HAMMER 17/many: Refactor IO backend, clean up buffer cache deadlocks.

[dragonfly.git] / sys / vfs / hammer / hammer_inode.c

/*
 * Copyright (c) 2007 The DragonFly Project.  All rights reserved.
 * 
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * $DragonFly: src/sys/vfs/hammer/hammer_inode.c,v 1.18 2008/01/10 07:41:03 dillon Exp $
 */

#include "hammer.h"
#include <sys/buf.h>
#include <sys/buf2.h>

/*
 * The kernel is not actively referencing this vnode but is still holding
 * it cached.
 */
int
hammer_vop_inactive(struct vop_inactive_args *ap)
{
        struct hammer_inode *ip = VTOI(ap->a_vp);

        /*
         * Degenerate case
         */
        if (ip == NULL) {
                vrecycle(ap->a_vp);
                return(0);
        }

        /*
         * If the inode no longer has any references we recover its
         * in-memory resources immediately.
         */
        if (ip->ino_rec.ino_nlinks == 0)
                vrecycle(ap->a_vp);
        return(0);
}

/*
 * Release the vnode association.  This is typically (but not always)
 * the last reference on the inode and will flush the inode to the
 * buffer cache.
 *
 * XXX Currently our sync code only runs through inodes with vnode
 * associations, so we depend on hammer_rel_inode() to sync any inode
 * record data to the block device prior to losing the association.
 * Otherwise transactions that the user expected to be distinct by
 * doing a manual sync may be merged.
 */
int
hammer_vop_reclaim(struct vop_reclaim_args *ap)
{
        struct hammer_inode *ip;
        struct vnode *vp;

        vp = ap->a_vp;

        if ((ip = vp->v_data) != NULL) {
                vp->v_data = NULL;
                ip->vp = NULL;
                hammer_rel_inode(ip, 0);
        }
        return(0);
}

/*
 * Obtain a vnode for the specified inode number.  An exclusively locked
 * vnode is returned.
 */
int
hammer_vfs_vget(struct mount *mp, ino_t ino, struct vnode **vpp)
{
        struct hammer_mount *hmp = (void *)mp->mnt_data;
        struct hammer_inode *ip;
        int error;

        /*
         * Get/allocate the hammer_inode structure.  The structure must be
         * unlocked while we manipulate the related vnode to avoid a
         * deadlock.
         */
        ip = hammer_get_inode(hmp, NULL, ino, hmp->asof, 0, &error);
        if (ip == NULL) {
                *vpp = NULL;
                return(error);
        }
        error = hammer_get_vnode(ip, LK_EXCLUSIVE, vpp);
        hammer_rel_inode(ip, 0);
        return (error);
}

/*
 * Return a locked vnode for the specified inode.  The inode must be
 * referenced but NOT LOCKED on entry and will remain referenced on
 * return.
 */
int
hammer_get_vnode(struct hammer_inode *ip, int lktype, struct vnode **vpp)
{
        struct vnode *vp;
        int error = 0;

        for (;;) {
                if ((vp = ip->vp) == NULL) {
                        error = getnewvnode(VT_HAMMER, ip->hmp->mp, vpp, 0, 0);
                        if (error)
                                break;
                        hammer_lock_ex(&ip->lock);
                        if (ip->vp != NULL) {
                                hammer_unlock(&ip->lock);
                                vp->v_type = VBAD;
                                vx_put(vp);
                                continue;
                        }
                        hammer_ref(&ip->lock);
                        vp = *vpp;
                        ip->vp = vp;
                        vp->v_type = hammer_get_vnode_type(
                                            ip->ino_rec.base.base.obj_type);

                        switch(ip->ino_rec.base.base.obj_type) {
                        case HAMMER_OBJTYPE_CDEV:
                        case HAMMER_OBJTYPE_BDEV:
                                vp->v_ops = &ip->hmp->mp->mnt_vn_spec_ops;
                                addaliasu(vp, ip->ino_data.rmajor,
                                          ip->ino_data.rminor);
                                break;
                        case HAMMER_OBJTYPE_FIFO:
                                vp->v_ops = &ip->hmp->mp->mnt_vn_fifo_ops;
                                break;
                        default:
                                break;
                        }
                        if (ip->obj_id == HAMMER_OBJID_ROOT)
                                vp->v_flag |= VROOT;

                        vp->v_data = (void *)ip;
                        /* vnode locked by getnewvnode() */
                        /* make related vnode dirty if inode dirty? */
                        hammer_unlock(&ip->lock);
                        if (vp->v_type == VREG)
                                vinitvmio(vp, ip->ino_rec.ino_size);
                        break;
                }

                /*
                 * loop if the vget fails (aka races), or if the vp
                 * no longer matches ip->vp.
                 */
                if (vget(vp, LK_EXCLUSIVE) == 0) {
                        if (vp == ip->vp)
                                break;
                        vput(vp);
                }
        }
        *vpp = vp;
        return(error);
}

/*
 * Acquire a HAMMER inode.  The returned inode is not locked.  These functions
 * do not attach or detach the related vnode (use hammer_get_vnode() for
 * that).
 *
 * The flags argument is only applied for newly created inodes, and only
 * certain flags are inherited.
 */
struct hammer_inode *
hammer_get_inode(struct hammer_mount *hmp, struct hammer_node **cache,
                 u_int64_t obj_id, hammer_tid_t asof, int flags, int *errorp)
{
        struct hammer_inode_info iinfo;
        struct hammer_cursor cursor;
        struct hammer_inode *ip;

        /*
         * Determine if we already have an inode cached.  If we do then
         * we are golden.
         */
        iinfo.obj_id = obj_id;
        iinfo.obj_asof = asof;
loop:
        ip = hammer_ino_rb_tree_RB_LOOKUP_INFO(&hmp->rb_inos_root, &iinfo);
        if (ip) {
                hammer_ref(&ip->lock);
                *errorp = 0;
                return(ip);
        }

        ip = kmalloc(sizeof(*ip), M_HAMMER, M_WAITOK|M_ZERO);
        ++hammer_count_inodes;
        ip->obj_id = obj_id;
        ip->obj_asof = iinfo.obj_asof;
        ip->hmp = hmp;
        ip->flags = flags & HAMMER_INODE_RO;
        if (hmp->ronly)
                ip->flags |= HAMMER_INODE_RO;
        RB_INIT(&ip->rec_tree);

        /*
         * Locate the on-disk inode.
         */
        hammer_init_cursor_hmp(&cursor, cache, hmp);
        cursor.key_beg.obj_id = ip->obj_id;
        cursor.key_beg.key = 0;
        cursor.key_beg.create_tid = iinfo.obj_asof;
        cursor.key_beg.delete_tid = 0;
        cursor.key_beg.rec_type = HAMMER_RECTYPE_INODE;
        cursor.key_beg.obj_type = 0;
        cursor.flags = HAMMER_CURSOR_GET_RECORD | HAMMER_CURSOR_GET_DATA;

        *errorp = hammer_btree_lookup(&cursor);

        /*
         * On success the B-Tree lookup will hold the appropriate
         * buffer cache buffers and provide a pointer to the requested
         * information.  Copy the information to the in-memory inode
         * and cache the B-Tree node to improve future operations.
         */
        if (*errorp == 0) {
                ip->ino_rec = cursor.record->inode;
                ip->ino_data = cursor.data->inode;
                hammer_cache_node(cursor.node, &ip->cache[0]);
                if (cache)
                        hammer_cache_node(cursor.node, cache);
        }

        /*
         * On success load the inode's record and data and insert the
         * inode into the B-Tree.  It is possible to race another lookup
         * insertion of the same inode so deal with that condition too.
         *
         * The cursor's locked node interlocks against others creating and
         * destroying ip while we were blocked.
         */
        if (*errorp == 0) {
                hammer_ref(&ip->lock);
                if (RB_INSERT(hammer_ino_rb_tree, &hmp->rb_inos_root, ip)) {
                        hammer_uncache_node(&ip->cache[0]);
                        hammer_uncache_node(&ip->cache[1]);
                        hammer_unref(&ip->lock);
                        --hammer_count_inodes;
                        kfree(ip, M_HAMMER);
                        hammer_done_cursor(&cursor);
                        goto loop;
                }
                ip->flags |= HAMMER_INODE_ONDISK;
        } else {
                --hammer_count_inodes;
                kfree(ip, M_HAMMER);
                ip = NULL;
        }
        hammer_done_cursor(&cursor);
        return (ip);
}

/*
 * Create a new filesystem object, returning the inode in *ipp.  The
 * returned inode will be referenced but not locked.
 *
 * The inode is created in-memory and will be delay-synchronized to the
 * disk.
 */
int
hammer_create_inode(hammer_transaction_t trans, struct vattr *vap,
                    struct ucred *cred, hammer_inode_t dip,
                    struct hammer_inode **ipp)
{
        hammer_mount_t hmp;
        hammer_inode_t ip;
        uid_t xuid;

        hmp = trans->hmp;
        ip = kmalloc(sizeof(*ip), M_HAMMER, M_WAITOK|M_ZERO);
        ++hammer_count_inodes;
        ip->obj_id = hammer_alloc_tid(trans);
        KKASSERT(ip->obj_id != 0);
        ip->obj_asof = hmp->asof;
        ip->hmp = hmp;
        ip->flags = HAMMER_INODE_DDIRTY | HAMMER_INODE_RDIRTY |
                    HAMMER_INODE_ITIMES;
        ip->last_tid = trans->tid;

        RB_INIT(&ip->rec_tree);

        ip->ino_rec.ino_atime = trans->tid;
        ip->ino_rec.ino_mtime = trans->tid;
        ip->ino_rec.ino_size = 0;
        ip->ino_rec.ino_nlinks = 0;
        /* XXX */
        ip->ino_rec.base.rec_id = hammer_alloc_recid(trans);
        KKASSERT(ip->ino_rec.base.rec_id != 0);
        ip->ino_rec.base.base.obj_id = ip->obj_id;
        ip->ino_rec.base.base.key = 0;
        ip->ino_rec.base.base.create_tid = trans->tid;
        ip->ino_rec.base.base.delete_tid = 0;
        ip->ino_rec.base.base.rec_type = HAMMER_RECTYPE_INODE;
        ip->ino_rec.base.base.obj_type = hammer_get_obj_type(vap->va_type);

        ip->ino_data.version = HAMMER_INODE_DATA_VERSION;
        ip->ino_data.mode = vap->va_mode;
        ip->ino_data.ctime = trans->tid;
        ip->ino_data.parent_obj_id = (dip) ? dip->ino_rec.base.base.obj_id : 0;

        switch(ip->ino_rec.base.base.obj_type) {
        case HAMMER_OBJTYPE_CDEV:
        case HAMMER_OBJTYPE_BDEV:
                ip->ino_data.rmajor = vap->va_rmajor;
                ip->ino_data.rminor = vap->va_rminor;
                break;
        default:
                break;
        }

        /*
         * Calculate default uid/gid and overwrite with information from
         * the vap.
         */
        xuid = hammer_to_unix_xid(&dip->ino_data.uid);
        ip->ino_data.gid = dip->ino_data.gid;
        xuid = vop_helper_create_uid(hmp->mp, dip->ino_data.mode, xuid, cred,
                                     &vap->va_mode);
        ip->ino_data.mode = vap->va_mode;

        if (vap->va_vaflags & VA_UID_UUID_VALID)
                ip->ino_data.uid = vap->va_uid_uuid;
        else if (vap->va_uid != (uid_t)VNOVAL)
                hammer_guid_to_uuid(&ip->ino_data.uid, xuid);
        if (vap->va_vaflags & VA_GID_UUID_VALID)
                ip->ino_data.gid = vap->va_gid_uuid;
        else if (vap->va_gid != (gid_t)VNOVAL)
                hammer_guid_to_uuid(&ip->ino_data.gid, vap->va_gid);

        hammer_ref(&ip->lock);
        if (RB_INSERT(hammer_ino_rb_tree, &hmp->rb_inos_root, ip)) {
                hammer_unref(&ip->lock);
                panic("hammer_create_inode: duplicate obj_id %llx", ip->obj_id);
        }
        *ipp = ip;
        return(0);
}

/*
 * Called by hammer_sync_inode().
 */
static int
hammer_update_inode(hammer_inode_t ip)
{
        struct hammer_cursor cursor;
        struct hammer_cursor *spike = NULL;
        hammer_record_t record;
        int error;
        hammer_tid_t last_tid;

        /*
         * Locate the record on-disk and mark it as deleted.  Both the B-Tree
         * node and the record must be marked deleted.  The record may or
         * may not be physically deleted, depending on the retention policy.
         *
         * If the inode has already been deleted on-disk we have nothing
         * to do.
         *
         * XXX Update the inode record and data in-place if the retention
         * policy allows it.
         */
        last_tid = ip->last_tid;
retry:
        error = 0;

        if ((ip->flags & (HAMMER_INODE_ONDISK|HAMMER_INODE_DELONDISK)) ==
            HAMMER_INODE_ONDISK) {
                hammer_init_cursor_hmp(&cursor, &ip->cache[0], ip->hmp);
                cursor.key_beg.obj_id = ip->obj_id;
                cursor.key_beg.key = 0;
                cursor.key_beg.create_tid = ip->obj_asof;
                cursor.key_beg.delete_tid = 0;
                cursor.key_beg.rec_type = HAMMER_RECTYPE_INODE;
                cursor.key_beg.obj_type = 0;
                cursor.flags = HAMMER_CURSOR_GET_RECORD;

                error = hammer_btree_lookup(&cursor);

                if (error == 0) {
                        error = hammer_ip_delete_record(&cursor, last_tid);
                        if (error == 0)
                                ip->flags |= HAMMER_INODE_DELONDISK;
                }
                hammer_cache_node(cursor.node, &ip->cache[0]);
                hammer_done_cursor(&cursor);
        }

        /*
         * Write out a new record if the in-memory inode is not marked
         * as having been deleted.  Update our inode statistics if this
         * is the first application of the inode on-disk.
         *
         * If the inode has been deleted permanently, HAMMER_INODE_DELONDISK
         * will remain set and prevent further updates.
         */
        if (error == 0 && (ip->flags & HAMMER_INODE_DELETED) == 0) { 
                record = hammer_alloc_mem_record(ip);
                record->rec.inode = ip->ino_rec;
                record->rec.inode.base.base.create_tid = last_tid;
                record->rec.inode.base.data_len = sizeof(ip->ino_data);
                record->data = (void *)&ip->ino_data;
                error = hammer_ip_sync_record(record, &spike);
                record->flags |= HAMMER_RECF_DELETED;
                hammer_rel_mem_record(record);
                if (error == ENOSPC) {
                        error = hammer_spike(&spike);
                        if (error == 0)
                                goto retry;
                }
                KKASSERT(spike == NULL);
                if (error == 0) {
                        ip->flags &= ~(HAMMER_INODE_RDIRTY |
                                       HAMMER_INODE_DDIRTY |
                                       HAMMER_INODE_DELONDISK |
                                       HAMMER_INODE_ITIMES);
                        if ((ip->flags & HAMMER_INODE_ONDISK) == 0) {
                                hammer_modify_volume(ip->hmp->rootvol);
                                ++ip->hmp->rootvol->ondisk->vol0_stat_inodes;
                                ip->flags |= HAMMER_INODE_ONDISK;
                        }
                }
        }
        return(error);
}

/*
 * Update only the itimes fields.  This is done no-historically.  The
 * record is updated in-place on the disk.
 */
static int
hammer_update_itimes(hammer_inode_t ip)
{
        struct hammer_cursor cursor;
        struct hammer_inode_record *rec;
        int error;

        error = 0;
        if ((ip->flags & (HAMMER_INODE_ONDISK|HAMMER_INODE_DELONDISK)) ==
            HAMMER_INODE_ONDISK) {
                hammer_init_cursor_hmp(&cursor, &ip->cache[0], ip->hmp);
                cursor.key_beg.obj_id = ip->obj_id;
                cursor.key_beg.key = 0;
                cursor.key_beg.create_tid = ip->obj_asof;
                cursor.key_beg.delete_tid = 0;
                cursor.key_beg.rec_type = HAMMER_RECTYPE_INODE;
                cursor.key_beg.obj_type = 0;
                cursor.flags = HAMMER_CURSOR_GET_RECORD;

                error = hammer_btree_lookup(&cursor);

                if (error == 0) {
                        rec = &cursor.record->inode;
                        hammer_modify_buffer(cursor.record_buffer);
                        rec->ino_atime = ip->ino_rec.ino_atime;
                        rec->ino_mtime = ip->ino_rec.ino_mtime;
                        ip->flags &= ~HAMMER_INODE_ITIMES;
                        /* XXX recalculate crc */
                }
                hammer_cache_node(cursor.node, &ip->cache[0]);
                hammer_done_cursor(&cursor);
        }
        return(error);
}

/*
 * Release a reference on an inode.  If asked to flush the last release
 * will flush the inode.
 */
void
hammer_rel_inode(struct hammer_inode *ip, int flush)
{
        hammer_unref(&ip->lock);
        if (flush)
                ip->flags |= HAMMER_INODE_FLUSH;
        if (ip->lock.refs == 0) {
                if (ip->flags & HAMMER_INODE_FLUSH)
                        hammer_unload_inode(ip, (void *)MNT_WAIT);
                else
                        hammer_unload_inode(ip, (void *)MNT_NOWAIT);
        }
}

/*
 * Unload and destroy the specified inode.
 *
 * (called via RB_SCAN)
 */
int
hammer_unload_inode(struct hammer_inode *ip, void *data)
{
        int error;

        KASSERT(ip->lock.refs == 0,
                ("hammer_unload_inode: %d refs\n", ip->lock.refs));
        KKASSERT(ip->vp == NULL);
        hammer_ref(&ip->lock);

        error = hammer_sync_inode(ip, (int)data, 1);
        if (error)
                kprintf("hammer_sync_inode failed error %d\n", error);
        if (ip->lock.refs == 1) {
                KKASSERT(RB_EMPTY(&ip->rec_tree));
                RB_REMOVE(hammer_ino_rb_tree, &ip->hmp->rb_inos_root, ip);

                hammer_uncache_node(&ip->cache[0]);
                hammer_uncache_node(&ip->cache[1]);
                --hammer_count_inodes;
                kfree(ip, M_HAMMER);
        } else {
                hammer_unref(&ip->lock);
        }
        return(0);
}

/*
 * A transaction has modified an inode, requiring updates as specified by
 * the passed flags.
 *
 * HAMMER_INODE_RDIRTY: Inode record has been updated
 * HAMMER_INODE_DDIRTY: Inode data has been updated
 * HAMMER_INODE_DELETED: Inode record/data must be deleted
 * HAMMER_INODE_ITIMES: mtime/atime has been updated
 *
 * last_tid is the TID to use to generate the correct TID when the inode
 * is synced to disk.
 */
void
hammer_modify_inode(struct hammer_transaction *trans,
                    struct hammer_inode *ip, int flags)
{
        KKASSERT ((ip->flags & HAMMER_INODE_RO) == 0 ||
                  (HAMMER_INODE_RDIRTY|HAMMER_INODE_DDIRTY|
                   HAMMER_INODE_DELETED|HAMMER_INODE_ITIMES) == 0);

        if (flags &
            (HAMMER_INODE_RDIRTY|HAMMER_INODE_DDIRTY|HAMMER_INODE_DELETED)) {
                if (hammer_debug_tid) {
                        kprintf("hammer_modify_inode: %016llx (%08x)\n", 
                                trans->tid, (int)(trans->tid / 1000000000LL));
                }
                ip->last_tid = trans->tid;
        }
        ip->flags |= flags;
}

/*
 * Sync any dirty buffers and records associated with an inode.  The
 * inode's last_tid field is used as the transaction id for the sync,
 * overriding any intermediate TIDs that were used for records.  Note
 * that the dirty buffer cache buffers do not have any knowledge of
 * the transaction id they were modified under.
 *
 * If we can't sync due to a cluster becoming full the spike structure
 * will be filled in and ENOSPC returned.  We must return -ENOSPC to
 * terminate the RB_SCAN.
 */
static int
hammer_sync_inode_callback(hammer_record_t rec, void *data)
{
        struct hammer_cursor **spike = data;
        int error;

        hammer_ref(&rec->lock);
        error = hammer_ip_sync_record(rec, spike);
        hammer_rel_mem_record(rec);

        if (error) {
                error = -error;
                if (error != -ENOSPC) {
                        kprintf("hammer_sync_inode_callback: sync failed rec "
                                "%p, error %d\n", rec, error);
                }
        }
        return(error);
}

/*
 * XXX error handling
 */
int
hammer_sync_inode(hammer_inode_t ip, int waitfor, int handle_delete)
{
        struct hammer_transaction trans;
        struct hammer_cursor *spike = NULL;
        int error;

        if ((ip->flags & HAMMER_INODE_MODMASK) == 0) {
                return(0);
        }

        hammer_lock_ex(&ip->lock);

        /*
         * Use the transaction id of the last operation to sync.
         */
        if (ip->last_tid)
                hammer_start_transaction_tid(&trans, ip->hmp, ip->last_tid);
        else
                hammer_start_transaction(&trans, ip->hmp);

        /*
         * If the inode has been deleted (nlinks == 0), and the OS no longer
         * has any references to it (handle_delete != 0), clean up in-memory
         * data.
         *
         * NOTE: We do not set the RDIRTY flag when updating the delete_tid,
         * setting HAMMER_INODE_DELETED takes care of it.
         *
         * NOTE: Because we may sync records within this new transaction,
         * force the inode update later on to use our transaction id or
         * the delete_tid of the inode may be less then the create_tid of
         * the inode update.  XXX shouldn't happen but don't take the chance.
         *
         * NOTE: The call to hammer_ip_delete_range() cannot return ENOSPC
         * so we can pass a NULL spike structure, because no partial data
         * deletion can occur (yet).
         */
        if (ip->ino_rec.ino_nlinks == 0 && handle_delete && 
            (ip->flags & HAMMER_INODE_GONE) == 0) {
                ip->flags |= HAMMER_INODE_GONE;
                if (ip->vp)
                        vtruncbuf(ip->vp, 0, HAMMER_BUFSIZE);
                error = hammer_ip_delete_range_all(&trans, ip);
                KKASSERT(RB_EMPTY(&ip->rec_tree));
                ip->ino_rec.base.base.delete_tid = trans.tid;
                hammer_modify_inode(&trans, ip, HAMMER_INODE_DELETED);
                hammer_modify_volume(ip->hmp->rootvol);
                --ip->hmp->rootvol->ondisk->vol0_stat_inodes;
        }

        /*
         * Sync the buffer cache
         */
        if (ip->vp != NULL)
                error = vfsync(ip->vp, waitfor, 1, NULL, NULL);
        else
                error = 0;

        /*
         * Now sync related records
         */
        for (;;) {
                error = RB_SCAN(hammer_rec_rb_tree, &ip->rec_tree, NULL,
                                hammer_sync_inode_callback, &spike);
                KKASSERT(error <= 0);
                if (error < 0)
                        error = -error;
                if (error == ENOSPC) {
                        error = hammer_spike(&spike);
                        if (error == 0)
                                continue;
                }
                break;
        }
        if (RB_EMPTY(&ip->rec_tree))
                ip->flags &= ~HAMMER_INODE_XDIRTY;

        /*
         * Now update the inode's on-disk inode-data and/or on-disk record.
         */
        switch(ip->flags & (HAMMER_INODE_DELETED|HAMMER_INODE_ONDISK)) {
        case HAMMER_INODE_DELETED|HAMMER_INODE_ONDISK:
                /*
                 * If deleted and on-disk, don't set any additional flags.
                 * the delete flag takes care of things.
                 */
                break;
        case HAMMER_INODE_DELETED:
                /*
                 * Take care of the case where a deleted inode was never
                 * flushed to the disk in the first place.
                 */
                ip->flags &= ~(HAMMER_INODE_RDIRTY|HAMMER_INODE_DDIRTY|
                               HAMMER_INODE_XDIRTY|HAMMER_INODE_ITIMES);
                while (RB_ROOT(&ip->rec_tree)) {
                        hammer_record_t rec = RB_ROOT(&ip->rec_tree);
                        hammer_ref(&rec->lock);
                        rec->flags |= HAMMER_RECF_DELETED;
                        hammer_rel_mem_record(rec);
                }
                break;
        case HAMMER_INODE_ONDISK:
                /*
                 * If already on-disk, do not set any additional flags.
                 */
                break;
        default:
                /*
                 * If not on-disk and not deleted, set both dirty flags
                 * to force an initial record to be written.
                 */
                ip->flags |= HAMMER_INODE_RDIRTY | HAMMER_INODE_DDIRTY;
                break;
        }

        /*
         * If RDIRTY or DDIRTY is set, write out a new record.  If the inode
         * is already on-disk the old record is marked as deleted.
         *
         * If DELETED is set hammer_update_inode() will delete the existing
         * record without writing out a new one.
         *
         * If *ONLY* the ITIMES flag is set we can update the record in-place.
         */
        if ((ip->flags & (HAMMER_INODE_RDIRTY | HAMMER_INODE_DDIRTY |
                         HAMMER_INODE_ITIMES | HAMMER_INODE_DELETED)) ==
            HAMMER_INODE_ITIMES) {
                error = hammer_update_itimes(ip);
        } else
        if (ip->flags & (HAMMER_INODE_RDIRTY | HAMMER_INODE_DDIRTY |
                         HAMMER_INODE_ITIMES | HAMMER_INODE_DELETED)) {
                error = hammer_update_inode(ip);
        }
        hammer_commit_transaction(&trans);
        hammer_unlock(&ip->lock);
        return(error);
}

/*
 * Access the filesystem buffer containing the cluster-relative byte
 * offset, validate the buffer type, load *bufferp and return a
 * pointer to the requested data.  The buffer is reference and locked on
 * return.
 *
 * If buf_type is 0 the buffer is assumed to be a pure-data buffer and
 * no type or crc check is performed.
 *
 * If *bufferp is not NULL on entry it is assumed to contain a locked
 * and referenced buffer which will then be replaced.
 *
 * If the caller is holding another unrelated buffer locked it must be
 * passed in reorderbuf so we can properly order buffer locks.
 *
 * XXX add a flag for the buffer type and check the CRC here XXX
 */
void *
hammer_bread(hammer_cluster_t cluster, int32_t cloff,
             u_int64_t buf_type, int *errorp,
             struct hammer_buffer **bufferp)
{
        hammer_buffer_t buffer;
        int32_t buf_no;
        int32_t buf_off;

        /*
         * Load the correct filesystem buffer, replacing *bufferp.
         */
        buf_no = cloff / HAMMER_BUFSIZE;
        buffer = *bufferp;
        if (buffer == NULL || buffer->cluster != cluster ||
            buffer->buf_no != buf_no) {
                if (buffer) {
                        /*hammer_unlock(&buffer->io.lock);*/
                        hammer_rel_buffer(buffer, 0);
                }
                buffer = hammer_get_buffer(cluster, buf_no, 0, errorp);
                *bufferp = buffer;
                if (buffer == NULL)
                        return(NULL);
                /*hammer_lock_ex(&buffer->io.lock);*/
        }

        /*
         * Validate the buffer type
         */
        buf_off = cloff & HAMMER_BUFMASK;
        if (buf_type) {
                if (buf_type != buffer->ondisk->head.buf_type) {
                        kprintf("BUFFER HEAD TYPE MISMATCH %llx %llx\n",
                                buf_type, buffer->ondisk->head.buf_type);
                        *errorp = EIO;
                        return(NULL);
                }
                if (buf_off < sizeof(buffer->ondisk->head)) {
                        kprintf("BUFFER OFFSET TOO LOW %d\n", buf_off);
                        *errorp = EIO;
                        return(NULL);
                }
        }

        /*
         * Return a pointer to the buffer data.
         */
        *errorp = 0;
        return((char *)buffer->ondisk + buf_off);
}