/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2022 The FreeBSD Foundation
 *
 * This software was developed by Mark Johnston under sponsorship from
 * the FreeBSD Foundation.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include <util.h>

#include "zfs.h"

#define DNODES_PER_CHUNK        (MAXBLOCKSIZE / sizeof(dnode_phys_t))

struct objset_dnode_chunk {
        dnode_phys_t    buf[DNODES_PER_CHUNK];
        unsigned int    nextfree;
        STAILQ_ENTRY(objset_dnode_chunk) next;
};

typedef struct zfs_objset {
        /* Physical object set. */
        objset_phys_t   *phys;
        off_t           osloc;
        off_t           osblksz;
        blkptr_t        osbp;           /* set in objset_write() */

        /* Accounting. */
        off_t           space;          /* bytes allocated to this objset */

        /* dnode allocator. */
        uint64_t        dnodecount;
        STAILQ_HEAD(, objset_dnode_chunk) dnodechunks;
} zfs_objset_t;

static void
dnode_init(dnode_phys_t *dnode, uint8_t type, uint8_t bonustype,
    uint16_t bonuslen)
{
        dnode->dn_indblkshift = MAXBLOCKSHIFT;
        dnode->dn_type = type;
        dnode->dn_bonustype = bonustype;
        dnode->dn_bonuslen = bonuslen;
        dnode->dn_checksum = ZIO_CHECKSUM_FLETCHER_4;
        dnode->dn_nlevels = 1;
        dnode->dn_nblkptr = 1;
        dnode->dn_flags = DNODE_FLAG_USED_BYTES;
}

zfs_objset_t *
objset_alloc(zfs_opt_t *zfs, uint64_t type)
{
        struct objset_dnode_chunk *chunk;
        zfs_objset_t *os;

        os = ecalloc(1, sizeof(*os));
        os->osblksz = sizeof(objset_phys_t);
        os->osloc = objset_space_alloc(zfs, os, &os->osblksz);

        /*
         * Object ID zero is always reserved for the meta dnode, which is
         * embedded in the objset itself.
         */
        STAILQ_INIT(&os->dnodechunks);
        chunk = ecalloc(1, sizeof(*chunk));
        chunk->nextfree = 1;
        STAILQ_INSERT_HEAD(&os->dnodechunks, chunk, next);
        os->dnodecount = 1;

        os->phys = ecalloc(1, os->osblksz);
        os->phys->os_type = type;

        dnode_init(&os->phys->os_meta_dnode, DMU_OT_DNODE, DMU_OT_NONE, 0);
        os->phys->os_meta_dnode.dn_datablkszsec =
            DNODE_BLOCK_SIZE >> MINBLOCKSHIFT;

        return (os);
}

/*
 * Write the dnode array and physical object set to disk.
 */
static void
_objset_write(zfs_opt_t *zfs, zfs_objset_t *os, struct dnode_cursor *c,
    off_t loc)
{
        struct objset_dnode_chunk *chunk, *tmp;
        unsigned int total;

        /*
         * Write out the dnode array, i.e., the meta-dnode.  For some reason its
         * data blocks must be 16KB in size no matter how large the array is.
         */
        total = 0;
        STAILQ_FOREACH_SAFE(chunk, &os->dnodechunks, next, tmp) {
                unsigned int i;

                assert(chunk->nextfree > 0);
                assert(chunk->nextfree <= os->dnodecount);
                assert(chunk->nextfree <= DNODES_PER_CHUNK);

                for (i = 0; i < chunk->nextfree; i += DNODES_PER_BLOCK) {
                        blkptr_t *bp;
                        uint64_t fill;

                        if (chunk->nextfree - i < DNODES_PER_BLOCK)
                                fill = DNODES_PER_BLOCK - (chunk->nextfree - i);
                        else
                                fill = 0;
                        bp = dnode_cursor_next(zfs, c,
                            (total + i) * sizeof(dnode_phys_t));
                        vdev_pwrite_dnode_indir(zfs, &os->phys->os_meta_dnode,
                            0, fill, chunk->buf + i, DNODE_BLOCK_SIZE, loc, bp);
                        loc += DNODE_BLOCK_SIZE;
                }
                total += i;

                free(chunk);
        }
        dnode_cursor_finish(zfs, c);
        STAILQ_INIT(&os->dnodechunks);

        /*
         * Write the object set itself.  The saved block pointer will be copied
         * into the referencing DSL dataset or the uberblocks.
         */
        vdev_pwrite_data(zfs, DMU_OT_OBJSET, ZIO_CHECKSUM_FLETCHER_4, 0,
            os->dnodecount - 1, os->phys, os->osblksz, os->osloc, &os->osbp);
}

void
objset_write(zfs_opt_t *zfs, zfs_objset_t *os)
{
        struct dnode_cursor *c;
        off_t dnodeloc, dnodesz;
        uint64_t dnodecount;

        /*
         * There is a chicken-and-egg problem here when writing the MOS: we
         * cannot write space maps before we're finished allocating space from
         * the vdev, and we can't write the MOS without having allocated space
         * for indirect dnode blocks.  Thus, rather than lazily allocating
         * indirect blocks for the meta-dnode (which would be simpler), they are
         * allocated up-front and before writing space maps.
         */
        dnodecount = os->dnodecount;
        if (os == zfs->mos)
                dnodecount += zfs->mscount;
        dnodesz = dnodecount * sizeof(dnode_phys_t);
        c = dnode_cursor_init(zfs, os, &os->phys->os_meta_dnode, dnodesz,
            DNODE_BLOCK_SIZE);
        dnodesz = roundup2(dnodesz, DNODE_BLOCK_SIZE);
        dnodeloc = objset_space_alloc(zfs, os, &dnodesz);

        if (os == zfs->mos) {
                vdev_spacemap_write(zfs);

                /*
                 * We've finished allocating space, account for it in $MOS and
                 * in the parent directory.
                 */
                dsl_dir_root_finalize(zfs, os->space);
        }
        _objset_write(zfs, os, c, dnodeloc);
}

dnode_phys_t *
objset_dnode_bonus_alloc(zfs_objset_t *os, uint8_t type, uint8_t bonustype,
    uint16_t bonuslen, uint64_t *idp)
{
        struct objset_dnode_chunk *chunk;
        dnode_phys_t *dnode;

        assert(bonuslen <= DN_OLD_MAX_BONUSLEN);
        assert(!STAILQ_EMPTY(&os->dnodechunks));

        chunk = STAILQ_LAST(&os->dnodechunks, objset_dnode_chunk, next);
        if (chunk->nextfree == DNODES_PER_CHUNK) {
                chunk = ecalloc(1, sizeof(*chunk));
                STAILQ_INSERT_TAIL(&os->dnodechunks, chunk, next);
        }
        *idp = os->dnodecount++;
        dnode = &chunk->buf[chunk->nextfree++];
        dnode_init(dnode, type, bonustype, bonuslen);
        dnode->dn_datablkszsec = os->osblksz >> MINBLOCKSHIFT;
        return (dnode);
}

dnode_phys_t *
objset_dnode_alloc(zfs_objset_t *os, uint8_t type, uint64_t *idp)
{
        return (objset_dnode_bonus_alloc(os, type, DMU_OT_NONE, 0, idp));
}

/*
 * Look up a physical dnode by ID.  This is not used often so a linear search is
 * fine.
 */
dnode_phys_t *
objset_dnode_lookup(zfs_objset_t *os, uint64_t id)
{
        struct objset_dnode_chunk *chunk;

        assert(id > 0);
        assert(id < os->dnodecount);

        STAILQ_FOREACH(chunk, &os->dnodechunks, next) {
                if (id < DNODES_PER_CHUNK)
                        return (&chunk->buf[id]);
                id -= DNODES_PER_CHUNK;
        }
        assert(0);
        return (NULL);
}

off_t
objset_space_alloc(zfs_opt_t *zfs, zfs_objset_t *os, off_t *lenp)
{
        off_t loc;

        loc = vdev_space_alloc(zfs, lenp);
        os->space += *lenp;
        return (loc);
}

uint64_t
objset_space(const zfs_objset_t *os)
{
        return (os->space);
}

void
objset_root_blkptr_copy(const zfs_objset_t *os, blkptr_t *bp)
{
        memcpy(bp, &os->osbp, sizeof(blkptr_t));
}