ocfs2: Don't check for NULL before brelse()

[safe/jmp/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 "dir.h"
#include "dlmglue.h"
#include "extent_map.h"
#include "heartbeat.h"
#include "inode.h"
#include "journal.h"
#include "localalloc.h"
#include "slot_map.h"
#include "super.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, int replayed);
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);


/*
 * The recovery_list is a simple linked list of node numbers to recover.
 * It is protected by the recovery_lock.
 */

struct ocfs2_recovery_map {
        unsigned int rm_used;
        unsigned int *rm_entries;
};

int ocfs2_recovery_init(struct ocfs2_super *osb)
{
        struct ocfs2_recovery_map *rm;

        mutex_init(&osb->recovery_lock);
        osb->disable_recovery = 0;
        osb->recovery_thread_task = NULL;
        init_waitqueue_head(&osb->recovery_event);

        rm = kzalloc(sizeof(struct ocfs2_recovery_map) +
                     osb->max_slots * sizeof(unsigned int),
                     GFP_KERNEL);
        if (!rm) {
                mlog_errno(-ENOMEM);
                return -ENOMEM;
        }

        rm->rm_entries = (unsigned int *)((char *)rm +
                                          sizeof(struct ocfs2_recovery_map));
        osb->recovery_map = rm;

        return 0;
}

/* we can't grab the goofy sem lock from inside wait_event, so we use
 * memory barriers to make sure that we'll see the null task before
 * being woken up */
static int ocfs2_recovery_thread_running(struct ocfs2_super *osb)
{
        mb();
        return osb->recovery_thread_task != NULL;
}

void ocfs2_recovery_exit(struct ocfs2_super *osb)
{
        struct ocfs2_recovery_map *rm;

        /* disable any new recovery threads and wait for any currently
         * running ones to exit. Do this before setting the vol_state. */
        mutex_lock(&osb->recovery_lock);
        osb->disable_recovery = 1;
        mutex_unlock(&osb->recovery_lock);
        wait_event(osb->recovery_event, !ocfs2_recovery_thread_running(osb));

        /* At this point, we know that no more recovery threads can be
         * launched, so wait for any recovery completion work to
         * complete. */
        flush_workqueue(ocfs2_wq);

        /*
         * Now that recovery is shut down, and the osb is about to be
         * freed,  the osb_lock is not taken here.
         */
        rm = osb->recovery_map;
        /* XXX: Should we bug if there are dirty entries? */

        kfree(rm);
}

static int __ocfs2_recovery_map_test(struct ocfs2_super *osb,
                                     unsigned int node_num)
{
        int i;
        struct ocfs2_recovery_map *rm = osb->recovery_map;

        assert_spin_locked(&osb->osb_lock);

        for (i = 0; i < rm->rm_used; i++) {
                if (rm->rm_entries[i] == node_num)
                        return 1;
        }

        return 0;
}

/* Behaves like test-and-set.  Returns the previous value */
static int ocfs2_recovery_map_set(struct ocfs2_super *osb,
                                  unsigned int node_num)
{
        struct ocfs2_recovery_map *rm = osb->recovery_map;

        spin_lock(&osb->osb_lock);
        if (__ocfs2_recovery_map_test(osb, node_num)) {
                spin_unlock(&osb->osb_lock);
                return 1;
        }

        /* XXX: Can this be exploited? Not from o2dlm... */
        BUG_ON(rm->rm_used >= osb->max_slots);

        rm->rm_entries[rm->rm_used] = node_num;
        rm->rm_used++;
        spin_unlock(&osb->osb_lock);

        return 0;
}

static void ocfs2_recovery_map_clear(struct ocfs2_super *osb,
                                     unsigned int node_num)
{
        int i;
        struct ocfs2_recovery_map *rm = osb->recovery_map;

        spin_lock(&osb->osb_lock);

        for (i = 0; i < rm->rm_used; i++) {
                if (rm->rm_entries[i] == node_num)
                        break;
        }

        if (i < rm->rm_used) {
                /* XXX: be careful with the pointer math */
                memmove(&(rm->rm_entries[i]), &(rm->rm_entries[i + 1]),
                        (rm->rm_used - i - 1) * sizeof(unsigned int));
                rm->rm_used--;
        }

        spin_unlock(&osb->osb_lock);
}

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;
        }

        jbd2_journal_lock_updates(journal->j_journal);
        status = jbd2_journal_flush(journal->j_journal);
        jbd2_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_wake_downconvert_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 = jbd2_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 {
                if (!ocfs2_mount_local(osb))
                        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 = jbd2_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.
 *
 * This might call jbd2_journal_restart() which will commit dirty buffers
 * and then restart the transaction. Before calling
 * ocfs2_extend_trans(), any changed blocks should have been
 * dirtied. After calling it, all blocks which need to be changed must
 * go through another set of journal_access/journal_dirty calls.
 *
 * 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);

#ifdef CONFIG_OCFS2_DEBUG_FS
        status = 1;
#else
        status = jbd2_journal_extend(handle, nblocks);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }
#endif

        if (status > 0) {
                mlog(0,
                     "jbd2_journal_extend failed, trying "
                     "jbd2_journal_restart\n");
                status = jbd2_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 = jbd2_journal_get_write_access(handle, bh);
                break;

        case OCFS2_JOURNAL_ACCESS_UNDO:
                status = jbd2_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 = jbd2_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;
}

#ifdef CONFIG_OCFS2_COMPAT_JBD
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;
}
#endif

#define OCFS2_DEFAULT_COMMIT_INTERVAL   (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE)

void ocfs2_set_journal_params(struct ocfs2_super *osb)
{
        journal_t *journal = osb->journal->j_journal;
        unsigned long commit_interval = OCFS2_DEFAULT_COMMIT_INTERVAL;

        if (osb->osb_commit_interval)
                commit_interval = osb->osb_commit_interval;

        spin_lock(&journal->j_state_lock);
        journal->j_commit_interval = commit_interval;
        if (osb->s_mount_opt & OCFS2_MOUNT_BARRIER)
                journal->j_flags |= JBD2_BARRIER;
        else
                journal->j_flags &= ~JBD2_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 inode_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_inode_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;
        }

        inode_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 = jbd2_journal_init_inode(inode);
        if (j_journal == NULL) {
                mlog(ML_ERROR, "Linux journal layer error\n");
                status = -EINVAL;
                goto done;
        }

        mlog(0, "Returned from jbd2_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 (inode_lock)
                        ocfs2_inode_unlock(inode, 1);
                brelse(bh);
                if (inode) {
                        OCFS2_I(inode)->ip_open_count--;
                        iput(inode);
                }
        }

        mlog_exit(status);
        return status;
}

static void ocfs2_bump_recovery_generation(struct ocfs2_dinode *di)
{
        le32_add_cpu(&(di->id1.journal1.ij_recovery_generation), 1);
}

static u32 ocfs2_get_recovery_generation(struct ocfs2_dinode *di)
{
        return le32_to_cpu(di->id1.journal1.ij_recovery_generation);
}

static int ocfs2_journal_toggle_dirty(struct ocfs2_super *osb,
                                      int dirty, int replayed)
{
        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)le64_to_cpu(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);

        if (replayed)
                ocfs2_bump_recovery_generation(fe);

        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 - jbd2_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);

        if (ocfs2_mount_local(osb)) {
                jbd2_journal_lock_updates(journal->j_journal);
                status = jbd2_journal_flush(journal->j_journal);
                jbd2_journal_unlock_updates(journal->j_journal);
                if (status < 0)
                        mlog_errno(status);
        }

        if (status == 0) {
                /*
                 * Do not toggle if flush was unsuccessful otherwise
                 * will leave dirty metadata in a "clean" journal
                 */
                status = ocfs2_journal_toggle_dirty(osb, 0, 0);
                if (status < 0)
                        mlog_errno(status);
        }

        /* Shutdown the kernel journal system */
        jbd2_journal_destroy(journal->j_journal);

        OCFS2_I(inode)->ip_open_count--;

        /* unlock our journal */
        ocfs2_inode_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 = jbd2_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);

                jbd2_journal_ack_err(journal);
                jbd2_journal_clear_err(journal);
        }
}

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

        mlog_entry_void();

        BUG_ON(!journal);

        osb = journal->j_osb;

        status = jbd2_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, replayed);
        if (status < 0) {
                mlog_errno(status);
                goto done;
        }

        /* Launch the commit thread */
        if (!local) {
                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;
                }
        } else
                osb->commit_task = NULL;

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 = jbd2_journal_wipe(journal->j_journal, full);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

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

bail:
        mlog_exit(status);
        return status;
}

static int ocfs2_recovery_completed(struct ocfs2_super *osb)
{
        int empty;
        struct ocfs2_recovery_map *rm = osb->recovery_map;

        spin_lock(&osb->osb_lock);
        empty = (rm->rm_used == 0);
        spin_unlock(&osb->osb_lock);

        return empty;
}

void ocfs2_wait_for_recovery(struct ocfs2_super *osb)
{
        wait_event(osb->recovery_event, ocfs2_recovery_completed(osb));
}

/*
 * 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;
        u64 v_blkno, p_blkno, p_blocks, num_blocks;
#define CONCURRENT_JOURNAL_FILL 32ULL
        struct buffer_head *bhs[CONCURRENT_JOURNAL_FILL];

        mlog_entry_void();

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

        num_blocks = ocfs2_blocks_for_bytes(inode->i_sb, inode->i_size);
        v_blkno = 0;
        while (v_blkno < num_blocks) {
                status = ocfs2_extent_map_get_blocks(inode, v_blkno,
                                                     &p_blkno, &p_blocks, NULL);
                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++)
                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, *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_entry_safe(item, n, &tmp_la_list, 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)le64_to_cpu(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)le64_to_cpu(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;
        struct ocfs2_recovery_map *rm = osb->recovery_map;

        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;
        }

        spin_lock(&osb->osb_lock);
        while (rm->rm_used) {
                /* It's always safe to remove entry zero, as we won't
                 * clear it until ocfs2_recover_node() has succeeded. */
                node_num = rm->rm_entries[0];
                spin_unlock(&osb->osb_lock);

                status = ocfs2_recover_node(osb, node_num);
                if (!status) {
                        ocfs2_recovery_map_clear(osb, node_num);
                } else {
                        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");
                }

                spin_lock(&osb->osb_lock);
        }
        spin_unlock(&osb->osb_lock);
        mlog(0, "All nodes recovered\n");

        /* Refresh all journal recovery generations from disk */
        status = ocfs2_check_journals_nolocks(osb);
        status = (status == -EROFS) ? 0 : status;
        if (status < 0)
                mlog_errno(status);

        ocfs2_super_unlock(osb, 1);

        /* We always run recovery on our own orphan dir - the dead
         * node(s) may have disallowd a previos inode delete. Re-processing
         * is therefore required. */
        ocfs2_queue_recovery_completion(osb->journal, osb->slot_num, NULL,
                                        NULL);

bail:
        mutex_lock(&osb->recovery_lock);
        if (!status && !ocfs2_recovery_completed(osb)) {
                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 in recovery map.\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();
}

static int ocfs2_read_journal_inode(struct ocfs2_super *osb,
                                    int slot_num,
                                    struct buffer_head **bh,
                                    struct inode **ret_inode)
{
        int status = -EACCES;
        struct inode *inode = NULL;

        BUG_ON(slot_num >= osb->max_slots);

        inode = ocfs2_get_system_file_inode(osb, JOURNAL_SYSTEM_INODE,
                                            slot_num);
        if (!inode || is_bad_inode(inode)) {
                mlog_errno(status);
                goto bail;
        }
        SET_INODE_JOURNAL(inode);

        status = ocfs2_read_block(osb, OCFS2_I(inode)->ip_blkno, bh, 0, inode);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        status = 0;

bail:
        if (inode) {
                if (status || !ret_inode)
                        iput(inode);
                else
                        *ret_inode = inode;
        }
        return status;
}

/* 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;
        u32 slot_reco_gen;

        status = ocfs2_read_journal_inode(osb, slot_num, &bh, &inode);
        if (status) {
                mlog_errno(status);
                goto done;
        }

        fe = (struct ocfs2_dinode *)bh->b_data;
        slot_reco_gen = ocfs2_get_recovery_generation(fe);
        brelse(bh);
        bh = NULL;

        /*
         * As the fs recovery is asynchronous, there is a small chance that
         * another node mounted (and recovered) the slot before the recovery
         * thread could get the lock. To handle that, we dirty read the journal
         * inode for that slot to get the recovery generation. If it is
         * different than what we expected, the slot has been recovered.
         * If not, it needs recovery.
         */
        if (osb->slot_recovery_generations[slot_num] != slot_reco_gen) {
                mlog(0, "Slot %u already recovered (old/new=%u/%u)\n", slot_num,
                     osb->slot_recovery_generations[slot_num], slot_reco_gen);
                osb->slot_recovery_generations[slot_num] = slot_reco_gen;
                status = -EBUSY;
                goto done;
        }

        /* Continue with recovery as the journal has not yet been recovered */

        status = ocfs2_inode_lock_full(inode, &bh, 1, OCFS2_META_LOCK_RECOVERY);
        if (status < 0) {
                mlog(0, "status returned from ocfs2_inode_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);
        slot_reco_gen = ocfs2_get_recovery_generation(fe);

        if (!(flags & OCFS2_JOURNAL_DIRTY_FL)) {
                mlog(0, "No recovery required for node %d\n", node_num);
                /* Refresh recovery generation for the slot */
                osb->slot_recovery_generations[slot_num] = slot_reco_gen;
                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 = jbd2_journal_init_inode(inode);
        if (journal == NULL) {
                mlog(ML_ERROR, "Linux journal layer error\n");
                status = -EIO;
                goto done;
        }

        status = jbd2_journal_load(journal);
        if (status < 0) {
                mlog_errno(status);
                if (!igrab(inode))
                        BUG();
                jbd2_journal_destroy(journal);
                goto done;
        }

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

        /* wipe the journal */
        mlog(0, "flushing the journal.\n");
        jbd2_journal_lock_updates(journal);
        status = jbd2_journal_flush(journal);
        jbd2_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);

        /* Increment recovery generation to indicate successful recovery */
        ocfs2_bump_recovery_generation(fe);
        osb->slot_recovery_generations[slot_num] =
                                        ocfs2_get_recovery_generation(fe);

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

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

        jbd2_journal_destroy(journal);

done:
        /* drop the lock on this nodes journal */
        if (got_lock)
                ocfs2_inode_unlock(inode, 1);

        if (inode)
                iput(inode);

        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_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(osb, node_num);
        if (slot_num == -ENOENT) {
                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) {
                if (status == -EBUSY) {
                        mlog(0, "Skipping recovery for slot %u (node %u) "
                             "as another node has recovered it\n", slot_num,
                             node_num);
                        status = 0;
                        goto done;
                }
                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... */
        status = ocfs2_clear_slot(osb, slot_num);
        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_inode_lock_full(inode, NULL, 1, flags);
        if (status < 0) {
                if (status != -EAGAIN)
                        mlog_errno(status);
                goto bail;
        }

        ocfs2_inode_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)
{
        unsigned int node_num;
        int status, i;
        u32 gen;
        struct buffer_head *bh = NULL;
        struct ocfs2_dinode *di;

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

        for (i = 0; i < osb->max_slots; i++) {
                /* Read journal inode to get the recovery generation */
                status = ocfs2_read_journal_inode(osb, i, &bh, NULL);
                if (status) {
                        mlog_errno(status);
                        goto bail;
                }
                di = (struct ocfs2_dinode *)bh->b_data;
                gen = ocfs2_get_recovery_generation(di);
                brelse(bh);
                bh = NULL;

                spin_lock(&osb->osb_lock);
                osb->slot_recovery_generations[i] = gen;

                mlog(0, "Slot %u recovery generation is %u\n", i,
                     osb->slot_recovery_generations[i]);

                if (i == osb->slot_num) {
                        spin_unlock(&osb->osb_lock);
                        continue;
                }

                status = ocfs2_slot_to_node_num_locked(osb, i, &node_num);
                if (status == -ENOENT) {
                        spin_unlock(&osb->osb_lock);
                        continue;
                }

                if (__ocfs2_recovery_map_test(osb, node_num)) {
                        spin_unlock(&osb->osb_lock);
                        continue;
                }
                spin_unlock(&osb->osb_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;
                }
        }

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

struct ocfs2_orphan_filldir_priv {
        struct inode            *head;
        struct ocfs2_super      *osb;
};

static int ocfs2_orphan_filldir(void *priv, const char *name, int name_len,
                                loff_t pos, u64 ino, unsigned type)
{
        struct ocfs2_orphan_filldir_priv *p = priv;
        struct inode *iter;

        if (name_len == 1 && !strncmp(".", name, 1))
                return 0;
        if (name_len == 2 && !strncmp("..", name, 2))
                return 0;

        /* Skip bad inodes so that recovery can continue */
        iter = ocfs2_iget(p->osb, ino,
                          OCFS2_FI_FLAG_ORPHAN_RECOVERY, 0);
        if (IS_ERR(iter))
                return 0;

        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 = p->head;
        p->head = iter;

        return 0;
}

static int ocfs2_queue_orphans(struct ocfs2_super *osb,
                               int slot,
                               struct inode **head)
{
        int status;
        struct inode *orphan_dir_inode = NULL;
        struct ocfs2_orphan_filldir_priv priv;
        loff_t pos = 0;

        priv.osb = osb;
        priv.head = *head;

        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_inode_lock(orphan_dir_inode, NULL, 0);
        if (status < 0) {
                mlog_errno(status);
                goto out;
        }

        status = ocfs2_dir_foreach(orphan_dir_inode, &pos, &priv,
                                   ocfs2_orphan_filldir);
        if (status) {
                mlog_errno(status);
                goto out_cluster;
        }

        *head = priv.head;

out_cluster:
        ocfs2_inode_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);
                /* The remote delete code 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;
                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;
}

/* Reads all the journal inodes without taking any cluster locks. Used
 * for hard readonly access to determine whether any journal requires
 * recovery. Also used to refresh the recovery generation numbers after
 * a journal has been recovered by another node.
 */
int ocfs2_check_journals_nolocks(struct ocfs2_super *osb)
{
        int ret = 0;
        unsigned int slot;
        struct buffer_head *di_bh = NULL;
        struct ocfs2_dinode *di;
        int journal_dirty = 0;

        for(slot = 0; slot < osb->max_slots; slot++) {
                ret = ocfs2_read_journal_inode(osb, slot, &di_bh, NULL);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

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

                osb->slot_recovery_generations[slot] =
                                        ocfs2_get_recovery_generation(di);

                if (le32_to_cpu(di->id1.journal1.ij_flags) &
                    OCFS2_JOURNAL_DIRTY_FL)
                        journal_dirty = 1;

                brelse(di_bh);
                di_bh = NULL;
        }

out:
        if (journal_dirty)
                ret = -EROFS;
        return ret;
}