it fell to zero then * release the journal_head from the buffer_head. */ void journal_put_journal_head(struct journal_head *jh) { struct buffer_head *bh = jh2bh(jh); jbd_lock_bh_journal_head(bh); J_ASSERT_JH(jh, jh->b_jcount > 0); --jh->b_jcount; if (!jh->b_jcount) { __journal_remove_journal_head(bh); jbd_unlock_bh_journal_head(bh); __brelse(bh); } else jbd_unlock_bh_journal_head(bh); } /* * debugfs tunables */ #ifdef CONFIG_JBD_DEBUG u8 journal_enable_debug __read_mostly; EXPORT_SYMBOL(journal_enable_debug); static struct dentry *jbd_debugfs_dir; static struct dentry *jbd_debug; static void __init jbd_create_debugfs_entry(void) { jbd_debugfs_dir = debugfs_create_dir("jbd", NULL); if (jbd_debugfs_dir) jbd_debug = debugfs_create_u8("jbd-debug", S_IRUGO | S_IWUSR, jbd_debugfs_dir, &journal_enable_debug); } static void __exit jbd_remove_debugfs_entry(void) { debugfs_remove(jbd_debug); debugfs_remove(jbd_debugfs_dir); } #else static inline void jbd_create_debugfs_entry(void) { } static inline void jbd_remove_debugfs_entry(void) { } #endif struct kmem_cache *jbd_handle_cache; static int __init journal_init_handle_cache(void) { jbd_handle_cache = kmem_cache_create("journal_handle", sizeof(handle_t), 0, /* offset */ SLAB_TEMPORARY, /* flags */ NULL); /* ctor */ if (jbd_handle_cache == NULL) { printk(KERN_EMERG "JBD: failed to create handle cache\n"); return -ENOMEM; } return 0; } static void journal_destroy_handle_cache(void) { if (jbd_handle_cache) kmem_cache_destroy(jbd_handle_cache); } /* * Module startup and shutdown */ static int __init journal_init_caches(void) { int ret; ret = journal_init_revoke_caches(); if (ret == 0) ret = journal_init_journal_head_cache(); if (ret == 0) ret = journal_init_handle_cache(); return ret; } static void journal_destroy_caches(void) { journal_destroy_revoke_caches(); journal_destroy_journal_head_cache(); journal_destroy_handle_cache(); } static int __init journal_init(void) { int ret; BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024); ret = journal_init_caches(); if (ret != 0) journal_destroy_caches(); jbd_create_debugfs_entry(); return ret; } static void __exit journal_exit(void) { #ifdef CONFIG_JBD_DEBUG int n = atomic_read(&nr_journal_heads); if (n) printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n); #endif jbd_remove_debugfs_entry(); journal_destroy_caches(); } MODULE_LICENSE("GPL"); module_init(journal_init); module_exit(journal_exit);