FreeBSD/Linux Kernel Cross Reference
sys/cddl/boot/zfs/zfsimpl.h

     /*-
      * Copyright (c) 2002 McAfee, Inc.
      * All rights reserved.
      *
      * This software was developed for the FreeBSD Project by Marshall
      * Kirk McKusick and McAfee Research,, the Security Research Division of
      * McAfee, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as
      * part of the DARPA CHATS research program
      *
     * 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.
     */
    /*
     * CDDL HEADER START
     *
     * The contents of this file are subject to the terms of the
     * Common Development and Distribution License (the "License").
     * You may not use this file except in compliance with the License.
     *
     * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
     * or http://www.opensolaris.org/os/licensing.
     * See the License for the specific language governing permissions
     * and limitations under the License.
     *
     * When distributing Covered Code, include this CDDL HEADER in each
     * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     * If applicable, add the following below this CDDL HEADER, with the
     * fields enclosed by brackets "[]" replaced with your own identifying
     * information: Portions Copyright [yyyy] [name of copyright owner]
     *
     * CDDL HEADER END
     */
    /*
     * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
     * Use is subject to license terms.
     */
    /*
     * Copyright 2013 by Saso Kiselkov. All rights reserved.
     */
    /*
     * Copyright (c) 2020 by Delphix. All rights reserved.
     */
    
    #include <sys/queue.h>
    
    #ifndef _ZFSIMPL_H_
    #define _ZFSIMPL_H_
    
    #define MAXNAMELEN      256
    
    #define _NOTE(s)
    
    /*
     * AVL comparator helpers
     */
    #define AVL_ISIGN(a)    (((a) > 0) - ((a) < 0))
    #define AVL_CMP(a, b)   (((a) > (b)) - ((a) < (b)))
    #define AVL_PCMP(a, b)  \
            (((uintptr_t)(a) > (uintptr_t)(b)) - ((uintptr_t)(a) < (uintptr_t)(b)))
    
    #if !defined(NEED_SOLARIS_BOOLEAN)      /* Only defined when we'll define this elsewhere */
    typedef enum { B_FALSE, B_TRUE } boolean_t;
    #endif
    
    /* CRC64 table */
    #define ZFS_CRC64_POLY  0xC96C5795D7870F42ULL   /* ECMA-182, reflected form */
    
    /*
     * Macros for various sorts of alignment and rounding when the alignment
     * is known to be a power of 2.
     */
    #define P2ALIGN(x, align)               ((x) & -(align))
    #define P2PHASE(x, align)               ((x) & ((align) - 1))
    #define P2NPHASE(x, align)              (-(x) & ((align) - 1))
    #define P2ROUNDUP(x, align)             (-(-(x) & -(align)))
    #define P2END(x, align)                 (-(~(x) & -(align)))
    #define P2PHASEUP(x, align, phase)      ((phase) - (((phase) - (x)) & -(align)))
    #define P2BOUNDARY(off, len, align)     (((off) ^ ((off) + (len) - 1)) > (align) - 1)
    
    /*
     * General-purpose 32-bit and 64-bit bitfield encodings.
    */
   #define BF32_DECODE(x, low, len)        P2PHASE((x) >> (low), 1U << (len))
   #define BF64_DECODE(x, low, len)        P2PHASE((x) >> (low), 1ULL << (len))
   #define BF32_ENCODE(x, low, len)        (P2PHASE((x), 1U << (len)) << (low))
   #define BF64_ENCODE(x, low, len)        (P2PHASE((x), 1ULL << (len)) << (low))
   
   #define BF32_GET(x, low, len)           BF32_DECODE(x, low, len)
   #define BF64_GET(x, low, len)           BF64_DECODE(x, low, len)
   
   #define BF32_SET(x, low, len, val)      \
           ((x) ^= BF32_ENCODE((x >> low) ^ (val), low, len))
   #define BF64_SET(x, low, len, val)      \
           ((x) ^= BF64_ENCODE((x >> low) ^ (val), low, len))
   
   #define BF32_GET_SB(x, low, len, shift, bias)   \
           ((BF32_GET(x, low, len) + (bias)) << (shift))
   #define BF64_GET_SB(x, low, len, shift, bias)   \
           ((BF64_GET(x, low, len) + (bias)) << (shift))
   
   #define BF32_SET_SB(x, low, len, shift, bias, val)      \
           BF32_SET(x, low, len, ((val) >> (shift)) - (bias))
   #define BF64_SET_SB(x, low, len, shift, bias, val)      \
           BF64_SET(x, low, len, ((val) >> (shift)) - (bias))
   
   /*
    * Macros to reverse byte order
    */
   #define BSWAP_8(x)      ((x) & 0xff)
   #define BSWAP_16(x)     ((BSWAP_8(x) << 8) | BSWAP_8((x) >> 8))
   #define BSWAP_32(x)     ((BSWAP_16(x) << 16) | BSWAP_16((x) >> 16))
   #define BSWAP_64(x)     ((BSWAP_32(x) << 32) | BSWAP_32((x) >> 32))
   
   #define SPA_MINBLOCKSHIFT       9
   #define SPA_OLDMAXBLOCKSHIFT    17
   #define SPA_MAXBLOCKSHIFT       24
   #define SPA_MINBLOCKSIZE        (1ULL << SPA_MINBLOCKSHIFT)
   #define SPA_OLDMAXBLOCKSIZE     (1ULL << SPA_OLDMAXBLOCKSHIFT)
   #define SPA_MAXBLOCKSIZE        (1ULL << SPA_MAXBLOCKSHIFT)
   
   /*
    * The DVA size encodings for LSIZE and PSIZE support blocks up to 32MB.
    * The ASIZE encoding should be at least 64 times larger (6 more bits)
    * to support up to 4-way RAID-Z mirror mode with worst-case gang block
    * overhead, three DVAs per bp, plus one more bit in case we do anything
    * else that expands the ASIZE.
    */
   #define SPA_LSIZEBITS           16      /* LSIZE up to 32M (2^16 * 512) */
   #define SPA_PSIZEBITS           16      /* PSIZE up to 32M (2^16 * 512) */
   #define SPA_ASIZEBITS           24      /* ASIZE up to 64 times larger  */
   
   /*
    * All SPA data is represented by 128-bit data virtual addresses (DVAs).
    * The members of the dva_t should be considered opaque outside the SPA.
    */
   typedef struct dva {
           uint64_t        dva_word[2];
   } dva_t;
   
   /*
    * Each block has a 256-bit checksum -- strong enough for cryptographic hashes.
    */
   typedef struct zio_cksum {
           uint64_t        zc_word[4];
   } zio_cksum_t;
   
   /*
    * Some checksums/hashes need a 256-bit initialization salt. This salt is kept
    * secret and is suitable for use in MAC algorithms as the key.
    */
   typedef struct zio_cksum_salt {
           uint8_t         zcs_bytes[32];
   } zio_cksum_salt_t;
   
   /*
    * Each block is described by its DVAs, time of birth, checksum, etc.
    * The word-by-word, bit-by-bit layout of the blkptr is as follows:
    *
    *      64      56      48      40      32      24      16      8       0
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 0    |               vdev1           | GRID  |         ASIZE         |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 1    |G|                      offset1                                |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 2    |               vdev2           | GRID  |         ASIZE         |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 3    |G|                      offset2                                |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 4    |               vdev3           | GRID  |         ASIZE         |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 5    |G|                      offset3                                |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 6    |BDX|lvl| type  | cksum |E| comp|    PSIZE      |     LSIZE     |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 7    |                       padding                                 |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 8    |                       padding                                 |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 9    |                       physical birth txg                      |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * a    |                       logical birth txg                       |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * b    |                       fill count                              |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * c    |                       checksum[0]                             |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * d    |                       checksum[1]                             |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * e    |                       checksum[2]                             |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * f    |                       checksum[3]                             |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    *
    * Legend:
    *
    * vdev         virtual device ID
    * offset       offset into virtual device
    * LSIZE        logical size
    * PSIZE        physical size (after compression)
    * ASIZE        allocated size (including RAID-Z parity and gang block headers)
    * GRID         RAID-Z layout information (reserved for future use)
    * cksum        checksum function
    * comp         compression function
    * G            gang block indicator
    * B            byteorder (endianness)
    * D            dedup
    * X            encryption (on version 30, which is not supported)
    * E            blkptr_t contains embedded data (see below)
    * lvl          level of indirection
    * type         DMU object type
    * phys birth   txg of block allocation; zero if same as logical birth txg
    * log. birth   transaction group in which the block was logically born
    * fill count   number of non-zero blocks under this bp
    * checksum[4]  256-bit checksum of the data this bp describes
    */
   
   /*
    * "Embedded" blkptr_t's don't actually point to a block, instead they
    * have a data payload embedded in the blkptr_t itself.  See the comment
    * in blkptr.c for more details.
    *
    * The blkptr_t is laid out as follows:
    *
    *      64      56      48      40      32      24      16      8       0
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 0    |      payload                                                  |
    * 1    |      payload                                                  |
    * 2    |      payload                                                  |
    * 3    |      payload                                                  |
    * 4    |      payload                                                  |
    * 5    |      payload                                                  |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 6    |BDX|lvl| type  | etype |E| comp| PSIZE|              LSIZE     |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * 7    |      payload                                                  |
    * 8    |      payload                                                  |
    * 9    |      payload                                                  |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * a    |                       logical birth txg                       |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    * b    |      payload                                                  |
    * c    |      payload                                                  |
    * d    |      payload                                                  |
    * e    |      payload                                                  |
    * f    |      payload                                                  |
    *      +-------+-------+-------+-------+-------+-------+-------+-------+
    *
    * Legend:
    *
    * payload              contains the embedded data
    * B (byteorder)        byteorder (endianness)
    * D (dedup)            padding (set to zero)
    * X                    encryption (set to zero; see above)
    * E (embedded)         set to one
    * lvl                  indirection level
    * type                 DMU object type
    * etype                how to interpret embedded data (BP_EMBEDDED_TYPE_*)
    * comp                 compression function of payload
    * PSIZE                size of payload after compression, in bytes
    * LSIZE                logical size of payload, in bytes
    *                      note that 25 bits is enough to store the largest
    *                      "normal" BP's LSIZE (2^16 * 2^9) in bytes
    * log. birth           transaction group in which the block was logically born
    *
    * Note that LSIZE and PSIZE are stored in bytes, whereas for non-embedded
    * bp's they are stored in units of SPA_MINBLOCKSHIFT.
    * Generally, the generic BP_GET_*() macros can be used on embedded BP's.
    * The B, D, X, lvl, type, and comp fields are stored the same as with normal
    * BP's so the BP_SET_* macros can be used with them.  etype, PSIZE, LSIZE must
    * be set with the BPE_SET_* macros.  BP_SET_EMBEDDED() should be called before
    * other macros, as they assert that they are only used on BP's of the correct
    * "embedded-ness".
    */
   
   #define BPE_GET_ETYPE(bp)       \
           (ASSERT(BP_IS_EMBEDDED(bp)), \
           BF64_GET((bp)->blk_prop, 40, 8))
   #define BPE_SET_ETYPE(bp, t)    do { \
           ASSERT(BP_IS_EMBEDDED(bp)); \
           BF64_SET((bp)->blk_prop, 40, 8, t); \
   _NOTE(CONSTCOND) } while (0)
   
   #define BPE_GET_LSIZE(bp)       \
           (ASSERT(BP_IS_EMBEDDED(bp)), \
           BF64_GET_SB((bp)->blk_prop, 0, 25, 0, 1))
   #define BPE_SET_LSIZE(bp, x)    do { \
           ASSERT(BP_IS_EMBEDDED(bp)); \
           BF64_SET_SB((bp)->blk_prop, 0, 25, 0, 1, x); \
   _NOTE(CONSTCOND) } while (0)
   
   #define BPE_GET_PSIZE(bp)       \
           (ASSERT(BP_IS_EMBEDDED(bp)), \
           BF64_GET_SB((bp)->blk_prop, 25, 7, 0, 1))
   #define BPE_SET_PSIZE(bp, x)    do { \
           ASSERT(BP_IS_EMBEDDED(bp)); \
           BF64_SET_SB((bp)->blk_prop, 25, 7, 0, 1, x); \
   _NOTE(CONSTCOND) } while (0)
   
   typedef enum bp_embedded_type {
           BP_EMBEDDED_TYPE_DATA,
           BP_EMBEDDED_TYPE_RESERVED, /* Reserved for an unintegrated feature. */
           NUM_BP_EMBEDDED_TYPES = BP_EMBEDDED_TYPE_RESERVED
   } bp_embedded_type_t;
   
   #define BPE_NUM_WORDS 14
   #define BPE_PAYLOAD_SIZE (BPE_NUM_WORDS * sizeof (uint64_t))
   #define BPE_IS_PAYLOADWORD(bp, wp) \
           ((wp) != &(bp)->blk_prop && (wp) != &(bp)->blk_birth)
   
   #define SPA_BLKPTRSHIFT 7               /* blkptr_t is 128 bytes        */
   #define SPA_DVAS_PER_BP 3               /* Number of DVAs in a bp       */
   
   typedef struct blkptr {
           dva_t           blk_dva[SPA_DVAS_PER_BP]; /* Data Virtual Addresses */
           uint64_t        blk_prop;       /* size, compression, type, etc     */
           uint64_t        blk_pad[2];     /* Extra space for the future       */
           uint64_t        blk_phys_birth; /* txg when block was allocated     */
           uint64_t        blk_birth;      /* transaction group at birth       */
           uint64_t        blk_fill;       /* fill count                       */
           zio_cksum_t     blk_cksum;      /* 256-bit checksum                 */
   } blkptr_t;
   
   /*
    * Macros to get and set fields in a bp or DVA.
    */
   #define DVA_GET_ASIZE(dva)      \
           BF64_GET_SB((dva)->dva_word[0], 0, SPA_ASIZEBITS, SPA_MINBLOCKSHIFT, 0)
   #define DVA_SET_ASIZE(dva, x)   \
           BF64_SET_SB((dva)->dva_word[0], 0, SPA_ASIZEBITS, \
           SPA_MINBLOCKSHIFT, 0, x)
   
   #define DVA_GET_GRID(dva)       BF64_GET((dva)->dva_word[0], 24, 8)
   #define DVA_SET_GRID(dva, x)    BF64_SET((dva)->dva_word[0], 24, 8, x)
   
   #define DVA_GET_VDEV(dva)       BF64_GET((dva)->dva_word[0], 32, 32)
   #define DVA_SET_VDEV(dva, x)    BF64_SET((dva)->dva_word[0], 32, 32, x)
   
   #define DVA_GET_OFFSET(dva)     \
           BF64_GET_SB((dva)->dva_word[1], 0, 63, SPA_MINBLOCKSHIFT, 0)
   #define DVA_SET_OFFSET(dva, x)  \
           BF64_SET_SB((dva)->dva_word[1], 0, 63, SPA_MINBLOCKSHIFT, 0, x)
   
   #define DVA_GET_GANG(dva)       BF64_GET((dva)->dva_word[1], 63, 1)
   #define DVA_SET_GANG(dva, x)    BF64_SET((dva)->dva_word[1], 63, 1, x)
   
   #define BP_GET_LSIZE(bp)        \
           (BP_IS_EMBEDDED(bp) ?   \
           (BPE_GET_ETYPE(bp) == BP_EMBEDDED_TYPE_DATA ? BPE_GET_LSIZE(bp) : 0): \
           BF64_GET_SB((bp)->blk_prop, 0, SPA_LSIZEBITS, SPA_MINBLOCKSHIFT, 1))
   #define BP_SET_LSIZE(bp, x)     do { \
           ASSERT(!BP_IS_EMBEDDED(bp)); \
           BF64_SET_SB((bp)->blk_prop, \
               0, SPA_LSIZEBITS, SPA_MINBLOCKSHIFT, 1, x); \
   _NOTE(CONSTCOND) } while (0)
   
   #define BP_GET_PSIZE(bp)        \
           BF64_GET_SB((bp)->blk_prop, 16, SPA_LSIZEBITS, SPA_MINBLOCKSHIFT, 1)
   #define BP_SET_PSIZE(bp, x)     \
           BF64_SET_SB((bp)->blk_prop, 16, SPA_LSIZEBITS, SPA_MINBLOCKSHIFT, 1, x)
   
   #define BP_GET_COMPRESS(bp)     BF64_GET((bp)->blk_prop, 32, 7)
   #define BP_SET_COMPRESS(bp, x)  BF64_SET((bp)->blk_prop, 32, 7, x)
   
   #define BP_GET_CHECKSUM(bp)     BF64_GET((bp)->blk_prop, 40, 8)
   #define BP_SET_CHECKSUM(bp, x)  BF64_SET((bp)->blk_prop, 40, 8, x)
   
   #define BP_GET_TYPE(bp)         BF64_GET((bp)->blk_prop, 48, 8)
   #define BP_SET_TYPE(bp, x)      BF64_SET((bp)->blk_prop, 48, 8, x)
   
   #define BP_GET_LEVEL(bp)        BF64_GET((bp)->blk_prop, 56, 5)
   #define BP_SET_LEVEL(bp, x)     BF64_SET((bp)->blk_prop, 56, 5, x)
   
   #define BP_IS_EMBEDDED(bp)      BF64_GET((bp)->blk_prop, 39, 1)
   
   #define BP_GET_DEDUP(bp)        BF64_GET((bp)->blk_prop, 62, 1)
   #define BP_SET_DEDUP(bp, x)     BF64_SET((bp)->blk_prop, 62, 1, x)
   
   #define BP_GET_BYTEORDER(bp)    BF64_GET((bp)->blk_prop, 63, 1)
   #define BP_SET_BYTEORDER(bp, x) BF64_SET((bp)->blk_prop, 63, 1, x)
   
   #define BP_PHYSICAL_BIRTH(bp)           \
           ((bp)->blk_phys_birth ? (bp)->blk_phys_birth : (bp)->blk_birth)
   
   #define BP_SET_BIRTH(bp, logical, physical)     \
   {                                               \
           ASSERT(!BP_IS_EMBEDDED(bp));            \
           (bp)->blk_birth = (logical);            \
           (bp)->blk_phys_birth = ((logical) == (physical) ? 0 : (physical)); \
   }
   
   #define BP_GET_FILL(bp)                         \
           ((BP_IS_EMBEDDED(bp)) ? 1 : (bp)->blk_fill)
   
   #define BP_SET_FILL(bp, fill)                   \
   {                                               \
           (bp)->blk_fill = fill;                  \
   }
   
   #define BP_GET_ASIZE(bp)        \
           (DVA_GET_ASIZE(&(bp)->blk_dva[0]) + DVA_GET_ASIZE(&(bp)->blk_dva[1]) + \
                   DVA_GET_ASIZE(&(bp)->blk_dva[2]))
   
   #define BP_GET_UCSIZE(bp) \
           ((BP_GET_LEVEL(bp) > 0 || dmu_ot[BP_GET_TYPE(bp)].ot_metadata) ? \
           BP_GET_PSIZE(bp) : BP_GET_LSIZE(bp));
   
   #define BP_GET_NDVAS(bp)        \
           (!!DVA_GET_ASIZE(&(bp)->blk_dva[0]) + \
           !!DVA_GET_ASIZE(&(bp)->blk_dva[1]) + \
           !!DVA_GET_ASIZE(&(bp)->blk_dva[2]))
   
   #define DVA_EQUAL(dva1, dva2)   \
           ((dva1)->dva_word[1] == (dva2)->dva_word[1] && \
           (dva1)->dva_word[0] == (dva2)->dva_word[0])
   
   #define ZIO_CHECKSUM_EQUAL(zc1, zc2) \
           (0 == (((zc1).zc_word[0] - (zc2).zc_word[0]) | \
           ((zc1).zc_word[1] - (zc2).zc_word[1]) | \
           ((zc1).zc_word[2] - (zc2).zc_word[2]) | \
           ((zc1).zc_word[3] - (zc2).zc_word[3])))
   
   
   #define DVA_IS_VALID(dva)       (DVA_GET_ASIZE(dva) != 0)
   
   #define ZIO_SET_CHECKSUM(zcp, w0, w1, w2, w3)   \
   {                                               \
           (zcp)->zc_word[0] = w0;                 \
           (zcp)->zc_word[1] = w1;                 \
           (zcp)->zc_word[2] = w2;                 \
           (zcp)->zc_word[3] = w3;                 \
   }
   
   #define BP_IDENTITY(bp)         (&(bp)->blk_dva[0])
   #define BP_IS_GANG(bp)          DVA_GET_GANG(BP_IDENTITY(bp))
   #define DVA_IS_EMPTY(dva)       ((dva)->dva_word[0] == 0ULL &&  \
           (dva)->dva_word[1] == 0ULL)
   #define BP_IS_HOLE(bp)          DVA_IS_EMPTY(BP_IDENTITY(bp))
   #define BP_IS_OLDER(bp, txg)    (!BP_IS_HOLE(bp) && (bp)->blk_birth < (txg))
   
   #define BP_ZERO(bp)                             \
   {                                               \
           (bp)->blk_dva[0].dva_word[0] = 0;       \
           (bp)->blk_dva[0].dva_word[1] = 0;       \
           (bp)->blk_dva[1].dva_word[0] = 0;       \
           (bp)->blk_dva[1].dva_word[1] = 0;       \
           (bp)->blk_dva[2].dva_word[0] = 0;       \
           (bp)->blk_dva[2].dva_word[1] = 0;       \
           (bp)->blk_prop = 0;                     \
           (bp)->blk_pad[0] = 0;                   \
           (bp)->blk_pad[1] = 0;                   \
           (bp)->blk_phys_birth = 0;               \
           (bp)->blk_birth = 0;                    \
           (bp)->blk_fill = 0;                     \
           ZIO_SET_CHECKSUM(&(bp)->blk_cksum, 0, 0, 0, 0); \
   }
   
   #if BYTE_ORDER == _BIG_ENDIAN
   #define ZFS_HOST_BYTEORDER      (0ULL)
   #else
   #define ZFS_HOST_BYTEORDER      (1ULL)
   #endif
   
   #define BP_SHOULD_BYTESWAP(bp)  (BP_GET_BYTEORDER(bp) != ZFS_HOST_BYTEORDER)
   #define BPE_NUM_WORDS 14
   #define BPE_PAYLOAD_SIZE (BPE_NUM_WORDS * sizeof (uint64_t))
   #define BPE_IS_PAYLOADWORD(bp, wp) \
           ((wp) != &(bp)->blk_prop && (wp) != &(bp)->blk_birth)
   
   /*
    * Embedded checksum
    */
   #define ZEC_MAGIC       0x210da7ab10c7a11ULL
   
   typedef struct zio_eck {
           uint64_t        zec_magic;      /* for validation, endianness   */
           zio_cksum_t     zec_cksum;      /* 256-bit checksum             */
   } zio_eck_t;
   
   /*
    * Gang block headers are self-checksumming and contain an array
    * of block pointers.
    */
   #define SPA_GANGBLOCKSIZE       SPA_MINBLOCKSIZE
   #define SPA_GBH_NBLKPTRS        ((SPA_GANGBLOCKSIZE - \
           sizeof (zio_eck_t)) / sizeof (blkptr_t))
   #define SPA_GBH_FILLER          ((SPA_GANGBLOCKSIZE - \
           sizeof (zio_eck_t) - \
           (SPA_GBH_NBLKPTRS * sizeof (blkptr_t))) /\
           sizeof (uint64_t))
   
   typedef struct zio_gbh {
           blkptr_t                zg_blkptr[SPA_GBH_NBLKPTRS];
           uint64_t                zg_filler[SPA_GBH_FILLER];
           zio_eck_t               zg_tail;
   } zio_gbh_phys_t;
   
   #define VDEV_RAIDZ_MAXPARITY    3
   
   #define VDEV_PAD_SIZE           (8 << 10)
   /* 2 padding areas (vl_pad1 and vl_be) to skip */
   #define VDEV_SKIP_SIZE          VDEV_PAD_SIZE * 2
   #define VDEV_PHYS_SIZE          (112 << 10)
   #define VDEV_UBERBLOCK_RING     (128 << 10)
   
   /*
    * MMP blocks occupy the last MMP_BLOCKS_PER_LABEL slots in the uberblock
    * ring when MMP is enabled.
    */
   #define MMP_BLOCKS_PER_LABEL    1
   
   /* The largest uberblock we support is 8k. */
   #define MAX_UBERBLOCK_SHIFT     (13)
   #define VDEV_UBERBLOCK_SHIFT(vd)        \
           MIN(MAX((vd)->v_top->v_ashift, UBERBLOCK_SHIFT), MAX_UBERBLOCK_SHIFT)
   #define VDEV_UBERBLOCK_COUNT(vd)        \
           (VDEV_UBERBLOCK_RING >> VDEV_UBERBLOCK_SHIFT(vd))
   #define VDEV_UBERBLOCK_OFFSET(vd, n)    \
           offsetof(vdev_label_t, vl_uberblock[(n) << VDEV_UBERBLOCK_SHIFT(vd)])
   #define VDEV_UBERBLOCK_SIZE(vd)         (1ULL << VDEV_UBERBLOCK_SHIFT(vd))
   
   typedef struct vdev_phys {
           char            vp_nvlist[VDEV_PHYS_SIZE - sizeof (zio_eck_t)];
           zio_eck_t       vp_zbt;
   } vdev_phys_t;
   
   typedef enum vbe_vers {
           /* The bootenv file is stored as ascii text in the envblock */
           VB_RAW = 0,
   
           /*
            * The bootenv file is converted to an nvlist and then packed into the
            * envblock.
            */
           VB_NVLIST = 1
   } vbe_vers_t;
   
   typedef struct vdev_boot_envblock {
           uint64_t        vbe_version;
           char            vbe_bootenv[VDEV_PAD_SIZE - sizeof (uint64_t) -
                           sizeof (zio_eck_t)];
           zio_eck_t       vbe_zbt;
   } vdev_boot_envblock_t;
   
   _Static_assert(sizeof (vdev_boot_envblock_t) == VDEV_PAD_SIZE,
       "bad size for vdev_boot_envblock_t");
   
   typedef struct vdev_label {
           char            vl_pad1[VDEV_PAD_SIZE];                 /*  8K  */
           vdev_boot_envblock_t    vl_be;                          /*  8K  */
           vdev_phys_t     vl_vdev_phys;                           /* 112K */
           char            vl_uberblock[VDEV_UBERBLOCK_RING];      /* 128K */
   } vdev_label_t;                                                 /* 256K total */
   
   /*
    * vdev_dirty() flags
    */
   #define VDD_METASLAB    0x01
   #define VDD_DTL         0x02
   
   /*
    * Size and offset of embedded boot loader region on each label.
    * The total size of the first two labels plus the boot area is 4MB.
    */
   #define VDEV_BOOT_OFFSET        (2 * sizeof (vdev_label_t))
   #define VDEV_BOOT_SIZE          (7ULL << 19)                    /* 3.5M */
   
   /*
    * Size of label regions at the start and end of each leaf device.
    */
   #define VDEV_LABEL_START_SIZE   (2 * sizeof (vdev_label_t) + VDEV_BOOT_SIZE)
   #define VDEV_LABEL_END_SIZE     (2 * sizeof (vdev_label_t))
   #define VDEV_LABELS             4
   
   enum zio_checksum {
           ZIO_CHECKSUM_INHERIT = 0,
           ZIO_CHECKSUM_ON,
           ZIO_CHECKSUM_OFF,
           ZIO_CHECKSUM_LABEL,
           ZIO_CHECKSUM_GANG_HEADER,
           ZIO_CHECKSUM_ZILOG,
           ZIO_CHECKSUM_FLETCHER_2,
           ZIO_CHECKSUM_FLETCHER_4,
           ZIO_CHECKSUM_SHA256,
           ZIO_CHECKSUM_ZILOG2,
           ZIO_CHECKSUM_NOPARITY,
           ZIO_CHECKSUM_SHA512,
           ZIO_CHECKSUM_SKEIN,
           ZIO_CHECKSUM_EDONR,
           ZIO_CHECKSUM_BLAKE3,
           ZIO_CHECKSUM_FUNCTIONS
   };
   
   #define ZIO_CHECKSUM_ON_VALUE   ZIO_CHECKSUM_FLETCHER_4
   #define ZIO_CHECKSUM_DEFAULT    ZIO_CHECKSUM_ON
   
   enum zio_compress {
           ZIO_COMPRESS_INHERIT = 0,
           ZIO_COMPRESS_ON,
           ZIO_COMPRESS_OFF,
           ZIO_COMPRESS_LZJB,
           ZIO_COMPRESS_EMPTY,
           ZIO_COMPRESS_GZIP_1,
           ZIO_COMPRESS_GZIP_2,
           ZIO_COMPRESS_GZIP_3,
           ZIO_COMPRESS_GZIP_4,
           ZIO_COMPRESS_GZIP_5,
           ZIO_COMPRESS_GZIP_6,
           ZIO_COMPRESS_GZIP_7,
           ZIO_COMPRESS_GZIP_8,
           ZIO_COMPRESS_GZIP_9,
           ZIO_COMPRESS_ZLE,
           ZIO_COMPRESS_LZ4,
           ZIO_COMPRESS_ZSTD,
           ZIO_COMPRESS_FUNCTIONS
   };
   
   enum zio_zstd_levels {
           ZIO_ZSTD_LEVEL_INHERIT = 0,
           ZIO_ZSTD_LEVEL_1,
   #define ZIO_ZSTD_LEVEL_MIN      ZIO_ZSTD_LEVEL_1
           ZIO_ZSTD_LEVEL_2,
           ZIO_ZSTD_LEVEL_3,
   #define ZIO_ZSTD_LEVEL_DEFAULT  ZIO_ZSTD_LEVEL_3
           ZIO_ZSTD_LEVEL_4,
           ZIO_ZSTD_LEVEL_5,
           ZIO_ZSTD_LEVEL_6,
           ZIO_ZSTD_LEVEL_7,
           ZIO_ZSTD_LEVEL_8,
           ZIO_ZSTD_LEVEL_9,
           ZIO_ZSTD_LEVEL_10,
           ZIO_ZSTD_LEVEL_11,
           ZIO_ZSTD_LEVEL_12,
           ZIO_ZSTD_LEVEL_13,
           ZIO_ZSTD_LEVEL_14,
           ZIO_ZSTD_LEVEL_15,
           ZIO_ZSTD_LEVEL_16,
           ZIO_ZSTD_LEVEL_17,
           ZIO_ZSTD_LEVEL_18,
           ZIO_ZSTD_LEVEL_19,
   #define ZIO_ZSTD_LEVEL_MAX      ZIO_ZSTD_LEVEL_19
           ZIO_ZSTD_LEVEL_RESERVE = 101, /* Leave room for new positive levels */
           ZIO_ZSTD_LEVEL_FAST, /* Fast levels are negative */
           ZIO_ZSTD_LEVEL_FAST_1,
   #define ZIO_ZSTD_LEVEL_FAST_DEFAULT     ZIO_ZSTD_LEVEL_FAST_1
           ZIO_ZSTD_LEVEL_FAST_2,
           ZIO_ZSTD_LEVEL_FAST_3,
           ZIO_ZSTD_LEVEL_FAST_4,
           ZIO_ZSTD_LEVEL_FAST_5,
           ZIO_ZSTD_LEVEL_FAST_6,
           ZIO_ZSTD_LEVEL_FAST_7,
           ZIO_ZSTD_LEVEL_FAST_8,
           ZIO_ZSTD_LEVEL_FAST_9,
           ZIO_ZSTD_LEVEL_FAST_10,
           ZIO_ZSTD_LEVEL_FAST_20,
           ZIO_ZSTD_LEVEL_FAST_30,
           ZIO_ZSTD_LEVEL_FAST_40,
           ZIO_ZSTD_LEVEL_FAST_50,
           ZIO_ZSTD_LEVEL_FAST_60,
           ZIO_ZSTD_LEVEL_FAST_70,
           ZIO_ZSTD_LEVEL_FAST_80,
           ZIO_ZSTD_LEVEL_FAST_90,
           ZIO_ZSTD_LEVEL_FAST_100,
           ZIO_ZSTD_LEVEL_FAST_500,
           ZIO_ZSTD_LEVEL_FAST_1000,
   #define ZIO_ZSTD_LEVEL_FAST_MAX ZIO_ZSTD_LEVEL_FAST_1000
           ZIO_ZSTD_LEVEL_AUTO = 251, /* Reserved for future use */
           ZIO_ZSTD_LEVEL_LEVELS
   };
   
   #define ZIO_COMPRESS_ON_VALUE   ZIO_COMPRESS_LZJB
   #define ZIO_COMPRESS_DEFAULT    ZIO_COMPRESS_OFF
   
   /*
    * On-disk version number.
    */
   #define SPA_VERSION_1                   1ULL
   #define SPA_VERSION_2                   2ULL
   #define SPA_VERSION_3                   3ULL
   #define SPA_VERSION_4                   4ULL
   #define SPA_VERSION_5                   5ULL
   #define SPA_VERSION_6                   6ULL
   #define SPA_VERSION_7                   7ULL
   #define SPA_VERSION_8                   8ULL
   #define SPA_VERSION_9                   9ULL
   #define SPA_VERSION_10                  10ULL
   #define SPA_VERSION_11                  11ULL
   #define SPA_VERSION_12                  12ULL
   #define SPA_VERSION_13                  13ULL
   #define SPA_VERSION_14                  14ULL
   #define SPA_VERSION_15                  15ULL
   #define SPA_VERSION_16                  16ULL
   #define SPA_VERSION_17                  17ULL
   #define SPA_VERSION_18                  18ULL
   #define SPA_VERSION_19                  19ULL
   #define SPA_VERSION_20                  20ULL
   #define SPA_VERSION_21                  21ULL
   #define SPA_VERSION_22                  22ULL
   #define SPA_VERSION_23                  23ULL
   #define SPA_VERSION_24                  24ULL
   #define SPA_VERSION_25                  25ULL
   #define SPA_VERSION_26                  26ULL
   #define SPA_VERSION_27                  27ULL
   #define SPA_VERSION_28                  28ULL
   #define SPA_VERSION_5000                5000ULL
   
   /*
    * When bumping up SPA_VERSION, make sure GRUB ZFS understands the on-disk
    * format change. Go to usr/src/grub/grub-0.97/stage2/{zfs-include/, fsys_zfs*},
    * and do the appropriate changes.  Also bump the version number in
    * usr/src/grub/capability.
    */
   #define SPA_VERSION                     SPA_VERSION_5000
   #define SPA_VERSION_STRING              "5000"
   
   /*
    * Symbolic names for the changes that caused a SPA_VERSION switch.
    * Used in the code when checking for presence or absence of a feature.
    * Feel free to define multiple symbolic names for each version if there
    * were multiple changes to on-disk structures during that version.
    *
    * NOTE: When checking the current SPA_VERSION in your code, be sure
    *       to use spa_version() since it reports the version of the
    *       last synced uberblock.  Checking the in-flight version can
    *       be dangerous in some cases.
    */
   #define SPA_VERSION_INITIAL             SPA_VERSION_1
   #define SPA_VERSION_DITTO_BLOCKS        SPA_VERSION_2
   #define SPA_VERSION_SPARES              SPA_VERSION_3
   #define SPA_VERSION_RAID6               SPA_VERSION_3
   #define SPA_VERSION_BPLIST_ACCOUNT      SPA_VERSION_3
   #define SPA_VERSION_RAIDZ_DEFLATE       SPA_VERSION_3
   #define SPA_VERSION_DNODE_BYTES         SPA_VERSION_3
   #define SPA_VERSION_ZPOOL_HISTORY       SPA_VERSION_4
   #define SPA_VERSION_GZIP_COMPRESSION    SPA_VERSION_5
   #define SPA_VERSION_BOOTFS              SPA_VERSION_6
   #define SPA_VERSION_SLOGS               SPA_VERSION_7
   #define SPA_VERSION_DELEGATED_PERMS     SPA_VERSION_8
   #define SPA_VERSION_FUID                SPA_VERSION_9
   #define SPA_VERSION_REFRESERVATION      SPA_VERSION_9
   #define SPA_VERSION_REFQUOTA            SPA_VERSION_9
   #define SPA_VERSION_UNIQUE_ACCURATE     SPA_VERSION_9
   #define SPA_VERSION_L2CACHE             SPA_VERSION_10
   #define SPA_VERSION_NEXT_CLONES         SPA_VERSION_11
   #define SPA_VERSION_ORIGIN              SPA_VERSION_11
   #define SPA_VERSION_DSL_SCRUB           SPA_VERSION_11
   #define SPA_VERSION_SNAP_PROPS          SPA_VERSION_12
   #define SPA_VERSION_USED_BREAKDOWN      SPA_VERSION_13
   #define SPA_VERSION_PASSTHROUGH_X       SPA_VERSION_14
   #define SPA_VERSION_USERSPACE           SPA_VERSION_15
   #define SPA_VERSION_STMF_PROP           SPA_VERSION_16
   #define SPA_VERSION_RAIDZ3              SPA_VERSION_17
   #define SPA_VERSION_USERREFS            SPA_VERSION_18
   #define SPA_VERSION_HOLES               SPA_VERSION_19
   #define SPA_VERSION_ZLE_COMPRESSION     SPA_VERSION_20
   #define SPA_VERSION_DEDUP               SPA_VERSION_21
   #define SPA_VERSION_RECVD_PROPS         SPA_VERSION_22
   #define SPA_VERSION_SLIM_ZIL            SPA_VERSION_23
   #define SPA_VERSION_SA                  SPA_VERSION_24
   #define SPA_VERSION_SCAN                SPA_VERSION_25
   #define SPA_VERSION_DIR_CLONES          SPA_VERSION_26
   #define SPA_VERSION_DEADLISTS           SPA_VERSION_26
   #define SPA_VERSION_FAST_SNAP           SPA_VERSION_27
   #define SPA_VERSION_MULTI_REPLACE       SPA_VERSION_28
   #define SPA_VERSION_BEFORE_FEATURES     SPA_VERSION_28
   #define SPA_VERSION_FEATURES            SPA_VERSION_5000
   
   #define SPA_VERSION_IS_SUPPORTED(v) \
           (((v) >= SPA_VERSION_INITIAL && (v) <= SPA_VERSION_BEFORE_FEATURES) || \
           ((v) >= SPA_VERSION_FEATURES && (v) <= SPA_VERSION))
   
   /*
    * The following are configuration names used in the nvlist describing a pool's
    * configuration.
    */
   #define ZPOOL_CONFIG_VERSION            "version"
   #define ZPOOL_CONFIG_POOL_NAME          "name"
   #define ZPOOL_CONFIG_POOL_STATE         "state"
   #define ZPOOL_CONFIG_POOL_TXG           "txg"
   #define ZPOOL_CONFIG_POOL_GUID          "pool_guid"
   #define ZPOOL_CONFIG_CREATE_TXG         "create_txg"
   #define ZPOOL_CONFIG_TOP_GUID           "top_guid"
   #define ZPOOL_CONFIG_VDEV_TREE          "vdev_tree"
   #define ZPOOL_CONFIG_TYPE               "type"
   #define ZPOOL_CONFIG_CHILDREN           "children"
   #define ZPOOL_CONFIG_ID                 "id"
   #define ZPOOL_CONFIG_GUID               "guid"
   #define ZPOOL_CONFIG_INDIRECT_OBJECT    "com.delphix:indirect_object"
   #define ZPOOL_CONFIG_INDIRECT_BIRTHS    "com.delphix:indirect_births"
   #define ZPOOL_CONFIG_PREV_INDIRECT_VDEV "com.delphix:prev_indirect_vdev"
   #define ZPOOL_CONFIG_PATH               "path"
   #define ZPOOL_CONFIG_DEVID              "devid"
   #define ZPOOL_CONFIG_METASLAB_ARRAY     "metaslab_array"
   #define ZPOOL_CONFIG_METASLAB_SHIFT     "metaslab_shift"
   #define ZPOOL_CONFIG_ASHIFT             "ashift"
   #define ZPOOL_CONFIG_ASIZE              "asize"
   #define ZPOOL_CONFIG_DTL                "DTL"
   #define ZPOOL_CONFIG_STATS              "stats"
   #define ZPOOL_CONFIG_WHOLE_DISK         "whole_disk"
   #define ZPOOL_CONFIG_ERRCOUNT           "error_count"
   #define ZPOOL_CONFIG_NOT_PRESENT        "not_present"
   #define ZPOOL_CONFIG_SPARES             "spares"
   #define ZPOOL_CONFIG_IS_SPARE           "is_spare"
   #define ZPOOL_CONFIG_NPARITY            "nparity"
   #define ZPOOL_CONFIG_HOSTID             "hostid"
   #define ZPOOL_CONFIG_HOSTNAME           "hostname"
   #define ZPOOL_CONFIG_IS_LOG             "is_log"
   #define ZPOOL_CONFIG_TIMESTAMP          "timestamp" /* not stored on disk */
   #define ZPOOL_CONFIG_FEATURES_FOR_READ  "features_for_read"
   #define ZPOOL_CONFIG_VDEV_CHILDREN      "vdev_children"
   
   /*
    * The persistent vdev state is stored as separate values rather than a single
    * 'vdev_state' entry.  This is because a device can be in multiple states, such
    * as offline and degraded.
    */
   #define ZPOOL_CONFIG_OFFLINE            "offline"
   #define ZPOOL_CONFIG_FAULTED            "faulted"
   #define ZPOOL_CONFIG_DEGRADED           "degraded"
   #define ZPOOL_CONFIG_REMOVED            "removed"
   #define ZPOOL_CONFIG_FRU                "fru"
   #define ZPOOL_CONFIG_AUX_STATE          "aux_state"
   
   #define VDEV_TYPE_ROOT                  "root"
   #define VDEV_TYPE_MIRROR                "mirror"
   #define VDEV_TYPE_REPLACING             "replacing"
   #define VDEV_TYPE_RAIDZ                 "raidz"
   #define VDEV_TYPE_DISK                  "disk"
   #define VDEV_TYPE_FILE                  "file"
   #define VDEV_TYPE_MISSING               "missing"
   #define VDEV_TYPE_HOLE                  "hole"
   #define VDEV_TYPE_SPARE                 "spare"
   #define VDEV_TYPE_LOG                   "log"
   #define VDEV_TYPE_L2CACHE               "l2cache"
   #define VDEV_TYPE_INDIRECT              "indirect"
   
   /*
    * This is needed in userland to report the minimum necessary device size.
    */
   #define SPA_MINDEVSIZE          (64ULL << 20)
   
   /*
    * The location of the pool configuration repository, shared between kernel and
    * userland.
    */
   #define ZPOOL_CACHE             "/boot/zfs/zpool.cache"
   
   /*
    * vdev states are ordered from least to most healthy.
    * A vdev that's CANT_OPEN or below is considered unusable.
    */
   typedef enum vdev_state {
           VDEV_STATE_UNKNOWN = 0, /* Uninitialized vdev                   */
           VDEV_STATE_CLOSED,      /* Not currently open                   */
           VDEV_STATE_OFFLINE,     /* Not allowed to open                  */
           VDEV_STATE_REMOVED,     /* Explicitly removed from system       */
           VDEV_STATE_CANT_OPEN,   /* Tried to open, but failed            */
           VDEV_STATE_FAULTED,     /* External request to fault device     */
           VDEV_STATE_DEGRADED,    /* Replicated vdev with unhealthy kids  */
           VDEV_STATE_HEALTHY      /* Presumed good                        */
   } vdev_state_t;
   
   /*
    * vdev aux states.  When a vdev is in the CANT_OPEN state, the aux field
    * of the vdev stats structure uses these constants to distinguish why.
    */
   typedef enum vdev_aux {
           VDEV_AUX_NONE,          /* no error                             */
           VDEV_AUX_OPEN_FAILED,   /* ldi_open_*() or vn_open() failed     */
           VDEV_AUX_CORRUPT_DATA,  /* bad label or disk contents           */
           VDEV_AUX_NO_REPLICAS,   /* insufficient number of replicas      */
           VDEV_AUX_BAD_GUID_SUM,  /* vdev guid sum doesn't match          */
           VDEV_AUX_TOO_SMALL,     /* vdev size is too small               */
           VDEV_AUX_BAD_LABEL,     /* the label is OK but invalid          */
           VDEV_AUX_VERSION_NEWER, /* on-disk version is too new           */
           VDEV_AUX_VERSION_OLDER, /* on-disk version is too old           */
           VDEV_AUX_SPARED         /* hot spare used in another pool       */
   } vdev_aux_t;
   
   /*
    * pool state.  The following states are written to disk as part of the normal
    * SPA lifecycle: ACTIVE, EXPORTED, DESTROYED, SPARE.  The remaining states are
    * software abstractions used at various levels to communicate pool state.
    */
   typedef enum pool_state {
           POOL_STATE_ACTIVE = 0,          /* In active use                */
           POOL_STATE_EXPORTED,            /* Explicitly exported          */
           POOL_STATE_DESTROYED,           /* Explicitly destroyed         */
           POOL_STATE_SPARE,               /* Reserved for hot spare use   */
           POOL_STATE_UNINITIALIZED,       /* Internal spa_t state         */
           POOL_STATE_UNAVAIL,             /* Internal libzfs state        */
           POOL_STATE_POTENTIALLY_ACTIVE   /* Internal libzfs state        */
   } pool_state_t;
   
   /*
    * The uberblock version is incremented whenever an incompatible on-disk
    * format change is made to the SPA, DMU, or ZAP.
    *
    * Note: the first two fields should never be moved.  When a storage pool
    * is opened, the uberblock must be read off the disk before the version
    * can be checked.  If the ub_version field is moved, we may not detect
    * version mismatch.  If the ub_magic field is moved, applications that
    * expect the magic number in the first word won't work.
    */
   #define UBERBLOCK_MAGIC         0x00bab10c              /* oo-ba-bloc!  */
   #define UBERBLOCK_SHIFT         10                      /* up to 1K     */
   
   #define MMP_MAGIC               0xa11cea11              /* all-see-all  */
   
   #define MMP_INTERVAL_VALID_BIT  0x01
   #define MMP_SEQ_VALID_BIT       0x02
   #define MMP_FAIL_INT_VALID_BIT  0x04
   
   #define MMP_VALID(ubp)          (ubp->ub_magic == UBERBLOCK_MAGIC && \
                                       ubp->ub_mmp_magic == MMP_MAGIC)
   #define MMP_INTERVAL_VALID(ubp) (MMP_VALID(ubp) && (ubp->ub_mmp_config & \
                                       MMP_INTERVAL_VALID_BIT))
   #define MMP_SEQ_VALID(ubp)      (MMP_VALID(ubp) && (ubp->ub_mmp_config & \
                                       MMP_SEQ_VALID_BIT))
   #define MMP_FAIL_INT_VALID(ubp) (MMP_VALID(ubp) && (ubp->ub_mmp_config & \
                                       MMP_FAIL_INT_VALID_BIT))
   
   #define MMP_INTERVAL(ubp)       ((ubp->ub_mmp_config & 0x00000000FFFFFF00) \
                                       >> 8)
   #define MMP_SEQ(ubp)            ((ubp->ub_mmp_config & 0x0000FFFF00000000) \
                                       >> 32)
   #define MMP_FAIL_INT(ubp)       ((ubp->ub_mmp_config & 0xFFFF000000000000) \
                                       >> 48)
   
   typedef struct uberblock {
           uint64_t        ub_magic;       /* UBERBLOCK_MAGIC              */
           uint64_t        ub_version;     /* SPA_VERSION                  */
           uint64_t        ub_txg;         /* txg of last sync             */
           uint64_t        ub_guid_sum;    /* sum of all vdev guids        */
           uint64_t        ub_timestamp;   /* UTC time of last sync        */
           blkptr_t        ub_rootbp;      /* MOS objset_phys_t            */
           /* highest SPA_VERSION supported by software that wrote this txg */
           uint64_t        ub_software_version;
           /* Maybe missing in uberblocks we read, but always written */
           uint64_t        ub_mmp_magic;
           /*
            * If ub_mmp_delay == 0 and ub_mmp_magic is valid, MMP is off.
            * Otherwise, nanosec since last MMP write.
            */
           uint64_t        ub_mmp_delay;
   
           /*
            * The ub_mmp_config contains the multihost write interval, multihost
            * fail intervals, sequence number for sub-second granularity, and
            * valid bit mask.  This layout is as follows:
            *
            *   64      56      48      40      32      24      16      8       0
            *   +-------+-------+-------+-------+-------+-------+-------+-------+
            * 0 | Fail Intervals|      Seq      |   Write Interval (ms) | VALID |
            *   +-------+-------+-------+-------+-------+-------+-------+-------+
            *
            * This allows a write_interval of (2^24/1000)s, over 4.5 hours
            *
            * VALID Bits:
            * - 0x01 - Write Interval (ms)
            * - 0x02 - Sequence number exists
            * - 0x04 - Fail Intervals
            * - 0xf8 - Reserved
            */
           uint64_t        ub_mmp_config;
   
           /*
            * ub_checkpoint_txg indicates two things about the current uberblock:
            *
            * 1] If it is not zero then this uberblock is a checkpoint. If it is
            *    zero, then this uberblock is not a checkpoint.
            *
            * 2] On checkpointed uberblocks, the value of ub_checkpoint_txg is
            *    the ub_txg that the uberblock had at the time we moved it to
            *    the MOS config.
            *
            * The field is set when we checkpoint the uberblock and continues to
            * hold that value even after we've rewound (unlike the ub_txg that
            * is reset to a higher value).
            *
            * Besides checks used to determine whether we are reopening the
            * pool from a checkpointed uberblock [see spa_ld_select_uberblock()],
           * the value of the field is used to determine which ZIL blocks have
           * been allocated according to the ms_sm when we are rewinding to a
           * checkpoint. Specifically, if blk_birth > ub_checkpoint_txg, then
           * the ZIL block is not allocated [see uses of spa_min_claim_txg()].
           */
          uint64_t        ub_checkpoint_txg;
  } uberblock_t;
  
  /*
   * Flags.
   */
  #define DNODE_MUST_BE_ALLOCATED 1
  #define DNODE_MUST_BE_FREE      2
  
  /*
   * Fixed constants.
   */
  #define DNODE_SHIFT             9       /* 512 bytes */
  #define DN_MIN_INDBLKSHIFT      12      /* 4k */
  #define DN_MAX_INDBLKSHIFT      17      /* 128k */
  #define DNODE_BLOCK_SHIFT       14      /* 16k */
  #define DNODE_CORE_SIZE         64      /* 64 bytes for dnode sans blkptrs */
  #define DN_MAX_OBJECT_SHIFT     48      /* 256 trillion (zfs_fid_t limit) */
  #define DN_MAX_OFFSET_SHIFT     64      /* 2^64 bytes in a dnode */
  
  /*
   * Derived constants.
   */
  #define DNODE_MIN_SIZE          (1 << DNODE_SHIFT)
  #define DNODE_MAX_SIZE          (1 << DNODE_BLOCK_SHIFT)
  #define DNODE_BLOCK_SIZE        (1 << DNODE_BLOCK_SHIFT)
  #define DNODE_MIN_SLOTS         (DNODE_MIN_SIZE >> DNODE_SHIFT)
  #define DNODE_MAX_SLOTS         (DNODE_MAX_SIZE >> DNODE_SHIFT)
  #define DN_BONUS_SIZE(dnsize)   ((dnsize) - DNODE_CORE_SIZE - \
          (1 << SPA_BLKPTRSHIFT))
  #define DN_SLOTS_TO_BONUSLEN(slots)     DN_BONUS_SIZE((slots) << DNODE_SHIFT)
  #define DN_OLD_MAX_BONUSLEN             (DN_BONUS_SIZE(DNODE_MIN_SIZE))
  #define DN_MAX_NBLKPTR          ((DNODE_MIN_SIZE - DNODE_CORE_SIZE) >> \
          SPA_BLKPTRSHIFT)
  #define DN_MAX_OBJECT           (1ULL << DN_MAX_OBJECT_SHIFT)
  #define DN_ZERO_BONUSLEN        (DN_BONUS_SIZE(DNODE_MAX_SIZE) + 1)
  
  #define DNODES_PER_BLOCK_SHIFT  (DNODE_BLOCK_SHIFT - DNODE_SHIFT)
  #define DNODES_PER_BLOCK        (1ULL << DNODES_PER_BLOCK_SHIFT)
  #define DNODES_PER_LEVEL_SHIFT  (DN_MAX_INDBLKSHIFT - SPA_BLKPTRSHIFT)
  
  /* The +2 here is a cheesy way to round up */
  #define DN_MAX_LEVELS   (2 + ((DN_MAX_OFFSET_SHIFT - SPA_MINBLOCKSHIFT) / \
          (DN_MIN_INDBLKSHIFT - SPA_BLKPTRSHIFT)))
  
  #define DN_BONUS(dnp)   ((void*)((dnp)->dn_bonus + \
          (((dnp)->dn_nblkptr - 1) * sizeof (blkptr_t))))
  
  #define DN_USED_BYTES(dnp) (((dnp)->dn_flags & DNODE_FLAG_USED_BYTES) ? \
          (dnp)->dn_used : (dnp)->dn_used << SPA_MINBLOCKSHIFT)
  
  #define EPB(blkshift, typeshift)        (1 << (blkshift - typeshift))
  
  /* Is dn_used in bytes?  if not, it's in multiples of SPA_MINBLOCKSIZE */
  #define DNODE_FLAG_USED_BYTES           (1<<0)
  #define DNODE_FLAG_USERUSED_ACCOUNTED   (1<<1)
  
  /* Does dnode have a SA spill blkptr in bonus? */
  #define DNODE_FLAG_SPILL_BLKPTR (1<<2)
  
  typedef struct dnode_phys {
          uint8_t dn_type;                /* dmu_object_type_t */
          uint8_t dn_indblkshift;         /* ln2(indirect block size) */
          uint8_t dn_nlevels;             /* 1=dn_blkptr->data blocks */
          uint8_t dn_nblkptr;             /* length of dn_blkptr */
          uint8_t dn_bonustype;           /* type of data in bonus buffer */
          uint8_t dn_checksum;            /* ZIO_CHECKSUM type */
          uint8_t dn_compress;            /* ZIO_COMPRESS type */
          uint8_t dn_flags;               /* DNODE_FLAG_* */
          uint16_t dn_datablkszsec;       /* data block size in 512b sectors */
          uint16_t dn_bonuslen;           /* length of dn_bonus */
          uint8_t dn_extra_slots;         /* # of subsequent slots consumed */
          uint8_t dn_pad2[3];
  
          /* accounting is protected by dn_dirty_mtx */
          uint64_t dn_maxblkid;           /* largest allocated block ID */
          uint64_t dn_used;               /* bytes (or sectors) of disk space */
  
          uint64_t dn_pad3[4];
  
          /*
           * The tail region is 448 bytes for a 512 byte dnode, and
           * correspondingly larger for larger dnode sizes. The spill
           * block pointer, when present, is always at the end of the tail
           * region. There are three ways this space may be used, using
           * a 512 byte dnode for this diagram:
           *
           * 0       64      128     192     256     320     384     448 (offset)
           * +---------------+---------------+---------------+-------+
           * | dn_blkptr[0]  | dn_blkptr[1]  | dn_blkptr[2]  | /     |
           * +---------------+---------------+---------------+-------+
           * | dn_blkptr[0]  | dn_bonus[0..319]                      |
           * +---------------+-----------------------+---------------+
           * | dn_blkptr[0]  | dn_bonus[0..191]      | dn_spill      |
           * +---------------+-----------------------+---------------+
           */
          union {
                  blkptr_t dn_blkptr[1+DN_OLD_MAX_BONUSLEN/sizeof (blkptr_t)];
                  struct {
                          blkptr_t __dn_ignore1;
                          uint8_t dn_bonus[DN_OLD_MAX_BONUSLEN];
                  };
                  struct {
                          blkptr_t __dn_ignore2;
                          uint8_t __dn_ignore3[DN_OLD_MAX_BONUSLEN -
                              sizeof (blkptr_t)];
                          blkptr_t dn_spill;
                  };
          };
  } dnode_phys_t;
  
  #define DN_SPILL_BLKPTR(dnp)    (blkptr_t *)((char *)(dnp) + \
          (((dnp)->dn_extra_slots + 1) << DNODE_SHIFT) - (1 << SPA_BLKPTRSHIFT))
  
  typedef enum dmu_object_byteswap {
          DMU_BSWAP_UINT8,
          DMU_BSWAP_UINT16,
          DMU_BSWAP_UINT32,
          DMU_BSWAP_UINT64,
          DMU_BSWAP_ZAP,
          DMU_BSWAP_DNODE,
          DMU_BSWAP_OBJSET,
          DMU_BSWAP_ZNODE,
          DMU_BSWAP_OLDACL,
          DMU_BSWAP_ACL,
          /*
           * Allocating a new byteswap type number makes the on-disk format
           * incompatible with any other format that uses the same number.
           *
           * Data can usually be structured to work with one of the
           * DMU_BSWAP_UINT* or DMU_BSWAP_ZAP types.
           */
          DMU_BSWAP_NUMFUNCS
  } dmu_object_byteswap_t;
  
  #define DMU_OT_NEWTYPE 0x80
  #define DMU_OT_METADATA 0x40
  #define DMU_OT_BYTESWAP_MASK 0x3f
  
  /*
   * Defines a uint8_t object type. Object types specify if the data
   * in the object is metadata (boolean) and how to byteswap the data
   * (dmu_object_byteswap_t).
   */
  #define DMU_OT(byteswap, metadata) \
          (DMU_OT_NEWTYPE | \
          ((metadata) ? DMU_OT_METADATA : 0) | \
          ((byteswap) & DMU_OT_BYTESWAP_MASK))
  
  typedef enum dmu_object_type {
          DMU_OT_NONE,
          /* general: */
          DMU_OT_OBJECT_DIRECTORY,        /* ZAP */
          DMU_OT_OBJECT_ARRAY,            /* UINT64 */
          DMU_OT_PACKED_NVLIST,           /* UINT8 (XDR by nvlist_pack/unpack) */
          DMU_OT_PACKED_NVLIST_SIZE,      /* UINT64 */
          DMU_OT_BPOBJ,                   /* UINT64 */
          DMU_OT_BPOBJ_HDR,               /* UINT64 */
          /* spa: */
          DMU_OT_SPACE_MAP_HEADER,        /* UINT64 */
          DMU_OT_SPACE_MAP,               /* UINT64 */
          /* zil: */
          DMU_OT_INTENT_LOG,              /* UINT64 */
          /* dmu: */
          DMU_OT_DNODE,                   /* DNODE */
          DMU_OT_OBJSET,                  /* OBJSET */
          /* dsl: */
          DMU_OT_DSL_DIR,                 /* UINT64 */
          DMU_OT_DSL_DIR_CHILD_MAP,       /* ZAP */
          DMU_OT_DSL_DS_SNAP_MAP,         /* ZAP */
          DMU_OT_DSL_PROPS,               /* ZAP */
          DMU_OT_DSL_DATASET,             /* UINT64 */
          /* zpl: */
          DMU_OT_ZNODE,                   /* ZNODE */
          DMU_OT_OLDACL,                  /* Old ACL */
          DMU_OT_PLAIN_FILE_CONTENTS,     /* UINT8 */
          DMU_OT_DIRECTORY_CONTENTS,      /* ZAP */
          DMU_OT_MASTER_NODE,             /* ZAP */
          DMU_OT_UNLINKED_SET,            /* ZAP */
          /* zvol: */
          DMU_OT_ZVOL,                    /* UINT8 */
          DMU_OT_ZVOL_PROP,               /* ZAP */
          /* other; for testing only! */
          DMU_OT_PLAIN_OTHER,             /* UINT8 */
          DMU_OT_UINT64_OTHER,            /* UINT64 */
          DMU_OT_ZAP_OTHER,               /* ZAP */
          /* new object types: */
          DMU_OT_ERROR_LOG,               /* ZAP */
          DMU_OT_SPA_HISTORY,             /* UINT8 */
          DMU_OT_SPA_HISTORY_OFFSETS,     /* spa_his_phys_t */
          DMU_OT_POOL_PROPS,              /* ZAP */
          DMU_OT_DSL_PERMS,               /* ZAP */
          DMU_OT_ACL,                     /* ACL */
          DMU_OT_SYSACL,                  /* SYSACL */
          DMU_OT_FUID,                    /* FUID table (Packed NVLIST UINT8) */
          DMU_OT_FUID_SIZE,               /* FUID table size UINT64 */
          DMU_OT_NEXT_CLONES,             /* ZAP */
          DMU_OT_SCAN_QUEUE,              /* ZAP */
          DMU_OT_USERGROUP_USED,          /* ZAP */
          DMU_OT_USERGROUP_QUOTA,         /* ZAP */
          DMU_OT_USERREFS,                /* ZAP */
          DMU_OT_DDT_ZAP,                 /* ZAP */
          DMU_OT_DDT_STATS,               /* ZAP */
          DMU_OT_SA,                      /* System attr */
          DMU_OT_SA_MASTER_NODE,          /* ZAP */
          DMU_OT_SA_ATTR_REGISTRATION,    /* ZAP */
          DMU_OT_SA_ATTR_LAYOUTS,         /* ZAP */
          DMU_OT_SCAN_XLATE,              /* ZAP */
          DMU_OT_DEDUP,                   /* fake dedup BP from ddt_bp_create() */
          DMU_OT_DEADLIST,                /* ZAP */
          DMU_OT_DEADLIST_HDR,            /* UINT64 */
          DMU_OT_DSL_CLONES,              /* ZAP */
          DMU_OT_BPOBJ_SUBOBJ,            /* UINT64 */
          DMU_OT_NUMTYPES,
  
          /*
           * Names for valid types declared with DMU_OT().
           */
          DMU_OTN_UINT8_DATA = DMU_OT(DMU_BSWAP_UINT8, B_FALSE),
          DMU_OTN_UINT8_METADATA = DMU_OT(DMU_BSWAP_UINT8, B_TRUE),
          DMU_OTN_UINT16_DATA = DMU_OT(DMU_BSWAP_UINT16, B_FALSE),
          DMU_OTN_UINT16_METADATA = DMU_OT(DMU_BSWAP_UINT16, B_TRUE),
          DMU_OTN_UINT32_DATA = DMU_OT(DMU_BSWAP_UINT32, B_FALSE),
          DMU_OTN_UINT32_METADATA = DMU_OT(DMU_BSWAP_UINT32, B_TRUE),
          DMU_OTN_UINT64_DATA = DMU_OT(DMU_BSWAP_UINT64, B_FALSE),
          DMU_OTN_UINT64_METADATA = DMU_OT(DMU_BSWAP_UINT64, B_TRUE),
          DMU_OTN_ZAP_DATA = DMU_OT(DMU_BSWAP_ZAP, B_FALSE),
          DMU_OTN_ZAP_METADATA = DMU_OT(DMU_BSWAP_ZAP, B_TRUE)
  } dmu_object_type_t;
  
  typedef enum dmu_objset_type {
          DMU_OST_NONE,
          DMU_OST_META,
          DMU_OST_ZFS,
          DMU_OST_ZVOL,
          DMU_OST_OTHER,                  /* For testing only! */
          DMU_OST_ANY,                    /* Be careful! */
          DMU_OST_NUMTYPES
  } dmu_objset_type_t;
  
  #define ZAP_MAXVALUELEN (1024 * 8)
  
  /*
   * header for all bonus and spill buffers.
   * The header has a fixed portion with a variable number
   * of "lengths" depending on the number of variable sized
   * attribues which are determined by the "layout number"
   */
  
  #define SA_MAGIC        0x2F505A  /* ZFS SA */
  typedef struct sa_hdr_phys {
          uint32_t sa_magic;
          uint16_t sa_layout_info;  /* Encoded with hdrsize and layout number */
          uint16_t sa_lengths[1]; /* optional sizes for variable length attrs */
          /* ... Data follows the lengths.  */
  } sa_hdr_phys_t;
  
  /*
   * sa_hdr_phys -> sa_layout_info
   *
   * 16      10       0
   * +--------+-------+
   * | hdrsz  |layout |
   * +--------+-------+
   *
   * Bits 0-10 are the layout number
   * Bits 11-16 are the size of the header.
   * The hdrsize is the number * 8
   *
   * For example.
   * hdrsz of 1 ==> 8 byte header
   *          2 ==> 16 byte header
   *
   */
  
  #define SA_HDR_LAYOUT_NUM(hdr) BF32_GET(hdr->sa_layout_info, 0, 10)
  #define SA_HDR_SIZE(hdr) BF32_GET_SB(hdr->sa_layout_info, 10, 16, 3, 0)
  #define SA_HDR_LAYOUT_INFO_ENCODE(x, num, size) \
  { \
          BF32_SET_SB(x, 10, 6, 3, 0, size); \
          BF32_SET(x, 0, 10, num); \
  }
  
  #define SA_ATTR_BSWAP(x)        BF32_GET(x, 16, 8)
  #define SA_ATTR_LENGTH(x)       BF32_GET(x, 24, 16)
  #define SA_ATTR_NUM(x)          BF32_GET(x, 0, 16)
  #define SA_ATTR_ENCODE(x, attr, length, bswap) \
  { \
          BF64_SET(x, 24, 16, length); \
          BF64_SET(x, 16, 8, bswap); \
          BF64_SET(x, 0, 16, attr); \
  }
  
  #define SA_MODE_OFFSET          0
  #define SA_SIZE_OFFSET          8
  #define SA_GEN_OFFSET           16
  #define SA_UID_OFFSET           24
  #define SA_GID_OFFSET           32
  #define SA_PARENT_OFFSET        40
  #define SA_SYMLINK_OFFSET       160
  
  #define SA_REGISTRY     "REGISTRY"
  #define SA_LAYOUTS      "LAYOUTS"
  
  typedef enum sa_bswap_type {
          SA_UINT64_ARRAY,
          SA_UINT32_ARRAY,
          SA_UINT16_ARRAY,
          SA_UINT8_ARRAY,
          SA_ACL,
  } sa_bswap_type_t;
  
  typedef uint16_t        sa_attr_type_t;
  
  #define ZIO_OBJSET_MAC_LEN              32
  
  /*
   * Intent log header - this on disk structure holds fields to manage
   * the log.  All fields are 64 bit to easily handle cross architectures.
   */
  typedef struct zil_header {
          uint64_t zh_claim_txg;  /* txg in which log blocks were claimed */
          uint64_t zh_replay_seq; /* highest replayed sequence number */
          blkptr_t zh_log;        /* log chain */
          uint64_t zh_claim_seq;  /* highest claimed sequence number */
          uint64_t zh_pad[5];
  } zil_header_t;
  
  #define OBJSET_PHYS_SIZE_V2 2048
  #define OBJSET_PHYS_SIZE_V3 4096
  
  typedef struct objset_phys {
          dnode_phys_t os_meta_dnode;
          zil_header_t os_zil_header;
          uint64_t os_type;
          uint64_t os_flags;
          uint8_t os_portable_mac[ZIO_OBJSET_MAC_LEN];
          uint8_t os_local_mac[ZIO_OBJSET_MAC_LEN];
          char os_pad0[OBJSET_PHYS_SIZE_V2 - sizeof (dnode_phys_t)*3 -
                  sizeof (zil_header_t) - sizeof (uint64_t)*2 -
                  2*ZIO_OBJSET_MAC_LEN];
          dnode_phys_t os_userused_dnode;
          dnode_phys_t os_groupused_dnode;
          dnode_phys_t os_projectused_dnode;
          char os_pad1[OBJSET_PHYS_SIZE_V3 - OBJSET_PHYS_SIZE_V2 -
              sizeof (dnode_phys_t)];
  } objset_phys_t;
  
  typedef struct space_map_phys {
          /* object number: not needed but kept for backwards compatibility */
          uint64_t        smp_object;
  
          /* length of the object in bytes */
          uint64_t        smp_length;
  
          /* space allocated from the map */
          int64_t         smp_alloc;
  } space_map_phys_t;
  
  typedef enum {
          SM_ALLOC,
          SM_FREE
  } maptype_t;
  
  /* one-word entry constants */
  #define SM_DEBUG_PREFIX 2
  #define SM_OFFSET_BITS  47
  #define SM_RUN_BITS     15
  
  /* two-word entry constants */
  #define SM2_PREFIX      3
  #define SM2_OFFSET_BITS 63
  #define SM2_RUN_BITS    36
  
  #define SM_PREFIX_DECODE(x)     BF64_DECODE(x, 62, 2)
  #define SM_PREFIX_ENCODE(x)     BF64_ENCODE(x, 62, 2)
  
  #define SM_DEBUG_ACTION_DECODE(x)       BF64_DECODE(x, 60, 2)
  #define SM_DEBUG_ACTION_ENCODE(x)       BF64_ENCODE(x, 60, 2)
  #define SM_DEBUG_SYNCPASS_DECODE(x)     BF64_DECODE(x, 50, 10)
  #define SM_DEBUG_SYNCPASS_ENCODE(x)     BF64_ENCODE(x, 50, 10)
  #define SM_DEBUG_TXG_DECODE(x)          BF64_DECODE(x, 0, 50)
  #define SM_DEBUG_TXG_ENCODE(x)          BF64_ENCODE(x, 0, 50)
  
  #define SM_OFFSET_DECODE(x)     BF64_DECODE(x, 16, SM_OFFSET_BITS)
  #define SM_OFFSET_ENCODE(x)     BF64_ENCODE(x, 16, SM_OFFSET_BITS)
  #define SM_TYPE_DECODE(x)       BF64_DECODE(x, 15, 1)
  #define SM_TYPE_ENCODE(x)       BF64_ENCODE(x, 15, 1)
  #define SM_RUN_DECODE(x)        (BF64_DECODE(x, 0, SM_RUN_BITS) + 1)
  #define SM_RUN_ENCODE(x)        BF64_ENCODE((x) - 1, 0, SM_RUN_BITS)
  #define SM_RUN_MAX              SM_RUN_DECODE(~0ULL)
  #define SM_OFFSET_MAX           SM_OFFSET_DECODE(~0ULL)
  
  #define SM2_RUN_DECODE(x)       (BF64_DECODE(x, 24, SM2_RUN_BITS) + 1)
  #define SM2_RUN_ENCODE(x)       BF64_ENCODE((x) - 1, 24, SM2_RUN_BITS)
  #define SM2_VDEV_DECODE(x)      BF64_DECODE(x, 0, 24)
  #define SM2_VDEV_ENCODE(x)      BF64_ENCODE(x, 0, 24)
  #define SM2_TYPE_DECODE(x)      BF64_DECODE(x, SM2_OFFSET_BITS, 1)
  #define SM2_TYPE_ENCODE(x)      BF64_ENCODE(x, SM2_OFFSET_BITS, 1)
  #define SM2_OFFSET_DECODE(x)    BF64_DECODE(x, 0, SM2_OFFSET_BITS)
  #define SM2_OFFSET_ENCODE(x)    BF64_ENCODE(x, 0, SM2_OFFSET_BITS)
  #define SM2_RUN_MAX             SM2_RUN_DECODE(~0ULL)
  #define SM2_OFFSET_MAX          SM2_OFFSET_DECODE(~0ULL)
  
  typedef struct dsl_dir_phys {
          uint64_t dd_creation_time; /* not actually used */
          uint64_t dd_head_dataset_obj;
          uint64_t dd_parent_obj;
          uint64_t dd_clone_parent_obj;
          uint64_t dd_child_dir_zapobj;
          /*
           * how much space our children are accounting for; for leaf
           * datasets, == physical space used by fs + snaps
           */
          uint64_t dd_used_bytes;
          uint64_t dd_compressed_bytes;
          uint64_t dd_uncompressed_bytes;
          /* Administrative quota setting */
          uint64_t dd_quota;
          /* Administrative reservation setting */
          uint64_t dd_reserved;
          uint64_t dd_props_zapobj;
          uint64_t dd_pad[7];
          uint64_t dd_clones;
          uint64_t dd_pad1[13]; /* pad out to 256 bytes for good measure */
  } dsl_dir_phys_t;
  
  typedef struct dsl_dataset_phys {
          uint64_t ds_dir_obj;
          uint64_t ds_prev_snap_obj;
          uint64_t ds_prev_snap_txg;
          uint64_t ds_next_snap_obj;
          uint64_t ds_snapnames_zapobj;   /* zap obj of snaps; ==0 for snaps */
          uint64_t ds_num_children;       /* clone/snap children; ==0 for head */
          uint64_t ds_creation_time;      /* seconds since 1970 */
          uint64_t ds_creation_txg;
          uint64_t ds_deadlist_obj;
          uint64_t ds_used_bytes;
          uint64_t ds_compressed_bytes;
          uint64_t ds_uncompressed_bytes;
          uint64_t ds_unique_bytes;       /* only relevant to snapshots */
          /*
           * The ds_fsid_guid is a 56-bit ID that can change to avoid
           * collisions.  The ds_guid is a 64-bit ID that will never
           * change, so there is a small probability that it will collide.
           */
          uint64_t ds_fsid_guid;
          uint64_t ds_guid;
          uint64_t ds_flags;
          blkptr_t ds_bp;
          uint64_t ds_pad[8]; /* pad out to 320 bytes for good measure */
  } dsl_dataset_phys_t;
  
  typedef struct dsl_deadlist_phys {
          uint64_t dl_used;
          uint64_t dl_comp;
          uint64_t dl_uncomp;
          uint64_t dl_pad[37]; /* pad out to 320b for future expansion */
  } dsl_deadlist_phys_t;
  
  #define BPOBJ_SIZE_V2   (6 * sizeof (uint64_t))
  
  typedef struct bpobj_phys {
          uint64_t        bpo_num_blkptrs;
          uint64_t        bpo_bytes;
          uint64_t        bpo_comp;
          uint64_t        bpo_uncomp;
          uint64_t        bpo_subobjs;
          uint64_t        bpo_num_subobjs;
          uint64_t        bpo_num_freed;
  } bpobj_phys_t;
  
  /*
   * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
   */
  #define DMU_POOL_DIRECTORY_OBJECT       1
  #define DMU_POOL_CONFIG                 "config"
  #define DMU_POOL_FEATURES_FOR_READ      "features_for_read"
  #define DMU_POOL_FEATURES_FOR_WRITE     "features_for_write"
  #define DMU_POOL_FEATURE_DESCRIPTIONS   "feature_descriptions"
  #define DMU_POOL_ROOT_DATASET           "root_dataset"
  #define DMU_POOL_SYNC_BPLIST            "sync_bplist"
  #define DMU_POOL_ERRLOG_SCRUB           "errlog_scrub"
  #define DMU_POOL_ERRLOG_LAST            "errlog_last"
  #define DMU_POOL_SPARES                 "spares"
  #define DMU_POOL_DEFLATE                "deflate"
  #define DMU_POOL_HISTORY                "history"
  #define DMU_POOL_PROPS                  "pool_props"
  #define DMU_POOL_FREE_BPOBJ             "free_bpobj"
  #define DMU_POOL_BPTREE_OBJ             "bptree_obj"
  #define DMU_POOL_EMPTY_BPOBJ            "empty_bpobj"
  #define DMU_POOL_TMP_USERREFS           "tmp_userrefs"
  #define DMU_POOL_CHECKSUM_SALT          "org.illumos:checksum_salt"
  #define DMU_POOL_REMOVING               "com.delphix:removing"
  #define DMU_POOL_OBSOLETE_BPOBJ         "com.delphix:obsolete_bpobj"
  #define DMU_POOL_CONDENSING_INDIRECT    "com.delphix:condensing_indirect"
  #define DMU_POOL_ZPOOL_CHECKPOINT       "com.delphix:zpool_checkpoint"
  
  #define ZAP_MAGIC 0x2F52AB2ABULL
  
  #define FZAP_BLOCK_SHIFT(zap)   ((zap)->zap_block_shift)
  
  #define ZAP_MAXCD               (uint32_t)(-1)
  #define ZAP_HASHBITS            28
  #define MZAP_ENT_LEN            64
  #define MZAP_ENT_MAX            \
          ((MZAP_MAX_BLKSZ - sizeof(mzap_phys_t)) / sizeof(mzap_ent_phys_t) + 1)
  #define MZAP_NAME_LEN           (MZAP_ENT_LEN - 8 - 4 - 2)
  #define MZAP_MAX_BLKSZ          SPA_OLDMAXBLOCKSIZE
  
  typedef struct mzap_ent_phys {
          uint64_t mze_value;
          uint32_t mze_cd;
          uint16_t mze_pad;       /* in case we want to chain them someday */
          char mze_name[MZAP_NAME_LEN];
  } mzap_ent_phys_t;
  
  typedef struct mzap_phys {
          uint64_t mz_block_type; /* ZBT_MICRO */
          uint64_t mz_salt;
          uint64_t mz_normflags;
          uint64_t mz_pad[5];
          mzap_ent_phys_t mz_chunk[1];
          /* actually variable size depending on block size */
  } mzap_phys_t;
  
  /*
   * The (fat) zap is stored in one object. It is an array of
   * 1<<FZAP_BLOCK_SHIFT byte blocks. The layout looks like one of:
   *
   * ptrtbl fits in first block:
   *      [zap_phys_t zap_ptrtbl_shift < 6] [zap_leaf_t] ...
   *
   * ptrtbl too big for first block:
   *      [zap_phys_t zap_ptrtbl_shift >= 6] [zap_leaf_t] [ptrtbl] ...
   *
   */
  
  #define ZBT_LEAF                ((1ULL << 63) + 0)
  #define ZBT_HEADER              ((1ULL << 63) + 1)
  #define ZBT_MICRO               ((1ULL << 63) + 3)
  /* any other values are ptrtbl blocks */
  
  /*
   * the embedded pointer table takes up half a block:
   * block size / entry size (2^3) / 2
   */
  #define ZAP_EMBEDDED_PTRTBL_SHIFT(zap) (FZAP_BLOCK_SHIFT(zap) - 3 - 1)
  
  /*
   * The embedded pointer table starts half-way through the block.  Since
   * the pointer table itself is half the block, it starts at (64-bit)
   * word number (1<<ZAP_EMBEDDED_PTRTBL_SHIFT(zap)).
   */
  #define ZAP_EMBEDDED_PTRTBL_ENT(zap, idx) \
          ((uint64_t *)(zap)->zap_phys) \
          [(idx) + (1<<ZAP_EMBEDDED_PTRTBL_SHIFT(zap))]
  
  #define ZAP_HASH_IDX(hash, n)   (((n) == 0) ? 0 : ((hash) >> (64 - (n))))
  
  /*
   * TAKE NOTE:
   * If zap_phys_t is modified, zap_byteswap() must be modified.
   */
  typedef struct zap_phys {
          uint64_t zap_block_type;        /* ZBT_HEADER */
          uint64_t zap_magic;             /* ZAP_MAGIC */
  
          struct zap_table_phys {
                  uint64_t zt_blk;        /* starting block number */
                  uint64_t zt_numblks;    /* number of blocks */
                  uint64_t zt_shift;      /* bits to index it */
                  uint64_t zt_nextblk;    /* next (larger) copy start block */
                  uint64_t zt_blks_copied; /* number source blocks copied */
          } zap_ptrtbl;
  
          uint64_t zap_freeblk;           /* the next free block */
          uint64_t zap_num_leafs;         /* number of leafs */
          uint64_t zap_num_entries;       /* number of entries */
          uint64_t zap_salt;              /* salt to stir into hash function */
          uint64_t zap_normflags;         /* flags for u8_textprep_str() */
          uint64_t zap_flags;             /* zap_flags_t */
          /*
           * This structure is followed by padding, and then the embedded
           * pointer table.  The embedded pointer table takes up second
           * half of the block.  It is accessed using the
           * ZAP_EMBEDDED_PTRTBL_ENT() macro.
           */
  } zap_phys_t;
  
  typedef struct zap_table_phys zap_table_phys_t;
  
  struct spa;
  typedef struct fat_zap {
          int zap_block_shift;                    /* block size shift */
          zap_phys_t *zap_phys;
          const struct spa *zap_spa;
          const dnode_phys_t *zap_dnode;
  } fat_zap_t;
  
  #define ZAP_LEAF_MAGIC 0x2AB1EAF
  
  /* chunk size = 24 bytes */
  #define ZAP_LEAF_CHUNKSIZE 24
  
  /*
   * The amount of space available for chunks is:
   * block size (1<<l->l_bs) - hash entry size (2) * number of hash
   * entries - header space (2*chunksize)
   */
  #define ZAP_LEAF_NUMCHUNKS(l) \
          (((1<<(l)->l_bs) - 2*ZAP_LEAF_HASH_NUMENTRIES(l)) / \
          ZAP_LEAF_CHUNKSIZE - 2)
  
  /*
   * The amount of space within the chunk available for the array is:
   * chunk size - space for type (1) - space for next pointer (2)
   */
  #define ZAP_LEAF_ARRAY_BYTES (ZAP_LEAF_CHUNKSIZE - 3)
  
  #define ZAP_LEAF_ARRAY_NCHUNKS(bytes) \
          (((bytes)+ZAP_LEAF_ARRAY_BYTES-1)/ZAP_LEAF_ARRAY_BYTES)
  
  /*
   * Low water mark:  when there are only this many chunks free, start
   * growing the ptrtbl.  Ideally, this should be larger than a
   * "reasonably-sized" entry.  20 chunks is more than enough for the
   * largest directory entry (MAXNAMELEN (256) byte name, 8-byte value),
   * while still being only around 3% for 16k blocks.
   */
  #define ZAP_LEAF_LOW_WATER (20)
  
  /*
   * The leaf hash table has block size / 2^5 (32) number of entries,
   * which should be more than enough for the maximum number of entries,
   * which is less than block size / CHUNKSIZE (24) / minimum number of
   * chunks per entry (3).
   */
  #define ZAP_LEAF_HASH_SHIFT(l) ((l)->l_bs - 5)
  #define ZAP_LEAF_HASH_NUMENTRIES(l) (1 << ZAP_LEAF_HASH_SHIFT(l))
  
  /*
   * The chunks start immediately after the hash table.  The end of the
   * hash table is at l_hash + HASH_NUMENTRIES, which we simply cast to a
   * chunk_t.
   */
  #define ZAP_LEAF_CHUNK(l, idx) \
          ((zap_leaf_chunk_t *)(void *) \
          ((l)->l_phys->l_hash + ZAP_LEAF_HASH_NUMENTRIES(l)))[idx]
  #define ZAP_LEAF_ENTRY(l, idx) (&ZAP_LEAF_CHUNK(l, idx).l_entry)
  
  #define ZAP_LEAF_HASH(l, h) \
          ((ZAP_LEAF_HASH_NUMENTRIES(l)-1) & \
          ((h) >> \
          (64 - ZAP_LEAF_HASH_SHIFT(l) - (l)->l_phys->l_hdr.lh_prefix_len)))
  #define ZAP_LEAF_HASH_ENTPTR(l, h) (&(l)->l_phys->l_hash[ZAP_LEAF_HASH(l, h)])
  
  typedef enum zap_chunk_type {
          ZAP_CHUNK_FREE = 253,
          ZAP_CHUNK_ENTRY = 252,
          ZAP_CHUNK_ARRAY = 251,
          ZAP_CHUNK_TYPE_MAX = 250
  } zap_chunk_type_t;
  
  /*
   * TAKE NOTE:
   * If zap_leaf_phys_t is modified, zap_leaf_byteswap() must be modified.
   */
  typedef struct zap_leaf_phys {
          struct zap_leaf_header {
                  uint64_t lh_block_type;         /* ZBT_LEAF */
                  uint64_t lh_pad1;
                  uint64_t lh_prefix;             /* hash prefix of this leaf */
                  uint32_t lh_magic;              /* ZAP_LEAF_MAGIC */
                  uint16_t lh_nfree;              /* number free chunks */
                  uint16_t lh_nentries;           /* number of entries */
                  uint16_t lh_prefix_len;         /* num bits used to id this */
  
  /* above is accessable to zap, below is zap_leaf private */
  
                  uint16_t lh_freelist;           /* chunk head of free list */
                  uint8_t lh_pad2[12];
          } l_hdr; /* 2 24-byte chunks */
  
          /*
           * The header is followed by a hash table with
           * ZAP_LEAF_HASH_NUMENTRIES(zap) entries.  The hash table is
           * followed by an array of ZAP_LEAF_NUMCHUNKS(zap)
           * zap_leaf_chunk structures.  These structures are accessed
           * with the ZAP_LEAF_CHUNK() macro.
           */
  
          uint16_t l_hash[1];
  } zap_leaf_phys_t;
  
  typedef union zap_leaf_chunk {
          struct zap_leaf_entry {
                  uint8_t le_type;                /* always ZAP_CHUNK_ENTRY */
                  uint8_t le_value_intlen;        /* size of ints */
                  uint16_t le_next;               /* next entry in hash chain */
                  uint16_t le_name_chunk;         /* first chunk of the name */
                  uint16_t le_name_numints;       /* bytes in name, incl null */
                  uint16_t le_value_chunk;        /* first chunk of the value */
                  uint16_t le_value_numints;      /* value length in ints */
                  uint32_t le_cd;                 /* collision differentiator */
                  uint64_t le_hash;               /* hash value of the name */
          } l_entry;
          struct zap_leaf_array {
                  uint8_t la_type;                /* always ZAP_CHUNK_ARRAY */
                  uint8_t la_array[ZAP_LEAF_ARRAY_BYTES];
                  uint16_t la_next;               /* next blk or CHAIN_END */
          } l_array;
          struct zap_leaf_free {
                  uint8_t lf_type;                /* always ZAP_CHUNK_FREE */
                  uint8_t lf_pad[ZAP_LEAF_ARRAY_BYTES];
                  uint16_t lf_next;       /* next in free list, or CHAIN_END */
          } l_free;
  } zap_leaf_chunk_t;
  
  typedef struct zap_leaf {
          int l_bs;                       /* block size shift */
          zap_leaf_phys_t *l_phys;
  } zap_leaf_t;
  
  #define ZAP_MAXNAMELEN 256
  #define ZAP_MAXVALUELEN (1024 * 8)
  
  #define ACE_READ_DATA           0x00000001      /* file: read data */
  #define ACE_LIST_DIRECTORY      0x00000001      /* dir: list files */
  #define ACE_WRITE_DATA          0x00000002      /* file: write data */
  #define ACE_ADD_FILE            0x00000002      /* dir: create file */
  #define ACE_APPEND_DATA         0x00000004      /* file: append data */
  #define ACE_ADD_SUBDIRECTORY    0x00000004      /* dir: create subdir */
  #define ACE_READ_NAMED_ATTRS    0x00000008      /* FILE_READ_EA */
  #define ACE_WRITE_NAMED_ATTRS   0x00000010      /* FILE_WRITE_EA */
  #define ACE_EXECUTE             0x00000020      /* file: execute */
  #define ACE_TRAVERSE            0x00000020      /* dir: lookup name */
  #define ACE_DELETE_CHILD        0x00000040      /* dir: unlink child */
  #define ACE_READ_ATTRIBUTES     0x00000080      /* (all) stat, etc. */
  #define ACE_WRITE_ATTRIBUTES    0x00000100      /* (all) utimes, etc. */
  #define ACE_DELETE              0x00010000      /* (all) unlink self */
  #define ACE_READ_ACL            0x00020000      /* (all) getsecattr */
  #define ACE_WRITE_ACL           0x00040000      /* (all) setsecattr */
  #define ACE_WRITE_OWNER         0x00080000      /* (all) chown */
  #define ACE_SYNCHRONIZE         0x00100000      /* (all) */
  
  #define ACE_FILE_INHERIT_ACE            0x0001
  #define ACE_DIRECTORY_INHERIT_ACE       0x0002
  #define ACE_NO_PROPAGATE_INHERIT_ACE    0x0004
  #define ACE_INHERIT_ONLY_ACE            0x0008
  #define ACE_SUCCESSFUL_ACCESS_ACE_FLAG  0x0010
  #define ACE_FAILED_ACCESS_ACE_FLAG      0x0020
  #define ACE_IDENTIFIER_GROUP            0x0040
  #define ACE_INHERITED_ACE               0x0080
  #define ACE_OWNER                       0x1000
  #define ACE_GROUP                       0x2000
  #define ACE_EVERYONE                    0x4000
  
  #define ACE_ACCESS_ALLOWED_ACE_TYPE     0x0000
  #define ACE_ACCESS_DENIED_ACE_TYPE      0x0001
  #define ACE_SYSTEM_AUDIT_ACE_TYPE       0x0002
  #define ACE_SYSTEM_ALARM_ACE_TYPE       0x0003
  
  typedef struct zfs_ace_hdr {
          uint16_t z_type;
          uint16_t z_flags;
          uint32_t z_access_mask;
  } zfs_ace_hdr_t;
  
  /*
   * Define special zfs pflags
   */
  #define ZFS_XATTR               0x1             /* is an extended attribute */
  #define ZFS_INHERIT_ACE         0x2             /* ace has inheritable ACEs */
  #define ZFS_ACL_TRIVIAL         0x4             /* files ACL is trivial */
  #define ZFS_ACL_OBJ_ACE         0x8             /* ACL has CMPLX Object ACE */
  #define ZFS_ACL_PROTECTED       0x10            /* ACL protected */
  #define ZFS_ACL_DEFAULTED       0x20            /* ACL should be defaulted */
  #define ZFS_ACL_AUTO_INHERIT    0x40            /* ACL should be inherited */
  #define ZFS_BONUS_SCANSTAMP     0x80            /* Scanstamp in bonus area */
  #define ZFS_NO_EXECS_DENIED     0x100           /* exec was given to everyone */
  
  #define ZFS_READONLY            0x0000000100000000ull
  #define ZFS_HIDDEN              0x0000000200000000ull
  #define ZFS_SYSTEM              0x0000000400000000ull
  #define ZFS_ARCHIVE             0x0000000800000000ull
  #define ZFS_IMMUTABLE           0x0000001000000000ull
  #define ZFS_NOUNLINK            0x0000002000000000ull
  #define ZFS_APPENDONLY          0x0000004000000000ull
  #define ZFS_NODUMP              0x0000008000000000ull
  #define ZFS_OPAQUE              0x0000010000000000ull
  #define ZFS_AV_QUARANTINED      0x0000020000000000ull
  #define ZFS_AV_MODIFIED         0x0000040000000000ull
  #define ZFS_REPARSE             0x0000080000000000ull
  #define ZFS_OFFLINE             0x0000100000000000ull
  #define ZFS_SPARSE              0x0000200000000000ull
  
  #define MASTER_NODE_OBJ 1
  
  /*
   * special attributes for master node.
   */
  
  #define ZFS_FSID                "FSID"
  #define ZFS_UNLINKED_SET        "DELETE_QUEUE"
  #define ZFS_ROOT_OBJ            "ROOT"
  #define ZPL_VERSION_OBJ         "VERSION"
  #define ZFS_PROP_BLOCKPERPAGE   "BLOCKPERPAGE"
  #define ZFS_PROP_NOGROWBLOCKS   "NOGROWBLOCKS"
  #define ZFS_SA_ATTRS            "SA_ATTRS"
  
  #define ZFS_FLAG_BLOCKPERPAGE   0x1
  #define ZFS_FLAG_NOGROWBLOCKS   0x2
  
  /*
   * ZPL version - rev'd whenever an incompatible on-disk format change
   * occurs.  Independent of SPA/DMU/ZAP versioning.
   */
  
  #define ZPL_VERSION             1ULL
  
  /*
   * The directory entry has the type (currently unused on Solaris) in the
   * top 4 bits, and the object number in the low 48 bits.  The "middle"
   * 12 bits are unused.
   */
  #define ZFS_DIRENT_TYPE(de) BF64_GET(de, 60, 4)
  #define ZFS_DIRENT_OBJ(de) BF64_GET(de, 0, 48)
  #define ZFS_DIRENT_MAKE(type, obj) (((uint64_t)type << 60) | obj)
  
  typedef struct ace {
          uid_t           a_who;          /* uid or gid */
          uint32_t        a_access_mask;  /* read,write,... */
          uint16_t        a_flags;        /* see below */
          uint16_t        a_type;         /* allow or deny */
  } ace_t;
  
  #define ACE_SLOT_CNT    6
  
  typedef struct zfs_znode_acl {
          uint64_t        z_acl_extern_obj;         /* ext acl pieces */
          uint32_t        z_acl_count;              /* Number of ACEs */
          uint16_t        z_acl_version;            /* acl version */
          uint16_t        z_acl_pad;                /* pad */
          ace_t           z_ace_data[ACE_SLOT_CNT]; /* 6 standard ACEs */
  } zfs_znode_acl_t;
  
  /*
   * This is the persistent portion of the znode.  It is stored
   * in the "bonus buffer" of the file.  Short symbolic links
   * are also stored in the bonus buffer.
   */
  typedef struct znode_phys {
          uint64_t zp_atime[2];           /*  0 - last file access time */
          uint64_t zp_mtime[2];           /* 16 - last file modification time */
          uint64_t zp_ctime[2];           /* 32 - last file change time */
          uint64_t zp_crtime[2];          /* 48 - creation time */
          uint64_t zp_gen;                /* 64 - generation (txg of creation) */
          uint64_t zp_mode;               /* 72 - file mode bits */
          uint64_t zp_size;               /* 80 - size of file */
          uint64_t zp_parent;             /* 88 - directory parent (`..') */
          uint64_t zp_links;              /* 96 - number of links to file */
          uint64_t zp_xattr;              /* 104 - DMU object for xattrs */
          uint64_t zp_rdev;               /* 112 - dev_t for VBLK & VCHR files */
          uint64_t zp_flags;              /* 120 - persistent flags */
          uint64_t zp_uid;                /* 128 - file owner */
          uint64_t zp_gid;                /* 136 - owning group */
          uint64_t zp_pad[4];             /* 144 - future */
          zfs_znode_acl_t zp_acl;         /* 176 - 263 ACL */
          /*
           * Data may pad out any remaining bytes in the znode buffer, eg:
           *
           * |<---------------------- dnode_phys (512) ------------------------>|
           * |<-- dnode (192) --->|<----------- "bonus" buffer (320) ---------->|
           *                      |<---- znode (264) ---->|<---- data (56) ---->|
           *
           * At present, we only use this space to store symbolic links.
           */
  } znode_phys_t;
  
  /*
   * In-core vdev representation.
   */
  struct vdev;
  struct spa;
  typedef int vdev_phys_read_t(struct vdev *, void *, off_t, void *, size_t);
  typedef int vdev_phys_write_t(struct vdev *, off_t, void *, size_t);
  typedef int vdev_read_t(struct vdev *, const blkptr_t *, void *, off_t, size_t);
  
  typedef STAILQ_HEAD(vdev_list, vdev) vdev_list_t;
  
  typedef struct vdev_indirect_mapping_entry_phys {
          /*
           * Decode with DVA_MAPPING_* macros.
           * Contains:
           *   the source offset (low 63 bits)
           *   the one-bit "mark", used for garbage collection (by zdb)
           */
          uint64_t vimep_src;
  
          /*
           * Note: the DVA's asize is 24 bits, and can thus store ranges
           * up to 8GB.
           */
          dva_t   vimep_dst;
  } vdev_indirect_mapping_entry_phys_t;
  
  #define DVA_MAPPING_GET_SRC_OFFSET(vimep)       \
          BF64_GET_SB((vimep)->vimep_src, 0, 63, SPA_MINBLOCKSHIFT, 0)
  #define DVA_MAPPING_SET_SRC_OFFSET(vimep, x)    \
          BF64_SET_SB((vimep)->vimep_src, 0, 63, SPA_MINBLOCKSHIFT, 0, x)
  
  /*
   * This is stored in the bonus buffer of the mapping object, see comment of
   * vdev_indirect_config for more details.
   */
  typedef struct vdev_indirect_mapping_phys {
          uint64_t        vimp_max_offset;
          uint64_t        vimp_bytes_mapped;
          uint64_t        vimp_num_entries; /* number of v_i_m_entry_phys_t's */
  
          /*
           * For each entry in the mapping object, this object contains an
           * entry representing the number of bytes of that mapping entry
           * that were no longer in use by the pool at the time this indirect
           * vdev was last condensed.
           */
          uint64_t        vimp_counts_object;
  } vdev_indirect_mapping_phys_t;
  
  #define VDEV_INDIRECT_MAPPING_SIZE_V0   (3 * sizeof (uint64_t))
  
  typedef struct vdev_indirect_mapping {
          uint64_t        vim_object;
          boolean_t       vim_havecounts;
  
          /* vim_entries segment offset currently in memory. */
          uint64_t        vim_entry_offset;
          /* vim_entries segment size. */
          size_t          vim_num_entries;
  
          /* Needed by dnode_read() */
          const void      *vim_spa;
          dnode_phys_t    *vim_dn;
  
          /*
           * An ordered array of mapping entries, sorted by source offset.
           * Note that vim_entries is needed during a removal (and contains
           * mappings that have been synced to disk so far) to handle frees
           * from the removing device.
           */
          vdev_indirect_mapping_entry_phys_t *vim_entries;
          objset_phys_t   *vim_objset;
          vdev_indirect_mapping_phys_t    *vim_phys;
  } vdev_indirect_mapping_t;
  
  /*
   * On-disk indirect vdev state.
   *
   * An indirect vdev is described exclusively in the MOS config of a pool.
   * The config for an indirect vdev includes several fields, which are
   * accessed in memory by a vdev_indirect_config_t.
   */
  typedef struct vdev_indirect_config {
          /*
           * Object (in MOS) which contains the indirect mapping. This object
           * contains an array of vdev_indirect_mapping_entry_phys_t ordered by
           * vimep_src. The bonus buffer for this object is a
           * vdev_indirect_mapping_phys_t. This object is allocated when a vdev
           * removal is initiated.
           *
           * Note that this object can be empty if none of the data on the vdev
           * has been copied yet.
           */
          uint64_t        vic_mapping_object;
  
          /*
           * Object (in MOS) which contains the birth times for the mapping
           * entries. This object contains an array of
           * vdev_indirect_birth_entry_phys_t sorted by vibe_offset. The bonus
           * buffer for this object is a vdev_indirect_birth_phys_t. This object
           * is allocated when a vdev removal is initiated.
           *
           * Note that this object can be empty if none of the vdev has yet been
           * copied.
           */
          uint64_t        vic_births_object;
  
  /*
   * This is the vdev ID which was removed previous to this vdev, or
   * UINT64_MAX if there are no previously removed vdevs.
   */
          uint64_t        vic_prev_indirect_vdev;
  } vdev_indirect_config_t;
  
  typedef struct vdev {
          STAILQ_ENTRY(vdev) v_childlink; /* link in parent's child list */
          STAILQ_ENTRY(vdev) v_alllink;   /* link in global vdev list */
          vdev_list_t     v_children;     /* children of this vdev */
          const char      *v_name;        /* vdev name */
          uint64_t        v_guid;         /* vdev guid */
          uint64_t        v_id;           /* index in parent */
          uint64_t        v_psize;        /* physical device capacity */
          int             v_ashift;       /* offset to block shift */
          int             v_nparity;      /* # parity for raidz */
          struct vdev     *v_top;         /* parent vdev */
          size_t          v_nchildren;    /* # children */
          vdev_state_t    v_state;        /* current state */
          vdev_phys_read_t *v_phys_read;  /* read from raw leaf vdev */
          vdev_phys_write_t *v_phys_write; /* write to raw leaf vdev */
          vdev_read_t     *v_read;        /* read from vdev */
          void            *v_priv;        /* data for read/write function */
          boolean_t       v_islog;
          struct spa      *v_spa;         /* link to spa */
          /*
           * Values stored in the config for an indirect or removing vdev.
           */
          vdev_indirect_config_t vdev_indirect_config;
          vdev_indirect_mapping_t *v_mapping;
  } vdev_t;
  
  /*
   * In-core pool representation.
   */
  typedef STAILQ_HEAD(spa_list, spa) spa_list_t;
  
  typedef struct spa {
          STAILQ_ENTRY(spa) spa_link;     /* link in global pool list */
          char            *spa_name;      /* pool name */
          uint64_t        spa_guid;       /* pool guid */
          uint64_t        spa_txg;        /* most recent transaction */
          struct uberblock *spa_uberblock;        /* best uberblock so far */
          vdev_t          *spa_root_vdev; /* toplevel vdev container */
          objset_phys_t   *spa_mos;       /* MOS for this pool */
          zio_cksum_salt_t spa_cksum_salt;        /* secret salt for cksum */
          void            *spa_cksum_tmpls[ZIO_CHECKSUM_FUNCTIONS];
          boolean_t       spa_with_log;   /* this pool has log */
  
          struct uberblock spa_uberblock_master;  /* best uberblock so far */
          objset_phys_t   spa_mos_master;         /* MOS for this pool */
          struct uberblock spa_uberblock_checkpoint; /* checkpoint uberblock */
          objset_phys_t   spa_mos_checkpoint;     /* Checkpoint MOS */
          void            *spa_bootenv;           /* bootenv from pool label */
  } spa_t;
  
  /* IO related arguments. */
  typedef struct zio {
          spa_t           *io_spa;
          blkptr_t        *io_bp;
          void            *io_data;
          uint64_t        io_size;
          uint64_t        io_offset;
  
          /* Stuff for the vdev stack */
          vdev_t          *io_vd;
          void            *io_vsd;
  
          int             io_error;
  } zio_t;
  
  extern void decode_embedded_bp_compressed(const blkptr_t *, void *);
  
  #endif /* _ZFSIMPL_H_ */

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