hammer2 - Fix focus vs modify race

[dragonfly.git] / sys / vfs / hammer2 / hammer2_inode.c

/*
 * Copyright (c) 2011-2018 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@dragonflybsd.org>
 * by Venkatesh Srinivas <vsrinivas@dragonflybsd.org>
 *
 * 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.
 */
#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/lock.h>
#include <sys/uuid.h>

#include "hammer2.h"

#define INODE_DEBUG     0

RB_GENERATE2(hammer2_inode_tree, hammer2_inode, rbnode, hammer2_inode_cmp,
             hammer2_tid_t, meta.inum);

int
hammer2_inode_cmp(hammer2_inode_t *ip1, hammer2_inode_t *ip2)
{
        if (ip1->meta.inum < ip2->meta.inum)
                return(-1);
        if (ip1->meta.inum > ip2->meta.inum)
                return(1);
        return(0);
}

static __inline
void
hammer2_knote(struct vnode *vp, int flags)
{
        if (flags)
                KNOTE(&vp->v_pollinfo.vpi_kqinfo.ki_note, flags);
}

static
void
hammer2_inode_delayed_sideq(hammer2_inode_t *ip)
{
        hammer2_inode_sideq_t *ipul;
        hammer2_pfs_t *pmp = ip->pmp;

        if ((ip->flags & HAMMER2_INODE_ONSIDEQ) == 0) {
                ipul = kmalloc(sizeof(*ipul), pmp->minode,
                               M_WAITOK | M_ZERO);
                ipul->ip = ip;
                hammer2_spin_ex(&pmp->list_spin);
                if ((ip->flags & HAMMER2_INODE_ONSIDEQ) == 0) {
                        hammer2_inode_ref(ip);
                        atomic_set_int(&ip->flags,
                                       HAMMER2_INODE_ONSIDEQ);
                        TAILQ_INSERT_TAIL(&pmp->sideq, ipul, entry);
                        ++pmp->sideq_count;
                        hammer2_spin_unex(&pmp->list_spin);
                } else {
                        hammer2_spin_unex(&pmp->list_spin);
                        kfree(ipul, pmp->minode);
                }
        }
}

/*
 * HAMMER2 inode locks
 *
 * HAMMER2 offers shared and exclusive locks on inodes.  Pass a mask of
 * flags for options:
 *
 *      - pass HAMMER2_RESOLVE_SHARED if a shared lock is desired.  The
 *        inode locking function will automatically set the RDONLY flag.
 *
 *      - pass HAMMER2_RESOLVE_ALWAYS if you need the inode's meta-data.
 *        Most front-end inode locks do.
 *
 *      - pass HAMMER2_RESOLVE_NEVER if you do not want to require that
 *        the inode data be resolved.  This is used by the syncthr because
 *        it can run on an unresolved/out-of-sync cluster, and also by the
 *        vnode reclamation code to avoid unnecessary I/O (particularly when
 *        disposing of hundreds of thousands of cached vnodes).
 *
 * The inode locking function locks the inode itself, resolves any stale
 * chains in the inode's cluster, and allocates a fresh copy of the
 * cluster with 1 ref and all the underlying chains locked.
 *
 * ip->cluster will be stable while the inode is locked.
 *
 * NOTE: We don't combine the inode/chain lock because putting away an
 *       inode would otherwise confuse multiple lock holders of the inode.
 *
 * NOTE: In-memory inodes always point to hardlink targets (the actual file),
 *       and never point to a hardlink pointer.
 *
 * NOTE: If caller passes HAMMER2_RESOLVE_RDONLY the exclusive locking code
 *       will feel free to reduce the chain set in the cluster as an
 *       optimization.  It will still be validated against the quorum if
 *       appropriate, but the optimization might be able to reduce data
 *       accesses to one node.  This flag is automatically set if the inode
 *       is locked with HAMMER2_RESOLVE_SHARED.
 */
void
hammer2_inode_lock(hammer2_inode_t *ip, int how)
{
        hammer2_inode_ref(ip);

        /* 
         * Inode structure mutex
         */
        if (how & HAMMER2_RESOLVE_SHARED) {
                /*how |= HAMMER2_RESOLVE_RDONLY; not used */
                hammer2_mtx_sh(&ip->lock);
        } else {
                hammer2_mtx_ex(&ip->lock);
        }
}

/*
 * Select a chain out of an inode's cluster and lock it.
 *
 * The inode does not have to be locked.
 */
hammer2_chain_t *
hammer2_inode_chain(hammer2_inode_t *ip, int clindex, int how)
{
        hammer2_chain_t *chain;
        hammer2_cluster_t *cluster;

        hammer2_spin_sh(&ip->cluster_spin);
        cluster = &ip->cluster;
        if (clindex >= cluster->nchains)
                chain = NULL;
        else
                chain = cluster->array[clindex].chain;
        if (chain) {
                hammer2_chain_ref(chain);
                hammer2_spin_unsh(&ip->cluster_spin);
                hammer2_chain_lock(chain, how);
        } else {
                hammer2_spin_unsh(&ip->cluster_spin);
        }
        return chain;
}

hammer2_chain_t *
hammer2_inode_chain_and_parent(hammer2_inode_t *ip, int clindex,
                               hammer2_chain_t **parentp, int how)
{
        hammer2_chain_t *chain;
        hammer2_chain_t *parent;

        for (;;) {
                hammer2_spin_sh(&ip->cluster_spin);
                if (clindex >= ip->cluster.nchains)
                        chain = NULL;
                else
                        chain = ip->cluster.array[clindex].chain;
                if (chain) {
                        hammer2_chain_ref(chain);
                        hammer2_spin_unsh(&ip->cluster_spin);
                        hammer2_chain_lock(chain, how);
                } else {
                        hammer2_spin_unsh(&ip->cluster_spin);
                }

                /*
                 * Get parent, lock order must be (parent, chain).
                 */
                parent = chain->parent;
                if (parent) {
                        hammer2_chain_ref(parent);
                        hammer2_chain_unlock(chain);
                        hammer2_chain_lock(parent, how);
                        hammer2_chain_lock(chain, how);
                }
                if (ip->cluster.array[clindex].chain == chain &&
                    chain->parent == parent) {
                        break;
                }

                /*
                 * Retry
                 */
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
                if (parent) {
                        hammer2_chain_unlock(parent);
                        hammer2_chain_drop(parent);
                }
        }
        *parentp = parent;

        return chain;
}

void
hammer2_inode_unlock(hammer2_inode_t *ip)
{
        hammer2_mtx_unlock(&ip->lock);
        hammer2_inode_drop(ip);
}

/*
 * Temporarily release a lock held shared or exclusive.  Caller must
 * hold the lock shared or exclusive on call and lock will be released
 * on return.
 *
 * Restore a lock that was temporarily released.
 */
hammer2_mtx_state_t
hammer2_inode_lock_temp_release(hammer2_inode_t *ip)
{
        return hammer2_mtx_temp_release(&ip->lock);
}

void
hammer2_inode_lock_temp_restore(hammer2_inode_t *ip, hammer2_mtx_state_t ostate)
{
        hammer2_mtx_temp_restore(&ip->lock, ostate);
}

/*
 * Upgrade a shared inode lock to exclusive and return.  If the inode lock
 * is already held exclusively this is a NOP.
 *
 * The caller MUST hold the inode lock either shared or exclusive on call
 * and will own the lock exclusively on return.
 *
 * Returns non-zero if the lock was already exclusive prior to the upgrade.
 */
int
hammer2_inode_lock_upgrade(hammer2_inode_t *ip)
{
        int wasexclusive;

        if (mtx_islocked_ex(&ip->lock)) {
                wasexclusive = 1;
        } else {
                hammer2_mtx_unlock(&ip->lock);
                hammer2_mtx_ex(&ip->lock);
                wasexclusive = 0;
        }
        return wasexclusive;
}

/*
 * Downgrade an inode lock from exclusive to shared only if the inode
 * lock was previously shared.  If the inode lock was previously exclusive,
 * this is a NOP.
 */
void
hammer2_inode_lock_downgrade(hammer2_inode_t *ip, int wasexclusive)
{
        if (wasexclusive == 0)
                mtx_downgrade(&ip->lock);
}

/*
 * Lookup an inode by inode number
 */
hammer2_inode_t *
hammer2_inode_lookup(hammer2_pfs_t *pmp, hammer2_tid_t inum)
{
        hammer2_inode_t *ip;

        KKASSERT(pmp);
        if (pmp->spmp_hmp) {
                ip = NULL;
        } else {
                hammer2_spin_ex(&pmp->inum_spin);
                ip = RB_LOOKUP(hammer2_inode_tree, &pmp->inum_tree, inum);
                if (ip)
                        hammer2_inode_ref(ip);
                hammer2_spin_unex(&pmp->inum_spin);
        }
        return(ip);
}

/*
 * Adding a ref to an inode is only legal if the inode already has at least
 * one ref.
 *
 * (can be called with spinlock held)
 */
void
hammer2_inode_ref(hammer2_inode_t *ip)
{
        atomic_add_int(&ip->refs, 1);
        if (hammer2_debug & 0x80000) {
                kprintf("INODE+1 %p (%d->%d)\n", ip, ip->refs - 1, ip->refs);
                print_backtrace(8);
        }
}

/*
 * Drop an inode reference, freeing the inode when the last reference goes
 * away.
 */
void
hammer2_inode_drop(hammer2_inode_t *ip)
{
        hammer2_pfs_t *pmp;
        u_int refs;

        while (ip) {
                if (hammer2_debug & 0x80000) {
                        kprintf("INODE-1 %p (%d->%d)\n",
                                ip, ip->refs, ip->refs - 1);
                        print_backtrace(8);
                }
                refs = ip->refs;
                cpu_ccfence();
                if (refs == 1) {
                        /*
                         * Transition to zero, must interlock with
                         * the inode inumber lookup tree (if applicable).
                         * It should not be possible for anyone to race
                         * the transition to 0.
                         */
                        pmp = ip->pmp;
                        KKASSERT(pmp);
                        hammer2_spin_ex(&pmp->inum_spin);

                        if (atomic_cmpset_int(&ip->refs, 1, 0)) {
                                KKASSERT(hammer2_mtx_refs(&ip->lock) == 0);
                                if (ip->flags & HAMMER2_INODE_ONRBTREE) {
                                        atomic_clear_int(&ip->flags,
                                                     HAMMER2_INODE_ONRBTREE);
                                        RB_REMOVE(hammer2_inode_tree,
                                                  &pmp->inum_tree, ip);
                                        --pmp->inum_count;
                                }
                                hammer2_spin_unex(&pmp->inum_spin);

                                ip->pmp = NULL;

                                /*
                                 * Cleaning out ip->cluster isn't entirely
                                 * trivial.
                                 */
                                hammer2_inode_repoint(ip, NULL, NULL);

                                kfree(ip, pmp->minode);
                                atomic_add_long(&pmp->inmem_inodes, -1);
                                ip = NULL;      /* will terminate loop */
                        } else {
                                hammer2_spin_unex(&ip->pmp->inum_spin);
                        }
                } else {
                        /*
                         * Non zero transition
                         */
                        if (atomic_cmpset_int(&ip->refs, refs, refs - 1))
                                break;
                }
        }
}

/*
 * Get the vnode associated with the given inode, allocating the vnode if
 * necessary.  The vnode will be returned exclusively locked.
 *
 * *errorp is set to a UNIX error, not a HAMMER2 error.
 *
 * The caller must lock the inode (shared or exclusive).
 *
 * Great care must be taken to avoid deadlocks and vnode acquisition/reclaim
 * races.
 */
struct vnode *
hammer2_igetv(hammer2_inode_t *ip, int *errorp)
{
        hammer2_pfs_t *pmp;
        struct vnode *vp;

        pmp = ip->pmp;
        KKASSERT(pmp != NULL);
        *errorp = 0;

        for (;;) {
                /*
                 * Attempt to reuse an existing vnode assignment.  It is
                 * possible to race a reclaim so the vget() may fail.  The
                 * inode must be unlocked during the vget() to avoid a
                 * deadlock against a reclaim.
                 */
                int wasexclusive;

                vp = ip->vp;
                if (vp) {
                        /*
                         * Inode must be unlocked during the vget() to avoid
                         * possible deadlocks, but leave the ip ref intact.
                         *
                         * vnode is held to prevent destruction during the
                         * vget().  The vget() can still fail if we lost
                         * a reclaim race on the vnode.
                         */
                        hammer2_mtx_state_t ostate;

                        vhold(vp);
                        ostate = hammer2_inode_lock_temp_release(ip);
                        if (vget(vp, LK_EXCLUSIVE)) {
                                vdrop(vp);
                                hammer2_inode_lock_temp_restore(ip, ostate);
                                continue;
                        }
                        hammer2_inode_lock_temp_restore(ip, ostate);
                        vdrop(vp);
                        /* vp still locked and ref from vget */
                        if (ip->vp != vp) {
                                kprintf("hammer2: igetv race %p/%p\n",
                                        ip->vp, vp);
                                vput(vp);
                                continue;
                        }
                        *errorp = 0;
                        break;
                }

                /*
                 * No vnode exists, allocate a new vnode.  Beware of
                 * allocation races.  This function will return an
                 * exclusively locked and referenced vnode.
                 */
                *errorp = getnewvnode(VT_HAMMER2, pmp->mp, &vp, 0, 0);
                if (*errorp) {
                        kprintf("hammer2: igetv getnewvnode failed %d\n",
                                *errorp);
                        vp = NULL;
                        break;
                }

                /*
                 * Lock the inode and check for an allocation race.
                 */
                wasexclusive = hammer2_inode_lock_upgrade(ip);
                if (ip->vp != NULL) {
                        vp->v_type = VBAD;
                        vx_put(vp);
                        hammer2_inode_lock_downgrade(ip, wasexclusive);
                        continue;
                }

                switch (ip->meta.type) {
                case HAMMER2_OBJTYPE_DIRECTORY:
                        vp->v_type = VDIR;
                        break;
                case HAMMER2_OBJTYPE_REGFILE:
                        /*
                         * Regular file must use buffer cache I/O
                         * (VKVABIO cpu sync semantics supported)
                         */
                        vp->v_type = VREG;
                        vsetflags(vp, VKVABIO);
                        vinitvmio(vp, ip->meta.size,
                                  HAMMER2_LBUFSIZE,
                                  (int)ip->meta.size & HAMMER2_LBUFMASK);
                        break;
                case HAMMER2_OBJTYPE_SOFTLINK:
                        /*
                         * XXX for now we are using the generic file_read
                         * and file_write code so we need a buffer cache
                         * association.
                         *
                         * (VKVABIO cpu sync semantics supported)
                         */
                        vp->v_type = VLNK;
                        vsetflags(vp, VKVABIO);
                        vinitvmio(vp, ip->meta.size,
                                  HAMMER2_LBUFSIZE,
                                  (int)ip->meta.size & HAMMER2_LBUFMASK);
                        break;
                case HAMMER2_OBJTYPE_CDEV:
                        vp->v_type = VCHR;
                        /* fall through */
                case HAMMER2_OBJTYPE_BDEV:
                        vp->v_ops = &pmp->mp->mnt_vn_spec_ops;
                        if (ip->meta.type != HAMMER2_OBJTYPE_CDEV)
                                vp->v_type = VBLK;
                        addaliasu(vp,
                                  ip->meta.rmajor,
                                  ip->meta.rminor);
                        break;
                case HAMMER2_OBJTYPE_FIFO:
                        vp->v_type = VFIFO;
                        vp->v_ops = &pmp->mp->mnt_vn_fifo_ops;
                        break;
                case HAMMER2_OBJTYPE_SOCKET:
                        vp->v_type = VSOCK;
                        break;
                default:
                        panic("hammer2: unhandled objtype %d",
                              ip->meta.type);
                        break;
                }

                if (ip == pmp->iroot)
                        vsetflags(vp, VROOT);

                vp->v_data = ip;
                ip->vp = vp;
                hammer2_inode_ref(ip);          /* vp association */
                hammer2_inode_lock_downgrade(ip, wasexclusive);
                break;
        }

        /*
         * Return non-NULL vp and *errorp == 0, or NULL vp and *errorp != 0.
         */
        if (hammer2_debug & 0x0002) {
                kprintf("igetv vp %p refs 0x%08x aux 0x%08x\n",
                        vp, vp->v_refcnt, vp->v_auxrefs);
        }
        return (vp);
}

/*
 * Returns the inode associated with the passed-in cluster, creating the
 * inode if necessary and synchronizing it to the passed-in cluster otherwise.
 * When synchronizing, if idx >= 0, only cluster index (idx) is synchronized.
 * Otherwise the whole cluster is synchronized.
 *
 * The passed-in cluster must be locked and will remain locked on return.
 * The returned inode will be locked and the caller may dispose of both
 * via hammer2_inode_unlock() + hammer2_inode_drop().  However, if the caller
 * needs to resolve a hardlink it must ref/unlock/relock/drop the inode.
 *
 * The hammer2_inode structure regulates the interface between the high level
 * kernel VNOPS API and the filesystem backend (the chains).
 *
 * On return the inode is locked with the supplied cluster.
 */
hammer2_inode_t *
hammer2_inode_get(hammer2_pfs_t *pmp, hammer2_inode_t *dip,
                  hammer2_xop_head_t *xop, int idx)
{
        hammer2_inode_t *nip;
        const hammer2_inode_data_t *iptmp;
        const hammer2_inode_data_t *nipdata;

        KKASSERT(xop == NULL ||
                 hammer2_cluster_type(&xop->cluster) ==
                 HAMMER2_BREF_TYPE_INODE);
        KKASSERT(pmp);

        /*
         * Interlocked lookup/ref of the inode.  This code is only needed
         * when looking up inodes with nlinks != 0 (TODO: optimize out
         * otherwise and test for duplicates).
         *
         * Cluster can be NULL during the initial pfs allocation.
         */
again:
        while (xop) {
                iptmp = &hammer2_xop_gdata(xop)->ipdata;
                nip = hammer2_inode_lookup(pmp, iptmp->meta.inum);
                hammer2_xop_pdata(xop);
                if (nip == NULL)
                        break;

                hammer2_mtx_ex(&nip->lock);

                /*
                 * Handle SMP race (not applicable to the super-root spmp
                 * which can't index inodes due to duplicative inode numbers).
                 */
                if (pmp->spmp_hmp == NULL &&
                    (nip->flags & HAMMER2_INODE_ONRBTREE) == 0) {
                        hammer2_mtx_unlock(&nip->lock);
                        hammer2_inode_drop(nip);
                        continue;
                }
                if (idx >= 0)
                        hammer2_inode_repoint_one(nip, &xop->cluster, idx);
                else
                        hammer2_inode_repoint(nip, NULL, &xop->cluster);

                return nip;
        }

        /*
         * We couldn't find the inode number, create a new inode.
         */
        nip = kmalloc(sizeof(*nip), pmp->minode, M_WAITOK | M_ZERO);
        spin_init(&nip->cluster_spin, "h2clspin");
        atomic_add_long(&pmp->inmem_inodes, 1);
        hammer2_pfs_memory_inc(pmp);
        hammer2_pfs_memory_wakeup(pmp);
        if (pmp->spmp_hmp)
                nip->flags = HAMMER2_INODE_SROOT;

        /*
         * Initialize nip's cluster.  A cluster is provided for normal
         * inodes but typically not for the super-root or PFS inodes.
         */
        nip->cluster.refs = 1;
        nip->cluster.pmp = pmp;
        nip->cluster.flags |= HAMMER2_CLUSTER_INODE;
        if (xop) {
                nipdata = &hammer2_xop_gdata(xop)->ipdata;
                nip->meta = nipdata->meta;
                hammer2_xop_pdata(xop);
                atomic_set_int(&nip->flags, HAMMER2_INODE_METAGOOD);
                hammer2_inode_repoint(nip, NULL, &xop->cluster);
        } else {
                nip->meta.inum = 1;             /* PFS inum is always 1 XXX */
                /* mtime will be updated when a cluster is available */
                atomic_set_int(&nip->flags, HAMMER2_INODE_METAGOOD);/*XXX*/
        }

        nip->pmp = pmp;

        /*
         * ref and lock on nip gives it state compatible to after a
         * hammer2_inode_lock() call.
         */
        nip->refs = 1;
        hammer2_mtx_init(&nip->lock, "h2inode");
        hammer2_mtx_ex(&nip->lock);
        /* combination of thread lock and chain lock == inode lock */

        /*
         * Attempt to add the inode.  If it fails we raced another inode
         * get.  Undo all the work and try again.
         */
        if (pmp->spmp_hmp == NULL) {
                hammer2_spin_ex(&pmp->inum_spin);
                if (RB_INSERT(hammer2_inode_tree, &pmp->inum_tree, nip)) {
                        hammer2_spin_unex(&pmp->inum_spin);
                        hammer2_mtx_unlock(&nip->lock);
                        hammer2_inode_drop(nip);
                        goto again;
                }
                atomic_set_int(&nip->flags, HAMMER2_INODE_ONRBTREE);
                ++pmp->inum_count;
                hammer2_spin_unex(&pmp->inum_spin);
        }

        return (nip);
}

/*
 * MESSY! CLEANUP!
 *
 * Create a new inode using the vattr to figure out the type.  A non-zero
 * type field overrides vattr.  We need the directory to set iparent or to
 * use when the inode is directly embedded in a directory (typically super-root
 * entries), but note that this really only applies OBJTYPE_DIRECTORY as
 * non-directory inodes can be hardlinked.
 *
 * If no error occurs the new inode is returned, otherwise NULL is returned.
 * It is possible for an error to create a junk inode and then fail later.
 * It will attempt to delete the junk inode and return NULL in this situation.
 *
 * If vap and/or cred are NULL the related fields are not set and the
 * inode type defaults to a directory.  This is used when creating PFSs
 * under the super-root, so the inode number is set to 1 in this case.
 *
 * dip is not locked on entry.
 *
 * NOTE: This function is used to create all manners of inodes, including
 *       super-root entries for snapshots and PFSs.  When used to create a
 *       snapshot the inode will be temporarily associated with the spmp.
 *
 * NOTE: When creating a normal file or directory the name/name_len/lhc
 *       is optional, but is typically specified to make debugging and
 *       recovery easeier.
 */
hammer2_inode_t *
hammer2_inode_create(hammer2_inode_t *dip, hammer2_inode_t *pip,
                     struct vattr *vap, struct ucred *cred,
                     const uint8_t *name, size_t name_len, hammer2_key_t lhc,
                     hammer2_key_t inum,
                     uint8_t type, uint8_t target_type,
                     int flags, int *errorp)
{
        hammer2_xop_create_t *xop;
        hammer2_inode_t *nip;
        int error;
        uid_t xuid;
        uuid_t pip_uid;
        uuid_t pip_gid;
        uint32_t pip_mode;
        uint8_t pip_comp_algo;
        uint8_t pip_check_algo;
        hammer2_tid_t pip_inum;

        if (name)
                lhc = hammer2_dirhash(name, name_len);
        *errorp = 0;
        nip = NULL;

        /*
         * Locate the inode or indirect block to create the new
         * entry in.  At the same time check for key collisions
         * and iterate until we don't get one.
         *
         * Lock the directory exclusively for now to guarantee that
         * we can find an unused lhc for the name.  Due to collisions,
         * two different creates can end up with the same lhc so we
         * cannot depend on the OS to prevent the collision.
         */
        hammer2_inode_lock(dip, 0);

        pip_uid = pip->meta.uid;
        pip_gid = pip->meta.gid;
        pip_mode = pip->meta.mode;
        pip_comp_algo = pip->meta.comp_algo;
        pip_check_algo = pip->meta.check_algo;
        pip_inum = (pip == pip->pmp->iroot) ? 1 : pip->meta.inum;

        /*
         * If name specified, locate an unused key in the collision space.
         * Otherwise use the passed-in lhc directly.
         */
        if (name) {
                hammer2_xop_scanlhc_t *sxop;
                hammer2_key_t lhcbase;

                lhcbase = lhc;
                sxop = hammer2_xop_alloc(dip, HAMMER2_XOP_MODIFYING);
                sxop->lhc = lhc;
                hammer2_xop_start(&sxop->head, hammer2_xop_scanlhc);
                while ((error = hammer2_xop_collect(&sxop->head, 0)) == 0) {
                        if (lhc != sxop->head.cluster.focus->bref.key)
                                break;
                        ++lhc;
                }
                hammer2_xop_retire(&sxop->head, HAMMER2_XOPMASK_VOP);

                if (error) {
                        if (error != HAMMER2_ERROR_ENOENT)
                                goto done2;
                        ++lhc;
                        error = 0;
                }
                if ((lhcbase ^ lhc) & ~HAMMER2_DIRHASH_LOMASK) {
                        error = HAMMER2_ERROR_ENOSPC;
                        goto done2;
                }
        }

        /*
         * Create the inode with the lhc as the key.
         */
        xop = hammer2_xop_alloc(dip, HAMMER2_XOP_MODIFYING);
        xop->lhc = lhc;
        xop->flags = flags;
        bzero(&xop->meta, sizeof(xop->meta));

        if (vap) {
                xop->meta.type = hammer2_get_obj_type(vap->va_type);

                switch (xop->meta.type) {
                case HAMMER2_OBJTYPE_CDEV:
                case HAMMER2_OBJTYPE_BDEV:
                        xop->meta.rmajor = vap->va_rmajor;
                        xop->meta.rminor = vap->va_rminor;
                        break;
                default:
                        break;
                }
                type = xop->meta.type;
        } else {
                xop->meta.type = type;
                xop->meta.target_type = target_type;
        }
        xop->meta.inum = inum;
        xop->meta.iparent = pip_inum;
        
        /* Inherit parent's inode compression mode. */
        xop->meta.comp_algo = pip_comp_algo;
        xop->meta.check_algo = pip_check_algo;
        xop->meta.version = HAMMER2_INODE_VERSION_ONE;
        hammer2_update_time(&xop->meta.ctime);
        xop->meta.mtime = xop->meta.ctime;
        if (vap)
                xop->meta.mode = vap->va_mode;
        xop->meta.nlinks = 1;
        if (vap) {
                if (dip->pmp) {
                        xuid = hammer2_to_unix_xid(&pip_uid);
                        xuid = vop_helper_create_uid(dip->pmp->mp,
                                                     pip_mode,
                                                     xuid,
                                                     cred,
                                                     &vap->va_mode);
                } else {
                        /* super-root has no dip and/or pmp */
                        xuid = 0;
                }
                if (vap->va_vaflags & VA_UID_UUID_VALID)
                        xop->meta.uid = vap->va_uid_uuid;
                else if (vap->va_uid != (uid_t)VNOVAL)
                        hammer2_guid_to_uuid(&xop->meta.uid, vap->va_uid);
                else
                        hammer2_guid_to_uuid(&xop->meta.uid, xuid);

                if (vap->va_vaflags & VA_GID_UUID_VALID)
                        xop->meta.gid = vap->va_gid_uuid;
                else if (vap->va_gid != (gid_t)VNOVAL)
                        hammer2_guid_to_uuid(&xop->meta.gid, vap->va_gid);
                else
                        xop->meta.gid = pip_gid;
        }

        /*
         * Regular files and softlinks allow a small amount of data to be
         * directly embedded in the inode.  This flag will be cleared if
         * the size is extended past the embedded limit.
         */
        if (xop->meta.type == HAMMER2_OBJTYPE_REGFILE ||
            xop->meta.type == HAMMER2_OBJTYPE_SOFTLINK) {
                xop->meta.op_flags |= HAMMER2_OPFLAG_DIRECTDATA;
        }
        if (name) {
                hammer2_xop_setname(&xop->head, name, name_len);
        } else {
                name_len = hammer2_xop_setname_inum(&xop->head, inum);
                KKASSERT(lhc == inum);
        }
        xop->meta.name_len = name_len;
        xop->meta.name_key = lhc;
        KKASSERT(name_len < HAMMER2_INODE_MAXNAME);

        hammer2_xop_start(&xop->head, hammer2_inode_xop_create);

        error = hammer2_xop_collect(&xop->head, 0);
#if INODE_DEBUG
        kprintf("CREATE INODE %*.*s\n",
                (int)name_len, (int)name_len, name);
#endif

        if (error) {
                *errorp = error;
                goto done;
        }

        /*
         * Set up the new inode if not a hardlink pointer.
         *
         * NOTE: *_get() integrates chain's lock into the inode lock.
         *
         * NOTE: Only one new inode can currently be created per
         *       transaction.  If the need arises we can adjust
         *       hammer2_trans_init() to allow more.
         *
         * NOTE: nipdata will have chain's blockset data.
         */
        nip = hammer2_inode_get(dip->pmp, dip, &xop->head, -1);
        nip->comp_heuristic = 0;
done:
        hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
done2:
        hammer2_inode_unlock(dip);

        return (nip);
}

/*
 * Create a directory entry under dip with the specified name, inode number,
 * and OBJTYPE (type).
 *
 * This returns a UNIX errno code, not a HAMMER2_ERROR_* code.
 */
int
hammer2_dirent_create(hammer2_inode_t *dip, const char *name, size_t name_len,
                      hammer2_key_t inum, uint8_t type)
{
        hammer2_xop_mkdirent_t *xop;
        hammer2_key_t lhc;
        int error;

        lhc = 0;
        error = 0;

        KKASSERT(name != NULL);
        lhc = hammer2_dirhash(name, name_len);

        /*
         * Locate the inode or indirect block to create the new
         * entry in.  At the same time check for key collisions
         * and iterate until we don't get one.
         *
         * Lock the directory exclusively for now to guarantee that
         * we can find an unused lhc for the name.  Due to collisions,
         * two different creates can end up with the same lhc so we
         * cannot depend on the OS to prevent the collision.
         */
        hammer2_inode_lock(dip, 0);

        /*
         * If name specified, locate an unused key in the collision space.
         * Otherwise use the passed-in lhc directly.
         */
        {
                hammer2_xop_scanlhc_t *sxop;
                hammer2_key_t lhcbase;

                lhcbase = lhc;
                sxop = hammer2_xop_alloc(dip, HAMMER2_XOP_MODIFYING);
                sxop->lhc = lhc;
                hammer2_xop_start(&sxop->head, hammer2_xop_scanlhc);
                while ((error = hammer2_xop_collect(&sxop->head, 0)) == 0) {
                        if (lhc != sxop->head.cluster.focus->bref.key)
                                break;
                        ++lhc;
                }
                hammer2_xop_retire(&sxop->head, HAMMER2_XOPMASK_VOP);

                if (error) {
                        if (error != HAMMER2_ERROR_ENOENT)
                                goto done2;
                        ++lhc;
                        error = 0;
                }
                if ((lhcbase ^ lhc) & ~HAMMER2_DIRHASH_LOMASK) {
                        error = HAMMER2_ERROR_ENOSPC;
                        goto done2;
                }
        }

        /*
         * Create the directory entry with the lhc as the key.
         */
        xop = hammer2_xop_alloc(dip, HAMMER2_XOP_MODIFYING);
        xop->lhc = lhc;
        bzero(&xop->dirent, sizeof(xop->dirent));
        xop->dirent.inum = inum;
        xop->dirent.type = type;
        xop->dirent.namlen = name_len;

        KKASSERT(name_len < HAMMER2_INODE_MAXNAME);
        hammer2_xop_setname(&xop->head, name, name_len);

        hammer2_xop_start(&xop->head, hammer2_inode_xop_mkdirent);

        error = hammer2_xop_collect(&xop->head, 0);

        hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
done2:
        error = hammer2_error_to_errno(error);
        hammer2_inode_unlock(dip);

        return error;
}

/*
 * Repoint ip->cluster's chains to cluster's chains and fixup the default
 * focus.  All items, valid or invalid, are repointed.  hammer2_xop_start()
 * filters out invalid or non-matching elements.
 *
 * Caller must hold the inode and cluster exclusive locked, if not NULL,
 * must also be locked.
 *
 * Cluster may be NULL to clean out any chains in ip->cluster.
 */
void
hammer2_inode_repoint(hammer2_inode_t *ip, hammer2_inode_t *pip,
                      hammer2_cluster_t *cluster)
{
        hammer2_chain_t *dropch[HAMMER2_MAXCLUSTER];
        hammer2_chain_t *ochain;
        hammer2_chain_t *nchain;
        int i;

        bzero(dropch, sizeof(dropch));

        /*
         * Replace chains in ip->cluster with chains from cluster and
         * adjust the focus if necessary.
         *
         * NOTE: nchain and/or ochain can be NULL due to gaps
         *       in the cluster arrays.
         */
        hammer2_spin_ex(&ip->cluster_spin);
        for (i = 0; cluster && i < cluster->nchains; ++i) {
                /*
                 * Do not replace elements which are the same.  Also handle
                 * element count discrepancies.
                 */
                nchain = cluster->array[i].chain;
                if (i < ip->cluster.nchains) {
                        ochain = ip->cluster.array[i].chain;
                        if (ochain == nchain)
                                continue;
                } else {
                        ochain = NULL;
                }

                /*
                 * Make adjustments
                 */
                ip->cluster.array[i].chain = nchain;
                ip->cluster.array[i].flags &= ~HAMMER2_CITEM_INVALID;
                ip->cluster.array[i].flags |= cluster->array[i].flags &
                                              HAMMER2_CITEM_INVALID;
                if (nchain)
                        hammer2_chain_ref(nchain);
                dropch[i] = ochain;
        }

        /*
         * Release any left-over chains in ip->cluster.
         */
        while (i < ip->cluster.nchains) {
                nchain = ip->cluster.array[i].chain;
                if (nchain) {
                        ip->cluster.array[i].chain = NULL;
                        ip->cluster.array[i].flags |= HAMMER2_CITEM_INVALID;
                }
                dropch[i] = nchain;
                ++i;
        }

        /*
         * Fixup fields.  Note that the inode-embedded cluster is never
         * directly locked.
         */
        if (cluster) {
                ip->cluster.nchains = cluster->nchains;
                ip->cluster.focus = cluster->focus;
                ip->cluster.flags = cluster->flags & ~HAMMER2_CLUSTER_LOCKED;
        } else {
                ip->cluster.nchains = 0;
                ip->cluster.focus = NULL;
                ip->cluster.flags &= ~HAMMER2_CLUSTER_ZFLAGS;
        }

        hammer2_spin_unex(&ip->cluster_spin);

        /*
         * Cleanup outside of spinlock
         */
        while (--i >= 0) {
                if (dropch[i])
                        hammer2_chain_drop(dropch[i]);
        }
}

/*
 * Repoint a single element from the cluster to the ip.  Used by the
 * synchronization threads to piecemeal update inodes.  Does not change
 * focus and requires inode to be re-locked to clean-up flags (XXX).
 */
void
hammer2_inode_repoint_one(hammer2_inode_t *ip, hammer2_cluster_t *cluster,
                          int idx)
{
        hammer2_chain_t *ochain;
        hammer2_chain_t *nchain;
        int i;

        hammer2_spin_ex(&ip->cluster_spin);
        KKASSERT(idx < cluster->nchains);
        if (idx < ip->cluster.nchains) {
                ochain = ip->cluster.array[idx].chain;
                nchain = cluster->array[idx].chain;
        } else {
                ochain = NULL;
                nchain = cluster->array[idx].chain;
                for (i = ip->cluster.nchains; i <= idx; ++i) {
                        bzero(&ip->cluster.array[i],
                              sizeof(ip->cluster.array[i]));
                        ip->cluster.array[i].flags |= HAMMER2_CITEM_INVALID;
                }
                ip->cluster.nchains = idx + 1;
        }
        if (ochain != nchain) {
                /*
                 * Make adjustments.
                 */
                ip->cluster.array[idx].chain = nchain;
                ip->cluster.array[idx].flags &= ~HAMMER2_CITEM_INVALID;
                ip->cluster.array[idx].flags |= cluster->array[idx].flags &
                                                HAMMER2_CITEM_INVALID;
        }
        hammer2_spin_unex(&ip->cluster_spin);
        if (ochain != nchain) {
                if (nchain)
                        hammer2_chain_ref(nchain);
                if (ochain)
                        hammer2_chain_drop(ochain);
        }
}

/*
 * Called with a locked inode to finish unlinking an inode after xop_unlink
 * had been run.  This function is responsible for decrementing nlinks.
 *
 * We don't bother decrementing nlinks if the file is not open and this was
 * the last link.
 *
 * If the inode is a hardlink target it's chain has not yet been deleted,
 * otherwise it's chain has been deleted.
 *
 * If isopen then any prior deletion was not permanent and the inode is
 * left intact with nlinks == 0;
 */
int
hammer2_inode_unlink_finisher(hammer2_inode_t *ip, int isopen)
{
        hammer2_pfs_t *pmp;
        int error;

        pmp = ip->pmp;

        /*
         * Decrement nlinks.  If this is the last link and the file is
         * not open we can just delete the inode and not bother dropping
         * nlinks to 0 (avoiding unnecessary block updates).
         */
        if (ip->meta.nlinks == 1) {
                atomic_set_int(&ip->flags, HAMMER2_INODE_ISUNLINKED);
                if (isopen == 0)
                        goto killit;
        }

        hammer2_inode_modify(ip);
        --ip->meta.nlinks;
        if ((int64_t)ip->meta.nlinks < 0)
                ip->meta.nlinks = 0;    /* safety */

        /*
         * If nlinks is not zero we are done.  However, this should only be
         * possible with a hardlink target.  If the inode is an embedded
         * hardlink nlinks should have dropped to zero, warn and proceed
         * with the next step.
         */
        if (ip->meta.nlinks) {
                if ((ip->meta.name_key & HAMMER2_DIRHASH_VISIBLE) == 0)
                        return 0;
                kprintf("hammer2_inode_unlink: nlinks was not 0 (%jd)\n",
                        (intmax_t)ip->meta.nlinks);
                return 0;
        }

        if (ip->vp)
                hammer2_knote(ip->vp, NOTE_DELETE);

        /*
         * nlinks is now an implied zero, delete the inode if not open.
         * We avoid unnecessary media updates by not bothering to actually
         * decrement nlinks for the 1->0 transition
         *
         * Put the inode on the sideq to ensure that any disconnected chains
         * get properly flushed (so they can be freed).
         */
        if (isopen == 0) {
                hammer2_xop_destroy_t *xop;

killit:
                hammer2_inode_delayed_sideq(ip);
                atomic_set_int(&ip->flags, HAMMER2_INODE_ISDELETED);
                xop = hammer2_xop_alloc(ip, HAMMER2_XOP_MODIFYING);
                hammer2_xop_start(&xop->head, hammer2_inode_xop_destroy);
                error = hammer2_xop_collect(&xop->head, 0);
                hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
        }
        error = 0;      /* XXX */

        return error;
}

/*
 * Mark an inode as being modified, meaning that the caller will modify
 * ip->meta.
 *
 * If a vnode is present we set the vnode dirty and the nominal filesystem
 * sync will also handle synchronizing the inode meta-data.  If no vnode
 * is present we must ensure that the inode is on pmp->sideq.
 *
 * NOTE: No mtid (modify_tid) is passed into this routine.  The caller is
 *       only modifying the in-memory inode.  A modify_tid is synchronized
 *       later when the inode gets flushed.
 *
 * NOTE: As an exception to the general rule, the inode MAY be locked
 *       shared for this particular call.
 */
void
hammer2_inode_modify(hammer2_inode_t *ip)
{
        atomic_set_int(&ip->flags, HAMMER2_INODE_MODIFIED);
        if (ip->vp) {
                vsetisdirty(ip->vp);
        } else if (ip->pmp && (ip->flags & HAMMER2_INODE_NOSIDEQ) == 0) {
                hammer2_inode_delayed_sideq(ip);
        }
}

/*
 * Synchronize the inode's frontend state with the chain state prior
 * to any explicit flush of the inode or any strategy write call.  This
 * does not flush the inode's chain or its sub-topology to media (higher
 * level layers are responsible for doing that).
 *
 * Called with a locked inode inside a normal transaction.
 *
 * inode must be locked.
 */
int
hammer2_inode_chain_sync(hammer2_inode_t *ip)
{
        int error;

        error = 0;
        if (ip->flags & (HAMMER2_INODE_RESIZED | HAMMER2_INODE_MODIFIED)) {
                hammer2_xop_fsync_t *xop;

                xop = hammer2_xop_alloc(ip, HAMMER2_XOP_MODIFYING);
                xop->clear_directdata = 0;
                if (ip->flags & HAMMER2_INODE_RESIZED) {
                        if ((ip->meta.op_flags & HAMMER2_OPFLAG_DIRECTDATA) &&
                            ip->meta.size > HAMMER2_EMBEDDED_BYTES) {
                                ip->meta.op_flags &= ~HAMMER2_OPFLAG_DIRECTDATA;
                                xop->clear_directdata = 1;
                        }
                        xop->osize = ip->osize;
                } else {
                        xop->osize = ip->meta.size;     /* safety */
                }
                xop->ipflags = ip->flags;
                xop->meta = ip->meta;

                atomic_clear_int(&ip->flags, HAMMER2_INODE_RESIZED |
                                             HAMMER2_INODE_MODIFIED);
                hammer2_xop_start(&xop->head, hammer2_inode_xop_chain_sync);
                error = hammer2_xop_collect(&xop->head, 0);
                hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
                if (error == HAMMER2_ERROR_ENOENT)
                        error = 0;
                if (error) {
                        kprintf("hammer2: unable to fsync inode %p\n", ip);
                        /*
                        atomic_set_int(&ip->flags,
                                       xop->ipflags & (HAMMER2_INODE_RESIZED |
                                                       HAMMER2_INODE_MODIFIED));
                        */
                        /* XXX return error somehow? */
                }
        }
        return error;
}

/*
 * Flushes the inode's chain and its sub-topology to media.  Interlocks
 * HAMMER2_INODE_DIRTYDATA by clearing it prior to the flush.  Any strategy
 * function creating or modifying a chain under this inode will re-set the
 * flag.
 *
 * inode must be locked.
 */
int
hammer2_inode_chain_flush(hammer2_inode_t *ip)
{
        hammer2_xop_fsync_t *xop;
        int error;

        atomic_clear_int(&ip->flags, HAMMER2_INODE_DIRTYDATA);
        xop = hammer2_xop_alloc(ip, HAMMER2_XOP_MODIFYING |
                                    HAMMER2_XOP_INODE_STOP);
        hammer2_xop_start(&xop->head, hammer2_inode_xop_flush);
        error = hammer2_xop_collect(&xop->head, HAMMER2_XOP_COLLECT_WAITALL);
        hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
        if (error == HAMMER2_ERROR_ENOENT)
                error = 0;

        return error;
}

/*
 * The normal filesystem sync no longer has visibility to an inode structure
 * after its vnode has been reclaimed.  In this situation a dirty inode may
 * require additional processing to synchronize ip->meta to its underlying
 * cluster nodes.
 *
 * In particular, reclaims can occur in almost any state (for example, when
 * doing operations on unrelated vnodes) and flushing the reclaimed inode
 * in the reclaim path itself is a non-starter.
 *
 * Caller must be in a transaction.
 */
void
hammer2_inode_run_sideq(hammer2_pfs_t *pmp, int doall)
{
        hammer2_xop_destroy_t *xop;
        hammer2_inode_sideq_t *ipul;
        hammer2_inode_t *ip;
        int error;

        /*
         * Nothing to do if sideq is empty or (if doall == 0) there just
         * aren't very many sideq entries.
         */
        if (TAILQ_EMPTY(&pmp->sideq))
                return;
        if (doall == 0) {
                if (pmp->sideq_count > (pmp->inum_count >> 3)) {
                        if (hammer2_debug & 0x0001) {
                                kprintf("hammer2: flush sideq %ld/%ld\n",
                                        pmp->sideq_count, pmp->inum_count);
                        }
                }
        }

        if (doall == 0 && pmp->sideq_count <= (pmp->inum_count >> 3))
                return;

        hammer2_spin_ex(&pmp->list_spin);
        while ((ipul = TAILQ_FIRST(&pmp->sideq)) != NULL) {
                TAILQ_REMOVE(&pmp->sideq, ipul, entry);
                --pmp->sideq_count;
                ip = ipul->ip;
                KKASSERT(ip->flags & HAMMER2_INODE_ONSIDEQ);
                atomic_clear_int(&ip->flags, HAMMER2_INODE_ONSIDEQ);
                hammer2_spin_unex(&pmp->list_spin);
                kfree(ipul, pmp->minode);

                hammer2_inode_lock(ip, 0);
                if (ip->flags & HAMMER2_INODE_ISDELETED) {
                        /*
                         * The inode has already been deleted.  This is a
                         * fairly rare circumstance.  For now we don't rock
                         * the boat and synchronize it normally.
                         */
                        hammer2_inode_chain_sync(ip);
                        hammer2_inode_chain_flush(ip);
                } else if (ip->flags & HAMMER2_INODE_ISUNLINKED) {
                        /*
                         * The inode was unlinked while open.  The inode must
                         * be deleted and destroyed.
                         */
                        xop = hammer2_xop_alloc(ip, HAMMER2_XOP_MODIFYING);
                        hammer2_xop_start(&xop->head,
                                          hammer2_inode_xop_destroy);
                        error = hammer2_xop_collect(&xop->head, 0);
                        /* XXX error handling */
                        hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
                } else {
                        /*
                         * The inode was dirty as-of the reclaim, requiring
                         * synchronization of ip->meta with its underlying
                         * chains.
                         */
                        hammer2_inode_chain_sync(ip);
                        hammer2_inode_chain_flush(ip);
                }

                hammer2_inode_unlock(ip);
                hammer2_inode_drop(ip);                 /* ipul ref */

                hammer2_spin_ex(&pmp->list_spin);

                /*
                 * If doall is 0 the original sideq_count was greater than
                 * 1/8 the inode count.  Add some hysteresis in the loop,
                 * don't stop flushing until sideq_count drops below 1/16.
                 */
                if (doall == 0 && pmp->sideq_count <= (pmp->inum_count >> 4)) {
                        if (hammer2_debug & 0x0001) {
                                kprintf("hammer2: flush sideq %ld/%ld (end)\n",
                                        pmp->sideq_count, pmp->inum_count);
                        }
                        break;
                }
        }
        hammer2_spin_unex(&pmp->list_spin);
}

/*
 * Helper to create a directory entry.
 */
void
hammer2_inode_xop_mkdirent(hammer2_thread_t *thr, hammer2_xop_t *arg)
{
        hammer2_xop_mkdirent_t *xop = &arg->xop_mkdirent;
        hammer2_chain_t *parent;
        hammer2_chain_t *chain;
        hammer2_key_t key_next;
        size_t data_len;
        int error;

        if (hammer2_debug & 0x0001)
                kprintf("dirent_create lhc %016jx clindex %d\n",
                        xop->lhc, thr->clindex);

        parent = hammer2_inode_chain(xop->head.ip1, thr->clindex,
                                     HAMMER2_RESOLVE_ALWAYS);
        if (parent == NULL) {
                error = HAMMER2_ERROR_EIO;
                chain = NULL;
                goto fail;
        }
        chain = hammer2_chain_lookup(&parent, &key_next,
                                     xop->lhc, xop->lhc,
                                     &error, 0);
        if (chain) {
                error = HAMMER2_ERROR_EEXIST;
                goto fail;
        }

        /*
         * We may be able to embed the directory entry directly in the
         * blockref.
         */
        if (xop->dirent.namlen <= sizeof(chain->bref.check.buf))
                data_len = 0;
        else
                data_len = HAMMER2_ALLOC_MIN;

        error = hammer2_chain_create(&parent, &chain,
                                     xop->head.ip1->pmp, HAMMER2_METH_DEFAULT,
                                     xop->lhc, 0,
                                     HAMMER2_BREF_TYPE_DIRENT,
                                     data_len,
                                     xop->head.mtid, 0, 0);
        if (error == 0) {
                /*
                 * WARNING: chain->data->buf is sized to chain->bytes,
                 *          do not use sizeof(chain->data->buf), which
                 *          will be much larger.
                 */
                error = hammer2_chain_modify(chain, xop->head.mtid, 0, 0);
                if (error == 0) {
                        chain->bref.embed.dirent = xop->dirent;
                        if (xop->dirent.namlen <= sizeof(chain->bref.check.buf))
                                bcopy(xop->head.name1, chain->bref.check.buf,
                                      xop->dirent.namlen);
                        else
                                bcopy(xop->head.name1, chain->data->buf,
                                      xop->dirent.namlen);
                }
        }
fail:
        if (parent) {
                hammer2_chain_unlock(parent);
                hammer2_chain_drop(parent);
        }
        hammer2_xop_feed(&xop->head, chain, thr->clindex, error);
        if (chain) {
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
        }
}

/*
 * Inode create helper (threaded, backend)
 *
 * Used by ncreate, nmknod, nsymlink, nmkdir.
 * Used by nlink and rename to create HARDLINK pointers.
 *
 * Frontend holds the parent directory ip locked exclusively.  We
 * create the inode and feed the exclusively locked chain to the
 * frontend.
 */
void
hammer2_inode_xop_create(hammer2_thread_t *thr, hammer2_xop_t *arg)
{
        hammer2_xop_create_t *xop = &arg->xop_create;
        hammer2_chain_t *parent;
        hammer2_chain_t *chain;
        hammer2_key_t key_next;
        int error;

        if (hammer2_debug & 0x0001)
                kprintf("inode_create lhc %016jx clindex %d\n",
                        xop->lhc, thr->clindex);

        parent = hammer2_inode_chain(xop->head.ip1, thr->clindex,
                                     HAMMER2_RESOLVE_ALWAYS);
        if (parent == NULL) {
                error = HAMMER2_ERROR_EIO;
                chain = NULL;
                goto fail;
        }
        chain = hammer2_chain_lookup(&parent, &key_next,
                                     xop->lhc, xop->lhc,
                                     &error, 0);
        if (chain) {
                error = HAMMER2_ERROR_EEXIST;
                goto fail;
        }

        error = hammer2_chain_create(&parent, &chain,
                                     xop->head.ip1->pmp, HAMMER2_METH_DEFAULT,
                                     xop->lhc, 0,
                                     HAMMER2_BREF_TYPE_INODE,
                                     HAMMER2_INODE_BYTES,
                                     xop->head.mtid, 0, xop->flags);
        if (error == 0) {
                error = hammer2_chain_modify(chain, xop->head.mtid, 0, 0);
                if (error == 0) {
                        chain->data->ipdata.meta = xop->meta;
                        if (xop->head.name1) {
                                bcopy(xop->head.name1,
                                      chain->data->ipdata.filename,
                                      xop->head.name1_len);
                                chain->data->ipdata.meta.name_len =
                                        xop->head.name1_len;
                        }
                        chain->data->ipdata.meta.name_key = xop->lhc;
                }
        }
fail:
        if (parent) {
                hammer2_chain_unlock(parent);
                hammer2_chain_drop(parent);
        }
        hammer2_xop_feed(&xop->head, chain, thr->clindex, error);
        if (chain) {
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
        }
}

/*
 * Inode delete helper (backend, threaded)
 *
 * Generally used by hammer2_run_sideq()
 */
void
hammer2_inode_xop_destroy(hammer2_thread_t *thr, hammer2_xop_t *arg)
{
        hammer2_xop_destroy_t *xop = &arg->xop_destroy;
        hammer2_pfs_t *pmp;
        hammer2_chain_t *parent;
        hammer2_chain_t *chain;
        hammer2_inode_t *ip;
        int error;

        /*
         * We need the precise parent chain to issue the deletion.
         */
        ip = xop->head.ip1;
        pmp = ip->pmp;

        chain = hammer2_inode_chain(ip, thr->clindex, HAMMER2_RESOLVE_ALWAYS);
        if (chain == NULL) {
                parent = NULL;
                error = HAMMER2_ERROR_EIO;
                goto done;
        }
        parent = hammer2_chain_getparent(chain, HAMMER2_RESOLVE_ALWAYS);
        if (parent == NULL) {
                error = HAMMER2_ERROR_EIO;
                goto done;
        }
        KKASSERT(chain->parent == parent);

        /*
         * We have the correct parent, we can issue the deletion.
         */
        hammer2_chain_delete(parent, chain, xop->head.mtid, 0);
        error = 0;
done:
        hammer2_xop_feed(&xop->head, NULL, thr->clindex, error);
        if (parent) {
                hammer2_chain_unlock(parent);
                hammer2_chain_drop(parent);
        }
        if (chain) {
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
        }
}

void
hammer2_inode_xop_unlinkall(hammer2_thread_t *thr, hammer2_xop_t *arg)
{
        hammer2_xop_unlinkall_t *xop = &arg->xop_unlinkall;
        hammer2_chain_t *parent;
        hammer2_chain_t *chain;
        hammer2_key_t key_next;
        int error;

        /*
         * We need the precise parent chain to issue the deletion.
         */
        parent = hammer2_inode_chain(xop->head.ip1, thr->clindex,
                                     HAMMER2_RESOLVE_ALWAYS);
        chain = NULL;
        if (parent == NULL) {
                error = 0;
                goto done;
        }
        chain = hammer2_chain_lookup(&parent, &key_next,
                                     xop->key_beg, xop->key_end,
                                     &error, HAMMER2_LOOKUP_ALWAYS);
        while (chain) {
                hammer2_chain_delete(parent, chain,
                                     xop->head.mtid, HAMMER2_DELETE_PERMANENT);
                hammer2_xop_feed(&xop->head, chain, thr->clindex, chain->error);
                /* depend on function to unlock the shared lock */
                chain = hammer2_chain_next(&parent, chain, &key_next,
                                           key_next, xop->key_end,
                                           &error,
                                           HAMMER2_LOOKUP_ALWAYS);
        }
done:
        if (error == 0)
                error = HAMMER2_ERROR_ENOENT;
        hammer2_xop_feed(&xop->head, NULL, thr->clindex, error);
        if (parent) {
                hammer2_chain_unlock(parent);
                hammer2_chain_drop(parent);
        }
        if (chain) {
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
        }
}

void
hammer2_inode_xop_connect(hammer2_thread_t *thr, hammer2_xop_t *arg)
{
        hammer2_xop_connect_t *xop = &arg->xop_connect;
        hammer2_inode_data_t *wipdata;
        hammer2_chain_t *parent;
        hammer2_chain_t *chain;
        hammer2_pfs_t *pmp;
        hammer2_key_t key_dummy;
        int error;

        /*
         * Get directory, then issue a lookup to prime the parent chain
         * for the create.  The lookup is expected to fail.
         */
        pmp = xop->head.ip1->pmp;
        parent = hammer2_inode_chain(xop->head.ip1, thr->clindex,
                                     HAMMER2_RESOLVE_ALWAYS);
        if (parent == NULL) {
                chain = NULL;
                error = HAMMER2_ERROR_EIO;
                goto fail;
        }
        chain = hammer2_chain_lookup(&parent, &key_dummy,
                                     xop->lhc, xop->lhc,
                                     &error, 0);
        if (chain) {
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
                chain = NULL;
                error = HAMMER2_ERROR_EEXIST;
                goto fail;
        }
        if (error)
                goto fail;

        /*
         * Adjust the filename in the inode, set the name key.
         *
         * NOTE: Frontend must also adjust ip2->meta on success, we can't
         *       do it here.
         */
        chain = hammer2_inode_chain(xop->head.ip2, thr->clindex,
                                    HAMMER2_RESOLVE_ALWAYS);
        error = hammer2_chain_modify(chain, xop->head.mtid, 0, 0);
        if (error)
                goto fail;

        wipdata = &chain->data->ipdata;

        hammer2_inode_modify(xop->head.ip2);
        if (xop->head.name1) {
                bzero(wipdata->filename, sizeof(wipdata->filename));
                bcopy(xop->head.name1, wipdata->filename, xop->head.name1_len);
                wipdata->meta.name_len = xop->head.name1_len;
        }
        wipdata->meta.name_key = xop->lhc;

        /*
         * Reconnect the chain to the new parent directory
         */
        error = hammer2_chain_create(&parent, &chain,
                                     pmp, HAMMER2_METH_DEFAULT,
                                     xop->lhc, 0,
                                     HAMMER2_BREF_TYPE_INODE,
                                     HAMMER2_INODE_BYTES,
                                     xop->head.mtid, 0, 0);

        /*
         * Feed result back.
         */
fail:
        hammer2_xop_feed(&xop->head, NULL, thr->clindex, error);
        if (parent) {
                hammer2_chain_unlock(parent);
                hammer2_chain_drop(parent);
        }
        if (chain) {
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
        }
}

/*
 * Synchronize the in-memory inode with the chain.  This does not flush
 * the chain to disk.  Instead, it makes front-end inode changes visible
 * in the chain topology, thus visible to the backend.  This is done in an
 * ad-hoc manner outside of the filesystem vfs_sync, and in a controlled
 * manner inside the vfs_sync.
 */
void
hammer2_inode_xop_chain_sync(hammer2_thread_t *thr, hammer2_xop_t *arg)
{
        hammer2_xop_fsync_t *xop = &arg->xop_fsync;
        hammer2_chain_t *parent;
        hammer2_chain_t *chain;
        int error;

        parent = hammer2_inode_chain(xop->head.ip1, thr->clindex,
                                     HAMMER2_RESOLVE_ALWAYS);
        chain = NULL;
        if (parent == NULL) {
                error = HAMMER2_ERROR_EIO;
                goto done;
        }
        if (parent->error) {
                error = parent->error;
                goto done;
        }

        error = 0;

        if ((xop->ipflags & HAMMER2_INODE_RESIZED) == 0) {
                /* osize must be ignored */
        } else if (xop->meta.size < xop->osize) {
                /*
                 * We must delete any chains beyond the EOF.  The chain
                 * straddling the EOF will be pending in the bioq.
                 */
                hammer2_key_t lbase;
                hammer2_key_t key_next;

                lbase = (xop->meta.size + HAMMER2_PBUFMASK64) &
                        ~HAMMER2_PBUFMASK64;
                chain = hammer2_chain_lookup(&parent, &key_next,
                                             lbase, HAMMER2_KEY_MAX,
                                             &error,
                                             HAMMER2_LOOKUP_NODATA |
                                             HAMMER2_LOOKUP_NODIRECT);
                while (chain) {
                        /*
                         * Degenerate embedded case, nothing to loop on
                         */
                        switch (chain->bref.type) {
                        case HAMMER2_BREF_TYPE_DIRENT:
                        case HAMMER2_BREF_TYPE_INODE:
                                KKASSERT(0);
                                break;
                        case HAMMER2_BREF_TYPE_DATA:
                                hammer2_chain_delete(parent, chain,
                                                     xop->head.mtid,
                                                     HAMMER2_DELETE_PERMANENT);
                                break;
                        }
                        chain = hammer2_chain_next(&parent, chain, &key_next,
                                                   key_next, HAMMER2_KEY_MAX,
                                                   &error,
                                                   HAMMER2_LOOKUP_NODATA |
                                                   HAMMER2_LOOKUP_NODIRECT);
                }

                /*
                 * Reset to point at inode for following code, if necessary.
                 */
                if (parent->bref.type != HAMMER2_BREF_TYPE_INODE) {
                        hammer2_chain_unlock(parent);
                        hammer2_chain_drop(parent);
                        parent = hammer2_inode_chain(xop->head.ip1,
                                                     thr->clindex,
                                                     HAMMER2_RESOLVE_ALWAYS);
                        kprintf("hammer2: TRUNCATE RESET on '%s'\n",
                                parent->data->ipdata.filename);
                }
        }

        /*
         * Sync the inode meta-data, potentially clear the blockset area
         * of direct data so it can be used for blockrefs.
         */
        if (error == 0) {
                error = hammer2_chain_modify(parent, xop->head.mtid, 0, 0);
                if (error == 0) {
                        parent->data->ipdata.meta = xop->meta;
                        if (xop->clear_directdata) {
                                bzero(&parent->data->ipdata.u.blockset,
                                      sizeof(parent->data->ipdata.u.blockset));
                        }
                }
        }
done:
        if (chain) {
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
        }
        if (parent) {
                hammer2_chain_unlock(parent);
                hammer2_chain_drop(parent);
        }
        hammer2_xop_feed(&xop->head, NULL, thr->clindex, error);
}