[linux-block.git] / fs / erofs / decompressor.c

// 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

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);
}

/*
 * Fill all gaps with bounce pages if it's a sparse page list. Also check if
 * all physical pages are consecutive, which can be seen for moderate CR.
 */
static int z_erofs_lz4_prepare_dstpages(struct z_erofs_decompress_req *rq,
					struct page **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_lz4_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_mem(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 zero_padding is enabled */
	if (erofs_sb_has_zero_padding(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_lz4_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);

		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;
	} else {
		ret = 0;
	}

	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 int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
				  struct page **pagepool)
{
	const unsigned int nrpages_out =
		PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
	unsigned int dst_maptype;
	void *dst;
	int ret;

	/* one optimized fast path only for non bigpcluster cases yet */
	if (rq->inputsize <= PAGE_SIZE && nrpages_out == 1 && !rq->inplace_io) {
		DBG_BUGON(!*rq->out);
		dst = kmap_atomic(*rq->out);
		dst_maptype = 0;
		goto dstmap_out;
	}

	/* general decoding path which can be used for all cases */
	ret = z_erofs_lz4_prepare_dstpages(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 = z_erofs_lz4_decompress_mem(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(struct z_erofs_decompress_req *rq,
				     struct page **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;
}

static struct z_erofs_decompressor decompressors[] = {
	[Z_EROFS_COMPRESSION_SHIFTED] = {
		.decompress = z_erofs_shifted_transform,
		.name = "shifted"
	},
	[Z_EROFS_COMPRESSION_LZ4] = {
		.decompress = z_erofs_lz4_decompress,
		.name = "lz4"
	},
#ifdef CONFIG_EROFS_FS_ZIP_LZMA
	[Z_EROFS_COMPRESSION_LZMA] = {
		.decompress = z_erofs_lzma_decompress,
		.name = "lzma"
	},
#endif
};

int z_erofs_decompress(struct z_erofs_decompress_req *rq,
		       struct page **pagepool)
{
	return decompressors[rq->alg].decompress(rq, pagepool);
}
Commit	Line	Data
29b24f6c	1	// SPDX-License-Identifier: GPL-2.0-only
7fc45dbc	2	/*
7fc45dbc	3	* Copyright (C) 2019 HUAWEI, Inc.
592e7cd0	4	* https://www.huawei.com/
7fc45dbc GX	5	*/
7fc45dbc GX	6	#include "compress.h"
46c2d149	7	#include <linux/module.h>
7fc45dbc GX	8	#include <linux/lz4.h>
	9
	10	#ifndef LZ4_DISTANCE_MAX /* history window size */
	11	#define LZ4_DISTANCE_MAX 65535 /* set to maximum value by default */
	12	#endif
	13
af89bcef	14	#define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
0ffd71bc GX	15	#ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
	16	#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32)
	17	#endif
7fc45dbc	18
5d50538f	19	int z_erofs_load_lz4_config(struct super_block *sb,
46249cde GX	20	struct erofs_super_block *dsb,
46249cde GX	21	struct z_erofs_lz4_cfgs *lz4, int size)
5d50538f	22	{
4fea63f7	23	struct erofs_sb_info *sbi = EROFS_SB(sb);
46249cde GX	24	u16 distance;
	25
	26	if (lz4) {
	27	if (size < sizeof(struct z_erofs_lz4_cfgs)) {
	28	erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
	29	return -EINVAL;
	30	}
	31	distance = le16_to_cpu(lz4->max_distance);
4fea63f7 GX	32
	33	sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
	34	if (!sbi->lz4.max_pclusterblks) {
	35	sbi->lz4.max_pclusterblks = 1; /* reserved case */
	36	} else if (sbi->lz4.max_pclusterblks >
	37	Z_EROFS_PCLUSTER_MAX_SIZE / EROFS_BLKSIZ) {
	38	erofs_err(sb, "too large lz4 pclusterblks %u",
	39	sbi->lz4.max_pclusterblks);
	40	return -EINVAL;
	41	} else if (sbi->lz4.max_pclusterblks >= 2) {
	42	erofs_info(sb, "EXPERIMENTAL big pcluster feature in use. Use at your own risk!");
	43	}
46249cde	44	} else {
14373711	45	distance = le16_to_cpu(dsb->u1.lz4_max_distance);
4fea63f7	46	sbi->lz4.max_pclusterblks = 1;
46249cde	47	}
5d50538f	48
4fea63f7	49	sbi->lz4.max_distance_pages = distance ?
5d50538f HJ	50	DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
5d50538f HJ	51	LZ4_MAX_DISTANCE_PAGES;
4fea63f7	52	return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
5d50538f HJ	53	}
5d50538f HJ	54
966edfb0 GX	55	/*
	56	* Fill all gaps with bounce pages if it's a sparse page list. Also check if
	57	* all physical pages are consecutive, which can be seen for moderate CR.
	58	*/
	59	static int z_erofs_lz4_prepare_dstpages(struct z_erofs_decompress_req *rq,
eaa9172a	60	struct page **pagepool)
7fc45dbc GX	61	{
	62	const unsigned int nr =
	63	PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
	64	struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
af89bcef GX	65	unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
af89bcef GX	66	BITS_PER_LONG)] = { 0 };
5d50538f HJ	67	unsigned int lz4_max_distance_pages =
5d50538f HJ	68	EROFS_SB(rq->sb)->lz4.max_distance_pages;
7fc45dbc	69	void *kaddr = NULL;
af89bcef	70	unsigned int i, j, top;
7fc45dbc	71
af89bcef GX	72	top = 0;
af89bcef GX	73	for (i = j = 0; i < nr; ++i, ++j) {
7fc45dbc	74	struct page *const page = rq->out[i];
af89bcef	75	struct page *victim;
7fc45dbc	76
5d50538f	77	if (j >= lz4_max_distance_pages)
af89bcef GX	78	j = 0;
	79
	80	/* 'valid' bounced can only be tested after a complete round */
	81	if (test_bit(j, bounced)) {
5d50538f HJ	82	DBG_BUGON(i < lz4_max_distance_pages);
	83	DBG_BUGON(top >= lz4_max_distance_pages);
	84	availables[top++] = rq->out[i - lz4_max_distance_pages];
af89bcef	85	}
7fc45dbc GX	86
7fc45dbc GX	87	if (page) {
af89bcef	88	__clear_bit(j, bounced);
7fc45dbc GX	89	if (kaddr) {
	90	if (kaddr + PAGE_SIZE == page_address(page))
	91	kaddr += PAGE_SIZE;
	92	else
	93	kaddr = NULL;
	94	} else if (!i) {
	95	kaddr = page_address(page);
	96	}
	97	continue;
	98	}
	99	kaddr = NULL;
af89bcef	100	__set_bit(j, bounced);
7fc45dbc	101
af89bcef GX	102	if (top) {
	103	victim = availables[--top];
	104	get_page(victim);
7fc45dbc	105	} else {
b4892fa3 HJ	106	victim = erofs_allocpage(pagepool,
b4892fa3 HJ	107	GFP_KERNEL \| __GFP_NOFAIL);
6aaa7b06	108	set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
7fc45dbc	109	}
af89bcef	110	rq->out[i] = victim;
7fc45dbc GX	111	}
	112	return kaddr ? 1 : 0;
	113	}
	114
966edfb0	115	static void z_erofs_lz4_handle_inplace_io(struct z_erofs_decompress_req rq,
598162d0 GX	116	void inpage, unsigned int inputmargin, int *maptype,
598162d0 GX	117	bool support_0padding)
7fc45dbc	118	{
598162d0 GX	119	unsigned int nrpages_in, nrpages_out;
	120	unsigned int ofull, oend, inputsize, total, i, j;
	121	struct page **in;
	122	void src, tmp;
	123
	124	inputsize = rq->inputsize;
	125	nrpages_in = PAGE_ALIGN(inputsize) >> PAGE_SHIFT;
	126	oend = rq->pageofs_out + rq->outputsize;
	127	ofull = PAGE_ALIGN(oend);
	128	nrpages_out = ofull >> PAGE_SHIFT;
	129
	130	if (rq->inplace_io) {
	131	if (rq->partial_decoding \|\| !support_0padding \|\|
	132	ofull - oend < LZ4_DECOMPRESS_INPLACE_MARGIN(inputsize))
	133	goto docopy;
	134
	135	for (i = 0; i < nrpages_in; ++i) {
	136	DBG_BUGON(rq->in[i] == NULL);
	137	for (j = 0; j < nrpages_out - nrpages_in + i; ++j)
	138	if (rq->out[j] == rq->in[i])
	139	goto docopy;
	140	}
	141	}
	142
	143	if (nrpages_in <= 1) {
	144	*maptype = 0;
	145	return inpage;
	146	}
	147	kunmap_atomic(inpage);
	148	might_sleep();
	149	src = erofs_vm_map_ram(rq->in, nrpages_in);
	150	if (!src)
	151	return ERR_PTR(-ENOMEM);
	152	*maptype = 1;
	153	return src;
	154
	155	docopy:
	156	/* Or copy compressed data which can be overlapped to per-CPU buffer */
	157	in = rq->in;
	158	src = erofs_get_pcpubuf(nrpages_in);
	159	if (!src) {
	160	DBG_BUGON(1);
	161	kunmap_atomic(inpage);
	162	return ERR_PTR(-EFAULT);
	163	}
	164
	165	tmp = src;
	166	total = rq->inputsize;
	167	while (total) {
	168	unsigned int page_copycnt =
	169	min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
	170
	171	if (!inpage)
	172	inpage = kmap_atomic(*in);
	173	memcpy(tmp, inpage + *inputmargin, page_copycnt);
	174	kunmap_atomic(inpage);
	175	inpage = NULL;
	176	tmp += page_copycnt;
	177	total -= page_copycnt;
7fc45dbc	178	++in;
598162d0	179	*inputmargin = 0;
7fc45dbc	180	}
598162d0 GX	181	*maptype = 2;
598162d0 GX	182	return src;
7fc45dbc GX	183	}
7fc45dbc GX	184
966edfb0 GX	185	static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq,
966edfb0 GX	186	u8 *out)
7fc45dbc	187	{
598162d0 GX	188	unsigned int inputmargin;
	189	u8 headpage, src;
	190	bool support_0padding;
	191	int ret, maptype;
7fc45dbc	192
598162d0 GX	193	DBG_BUGON(*rq->in == NULL);
598162d0 GX	194	headpage = kmap_atomic(*rq->in);
7fc45dbc	195	inputmargin = 0;
0ffd71bc GX	196	support_0padding = false;
0ffd71bc GX	197
7e508f2c HJ	198	/* decompression inplace is only safe when zero_padding is enabled */
7e508f2c HJ	199	if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
0ffd71bc GX	200	support_0padding = true;
0ffd71bc GX	201
598162d0	202	while (!headpage[inputmargin & ~PAGE_MASK])
0ffd71bc GX	203	if (!(++inputmargin & ~PAGE_MASK))
	204	break;
	205
	206	if (inputmargin >= rq->inputsize) {
598162d0	207	kunmap_atomic(headpage);
0ffd71bc GX	208	return -EIO;
	209	}
	210	}
7fc45dbc	211
598162d0	212	rq->inputsize -= inputmargin;
966edfb0 GX	213	src = z_erofs_lz4_handle_inplace_io(rq, headpage, &inputmargin,
966edfb0 GX	214	&maptype, support_0padding);
598162d0 GX	215	if (IS_ERR(src))
598162d0 GX	216	return PTR_ERR(src);
7fc45dbc	217
af1038ab GX	218	/* legacy format could compress extra data in a pcluster. */
	219	if (rq->partial_decoding \|\| !support_0padding)
	220	ret = LZ4_decompress_safe_partial(src + inputmargin, out,
598162d0	221	rq->inputsize, rq->outputsize, rq->outputsize);
af1038ab GX	222	else
af1038ab GX	223	ret = LZ4_decompress_safe(src + inputmargin, out,
598162d0	224	rq->inputsize, rq->outputsize);
af1038ab	225
aa99a76b GX	226	if (ret != rq->outputsize) {
aa99a76b GX	227	erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
598162d0	228	ret, rq->inputsize, inputmargin, rq->outputsize);
aa99a76b	229
7fc45dbc	230	print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
598162d0	231	16, 1, src + inputmargin, rq->inputsize, true);
7fc45dbc GX	232	print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
7fc45dbc GX	233	16, 1, out, rq->outputsize, true);
aa99a76b GX	234
	235	if (ret >= 0)
	236	memset(out + ret, 0, rq->outputsize - ret);
7fc45dbc	237	ret = -EIO;
5b6e7e12 YH	238	} else {
5b6e7e12 YH	239	ret = 0;
7fc45dbc GX	240	}
7fc45dbc GX	241
598162d0	242	if (maptype == 0) {
7fc45dbc	243	kunmap_atomic(src);
598162d0 GX	244	} else if (maptype == 1) {
	245	vm_unmap_ram(src, PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT);
	246	} else if (maptype == 2) {
	247	erofs_put_pcpubuf(src);
	248	} else {
	249	DBG_BUGON(1);
	250	return -EFAULT;
	251	}
7fc45dbc GX	252	return ret;
	253	}
	254
966edfb0	255	static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
eaa9172a	256	struct page **pagepool)
7fc45dbc GX	257	{
	258	const unsigned int nrpages_out =
	259	PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
7fc45dbc GX	260	unsigned int dst_maptype;
7fc45dbc GX	261	void *dst;
598162d0	262	int ret;
7fc45dbc	263
5b6e7e12 YH	264	/* one optimized fast path only for non bigpcluster cases yet */
	265	if (rq->inputsize <= PAGE_SIZE && nrpages_out == 1 && !rq->inplace_io) {
	266	DBG_BUGON(!*rq->out);
	267	dst = kmap_atomic(*rq->out);
	268	dst_maptype = 0;
	269	goto dstmap_out;
7fc45dbc GX	270	}
7fc45dbc GX	271
598162d0	272	/* general decoding path which can be used for all cases */
966edfb0	273	ret = z_erofs_lz4_prepare_dstpages(rq, pagepool);
598162d0	274	if (ret < 0)
7fc45dbc	275	return ret;
598162d0	276	if (ret) {
7fc45dbc GX	277	dst = page_address(*rq->out);
	278	dst_maptype = 1;
	279	goto dstmap_out;
	280	}
	281
598162d0	282	dst = erofs_vm_map_ram(rq->out, nrpages_out);
7fc45dbc GX	283	if (!dst)
	284	return -ENOMEM;
	285	dst_maptype = 2;
	286
	287	dstmap_out:
966edfb0	288	ret = z_erofs_lz4_decompress_mem(rq, dst + rq->pageofs_out);
7fc45dbc GX	289
	290	if (!dst_maptype)
	291	kunmap_atomic(dst);
	292	else if (dst_maptype == 2)
73d03931	293	vm_unmap_ram(dst, nrpages_out);
7fc45dbc GX	294	return ret;
	295	}
	296
966edfb0	297	static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq,
eaa9172a	298	struct page **pagepool)
7fc45dbc GX	299	{
	300	const unsigned int nrpages_out =
	301	PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
	302	const unsigned int righthalf = PAGE_SIZE - rq->pageofs_out;
	303	unsigned char src, dst;
	304
	305	if (nrpages_out > 2) {
	306	DBG_BUGON(1);
	307	return -EIO;
	308	}
	309
	310	if (rq->out[0] == *rq->in) {
	311	DBG_BUGON(nrpages_out != 1);
	312	return 0;
	313	}
	314
	315	src = kmap_atomic(*rq->in);
4d202437	316	if (rq->out[0]) {
7fc45dbc GX	317	dst = kmap_atomic(rq->out[0]);
7fc45dbc GX	318	memcpy(dst + rq->pageofs_out, src, righthalf);
4d202437	319	kunmap_atomic(dst);
7fc45dbc GX	320	}
7fc45dbc GX	321
4d202437	322	if (nrpages_out == 2) {
7fc45dbc	323	DBG_BUGON(!rq->out[1]);
4d202437 GX	324	if (rq->out[1] == *rq->in) {
	325	memmove(src, src + righthalf, rq->pageofs_out);
	326	} else {
	327	dst = kmap_atomic(rq->out[1]);
	328	memcpy(dst, src + righthalf, rq->pageofs_out);
	329	kunmap_atomic(dst);
	330	}
7fc45dbc	331	}
7fc45dbc GX	332	kunmap_atomic(src);
	333	return 0;
	334	}
	335
966edfb0 GX	336	static struct z_erofs_decompressor decompressors[] = {
	337	[Z_EROFS_COMPRESSION_SHIFTED] = {
	338	.decompress = z_erofs_shifted_transform,
	339	.name = "shifted"
	340	},
	341	[Z_EROFS_COMPRESSION_LZ4] = {
	342	.decompress = z_erofs_lz4_decompress,
	343	.name = "lz4"
	344	},
622ceadd GX	345	#ifdef CONFIG_EROFS_FS_ZIP_LZMA
	346	[Z_EROFS_COMPRESSION_LZMA] = {
	347	.decompress = z_erofs_lzma_decompress,
	348	.name = "lzma"
	349	},
	350	#endif
966edfb0 GX	351	};
966edfb0 GX	352
7fc45dbc	353	int z_erofs_decompress(struct z_erofs_decompress_req *rq,
eaa9172a	354	struct page **pagepool)
7fc45dbc	355	{
966edfb0	356	return decompressors[rq->alg].decompress(rq, pagepool);
7fc45dbc	357	}