decompressor_deflate.c

  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
 18static void 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(&z_erofs_deflate_lock);
 25		strm = z_erofs_deflate_head;
 26		if (!strm) {
 27			spin_unlock(&z_erofs_deflate_lock);
 28			continue;
 29		}
 30		z_erofs_deflate_head = NULL;
 31		spin_unlock(&z_erofs_deflate_lock);
 32
 33		while (strm) {
 34			struct z_erofs_deflate *n = strm->next;
 35
 36			vfree(strm->z.workspace);
 37			kfree(strm);
 38			--z_erofs_deflate_avail_strms;
 39			strm = n;
 40		}
 41	}
 42}
 43
 44static int __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	return 0;
 50}
 51
 52static int z_erofs_load_deflate_config(struct super_block *sb,
 53			struct erofs_super_block *dsb, void *data, int size)
 54{
 55	struct z_erofs_deflate_cfgs *dfl = data;
 56	static DEFINE_MUTEX(deflate_resize_mutex);
 57	static bool inited;
 58
 59	if (!dfl || size < sizeof(struct z_erofs_deflate_cfgs)) {
 60		erofs_err(sb, "invalid deflate cfgs, size=%u", size);
 61		return -EINVAL;
 62	}
 63
 64	if (dfl->windowbits > MAX_WBITS) {
 65		erofs_err(sb, "unsupported windowbits %u", dfl->windowbits);
 66		return -EOPNOTSUPP;
 67	}
 68	mutex_lock(&deflate_resize_mutex);
 69	if (!inited) {
 70		for (; z_erofs_deflate_avail_strms < z_erofs_deflate_nstrms;
 71		     ++z_erofs_deflate_avail_strms) {
 72			struct z_erofs_deflate *strm;
 73
 74			strm = kzalloc(sizeof(*strm), GFP_KERNEL);
 75			if (!strm)
 76				goto failed;
 77			/* XXX: in-kernel zlib cannot customize windowbits */
 78			strm->z.workspace = vmalloc(zlib_inflate_workspacesize());
 79			if (!strm->z.workspace) {
 80				kfree(strm);
 81				goto failed;
 82			}
 83
 84			spin_lock(&z_erofs_deflate_lock);
 85			strm->next = z_erofs_deflate_head;
 86			z_erofs_deflate_head = strm;
 87			spin_unlock(&z_erofs_deflate_lock);
 88		}
 89		inited = true;
 90	}
 91	mutex_unlock(&deflate_resize_mutex);
 92	erofs_info(sb, "EXPERIMENTAL DEFLATE feature in use. Use at your own risk!");
 93	return 0;
 94failed:
 95	mutex_unlock(&deflate_resize_mutex);
 96	z_erofs_deflate_exit();
 97	return -ENOMEM;
 98}
 99
100static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
101						struct page **pgpl)
102{
103	struct super_block *sb = rq->sb;
104	struct z_erofs_stream_dctx dctx = { .rq = rq, .no = -1, .ni = 0 };
105	struct z_erofs_deflate *strm;
106	const char *reason;
107	int zerr;
108
109	/* 1. get the exact DEFLATE compressed size */
110	dctx.kin = kmap_local_page(*rq->in);
111	reason = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
112			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
113	if (reason) {
114		kunmap_local(dctx.kin);
115		return reason;
116	}
117
118	/* 2. get an available DEFLATE context */
119again:
120	spin_lock(&z_erofs_deflate_lock);
121	strm = z_erofs_deflate_head;
122	if (!strm) {
123		spin_unlock(&z_erofs_deflate_lock);
124		wait_event(z_erofs_deflate_wq, READ_ONCE(z_erofs_deflate_head));
125		goto again;
126	}
127	z_erofs_deflate_head = strm->next;
128	spin_unlock(&z_erofs_deflate_lock);
129
130	/* 3. multi-call decompress */
131	zerr = zlib_inflateInit2(&strm->z, -MAX_WBITS);
132	if (zerr != Z_OK) {
133		reason = ERR_PTR(-EINVAL);
134		goto failed_zinit;
135	}
136
137	rq->fillgaps = true;	/* DEFLATE doesn't support NULL output buffer */
138	strm->z.avail_in = min(rq->inputsize, PAGE_SIZE - rq->pageofs_in);
139	rq->inputsize -= strm->z.avail_in;
140	strm->z.next_in = dctx.kin + rq->pageofs_in;
141	strm->z.avail_out = 0;
142	dctx.bounce = strm->bounce;
143
144	while (1) {
145		dctx.avail_out = strm->z.avail_out;
146		dctx.inbuf_sz = strm->z.avail_in;
147		reason = z_erofs_stream_switch_bufs(&dctx,
148					(void **)&strm->z.next_out,
149					(void **)&strm->z.next_in, pgpl);
150		if (reason)
151			break;
152		strm->z.avail_out = dctx.avail_out;
153		strm->z.avail_in = dctx.inbuf_sz;
154
155		zerr = zlib_inflate(&strm->z, Z_SYNC_FLUSH);
156		if (zerr != Z_OK || !(rq->outputsize + strm->z.avail_out)) {
157			if (zerr == Z_OK && rq->partial_decoding)
158				break;
159			if (zerr == Z_STREAM_END && !rq->outputsize)
160				break;
161			reason = (zerr == Z_DATA_ERROR ?
162				"corrupted compressed data" :
163				"unexpected end of stream");
164			break;
165		}
166	}
167	if (zlib_inflateEnd(&strm->z) != Z_OK && !reason)
168		reason = ERR_PTR(-EIO);
169	if (dctx.kout)
170		kunmap_local(dctx.kout);
171failed_zinit:
172	kunmap_local(dctx.kin);
173	/* 4. push back DEFLATE stream context to the global list */
174	spin_lock(&z_erofs_deflate_lock);
175	strm->next = z_erofs_deflate_head;
176	z_erofs_deflate_head = strm;
177	spin_unlock(&z_erofs_deflate_lock);
178	wake_up(&z_erofs_deflate_wq);
179	return reason;
180}
181
182static const char *z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
183					      struct page **pgpl)
184{
185#ifdef CONFIG_EROFS_FS_ZIP_ACCEL
186	int err;
187
188	if (!rq->partial_decoding) {
189		err = z_erofs_crypto_decompress(rq, pgpl);
190		if (err != -EOPNOTSUPP)
191			return ERR_PTR(err);
192
193	}
194#endif
195	return __z_erofs_deflate_decompress(rq, pgpl);
196}
197
198const struct z_erofs_decompressor z_erofs_deflate_decomp = {
199	.config = z_erofs_load_deflate_config,
200	.decompress = z_erofs_deflate_decompress,
201	.init = z_erofs_deflate_init,
202	.exit = z_erofs_deflate_exit,
203	.name = "deflate",
204};