diff options
Diffstat (limited to 'fs/jbd/journal.c')
| -rw-r--r-- | fs/jbd/journal.c | 2003 |
1 files changed, 2003 insertions, 0 deletions
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c new file mode 100644 index 0000000..1e6f2e2 --- /dev/null +++ b/fs/jbd/journal.c @@ -0,0 +1,2003 @@ +/* + * linux/fs/journal.c + * + * Written by Stephen C. Tweedie <sct@redhat.com>, 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 <linux/module.h> +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/jbd.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/smp_lock.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/suspend.h> +#include <linux/pagemap.h> +#include <asm/uaccess.h> +#include <asm/page.h> +#include <linux/proc_fs.h> + +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_recover); +EXPORT_SYMBOL(journal_update_superblock); +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(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 *); + +/* + * 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); +} + +/* Static check for data structure consistency. There's no code + * invoked --- we'll just get a linker failure if things aren't right. + */ +void __journal_internal_check(void) +{ + extern void journal_bad_superblock_size(void); + if (sizeof(struct journal_superblock_s) != 1024) + journal_bad_superblock_size(); +} + +/* + * 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. + */ + +journal_t *current_journal; // AKPM: debug + +int kjournald(void *arg) +{ + journal_t *journal = (journal_t *) arg; + transaction_t *transaction; + struct timer_list timer; + + current_journal = journal; + + daemonize("kjournald"); + + /* Set up an interval timer which can be used to trigger a + commit wakeup after the commit interval expires */ + init_timer(&timer); + timer.data = (unsigned long) current; + timer.function = commit_timeout; + journal->j_commit_timer = &timer; + + /* 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 (current->flags & PF_FREEZE) { + /* + * 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); + refrigerator(PF_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 (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 void journal_start_thread(journal_t *journal) +{ + kernel_thread(kjournald, journal, CLONE_VM|CLONE_FS|CLONE_FILES); + wait_event(journal->j_wait_done_commit, journal->j_task != 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 == 0); + 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, + 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); + + /* + * 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); + + /* + * 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_rep_kmalloc(bh_in->b_size, GFP_NOFS); + jbd_lock_bh_state(bh_in); + if (jh_in->b_frozen_data) { + kfree(tmp); + 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); + } + + /* keep subsequent assertions sane */ + new_bh->b_state = 0; + init_buffer(new_bh, NULL, NULL); + atomic_set(&new_bh->b_count, 1); + jbd_unlock_bh_state(bh_in); + + new_jh = journal_add_journal_head(new_bh); /* This sleeps */ + + 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"); + journal_file_buffer(jh_in, transaction, BJ_Shadow); + 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 was started. + */ +int __log_start_commit(journal_t *journal, tid_t target) +{ + /* + * Are we already doing a recent enough commit? + */ + if (!tid_geq(journal->j_commit_request, target)) { + /* + * We want a new commit: OK, mark the request and wakup 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; + } + 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 was started, 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; + + ret = __log_start_commit(journal, tid); + if (ret && ptid) + *ptid = tid; + } else if (journal->j_committing_transaction && ptid) { + /* + * If ext3_write_super() recently started a commit, then we + * have to wait for completion of that transaction + */ + *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", + __FUNCTION__, 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; +} + +/* + * Log buffer allocation routines: + */ + +int journal_next_log_block(journal_t *journal, unsigned long *retp) +{ + unsigned long 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 long blocknr, + unsigned long *retp) +{ + int err = 0; + unsigned long 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 %lu on %s\n", + __FUNCTION__, + 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 long blocknr; + int err; + + err = journal_next_log_block(journal, &blocknr); + + if (err) + return NULL; + + bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); + 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 = jbd_kmalloc(sizeof(*journal), GFP_KERNEL); + if (!journal) + goto fail; + memset(journal, 0, sizeof(*journal)); + + 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); + init_MUTEX(&journal->j_barrier); + init_MUTEX(&journal->j_checkpoint_sem); + 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 an 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: Lenght 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->j_dev = bdev; + journal->j_fs_dev = fs_dev; + journal->j_blk_offset = start; + journal->j_maxlen = len; + journal->j_blocksize = blocksize; + + bh = __getblk(journal->j_dev, start, journal->j_blocksize); + J_ASSERT(bh != NULL); + journal->j_sb_buffer = bh; + journal->j_superblock = (journal_superblock_t *)bh->b_data; + + /* 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: Cant allocate bhs for commit thread\n", + __FUNCTION__); + kfree(journal); + journal = NULL; + } + + return journal; +} + +/** + * 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 long 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: Cant allocate bhs for commit thread\n", + __FUNCTION__); + kfree(journal); + return NULL; + } + + err = journal_bmap(journal, 0, &blocknr); + /* If that failed, give up */ + if (err) { + printk(KERN_ERR "%s: Cannnot locate journal superblock\n", + __FUNCTION__); + kfree(journal); + return NULL; + } + + bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); + J_ASSERT(bh != NULL); + journal->j_sb_buffer = bh; + journal->j_superblock = (journal_superblock_t *)bh->b_data; + + return journal; +} + +/* + * 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); + + 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); + journal_start_thread(journal); + return 0; +} + +/** + * 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 long 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", + __FUNCTION__); + 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); + 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 %ld, seq %d, errno %d)\n", + journal->j_tail, journal->j_tail_sequence, + journal->j_errno); + goto out; + } + + spin_lock(&journal->j_state_lock); + jbd_debug(1,"JBD: updating superblock (start %ld, 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); + else + ll_rw_block(WRITE, 1, &bh); + +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; + } + + 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; + + err = load_superblock(journal); + if (err) + return err; + + /* If this is a V2 superblock, then we have to check the + * features flags on it. */ + + if (journal->j_format_version >= 2) { + journal_superblock_t *sb = journal->j_superblock; + + 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. + */ +void journal_destroy(journal_t *journal) +{ + /* 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); + + /* We can now mark the journal as empty. */ + journal->j_tail = 0; + journal->j_tail_sequence = ++journal->j_transaction_sequence; + if (journal->j_sb_buffer) { + journal_update_superblock(journal, 1); + 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); +} + + +/** + *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) +{ + journal_superblock_t *sb; + + if (!compat && !ro && !incompat) + return 1; + + sb = journal->j_superblock; + + /* 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 long 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); + err = log_do_checkpoint(journal); + spin_lock(&journal->j_list_lock); + } + spin_unlock(&journal->j_list_lock); + 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 err; +} + +/** + * 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) +{ + journal_superblock_t *sb; + int err = 0; + + J_ASSERT (!(journal->j_flags & JFS_LOADED)); + + err = load_superblock(journal); + if (err) + return err; + + sb = journal->j_superblock; + + 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. + */ + +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. + */ +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. */ +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); +} + +/* + * Simple support for retrying memory allocations. Introduced to help to + * debug different VM deadlock avoidance strategies. + */ +void * __jbd_kmalloc (const char *where, size_t size, int flags, int retry) +{ + return kmalloc(size, flags | (retry ? __GFP_NOFAIL : 0)); +} + +/* + * Journal_head storage management + */ +static kmem_cache_t *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 == 0); + journal_head_cache = kmem_cache_create("journal_head", + sizeof(struct journal_head), + 0, /* offset */ + 0, /* flags */ + NULL, /* ctor */ + NULL); /* dtor */ + retval = 0; + if (journal_head_cache == 0) { + retval = -ENOMEM; + printk(KERN_EMERG "JBD: no memory for journal_head cache\n"); + } + return retval; +} + +static void journal_destroy_journal_head_cache(void) +{ + J_ASSERT(journal_head_cache != NULL); + 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; + static unsigned long last_warning; + +#ifdef CONFIG_JBD_DEBUG + atomic_inc(&nr_journal_heads); +#endif + ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS); + if (ret == 0) { + jbd_debug(1, "out of memory for journal_head\n"); + if (time_after(jiffies, last_warning + 5*HZ)) { + printk(KERN_NOTICE "ENOMEM in %s, retrying.\n", + __FUNCTION__); + last_warning = jiffies; + } + while (ret == 0) { + 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, 0x5b, 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 may be detached from its buffer_head when the journal_head's + * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL. + * Various places in JBD call journal_remove_journal_head() to indicate that the + * journal_head can be dropped if needed. + * + * 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); + * ... + * jh->b_transaction = xxx; + * journal_put_journal_head(jh); + * + * Now, the journal_head's b_jcount is zero, but it is safe from being released + * because it has a non-zero b_transaction. + */ + +/* + * Give a buffer_head a journal_head. + * + * Doesn't need the journal lock. + * 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); + + get_bh(bh); + if (jh->b_jcount == 0) { + if (jh->b_transaction == NULL && + jh->b_next_transaction == NULL && + 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", + __FUNCTION__); + kfree(jh->b_frozen_data); + } + if (jh->b_committed_data) { + printk(KERN_WARNING "%s: freeing " + "b_committed_data\n", + __FUNCTION__); + kfree(jh->b_committed_data); + } + bh->b_private = NULL; + jh->b_bh = NULL; /* debug, really */ + clear_buffer_jbd(bh); + __brelse(bh); + journal_free_journal_head(jh); + } else { + BUFFER_TRACE(bh, "journal_head was locked"); + } + } +} + +/* + * journal_remove_journal_head(): if the buffer isn't attached to a transaction + * and has a zero b_jcount then remove and release its journal_head. If we did + * see that the buffer is not used by any transaction we also "logically" + * decrement ->b_count. + * + * We in fact take an additional increment on ->b_count as a convenience, + * because the caller usually wants to do additional things with the bh + * after calling here. + * The caller of journal_remove_journal_head() *must* run __brelse(bh) at some + * time. Once the caller has run __brelse(), the buffer is eligible for + * reaping by try_to_free_buffers(). + */ +void journal_remove_journal_head(struct buffer_head *bh) +{ + jbd_lock_bh_journal_head(bh); + __journal_remove_journal_head(bh); + jbd_unlock_bh_journal_head(bh); +} + +/* + * Drop a reference on the passed journal_head. If it fell to zero then try to + * 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 && !jh->b_transaction) { + __journal_remove_journal_head(bh); + __brelse(bh); + } + jbd_unlock_bh_journal_head(bh); +} + +/* + * /proc tunables + */ +#if defined(CONFIG_JBD_DEBUG) +int journal_enable_debug; +EXPORT_SYMBOL(journal_enable_debug); +#endif + +#if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_PROC_FS) + +static struct proc_dir_entry *proc_jbd_debug; + +int read_jbd_debug(char *page, char **start, off_t off, + int count, int *eof, void *data) +{ + int ret; + + ret = sprintf(page + off, "%d\n", journal_enable_debug); + *eof = 1; + return ret; +} + +int write_jbd_debug(struct file *file, const char __user *buffer, + unsigned long count, void *data) +{ + char buf[32]; + + if (count > ARRAY_SIZE(buf) - 1) + count = ARRAY_SIZE(buf) - 1; + if (copy_from_user(buf, buffer, count)) + return -EFAULT; + buf[ARRAY_SIZE(buf) - 1] = '\0'; + journal_enable_debug = simple_strtoul(buf, NULL, 10); + return count; +} + +#define JBD_PROC_NAME "sys/fs/jbd-debug" + +static void __init create_jbd_proc_entry(void) +{ + proc_jbd_debug = create_proc_entry(JBD_PROC_NAME, 0644, NULL); + if (proc_jbd_debug) { + /* Why is this so hard? */ + proc_jbd_debug->read_proc = read_jbd_debug; + proc_jbd_debug->write_proc = write_jbd_debug; + } +} + +static void __exit remove_jbd_proc_entry(void) +{ + if (proc_jbd_debug) + remove_proc_entry(JBD_PROC_NAME, NULL); +} + +#else + +#define create_jbd_proc_entry() do {} while (0) +#define remove_jbd_proc_entry() do {} while (0) + +#endif + +kmem_cache_t *jbd_handle_cache; + +static int __init journal_init_handle_cache(void) +{ + jbd_handle_cache = kmem_cache_create("journal_handle", + sizeof(handle_t), + 0, /* offset */ + 0, /* flags */ + NULL, /* ctor */ + NULL); /* dtor */ + 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; + + ret = journal_init_caches(); + if (ret != 0) + journal_destroy_caches(); + create_jbd_proc_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 + remove_jbd_proc_entry(); + journal_destroy_caches(); +} + +MODULE_LICENSE("GPL"); +module_init(journal_init); +module_exit(journal_exit); + |
