• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * Copyright (C) 2008 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18 
19 #include <linux/kernel.h>
20 #include <linux/slab.h>
21 #include <linux/vmalloc.h>
22 #include <linux/init.h>
23 #include <linux/err.h>
24 #include <linux/sched.h>
25 #include <linux/pagemap.h>
26 #include <linux/bio.h>
27 #include <linux/lzo.h>
28 #include "compression.h"
29 
30 #define LZO_LEN	4
31 
32 struct workspace {
33 	void *mem;
34 	void *buf;	/* where compressed data goes */
35 	void *cbuf;	/* where decompressed data goes */
36 	struct list_head list;
37 };
38 
lzo_free_workspace(struct list_head * ws)39 static void lzo_free_workspace(struct list_head *ws)
40 {
41 	struct workspace *workspace = list_entry(ws, struct workspace, list);
42 
43 	vfree(workspace->buf);
44 	vfree(workspace->cbuf);
45 	vfree(workspace->mem);
46 	kfree(workspace);
47 }
48 
lzo_alloc_workspace(void)49 static struct list_head *lzo_alloc_workspace(void)
50 {
51 	struct workspace *workspace;
52 
53 	workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
54 	if (!workspace)
55 		return ERR_PTR(-ENOMEM);
56 
57 	workspace->mem = vmalloc(LZO1X_MEM_COMPRESS);
58 	workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));
59 	workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));
60 	if (!workspace->mem || !workspace->buf || !workspace->cbuf)
61 		goto fail;
62 
63 	INIT_LIST_HEAD(&workspace->list);
64 
65 	return &workspace->list;
66 fail:
67 	lzo_free_workspace(&workspace->list);
68 	return ERR_PTR(-ENOMEM);
69 }
70 
write_compress_length(char * buf,size_t len)71 static inline void write_compress_length(char *buf, size_t len)
72 {
73 	__le32 dlen;
74 
75 	dlen = cpu_to_le32(len);
76 	memcpy(buf, &dlen, LZO_LEN);
77 }
78 
read_compress_length(char * buf)79 static inline size_t read_compress_length(char *buf)
80 {
81 	__le32 dlen;
82 
83 	memcpy(&dlen, buf, LZO_LEN);
84 	return le32_to_cpu(dlen);
85 }
86 
lzo_compress_pages(struct list_head * ws,struct address_space * mapping,u64 start,unsigned long len,struct page ** pages,unsigned long nr_dest_pages,unsigned long * out_pages,unsigned long * total_in,unsigned long * total_out,unsigned long max_out)87 static int lzo_compress_pages(struct list_head *ws,
88 			      struct address_space *mapping,
89 			      u64 start, unsigned long len,
90 			      struct page **pages,
91 			      unsigned long nr_dest_pages,
92 			      unsigned long *out_pages,
93 			      unsigned long *total_in,
94 			      unsigned long *total_out,
95 			      unsigned long max_out)
96 {
97 	struct workspace *workspace = list_entry(ws, struct workspace, list);
98 	int ret = 0;
99 	char *data_in;
100 	char *cpage_out;
101 	int nr_pages = 0;
102 	struct page *in_page = NULL;
103 	struct page *out_page = NULL;
104 	unsigned long bytes_left;
105 
106 	size_t in_len;
107 	size_t out_len;
108 	char *buf;
109 	unsigned long tot_in = 0;
110 	unsigned long tot_out = 0;
111 	unsigned long pg_bytes_left;
112 	unsigned long out_offset;
113 	unsigned long bytes;
114 
115 	*out_pages = 0;
116 	*total_out = 0;
117 	*total_in = 0;
118 
119 	in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
120 	data_in = kmap(in_page);
121 
122 	/*
123 	 * store the size of all chunks of compressed data in
124 	 * the first 4 bytes
125 	 */
126 	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
127 	if (out_page == NULL) {
128 		ret = -ENOMEM;
129 		goto out;
130 	}
131 	cpage_out = kmap(out_page);
132 	out_offset = LZO_LEN;
133 	tot_out = LZO_LEN;
134 	pages[0] = out_page;
135 	nr_pages = 1;
136 	pg_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
137 
138 	/* compress at most one page of data each time */
139 	in_len = min(len, PAGE_CACHE_SIZE);
140 	while (tot_in < len) {
141 		ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
142 				       &out_len, workspace->mem);
143 		if (ret != LZO_E_OK) {
144 			printk(KERN_DEBUG "btrfs deflate in loop returned %d\n",
145 			       ret);
146 			ret = -1;
147 			goto out;
148 		}
149 
150 		/* store the size of this chunk of compressed data */
151 		write_compress_length(cpage_out + out_offset, out_len);
152 		tot_out += LZO_LEN;
153 		out_offset += LZO_LEN;
154 		pg_bytes_left -= LZO_LEN;
155 
156 		tot_in += in_len;
157 		tot_out += out_len;
158 
159 		/* copy bytes from the working buffer into the pages */
160 		buf = workspace->cbuf;
161 		while (out_len) {
162 			bytes = min_t(unsigned long, pg_bytes_left, out_len);
163 
164 			memcpy(cpage_out + out_offset, buf, bytes);
165 
166 			out_len -= bytes;
167 			pg_bytes_left -= bytes;
168 			buf += bytes;
169 			out_offset += bytes;
170 
171 			/*
172 			 * we need another page for writing out.
173 			 *
174 			 * Note if there's less than 4 bytes left, we just
175 			 * skip to a new page.
176 			 */
177 			if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
178 			    pg_bytes_left == 0) {
179 				if (pg_bytes_left) {
180 					memset(cpage_out + out_offset, 0,
181 					       pg_bytes_left);
182 					tot_out += pg_bytes_left;
183 				}
184 
185 				/* we're done, don't allocate new page */
186 				if (out_len == 0 && tot_in >= len)
187 					break;
188 
189 				kunmap(out_page);
190 				if (nr_pages == nr_dest_pages) {
191 					out_page = NULL;
192 					ret = -1;
193 					goto out;
194 				}
195 
196 				out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
197 				if (out_page == NULL) {
198 					ret = -ENOMEM;
199 					goto out;
200 				}
201 				cpage_out = kmap(out_page);
202 				pages[nr_pages++] = out_page;
203 
204 				pg_bytes_left = PAGE_CACHE_SIZE;
205 				out_offset = 0;
206 			}
207 		}
208 
209 		/* we're making it bigger, give up */
210 		if (tot_in > 8192 && tot_in < tot_out)
211 			goto out;
212 
213 		/* we're all done */
214 		if (tot_in >= len)
215 			break;
216 
217 		if (tot_out > max_out)
218 			break;
219 
220 		bytes_left = len - tot_in;
221 		kunmap(in_page);
222 		page_cache_release(in_page);
223 
224 		start += PAGE_CACHE_SIZE;
225 		in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
226 		data_in = kmap(in_page);
227 		in_len = min(bytes_left, PAGE_CACHE_SIZE);
228 	}
229 
230 	if (tot_out > tot_in)
231 		goto out;
232 
233 	/* store the size of all chunks of compressed data */
234 	cpage_out = kmap(pages[0]);
235 	write_compress_length(cpage_out, tot_out);
236 
237 	kunmap(pages[0]);
238 
239 	ret = 0;
240 	*total_out = tot_out;
241 	*total_in = tot_in;
242 out:
243 	*out_pages = nr_pages;
244 	if (out_page)
245 		kunmap(out_page);
246 
247 	if (in_page) {
248 		kunmap(in_page);
249 		page_cache_release(in_page);
250 	}
251 
252 	return ret;
253 }
254 
lzo_decompress_biovec(struct list_head * ws,struct page ** pages_in,u64 disk_start,struct bio_vec * bvec,int vcnt,size_t srclen)255 static int lzo_decompress_biovec(struct list_head *ws,
256 				 struct page **pages_in,
257 				 u64 disk_start,
258 				 struct bio_vec *bvec,
259 				 int vcnt,
260 				 size_t srclen)
261 {
262 	struct workspace *workspace = list_entry(ws, struct workspace, list);
263 	int ret = 0, ret2;
264 	char *data_in;
265 	unsigned long page_in_index = 0;
266 	unsigned long page_out_index = 0;
267 	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
268 					PAGE_CACHE_SIZE;
269 	unsigned long buf_start;
270 	unsigned long buf_offset = 0;
271 	unsigned long bytes;
272 	unsigned long working_bytes;
273 	unsigned long pg_offset;
274 
275 	size_t in_len;
276 	size_t out_len;
277 	unsigned long in_offset;
278 	unsigned long in_page_bytes_left;
279 	unsigned long tot_in;
280 	unsigned long tot_out;
281 	unsigned long tot_len;
282 	char *buf;
283 	bool may_late_unmap, need_unmap;
284 
285 	data_in = kmap(pages_in[0]);
286 	tot_len = read_compress_length(data_in);
287 
288 	tot_in = LZO_LEN;
289 	in_offset = LZO_LEN;
290 	tot_len = min_t(size_t, srclen, tot_len);
291 	in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
292 
293 	tot_out = 0;
294 	pg_offset = 0;
295 
296 	while (tot_in < tot_len) {
297 		in_len = read_compress_length(data_in + in_offset);
298 		in_page_bytes_left -= LZO_LEN;
299 		in_offset += LZO_LEN;
300 		tot_in += LZO_LEN;
301 
302 		tot_in += in_len;
303 		working_bytes = in_len;
304 		may_late_unmap = need_unmap = false;
305 
306 		/* fast path: avoid using the working buffer */
307 		if (in_page_bytes_left >= in_len) {
308 			buf = data_in + in_offset;
309 			bytes = in_len;
310 			may_late_unmap = true;
311 			goto cont;
312 		}
313 
314 		/* copy bytes from the pages into the working buffer */
315 		buf = workspace->cbuf;
316 		buf_offset = 0;
317 		while (working_bytes) {
318 			bytes = min(working_bytes, in_page_bytes_left);
319 
320 			memcpy(buf + buf_offset, data_in + in_offset, bytes);
321 			buf_offset += bytes;
322 cont:
323 			working_bytes -= bytes;
324 			in_page_bytes_left -= bytes;
325 			in_offset += bytes;
326 
327 			/* check if we need to pick another page */
328 			if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
329 			    || in_page_bytes_left == 0) {
330 				tot_in += in_page_bytes_left;
331 
332 				if (working_bytes == 0 && tot_in >= tot_len)
333 					break;
334 
335 				if (page_in_index + 1 >= total_pages_in) {
336 					ret = -1;
337 					goto done;
338 				}
339 
340 				if (may_late_unmap)
341 					need_unmap = true;
342 				else
343 					kunmap(pages_in[page_in_index]);
344 
345 				data_in = kmap(pages_in[++page_in_index]);
346 
347 				in_page_bytes_left = PAGE_CACHE_SIZE;
348 				in_offset = 0;
349 			}
350 		}
351 
352 		out_len = lzo1x_worst_compress(PAGE_CACHE_SIZE);
353 		ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
354 					    &out_len);
355 		if (need_unmap)
356 			kunmap(pages_in[page_in_index - 1]);
357 		if (ret != LZO_E_OK) {
358 			printk(KERN_WARNING "btrfs decompress failed\n");
359 			ret = -1;
360 			break;
361 		}
362 
363 		buf_start = tot_out;
364 		tot_out += out_len;
365 
366 		ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
367 						 tot_out, disk_start,
368 						 bvec, vcnt,
369 						 &page_out_index, &pg_offset);
370 		if (ret2 == 0)
371 			break;
372 	}
373 done:
374 	kunmap(pages_in[page_in_index]);
375 	return ret;
376 }
377 
lzo_decompress(struct list_head * ws,unsigned char * data_in,struct page * dest_page,unsigned long start_byte,size_t srclen,size_t destlen)378 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
379 			  struct page *dest_page,
380 			  unsigned long start_byte,
381 			  size_t srclen, size_t destlen)
382 {
383 	struct workspace *workspace = list_entry(ws, struct workspace, list);
384 	size_t in_len;
385 	size_t out_len;
386 	size_t tot_len;
387 	int ret = 0;
388 	char *kaddr;
389 	unsigned long bytes;
390 
391 	BUG_ON(srclen < LZO_LEN);
392 
393 	tot_len = read_compress_length(data_in);
394 	data_in += LZO_LEN;
395 
396 	in_len = read_compress_length(data_in);
397 	data_in += LZO_LEN;
398 
399 	out_len = PAGE_CACHE_SIZE;
400 	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
401 	if (ret != LZO_E_OK) {
402 		printk(KERN_WARNING "btrfs decompress failed!\n");
403 		ret = -1;
404 		goto out;
405 	}
406 
407 	if (out_len < start_byte) {
408 		ret = -1;
409 		goto out;
410 	}
411 
412 	bytes = min_t(unsigned long, destlen, out_len - start_byte);
413 
414 	kaddr = kmap_atomic(dest_page);
415 	memcpy(kaddr, workspace->buf + start_byte, bytes);
416 	kunmap_atomic(kaddr);
417 out:
418 	return ret;
419 }
420 
421 struct btrfs_compress_op btrfs_lzo_compress = {
422 	.alloc_workspace	= lzo_alloc_workspace,
423 	.free_workspace		= lzo_free_workspace,
424 	.compress_pages		= lzo_compress_pages,
425 	.decompress_biovec	= lzo_decompress_biovec,
426 	.decompress		= lzo_decompress,
427 };
428