HAMMER 38F/Many: Undo/Synchronization and crash recovery, stabilization pass

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

/*
 * Copyright (c) 2007-2008 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 1.42 2008/04/27 21:07:15 dillon Exp $
 */

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

static int hammer_unload_inode(struct hammer_inode *ip);
static void hammer_flush_inode_copysync(hammer_inode_t ip);
static int hammer_mark_record_callback(hammer_record_t rec, void *data);

/*
 * The kernel is not actively referencing this vnode but is still holding
 * it cached.
 *
 * This is called from the frontend.
 */
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.
         *
         * NOTE: called from frontend, use ino_rec instead of sync_ino_rec.
         */
        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;

                /*
                 * Don't let too many dependancies build up on unreferenced
                 * inodes or we could run ourselves out of memory.
                 */
                if (TAILQ_FIRST(&ip->depend_list)) {
                        ip->hmp->reclaim_count += ip->depend_count;
                        if (ip->hmp->reclaim_count > 256) {
                                ip->hmp->reclaim_count = 0;
                                hammer_flusher_async(ip->hmp);
                        }
                }
                hammer_rel_inode(ip, 1);
        }
        return(0);
}

/*
 * Return a locked vnode for the specified inode.  The inode must be
 * referenced but NOT LOCKED on entry and will remain referenced on
 * return.
 *
 * Called from the frontend.
 */
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;
                        }

                        /*
                         * Only mark as the root vnode if the ip is not
                         * historical, otherwise the VFS cache will get
                         * confused.  The other half of the special handling
                         * is in hammer_vop_nlookupdotdot().
                         */
                        if (ip->obj_id == HAMMER_OBJID_ROOT &&
                            ip->obj_asof == ip->hmp->asof) {
                                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.
 *
 * Called from the frontend.
 */
struct hammer_inode *
hammer_get_inode(hammer_transaction_t trans, struct hammer_node **cache,
                 u_int64_t obj_id, hammer_tid_t asof, int flags, int *errorp)
{
        hammer_mount_t hmp = trans->hmp;
        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;
        ip->trunc_off = 0x7FFFFFFFFFFFFFFFLL;
        RB_INIT(&ip->rec_tree);
        TAILQ_INIT(&ip->bio_list);
        TAILQ_INIT(&ip->bio_alt_list);
        TAILQ_INIT(&ip->depend_list);

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

        *errorp = hammer_btree_lookup(&cursor);
        if (*errorp == EDEADLK) {
                hammer_done_cursor(&cursor);
                goto retry;
        }

        /*
         * 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]);
                        KKASSERT(ip->lock.refs == 1);
                        --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 and also marked HAMMER_INODE_NEW,
 * preventing it from being synchronized too early.  The caller must
 * call hammer_finalize_inode() to make it available for media sync.
 *
 * The inode is created in-memory.
 */
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->flush_state = HAMMER_FST_IDLE;
        ip->flags = HAMMER_INODE_DDIRTY | HAMMER_INODE_RDIRTY |
                    HAMMER_INODE_ITIMES;
        ip->flags |= HAMMER_INODE_NEW;

        ip->trunc_off = 0x7FFFFFFFFFFFFFFFLL;
        RB_INIT(&ip->rec_tree);
        TAILQ_INIT(&ip->bio_list);
        TAILQ_INIT(&ip->bio_alt_list);
        TAILQ_INIT(&ip->depend_list);

        ip->ino_rec.ino_atime = trans->time;
        ip->ino_rec.ino_mtime = trans->time;
        ip->ino_rec.ino_size = 0;
        ip->ino_rec.ino_nlinks = 0;
        /* XXX */
        ip->ino_rec.base.base.btype = HAMMER_BTREE_TYPE_RECORD;
        ip->ino_rec.base.base.obj_id = ip->obj_id;
        ip->ino_rec.base.base.key = 0;
        ip->ino_rec.base.base.create_tid = 0;
        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->time;
        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);
}

/*
 * Finalize a newly created inode, allowing it to be synchronized to the
 * media.  If an error occured make sure the inode has been cleaned up and
 * will not be synchronized to the media.
 */
void
hammer_finalize_inode(hammer_transaction_t trans, hammer_inode_t ip, int error)
{
        if (error) {
                ip->flags &= ~HAMMER_INODE_MODMASK;

                KASSERT(ip->lock.refs == 1,
                        ("hammer_unload_inode: %d refs\n", ip->lock.refs));
                KKASSERT(ip->vp == NULL);
                KKASSERT(ip->flush_state == HAMMER_FST_IDLE);
                KKASSERT(ip->cursor_ip_refs == 0);
                KKASSERT((ip->flags & HAMMER_INODE_MODMASK) == 0);

                KKASSERT(RB_EMPTY(&ip->rec_tree));
                KKASSERT(TAILQ_EMPTY(&ip->bio_list));
                KKASSERT(TAILQ_EMPTY(&ip->bio_alt_list));
        }
        ip->flags &= ~HAMMER_INODE_NEW;
}

/*
 * Called by hammer_sync_inode().
 */
static int
hammer_update_inode(hammer_transaction_t trans, hammer_inode_t ip)
{
        struct hammer_cursor cursor;
        hammer_record_t record;
        int error;

        /*
         * 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.
         */
retry:
        error = 0;

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

                error = hammer_btree_lookup(&cursor);
                if (error) {
                        kprintf("error %d\n", error);
                        Debugger("hammer_update_inode");
                }


                if (error == 0) {
                        error = hammer_ip_delete_record(&cursor, trans->tid);
                        if (error && error != EDEADLK) {
                                kprintf("error %d\n", error);
                                Debugger("hammer_update_inode2");
                        }
                        if (error == 0)
                                ip->flags |= HAMMER_INODE_DELONDISK;
                        hammer_cache_node(cursor.node, &ip->cache[0]);
                }
                hammer_done_cursor(&cursor);
                if (error == EDEADLK)
                        goto retry;
        }

        /*
         * 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->state = HAMMER_FST_FLUSH;
                record->rec.inode = ip->sync_ino_rec;
                record->rec.inode.base.base.create_tid = trans->tid;
                record->rec.inode.base.data_len = sizeof(ip->sync_ino_data);
                record->data = (void *)&ip->sync_ino_data;
                record->flags |= HAMMER_RECF_INTERLOCK_BE;
                error = hammer_ip_sync_record(trans, record);
                if (error) {
                        kprintf("error %d\n", error);
                        Debugger("hammer_update_inode3");
                }

                /*
                 * The record isn't managed by the inode's record tree,
                 * destroy it whether we succeed or fail.
                 */
                record->flags &= ~HAMMER_RECF_INTERLOCK_BE;
                record->flags |= HAMMER_RECF_DELETED_FE;
                record->state = HAMMER_FST_IDLE;
                KKASSERT(TAILQ_FIRST(&record->depend_list) == NULL);
                hammer_rel_mem_record(record);

                if (error == 0) {
                        ip->sync_flags &= ~(HAMMER_INODE_RDIRTY |
                                            HAMMER_INODE_DDIRTY |
                                            HAMMER_INODE_ITIMES);
                        ip->flags &= ~HAMMER_INODE_DELONDISK;
                        if ((ip->flags & HAMMER_INODE_ONDISK) == 0) {
                                hammer_modify_volume(trans, trans->rootvol,
                                                     NULL, 0);
                                ++ip->hmp->rootvol->ondisk->vol0_stat_inodes;
                                hammer_modify_volume_done(trans->rootvol);
                                ip->flags |= HAMMER_INODE_ONDISK;
                        }
                }
        }
        if (error == 0 && (ip->flags & HAMMER_INODE_DELETED)) { 
                /*
                 * Clean out any left-over flags if the inode has been
                 * destroyed.
                 */
                ip->sync_flags &= ~(HAMMER_INODE_RDIRTY |
                                    HAMMER_INODE_DDIRTY |
                                    HAMMER_INODE_ITIMES);
        }
        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_transaction_t trans, hammer_inode_t ip)
{
        struct hammer_cursor cursor;
        struct hammer_inode_record *rec;
        int error;

retry:
        error = 0;
        if ((ip->flags & (HAMMER_INODE_ONDISK|HAMMER_INODE_DELONDISK)) ==
            HAMMER_INODE_ONDISK) {
                hammer_init_cursor(trans, &cursor, &ip->cache[0]);
                cursor.key_beg.obj_id = ip->obj_id;
                cursor.key_beg.key = 0;
                cursor.key_beg.create_tid = 0;
                cursor.key_beg.delete_tid = 0;
                cursor.key_beg.rec_type = HAMMER_RECTYPE_INODE;
                cursor.key_beg.obj_type = 0;
                cursor.asof = ip->obj_asof;
                cursor.flags |= HAMMER_CURSOR_GET_RECORD | HAMMER_CURSOR_ASOF;
                cursor.flags |= HAMMER_CURSOR_BACKEND;

                error = hammer_btree_lookup(&cursor);
                if (error) {
                        kprintf("error %d\n", error);
                        Debugger("hammer_update_itimes1");
                }
                if (error == 0) {
                        /*
                         * Do not generate UNDO records for atime/mtime
                         * updates.
                         */
                        rec = &cursor.record->inode;
                        hammer_modify_buffer(cursor.trans, cursor.record_buffer,
                                             NULL, 0);
                        rec->ino_atime = ip->sync_ino_rec.ino_atime;
                        rec->ino_mtime = ip->sync_ino_rec.ino_mtime;
                        hammer_modify_buffer_done(cursor.record_buffer);
                        ip->sync_flags &= ~HAMMER_INODE_ITIMES;
                        /* XXX recalculate crc */
                        hammer_cache_node(cursor.node, &ip->cache[0]);
                }
                hammer_done_cursor(&cursor);
                if (error == EDEADLK)
                        goto retry;
        }
        return(error);
}

/*
 * Release a reference on an inode.  If asked to flush the last release
 * will flush the inode.
 *
 * On the last reference we queue the inode to the flusher for its final
 * disposition.
 */
void
hammer_rel_inode(struct hammer_inode *ip, int flush)
{
        /*
         * Handle disposition when dropping the last ref.
         */
        while (ip->lock.refs == 1) {
                if ((ip->flags & HAMMER_INODE_MODMASK) == 0) {
                        hammer_unload_inode(ip);
                        return;
                }

                /*
                 * Hand the inode over to the flusher, which will
                 * add another ref to it.
                 */
                if (++ip->hmp->reclaim_count > 256) {
                        ip->hmp->reclaim_count = 0;
                        hammer_flush_inode(ip, HAMMER_FLUSH_FORCE |
                                                HAMMER_FLUSH_SIGNAL);
                } else {
                        hammer_flush_inode(ip, HAMMER_FLUSH_FORCE);
                }
                /* retry */
        }

        /*
         * The inode still has multiple refs, drop one ref.  If a flush was
         * requested make sure the flusher sees it.  New inodes which have
         * not been finalized cannot be flushed.
         */
        if (flush && ip->flush_state == HAMMER_FST_IDLE && 
            (ip->flags & HAMMER_INODE_NEW) == 0) {
                hammer_flush_inode(ip, HAMMER_FLUSH_RELEASE);
        } else {
                hammer_unref(&ip->lock);
        }
}

/*
 * Unload and destroy the specified inode.  Must be called with one remaining
 * reference.  The reference is disposed of.
 *
 * This can only be called in the context of the flusher.
 */
static int
hammer_unload_inode(struct hammer_inode *ip)
{
        KASSERT(ip->lock.refs == 1,
                ("hammer_unload_inode: %d refs\n", ip->lock.refs));
        KKASSERT(ip->vp == NULL);
        KKASSERT(ip->flush_state == HAMMER_FST_IDLE);
        KKASSERT(ip->cursor_ip_refs == 0);
        KKASSERT((ip->flags & HAMMER_INODE_MODMASK) == 0);

        KKASSERT(RB_EMPTY(&ip->rec_tree));
        KKASSERT(TAILQ_EMPTY(&ip->bio_list));
        KKASSERT(TAILQ_EMPTY(&ip->bio_alt_list));

        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);

        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_XDIRTY: Dirty frontend buffer cache buffer strategized
 * HAMMER_INODE_DELETED: Inode record/data must be deleted
 * HAMMER_INODE_ITIMES: mtime/atime has been updated
 */
void
hammer_modify_inode(hammer_transaction_t trans, hammer_inode_t ip, int flags)
{
        KKASSERT ((ip->flags & HAMMER_INODE_RO) == 0 ||
                  (flags & (HAMMER_INODE_RDIRTY|HAMMER_INODE_DDIRTY|
                   HAMMER_INODE_XDIRTY|
                   HAMMER_INODE_DELETED|HAMMER_INODE_ITIMES)) == 0);

        ip->flags |= flags;
}

/*
 * Flush an inode.  If the inode is already being flushed wait for
 * it to complete, then flush it again.  The interlock is against
 * front-end transactions, the backend flusher does not hold the lock.
 *
 * The flusher must distinguish between the records that are part of the
 * flush and any new records created in parallel with the flush.  The
 * inode data and truncation fields are also copied.  BIOs are a bit more
 * troublesome because some dirty buffers may not have been queued yet.
 */
void
hammer_flush_inode(hammer_inode_t ip, int flags)
{
        KKASSERT((ip->flags & HAMMER_INODE_NEW) == 0);
        if (ip->flush_state != HAMMER_FST_IDLE &&
            (ip->flags & HAMMER_INODE_MODMASK)) {
                ip->flags |= HAMMER_INODE_REFLUSH;
                if (flags & HAMMER_FLUSH_RELEASE) {
                        hammer_unref(&ip->lock);
                        KKASSERT(ip->lock.refs > 0);
                }
                return;
        }
        if (ip->flush_state == HAMMER_FST_IDLE) {
                if ((ip->flags & HAMMER_INODE_MODMASK) ||
                    (flags & HAMMER_FLUSH_FORCE)) {
                        /*
                         * Add a reference to represent the inode being queued
                         * to the flusher.  If the caller wants us to 
                         * release a reference the two cancel each other out.
                         */
                        if ((flags & HAMMER_FLUSH_RELEASE) == 0)
                                hammer_ref(&ip->lock);

                        hammer_flush_inode_copysync(ip);
                        /*
                         * Move the inode to the flush list and add a ref to
                         * it representing it on the list.
                         */
                        TAILQ_INSERT_TAIL(&ip->hmp->flush_list, ip, flush_entry);
                        if (flags & HAMMER_FLUSH_SIGNAL)
                                hammer_flusher_async(ip->hmp);
                }
        }
}

/*
 * Helper routine to copy the frontend synchronization state to the backend.
 * This routine may be called by either the frontend or the backend.
 */
static void
hammer_flush_inode_copysync(hammer_inode_t ip)
{
        int error;
        int count;

        /*
         * Prevent anyone else from trying to do the same thing.
         */
        ip->flush_state = HAMMER_FST_SETUP;

        /*
         * Sync the buffer cache.  This will queue the BIOs.  If called
         * from the context of the flusher the BIO's are thrown into bio_list
         * regardless of ip->flush_state.
         */
        if (ip->vp != NULL)
                error = vfsync(ip->vp, MNT_NOWAIT, 1, NULL, NULL);
        else
                error = 0;

        /*
         * This freezes strategy writes, any further BIOs will be
         * queued to alt_bio (unless we are 
         */
        ip->flush_state = HAMMER_FST_FLUSH;

        /*
         * Snapshot the state of the inode for the backend flusher.
         *
         * The truncation must be retained in the frontend until after
         * we've actually performed the record deletion.
         */
        ip->sync_flags = (ip->flags & HAMMER_INODE_MODMASK);
        ip->sync_trunc_off = ip->trunc_off;
        ip->sync_ino_rec = ip->ino_rec;
        ip->sync_ino_data = ip->ino_data;
        ip->flags &= ~HAMMER_INODE_MODMASK |
                     HAMMER_INODE_TRUNCATED | HAMMER_INODE_BUFS;

        /*
         * Fix up the dirty buffer status.
         */
        if (ip->vp == NULL || RB_ROOT(&ip->vp->v_rbdirty_tree) == NULL)
                ip->flags &= ~HAMMER_INODE_BUFS;
        if (TAILQ_FIRST(&ip->bio_list))
                ip->sync_flags |= HAMMER_INODE_BUFS;
        else
                ip->sync_flags &= ~HAMMER_INODE_BUFS;

        /*
         * Set the state for the inode's in-memory records.  If some records
         * could not be marked for backend flush (i.e. deleted records),
         * re-set the XDIRTY flag.
         */
        count = RB_SCAN(hammer_rec_rb_tree, &ip->rec_tree, NULL,
                        hammer_mark_record_callback, NULL);
        if (count)
                ip->flags |= HAMMER_INODE_XDIRTY;
}

/*
 * Mark records for backend flush, accumulate a count of the number of
 * records which could not be marked.  Records marked for deletion
 * by the frontend never make it to the media.  It is possible for
 * a record queued to the backend to wind up with FE set after the
 * fact, as long as BE has not yet been set.  The backend deals with
 * this race by syncing the record as if FE had not been set, and
 * then converting the record to a delete-on-disk record.
 */
static int
hammer_mark_record_callback(hammer_record_t rec, void *data)
{
        if (rec->state == HAMMER_FST_FLUSH) {
                return(0);
        } else if ((rec->flags & HAMMER_RECF_DELETED_FE) == 0) {
                rec->state = HAMMER_FST_FLUSH;
                hammer_ref(&rec->lock);
                return(0);
        } else {
                return(1);
        }
}



/*
 * Wait for a previously queued flush to complete
 */
void
hammer_wait_inode(hammer_inode_t ip)
{
        while (ip->flush_state == HAMMER_FST_FLUSH) {
                ip->flags |= HAMMER_INODE_FLUSHW;
                tsleep(&ip->flags, 0, "hmrwin", 0);
        }
}

/*
 * Called by the backend code when a flush has been completed.
 * The inode has already been removed from the flush list.
 *
 * A pipelined flush can occur, in which case we must re-enter the
 * inode on the list and re-copy its fields.
 */
void
hammer_flush_inode_done(hammer_inode_t ip)
{
        struct bio *bio;

        KKASSERT(ip->flush_state == HAMMER_FST_FLUSH);

        if (ip->sync_flags)
                kprintf("ip %p leftover sync_flags %08x\n", ip, ip->sync_flags);
        ip->flags |= ip->sync_flags;
        ip->flush_state = HAMMER_FST_IDLE;

        /*
         * Reflush any BIOs that wound up in the alt list.  Our inode will
         * also wind up at the end of the flusher's list.
         */
        while ((bio = TAILQ_FIRST(&ip->bio_alt_list)) != NULL) {
                TAILQ_REMOVE(&ip->bio_alt_list, bio, bio_act);
                TAILQ_INSERT_TAIL(&ip->bio_list, bio, bio_act);
                ip->flags |= HAMMER_INODE_XDIRTY;
                ip->flags |= HAMMER_INODE_REFLUSH;
                kprintf("rebio %p ip %p @%016llx,%d\n", bio, ip, bio->bio_offset, bio->bio_buf->b_bufsize);
        }

        /*
         * If the frontend made more changes and requested another flush,
         * do it. 
         */
        if (ip->flags & HAMMER_INODE_REFLUSH) {
                ip->flags &= ~HAMMER_INODE_REFLUSH;
                hammer_flush_inode(ip, 0);
        } else {
                if (ip->flags & HAMMER_INODE_FLUSHW) {
                        ip->flags &= ~HAMMER_INODE_FLUSHW;
                        wakeup(&ip->flags);
                }
        }
        hammer_rel_inode(ip, 0);
}

/*
 * Called from hammer_sync_inode() to synchronize in-memory records
 * to the media.
 */
static int
hammer_sync_record_callback(hammer_record_t record, void *data)
{
        hammer_transaction_t trans = data;
        int error;

        /*
         * Skip records that do not belong to the current flush.  Records
         * belonging to the flush will have been referenced for us.
         */
        if (record->state != HAMMER_FST_FLUSH)
                return(0);

        /*
         * Interlock the record using the BE flag.  Once BE is set the
         * frontend cannot change the state of FE.
         *
         * NOTE: If FE is set prior to us setting BE we still sync the
         * record out, but the flush completion code converts it to 
         * a delete-on-disk record instead of destroying it.
         */
        hammer_lock_ex(&record->lock);
        if (record->flags & HAMMER_RECF_INTERLOCK_BE) {
                hammer_unlock(&record->lock);
                return(0);
        }
        record->flags |= HAMMER_RECF_INTERLOCK_BE;

        /*
         * If DELETED_FE is set we may have already sent dependant pieces
         * to the disk and we must flush the record as if it hadn't been
         * deleted.  This creates a bit of a mess because we have to
         * have ip_sync_record convert the record to DELETE_ONDISK before
         * it inserts the B-Tree record.  Otherwise the media sync might
         * be visible to the frontend.
         */
        if (record->flags & HAMMER_RECF_DELETED_FE)
                record->flags |= HAMMER_RECF_CONVERT_DELETE_ONDISK;

        /*
         * Assign the create_tid for new records.  Deletions already
         * have the record's entire key properly set up.
         */
        if ((record->flags & HAMMER_RECF_DELETE_ONDISK) == 0)
                record->rec.inode.base.base.create_tid = trans->tid;
        error = hammer_ip_sync_record(trans, record);

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

/*
 * XXX error handling
 */
int
hammer_sync_inode(hammer_inode_t ip, int handle_delete)
{
        struct hammer_transaction trans;
        struct bio *bio;
        hammer_depend_t depend;
        int error, tmp_error;

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

        hammer_start_transaction_fls(&trans, ip->hmp);

        /*
         * Any (directory) records this inode depends on must also be
         * synchronized.  The directory itself only needs to be flushed
         * if its inode is not already on-disk.
         */
        while ((depend = TAILQ_FIRST(&ip->depend_list)) != NULL) {
                hammer_record_t record;

                record = depend->record;
                TAILQ_REMOVE(&depend->record->depend_list, depend, rec_entry);
                TAILQ_REMOVE(&ip->depend_list, depend, ip_entry);
                --ip->depend_count;
                if (record->state != HAMMER_FST_FLUSH) {
                        record->state = HAMMER_FST_FLUSH;
                        /* add ref (steal ref from dependancy) */
                } else {
                        /* remove ref related to dependancy */
                        /* record still has at least one ref from state */
                        hammer_unref(&record->lock);
                        KKASSERT(record->lock.refs > 0);
                }
                if (record->ip->flags & HAMMER_INODE_ONDISK) {
                        kprintf("I");
                        hammer_sync_record_callback(record, &trans);
                } else {
                        kprintf("J");
                        KKASSERT((record->ip->flags & HAMMER_INODE_NEW) == 0);
                        hammer_flush_inode(record->ip, 0);
                }
                hammer_unref(&ip->lock);
                KKASSERT(ip->lock.refs > 0);
                kfree(depend, M_HAMMER);
        }


        /*
         * Sync inode deletions and truncations.
         */
        if (ip->sync_ino_rec.ino_nlinks == 0 && handle_delete && 
            (ip->flags & HAMMER_INODE_GONE) == 0) {
                /*
                 * Handle the case where the inode has been completely deleted
                 * and is no longer referenceable from the filesystem
                 * namespace.
                 *
                 * NOTE: We do not set the RDIRTY flag when updating the
                 * delete_tid, setting HAMMER_INODE_DELETED takes care of it.
                 */

                ip->flags |= HAMMER_INODE_GONE | HAMMER_INODE_DELETED;
                ip->flags &= ~HAMMER_INODE_TRUNCATED;
                ip->sync_flags &= ~HAMMER_INODE_TRUNCATED;
                if (ip->vp)
                        vtruncbuf(ip->vp, 0, HAMMER_BUFSIZE);
                error = hammer_ip_delete_range_all(&trans, ip);
                if (error)
                        Debugger("hammer_ip_delete_range_all errored");

                /*
                 * Sanity check.  The only records that remain should be
                 * marked for back-end deletion.
                 */
                {
                        hammer_record_t rec;

                        RB_FOREACH(rec, hammer_rec_rb_tree, &ip->rec_tree) {
                                KKASSERT(rec->state == HAMMER_FST_FLUSH);
                        }
                }

                /*
                 * Set delete_tid in both the frontend and backend
                 * copy of the inode record.
                 */
                ip->ino_rec.base.base.delete_tid = trans.tid;
                ip->sync_ino_rec.base.base.delete_tid = trans.tid;

                /*
                 * Indicate that the inode has/is-being deleted.
                 */
                ip->flags |= HAMMER_NODE_DELETED;
                hammer_modify_inode(&trans, ip, HAMMER_INODE_RDIRTY);
                hammer_modify_volume(&trans, trans.rootvol, NULL, 0);
                --ip->hmp->rootvol->ondisk->vol0_stat_inodes;
                hammer_modify_volume_done(trans.rootvol);
        } else if (ip->sync_flags & HAMMER_INODE_TRUNCATED) {
                /*
                 * Interlock trunc_off.  The VOP front-end may continue to
                 * make adjustments to it while we are blocked.
                 */
                off_t trunc_off;
                off_t aligned_trunc_off;

                trunc_off = ip->sync_trunc_off;
                aligned_trunc_off = (trunc_off + HAMMER_BUFMASK) &
                                    ~HAMMER_BUFMASK64;

                /*
                 * Delete any whole blocks on-media.  The front-end has
                 * already cleaned out any partial block and made it
                 * pending.  The front-end may have updated trunc_off
                 * while we were blocked so do not just unconditionally
                 * set it to the maximum offset.
                 */
                kprintf("sync truncation range @ %016llx\n", aligned_trunc_off);
                error = hammer_ip_delete_range(&trans, ip,
                                                aligned_trunc_off,
                                                0x7FFFFFFFFFFFFFFFLL);
                if (error)
                        Debugger("hammer_ip_delete_range errored");
                ip->sync_flags &= ~HAMMER_INODE_TRUNCATED;
                if (ip->trunc_off >= trunc_off) {
                        ip->trunc_off = 0x7FFFFFFFFFFFFFFFLL;
                        ip->flags &= ~HAMMER_INODE_TRUNCATED;
                }
        }

        error = 0;      /* XXX vfsync used to be here */

        /*
         * Flush any queued BIOs.
         */
        while ((bio = TAILQ_FIRST(&ip->bio_list)) != NULL) {
                TAILQ_REMOVE(&ip->bio_list, bio, bio_act);
#if 0
                kprintf("dowrite %016llx ip %p bio %p @ %016llx\n", trans.tid, ip, bio, bio->bio_offset);
#endif
                tmp_error = hammer_dowrite(&trans, ip, bio);
                if (tmp_error)
                        error = tmp_error;
        }
        ip->sync_flags &= ~HAMMER_INODE_BUFS;

        /*
         * Now sync related records.
         */
        for (;;) {
                tmp_error = RB_SCAN(hammer_rec_rb_tree, &ip->rec_tree, NULL,
                                hammer_sync_record_callback, &trans);
                KKASSERT(error <= 0);
                if (tmp_error < 0)
                        tmp_error = -error;
                if (tmp_error)
                        error = tmp_error;
                break;
        }

        /*
         * XDIRTY represents rec_tree and bio_list.  However, rec_tree may
         * contain new front-end records so short of scanning it we can't
         * just test whether it is empty or not. 
         *
         * If no error occured assume we succeeded.
         */
        if (error == 0)
                ip->sync_flags &= ~HAMMER_INODE_XDIRTY;

        if (error)
                Debugger("RB_SCAN errored");

        /*
         * Now update the inode's on-disk inode-data and/or on-disk record.
         * DELETED and ONDISK are managed only in ip->flags.
         */
        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->sync_flags &= ~(HAMMER_INODE_RDIRTY|HAMMER_INODE_DDIRTY|
                                    HAMMER_INODE_XDIRTY|HAMMER_INODE_ITIMES);
                while (RB_ROOT(&ip->rec_tree)) {
                        hammer_record_t record = RB_ROOT(&ip->rec_tree);
                        hammer_ref(&record->lock);
                        KKASSERT(record->lock.refs == 1);
                        record->flags |= HAMMER_RECF_DELETED_FE;
                        record->flags |= HAMMER_RECF_DELETED_BE;
                        hammer_cleardep_mem_record(record);
                        hammer_rel_mem_record(record);
                }
                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.  Also set
                 * the create_tid for the inode.
                 *
                 * Set create_tid in both the frontend and backend
                 * copy of the inode record.
                 */
                ip->ino_rec.base.base.create_tid = trans.tid;
                ip->sync_ino_rec.base.base.create_tid = trans.tid;
                ip->sync_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_DELETED) {
                error = hammer_update_inode(&trans, ip);
        } else 
        if ((ip->sync_flags & (HAMMER_INODE_RDIRTY | HAMMER_INODE_DDIRTY |
                               HAMMER_INODE_ITIMES)) == HAMMER_INODE_ITIMES) {
                error = hammer_update_itimes(&trans, ip);
        } else
        if (ip->sync_flags & (HAMMER_INODE_RDIRTY | HAMMER_INODE_DDIRTY |
                              HAMMER_INODE_ITIMES)) {
                error = hammer_update_inode(&trans, ip);
        }
        if (error)
                Debugger("hammer_update_itimes/inode errored");

        /*
         * Save the TID we used to sync the inode with to make sure we
         * do not improperly reuse it.
         */
        hammer_done_transaction(&trans);
        return(error);
}