Hi Chao,
On 2019/6/21 17:46, Chao Yu wrote:
> On 2019/6/21 0:07, Gao Xiang wrote:
>> 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.
>>
>> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
>> ---
>> drivers/staging/erofs/Makefile | 2 +-
>> drivers/staging/erofs/compress.h | 21 ++
>> drivers/staging/erofs/decompressor.c | 307 +++++++++++++++++++++++++++
>> 3 files changed, 329 insertions(+), 1 deletion(-)
>> create mode 100644 drivers/staging/erofs/decompressor.c
>>
>> diff --git a/drivers/staging/erofs/Makefile b/drivers/staging/erofs/Makefile
>> index 84b412c7a991..adeb5d6e2668 100644
>> --- a/drivers/staging/erofs/Makefile
>> +++ b/drivers/staging/erofs/Makefile
>> @@ -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
>>
>> diff --git a/drivers/staging/erofs/compress.h b/drivers/staging/erofs/compress.h
>> index 1dcfc3b35118..ebeccb1f4eae 100644
>> --- a/drivers/staging/erofs/compress.h
>> +++ b/drivers/staging/erofs/compress.h
>> @@ -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
>>
>> diff --git a/drivers/staging/erofs/decompressor.c b/drivers/staging/erofs/decompressor.c
>> new file mode 100644
>> index 000000000000..c68d17b579e0
>> --- /dev/null
>> +++ b/drivers/staging/erofs/decompressor.c
>> @@ -0,0 +1,307 @@
>> +// 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@xxxxxxxxxx>
>> + */
>> +#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;
>
> Could we use __stagingpage_alloc() instead opened codes, there is something
> different in between them though.
It was written "on propose" since the problem is that currently __stagingpage_alloc()
will allocate all pages in GFP_NOFAIL case, but memory allocation failure is accepted
here, therefore I open code to aim at introducing new decompression backend.
I will submit another patch after this series to clean up all staging page allocation
cases later, which was already on my scheduling list. :)
Thanks,
Gao Xiang
>
> Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
>
> Thanks,
>
>> + }
>> + 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;
>> + while (!src[inputmargin & ~PAGE_MASK])
>> + if (!(++inputmargin & ~PAGE_MASK))
>> + break;
>> +
>> + if (inputmargin >= rq->inputsize) {
>> + kunmap_atomic(src);
>> + return -EIO;
>> + }
>> +
>> + 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);
>> +
>> + 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);
>> +}
>> +
>>
