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(&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
 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(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(zlib_inflate_workspacesize());
 60		if (!strm->z.workspace) {
 61			kfree(strm);
 62			goto out_failed;
 63		}
 64
 65		spin_lock(&z_erofs_deflate_lock);
 66		strm->next = z_erofs_deflate_head;
 67		z_erofs_deflate_head = strm;
 68		spin_unlock(&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(*rq->in);
113	err = z_erofs_fixup_insize(rq, 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(&z_erofs_deflate_lock);
124	strm = z_erofs_deflate_head;
125	if (!strm) {
126		spin_unlock(&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(&z_erofs_deflate_lock);
132
133	/* 3. multi-call decompress */
134	insz = rq->inputsize;
135	outsz = rq->outputsize;
136	zerr = zlib_inflateInit2(&strm->z, -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(pgpl, rq->gfp);
162				if (!rq->out[no]) {
163					kout = NULL;
164					err = -ENOMEM;
165					break;
166				}
167				set_page_private(rq->out[no],
168						 Z_EROFS_SHORTLIVED_PAGE);
169			}
170			kout = kmap_local_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(rq->in[ni]);
190			strm->z.next_in = kin;
191			bounced = false;
192			if (kout) {
193				kout = kmap_local_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
216			DBG_BUGON(erofs_page_is_managed(EROFS_SB(sb),
217							rq->in[j]));
218			tmppage = erofs_allocpage(pgpl, rq->gfp);
219			if (!tmppage) {
220				err = -ENOMEM;
221				goto failed;
222			}
223			set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
224			copy_highpage(tmppage, rq->in[j]);
225			rq->in[j] = tmppage;
226		}
227
228		zerr = zlib_inflate(&strm->z, Z_SYNC_FLUSH);
229		if (zerr != Z_OK || !(outsz + strm->z.avail_out)) {
230			if (zerr == Z_OK && rq->partial_decoding)
231				break;
232			if (zerr == Z_STREAM_END && !outsz)
233				break;
234			erofs_err(sb, "failed to decompress %d in[%u] out[%u]",
235				  zerr, rq->inputsize, rq->outputsize);
236			err = -EFSCORRUPTED;
237			break;
238		}
239	}
240failed:
241	if (zlib_inflateEnd(&strm->z) != Z_OK && !err)
242		err = -EIO;
243	if (kout)
244		kunmap_local(kout);
245failed_zinit:
246	kunmap_local(kin);
247	/* 4. push back DEFLATE stream context to the global list */
248	spin_lock(&z_erofs_deflate_lock);
249	strm->next = z_erofs_deflate_head;
250	z_erofs_deflate_head = strm;
251	spin_unlock(&z_erofs_deflate_lock);
252	wake_up(&z_erofs_deflate_wq);
253	return err;
254}