HAMMER 33C/many: features and bug fixes.

[dfdiff.git] / sbin / hammer / ondisk.c

/*
 * Copyright (c) 2007 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/ondisk.c,v 1.14 2008/03/18 05:21:53 dillon Exp $
 */

#include <sys/types.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <err.h>
#include <fcntl.h>
#include "hammer_util.h"

static void *alloc_blockmap(int zone, int bytes, hammer_off_t *result_offp,
                        struct buffer_info **bufferp);
static hammer_off_t alloc_bigblock(struct volume_info *volume,
                        hammer_off_t owner);
#if 0
static void init_fifo_head(hammer_fifo_head_t head, u_int16_t hdr_type);
static hammer_off_t hammer_alloc_fifo(int32_t base_bytes, int32_t ext_bytes,
                        struct buffer_info **bufp, u_int16_t hdr_type);
static void readhammerbuf(struct volume_info *vol, void *data,
                        int64_t offset);
#endif
static void writehammerbuf(struct volume_info *vol, const void *data,
                        int64_t offset);


uuid_t Hammer_FSType;
uuid_t Hammer_FSId;
int64_t BootAreaSize;
int64_t MemAreaSize;
int     UsingSuperClusters;
int     NumVolumes;
int     RootVolNo = -1;
struct volume_list VolList = TAILQ_HEAD_INITIALIZER(VolList);

/*
 * Lookup the requested information structure and related on-disk buffer.
 * Missing structures are created.
 */
struct volume_info *
setup_volume(int32_t vol_no, const char *filename, int isnew, int oflags)
{
        struct volume_info *vol;
        struct volume_info *scan;
        struct hammer_volume_ondisk *ondisk;
        int n;

        /*
         * Allocate the volume structure
         */
        vol = malloc(sizeof(*vol));
        bzero(vol, sizeof(*vol));
        TAILQ_INIT(&vol->buffer_list);
        vol->name = strdup(filename);
        vol->fd = open(filename, oflags);
        if (vol->fd < 0) {
                free(vol->name);
                free(vol);
                err(1, "setup_volume: %s: Open failed", filename);
        }

        /*
         * Read or initialize the volume header
         */
        vol->ondisk = ondisk = malloc(HAMMER_BUFSIZE);
        if (isnew) {
                bzero(ondisk, HAMMER_BUFSIZE);
        } else {
                n = pread(vol->fd, ondisk, HAMMER_BUFSIZE, 0);
                if (n != HAMMER_BUFSIZE) {
                        err(1, "setup_volume: %s: Read failed at offset 0",
                            filename);
                }
                vol_no = ondisk->vol_no;
                if (RootVolNo < 0) {
                        RootVolNo = ondisk->vol_rootvol;
                } else if (RootVolNo != (int)ondisk->vol_rootvol) {
                        errx(1, "setup_volume: %s: root volume disagreement: "
                                "%d vs %d",
                                vol->name, RootVolNo, ondisk->vol_rootvol);
                }

                if (bcmp(&Hammer_FSType, &ondisk->vol_fstype, sizeof(Hammer_FSType)) != 0) {
                        errx(1, "setup_volume: %s: Header does not indicate "
                                "that this is a hammer volume", vol->name);
                }
                if (TAILQ_EMPTY(&VolList)) {
                        Hammer_FSId = vol->ondisk->vol_fsid;
                } else if (bcmp(&Hammer_FSId, &ondisk->vol_fsid, sizeof(Hammer_FSId)) != 0) {
                        errx(1, "setup_volume: %s: FSId does match other "
                                "volumes!", vol->name);
                }
        }
        vol->vol_no = vol_no;

        if (isnew) {
                /*init_fifo_head(&ondisk->head, HAMMER_HEAD_TYPE_VOL);*/
                vol->cache.modified = 1;
        }

        /*
         * Link the volume structure in
         */
        TAILQ_FOREACH(scan, &VolList, entry) {
                if (scan->vol_no == vol_no) {
                        errx(1, "setup_volume %s: Duplicate volume number %d "
                                "against %s", filename, vol_no, scan->name);
                }
        }
        TAILQ_INSERT_TAIL(&VolList, vol, entry);
        return(vol);
}

struct volume_info *
get_volume(int32_t vol_no)
{
        struct volume_info *vol;

        TAILQ_FOREACH(vol, &VolList, entry) {
                if (vol->vol_no == vol_no)
                        break;
        }
        if (vol == NULL)
                errx(1, "get_volume: Volume %d does not exist!", vol_no);
        ++vol->cache.refs;
        /* not added to or removed from hammer cache */
        return(vol);
}

void
rel_volume(struct volume_info *volume)
{
        /* not added to or removed from hammer cache */
        --volume->cache.refs;
}

/*
 * Acquire the specified buffer.
 */
struct buffer_info *
get_buffer(hammer_off_t buf_offset, int isnew)
{
        void *ondisk;
        struct buffer_info *buf;
        struct volume_info *volume;
        int vol_no;
        int zone;
        int n;

        zone = HAMMER_ZONE_DECODE(buf_offset);
        if (zone > HAMMER_ZONE_RAW_BUFFER_INDEX) {
                buf_offset = blockmap_lookup(buf_offset, NULL, NULL);
        }
        assert((buf_offset & HAMMER_OFF_ZONE_MASK) == HAMMER_ZONE_RAW_BUFFER);
        vol_no = HAMMER_VOL_DECODE(buf_offset);
        volume = get_volume(vol_no);
        buf_offset &= ~HAMMER_BUFMASK64;

        TAILQ_FOREACH(buf, &volume->buffer_list, entry) {
                if (buf->buf_offset == buf_offset)
                        break;
        }
        if (buf == NULL) {
                buf = malloc(sizeof(*buf));
                bzero(buf, sizeof(*buf));
                buf->buf_offset = buf_offset;
                buf->buf_disk_offset = volume->ondisk->vol_buf_beg +
                                        (buf_offset & HAMMER_OFF_SHORT_MASK);
                buf->volume = volume;
                TAILQ_INSERT_TAIL(&volume->buffer_list, buf, entry);
                ++volume->cache.refs;
                buf->cache.u.buffer = buf;
                hammer_cache_add(&buf->cache, ISBUFFER);
        }
        ++buf->cache.refs;
        hammer_cache_flush();
        if ((ondisk = buf->ondisk) == NULL) {
                buf->ondisk = ondisk = malloc(HAMMER_BUFSIZE);
                if (isnew == 0) {
                        n = pread(volume->fd, ondisk, HAMMER_BUFSIZE,
                                  buf->buf_disk_offset);
                        if (n != HAMMER_BUFSIZE) {
                                err(1, "get_buffer: %s:%016llx Read failed at "
                                       "offset %lld",
                                    volume->name, buf->buf_offset,
                                    buf->buf_disk_offset);
                        }
                }
        }
        if (isnew) {
                bzero(ondisk, HAMMER_BUFSIZE);
                buf->cache.modified = 1;
        }
        return(buf);
}

void
rel_buffer(struct buffer_info *buffer)
{
        struct volume_info *volume;

        assert(buffer->cache.refs > 0);
        if (--buffer->cache.refs == 0) {
                if (buffer->cache.delete) {
                        volume = buffer->volume;
                        if (buffer->cache.modified)
                                flush_buffer(buffer);
                        TAILQ_REMOVE(&volume->buffer_list, buffer, entry);
                        hammer_cache_del(&buffer->cache);
                        free(buffer->ondisk);
                        free(buffer);
                        rel_volume(volume);
                }
        }
}

void *
get_buffer_data(hammer_off_t buf_offset, struct buffer_info **bufferp,
                int isnew)
{
        struct buffer_info *buffer;

        if ((buffer = *bufferp) != NULL) {
                if (isnew || 
                    ((buffer->buf_offset ^ buf_offset) & ~HAMMER_BUFMASK64)) {
                        rel_buffer(buffer);
                        buffer = *bufferp = NULL;
                }
        }
        if (buffer == NULL)
                buffer = *bufferp = get_buffer(buf_offset, isnew);
        return((char *)buffer->ondisk + ((int32_t)buf_offset & HAMMER_BUFMASK));
}

/*
 * Retrieve a pointer to a B-Tree node given a cluster offset.  The underlying
 * bufp is freed if non-NULL and a referenced buffer is loaded into it.
 */
hammer_node_ondisk_t
get_node(hammer_off_t node_offset, struct buffer_info **bufp)
{
        struct buffer_info *buf;

        if (*bufp)
                rel_buffer(*bufp);
        *bufp = buf = get_buffer(node_offset, 0);
        return((void *)((char *)buf->ondisk +
                        (int32_t)(node_offset & HAMMER_BUFMASK)));
}

/*
 * Allocate HAMMER elements - btree nodes, data storage, and record elements
 *
 * NOTE: hammer_alloc_fifo() initializes the fifo header for the returned
 * item and zero's out the remainder, so don't bzero() it.
 */
void *
alloc_btree_element(hammer_off_t *offp)
{
        struct buffer_info *buffer = NULL;
        hammer_node_ondisk_t node;

        node = alloc_blockmap(HAMMER_ZONE_BTREE_INDEX, sizeof(*node),
                              offp, &buffer);
        bzero(node, sizeof(*node));
        /* XXX buffer not released, pointer remains valid */
        return(node);
}

hammer_record_ondisk_t
alloc_record_element(hammer_off_t *offp, int32_t data_len, void **datap)
{
        struct buffer_info *record_buffer = NULL;
        struct buffer_info *data_buffer = NULL;
        hammer_record_ondisk_t rec;

        rec = alloc_blockmap(HAMMER_ZONE_RECORD_INDEX, sizeof(*rec),
                             offp, &record_buffer);
        bzero(rec, sizeof(*rec));

        if (data_len >= HAMMER_BUFSIZE) {
                assert(data_len <= HAMMER_BUFSIZE); /* just one buffer */
                *datap = alloc_blockmap(HAMMER_ZONE_LARGE_DATA_INDEX, data_len,
                                        &rec->base.data_off, &data_buffer);
                rec->base.data_len = data_len;
                bzero(*datap, data_len);
        } else if (data_len) {
                *datap = alloc_blockmap(HAMMER_ZONE_SMALL_DATA_INDEX, data_len,
                                        &rec->base.data_off, &data_buffer);
                rec->base.data_len = data_len;
                bzero(*datap, data_len);
        } else {
                *datap = NULL;
        }
        /* XXX buf not released, ptr remains valid */
        return(rec);
}

/*
 * Format a new freemap.  Set all layer1 entries to UNAVAIL.  The initialize
 * code will load each volume's freemap.
 */
void
format_freemap(struct volume_info *root_vol, hammer_blockmap_t blockmap)
{
        struct buffer_info *buffer = NULL;
        hammer_off_t layer1_offset;
        struct hammer_blockmap_layer1 *layer1;
        int i, isnew;

        layer1_offset = alloc_bigblock(root_vol, 0);
        for (i = 0; i < (int)HAMMER_BLOCKMAP_RADIX1; ++i) {
                isnew = ((i % HAMMER_BLOCKMAP_RADIX1_PERBUFFER) == 0);
                layer1 = get_buffer_data(layer1_offset + i * sizeof(*layer1),
                                         &buffer, isnew);
                bzero(layer1, sizeof(*layer1));
                layer1->phys_offset = HAMMER_BLOCKMAP_UNAVAIL;
                layer1->layer1_crc = crc32(layer1, sizeof(*layer1));
        }
        rel_buffer(buffer);

        blockmap = &root_vol->ondisk->vol0_blockmap[HAMMER_ZONE_FREEMAP_INDEX];
        blockmap->phys_offset = layer1_offset;
        blockmap->alloc_offset = HAMMER_ENCODE_RAW_BUFFER(255, -1);
        blockmap->next_offset = HAMMER_ENCODE_RAW_BUFFER(0, 0);
        blockmap->reserved01 = 0;
        blockmap->entry_crc = crc32(blockmap, sizeof(*blockmap));
        root_vol->cache.modified = 1;
}

/*
 * Load the volume's remaining free space into the freemap.  If this is
 * the root volume, initialize the freemap owner for the layer1 bigblock.
 *
 * Returns the number of bigblocks available.
 */
int64_t
initialize_freemap(struct volume_info *vol)
{
        struct volume_info *root_vol;
        struct buffer_info *buffer1 = NULL;
        struct buffer_info *buffer2 = NULL;
        struct hammer_blockmap_layer1 *layer1;
        struct hammer_blockmap_layer2 *layer2;
        hammer_off_t layer1_base;
        hammer_off_t layer1_offset;
        hammer_off_t layer2_offset;
        hammer_off_t phys_offset;
        hammer_off_t aligned_vol_free_end;
        int64_t count = 0;

        root_vol = get_volume(RootVolNo);
        aligned_vol_free_end = (vol->vol_free_end + HAMMER_BLOCKMAP_LAYER2_MASK)
                                & ~HAMMER_BLOCKMAP_LAYER2_MASK;

        printf("initialize freemap volume %d\n", vol->vol_no);

        /*
         * Initialize the freemap.  First preallocate the bigblocks required
         * to implement layer2.   This preallocation is a bootstrap allocation
         * using blocks from the target volume.
         */
        layer1_base = root_vol->ondisk->vol0_blockmap[
                                        HAMMER_ZONE_FREEMAP_INDEX].phys_offset;
        for (phys_offset = HAMMER_ENCODE_RAW_BUFFER(vol->vol_no, 0);
             phys_offset < aligned_vol_free_end;
             phys_offset += HAMMER_BLOCKMAP_LAYER2) {
                layer1_offset = layer1_base +
                                HAMMER_BLOCKMAP_LAYER1_OFFSET(phys_offset);
                layer1 = get_buffer_data(layer1_offset, &buffer1, 0);
                if (layer1->phys_offset == HAMMER_BLOCKMAP_UNAVAIL) {
                        layer1->phys_offset = alloc_bigblock(vol, 0);
                        layer1->blocks_free = 0;
                        buffer1->cache.modified = 1;
                }
        }

        /*
         * Now fill everything in.
         */
        for (phys_offset = HAMMER_ENCODE_RAW_BUFFER(vol->vol_no, 0);
             phys_offset < aligned_vol_free_end;
             phys_offset += HAMMER_LARGEBLOCK_SIZE) {
                layer1_offset = layer1_base +
                                HAMMER_BLOCKMAP_LAYER1_OFFSET(phys_offset);
                layer1 = get_buffer_data(layer1_offset, &buffer1, 0);

                assert(layer1->phys_offset != HAMMER_BLOCKMAP_UNAVAIL);
                layer2_offset = layer1->phys_offset +
                                HAMMER_BLOCKMAP_LAYER2_OFFSET(phys_offset);

                layer2 = get_buffer_data(layer2_offset, &buffer2, 0);
                if (phys_offset < vol->vol_free_off) {
                        /*
                         * Fixups XXX - bigblocks already allocated as part
                         * of the freemap bootstrap.
                         */
                        layer2->u.owner = HAMMER_ENCODE_FREEMAP(0, 0); /* XXX */
                } else if (phys_offset < vol->vol_free_end) {
                        ++layer1->blocks_free;
                        buffer1->cache.modified = 1;
                        layer2->u.owner = HAMMER_BLOCKMAP_FREE;
                        ++count;
                } else {
                        layer2->u.owner = HAMMER_BLOCKMAP_UNAVAIL;
                }
                layer2->entry_crc = crc32(layer2, sizeof(*layer2));
                buffer2->cache.modified = 1;

                /*
                 * Finish-up layer 1
                 */
                if (((phys_offset + HAMMER_LARGEBLOCK_SIZE) & HAMMER_BLOCKMAP_LAYER2_MASK) == 0) {
                        layer1->layer1_crc = crc32(layer1, sizeof(*layer1));
                        buffer1->cache.modified = 1;
                }
        }
        rel_buffer(buffer1);
        rel_buffer(buffer2);
        rel_volume(root_vol);
        return(count);
}

/*
 * Allocate big-blocks using our poor-man's volume->vol_free_off and
 * update the freemap if owner != 0.
 */
hammer_off_t
alloc_bigblock(struct volume_info *volume, hammer_off_t owner)
{
        struct buffer_info *buffer = NULL;
        struct volume_info *root_vol;
        hammer_off_t result_offset;
        hammer_off_t layer_offset;
        struct hammer_blockmap_layer1 *layer1;
        struct hammer_blockmap_layer2 *layer2;
        int didget;

        if (volume == NULL) {
                volume = get_volume(RootVolNo);
                didget = 1;
        } else {
                didget = 0;
        }
        result_offset = volume->vol_free_off;
        if (result_offset >= volume->vol_free_end)
                panic("alloc_bigblock: Ran out of room, filesystem too small");
        volume->vol_free_off += HAMMER_LARGEBLOCK_SIZE;

        /*
         * Update the freemap
         */
        if (owner) {
                root_vol = get_volume(RootVolNo);
                layer_offset = root_vol->ondisk->vol0_blockmap[
                                        HAMMER_ZONE_FREEMAP_INDEX].phys_offset;
                layer_offset += HAMMER_BLOCKMAP_LAYER1_OFFSET(result_offset);
                layer1 = get_buffer_data(layer_offset, &buffer, 0);
                assert(layer1->phys_offset != HAMMER_BLOCKMAP_UNAVAIL);
                --layer1->blocks_free;
                layer1->layer1_crc = crc32(layer1, sizeof(*layer1));
                buffer->cache.modified = 1;
                layer_offset = layer1->phys_offset +
                               HAMMER_BLOCKMAP_LAYER2_OFFSET(result_offset);
                layer2 = get_buffer_data(layer_offset, &buffer, 0);
                assert(layer2->u.owner == HAMMER_BLOCKMAP_FREE);
                layer2->u.owner = owner;
                layer2->entry_crc = crc32(layer2, sizeof(*layer2));
                buffer->cache.modified = 1;

                rel_buffer(buffer);
                rel_volume(root_vol);
        }

        if (didget)
                rel_volume(volume);
        return(result_offset);
}

/*
 * Format the undo-map for the root volume.
 */
void
format_undomap(hammer_volume_ondisk_t ondisk)
{
        const int undo_zone = HAMMER_ZONE_UNDO_INDEX;
        const hammer_off_t undo_limit = HAMMER_LARGEBLOCK_SIZE; /* XXX */
        hammer_blockmap_t blockmap;
        hammer_off_t scan;
        struct hammer_blockmap_layer2 *layer2;
        int n;
        int limit_index;

        blockmap = &ondisk->vol0_blockmap[undo_zone];
        bzero(blockmap, sizeof(*blockmap));
        blockmap->phys_offset = HAMMER_BLOCKMAP_UNAVAIL;
        blockmap->first_offset = HAMMER_ZONE_ENCODE(undo_zone, 0);
        blockmap->next_offset = blockmap->first_offset;
        blockmap->alloc_offset = HAMMER_ZONE_ENCODE(undo_zone, undo_limit);
        
        blockmap->entry_crc = crc32(blockmap, sizeof(*blockmap));

        layer2 = &ondisk->vol0_undo_array[0];
        n = 0;
        scan = blockmap->next_offset;
        limit_index = undo_limit / HAMMER_LARGEBLOCK_SIZE;

        assert(limit_index < HAMMER_UNDO_LAYER2);

        for (n = 0; n < limit_index; ++n) {
                layer2->u.phys_offset = alloc_bigblock(NULL, scan);
                layer2->bytes_free = -1;        /* not used */
                layer2->entry_crc = crc32(layer2, sizeof(*layer2));

                scan += HAMMER_LARGEBLOCK_SIZE;
                ++layer2;
        }
        while (n < HAMMER_UNDO_LAYER2) {
                layer2->u.phys_offset = HAMMER_BLOCKMAP_UNAVAIL;
                layer2->bytes_free = -1;
                layer2->entry_crc = crc32(layer2, sizeof(*layer2));
                ++layer2;
                ++n;
        }
}

/*
 * Format a new blockmap.  Set the owner to the base of the blockmap
 * (meaning either the blockmap layer1 bigblock, layer2 bigblock, or
 * target bigblock).
 */
void
format_blockmap(hammer_blockmap_t blockmap, hammer_off_t zone_off)
{
        blockmap->phys_offset = alloc_bigblock(NULL, zone_off);
        blockmap->alloc_offset = zone_off;
        blockmap->first_offset = zone_off;
        blockmap->next_offset = zone_off;
        blockmap->entry_crc = crc32(blockmap, sizeof(*blockmap));
}

static
void *
alloc_blockmap(int zone, int bytes, hammer_off_t *result_offp,
               struct buffer_info **bufferp)
{
        struct buffer_info *buffer1 = NULL;
        struct buffer_info *buffer2 = NULL;
        struct volume_info *volume;
        hammer_blockmap_t rootmap;
        struct hammer_blockmap_layer1 *layer1;
        struct hammer_blockmap_layer2 *layer2;
        hammer_off_t layer1_offset;
        hammer_off_t layer2_offset;
        hammer_off_t bigblock_offset;
        void *ptr;

        volume = get_volume(RootVolNo);

        rootmap = &volume->ondisk->vol0_blockmap[zone];

        /*
         * Alignment and buffer-boundary issues
         */
        bytes = (bytes + 7) & ~7;
        if ((rootmap->phys_offset ^ (rootmap->phys_offset + bytes - 1)) &
            ~HAMMER_BUFMASK64) {
                volume->cache.modified = 1;
                rootmap->phys_offset = (rootmap->phys_offset + bytes) &
                                       ~HAMMER_BUFMASK64;
        }

        /*
         * Dive layer 1
         */
        layer1_offset = rootmap->phys_offset +
                        HAMMER_BLOCKMAP_LAYER1_OFFSET(rootmap->alloc_offset);

        layer1 = get_buffer_data(layer1_offset, &buffer1, 0);
        if ((rootmap->alloc_offset & HAMMER_BLOCKMAP_LAYER2_MASK) == 0) {
                buffer1->cache.modified = 1;
                bzero(layer1, sizeof(*layer1));
                layer1->blocks_free = HAMMER_BLOCKMAP_RADIX2;
                layer1->phys_offset = alloc_bigblock(NULL,
                                                     rootmap->alloc_offset);
        }

        /*
         * Dive layer 2
         */
        layer2_offset = layer1->phys_offset +
                        HAMMER_BLOCKMAP_LAYER2_OFFSET(rootmap->alloc_offset);

        layer2 = get_buffer_data(layer2_offset, &buffer2, 0);

        if ((rootmap->alloc_offset & HAMMER_LARGEBLOCK_MASK64) == 0) {
                buffer2->cache.modified = 1;
                bzero(layer2, sizeof(*layer2));
                layer2->u.phys_offset = alloc_bigblock(NULL,
                                                       rootmap->alloc_offset);
                layer2->bytes_free = HAMMER_LARGEBLOCK_SIZE;
                --layer1->blocks_free;
        }

        buffer1->cache.modified = 1;
        buffer2->cache.modified = 1;
        volume->cache.modified = 1;
        layer2->bytes_free -= bytes;
        *result_offp = rootmap->alloc_offset;
        rootmap->alloc_offset += bytes;
        rootmap->next_offset = rootmap->alloc_offset;

        bigblock_offset = layer2->u.phys_offset + 
                          (*result_offp & HAMMER_LARGEBLOCK_MASK);
        ptr = get_buffer_data(bigblock_offset, bufferp, 0);
        (*bufferp)->cache.modified = 1;

        if (buffer1)
                rel_buffer(buffer1);
        if (buffer2)
                rel_buffer(buffer2);

        rel_volume(volume);
        return(ptr);
}

#if 0
/*
 * Reserve space from the FIFO.  Make sure that bytes does not cross a 
 * record boundary.
 *
 * Zero out base_bytes and initialize the fifo head and tail.  The
 * data area is not zerod.
 */
static
hammer_off_t
hammer_alloc_fifo(int32_t base_bytes, int32_t ext_bytes,
                  struct buffer_info **bufp, u_int16_t hdr_type)
{
        struct buffer_info *buf;
        struct volume_info *volume;
        hammer_fifo_head_t head;
        hammer_fifo_tail_t tail;
        hammer_off_t off;
        int32_t aligned_bytes;

        aligned_bytes = (base_bytes + ext_bytes + HAMMER_TAIL_ONDISK_SIZE +
                         HAMMER_HEAD_ALIGN_MASK) & ~HAMMER_HEAD_ALIGN_MASK;

        volume = get_volume(RootVolNo);
        off = volume->ondisk->vol0_fifo_end;

        /*
         * For now don't deal with transitions across buffer boundaries,
         * only newfs_hammer uses this function.
         */
        assert((off & ~HAMMER_BUFMASK64) ==
                ((off + aligned_bytes) & ~HAMMER_BUFMASK));

        *bufp = buf = get_buffer(off, 0);

        buf->cache.modified = 1;
        volume->cache.modified = 1;

        head = (void *)((char *)buf->ondisk + ((int32_t)off & HAMMER_BUFMASK));
        bzero(head, base_bytes);

        head->hdr_signature = HAMMER_HEAD_SIGNATURE;
        head->hdr_type = hdr_type;
        head->hdr_size = aligned_bytes;
        head->hdr_seq = volume->ondisk->vol0_next_seq++;

        tail = (void*)((char *)head + aligned_bytes - HAMMER_TAIL_ONDISK_SIZE);
        tail->tail_signature = HAMMER_TAIL_SIGNATURE;
        tail->tail_type = hdr_type;
        tail->tail_size = aligned_bytes;

        volume->ondisk->vol0_fifo_end += aligned_bytes;
        volume->cache.modified = 1;

        rel_volume(volume);

        return(off);
}

#endif

/*
 * Flush various tracking structures to disk
 */

/*
 * Flush various tracking structures to disk
 */
void
flush_all_volumes(void)
{
        struct volume_info *vol;

        TAILQ_FOREACH(vol, &VolList, entry)
                flush_volume(vol);
}

void
flush_volume(struct volume_info *volume)
{
        struct buffer_info *buffer;

        TAILQ_FOREACH(buffer, &volume->buffer_list, entry)
                flush_buffer(buffer);
        writehammerbuf(volume, volume->ondisk, 0);
        volume->cache.modified = 0;
}

void
flush_buffer(struct buffer_info *buffer)
{
        writehammerbuf(buffer->volume, buffer->ondisk, buffer->buf_disk_offset);
        buffer->cache.modified = 0;
}

#if 0
/*
 * Generic buffer initialization
 */
static void
init_fifo_head(hammer_fifo_head_t head, u_int16_t hdr_type)
{
        head->hdr_signature = HAMMER_HEAD_SIGNATURE;
        head->hdr_type = hdr_type;
        head->hdr_size = 0;
        head->hdr_crc = 0;
        head->hdr_seq = 0;
}

#endif

#if 0
/*
 * Core I/O operations
 */
static void
readhammerbuf(struct volume_info *vol, void *data, int64_t offset)
{
        ssize_t n;

        n = pread(vol->fd, data, HAMMER_BUFSIZE, offset);
        if (n != HAMMER_BUFSIZE)
                err(1, "Read volume %d (%s)", vol->vol_no, vol->name);
}

#endif

static void
writehammerbuf(struct volume_info *vol, const void *data, int64_t offset)
{
        ssize_t n;

        n = pwrite(vol->fd, data, HAMMER_BUFSIZE, offset);
        if (n != HAMMER_BUFSIZE)
                err(1, "Write volume %d (%s)", vol->vol_no, vol->name);
}

void
panic(const char *ctl, ...)
{
        va_list va;

        va_start(va, ctl);
        vfprintf(stderr, ctl, va);
        va_end(va);
        fprintf(stderr, "\n");
        exit(1);
}