Commit 7fc45dbc authored by Gao Xiang's avatar Gao Xiang Committed by Greg Kroah-Hartman

staging: erofs: introduce generic decompression backend

This patch adds a new generic decompression framework
in order to replace the old LZ4-specific decompression code.

Even though LZ4 is still the only supported algorithm, yet
it is more cleaner and easy to integrate new algorithm than
the old almost hard-coded decompression backend.
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarGao Xiang <gaoxiang25@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 27481233
......@@ -9,5 +9,5 @@ obj-$(CONFIG_EROFS_FS) += erofs.o
ccflags-y += -I $(srctree)/$(src)/include
erofs-objs := super.o inode.o data.o namei.o dir.o utils.o
erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o unzip_vle_lz4.o zmap.o
erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o unzip_vle_lz4.o zmap.o decompressor.o
......@@ -9,6 +9,24 @@
#ifndef __EROFS_FS_COMPRESS_H
#define __EROFS_FS_COMPRESS_H
#include "internal.h"
enum {
Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX,
Z_EROFS_COMPRESSION_RUNTIME_MAX
};
struct z_erofs_decompress_req {
struct page **in, **out;
unsigned short pageofs_out;
unsigned int inputsize, outputsize;
/* indicate the algorithm will be used for decompression */
unsigned int alg;
bool inplace_io, partial_decoding;
};
/*
* - 0x5A110C8D ('sallocated', Z_EROFS_MAPPING_STAGING) -
* used to mark temporary allocated pages from other
......@@ -36,5 +54,8 @@ static inline bool z_erofs_put_stagingpage(struct list_head *pagepool,
return true;
}
int z_erofs_decompress(struct z_erofs_decompress_req *rq,
struct list_head *pagepool);
#endif
// SPDX-License-Identifier: GPL-2.0
/*
* linux/drivers/staging/erofs/decompressor.c
*
* Copyright (C) 2019 HUAWEI, Inc.
* http://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*/
#include "compress.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)
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;
};
static int 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 unused[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
BITS_PER_LONG)] = { 0 };
void *kaddr = NULL;
unsigned int i, j, k;
for (i = 0; i < nr; ++i) {
struct page *const page = rq->out[i];
j = i & (LZ4_MAX_DISTANCE_PAGES - 1);
if (availables[j])
__set_bit(j, unused);
if (page) {
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;
k = find_first_bit(unused, LZ4_MAX_DISTANCE_PAGES);
if (k < LZ4_MAX_DISTANCE_PAGES) {
j = k;
get_page(availables[j]);
} else {
DBG_BUGON(availables[j]);
if (!list_empty(pagepool)) {
availables[j] = lru_to_page(pagepool);
list_del(&availables[j]->lru);
DBG_BUGON(page_ref_count(availables[j]) != 1);
} else {
availables[j] = alloc_pages(GFP_KERNEL, 0);
if (!availables[j])
return -ENOMEM;
}
availables[j]->mapping = Z_EROFS_MAPPING_STAGING;
}
rq->out[i] = availables[j];
__clear_bit(j, unused);
}
return kaddr ? 1 : 0;
}
static void *generic_copy_inplace_data(struct z_erofs_decompress_req *rq,
u8 *src, unsigned int pageofs_in)
{
/*
* if in-place decompression is ongoing, those decompressed
* pages should be copied in order to avoid being overlapped.
*/
struct page **in = rq->in;
u8 *const tmp = erofs_get_pcpubuf(0);
u8 *tmpp = tmp;
unsigned int inlen = rq->inputsize - pageofs_in;
unsigned int count = min_t(uint, inlen, PAGE_SIZE - pageofs_in);
while (tmpp < tmp + inlen) {
if (!src)
src = kmap_atomic(*in);
memcpy(tmpp, src + pageofs_in, count);
kunmap_atomic(src);
src = NULL;
tmpp += count;
pageofs_in = 0;
count = PAGE_SIZE;
++in;
}
return tmp;
}
static int lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
{
unsigned int inputmargin, inlen;
u8 *src;
bool copied;
int ret;
if (rq->inputsize > PAGE_SIZE)
return -ENOTSUPP;
src = kmap_atomic(*rq->in);
inputmargin = 0;
copied = false;
inlen = rq->inputsize - inputmargin;
if (rq->inplace_io) {
src = generic_copy_inplace_data(rq, src, inputmargin);
inputmargin = 0;
copied = true;
}
ret = LZ4_decompress_safe_partial(src + inputmargin, out,
inlen, rq->outputsize,
rq->outputsize);
if (ret < 0) {
errln("%s, failed to decompress, in[%p, %u, %u] out[%p, %u]",
__func__, src + inputmargin, inlen, inputmargin,
out, rq->outputsize);
WARN_ON(1);
print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
16, 1, src + inputmargin, inlen, true);
print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
16, 1, out, rq->outputsize, true);
ret = -EIO;
}
if (copied)
erofs_put_pcpubuf(src);
else
kunmap_atomic(src);
return ret;
}
static struct z_erofs_decompressor decompressors[] = {
[Z_EROFS_COMPRESSION_SHIFTED] = {
.name = "shifted"
},
[Z_EROFS_COMPRESSION_LZ4] = {
.prepare_destpages = lz4_prepare_destpages,
.decompress = 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 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;
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(0);
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;
}
ret = alg->prepare_destpages(rq, pagepool);
if (ret < 0) {
return ret;
} else if (ret) {
dst = page_address(*rq->out);
dst_maptype = 1;
goto dstmap_out;
}
dst = erofs_vmap(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)
erofs_vunmap(dst, nrpages_out);
return ret;
}
static int shifted_decompress(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 = NULL;
} else {
dst = kmap_atomic(rq->out[0]);
memcpy(dst + rq->pageofs_out, src, righthalf);
}
if (rq->out[1] == *rq->in) {
memmove(src, src + righthalf, rq->pageofs_out);
} else if (nrpages_out == 2) {
if (dst)
kunmap_atomic(dst);
DBG_BUGON(!rq->out[1]);
dst = kmap_atomic(rq->out[1]);
memcpy(dst, src + righthalf, rq->pageofs_out);
}
if (dst)
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 shifted_decompress(rq, pagepool);
return decompress_generic(rq, pagepool);
}
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