summaryrefslogtreecommitdiff
path: root/fs/erofs/decompressor_lzma.c
blob: 5e59b3f523eb62f85e1061f51dfb1d000557b2ca (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
// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/xz.h>
#include <linux/module.h>
#include "compress.h"

struct z_erofs_lzma {
	struct z_erofs_lzma *next;
	struct xz_dec_microlzma *state;
	struct xz_buf buf;
	u8 bounce[PAGE_SIZE];
};

/* considering the LZMA performance, no need to use a lockless list for now */
static DEFINE_SPINLOCK(z_erofs_lzma_lock);
static unsigned int z_erofs_lzma_max_dictsize;
static unsigned int z_erofs_lzma_nstrms, z_erofs_lzma_avail_strms;
static struct z_erofs_lzma *z_erofs_lzma_head;
static DECLARE_WAIT_QUEUE_HEAD(z_erofs_lzma_wq);

module_param_named(lzma_streams, z_erofs_lzma_nstrms, uint, 0444);

void z_erofs_lzma_exit(void)
{
	/* there should be no running fs instance */
	while (z_erofs_lzma_avail_strms) {
		struct z_erofs_lzma *strm;

		spin_lock(&z_erofs_lzma_lock);
		strm = z_erofs_lzma_head;
		if (!strm) {
			spin_unlock(&z_erofs_lzma_lock);
			DBG_BUGON(1);
			return;
		}
		z_erofs_lzma_head = NULL;
		spin_unlock(&z_erofs_lzma_lock);

		while (strm) {
			struct z_erofs_lzma *n = strm->next;

			if (strm->state)
				xz_dec_microlzma_end(strm->state);
			kfree(strm);
			--z_erofs_lzma_avail_strms;
			strm = n;
		}
	}
}

int z_erofs_lzma_init(void)
{
	unsigned int i;

	/* by default, use # of possible CPUs instead */
	if (!z_erofs_lzma_nstrms)
		z_erofs_lzma_nstrms = num_possible_cpus();

	for (i = 0; i < z_erofs_lzma_nstrms; ++i) {
		struct z_erofs_lzma *strm = kzalloc(sizeof(*strm), GFP_KERNEL);

		if (!strm) {
			z_erofs_lzma_exit();
			return -ENOMEM;
		}
		spin_lock(&z_erofs_lzma_lock);
		strm->next = z_erofs_lzma_head;
		z_erofs_lzma_head = strm;
		spin_unlock(&z_erofs_lzma_lock);
		++z_erofs_lzma_avail_strms;
	}
	return 0;
}

int z_erofs_load_lzma_config(struct super_block *sb,
			     struct erofs_super_block *dsb,
			     struct z_erofs_lzma_cfgs *lzma, int size)
{
	static DEFINE_MUTEX(lzma_resize_mutex);
	unsigned int dict_size, i;
	struct z_erofs_lzma *strm, *head = NULL;
	int err;

	if (!lzma || size < sizeof(struct z_erofs_lzma_cfgs)) {
		erofs_err(sb, "invalid lzma cfgs, size=%u", size);
		return -EINVAL;
	}
	if (lzma->format) {
		erofs_err(sb, "unidentified lzma format %x, please check kernel version",
			  le16_to_cpu(lzma->format));
		return -EINVAL;
	}
	dict_size = le32_to_cpu(lzma->dict_size);
	if (dict_size > Z_EROFS_LZMA_MAX_DICT_SIZE || dict_size < 4096) {
		erofs_err(sb, "unsupported lzma dictionary size %u",
			  dict_size);
		return -EINVAL;
	}

	erofs_info(sb, "EXPERIMENTAL MicroLZMA in use. Use at your own risk!");

	/* in case 2 z_erofs_load_lzma_config() race to avoid deadlock */
	mutex_lock(&lzma_resize_mutex);

	if (z_erofs_lzma_max_dictsize >= dict_size) {
		mutex_unlock(&lzma_resize_mutex);
		return 0;
	}

	/* 1. collect/isolate all streams for the following check */
	for (i = 0; i < z_erofs_lzma_avail_strms; ++i) {
		struct z_erofs_lzma *last;

again:
		spin_lock(&z_erofs_lzma_lock);
		strm = z_erofs_lzma_head;
		if (!strm) {
			spin_unlock(&z_erofs_lzma_lock);
			wait_event(z_erofs_lzma_wq,
				   READ_ONCE(z_erofs_lzma_head));
			goto again;
		}
		z_erofs_lzma_head = NULL;
		spin_unlock(&z_erofs_lzma_lock);

		for (last = strm; last->next; last = last->next)
			++i;
		last->next = head;
		head = strm;
	}

	err = 0;
	/* 2. walk each isolated stream and grow max dict_size if needed */
	for (strm = head; strm; strm = strm->next) {
		if (strm->state)
			xz_dec_microlzma_end(strm->state);
		strm->state = xz_dec_microlzma_alloc(XZ_PREALLOC, dict_size);
		if (!strm->state)
			err = -ENOMEM;
	}

	/* 3. push back all to the global list and update max dict_size */
	spin_lock(&z_erofs_lzma_lock);
	DBG_BUGON(z_erofs_lzma_head);
	z_erofs_lzma_head = head;
	spin_unlock(&z_erofs_lzma_lock);
	wake_up_all(&z_erofs_lzma_wq);

	z_erofs_lzma_max_dictsize = dict_size;
	mutex_unlock(&lzma_resize_mutex);
	return err;
}

int z_erofs_lzma_decompress(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 nrpages_in =
		PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
	unsigned int inlen, outlen, pageofs;
	struct z_erofs_lzma *strm;
	u8 *kin;
	bool bounced = false;
	int no, ni, j, err = 0;

	/* 1. get the exact LZMA compressed size */
	kin = kmap(*rq->in);
	err = z_erofs_fixup_insize(rq, kin + rq->pageofs_in,
				   min_t(unsigned int, rq->inputsize,
					 EROFS_BLKSIZ - rq->pageofs_in));
	if (err) {
		kunmap(*rq->in);
		return err;
	}

	/* 2. get an available lzma context */
again:
	spin_lock(&z_erofs_lzma_lock);
	strm = z_erofs_lzma_head;
	if (!strm) {
		spin_unlock(&z_erofs_lzma_lock);
		wait_event(z_erofs_lzma_wq, READ_ONCE(z_erofs_lzma_head));
		goto again;
	}
	z_erofs_lzma_head = strm->next;
	spin_unlock(&z_erofs_lzma_lock);

	/* 3. multi-call decompress */
	inlen = rq->inputsize;
	outlen = rq->outputsize;
	xz_dec_microlzma_reset(strm->state, inlen, outlen,
			       !rq->partial_decoding);
	pageofs = rq->pageofs_out;
	strm->buf.in = kin + rq->pageofs_in;
	strm->buf.in_pos = 0;
	strm->buf.in_size = min_t(u32, inlen, PAGE_SIZE - rq->pageofs_in);
	inlen -= strm->buf.in_size;
	strm->buf.out = NULL;
	strm->buf.out_pos = 0;
	strm->buf.out_size = 0;

	for (ni = 0, no = -1;;) {
		enum xz_ret xz_err;

		if (strm->buf.out_pos == strm->buf.out_size) {
			if (strm->buf.out) {
				kunmap(rq->out[no]);
				strm->buf.out = NULL;
			}

			if (++no >= nrpages_out || !outlen) {
				erofs_err(rq->sb, "decompressed buf out of bound");
				err = -EFSCORRUPTED;
				break;
			}
			strm->buf.out_pos = 0;
			strm->buf.out_size = min_t(u32, outlen,
						   PAGE_SIZE - pageofs);
			outlen -= strm->buf.out_size;
			if (rq->out[no])
				strm->buf.out = kmap(rq->out[no]) + pageofs;
			pageofs = 0;
		} else if (strm->buf.in_pos == strm->buf.in_size) {
			kunmap(rq->in[ni]);

			if (++ni >= nrpages_in || !inlen) {
				erofs_err(rq->sb, "compressed buf out of bound");
				err = -EFSCORRUPTED;
				break;
			}
			strm->buf.in_pos = 0;
			strm->buf.in_size = min_t(u32, inlen, PAGE_SIZE);
			inlen -= strm->buf.in_size;
			kin = kmap(rq->in[ni]);
			strm->buf.in = kin;
			bounced = false;
		}

		/*
		 * Handle overlapping: Use bounced buffer if the compressed
		 * data is under processing; Otherwise, Use short-lived pages
		 * from the on-stack pagepool where pages share with the same
		 * request.
		 */
		if (!bounced && rq->out[no] == rq->in[ni]) {
			memcpy(strm->bounce, strm->buf.in, strm->buf.in_size);
			strm->buf.in = strm->bounce;
			bounced = true;
		}
		for (j = ni + 1; j < nrpages_in; ++j) {
			struct page *tmppage;

			if (rq->out[no] != rq->in[j])
				continue;

			DBG_BUGON(erofs_page_is_managed(EROFS_SB(rq->sb),
							rq->in[j]));
			tmppage = erofs_allocpage(pagepool,
						  GFP_KERNEL | __GFP_NOFAIL);
			set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
			copy_highpage(tmppage, rq->in[j]);
			rq->in[j] = tmppage;
		}
		xz_err = xz_dec_microlzma_run(strm->state, &strm->buf);
		DBG_BUGON(strm->buf.out_pos > strm->buf.out_size);
		DBG_BUGON(strm->buf.in_pos > strm->buf.in_size);

		if (xz_err != XZ_OK) {
			if (xz_err == XZ_STREAM_END && !outlen)
				break;
			erofs_err(rq->sb, "failed to decompress %d in[%u] out[%u]",
				  xz_err, rq->inputsize, rq->outputsize);
			err = -EFSCORRUPTED;
			break;
		}
	}
	if (no < nrpages_out && strm->buf.out)
		kunmap(rq->in[no]);
	if (ni < nrpages_in)
		kunmap(rq->in[ni]);
	/* 4. push back LZMA stream context to the global list */
	spin_lock(&z_erofs_lzma_lock);
	strm->next = z_erofs_lzma_head;
	z_erofs_lzma_head = strm;
	spin_unlock(&z_erofs_lzma_lock);
	wake_up(&z_erofs_lzma_wq);
	return err;
}