1// SPDX-License-Identifier: GPL-2.0-or-later
2#include <linux/zlib.h>
3#include "compress.h"
4
5struct z_erofs_deflate {
6 struct z_erofs_deflate *next;
7 struct z_stream_s z;
8 u8 bounce[PAGE_SIZE];
9};
10
11static DEFINE_SPINLOCK(z_erofs_deflate_lock);
12static unsigned int z_erofs_deflate_nstrms, z_erofs_deflate_avail_strms;
13static struct z_erofs_deflate *z_erofs_deflate_head;
14static DECLARE_WAIT_QUEUE_HEAD(z_erofs_deflate_wq);
15
16module_param_named(deflate_streams, z_erofs_deflate_nstrms, uint, 0444);
17
18void z_erofs_deflate_exit(void)
19{
20 /* there should be no running fs instance */
21 while (z_erofs_deflate_avail_strms) {
22 struct z_erofs_deflate *strm;
23
24 spin_lock(lock: &z_erofs_deflate_lock);
25 strm = z_erofs_deflate_head;
26 if (!strm) {
27 spin_unlock(lock: &z_erofs_deflate_lock);
28 continue;
29 }
30 z_erofs_deflate_head = NULL;
31 spin_unlock(lock: &z_erofs_deflate_lock);
32
33 while (strm) {
34 struct z_erofs_deflate *n = strm->next;
35
36 vfree(addr: strm->z.workspace);
37 kfree(objp: strm);
38 --z_erofs_deflate_avail_strms;
39 strm = n;
40 }
41 }
42}
43
44int __init z_erofs_deflate_init(void)
45{
46 /* by default, use # of possible CPUs instead */
47 if (!z_erofs_deflate_nstrms)
48 z_erofs_deflate_nstrms = num_possible_cpus();
49
50 for (; z_erofs_deflate_avail_strms < z_erofs_deflate_nstrms;
51 ++z_erofs_deflate_avail_strms) {
52 struct z_erofs_deflate *strm;
53
54 strm = kzalloc(size: sizeof(*strm), GFP_KERNEL);
55 if (!strm)
56 goto out_failed;
57
58 /* XXX: in-kernel zlib cannot shrink windowbits currently */
59 strm->z.workspace = vmalloc(size: zlib_inflate_workspacesize());
60 if (!strm->z.workspace) {
61 kfree(objp: strm);
62 goto out_failed;
63 }
64
65 spin_lock(lock: &z_erofs_deflate_lock);
66 strm->next = z_erofs_deflate_head;
67 z_erofs_deflate_head = strm;
68 spin_unlock(lock: &z_erofs_deflate_lock);
69 }
70 return 0;
71
72out_failed:
73 erofs_err(NULL, "failed to allocate zlib workspace");
74 z_erofs_deflate_exit();
75 return -ENOMEM;
76}
77
78int z_erofs_load_deflate_config(struct super_block *sb,
79 struct erofs_super_block *dsb, void *data, int size)
80{
81 struct z_erofs_deflate_cfgs *dfl = data;
82
83 if (!dfl || size < sizeof(struct z_erofs_deflate_cfgs)) {
84 erofs_err(sb, "invalid deflate cfgs, size=%u", size);
85 return -EINVAL;
86 }
87
88 if (dfl->windowbits > MAX_WBITS) {
89 erofs_err(sb, "unsupported windowbits %u", dfl->windowbits);
90 return -EOPNOTSUPP;
91 }
92
93 erofs_info(sb, "EXPERIMENTAL DEFLATE feature in use. Use at your own risk!");
94 return 0;
95}
96
97int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
98 struct page **pgpl)
99{
100 const unsigned int nrpages_out =
101 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
102 const unsigned int nrpages_in =
103 PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
104 struct super_block *sb = rq->sb;
105 unsigned int insz, outsz, pofs;
106 struct z_erofs_deflate *strm;
107 u8 *kin, *kout = NULL;
108 bool bounced = false;
109 int no = -1, ni = 0, j = 0, zerr, err;
110
111 /* 1. get the exact DEFLATE compressed size */
112 kin = kmap_local_page(page: *rq->in);
113 err = z_erofs_fixup_insize(rq, padbuf: kin + rq->pageofs_in,
114 min_t(unsigned int, rq->inputsize,
115 sb->s_blocksize - rq->pageofs_in));
116 if (err) {
117 kunmap_local(kin);
118 return err;
119 }
120
121 /* 2. get an available DEFLATE context */
122again:
123 spin_lock(lock: &z_erofs_deflate_lock);
124 strm = z_erofs_deflate_head;
125 if (!strm) {
126 spin_unlock(lock: &z_erofs_deflate_lock);
127 wait_event(z_erofs_deflate_wq, READ_ONCE(z_erofs_deflate_head));
128 goto again;
129 }
130 z_erofs_deflate_head = strm->next;
131 spin_unlock(lock: &z_erofs_deflate_lock);
132
133 /* 3. multi-call decompress */
134 insz = rq->inputsize;
135 outsz = rq->outputsize;
136 zerr = zlib_inflateInit2(strm: &strm->z, windowBits: -MAX_WBITS);
137 if (zerr != Z_OK) {
138 err = -EIO;
139 goto failed_zinit;
140 }
141
142 pofs = rq->pageofs_out;
143 strm->z.avail_in = min_t(u32, insz, PAGE_SIZE - rq->pageofs_in);
144 insz -= strm->z.avail_in;
145 strm->z.next_in = kin + rq->pageofs_in;
146 strm->z.avail_out = 0;
147
148 while (1) {
149 if (!strm->z.avail_out) {
150 if (++no >= nrpages_out || !outsz) {
151 erofs_err(sb, "insufficient space for decompressed data");
152 err = -EFSCORRUPTED;
153 break;
154 }
155
156 if (kout)
157 kunmap_local(kout);
158 strm->z.avail_out = min_t(u32, outsz, PAGE_SIZE - pofs);
159 outsz -= strm->z.avail_out;
160 if (!rq->out[no]) {
161 rq->out[no] = erofs_allocpage(pagepool: pgpl, gfp: rq->gfp);
162 if (!rq->out[no]) {
163 kout = NULL;
164 err = -ENOMEM;
165 break;
166 }
167 set_page_private(page: rq->out[no],
168 Z_EROFS_SHORTLIVED_PAGE);
169 }
170 kout = kmap_local_page(page: rq->out[no]);
171 strm->z.next_out = kout + pofs;
172 pofs = 0;
173 }
174
175 if (!strm->z.avail_in && insz) {
176 if (++ni >= nrpages_in) {
177 erofs_err(sb, "invalid compressed data");
178 err = -EFSCORRUPTED;
179 break;
180 }
181
182 if (kout) { /* unlike kmap(), take care of the orders */
183 j = strm->z.next_out - kout;
184 kunmap_local(kout);
185 }
186 kunmap_local(kin);
187 strm->z.avail_in = min_t(u32, insz, PAGE_SIZE);
188 insz -= strm->z.avail_in;
189 kin = kmap_local_page(page: rq->in[ni]);
190 strm->z.next_in = kin;
191 bounced = false;
192 if (kout) {
193 kout = kmap_local_page(page: rq->out[no]);
194 strm->z.next_out = kout + j;
195 }
196 }
197
198 /*
199 * Handle overlapping: Use bounced buffer if the compressed
200 * data is under processing; Or use short-lived pages from the
201 * on-stack pagepool where pages share among the same request
202 * and not _all_ inplace I/O pages are needed to be doubled.
203 */
204 if (!bounced && rq->out[no] == rq->in[ni]) {
205 memcpy(strm->bounce, strm->z.next_in, strm->z.avail_in);
206 strm->z.next_in = strm->bounce;
207 bounced = true;
208 }
209
210 for (j = ni + 1; j < nrpages_in; ++j) {
211 struct page *tmppage;
212
213 if (rq->out[no] != rq->in[j])
214 continue;
215 tmppage = erofs_allocpage(pagepool: pgpl, gfp: rq->gfp);
216 if (!tmppage) {
217 err = -ENOMEM;
218 goto failed;
219 }
220 set_page_private(page: tmppage, Z_EROFS_SHORTLIVED_PAGE);
221 copy_highpage(to: tmppage, from: rq->in[j]);
222 rq->in[j] = tmppage;
223 }
224
225 zerr = zlib_inflate(strm: &strm->z, Z_SYNC_FLUSH);
226 if (zerr != Z_OK || !(outsz + strm->z.avail_out)) {
227 if (zerr == Z_OK && rq->partial_decoding)
228 break;
229 if (zerr == Z_STREAM_END && !outsz)
230 break;
231 erofs_err(sb, "failed to decompress %d in[%u] out[%u]",
232 zerr, rq->inputsize, rq->outputsize);
233 err = -EFSCORRUPTED;
234 break;
235 }
236 }
237failed:
238 if (zlib_inflateEnd(strm: &strm->z) != Z_OK && !err)
239 err = -EIO;
240 if (kout)
241 kunmap_local(kout);
242failed_zinit:
243 kunmap_local(kin);
244 /* 4. push back DEFLATE stream context to the global list */
245 spin_lock(lock: &z_erofs_deflate_lock);
246 strm->next = z_erofs_deflate_head;
247 z_erofs_deflate_head = strm;
248 spin_unlock(lock: &z_erofs_deflate_lock);
249 wake_up(&z_erofs_deflate_wq);
250 return err;
251}
252

source code of linux/fs/erofs/decompressor_deflate.c