summaryrefslogtreecommitdiffstats
path: root/fs/btrfs/zlib.c
blob: 970ff3e35bb345e598854e5767b8c0981bfbb15c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 *
 * Based on jffs2 zlib code:
 * Copyright © 2001-2007 Red Hat, Inc.
 * Created by David Woodhouse <dwmw2@infradead.org>
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/zlib.h>
#include <linux/zutil.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/refcount.h>
#include "compression.h"

struct workspace {
	z_stream strm;
	char *buf;
	struct list_head list;
	int level;
};

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

	kvfree(workspace->strm.workspace);
	kfree(workspace->buf);
	kfree(workspace);
}

static struct list_head *zlib_alloc_workspace(void)
{
	struct workspace *workspace;
	int workspacesize;

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

	workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
			zlib_inflate_workspacesize());
	workspace->strm.workspace = kvmalloc(workspacesize, GFP_KERNEL);
	workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!workspace->strm.workspace || !workspace->buf)
		goto fail;

	INIT_LIST_HEAD(&workspace->list);

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

static int zlib_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;
	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;

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

	if (Z_OK != zlib_deflateInit(&workspace->strm, workspace->level)) {
		pr_warn("BTRFS: deflateInit failed\n");
		ret = -EIO;
		goto out;
	}

	workspace->strm.total_in = 0;
	workspace->strm.total_out = 0;

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

	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
	if (out_page == NULL) {
		ret = -ENOMEM;
		goto out;
	}
	cpage_out = kmap(out_page);
	pages[0] = out_page;
	nr_pages = 1;

	workspace->strm.next_in = data_in;
	workspace->strm.next_out = cpage_out;
	workspace->strm.avail_out = PAGE_SIZE;
	workspace->strm.avail_in = min(len, PAGE_SIZE);

	while (workspace->strm.total_in < len) {
		ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
		if (ret != Z_OK) {
			pr_debug("BTRFS: deflate in loop returned %d\n",
			       ret);
			zlib_deflateEnd(&workspace->strm);
			ret = -EIO;
			goto out;
		}

		/* we're making it bigger, give up */
		if (workspace->strm.total_in > 8192 &&
		    workspace->strm.total_in <
		    workspace->strm.total_out) {
			ret = -E2BIG;
			goto out;
		}
		/* we need another page for writing out.  Test this
		 * before the total_in so we will pull in a new page for
		 * the stream end if required
		 */
		if (workspace->strm.avail_out == 0) {
			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;
			nr_pages++;
			workspace->strm.avail_out = PAGE_SIZE;
			workspace->strm.next_out = cpage_out;
		}
		/* we're all done */
		if (workspace->strm.total_in >= len)
			break;

		/* we've read in a full page, get a new one */
		if (workspace->strm.avail_in == 0) {
			if (workspace->strm.total_out > max_out)
				break;

			bytes_left = len - workspace->strm.total_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);
			workspace->strm.avail_in = min(bytes_left,
							   PAGE_SIZE);
			workspace->strm.next_in = data_in;
		}
	}
	workspace->strm.avail_in = 0;
	ret = zlib_deflate(&workspace->strm, Z_FINISH);
	zlib_deflateEnd(&workspace->strm);

	if (ret != Z_STREAM_END) {
		ret = -EIO;
		goto out;
	}

	if (workspace->strm.total_out >= workspace->strm.total_in) {
		ret = -E2BIG;
		goto out;
	}

	ret = 0;
	*total_out = workspace->strm.total_out;
	*total_in = workspace->strm.total_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 zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	int ret = 0, ret2;
	int wbits = MAX_WBITS;
	char *data_in;
	size_t total_out = 0;
	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;
	struct page **pages_in = cb->compressed_pages;
	u64 disk_start = cb->start;
	struct bio *orig_bio = cb->orig_bio;

	data_in = kmap(pages_in[page_in_index]);
	workspace->strm.next_in = data_in;
	workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
	workspace->strm.total_in = 0;

	workspace->strm.total_out = 0;
	workspace->strm.next_out = workspace->buf;
	workspace->strm.avail_out = PAGE_SIZE;

	/* If it's deflate, and it's got no preset dictionary, then
	   we can tell zlib to skip the adler32 check. */
	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
	    !(((data_in[0]<<8) + data_in[1]) % 31)) {

		wbits = -((data_in[0] >> 4) + 8);
		workspace->strm.next_in += 2;
		workspace->strm.avail_in -= 2;
	}

	if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
		pr_warn("BTRFS: inflateInit failed\n");
		kunmap(pages_in[page_in_index]);
		return -EIO;
	}
	while (workspace->strm.total_in < srclen) {
		ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
		if (ret != Z_OK && ret != Z_STREAM_END)
			break;

		buf_start = total_out;
		total_out = workspace->strm.total_out;

		/* we didn't make progress in this inflate call, we're done */
		if (buf_start == total_out)
			break;

		ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
						 total_out, disk_start,
						 orig_bio);
		if (ret2 == 0) {
			ret = 0;
			goto done;
		}

		workspace->strm.next_out = workspace->buf;
		workspace->strm.avail_out = PAGE_SIZE;

		if (workspace->strm.avail_in == 0) {
			unsigned long tmp;
			kunmap(pages_in[page_in_index]);
			page_in_index++;
			if (page_in_index >= total_pages_in) {
				data_in = NULL;
				break;
			}
			data_in = kmap(pages_in[page_in_index]);
			workspace->strm.next_in = data_in;
			tmp = srclen - workspace->strm.total_in;
			workspace->strm.avail_in = min(tmp,
							   PAGE_SIZE);
		}
	}
	if (ret != Z_STREAM_END)
		ret = -EIO;
	else
		ret = 0;
done:
	zlib_inflateEnd(&workspace->strm);
	if (data_in)
		kunmap(pages_in[page_in_index]);
	if (!ret)
		zero_fill_bio(orig_bio);
	return ret;
}

static int zlib_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);
	int ret = 0;
	int wbits = MAX_WBITS;
	unsigned long bytes_left;
	unsigned long total_out = 0;
	unsigned long pg_offset = 0;
	char *kaddr;

	destlen = min_t(unsigned long, destlen, PAGE_SIZE);
	bytes_left = destlen;

	workspace->strm.next_in = data_in;
	workspace->strm.avail_in = srclen;
	workspace->strm.total_in = 0;

	workspace->strm.next_out = workspace->buf;
	workspace->strm.avail_out = PAGE_SIZE;
	workspace->strm.total_out = 0;
	/* If it's deflate, and it's got no preset dictionary, then
	   we can tell zlib to skip the adler32 check. */
	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
	    !(((data_in[0]<<8) + data_in[1]) % 31)) {

		wbits = -((data_in[0] >> 4) + 8);
		workspace->strm.next_in += 2;
		workspace->strm.avail_in -= 2;
	}

	if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
		pr_warn("BTRFS: inflateInit failed\n");
		return -EIO;
	}

	while (bytes_left > 0) {
		unsigned long buf_start;
		unsigned long buf_offset;
		unsigned long bytes;

		ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
		if (ret != Z_OK && ret != Z_STREAM_END)
			break;

		buf_start = total_out;
		total_out = workspace->strm.total_out;

		if (total_out == buf_start) {
			ret = -EIO;
			break;
		}

		if (total_out <= start_byte)
			goto next;

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

		bytes = min(PAGE_SIZE - pg_offset,
			    PAGE_SIZE - buf_offset);
		bytes = min(bytes, bytes_left);

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

		pg_offset += bytes;
		bytes_left -= bytes;
next:
		workspace->strm.next_out = workspace->buf;
		workspace->strm.avail_out = PAGE_SIZE;
	}

	if (ret != Z_STREAM_END && bytes_left != 0)
		ret = -EIO;
	else
		ret = 0;

	zlib_inflateEnd(&workspace->strm);

	/*
	 * this should only happen if zlib returned fewer bytes than we
	 * expected.  btrfs_get_block is responsible for zeroing from the
	 * end of the inline extent (destlen) to the end of the page
	 */
	if (pg_offset < destlen) {
		kaddr = kmap_atomic(dest_page);
		memset(kaddr + pg_offset, 0, destlen - pg_offset);
		kunmap_atomic(kaddr);
	}
	return ret;
}

static void zlib_set_level(struct list_head *ws, unsigned int type)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	unsigned level = (type & 0xF0) >> 4;

	if (level > 9)
		level = 9;

	workspace->level = level > 0 ? level : 3;
}

const struct btrfs_compress_op btrfs_zlib_compress = {
	.alloc_workspace	= zlib_alloc_workspace,
	.free_workspace		= zlib_free_workspace,
	.compress_pages		= zlib_compress_pages,
	.decompress_bio		= zlib_decompress_bio,
	.decompress		= zlib_decompress,
	.set_level              = zlib_set_level,
};