1267565Sdelphij/* 2267565Sdelphij * CDDL HEADER START 3267565Sdelphij * 4267565Sdelphij * This file and its contents are supplied under the terms of the 5267565Sdelphij * Common Development and Distribution License ("CDDL"), version 1.0. 6267565Sdelphij * You may only use this file in accordance with the terms of version 7267565Sdelphij * 1.0 of the CDDL. 8267565Sdelphij * 9267565Sdelphij * A full copy of the text of the CDDL should have accompanied this 10267565Sdelphij * source. A copy of the CDDL is also available via the Internet at 11267565Sdelphij * http://www.illumos.org/license/CDDL. 12267565Sdelphij * 13267565Sdelphij * CDDL HEADER END 14267565Sdelphij */ 15267565Sdelphij 16267565Sdelphij/* 17267565Sdelphij * Copyright (c) 2013 by Delphix. All rights reserved. 18267565Sdelphij */ 19267565Sdelphij 20267565Sdelphij#include <sys/zfs_context.h> 21267565Sdelphij#include <sys/zio.h> 22267565Sdelphij#include <sys/zio_compress.h> 23267565Sdelphij 24267565Sdelphij/* 25267565Sdelphij * Embedded-data Block Pointers 26267565Sdelphij * 27267565Sdelphij * Normally, block pointers point (via their DVAs) to a block which holds data. 28267565Sdelphij * If the data that we need to store is very small, this is an inefficient 29267565Sdelphij * use of space, because a block must be at minimum 1 sector (typically 512 30267565Sdelphij * bytes or 4KB). Additionally, reading these small blocks tends to generate 31267565Sdelphij * more random reads. 32267565Sdelphij * 33267565Sdelphij * Embedded-data Block Pointers allow small pieces of data (the "payload", 34267565Sdelphij * up to 112 bytes) to be stored in the block pointer itself, instead of 35267565Sdelphij * being pointed to. The "Pointer" part of this name is a bit of a 36267565Sdelphij * misnomer, as nothing is pointed to. 37267565Sdelphij * 38267565Sdelphij * BP_EMBEDDED_TYPE_DATA block pointers allow highly-compressible data to 39267565Sdelphij * be embedded in the block pointer. The logic for this is handled in 40267565Sdelphij * the SPA, by the zio pipeline. Therefore most code outside the zio 41267565Sdelphij * pipeline doesn't need special-cases to handle these block pointers. 42267565Sdelphij * 43267565Sdelphij * See spa.h for details on the exact layout of embedded block pointers. 44267565Sdelphij */ 45267565Sdelphij 46267565Sdelphijvoid 47267565Sdelphijencode_embedded_bp_compressed(blkptr_t *bp, void *data, 48267565Sdelphij enum zio_compress comp, int uncompressed_size, int compressed_size) 49267565Sdelphij{ 50267565Sdelphij uint64_t *bp64 = (uint64_t *)bp; 51267565Sdelphij uint64_t w = 0; 52267565Sdelphij uint8_t *data8 = data; 53267565Sdelphij 54267565Sdelphij ASSERT3U(compressed_size, <=, BPE_PAYLOAD_SIZE); 55267565Sdelphij ASSERT(uncompressed_size == compressed_size || 56267565Sdelphij comp != ZIO_COMPRESS_OFF); 57267565Sdelphij ASSERT3U(comp, >=, ZIO_COMPRESS_OFF); 58267565Sdelphij ASSERT3U(comp, <, ZIO_COMPRESS_FUNCTIONS); 59267565Sdelphij 60267565Sdelphij bzero(bp, sizeof (*bp)); 61267565Sdelphij BP_SET_EMBEDDED(bp, B_TRUE); 62267565Sdelphij BP_SET_COMPRESS(bp, comp); 63267565Sdelphij BP_SET_BYTEORDER(bp, ZFS_HOST_BYTEORDER); 64267565Sdelphij BPE_SET_LSIZE(bp, uncompressed_size); 65267565Sdelphij BPE_SET_PSIZE(bp, compressed_size); 66267565Sdelphij 67267565Sdelphij /* 68267565Sdelphij * Encode the byte array into the words of the block pointer. 69267565Sdelphij * First byte goes into low bits of first word (little endian). 70267565Sdelphij */ 71267565Sdelphij for (int i = 0; i < compressed_size; i++) { 72267565Sdelphij BF64_SET(w, (i % sizeof (w)) * NBBY, NBBY, data8[i]); 73267565Sdelphij if (i % sizeof (w) == sizeof (w) - 1) { 74267565Sdelphij /* we've reached the end of a word */ 75267565Sdelphij ASSERT3P(bp64, <, bp + 1); 76267565Sdelphij *bp64 = w; 77267565Sdelphij bp64++; 78267565Sdelphij if (!BPE_IS_PAYLOADWORD(bp, bp64)) 79267565Sdelphij bp64++; 80267565Sdelphij w = 0; 81267565Sdelphij } 82267565Sdelphij } 83267565Sdelphij /* write last partial word */ 84267565Sdelphij if (bp64 < (uint64_t *)(bp + 1)) 85267565Sdelphij *bp64 = w; 86267565Sdelphij} 87267565Sdelphij 88267565Sdelphij/* 89267565Sdelphij * buf must be at least BPE_GET_PSIZE(bp) bytes long (which will never be 90267565Sdelphij * more than BPE_PAYLOAD_SIZE bytes). 91267565Sdelphij */ 92267565Sdelphijvoid 93267565Sdelphijdecode_embedded_bp_compressed(const blkptr_t *bp, void *buf) 94267565Sdelphij{ 95267565Sdelphij int psize; 96267565Sdelphij uint8_t *buf8 = buf; 97267565Sdelphij uint64_t w = 0; 98267565Sdelphij const uint64_t *bp64 = (const uint64_t *)bp; 99267565Sdelphij 100267565Sdelphij ASSERT(BP_IS_EMBEDDED(bp)); 101267565Sdelphij 102267565Sdelphij psize = BPE_GET_PSIZE(bp); 103267565Sdelphij 104267565Sdelphij /* 105267565Sdelphij * Decode the words of the block pointer into the byte array. 106267565Sdelphij * Low bits of first word are the first byte (little endian). 107267565Sdelphij */ 108267565Sdelphij for (int i = 0; i < psize; i++) { 109267565Sdelphij if (i % sizeof (w) == 0) { 110267565Sdelphij /* beginning of a word */ 111267565Sdelphij ASSERT3P(bp64, <, bp + 1); 112267565Sdelphij w = *bp64; 113267565Sdelphij bp64++; 114267565Sdelphij if (!BPE_IS_PAYLOADWORD(bp, bp64)) 115267565Sdelphij bp64++; 116267565Sdelphij } 117267565Sdelphij buf8[i] = BF64_GET(w, (i % sizeof (w)) * NBBY, NBBY); 118267565Sdelphij } 119267565Sdelphij} 120