HAMMER - Rework write pipelining

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

/*
 * Copyright (c) 2007-2008 The DragonFly Project.  All rights reserved.
 * 
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * $DragonFly: src/sys/vfs/hammer/hammer_vfsops.c,v 1.74 2008/11/13 02:18:43 dillon Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/nlookup.h>
#include <sys/fcntl.h>
#include <sys/sysctl.h>
#include <sys/buf.h>
#include <sys/buf2.h>
#include "hammer.h"

int hammer_supported_version = HAMMER_VOL_VERSION_TWO;
int hammer_debug_io;
int hammer_debug_general;
int hammer_debug_debug = 1;             /* medium-error panics */ 
int hammer_debug_inode;
int hammer_debug_locks;
int hammer_debug_btree;
int hammer_debug_tid;
int hammer_debug_recover;               /* -1 will disable, +1 will force */
int hammer_debug_recover_faults;
int hammer_cluster_enable = 1;          /* enable read clustering by default */
int hammer_count_fsyncs;
int hammer_count_inodes;
int hammer_count_iqueued;
int hammer_count_reclaiming;
int hammer_count_records;
int hammer_count_record_datas;
int hammer_count_volumes;
int hammer_count_buffers;
int hammer_count_nodes;
int64_t hammer_count_extra_space_used;
int64_t hammer_stats_btree_lookups;
int64_t hammer_stats_btree_searches;
int64_t hammer_stats_btree_inserts;
int64_t hammer_stats_btree_deletes;
int64_t hammer_stats_btree_elements;
int64_t hammer_stats_btree_splits;
int64_t hammer_stats_btree_iterations;
int64_t hammer_stats_btree_root_iterations;
int64_t hammer_stats_record_iterations;

int64_t hammer_stats_file_read;
int64_t hammer_stats_file_write;
int64_t hammer_stats_file_iopsr;
int64_t hammer_stats_file_iopsw;
int64_t hammer_stats_disk_read;
int64_t hammer_stats_disk_write;
int64_t hammer_stats_inode_flushes;
int64_t hammer_stats_commits;

int hammer_count_dirtybufspace;         /* global */
int hammer_count_refedbufs;             /* global */
int hammer_count_reservations;
int hammer_count_io_running_read;
int hammer_count_io_running_write;
int hammer_count_io_locked;
int hammer_limit_dirtybufspace;         /* per-mount */
int hammer_limit_recs;                  /* as a whole XXX */
int hammer_limit_inode_recs = 1024;     /* per inode */
int hammer_autoflush = 2000;            /* auto flush */
int hammer_bio_count;
int hammer_verify_zone;
int hammer_verify_data = 1;
int hammer_write_mode;
int hammer_yield_check = 16;
int64_t hammer_contention_count;
int64_t hammer_zone_limit;

SYSCTL_NODE(_vfs, OID_AUTO, hammer, CTLFLAG_RW, 0, "HAMMER filesystem");
SYSCTL_INT(_vfs_hammer, OID_AUTO, supported_version, CTLFLAG_RD,
           &hammer_supported_version, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_general, CTLFLAG_RW,
           &hammer_debug_general, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_io, CTLFLAG_RW,
           &hammer_debug_io, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_debug, CTLFLAG_RW,
           &hammer_debug_debug, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_inode, CTLFLAG_RW,
           &hammer_debug_inode, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_locks, CTLFLAG_RW,
           &hammer_debug_locks, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_btree, CTLFLAG_RW,
           &hammer_debug_btree, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_tid, CTLFLAG_RW,
           &hammer_debug_tid, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_recover, CTLFLAG_RW,
           &hammer_debug_recover, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, debug_recover_faults, CTLFLAG_RW,
           &hammer_debug_recover_faults, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, cluster_enable, CTLFLAG_RW,
           &hammer_cluster_enable, 0, "");

SYSCTL_INT(_vfs_hammer, OID_AUTO, limit_dirtybufspace, CTLFLAG_RW,
           &hammer_limit_dirtybufspace, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, limit_recs, CTLFLAG_RW,
           &hammer_limit_recs, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, limit_inode_recs, CTLFLAG_RW,
           &hammer_limit_inode_recs, 0, "");

SYSCTL_INT(_vfs_hammer, OID_AUTO, count_fsyncs, CTLFLAG_RD,
           &hammer_count_fsyncs, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_inodes, CTLFLAG_RD,
           &hammer_count_inodes, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_iqueued, CTLFLAG_RD,
           &hammer_count_iqueued, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_reclaiming, CTLFLAG_RD,
           &hammer_count_reclaiming, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_records, CTLFLAG_RD,
           &hammer_count_records, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_record_datas, CTLFLAG_RD,
           &hammer_count_record_datas, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_volumes, CTLFLAG_RD,
           &hammer_count_volumes, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_buffers, CTLFLAG_RD,
           &hammer_count_buffers, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_nodes, CTLFLAG_RD,
           &hammer_count_nodes, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, count_extra_space_used, CTLFLAG_RD,
           &hammer_count_extra_space_used, 0, "");

SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_btree_searches, CTLFLAG_RD,
           &hammer_stats_btree_searches, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_btree_lookups, CTLFLAG_RD,
           &hammer_stats_btree_lookups, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_btree_inserts, CTLFLAG_RD,
           &hammer_stats_btree_inserts, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_btree_deletes, CTLFLAG_RD,
           &hammer_stats_btree_deletes, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_btree_elements, CTLFLAG_RD,
           &hammer_stats_btree_elements, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_btree_splits, CTLFLAG_RD,
           &hammer_stats_btree_splits, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_btree_iterations, CTLFLAG_RD,
           &hammer_stats_btree_iterations, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_btree_root_iterations, CTLFLAG_RD,
           &hammer_stats_btree_root_iterations, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_record_iterations, CTLFLAG_RD,
           &hammer_stats_record_iterations, 0, "");

SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_file_read, CTLFLAG_RD,
           &hammer_stats_file_read, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_file_write, CTLFLAG_RD,
           &hammer_stats_file_write, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_file_iopsr, CTLFLAG_RD,
           &hammer_stats_file_iopsr, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_file_iopsw, CTLFLAG_RD,
           &hammer_stats_file_iopsw, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_disk_read, CTLFLAG_RD,
           &hammer_stats_disk_read, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_disk_write, CTLFLAG_RD,
           &hammer_stats_disk_write, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_inode_flushes, CTLFLAG_RD,
           &hammer_stats_inode_flushes, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, stats_commits, CTLFLAG_RD,
           &hammer_stats_commits, 0, "");

SYSCTL_INT(_vfs_hammer, OID_AUTO, count_dirtybufspace, CTLFLAG_RD,
           &hammer_count_dirtybufspace, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_refedbufs, CTLFLAG_RD,
           &hammer_count_refedbufs, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_reservations, CTLFLAG_RD,
           &hammer_count_reservations, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_io_running_read, CTLFLAG_RD,
           &hammer_count_io_running_read, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_io_locked, CTLFLAG_RD,
           &hammer_count_io_locked, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, count_io_running_write, CTLFLAG_RD,
           &hammer_count_io_running_write, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, zone_limit, CTLFLAG_RW,
           &hammer_zone_limit, 0, "");
SYSCTL_QUAD(_vfs_hammer, OID_AUTO, contention_count, CTLFLAG_RW,
           &hammer_contention_count, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, autoflush, CTLFLAG_RW,
           &hammer_autoflush, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, verify_zone, CTLFLAG_RW,
           &hammer_verify_zone, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, verify_data, CTLFLAG_RW,
           &hammer_verify_data, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, write_mode, CTLFLAG_RW,
           &hammer_write_mode, 0, "");
SYSCTL_INT(_vfs_hammer, OID_AUTO, yield_check, CTLFLAG_RW,
           &hammer_yield_check, 0, "");

KTR_INFO_MASTER(hammer);

/*
 * VFS ABI
 */
static void     hammer_free_hmp(struct mount *mp);

static int      hammer_vfs_mount(struct mount *mp, char *path, caddr_t data,
                                struct ucred *cred);
static int      hammer_vfs_unmount(struct mount *mp, int mntflags);
static int      hammer_vfs_root(struct mount *mp, struct vnode **vpp);
static int      hammer_vfs_statfs(struct mount *mp, struct statfs *sbp,
                                struct ucred *cred);
static int      hammer_vfs_statvfs(struct mount *mp, struct statvfs *sbp,
                                struct ucred *cred);
static int      hammer_vfs_sync(struct mount *mp, int waitfor);
static int      hammer_vfs_vget(struct mount *mp, struct vnode *dvp,
                                ino_t ino, struct vnode **vpp);
static int      hammer_vfs_init(struct vfsconf *conf);
static int      hammer_vfs_fhtovp(struct mount *mp, struct vnode *rootvp,
                                struct fid *fhp, struct vnode **vpp);
static int      hammer_vfs_vptofh(struct vnode *vp, struct fid *fhp);
static int      hammer_vfs_checkexp(struct mount *mp, struct sockaddr *nam,
                                int *exflagsp, struct ucred **credanonp);


static struct vfsops hammer_vfsops = {
        .vfs_mount      = hammer_vfs_mount,
        .vfs_unmount    = hammer_vfs_unmount,
        .vfs_root       = hammer_vfs_root,
        .vfs_statfs     = hammer_vfs_statfs,
        .vfs_statvfs    = hammer_vfs_statvfs,
        .vfs_sync       = hammer_vfs_sync,
        .vfs_vget       = hammer_vfs_vget,
        .vfs_init       = hammer_vfs_init,
        .vfs_vptofh     = hammer_vfs_vptofh,
        .vfs_fhtovp     = hammer_vfs_fhtovp,
        .vfs_checkexp   = hammer_vfs_checkexp
};

MALLOC_DEFINE(M_HAMMER, "HAMMER-mount", "");

VFS_SET(hammer_vfsops, hammer, 0);
MODULE_VERSION(hammer, 1);

static int
hammer_vfs_init(struct vfsconf *conf)
{
        int n;

        if (hammer_limit_recs == 0) {
                hammer_limit_recs = nbuf * 25;
                n = kmalloc_limit(M_HAMMER) / 512;
                if (hammer_limit_recs > n)
                        hammer_limit_recs = n;
        }
        if (hammer_limit_dirtybufspace == 0) {
                hammer_limit_dirtybufspace = hidirtybufspace / 2;
                if (hammer_limit_dirtybufspace < 100)
                        hammer_limit_dirtybufspace = 100;
        }
        return(0);
}

static int
hammer_vfs_mount(struct mount *mp, char *mntpt, caddr_t data,
                 struct ucred *cred)
{
        struct hammer_mount_info info;
        hammer_mount_t hmp;
        hammer_volume_t rootvol;
        struct vnode *rootvp;
        struct vnode *devvp = NULL;
        const char *upath;      /* volume name in userspace */
        char *path;             /* volume name in system space */
        int error;
        int i;
        int master_id;
        int maxinodes;

        /*
         * Accept hammer_mount_info.  mntpt is NULL for root mounts at boot.
         */
        if (mntpt == NULL) {
                if ((error = bdevvp(rootdev, &devvp))) {
                        kprintf("hammer_mountroot: can't find devvp\n");
                        return (error);
                }
                mp->mnt_flag &= ~MNT_RDONLY; /* mount R/W */
                bzero(&info, sizeof(info));
                info.asof = 0;
                info.hflags = 0;
                info.nvolumes = 1;
        } else {
                if ((error = copyin(data, &info, sizeof(info))) != 0)
                        return (error);
        }

        /*
         * updating or new mount
         */
        if (mp->mnt_flag & MNT_UPDATE) {
                hmp = (void *)mp->mnt_data;
                KKASSERT(hmp != NULL);
        } else {
                if (info.nvolumes <= 0 || info.nvolumes >= 32768)
                        return (EINVAL);
                hmp = NULL;
        }

        /*
         * master-id validation.  The master id may not be changed by a
         * mount update.
         */
        if (info.hflags & HMNT_MASTERID) {
                if (hmp && hmp->master_id != info.master_id) {
                        kprintf("hammer: cannot change master id "
                                "with mount update\n");
                        return(EINVAL);
                }
                master_id = info.master_id;
                if (master_id < -1 || master_id >= HAMMER_MAX_MASTERS)
                        return (EINVAL);
        } else {
                if (hmp)
                        master_id = hmp->master_id;
                else
                        master_id = 0;
        }

        /*
         * Interal mount data structure
         */
        if (hmp == NULL) {
                hmp = kmalloc(sizeof(*hmp), M_HAMMER, M_WAITOK | M_ZERO);
                mp->mnt_data = (qaddr_t)hmp;
                hmp->mp = mp;
                /*TAILQ_INIT(&hmp->recycle_list);*/

                /*
                 * Make sure kmalloc type limits are set appropriately.  If root
                 * increases the vnode limit you may have to do a dummy remount
                 * to adjust the HAMMER inode limit.
                 */
                kmalloc_create(&hmp->m_misc, "HAMMER-others");
                kmalloc_create(&hmp->m_inodes, "HAMMER-inodes");

                maxinodes = desiredvnodes + desiredvnodes / 5 +
                            HAMMER_RECLAIM_WAIT;
                kmalloc_raise_limit(hmp->m_inodes,
                                    maxinodes * sizeof(struct hammer_inode));

                hmp->root_btree_beg.localization = 0x00000000U;
                hmp->root_btree_beg.obj_id = -0x8000000000000000LL;
                hmp->root_btree_beg.key = -0x8000000000000000LL;
                hmp->root_btree_beg.create_tid = 1;
                hmp->root_btree_beg.delete_tid = 1;
                hmp->root_btree_beg.rec_type = 0;
                hmp->root_btree_beg.obj_type = 0;

                hmp->root_btree_end.localization = 0xFFFFFFFFU;
                hmp->root_btree_end.obj_id = 0x7FFFFFFFFFFFFFFFLL;
                hmp->root_btree_end.key = 0x7FFFFFFFFFFFFFFFLL;
                hmp->root_btree_end.create_tid = 0xFFFFFFFFFFFFFFFFULL;
                hmp->root_btree_end.delete_tid = 0;   /* special case */
                hmp->root_btree_end.rec_type = 0xFFFFU;
                hmp->root_btree_end.obj_type = 0;

                hmp->krate.freq = 1;    /* maximum reporting rate (hz) */
                hmp->krate.count = -16; /* initial burst */

                hmp->sync_lock.refs = 1;
                hmp->free_lock.refs = 1;
                hmp->undo_lock.refs = 1;
                hmp->blkmap_lock.refs = 1;

                TAILQ_INIT(&hmp->delay_list);
                TAILQ_INIT(&hmp->flush_group_list);
                TAILQ_INIT(&hmp->objid_cache_list);
                TAILQ_INIT(&hmp->undo_lru_list);
                TAILQ_INIT(&hmp->reclaim_list);
        }
        hmp->hflags &= ~HMNT_USERFLAGS;
        hmp->hflags |= info.hflags & HMNT_USERFLAGS;

        hmp->master_id = master_id;

        if (info.asof) {
                mp->mnt_flag |= MNT_RDONLY;
                hmp->asof = info.asof;
        } else {
                hmp->asof = HAMMER_MAX_TID;
        }

        /*
         * Re-open read-write if originally read-only, or vise-versa.
         */
        if (mp->mnt_flag & MNT_UPDATE) {
                error = 0;
                if (hmp->ronly && (mp->mnt_kern_flag & MNTK_WANTRDWR)) {
                        kprintf("HAMMER read-only -> read-write\n");
                        hmp->ronly = 0;
                        RB_SCAN(hammer_vol_rb_tree, &hmp->rb_vols_root, NULL,
                                hammer_adjust_volume_mode, NULL);
                        rootvol = hammer_get_root_volume(hmp, &error);
                        if (rootvol) {
                                hammer_recover_flush_buffers(hmp, rootvol, 1);
                                bcopy(rootvol->ondisk->vol0_blockmap,
                                      hmp->blockmap,
                                      sizeof(hmp->blockmap));
                                hammer_rel_volume(rootvol, 0);
                        }
                        RB_SCAN(hammer_ino_rb_tree, &hmp->rb_inos_root, NULL,
                                hammer_reload_inode, NULL);
                        /* kernel clears MNT_RDONLY */
                } else if (hmp->ronly == 0 && (mp->mnt_flag & MNT_RDONLY)) {
                        kprintf("HAMMER read-write -> read-only\n");
                        hmp->ronly = 1; /* messy */
                        RB_SCAN(hammer_ino_rb_tree, &hmp->rb_inos_root, NULL,
                                hammer_reload_inode, NULL);
                        hmp->ronly = 0;
                        hammer_flusher_sync(hmp);
                        hammer_flusher_sync(hmp);
                        hammer_flusher_sync(hmp);
                        hmp->ronly = 1;
                        RB_SCAN(hammer_vol_rb_tree, &hmp->rb_vols_root, NULL,
                                hammer_adjust_volume_mode, NULL);
                }
                return(error);
        }

        RB_INIT(&hmp->rb_vols_root);
        RB_INIT(&hmp->rb_inos_root);
        RB_INIT(&hmp->rb_nods_root);
        RB_INIT(&hmp->rb_undo_root);
        RB_INIT(&hmp->rb_resv_root);
        RB_INIT(&hmp->rb_bufs_root);
        RB_INIT(&hmp->rb_pfsm_root);

        hmp->ronly = ((mp->mnt_flag & MNT_RDONLY) != 0);

        TAILQ_INIT(&hmp->volu_list);
        TAILQ_INIT(&hmp->undo_list);
        TAILQ_INIT(&hmp->data_list);
        TAILQ_INIT(&hmp->meta_list);
        TAILQ_INIT(&hmp->lose_list);

        /*
         * Load volumes
         */
        path = objcache_get(namei_oc, M_WAITOK);
        hmp->nvolumes = -1;
        for (i = 0; i < info.nvolumes; ++i) {
                if (mntpt == NULL) {
                        /*
                         * Root mount.
                         * Only one volume; and no need for copyin.
                         */
                        KKASSERT(info.nvolumes == 1);
                        ksnprintf(path, MAXPATHLEN, "/dev/%s",
                                  mp->mnt_stat.f_mntfromname);  
                        error = 0;
                } else {
                        error = copyin(&info.volumes[i], &upath,
                                       sizeof(char *));
                        if (error == 0)
                                error = copyinstr(upath, path,
                                                  MAXPATHLEN, NULL);
                }
                if (error == 0)
                        error = hammer_install_volume(hmp, path, devvp);
                if (error)
                        break;
        }
        objcache_put(namei_oc, path);

        /*
         * Make sure we found a root volume
         */
        if (error == 0 && hmp->rootvol == NULL) {
                kprintf("hammer_mount: No root volume found!\n");
                error = EINVAL;
        }

        /*
         * Check that all required volumes are available
         */
        if (error == 0 && hammer_mountcheck_volumes(hmp)) {
                kprintf("hammer_mount: Missing volumes, cannot mount!\n");
                error = EINVAL;
        }

        if (error) {
                hammer_free_hmp(mp);
                return (error);
        }

        /*
         * No errors, setup enough of the mount point so we can lookup the
         * root vnode.
         */
        mp->mnt_iosize_max = MAXPHYS;
        mp->mnt_kern_flag |= MNTK_FSMID;

        /* 
         * note: f_iosize is used by vnode_pager_haspage() when constructing
         * its VOP_BMAP call.
         */
        mp->mnt_stat.f_iosize = HAMMER_BUFSIZE;
        mp->mnt_stat.f_bsize = HAMMER_BUFSIZE;

        mp->mnt_vstat.f_frsize = HAMMER_BUFSIZE;
        mp->mnt_vstat.f_bsize = HAMMER_BUFSIZE;

        mp->mnt_maxsymlinklen = 255;
        mp->mnt_flag |= MNT_LOCAL;

        vfs_add_vnodeops(mp, &hammer_vnode_vops, &mp->mnt_vn_norm_ops);
        vfs_add_vnodeops(mp, &hammer_spec_vops, &mp->mnt_vn_spec_ops);
        vfs_add_vnodeops(mp, &hammer_fifo_vops, &mp->mnt_vn_fifo_ops);

        /*
         * The root volume's ondisk pointer is only valid if we hold a
         * reference to it.
         */
        rootvol = hammer_get_root_volume(hmp, &error);
        if (error)
                goto failed;

        /*
         * Perform any necessary UNDO operations.  The recovery code does
         * call hammer_undo_lookup() so we have to pre-cache the blockmap,
         * and then re-copy it again after recovery is complete.
         *
         * If this is a read-only mount the UNDO information is retained
         * in memory in the form of dirty buffer cache buffers, and not
         * written back to the media.
         */
        bcopy(rootvol->ondisk->vol0_blockmap, hmp->blockmap,
              sizeof(hmp->blockmap));

        /*
         * Check filesystem version
         */
        hmp->version = rootvol->ondisk->vol_version;
        if (hmp->version < HAMMER_VOL_VERSION_MIN ||
            hmp->version > HAMMER_VOL_VERSION_MAX) {
                kprintf("HAMMER: mount unsupported fs version %d\n",
                        hmp->version);
                error = ERANGE;
                goto done;
        }

        /*
         * The undo_rec_limit limits the size of flush groups to avoid
         * blowing out the UNDO FIFO.  This calculation is typically in
         * the tens of thousands and is designed primarily when small
         * HAMMER filesystems are created.
         */
        hmp->undo_rec_limit = hammer_undo_max(hmp) / 8192 + 100;
        if (hammer_debug_general & 0x0001)
                kprintf("HAMMER: undo_rec_limit %d\n", hmp->undo_rec_limit);

        error = hammer_recover(hmp, rootvol);
        if (error) {
                kprintf("Failed to recover HAMMER filesystem on mount\n");
                goto done;
        }

        /*
         * Finish setup now that we have a good root volume.
         *
         * The top 16 bits of fsid.val[1] is a pfs id.
         */
        ksnprintf(mp->mnt_stat.f_mntfromname,
                  sizeof(mp->mnt_stat.f_mntfromname), "%s",
                  rootvol->ondisk->vol_name);
        mp->mnt_stat.f_fsid.val[0] =
                crc32((char *)&rootvol->ondisk->vol_fsid + 0, 8);
        mp->mnt_stat.f_fsid.val[1] =
                crc32((char *)&rootvol->ondisk->vol_fsid + 8, 8);
        mp->mnt_stat.f_fsid.val[1] &= 0x0000FFFF;

        mp->mnt_vstat.f_fsid_uuid = rootvol->ondisk->vol_fsid;
        mp->mnt_vstat.f_fsid = crc32(&mp->mnt_vstat.f_fsid_uuid,
                                     sizeof(mp->mnt_vstat.f_fsid_uuid));

        /*
         * Certain often-modified fields in the root volume are cached in
         * the hammer_mount structure so we do not have to generate lots
         * of little UNDO structures for them.
         *
         * Recopy after recovery.  This also has the side effect of
         * setting our cached undo FIFO's first_offset, which serves to
         * placemark the FIFO start for the NEXT flush cycle while the
         * on-disk first_offset represents the LAST flush cycle.
         */
        hmp->next_tid = rootvol->ondisk->vol0_next_tid;
        hmp->flush_tid1 = hmp->next_tid;
        hmp->flush_tid2 = hmp->next_tid;
        bcopy(rootvol->ondisk->vol0_blockmap, hmp->blockmap,
              sizeof(hmp->blockmap));
        hmp->copy_stat_freebigblocks = rootvol->ondisk->vol0_stat_freebigblocks;

        hammer_flusher_create(hmp);

        /*
         * Locate the root directory using the root cluster's B-Tree as a
         * starting point.  The root directory uses an obj_id of 1.
         *
         * FUTURE: Leave the root directory cached referenced but unlocked
         * in hmp->rootvp (need to flush it on unmount).
         */
        error = hammer_vfs_vget(mp, NULL, 1, &rootvp);
        if (error)
                goto done;
        vput(rootvp);
        /*vn_unlock(hmp->rootvp);*/

done:
        hammer_rel_volume(rootvol, 0);
failed:
        /*
         * Cleanup and return.
         */
        if (error)
                hammer_free_hmp(mp);
        return (error);
}

static int
hammer_vfs_unmount(struct mount *mp, int mntflags)
{
#if 0
        struct hammer_mount *hmp = (void *)mp->mnt_data;
#endif
        int flags;
        int error;

        /*
         * Clean out the vnodes
         */
        flags = 0;
        if (mntflags & MNT_FORCE)
                flags |= FORCECLOSE;
        if ((error = vflush(mp, 0, flags)) != 0)
                return (error);

        /*
         * Clean up the internal mount structure and related entities.  This
         * may issue I/O.
         */
        hammer_free_hmp(mp);
        return(0);
}

/*
 * Clean up the internal mount structure and disassociate it from the mount.
 * This may issue I/O.
 */
static void
hammer_free_hmp(struct mount *mp)
{
        struct hammer_mount *hmp = (void *)mp->mnt_data;
        hammer_flush_group_t flg;
        int count;
        int dummy;

        /*
         * Flush anything dirty.  This won't even run if the
         * filesystem errored-out.
         */
        count = 0;
        while (hammer_flusher_haswork(hmp)) {
                hammer_flusher_sync(hmp);
                ++count;
                if (count >= 5) {
                        if (count == 5)
                                kprintf("HAMMER: umount flushing.");
                        else
                                kprintf(".");
                        tsleep(&dummy, 0, "hmrufl", hz);
                }
                if (count == 30) {
                        kprintf("giving up\n");
                        break;
                }
        }
        if (count >= 5 && count < 30)
                kprintf("\n");

        /*
         * If the mount had a critical error we have to destroy any
         * remaining inodes before we can finish cleaning up the flusher.
         */
        if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) {
                RB_SCAN(hammer_ino_rb_tree, &hmp->rb_inos_root, NULL,
                        hammer_destroy_inode_callback, NULL);
        }

        /*
         * There shouldn't be any inodes left now and any left over
         * flush groups should now be empty.
         */
        KKASSERT(RB_EMPTY(&hmp->rb_inos_root));
        while ((flg = TAILQ_FIRST(&hmp->flush_group_list)) != NULL) {
                TAILQ_REMOVE(&hmp->flush_group_list, flg, flush_entry);
                KKASSERT(TAILQ_EMPTY(&flg->flush_list));
                if (flg->refs) {
                        kprintf("HAMMER: Warning, flush_group %p was "
                                "not empty on umount!\n", flg);
                }
                kfree(flg, hmp->m_misc);
        }

        /*
         * We can finally destroy the flusher
         */
        hammer_flusher_destroy(hmp);

        /*
         * We may have held recovered buffers due to a read-only mount.
         * These must be discarded.
         */
        if (hmp->ronly)
                hammer_recover_flush_buffers(hmp, NULL, -1);

        /*
         * Unload buffers and then volumes
         */
        RB_SCAN(hammer_buf_rb_tree, &hmp->rb_bufs_root, NULL,
                hammer_unload_buffer, NULL);
        RB_SCAN(hammer_vol_rb_tree, &hmp->rb_vols_root, NULL,
                hammer_unload_volume, NULL);

        mp->mnt_data = NULL;
        mp->mnt_flag &= ~MNT_LOCAL;
        hmp->mp = NULL;
        hammer_destroy_objid_cache(hmp);
        kmalloc_destroy(&hmp->m_misc);
        kmalloc_destroy(&hmp->m_inodes);
        kfree(hmp, M_HAMMER);
}

/*
 * Report critical errors.  ip may be NULL.
 */
void
hammer_critical_error(hammer_mount_t hmp, hammer_inode_t ip,
                      int error, const char *msg)
{
        hmp->flags |= HAMMER_MOUNT_CRITICAL_ERROR;
        krateprintf(&hmp->krate,
                "HAMMER(%s): Critical error inode=%lld %s\n",
                hmp->mp->mnt_stat.f_mntfromname,
                (long long)(ip ? ip->obj_id : -1), msg);
        if (hmp->ronly == 0) {
                hmp->ronly = 2;         /* special errored read-only mode */
                hmp->mp->mnt_flag |= MNT_RDONLY;
                kprintf("HAMMER(%s): Forcing read-only mode\n",
                        hmp->mp->mnt_stat.f_mntfromname);
        }
        hmp->error = error;
}


/*
 * Obtain a vnode for the specified inode number.  An exclusively locked
 * vnode is returned.
 */
int
hammer_vfs_vget(struct mount *mp, struct vnode *dvp,
                ino_t ino, struct vnode **vpp)
{
        struct hammer_transaction trans;
        struct hammer_mount *hmp = (void *)mp->mnt_data;
        struct hammer_inode *ip;
        int error;
        u_int32_t localization;

        hammer_simple_transaction(&trans, hmp);

        /*
         * If a directory vnode is supplied (mainly NFS) then we can acquire
         * the PFS domain from it.  Otherwise we would only be able to vget
         * inodes in the root PFS.
         */
        if (dvp) {
                localization = HAMMER_DEF_LOCALIZATION +
                                VTOI(dvp)->obj_localization;
        } else {
                localization = HAMMER_DEF_LOCALIZATION;
        }

        /*
         * Lookup the requested HAMMER inode.  The structure must be
         * left unlocked while we manipulate the related vnode to avoid
         * a deadlock.
         */
        ip = hammer_get_inode(&trans, NULL, ino,
                              hmp->asof, localization,
                              0, &error);
        if (ip == NULL) {
                *vpp = NULL;
                hammer_done_transaction(&trans);
                return(error);
        }
        error = hammer_get_vnode(ip, vpp);
        hammer_rel_inode(ip, 0);
        hammer_done_transaction(&trans);
        return (error);
}

/*
 * Return the root vnode for the filesystem.
 *
 * HAMMER stores the root vnode in the hammer_mount structure so
 * getting it is easy.
 */
static int
hammer_vfs_root(struct mount *mp, struct vnode **vpp)
{
#if 0
        struct hammer_mount *hmp = (void *)mp->mnt_data;
#endif
        int error;

        error = hammer_vfs_vget(mp, NULL, 1, vpp);
        return (error);
}

static int
hammer_vfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
{
        struct hammer_mount *hmp = (void *)mp->mnt_data;
        hammer_volume_t volume;
        hammer_volume_ondisk_t ondisk;
        int error;
        int64_t bfree;
        int64_t breserved;

        volume = hammer_get_root_volume(hmp, &error);
        if (error)
                return(error);
        ondisk = volume->ondisk;

        /*
         * Basic stats
         */
        _hammer_checkspace(hmp, HAMMER_CHKSPC_WRITE, &breserved);
        mp->mnt_stat.f_files = ondisk->vol0_stat_inodes;
        bfree = ondisk->vol0_stat_freebigblocks * HAMMER_LARGEBLOCK_SIZE;
        hammer_rel_volume(volume, 0);

        mp->mnt_stat.f_bfree = (bfree - breserved) / HAMMER_BUFSIZE;
        mp->mnt_stat.f_bavail = mp->mnt_stat.f_bfree;
        if (mp->mnt_stat.f_files < 0)
                mp->mnt_stat.f_files = 0;

        *sbp = mp->mnt_stat;
        return(0);
}

static int
hammer_vfs_statvfs(struct mount *mp, struct statvfs *sbp, struct ucred *cred)
{
        struct hammer_mount *hmp = (void *)mp->mnt_data;
        hammer_volume_t volume;
        hammer_volume_ondisk_t ondisk;
        int error;
        int64_t bfree;
        int64_t breserved;

        volume = hammer_get_root_volume(hmp, &error);
        if (error)
                return(error);
        ondisk = volume->ondisk;

        /*
         * Basic stats
         */
        _hammer_checkspace(hmp, HAMMER_CHKSPC_WRITE, &breserved);
        mp->mnt_vstat.f_files = ondisk->vol0_stat_inodes;
        bfree = ondisk->vol0_stat_freebigblocks * HAMMER_LARGEBLOCK_SIZE;
        hammer_rel_volume(volume, 0);

        mp->mnt_vstat.f_bfree = (bfree - breserved) / HAMMER_BUFSIZE;
        mp->mnt_vstat.f_bavail = mp->mnt_stat.f_bfree;
        if (mp->mnt_vstat.f_files < 0)
                mp->mnt_vstat.f_files = 0;
        *sbp = mp->mnt_vstat;
        return(0);
}

/*
 * Sync the filesystem.  Currently we have to run it twice, the second
 * one will advance the undo start index to the end index, so if a crash
 * occurs no undos will be run on mount.
 *
 * We do not sync the filesystem if we are called from a panic.  If we did
 * we might end up blowing up a sync that was already in progress.
 */
static int
hammer_vfs_sync(struct mount *mp, int waitfor)
{
        struct hammer_mount *hmp = (void *)mp->mnt_data;
        int error;

        if (panicstr == NULL) {
                error = hammer_sync_hmp(hmp, waitfor);
        } else {
                error = EIO;
        }
        return (error);
}

/*
 * Convert a vnode to a file handle.
 */
static int
hammer_vfs_vptofh(struct vnode *vp, struct fid *fhp)
{
        hammer_inode_t ip;

        KKASSERT(MAXFIDSZ >= 16);
        ip = VTOI(vp);
        fhp->fid_len = offsetof(struct fid, fid_data[16]);
        fhp->fid_ext = ip->obj_localization >> 16;
        bcopy(&ip->obj_id, fhp->fid_data + 0, sizeof(ip->obj_id));
        bcopy(&ip->obj_asof, fhp->fid_data + 8, sizeof(ip->obj_asof));
        return(0);
}


/*
 * Convert a file handle back to a vnode.
 *
 * Use rootvp to enforce PFS isolation when a PFS is exported via a
 * null mount.
 */
static int
hammer_vfs_fhtovp(struct mount *mp, struct vnode *rootvp,
                  struct fid *fhp, struct vnode **vpp)
{
        struct hammer_transaction trans;
        struct hammer_inode *ip;
        struct hammer_inode_info info;
        int error;
        u_int32_t localization;

        bcopy(fhp->fid_data + 0, &info.obj_id, sizeof(info.obj_id));
        bcopy(fhp->fid_data + 8, &info.obj_asof, sizeof(info.obj_asof));
        if (rootvp)
                localization = VTOI(rootvp)->obj_localization;
        else
                localization = (u_int32_t)fhp->fid_ext << 16;

        hammer_simple_transaction(&trans, (void *)mp->mnt_data);

        /*
         * Get/allocate the hammer_inode structure.  The structure must be
         * unlocked while we manipulate the related vnode to avoid a
         * deadlock.
         */
        ip = hammer_get_inode(&trans, NULL, info.obj_id,
                              info.obj_asof, localization, 0, &error);
        if (ip == NULL) {
                *vpp = NULL;
                return(error);
        }
        error = hammer_get_vnode(ip, vpp);
        hammer_rel_inode(ip, 0);
        hammer_done_transaction(&trans);
        return (error);
}

static int
hammer_vfs_checkexp(struct mount *mp, struct sockaddr *nam,
                    int *exflagsp, struct ucred **credanonp)
{
        hammer_mount_t hmp = (void *)mp->mnt_data;
        struct netcred *np;
        int error;

        np = vfs_export_lookup(mp, &hmp->export, nam);
        if (np) {
                *exflagsp = np->netc_exflags;
                *credanonp = &np->netc_anon;
                error = 0;
        } else {
                error = EACCES;
        }
        return (error);

}

int
hammer_vfs_export(struct mount *mp, int op, const struct export_args *export)
{
        hammer_mount_t hmp = (void *)mp->mnt_data;
        int error;

        switch(op) {
        case MOUNTCTL_SET_EXPORT:
                error = vfs_export(mp, &hmp->export, export);
                break;
        default:
                error = EOPNOTSUPP;
                break;
        }
        return(error);
}