hammer2 - structuralize the cluster's chain array

[dragonfly.git] / sys / vfs / hammer2 / hammer2_vnops.c

/*
 * Copyright (c) 2011-2014 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>
 * by Daniel Flores (GSOC 2013 - mentored by Matthew Dillon, compression) 
 *
 * 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.
 */
/*
 * Kernel Filesystem interface
 *
 * NOTE! local ipdata pointers must be reloaded on any modifying operation
 *       to the inode as its underlying chain may have changed.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/fcntl.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/mountctl.h>
#include <sys/dirent.h>
#include <sys/uio.h>
#include <sys/objcache.h>
#include <sys/event.h>
#include <sys/file.h>
#include <vfs/fifofs/fifo.h>

#include "hammer2.h"
#include "hammer2_lz4.h"

#include "zlib/hammer2_zlib.h"

#define ZFOFFSET        (-2LL)

static int hammer2_read_file(hammer2_inode_t *ip, struct uio *uio,
                                int seqcount);
static int hammer2_write_file(hammer2_inode_t *ip, struct uio *uio,
                                int ioflag, int seqcount);
static void hammer2_extend_file(hammer2_inode_t *ip, hammer2_key_t nsize);
static void hammer2_truncate_file(hammer2_inode_t *ip, hammer2_key_t nsize);

struct objcache *cache_buffer_read;
struct objcache *cache_buffer_write;

/* 
 * Callback used in read path in case that a block is compressed with LZ4.
 */
static
void
hammer2_decompress_LZ4_callback(const char *data, u_int bytes, struct bio *bio)
{
        struct buf *bp;
        char *compressed_buffer;
        int compressed_size;
        int result;

        bp = bio->bio_buf;

#if 0
        if bio->bio_caller_info2.index &&
              bio->bio_caller_info1.uvalue32 !=
              crc32(bp->b_data, bp->b_bufsize) --- return error
#endif

        KKASSERT(bp->b_bufsize <= HAMMER2_PBUFSIZE);
        compressed_size = *(const int *)data;
        KKASSERT(compressed_size <= bytes - sizeof(int));

        compressed_buffer = objcache_get(cache_buffer_read, M_INTWAIT);
        result = LZ4_decompress_safe(__DECONST(char *, &data[sizeof(int)]),
                                     compressed_buffer,
                                     compressed_size,
                                     bp->b_bufsize);
        if (result < 0) {
                kprintf("READ PATH: Error during decompression."
                        "bio %016jx/%d\n",
                        (intmax_t)bio->bio_offset, bytes);
                /* make sure it isn't random garbage */
                bzero(compressed_buffer, bp->b_bufsize);
        }
        KKASSERT(result <= bp->b_bufsize);
        bcopy(compressed_buffer, bp->b_data, bp->b_bufsize);
        if (result < bp->b_bufsize)
                bzero(bp->b_data + result, bp->b_bufsize - result);
        objcache_put(cache_buffer_read, compressed_buffer);
        bp->b_resid = 0;
        bp->b_flags |= B_AGE;
}

/*
 * Callback used in read path in case that a block is compressed with ZLIB.
 * It is almost identical to LZ4 callback, so in theory they can be unified,
 * but we didn't want to make changes in bio structure for that.
 */
static
void
hammer2_decompress_ZLIB_callback(const char *data, u_int bytes, struct bio *bio)
{
        struct buf *bp;
        char *compressed_buffer;
        z_stream strm_decompress;
        int result;
        int ret;

        bp = bio->bio_buf;

        KKASSERT(bp->b_bufsize <= HAMMER2_PBUFSIZE);
        strm_decompress.avail_in = 0;
        strm_decompress.next_in = Z_NULL;

        ret = inflateInit(&strm_decompress);

        if (ret != Z_OK)
                kprintf("HAMMER2 ZLIB: Fatal error in inflateInit.\n");

        compressed_buffer = objcache_get(cache_buffer_read, M_INTWAIT);
        strm_decompress.next_in = __DECONST(char *, data);

        /* XXX supply proper size, subset of device bp */
        strm_decompress.avail_in = bytes;
        strm_decompress.next_out = compressed_buffer;
        strm_decompress.avail_out = bp->b_bufsize;

        ret = inflate(&strm_decompress, Z_FINISH);
        if (ret != Z_STREAM_END) {
                kprintf("HAMMER2 ZLIB: Fatar error during decompression.\n");
                bzero(compressed_buffer, bp->b_bufsize);
        }
        bcopy(compressed_buffer, bp->b_data, bp->b_bufsize);
        result = bp->b_bufsize - strm_decompress.avail_out;
        if (result < bp->b_bufsize)
                bzero(bp->b_data + result, strm_decompress.avail_out);
        objcache_put(cache_buffer_read, compressed_buffer);
        ret = inflateEnd(&strm_decompress);

        bp->b_resid = 0;
        bp->b_flags |= B_AGE;
}

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

/*
 * Last reference to a vnode is going away but it is still cached.
 */
static
int
hammer2_vop_inactive(struct vop_inactive_args *ap)
{
        hammer2_inode_t *ip;
        hammer2_cluster_t *cluster;
        struct vnode *vp;

        LOCKSTART;
        vp = ap->a_vp;
        ip = VTOI(vp);

        /*
         * Degenerate case
         */
        if (ip == NULL) {
                vrecycle(vp);
                LOCKSTOP;
                return (0);
        }

        /*
         * Detect updates to the embedded data which may be synchronized by
         * the strategy code.  Simply mark the inode modified so it gets
         * picked up by our normal flush.
         */
        cluster = hammer2_inode_lock_nex(ip, HAMMER2_RESOLVE_NEVER);
        KKASSERT(cluster);

        /*
         * Check for deleted inodes and recycle immediately.
         *
         * WARNING: nvtruncbuf() can only be safely called without the inode
         *          lock held due to the way our write thread works.
         */
        if (hammer2_cluster_isunlinked(cluster)) {
                hammer2_key_t lbase;
                int nblksize;

                nblksize = hammer2_calc_logical(ip, 0, &lbase, NULL);
                hammer2_inode_unlock_ex(ip, cluster);
                nvtruncbuf(vp, 0, nblksize, 0, 0);
                vrecycle(vp);
        } else {
                hammer2_inode_unlock_ex(ip, cluster);
        }
        LOCKSTOP;
        return (0);
}

/*
 * Reclaim a vnode so that it can be reused; after the inode is
 * disassociated, the filesystem must manage it alone.
 */
static
int
hammer2_vop_reclaim(struct vop_reclaim_args *ap)
{
        hammer2_cluster_t *cluster;
        hammer2_inode_t *ip;
        hammer2_pfsmount_t *pmp;
        struct vnode *vp;

        LOCKSTART;
        vp = ap->a_vp;
        ip = VTOI(vp);
        if (ip == NULL) {
                LOCKSTOP;
                return(0);
        }

        /*
         * Inode must be locked for reclaim.
         */
        pmp = ip->pmp;
        cluster = hammer2_inode_lock_nex(ip, HAMMER2_RESOLVE_NEVER);

        /*
         * The final close of a deleted file or directory marks it for
         * destruction.  The DELETED flag allows the flusher to shortcut
         * any modified blocks still unflushed (that is, just ignore them).
         *
         * HAMMER2 usually does not try to optimize the freemap by returning
         * deleted blocks to it as it does not usually know how many snapshots
         * might be referencing portions of the file/dir.
         */
        vp->v_data = NULL;
        ip->vp = NULL;

        /*
         * NOTE! We do not attempt to flush chains here, flushing is
         *       really fragile and could also deadlock.
         */
        vclrisdirty(vp);

        /*
         * A reclaim can occur at any time so we cannot safely start a
         * transaction to handle reclamation of unlinked files.  Instead,
         * the ip is left with a reference and placed on a linked list and
         * handled later on.
         */
        if (hammer2_cluster_isunlinked(cluster)) {
                hammer2_inode_unlink_t *ipul;

                ipul = kmalloc(sizeof(*ipul), pmp->minode, M_WAITOK | M_ZERO);
                ipul->ip = ip;

                hammer2_spin_ex(&pmp->list_spin);
                TAILQ_INSERT_TAIL(&pmp->unlinkq, ipul, entry);
                hammer2_spin_unex(&pmp->list_spin);
                hammer2_inode_unlock_ex(ip, cluster);   /* unlock */
                /* retain ref from vp for ipul */
        } else {
                hammer2_inode_unlock_ex(ip, cluster);   /* unlock */
                hammer2_inode_drop(ip);                 /* vp ref */
        }
        /* cluster no longer referenced */
        /* cluster = NULL; not needed */

        /*
         * XXX handle background sync when ip dirty, kernel will no longer
         * notify us regarding this inode because there is no longer a
         * vnode attached to it.
         */

        LOCKSTOP;
        return (0);
}

static
int
hammer2_vop_fsync(struct vop_fsync_args *ap)
{
        hammer2_inode_t *ip;
        hammer2_trans_t trans;
        hammer2_cluster_t *cluster;
        struct vnode *vp;

        LOCKSTART;
        vp = ap->a_vp;
        ip = VTOI(vp);

#if 0
        /* XXX can't do this yet */
        hammer2_trans_init(&trans, ip->pmp, HAMMER2_TRANS_ISFLUSH);
        vfsync(vp, ap->a_waitfor, 1, NULL, NULL);
#endif
        hammer2_trans_init(&trans, ip->pmp, 0);
        vfsync(vp, ap->a_waitfor, 1, NULL, NULL);

        /*
         * Calling chain_flush here creates a lot of duplicative
         * COW operations due to non-optimal vnode ordering.
         *
         * Only do it for an actual fsync() syscall.  The other forms
         * which call this function will eventually call chain_flush
         * on the volume root as a catch-all, which is far more optimal.
         */
        cluster = hammer2_inode_lock_ex(ip);
        atomic_clear_int(&ip->flags, HAMMER2_INODE_MODIFIED);
        vclrisdirty(vp);
        if (ip->flags & (HAMMER2_INODE_RESIZED|HAMMER2_INODE_MTIME))
                hammer2_inode_fsync(&trans, ip, cluster);

#if 0
        /*
         * XXX creates discontinuity w/modify_tid
         */
        if (ap->a_flags & VOP_FSYNC_SYSCALL) {
                hammer2_flush(&trans, cluster);
        }
#endif
        hammer2_inode_unlock_ex(ip, cluster);
        hammer2_trans_done(&trans);

        LOCKSTOP;
        return (0);
}

static
int
hammer2_vop_access(struct vop_access_args *ap)
{
        hammer2_inode_t *ip = VTOI(ap->a_vp);
        const hammer2_inode_data_t *ripdata;
        hammer2_cluster_t *cluster;
        uid_t uid;
        gid_t gid;
        int error;

        LOCKSTART;
        cluster = hammer2_inode_lock_sh(ip);
        ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
        uid = hammer2_to_unix_xid(&ripdata->uid);
        gid = hammer2_to_unix_xid(&ripdata->gid);
        error = vop_helper_access(ap, uid, gid, ripdata->mode, ripdata->uflags);
        hammer2_inode_unlock_sh(ip, cluster);

        LOCKSTOP;
        return (error);
}

static
int
hammer2_vop_getattr(struct vop_getattr_args *ap)
{
        const hammer2_inode_data_t *ripdata;
        hammer2_cluster_t *cluster;
        hammer2_pfsmount_t *pmp;
        hammer2_inode_t *ip;
        struct vnode *vp;
        struct vattr *vap;

        LOCKSTART;
        vp = ap->a_vp;
        vap = ap->a_vap;

        ip = VTOI(vp);
        pmp = ip->pmp;

        cluster = hammer2_inode_lock_sh(ip);
        ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
        KKASSERT(hammer2_cluster_type(cluster) == HAMMER2_BREF_TYPE_INODE);

        vap->va_fsid = pmp->mp->mnt_stat.f_fsid.val[0];
        vap->va_fileid = ripdata->inum;
        vap->va_mode = ripdata->mode;
        vap->va_nlink = ripdata->nlinks;
        vap->va_uid = hammer2_to_unix_xid(&ripdata->uid);
        vap->va_gid = hammer2_to_unix_xid(&ripdata->gid);
        vap->va_rmajor = 0;
        vap->va_rminor = 0;
        vap->va_size = ip->size;        /* protected by shared lock */
        vap->va_blocksize = HAMMER2_PBUFSIZE;
        vap->va_flags = ripdata->uflags;
        hammer2_time_to_timespec(ripdata->ctime, &vap->va_ctime);
        hammer2_time_to_timespec(ripdata->mtime, &vap->va_mtime);
        hammer2_time_to_timespec(ripdata->mtime, &vap->va_atime);
        vap->va_gen = 1;
        vap->va_bytes = vap->va_size;   /* XXX */
        vap->va_type = hammer2_get_vtype(ripdata);
        vap->va_filerev = 0;
        vap->va_uid_uuid = ripdata->uid;
        vap->va_gid_uuid = ripdata->gid;
        vap->va_vaflags = VA_UID_UUID_VALID | VA_GID_UUID_VALID |
                          VA_FSID_UUID_VALID;

        hammer2_inode_unlock_sh(ip, cluster);

        LOCKSTOP;
        return (0);
}

static
int
hammer2_vop_setattr(struct vop_setattr_args *ap)
{
        const hammer2_inode_data_t *ripdata;
        hammer2_inode_data_t *wipdata;
        hammer2_inode_t *ip;
        hammer2_cluster_t *cluster;
        hammer2_trans_t trans;
        struct vnode *vp;
        struct vattr *vap;
        int error;
        int kflags = 0;
        int domtime = 0;
        int dosync = 0;
        uint64_t ctime;

        LOCKSTART;
        vp = ap->a_vp;
        vap = ap->a_vap;
        hammer2_update_time(&ctime);

        ip = VTOI(vp);

        if (ip->pmp->ronly) {
                LOCKSTOP;
                return(EROFS);
        }

        hammer2_pfs_memory_wait(ip->pmp);
        hammer2_trans_init(&trans, ip->pmp, 0);
        cluster = hammer2_inode_lock_ex(ip);
        ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
        error = 0;

        if (vap->va_flags != VNOVAL) {
                u_int32_t flags;

                flags = ripdata->uflags;
                error = vop_helper_setattr_flags(&flags, vap->va_flags,
                                         hammer2_to_unix_xid(&ripdata->uid),
                                         ap->a_cred);
                if (error == 0) {
                        if (ripdata->uflags != flags) {
                                wipdata = hammer2_cluster_modify_ip(&trans, ip,
                                                                    cluster, 0);
                                wipdata->uflags = flags;
                                wipdata->ctime = ctime;
                                kflags |= NOTE_ATTRIB;
                                dosync = 1;
                                ripdata = wipdata;
                        }
                        if (ripdata->uflags & (IMMUTABLE | APPEND)) {
                                error = 0;
                                goto done;
                        }
                }
                goto done;
        }
        if (ripdata->uflags & (IMMUTABLE | APPEND)) {
                error = EPERM;
                goto done;
        }
        if (vap->va_uid != (uid_t)VNOVAL || vap->va_gid != (gid_t)VNOVAL) {
                mode_t cur_mode = ripdata->mode;
                uid_t cur_uid = hammer2_to_unix_xid(&ripdata->uid);
                gid_t cur_gid = hammer2_to_unix_xid(&ripdata->gid);
                uuid_t uuid_uid;
                uuid_t uuid_gid;

                error = vop_helper_chown(ap->a_vp, vap->va_uid, vap->va_gid,
                                         ap->a_cred,
                                         &cur_uid, &cur_gid, &cur_mode);
                if (error == 0) {
                        hammer2_guid_to_uuid(&uuid_uid, cur_uid);
                        hammer2_guid_to_uuid(&uuid_gid, cur_gid);
                        if (bcmp(&uuid_uid, &ripdata->uid, sizeof(uuid_uid)) ||
                            bcmp(&uuid_gid, &ripdata->gid, sizeof(uuid_gid)) ||
                            ripdata->mode != cur_mode
                        ) {
                                wipdata = hammer2_cluster_modify_ip(&trans, ip,
                                                                    cluster, 0);
                                wipdata->uid = uuid_uid;
                                wipdata->gid = uuid_gid;
                                wipdata->mode = cur_mode;
                                wipdata->ctime = ctime;
                                dosync = 1;
                                ripdata = wipdata;
                        }
                        kflags |= NOTE_ATTRIB;
                }
        }

        /*
         * Resize the file
         */
        if (vap->va_size != VNOVAL && ip->size != vap->va_size) {
                switch(vp->v_type) {
                case VREG:
                        if (vap->va_size == ip->size)
                                break;
                        hammer2_inode_unlock_ex(ip, cluster);
                        if (vap->va_size < ip->size) {
                                hammer2_truncate_file(ip, vap->va_size);
                        } else {
                                hammer2_extend_file(ip, vap->va_size);
                        }
                        cluster = hammer2_inode_lock_ex(ip);
                        /* RELOAD */
                        ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
                        domtime = 1;
                        break;
                default:
                        error = EINVAL;
                        goto done;
                }
        }
#if 0
        /* atime not supported */
        if (vap->va_atime.tv_sec != VNOVAL) {
                wipdata = hammer2_cluster_modify_ip(&trans, ip, cluster, 0);
                wipdata->atime = hammer2_timespec_to_time(&vap->va_atime);
                kflags |= NOTE_ATTRIB;
                dosync = 1;
                ripdata = wipdata;
        }
#endif
        if (vap->va_mtime.tv_sec != VNOVAL) {
                wipdata = hammer2_cluster_modify_ip(&trans, ip, cluster, 0);
                wipdata->mtime = hammer2_timespec_to_time(&vap->va_mtime);
                kflags |= NOTE_ATTRIB;
                domtime = 0;
                dosync = 1;
                ripdata = wipdata;
        }
        if (vap->va_mode != (mode_t)VNOVAL) {
                mode_t cur_mode = ripdata->mode;
                uid_t cur_uid = hammer2_to_unix_xid(&ripdata->uid);
                gid_t cur_gid = hammer2_to_unix_xid(&ripdata->gid);

                error = vop_helper_chmod(ap->a_vp, vap->va_mode, ap->a_cred,
                                         cur_uid, cur_gid, &cur_mode);
                if (error == 0 && ripdata->mode != cur_mode) {
                        wipdata = hammer2_cluster_modify_ip(&trans, ip,
                                                            cluster, 0);
                        wipdata->mode = cur_mode;
                        wipdata->ctime = ctime;
                        kflags |= NOTE_ATTRIB;
                        dosync = 1;
                        ripdata = wipdata;
                }
        }

        /*
         * If a truncation occurred we must call inode_fsync() now in order
         * to trim the related data chains, otherwise a later expansion can
         * cause havoc.
         */
        if (dosync) {
                hammer2_cluster_modsync(cluster);
                dosync = 0;
        }
        hammer2_inode_fsync(&trans, ip, cluster);

        /*
         * Cleanup.  If domtime is set an additional inode modification
         * must be flagged.  All other modifications will have already
         * set INODE_MODIFIED and called vsetisdirty().
         */
done:
        if (domtime) {
                atomic_set_int(&ip->flags, HAMMER2_INODE_MODIFIED |
                                           HAMMER2_INODE_MTIME);
                vsetisdirty(ip->vp);
        }
        if (dosync)
                hammer2_cluster_modsync(cluster);
        hammer2_inode_unlock_ex(ip, cluster);
        hammer2_trans_done(&trans);
        hammer2_knote(ip->vp, kflags);

        LOCKSTOP;
        return (error);
}

static
int
hammer2_vop_readdir(struct vop_readdir_args *ap)
{
        const hammer2_inode_data_t *ripdata;
        hammer2_inode_t *ip;
        hammer2_inode_t *xip;
        hammer2_cluster_t *cparent;
        hammer2_cluster_t *cluster;
        hammer2_cluster_t *xcluster;
        hammer2_blockref_t bref;
        hammer2_tid_t inum;
        hammer2_key_t key_next;
        hammer2_key_t lkey;
        struct uio *uio;
        off_t *cookies;
        off_t saveoff;
        int cookie_index;
        int ncookies;
        int error;
        int dtype;
        int ddflag;
        int r;

        LOCKSTART;
        ip = VTOI(ap->a_vp);
        uio = ap->a_uio;
        saveoff = uio->uio_offset;

        /*
         * Setup cookies directory entry cookies if requested
         */
        if (ap->a_ncookies) {
                ncookies = uio->uio_resid / 16 + 1;
                if (ncookies > 1024)
                        ncookies = 1024;
                cookies = kmalloc(ncookies * sizeof(off_t), M_TEMP, M_WAITOK);
        } else {
                ncookies = -1;
                cookies = NULL;
        }
        cookie_index = 0;

        cparent = hammer2_inode_lock_sh(ip);
        ripdata = &hammer2_cluster_rdata(cparent)->ipdata;

        /*
         * Handle artificial entries.  To ensure that only positive 64 bit
         * quantities are returned to userland we always strip off bit 63.
         * The hash code is designed such that codes 0x0000-0x7FFF are not
         * used, allowing us to use these codes for articial entries.
         *
         * Entry 0 is used for '.' and entry 1 is used for '..'.  Do not
         * allow '..' to cross the mount point into (e.g.) the super-root.
         */
        error = 0;
        cluster = (void *)(intptr_t)-1; /* non-NULL for early goto done case */

        if (saveoff == 0) {
                inum = ripdata->inum & HAMMER2_DIRHASH_USERMSK;
                r = vop_write_dirent(&error, uio, inum, DT_DIR, 1, ".");
                if (r)
                        goto done;
                if (cookies)
                        cookies[cookie_index] = saveoff;
                ++saveoff;
                ++cookie_index;
                if (cookie_index == ncookies)
                        goto done;
        }

        if (saveoff == 1) {
                /*
                 * Be careful with lockorder when accessing ".."
                 *
                 * (ip is the current dir. xip is the parent dir).
                 */
                inum = ripdata->inum & HAMMER2_DIRHASH_USERMSK;
                while (ip->pip != NULL && ip != ip->pmp->iroot) {
                        xip = ip->pip;
                        hammer2_inode_ref(xip);
                        hammer2_inode_unlock_sh(ip, cparent);
                        xcluster = hammer2_inode_lock_sh(xip);
                        cparent = hammer2_inode_lock_sh(ip);
                        hammer2_inode_drop(xip);
                        ripdata = &hammer2_cluster_rdata(cparent)->ipdata;
                        if (xip == ip->pip) {
                                inum = hammer2_cluster_rdata(xcluster)->
                                        ipdata.inum & HAMMER2_DIRHASH_USERMSK;
                                hammer2_inode_unlock_sh(xip, xcluster);
                                break;
                        }
                        hammer2_inode_unlock_sh(xip, xcluster);
                }
                r = vop_write_dirent(&error, uio, inum, DT_DIR, 2, "..");
                if (r)
                        goto done;
                if (cookies)
                        cookies[cookie_index] = saveoff;
                ++saveoff;
                ++cookie_index;
                if (cookie_index == ncookies)
                        goto done;
        }

        lkey = saveoff | HAMMER2_DIRHASH_VISIBLE;
        if (hammer2_debug & 0x0020)
                kprintf("readdir: lkey %016jx\n", lkey);

        /*
         * parent is the inode cluster, already locked for us.  Don't
         * double lock shared locks as this will screw up upgrades.
         */
        if (error) {
                goto done;
        }
        cluster = hammer2_cluster_lookup(cparent, &key_next, lkey, lkey,
                                     HAMMER2_LOOKUP_SHARED, &ddflag);
        if (cluster == NULL) {
                cluster = hammer2_cluster_lookup(cparent, &key_next,
                                             lkey, (hammer2_key_t)-1,
                                             HAMMER2_LOOKUP_SHARED, &ddflag);
        }
        if (cluster)
                hammer2_cluster_bref(cluster, &bref);
        while (cluster) {
                if (hammer2_debug & 0x0020)
                        kprintf("readdir: p=%p chain=%p %016jx (next %016jx)\n",
                                cparent->focus, cluster->focus,
                                bref.key, key_next);

                if (bref.type == HAMMER2_BREF_TYPE_INODE) {
                        ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
                        dtype = hammer2_get_dtype(ripdata);
                        saveoff = bref.key & HAMMER2_DIRHASH_USERMSK;
                        r = vop_write_dirent(&error, uio,
                                             ripdata->inum &
                                              HAMMER2_DIRHASH_USERMSK,
                                             dtype,
                                             ripdata->name_len,
                                             ripdata->filename);
                        if (r)
                                break;
                        if (cookies)
                                cookies[cookie_index] = saveoff;
                        ++cookie_index;
                } else {
                        /* XXX chain error */
                        kprintf("bad chain type readdir %d\n", bref.type);
                }

                /*
                 * Keys may not be returned in order so once we have a
                 * placemarker (cluster) the scan must allow the full range
                 * or some entries will be missed.
                 */
                cluster = hammer2_cluster_next(cparent, cluster, &key_next,
                                               key_next, (hammer2_key_t)-1,
                                               HAMMER2_LOOKUP_SHARED);
                if (cluster) {
                        hammer2_cluster_bref(cluster, &bref);
                        saveoff = (bref.key & HAMMER2_DIRHASH_USERMSK) + 1;
                } else {
                        saveoff = (hammer2_key_t)-1;
                }
                if (cookie_index == ncookies)
                        break;
        }
        if (cluster)
                hammer2_cluster_unlock(cluster);
done:
        hammer2_inode_unlock_sh(ip, cparent);
        if (ap->a_eofflag)
                *ap->a_eofflag = (cluster == NULL);
        if (hammer2_debug & 0x0020)
                kprintf("readdir: done at %016jx\n", saveoff);
        uio->uio_offset = saveoff & ~HAMMER2_DIRHASH_VISIBLE;
        if (error && cookie_index == 0) {
                if (cookies) {
                        kfree(cookies, M_TEMP);
                        *ap->a_ncookies = 0;
                        *ap->a_cookies = NULL;
                }
        } else {
                if (cookies) {
                        *ap->a_ncookies = cookie_index;
                        *ap->a_cookies = cookies;
                }
        }
        LOCKSTOP;
        return (error);
}

/*
 * hammer2_vop_readlink { vp, uio, cred }
 */
static
int
hammer2_vop_readlink(struct vop_readlink_args *ap)
{
        struct vnode *vp;
        hammer2_inode_t *ip;
        int error;

        vp = ap->a_vp;
        if (vp->v_type != VLNK)
                return (EINVAL);
        ip = VTOI(vp);

        error = hammer2_read_file(ip, ap->a_uio, 0);
        return (error);
}

static
int
hammer2_vop_read(struct vop_read_args *ap)
{
        struct vnode *vp;
        hammer2_inode_t *ip;
        struct uio *uio;
        int error;
        int seqcount;
        int bigread;

        /*
         * Read operations supported on this vnode?
         */
        vp = ap->a_vp;
        if (vp->v_type != VREG)
                return (EINVAL);

        /*
         * Misc
         */
        ip = VTOI(vp);
        uio = ap->a_uio;
        error = 0;

        seqcount = ap->a_ioflag >> 16;
        bigread = (uio->uio_resid > 100 * 1024 * 1024);

        error = hammer2_read_file(ip, uio, seqcount);
        return (error);
}

static
int
hammer2_vop_write(struct vop_write_args *ap)
{
        hammer2_inode_t *ip;
        hammer2_trans_t trans;
        thread_t td;
        struct vnode *vp;
        struct uio *uio;
        int error;
        int seqcount;
        int bigwrite;

        /*
         * Read operations supported on this vnode?
         */
        vp = ap->a_vp;
        if (vp->v_type != VREG)
                return (EINVAL);

        /*
         * Misc
         */
        ip = VTOI(vp);
        uio = ap->a_uio;
        error = 0;
        if (ip->pmp->ronly) {
                return (EROFS);
        }

        seqcount = ap->a_ioflag >> 16;
        bigwrite = (uio->uio_resid > 100 * 1024 * 1024);

        /*
         * Check resource limit
         */
        if (uio->uio_resid > 0 && (td = uio->uio_td) != NULL && td->td_proc &&
            uio->uio_offset + uio->uio_resid >
             td->td_proc->p_rlimit[RLIMIT_FSIZE].rlim_cur) {
                lwpsignal(td->td_proc, td->td_lwp, SIGXFSZ);
                return (EFBIG);
        }

        bigwrite = (uio->uio_resid > 100 * 1024 * 1024);

        /*
         * The transaction interlocks against flushes initiations
         * (note: but will run concurrently with the actual flush).
         */
        hammer2_trans_init(&trans, ip->pmp, 0);
        error = hammer2_write_file(ip, uio, ap->a_ioflag, seqcount);
        hammer2_trans_done(&trans);

        return (error);
}

/*
 * Perform read operations on a file or symlink given an UNLOCKED
 * inode and uio.
 *
 * The passed ip is not locked.
 */
static
int
hammer2_read_file(hammer2_inode_t *ip, struct uio *uio, int seqcount)
{
        hammer2_off_t size;
        struct buf *bp;
        int error;

        error = 0;

        /*
         * UIO read loop.
         *
         * WARNING! Assumes that the kernel interlocks size changes at the
         *          vnode level.
         */
        hammer2_mtx_sh(&ip->lock);
        size = ip->size;
        hammer2_mtx_unlock(&ip->lock);

        while (uio->uio_resid > 0 && uio->uio_offset < size) {
                hammer2_key_t lbase;
                hammer2_key_t leof;
                int lblksize;
                int loff;
                int n;

                lblksize = hammer2_calc_logical(ip, uio->uio_offset,
                                                &lbase, &leof);

                error = cluster_read(ip->vp, leof, lbase, lblksize,
                                     uio->uio_resid, seqcount * BKVASIZE,
                                     &bp);

                if (error)
                        break;
                loff = (int)(uio->uio_offset - lbase);
                n = lblksize - loff;
                if (n > uio->uio_resid)
                        n = uio->uio_resid;
                if (n > size - uio->uio_offset)
                        n = (int)(size - uio->uio_offset);
                bp->b_flags |= B_AGE;
                uiomove((char *)bp->b_data + loff, n, uio);
                bqrelse(bp);
        }
        return (error);
}

/*
 * Write to the file represented by the inode via the logical buffer cache.
 * The inode may represent a regular file or a symlink.
 *
 * The inode must not be locked.
 */
static
int
hammer2_write_file(hammer2_inode_t *ip,
                   struct uio *uio, int ioflag, int seqcount)
{
        hammer2_key_t old_eof;
        hammer2_key_t new_eof;
        struct buf *bp;
        int kflags;
        int error;
        int modified;

        /*
         * Setup if append
         *
         * WARNING! Assumes that the kernel interlocks size changes at the
         *          vnode level.
         */
        hammer2_mtx_ex(&ip->lock);
        if (ioflag & IO_APPEND)
                uio->uio_offset = ip->size;
        old_eof = ip->size;
        hammer2_mtx_unlock(&ip->lock);

        /*
         * Extend the file if necessary.  If the write fails at some point
         * we will truncate it back down to cover as much as we were able
         * to write.
         *
         * Doing this now makes it easier to calculate buffer sizes in
         * the loop.
         */
        kflags = 0;
        error = 0;
        modified = 0;

        if (uio->uio_offset + uio->uio_resid > old_eof) {
                new_eof = uio->uio_offset + uio->uio_resid;
                modified = 1;
                hammer2_extend_file(ip, new_eof);
                kflags |= NOTE_EXTEND;
        } else {
                new_eof = old_eof;
        }
        
        /*
         * UIO write loop
         */
        while (uio->uio_resid > 0) {
                hammer2_key_t lbase;
                int trivial;
                int endofblk;
                int lblksize;
                int loff;
                int n;

                /*
                 * Don't allow the buffer build to blow out the buffer
                 * cache.
                 */
                if ((ioflag & IO_RECURSE) == 0)
                        bwillwrite(HAMMER2_PBUFSIZE);

                /*
                 * This nominally tells us how much we can cluster and
                 * what the logical buffer size needs to be.  Currently
                 * we don't try to cluster the write and just handle one
                 * block at a time.
                 */
                lblksize = hammer2_calc_logical(ip, uio->uio_offset,
                                                &lbase, NULL);
                loff = (int)(uio->uio_offset - lbase);
                
                KKASSERT(lblksize <= 65536);

                /*
                 * Calculate bytes to copy this transfer and whether the
                 * copy completely covers the buffer or not.
                 */
                trivial = 0;
                n = lblksize - loff;
                if (n > uio->uio_resid) {
                        n = uio->uio_resid;
                        if (loff == lbase && uio->uio_offset + n == new_eof)
                                trivial = 1;
                        endofblk = 0;
                } else {
                        if (loff == 0)
                                trivial = 1;
                        endofblk = 1;
                }

                /*
                 * Get the buffer
                 */
                if (uio->uio_segflg == UIO_NOCOPY) {
                        /*
                         * Issuing a write with the same data backing the
                         * buffer.  Instantiate the buffer to collect the
                         * backing vm pages, then read-in any missing bits.
                         *
                         * This case is used by vop_stdputpages().
                         */
                        bp = getblk(ip->vp, lbase, lblksize, GETBLK_BHEAVY, 0);
                        if ((bp->b_flags & B_CACHE) == 0) {
                                bqrelse(bp);
                                error = bread(ip->vp, lbase, lblksize, &bp);
                        }
                } else if (trivial) {
                        /*
                         * Even though we are entirely overwriting the buffer
                         * we may still have to zero it out to avoid a
                         * mmap/write visibility issue.
                         */
                        bp = getblk(ip->vp, lbase, lblksize, GETBLK_BHEAVY, 0);
                        if ((bp->b_flags & B_CACHE) == 0)
                                vfs_bio_clrbuf(bp);
                } else {
                        /*
                         * Partial overwrite, read in any missing bits then
                         * replace the portion being written.
                         *
                         * (The strategy code will detect zero-fill physical
                         * blocks for this case).
                         */
                        error = bread(ip->vp, lbase, lblksize, &bp);
                        if (error == 0)
                                bheavy(bp);
                }

                if (error) {
                        brelse(bp);
                        break;
                }

                /*
                 * Ok, copy the data in
                 */
                error = uiomove(bp->b_data + loff, n, uio);
                kflags |= NOTE_WRITE;
                modified = 1;
                if (error) {
                        brelse(bp);
                        break;
                }

                /*
                 * WARNING: Pageout daemon will issue UIO_NOCOPY writes
                 *          with IO_SYNC or IO_ASYNC set.  These writes
                 *          must be handled as the pageout daemon expects.
                 */
                if (ioflag & IO_SYNC) {
                        bwrite(bp);
                } else if ((ioflag & IO_DIRECT) && endofblk) {
                        bawrite(bp);
                } else if (ioflag & IO_ASYNC) {
                        bawrite(bp);
                } else {
                        bdwrite(bp);
                }
        }

        /*
         * Cleanup.  If we extended the file EOF but failed to write through
         * the entire write is a failure and we have to back-up.
         */
        if (error && new_eof != old_eof) {
                hammer2_truncate_file(ip, old_eof);
        } else if (modified) {
                hammer2_mtx_ex(&ip->lock);
                hammer2_update_time(&ip->mtime);
                atomic_set_int(&ip->flags, HAMMER2_INODE_MTIME);
                hammer2_mtx_unlock(&ip->lock);
        }
        atomic_set_int(&ip->flags, HAMMER2_INODE_MODIFIED);
        hammer2_knote(ip->vp, kflags);
        vsetisdirty(ip->vp);

        return error;
}

/*
 * Truncate the size of a file.  The inode must not be locked.
 *
 * NOTE:    Caller handles setting HAMMER2_INODE_MODIFIED
 *
 * WARNING: nvtruncbuf() can only be safely called without the inode lock
 *          held due to the way our write thread works.
 *
 * WARNING! Assumes that the kernel interlocks size changes at the
 *          vnode level.
 */
static
void
hammer2_truncate_file(hammer2_inode_t *ip, hammer2_key_t nsize)
{
        hammer2_key_t lbase;
        int nblksize;

        LOCKSTART;
        if (ip->vp) {
                nblksize = hammer2_calc_logical(ip, nsize, &lbase, NULL);
                nvtruncbuf(ip->vp, nsize,
                           nblksize, (int)nsize & (nblksize - 1),
                           0);
        }
        hammer2_mtx_ex(&ip->lock);
        ip->size = nsize;
        atomic_set_int(&ip->flags, HAMMER2_INODE_RESIZED);
        hammer2_mtx_unlock(&ip->lock);
        LOCKSTOP;
}

/*
 * Extend the size of a file.  The inode must not be locked.
 *
 * WARNING! Assumes that the kernel interlocks size changes at the
 *          vnode level.
 *
 * NOTE: Caller handles setting HAMMER2_INODE_MODIFIED
 */
static
void
hammer2_extend_file(hammer2_inode_t *ip, hammer2_key_t nsize)
{
        hammer2_key_t lbase;
        hammer2_key_t osize;
        int oblksize;
        int nblksize;

        LOCKSTART;
        hammer2_mtx_ex(&ip->lock);
        osize = ip->size;
        ip->size = nsize;
        hammer2_mtx_unlock(&ip->lock);

        if (ip->vp) {
                oblksize = hammer2_calc_logical(ip, osize, &lbase, NULL);
                nblksize = hammer2_calc_logical(ip, nsize, &lbase, NULL);
                nvextendbuf(ip->vp,
                            osize, nsize,
                            oblksize, nblksize,
                            -1, -1, 0);
        }
        atomic_set_int(&ip->flags, HAMMER2_INODE_RESIZED);
        LOCKSTOP;
}

static
int
hammer2_vop_nresolve(struct vop_nresolve_args *ap)
{
        hammer2_inode_t *ip;
        hammer2_inode_t *dip;
        hammer2_cluster_t *cparent;
        hammer2_cluster_t *cluster;
        const hammer2_inode_data_t *ripdata;
        hammer2_key_t key_next;
        hammer2_key_t lhc;
        struct namecache *ncp;
        const uint8_t *name;
        size_t name_len;
        int error = 0;
        int ddflag;
        struct vnode *vp;

        LOCKSTART;
        dip = VTOI(ap->a_dvp);
        ncp = ap->a_nch->ncp;
        name = ncp->nc_name;
        name_len = ncp->nc_nlen;
        lhc = hammer2_dirhash(name, name_len);

        /*
         * Note: In DragonFly the kernel handles '.' and '..'.
         */
        cparent = hammer2_inode_lock_sh(dip);
        cluster = hammer2_cluster_lookup(cparent, &key_next,
                                         lhc, lhc + HAMMER2_DIRHASH_LOMASK,
                                         HAMMER2_LOOKUP_SHARED, &ddflag);
        while (cluster) {
                if (hammer2_cluster_type(cluster) == HAMMER2_BREF_TYPE_INODE) {
                        ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
                        if (ripdata->name_len == name_len &&
                            bcmp(ripdata->filename, name, name_len) == 0) {
                                break;
                        }
                }
                cluster = hammer2_cluster_next(cparent, cluster, &key_next,
                                               key_next,
                                               lhc + HAMMER2_DIRHASH_LOMASK,
                                               HAMMER2_LOOKUP_SHARED);
        }
        hammer2_inode_unlock_sh(dip, cparent);

        /*
         * Resolve hardlink entries before acquiring the inode.
         */
        if (cluster) {
                ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
                if (ripdata->type == HAMMER2_OBJTYPE_HARDLINK) {
                        hammer2_tid_t inum = ripdata->inum;
                        error = hammer2_hardlink_find(dip, NULL, cluster);
                        if (error) {
                                kprintf("hammer2: unable to find hardlink "
                                        "0x%016jx\n", inum);
                                hammer2_cluster_unlock(cluster);
                                LOCKSTOP;
                                return error;
                        }
                }
        }

        /*
         * nresolve needs to resolve hardlinks, the original cluster is not
         * sufficient.
         */
        if (cluster) {
                ip = hammer2_inode_get(dip->pmp, dip, cluster);
                ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
                if (ripdata->type == HAMMER2_OBJTYPE_HARDLINK) {
                        kprintf("nresolve: fixup hardlink\n");
                        hammer2_inode_ref(ip);
                        hammer2_inode_unlock_ex(ip, NULL);
                        hammer2_cluster_unlock(cluster);
                        cluster = hammer2_inode_lock_ex(ip);
                        ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
                        hammer2_inode_drop(ip);
                        kprintf("nresolve: fixup to type %02x\n",
                                ripdata->type);
                }
        } else {
                ip = NULL;
        }

#if 0
        /*
         * Deconsolidate any hardlink whos nlinks == 1.  Ignore errors.
         * If an error occurs chain and ip are left alone.
         *
         * XXX upgrade shared lock?
         */
        if (ochain && chain &&
            chain->data->ipdata.nlinks == 1 && !dip->pmp->ronly) {
                kprintf("hammer2: need to unconsolidate hardlink for %s\n",
                        chain->data->ipdata.filename);
                /* XXX retain shared lock on dip? (currently not held) */
                hammer2_trans_init(&trans, dip->pmp, 0);
                hammer2_hardlink_deconsolidate(&trans, dip, &chain, &ochain);
                hammer2_trans_done(&trans);
        }
#endif

        /*
         * Acquire the related vnode
         *
         * NOTE: For error processing, only ENOENT resolves the namecache
         *       entry to NULL, otherwise we just return the error and
         *       leave the namecache unresolved.
         *
         * NOTE: multiple hammer2_inode structures can be aliased to the
         *       same chain element, for example for hardlinks.  This
         *       use case does not 'reattach' inode associations that
         *       might already exist, but always allocates a new one.
         *
         * WARNING: inode structure is locked exclusively via inode_get
         *          but chain was locked shared.  inode_unlock_ex()
         *          will handle it properly.
         */
        if (cluster) {
                vp = hammer2_igetv(ip, cluster, &error);
                if (error == 0) {
                        vn_unlock(vp);
                        cache_setvp(ap->a_nch, vp);
                } else if (error == ENOENT) {
                        cache_setvp(ap->a_nch, NULL);
                }
                hammer2_inode_unlock_ex(ip, cluster);

                /*
                 * The vp should not be released until after we've disposed
                 * of our locks, because it might cause vop_inactive() to
                 * be called.
                 */
                if (vp)
                        vrele(vp);
        } else {
                error = ENOENT;
                cache_setvp(ap->a_nch, NULL);
        }
        KASSERT(error || ap->a_nch->ncp->nc_vp != NULL,
                ("resolve error %d/%p ap %p\n",
                 error, ap->a_nch->ncp->nc_vp, ap));
        LOCKSTOP;
        return error;
}

static
int
hammer2_vop_nlookupdotdot(struct vop_nlookupdotdot_args *ap)
{
        hammer2_inode_t *dip;
        hammer2_inode_t *ip;
        hammer2_cluster_t *cparent;
        int error;

        LOCKSTART;
        dip = VTOI(ap->a_dvp);

        if ((ip = dip->pip) == NULL) {
                *ap->a_vpp = NULL;
                LOCKSTOP;
                return ENOENT;
        }
        cparent = hammer2_inode_lock_ex(ip);
        *ap->a_vpp = hammer2_igetv(ip, cparent, &error);
        hammer2_inode_unlock_ex(ip, cparent);

        LOCKSTOP;
        return error;
}

static
int
hammer2_vop_nmkdir(struct vop_nmkdir_args *ap)
{
        hammer2_inode_t *dip;
        hammer2_inode_t *nip;
        hammer2_trans_t trans;
        hammer2_cluster_t *cluster;
        struct namecache *ncp;
        const uint8_t *name;
        size_t name_len;
        int error;

        LOCKSTART;
        dip = VTOI(ap->a_dvp);
        if (dip->pmp->ronly) {
                LOCKSTOP;
                return (EROFS);
        }

        ncp = ap->a_nch->ncp;
        name = ncp->nc_name;
        name_len = ncp->nc_nlen;
        cluster = NULL;

        hammer2_pfs_memory_wait(dip->pmp);
        hammer2_trans_init(&trans, dip->pmp, HAMMER2_TRANS_NEWINODE);
        nip = hammer2_inode_create(&trans, dip, ap->a_vap, ap->a_cred,
                                   name, name_len, &cluster, &error);
        if (error) {
                KKASSERT(nip == NULL);
                *ap->a_vpp = NULL;
        } else {
                *ap->a_vpp = hammer2_igetv(nip, cluster, &error);
                hammer2_inode_unlock_ex(nip, cluster);
        }
        hammer2_trans_done(&trans);

        if (error == 0) {
                cache_setunresolved(ap->a_nch);
                cache_setvp(ap->a_nch, *ap->a_vpp);
        }
        LOCKSTOP;
        return error;
}

/*
 * Return the largest contiguous physical disk range for the logical
 * request, in bytes.
 *
 * (struct vnode *vp, off_t loffset, off_t *doffsetp, int *runp, int *runb)
 *
 * Basically disabled, the logical buffer write thread has to deal with
 * buffers one-at-a-time.
 */
static
int
hammer2_vop_bmap(struct vop_bmap_args *ap)
{
        *ap->a_doffsetp = NOOFFSET;
        if (ap->a_runp)
                *ap->a_runp = 0;
        if (ap->a_runb)
                *ap->a_runb = 0;
        return (EOPNOTSUPP);
}

static
int
hammer2_vop_open(struct vop_open_args *ap)
{
        return vop_stdopen(ap);
}

/*
 * hammer2_vop_advlock { vp, id, op, fl, flags }
 */
static
int
hammer2_vop_advlock(struct vop_advlock_args *ap)
{
        hammer2_inode_t *ip = VTOI(ap->a_vp);
        const hammer2_inode_data_t *ripdata;
        hammer2_cluster_t *cparent;
        hammer2_off_t size;

        cparent = hammer2_inode_lock_sh(ip);
        ripdata = &hammer2_cluster_rdata(cparent)->ipdata;
        size = ripdata->size;
        hammer2_inode_unlock_sh(ip, cparent);
        return (lf_advlock(ap, &ip->advlock, size));
}


static
int
hammer2_vop_close(struct vop_close_args *ap)
{
        return vop_stdclose(ap);
}

/*
 * hammer2_vop_nlink { nch, dvp, vp, cred }
 *
 * Create a hardlink from (vp) to {dvp, nch}.
 */
static
int
hammer2_vop_nlink(struct vop_nlink_args *ap)
{
        hammer2_inode_t *fdip;  /* target directory to create link in */
        hammer2_inode_t *tdip;  /* target directory to create link in */
        hammer2_inode_t *cdip;  /* common parent directory */
        hammer2_inode_t *ip;    /* inode we are hardlinking to */
        hammer2_cluster_t *cluster;
        hammer2_cluster_t *fdcluster;
        hammer2_cluster_t *tdcluster;
        hammer2_cluster_t *cdcluster;
        hammer2_trans_t trans;
        struct namecache *ncp;
        const uint8_t *name;
        size_t name_len;
        int error;

        LOCKSTART;
        tdip = VTOI(ap->a_dvp);
        if (tdip->pmp->ronly) {
                LOCKSTOP;
                return (EROFS);
        }

        ncp = ap->a_nch->ncp;
        name = ncp->nc_name;
        name_len = ncp->nc_nlen;

        /*
         * ip represents the file being hardlinked.  The file could be a
         * normal file or a hardlink target if it has already been hardlinked.
         * If ip is a hardlinked target then ip->pip represents the location
         * of the hardlinked target, NOT the location of the hardlink pointer.
         *
         * Bump nlinks and potentially also create or move the hardlink
         * target in the parent directory common to (ip) and (tdip).  The
         * consolidation code can modify ip->cluster and ip->pip.  The
         * returned cluster is locked.
         */
        ip = VTOI(ap->a_vp);
        hammer2_pfs_memory_wait(ip->pmp);
        hammer2_trans_init(&trans, ip->pmp, HAMMER2_TRANS_NEWINODE);

        /*
         * The common parent directory must be locked first to avoid deadlocks.
         * Also note that fdip and/or tdip might match cdip.
         */
        fdip = ip->pip;
        cdip = hammer2_inode_common_parent(fdip, tdip);
        cdcluster = hammer2_inode_lock_ex(cdip);
        fdcluster = hammer2_inode_lock_ex(fdip);
        tdcluster = hammer2_inode_lock_ex(tdip);
        cluster = hammer2_inode_lock_ex(ip);
        error = hammer2_hardlink_consolidate(&trans, ip, &cluster,
                                             cdip, cdcluster, 1);
        if (error)
                goto done;

        /*
         * Create a directory entry connected to the specified cluster.
         *
         * WARNING! chain can get moved by the connect (indirectly due to
         *          potential indirect block creation).
         */
        error = hammer2_inode_connect(&trans, &cluster, 1,
                                      tdip, tdcluster,
                                      name, name_len, 0);
        if (error == 0) {
                cache_setunresolved(ap->a_nch);
                cache_setvp(ap->a_nch, ap->a_vp);
        }
done:
        hammer2_inode_unlock_ex(ip, cluster);
        hammer2_inode_unlock_ex(tdip, tdcluster);
        hammer2_inode_unlock_ex(fdip, fdcluster);
        hammer2_inode_unlock_ex(cdip, cdcluster);
        hammer2_inode_drop(cdip);
        hammer2_trans_done(&trans);

        LOCKSTOP;
        return error;
}

/*
 * hammer2_vop_ncreate { nch, dvp, vpp, cred, vap }
 *
 * The operating system has already ensured that the directory entry
 * does not exist and done all appropriate namespace locking.
 */
static
int
hammer2_vop_ncreate(struct vop_ncreate_args *ap)
{
        hammer2_inode_t *dip;
        hammer2_inode_t *nip;
        hammer2_trans_t trans;
        hammer2_cluster_t *ncluster;
        struct namecache *ncp;
        const uint8_t *name;
        size_t name_len;
        int error;

        LOCKSTART;
        dip = VTOI(ap->a_dvp);
        if (dip->pmp->ronly) {
                LOCKSTOP;
                return (EROFS);
        }

        ncp = ap->a_nch->ncp;
        name = ncp->nc_name;
        name_len = ncp->nc_nlen;
        hammer2_pfs_memory_wait(dip->pmp);
        hammer2_trans_init(&trans, dip->pmp, HAMMER2_TRANS_NEWINODE);
        ncluster = NULL;

        nip = hammer2_inode_create(&trans, dip, ap->a_vap, ap->a_cred,
                                   name, name_len, &ncluster, &error);
        if (error) {
                KKASSERT(nip == NULL);
                *ap->a_vpp = NULL;
        } else {
                *ap->a_vpp = hammer2_igetv(nip, ncluster, &error);
                hammer2_inode_unlock_ex(nip, ncluster);
        }
        hammer2_trans_done(&trans);

        if (error == 0) {
                cache_setunresolved(ap->a_nch);
                cache_setvp(ap->a_nch, *ap->a_vpp);
        }
        LOCKSTOP;
        return error;
}

/*
 * Make a device node (typically a fifo)
 */
static
int
hammer2_vop_nmknod(struct vop_nmknod_args *ap)
{
        hammer2_inode_t *dip;
        hammer2_inode_t *nip;
        hammer2_trans_t trans;
        hammer2_cluster_t *ncluster;
        struct namecache *ncp;
        const uint8_t *name;
        size_t name_len;
        int error;

        LOCKSTART;
        dip = VTOI(ap->a_dvp);
        if (dip->pmp->ronly) {
                LOCKSTOP;
                return (EROFS);
        }

        ncp = ap->a_nch->ncp;
        name = ncp->nc_name;
        name_len = ncp->nc_nlen;
        hammer2_pfs_memory_wait(dip->pmp);
        hammer2_trans_init(&trans, dip->pmp, HAMMER2_TRANS_NEWINODE);
        ncluster = NULL;

        nip = hammer2_inode_create(&trans, dip, ap->a_vap, ap->a_cred,
                                   name, name_len, &ncluster, &error);
        if (error) {
                KKASSERT(nip == NULL);
                *ap->a_vpp = NULL;
        } else {
                *ap->a_vpp = hammer2_igetv(nip, ncluster, &error);
                hammer2_inode_unlock_ex(nip, ncluster);
        }
        hammer2_trans_done(&trans);

        if (error == 0) {
                cache_setunresolved(ap->a_nch);
                cache_setvp(ap->a_nch, *ap->a_vpp);
        }
        LOCKSTOP;
        return error;
}

/*
 * hammer2_vop_nsymlink { nch, dvp, vpp, cred, vap, target }
 */
static
int
hammer2_vop_nsymlink(struct vop_nsymlink_args *ap)
{
        hammer2_inode_t *dip;
        hammer2_inode_t *nip;
        hammer2_cluster_t *ncparent;
        hammer2_trans_t trans;
        struct namecache *ncp;
        const uint8_t *name;
        size_t name_len;
        int error;
        
        dip = VTOI(ap->a_dvp);
        if (dip->pmp->ronly)
                return (EROFS);

        ncp = ap->a_nch->ncp;
        name = ncp->nc_name;
        name_len = ncp->nc_nlen;
        hammer2_pfs_memory_wait(dip->pmp);
        hammer2_trans_init(&trans, dip->pmp, HAMMER2_TRANS_NEWINODE);
        ncparent = NULL;

        ap->a_vap->va_type = VLNK;      /* enforce type */

        nip = hammer2_inode_create(&trans, dip, ap->a_vap, ap->a_cred,
                                   name, name_len, &ncparent, &error);
        if (error) {
                KKASSERT(nip == NULL);
                *ap->a_vpp = NULL;
                hammer2_trans_done(&trans);
                return error;
        }
        *ap->a_vpp = hammer2_igetv(nip, ncparent, &error);

        /*
         * Build the softlink (~like file data) and finalize the namecache.
         */
        if (error == 0) {
                size_t bytes;
                struct uio auio;
                struct iovec aiov;
                hammer2_inode_data_t *nipdata;

                nipdata = &hammer2_cluster_wdata(ncparent)->ipdata;
                /* nipdata = &nip->chain->data->ipdata;XXX */
                bytes = strlen(ap->a_target);

                if (bytes <= HAMMER2_EMBEDDED_BYTES) {
                        KKASSERT(nipdata->op_flags &
                                 HAMMER2_OPFLAG_DIRECTDATA);
                        bcopy(ap->a_target, nipdata->u.data, bytes);
                        nipdata->size = bytes;
                        nip->size = bytes;
                        hammer2_cluster_modsync(ncparent);
                        hammer2_inode_unlock_ex(nip, ncparent);
                        /* nipdata = NULL; not needed */
                } else {
                        hammer2_inode_unlock_ex(nip, ncparent);
                        /* nipdata = NULL; not needed */
                        bzero(&auio, sizeof(auio));
                        bzero(&aiov, sizeof(aiov));
                        auio.uio_iov = &aiov;
                        auio.uio_segflg = UIO_SYSSPACE;
                        auio.uio_rw = UIO_WRITE;
                        auio.uio_resid = bytes;
                        auio.uio_iovcnt = 1;
                        auio.uio_td = curthread;
                        aiov.iov_base = ap->a_target;
                        aiov.iov_len = bytes;
                        error = hammer2_write_file(nip, &auio, IO_APPEND, 0);
                        /* XXX handle error */
                        error = 0;
                }
        } else {
                hammer2_inode_unlock_ex(nip, ncparent);
        }
        hammer2_trans_done(&trans);

        /*
         * Finalize namecache
         */
        if (error == 0) {
                cache_setunresolved(ap->a_nch);
                cache_setvp(ap->a_nch, *ap->a_vpp);
                /* hammer2_knote(ap->a_dvp, NOTE_WRITE); */
        }
        return error;
}

/*
 * hammer2_vop_nremove { nch, dvp, cred }
 */
static
int
hammer2_vop_nremove(struct vop_nremove_args *ap)
{
        hammer2_inode_t *dip;
        hammer2_trans_t trans;
        struct namecache *ncp;
        const uint8_t *name;
        size_t name_len;
        int error;

        LOCKSTART;
        dip = VTOI(ap->a_dvp);
        if (dip->pmp->ronly) {
                LOCKSTOP;
                return(EROFS);
        }

        ncp = ap->a_nch->ncp;
        name = ncp->nc_name;
        name_len = ncp->nc_nlen;

        hammer2_pfs_memory_wait(dip->pmp);
        hammer2_trans_init(&trans, dip->pmp, 0);
        error = hammer2_unlink_file(&trans, dip, name, name_len,
                                    0, NULL, ap->a_nch, -1);
        hammer2_run_unlinkq(&trans, dip->pmp);
        hammer2_trans_done(&trans);
        if (error == 0)
                cache_unlink(ap->a_nch);
        LOCKSTOP;
        return (error);
}

/*
 * hammer2_vop_nrmdir { nch, dvp, cred }
 */
static
int
hammer2_vop_nrmdir(struct vop_nrmdir_args *ap)
{
        hammer2_inode_t *dip;
        hammer2_trans_t trans;
        struct namecache *ncp;
        const uint8_t *name;
        size_t name_len;
        int error;

        LOCKSTART;
        dip = VTOI(ap->a_dvp);
        if (dip->pmp->ronly) {
                LOCKSTOP;
                return(EROFS);
        }

        ncp = ap->a_nch->ncp;
        name = ncp->nc_name;
        name_len = ncp->nc_nlen;

        hammer2_pfs_memory_wait(dip->pmp);
        hammer2_trans_init(&trans, dip->pmp, 0);
        hammer2_run_unlinkq(&trans, dip->pmp);
        error = hammer2_unlink_file(&trans, dip, name, name_len,
                                    1, NULL, ap->a_nch, -1);
        hammer2_trans_done(&trans);
        if (error == 0)
                cache_unlink(ap->a_nch);
        LOCKSTOP;
        return (error);
}

/*
 * hammer2_vop_nrename { fnch, tnch, fdvp, tdvp, cred }
 */
static
int
hammer2_vop_nrename(struct vop_nrename_args *ap)
{
        struct namecache *fncp;
        struct namecache *tncp;
        hammer2_inode_t *cdip;
        hammer2_inode_t *fdip;
        hammer2_inode_t *tdip;
        hammer2_inode_t *ip;
        hammer2_cluster_t *cluster;
        hammer2_cluster_t *fdcluster;
        hammer2_cluster_t *tdcluster;
        hammer2_cluster_t *cdcluster;
        hammer2_trans_t trans;
        const uint8_t *fname;
        size_t fname_len;
        const uint8_t *tname;
        size_t tname_len;
        int error;
        int tnch_error;
        int hlink;

        if (ap->a_fdvp->v_mount != ap->a_tdvp->v_mount)
                return(EXDEV);
        if (ap->a_fdvp->v_mount != ap->a_fnch->ncp->nc_vp->v_mount)
                return(EXDEV);

        fdip = VTOI(ap->a_fdvp);        /* source directory */
        tdip = VTOI(ap->a_tdvp);        /* target directory */

        if (fdip->pmp->ronly)
                return(EROFS);

        LOCKSTART;
        fncp = ap->a_fnch->ncp;         /* entry name in source */
        fname = fncp->nc_name;
        fname_len = fncp->nc_nlen;

        tncp = ap->a_tnch->ncp;         /* entry name in target */
        tname = tncp->nc_name;
        tname_len = tncp->nc_nlen;

        hammer2_pfs_memory_wait(tdip->pmp);
        hammer2_trans_init(&trans, tdip->pmp, 0);

        /*
         * ip is the inode being renamed.  If this is a hardlink then
         * ip represents the actual file and not the hardlink marker.
         */
        ip = VTOI(fncp->nc_vp);
        cluster = NULL;


        /*
         * The common parent directory must be locked first to avoid deadlocks.
         * Also note that fdip and/or tdip might match cdip.
         *
         * WARNING! fdip may not match ip->pip.  That is, if the source file
         *          is already a hardlink then what we are renaming is the
         *          hardlink pointer, not the hardlink itself.  The hardlink
         *          directory (ip->pip) will already be at a common parent
         *          of fdrip.
         *
         *          Be sure to use ip->pip when finding the common parent
         *          against tdip or we might accidently move the hardlink
         *          target into a subdirectory that makes it inaccessible to
         *          other pointers.
         */
        cdip = hammer2_inode_common_parent(ip->pip, tdip);
        cdcluster = hammer2_inode_lock_ex(cdip);
        fdcluster = hammer2_inode_lock_ex(fdip);
        tdcluster = hammer2_inode_lock_ex(tdip);

        /*
         * Keep a tight grip on the inode so the temporary unlinking from
         * the source location prior to linking to the target location
         * does not cause the cluster to be destroyed.
         *
         * NOTE: To avoid deadlocks we cannot lock (ip) while we are
         *       unlinking elements from their directories.  Locking
         *       the nlinks field does not lock the whole inode.
         */
        hammer2_inode_ref(ip);

        /*
         * Remove target if it exists.
         */
        error = hammer2_unlink_file(&trans, tdip, tname, tname_len,
                                    -1, NULL, ap->a_tnch, -1);
        tnch_error = error;
        if (error && error != ENOENT)
                goto done;

        /*
         * When renaming a hardlinked file we may have to re-consolidate
         * the location of the hardlink target.
         *
         * If ip represents a regular file the consolidation code essentially
         * does nothing other than return the same locked cluster that was
         * passed in.
         *
         * The returned cluster will be locked.
         *
         * WARNING!  We do not currently have a local copy of ipdata but
         *           we do use one later remember that it must be reloaded
         *           on any modification to the inode, including connects.
         */
        cluster = hammer2_inode_lock_ex(ip);
        error = hammer2_hardlink_consolidate(&trans, ip, &cluster,
                                             cdip, cdcluster, 0);
        if (error)
                goto done;

        /*
         * Disconnect (fdip, fname) from the source directory.  This will
         * disconnect (ip) if it represents a direct file.  If (ip) represents
         * a hardlink the HARDLINK pointer object will be removed but the
         * hardlink will stay intact.
         *
         * Always pass nch as NULL because we intend to reconnect the inode,
         * so we don't want hammer2_unlink_file() to rename it to the hidden
         * open-but-unlinked directory.
         *
         * The target cluster may be marked DELETED but will not be destroyed
         * since we retain our hold on ip and cluster.
         *
         * NOTE: We pass nlinks as 0 (not -1) in order to retain the file's
         *       link count.
         */
        error = hammer2_unlink_file(&trans, fdip, fname, fname_len,
                                    -1, &hlink, NULL, 0);
        KKASSERT(error != EAGAIN);
        if (error)
                goto done;

        /*
         * Reconnect ip to target directory using cluster.  Chains cannot
         * actually be moved, so this will duplicate the cluster in the new
         * spot and assign it to the ip, replacing the old cluster.
         *
         * WARNING: Because recursive locks are allowed and we unlinked the
         *          file that we have a cluster-in-hand for just above, the
         *          cluster might have been delete-duplicated.  We must
         *          refactor the cluster.
         *
         * WARNING: Chain locks can lock buffer cache buffers, to avoid
         *          deadlocks we want to unlock before issuing a cache_*()
         *          op (that might have to lock a vnode).
         *
         * NOTE:    Pass nlinks as 0 because we retained the link count from
         *          the unlink, so we do not have to modify it.
         */
        error = hammer2_inode_connect(&trans, &cluster, hlink,
                                      tdip, tdcluster,
                                      tname, tname_len, 0);
        if (error == 0) {
                KKASSERT(cluster != NULL);
                hammer2_inode_repoint(ip, (hlink ? ip->pip : tdip), cluster);
        }
done:
        hammer2_inode_unlock_ex(ip, cluster);
        hammer2_inode_unlock_ex(tdip, tdcluster);
        hammer2_inode_unlock_ex(fdip, fdcluster);
        hammer2_inode_unlock_ex(cdip, cdcluster);
        hammer2_inode_drop(ip);
        hammer2_inode_drop(cdip);
        hammer2_run_unlinkq(&trans, fdip->pmp);
        hammer2_trans_done(&trans);

        /*
         * Issue the namecache update after unlocking all the internal
         * hammer structures, otherwise we might deadlock.
         */
        if (tnch_error == 0) {
                cache_unlink(ap->a_tnch);
                cache_setunresolved(ap->a_tnch);
        }
        if (error == 0)
                cache_rename(ap->a_fnch, ap->a_tnch);

        LOCKSTOP;
        return (error);
}

/*
 * Strategy code (async logical file buffer I/O from system)
 *
 * WARNING: The strategy code cannot safely use hammer2 transactions
 *          as this can deadlock against vfs_sync's vfsync() call
 *          if multiple flushes are queued.  All H2 structures must
 *          already be present and ready for the DIO.
 *
 *          Reads can be initiated asynchronously, writes have to be
 *          spooled to a separate thread for action to avoid deadlocks.
 */
static int hammer2_strategy_read(struct vop_strategy_args *ap);
static int hammer2_strategy_write(struct vop_strategy_args *ap);
static void hammer2_strategy_read_callback(hammer2_iocb_t *iocb);

static
int
hammer2_vop_strategy(struct vop_strategy_args *ap)
{
        struct bio *biop;
        struct buf *bp;
        int error;

        biop = ap->a_bio;
        bp = biop->bio_buf;

        switch(bp->b_cmd) {
        case BUF_CMD_READ:
                error = hammer2_strategy_read(ap);
                ++hammer2_iod_file_read;
                break;
        case BUF_CMD_WRITE:
                error = hammer2_strategy_write(ap);
                ++hammer2_iod_file_write;
                break;
        default:
                bp->b_error = error = EINVAL;
                bp->b_flags |= B_ERROR;
                biodone(biop);
                break;
        }
        return (error);
}

/*
 * Logical buffer I/O, async read.
 */
static
int
hammer2_strategy_read(struct vop_strategy_args *ap)
{
        struct buf *bp;
        struct bio *bio;
        struct bio *nbio;
        hammer2_inode_t *ip;
        hammer2_cluster_t *cparent;
        hammer2_cluster_t *cluster;
        hammer2_key_t key_dummy;
        hammer2_key_t lbase;
        int ddflag;
        uint8_t btype;

        bio = ap->a_bio;
        bp = bio->bio_buf;
        ip = VTOI(ap->a_vp);
        nbio = push_bio(bio);

        lbase = bio->bio_offset;
        KKASSERT(((int)lbase & HAMMER2_PBUFMASK) == 0);

        /*
         * Lookup the file offset.
         */
        cparent = hammer2_inode_lock_sh(ip);
        cluster = hammer2_cluster_lookup(cparent, &key_dummy,
                                       lbase, lbase,
                                       HAMMER2_LOOKUP_NODATA |
                                       HAMMER2_LOOKUP_SHARED,
                                       &ddflag);
        hammer2_inode_unlock_sh(ip, cparent);

        /*
         * Data is zero-fill if no cluster could be found
         * (XXX or EIO on a cluster failure).
         */
        if (cluster == NULL) {
                bp->b_resid = 0;
                bp->b_error = 0;
                bzero(bp->b_data, bp->b_bcount);
                biodone(nbio);
                return(0);
        }

        /*
         * Cluster elements must be type INODE or type DATA, but the
         * compression mode (or not) for DATA chains can be different for
         * each chain.  This will be handled by the callback.
         *
         * If the cluster already has valid data the callback will be made
         * immediately/synchronously.
         */
        btype = hammer2_cluster_type(cluster);
        if (btype != HAMMER2_BREF_TYPE_INODE &&
            btype != HAMMER2_BREF_TYPE_DATA) {
                panic("READ PATH: hammer2_strategy_read: unknown bref type");
        }
        hammer2_cluster_load_async(cluster, hammer2_strategy_read_callback,
                                   nbio);
        return(0);
}

/*
 * Read callback for hammer2_cluster_load_async().  The load function may
 * start several actual I/Os but will only make one callback, typically with
 * the first valid I/O XXX
 */
static
void
hammer2_strategy_read_callback(hammer2_iocb_t *iocb)
{
        struct bio *bio = iocb->ptr;    /* original logical buffer */
        struct buf *bp = bio->bio_buf;  /* original logical buffer */
        hammer2_chain_t *chain;
        hammer2_cluster_t *cluster;
        hammer2_io_t *dio;
        char *data;
        int i;

        /*
         * Extract data and handle iteration on I/O failure.  iocb->off
         * is the cluster index for iteration.
         */
        cluster = iocb->cluster;
        dio = iocb->dio;        /* can be NULL if iocb not in progress */

        /*
         * Work to do if INPROG set, else dio is already good or dio is
         * NULL (which is the shortcut case if chain->data is already good).
         */
        if (iocb->flags & HAMMER2_IOCB_INPROG) {
                /*
                 * Read attempt not yet made.  Issue an asynchronous read
                 * if necessary and return, operation will chain back to
                 * this function.
                 */
                if ((iocb->flags & HAMMER2_IOCB_READ) == 0) {
                        if (dio->bp == NULL ||
                            (dio->bp->b_flags & B_CACHE) == 0) {
                                if (dio->bp) {
                                        bqrelse(dio->bp);
                                        dio->bp = NULL;
                                }
                                iocb->flags |= HAMMER2_IOCB_READ;
                                breadcb(dio->hmp->devvp,
                                        dio->pbase, dio->psize,
                                        hammer2_io_callback, iocb);
                                return;
                        }
                }
        }

        /*
         * If we have a DIO it is now done, check for an error and
         * calculate the data.
         *
         * If there is no DIO it is an optimization by
         * hammer2_cluster_load_async(), the data is available in
         * chain->data.
         */
        if (dio) {
                if (dio->bp->b_flags & B_ERROR) {
                        i = (int)iocb->lbase + 1;
                        if (i >= cluster->nchains) {
                                bp->b_flags |= B_ERROR;
                                bp->b_error = dio->bp->b_error;
                                hammer2_io_complete(iocb);
                                biodone(bio);
                                hammer2_cluster_unlock(cluster);
                        } else {
                                hammer2_io_complete(iocb); /* XXX */
                                chain = cluster->array[i].chain;
                                kprintf("hammer2: IO CHAIN-%d %p\n", i, chain);
                                hammer2_adjreadcounter(&chain->bref,
                                                       chain->bytes);
                                iocb->chain = chain;
                                iocb->lbase = (off_t)i;
                                iocb->flags = 0;
                                iocb->error = 0;
                                hammer2_io_getblk(chain->hmp,
                                                  chain->bref.data_off,
                                                  chain->bytes,
                                                  iocb);
                        }
                        return;
                }
                chain = iocb->chain;
                data = hammer2_io_data(dio, chain->bref.data_off);
        } else {
                /*
                 * Special synchronous case, data present in chain->data.
                 */
                chain = iocb->chain;
                data = (void *)chain->data;
        }

        if (chain->bref.type == HAMMER2_BREF_TYPE_INODE) {
                /*
                 * Data is embedded in the inode (copy from inode).
                 */
                bcopy(((hammer2_inode_data_t *)data)->u.data,
                      bp->b_data, HAMMER2_EMBEDDED_BYTES);
                bzero(bp->b_data + HAMMER2_EMBEDDED_BYTES,
                      bp->b_bcount - HAMMER2_EMBEDDED_BYTES);
                bp->b_resid = 0;
                bp->b_error = 0;
        } else if (chain->bref.type == HAMMER2_BREF_TYPE_DATA) {
                /*
                 * Data is on-media, issue device I/O and copy.
                 *
                 * XXX direct-IO shortcut could go here XXX.
                 */
                switch (HAMMER2_DEC_COMP(chain->bref.methods)) {
                case HAMMER2_COMP_LZ4:
                        hammer2_decompress_LZ4_callback(data, chain->bytes,
                                                        bio);
                        break;
                case HAMMER2_COMP_ZLIB:
                        hammer2_decompress_ZLIB_callback(data, chain->bytes,
                                                         bio);
                        break;
                case HAMMER2_COMP_NONE:
                        KKASSERT(chain->bytes <= bp->b_bcount);
                        bcopy(data, bp->b_data, chain->bytes);
                        if (chain->bytes < bp->b_bcount) {
                                bzero(bp->b_data + chain->bytes,
                                      bp->b_bcount - chain->bytes);
                        }
                        bp->b_flags |= B_NOTMETA;
                        bp->b_resid = 0;
                        bp->b_error = 0;
                        break;
                default:
                        panic("hammer2_strategy_read: "
                              "unknown compression type");
                }
        } else {
                /* bqrelse the dio to help stabilize the call to panic() */
                if (dio)
                        hammer2_io_bqrelse(&dio);
                panic("hammer2_strategy_read: unknown bref type");
        }

        /*
         * Once the iocb is cleaned up the DIO (if any) will no longer be
         * in-progress but will still have a ref.  Be sure to release
         * the ref.
         */
        hammer2_io_complete(iocb);              /* physical management */
        if (dio)                                /* physical dio & buffer */
                hammer2_io_bqrelse(&dio);
        hammer2_cluster_unlock(cluster);        /* cluster management */
        biodone(bio);                           /* logical buffer */
}

static
int
hammer2_strategy_write(struct vop_strategy_args *ap)
{       
        hammer2_pfsmount_t *pmp;
        struct bio *bio;
        struct buf *bp;
        hammer2_inode_t *ip;
        
        bio = ap->a_bio;
        bp = bio->bio_buf;
        ip = VTOI(ap->a_vp);
        pmp = ip->pmp;
        
        hammer2_lwinprog_ref(pmp);
        hammer2_mtx_ex(&pmp->wthread_mtx);
        if (TAILQ_EMPTY(&pmp->wthread_bioq.queue)) {
                bioq_insert_tail(&pmp->wthread_bioq, ap->a_bio);
                hammer2_mtx_unlock(&pmp->wthread_mtx);
                wakeup(&pmp->wthread_bioq);
        } else {
                bioq_insert_tail(&pmp->wthread_bioq, ap->a_bio);
                hammer2_mtx_unlock(&pmp->wthread_mtx);
        }
        hammer2_lwinprog_wait(pmp);

        return(0);
}

/*
 * hammer2_vop_ioctl { vp, command, data, fflag, cred }
 */
static
int
hammer2_vop_ioctl(struct vop_ioctl_args *ap)
{
        hammer2_inode_t *ip;
        int error;

        LOCKSTART;
        ip = VTOI(ap->a_vp);

        error = hammer2_ioctl(ip, ap->a_command, (void *)ap->a_data,
                              ap->a_fflag, ap->a_cred);
        LOCKSTOP;
        return (error);
}

static
int 
hammer2_vop_mountctl(struct vop_mountctl_args *ap)
{
        struct mount *mp;
        hammer2_pfsmount_t *pmp;
        int rc;

        LOCKSTART;
        switch (ap->a_op) {
        case (MOUNTCTL_SET_EXPORT):
                mp = ap->a_head.a_ops->head.vv_mount;
                pmp = MPTOPMP(mp);

                if (ap->a_ctllen != sizeof(struct export_args))
                        rc = (EINVAL);
                else
                        rc = vfs_export(mp, &pmp->export,
                                        (const struct export_args *)ap->a_ctl);
                break;
        default:
                rc = vop_stdmountctl(ap);
                break;
        }
        LOCKSTOP;
        return (rc);
}

/*
 * This handles unlinked open files after the vnode is finally dereferenced.
 * To avoid deadlocks it cannot be called from the normal vnode recycling
 * path, so we call it (1) after a unlink, rmdir, or rename, (2) on every
 * flush, and (3) on umount.
 */
void
hammer2_run_unlinkq(hammer2_trans_t *trans, hammer2_pfsmount_t *pmp)
{
        const hammer2_inode_data_t *ripdata;
        hammer2_inode_unlink_t *ipul;
        hammer2_inode_t *ip;
        hammer2_cluster_t *cluster;
        hammer2_cluster_t *cparent;

        if (TAILQ_EMPTY(&pmp->unlinkq))
                return;

        LOCKSTART;
        hammer2_spin_ex(&pmp->list_spin);
        while ((ipul = TAILQ_FIRST(&pmp->unlinkq)) != NULL) {
                TAILQ_REMOVE(&pmp->unlinkq, ipul, entry);
                hammer2_spin_unex(&pmp->list_spin);
                ip = ipul->ip;
                kfree(ipul, pmp->minode);

                cluster = hammer2_inode_lock_ex(ip);
                ripdata = &hammer2_cluster_rdata(cluster)->ipdata;
                if (hammer2_debug & 0x400) {
                        kprintf("hammer2: unlink on reclaim: %s refs=%d\n",
                                ripdata->filename, ip->refs);
                }
                KKASSERT(ripdata->nlinks == 0);

                cparent = hammer2_cluster_parent(cluster);
                hammer2_cluster_delete(trans, cparent, cluster,
                                       HAMMER2_DELETE_PERMANENT);
                hammer2_cluster_unlock(cparent);
                hammer2_inode_unlock_ex(ip, cluster);   /* inode lock */
                hammer2_inode_drop(ip);                 /* ipul ref */

                hammer2_spin_ex(&pmp->list_spin);
        }
        hammer2_spin_unex(&pmp->list_spin);
        LOCKSTOP;
}


/*
 * KQFILTER
 */
static void filt_hammer2detach(struct knote *kn);
static int filt_hammer2read(struct knote *kn, long hint);
static int filt_hammer2write(struct knote *kn, long hint);
static int filt_hammer2vnode(struct knote *kn, long hint);

static struct filterops hammer2read_filtops =
        { FILTEROP_ISFD | FILTEROP_MPSAFE,
          NULL, filt_hammer2detach, filt_hammer2read };
static struct filterops hammer2write_filtops =
        { FILTEROP_ISFD | FILTEROP_MPSAFE,
          NULL, filt_hammer2detach, filt_hammer2write };
static struct filterops hammer2vnode_filtops =
        { FILTEROP_ISFD | FILTEROP_MPSAFE,
          NULL, filt_hammer2detach, filt_hammer2vnode };

static
int
hammer2_vop_kqfilter(struct vop_kqfilter_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct knote *kn = ap->a_kn;

        switch (kn->kn_filter) {
        case EVFILT_READ:
                kn->kn_fop = &hammer2read_filtops;
                break;
        case EVFILT_WRITE:
                kn->kn_fop = &hammer2write_filtops;
                break;
        case EVFILT_VNODE:
                kn->kn_fop = &hammer2vnode_filtops;
                break;
        default:
                return (EOPNOTSUPP);
        }

        kn->kn_hook = (caddr_t)vp;

        knote_insert(&vp->v_pollinfo.vpi_kqinfo.ki_note, kn);

        return(0);
}

static void
filt_hammer2detach(struct knote *kn)
{
        struct vnode *vp = (void *)kn->kn_hook;

        knote_remove(&vp->v_pollinfo.vpi_kqinfo.ki_note, kn);
}

static int
filt_hammer2read(struct knote *kn, long hint)
{
        struct vnode *vp = (void *)kn->kn_hook;
        hammer2_inode_t *ip = VTOI(vp);
        off_t off;

        if (hint == NOTE_REVOKE) {
                kn->kn_flags |= (EV_EOF | EV_NODATA | EV_ONESHOT);
                return(1);
        }
        off = ip->size - kn->kn_fp->f_offset;
        kn->kn_data = (off < INTPTR_MAX) ? off : INTPTR_MAX;
        if (kn->kn_sfflags & NOTE_OLDAPI)
                return(1);
        return (kn->kn_data != 0);
}


static int
filt_hammer2write(struct knote *kn, long hint)
{
        if (hint == NOTE_REVOKE)
                kn->kn_flags |= (EV_EOF | EV_NODATA | EV_ONESHOT);
        kn->kn_data = 0;
        return (1);
}

static int
filt_hammer2vnode(struct knote *kn, long hint)
{
        if (kn->kn_sfflags & hint)
                kn->kn_fflags |= hint;
        if (hint == NOTE_REVOKE) {
                kn->kn_flags |= (EV_EOF | EV_NODATA);
                return (1);
        }
        return (kn->kn_fflags != 0);
}

/*
 * FIFO VOPS
 */
static
int
hammer2_vop_markatime(struct vop_markatime_args *ap)
{
        hammer2_inode_t *ip;
        struct vnode *vp;

        vp = ap->a_vp;
        ip = VTOI(vp);

        if (ip->pmp->ronly)
                return(EROFS);
        return(0);
}

static
int
hammer2_vop_fifokqfilter(struct vop_kqfilter_args *ap)
{
        int error;

        error = VOCALL(&fifo_vnode_vops, &ap->a_head);
        if (error)
                error = hammer2_vop_kqfilter(ap);
        return(error);
}

/*
 * VOPS vector
 */
struct vop_ops hammer2_vnode_vops = {
        .vop_default    = vop_defaultop,
        .vop_fsync      = hammer2_vop_fsync,
        .vop_getpages   = vop_stdgetpages,
        .vop_putpages   = vop_stdputpages,
        .vop_access     = hammer2_vop_access,
        .vop_advlock    = hammer2_vop_advlock,
        .vop_close      = hammer2_vop_close,
        .vop_nlink      = hammer2_vop_nlink,
        .vop_ncreate    = hammer2_vop_ncreate,
        .vop_nsymlink   = hammer2_vop_nsymlink,
        .vop_nremove    = hammer2_vop_nremove,
        .vop_nrmdir     = hammer2_vop_nrmdir,
        .vop_nrename    = hammer2_vop_nrename,
        .vop_getattr    = hammer2_vop_getattr,
        .vop_setattr    = hammer2_vop_setattr,
        .vop_readdir    = hammer2_vop_readdir,
        .vop_readlink   = hammer2_vop_readlink,
        .vop_getpages   = vop_stdgetpages,
        .vop_putpages   = vop_stdputpages,
        .vop_read       = hammer2_vop_read,
        .vop_write      = hammer2_vop_write,
        .vop_open       = hammer2_vop_open,
        .vop_inactive   = hammer2_vop_inactive,
        .vop_reclaim    = hammer2_vop_reclaim,
        .vop_nresolve   = hammer2_vop_nresolve,
        .vop_nlookupdotdot = hammer2_vop_nlookupdotdot,
        .vop_nmkdir     = hammer2_vop_nmkdir,
        .vop_nmknod     = hammer2_vop_nmknod,
        .vop_ioctl      = hammer2_vop_ioctl,
        .vop_mountctl   = hammer2_vop_mountctl,
        .vop_bmap       = hammer2_vop_bmap,
        .vop_strategy   = hammer2_vop_strategy,
        .vop_kqfilter   = hammer2_vop_kqfilter
};

struct vop_ops hammer2_spec_vops = {
        .vop_default =          vop_defaultop,
        .vop_fsync =            hammer2_vop_fsync,
        .vop_read =             vop_stdnoread,
        .vop_write =            vop_stdnowrite,
        .vop_access =           hammer2_vop_access,
        .vop_close =            hammer2_vop_close,
        .vop_markatime =        hammer2_vop_markatime,
        .vop_getattr =          hammer2_vop_getattr,
        .vop_inactive =         hammer2_vop_inactive,
        .vop_reclaim =          hammer2_vop_reclaim,
        .vop_setattr =          hammer2_vop_setattr
};

struct vop_ops hammer2_fifo_vops = {
        .vop_default =          fifo_vnoperate,
        .vop_fsync =            hammer2_vop_fsync,
#if 0
        .vop_read =             hammer2_vop_fiforead,
        .vop_write =            hammer2_vop_fifowrite,
#endif
        .vop_access =           hammer2_vop_access,
#if 0
        .vop_close =            hammer2_vop_fifoclose,
#endif
        .vop_markatime =        hammer2_vop_markatime,
        .vop_getattr =          hammer2_vop_getattr,
        .vop_inactive =         hammer2_vop_inactive,
        .vop_reclaim =          hammer2_vop_reclaim,
        .vop_setattr =          hammer2_vop_setattr,
        .vop_kqfilter =         hammer2_vop_fifokqfilter
};