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lzo.c
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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 
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 
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);
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 
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 
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 
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 
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) /
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 
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 
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 
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 };