Merge branch 'upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/linville...

[linux-2.6] / fs / ocfs2 / journal.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * journal.c
 *
 * Defines functions of journalling api
 *
 * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/kthread.h>

#define MLOG_MASK_PREFIX ML_JOURNAL
#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.h"
#include "dlmglue.h"
#include "extent_map.h"
#include "heartbeat.h"
#include "inode.h"
#include "journal.h"
#include "localalloc.h"
#include "namei.h"
#include "slot_map.h"
#include "super.h"
#include "vote.h"
#include "sysfile.h"

#include "buffer_head_io.h"

DEFINE_SPINLOCK(trans_inc_lock);

static int ocfs2_force_read_journal(struct inode *inode);
static int ocfs2_recover_node(struct ocfs2_super *osb,
                              int node_num);
static int __ocfs2_recovery_thread(void *arg);
static int ocfs2_commit_cache(struct ocfs2_super *osb);
static int ocfs2_wait_on_mount(struct ocfs2_super *osb);
static int ocfs2_journal_toggle_dirty(struct ocfs2_super *osb,
                                      int dirty);
static int ocfs2_trylock_journal(struct ocfs2_super *osb,
                                 int slot_num);
static int ocfs2_recover_orphans(struct ocfs2_super *osb,
                                 int slot);
static int ocfs2_commit_thread(void *arg);

static int ocfs2_commit_cache(struct ocfs2_super *osb)
{
        int status = 0;
        unsigned int flushed;
        unsigned long old_id;
        struct ocfs2_journal *journal = NULL;

        mlog_entry_void();

        journal = osb->journal;

        /* Flush all pending commits and checkpoint the journal. */
        down_write(&journal->j_trans_barrier);

        if (atomic_read(&journal->j_num_trans) == 0) {
                up_write(&journal->j_trans_barrier);
                mlog(0, "No transactions for me to flush!\n");
                goto finally;
        }

        journal_lock_updates(journal->j_journal);
        status = journal_flush(journal->j_journal);
        journal_unlock_updates(journal->j_journal);
        if (status < 0) {
                up_write(&journal->j_trans_barrier);
                mlog_errno(status);
                goto finally;
        }

        old_id = ocfs2_inc_trans_id(journal);

        flushed = atomic_read(&journal->j_num_trans);
        atomic_set(&journal->j_num_trans, 0);
        up_write(&journal->j_trans_barrier);

        mlog(0, "commit_thread: flushed transaction %lu (%u handles)\n",
             journal->j_trans_id, flushed);

        ocfs2_kick_vote_thread(osb);
        wake_up(&journal->j_checkpointed);
finally:
        mlog_exit(status);
        return status;
}

/* pass it NULL and it will allocate a new handle object for you.  If
 * you pass it a handle however, it may still return error, in which
 * case it has free'd the passed handle for you. */
handle_t *ocfs2_start_trans(struct ocfs2_super *osb, int max_buffs)
{
        journal_t *journal = osb->journal->j_journal;
        handle_t *handle;

        BUG_ON(!osb || !osb->journal->j_journal);

        if (ocfs2_is_hard_readonly(osb))
                return ERR_PTR(-EROFS);

        BUG_ON(osb->journal->j_state == OCFS2_JOURNAL_FREE);
        BUG_ON(max_buffs <= 0);

        /* JBD might support this, but our journalling code doesn't yet. */
        if (journal_current_handle()) {
                mlog(ML_ERROR, "Recursive transaction attempted!\n");
                BUG();
        }

        down_read(&osb->journal->j_trans_barrier);

        handle = journal_start(journal, max_buffs);
        if (IS_ERR(handle)) {
                up_read(&osb->journal->j_trans_barrier);

                mlog_errno(PTR_ERR(handle));

                if (is_journal_aborted(journal)) {
                        ocfs2_abort(osb->sb, "Detected aborted journal");
                        handle = ERR_PTR(-EROFS);
                }
        } else
                atomic_inc(&(osb->journal->j_num_trans));

        return handle;
}

int ocfs2_commit_trans(struct ocfs2_super *osb,
                       handle_t *handle)
{
        int ret;
        struct ocfs2_journal *journal = osb->journal;

        BUG_ON(!handle);

        ret = journal_stop(handle);
        if (ret < 0)
                mlog_errno(ret);

        up_read(&journal->j_trans_barrier);

        return ret;
}

/*
 * 'nblocks' is what you want to add to the current
 * transaction. extend_trans will either extend the current handle by
 * nblocks, or commit it and start a new one with nblocks credits.
 *
 * WARNING: This will not release any semaphores or disk locks taken
 * during the transaction, so make sure they were taken *before*
 * start_trans or we'll have ordering deadlocks.
 *
 * WARNING2: Note that we do *not* drop j_trans_barrier here. This is
 * good because transaction ids haven't yet been recorded on the
 * cluster locks associated with this handle.
 */
int ocfs2_extend_trans(handle_t *handle, int nblocks)
{
        int status;

        BUG_ON(!handle);
        BUG_ON(!nblocks);

        mlog_entry_void();

        mlog(0, "Trying to extend transaction by %d blocks\n", nblocks);

        status = journal_extend(handle, nblocks);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        if (status > 0) {
                mlog(0, "journal_extend failed, trying journal_restart\n");
                status = journal_restart(handle, nblocks);
                if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                }
        }

        status = 0;
bail:

        mlog_exit(status);
        return status;
}

int ocfs2_journal_access(handle_t *handle,
                         struct inode *inode,
                         struct buffer_head *bh,
                         int type)
{
        int status;

        BUG_ON(!inode);
        BUG_ON(!handle);
        BUG_ON(!bh);

        mlog_entry("bh->b_blocknr=%llu, type=%d (\"%s\"), bh->b_size = %zu\n",
                   (unsigned long long)bh->b_blocknr, type,
                   (type == OCFS2_JOURNAL_ACCESS_CREATE) ?
                   "OCFS2_JOURNAL_ACCESS_CREATE" :
                   "OCFS2_JOURNAL_ACCESS_WRITE",
                   bh->b_size);

        /* we can safely remove this assertion after testing. */
        if (!buffer_uptodate(bh)) {
                mlog(ML_ERROR, "giving me a buffer that's not uptodate!\n");
                mlog(ML_ERROR, "b_blocknr=%llu\n",
                     (unsigned long long)bh->b_blocknr);
                BUG();
        }

        /* Set the current transaction information on the inode so
         * that the locking code knows whether it can drop it's locks
         * on this inode or not. We're protected from the commit
         * thread updating the current transaction id until
         * ocfs2_commit_trans() because ocfs2_start_trans() took
         * j_trans_barrier for us. */
        ocfs2_set_inode_lock_trans(OCFS2_SB(inode->i_sb)->journal, inode);

        mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
        switch (type) {
        case OCFS2_JOURNAL_ACCESS_CREATE:
        case OCFS2_JOURNAL_ACCESS_WRITE:
                status = journal_get_write_access(handle, bh);
                break;

        case OCFS2_JOURNAL_ACCESS_UNDO:
                status = journal_get_undo_access(handle, bh);
                break;

        default:
                status = -EINVAL;
                mlog(ML_ERROR, "Uknown access type!\n");
        }
        mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);

        if (status < 0)
                mlog(ML_ERROR, "Error %d getting %d access to buffer!\n",
                     status, type);

        mlog_exit(status);
        return status;
}

int ocfs2_journal_dirty(handle_t *handle,
                        struct buffer_head *bh)
{
        int status;

        mlog_entry("(bh->b_blocknr=%llu)\n",
                   (unsigned long long)bh->b_blocknr);

        status = journal_dirty_metadata(handle, bh);
        if (status < 0)
                mlog(ML_ERROR, "Could not dirty metadata buffer. "
                     "(bh->b_blocknr=%llu)\n",
                     (unsigned long long)bh->b_blocknr);

        mlog_exit(status);
        return status;
}

int ocfs2_journal_dirty_data(handle_t *handle,
                             struct buffer_head *bh)
{
        int err = journal_dirty_data(handle, bh);
        if (err)
                mlog_errno(err);
        /* TODO: When we can handle it, abort the handle and go RO on
         * error here. */

        return err;
}

#define OCFS2_DEFAULT_COMMIT_INTERVAL   (HZ * 5)

void ocfs2_set_journal_params(struct ocfs2_super *osb)
{
        journal_t *journal = osb->journal->j_journal;

        spin_lock(&journal->j_state_lock);
        journal->j_commit_interval = OCFS2_DEFAULT_COMMIT_INTERVAL;
        if (osb->s_mount_opt & OCFS2_MOUNT_BARRIER)
                journal->j_flags |= JFS_BARRIER;
        else
                journal->j_flags &= ~JFS_BARRIER;
        spin_unlock(&journal->j_state_lock);
}

int ocfs2_journal_init(struct ocfs2_journal *journal, int *dirty)
{
        int status = -1;
        struct inode *inode = NULL; /* the journal inode */
        journal_t *j_journal = NULL;
        struct ocfs2_dinode *di = NULL;
        struct buffer_head *bh = NULL;
        struct ocfs2_super *osb;
        int meta_lock = 0;

        mlog_entry_void();

        BUG_ON(!journal);

        osb = journal->j_osb;

        /* already have the inode for our journal */
        inode = ocfs2_get_system_file_inode(osb, JOURNAL_SYSTEM_INODE,
                                            osb->slot_num);
        if (inode == NULL) {
                status = -EACCES;
                mlog_errno(status);
                goto done;
        }
        if (is_bad_inode(inode)) {
                mlog(ML_ERROR, "access error (bad inode)\n");
                iput(inode);
                inode = NULL;
                status = -EACCES;
                goto done;
        }

        SET_INODE_JOURNAL(inode);
        OCFS2_I(inode)->ip_open_count++;

        /* Skip recovery waits here - journal inode metadata never
         * changes in a live cluster so it can be considered an
         * exception to the rule. */
        status = ocfs2_meta_lock_full(inode, &bh, 1, OCFS2_META_LOCK_RECOVERY);
        if (status < 0) {
                if (status != -ERESTARTSYS)
                        mlog(ML_ERROR, "Could not get lock on journal!\n");
                goto done;
        }

        meta_lock = 1;
        di = (struct ocfs2_dinode *)bh->b_data;

        if (inode->i_size <  OCFS2_MIN_JOURNAL_SIZE) {
                mlog(ML_ERROR, "Journal file size (%lld) is too small!\n",
                     inode->i_size);
                status = -EINVAL;
                goto done;
        }

        mlog(0, "inode->i_size = %lld\n", inode->i_size);
        mlog(0, "inode->i_blocks = %llu\n",
                        (unsigned long long)inode->i_blocks);
        mlog(0, "inode->ip_clusters = %u\n", OCFS2_I(inode)->ip_clusters);

        /* call the kernels journal init function now */
        j_journal = journal_init_inode(inode);
        if (j_journal == NULL) {
                mlog(ML_ERROR, "Linux journal layer error\n");
                status = -EINVAL;
                goto done;
        }

        mlog(0, "Returned from journal_init_inode\n");
        mlog(0, "j_journal->j_maxlen = %u\n", j_journal->j_maxlen);

        *dirty = (le32_to_cpu(di->id1.journal1.ij_flags) &
                  OCFS2_JOURNAL_DIRTY_FL);

        journal->j_journal = j_journal;
        journal->j_inode = inode;
        journal->j_bh = bh;

        ocfs2_set_journal_params(osb);

        journal->j_state = OCFS2_JOURNAL_LOADED;

        status = 0;
done:
        if (status < 0) {
                if (meta_lock)
                        ocfs2_meta_unlock(inode, 1);
                if (bh != NULL)
                        brelse(bh);
                if (inode) {
                        OCFS2_I(inode)->ip_open_count--;
                        iput(inode);
                }
        }

        mlog_exit(status);
        return status;
}

static int ocfs2_journal_toggle_dirty(struct ocfs2_super *osb,
                                      int dirty)
{
        int status;
        unsigned int flags;
        struct ocfs2_journal *journal = osb->journal;
        struct buffer_head *bh = journal->j_bh;
        struct ocfs2_dinode *fe;

        mlog_entry_void();

        fe = (struct ocfs2_dinode *)bh->b_data;
        if (!OCFS2_IS_VALID_DINODE(fe)) {
                /* This is called from startup/shutdown which will
                 * handle the errors in a specific manner, so no need
                 * to call ocfs2_error() here. */
                mlog(ML_ERROR, "Journal dinode %llu  has invalid "
                     "signature: %.*s", (unsigned long long)fe->i_blkno, 7,
                     fe->i_signature);
                status = -EIO;
                goto out;
        }

        flags = le32_to_cpu(fe->id1.journal1.ij_flags);
        if (dirty)
                flags |= OCFS2_JOURNAL_DIRTY_FL;
        else
                flags &= ~OCFS2_JOURNAL_DIRTY_FL;
        fe->id1.journal1.ij_flags = cpu_to_le32(flags);

        status = ocfs2_write_block(osb, bh, journal->j_inode);
        if (status < 0)
                mlog_errno(status);

out:
        mlog_exit(status);
        return status;
}

/*
 * If the journal has been kmalloc'd it needs to be freed after this
 * call.
 */
void ocfs2_journal_shutdown(struct ocfs2_super *osb)
{
        struct ocfs2_journal *journal = NULL;
        int status = 0;
        struct inode *inode = NULL;
        int num_running_trans = 0;

        mlog_entry_void();

        BUG_ON(!osb);

        journal = osb->journal;
        if (!journal)
                goto done;

        inode = journal->j_inode;

        if (journal->j_state != OCFS2_JOURNAL_LOADED)
                goto done;

        /* need to inc inode use count as journal_destroy will iput. */
        if (!igrab(inode))
                BUG();

        num_running_trans = atomic_read(&(osb->journal->j_num_trans));
        if (num_running_trans > 0)
                mlog(0, "Shutting down journal: must wait on %d "
                     "running transactions!\n",
                     num_running_trans);

        /* Do a commit_cache here. It will flush our journal, *and*
         * release any locks that are still held.
         * set the SHUTDOWN flag and release the trans lock.
         * the commit thread will take the trans lock for us below. */
        journal->j_state = OCFS2_JOURNAL_IN_SHUTDOWN;

        /* The OCFS2_JOURNAL_IN_SHUTDOWN will signal to commit_cache to not
         * drop the trans_lock (which we want to hold until we
         * completely destroy the journal. */
        if (osb->commit_task) {
                /* Wait for the commit thread */
                mlog(0, "Waiting for ocfs2commit to exit....\n");
                kthread_stop(osb->commit_task);
                osb->commit_task = NULL;
        }

        BUG_ON(atomic_read(&(osb->journal->j_num_trans)) != 0);

        status = ocfs2_journal_toggle_dirty(osb, 0);
        if (status < 0)
                mlog_errno(status);

        /* Shutdown the kernel journal system */
        journal_destroy(journal->j_journal);

        OCFS2_I(inode)->ip_open_count--;

        /* unlock our journal */
        ocfs2_meta_unlock(inode, 1);

        brelse(journal->j_bh);
        journal->j_bh = NULL;

        journal->j_state = OCFS2_JOURNAL_FREE;

//      up_write(&journal->j_trans_barrier);
done:
        if (inode)
                iput(inode);
        mlog_exit_void();
}

static void ocfs2_clear_journal_error(struct super_block *sb,
                                      journal_t *journal,
                                      int slot)
{
        int olderr;

        olderr = journal_errno(journal);
        if (olderr) {
                mlog(ML_ERROR, "File system error %d recorded in "
                     "journal %u.\n", olderr, slot);
                mlog(ML_ERROR, "File system on device %s needs checking.\n",
                     sb->s_id);

                journal_ack_err(journal);
                journal_clear_err(journal);
        }
}

int ocfs2_journal_load(struct ocfs2_journal *journal)
{
        int status = 0;
        struct ocfs2_super *osb;

        mlog_entry_void();

        if (!journal)
                BUG();

        osb = journal->j_osb;

        status = journal_load(journal->j_journal);
        if (status < 0) {
                mlog(ML_ERROR, "Failed to load journal!\n");
                goto done;
        }

        ocfs2_clear_journal_error(osb->sb, journal->j_journal, osb->slot_num);

        status = ocfs2_journal_toggle_dirty(osb, 1);
        if (status < 0) {
                mlog_errno(status);
                goto done;
        }

        /* Launch the commit thread */
        osb->commit_task = kthread_run(ocfs2_commit_thread, osb, "ocfs2cmt");
        if (IS_ERR(osb->commit_task)) {
                status = PTR_ERR(osb->commit_task);
                osb->commit_task = NULL;
                mlog(ML_ERROR, "unable to launch ocfs2commit thread, error=%d",
                     status);
                goto done;
        }

done:
        mlog_exit(status);
        return status;
}


/* 'full' flag tells us whether we clear out all blocks or if we just
 * mark the journal clean */
int ocfs2_journal_wipe(struct ocfs2_journal *journal, int full)
{
        int status;

        mlog_entry_void();

        BUG_ON(!journal);

        status = journal_wipe(journal->j_journal, full);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        status = ocfs2_journal_toggle_dirty(journal->j_osb, 0);
        if (status < 0)
                mlog_errno(status);

bail:
        mlog_exit(status);
        return status;
}

/*
 * JBD Might read a cached version of another nodes journal file. We
 * don't want this as this file changes often and we get no
 * notification on those changes. The only way to be sure that we've
 * got the most up to date version of those blocks then is to force
 * read them off disk. Just searching through the buffer cache won't
 * work as there may be pages backing this file which are still marked
 * up to date. We know things can't change on this file underneath us
 * as we have the lock by now :)
 */
static int ocfs2_force_read_journal(struct inode *inode)
{
        int status = 0;
        int i, p_blocks;
        u64 v_blkno, p_blkno;
#define CONCURRENT_JOURNAL_FILL 32
        struct buffer_head *bhs[CONCURRENT_JOURNAL_FILL];

        mlog_entry_void();

        BUG_ON(inode->i_blocks !=
                     ocfs2_align_bytes_to_sectors(i_size_read(inode)));

        memset(bhs, 0, sizeof(struct buffer_head *) * CONCURRENT_JOURNAL_FILL);

        mlog(0, "Force reading %llu blocks\n",
                (unsigned long long)(inode->i_blocks >>
                        (inode->i_sb->s_blocksize_bits - 9)));

        v_blkno = 0;
        while (v_blkno <
               (inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9))) {

                status = ocfs2_extent_map_get_blocks(inode, v_blkno,
                                                     1, &p_blkno,
                                                     &p_blocks);
                if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                }

                if (p_blocks > CONCURRENT_JOURNAL_FILL)
                        p_blocks = CONCURRENT_JOURNAL_FILL;

                /* We are reading journal data which should not
                 * be put in the uptodate cache */
                status = ocfs2_read_blocks(OCFS2_SB(inode->i_sb),
                                           p_blkno, p_blocks, bhs, 0,
                                           NULL);
                if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                }

                for(i = 0; i < p_blocks; i++) {
                        brelse(bhs[i]);
                        bhs[i] = NULL;
                }

                v_blkno += p_blocks;
        }

bail:
        for(i = 0; i < CONCURRENT_JOURNAL_FILL; i++)
                if (bhs[i])
                        brelse(bhs[i]);
        mlog_exit(status);
        return status;
}

struct ocfs2_la_recovery_item {
        struct list_head        lri_list;
        int                     lri_slot;
        struct ocfs2_dinode     *lri_la_dinode;
        struct ocfs2_dinode     *lri_tl_dinode;
};

/* Does the second half of the recovery process. By this point, the
 * node is marked clean and can actually be considered recovered,
 * hence it's no longer in the recovery map, but there's still some
 * cleanup we can do which shouldn't happen within the recovery thread
 * as locking in that context becomes very difficult if we are to take
 * recovering nodes into account.
 *
 * NOTE: This function can and will sleep on recovery of other nodes
 * during cluster locking, just like any other ocfs2 process.
 */
void ocfs2_complete_recovery(struct work_struct *work)
{
        int ret;
        struct ocfs2_journal *journal =
                container_of(work, struct ocfs2_journal, j_recovery_work);
        struct ocfs2_super *osb = journal->j_osb;
        struct ocfs2_dinode *la_dinode, *tl_dinode;
        struct ocfs2_la_recovery_item *item;
        struct list_head *p, *n;
        LIST_HEAD(tmp_la_list);

        mlog_entry_void();

        mlog(0, "completing recovery from keventd\n");

        spin_lock(&journal->j_lock);
        list_splice_init(&journal->j_la_cleanups, &tmp_la_list);
        spin_unlock(&journal->j_lock);

        list_for_each_safe(p, n, &tmp_la_list) {
                item = list_entry(p, struct ocfs2_la_recovery_item, lri_list);
                list_del_init(&item->lri_list);

                mlog(0, "Complete recovery for slot %d\n", item->lri_slot);

                la_dinode = item->lri_la_dinode;
                if (la_dinode) {
                        mlog(0, "Clean up local alloc %llu\n",
                             (unsigned long long)la_dinode->i_blkno);

                        ret = ocfs2_complete_local_alloc_recovery(osb,
                                                                  la_dinode);
                        if (ret < 0)
                                mlog_errno(ret);

                        kfree(la_dinode);
                }

                tl_dinode = item->lri_tl_dinode;
                if (tl_dinode) {
                        mlog(0, "Clean up truncate log %llu\n",
                             (unsigned long long)tl_dinode->i_blkno);

                        ret = ocfs2_complete_truncate_log_recovery(osb,
                                                                   tl_dinode);
                        if (ret < 0)
                                mlog_errno(ret);

                        kfree(tl_dinode);
                }

                ret = ocfs2_recover_orphans(osb, item->lri_slot);
                if (ret < 0)
                        mlog_errno(ret);

                kfree(item);
        }

        mlog(0, "Recovery completion\n");
        mlog_exit_void();
}

/* NOTE: This function always eats your references to la_dinode and
 * tl_dinode, either manually on error, or by passing them to
 * ocfs2_complete_recovery */
static void ocfs2_queue_recovery_completion(struct ocfs2_journal *journal,
                                            int slot_num,
                                            struct ocfs2_dinode *la_dinode,
                                            struct ocfs2_dinode *tl_dinode)
{
        struct ocfs2_la_recovery_item *item;

        item = kmalloc(sizeof(struct ocfs2_la_recovery_item), GFP_NOFS);
        if (!item) {
                /* Though we wish to avoid it, we are in fact safe in
                 * skipping local alloc cleanup as fsck.ocfs2 is more
                 * than capable of reclaiming unused space. */
                if (la_dinode)
                        kfree(la_dinode);

                if (tl_dinode)
                        kfree(tl_dinode);

                mlog_errno(-ENOMEM);
                return;
        }

        INIT_LIST_HEAD(&item->lri_list);
        item->lri_la_dinode = la_dinode;
        item->lri_slot = slot_num;
        item->lri_tl_dinode = tl_dinode;

        spin_lock(&journal->j_lock);
        list_add_tail(&item->lri_list, &journal->j_la_cleanups);
        queue_work(ocfs2_wq, &journal->j_recovery_work);
        spin_unlock(&journal->j_lock);
}

/* Called by the mount code to queue recovery the last part of
 * recovery for it's own slot. */
void ocfs2_complete_mount_recovery(struct ocfs2_super *osb)
{
        struct ocfs2_journal *journal = osb->journal;

        if (osb->dirty) {
                /* No need to queue up our truncate_log as regular
                 * cleanup will catch that. */
                ocfs2_queue_recovery_completion(journal,
                                                osb->slot_num,
                                                osb->local_alloc_copy,
                                                NULL);
                ocfs2_schedule_truncate_log_flush(osb, 0);

                osb->local_alloc_copy = NULL;
                osb->dirty = 0;
        }
}

static int __ocfs2_recovery_thread(void *arg)
{
        int status, node_num;
        struct ocfs2_super *osb = arg;

        mlog_entry_void();

        status = ocfs2_wait_on_mount(osb);
        if (status < 0) {
                goto bail;
        }

restart:
        status = ocfs2_super_lock(osb, 1);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        while(!ocfs2_node_map_is_empty(osb, &osb->recovery_map)) {
                node_num = ocfs2_node_map_first_set_bit(osb,
                                                        &osb->recovery_map);
                if (node_num == O2NM_INVALID_NODE_NUM) {
                        mlog(0, "Out of nodes to recover.\n");
                        break;
                }

                status = ocfs2_recover_node(osb, node_num);
                if (status < 0) {
                        mlog(ML_ERROR,
                             "Error %d recovering node %d on device (%u,%u)!\n",
                             status, node_num,
                             MAJOR(osb->sb->s_dev), MINOR(osb->sb->s_dev));
                        mlog(ML_ERROR, "Volume requires unmount.\n");
                        continue;
                }

                ocfs2_recovery_map_clear(osb, node_num);
        }
        ocfs2_super_unlock(osb, 1);

        /* We always run recovery on our own orphan dir - the dead
         * node(s) may have voted "no" on an inode delete earlier. A
         * revote is therefore required. */
        ocfs2_queue_recovery_completion(osb->journal, osb->slot_num, NULL,
                                        NULL);

bail:
        mutex_lock(&osb->recovery_lock);
        if (!status &&
            !ocfs2_node_map_is_empty(osb, &osb->recovery_map)) {
                mutex_unlock(&osb->recovery_lock);
                goto restart;
        }

        osb->recovery_thread_task = NULL;
        mb(); /* sync with ocfs2_recovery_thread_running */
        wake_up(&osb->recovery_event);

        mutex_unlock(&osb->recovery_lock);

        mlog_exit(status);
        /* no one is callint kthread_stop() for us so the kthread() api
         * requires that we call do_exit().  And it isn't exported, but
         * complete_and_exit() seems to be a minimal wrapper around it. */
        complete_and_exit(NULL, status);
        return status;
}

void ocfs2_recovery_thread(struct ocfs2_super *osb, int node_num)
{
        mlog_entry("(node_num=%d, osb->node_num = %d)\n",
                   node_num, osb->node_num);

        mutex_lock(&osb->recovery_lock);
        if (osb->disable_recovery)
                goto out;

        /* People waiting on recovery will wait on
         * the recovery map to empty. */
        if (!ocfs2_recovery_map_set(osb, node_num))
                mlog(0, "node %d already be in recovery.\n", node_num);

        mlog(0, "starting recovery thread...\n");

        if (osb->recovery_thread_task)
                goto out;

        osb->recovery_thread_task =  kthread_run(__ocfs2_recovery_thread, osb,
                                                 "ocfs2rec");
        if (IS_ERR(osb->recovery_thread_task)) {
                mlog_errno((int)PTR_ERR(osb->recovery_thread_task));
                osb->recovery_thread_task = NULL;
        }

out:
        mutex_unlock(&osb->recovery_lock);
        wake_up(&osb->recovery_event);

        mlog_exit_void();
}

/* Does the actual journal replay and marks the journal inode as
 * clean. Will only replay if the journal inode is marked dirty. */
static int ocfs2_replay_journal(struct ocfs2_super *osb,
                                int node_num,
                                int slot_num)
{
        int status;
        int got_lock = 0;
        unsigned int flags;
        struct inode *inode = NULL;
        struct ocfs2_dinode *fe;
        journal_t *journal = NULL;
        struct buffer_head *bh = NULL;

        inode = ocfs2_get_system_file_inode(osb, JOURNAL_SYSTEM_INODE,
                                            slot_num);
        if (inode == NULL) {
                status = -EACCES;
                mlog_errno(status);
                goto done;
        }
        if (is_bad_inode(inode)) {
                status = -EACCES;
                iput(inode);
                inode = NULL;
                mlog_errno(status);
                goto done;
        }
        SET_INODE_JOURNAL(inode);

        status = ocfs2_meta_lock_full(inode, &bh, 1, OCFS2_META_LOCK_RECOVERY);
        if (status < 0) {
                mlog(0, "status returned from ocfs2_meta_lock=%d\n", status);
                if (status != -ERESTARTSYS)
                        mlog(ML_ERROR, "Could not lock journal!\n");
                goto done;
        }
        got_lock = 1;

        fe = (struct ocfs2_dinode *) bh->b_data;

        flags = le32_to_cpu(fe->id1.journal1.ij_flags);

        if (!(flags & OCFS2_JOURNAL_DIRTY_FL)) {
                mlog(0, "No recovery required for node %d\n", node_num);
                goto done;
        }

        mlog(ML_NOTICE, "Recovering node %d from slot %d on device (%u,%u)\n",
             node_num, slot_num,
             MAJOR(osb->sb->s_dev), MINOR(osb->sb->s_dev));

        OCFS2_I(inode)->ip_clusters = le32_to_cpu(fe->i_clusters);

        status = ocfs2_force_read_journal(inode);
        if (status < 0) {
                mlog_errno(status);
                goto done;
        }

        mlog(0, "calling journal_init_inode\n");
        journal = journal_init_inode(inode);
        if (journal == NULL) {
                mlog(ML_ERROR, "Linux journal layer error\n");
                status = -EIO;
                goto done;
        }

        status = journal_load(journal);
        if (status < 0) {
                mlog_errno(status);
                if (!igrab(inode))
                        BUG();
                journal_destroy(journal);
                goto done;
        }

        ocfs2_clear_journal_error(osb->sb, journal, slot_num);

        /* wipe the journal */
        mlog(0, "flushing the journal.\n");
        journal_lock_updates(journal);
        status = journal_flush(journal);
        journal_unlock_updates(journal);
        if (status < 0)
                mlog_errno(status);

        /* This will mark the node clean */
        flags = le32_to_cpu(fe->id1.journal1.ij_flags);
        flags &= ~OCFS2_JOURNAL_DIRTY_FL;
        fe->id1.journal1.ij_flags = cpu_to_le32(flags);

        status = ocfs2_write_block(osb, bh, inode);
        if (status < 0)
                mlog_errno(status);

        if (!igrab(inode))
                BUG();

        journal_destroy(journal);

done:
        /* drop the lock on this nodes journal */
        if (got_lock)
                ocfs2_meta_unlock(inode, 1);

        if (inode)
                iput(inode);

        if (bh)
                brelse(bh);

        mlog_exit(status);
        return status;
}

/*
 * Do the most important parts of node recovery:
 *  - Replay it's journal
 *  - Stamp a clean local allocator file
 *  - Stamp a clean truncate log
 *  - Mark the node clean
 *
 * If this function completes without error, a node in OCFS2 can be
 * said to have been safely recovered. As a result, failure during the
 * second part of a nodes recovery process (local alloc recovery) is
 * far less concerning.
 */
static int ocfs2_recover_node(struct ocfs2_super *osb,
                              int node_num)
{
        int status = 0;
        int slot_num;
        struct ocfs2_slot_info *si = osb->slot_info;
        struct ocfs2_dinode *la_copy = NULL;
        struct ocfs2_dinode *tl_copy = NULL;

        mlog_entry("(node_num=%d, osb->node_num = %d)\n",
                   node_num, osb->node_num);

        mlog(0, "checking node %d\n", node_num);

        /* Should not ever be called to recover ourselves -- in that
         * case we should've called ocfs2_journal_load instead. */
        BUG_ON(osb->node_num == node_num);

        slot_num = ocfs2_node_num_to_slot(si, node_num);
        if (slot_num == OCFS2_INVALID_SLOT) {
                status = 0;
                mlog(0, "no slot for this node, so no recovery required.\n");
                goto done;
        }

        mlog(0, "node %d was using slot %d\n", node_num, slot_num);

        status = ocfs2_replay_journal(osb, node_num, slot_num);
        if (status < 0) {
                mlog_errno(status);
                goto done;
        }

        /* Stamp a clean local alloc file AFTER recovering the journal... */
        status = ocfs2_begin_local_alloc_recovery(osb, slot_num, &la_copy);
        if (status < 0) {
                mlog_errno(status);
                goto done;
        }

        /* An error from begin_truncate_log_recovery is not
         * serious enough to warrant halting the rest of
         * recovery. */
        status = ocfs2_begin_truncate_log_recovery(osb, slot_num, &tl_copy);
        if (status < 0)
                mlog_errno(status);

        /* Likewise, this would be a strange but ultimately not so
         * harmful place to get an error... */
        ocfs2_clear_slot(si, slot_num);
        status = ocfs2_update_disk_slots(osb, si);
        if (status < 0)
                mlog_errno(status);

        /* This will kfree the memory pointed to by la_copy and tl_copy */
        ocfs2_queue_recovery_completion(osb->journal, slot_num, la_copy,
                                        tl_copy);

        status = 0;
done:

        mlog_exit(status);
        return status;
}

/* Test node liveness by trylocking his journal. If we get the lock,
 * we drop it here. Return 0 if we got the lock, -EAGAIN if node is
 * still alive (we couldn't get the lock) and < 0 on error. */
static int ocfs2_trylock_journal(struct ocfs2_super *osb,
                                 int slot_num)
{
        int status, flags;
        struct inode *inode = NULL;

        inode = ocfs2_get_system_file_inode(osb, JOURNAL_SYSTEM_INODE,
                                            slot_num);
        if (inode == NULL) {
                mlog(ML_ERROR, "access error\n");
                status = -EACCES;
                goto bail;
        }
        if (is_bad_inode(inode)) {
                mlog(ML_ERROR, "access error (bad inode)\n");
                iput(inode);
                inode = NULL;
                status = -EACCES;
                goto bail;
        }
        SET_INODE_JOURNAL(inode);

        flags = OCFS2_META_LOCK_RECOVERY | OCFS2_META_LOCK_NOQUEUE;
        status = ocfs2_meta_lock_full(inode, NULL, 1, flags);
        if (status < 0) {
                if (status != -EAGAIN)
                        mlog_errno(status);
                goto bail;
        }

        ocfs2_meta_unlock(inode, 1);
bail:
        if (inode)
                iput(inode);

        return status;
}

/* Call this underneath ocfs2_super_lock. It also assumes that the
 * slot info struct has been updated from disk. */
int ocfs2_mark_dead_nodes(struct ocfs2_super *osb)
{
        int status, i, node_num;
        struct ocfs2_slot_info *si = osb->slot_info;

        /* This is called with the super block cluster lock, so we
         * know that the slot map can't change underneath us. */

        spin_lock(&si->si_lock);
        for(i = 0; i < si->si_num_slots; i++) {
                if (i == osb->slot_num)
                        continue;
                if (ocfs2_is_empty_slot(si, i))
                        continue;

                node_num = si->si_global_node_nums[i];
                if (ocfs2_node_map_test_bit(osb, &osb->recovery_map, node_num))
                        continue;
                spin_unlock(&si->si_lock);

                /* Ok, we have a slot occupied by another node which
                 * is not in the recovery map. We trylock his journal
                 * file here to test if he's alive. */
                status = ocfs2_trylock_journal(osb, i);
                if (!status) {
                        /* Since we're called from mount, we know that
                         * the recovery thread can't race us on
                         * setting / checking the recovery bits. */
                        ocfs2_recovery_thread(osb, node_num);
                } else if ((status < 0) && (status != -EAGAIN)) {
                        mlog_errno(status);
                        goto bail;
                }

                spin_lock(&si->si_lock);
        }
        spin_unlock(&si->si_lock);

        status = 0;
bail:
        mlog_exit(status);
        return status;
}

static int ocfs2_queue_orphans(struct ocfs2_super *osb,
                               int slot,
                               struct inode **head)
{
        int status;
        struct inode *orphan_dir_inode = NULL;
        struct inode *iter;
        unsigned long offset, blk, local;
        struct buffer_head *bh = NULL;
        struct ocfs2_dir_entry *de;
        struct super_block *sb = osb->sb;

        orphan_dir_inode = ocfs2_get_system_file_inode(osb,
                                                       ORPHAN_DIR_SYSTEM_INODE,
                                                       slot);
        if  (!orphan_dir_inode) {
                status = -ENOENT;
                mlog_errno(status);
                return status;
        }       

        mutex_lock(&orphan_dir_inode->i_mutex);
        status = ocfs2_meta_lock(orphan_dir_inode, NULL, 0);
        if (status < 0) {
                mlog_errno(status);
                goto out;
        }

        offset = 0;
        iter = NULL;
        while(offset < i_size_read(orphan_dir_inode)) {
                blk = offset >> sb->s_blocksize_bits;

                bh = ocfs2_bread(orphan_dir_inode, blk, &status, 0);
                if (!bh)
                        status = -EINVAL;
                if (status < 0) {
                        if (bh)
                                brelse(bh);
                        mlog_errno(status);
                        goto out_unlock;
                }

                local = 0;
                while(offset < i_size_read(orphan_dir_inode)
                      && local < sb->s_blocksize) {
                        de = (struct ocfs2_dir_entry *) (bh->b_data + local);

                        if (!ocfs2_check_dir_entry(orphan_dir_inode,
                                                  de, bh, local)) {
                                status = -EINVAL;
                                mlog_errno(status);
                                brelse(bh);
                                goto out_unlock;
                        }

                        local += le16_to_cpu(de->rec_len);
                        offset += le16_to_cpu(de->rec_len);

                        /* I guess we silently fail on no inode? */
                        if (!le64_to_cpu(de->inode))
                                continue;
                        if (de->file_type > OCFS2_FT_MAX) {
                                mlog(ML_ERROR,
                                     "block %llu contains invalid de: "
                                     "inode = %llu, rec_len = %u, "
                                     "name_len = %u, file_type = %u, "
                                     "name='%.*s'\n",
                                     (unsigned long long)bh->b_blocknr,
                                     (unsigned long long)le64_to_cpu(de->inode),
                                     le16_to_cpu(de->rec_len),
                                     de->name_len,
                                     de->file_type,
                                     de->name_len,
                                     de->name);
                                continue;
                        }
                        if (de->name_len == 1 && !strncmp(".", de->name, 1))
                                continue;
                        if (de->name_len == 2 && !strncmp("..", de->name, 2))
                                continue;

                        iter = ocfs2_iget(osb, le64_to_cpu(de->inode),
                                          OCFS2_FI_FLAG_NOLOCK);
                        if (IS_ERR(iter))
                                continue;

                        mlog(0, "queue orphan %llu\n",
                             (unsigned long long)OCFS2_I(iter)->ip_blkno);
                        /* No locking is required for the next_orphan
                         * queue as there is only ever a single
                         * process doing orphan recovery. */
                        OCFS2_I(iter)->ip_next_orphan = *head;
                        *head = iter;
                }
                brelse(bh);
        }

out_unlock:
        ocfs2_meta_unlock(orphan_dir_inode, 0);
out:
        mutex_unlock(&orphan_dir_inode->i_mutex);
        iput(orphan_dir_inode);
        return status;
}

static int ocfs2_orphan_recovery_can_continue(struct ocfs2_super *osb,
                                              int slot)
{
        int ret;

        spin_lock(&osb->osb_lock);
        ret = !osb->osb_orphan_wipes[slot];
        spin_unlock(&osb->osb_lock);
        return ret;
}

static void ocfs2_mark_recovering_orphan_dir(struct ocfs2_super *osb,
                                             int slot)
{
        spin_lock(&osb->osb_lock);
        /* Mark ourselves such that new processes in delete_inode()
         * know to quit early. */
        ocfs2_node_map_set_bit(osb, &osb->osb_recovering_orphan_dirs, slot);
        while (osb->osb_orphan_wipes[slot]) {
                /* If any processes are already in the middle of an
                 * orphan wipe on this dir, then we need to wait for
                 * them. */
                spin_unlock(&osb->osb_lock);
                wait_event_interruptible(osb->osb_wipe_event,
                                         ocfs2_orphan_recovery_can_continue(osb, slot));
                spin_lock(&osb->osb_lock);
        }
        spin_unlock(&osb->osb_lock);
}

static void ocfs2_clear_recovering_orphan_dir(struct ocfs2_super *osb,
                                              int slot)
{
        ocfs2_node_map_clear_bit(osb, &osb->osb_recovering_orphan_dirs, slot);
}

/*
 * Orphan recovery. Each mounted node has it's own orphan dir which we
 * must run during recovery. Our strategy here is to build a list of
 * the inodes in the orphan dir and iget/iput them. The VFS does
 * (most) of the rest of the work.
 *
 * Orphan recovery can happen at any time, not just mount so we have a
 * couple of extra considerations.
 *
 * - We grab as many inodes as we can under the orphan dir lock -
 *   doing iget() outside the orphan dir risks getting a reference on
 *   an invalid inode.
 * - We must be sure not to deadlock with other processes on the
 *   system wanting to run delete_inode(). This can happen when they go
 *   to lock the orphan dir and the orphan recovery process attempts to
 *   iget() inside the orphan dir lock. This can be avoided by
 *   advertising our state to ocfs2_delete_inode().
 */
static int ocfs2_recover_orphans(struct ocfs2_super *osb,
                                 int slot)
{
        int ret = 0;
        struct inode *inode = NULL;
        struct inode *iter;
        struct ocfs2_inode_info *oi;

        mlog(0, "Recover inodes from orphan dir in slot %d\n", slot);

        ocfs2_mark_recovering_orphan_dir(osb, slot);
        ret = ocfs2_queue_orphans(osb, slot, &inode);
        ocfs2_clear_recovering_orphan_dir(osb, slot);

        /* Error here should be noted, but we want to continue with as
         * many queued inodes as we've got. */
        if (ret)
                mlog_errno(ret);

        while (inode) {
                oi = OCFS2_I(inode);
                mlog(0, "iput orphan %llu\n", (unsigned long long)oi->ip_blkno);

                iter = oi->ip_next_orphan;

                spin_lock(&oi->ip_lock);
                /* Delete voting may have set these on the assumption
                 * that the other node would wipe them successfully.
                 * If they are still in the node's orphan dir, we need
                 * to reset that state. */
                oi->ip_flags &= ~(OCFS2_INODE_DELETED|OCFS2_INODE_SKIP_DELETE);

                /* Set the proper information to get us going into
                 * ocfs2_delete_inode. */
                oi->ip_flags |= OCFS2_INODE_MAYBE_ORPHANED;
                oi->ip_orphaned_slot = slot;
                spin_unlock(&oi->ip_lock);

                iput(inode);

                inode = iter;
        }

        return ret;
}

static int ocfs2_wait_on_mount(struct ocfs2_super *osb)
{
        /* This check is good because ocfs2 will wait on our recovery
         * thread before changing it to something other than MOUNTED
         * or DISABLED. */
        wait_event(osb->osb_mount_event,
                   atomic_read(&osb->vol_state) == VOLUME_MOUNTED ||
                   atomic_read(&osb->vol_state) == VOLUME_DISABLED);

        /* If there's an error on mount, then we may never get to the
         * MOUNTED flag, but this is set right before
         * dismount_volume() so we can trust it. */
        if (atomic_read(&osb->vol_state) == VOLUME_DISABLED) {
                mlog(0, "mount error, exiting!\n");
                return -EBUSY;
        }

        return 0;
}

static int ocfs2_commit_thread(void *arg)
{
        int status;
        struct ocfs2_super *osb = arg;
        struct ocfs2_journal *journal = osb->journal;

        /* we can trust j_num_trans here because _should_stop() is only set in
         * shutdown and nobody other than ourselves should be able to start
         * transactions.  committing on shutdown might take a few iterations
         * as final transactions put deleted inodes on the list */
        while (!(kthread_should_stop() &&
                 atomic_read(&journal->j_num_trans) == 0)) {

                wait_event_interruptible(osb->checkpoint_event,
                                         atomic_read(&journal->j_num_trans)
                                         || kthread_should_stop());

                status = ocfs2_commit_cache(osb);
                if (status < 0)
                        mlog_errno(status);

                if (kthread_should_stop() && atomic_read(&journal->j_num_trans)){
                        mlog(ML_KTHREAD,
                             "commit_thread: %u transactions pending on "
                             "shutdown\n",
                             atomic_read(&journal->j_num_trans));
                }
        }

        return 0;
}

/* Look for a dirty journal without taking any cluster locks. Used for
 * hard readonly access to determine whether the file system journals
 * require recovery. */
int ocfs2_check_journals_nolocks(struct ocfs2_super *osb)
{
        int ret = 0;
        unsigned int slot;
        struct buffer_head *di_bh;
        struct ocfs2_dinode *di;
        struct inode *journal = NULL;

        for(slot = 0; slot < osb->max_slots; slot++) {
                journal = ocfs2_get_system_file_inode(osb,
                                                      JOURNAL_SYSTEM_INODE,
                                                      slot);
                if (!journal || is_bad_inode(journal)) {
                        ret = -EACCES;
                        mlog_errno(ret);
                        goto out;
                }

                di_bh = NULL;
                ret = ocfs2_read_block(osb, OCFS2_I(journal)->ip_blkno, &di_bh,
                                       0, journal);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out;
                }

                di = (struct ocfs2_dinode *) di_bh->b_data;

                if (le32_to_cpu(di->id1.journal1.ij_flags) &
                    OCFS2_JOURNAL_DIRTY_FL)
                        ret = -EROFS;

                brelse(di_bh);
                if (ret)
                        break;
        }

out:
        if (journal)
                iput(journal);

        return ret;
}