/* * linux/fs/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 EXPORT_SYMBOL(journal_start); EXPORT_SYMBOL(journal_try_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); #if 0 EXPORT_SYMBOL(journal_release_buffer); #endif 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(log_start_commit); EXPORT_SYMBOL(journal_wipe); EXPORT_SYMBOL(journal_blocks_per_page); EXPORT_SYMBOL(journal_flushpage); EXPORT_SYMBOL(journal_try_to_free_buffers); EXPORT_SYMBOL(journal_bmap); EXPORT_SYMBOL(journal_force_commit); static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *); /* * journal_datalist_lock is used to protect data buffers: * * bh->b_transaction * bh->b_tprev * bh->b_tnext * * journal_free_buffer() is called from journal_try_to_free_buffer(), and is * async wrt everything else. * * It is also used for checkpoint data, also to protect against * journal_try_to_free_buffer(): * * bh->b_cp_transaction * bh->b_cpnext * bh->b_cpprev * transaction->t_checkpoint_list * transaction->t_cpnext * transaction->t_cpprev * journal->j_checkpoint_transactions * * It is global at this time rather than per-journal because it's * impossible for __journal_free_buffer to go from a buffer_head * back to a journal_t unracily (well, not true. Fix later) * * * The `datalist' and `checkpoint list' functions are quite * separate and we could use two spinlocks here. * * lru_list_lock nests inside journal_datalist_lock. */ spinlock_t journal_datalist_lock = SPIN_LOCK_UNLOCKED; /* * jh_splice_lock needs explantion. * * In a number of places we want to do things like: * * if (buffer_jbd(bh) && bh2jh(bh)->foo) * * This is racy on SMP, because another CPU could remove the journal_head * in the middle of this expression. We need locking. * * But we can greatly optimise the locking cost by testing BH_JBD * outside the lock. So, effectively: * * ret = 0; * if (buffer_jbd(bh)) { * spin_lock(&jh_splice_lock); * if (buffer_jbd(bh)) { (* Still there? *) * ret = bh2jh(bh)->foo; * } * spin_unlock(&jh_splice_lock); * } * return ret; * * Now, that protects us from races where another CPU can remove the * journal_head. But it doesn't defend us from the situation where another * CPU can *add* a journal_head. This is a correctness issue. But it's not * a problem because a) the calling code was *already* racy and b) it often * can't happen at the call site and c) the places where we add journal_heads * tend to be under external locking. */ spinlock_t jh_splice_lock = SPIN_LOCK_UNLOCKED; /* * List of all journals in the system. Protected by the BKL. */ static LIST_HEAD(all_journals); /* * 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; lock_kernel(); daemonize(); spin_lock_irq(¤t->sigmask_lock); sigfillset(¤t->blocked); recalc_sigpending(current); spin_unlock_irq(¤t->sigmask_lock); sprintf(current->comm, "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); list_add(&journal->j_all_journals, &all_journals); /* And now, wait forever for commit wakeup events. */ while (1) { if (journal->j_flags & JFS_UNMOUNT) break; 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"); if (journal->j_commit_timer_active) { journal->j_commit_timer_active = 0; del_timer(journal->j_commit_timer); } journal_commit_transaction(journal); continue; } wake_up(&journal->j_wait_done_commit); interruptible_sleep_on(&journal->j_wait_commit); jbd_debug(1, "kjournald wakes\n"); /* Were we woken up by a commit wakeup event? */ if ((transaction = journal->j_running_transaction) != NULL && time_after_eq(jiffies, transaction->t_expires)) { journal->j_commit_request = transaction->t_tid; jbd_debug(1, "woke because of timeout\n"); } } if (journal->j_commit_timer_active) { journal->j_commit_timer_active = 0; del_timer_sync(journal->j_commit_timer); } list_del(&journal->j_all_journals); 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, (void *) journal, CLONE_VM | CLONE_FS | CLONE_FILES); while (!journal->j_task) sleep_on(&journal->j_wait_done_commit); } static void journal_kill_thread(journal_t *journal) { journal->j_flags |= JFS_UNMOUNT; while (journal->j_task) { wake_up(&journal->j_wait_commit); sleep_on(&journal->j_wait_done_commit); } } #if 0 This is no longer needed - we do it in commit quite efficiently. Note that if this function is resurrected, the loop needs to be reorganised into the next_jh/last_jh algorithm. /* * journal_clean_data_list: cleanup after data IO. * * Once the IO system has finished writing the buffers on the transaction's * data list, we can remove those buffers from the list. This function * scans the list for such buffers and removes them cleanly. * * We assume that the journal is already locked. * We are called with journal_datalist_lock held. * * AKPM: This function looks inefficient. Approximately O(n^2) * for potentially thousands of buffers. It no longer shows on profiles * because these buffers are mainly dropped in journal_commit_transaction(). */ void __journal_clean_data_list(transaction_t *transaction) { struct journal_head *jh, *next; assert_spin_locked(&journal_datalist_lock); restart: jh = transaction->t_sync_datalist; if (!jh) goto out; do { next = jh->b_tnext; if (!buffer_locked(jh2bh(jh)) && !buffer_dirty(jh2bh(jh))) { struct buffer_head *bh = jh2bh(jh); BUFFER_TRACE(bh, "data writeout complete: unfile"); __journal_unfile_buffer(jh); jh->b_transaction = NULL; __journal_remove_journal_head(bh); refile_buffer(bh); __brelse(bh); goto restart; } jh = next; } while (transaction->t_sync_datalist && jh != transaction->t_sync_datalist); out: return; } #endif /* * 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) */ static inline unsigned long virt_to_offset(void *p) {return ((unsigned long) p) & ~PAGE_MASK;} 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; /* * 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_JH(jh_in, buffer_jdirty(jh2bh(jh_in))); /* * If a new transaction has already done a buffer copy-out, then * we use that version of the data for the commit. */ if (jh_in->b_frozen_data) { done_copy_out = 1; new_page = virt_to_page(jh_in->b_frozen_data); new_offset = virt_to_offset(jh_in->b_frozen_data); } else { new_page = jh2bh(jh_in)->b_page; new_offset = virt_to_offset(jh2bh(jh_in)->b_data); } mapped_data = ((char *) kmap(new_page)) + new_offset; /* * Check for escaping */ if (* ((unsigned int *) mapped_data) == htonl(JFS_MAGIC_NUMBER)) { need_copy_out = 1; do_escape = 1; } /* * Do we need to do a data copy? */ if (need_copy_out && !done_copy_out) { char *tmp; tmp = jbd_rep_kmalloc(jh2bh(jh_in)->b_size, GFP_NOFS); jh_in->b_frozen_data = tmp; memcpy (tmp, mapped_data, jh2bh(jh_in)->b_size); /* If we get to this path, we'll always need the new address kmapped so that we can clear the escaped magic number below. */ kunmap(new_page); new_page = virt_to_page(tmp); new_offset = virt_to_offset(tmp); mapped_data = ((char *) kmap(new_page)) + new_offset; done_copy_out = 1; } /* * Right, time to make up the new buffer_head. */ do { new_bh = get_unused_buffer_head(0); if (!new_bh) { printk (KERN_NOTICE __FUNCTION__ ": ENOMEM at get_unused_buffer_head, " "trying again.\n"); current->policy |= SCHED_YIELD; schedule(); } } while (!new_bh); /* keep subsequent assertions sane */ new_bh->b_prev_free = 0; new_bh->b_next_free = 0; 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); 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_dev = transaction->t_journal->j_dev; new_bh->b_blocknr = blocknr; new_bh->b_state |= (1 << BH_Mapped) | (1 << BH_Dirty); *jh_out = new_jh; /* * Did we need to do an escaping? Now we've done all the * copying, we can finally do so. */ if (do_escape) * ((unsigned int *) mapped_data) = 0; kunmap(new_page); /* * 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. */ int log_space_left (journal_t *journal) { int left = journal->j_free; /* 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; } /* * This function must be non-allocating for PF_MEMALLOC tasks */ tid_t log_start_commit (journal_t *journal, transaction_t *transaction) { tid_t target = journal->j_commit_request; lock_kernel(); /* Protect journal->j_running_transaction */ /* * A NULL transaction asks us to commit the currently running * transaction, if there is one. */ if (transaction) target = transaction->t_tid; else { transaction = journal->j_running_transaction; if (!transaction) goto out; target = transaction->t_tid; } /* * Are we already doing a recent enough commit? */ if (tid_geq(journal->j_commit_request, target)) goto out; /* * 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); out: unlock_kernel(); return target; } /* * Wait for a specified commit to complete. * The caller may not hold the journal lock. */ void log_wait_commit (journal_t *journal, tid_t tid) { lock_kernel(); #ifdef CONFIG_JBD_DEBUG lock_journal(journal); if (!tid_geq(journal->j_commit_request, tid)) { printk(KERN_EMERG __FUNCTION__ ": error: j_commit_request=%d, tid=%d\n", journal->j_commit_request, tid); } unlock_journal(journal); #endif 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); sleep_on(&journal->j_wait_done_commit); } unlock_kernel(); } /* * Log buffer allocation routines: */ int journal_next_log_block(journal_t *journal, unsigned long *retp) { unsigned long blocknr; 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; 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 { printk (KERN_ALERT __FUNCTION__ ": journal block not found " "at offset %lu on %s\n", blocknr, bdevname(journal->j_dev)); 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. * * We return a jh whose bh is locked and ready to be populated. */ 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); 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; MOD_INC_USE_COUNT; 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); init_MUTEX(&journal->j_sem); journal->j_commit_interval = (HZ * 5); /* 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: MOD_DEC_USE_COUNT; 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_init_dev creates a journal which maps a fixed contiguous * range of blocks on an arbitrary block device. * * 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_dev(kdev_t dev, kdev_t fs_dev, int start, int len, int blocksize) { journal_t *journal = journal_init_common(); struct buffer_head *bh; if (!journal) return NULL; journal->j_dev = dev; 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; return journal; } journal_t * journal_init_inode (struct inode *inode) { struct buffer_head *bh; journal_t *journal = journal_init_common(); int err; unsigned long blocknr; if (!journal) return NULL; journal->j_dev = inode->i_dev; journal->j_fs_dev = inode->i_dev; journal->j_inode = inode; jbd_debug(1, "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n", journal, bdevname(inode->i_dev), 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; err = journal_bmap(journal, 0, &blocknr); /* If that failed, give up */ if (err) { printk(KERN_ERR __FUNCTION__ ": Cannnot locate journal " "superblock\n"); 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 = ntohl(sb->s_first); last = ntohl(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); lock_journal(journal); journal_start_thread(journal); unlock_journal(journal); return 0; } /* * 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 __FUNCTION__ ": creation of journal on external device!\n"); 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); wait_on_buffer(bh); memset (bh->b_data, 0, journal->j_blocksize); BUFFER_TRACE(bh, "marking dirty"); mark_buffer_dirty(bh); BUFFER_TRACE(bh, "marking uptodate"); mark_buffer_uptodate(bh, 1); __brelse(bh); } sync_dev(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 = htonl(JFS_MAGIC_NUMBER); sb->s_header.h_blocktype = htonl(JFS_SUPERBLOCK_V2); sb->s_blocksize = htonl(journal->j_blocksize); sb->s_maxlen = htonl(journal->j_maxlen); sb->s_first = htonl(1); journal->j_transaction_sequence = 1; journal->j_flags &= ~JFS_ABORT; journal->j_format_version = 2; return journal_reset(journal); } /* * 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; 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 = htonl(journal->j_tail_sequence); sb->s_start = htonl(journal->j_tail); sb->s_errno = htonl(journal->j_errno); BUFFER_TRACE(bh, "marking dirty"); mark_buffer_dirty(bh); ll_rw_block(WRITE, 1, &bh); if (wait) wait_on_buffer(bh); /* 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. */ if (sb->s_start) journal->j_flags &= ~JFS_FLUSHED; else journal->j_flags |= JFS_FLUSHED; } /* * 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 != htonl(JFS_MAGIC_NUMBER) || sb->s_blocksize != htonl(journal->j_blocksize)) { printk(KERN_WARNING "JBD: no valid journal superblock found\n"); goto out; } switch(ntohl(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 (ntohl(sb->s_maxlen) < journal->j_maxlen) journal->j_maxlen = ntohl(sb->s_maxlen); else if (ntohl(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 = ntohl(sb->s_sequence); journal->j_tail = ntohl(sb->s_start); journal->j_first = ntohl(sb->s_first); journal->j_last = ntohl(sb->s_maxlen); journal->j_errno = ntohl(sb->s_errno); return 0; } /* * 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; } /* * 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 */ lock_journal(journal); while (journal->j_checkpoint_transactions != NULL) log_do_checkpoint(journal, 1); J_ASSERT(journal->j_running_transaction == NULL); J_ASSERT(journal->j_committing_transaction == NULL); J_ASSERT(journal->j_checkpoint_transactions == NULL); /* 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); unlock_journal(journal); kfree(journal); MOD_DEC_USE_COUNT; } /* Published API: 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; } /* Published API: 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; } /* Published API: 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; } /* * Published API: * 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 (ntohl(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 = ntohl(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); ll_rw_block(WRITE, 1, &bh); wait_on_buffer(bh); return 0; } /* * 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; lock_kernel(); /* Force everything buffered to the log... */ if (journal->j_running_transaction) { transaction = journal->j_running_transaction; log_start_commit(journal, transaction); } else if (journal->j_committing_transaction) transaction = journal->j_committing_transaction; /* Wait for the log commit to complete... */ if (transaction) log_wait_commit(journal, transaction->t_tid); /* ...and flush everything in the log out to disk. */ lock_journal(journal); while (!err && journal->j_checkpoint_transactions != NULL) err = log_do_checkpoint(journal, journal->j_maxlen); 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. */ old_tail = journal->j_tail; journal->j_tail = 0; journal_update_superblock(journal, 1); journal->j_tail = old_tail; unlock_journal(journal); 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); unlock_kernel(); return err; } /* * 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) { kdev_t dev; if (journal->j_inode) dev = journal->j_inode->i_dev; else dev = journal->j_dev; return bdevname(dev); } /* * journal_abort: 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 recored (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). */ /* 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; if (journal->j_flags & JFS_ABORT) return; printk (KERN_ERR "Aborting journal on device %s.\n", journal_dev_name(journal)); journal->j_flags |= JFS_ABORT; transaction = journal->j_running_transaction; if (transaction) log_start_commit(journal, transaction); } /* 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); } /* Full version for external use */ void journal_abort (journal_t *journal, int errno) { lock_journal(journal); __journal_abort_soft(journal, errno); unlock_journal(journal); } int journal_errno (journal_t *journal) { int err; lock_journal(journal); if (journal->j_flags & JFS_ABORT) err = -EROFS; else err = journal->j_errno; unlock_journal(journal); return err; } int journal_clear_err (journal_t *journal) { int err = 0; lock_journal(journal); if (journal->j_flags & JFS_ABORT) err = -EROFS; else journal->j_errno = 0; unlock_journal(journal); return err; } void journal_ack_err (journal_t *journal) { lock_journal(journal); if (journal->j_errno) journal->j_flags |= JFS_ACK_ERR; unlock_journal(journal); } int journal_blocks_per_page(struct inode *inode) { return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits); } /* * shrink_journal_memory(). * Called when we're under memory pressure. Free up all the written-back * checkpointed metadata buffers. */ void shrink_journal_memory(void) { struct list_head *list; lock_kernel(); list_for_each(list, &all_journals) { journal_t *journal = list_entry(list, journal_t, j_all_journals); spin_lock(&journal_datalist_lock); __journal_clean_checkpoint_list(journal); spin_unlock(&journal_datalist_lock); } unlock_kernel(); } /* * Simple support for retying memory allocations. Introduced to help to * debug different VM deadlock avoidance strategies. */ /* * Simple support for retying memory allocations. Introduced to help to * debug different VM deadlock avoidance strategies. */ void * __jbd_kmalloc (char *where, size_t size, int flags, int retry) { void *p; static unsigned long last_warning; while (1) { p = kmalloc(size, flags); if (p) return p; if (!retry) return NULL; /* Log every retry for debugging. Also log them to the * syslog, but do rate-limiting on the non-debugging * messages. */ jbd_debug(1, "ENOMEM in %s, retrying.\n", where); if (time_after(jiffies, last_warning + 5*HZ)) { printk(KERN_NOTICE "ENOMEM in %s, retrying.\n", where); last_warning = jiffies; } current->policy |= SCHED_YIELD; schedule(); } } /* * 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 = 0; } /* * 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 " __FUNCTION__ ", retrying.\n"); last_warning = jiffies; } while (ret == 0) { current->policy |= SCHED_YIELD; schedule(); 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_unlock_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_unlock_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. * Cannot be called with journal_datalist_lock held. */ struct journal_head *journal_add_journal_head(struct buffer_head *bh) { struct journal_head *jh; spin_lock(&journal_datalist_lock); 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)); spin_unlock(&journal_datalist_lock); jh = journal_alloc_journal_head(); memset(jh, 0, sizeof(*jh)); spin_lock(&journal_datalist_lock); if (buffer_jbd(bh)) { /* Someone did it for us! */ J_ASSERT_BH(bh, bh->b_private != NULL); journal_free_journal_head(jh); jh = bh->b_private; } else { /* * We actually don't need jh_splice_lock when * adding a journal_head - only on removal. */ spin_lock(&jh_splice_lock); set_bit(BH_JBD, &bh->b_state); bh->b_private = jh; jh->b_bh = bh; atomic_inc(&bh->b_count); spin_unlock(&jh_splice_lock); BUFFER_TRACE(bh, "added journal_head"); } } jh->b_jcount++; spin_unlock(&journal_datalist_lock); return bh->b_private; } /* * 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(). * * Requires journal_datalist_lock. */ void __journal_remove_journal_head(struct buffer_head *bh) { struct journal_head *jh = bh2jh(bh); assert_spin_locked(&journal_datalist_lock); J_ASSERT_JH(jh, jh->b_jcount >= 0); atomic_inc(&bh->b_count); if (jh->b_jcount == 0) { if (jh->b_transaction == NULL && jh->b_next_transaction == NULL && jh->b_cp_transaction == NULL) { J_ASSERT_BH(bh, buffer_jbd(bh)); J_ASSERT_BH(bh, jh2bh(jh) == bh); BUFFER_TRACE(bh, "remove journal_head"); spin_lock(&jh_splice_lock); bh->b_private = NULL; jh->b_bh = NULL; /* debug, really */ clear_bit(BH_JBD, &bh->b_state); __brelse(bh); spin_unlock(&jh_splice_lock); journal_free_journal_head(jh); } else { BUFFER_TRACE(bh, "journal_head was locked"); } } } void journal_unlock_journal_head(struct journal_head *jh) { spin_lock(&journal_datalist_lock); J_ASSERT_JH(jh, jh->b_jcount > 0); --jh->b_jcount; if (!jh->b_jcount && !jh->b_transaction) { struct buffer_head *bh; bh = jh2bh(jh); __journal_remove_journal_head(bh); __brelse(bh); } spin_unlock(&journal_datalist_lock); } void journal_remove_journal_head(struct buffer_head *bh) { spin_lock(&journal_datalist_lock); __journal_remove_journal_head(bh); spin_unlock(&journal_datalist_lock); } /* * /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 *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 /* * 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(); return ret; } static void journal_destroy_caches(void) { journal_destroy_revoke_caches(); journal_destroy_journal_head_cache(); } static int __init journal_init(void) { int ret; printk(KERN_INFO "Journalled Block Device driver loaded\n"); 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);