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OpenCloudOS-Kernel/fs/erofs/decompressor.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2019 HUAWEI, Inc.
* https://www.huawei.com/
*/
#include "compress.h"
#include <linux/module.h>
#include <linux/lz4.h>
#ifndef LZ4_DISTANCE_MAX /* history window size */
#define LZ4_DISTANCE_MAX 65535 /* set to maximum value by default */
#endif
#define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
#ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32)
#endif
struct z_erofs_decompressor {
/*
* if destpages have sparsed pages, fill them with bounce pages.
* it also check whether destpages indicate continuous physical memory.
*/
int (*prepare_destpages)(struct z_erofs_decompress_req *rq,
struct list_head *pagepool);
int (*decompress)(struct z_erofs_decompress_req *rq, u8 *out);
char *name;
};
int z_erofs_load_lz4_config(struct super_block *sb,
struct erofs_super_block *dsb,
struct z_erofs_lz4_cfgs *lz4, int size)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
u16 distance;
if (lz4) {
if (size < sizeof(struct z_erofs_lz4_cfgs)) {
erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
return -EINVAL;
}
distance = le16_to_cpu(lz4->max_distance);
sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
if (!sbi->lz4.max_pclusterblks) {
sbi->lz4.max_pclusterblks = 1; /* reserved case */
} else if (sbi->lz4.max_pclusterblks >
Z_EROFS_PCLUSTER_MAX_SIZE / EROFS_BLKSIZ) {
erofs_err(sb, "too large lz4 pclusterblks %u",
sbi->lz4.max_pclusterblks);
return -EINVAL;
} else if (sbi->lz4.max_pclusterblks >= 2) {
erofs_info(sb, "EXPERIMENTAL big pcluster feature in use. Use at your own risk!");
}
} else {
distance = le16_to_cpu(dsb->u1.lz4_max_distance);
sbi->lz4.max_pclusterblks = 1;
}
sbi->lz4.max_distance_pages = distance ?
DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
LZ4_MAX_DISTANCE_PAGES;
return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
}
static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
struct list_head *pagepool)
{
const unsigned int nr =
PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
BITS_PER_LONG)] = { 0 };
unsigned int lz4_max_distance_pages =
EROFS_SB(rq->sb)->lz4.max_distance_pages;
void *kaddr = NULL;
unsigned int i, j, top;
top = 0;
for (i = j = 0; i < nr; ++i, ++j) {
struct page *const page = rq->out[i];
struct page *victim;
if (j >= lz4_max_distance_pages)
j = 0;
/* 'valid' bounced can only be tested after a complete round */
if (test_bit(j, bounced)) {
DBG_BUGON(i < lz4_max_distance_pages);
DBG_BUGON(top >= lz4_max_distance_pages);
availables[top++] = rq->out[i - lz4_max_distance_pages];
}
if (page) {
__clear_bit(j, bounced);
if (kaddr) {
if (kaddr + PAGE_SIZE == page_address(page))
kaddr += PAGE_SIZE;
else
kaddr = NULL;
} else if (!i) {
kaddr = page_address(page);
}
continue;
}
kaddr = NULL;
__set_bit(j, bounced);
if (top) {
victim = availables[--top];
get_page(victim);
} else {
victim = erofs_allocpage(pagepool,
GFP_KERNEL | __GFP_NOFAIL);
set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
}
rq->out[i] = victim;
}
return kaddr ? 1 : 0;
}
static void *z_erofs_handle_inplace_io(struct z_erofs_decompress_req *rq,
void *inpage, unsigned int *inputmargin, int *maptype,
bool support_0padding)
{
unsigned int nrpages_in, nrpages_out;
unsigned int ofull, oend, inputsize, total, i, j;
struct page **in;
void *src, *tmp;
inputsize = rq->inputsize;
nrpages_in = PAGE_ALIGN(inputsize) >> PAGE_SHIFT;
oend = rq->pageofs_out + rq->outputsize;
ofull = PAGE_ALIGN(oend);
nrpages_out = ofull >> PAGE_SHIFT;
if (rq->inplace_io) {
if (rq->partial_decoding || !support_0padding ||
ofull - oend < LZ4_DECOMPRESS_INPLACE_MARGIN(inputsize))
goto docopy;
for (i = 0; i < nrpages_in; ++i) {
DBG_BUGON(rq->in[i] == NULL);
for (j = 0; j < nrpages_out - nrpages_in + i; ++j)
if (rq->out[j] == rq->in[i])
goto docopy;
}
}
if (nrpages_in <= 1) {
*maptype = 0;
return inpage;
}
kunmap_atomic(inpage);
might_sleep();
src = erofs_vm_map_ram(rq->in, nrpages_in);
if (!src)
return ERR_PTR(-ENOMEM);
*maptype = 1;
return src;
docopy:
/* Or copy compressed data which can be overlapped to per-CPU buffer */
in = rq->in;
src = erofs_get_pcpubuf(nrpages_in);
if (!src) {
DBG_BUGON(1);
kunmap_atomic(inpage);
return ERR_PTR(-EFAULT);
}
tmp = src;
total = rq->inputsize;
while (total) {
unsigned int page_copycnt =
min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
if (!inpage)
inpage = kmap_atomic(*in);
memcpy(tmp, inpage + *inputmargin, page_copycnt);
kunmap_atomic(inpage);
inpage = NULL;
tmp += page_copycnt;
total -= page_copycnt;
++in;
*inputmargin = 0;
}
*maptype = 2;
return src;
}
static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
{
unsigned int inputmargin;
u8 *headpage, *src;
bool support_0padding;
int ret, maptype;
DBG_BUGON(*rq->in == NULL);
headpage = kmap_atomic(*rq->in);
inputmargin = 0;
support_0padding = false;
/* decompression inplace is only safe when 0padding is enabled */
if (erofs_sb_has_lz4_0padding(EROFS_SB(rq->sb))) {
support_0padding = true;
while (!headpage[inputmargin & ~PAGE_MASK])
if (!(++inputmargin & ~PAGE_MASK))
break;
if (inputmargin >= rq->inputsize) {
kunmap_atomic(headpage);
return -EIO;
}
}
rq->inputsize -= inputmargin;
src = z_erofs_handle_inplace_io(rq, headpage, &inputmargin, &maptype,
support_0padding);
if (IS_ERR(src))
return PTR_ERR(src);
/* legacy format could compress extra data in a pcluster. */
if (rq->partial_decoding || !support_0padding)
ret = LZ4_decompress_safe_partial(src + inputmargin, out,
rq->inputsize, rq->outputsize, rq->outputsize);
else
ret = LZ4_decompress_safe(src + inputmargin, out,
rq->inputsize, rq->outputsize);
if (ret != rq->outputsize) {
erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
ret, rq->inputsize, inputmargin, rq->outputsize);
WARN_ON(1);
print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
16, 1, src + inputmargin, rq->inputsize, true);
print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
16, 1, out, rq->outputsize, true);
if (ret >= 0)
memset(out + ret, 0, rq->outputsize - ret);
ret = -EIO;
}
if (maptype == 0) {
kunmap_atomic(src);
} else if (maptype == 1) {
vm_unmap_ram(src, PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT);
} else if (maptype == 2) {
erofs_put_pcpubuf(src);
} else {
DBG_BUGON(1);
return -EFAULT;
}
return ret;
}
static struct z_erofs_decompressor decompressors[] = {
[Z_EROFS_COMPRESSION_SHIFTED] = {
.name = "shifted"
},
[Z_EROFS_COMPRESSION_LZ4] = {
.prepare_destpages = z_erofs_lz4_prepare_destpages,
.decompress = z_erofs_lz4_decompress,
.name = "lz4"
},
};
static void copy_from_pcpubuf(struct page **out, const char *dst,
unsigned short pageofs_out,
unsigned int outputsize)
{
const char *end = dst + outputsize;
const unsigned int righthalf = PAGE_SIZE - pageofs_out;
const char *cur = dst - pageofs_out;
while (cur < end) {
struct page *const page = *out++;
if (page) {
char *buf = kmap_atomic(page);
if (cur >= dst) {
memcpy(buf, cur, min_t(uint, PAGE_SIZE,
end - cur));
} else {
memcpy(buf + pageofs_out, cur + pageofs_out,
min_t(uint, righthalf, end - cur));
}
kunmap_atomic(buf);
}
cur += PAGE_SIZE;
}
}
static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
struct list_head *pagepool)
{
const unsigned int nrpages_out =
PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
const struct z_erofs_decompressor *alg = decompressors + rq->alg;
unsigned int dst_maptype;
void *dst;
int ret;
/* two optimized fast paths only for non bigpcluster cases yet */
if (rq->inputsize <= PAGE_SIZE) {
if (nrpages_out == 1 && !rq->inplace_io) {
DBG_BUGON(!*rq->out);
dst = kmap_atomic(*rq->out);
dst_maptype = 0;
goto dstmap_out;
}
/*
* For the case of small output size (especially much less
* than PAGE_SIZE), memcpy the decompressed data rather than
* compressed data is preferred.
*/
if (rq->outputsize <= PAGE_SIZE * 7 / 8) {
dst = erofs_get_pcpubuf(1);
if (IS_ERR(dst))
return PTR_ERR(dst);
rq->inplace_io = false;
ret = alg->decompress(rq, dst);
if (!ret)
copy_from_pcpubuf(rq->out, dst, rq->pageofs_out,
rq->outputsize);
erofs_put_pcpubuf(dst);
return ret;
}
}
/* general decoding path which can be used for all cases */
ret = alg->prepare_destpages(rq, pagepool);
if (ret < 0)
return ret;
if (ret) {
dst = page_address(*rq->out);
dst_maptype = 1;
goto dstmap_out;
}
dst = erofs_vm_map_ram(rq->out, nrpages_out);
if (!dst)
return -ENOMEM;
dst_maptype = 2;
dstmap_out:
ret = alg->decompress(rq, dst + rq->pageofs_out);
if (!dst_maptype)
kunmap_atomic(dst);
else if (dst_maptype == 2)
vm_unmap_ram(dst, nrpages_out);
return ret;
}
static int z_erofs_shifted_transform(const struct z_erofs_decompress_req *rq,
struct list_head *pagepool)
{
const unsigned int nrpages_out =
PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
const unsigned int righthalf = PAGE_SIZE - rq->pageofs_out;
unsigned char *src, *dst;
if (nrpages_out > 2) {
DBG_BUGON(1);
return -EIO;
}
if (rq->out[0] == *rq->in) {
DBG_BUGON(nrpages_out != 1);
return 0;
}
src = kmap_atomic(*rq->in);
if (rq->out[0]) {
dst = kmap_atomic(rq->out[0]);
memcpy(dst + rq->pageofs_out, src, righthalf);
kunmap_atomic(dst);
}
if (nrpages_out == 2) {
DBG_BUGON(!rq->out[1]);
if (rq->out[1] == *rq->in) {
memmove(src, src + righthalf, rq->pageofs_out);
} else {
dst = kmap_atomic(rq->out[1]);
memcpy(dst, src + righthalf, rq->pageofs_out);
kunmap_atomic(dst);
}
}
kunmap_atomic(src);
return 0;
}
int z_erofs_decompress(struct z_erofs_decompress_req *rq,
struct list_head *pagepool)
{
if (rq->alg == Z_EROFS_COMPRESSION_SHIFTED)
return z_erofs_shifted_transform(rq, pagepool);
return z_erofs_decompress_generic(rq, pagepool);
}
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