/*        $NetBSD: hammer2_disk.h,v 1.4 2022/04/04 19:33:46 andvar Exp $      */

/*
* Copyright (c) 2011-2019 The DragonFly Project.  All rights reserved.
*
* This code is derived from software contributed to The DragonFly Project
* by Matthew Dillon <[email protected]>
* by Venkatesh Srinivas <[email protected]>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
* 3. Neither the name of The DragonFly Project nor the names of its
*    contributors may be used to endorse or promote products derived
*    from this software without specific, prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: hammer2_disk.h,v 1.4 2022/04/04 19:33:46 andvar Exp $");

#ifndef _VFS_HAMMER2_DISK_H_
#define _VFS_HAMMER2_DISK_H_

#ifndef _SYS_UUID_H_
#include <sys/uuid.h>
#endif
#if 0
#ifndef _SYS_DMSG_H_
#include <sys/dmsg.h>
#endif
#endif

/*
* The structures below represent the on-disk media structures for the HAMMER2
* filesystem.  Note that all fields for on-disk structures are naturally
* aligned.  The host endian format is typically used - compatibility is
* possible if the implementation detects reversed endian and adjusts accesses
* accordingly.
*
* HAMMER2 primarily revolves around the directory topology:  inodes,
* directory entries, and block tables.  Block device buffer cache buffers
* are always 64KB.  Logical file buffers are typically 16KB.  All data
* references utilize 64-bit byte offsets.
*
* Free block management is handled independently using blocks reserved by
* the media topology.
*/

/*
* The data at the end of a file or directory may be a fragment in order
* to optimize storage efficiency.  The minimum fragment size is 1KB.
* Since allocations are in powers of 2 fragments must also be sized in
* powers of 2 (1024, 2048, ... 65536).
*
* For the moment the maximum allocation size is HAMMER2_PBUFSIZE (64K),
* which is 2^16.  Larger extents may be supported in the future.  Smaller
* fragments might be supported in the future (down to 64 bytes is possible),
* but probably will not be.
*
* A full indirect block use supports 512 x 128-byte blockrefs in a 64KB
* buffer.  Indirect blocks down to 1KB are supported to keep small
* directories small.
*
* A maximally sized file (2^64-1 bytes) requires ~6 indirect block levels
* using 64KB indirect blocks (128 byte refs, 512 or radix 9 per indblk).
*
*      16(datablk) + 9 + 9 + 9 + 9 + 9 + 9 = ~70.
*      16(datablk) + 7 + 9 + 9 + 9 + 9 + 9 = ~68.  (smaller top level indblk)
*
* The actual depth depends on copies redundancy and whether the filesystem
* has chosen to use a smaller indirect block size at the top level or not.
*/
#define HAMMER2_ALLOC_MIN       1024    /* minimum allocation size */
#define HAMMER2_RADIX_MIN       10      /* minimum allocation size 2^N */
#define HAMMER2_ALLOC_MAX       65536   /* maximum allocation size */
#define HAMMER2_RADIX_MAX       16      /* maximum allocation size 2^N */
#define HAMMER2_RADIX_KEY       64      /* number of bits in key */

/*
* HAMMER2_LBUFSIZE     - Nominal buffer size for I/O rollups.
*
* HAMMER2_PBUFSIZE     - Topological block size used by files for all
*                        blocks except the block straddling EOF.
*
* HAMMER2_SEGSIZE      - Allocation map segment size, typically 4MB
*                        (space represented by a level0 bitmap).
*/

#define HAMMER2_SEGSIZE         (1 << HAMMER2_FREEMAP_LEVEL0_RADIX)
#define HAMMER2_SEGRADIX        HAMMER2_FREEMAP_LEVEL0_RADIX

#define HAMMER2_PBUFRADIX       16      /* physical buf (1<<16) bytes */
#define HAMMER2_PBUFSIZE        65536
#define HAMMER2_LBUFRADIX       14      /* logical buf (1<<14) bytes */
#define HAMMER2_LBUFSIZE        16384

#define HAMMER2_IND_BYTES_MIN   4096
#define HAMMER2_IND_BYTES_NOM   HAMMER2_LBUFSIZE
#define HAMMER2_IND_BYTES_MAX   HAMMER2_PBUFSIZE
#define HAMMER2_IND_RADIX_MIN   12
#define HAMMER2_IND_RADIX_NOM   HAMMER2_LBUFRADIX
#define HAMMER2_IND_RADIX_MAX   HAMMER2_PBUFRADIX
#define HAMMER2_IND_COUNT_MIN   (HAMMER2_IND_BYTES_MIN / \
                                sizeof(hammer2_blockref_t))
#define HAMMER2_IND_COUNT_MAX   (HAMMER2_IND_BYTES_MAX / \
                                sizeof(hammer2_blockref_t))

/*
* In HAMMER2, arrays of blockrefs are fully set-associative, meaning that
* any element can occur at any index and holes can be anywhere.
*
* Inodes embed either 512 bytes of direct data or an array of 4 blockrefs,
* resulting in highly efficient storage for files <= 512 bytes and for files
* <= 512KB.  Up to 4 directory entries can be referenced from a directory
* without requiring an indirect block.
*/
#define HAMMER2_SET_RADIX               2       /* radix 2 = 4 entries */
#define HAMMER2_SET_COUNT               (1 << HAMMER2_SET_RADIX)
#define HAMMER2_EMBEDDED_BYTES          512     /* inode blockset/dd size */
#define HAMMER2_EMBEDDED_RADIX          9

#define HAMMER2_PBUFMASK        (HAMMER2_PBUFSIZE - 1)
#define HAMMER2_LBUFMASK        (HAMMER2_LBUFSIZE - 1)
#define HAMMER2_SEGMASK         (HAMMER2_SEGSIZE - 1)

#define HAMMER2_LBUFMASK64      ((hammer2_off_t)HAMMER2_LBUFMASK)
#define HAMMER2_PBUFSIZE64      ((hammer2_off_t)HAMMER2_PBUFSIZE)
#define HAMMER2_PBUFMASK64      ((hammer2_off_t)HAMMER2_PBUFMASK)
#define HAMMER2_SEGSIZE64       ((hammer2_off_t)HAMMER2_SEGSIZE)
#define HAMMER2_SEGMASK64       ((hammer2_off_t)HAMMER2_SEGMASK)

#define HAMMER2_UUID_STRING     "5cbb9ad1-862d-11dc-a94d-01301bb8a9f5"

/*
* A 4MB segment is reserved at the beginning of each 1GB.  This segment
* contains the volume header (or backup volume header), the free block
* table, and possibly other information in the future.
*
* 4MB = 64 x 64K blocks.  Each 4MB segment is broken down as follows:
*
* ==========
*  0 volume header (for the first four 2GB zones)
*  1 freemap00 level1 FREEMAP_LEAF (256 x 128B bitmap data per 1GB)
*  2           level2 FREEMAP_NODE (256 x 128B indirect block per 256GB)
*  3           level3 FREEMAP_NODE (256 x 128B indirect block per 64TB)
*  4           level4 FREEMAP_NODE (256 x 128B indirect block per 16PB)
*  5           level5 FREEMAP_NODE (256 x 128B indirect block per 4EB)
*  6 freemap01 level1 (rotation)
*  7           level2
*  8           level3
*  9           level4
* 10           level5
* 11 freemap02 level1 (rotation)
* 12           level2
* 13           level3
* 14           level4
* 15           level5
* 16 freemap03 level1 (rotation)
* 17           level2
* 18           level3
* 19           level4
* 20           level5
* 21 freemap04 level1 (rotation)
* 22           level2
* 23           level3
* 24           level4
* 25           level5
* 26 freemap05 level1 (rotation)
* 27           level2
* 28           level3
* 29           level4
* 30           level5
* 31 freemap06 level1 (rotation)
* 32           level2
* 33           level3
* 34           level4
* 35           level5
* 36 freemap07 level1 (rotation)
* 37           level2
* 38           level3
* 39           level4
* 40           level5
* 41 unused
* .. unused
* 63 unused
* ==========
*
* The first four 2GB zones contain volume headers and volume header backups.
* After that the volume header block# is reserved for future use.  Similarly,
* there are many blocks related to various Freemap levels which are not
* used in every segment and those are also reserved for future use.
* Note that each FREEMAP_LEAF or FREEMAP_NODE uses 32KB out of 64KB slot.
*
*                      Freemap (see the FREEMAP document)
*
* The freemap utilizes blocks #1-40 in 8 sets of 5 blocks.  Each block in
* a set represents a level of depth in the freemap topology.  Eight sets
* exist to prevent live updates from disturbing the state of the freemap
* were a crash/reboot to occur.  That is, a live update is not committed
* until the update's flush reaches the volume root.  There are FOUR volume
* roots representing the last four synchronization points, so the freemap
* must be consistent no matter which volume root is chosen by the mount
* code.
*
* Each freemap set is 5 x 64K blocks and represents the 1GB, 256GB, 64TB,
* 16PB and 4EB indirect map.  The volume header itself has a set of 4 freemap
* blockrefs representing another 2 bits, giving us a total 64 bits of
* representable address space.
*
* The Level 0 64KB block represents 1GB of storage represented by 32KB
* (256 x struct hammer2_bmap_data).  Each structure represents 4MB of storage
* and has a 512 bit bitmap, using 2 bits to represent a 16KB chunk of
* storage.  These 2 bits represent the following states:
*
*      00      Free
*      01      (reserved) (Possibly partially allocated)
*      10      Possibly free
*      11      Allocated
*
* One important thing to note here is that the freemap resolution is 16KB,
* but the minimum storage allocation size is 1KB.  The hammer2 vfs keeps
* track of sub-allocations in memory, which means that on a unmount or reboot
* the entire 16KB of a partially allocated block will be considered fully
* allocated.  It is possible for fragmentation to build up over time, but
* defragmentation is fairly easy to accomplish since all modifications
* allocate a new block.
*
* The Second thing to note is that due to the way snapshots and inode
* replication works, deleting a file cannot immediately free the related
* space.  Furthermore, deletions often do not bother to traverse the
* block subhierarchy being deleted.  And to go even further, whole
* sub-directory trees can be deleted simply by deleting the directory inode
* at the top.  So even though we have a symbol to represent a 'possibly free'
* block (binary 10), only the bulk free scanning code can actually use it.
* Normal 'rm's or other deletions do not.
*
* WARNING!  ZONE_SEG and VOLUME_ALIGN must be a multiple of 1<<LEVEL0_RADIX
*           (i.e. a multiple of 4MB).  VOLUME_ALIGN must be >= ZONE_SEG.
*
* In Summary:
*
* (1) Modifications to freemap blocks 'allocate' a new copy (aka use a block
*     from the next set).  The new copy is reused until a flush occurs at
*     which point the next modification will then rotate to the next set.
*/
#define HAMMER2_VOLUME_ALIGN            (8 * 1024 * 1024)
#define HAMMER2_VOLUME_ALIGN64          ((hammer2_off_t)HAMMER2_VOLUME_ALIGN)
#define HAMMER2_VOLUME_ALIGNMASK        (HAMMER2_VOLUME_ALIGN - 1)
#define HAMMER2_VOLUME_ALIGNMASK64      ((hammer2_off_t)HAMMER2_VOLUME_ALIGNMASK)

#define HAMMER2_NEWFS_ALIGN             (HAMMER2_VOLUME_ALIGN)
#define HAMMER2_NEWFS_ALIGN64           ((hammer2_off_t)HAMMER2_VOLUME_ALIGN)
#define HAMMER2_NEWFS_ALIGNMASK         (HAMMER2_VOLUME_ALIGN - 1)
#define HAMMER2_NEWFS_ALIGNMASK64       ((hammer2_off_t)HAMMER2_NEWFS_ALIGNMASK)

#define HAMMER2_ZONE_BYTES64            (2LLU * 1024 * 1024 * 1024)
#define HAMMER2_ZONE_MASK64             (HAMMER2_ZONE_BYTES64 - 1)
#define HAMMER2_ZONE_SEG                (4 * 1024 * 1024)
#define HAMMER2_ZONE_SEG64              ((hammer2_off_t)HAMMER2_ZONE_SEG)
#define HAMMER2_ZONE_BLOCKS_SEG         (HAMMER2_ZONE_SEG / HAMMER2_PBUFSIZE)

#define HAMMER2_ZONE_FREEMAP_INC        5       /* 5 deep */

#define HAMMER2_ZONE_VOLHDR             0       /* volume header or backup */
#define HAMMER2_ZONE_FREEMAP_00         1       /* normal freemap rotation */
#define HAMMER2_ZONE_FREEMAP_01         6       /* normal freemap rotation */
#define HAMMER2_ZONE_FREEMAP_02         11      /* normal freemap rotation */
#define HAMMER2_ZONE_FREEMAP_03         16      /* normal freemap rotation */
#define HAMMER2_ZONE_FREEMAP_04         21      /* normal freemap rotation */
#define HAMMER2_ZONE_FREEMAP_05         26      /* normal freemap rotation */
#define HAMMER2_ZONE_FREEMAP_06         31      /* normal freemap rotation */
#define HAMMER2_ZONE_FREEMAP_07         36      /* normal freemap rotation */
#define HAMMER2_ZONE_FREEMAP_END        41      /* (non-inclusive) */

#define HAMMER2_ZONE_UNUSED41           41
#define HAMMER2_ZONE_UNUSED42           42
#define HAMMER2_ZONE_UNUSED43           43
#define HAMMER2_ZONE_UNUSED44           44
#define HAMMER2_ZONE_UNUSED45           45
#define HAMMER2_ZONE_UNUSED46           46
#define HAMMER2_ZONE_UNUSED47           47
#define HAMMER2_ZONE_UNUSED48           48
#define HAMMER2_ZONE_UNUSED49           49
#define HAMMER2_ZONE_UNUSED50           50
#define HAMMER2_ZONE_UNUSED51           51
#define HAMMER2_ZONE_UNUSED52           52
#define HAMMER2_ZONE_UNUSED53           53
#define HAMMER2_ZONE_UNUSED54           54
#define HAMMER2_ZONE_UNUSED55           55
#define HAMMER2_ZONE_UNUSED56           56
#define HAMMER2_ZONE_UNUSED57           57
#define HAMMER2_ZONE_UNUSED58           58
#define HAMMER2_ZONE_UNUSED59           59
#define HAMMER2_ZONE_UNUSED60           60
#define HAMMER2_ZONE_UNUSED61           61
#define HAMMER2_ZONE_UNUSED62           62
#define HAMMER2_ZONE_UNUSED63           63
#define HAMMER2_ZONE_END                64      /* non-inclusive */

#define HAMMER2_NFREEMAPS               8       /* FREEMAP_00 - FREEMAP_07 */

                                               /* relative to FREEMAP_x */
#define HAMMER2_ZONEFM_LEVEL1           0       /* 1GB leafmap */
#define HAMMER2_ZONEFM_LEVEL2           1       /* 256GB indmap */
#define HAMMER2_ZONEFM_LEVEL3           2       /* 64TB indmap */
#define HAMMER2_ZONEFM_LEVEL4           3       /* 16PB indmap */
#define HAMMER2_ZONEFM_LEVEL5           4       /* 4EB indmap */
/* LEVEL6 is a set of 4 blockrefs in the volume header 16EB */

/*
* Freemap radix.  Assumes a set-count of 4, 128-byte blockrefs,
* 32KB indirect block for freemap (LEVELN_PSIZE below).
*
* Leaf entry represents 4MB of storage broken down into a 512-bit
* bitmap, 2-bits per entry.  So course bitmap item represents 16KB.
*/
#if HAMMER2_SET_COUNT != 4
#error "hammer2_disk.h - freemap assumes SET_COUNT is 4"
#endif
#define HAMMER2_FREEMAP_LEVEL6_RADIX    64      /* 16EB (end) */
#define HAMMER2_FREEMAP_LEVEL5_RADIX    62      /* 4EB */
#define HAMMER2_FREEMAP_LEVEL4_RADIX    54      /* 16PB */
#define HAMMER2_FREEMAP_LEVEL3_RADIX    46      /* 64TB */
#define HAMMER2_FREEMAP_LEVEL2_RADIX    38      /* 256GB */
#define HAMMER2_FREEMAP_LEVEL1_RADIX    30      /* 1GB */
#define HAMMER2_FREEMAP_LEVEL0_RADIX    22      /* 4MB (x 256 in l-1 leaf) */

#define HAMMER2_FREEMAP_LEVELN_PSIZE    32768   /* physical bytes */

#define HAMMER2_FREEMAP_LEVEL5_SIZE     ((hammer2_off_t)1 <<            \
                                        HAMMER2_FREEMAP_LEVEL5_RADIX)
#define HAMMER2_FREEMAP_LEVEL4_SIZE     ((hammer2_off_t)1 <<            \
                                        HAMMER2_FREEMAP_LEVEL4_RADIX)
#define HAMMER2_FREEMAP_LEVEL3_SIZE     ((hammer2_off_t)1 <<            \
                                        HAMMER2_FREEMAP_LEVEL3_RADIX)
#define HAMMER2_FREEMAP_LEVEL2_SIZE     ((hammer2_off_t)1 <<            \
                                        HAMMER2_FREEMAP_LEVEL2_RADIX)
#define HAMMER2_FREEMAP_LEVEL1_SIZE     ((hammer2_off_t)1 <<            \
                                        HAMMER2_FREEMAP_LEVEL1_RADIX)
#define HAMMER2_FREEMAP_LEVEL0_SIZE     ((hammer2_off_t)1 <<            \
                                        HAMMER2_FREEMAP_LEVEL0_RADIX)

#define HAMMER2_FREEMAP_LEVEL5_MASK     (HAMMER2_FREEMAP_LEVEL5_SIZE - 1)
#define HAMMER2_FREEMAP_LEVEL4_MASK     (HAMMER2_FREEMAP_LEVEL4_SIZE - 1)
#define HAMMER2_FREEMAP_LEVEL3_MASK     (HAMMER2_FREEMAP_LEVEL3_SIZE - 1)
#define HAMMER2_FREEMAP_LEVEL2_MASK     (HAMMER2_FREEMAP_LEVEL2_SIZE - 1)
#define HAMMER2_FREEMAP_LEVEL1_MASK     (HAMMER2_FREEMAP_LEVEL1_SIZE - 1)
#define HAMMER2_FREEMAP_LEVEL0_MASK     (HAMMER2_FREEMAP_LEVEL0_SIZE - 1)

#define HAMMER2_FREEMAP_COUNT           (int)(HAMMER2_FREEMAP_LEVELN_PSIZE / \
                                        sizeof(hammer2_bmap_data_t))

/*
* XXX I made a mistake and made the reserved area begin at each LEVEL1 zone,
*     which is on a 1GB demark.  This will eat a little more space but for
*     now we retain compatibility and make FMZONEBASE every 1GB
*/
#define H2FMZONEBASE(key)       ((key) & ~HAMMER2_FREEMAP_LEVEL1_MASK)
#define H2FMBASE(key, radix)    rounddown2(key, (hammer2_off_t)1 << (radix))

/*
* 16KB bitmap granularity (x2 bits per entry).
*/
#define HAMMER2_FREEMAP_BLOCK_RADIX     14
#define HAMMER2_FREEMAP_BLOCK_SIZE      (1 << HAMMER2_FREEMAP_BLOCK_RADIX)
#define HAMMER2_FREEMAP_BLOCK_MASK      (HAMMER2_FREEMAP_BLOCK_SIZE - 1)

/*
* bitmap[] structure.  2 bits per HAMMER2_FREEMAP_BLOCK_SIZE.
*
* 8 x 64-bit elements, 2 bits per block.
* 32 blocks (radix 5) per element.
* representing INDEX_SIZE bytes worth of storage per element.
*/

typedef uint64_t                        hammer2_bitmap_t;

#define HAMMER2_BMAP_ALLONES            ((hammer2_bitmap_t)-1)
#define HAMMER2_BMAP_ELEMENTS           8
#define HAMMER2_BMAP_BITS_PER_ELEMENT   64
#define HAMMER2_BMAP_INDEX_RADIX        5       /* 32 blocks per element */
#define HAMMER2_BMAP_BLOCKS_PER_ELEMENT (1 << HAMMER2_BMAP_INDEX_RADIX)

#define HAMMER2_BMAP_INDEX_SIZE         (HAMMER2_FREEMAP_BLOCK_SIZE * \
                                        HAMMER2_BMAP_BLOCKS_PER_ELEMENT)
#define HAMMER2_BMAP_INDEX_MASK         (HAMMER2_BMAP_INDEX_SIZE - 1)

#define HAMMER2_BMAP_SIZE               (HAMMER2_BMAP_INDEX_SIZE * \
                                        HAMMER2_BMAP_ELEMENTS)
#define HAMMER2_BMAP_MASK               (HAMMER2_BMAP_SIZE - 1)

/*
* Two linear areas can be reserved after the initial 4MB segment in the base
* zone (the one starting at offset 0).  These areas are NOT managed by the
* block allocator and do not fall under HAMMER2 crc checking rules based
* at the volume header (but can be self-CRCd internally, depending).
*/
#define HAMMER2_BOOT_MIN_BYTES          HAMMER2_VOLUME_ALIGN
#define HAMMER2_BOOT_NOM_BYTES          (64*1024*1024)
#define HAMMER2_BOOT_MAX_BYTES          (256*1024*1024)

#define HAMMER2_AUX_MIN_BYTES           HAMMER2_VOLUME_ALIGN
#define HAMMER2_AUX_NOM_BYTES           (256*1024*1024)
#define HAMMER2_AUX_MAX_BYTES           (1024*1024*1024)

/*
* Most HAMMER2 types are implemented as unsigned 64-bit integers.
* Transaction ids are monotonic.
*
* We utilize 32-bit iSCSI CRCs.
*/
typedef uint64_t hammer2_tid_t;
typedef uint64_t hammer2_off_t;
typedef uint64_t hammer2_key_t;
typedef uint32_t hammer2_crc32_t;

/*
* Miscellaneous ranges (all are unsigned).
*/
#define HAMMER2_TID_MIN         1ULL
#define HAMMER2_TID_MAX         0xFFFFFFFFFFFFFFFFULL
#define HAMMER2_KEY_MIN         0ULL
#define HAMMER2_KEY_MAX         0xFFFFFFFFFFFFFFFFULL
#define HAMMER2_OFFSET_MIN      0ULL
#define HAMMER2_OFFSET_MAX      0xFFFFFFFFFFFFFFFFULL

/*
* HAMMER2 data offset special cases and masking.
*
* All HAMMER2 data offsets have to be broken down into a 64K buffer base
* offset (HAMMER2_OFF_MASK_HI) and a 64K buffer index (HAMMER2_OFF_MASK_LO).
*
* Indexes into physical buffers are always 64-byte aligned.  The low 6 bits
* of the data offset field specifies how large the data chunk being pointed
* to as a power of 2.  The theoretical minimum radix is thus 6 (The space
* needed in the low bits of the data offset field).  However, the practical
* minimum allocation chunk size is 1KB (a radix of 10), so HAMMER2 sets
* HAMMER2_RADIX_MIN to 10.  The maximum radix is currently 16 (64KB), but
* we fully intend to support larger extents in the future.
*
* WARNING! A radix of 0 (such as when data_off is all 0's) is a special
*          case which means no data associated with the blockref, and
*          not the '1 byte' it would otherwise calculate to.
*/
#define HAMMER2_OFF_MASK        0xFFFFFFFFFFFFFFC0ULL
#define HAMMER2_OFF_MASK_LO     (HAMMER2_OFF_MASK & HAMMER2_PBUFMASK64)
#define HAMMER2_OFF_MASK_HI     (~HAMMER2_PBUFMASK64)
#define HAMMER2_OFF_MASK_RADIX  0x000000000000003FULL

/*
* HAMMER2 directory support and pre-defined keys
*/
#define HAMMER2_DIRHASH_VISIBLE 0x8000000000000000ULL
#define HAMMER2_DIRHASH_USERMSK 0x7FFFFFFFFFFFFFFFULL
#define HAMMER2_DIRHASH_LOMASK  0x0000000000007FFFULL
#define HAMMER2_DIRHASH_HIMASK  0xFFFFFFFFFFFF0000ULL
#define HAMMER2_DIRHASH_FORCED  0x0000000000008000ULL   /* bit forced on */

#define HAMMER2_SROOT_KEY       0x0000000000000000ULL   /* volume to sroot */
#define HAMMER2_BOOT_KEY        0xd9b36ce135528000ULL   /* sroot to BOOT PFS */

/************************************************************************
*                              DMSG SUPPORT                            *
************************************************************************
* LNK_VOLCONF
*
* All HAMMER2 directories directly under the super-root on your local
* media can be mounted separately, even if they share the same physical
* device.
*
* When you do a HAMMER2 mount you are effectively tying into a HAMMER2
* cluster via local media.  The local media does not have to participate
* in the cluster, other than to provide the hammer2_volconf[] array and
* root inode for the mount.
*
* This is important: The mount device path you specify serves to bootstrap
* your entry into the cluster, but your mount will make active connections
* to ALL copy elements in the hammer2_volconf[] array which match the
* PFSID of the directory in the super-root that you specified.  The local
* media path does not have to be mentioned in this array but becomes part
* of the cluster based on its type and access rights.  ALL ELEMENTS ARE
* TREATED ACCORDING TO TYPE NO MATTER WHICH ONE YOU MOUNT FROM.
*
* The actual cluster may be far larger than the elements you list in the
* hammer2_volconf[] array.  You list only the elements you wish to
* directly connect to and you are able to access the rest of the cluster
* indirectly through those connections.
*
* WARNING!  This structure must be exactly 128 bytes long for its config
*           array to fit in the volume header.
*/
struct hammer2_volconf {
       uint8_t copyid;         /* 00    copyid 0-255 (must match slot) */
       uint8_t inprog;         /* 01    operation in progress, or 0 */
       uint8_t chain_to;       /* 02    operation chaining to, or 0 */
       uint8_t chain_from;     /* 03    operation chaining from, or 0 */
       uint16_t flags;         /* 04-05 flags field */
       uint8_t error;          /* 06    last operational error */
       uint8_t priority;       /* 07    priority and round-robin flag */
       uint8_t remote_pfs_type;/* 08    probed direct remote PFS type */
       uint8_t reserved08[23]; /* 09-1F */
       uuid_t  pfs_clid;       /* 20-2F copy target must match this uuid */
       uint8_t label[16];      /* 30-3F import/export label */
       uint8_t path[64];       /* 40-7F target specification string or key */
} __packed;

typedef struct hammer2_volconf hammer2_volconf_t;

#define DMSG_VOLF_ENABLED       0x0001
#define DMSG_VOLF_INPROG        0x0002
#define DMSG_VOLF_CONN_RR       0x80    /* round-robin at same priority */
#define DMSG_VOLF_CONN_EF       0x40    /* media errors flagged */
#define DMSG_VOLF_CONN_PRI      0x0F    /* select priority 0-15 (15=best) */

#if 0
struct dmsg_lnk_hammer2_volconf {
       dmsg_hdr_t              head;
       hammer2_volconf_t       copy;   /* copy spec */
       int32_t                 index;
       int32_t                 unused01;
       uuid_t                  mediaid;
       int64_t                 reserved02[32];
} __packed;
#endif

typedef struct dmsg_lnk_hammer2_volconf dmsg_lnk_hammer2_volconf_t;

#define DMSG_LNK_HAMMER2_VOLCONF DMSG_LNK(DMSG_LNK_CMD_HAMMER2_VOLCONF, \
                                         dmsg_lnk_hammer2_volconf)

#define H2_LNK_VOLCONF(msg)     ((dmsg_lnk_hammer2_volconf_t *)(msg)->any.buf)

/*
* HAMMER2 directory entry header (embedded in blockref)  exactly 16 bytes
*/
struct hammer2_dirent_head {
       hammer2_tid_t           inum;           /* inode number */
       uint16_t                namlen;         /* name length */
       uint8_t                 type;           /* OBJTYPE_*    */
       uint8_t                 unused0B;
       uint8_t                 unused0C[4];
} __packed;

typedef struct hammer2_dirent_head hammer2_dirent_head_t;

/*
* The media block reference structure.  This forms the core of the HAMMER2
* media topology recursion.  This 128-byte data structure is embedded in the
* volume header, in inodes (which are also directory entries), and in
* indirect blocks.
*
* A blockref references a single media item, which typically can be a
* directory entry (aka inode), indirect block, or data block.
*
* The primary feature a blockref represents is the ability to validate
* the entire tree underneath it via its check code.  Any modification to
* anything propagates up the blockref tree all the way to the root, replacing
* the related blocks and compounding the generated check code.
*
* The check code can be a simple 32-bit iscsi code, a 64-bit crc, or as
* complex as a 512 bit cryptographic hash.  I originally used a 64-byte
* blockref but later expanded it to 128 bytes to be able to support the
* larger check code as well as to embed statistics for quota operation.
*
* Simple check codes are not sufficient for unverified dedup.  Even with
* a maximally-sized check code unverified dedup should only be used in
* in subdirectory trees where you do not need 100% data integrity.
*
* Unverified dedup is deduping based on meta-data only without verifying
* that the data blocks are actually identical.  Verified dedup guarantees
* integrity but is a far more I/O-expensive operation.
*
* --
*
* mirror_tid - per cluster node modified (propagated upward by flush)
* modify_tid - clc record modified (not propagated).
* update_tid - clc record updated (propagated upward on verification)
*
* CLC - Stands for 'Cluster Level Change', identifiers which are identical
*       within the topology across all cluster nodes (when fully
*       synchronized).
*
* NOTE: The range of keys represented by the blockref is (key) to
*       ((key) + (1LL << keybits) - 1).  HAMMER2 usually populates
*       blocks bottom-up, inserting a new root when radix expansion
*       is required.
*
* leaf_count  - Helps manage leaf collapse calculations when indirect
*               blocks become mostly empty.  This value caps out at
*               HAMMER2_BLOCKREF_LEAF_MAX (65535).
*
*               Used by the chain code to determine when to pull leafs up
*               from nearly empty indirect blocks.  For the purposes of this
*               calculation, BREF_TYPE_INODE is considered a leaf, along
*               with DIRENT and DATA.
*
*                                  RESERVED FIELDS
*
* A number of blockref fields are reserved and should generally be set to
* 0 for future compatibility.
*
*                              FUTURE BLOCKREF EXPANSION
*
* CONTENT ADDRESSABLE INDEXING (future) - Using a 256 or 512-bit check code.
*/
struct hammer2_blockref {               /* MUST BE EXACTLY 64 BYTES */
       uint8_t         type;           /* type of underlying item */
       uint8_t         methods;        /* check method & compression method */
       uint8_t         copyid;         /* specify which copy this is */
       uint8_t         keybits;        /* #of keybits masked off 0=leaf */
       uint8_t         vradix;         /* virtual data/meta-data size */
       uint8_t         flags;          /* blockref flags */
       uint16_t        leaf_count;     /* leaf aggregation count */
       hammer2_key_t   key;            /* key specification */
       hammer2_tid_t   mirror_tid;     /* media flush topology & freemap */
       hammer2_tid_t   modify_tid;     /* clc modify (not propagated) */
       hammer2_off_t   data_off;       /* low 6 bits is phys size (radix)*/
       hammer2_tid_t   update_tid;     /* clc modify (propagated upward) */
       union {
               char    buf[16];

               /*
                * Directory entry header (BREF_TYPE_DIRENT)
                *
                * NOTE: check.buf contains filename if <= 64 bytes.  Longer
                *       filenames are stored in a data reference of size
                *       HAMMER2_ALLOC_MIN (at least 256, typically 1024).
                *
                * NOTE: inode structure may contain a copy of a recently
                *       associated filename, for recovery purposes.
                *
                * NOTE: Superroot entries are INODEs, not DIRENTs.  Code
                *       allows both cases.
                */
               hammer2_dirent_head_t dirent;

               /*
                * Statistics aggregation (BREF_TYPE_INODE, BREF_TYPE_INDIRECT)
                */
               struct {
                       hammer2_key_t   data_count;
                       hammer2_key_t   inode_count;
               } stats;
       } embed;
       union {                         /* check info */
               char    buf[64];
               struct {
                       uint32_t value;
                       uint32_t reserved[15];
               } iscsi32;
               struct {
                       uint64_t value;
                       uint64_t reserved[7];
               } xxhash64;
               struct {
                       char data[24];
                       char reserved[40];
               } sha192;
               struct {
                       char data[32];
                       char reserved[32];
               } sha256;
               struct {
                       char data[64];
               } sha512;

               /*
                * Freemap hints are embedded in addition to the icrc32.
                *
                * bigmask - Radixes available for allocation (0-31).
                *           Heuristical (may be permissive but not
                *           restrictive).  Typically only radix values
                *           10-16 are used (i.e. (1<<10) through (1<<16)).
                *
                * avail   - Total available space remaining, in bytes
                */
               struct {
                       uint32_t icrc32;
                       uint32_t bigmask;       /* available radixes */
                       uint64_t avail;         /* total available bytes */
                       char reserved[48];
               } freemap;
       } check;
} __packed;

typedef struct hammer2_blockref hammer2_blockref_t;

#define HAMMER2_BLOCKREF_BYTES          128     /* blockref struct in bytes */
#define HAMMER2_BLOCKREF_RADIX          7

#define HAMMER2_BLOCKREF_LEAF_MAX       65535

/*
* On-media and off-media blockref types.
*
* types >= 128 are pseudo values that should never be present on-media.
*/
#define HAMMER2_BREF_TYPE_EMPTY         0
#define HAMMER2_BREF_TYPE_INODE         1
#define HAMMER2_BREF_TYPE_INDIRECT      2
#define HAMMER2_BREF_TYPE_DATA          3
#define HAMMER2_BREF_TYPE_DIRENT        4
#define HAMMER2_BREF_TYPE_FREEMAP_NODE  5
#define HAMMER2_BREF_TYPE_FREEMAP_LEAF  6
#define HAMMER2_BREF_TYPE_INVALID       7
#define HAMMER2_BREF_TYPE_FREEMAP       254     /* pseudo-type */
#define HAMMER2_BREF_TYPE_VOLUME        255     /* pseudo-type */

#define HAMMER2_BREF_FLAG_PFSROOT       0x01    /* see also related opflag */
#define HAMMER2_BREF_FLAG_ZERO          0x02    /* NO LONGER USED */
#define HAMMER2_BREF_FLAG_EMERG_MIP     0x04    /* emerg modified-in-place */

/*
* Encode/decode check mode and compression mode for
* bref.methods.  The compression level is not encoded in
* bref.methods.
*/
#define HAMMER2_ENC_CHECK(n)            (((n) & 15) << 4)
#define HAMMER2_DEC_CHECK(n)            (((n) >> 4) & 15)
#define HAMMER2_ENC_COMP(n)             ((n) & 15)
#define HAMMER2_DEC_COMP(n)             ((n) & 15)

#define HAMMER2_CHECK_NONE              0
#define HAMMER2_CHECK_DISABLED          1
#define HAMMER2_CHECK_ISCSI32           2
#define HAMMER2_CHECK_XXHASH64          3
#define HAMMER2_CHECK_SHA192            4
#define HAMMER2_CHECK_FREEMAP           5

#define HAMMER2_CHECK_DEFAULT           HAMMER2_CHECK_XXHASH64

/* user-specifiable check modes only */
#define HAMMER2_CHECK_STRINGS           { "none", "disabled", "crc32", \
                                         "xxhash64", "sha192" }
#define HAMMER2_CHECK_STRINGS_COUNT     5

/*
* Encode/decode check or compression algorithm request in
* ipdata->meta.check_algo and ipdata->meta.comp_algo.
*/
#define HAMMER2_ENC_ALGO(n)             (n)
#define HAMMER2_DEC_ALGO(n)             ((n) & 15)
#define HAMMER2_ENC_LEVEL(n)            ((n) << 4)
#define HAMMER2_DEC_LEVEL(n)            (((n) >> 4) & 15)

#define HAMMER2_COMP_NONE               0
#define HAMMER2_COMP_AUTOZERO           1
#define HAMMER2_COMP_LZ4                2
#define HAMMER2_COMP_ZLIB               3

#define HAMMER2_COMP_NEWFS_DEFAULT      HAMMER2_COMP_LZ4
#define HAMMER2_COMP_STRINGS            { "none", "autozero", "lz4", "zlib" }
#define HAMMER2_COMP_STRINGS_COUNT      4

/*
* Passed to hammer2_chain_create(), causes methods to be inherited from
* parent.
*/
#define HAMMER2_METH_DEFAULT            -1

/*
* HAMMER2 block references are collected into sets of 4 blockrefs.  These
* sets are fully associative, meaning the elements making up a set may
* contain duplicate entries, holes, but valid elements are always sorted.
*
* When redundancy is desired a set may contain several duplicate
* entries pointing to different copies of the same data.  Up to 4 copies
* are supported. Not implemented.
*
* When a set fills up another level of indirection is inserted, moving
* some or all of the set's contents into indirect blocks placed under the
* set.  This is a top-down approach in that indirect blocks are not created
* until the set actually becomes full (that is, the entries in the set can
* shortcut the indirect blocks when the set is not full).  Depending on how
* things are filled multiple indirect blocks will eventually be created.
*/
struct hammer2_blockset {
       hammer2_blockref_t      blockref[HAMMER2_SET_COUNT];
};

typedef struct hammer2_blockset hammer2_blockset_t;

/*
* Catch programmer snafus
*/
#if (1 << HAMMER2_SET_RADIX) != HAMMER2_SET_COUNT
#error "hammer2 direct radix is incorrect"
#endif
#if (1 << HAMMER2_PBUFRADIX) != HAMMER2_PBUFSIZE
#error "HAMMER2_PBUFRADIX and HAMMER2_PBUFSIZE are inconsistent"
#endif
#if (1 << HAMMER2_RADIX_MIN) != HAMMER2_ALLOC_MIN
#error "HAMMER2_RADIX_MIN and HAMMER2_ALLOC_MIN are inconsistent"
#endif

/*
* hammer2_bmap_data - A freemap entry in the LEVEL1 block.
*
* Each 128-byte entry contains the bitmap and meta-data required to manage
* a LEVEL0 (4MB) block of storage.  The storage is managed in 256 x 16KB
* chunks.
*
* A smaller allocation granularity is supported via a linear iterator and/or
* must otherwise be tracked in ram.
*
* (data structure must be 128 bytes exactly)
*
* linear  - A BYTE linear allocation offset used for sub-16KB allocations
*           only.  May contain values between 0 and 4MB.  Must be ignored
*           if 16KB-aligned (i.e. force bitmap scan), otherwise may be
*           used to sub-allocate within the 16KB block (which is already
*           marked as allocated in the bitmap).
*
*           Sub-allocations need only be 1KB-aligned and do not have to be
*           size-aligned, and 16KB or larger allocations do not update this
*           field, resulting in pretty good packing.
*
*           Please note that file data granularity may be limited by
*           other issues such as buffer cache direct-mapping and the
*           desire to support sector sizes up to 16KB (so H2 only issues
*           I/O's in multiples of 16KB anyway).
*
* class   - Clustering class.  Cleared to 0 only if the entire leaf becomes
*           free.  Used to cluster device buffers so all elements must have
*           the same device block size, but may mix logical sizes.
*
*           Typically integrated with the blockref type in the upper 8 bits
*           to localize inodes and indrect blocks, improving bulk free scans
*           and directory scans.
*
* bitmap  - Two bits per 16KB allocation block arranged in arrays of
*           64-bit elements, 256x2 bits representing ~4MB worth of media
*           storage.  Bit patterns are as follows:
*
*           00 Unallocated
*           01 (reserved)
*           10 Possibly free
*           11 Allocated
*
* ==========
* level6 freemap
* blockref[0]       : 4EB
* blockref[1]       : 4EB
* blockref[2]       : 4EB
* blockref[3]       : 4EB
* -----------------------------------------------------------------------
* 4 x 128B = 512B   : 4 x 4EB = 16EB
*
* level2-5 FREEMAP_NODE
* blockref[0]       : 1GB,256GB,64TB,16PB
* blockref[1]       : 1GB,256GB,64TB,16PB
* ...
* blockref[255]     : 1GB,256GB,64TB,16PB
* -----------------------------------------------------------------------
* 256 x 128B = 32KB : 256 x 1GB,256GB,64TB,16PB = 256GB,64TB,16PB,4EB
*
* level1 FREEMAP_LEAF
* bmap_data[0]      : 8 x 8B = 512bits = 256 x 2bits -> 256 x 16KB = 4MB
* bmap_data[1]      : 8 x 8B = 512bits = 256 x 2bits -> 256 x 16KB = 4MB
* ...
* bmap_data[255]    : 8 x 8B = 512bits = 256 x 2bits -> 256 x 16KB = 4MB
* -----------------------------------------------------------------------
* 256 x 128B = 32KB : 256 x 4MB = 1GB
* ==========
*/
struct hammer2_bmap_data {
       int32_t linear;         /* 00 linear sub-granular allocation offset */
       uint16_t class;         /* 04-05 clustering class ((type<<8)|radix) */
       uint8_t reserved06;     /* 06 */
       uint8_t reserved07;     /* 07 */
       uint32_t reserved08;    /* 08 */
       uint32_t reserved0C;    /* 0C */
       uint32_t reserved10;    /* 10 */
       uint32_t reserved14;    /* 14 */
       uint32_t reserved18;    /* 18 */
       uint32_t avail;         /* 1C */
       uint32_t reserved20[8]; /* 20-3F 256 bits manages 128K/1KB/2-bits */
                               /* 40-7F 512 bits manages 4MB of storage */
       hammer2_bitmap_t bitmapq[HAMMER2_BMAP_ELEMENTS];
} __packed;

typedef struct hammer2_bmap_data hammer2_bmap_data_t;

/*
* The inode number is stored in the inode rather than being
* based on the location of the inode (since the location moves every time
* the inode or anything underneath the inode is modified).
*
* The inode is 1024 bytes, made up of 256 bytes of meta-data, 256 bytes
* for the filename, and 512 bytes worth of direct file data OR an embedded
* blockset.  The in-memory hammer2_inode structure contains only the mostly-
* node-independent meta-data portion (some flags are node-specific and will
* not be synchronized).  The rest of the inode is node-specific and chain I/O
* is required to obtain it.
*
* Directories represent one inode per blockref.  Inodes are not laid out
* as a file but instead are represented by the related blockrefs.  The
* blockrefs, in turn, are indexed by the 64-bit directory hash key.  Remember
* that blocksets are fully associative, so a certain degree efficiency is
* achieved just from that.
*
* Up to 512 bytes of direct data can be embedded in an inode, and since
* inodes are essentially directory entries this also means that small data
* files end up simply being laid out linearly in the directory, resulting
* in fewer seeks and highly optimal access.
*
* The compression mode can be changed at any time in the inode and is
* recorded on a blockref-by-blockref basis.
*/
#define HAMMER2_INODE_BYTES             1024    /* (asserted by code) */
#define HAMMER2_INODE_MAXNAME           256     /* maximum name in bytes */
#define HAMMER2_INODE_VERSION_ONE       1

#define HAMMER2_INODE_START             1024    /* dynamically allocated */

struct hammer2_inode_meta {
       uint16_t        version;        /* 0000 inode data version */
       uint8_t         reserved02;     /* 0002 */
       uint8_t         pfs_subtype;    /* 0003 pfs sub-type */

       /*
        * core inode attributes, inode type, misc flags
        */
       uint32_t        uflags;         /* 0004 chflags */
       uint32_t        rmajor;         /* 0008 available for device nodes */
       uint32_t        rminor;         /* 000C available for device nodes */
       uint64_t        ctime;          /* 0010 inode change time */
       uint64_t        mtime;          /* 0018 modified time */
       uint64_t        atime;          /* 0020 access time (unsupported) */
       uint64_t        btime;          /* 0028 birth time */
       uuid_t          uid;            /* 0030 uid / degenerate unix uid */
       uuid_t          gid;            /* 0040 gid / degenerate unix gid */

       uint8_t         type;           /* 0050 object type */
       uint8_t         op_flags;       /* 0051 operational flags */
       uint16_t        cap_flags;      /* 0052 capability flags */
       uint32_t        mode;           /* 0054 unix modes (typ low 16 bits) */

       /*
        * inode size, identification, localized recursive configuration
        * for compression and backup copies.
        *
        * NOTE: Nominal parent inode number (iparent) is only applicable
        *       for directories but can also help for files during
        *       catastrophic recovery.
        */
       hammer2_tid_t   inum;           /* 0058 inode number */
       hammer2_off_t   size;           /* 0060 size of file */
       uint64_t        nlinks;         /* 0068 hard links (typ only dirs) */
       hammer2_tid_t   iparent;        /* 0070 nominal parent inum */
       hammer2_key_t   name_key;       /* 0078 full filename key */
       uint16_t        name_len;       /* 0080 filename length */
       uint8_t         ncopies;        /* 0082 ncopies to local media */
       uint8_t         comp_algo;      /* 0083 compression request & algo */

       /*
        * These fields are currently only applicable to PFSROOTs.
        *
        * NOTE: We can't use {volume_data->fsid, pfs_clid} to uniquely
        *       identify an instance of a PFS in the cluster because
        *       a mount may contain more than one copy of the PFS as
        *       a separate node.  {pfs_clid, pfs_fsid} must be used for
        *       registration in the cluster.
        */
       uint8_t         target_type;    /* 0084 hardlink target type */
       uint8_t         check_algo;     /* 0085 check code request & algo */
       uint8_t         pfs_nmasters;   /* 0086 (if PFSROOT) if multi-master */
       uint8_t         pfs_type;       /* 0087 (if PFSROOT) node type */
       hammer2_tid_t   pfs_inum;       /* 0088 (if PFSROOT) inum allocator */
       uuid_t          pfs_clid;       /* 0090 (if PFSROOT) cluster uuid */
       uuid_t          pfs_fsid;       /* 00A0 (if PFSROOT) unique uuid */

       /*
        * Quotas and aggregate sub-tree inode and data counters.  Note that
        * quotas are not replicated downward, they are explicitly set by
        * the sysop and in-memory structures keep track of inheritance.
        */
       hammer2_key_t   data_quota;     /* 00B0 subtree quota in bytes */
       hammer2_key_t   unusedB8;       /* 00B8 subtree byte count */
       hammer2_key_t   inode_quota;    /* 00C0 subtree quota inode count */
       hammer2_key_t   unusedC8;       /* 00C8 subtree inode count */

       /*
        * The last snapshot tid is tested against modify_tid to determine
        * when a copy must be made of a data block whos check mode has been
        * disabled (a disabled check mode allows data blocks to be updated
        * in place instead of copy-on-write).
        */
       hammer2_tid_t   pfs_lsnap_tid;  /* 00D0 last snapshot tid */
       hammer2_tid_t   reservedD8;     /* 00D8 (avail) */

       /*
        * Tracks (possibly degenerate) free areas covering all sub-tree
        * allocations under inode, not counting the inode itself.
        * 0/0 indicates empty entry.  fully set-associative.
        *
        * (not yet implemented)
        */
       uint64_t        decrypt_check;  /* 00E0 decryption validator */
       hammer2_off_t   reservedE0[3];  /* 00E8/F0/F8 */
} __packed;

typedef struct hammer2_inode_meta hammer2_inode_meta_t;

struct hammer2_inode_data {
       hammer2_inode_meta_t    meta;   /* 0000-00FF */
       unsigned char   filename[HAMMER2_INODE_MAXNAME];
                                       /* 0100-01FF (256 char, unterminated) */
       union {                         /* 0200-03FF (64x8 = 512 bytes) */
               hammer2_blockset_t blockset;
               char data[HAMMER2_EMBEDDED_BYTES];
       } u;
} __packed;

typedef struct hammer2_inode_data hammer2_inode_data_t;

#define HAMMER2_OPFLAG_DIRECTDATA       0x01
#define HAMMER2_OPFLAG_PFSROOT          0x02    /* (see also bref flag) */
#define HAMMER2_OPFLAG_COPYIDS          0x04    /* copyids override parent */

#define HAMMER2_OBJTYPE_UNKNOWN         0
#define HAMMER2_OBJTYPE_DIRECTORY       1
#define HAMMER2_OBJTYPE_REGFILE         2
#define HAMMER2_OBJTYPE_FIFO            4
#define HAMMER2_OBJTYPE_CDEV            5
#define HAMMER2_OBJTYPE_BDEV            6
#define HAMMER2_OBJTYPE_SOFTLINK        7
#define HAMMER2_OBJTYPE_UNUSED08        8
#define HAMMER2_OBJTYPE_SOCKET          9
#define HAMMER2_OBJTYPE_WHITEOUT        10

#define HAMMER2_COPYID_NONE             0
#define HAMMER2_COPYID_LOCAL            ((uint8_t)-1)

#define HAMMER2_COPYID_COUNT            256

/*
* PFS types identify the role of a PFS within a cluster.  The PFS types
* is stored on media and in LNK_SPAN messages and used in other places.
*
* The low 4 bits specify the current active type while the high 4 bits
* specify the transition target if the PFS is being upgraded or downgraded,
* If the upper 4 bits are not zero it may effect how a PFS is used during
* the transition.
*
* Generally speaking, downgrading a MASTER to a SLAVE cannot complete until
* at least all MASTERs have updated their pfs_nmasters field.  And upgrading
* a SLAVE to a MASTER cannot complete until the new prospective master has
* been fully synchronized (though theoretically full synchronization is
* not required if a (new) quorum of other masters are fully synchronized).
*
* It generally does not matter which PFS element you actually mount, you
* are mounting 'the cluster'.  So, for example, a network mount will mount
* a DUMMY PFS type on a memory filesystem.  However, there are two exceptions.
* In order to gain the benefits of a SOFT_MASTER or SOFT_SLAVE, those PFSs
* must be directly mounted.
*/
#define HAMMER2_PFSTYPE_NONE            0x00
#define HAMMER2_PFSTYPE_CACHE           0x01
#define HAMMER2_PFSTYPE_UNUSED02        0x02
#define HAMMER2_PFSTYPE_SLAVE           0x03
#define HAMMER2_PFSTYPE_SOFT_SLAVE      0x04
#define HAMMER2_PFSTYPE_SOFT_MASTER     0x05
#define HAMMER2_PFSTYPE_MASTER          0x06
#define HAMMER2_PFSTYPE_UNUSED07        0x07
#define HAMMER2_PFSTYPE_SUPROOT         0x08
#define HAMMER2_PFSTYPE_DUMMY           0x09
#define HAMMER2_PFSTYPE_MAX             16

#define HAMMER2_PFSTRAN_NONE            0x00    /* no transition in progress */
#define HAMMER2_PFSTRAN_CACHE           0x10
#define HAMMER2_PFSTRAN_UNMUSED20       0x20
#define HAMMER2_PFSTRAN_SLAVE           0x30
#define HAMMER2_PFSTRAN_SOFT_SLAVE      0x40
#define HAMMER2_PFSTRAN_SOFT_MASTER     0x50
#define HAMMER2_PFSTRAN_MASTER          0x60
#define HAMMER2_PFSTRAN_UNUSED70        0x70
#define HAMMER2_PFSTRAN_SUPROOT         0x80
#define HAMMER2_PFSTRAN_DUMMY           0x90

#define HAMMER2_PFS_DEC(n)              ((n) & 0x0F)
#define HAMMER2_PFS_DEC_TRANSITION(n)   (((n) >> 4) & 0x0F)
#define HAMMER2_PFS_ENC_TRANSITION(n)   (((n) & 0x0F) << 4)

#define HAMMER2_PFSSUBTYPE_NONE         0
#define HAMMER2_PFSSUBTYPE_SNAPSHOT     1       /* manual/managed snapshot */
#define HAMMER2_PFSSUBTYPE_AUTOSNAP     2       /* automatic snapshot */

/*
* PFS mode of operation is a bitmask.  This is typically not stored
* on-media, but defined here because the field may be used in dmsgs.
*/
#define HAMMER2_PFSMODE_QUORUM          0x01
#define HAMMER2_PFSMODE_RW              0x02

/*
* The volume header eats a 64K block at the beginning of each 2GB zone
* up to four copies.
*
* All information is stored in host byte order.  The volume header's magic
* number may be checked to determine the byte order.  If you wish to mount
* between machines w/ different endian modes you'll need filesystem code
* which acts on the media data consistently (either all one way or all the
* other).  Our code currently does not do that.
*
* A read-write mount may have to recover missing allocations by doing an
* incremental mirror scan looking for modifications made after alloc_tid.
* If alloc_tid == last_tid then no recovery operation is needed.  Recovery
* operations are usually very, very fast.
*
* Read-only mounts do not need to do any recovery, access to the filesystem
* topology is always consistent after a crash (is always consistent, period).
* However, there may be shortcutted blockref updates present from deep in
* the tree which are stored in the volumeh eader and must be tracked on
* the fly.
*
* NOTE: The copyinfo[] array contains the configuration for both the
*       cluster connections and any local media copies.  The volume
*       header will be replicated for each local media copy.
*
*       The mount command may specify multiple medias or just one and
*       allow HAMMER2 to pick up the others when it checks the copyinfo[]
*       array on mount.
*
* NOTE: sroot_blockset points to the super-root directory, not the root
*       directory.  The root directory will be a subdirectory under the
*       super-root.
*
*       The super-root directory contains all root directories and all
*       snapshots (readonly or writable).  It is possible to do a
*       null-mount of the super-root using special path constructions
*       relative to your mounted root.
*/
#define HAMMER2_VOLUME_ID_HBO   0x48414d3205172011LLU
#define HAMMER2_VOLUME_ID_ABO   0x11201705324d4148LLU

/*
* If volume version is HAMMER2_VOL_VERSION_MULTI_VOLUMES or above, max
* HAMMER2_MAX_VOLUMES volumes are supported. There must be 1 (and only 1)
* volume with volume id HAMMER2_ROOT_VOLUME.
* Otherwise filesystem only supports 1 volume, and that volume must have
* volume id HAMMER2_ROOT_VOLUME(0) which was a reserved field then.
*/
#define HAMMER2_MAX_VOLUMES     64
#define HAMMER2_ROOT_VOLUME     0

struct hammer2_volume_data {
       /*
        * sector #0 - 512 bytes
        */
       uint64_t        magic;                  /* 0000 Signature */
       hammer2_off_t   boot_beg;               /* 0008 Boot area (future) */
       hammer2_off_t   boot_end;               /* 0010 (size = end - beg) */
       hammer2_off_t   aux_beg;                /* 0018 Aux area (future) */
       hammer2_off_t   aux_end;                /* 0020 (size = end - beg) */
       hammer2_off_t   volu_size;              /* 0028 Volume size, bytes */

       uint32_t        version;                /* 0030 */
       uint32_t        flags;                  /* 0034 */
       uint8_t         copyid;                 /* 0038 copyid of phys vol */
       uint8_t         freemap_version;        /* 0039 freemap algorithm */
       uint8_t         peer_type;              /* 003A HAMMER2_PEER_xxx */
       uint8_t         volu_id;                /* 003B */
       uint8_t         nvolumes;               /* 003C */
       uint8_t         reserved003D;           /* 003D */
       uint16_t        reserved003E;           /* 003E */

       uuid_t          fsid;                   /* 0040 */
       uuid_t          fstype;                 /* 0050 */

       /*
        * allocator_size is precalculated at newfs time and does not include
        * reserved blocks, boot, or aux areas.
        *
        * Initial non-reserved-area allocations do not use the freemap
        * but instead adjust alloc_iterator.  Dynamic allocations take
        * over starting at (allocator_beg).  This makes newfs_hammer2's
        * job a lot easier and can also serve as a testing jig.
        */
       hammer2_off_t   allocator_size;         /* 0060 Total data space */
       hammer2_off_t   allocator_free;         /* 0068 Free space */
       hammer2_off_t   allocator_beg;          /* 0070 Initial allocations */

       /*
        * mirror_tid reflects the highest committed change for this
        * block device regardless of whether it is to the super-root
        * or to a PFS or whatever.
        *
        * freemap_tid reflects the highest committed freemap change for
        * this block device.
        */
       hammer2_tid_t   mirror_tid;             /* 0078 committed tid (vol) */
       hammer2_tid_t   reserved0080;           /* 0080 */
       hammer2_tid_t   reserved0088;           /* 0088 */
       hammer2_tid_t   freemap_tid;            /* 0090 committed tid (fmap) */
       hammer2_tid_t   bulkfree_tid;           /* 0098 bulkfree incremental */
       hammer2_tid_t   reserved00A0[4];        /* 00A0-00BF */

       hammer2_off_t   total_size;             /* 00C0 Total volume size, bytes */

       /*
        * Copyids are allocated dynamically from the copyexists bitmap.
        * An id from the active copies set (up to 8, see copyinfo later on)
        * may still exist after the copy set has been removed from the
        * volume header and its bit will remain active in the bitmap and
        * cannot be reused until it is 100% removed from the hierarchy.
        */
       uint32_t        copyexists[8];          /* 00C8-00E7 copy exists bmap */
       char            reserved0140[248];      /* 00E8-01DF */

       /*
        * 32 bit CRC array at the end of the first 512 byte sector.
        *
        * icrc_sects[7] - First 512-4 bytes of volume header (including all
        *                 the other icrc's except this one).
        *
        * icrc_sects[6] - Sector 1 (512 bytes) of volume header, which is
        *                 the blockset for the root.
        *
        * icrc_sects[5] - Sector 2
        * icrc_sects[4] - Sector 3
        * icrc_sects[3] - Sector 4 (the freemap blockset)
        */
       hammer2_crc32_t icrc_sects[8];          /* 01E0-01FF */

       /*
        * sector #1 - 512 bytes
        *
        * The entire sector is used by a blockset, but currently only first
        * blockref is used.
        */
       hammer2_blockset_t sroot_blockset;      /* 0200-03FF Superroot dir */

       /*
        * sector #2-6
        */
       char    sector2[512];                   /* 0400-05FF reserved */
       char    sector3[512];                   /* 0600-07FF reserved */
       hammer2_blockset_t freemap_blockset;    /* 0800-09FF freemap  */
       char    sector5[512];                   /* 0A00-0BFF reserved */
       char    sector6[512];                   /* 0C00-0DFF reserved */

       /*
        * sector #7 - 512 bytes
        * Maximum 64 volume offsets within logical offset.
        */
       hammer2_off_t volu_loff[HAMMER2_MAX_VOLUMES];

       /*
        * sector #8-71 - 32768 bytes
        *
        * Contains the configuration for up to 256 copyinfo targets.  These
        * specify local and remote copies operating as masters or slaves.
        * copyid's 0 and 255 are reserved (0 indicates an empty slot and 255
        * indicates the local media).
        */
                                               /* 1000-8FFF copyinfo config */
       hammer2_volconf_t copyinfo[HAMMER2_COPYID_COUNT];

       /*
        * Remaining sections are reserved for future use.
        */
       char            reserved0400[0x6FFC];   /* 9000-FFFB reserved */

       /*
        * icrc on entire volume header
        */
       hammer2_crc32_t icrc_volheader;         /* FFFC-FFFF full volume icrc*/
} __packed;

typedef struct hammer2_volume_data hammer2_volume_data_t;

/*
* Various parts of the volume header have their own iCRCs.
*
* The first 512 bytes has its own iCRC stored at the end of the 512 bytes
* and not included the icrc calculation.
*
* The second 512 bytes also has its own iCRC but it is stored in the first
* 512 bytes so it covers the entire second 512 bytes.
*
* The whole volume block (64KB) has an iCRC covering all but the last 4 bytes,
* which is where the iCRC for the whole volume is stored.  This is currently
* a catch-all for anything not individually iCRCd.
*/
#define HAMMER2_VOL_ICRC_SECT0          7
#define HAMMER2_VOL_ICRC_SECT1          6

#define HAMMER2_VOLUME_BYTES            65536

#define HAMMER2_VOLUME_ICRC0_OFF        0
#define HAMMER2_VOLUME_ICRC1_OFF        512
#define HAMMER2_VOLUME_ICRCVH_OFF       0

#define HAMMER2_VOLUME_ICRC0_SIZE       (512 - 4)
#define HAMMER2_VOLUME_ICRC1_SIZE       (512)
#define HAMMER2_VOLUME_ICRCVH_SIZE      (65536 - 4)

#define HAMMER2_VOL_VERSION_MULTI_VOLUMES       2

#define HAMMER2_VOL_VERSION_MIN         1
#define HAMMER2_VOL_VERSION_DEFAULT     HAMMER2_VOL_VERSION_MULTI_VOLUMES
#define HAMMER2_VOL_VERSION_WIP         (HAMMER2_VOL_VERSION_MULTI_VOLUMES + 1)

#define HAMMER2_NUM_VOLHDRS             4

union hammer2_media_data {
       hammer2_volume_data_t   voldata;
       hammer2_inode_data_t    ipdata;
       hammer2_blockset_t      blkset;
       hammer2_blockref_t      npdata[HAMMER2_IND_COUNT_MAX];
       hammer2_bmap_data_t     bmdata[HAMMER2_FREEMAP_COUNT];
       char                    buf[HAMMER2_PBUFSIZE];
} __packed;

typedef union hammer2_media_data hammer2_media_data_t;

#endif /* !_VFS_HAMMER2_DISK_H_ */