zio_compress.c

Go to the documentation of this file.

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/zfs_context.h>
#include <sys/compress.h>
#include <sys/spa.h>
#include <sys/zio.h>
#include <sys/zio_compress.h>

/*
 * Compression vectors.
 */

zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
        {NULL,                  NULL,                   0,      "inherit"},
        {NULL,                  NULL,                   0,      "on"},
        {NULL,                  NULL,                   0,      "uncompressed"},
        {lzjb_compress,         lzjb_decompress,        0,      "lzjb"},
        {NULL,                  NULL,                   0,      "empty"},
        {gzip_compress,         gzip_decompress,        1,      "gzip-1"},
        {gzip_compress,         gzip_decompress,        2,      "gzip-2"},
        {gzip_compress,         gzip_decompress,        3,      "gzip-3"},
        {gzip_compress,         gzip_decompress,        4,      "gzip-4"},
        {gzip_compress,         gzip_decompress,        5,      "gzip-5"},
        {gzip_compress,         gzip_decompress,        6,      "gzip-6"},
        {gzip_compress,         gzip_decompress,        7,      "gzip-7"},
        {gzip_compress,         gzip_decompress,        8,      "gzip-8"},
        {gzip_compress,         gzip_decompress,        9,      "gzip-9"},
        {zle_compress,          zle_decompress,         64,     "zle"},
};

enum zio_compress
zio_compress_select(enum zio_compress child, enum zio_compress parent)
{
        ASSERT(child < ZIO_COMPRESS_FUNCTIONS);
        ASSERT(parent < ZIO_COMPRESS_FUNCTIONS);
        ASSERT(parent != ZIO_COMPRESS_INHERIT && parent != ZIO_COMPRESS_ON);

        if (child == ZIO_COMPRESS_INHERIT)
                return (parent);

        if (child == ZIO_COMPRESS_ON)
                return (ZIO_COMPRESS_ON_VALUE);

        return (child);
}

size_t
zio_compress_data(enum zio_compress c, void *src, void *dst, size_t s_len)
{
        uint64_t *word, *word_end;
        size_t c_len, d_len, r_len;
        zio_compress_info_t *ci = &zio_compress_table[c];

        ASSERT((uint_t)c < ZIO_COMPRESS_FUNCTIONS);
        ASSERT((uint_t)c == ZIO_COMPRESS_EMPTY || ci->ci_compress != NULL);

        /*
         * If the data is all zeroes, we don't even need to allocate
         * a block for it.  We indicate this by returning zero size.
         */
        word_end = (uint64_t *)((char *)src + s_len);
        for (word = src; word < word_end; word++)
                if (*word != 0)
                        break;

        if (word == word_end)
                return (0);

        if (c == ZIO_COMPRESS_EMPTY)
                return (s_len);

        /* Compress at least 12.5% */
        d_len = P2ALIGN(s_len - (s_len >> 3), (size_t)SPA_MINBLOCKSIZE);
        if (d_len == 0)
                return (s_len);

        c_len = ci->ci_compress(src, dst, s_len, d_len, ci->ci_level);

        if (c_len > d_len)
                return (s_len);

        /*
         * Cool.  We compressed at least as much as we were hoping to.
         * For both security and repeatability, pad out the last sector.
         */
        r_len = P2ROUNDUP(c_len, (size_t)SPA_MINBLOCKSIZE);
        if (r_len > c_len) {
                bzero((char *)dst + c_len, r_len - c_len);
                c_len = r_len;
        }

        ASSERT3U(c_len, <=, d_len);
        ASSERT(P2PHASE(c_len, (size_t)SPA_MINBLOCKSIZE) == 0);

        return (c_len);
}

int
zio_decompress_data(enum zio_compress c, void *src, void *dst,
    size_t s_len, size_t d_len)
{
        zio_compress_info_t *ci = &zio_compress_table[c];

        if ((uint_t)c >= ZIO_COMPRESS_FUNCTIONS || ci->ci_decompress == NULL)
                return (EINVAL);

        return (ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level));
}