[linux.git] / fs / btrfs / zstd.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2016-present, Facebook, Inc.
 * All rights reserved.
 *
 */

#include <linux/bio.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/refcount.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/zstd.h>
#include "compression.h"

#define ZSTD_BTRFS_MAX_WINDOWLOG 17
#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
#define ZSTD_BTRFS_DEFAULT_LEVEL 3

static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len)
{
	ZSTD_parameters params = ZSTD_getParams(ZSTD_BTRFS_DEFAULT_LEVEL,
						src_len, 0);

	if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)
		params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
	WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);
	return params;
}

struct workspace {
	void *mem;
	size_t size;
	char *buf;
	struct list_head list;
	ZSTD_inBuffer in_buf;
	ZSTD_outBuffer out_buf;
};

static void zstd_free_workspace(struct list_head *ws)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);

	kvfree(workspace->mem);
	kfree(workspace->buf);
	kfree(workspace);
}

static struct list_head *zstd_alloc_workspace(void)
{
	ZSTD_parameters params =
			zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT);
	struct workspace *workspace;

	workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
	if (!workspace)
		return ERR_PTR(-ENOMEM);

	workspace->size = max_t(size_t,
			ZSTD_CStreamWorkspaceBound(params.cParams),
			ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
	workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
	workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!workspace->mem || !workspace->buf)
		goto fail;

	INIT_LIST_HEAD(&workspace->list);

	return &workspace->list;
fail:
	zstd_free_workspace(&workspace->list);
	return ERR_PTR(-ENOMEM);
}

static int zstd_compress_pages(struct list_head *ws,
		struct address_space *mapping,
		u64 start,
		struct page **pages,
		unsigned long *out_pages,
		unsigned long *total_in,
		unsigned long *total_out)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	ZSTD_CStream *stream;
	int ret = 0;
	int nr_pages = 0;
	struct page *in_page = NULL;  /* The current page to read */
	struct page *out_page = NULL; /* The current page to write to */
	unsigned long tot_in = 0;
	unsigned long tot_out = 0;
	unsigned long len = *total_out;
	const unsigned long nr_dest_pages = *out_pages;
	unsigned long max_out = nr_dest_pages * PAGE_SIZE;
	ZSTD_parameters params = zstd_get_btrfs_parameters(len);

	*out_pages = 0;
	*total_out = 0;
	*total_in = 0;

	/* Initialize the stream */
	stream = ZSTD_initCStream(params, len, workspace->mem,
			workspace->size);
	if (!stream) {
		pr_warn("BTRFS: ZSTD_initCStream failed\n");
		ret = -EIO;
		goto out;
	}

	/* map in the first page of input data */
	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
	workspace->in_buf.src = kmap(in_page);
	workspace->in_buf.pos = 0;
	workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);


	/* Allocate and map in the output buffer */
	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
	if (out_page == NULL) {
		ret = -ENOMEM;
		goto out;
	}
	pages[nr_pages++] = out_page;
	workspace->out_buf.dst = kmap(out_page);
	workspace->out_buf.pos = 0;
	workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);

	while (1) {
		size_t ret2;

		ret2 = ZSTD_compressStream(stream, &workspace->out_buf,
				&workspace->in_buf);
		if (ZSTD_isError(ret2)) {
			pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
					ZSTD_getErrorCode(ret2));
			ret = -EIO;
			goto out;
		}

		/* Check to see if we are making it bigger */
		if (tot_in + workspace->in_buf.pos > 8192 &&
				tot_in + workspace->in_buf.pos <
				tot_out + workspace->out_buf.pos) {
			ret = -E2BIG;
			goto out;
		}

		/* We've reached the end of our output range */
		if (workspace->out_buf.pos >= max_out) {
			tot_out += workspace->out_buf.pos;
			ret = -E2BIG;
			goto out;
		}

		/* Check if we need more output space */
		if (workspace->out_buf.pos == workspace->out_buf.size) {
			tot_out += PAGE_SIZE;
			max_out -= PAGE_SIZE;
			kunmap(out_page);
			if (nr_pages == nr_dest_pages) {
				out_page = NULL;
				ret = -E2BIG;
				goto out;
			}
			out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
			if (out_page == NULL) {
				ret = -ENOMEM;
				goto out;
			}
			pages[nr_pages++] = out_page;
			workspace->out_buf.dst = kmap(out_page);
			workspace->out_buf.pos = 0;
			workspace->out_buf.size = min_t(size_t, max_out,
							PAGE_SIZE);
		}

		/* We've reached the end of the input */
		if (workspace->in_buf.pos >= len) {
			tot_in += workspace->in_buf.pos;
			break;
		}

		/* Check if we need more input */
		if (workspace->in_buf.pos == workspace->in_buf.size) {
			tot_in += PAGE_SIZE;
			kunmap(in_page);
			put_page(in_page);

			start += PAGE_SIZE;
			len -= PAGE_SIZE;
			in_page = find_get_page(mapping, start >> PAGE_SHIFT);
			workspace->in_buf.src = kmap(in_page);
			workspace->in_buf.pos = 0;
			workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
		}
	}
	while (1) {
		size_t ret2;

		ret2 = ZSTD_endStream(stream, &workspace->out_buf);
		if (ZSTD_isError(ret2)) {
			pr_debug("BTRFS: ZSTD_endStream returned %d\n",
					ZSTD_getErrorCode(ret2));
			ret = -EIO;
			goto out;
		}
		if (ret2 == 0) {
			tot_out += workspace->out_buf.pos;
			break;
		}
		if (workspace->out_buf.pos >= max_out) {
			tot_out += workspace->out_buf.pos;
			ret = -E2BIG;
			goto out;
		}

		tot_out += PAGE_SIZE;
		max_out -= PAGE_SIZE;
		kunmap(out_page);
		if (nr_pages == nr_dest_pages) {
			out_page = NULL;
			ret = -E2BIG;
			goto out;
		}
		out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
		if (out_page == NULL) {
			ret = -ENOMEM;
			goto out;
		}
		pages[nr_pages++] = out_page;
		workspace->out_buf.dst = kmap(out_page);
		workspace->out_buf.pos = 0;
		workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
	}

	if (tot_out >= tot_in) {
		ret = -E2BIG;
		goto out;
	}

	ret = 0;
	*total_in = tot_in;
	*total_out = tot_out;
out:
	*out_pages = nr_pages;
	/* Cleanup */
	if (in_page) {
		kunmap(in_page);
		put_page(in_page);
	}
	if (out_page)
		kunmap(out_page);
	return ret;
}

static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	struct page **pages_in = cb->compressed_pages;
	u64 disk_start = cb->start;
	struct bio *orig_bio = cb->orig_bio;
	size_t srclen = cb->compressed_len;
	ZSTD_DStream *stream;
	int ret = 0;
	unsigned long page_in_index = 0;
	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
	unsigned long buf_start;
	unsigned long total_out = 0;

	stream = ZSTD_initDStream(
			ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
	if (!stream) {
		pr_debug("BTRFS: ZSTD_initDStream failed\n");
		ret = -EIO;
		goto done;
	}

	workspace->in_buf.src = kmap(pages_in[page_in_index]);
	workspace->in_buf.pos = 0;
	workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);

	workspace->out_buf.dst = workspace->buf;
	workspace->out_buf.pos = 0;
	workspace->out_buf.size = PAGE_SIZE;

	while (1) {
		size_t ret2;

		ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
				&workspace->in_buf);
		if (ZSTD_isError(ret2)) {
			pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
					ZSTD_getErrorCode(ret2));
			ret = -EIO;
			goto done;
		}
		buf_start = total_out;
		total_out += workspace->out_buf.pos;
		workspace->out_buf.pos = 0;

		ret = btrfs_decompress_buf2page(workspace->out_buf.dst,
				buf_start, total_out, disk_start, orig_bio);
		if (ret == 0)
			break;

		if (workspace->in_buf.pos >= srclen)
			break;

		/* Check if we've hit the end of a frame */
		if (ret2 == 0)
			break;

		if (workspace->in_buf.pos == workspace->in_buf.size) {
			kunmap(pages_in[page_in_index++]);
			if (page_in_index >= total_pages_in) {
				workspace->in_buf.src = NULL;
				ret = -EIO;
				goto done;
			}
			srclen -= PAGE_SIZE;
			workspace->in_buf.src = kmap(pages_in[page_in_index]);
			workspace->in_buf.pos = 0;
			workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
		}
	}
	ret = 0;
	zero_fill_bio(orig_bio);
done:
	if (workspace->in_buf.src)
		kunmap(pages_in[page_in_index]);
	return ret;
}

static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
		struct page *dest_page,
		unsigned long start_byte,
		size_t srclen, size_t destlen)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	ZSTD_DStream *stream;
	int ret = 0;
	size_t ret2;
	unsigned long total_out = 0;
	unsigned long pg_offset = 0;
	char *kaddr;

	stream = ZSTD_initDStream(
			ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
	if (!stream) {
		pr_warn("BTRFS: ZSTD_initDStream failed\n");
		ret = -EIO;
		goto finish;
	}

	destlen = min_t(size_t, destlen, PAGE_SIZE);

	workspace->in_buf.src = data_in;
	workspace->in_buf.pos = 0;
	workspace->in_buf.size = srclen;

	workspace->out_buf.dst = workspace->buf;
	workspace->out_buf.pos = 0;
	workspace->out_buf.size = PAGE_SIZE;

	ret2 = 1;
	while (pg_offset < destlen
	       && workspace->in_buf.pos < workspace->in_buf.size) {
		unsigned long buf_start;
		unsigned long buf_offset;
		unsigned long bytes;

		/* Check if the frame is over and we still need more input */
		if (ret2 == 0) {
			pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
			ret = -EIO;
			goto finish;
		}
		ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
				&workspace->in_buf);
		if (ZSTD_isError(ret2)) {
			pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
					ZSTD_getErrorCode(ret2));
			ret = -EIO;
			goto finish;
		}

		buf_start = total_out;
		total_out += workspace->out_buf.pos;
		workspace->out_buf.pos = 0;

		if (total_out <= start_byte)
			continue;

		if (total_out > start_byte && buf_start < start_byte)
			buf_offset = start_byte - buf_start;
		else
			buf_offset = 0;

		bytes = min_t(unsigned long, destlen - pg_offset,
				workspace->out_buf.size - buf_offset);

		kaddr = kmap_atomic(dest_page);
		memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset,
				bytes);
		kunmap_atomic(kaddr);

		pg_offset += bytes;
	}
	ret = 0;
finish:
	if (pg_offset < destlen) {
		kaddr = kmap_atomic(dest_page);
		memset(kaddr + pg_offset, 0, destlen - pg_offset);
		kunmap_atomic(kaddr);
	}
	return ret;
}

static void zstd_set_level(struct list_head *ws, unsigned int type)
{
}

const struct btrfs_compress_op btrfs_zstd_compress = {
	.alloc_workspace = zstd_alloc_workspace,
	.free_workspace = zstd_free_workspace,
	.compress_pages = zstd_compress_pages,
	.decompress_bio = zstd_decompress_bio,
	.decompress = zstd_decompress,
	.set_level = zstd_set_level,
};
Commit	Line	Data
c1d7c514	1	// SPDX-License-Identifier: GPL-2.0
5c1aab1d NT	2	/*
	3	* Copyright (c) 2016-present, Facebook, Inc.
	4	* All rights reserved.
	5	*
5c1aab1d	6	*/
c1d7c514	7
5c1aab1d NT	8	#include <linux/bio.h>
	9	#include <linux/err.h>
	10	#include <linux/init.h>
	11	#include <linux/kernel.h>
	12	#include <linux/mm.h>
	13	#include <linux/pagemap.h>
	14	#include <linux/refcount.h>
	15	#include <linux/sched.h>
	16	#include <linux/slab.h>
	17	#include <linux/zstd.h>
	18	#include "compression.h"
	19
	20	#define ZSTD_BTRFS_MAX_WINDOWLOG 17
	21	#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
	22	#define ZSTD_BTRFS_DEFAULT_LEVEL 3
	23
	24	static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len)
	25	{
	26	ZSTD_parameters params = ZSTD_getParams(ZSTD_BTRFS_DEFAULT_LEVEL,
	27	src_len, 0);
	28
	29	if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)
	30	params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
	31	WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);
	32	return params;
	33	}
	34
	35	struct workspace {
	36	void *mem;
	37	size_t size;
	38	char *buf;
	39	struct list_head list;
431e9822 DS	40	ZSTD_inBuffer in_buf;
431e9822 DS	41	ZSTD_outBuffer out_buf;
5c1aab1d NT	42	};
	43
	44	static void zstd_free_workspace(struct list_head *ws)
	45	{
	46	struct workspace *workspace = list_entry(ws, struct workspace, list);
	47
	48	kvfree(workspace->mem);
	49	kfree(workspace->buf);
	50	kfree(workspace);
	51	}
	52
	53	static struct list_head *zstd_alloc_workspace(void)
	54	{
	55	ZSTD_parameters params =
	56	zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT);
	57	struct workspace *workspace;
	58
	59	workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
	60	if (!workspace)
	61	return ERR_PTR(-ENOMEM);
	62
	63	workspace->size = max_t(size_t,
	64	ZSTD_CStreamWorkspaceBound(params.cParams),
	65	ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
	66	workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
	67	workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	68	if (!workspace->mem \|\| !workspace->buf)
	69	goto fail;
	70
	71	INIT_LIST_HEAD(&workspace->list);
	72
	73	return &workspace->list;
	74	fail:
	75	zstd_free_workspace(&workspace->list);
	76	return ERR_PTR(-ENOMEM);
	77	}
	78
	79	static int zstd_compress_pages(struct list_head *ws,
	80	struct address_space *mapping,
	81	u64 start,
	82	struct page **pages,
	83	unsigned long *out_pages,
	84	unsigned long *total_in,
	85	unsigned long *total_out)
	86	{
	87	struct workspace *workspace = list_entry(ws, struct workspace, list);
	88	ZSTD_CStream *stream;
	89	int ret = 0;
	90	int nr_pages = 0;
	91	struct page in_page = NULL; / The current page to read */
	92	struct page out_page = NULL; / The current page to write to */
5c1aab1d NT	93	unsigned long tot_in = 0;
	94	unsigned long tot_out = 0;
	95	unsigned long len = *total_out;
	96	const unsigned long nr_dest_pages = *out_pages;
	97	unsigned long max_out = nr_dest_pages * PAGE_SIZE;
	98	ZSTD_parameters params = zstd_get_btrfs_parameters(len);
	99
	100	*out_pages = 0;
	101	*total_out = 0;
	102	*total_in = 0;
	103
	104	/* Initialize the stream */
	105	stream = ZSTD_initCStream(params, len, workspace->mem,
	106	workspace->size);
	107	if (!stream) {
	108	pr_warn("BTRFS: ZSTD_initCStream failed\n");
	109	ret = -EIO;
	110	goto out;
	111	}
	112
	113	/* map in the first page of input data */
	114	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
431e9822 DS	115	workspace->in_buf.src = kmap(in_page);
	116	workspace->in_buf.pos = 0;
	117	workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
5c1aab1d NT	118
	119
	120	/* Allocate and map in the output buffer */
	121	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	122	if (out_page == NULL) {
	123	ret = -ENOMEM;
	124	goto out;
	125	}
	126	pages[nr_pages++] = out_page;
431e9822 DS	127	workspace->out_buf.dst = kmap(out_page);
	128	workspace->out_buf.pos = 0;
	129	workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
5c1aab1d NT	130
	131	while (1) {
	132	size_t ret2;
	133
431e9822 DS	134	ret2 = ZSTD_compressStream(stream, &workspace->out_buf,
431e9822 DS	135	&workspace->in_buf);
5c1aab1d NT	136	if (ZSTD_isError(ret2)) {
	137	pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
	138	ZSTD_getErrorCode(ret2));
	139	ret = -EIO;
	140	goto out;
	141	}
	142
	143	/* Check to see if we are making it bigger */
431e9822 DS	144	if (tot_in + workspace->in_buf.pos > 8192 &&
	145	tot_in + workspace->in_buf.pos <
	146	tot_out + workspace->out_buf.pos) {
5c1aab1d NT	147	ret = -E2BIG;
	148	goto out;
	149	}
	150
	151	/* We've reached the end of our output range */
431e9822 DS	152	if (workspace->out_buf.pos >= max_out) {
431e9822 DS	153	tot_out += workspace->out_buf.pos;
5c1aab1d NT	154	ret = -E2BIG;
	155	goto out;
	156	}
	157
	158	/* Check if we need more output space */
431e9822	159	if (workspace->out_buf.pos == workspace->out_buf.size) {
5c1aab1d NT	160	tot_out += PAGE_SIZE;
	161	max_out -= PAGE_SIZE;
	162	kunmap(out_page);
	163	if (nr_pages == nr_dest_pages) {
	164	out_page = NULL;
	165	ret = -E2BIG;
	166	goto out;
	167	}
	168	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	169	if (out_page == NULL) {
	170	ret = -ENOMEM;
	171	goto out;
	172	}
	173	pages[nr_pages++] = out_page;
431e9822 DS	174	workspace->out_buf.dst = kmap(out_page);
	175	workspace->out_buf.pos = 0;
	176	workspace->out_buf.size = min_t(size_t, max_out,
	177	PAGE_SIZE);
5c1aab1d NT	178	}
	179
	180	/* We've reached the end of the input */
431e9822 DS	181	if (workspace->in_buf.pos >= len) {
431e9822 DS	182	tot_in += workspace->in_buf.pos;
5c1aab1d NT	183	break;
	184	}
	185
	186	/* Check if we need more input */
431e9822	187	if (workspace->in_buf.pos == workspace->in_buf.size) {
5c1aab1d NT	188	tot_in += PAGE_SIZE;
	189	kunmap(in_page);
	190	put_page(in_page);
	191
	192	start += PAGE_SIZE;
	193	len -= PAGE_SIZE;
	194	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
431e9822 DS	195	workspace->in_buf.src = kmap(in_page);
	196	workspace->in_buf.pos = 0;
	197	workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
5c1aab1d NT	198	}
	199	}
	200	while (1) {
	201	size_t ret2;
	202
431e9822	203	ret2 = ZSTD_endStream(stream, &workspace->out_buf);
5c1aab1d NT	204	if (ZSTD_isError(ret2)) {
	205	pr_debug("BTRFS: ZSTD_endStream returned %d\n",
	206	ZSTD_getErrorCode(ret2));
	207	ret = -EIO;
	208	goto out;
	209	}
	210	if (ret2 == 0) {
431e9822	211	tot_out += workspace->out_buf.pos;
5c1aab1d NT	212	break;
5c1aab1d NT	213	}
431e9822 DS	214	if (workspace->out_buf.pos >= max_out) {
431e9822 DS	215	tot_out += workspace->out_buf.pos;
5c1aab1d NT	216	ret = -E2BIG;
	217	goto out;
	218	}
	219
	220	tot_out += PAGE_SIZE;
	221	max_out -= PAGE_SIZE;
	222	kunmap(out_page);
	223	if (nr_pages == nr_dest_pages) {
	224	out_page = NULL;
	225	ret = -E2BIG;
	226	goto out;
	227	}
	228	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	229	if (out_page == NULL) {
	230	ret = -ENOMEM;
	231	goto out;
	232	}
	233	pages[nr_pages++] = out_page;
431e9822 DS	234	workspace->out_buf.dst = kmap(out_page);
	235	workspace->out_buf.pos = 0;
	236	workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
5c1aab1d NT	237	}
	238
	239	if (tot_out >= tot_in) {
	240	ret = -E2BIG;
	241	goto out;
	242	}
	243
	244	ret = 0;
	245	*total_in = tot_in;
	246	*total_out = tot_out;
	247	out:
	248	*out_pages = nr_pages;
	249	/* Cleanup */
	250	if (in_page) {
	251	kunmap(in_page);
	252	put_page(in_page);
	253	}
	254	if (out_page)
	255	kunmap(out_page);
	256	return ret;
	257	}
	258
	259	static int zstd_decompress_bio(struct list_head ws, struct compressed_bio cb)
	260	{
	261	struct workspace *workspace = list_entry(ws, struct workspace, list);
	262	struct page **pages_in = cb->compressed_pages;
	263	u64 disk_start = cb->start;
	264	struct bio *orig_bio = cb->orig_bio;
	265	size_t srclen = cb->compressed_len;
	266	ZSTD_DStream *stream;
	267	int ret = 0;
	268	unsigned long page_in_index = 0;
	269	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
	270	unsigned long buf_start;
	271	unsigned long total_out = 0;
5c1aab1d NT	272
	273	stream = ZSTD_initDStream(
	274	ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
	275	if (!stream) {
	276	pr_debug("BTRFS: ZSTD_initDStream failed\n");
	277	ret = -EIO;
	278	goto done;
	279	}
	280
431e9822 DS	281	workspace->in_buf.src = kmap(pages_in[page_in_index]);
	282	workspace->in_buf.pos = 0;
	283	workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
5c1aab1d	284
431e9822 DS	285	workspace->out_buf.dst = workspace->buf;
	286	workspace->out_buf.pos = 0;
	287	workspace->out_buf.size = PAGE_SIZE;
5c1aab1d NT	288
	289	while (1) {
	290	size_t ret2;
	291
431e9822 DS	292	ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
431e9822 DS	293	&workspace->in_buf);
5c1aab1d NT	294	if (ZSTD_isError(ret2)) {
	295	pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
	296	ZSTD_getErrorCode(ret2));
	297	ret = -EIO;
	298	goto done;
	299	}
	300	buf_start = total_out;
431e9822 DS	301	total_out += workspace->out_buf.pos;
431e9822 DS	302	workspace->out_buf.pos = 0;
5c1aab1d	303
431e9822 DS	304	ret = btrfs_decompress_buf2page(workspace->out_buf.dst,
431e9822 DS	305	buf_start, total_out, disk_start, orig_bio);
5c1aab1d NT	306	if (ret == 0)
	307	break;
	308
431e9822	309	if (workspace->in_buf.pos >= srclen)
5c1aab1d NT	310	break;
	311
	312	/* Check if we've hit the end of a frame */
	313	if (ret2 == 0)
	314	break;
	315
431e9822	316	if (workspace->in_buf.pos == workspace->in_buf.size) {
5c1aab1d NT	317	kunmap(pages_in[page_in_index++]);
5c1aab1d NT	318	if (page_in_index >= total_pages_in) {
431e9822	319	workspace->in_buf.src = NULL;
5c1aab1d NT	320	ret = -EIO;
	321	goto done;
	322	}
	323	srclen -= PAGE_SIZE;
431e9822 DS	324	workspace->in_buf.src = kmap(pages_in[page_in_index]);
	325	workspace->in_buf.pos = 0;
	326	workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
5c1aab1d NT	327	}
	328	}
	329	ret = 0;
	330	zero_fill_bio(orig_bio);
	331	done:
431e9822	332	if (workspace->in_buf.src)
5c1aab1d NT	333	kunmap(pages_in[page_in_index]);
	334	return ret;
	335	}
	336
	337	static int zstd_decompress(struct list_head ws, unsigned char data_in,
	338	struct page *dest_page,
	339	unsigned long start_byte,
	340	size_t srclen, size_t destlen)
	341	{
	342	struct workspace *workspace = list_entry(ws, struct workspace, list);
	343	ZSTD_DStream *stream;
	344	int ret = 0;
	345	size_t ret2;
5c1aab1d NT	346	unsigned long total_out = 0;
	347	unsigned long pg_offset = 0;
	348	char *kaddr;
	349
	350	stream = ZSTD_initDStream(
	351	ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
	352	if (!stream) {
	353	pr_warn("BTRFS: ZSTD_initDStream failed\n");
	354	ret = -EIO;
	355	goto finish;
	356	}
	357
	358	destlen = min_t(size_t, destlen, PAGE_SIZE);
	359
431e9822 DS	360	workspace->in_buf.src = data_in;
	361	workspace->in_buf.pos = 0;
	362	workspace->in_buf.size = srclen;
5c1aab1d	363
431e9822 DS	364	workspace->out_buf.dst = workspace->buf;
	365	workspace->out_buf.pos = 0;
	366	workspace->out_buf.size = PAGE_SIZE;
5c1aab1d NT	367
5c1aab1d NT	368	ret2 = 1;
431e9822 DS	369	while (pg_offset < destlen
431e9822 DS	370	&& workspace->in_buf.pos < workspace->in_buf.size) {
5c1aab1d NT	371	unsigned long buf_start;
	372	unsigned long buf_offset;
	373	unsigned long bytes;
	374
	375	/* Check if the frame is over and we still need more input */
	376	if (ret2 == 0) {
	377	pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
	378	ret = -EIO;
	379	goto finish;
	380	}
431e9822 DS	381	ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
431e9822 DS	382	&workspace->in_buf);
5c1aab1d NT	383	if (ZSTD_isError(ret2)) {
	384	pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
	385	ZSTD_getErrorCode(ret2));
	386	ret = -EIO;
	387	goto finish;
	388	}
	389
	390	buf_start = total_out;
431e9822 DS	391	total_out += workspace->out_buf.pos;
431e9822 DS	392	workspace->out_buf.pos = 0;
5c1aab1d NT	393
	394	if (total_out <= start_byte)
	395	continue;
	396
	397	if (total_out > start_byte && buf_start < start_byte)
	398	buf_offset = start_byte - buf_start;
	399	else
	400	buf_offset = 0;
	401
	402	bytes = min_t(unsigned long, destlen - pg_offset,
431e9822	403	workspace->out_buf.size - buf_offset);
5c1aab1d NT	404
5c1aab1d NT	405	kaddr = kmap_atomic(dest_page);
431e9822 DS	406	memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset,
431e9822 DS	407	bytes);
5c1aab1d NT	408	kunmap_atomic(kaddr);
	409
	410	pg_offset += bytes;
	411	}
	412	ret = 0;
	413	finish:
	414	if (pg_offset < destlen) {
	415	kaddr = kmap_atomic(dest_page);
	416	memset(kaddr + pg_offset, 0, destlen - pg_offset);
	417	kunmap_atomic(kaddr);
	418	}
	419	return ret;
	420	}
	421
f51d2b59 DS	422	static void zstd_set_level(struct list_head *ws, unsigned int type)
	423	{
	424	}
	425
5c1aab1d NT	426	const struct btrfs_compress_op btrfs_zstd_compress = {
	427	.alloc_workspace = zstd_alloc_workspace,
	428	.free_workspace = zstd_free_workspace,
	429	.compress_pages = zstd_compress_pages,
	430	.decompress_bio = zstd_decompress_bio,
	431	.decompress = zstd_decompress,
f51d2b59	432	.set_level = zstd_set_level,
5c1aab1d	433	};