[linux-block.git] / fs / btrfs / lzo.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 */

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

#define LZO_LEN	4

/*
 * Btrfs LZO compression format
 *
 * Regular and inlined LZO compressed data extents consist of:
 *
 * 1.  Header
 *     Fixed size. LZO_LEN (4) bytes long, LE32.
 *     Records the total size (including the header) of compressed data.
 *
 * 2.  Segment(s)
 *     Variable size. Each segment includes one segment header, followed by data
 *     payload.
 *     One regular LZO compressed extent can have one or more segments.
 *     For inlined LZO compressed extent, only one segment is allowed.
 *     One segment represents at most one page of uncompressed data.
 *
 * 2.1 Segment header
 *     Fixed size. LZO_LEN (4) bytes long, LE32.
 *     Records the total size of the segment (not including the header).
 *     Segment header never crosses page boundary, thus it's possible to
 *     have at most 3 padding zeros at the end of the page.
 *
 * 2.2 Data Payload
 *     Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
 *     which is 4419 for a 4KiB page.
 *
 * Example:
 * Page 1:
 *          0     0x2   0x4   0x6   0x8   0xa   0xc   0xe     0x10
 * 0x0000   |  Header   | SegHdr 01 | Data payload 01 ...     |
 * ...
 * 0x0ff0   | SegHdr  N | Data payload  N     ...          |00|
 *                                                          ^^ padding zeros
 * Page 2:
 * 0x1000   | SegHdr N+1| Data payload N+1 ...                |
 */

struct workspace {
	void *mem;
	void *buf;	/* where decompressed data goes */
	void *cbuf;	/* where compressed data goes */
	struct list_head list;
};

static struct workspace_manager wsm;

static void lzo_init_workspace_manager(void)
{
	btrfs_init_workspace_manager(&wsm, &btrfs_lzo_compress);
}

static void lzo_cleanup_workspace_manager(void)
{
	btrfs_cleanup_workspace_manager(&wsm);
}

static struct list_head *lzo_get_workspace(unsigned int level)
{
	return btrfs_get_workspace(&wsm, level);
}

static void lzo_put_workspace(struct list_head *ws)
{
	btrfs_put_workspace(&wsm, ws);
}

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

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

static struct list_head *lzo_alloc_workspace(unsigned int level)
{
	struct workspace *workspace;

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

	workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
	workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
	workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
	if (!workspace->mem || !workspace->buf || !workspace->cbuf)
		goto fail;

	INIT_LIST_HEAD(&workspace->list);

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

static inline void write_compress_length(char *buf, size_t len)
{
	__le32 dlen;

	dlen = cpu_to_le32(len);
	memcpy(buf, &dlen, LZO_LEN);
}

static inline size_t read_compress_length(const char *buf)
{
	__le32 dlen;

	memcpy(&dlen, buf, LZO_LEN);
	return le32_to_cpu(dlen);
}

static int lzo_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);
	int ret = 0;
	char *data_in;
	char *cpage_out;
	int nr_pages = 0;
	struct page *in_page = NULL;
	struct page *out_page = NULL;
	unsigned long bytes_left;
	unsigned long len = *total_out;
	unsigned long nr_dest_pages = *out_pages;
	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
	size_t in_len;
	size_t out_len;
	char *buf;
	unsigned long tot_in = 0;
	unsigned long tot_out = 0;
	unsigned long pg_bytes_left;
	unsigned long out_offset;
	unsigned long bytes;

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

	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
	data_in = kmap(in_page);

	/*
	 * store the size of all chunks of compressed data in
	 * the first 4 bytes
	 */
	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
	if (out_page == NULL) {
		ret = -ENOMEM;
		goto out;
	}
	cpage_out = kmap(out_page);
	out_offset = LZO_LEN;
	tot_out = LZO_LEN;
	pages[0] = out_page;
	nr_pages = 1;
	pg_bytes_left = PAGE_SIZE - LZO_LEN;

	/* compress at most one page of data each time */
	in_len = min(len, PAGE_SIZE);
	while (tot_in < len) {
		ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
				       &out_len, workspace->mem);
		if (ret != LZO_E_OK) {
			pr_debug("BTRFS: lzo in loop returned %d\n",
			       ret);
			ret = -EIO;
			goto out;
		}

		/* store the size of this chunk of compressed data */
		write_compress_length(cpage_out + out_offset, out_len);
		tot_out += LZO_LEN;
		out_offset += LZO_LEN;
		pg_bytes_left -= LZO_LEN;

		tot_in += in_len;
		tot_out += out_len;

		/* copy bytes from the working buffer into the pages */
		buf = workspace->cbuf;
		while (out_len) {
			bytes = min_t(unsigned long, pg_bytes_left, out_len);

			memcpy(cpage_out + out_offset, buf, bytes);

			out_len -= bytes;
			pg_bytes_left -= bytes;
			buf += bytes;
			out_offset += bytes;

			/*
			 * we need another page for writing out.
			 *
			 * Note if there's less than 4 bytes left, we just
			 * skip to a new page.
			 */
			if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
			    pg_bytes_left == 0) {
				if (pg_bytes_left) {
					memset(cpage_out + out_offset, 0,
					       pg_bytes_left);
					tot_out += pg_bytes_left;
				}

				/* we're done, don't allocate new page */
				if (out_len == 0 && tot_in >= len)
					break;

				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;
				}
				cpage_out = kmap(out_page);
				pages[nr_pages++] = out_page;

				pg_bytes_left = PAGE_SIZE;
				out_offset = 0;
			}
		}

		/* we're making it bigger, give up */
		if (tot_in > 8192 && tot_in < tot_out) {
			ret = -E2BIG;
			goto out;
		}

		/* we're all done */
		if (tot_in >= len)
			break;

		if (tot_out > max_out)
			break;

		bytes_left = len - tot_in;
		kunmap(in_page);
		put_page(in_page);

		start += PAGE_SIZE;
		in_page = find_get_page(mapping, start >> PAGE_SHIFT);
		data_in = kmap(in_page);
		in_len = min(bytes_left, PAGE_SIZE);
	}

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

	/* store the size of all chunks of compressed data */
	cpage_out = kmap(pages[0]);
	write_compress_length(cpage_out, tot_out);

	kunmap(pages[0]);

	ret = 0;
	*total_out = tot_out;
	*total_in = tot_in;
out:
	*out_pages = nr_pages;
	if (out_page)
		kunmap(out_page);

	if (in_page) {
		kunmap(in_page);
		put_page(in_page);
	}

	return ret;
}

static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	int ret = 0, ret2;
	char *data_in;
	unsigned long page_in_index = 0;
	size_t srclen = cb->compressed_len;
	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
	unsigned long buf_start;
	unsigned long buf_offset = 0;
	unsigned long bytes;
	unsigned long working_bytes;
	size_t in_len;
	size_t out_len;
	const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
	unsigned long in_offset;
	unsigned long in_page_bytes_left;
	unsigned long tot_in;
	unsigned long tot_out;
	unsigned long tot_len;
	char *buf;
	bool may_late_unmap, need_unmap;
	struct page **pages_in = cb->compressed_pages;
	u64 disk_start = cb->start;
	struct bio *orig_bio = cb->orig_bio;

	data_in = kmap(pages_in[0]);
	tot_len = read_compress_length(data_in);
	/*
	 * Compressed data header check.
	 *
	 * The real compressed size can't exceed the maximum extent length, and
	 * all pages should be used (whole unused page with just the segment
	 * header is not possible).  If this happens it means the compressed
	 * extent is corrupted.
	 */
	if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
	    tot_len < srclen - PAGE_SIZE) {
		ret = -EUCLEAN;
		goto done;
	}

	tot_in = LZO_LEN;
	in_offset = LZO_LEN;
	in_page_bytes_left = PAGE_SIZE - LZO_LEN;

	tot_out = 0;

	while (tot_in < tot_len) {
		in_len = read_compress_length(data_in + in_offset);
		in_page_bytes_left -= LZO_LEN;
		in_offset += LZO_LEN;
		tot_in += LZO_LEN;

		/*
		 * Segment header check.
		 *
		 * The segment length must not exceed the maximum LZO
		 * compression size, nor the total compressed size.
		 */
		if (in_len > max_segment_len || tot_in + in_len > tot_len) {
			ret = -EUCLEAN;
			goto done;
		}

		tot_in += in_len;
		working_bytes = in_len;
		may_late_unmap = need_unmap = false;

		/* fast path: avoid using the working buffer */
		if (in_page_bytes_left >= in_len) {
			buf = data_in + in_offset;
			bytes = in_len;
			may_late_unmap = true;
			goto cont;
		}

		/* copy bytes from the pages into the working buffer */
		buf = workspace->cbuf;
		buf_offset = 0;
		while (working_bytes) {
			bytes = min(working_bytes, in_page_bytes_left);

			memcpy(buf + buf_offset, data_in + in_offset, bytes);
			buf_offset += bytes;
cont:
			working_bytes -= bytes;
			in_page_bytes_left -= bytes;
			in_offset += bytes;

			/* check if we need to pick another page */
			if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
			    || in_page_bytes_left == 0) {
				tot_in += in_page_bytes_left;

				if (working_bytes == 0 && tot_in >= tot_len)
					break;

				if (page_in_index + 1 >= total_pages_in) {
					ret = -EIO;
					goto done;
				}

				if (may_late_unmap)
					need_unmap = true;
				else
					kunmap(pages_in[page_in_index]);

				data_in = kmap(pages_in[++page_in_index]);

				in_page_bytes_left = PAGE_SIZE;
				in_offset = 0;
			}
		}

		out_len = max_segment_len;
		ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
					    &out_len);
		if (need_unmap)
			kunmap(pages_in[page_in_index - 1]);
		if (ret != LZO_E_OK) {
			pr_warn("BTRFS: decompress failed\n");
			ret = -EIO;
			break;
		}

		buf_start = tot_out;
		tot_out += out_len;

		ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
						 tot_out, disk_start, orig_bio);
		if (ret2 == 0)
			break;
	}
done:
	kunmap(pages_in[page_in_index]);
	if (!ret)
		zero_fill_bio(orig_bio);
	return ret;
}

static int lzo_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);
	size_t in_len;
	size_t out_len;
	size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
	int ret = 0;
	char *kaddr;
	unsigned long bytes;

	if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
		return -EUCLEAN;

	in_len = read_compress_length(data_in);
	if (in_len != srclen)
		return -EUCLEAN;
	data_in += LZO_LEN;

	in_len = read_compress_length(data_in);
	if (in_len != srclen - LZO_LEN * 2) {
		ret = -EUCLEAN;
		goto out;
	}
	data_in += LZO_LEN;

	out_len = PAGE_SIZE;
	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
	if (ret != LZO_E_OK) {
		pr_warn("BTRFS: decompress failed!\n");
		ret = -EIO;
		goto out;
	}

	if (out_len < start_byte) {
		ret = -EIO;
		goto out;
	}

	/*
	 * the caller is already checking against PAGE_SIZE, but lets
	 * move this check closer to the memcpy/memset
	 */
	destlen = min_t(unsigned long, destlen, PAGE_SIZE);
	bytes = min_t(unsigned long, destlen, out_len - start_byte);

	kaddr = kmap_atomic(dest_page);
	memcpy(kaddr, workspace->buf + start_byte, bytes);

	/*
	 * btrfs_getblock is doing a zero on the tail of the page too,
	 * but this will cover anything missing from the decompressed
	 * data.
	 */
	if (bytes < destlen)
		memset(kaddr+bytes, 0, destlen-bytes);
	kunmap_atomic(kaddr);
out:
	return ret;
}

static unsigned int lzo_set_level(unsigned int level)
{
	return 0;
}

const struct btrfs_compress_op btrfs_lzo_compress = {
	.init_workspace_manager	= lzo_init_workspace_manager,
	.cleanup_workspace_manager = lzo_cleanup_workspace_manager,
	.get_workspace		= lzo_get_workspace,
	.put_workspace		= lzo_put_workspace,
	.alloc_workspace	= lzo_alloc_workspace,
	.free_workspace		= lzo_free_workspace,
	.compress_pages		= lzo_compress_pages,
	.decompress_bio		= lzo_decompress_bio,
	.decompress		= lzo_decompress,
	.set_level		= lzo_set_level,
};
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Copyright (C) 2008 Oracle. All rights reserved.
	4	*/
	5
	6	#include <linux/kernel.h>
	7	#include <linux/slab.h>
	8	#include <linux/mm.h>
	9	#include <linux/init.h>
	10	#include <linux/err.h>
	11	#include <linux/sched.h>
	12	#include <linux/pagemap.h>
	13	#include <linux/bio.h>
	14	#include <linux/lzo.h>
	15	#include <linux/refcount.h>
	16	#include "compression.h"
	17
	18	#define LZO_LEN 4
	19
	20	/*
	21	* Btrfs LZO compression format
	22	*
	23	* Regular and inlined LZO compressed data extents consist of:
	24	*
	25	* 1. Header
	26	* Fixed size. LZO_LEN (4) bytes long, LE32.
	27	* Records the total size (including the header) of compressed data.
	28	*
	29	* 2. Segment(s)
	30	* Variable size. Each segment includes one segment header, followed by data
	31	* payload.
	32	* One regular LZO compressed extent can have one or more segments.
	33	* For inlined LZO compressed extent, only one segment is allowed.
	34	* One segment represents at most one page of uncompressed data.
	35	*
	36	* 2.1 Segment header
	37	* Fixed size. LZO_LEN (4) bytes long, LE32.
	38	* Records the total size of the segment (not including the header).
	39	* Segment header never crosses page boundary, thus it's possible to
	40	* have at most 3 padding zeros at the end of the page.
	41	*
	42	* 2.2 Data Payload
	43	* Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
	44	* which is 4419 for a 4KiB page.
	45	*
	46	* Example:
	47	* Page 1:
	48	* 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10
	49	* 0x0000 \| Header \| SegHdr 01 \| Data payload 01 ... \|
	50	* ...
	51	* 0x0ff0 \| SegHdr N \| Data payload N ... \|00\|
	52	* ^^ padding zeros
	53	* Page 2:
	54	* 0x1000 \| SegHdr N+1\| Data payload N+1 ... \|
	55	*/
	56
	57	struct workspace {
	58	void *mem;
	59	void buf; / where decompressed data goes */
	60	void cbuf; / where compressed data goes */
	61	struct list_head list;
	62	};
	63
	64	static struct workspace_manager wsm;
	65
	66	static void lzo_init_workspace_manager(void)
	67	{
	68	btrfs_init_workspace_manager(&wsm, &btrfs_lzo_compress);
	69	}
	70
	71	static void lzo_cleanup_workspace_manager(void)
	72	{
	73	btrfs_cleanup_workspace_manager(&wsm);
	74	}
	75
	76	static struct list_head *lzo_get_workspace(unsigned int level)
	77	{
	78	return btrfs_get_workspace(&wsm, level);
	79	}
	80
	81	static void lzo_put_workspace(struct list_head *ws)
	82	{
	83	btrfs_put_workspace(&wsm, ws);
	84	}
	85
	86	static void lzo_free_workspace(struct list_head *ws)
	87	{
	88	struct workspace *workspace = list_entry(ws, struct workspace, list);
	89
	90	kvfree(workspace->buf);
	91	kvfree(workspace->cbuf);
	92	kvfree(workspace->mem);
	93	kfree(workspace);
	94	}
	95
	96	static struct list_head *lzo_alloc_workspace(unsigned int level)
	97	{
	98	struct workspace *workspace;
	99
	100	workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
	101	if (!workspace)
	102	return ERR_PTR(-ENOMEM);
	103
	104	workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
	105	workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
	106	workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
	107	if (!workspace->mem \|\| !workspace->buf \|\| !workspace->cbuf)
	108	goto fail;
	109
	110	INIT_LIST_HEAD(&workspace->list);
	111
	112	return &workspace->list;
	113	fail:
	114	lzo_free_workspace(&workspace->list);
	115	return ERR_PTR(-ENOMEM);
	116	}
	117
	118	static inline void write_compress_length(char *buf, size_t len)
	119	{
	120	__le32 dlen;
	121
	122	dlen = cpu_to_le32(len);
	123	memcpy(buf, &dlen, LZO_LEN);
	124	}
	125
	126	static inline size_t read_compress_length(const char *buf)
	127	{
	128	__le32 dlen;
	129
	130	memcpy(&dlen, buf, LZO_LEN);
	131	return le32_to_cpu(dlen);
	132	}
	133
	134	static int lzo_compress_pages(struct list_head *ws,
	135	struct address_space *mapping,
	136	u64 start,
	137	struct page **pages,
	138	unsigned long *out_pages,
	139	unsigned long *total_in,
	140	unsigned long *total_out)
	141	{
	142	struct workspace *workspace = list_entry(ws, struct workspace, list);
	143	int ret = 0;
	144	char *data_in;
	145	char *cpage_out;
	146	int nr_pages = 0;
	147	struct page *in_page = NULL;
	148	struct page *out_page = NULL;
	149	unsigned long bytes_left;
	150	unsigned long len = *total_out;
	151	unsigned long nr_dest_pages = *out_pages;
	152	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
	153	size_t in_len;
	154	size_t out_len;
	155	char *buf;
	156	unsigned long tot_in = 0;
	157	unsigned long tot_out = 0;
	158	unsigned long pg_bytes_left;
	159	unsigned long out_offset;
	160	unsigned long bytes;
	161
	162	*out_pages = 0;
	163	*total_out = 0;
	164	*total_in = 0;
	165
	166	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
	167	data_in = kmap(in_page);
	168
	169	/*
	170	* store the size of all chunks of compressed data in
	171	* the first 4 bytes
	172	*/
	173	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	174	if (out_page == NULL) {
	175	ret = -ENOMEM;
	176	goto out;
	177	}
	178	cpage_out = kmap(out_page);
	179	out_offset = LZO_LEN;
	180	tot_out = LZO_LEN;
	181	pages[0] = out_page;
	182	nr_pages = 1;
	183	pg_bytes_left = PAGE_SIZE - LZO_LEN;
	184
	185	/* compress at most one page of data each time */
	186	in_len = min(len, PAGE_SIZE);
	187	while (tot_in < len) {
	188	ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
	189	&out_len, workspace->mem);
	190	if (ret != LZO_E_OK) {
	191	pr_debug("BTRFS: lzo in loop returned %d\n",
	192	ret);
	193	ret = -EIO;
	194	goto out;
	195	}
	196
	197	/* store the size of this chunk of compressed data */
	198	write_compress_length(cpage_out + out_offset, out_len);
	199	tot_out += LZO_LEN;
	200	out_offset += LZO_LEN;
	201	pg_bytes_left -= LZO_LEN;
	202
	203	tot_in += in_len;
	204	tot_out += out_len;
	205
	206	/* copy bytes from the working buffer into the pages */
	207	buf = workspace->cbuf;
	208	while (out_len) {
	209	bytes = min_t(unsigned long, pg_bytes_left, out_len);
	210
	211	memcpy(cpage_out + out_offset, buf, bytes);
	212
	213	out_len -= bytes;
	214	pg_bytes_left -= bytes;
	215	buf += bytes;
	216	out_offset += bytes;
	217
	218	/*
	219	* we need another page for writing out.
	220	*
	221	* Note if there's less than 4 bytes left, we just
	222	* skip to a new page.
	223	*/
	224	if ((out_len == 0 && pg_bytes_left < LZO_LEN) \|\|
	225	pg_bytes_left == 0) {
	226	if (pg_bytes_left) {
	227	memset(cpage_out + out_offset, 0,
	228	pg_bytes_left);
	229	tot_out += pg_bytes_left;
	230	}
	231
	232	/* we're done, don't allocate new page */
	233	if (out_len == 0 && tot_in >= len)
	234	break;
	235
	236	kunmap(out_page);
	237	if (nr_pages == nr_dest_pages) {
	238	out_page = NULL;
	239	ret = -E2BIG;
	240	goto out;
	241	}
	242
	243	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	244	if (out_page == NULL) {
	245	ret = -ENOMEM;
	246	goto out;
	247	}
	248	cpage_out = kmap(out_page);
	249	pages[nr_pages++] = out_page;
	250
	251	pg_bytes_left = PAGE_SIZE;
	252	out_offset = 0;
	253	}
	254	}
	255
	256	/* we're making it bigger, give up */
	257	if (tot_in > 8192 && tot_in < tot_out) {
	258	ret = -E2BIG;
	259	goto out;
	260	}
	261
	262	/* we're all done */
	263	if (tot_in >= len)
	264	break;
	265
	266	if (tot_out > max_out)
	267	break;
	268
	269	bytes_left = len - tot_in;
	270	kunmap(in_page);
	271	put_page(in_page);
	272
	273	start += PAGE_SIZE;
	274	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
	275	data_in = kmap(in_page);
	276	in_len = min(bytes_left, PAGE_SIZE);
	277	}
	278
	279	if (tot_out >= tot_in) {
	280	ret = -E2BIG;
	281	goto out;
	282	}
	283
	284	/* store the size of all chunks of compressed data */
	285	cpage_out = kmap(pages[0]);
	286	write_compress_length(cpage_out, tot_out);
	287
	288	kunmap(pages[0]);
	289
	290	ret = 0;
	291	*total_out = tot_out;
	292	*total_in = tot_in;
	293	out:
	294	*out_pages = nr_pages;
	295	if (out_page)
	296	kunmap(out_page);
	297
	298	if (in_page) {
	299	kunmap(in_page);
	300	put_page(in_page);
	301	}
	302
	303	return ret;
	304	}
	305
	306	static int lzo_decompress_bio(struct list_head ws, struct compressed_bio cb)
	307	{
	308	struct workspace *workspace = list_entry(ws, struct workspace, list);
	309	int ret = 0, ret2;
	310	char *data_in;
	311	unsigned long page_in_index = 0;
	312	size_t srclen = cb->compressed_len;
	313	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
	314	unsigned long buf_start;
	315	unsigned long buf_offset = 0;
	316	unsigned long bytes;
	317	unsigned long working_bytes;
	318	size_t in_len;
	319	size_t out_len;
	320	const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
	321	unsigned long in_offset;
	322	unsigned long in_page_bytes_left;
	323	unsigned long tot_in;
	324	unsigned long tot_out;
	325	unsigned long tot_len;
	326	char *buf;
	327	bool may_late_unmap, need_unmap;
	328	struct page **pages_in = cb->compressed_pages;
	329	u64 disk_start = cb->start;
	330	struct bio *orig_bio = cb->orig_bio;
	331
	332	data_in = kmap(pages_in[0]);
	333	tot_len = read_compress_length(data_in);
	334	/*
	335	* Compressed data header check.
	336	*
	337	* The real compressed size can't exceed the maximum extent length, and
	338	* all pages should be used (whole unused page with just the segment
	339	* header is not possible). If this happens it means the compressed
	340	* extent is corrupted.
	341	*/
	342	if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) \|\|
	343	tot_len < srclen - PAGE_SIZE) {
	344	ret = -EUCLEAN;
	345	goto done;
	346	}
	347
	348	tot_in = LZO_LEN;
	349	in_offset = LZO_LEN;
	350	in_page_bytes_left = PAGE_SIZE - LZO_LEN;
	351
	352	tot_out = 0;
	353
	354	while (tot_in < tot_len) {
	355	in_len = read_compress_length(data_in + in_offset);
	356	in_page_bytes_left -= LZO_LEN;
	357	in_offset += LZO_LEN;
	358	tot_in += LZO_LEN;
	359
	360	/*
	361	* Segment header check.
	362	*
	363	* The segment length must not exceed the maximum LZO
	364	* compression size, nor the total compressed size.
	365	*/
	366	if (in_len > max_segment_len \|\| tot_in + in_len > tot_len) {
	367	ret = -EUCLEAN;
	368	goto done;
	369	}
	370
	371	tot_in += in_len;
	372	working_bytes = in_len;
	373	may_late_unmap = need_unmap = false;
	374
	375	/* fast path: avoid using the working buffer */
	376	if (in_page_bytes_left >= in_len) {
	377	buf = data_in + in_offset;
	378	bytes = in_len;
	379	may_late_unmap = true;
	380	goto cont;
	381	}
	382
	383	/* copy bytes from the pages into the working buffer */
	384	buf = workspace->cbuf;
	385	buf_offset = 0;
	386	while (working_bytes) {
	387	bytes = min(working_bytes, in_page_bytes_left);
	388
	389	memcpy(buf + buf_offset, data_in + in_offset, bytes);
	390	buf_offset += bytes;
	391	cont:
	392	working_bytes -= bytes;
	393	in_page_bytes_left -= bytes;
	394	in_offset += bytes;
	395
	396	/* check if we need to pick another page */
	397	if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
	398	\|\| in_page_bytes_left == 0) {
	399	tot_in += in_page_bytes_left;
	400
	401	if (working_bytes == 0 && tot_in >= tot_len)
	402	break;
	403
	404	if (page_in_index + 1 >= total_pages_in) {
	405	ret = -EIO;
	406	goto done;
	407	}
	408
	409	if (may_late_unmap)
	410	need_unmap = true;
	411	else
	412	kunmap(pages_in[page_in_index]);
	413
	414	data_in = kmap(pages_in[++page_in_index]);
	415
	416	in_page_bytes_left = PAGE_SIZE;
	417	in_offset = 0;
	418	}
	419	}
	420
	421	out_len = max_segment_len;
	422	ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
	423	&out_len);
	424	if (need_unmap)
	425	kunmap(pages_in[page_in_index - 1]);
	426	if (ret != LZO_E_OK) {
	427	pr_warn("BTRFS: decompress failed\n");
	428	ret = -EIO;
	429	break;
	430	}
	431
	432	buf_start = tot_out;
	433	tot_out += out_len;
	434
	435	ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
	436	tot_out, disk_start, orig_bio);
	437	if (ret2 == 0)
	438	break;
	439	}
	440	done:
	441	kunmap(pages_in[page_in_index]);
	442	if (!ret)
	443	zero_fill_bio(orig_bio);
	444	return ret;
	445	}
	446
	447	static int lzo_decompress(struct list_head ws, unsigned char data_in,
	448	struct page *dest_page,
	449	unsigned long start_byte,
	450	size_t srclen, size_t destlen)
	451	{
	452	struct workspace *workspace = list_entry(ws, struct workspace, list);
	453	size_t in_len;
	454	size_t out_len;
	455	size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
	456	int ret = 0;
	457	char *kaddr;
	458	unsigned long bytes;
	459
	460	if (srclen < LZO_LEN \|\| srclen > max_segment_len + LZO_LEN * 2)
	461	return -EUCLEAN;
	462
	463	in_len = read_compress_length(data_in);
	464	if (in_len != srclen)
	465	return -EUCLEAN;
	466	data_in += LZO_LEN;
	467
	468	in_len = read_compress_length(data_in);
	469	if (in_len != srclen - LZO_LEN * 2) {
	470	ret = -EUCLEAN;
	471	goto out;
	472	}
	473	data_in += LZO_LEN;
	474
	475	out_len = PAGE_SIZE;
	476	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
	477	if (ret != LZO_E_OK) {
	478	pr_warn("BTRFS: decompress failed!\n");
	479	ret = -EIO;
	480	goto out;
	481	}
	482
	483	if (out_len < start_byte) {
	484	ret = -EIO;
	485	goto out;
	486	}
	487
	488	/*
	489	* the caller is already checking against PAGE_SIZE, but lets
	490	* move this check closer to the memcpy/memset
	491	*/
	492	destlen = min_t(unsigned long, destlen, PAGE_SIZE);
	493	bytes = min_t(unsigned long, destlen, out_len - start_byte);
	494
	495	kaddr = kmap_atomic(dest_page);
	496	memcpy(kaddr, workspace->buf + start_byte, bytes);
	497
	498	/*
	499	* btrfs_getblock is doing a zero on the tail of the page too,
	500	* but this will cover anything missing from the decompressed
	501	* data.
	502	*/
	503	if (bytes < destlen)
	504	memset(kaddr+bytes, 0, destlen-bytes);
	505	kunmap_atomic(kaddr);
	506	out:
	507	return ret;
	508	}
	509
	510	static unsigned int lzo_set_level(unsigned int level)
	511	{
	512	return 0;
	513	}
	514
	515	const struct btrfs_compress_op btrfs_lzo_compress = {
	516	.init_workspace_manager = lzo_init_workspace_manager,
	517	.cleanup_workspace_manager = lzo_cleanup_workspace_manager,
	518	.get_workspace = lzo_get_workspace,
	519	.put_workspace = lzo_put_workspace,
	520	.alloc_workspace = lzo_alloc_workspace,
	521	.free_workspace = lzo_free_workspace,
	522	.compress_pages = lzo_compress_pages,
	523	.decompress_bio = lzo_decompress_bio,
	524	.decompress = lzo_decompress,
	525	.set_level = lzo_set_level,
	526	};