1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159
|
// SPDX-License-Identifier: CDDL-1.0
/*
* CDDL HEADER START
*
* This file and its contents are supplied under the terms of the
* Common Development and Distribution License ("CDDL"), version 1.0.
* You may only use this file in accordance with the terms of version
* 1.0 of the CDDL.
*
* A full copy of the text of the CDDL should have accompanied this
* source. A copy of the CDDL is also available via the Internet at
* http://www.illumos.org/license/CDDL.
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2013, 2016 by Delphix. All rights reserved.
*/
#include <sys/blkptr.h>
#include <sys/zfs_context.h>
#include <sys/zio.h>
#include <sys/zio_compress.h>
/*
* Embedded-data Block Pointers
*
* Normally, block pointers point (via their DVAs) to a block which holds data.
* If the data that we need to store is very small, this is an inefficient
* use of space, because a block must be at minimum 1 sector (typically 512
* bytes or 4KB). Additionally, reading these small blocks tends to generate
* more random reads.
*
* Embedded-data Block Pointers allow small pieces of data (the "payload",
* up to 112 bytes) to be stored in the block pointer itself, instead of
* being pointed to. The "Pointer" part of this name is a bit of a
* misnomer, as nothing is pointed to.
*
* BP_EMBEDDED_TYPE_DATA block pointers allow highly-compressible data to
* be embedded in the block pointer. The logic for this is handled in
* the SPA, by the zio pipeline. Therefore most code outside the zio
* pipeline doesn't need special-cases to handle these block pointers.
*
* See spa.h for details on the exact layout of embedded block pointers.
*/
void
encode_embedded_bp_compressed(blkptr_t *bp, void *data,
enum zio_compress comp, int uncompressed_size, int compressed_size)
{
uint64_t *bp64 = (uint64_t *)bp;
uint64_t w = 0;
uint8_t *data8 = data;
ASSERT3U(compressed_size, <=, BPE_PAYLOAD_SIZE);
ASSERT(uncompressed_size == compressed_size ||
comp != ZIO_COMPRESS_OFF);
ASSERT3U(comp, >=, ZIO_COMPRESS_OFF);
ASSERT3U(comp, <, ZIO_COMPRESS_FUNCTIONS);
memset(bp, 0, sizeof (*bp));
BP_SET_EMBEDDED(bp, B_TRUE);
BP_SET_COMPRESS(bp, comp);
BP_SET_BYTEORDER(bp, ZFS_HOST_BYTEORDER);
BPE_SET_LSIZE(bp, uncompressed_size);
BPE_SET_PSIZE(bp, compressed_size);
/*
* Encode the byte array into the words of the block pointer.
* First byte goes into low bits of first word (little endian).
*/
for (int i = 0; i < compressed_size; i++) {
BF64_SET(w, (i % sizeof (w)) * NBBY, NBBY, data8[i]);
if (i % sizeof (w) == sizeof (w) - 1) {
/* we've reached the end of a word */
ASSERT3P(bp64, <, bp + 1);
*bp64 = w;
bp64++;
if (!BPE_IS_PAYLOADWORD(bp, bp64))
bp64++;
w = 0;
}
}
/* write last partial word */
if (bp64 < (uint64_t *)(bp + 1))
*bp64 = w;
}
/*
* buf must be at least BPE_GET_PSIZE(bp) bytes long (which will never be
* more than BPE_PAYLOAD_SIZE bytes).
*/
void
decode_embedded_bp_compressed(const blkptr_t *bp, void *buf)
{
int psize;
uint8_t *buf8 = buf;
uint64_t w = 0;
const uint64_t *bp64 = (const uint64_t *)bp;
ASSERT(BP_IS_EMBEDDED(bp));
psize = BPE_GET_PSIZE(bp);
/*
* Decode the words of the block pointer into the byte array.
* Low bits of first word are the first byte (little endian).
*/
for (int i = 0; i < psize; i++) {
if (i % sizeof (w) == 0) {
/* beginning of a word */
ASSERT3P(bp64, <, bp + 1);
w = *bp64;
bp64++;
if (!BPE_IS_PAYLOADWORD(bp, bp64))
bp64++;
}
buf8[i] = BF64_GET(w, (i % sizeof (w)) * NBBY, NBBY);
}
}
/*
* Fill in the buffer with the (decompressed) payload of the embedded
* blkptr_t. Takes into account compression and byteorder (the payload is
* treated as a stream of bytes).
* Return 0 on success, or ENOSPC if it won't fit in the buffer.
*/
int
decode_embedded_bp(const blkptr_t *bp, void *buf, int buflen)
{
int lsize, psize;
ASSERT(BP_IS_EMBEDDED(bp));
lsize = BPE_GET_LSIZE(bp);
psize = BPE_GET_PSIZE(bp);
if (lsize > buflen)
return (SET_ERROR(ENOSPC));
ASSERT3U(lsize, ==, buflen);
if (BP_GET_COMPRESS(bp) != ZIO_COMPRESS_OFF) {
uint8_t dstbuf[BPE_PAYLOAD_SIZE];
decode_embedded_bp_compressed(bp, dstbuf);
abd_t cabd, dabd;
abd_get_from_buf_struct(&cabd, dstbuf, psize);
abd_get_from_buf_struct(&dabd, buf, buflen);
VERIFY0(zio_decompress_data(BP_GET_COMPRESS(bp), &cabd,
&dabd, psize, buflen, NULL));
abd_free(&dabd);
abd_free(&cabd);
} else {
ASSERT3U(lsize, ==, psize);
decode_embedded_bp_compressed(bp, buf);
}
return (0);
}
|