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/*
* BSD 3-Clause New License (https://spdx.org/licenses/BSD-3-Clause.html)
*
* 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 copyright holder 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 HOLDER 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.
*/
/*
* Copyright (c) 2016-2018, Klara Inc.
* Copyright (c) 2016-2018, Allan Jude
* Copyright (c) 2018-2020, Sebastian Gottschall
* Copyright (c) 2019-2020, Michael Niewöhner
* Copyright (c) 2020, The FreeBSD Foundation [1]
*
* [1] Portions of this software were developed by Allan Jude
* under sponsorship from the FreeBSD Foundation.
*/
#ifndef _ZFS_ZSTD_H
#define _ZFS_ZSTD_H
#ifdef __cplusplus
extern "C" {
#endif
/*
* ZSTD block header
* NOTE: all fields in this header are in big endian order.
*/
typedef struct zfs_zstd_header {
/* Compressed size of data */
uint32_t c_len;
/*
* Version and compression level
* We used to use a union to reference compression level
* and version easily, but as it turns out, relying on the
* ordering of bitfields is not remotely portable.
* So now we have get/set functions in zfs_zstd.c for
* manipulating this in just the right way forever.
*/
uint32_t raw_version_level;
char data[];
} zfs_zstdhdr_t;
/*
* Simple struct to pass the data from raw_version_level around.
*/
typedef struct zfs_zstd_meta {
uint8_t level;
uint32_t version;
} zfs_zstdmeta_t;
/*
* kstat helper macros
*/
#define ZSTDSTAT(stat) (zstd_stats.stat.value.ui64)
#define ZSTDSTAT_ZERO(stat) \
atomic_store_64(&zstd_stats.stat.value.ui64, 0)
#define ZSTDSTAT_ADD(stat, val) \
atomic_add_64(&zstd_stats.stat.value.ui64, (val))
#define ZSTDSTAT_SUB(stat, val) \
atomic_sub_64(&zstd_stats.stat.value.ui64, (val))
#define ZSTDSTAT_BUMP(stat) ZSTDSTAT_ADD(stat, 1)
/* (de)init for user space / kernel emulation */
int zstd_init(void);
void zstd_fini(void);
size_t zfs_zstd_compress(abd_t *src, abd_t *dst, size_t s_len,
size_t d_len, int level);
int zfs_zstd_get_level(void *s_start, size_t s_len, uint8_t *level);
int zfs_zstd_decompress_level(abd_t *src, abd_t *dst, size_t s_len,
size_t d_len, uint8_t *level);
int zfs_zstd_decompress(abd_t *src, abd_t *dst, size_t s_len,
size_t d_len, int n);
void zfs_zstd_cache_reap_now(void);
/*
* So, the reason we have all these complicated set/get functions is that
* originally, in the zstd "header" we wrote out to disk, we used a 32-bit
* bitfield to store the "level" (8 bits) and "version" (24 bits).
*
* Unfortunately, bitfields make few promises about how they're arranged in
* memory...
*
* By way of example, if we were using version 1.4.5 and level 3, it'd be
* level = 0x03, version = 10405/0x0028A5, which gets broken into Vhigh = 0x00,
* Vmid = 0x28, Vlow = 0xA5. We include these positions below to help follow
* which data winds up where.
*
* As a consequence, we wound up with little endian platforms with a layout
* like this in memory:
*
* 0 8 16 24 32
* +-------+-------+-------+-------+
* | Vlow | Vmid | Vhigh | level |
* +-------+-------+-------+-------+
* =A5 =28 =00 =03
*
* ...and then, after being run through BE_32(), serializing this out to
* disk:
*
* 0 8 16 24 32
* +-------+-------+-------+-------+
* | level | Vhigh | Vmid | Vlow |
* +-------+-------+-------+-------+
* =03 =00 =28 =A5
*
* while on big-endian systems, since BE_32() is a noop there, both in
* memory and on disk, we wind up with:
*
* 0 8 16 24 32
* +-------+-------+-------+-------+
* | Vhigh | Vmid | Vlow | level |
* +-------+-------+-------+-------+
* =00 =28 =A5 =03
*
* (Vhigh is always 0 until version exceeds 6.55.35. Vmid and Vlow are the
* other two bytes of the "version" data.)
*
* So now we use the BF32_SET macros to get consistent behavior (the
* ondisk LE encoding, since x86 currently rules the world) across
* platforms, but the "get" behavior requires that we check each of the
* bytes in the aforementioned former-bitfield for 0x00, and from there,
* we can know which possible layout we're dealing with. (Only the two
* that have been observed in the wild are illustrated above, but handlers
* for all 4 positions of 0x00 are implemented.
*/
static inline void
zfs_get_hdrmeta(const zfs_zstdhdr_t *blob, zfs_zstdmeta_t *res)
{
uint32_t raw = blob->raw_version_level;
uint8_t findme = 0xff;
int shift;
for (shift = 0; shift < 4; shift++) {
findme = BF32_GET(raw, 8*shift, 8);
if (findme == 0)
break;
}
switch (shift) {
case 0:
res->level = BF32_GET(raw, 24, 8);
res->version = BSWAP_32(raw);
res->version = BF32_GET(res->version, 8, 24);
break;
case 1:
res->level = BF32_GET(raw, 0, 8);
res->version = BSWAP_32(raw);
res->version = BF32_GET(res->version, 0, 24);
break;
case 2:
res->level = BF32_GET(raw, 24, 8);
res->version = BF32_GET(raw, 0, 24);
break;
case 3:
res->level = BF32_GET(raw, 0, 8);
res->version = BF32_GET(raw, 8, 24);
break;
default:
res->level = 0;
res->version = 0;
break;
}
}
static inline uint8_t
zfs_get_hdrlevel(const zfs_zstdhdr_t *blob)
{
uint8_t level = 0;
zfs_zstdmeta_t res;
zfs_get_hdrmeta(blob, &res);
level = res.level;
return (level);
}
static inline uint32_t
zfs_get_hdrversion(const zfs_zstdhdr_t *blob)
{
uint32_t version = 0;
zfs_zstdmeta_t res;
zfs_get_hdrmeta(blob, &res);
version = res.version;
return (version);
}
static inline void
zfs_set_hdrversion(zfs_zstdhdr_t *blob, uint32_t version)
{
/* cppcheck-suppress syntaxError */
BF32_SET(blob->raw_version_level, 0, 24, version);
}
static inline void
zfs_set_hdrlevel(zfs_zstdhdr_t *blob, uint8_t level)
{
/* cppcheck-suppress syntaxError */
BF32_SET(blob->raw_version_level, 24, 8, level);
}
#ifdef __cplusplus
}
#endif
#endif /* _ZFS_ZSTD_H */
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