xref: /linux/fs/erofs/decompressor_zstd.c (revision 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 #include <linux/zstd.h>
3 #include "compress.h"
4 
5 struct z_erofs_zstd {
6 	struct z_erofs_zstd *next;
7 	u8 bounce[PAGE_SIZE];
8 	void *wksp;
9 	unsigned int wkspsz;
10 };
11 
12 static DEFINE_SPINLOCK(z_erofs_zstd_lock);
13 static unsigned int z_erofs_zstd_max_dictsize;
14 static unsigned int z_erofs_zstd_nstrms, z_erofs_zstd_avail_strms;
15 static struct z_erofs_zstd *z_erofs_zstd_head;
16 static DECLARE_WAIT_QUEUE_HEAD(z_erofs_zstd_wq);
17 
18 module_param_named(zstd_streams, z_erofs_zstd_nstrms, uint, 0444);
19 
20 static struct z_erofs_zstd *z_erofs_isolate_strms(bool all)
21 {
22 	struct z_erofs_zstd *strm;
23 
24 again:
25 	spin_lock(&z_erofs_zstd_lock);
26 	strm = z_erofs_zstd_head;
27 	if (!strm) {
28 		spin_unlock(&z_erofs_zstd_lock);
29 		wait_event(z_erofs_zstd_wq, READ_ONCE(z_erofs_zstd_head));
30 		goto again;
31 	}
32 	z_erofs_zstd_head = all ? NULL : strm->next;
33 	spin_unlock(&z_erofs_zstd_lock);
34 	return strm;
35 }
36 
37 void z_erofs_zstd_exit(void)
38 {
39 	while (z_erofs_zstd_avail_strms) {
40 		struct z_erofs_zstd *strm, *n;
41 
42 		for (strm = z_erofs_isolate_strms(true); strm; strm = n) {
43 			n = strm->next;
44 
45 			kvfree(strm->wksp);
46 			kfree(strm);
47 			--z_erofs_zstd_avail_strms;
48 		}
49 	}
50 }
51 
52 int __init z_erofs_zstd_init(void)
53 {
54 	/* by default, use # of possible CPUs instead */
55 	if (!z_erofs_zstd_nstrms)
56 		z_erofs_zstd_nstrms = num_possible_cpus();
57 
58 	for (; z_erofs_zstd_avail_strms < z_erofs_zstd_nstrms;
59 	     ++z_erofs_zstd_avail_strms) {
60 		struct z_erofs_zstd *strm;
61 
62 		strm = kzalloc(sizeof(*strm), GFP_KERNEL);
63 		if (!strm) {
64 			z_erofs_zstd_exit();
65 			return -ENOMEM;
66 		}
67 		spin_lock(&z_erofs_zstd_lock);
68 		strm->next = z_erofs_zstd_head;
69 		z_erofs_zstd_head = strm;
70 		spin_unlock(&z_erofs_zstd_lock);
71 	}
72 	return 0;
73 }
74 
75 int z_erofs_load_zstd_config(struct super_block *sb,
76 			struct erofs_super_block *dsb, void *data, int size)
77 {
78 	static DEFINE_MUTEX(zstd_resize_mutex);
79 	struct z_erofs_zstd_cfgs *zstd = data;
80 	unsigned int dict_size, wkspsz;
81 	struct z_erofs_zstd *strm, *head = NULL;
82 	void *wksp;
83 
84 	if (!zstd || size < sizeof(struct z_erofs_zstd_cfgs) || zstd->format) {
85 		erofs_err(sb, "unsupported zstd format, size=%u", size);
86 		return -EINVAL;
87 	}
88 
89 	if (zstd->windowlog > ilog2(Z_EROFS_ZSTD_MAX_DICT_SIZE) - 10) {
90 		erofs_err(sb, "unsupported zstd window log %u", zstd->windowlog);
91 		return -EINVAL;
92 	}
93 	dict_size = 1U << (zstd->windowlog + 10);
94 
95 	/* in case 2 z_erofs_load_zstd_config() race to avoid deadlock */
96 	mutex_lock(&zstd_resize_mutex);
97 	if (z_erofs_zstd_max_dictsize >= dict_size) {
98 		mutex_unlock(&zstd_resize_mutex);
99 		return 0;
100 	}
101 
102 	/* 1. collect/isolate all streams for the following check */
103 	while (z_erofs_zstd_avail_strms) {
104 		struct z_erofs_zstd *n;
105 
106 		for (strm = z_erofs_isolate_strms(true); strm; strm = n) {
107 			n = strm->next;
108 			strm->next = head;
109 			head = strm;
110 			--z_erofs_zstd_avail_strms;
111 		}
112 	}
113 
114 	/* 2. walk each isolated stream and grow max dict_size if needed */
115 	wkspsz = zstd_dstream_workspace_bound(dict_size);
116 	for (strm = head; strm; strm = strm->next) {
117 		wksp = kvmalloc(wkspsz, GFP_KERNEL);
118 		if (!wksp)
119 			break;
120 		kvfree(strm->wksp);
121 		strm->wksp = wksp;
122 		strm->wkspsz = wkspsz;
123 	}
124 
125 	/* 3. push back all to the global list and update max dict_size */
126 	spin_lock(&z_erofs_zstd_lock);
127 	DBG_BUGON(z_erofs_zstd_head);
128 	z_erofs_zstd_head = head;
129 	spin_unlock(&z_erofs_zstd_lock);
130 	z_erofs_zstd_avail_strms = z_erofs_zstd_nstrms;
131 	wake_up_all(&z_erofs_zstd_wq);
132 	if (!strm)
133 		z_erofs_zstd_max_dictsize = dict_size;
134 	mutex_unlock(&zstd_resize_mutex);
135 	return strm ? -ENOMEM : 0;
136 }
137 
138 int z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
139 			    struct page **pgpl)
140 {
141 	const unsigned int nrpages_out =
142 		PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
143 	const unsigned int nrpages_in =
144 		PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
145 	zstd_dstream *stream;
146 	struct super_block *sb = rq->sb;
147 	unsigned int insz, outsz, pofs;
148 	struct z_erofs_zstd *strm;
149 	zstd_in_buffer in_buf = { NULL, 0, 0 };
150 	zstd_out_buffer out_buf = { NULL, 0, 0 };
151 	u8 *kin, *kout = NULL;
152 	bool bounced = false;
153 	int no = -1, ni = 0, j = 0, zerr, err;
154 
155 	/* 1. get the exact compressed size */
156 	kin = kmap_local_page(*rq->in);
157 	err = z_erofs_fixup_insize(rq, kin + rq->pageofs_in,
158 			min_t(unsigned int, rq->inputsize,
159 			      sb->s_blocksize - rq->pageofs_in));
160 	if (err) {
161 		kunmap_local(kin);
162 		return err;
163 	}
164 
165 	/* 2. get an available ZSTD context */
166 	strm = z_erofs_isolate_strms(false);
167 
168 	/* 3. multi-call decompress */
169 	insz = rq->inputsize;
170 	outsz = rq->outputsize;
171 	stream = zstd_init_dstream(z_erofs_zstd_max_dictsize, strm->wksp, strm->wkspsz);
172 	if (!stream) {
173 		err = -EIO;
174 		goto failed_zinit;
175 	}
176 
177 	pofs = rq->pageofs_out;
178 	in_buf.size = min_t(u32, insz, PAGE_SIZE - rq->pageofs_in);
179 	insz -= in_buf.size;
180 	in_buf.src = kin + rq->pageofs_in;
181 	do {
182 		if (out_buf.size == out_buf.pos) {
183 			if (++no >= nrpages_out || !outsz) {
184 				erofs_err(sb, "insufficient space for decompressed data");
185 				err = -EFSCORRUPTED;
186 				break;
187 			}
188 
189 			if (kout)
190 				kunmap_local(kout);
191 			out_buf.size = min_t(u32, outsz, PAGE_SIZE - pofs);
192 			outsz -= out_buf.size;
193 			if (!rq->out[no]) {
194 				rq->out[no] = erofs_allocpage(pgpl, rq->gfp);
195 				if (!rq->out[no]) {
196 					kout = NULL;
197 					err = -ENOMEM;
198 					break;
199 				}
200 				set_page_private(rq->out[no],
201 						 Z_EROFS_SHORTLIVED_PAGE);
202 			}
203 			kout = kmap_local_page(rq->out[no]);
204 			out_buf.dst = kout + pofs;
205 			out_buf.pos = 0;
206 			pofs = 0;
207 		}
208 
209 		if (in_buf.size == in_buf.pos && insz) {
210 			if (++ni >= nrpages_in) {
211 				erofs_err(sb, "invalid compressed data");
212 				err = -EFSCORRUPTED;
213 				break;
214 			}
215 
216 			if (kout) /* unlike kmap(), take care of the orders */
217 				kunmap_local(kout);
218 			kunmap_local(kin);
219 			in_buf.size = min_t(u32, insz, PAGE_SIZE);
220 			insz -= in_buf.size;
221 			kin = kmap_local_page(rq->in[ni]);
222 			in_buf.src = kin;
223 			in_buf.pos = 0;
224 			bounced = false;
225 			if (kout) {
226 				j = (u8 *)out_buf.dst - kout;
227 				kout = kmap_local_page(rq->out[no]);
228 				out_buf.dst = kout + j;
229 			}
230 		}
231 
232 		/*
233 		 * Handle overlapping: Use bounced buffer if the compressed
234 		 * data is under processing; Or use short-lived pages from the
235 		 * on-stack pagepool where pages share among the same request
236 		 * and not _all_ inplace I/O pages are needed to be doubled.
237 		 */
238 		if (!bounced && rq->out[no] == rq->in[ni]) {
239 			memcpy(strm->bounce, in_buf.src, in_buf.size);
240 			in_buf.src = strm->bounce;
241 			bounced = true;
242 		}
243 
244 		for (j = ni + 1; j < nrpages_in; ++j) {
245 			struct page *tmppage;
246 
247 			if (rq->out[no] != rq->in[j])
248 				continue;
249 			tmppage = erofs_allocpage(pgpl, rq->gfp);
250 			if (!tmppage) {
251 				err = -ENOMEM;
252 				goto failed;
253 			}
254 			set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
255 			copy_highpage(tmppage, rq->in[j]);
256 			rq->in[j] = tmppage;
257 		}
258 		zerr = zstd_decompress_stream(stream, &out_buf, &in_buf);
259 		if (zstd_is_error(zerr) || (!zerr && outsz)) {
260 			erofs_err(sb, "failed to decompress in[%u] out[%u]: %s",
261 				  rq->inputsize, rq->outputsize,
262 				  zerr ? zstd_get_error_name(zerr) : "unexpected end of stream");
263 			err = -EFSCORRUPTED;
264 			break;
265 		}
266 	} while (outsz || out_buf.pos < out_buf.size);
267 failed:
268 	if (kout)
269 		kunmap_local(kout);
270 failed_zinit:
271 	kunmap_local(kin);
272 	/* 4. push back ZSTD stream context to the global list */
273 	spin_lock(&z_erofs_zstd_lock);
274 	strm->next = z_erofs_zstd_head;
275 	z_erofs_zstd_head = strm;
276 	spin_unlock(&z_erofs_zstd_lock);
277 	wake_up(&z_erofs_zstd_wq);
278 	return err;
279 }
280