kernel - Fix bogus compiler warning

[dragonfly.git] / sbin / hammer / cmd_mirror.c

/*
 * Copyright (c) 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/sbin/hammer/cmd_mirror.c,v 1.16 2008/11/09 05:22:56 dillon Exp $
 */

#include "hammer.h"

#define SERIALBUF_SIZE  (512 * 1024)

typedef struct histogram {
        hammer_tid_t    tid;
        u_int64_t       bytes;
} *histogram_t;

static int read_mrecords(int fd, char *buf, u_int size,
                         hammer_ioc_mrecord_head_t pickup);
static int generate_histogram(int fd, const char *filesystem,
                         histogram_t *histogram_ary,
                         struct hammer_ioc_mirror_rw *mirror_base);
static hammer_ioc_mrecord_any_t read_mrecord(int fdin, int *errorp,
                         hammer_ioc_mrecord_head_t pickup);
static void write_mrecord(int fdout, u_int32_t type,
                         hammer_ioc_mrecord_any_t mrec, int bytes);
static void generate_mrec_header(int fd, int pfs_id,
                         union hammer_ioc_mrecord_any *mrec_tmp);
static int validate_mrec_header(int fd, int fdin, int is_target, int pfs_id,
                         struct hammer_ioc_mrecord_head *pickup,
                         hammer_tid_t *tid_begp, hammer_tid_t *tid_endp);
static void update_pfs_snapshot(int fd, hammer_tid_t snapshot_tid, int pfs_id);
static ssize_t writebw(int fd, const void *buf, size_t nbytes,
                        u_int64_t *bwcount, struct timeval *tv1);
static int getyn(void);
static void mirror_usage(int code);

/*
 * Generate a mirroring data stream from the specific source over the
 * entire key range, but restricted to the specified transaction range.
 *
 * The HAMMER VFS does most of the work, we add a few new mrecord
 * types to negotiate the TID ranges and verify that the entire
 * stream made it to the destination.
 */
void
hammer_cmd_mirror_read(char **av, int ac, int streaming)
{
        struct hammer_ioc_mirror_rw mirror;
        struct hammer_ioc_pseudofs_rw pfs;
        union hammer_ioc_mrecord_any mrec_tmp;
        struct hammer_ioc_mrecord_head pickup;
        hammer_ioc_mrecord_any_t mrec;
        hammer_tid_t sync_tid;
        histogram_t histogram_ary;
        const char *filesystem;
        char *buf = malloc(SERIALBUF_SIZE);
        int interrupted = 0;
        int error;
        int fd;
        int n;
        int didwork;
        int histogram;
        int histindex;
        int histmax;
        int64_t total_bytes;
        time_t base_t = time(NULL);
        struct timeval bwtv;
        u_int64_t bwcount;
        u_int64_t estbytes;

        if (ac == 0 || ac > 2)
                mirror_usage(1);
        filesystem = av[0];

        pickup.signature = 0;
        pickup.type = 0;
        histogram = 0;
        histindex = 0;
        histmax = 0;
        histogram_ary = NULL;

again:
        bzero(&mirror, sizeof(mirror));
        hammer_key_beg_init(&mirror.key_beg);
        hammer_key_end_init(&mirror.key_end);

        fd = getpfs(&pfs, filesystem);

        if (streaming && VerboseOpt && VerboseOpt < 2) {
                fprintf(stderr, "\nRunning");
                fflush(stderr);
        }
        total_bytes = 0;
        gettimeofday(&bwtv, NULL);
        bwcount = 0;

        /*
         * Send initial header for the purpose of determining the
         * shared-uuid.
         */
        generate_mrec_header(fd, pfs.pfs_id, &mrec_tmp);
        write_mrecord(1, HAMMER_MREC_TYPE_PFSD,
                      &mrec_tmp, sizeof(mrec_tmp.pfs));

        /*
         * In 2-way mode the target will send us a PFS info packet
         * first.  Use the target's current snapshot TID as our default
         * begin TID.
         */
        mirror.tid_beg = 0;
        if (TwoWayPipeOpt) {
                n = validate_mrec_header(fd, 0, 0, pfs.pfs_id, &pickup,
                                         NULL, &mirror.tid_beg);
                if (n < 0) {    /* got TERM record */
                        relpfs(fd, &pfs);
                        return;
                }
                ++mirror.tid_beg;
        }

        /*
         * Write out the PFS header, tid_beg will be updated if our PFS
         * has a larger begin sync.  tid_end is set to the latest source
         * TID whos flush cycle has completed.
         */
        generate_mrec_header(fd, pfs.pfs_id, &mrec_tmp);
        if (mirror.tid_beg < mrec_tmp.pfs.pfsd.sync_beg_tid)
                mirror.tid_beg = mrec_tmp.pfs.pfsd.sync_beg_tid;
        mirror.tid_end = mrec_tmp.pfs.pfsd.sync_end_tid;
        mirror.ubuf = buf;
        mirror.size = SERIALBUF_SIZE;
        mirror.pfs_id = pfs.pfs_id;
        mirror.shared_uuid = pfs.ondisk->shared_uuid;

        /*
         * XXX If the histogram is exhausted and the TID delta is large
         *     the stream might have been offline for a while and is
         *     now picking it up again.  Do another histogram.
         */
#if 0
        if (TwoWayPipeOpt && streaming && histogram && histindex == histend) {
                if (mirror.tid_end - mirror.tid_beg > BULK_MINIMUM)
                        histogram = 0;
        }
#endif

        /*
         * Initial bulk startup control, try to do some incremental
         * mirroring in order to allow the stream to be killed and
         * restarted without having to start over.
         */
        if (histogram == 0 && BulkOpt == 0) {
                if (VerboseOpt)
                        fprintf(stderr, "\n");
                histmax = generate_histogram(fd, filesystem,
                                             &histogram_ary, &mirror);
                histindex = 0;
                histogram = 1;
        }

        if (TwoWayPipeOpt && streaming && histogram) {
                ++histindex;
                mirror.tid_end = histogram_ary[histindex].tid;
                estbytes = histogram_ary[histindex-1].bytes;
                mrec_tmp.pfs.pfsd.sync_end_tid = mirror.tid_end;
        } else {
                estbytes = 0;
        }

        write_mrecord(1, HAMMER_MREC_TYPE_PFSD,
                      &mrec_tmp, sizeof(mrec_tmp.pfs));

        /*
         * A cycle file overrides the beginning TID only if we are
         * not operating in two-way mode.
         */
        if (TwoWayPipeOpt == 0) {
                hammer_get_cycle(&mirror.key_beg, &mirror.tid_beg);
        }

        /*
         * An additional argument overrides the beginning TID regardless
         * of what mode we are in.  This is not recommending if operating
         * in two-way mode.
         */
        if (ac == 2)
                mirror.tid_beg = strtoull(av[1], NULL, 0);

        if (streaming == 0 || VerboseOpt >= 2) {
                fprintf(stderr,
                        "Mirror-read: Mirror %016jx to %016jx",
                        (uintmax_t)mirror.tid_beg, (uintmax_t)mirror.tid_end);
                if (histogram)
                        fprintf(stderr, " (bulk= %ju)", (uintmax_t)estbytes);
                fprintf(stderr, "\n");
                fflush(stderr);
        }
        if (mirror.key_beg.obj_id != (int64_t)HAMMER_MIN_OBJID) {
                fprintf(stderr, "Mirror-read: Resuming at object %016jx\n",
                        (uintmax_t)mirror.key_beg.obj_id);
        }

        /*
         * Nothing to do if begin equals end.
         */
        if (mirror.tid_beg >= mirror.tid_end) {
                if (streaming == 0 || VerboseOpt >= 2)
                        fprintf(stderr, "Mirror-read: No work to do\n");
                didwork = 0;
                goto done;
        }
        didwork = 1;

        /*
         * Write out bulk records
         */
        mirror.ubuf = buf;
        mirror.size = SERIALBUF_SIZE;

        do {
                mirror.count = 0;
                mirror.pfs_id = pfs.pfs_id;
                mirror.shared_uuid = pfs.ondisk->shared_uuid;
                if (ioctl(fd, HAMMERIOC_MIRROR_READ, &mirror) < 0) {
                        fprintf(stderr, "Mirror-read %s failed: %s\n",
                                filesystem, strerror(errno));
                        exit(1);
                }
                if (mirror.head.flags & HAMMER_IOC_HEAD_ERROR) {
                        fprintf(stderr,
                                "Mirror-read %s fatal error %d\n",
                                filesystem, mirror.head.error);
                        exit(1);
                }
                if (mirror.count) {
                        if (BandwidthOpt) {
                                n = writebw(1, mirror.ubuf, mirror.count,
                                            &bwcount, &bwtv);
                        } else {
                                n = write(1, mirror.ubuf, mirror.count);
                        }
                        if (n != mirror.count) {
                                fprintf(stderr, "Mirror-read %s failed: "
                                                "short write\n",
                                filesystem);
                                exit(1);
                        }
                }
                total_bytes += mirror.count;
                if (streaming && VerboseOpt) {
                        fprintf(stderr,
                                "\robj=%016jx tids=%016jx:%016jx %11jd",
                                (uintmax_t)mirror.key_cur.obj_id,
                                (uintmax_t)mirror.tid_beg,
                                (uintmax_t)mirror.tid_end,
                                (intmax_t)total_bytes);
                        fflush(stderr);
                }
                mirror.key_beg = mirror.key_cur;

                /*
                 * Deal with time limit option
                 */
                if (TimeoutOpt &&
                    (unsigned)(time(NULL) - base_t) > (unsigned)TimeoutOpt) {
                        fprintf(stderr,
                                "Mirror-read %s interrupted by timer at"
                                " %016jx\n",
                                filesystem,
                                (uintmax_t)mirror.key_cur.obj_id);
                        interrupted = 1;
                        break;
                }
        } while (mirror.count != 0);

done:
        if (streaming && VerboseOpt) {
                fprintf(stderr, "\n");
                fflush(stderr);
        }

        /*
         * Write out the termination sync record - only if not interrupted
         */
        if (interrupted == 0) {
                if (didwork) {
                        write_mrecord(1, HAMMER_MREC_TYPE_SYNC,
                                      &mrec_tmp, sizeof(mrec_tmp.sync));
                } else {
                        write_mrecord(1, HAMMER_MREC_TYPE_IDLE,
                                      &mrec_tmp, sizeof(mrec_tmp.sync));
                }
        }

        /*
         * If the -2 option was given (automatic when doing mirror-copy),
         * a two-way pipe is assumed and we expect a response mrec from
         * the target.
         */
        if (TwoWayPipeOpt) {
                mrec = read_mrecord(0, &error, &pickup);
                if (mrec == NULL || 
                    mrec->head.type != HAMMER_MREC_TYPE_UPDATE ||
                    mrec->head.rec_size != sizeof(mrec->update)) {
                        fprintf(stderr, "mirror_read: Did not get final "
                                        "acknowledgement packet from target\n");
                        exit(1);
                }
                if (interrupted) {
                        if (CyclePath) {
                                hammer_set_cycle(&mirror.key_cur,
                                                 mirror.tid_beg);
                                fprintf(stderr, "Cyclefile %s updated for "
                                        "continuation\n", CyclePath);
                        }
                } else {
                        sync_tid = mrec->update.tid;
                        if (CyclePath) {
                                hammer_key_beg_init(&mirror.key_beg);
                                hammer_set_cycle(&mirror.key_beg, sync_tid);
                                fprintf(stderr,
                                        "Cyclefile %s updated to 0x%016jx\n",
                                        CyclePath, (uintmax_t)sync_tid);
                        }
                }
        } else if (CyclePath) {
                /* NOTE! mirror.tid_beg cannot be updated */
                fprintf(stderr, "Warning: cycle file (-c option) cannot be "
                                "fully updated unless you use mirror-copy\n");
                hammer_set_cycle(&mirror.key_beg, mirror.tid_beg);
        }
        if (streaming && interrupted == 0) {
                time_t t1 = time(NULL);
                time_t t2;

                /*
                 * Two way streaming tries to break down large bulk
                 * transfers into smaller ones so it can sync the
                 * transaction id on the slave.  This way if we get
                 * interrupted a restart doesn't have to start from
                 * scratch.
                 */
                if (TwoWayPipeOpt && streaming && histogram) {
                        if (histindex != histmax) {
                                if (VerboseOpt && VerboseOpt < 2)
                                        fprintf(stderr, " (bulk incremental)");
                                goto again;
                        }
                }

                if (VerboseOpt) {
                        fprintf(stderr, " W");
                        fflush(stderr);
                }
                pfs.ondisk->sync_end_tid = mirror.tid_end;
                if (ioctl(fd, HAMMERIOC_WAI_PSEUDOFS, &pfs) < 0) {
                        fprintf(stderr, "Mirror-read %s: cannot stream: %s\n",
                                filesystem, strerror(errno));
                } else {
                        t2 = time(NULL) - t1;
                        if (t2 >= 0 && t2 < DelayOpt) {
                                if (VerboseOpt) {
                                        fprintf(stderr, "\bD");
                                        fflush(stderr);
                                }
                                sleep(DelayOpt - t2);
                        }
                        if (VerboseOpt) {
                                fprintf(stderr, "\b ");
                                fflush(stderr);
                        }
                        relpfs(fd, &pfs);
                        goto again;
                }
        }
        write_mrecord(1, HAMMER_MREC_TYPE_TERM,
                      &mrec_tmp, sizeof(mrec_tmp.sync));
        relpfs(fd, &pfs);
        fprintf(stderr, "Mirror-read %s succeeded\n", filesystem);
}

/*
 * What we are trying to do here is figure out how much data is
 * going to be sent for the TID range and to break the TID range
 * down into reasonably-sized slices (from the point of view of
 * data sent) so a lost connection can restart at a reasonable
 * place and not all the way back at the beginning.
 *
 * An entry's TID serves as the end_tid for the prior entry
 * So we have to offset the calculation by 1 so that TID falls into
 * the previous entry when populating entries.
 *
 * Because the transaction id space is bursty we need a relatively
 * large number of buckets (like a million) to do a reasonable job
 * for things like an initial bulk mirrors on a very large filesystem.
 */
#define HIST_COUNT      (1024 * 1024)

static int
generate_histogram(int fd, const char *filesystem,
                   histogram_t *histogram_ary,
                   struct hammer_ioc_mirror_rw *mirror_base)
{
        struct hammer_ioc_mirror_rw mirror;
        union hammer_ioc_mrecord_any *mrec;
        hammer_tid_t tid_beg;
        hammer_tid_t tid_end;
        hammer_tid_t tid;
        hammer_tid_t tidx;
        u_int64_t *tid_bytes;
        u_int64_t total;
        u_int64_t accum;
        int i;
        int res;
        int off;
        int len;

        mirror = *mirror_base;
        tid_beg = mirror.tid_beg;
        tid_end = mirror.tid_end;
        mirror.head.flags |= HAMMER_IOC_MIRROR_NODATA;

        if (*histogram_ary == NULL) {
                *histogram_ary = malloc(sizeof(struct histogram) *
                                        (HIST_COUNT + 2));
        }
        if (tid_beg >= tid_end)
                return(0);

        /* needs 2 extra */
        tid_bytes = malloc(sizeof(*tid_bytes) * (HIST_COUNT + 2));
        bzero(tid_bytes, sizeof(tid_bytes));

        fprintf(stderr, "Prescan to break up bulk transfer");
        if (VerboseOpt > 1)
                fprintf(stderr, " (%juMB chunks)",
                        (uintmax_t)(SplitupOpt / (1024 * 1024)));
        fprintf(stderr, "\n");

        /*
         * Note: (tid_beg,tid_end), range is inclusive of both beg & end.
         *
         * Note: Estimates can be off when the mirror is way behind due
         *       to skips.
         */
        total = 0;
        accum = 0;
        for (;;) {
                mirror.count = 0;
                if (ioctl(fd, HAMMERIOC_MIRROR_READ, &mirror) < 0) {
                        fprintf(stderr, "Mirror-read %s failed: %s\n",
                                filesystem, strerror(errno));
                        exit(1);
                }
                if (mirror.head.flags & HAMMER_IOC_HEAD_ERROR) {
                        fprintf(stderr,
                                "Mirror-read %s fatal error %d\n",
                                filesystem, mirror.head.error);
                        exit(1);
                }
                for (off = 0;
                     off < mirror.count;
                     off += HAMMER_HEAD_DOALIGN(mrec->head.rec_size)
                ) {
                        mrec = (void *)((char *)mirror.ubuf + off);

                        /*
                         * We only care about general RECs and PASS
                         * records.  We ignore SKIPs.
                         */
                        switch (mrec->head.type & HAMMER_MRECF_TYPE_LOMASK) {
                        case HAMMER_MREC_TYPE_REC:
                        case HAMMER_MREC_TYPE_PASS:
                                break;
                        default:
                                continue;
                        }

                        /*
                         * Calculate for two indices, create_tid and
                         * delete_tid.  Record data only applies to
                         * the create_tid.
                         *
                         * When tid is exactly on the boundary it really
                         * belongs to the previous entry because scans
                         * are inclusive of the ending entry.
                         */
                        tid = mrec->rec.leaf.base.delete_tid;
                        if (tid && tid >= tid_beg && tid <= tid_end) {
                                len = HAMMER_HEAD_DOALIGN(mrec->head.rec_size);
                                if (mrec->head.type ==
                                    HAMMER_MREC_TYPE_REC) {
                                        len -= HAMMER_HEAD_DOALIGN(
                                                    mrec->rec.leaf.data_len);
                                        assert(len > 0);
                                }
                                i = (tid - tid_beg) * HIST_COUNT /
                                    (tid_end - tid_beg);
                                tidx = tid_beg + i * (tid_end - tid_beg) /
                                                 HIST_COUNT;
                                if (tid == tidx && i)
                                        --i;
                                assert(i >= 0 && i < HIST_COUNT);
                                tid_bytes[i] += len;
                                total += len;
                                accum += len;
                        }

                        tid = mrec->rec.leaf.base.create_tid;
                        if (tid && tid >= tid_beg && tid <= tid_end) {
                                len = HAMMER_HEAD_DOALIGN(mrec->head.rec_size);
                                if (mrec->head.type ==
                                    HAMMER_MREC_TYPE_REC_NODATA) {
                                        len += HAMMER_HEAD_DOALIGN(
                                                    mrec->rec.leaf.data_len);
                                }
                                i = (tid - tid_beg) * HIST_COUNT /
                                    (tid_end - tid_beg);
                                tidx = tid_beg + i * (tid_end - tid_beg) /
                                                 HIST_COUNT;
                                if (tid == tidx && i)
                                        --i;
                                assert(i >= 0 && i < HIST_COUNT);
                                tid_bytes[i] += len;
                                total += len;
                                accum += len;
                        }
                }
                if (VerboseOpt > 1) {
                        if (accum > SplitupOpt) {
                                fprintf(stderr, ".");
                                fflush(stderr);
                                accum = 0;
                        }
                }
                if (mirror.count == 0)
                        break;
                mirror.key_beg = mirror.key_cur;
        }

        /*
         * Reduce to SplitupOpt (default 100MB) chunks.  This code may
         * use up to two additional elements.  Do the array in-place.
         *
         * Inefficient degenerate cases can occur if we do not accumulate
         * at least the requested split amount, so error on the side of
         * going over a bit.
         */
        res = 0;
        (*histogram_ary)[res].tid = tid_beg;
        (*histogram_ary)[res].bytes = tid_bytes[0];
        for (i = 1; i < HIST_COUNT; ++i) {
                if ((*histogram_ary)[res].bytes >= SplitupOpt) {
                        ++res;
                        (*histogram_ary)[res].tid = tid_beg +
                                        i * (tid_end - tid_beg) /
                                        HIST_COUNT;
                        (*histogram_ary)[res].bytes = 0;

                }
                (*histogram_ary)[res].bytes += tid_bytes[i];
        }
        ++res;
        (*histogram_ary)[res].tid = tid_end;
        (*histogram_ary)[res].bytes = -1;

        if (VerboseOpt > 1)
                fprintf(stderr, "\n");  /* newline after ... */
        assert(res <= HIST_COUNT);
        fprintf(stderr, "Prescan %d chunks, total %ju MBytes (",
                res, (uintmax_t)total / (1024 * 1024));
        for (i = 0; i < res && i < 3; ++i) {
                if (i)
                        fprintf(stderr, ", ");
                fprintf(stderr, "%ju", (uintmax_t)(*histogram_ary)[i].bytes);
        }
        if (i < res)
                fprintf(stderr, ", ...");
        fprintf(stderr, ")\n");

        free(tid_bytes);
        return(res);
}

static void
create_pfs(const char *filesystem, uuid_t *s_uuid)
{
        if (ForceYesOpt == 1) {
                fprintf(stderr, "PFS slave %s does not exist. "
                        "Auto create new slave PFS!\n", filesystem);

        } else {
                fprintf(stderr, "PFS slave %s does not exist.\n"
                        "Do you want to create a new slave PFS? (yes|no) ",
                        filesystem);
                fflush(stderr);
                if (getyn() != 1) {
                        fprintf(stderr, "Aborting operation\n");
                        exit(1);
                }
        }

        u_int32_t status;
        char *shared_uuid = NULL;
        uuid_to_string(s_uuid, &shared_uuid, &status);

        char *cmd = NULL;
        asprintf(&cmd, "/sbin/hammer pfs-slave '%s' shared-uuid=%s 1>&2",
                 filesystem, shared_uuid); 
        free(shared_uuid);

        if (cmd == NULL) {
                fprintf(stderr, "Failed to alloc memory\n");
                exit(1);
        }
        if (system(cmd) != 0) {
                fprintf(stderr, "Failed to create PFS\n");
        }
        free(cmd);
}

/*
 * Pipe the mirroring data stream on stdin to the HAMMER VFS, adding
 * some additional packet types to negotiate TID ranges and to verify
 * completion.  The HAMMER VFS does most of the work.
 *
 * It is important to note that the mirror.key_{beg,end} range must
 * match the ranged used by the original.  For now both sides use
 * range the entire key space.
 *
 * It is even more important that the records in the stream conform
 * to the TID range also supplied in the stream.  The HAMMER VFS will
 * use the REC, PASS, and SKIP record types to track the portions of
 * the B-Tree being scanned in order to be able to proactively delete
 * records on the target within those active areas that are not mentioned
 * by the source.
 *
 * The mirror.key_cur field is used by the VFS to do this tracking.  It
 * must be initialized to key_beg but then is persistently updated by
 * the HAMMER VFS on each successive ioctl() call.  If you blow up this
 * field you will blow up the mirror target, possibly to the point of
 * deleting everything.  As a safety measure the HAMMER VFS simply marks
 * the records that the source has destroyed as deleted on the target,
 * and normal pruning operations will deal with their final disposition
 * at some later time.
 */
void
hammer_cmd_mirror_write(char **av, int ac)
{
        struct hammer_ioc_mirror_rw mirror;
        const char *filesystem;
        char *buf = malloc(SERIALBUF_SIZE);
        struct hammer_ioc_pseudofs_rw pfs;
        struct hammer_ioc_mrecord_head pickup;
        struct hammer_ioc_synctid synctid;
        union hammer_ioc_mrecord_any mrec_tmp;
        hammer_ioc_mrecord_any_t mrec;
        struct stat st;
        int error;
        int fd;
        int n;

        if (ac != 1)
                mirror_usage(1);
        filesystem = av[0];

        pickup.signature = 0;
        pickup.type = 0;

again:
        bzero(&mirror, sizeof(mirror));
        hammer_key_beg_init(&mirror.key_beg);
        hammer_key_end_init(&mirror.key_end);
        mirror.key_end = mirror.key_beg;

        /*
         * Read initial packet
         */
        mrec = read_mrecord(0, &error, &pickup);
        if (mrec == NULL) {
                if (error == 0)
                        fprintf(stderr, "validate_mrec_header: short read\n");
                exit(1);
        }
        /*
         * Validate packet
         */
        if (mrec->head.type == HAMMER_MREC_TYPE_TERM) {
                return;
        }
        if (mrec->head.type != HAMMER_MREC_TYPE_PFSD) {
                fprintf(stderr, "validate_mrec_header: did not get expected "
                                "PFSD record type\n");
                exit(1);
        }
        if (mrec->head.rec_size != sizeof(mrec->pfs)) {
                fprintf(stderr, "validate_mrec_header: unexpected payload "
                                "size\n");
                exit(1);
        }

        /*
         * Create slave PFS if it doesn't yet exist
         */
        if (lstat(filesystem, &st) != 0) {
                create_pfs(filesystem, &mrec->pfs.pfsd.shared_uuid);
        }
        free(mrec);
        mrec = NULL;

        fd = getpfs(&pfs, filesystem);

        /*
         * In two-way mode the target writes out a PFS packet first.
         * The source uses our tid_end as its tid_beg by default,
         * picking up where it left off.
         */
        mirror.tid_beg = 0;
        if (TwoWayPipeOpt) {
                generate_mrec_header(fd, pfs.pfs_id, &mrec_tmp);
                if (mirror.tid_beg < mrec_tmp.pfs.pfsd.sync_beg_tid)
                        mirror.tid_beg = mrec_tmp.pfs.pfsd.sync_beg_tid;
                mirror.tid_end = mrec_tmp.pfs.pfsd.sync_end_tid;
                write_mrecord(1, HAMMER_MREC_TYPE_PFSD,
                              &mrec_tmp, sizeof(mrec_tmp.pfs));
        }

        /*
         * Read and process the PFS header.  The source informs us of
         * the TID range the stream represents.
         */
        n = validate_mrec_header(fd, 0, 1, pfs.pfs_id, &pickup,
                                 &mirror.tid_beg, &mirror.tid_end);
        if (n < 0) {    /* got TERM record */
                relpfs(fd, &pfs);
                return;
        }

        mirror.ubuf = buf;
        mirror.size = SERIALBUF_SIZE;

        /*
         * Read and process bulk records (REC, PASS, and SKIP types).
         *
         * On your life, do NOT mess with mirror.key_cur or your mirror
         * target may become history.
         */
        for (;;) {
                mirror.count = 0;
                mirror.pfs_id = pfs.pfs_id;
                mirror.shared_uuid = pfs.ondisk->shared_uuid;
                mirror.size = read_mrecords(0, buf, SERIALBUF_SIZE, &pickup);
                if (mirror.size <= 0)
                        break;
                if (ioctl(fd, HAMMERIOC_MIRROR_WRITE, &mirror) < 0) {
                        fprintf(stderr, "Mirror-write %s failed: %s\n",
                                filesystem, strerror(errno));
                        exit(1);
                }
                if (mirror.head.flags & HAMMER_IOC_HEAD_ERROR) {
                        fprintf(stderr,
                                "Mirror-write %s fatal error %d\n",
                                filesystem, mirror.head.error);
                        exit(1);
                }
#if 0
                if (mirror.head.flags & HAMMER_IOC_HEAD_INTR) {
                        fprintf(stderr,
                                "Mirror-write %s interrupted by timer at"
                                " %016llx\n",
                                filesystem,
                                mirror.key_cur.obj_id);
                        exit(0);
                }
#endif
        }

        /*
         * Read and process the termination sync record.
         */
        mrec = read_mrecord(0, &error, &pickup);

        if (mrec && mrec->head.type == HAMMER_MREC_TYPE_TERM) {
                fprintf(stderr, "Mirror-write: received termination request\n");
                free(mrec);
                return;
        }

        if (mrec == NULL || 
            (mrec->head.type != HAMMER_MREC_TYPE_SYNC &&
             mrec->head.type != HAMMER_MREC_TYPE_IDLE) ||
            mrec->head.rec_size != sizeof(mrec->sync)) {
                fprintf(stderr, "Mirror-write %s: Did not get termination "
                                "sync record, or rec_size is wrong rt=%d\n",
                                filesystem, mrec->head.type);
                exit(1);
        }

        /*
         * Update the PFS info on the target so the user has visibility
         * into the new snapshot, and sync the target filesystem.
         */
        if (mrec->head.type == HAMMER_MREC_TYPE_SYNC) {
                update_pfs_snapshot(fd, mirror.tid_end, pfs.pfs_id);

                bzero(&synctid, sizeof(synctid));
                synctid.op = HAMMER_SYNCTID_SYNC2;
                ioctl(fd, HAMMERIOC_SYNCTID, &synctid);

                if (VerboseOpt >= 2) {
                        fprintf(stderr, "Mirror-write %s: succeeded\n",
                                filesystem);
                }
        }

        free(mrec);
        mrec = NULL;

        /*
         * Report back to the originator.
         */
        if (TwoWayPipeOpt) {
                mrec_tmp.update.tid = mirror.tid_end;
                write_mrecord(1, HAMMER_MREC_TYPE_UPDATE,
                              &mrec_tmp, sizeof(mrec_tmp.update));
        } else {
                printf("Source can update synctid to 0x%016jx\n",
                       (uintmax_t)mirror.tid_end);
        }
        relpfs(fd, &pfs);
        goto again;
}

void
hammer_cmd_mirror_dump(void)
{
        char *buf = malloc(SERIALBUF_SIZE);
        struct hammer_ioc_mrecord_head pickup;
        hammer_ioc_mrecord_any_t mrec;
        int error;
        int size;
        int offset;
        int bytes;

        /*
         * Read and process the PFS header 
         */
        pickup.signature = 0;
        pickup.type = 0;

        mrec = read_mrecord(0, &error, &pickup);

        /*
         * Read and process bulk records
         */
        for (;;) {
                size = read_mrecords(0, buf, SERIALBUF_SIZE, &pickup);
                if (size <= 0)
                        break;
                offset = 0;
                while (offset < size) {
                        mrec = (void *)((char *)buf + offset);
                        bytes = HAMMER_HEAD_DOALIGN(mrec->head.rec_size);
                        if (offset + bytes > size) {
                                fprintf(stderr, "Misaligned record\n");
                                exit(1);
                        }

                        switch(mrec->head.type & HAMMER_MRECF_TYPE_MASK) {
                        case HAMMER_MREC_TYPE_REC_BADCRC:
                        case HAMMER_MREC_TYPE_REC:
                                printf("Record obj=%016jx key=%016jx "
                                       "rt=%02x ot=%02x",
                                        (uintmax_t)mrec->rec.leaf.base.obj_id,
                                        (uintmax_t)mrec->rec.leaf.base.key,
                                        mrec->rec.leaf.base.rec_type,
                                        mrec->rec.leaf.base.obj_type);
                                if (mrec->head.type ==
                                    HAMMER_MREC_TYPE_REC_BADCRC) {
                                        printf(" (BAD CRC)");
                                }
                                printf("\n");
                                printf("       tids %016jx:%016jx data=%d\n",
                                    (uintmax_t)mrec->rec.leaf.base.create_tid,
                                    (uintmax_t)mrec->rec.leaf.base.delete_tid,
                                    mrec->rec.leaf.data_len);
                                break;
                        case HAMMER_MREC_TYPE_PASS:
                                printf("Pass   obj=%016jx key=%016jx "
                                       "rt=%02x ot=%02x\n",
                                        (uintmax_t)mrec->rec.leaf.base.obj_id,
                                        (uintmax_t)mrec->rec.leaf.base.key,
                                        mrec->rec.leaf.base.rec_type,
                                        mrec->rec.leaf.base.obj_type);
                                printf("       tids %016jx:%016jx data=%d\n",
                                    (uintmax_t)mrec->rec.leaf.base.create_tid,
                                    (uintmax_t)mrec->rec.leaf.base.delete_tid,
                                        mrec->rec.leaf.data_len);
                                break;
                        case HAMMER_MREC_TYPE_SKIP:
                                printf("Skip   obj=%016jx key=%016jx rt=%02x to\n"
                                       "       obj=%016jx key=%016jx rt=%02x\n",
                                       (uintmax_t)mrec->skip.skip_beg.obj_id,
                                       (uintmax_t)mrec->skip.skip_beg.key,
                                       mrec->skip.skip_beg.rec_type,
                                       (uintmax_t)mrec->skip.skip_end.obj_id,
                                       (uintmax_t)mrec->skip.skip_end.key,
                                       mrec->skip.skip_end.rec_type);
                        default:
                                break;
                        }
                        offset += bytes;
                }
        }

        /*
         * Read and process the termination sync record.
         */
        mrec = read_mrecord(0, &error, &pickup);
        if (mrec == NULL || 
            (mrec->head.type != HAMMER_MREC_TYPE_SYNC &&
             mrec->head.type != HAMMER_MREC_TYPE_IDLE)
         ) {
                fprintf(stderr, "Mirror-dump: Did not get termination "
                                "sync record\n");
        }
}

void
hammer_cmd_mirror_copy(char **av, int ac, int streaming)
{
        pid_t pid1;
        pid_t pid2;
        int fds[2];
        const char *xav[16];
        char tbuf[16];
        char *ptr;
        int xac;

        if (ac != 2)
                mirror_usage(1);

        TwoWayPipeOpt = 1;
        signal(SIGPIPE, SIG_IGN);

again:
        if (pipe(fds) < 0) {
                perror("pipe");
                exit(1);
        }

        /*
         * Source
         */
        if ((pid1 = fork()) == 0) {
                signal(SIGPIPE, SIG_DFL);
                dup2(fds[0], 0);
                dup2(fds[0], 1);
                close(fds[0]);
                close(fds[1]);
                if ((ptr = strchr(av[0], ':')) != NULL) {
                        *ptr++ = 0;
                        xac = 0;
                        xav[xac++] = "ssh";
                        if (CompressOpt)
                                xav[xac++] = "-C";
                        if (SshPort) {
                                xav[xac++] = "-p";
                                xav[xac++] = SshPort;
                        }
                        xav[xac++] = av[0];
                        xav[xac++] = "hammer";

                        switch(VerboseOpt) {
                        case 0:
                                break;
                        case 1:
                                xav[xac++] = "-v";
                                break;
                        case 2:
                                xav[xac++] = "-vv";
                                break;
                        default:
                                xav[xac++] = "-vvv";
                                break;
                        }
                        if (ForceYesOpt) {
                                xav[xac++] = "-y";
                        }
                        xav[xac++] = "-2";
                        if (TimeoutOpt) {
                                snprintf(tbuf, sizeof(tbuf), "%d", TimeoutOpt);
                                xav[xac++] = "-t";
                                xav[xac++] = tbuf;
                        }
                        if (streaming)
                                xav[xac++] = "mirror-read-stream";
                        else
                                xav[xac++] = "mirror-read";
                        xav[xac++] = ptr;
                        xav[xac++] = NULL;
                        execv("/usr/bin/ssh", (void *)xav);
                } else {
                        hammer_cmd_mirror_read(av, 1, streaming);
                        fflush(stdout);
                        fflush(stderr);
                }
                _exit(1);
        }

        /*
         * Target
         */
        if ((pid2 = fork()) == 0) {
                signal(SIGPIPE, SIG_DFL);
                dup2(fds[1], 0);
                dup2(fds[1], 1);
                close(fds[0]);
                close(fds[1]);
                if ((ptr = strchr(av[1], ':')) != NULL) {
                        *ptr++ = 0;
                        xac = 0;
                        xav[xac++] = "ssh";
                        if (CompressOpt)
                                xav[xac++] = "-C";
                        if (SshPort) {
                                xav[xac++] = "-p";
                                xav[xac++] = SshPort;
                        }
                        xav[xac++] = av[1];
                        xav[xac++] = "hammer";

                        switch(VerboseOpt) {
                        case 0:
                                break;
                        case 1:
                                xav[xac++] = "-v";
                                break;
                        case 2:
                                xav[xac++] = "-vv";
                                break;
                        default:
                                xav[xac++] = "-vvv";
                                break;
                        }
                        if (ForceYesOpt) {
                                xav[xac++] = "-y";
                        }
                        xav[xac++] = "-2";
                        xav[xac++] = "mirror-write";
                        xav[xac++] = ptr;
                        xav[xac++] = NULL;
                        execv("/usr/bin/ssh", (void *)xav);
                } else {
                        hammer_cmd_mirror_write(av + 1, 1);
                        fflush(stdout);
                        fflush(stderr);
                }
                _exit(1);
        }
        close(fds[0]);
        close(fds[1]);

        while (waitpid(pid1, NULL, 0) <= 0)
                ;
        while (waitpid(pid2, NULL, 0) <= 0)
                ;

        /*
         * If the link is lost restart
         */
        if (streaming) {
                if (VerboseOpt) {
                        fprintf(stderr, "\nLost Link\n");
                        fflush(stderr);
                }
                sleep(15 + DelayOpt);
                goto again;
        }

}

/*
 * Read and return multiple mrecords
 */
static int
read_mrecords(int fd, char *buf, u_int size, hammer_ioc_mrecord_head_t pickup)
{
        hammer_ioc_mrecord_any_t mrec;
        u_int count;
        size_t n;
        size_t i;
        size_t bytes;
        int type;

        count = 0;
        while (size - count >= HAMMER_MREC_HEADSIZE) {
                /*
                 * Cached the record header in case we run out of buffer
                 * space.
                 */
                fflush(stdout);
                if (pickup->signature == 0) {
                        for (n = 0; n < HAMMER_MREC_HEADSIZE; n += i) {
                                i = read(fd, (char *)pickup + n,
                                         HAMMER_MREC_HEADSIZE - n);
                                if (i <= 0)
                                        break;
                        }
                        if (n == 0)
                                break;
                        if (n != HAMMER_MREC_HEADSIZE) {
                                fprintf(stderr, "read_mrecords: short read on pipe\n");
                                exit(1);
                        }
                        if (pickup->signature != HAMMER_IOC_MIRROR_SIGNATURE) {
                                fprintf(stderr, "read_mrecords: malformed record on pipe, "
                                        "bad signature\n");
                                exit(1);
                        }
                }
                if (pickup->rec_size < HAMMER_MREC_HEADSIZE ||
                    pickup->rec_size > sizeof(*mrec) + HAMMER_XBUFSIZE) {
                        fprintf(stderr, "read_mrecords: malformed record on pipe, "
                                "illegal rec_size\n");
                        exit(1);
                }

                /*
                 * Stop if we have insufficient space for the record and data.
                 */
                bytes = HAMMER_HEAD_DOALIGN(pickup->rec_size);
                if (size - count < bytes)
                        break;

                /*
                 * Stop if the record type is not a REC, SKIP, or PASS,
                 * which are the only types the ioctl supports.  Other types
                 * are used only by the userland protocol.
                 *
                 * Ignore all flags.
                 */
                type = pickup->type & HAMMER_MRECF_TYPE_LOMASK;
                if (type != HAMMER_MREC_TYPE_PFSD &&
                    type != HAMMER_MREC_TYPE_REC &&
                    type != HAMMER_MREC_TYPE_SKIP &&
                    type != HAMMER_MREC_TYPE_PASS) {
                        break;
                }

                /*
                 * Read the remainder and clear the pickup signature.
                 */
                for (n = HAMMER_MREC_HEADSIZE; n < bytes; n += i) {
                        i = read(fd, buf + count + n, bytes - n);
                        if (i <= 0)
                                break;
                }
                if (n != bytes) {
                        fprintf(stderr, "read_mrecords: short read on pipe\n");
                        exit(1);
                }

                bcopy(pickup, buf + count, HAMMER_MREC_HEADSIZE);
                pickup->signature = 0;
                pickup->type = 0;
                mrec = (void *)(buf + count);

                /*
                 * Validate the completed record
                 */
                if (mrec->head.rec_crc !=
                    crc32((char *)mrec + HAMMER_MREC_CRCOFF,
                          mrec->head.rec_size - HAMMER_MREC_CRCOFF)) {
                        fprintf(stderr, "read_mrecords: malformed record "
                                        "on pipe, bad crc\n");
                        exit(1);
                }

                /*
                 * If its a B-Tree record validate the data crc.
                 *
                 * NOTE: If the VFS passes us an explicitly errorde mrec
                 *       we just pass it through.
                 */
                type = mrec->head.type & HAMMER_MRECF_TYPE_MASK;

                if (type == HAMMER_MREC_TYPE_REC) {
                        if (mrec->head.rec_size <
                            sizeof(mrec->rec) + mrec->rec.leaf.data_len) {
                                fprintf(stderr, 
                                        "read_mrecords: malformed record on "
                                        "pipe, illegal element data_len\n");
                                exit(1);
                        }
                        if (mrec->rec.leaf.data_len &&
                            mrec->rec.leaf.data_offset &&
                            hammer_crc_test_leaf(&mrec->rec + 1, &mrec->rec.leaf) == 0) {
                                fprintf(stderr,
                                        "read_mrecords: data_crc did not "
                                        "match data! obj=%016jx key=%016jx\n",
                                        (uintmax_t)mrec->rec.leaf.base.obj_id,
                                        (uintmax_t)mrec->rec.leaf.base.key);
                                fprintf(stderr,
                                        "continuing, but there are problems\n");
                        }
                }
                count += bytes;
        }
        return(count);
}

/*
 * Read and return a single mrecord.
 */
static
hammer_ioc_mrecord_any_t
read_mrecord(int fdin, int *errorp, hammer_ioc_mrecord_head_t pickup)
{
        hammer_ioc_mrecord_any_t mrec;
        struct hammer_ioc_mrecord_head mrechd;
        size_t bytes;
        size_t n;
        size_t i;

        if (pickup && pickup->type != 0) {
                mrechd = *pickup;
                pickup->signature = 0;
                pickup->type = 0;
                n = HAMMER_MREC_HEADSIZE;
        } else {
                /*
                 * Read in the PFSD header from the sender.
                 */
                for (n = 0; n < HAMMER_MREC_HEADSIZE; n += i) {
                        i = read(fdin, (char *)&mrechd + n, HAMMER_MREC_HEADSIZE - n);
                        if (i <= 0)
                                break;
                }
                if (n == 0) {
                        *errorp = 0;    /* EOF */
                        return(NULL);
                }
                if (n != HAMMER_MREC_HEADSIZE) {
                        fprintf(stderr, "short read of mrecord header\n");
                        *errorp = EPIPE;
                        return(NULL);
                }
        }
        if (mrechd.signature != HAMMER_IOC_MIRROR_SIGNATURE) {
                fprintf(stderr, "read_mrecord: bad signature\n");
                *errorp = EINVAL;
                return(NULL);
        }
        bytes = HAMMER_HEAD_DOALIGN(mrechd.rec_size);
        assert(bytes >= sizeof(mrechd));
        mrec = malloc(bytes);
        mrec->head = mrechd;

        while (n < bytes) {
                i = read(fdin, (char *)mrec + n, bytes - n);
                if (i <= 0)
                        break;
                n += i;
        }
        if (n != bytes) {
                fprintf(stderr, "read_mrecord: short read on payload\n");
                *errorp = EPIPE;
                return(NULL);
        }
        if (mrec->head.rec_crc != 
            crc32((char *)mrec + HAMMER_MREC_CRCOFF,
                  mrec->head.rec_size - HAMMER_MREC_CRCOFF)) {
                fprintf(stderr, "read_mrecord: bad CRC\n");
                *errorp = EINVAL;
                return(NULL);
        }
        *errorp = 0;
        return(mrec);
}

static
void
write_mrecord(int fdout, u_int32_t type, hammer_ioc_mrecord_any_t mrec,
              int bytes)
{
        char zbuf[HAMMER_HEAD_ALIGN];
        int pad;

        pad = HAMMER_HEAD_DOALIGN(bytes) - bytes;

        assert(bytes >= (int)sizeof(mrec->head));
        bzero(&mrec->head, sizeof(mrec->head));
        mrec->head.signature = HAMMER_IOC_MIRROR_SIGNATURE;
        mrec->head.type = type;
        mrec->head.rec_size = bytes;
        mrec->head.rec_crc = crc32((char *)mrec + HAMMER_MREC_CRCOFF,
                                   bytes - HAMMER_MREC_CRCOFF);
        if (write(fdout, mrec, bytes) != bytes) {
                fprintf(stderr, "write_mrecord: error %d (%s)\n",
                        errno, strerror(errno));
                exit(1);
        }
        if (pad) {
                bzero(zbuf, pad);
                if (write(fdout, zbuf, pad) != pad) {
                        fprintf(stderr, "write_mrecord: error %d (%s)\n",
                                errno, strerror(errno));
                        exit(1);
                }
        }
}

/*
 * Generate a mirroring header with the pfs information of the
 * originating filesytem.
 */
static void
generate_mrec_header(int fd, int pfs_id,
                     union hammer_ioc_mrecord_any *mrec_tmp)
{
        struct hammer_ioc_pseudofs_rw pfs;

        bzero(&pfs, sizeof(pfs));
        bzero(mrec_tmp, sizeof(*mrec_tmp));
        pfs.pfs_id = pfs_id;
        pfs.ondisk = &mrec_tmp->pfs.pfsd;
        pfs.bytes = sizeof(mrec_tmp->pfs.pfsd);
        if (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) != 0) {
                fprintf(stderr, "Mirror-read: not a HAMMER fs/pseudofs!\n");
                exit(1);
        }
        if (pfs.version != HAMMER_IOC_PSEUDOFS_VERSION) {
                fprintf(stderr, "Mirror-read: HAMMER pfs version mismatch!\n");
                exit(1);
        }
        mrec_tmp->pfs.version = pfs.version;
}

/*
 * Validate the pfs information from the originating filesystem
 * against the target filesystem.  shared_uuid must match.
 *
 * return -1 if we got a TERM record
 */
static int
validate_mrec_header(int fd, int fdin, int is_target, int pfs_id,
                     struct hammer_ioc_mrecord_head *pickup,
                     hammer_tid_t *tid_begp, hammer_tid_t *tid_endp)
{
        struct hammer_ioc_pseudofs_rw pfs;
        struct hammer_pseudofs_data pfsd;
        hammer_ioc_mrecord_any_t mrec;
        int error;

        /*
         * Get the PFSD info from the target filesystem.
         */
        bzero(&pfs, sizeof(pfs));
        bzero(&pfsd, sizeof(pfsd));
        pfs.pfs_id = pfs_id;
        pfs.ondisk = &pfsd;
        pfs.bytes = sizeof(pfsd);
        if (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) != 0) {
                fprintf(stderr, "mirror-write: not a HAMMER fs/pseudofs!\n");
                exit(1);
        }
        if (pfs.version != HAMMER_IOC_PSEUDOFS_VERSION) {
                fprintf(stderr, "mirror-write: HAMMER pfs version mismatch!\n");
                exit(1);
        }

        mrec = read_mrecord(fdin, &error, pickup);
        if (mrec == NULL) {
                if (error == 0)
                        fprintf(stderr, "validate_mrec_header: short read\n");
                exit(1);
        }
        if (mrec->head.type == HAMMER_MREC_TYPE_TERM) {
                free(mrec);
                return(-1);
        }

        if (mrec->head.type != HAMMER_MREC_TYPE_PFSD) {
                fprintf(stderr, "validate_mrec_header: did not get expected "
                                "PFSD record type\n");
                exit(1);
        }
        if (mrec->head.rec_size != sizeof(mrec->pfs)) {
                fprintf(stderr, "validate_mrec_header: unexpected payload "
                                "size\n");
                exit(1);
        }
        if (mrec->pfs.version != pfs.version) {
                fprintf(stderr, "validate_mrec_header: Version mismatch\n");
                exit(1);
        }

        /*
         * Whew.  Ok, is the read PFS info compatible with the target?
         */
        if (bcmp(&mrec->pfs.pfsd.shared_uuid, &pfsd.shared_uuid,
                 sizeof(pfsd.shared_uuid)) != 0) {
                fprintf(stderr, 
                        "mirror-write: source and target have "
                        "different shared-uuid's!\n");
                exit(1);
        }
        if (is_target &&
            (pfsd.mirror_flags & HAMMER_PFSD_SLAVE) == 0) {
                fprintf(stderr, "mirror-write: target must be in slave mode\n");
                exit(1);
        }
        if (tid_begp)
                *tid_begp = mrec->pfs.pfsd.sync_beg_tid;
        if (tid_endp)
                *tid_endp = mrec->pfs.pfsd.sync_end_tid;
        free(mrec);
        return(0);
}

static void
update_pfs_snapshot(int fd, hammer_tid_t snapshot_tid, int pfs_id)
{
        struct hammer_ioc_pseudofs_rw pfs;
        struct hammer_pseudofs_data pfsd;

        bzero(&pfs, sizeof(pfs));
        bzero(&pfsd, sizeof(pfsd));
        pfs.pfs_id = pfs_id;
        pfs.ondisk = &pfsd;
        pfs.bytes = sizeof(pfsd);
        if (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) != 0) {
                perror("update_pfs_snapshot (read)");
                exit(1);
        }
        if (pfsd.sync_end_tid != snapshot_tid) {
                pfsd.sync_end_tid = snapshot_tid;
                if (ioctl(fd, HAMMERIOC_SET_PSEUDOFS, &pfs) != 0) {
                        perror("update_pfs_snapshot (rewrite)");
                        exit(1);
                }
                if (VerboseOpt >= 2) {
                        fprintf(stderr,
                                "Mirror-write: Completed, updated snapshot "
                                "to %016jx\n",
                                (uintmax_t)snapshot_tid);
                        fflush(stderr);
                }
        }
}

/*
 * Bandwidth-limited write in chunks
 */
static
ssize_t
writebw(int fd, const void *buf, size_t nbytes,
        u_int64_t *bwcount, struct timeval *tv1)
{
        struct timeval tv2;
        size_t n;
        ssize_t r;
        ssize_t a;
        int usec;

        a = 0;
        r = 0;
        while (nbytes) {
                if (*bwcount + nbytes > BandwidthOpt)
                        n = BandwidthOpt - *bwcount;
                else
                        n = nbytes;
                if (n)
                        r = write(fd, buf, n);
                if (r >= 0) {
                        a += r;
                        nbytes -= r;
                        buf = (const char *)buf + r;
                }
                if ((size_t)r != n)
                        break;
                *bwcount += n;
                if (*bwcount >= BandwidthOpt) {
                        gettimeofday(&tv2, NULL);
                        usec = (int)(tv2.tv_sec - tv1->tv_sec) * 1000000 +
                                (int)(tv2.tv_usec - tv1->tv_usec);
                        if (usec >= 0 && usec < 1000000)
                                usleep(1000000 - usec);
                        gettimeofday(tv1, NULL);
                        *bwcount -= BandwidthOpt;
                }
        }
        return(a ? a : r);
}

/*
 * Get a yes or no answer from the terminal.  The program may be run as
 * part of a two-way pipe so we cannot use stdin for this operation.
 */
static int
getyn(void)
{
        char buf[256];
        FILE *fp;
        int result;

        fp = fopen("/dev/tty", "r");
        if (fp == NULL) {
                fprintf(stderr, "No terminal for response\n");
                return(-1);
        }
        result = -1;
        while (fgets(buf, sizeof(buf), fp) != NULL) {
                if (buf[0] == 'y' || buf[0] == 'Y') {
                        result = 1;
                        break;
                }
                if (buf[0] == 'n' || buf[0] == 'N') {
                        result = 0;
                        break;
                }
                fprintf(stderr, "Response not understood\n");
                break;
        }
        fclose(fp);
        return(result);
}

static void
mirror_usage(int code)
{
        fprintf(stderr, 
                "hammer mirror-read <filesystem> [begin-tid]\n"
                "hammer mirror-read-stream <filesystem> [begin-tid]\n"
                "hammer mirror-write <filesystem>\n"
                "hammer mirror-dump\n"
                "hammer mirror-copy [[user@]host:]<filesystem>"
                                  " [[user@]host:]<filesystem>\n"
                "hammer mirror-stream [[user@]host:]<filesystem>"
                                    " [[user@]host:]<filesystem>\n"
        );
        exit(code);
}