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d3c12383c9
This commit changes the provider compress and decompress API to take ABD pointers instead of buffer pointers for both data source and destination. It then updates all providers to match. This doesn't actually change the providers to do chunked compression, just changes the API to allow such an update in the future. Helper macros are added to easily adapt the ABD functions to their buffer-based implementations. Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
138 lines
4.0 KiB
C
138 lines
4.0 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or https://opensource.org/licenses/CDDL-1.0.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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*/
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/*
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* We keep our own copy of this algorithm for 3 main reasons:
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* 1. If we didn't, anyone modifying common/os/compress.c would
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* directly break our on disk format
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* 2. Our version of lzjb does not have a number of checks that the
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* common/os version needs and uses
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* 3. We initialize the lempel to ensure deterministic results,
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* so that identical blocks can always be deduplicated.
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* In particular, we are adding the "feature" that compress() can
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* take a destination buffer size and returns the compressed length, or the
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* source length if compression would overflow the destination buffer.
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*/
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#include <sys/zfs_context.h>
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#include <sys/zio_compress.h>
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#define MATCH_BITS 6
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#define MATCH_MIN 3
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#define MATCH_MAX ((1 << MATCH_BITS) + (MATCH_MIN - 1))
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#define OFFSET_MASK ((1 << (16 - MATCH_BITS)) - 1)
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#define LEMPEL_SIZE 1024
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static size_t
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zfs_lzjb_compress_buf(void *s_start, void *d_start, size_t s_len,
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size_t d_len, int n)
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{
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(void) n;
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uchar_t *src = s_start;
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uchar_t *dst = d_start;
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uchar_t *cpy;
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uchar_t *copymap = NULL;
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int copymask = 1 << (NBBY - 1);
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int mlen, offset, hash;
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uint16_t *hp;
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uint16_t *lempel;
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lempel = kmem_zalloc(LEMPEL_SIZE * sizeof (uint16_t), KM_SLEEP);
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while (src < (uchar_t *)s_start + s_len) {
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if ((copymask <<= 1) == (1 << NBBY)) {
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if (dst >= (uchar_t *)d_start + d_len - 1 - 2 * NBBY) {
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kmem_free(lempel,
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LEMPEL_SIZE*sizeof (uint16_t));
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return (s_len);
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}
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copymask = 1;
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copymap = dst;
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*dst++ = 0;
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}
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if (src > (uchar_t *)s_start + s_len - MATCH_MAX) {
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*dst++ = *src++;
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continue;
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}
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hash = (src[0] << 16) + (src[1] << 8) + src[2];
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hash += hash >> 9;
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hash += hash >> 5;
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hp = &lempel[hash & (LEMPEL_SIZE - 1)];
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offset = (intptr_t)(src - *hp) & OFFSET_MASK;
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*hp = (uint16_t)(uintptr_t)src;
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cpy = src - offset;
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if (cpy >= (uchar_t *)s_start && cpy != src &&
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src[0] == cpy[0] && src[1] == cpy[1] && src[2] == cpy[2]) {
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*copymap |= copymask;
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for (mlen = MATCH_MIN; mlen < MATCH_MAX; mlen++)
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if (src[mlen] != cpy[mlen])
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break;
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*dst++ = ((mlen - MATCH_MIN) << (NBBY - MATCH_BITS)) |
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(offset >> NBBY);
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*dst++ = (uchar_t)offset;
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src += mlen;
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} else {
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*dst++ = *src++;
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}
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}
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kmem_free(lempel, LEMPEL_SIZE * sizeof (uint16_t));
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return (dst - (uchar_t *)d_start);
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}
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static int
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zfs_lzjb_decompress_buf(void *s_start, void *d_start,
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size_t s_len, size_t d_len, int n)
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{
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(void) s_len, (void) n;
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uchar_t *src = s_start;
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uchar_t *dst = d_start;
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uchar_t *d_end = (uchar_t *)d_start + d_len;
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uchar_t *cpy;
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uchar_t copymap = 0;
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int copymask = 1 << (NBBY - 1);
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while (dst < d_end) {
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if ((copymask <<= 1) == (1 << NBBY)) {
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copymask = 1;
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copymap = *src++;
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}
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if (copymap & copymask) {
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int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
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int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
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src += 2;
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if ((cpy = dst - offset) < (uchar_t *)d_start)
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return (-1);
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while (--mlen >= 0 && dst < d_end)
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*dst++ = *cpy++;
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} else {
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*dst++ = *src++;
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}
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}
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return (0);
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}
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ZFS_COMPRESS_WRAP_DECL(zfs_lzjb_compress)
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ZFS_DECOMPRESS_WRAP_DECL(zfs_lzjb_decompress)
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