1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2008 Oracle.  All rights reserved.
4  *
5  * Based on jffs2 zlib code:
6  * Copyright © 2001-2007 Red Hat, Inc.
7  * Created by David Woodhouse <dwmw2@infradead.org>
8  */
9 
10 #include <linux/kernel.h>
11 #include <linux/slab.h>
12 #include <linux/zlib.h>
13 #include <linux/zutil.h>
14 #include <linux/mm.h>
15 #include <linux/init.h>
16 #include <linux/err.h>
17 #include <linux/sched.h>
18 #include <linux/pagemap.h>
19 #include <linux/bio.h>
20 #include <linux/refcount.h>
21 #include "compression.h"
22 
23 /* workspace buffer size for s390 zlib hardware support */
24 #define ZLIB_DFLTCC_BUF_SIZE    (4 * PAGE_SIZE)
25 
26 struct workspace {
27 	z_stream strm;
28 	char *buf;
29 	unsigned int buf_size;
30 	struct list_head list;
31 	int level;
32 };
33 
34 static struct workspace_manager wsm;
35 
zlib_get_workspace(unsigned int level)36 struct list_head *zlib_get_workspace(unsigned int level)
37 {
38 	struct list_head *ws = btrfs_get_workspace(BTRFS_COMPRESS_ZLIB, level);
39 	struct workspace *workspace = list_entry(ws, struct workspace, list);
40 
41 	workspace->level = level;
42 
43 	return ws;
44 }
45 
zlib_free_workspace(struct list_head * ws)46 void zlib_free_workspace(struct list_head *ws)
47 {
48 	struct workspace *workspace = list_entry(ws, struct workspace, list);
49 
50 	kvfree(workspace->strm.workspace);
51 	kfree(workspace->buf);
52 	kfree(workspace);
53 }
54 
zlib_alloc_workspace(unsigned int level)55 struct list_head *zlib_alloc_workspace(unsigned int level)
56 {
57 	struct workspace *workspace;
58 	int workspacesize;
59 
60 	workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
61 	if (!workspace)
62 		return ERR_PTR(-ENOMEM);
63 
64 	workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
65 			zlib_inflate_workspacesize());
66 	workspace->strm.workspace = kvmalloc(workspacesize, GFP_KERNEL);
67 	workspace->level = level;
68 	workspace->buf = NULL;
69 	/*
70 	 * In case of s390 zlib hardware support, allocate lager workspace
71 	 * buffer. If allocator fails, fall back to a single page buffer.
72 	 */
73 	if (zlib_deflate_dfltcc_enabled()) {
74 		workspace->buf = kmalloc(ZLIB_DFLTCC_BUF_SIZE,
75 					 __GFP_NOMEMALLOC | __GFP_NORETRY |
76 					 __GFP_NOWARN | GFP_NOIO);
77 		workspace->buf_size = ZLIB_DFLTCC_BUF_SIZE;
78 	}
79 	if (!workspace->buf) {
80 		workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
81 		workspace->buf_size = PAGE_SIZE;
82 	}
83 	if (!workspace->strm.workspace || !workspace->buf)
84 		goto fail;
85 
86 	INIT_LIST_HEAD(&workspace->list);
87 
88 	return &workspace->list;
89 fail:
90 	zlib_free_workspace(&workspace->list);
91 	return ERR_PTR(-ENOMEM);
92 }
93 
zlib_compress_pages(struct list_head * ws,struct address_space * mapping,u64 start,struct page ** pages,unsigned long * out_pages,unsigned long * total_in,unsigned long * total_out)94 int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
95 		u64 start, struct page **pages, unsigned long *out_pages,
96 		unsigned long *total_in, unsigned long *total_out)
97 {
98 	struct workspace *workspace = list_entry(ws, struct workspace, list);
99 	int ret;
100 	char *data_in = NULL;
101 	char *cpage_out;
102 	int nr_pages = 0;
103 	struct page *in_page = NULL;
104 	struct page *out_page = NULL;
105 	unsigned long bytes_left;
106 	unsigned int in_buf_pages;
107 	unsigned long len = *total_out;
108 	unsigned long nr_dest_pages = *out_pages;
109 	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
110 
111 	*out_pages = 0;
112 	*total_out = 0;
113 	*total_in = 0;
114 
115 	if (Z_OK != zlib_deflateInit(&workspace->strm, workspace->level)) {
116 		pr_warn("BTRFS: deflateInit failed\n");
117 		ret = -EIO;
118 		goto out;
119 	}
120 
121 	workspace->strm.total_in = 0;
122 	workspace->strm.total_out = 0;
123 
124 	out_page = alloc_page(GFP_NOFS);
125 	if (out_page == NULL) {
126 		ret = -ENOMEM;
127 		goto out;
128 	}
129 	cpage_out = page_address(out_page);
130 	pages[0] = out_page;
131 	nr_pages = 1;
132 
133 	workspace->strm.next_in = workspace->buf;
134 	workspace->strm.avail_in = 0;
135 	workspace->strm.next_out = cpage_out;
136 	workspace->strm.avail_out = PAGE_SIZE;
137 
138 	while (workspace->strm.total_in < len) {
139 		/*
140 		 * Get next input pages and copy the contents to
141 		 * the workspace buffer if required.
142 		 */
143 		if (workspace->strm.avail_in == 0) {
144 			bytes_left = len - workspace->strm.total_in;
145 			in_buf_pages = min(DIV_ROUND_UP(bytes_left, PAGE_SIZE),
146 					   workspace->buf_size / PAGE_SIZE);
147 			if (in_buf_pages > 1) {
148 				int i;
149 
150 				for (i = 0; i < in_buf_pages; i++) {
151 					if (data_in) {
152 						kunmap_local(data_in);
153 						put_page(in_page);
154 					}
155 					in_page = find_get_page(mapping,
156 								start >> PAGE_SHIFT);
157 					data_in = kmap_local_page(in_page);
158 					memcpy(workspace->buf + i * PAGE_SIZE,
159 					       data_in, PAGE_SIZE);
160 					start += PAGE_SIZE;
161 				}
162 				workspace->strm.next_in = workspace->buf;
163 			} else {
164 				if (data_in) {
165 					kunmap_local(data_in);
166 					put_page(in_page);
167 				}
168 				in_page = find_get_page(mapping,
169 							start >> PAGE_SHIFT);
170 				data_in = kmap_local_page(in_page);
171 				start += PAGE_SIZE;
172 				workspace->strm.next_in = data_in;
173 			}
174 			workspace->strm.avail_in = min(bytes_left,
175 						       (unsigned long) workspace->buf_size);
176 		}
177 
178 		ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
179 		if (ret != Z_OK) {
180 			pr_debug("BTRFS: deflate in loop returned %d\n",
181 			       ret);
182 			zlib_deflateEnd(&workspace->strm);
183 			ret = -EIO;
184 			goto out;
185 		}
186 
187 		/* we're making it bigger, give up */
188 		if (workspace->strm.total_in > 8192 &&
189 		    workspace->strm.total_in <
190 		    workspace->strm.total_out) {
191 			ret = -E2BIG;
192 			goto out;
193 		}
194 		/* we need another page for writing out.  Test this
195 		 * before the total_in so we will pull in a new page for
196 		 * the stream end if required
197 		 */
198 		if (workspace->strm.avail_out == 0) {
199 			if (nr_pages == nr_dest_pages) {
200 				ret = -E2BIG;
201 				goto out;
202 			}
203 			out_page = alloc_page(GFP_NOFS);
204 			if (out_page == NULL) {
205 				ret = -ENOMEM;
206 				goto out;
207 			}
208 			cpage_out = page_address(out_page);
209 			pages[nr_pages] = out_page;
210 			nr_pages++;
211 			workspace->strm.avail_out = PAGE_SIZE;
212 			workspace->strm.next_out = cpage_out;
213 		}
214 		/* we're all done */
215 		if (workspace->strm.total_in >= len)
216 			break;
217 		if (workspace->strm.total_out > max_out)
218 			break;
219 	}
220 	workspace->strm.avail_in = 0;
221 	/*
222 	 * Call deflate with Z_FINISH flush parameter providing more output
223 	 * space but no more input data, until it returns with Z_STREAM_END.
224 	 */
225 	while (ret != Z_STREAM_END) {
226 		ret = zlib_deflate(&workspace->strm, Z_FINISH);
227 		if (ret == Z_STREAM_END)
228 			break;
229 		if (ret != Z_OK && ret != Z_BUF_ERROR) {
230 			zlib_deflateEnd(&workspace->strm);
231 			ret = -EIO;
232 			goto out;
233 		} else if (workspace->strm.avail_out == 0) {
234 			/* get another page for the stream end */
235 			if (nr_pages == nr_dest_pages) {
236 				ret = -E2BIG;
237 				goto out;
238 			}
239 			out_page = alloc_page(GFP_NOFS);
240 			if (out_page == NULL) {
241 				ret = -ENOMEM;
242 				goto out;
243 			}
244 			cpage_out = page_address(out_page);
245 			pages[nr_pages] = out_page;
246 			nr_pages++;
247 			workspace->strm.avail_out = PAGE_SIZE;
248 			workspace->strm.next_out = cpage_out;
249 		}
250 	}
251 	zlib_deflateEnd(&workspace->strm);
252 
253 	if (workspace->strm.total_out >= workspace->strm.total_in) {
254 		ret = -E2BIG;
255 		goto out;
256 	}
257 
258 	ret = 0;
259 	*total_out = workspace->strm.total_out;
260 	*total_in = workspace->strm.total_in;
261 out:
262 	*out_pages = nr_pages;
263 	if (data_in) {
264 		kunmap_local(data_in);
265 		put_page(in_page);
266 	}
267 
268 	return ret;
269 }
270 
zlib_decompress_bio(struct list_head * ws,struct compressed_bio * cb)271 int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
272 {
273 	struct workspace *workspace = list_entry(ws, struct workspace, list);
274 	int ret = 0, ret2;
275 	int wbits = MAX_WBITS;
276 	char *data_in;
277 	size_t total_out = 0;
278 	unsigned long page_in_index = 0;
279 	size_t srclen = cb->compressed_len;
280 	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
281 	unsigned long buf_start;
282 	struct page **pages_in = cb->compressed_pages;
283 
284 	data_in = kmap_local_page(pages_in[page_in_index]);
285 	workspace->strm.next_in = data_in;
286 	workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
287 	workspace->strm.total_in = 0;
288 
289 	workspace->strm.total_out = 0;
290 	workspace->strm.next_out = workspace->buf;
291 	workspace->strm.avail_out = workspace->buf_size;
292 
293 	/* If it's deflate, and it's got no preset dictionary, then
294 	   we can tell zlib to skip the adler32 check. */
295 	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
296 	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
297 	    !(((data_in[0]<<8) + data_in[1]) % 31)) {
298 
299 		wbits = -((data_in[0] >> 4) + 8);
300 		workspace->strm.next_in += 2;
301 		workspace->strm.avail_in -= 2;
302 	}
303 
304 	if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
305 		pr_warn("BTRFS: inflateInit failed\n");
306 		kunmap_local(data_in);
307 		return -EIO;
308 	}
309 	while (workspace->strm.total_in < srclen) {
310 		ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
311 		if (ret != Z_OK && ret != Z_STREAM_END)
312 			break;
313 
314 		buf_start = total_out;
315 		total_out = workspace->strm.total_out;
316 
317 		/* we didn't make progress in this inflate call, we're done */
318 		if (buf_start == total_out)
319 			break;
320 
321 		ret2 = btrfs_decompress_buf2page(workspace->buf,
322 				total_out - buf_start, cb, buf_start);
323 		if (ret2 == 0) {
324 			ret = 0;
325 			goto done;
326 		}
327 
328 		workspace->strm.next_out = workspace->buf;
329 		workspace->strm.avail_out = workspace->buf_size;
330 
331 		if (workspace->strm.avail_in == 0) {
332 			unsigned long tmp;
333 			kunmap_local(data_in);
334 			page_in_index++;
335 			if (page_in_index >= total_pages_in) {
336 				data_in = NULL;
337 				break;
338 			}
339 			data_in = kmap_local_page(pages_in[page_in_index]);
340 			workspace->strm.next_in = data_in;
341 			tmp = srclen - workspace->strm.total_in;
342 			workspace->strm.avail_in = min(tmp, PAGE_SIZE);
343 		}
344 	}
345 	if (ret != Z_STREAM_END)
346 		ret = -EIO;
347 	else
348 		ret = 0;
349 done:
350 	zlib_inflateEnd(&workspace->strm);
351 	if (data_in)
352 		kunmap_local(data_in);
353 	if (!ret)
354 		zero_fill_bio(cb->orig_bio);
355 	return ret;
356 }
357 
zlib_decompress(struct list_head * ws,unsigned char * data_in,struct page * dest_page,unsigned long start_byte,size_t srclen,size_t destlen)358 int zlib_decompress(struct list_head *ws, unsigned char *data_in,
359 		struct page *dest_page, unsigned long start_byte, size_t srclen,
360 		size_t destlen)
361 {
362 	struct workspace *workspace = list_entry(ws, struct workspace, list);
363 	int ret = 0;
364 	int wbits = MAX_WBITS;
365 	unsigned long bytes_left;
366 	unsigned long total_out = 0;
367 	unsigned long pg_offset = 0;
368 
369 	destlen = min_t(unsigned long, destlen, PAGE_SIZE);
370 	bytes_left = destlen;
371 
372 	workspace->strm.next_in = data_in;
373 	workspace->strm.avail_in = srclen;
374 	workspace->strm.total_in = 0;
375 
376 	workspace->strm.next_out = workspace->buf;
377 	workspace->strm.avail_out = workspace->buf_size;
378 	workspace->strm.total_out = 0;
379 	/* If it's deflate, and it's got no preset dictionary, then
380 	   we can tell zlib to skip the adler32 check. */
381 	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
382 	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
383 	    !(((data_in[0]<<8) + data_in[1]) % 31)) {
384 
385 		wbits = -((data_in[0] >> 4) + 8);
386 		workspace->strm.next_in += 2;
387 		workspace->strm.avail_in -= 2;
388 	}
389 
390 	if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
391 		pr_warn("BTRFS: inflateInit failed\n");
392 		return -EIO;
393 	}
394 
395 	while (bytes_left > 0) {
396 		unsigned long buf_start;
397 		unsigned long buf_offset;
398 		unsigned long bytes;
399 
400 		ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
401 		if (ret != Z_OK && ret != Z_STREAM_END)
402 			break;
403 
404 		buf_start = total_out;
405 		total_out = workspace->strm.total_out;
406 
407 		if (total_out == buf_start) {
408 			ret = -EIO;
409 			break;
410 		}
411 
412 		if (total_out <= start_byte)
413 			goto next;
414 
415 		if (total_out > start_byte && buf_start < start_byte)
416 			buf_offset = start_byte - buf_start;
417 		else
418 			buf_offset = 0;
419 
420 		bytes = min(PAGE_SIZE - pg_offset,
421 			    PAGE_SIZE - (buf_offset % PAGE_SIZE));
422 		bytes = min(bytes, bytes_left);
423 
424 		memcpy_to_page(dest_page, pg_offset,
425 			       workspace->buf + buf_offset, bytes);
426 
427 		pg_offset += bytes;
428 		bytes_left -= bytes;
429 next:
430 		workspace->strm.next_out = workspace->buf;
431 		workspace->strm.avail_out = workspace->buf_size;
432 	}
433 
434 	if (ret != Z_STREAM_END && bytes_left != 0)
435 		ret = -EIO;
436 	else
437 		ret = 0;
438 
439 	zlib_inflateEnd(&workspace->strm);
440 
441 	/*
442 	 * this should only happen if zlib returned fewer bytes than we
443 	 * expected.  btrfs_get_block is responsible for zeroing from the
444 	 * end of the inline extent (destlen) to the end of the page
445 	 */
446 	if (pg_offset < destlen) {
447 		memzero_page(dest_page, pg_offset, destlen - pg_offset);
448 	}
449 	return ret;
450 }
451 
452 const struct btrfs_compress_op btrfs_zlib_compress = {
453 	.workspace_manager	= &wsm,
454 	.max_level		= 9,
455 	.default_level		= BTRFS_ZLIB_DEFAULT_LEVEL,
456 };
457