342 lines
8.2 KiB
C
342 lines
8.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2019 HUAWEI, Inc.
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* http://www.huawei.com/
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* Created by Gao Xiang <gaoxiang25@huawei.com>
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*/
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#include "compress.h"
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#include <linux/module.h>
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#include <linux/lz4.h>
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#ifndef LZ4_DISTANCE_MAX /* history window size */
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#define LZ4_DISTANCE_MAX 65535 /* set to maximum value by default */
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#endif
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#define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
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#ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
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#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32)
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#endif
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struct z_erofs_decompressor {
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/*
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* if destpages have sparsed pages, fill them with bounce pages.
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* it also check whether destpages indicate continuous physical memory.
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*/
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int (*prepare_destpages)(struct z_erofs_decompress_req *rq,
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struct list_head *pagepool);
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int (*decompress)(struct z_erofs_decompress_req *rq, u8 *out);
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char *name;
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};
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static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
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struct list_head *pagepool)
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{
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const unsigned int nr =
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PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
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struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
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unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
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BITS_PER_LONG)] = { 0 };
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void *kaddr = NULL;
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unsigned int i, j, top;
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top = 0;
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for (i = j = 0; i < nr; ++i, ++j) {
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struct page *const page = rq->out[i];
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struct page *victim;
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if (j >= LZ4_MAX_DISTANCE_PAGES)
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j = 0;
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/* 'valid' bounced can only be tested after a complete round */
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if (test_bit(j, bounced)) {
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DBG_BUGON(i < LZ4_MAX_DISTANCE_PAGES);
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DBG_BUGON(top >= LZ4_MAX_DISTANCE_PAGES);
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availables[top++] = rq->out[i - LZ4_MAX_DISTANCE_PAGES];
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}
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if (page) {
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__clear_bit(j, bounced);
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if (kaddr) {
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if (kaddr + PAGE_SIZE == page_address(page))
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kaddr += PAGE_SIZE;
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else
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kaddr = NULL;
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} else if (!i) {
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kaddr = page_address(page);
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}
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continue;
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}
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kaddr = NULL;
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__set_bit(j, bounced);
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if (top) {
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victim = availables[--top];
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get_page(victim);
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} else {
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victim = erofs_allocpage(pagepool, GFP_KERNEL, false);
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if (!victim)
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return -ENOMEM;
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victim->mapping = Z_EROFS_MAPPING_STAGING;
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}
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rq->out[i] = victim;
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}
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return kaddr ? 1 : 0;
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}
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static void *generic_copy_inplace_data(struct z_erofs_decompress_req *rq,
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u8 *src, unsigned int pageofs_in)
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{
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/*
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* if in-place decompression is ongoing, those decompressed
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* pages should be copied in order to avoid being overlapped.
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*/
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struct page **in = rq->in;
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u8 *const tmp = erofs_get_pcpubuf(0);
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u8 *tmpp = tmp;
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unsigned int inlen = rq->inputsize - pageofs_in;
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unsigned int count = min_t(uint, inlen, PAGE_SIZE - pageofs_in);
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while (tmpp < tmp + inlen) {
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if (!src)
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src = kmap_atomic(*in);
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memcpy(tmpp, src + pageofs_in, count);
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kunmap_atomic(src);
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src = NULL;
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tmpp += count;
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pageofs_in = 0;
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count = PAGE_SIZE;
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++in;
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}
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return tmp;
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}
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static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
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{
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unsigned int inputmargin, inlen;
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u8 *src;
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bool copied, support_0padding;
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int ret;
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if (rq->inputsize > PAGE_SIZE)
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return -EOPNOTSUPP;
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src = kmap_atomic(*rq->in);
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inputmargin = 0;
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support_0padding = false;
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/* decompression inplace is only safe when 0padding is enabled */
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if (EROFS_SB(rq->sb)->feature_incompat &
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EROFS_FEATURE_INCOMPAT_LZ4_0PADDING) {
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support_0padding = true;
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while (!src[inputmargin & ~PAGE_MASK])
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if (!(++inputmargin & ~PAGE_MASK))
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break;
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if (inputmargin >= rq->inputsize) {
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kunmap_atomic(src);
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return -EIO;
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}
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}
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copied = false;
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inlen = rq->inputsize - inputmargin;
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if (rq->inplace_io) {
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const uint oend = (rq->pageofs_out +
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rq->outputsize) & ~PAGE_MASK;
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const uint nr = PAGE_ALIGN(rq->pageofs_out +
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rq->outputsize) >> PAGE_SHIFT;
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if (rq->partial_decoding || !support_0padding ||
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rq->out[nr - 1] != rq->in[0] ||
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rq->inputsize - oend <
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LZ4_DECOMPRESS_INPLACE_MARGIN(inlen)) {
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src = generic_copy_inplace_data(rq, src, inputmargin);
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inputmargin = 0;
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copied = true;
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}
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}
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ret = LZ4_decompress_safe_partial(src + inputmargin, out,
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inlen, rq->outputsize,
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rq->outputsize);
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if (ret != rq->outputsize) {
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erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
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ret, inlen, inputmargin, rq->outputsize);
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WARN_ON(1);
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print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
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16, 1, src + inputmargin, inlen, true);
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print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
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16, 1, out, rq->outputsize, true);
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if (ret >= 0)
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memset(out + ret, 0, rq->outputsize - ret);
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ret = -EIO;
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}
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if (copied)
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erofs_put_pcpubuf(src);
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else
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kunmap_atomic(src);
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return ret;
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}
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static struct z_erofs_decompressor decompressors[] = {
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[Z_EROFS_COMPRESSION_SHIFTED] = {
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.name = "shifted"
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},
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[Z_EROFS_COMPRESSION_LZ4] = {
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.prepare_destpages = z_erofs_lz4_prepare_destpages,
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.decompress = z_erofs_lz4_decompress,
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.name = "lz4"
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},
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};
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static void copy_from_pcpubuf(struct page **out, const char *dst,
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unsigned short pageofs_out,
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unsigned int outputsize)
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{
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const char *end = dst + outputsize;
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const unsigned int righthalf = PAGE_SIZE - pageofs_out;
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const char *cur = dst - pageofs_out;
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while (cur < end) {
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struct page *const page = *out++;
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if (page) {
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char *buf = kmap_atomic(page);
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if (cur >= dst) {
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memcpy(buf, cur, min_t(uint, PAGE_SIZE,
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end - cur));
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} else {
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memcpy(buf + pageofs_out, cur + pageofs_out,
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min_t(uint, righthalf, end - cur));
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}
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kunmap_atomic(buf);
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}
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cur += PAGE_SIZE;
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}
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}
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static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
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struct list_head *pagepool)
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{
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const unsigned int nrpages_out =
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PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
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const struct z_erofs_decompressor *alg = decompressors + rq->alg;
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unsigned int dst_maptype;
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void *dst;
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int ret, i;
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if (nrpages_out == 1 && !rq->inplace_io) {
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DBG_BUGON(!*rq->out);
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dst = kmap_atomic(*rq->out);
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dst_maptype = 0;
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goto dstmap_out;
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}
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/*
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* For the case of small output size (especially much less
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* than PAGE_SIZE), memcpy the decompressed data rather than
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* compressed data is preferred.
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*/
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if (rq->outputsize <= PAGE_SIZE * 7 / 8) {
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dst = erofs_get_pcpubuf(0);
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if (IS_ERR(dst))
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return PTR_ERR(dst);
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rq->inplace_io = false;
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ret = alg->decompress(rq, dst);
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if (!ret)
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copy_from_pcpubuf(rq->out, dst, rq->pageofs_out,
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rq->outputsize);
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erofs_put_pcpubuf(dst);
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return ret;
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}
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ret = alg->prepare_destpages(rq, pagepool);
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if (ret < 0) {
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return ret;
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} else if (ret) {
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dst = page_address(*rq->out);
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dst_maptype = 1;
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goto dstmap_out;
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}
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i = 0;
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while (1) {
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dst = vm_map_ram(rq->out, nrpages_out, -1, PAGE_KERNEL);
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/* retry two more times (totally 3 times) */
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if (dst || ++i >= 3)
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break;
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vm_unmap_aliases();
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}
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if (!dst)
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return -ENOMEM;
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dst_maptype = 2;
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dstmap_out:
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ret = alg->decompress(rq, dst + rq->pageofs_out);
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if (!dst_maptype)
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kunmap_atomic(dst);
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else if (dst_maptype == 2)
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vm_unmap_ram(dst, nrpages_out);
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return ret;
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}
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static int z_erofs_shifted_transform(const struct z_erofs_decompress_req *rq,
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struct list_head *pagepool)
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{
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const unsigned int nrpages_out =
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PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
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const unsigned int righthalf = PAGE_SIZE - rq->pageofs_out;
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unsigned char *src, *dst;
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if (nrpages_out > 2) {
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DBG_BUGON(1);
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return -EIO;
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}
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if (rq->out[0] == *rq->in) {
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DBG_BUGON(nrpages_out != 1);
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return 0;
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}
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src = kmap_atomic(*rq->in);
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if (!rq->out[0]) {
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dst = NULL;
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} else {
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dst = kmap_atomic(rq->out[0]);
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memcpy(dst + rq->pageofs_out, src, righthalf);
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}
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if (rq->out[1] == *rq->in) {
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memmove(src, src + righthalf, rq->pageofs_out);
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} else if (nrpages_out == 2) {
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if (dst)
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kunmap_atomic(dst);
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DBG_BUGON(!rq->out[1]);
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dst = kmap_atomic(rq->out[1]);
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memcpy(dst, src + righthalf, rq->pageofs_out);
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}
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if (dst)
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kunmap_atomic(dst);
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kunmap_atomic(src);
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return 0;
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}
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int z_erofs_decompress(struct z_erofs_decompress_req *rq,
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struct list_head *pagepool)
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{
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if (rq->alg == Z_EROFS_COMPRESSION_SHIFTED)
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return z_erofs_shifted_transform(rq, pagepool);
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return z_erofs_decompress_generic(rq, pagepool);
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}
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